Spring Security Reference

Authors

Ben Alex , Luke Taylor , Rob Winch , Gunnar Hillert , Joe Grandja , Jay Bryant , Eddú Meléndez , Josh Cummings

5.2.1.RELEASE

Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.


Table of Contents

I. Preface
1. Prerequisites
2. Spring Security Community
2.1. Getting Help
2.2. Becoming Involved
2.3. Source Code
2.4. Apache 2 License
2.5. Social Media
3. What’s New in Spring Security 5.2
3.1. Servlet
3.2. WebFlux
3.3. Core
4. Getting Spring Security
4.1. Release Numbering
4.2. Usage with Maven
4.2.1. Spring Boot with Maven
4.2.2. Maven Without Spring Boot
4.2.3. Maven Repositories
4.3. Gradle
4.3.1. Spring Boot with Gradle
4.3.2. Gradle Without Spring Boot
4.3.3. Gradle Repositories
5. Features
5.1. Protection Against Exploits
5.1.1. Cross Site Request Forgery (CSRF)
What is a CSRF Attack?
Protecting Against CSRF Attacks
When to use CSRF protection
CSRF Considerations
6. Project Modules
6.1. Core — spring-security-core.jar
6.2. Remoting — spring-security-remoting.jar
6.3. Web — spring-security-web.jar
6.4. Config — spring-security-config.jar
6.5. LDAP — spring-security-ldap.jar
6.6. OAuth 2.0 Core — spring-security-oauth2-core.jar
6.7. OAuth 2.0 Client — spring-security-oauth2-client.jar
6.8. OAuth 2.0 JOSE — spring-security-oauth2-jose.jar
6.9. OAuth 2.0 Resource Server — spring-security-oauth2-resource-server.jar
6.10. ACL — spring-security-acl.jar
6.11. CAS — spring-security-cas.jar
6.12. OpenID — spring-security-openid.jar
6.13. Test — spring-security-test.jar
7. Samples
II. Servlet Applications
8. Hello Spring Security
8.1. Hello Spring Security (Boot)
8.1.1. Updating Dependencies
8.1.2. Starting Hello Spring Security Boot
8.1.3. Spring Boot Auto Configuration
8.2. Hello Spring Security (Java Configuration)
8.2.1. Updating Dependencies
8.2.2. Minimal @EnableWebSecurity Configuration
8.2.3. Using AbstractSecurityWebApplicationInitializer
8.3. Hello Spring Security (XML)
8.3.1. Updating Dependencies
8.3.2. Minimal <http> Configuration
8.3.3. web.xml Configuration
9. Architecture and Implementation
9.1. Technical Overview
9.1.1. Runtime Environment
9.1.2. Core Components
SecurityContextHolder, SecurityContext and Authentication Objects
The UserDetailsService
GrantedAuthority
Summary
9.1.3. Authentication
What is authentication in Spring Security?
Setting the SecurityContextHolder Contents Directly
9.1.4. Authentication in a Web Application
ExceptionTranslationFilter
AuthenticationEntryPoint
Authentication Mechanism
Storing the SecurityContext between requests
9.1.5. Access-Control (Authorization) in Spring Security
Security and AOP Advice
Secure Objects and the AbstractSecurityInterceptor
9.2. Core Services
9.2.1. The AuthenticationManager, ProviderManager and AuthenticationProvider
Erasing Credentials on Successful Authentication
DaoAuthenticationProvider
9.2.2. UserDetailsService Implementations
In-Memory Authentication
JdbcDaoImpl
10. Authentication
10.1. In-Memory Authentication
10.2. JDBC Authentication
10.3. LDAP Authentication
10.3.1. Overview
10.3.2. Using LDAP with Spring Security
10.4. Configuring an LDAP Server
10.4.1. Using an Embedded Test Server
10.4.2. Using Bind Authentication
10.4.3. Loading Authorities
10.5. Implementation Classes
10.5.1. LdapAuthenticator Implementations
Common Functionality
BindAuthenticator
PasswordComparisonAuthenticator
10.5.2. Connecting to the LDAP Server
10.5.3. LDAP Search Objects
FilterBasedLdapUserSearch
10.5.4. LdapAuthoritiesPopulator
10.5.5. Spring Bean Configuration
10.5.6. LDAP Attributes and Customized UserDetails
10.6. Active Directory Authentication
10.6.1. ActiveDirectoryLdapAuthenticationProvider
Active Directory Error Codes
10.7. LDAP Java Configuration
10.8. AuthenticationProvider
10.8.1. AuthenticationProvider Java Configuration
10.8.2. AuthenticationProvider XML Configuration
10.9. UserDetailsService
10.10. Password Encoding
10.10.1. Password History
10.10.2. DelegatingPasswordEncoder
Password Storage Format
Password Encoding
Password Matching
Getting Started Experience
Troubleshooting
10.10.3. BCryptPasswordEncoder
10.10.4. Argon2PasswordEncoder
10.10.5. Pbkdf2PasswordEncoder
10.10.6. SCryptPasswordEncoder
10.10.7. Other PasswordEncoders
10.10.8. Password Encoder XML Configuration
10.11. The Authentication Manager and the Namespace
10.12. Session Management
10.12.1. Detecting Timeouts
10.12.2. Concurrent Session Control
10.12.3. Session Fixation Attack Protection
10.12.4. SessionManagementFilter
10.12.5. SessionAuthenticationStrategy
10.12.6. Concurrency Control
Querying the SessionRegistry for currently authenticated users and their sessions
10.13. Remember-Me Authentication
10.13.1. Overview
10.13.2. Simple Hash-Based Token Approach
10.13.3. Persistent Token Approach
10.13.4. Remember-Me Interfaces and Implementations
TokenBasedRememberMeServices
PersistentTokenBasedRememberMeServices
10.14. OpenID Support
10.14.1. Attribute Exchange
10.15. Anonymous Authentication
10.15.1. Overview
10.15.2. Configuration
10.15.3. AuthenticationTrustResolver
10.16. Pre-Authentication Scenarios
10.16.1. Pre-Authentication Framework Classes
AbstractPreAuthenticatedProcessingFilter
PreAuthenticatedAuthenticationProvider
Http403ForbiddenEntryPoint
10.16.2. Concrete Implementations
Request-Header Authentication (Siteminder)
Java EE Container Authentication
10.17. Java Authentication and Authorization Service (JAAS) Provider
10.17.1. Overview
10.17.2. AbstractJaasAuthenticationProvider
JAAS CallbackHandler
JAAS AuthorityGranter
10.17.3. DefaultJaasAuthenticationProvider
InMemoryConfiguration
DefaultJaasAuthenticationProvider Example Configuration
10.17.4. JaasAuthenticationProvider
10.17.5. Running as a Subject
10.18. CAS Authentication
10.18.1. Overview
10.18.2. How CAS Works
Spring Security and CAS Interaction Sequence
10.18.3. Configuration of CAS Client
Service Ticket Authentication
Single Logout
Authenticating to a Stateless Service with CAS
Proxy Ticket Authentication
10.19. X.509 Authentication
10.19.1. Overview
10.19.2. Adding X.509 Authentication to Your Web Application
10.19.3. Setting up SSL in Tomcat
10.20. Run-As Authentication Replacement
10.20.1. Overview
10.20.2. Configuration
10.21. Form Login
10.21.1. Form Login Java Configuration
10.21.2. Form Login XML Configuration
Form and Basic Login Options
10.22. Basic and Digest Authentication
10.22.1. BasicAuthenticationFilter
10.22.2. Configuration
10.23. DigestAuthenticationFilter
10.23.1. Configuration
10.24. Handling Logouts
10.24.1. Logout Java Configuration
10.24.2. Logout XML Configuration
10.24.3. LogoutHandler
10.24.4. LogoutSuccessHandler
10.24.5. Further Logout-Related References
10.25. Setting a Custom AuthenticationEntryPoint
11. Authorization
11.1. Authorization Architecture
11.1.1. Authorities
11.1.2. Pre-Invocation Handling
The AccessDecisionManager
Voting-Based AccessDecisionManager Implementations
11.1.3. After Invocation Handling
11.1.4. Hierarchical Roles
11.2. Secure Object Implementations
11.2.1. AOP Alliance (MethodInvocation) Security Interceptor
Explicit MethodSecurityInterceptor Configuration
11.2.2. AspectJ (JoinPoint) Security Interceptor
11.3. Expression-Based Access Control
11.3.1. Overview
Common Built-In Expressions
11.3.2. Web Security Expressions
Referring to Beans in Web Security Expressions
Path Variables in Web Security Expressions
11.3.3. Method Security Expressions
@Pre and @Post Annotations
Built-In Expressions
11.4. Authorize Requests
11.5. Method Security
11.5.1. EnableGlobalMethodSecurity
11.5.2. GlobalMethodSecurityConfiguration
11.5.3. The <global-method-security> Element
11.5.4. Adding Security Pointcuts using protect-pointcut
11.6. Domain Object Security (ACLs)
11.6.1. Overview
11.6.2. Key Concepts
11.6.3. Getting Started
12. OAuth2
12.1. OAuth 2.0 Login
12.1.1. Spring Boot 2.x Sample
Initial setup
Setting the redirect URI
Configure application.yml
Boot up the application
12.1.2. Spring Boot 2.x Property Mappings
12.1.3. CommonOAuth2Provider
12.1.4. Configuring Custom Provider Properties
12.1.5. Overriding Spring Boot 2.x Auto-configuration
Register a ClientRegistrationRepository @Bean
Provide a WebSecurityConfigurerAdapter
Completely Override the Auto-configuration
12.1.6. Java Configuration without Spring Boot 2.x
12.1.7. Advanced Configuration
OAuth 2.0 Login Page
Redirection Endpoint
UserInfo Endpoint
ID Token Signature Verification
OpenID Connect 1.0 Logout
12.2. OAuth 2.0 Client
12.2.1. Core Interfaces / Classes
ClientRegistration
ClientRegistrationRepository
OAuth2AuthorizedClient
OAuth2AuthorizedClientRepository / OAuth2AuthorizedClientService
OAuth2AuthorizedClientManager / OAuth2AuthorizedClientProvider
12.2.2. Authorization Grant Support
Authorization Code
Refresh Token
Client Credentials
Resource Owner Password Credentials
12.2.3. Additional Features
Resolving an Authorized Client
12.2.4. WebClient integration for Servlet Environments
Providing the Authorized Client
Defaulting the Authorized Client
12.3. OAuth 2.0 Resource Server
12.3.1. Dependencies
12.3.2. Minimal Configuration for JWTs
Specifying the Authorization Server
Startup Expectations
Runtime Expectations
12.3.3. Specifying the Authorization Server JWK Set Uri Directly
12.3.4. Overriding or Replacing Boot Auto Configuration
Using jwkSetUri()
Using decoder()
Exposing a JwtDecoder @Bean
12.3.5. Configuring Trusted Algorithms
Via Spring Boot
Using a Builder
From JWK Set response
12.3.6. Trusting a Single Asymmetric Key
Via Spring Boot
Using a Builder
12.3.7. Trusting a Single Symmetric Key
12.3.8. Configuring Authorization
Extracting Authorities Manually
12.3.9. Configuring Validation
Customizing Timestamp Validation
Configuring a Custom Validator
12.3.10. Configuring Claim Set Mapping
Customizing the Conversion of a Single Claim
Adding a Claim
Removing a Claim
Renaming a Claim
12.3.11. Configuring Timeouts
12.3.12. Minimal Configuration for Introspection
Specifying the Authorization Server
Startup Expectations
Runtime Expectations
12.3.13. Looking Up Attributes Post-Authentication
Looking Up Attributes Via SpEL
12.3.14. Overriding or Replacing Boot Auto Configuration
Using introspectionUri()
Using introspector()
Exposing a OpaqueTokenIntrospector @Bean
12.3.15. Configuring Authorization
Extracting Authorities Manually
12.3.16. Configuring Timeouts
12.3.17. Using Introspection with JWTs
12.3.18. Calling a /userinfo Endpoint
12.3.19. Supporting both JWT and Opaque Token
12.3.20. Multi-tenancy
Resolving the Tenant By Request Material
Resolving the Tenant By Claim
Parsing the Claim Only Once
12.3.21. Bearer Token Resolution
Reading the Bearer Token from a Custom Header
Reading the Bearer Token from a Form Parameter
12.3.22. Bearer Token Propagation
RestTemplate support
13. SAML2
13.1. SAML 2.0 Login
13.1.1. SAML 2 Support in Spring Security
13.1.2. Saml 2 Login - High Level Concepts
13.1.3. Saml 2 Login - Current Feature Set
Saml 2 Login - Not Yet Supported
13.1.4. Saml 2 Login - Introduction to Java Configuration
RelyingPartyRegistration
Service Provider Metadata
Authentication Requests - SP Initiated Flow
13.1.5. Spring Boot 2.x Sample
Multiple Identity Provider Sample
14. Protection Against Exploits
14.1. Cross Site Request Forgery (CSRF) for Servlet Environments
14.1.1. Using Spring Security CSRF Protection
Use proper HTTP verbs
Configure CSRF Protection
Include the CSRF Token
14.1.2. CSRF Considerations
Logging In
Logging Out
CSRF and Session Timeouts
Multipart (file upload)
HiddenHttpMethodFilter
14.2. Security HTTP Response Headers
14.2.1. Default Security Headers
14.2.2. Cache Control
14.2.3. Content Type Options
14.2.4. HTTP Strict Transport Security (HSTS)
14.2.5. HTTP Public Key Pinning (HPKP)
14.2.6. X-Frame-Options
14.2.7. X-XSS-Protection
14.2.8. Content Security Policy (CSP)
Configuring Content Security Policy
Additional Resources
14.2.9. Referrer Policy
Configuring Referrer Policy
14.2.10. Feature Policy
Configuring Feature Policy
14.2.11. Clear Site Data
Configuring Clear Site Data
14.2.12. Custom Headers
Static Headers
Headers Writer
DelegatingRequestMatcherHeaderWriter
14.3. HTTPS
14.3.1. Adding HTTP/HTTPS Channel Security
15. Integrations
15.1. Servlet API integration
15.1.1. Servlet 2.5+ Integration
HttpServletRequest.getRemoteUser()
HttpServletRequest.getUserPrincipal()
HttpServletRequest.isUserInRole(String)
15.1.2. Servlet 3+ Integration
HttpServletRequest.authenticate(HttpServletRequest,HttpServletResponse)
HttpServletRequest.login(String,String)
HttpServletRequest.logout()
AsyncContext.start(Runnable)
Async Servlet Support
15.1.3. Servlet 3.1+ Integration
HttpServletRequest#changeSessionId()
15.2. Spring Data Integration
15.2.1. Spring Data & Spring Security Configuration
15.2.2. Security Expressions within @Query
15.3. Concurrency Support
15.3.1. DelegatingSecurityContextRunnable
15.3.2. DelegatingSecurityContextExecutor
15.3.3. Spring Security Concurrency Classes
15.4. Jackson Support
15.5. Localization
15.6. Spring MVC Integration
15.6.1. @EnableWebMvcSecurity
15.6.2. MvcRequestMatcher
15.6.3. @AuthenticationPrincipal
15.6.4. Spring MVC Async Integration
15.6.5. Spring MVC and CSRF Integration
Automatic Token Inclusion
Resolving the CsrfToken
15.7. WebSocket Security
15.7.1. WebSocket Configuration
15.7.2. WebSocket Authentication
15.7.3. WebSocket Authorization
WebSocket Authorization Notes
Outbound Messages
15.7.4. Enforcing Same Origin Policy
Why Same Origin?
Spring WebSocket Allowed Origin
Adding CSRF to Stomp Headers
Disable CSRF within WebSockets
15.7.5. Working with SockJS
SockJS & frame-options
SockJS & Relaxing CSRF
15.8. CORS
15.9. JSP Tag Libraries
15.9.1. Declaring the Taglib
15.9.2. The authorize Tag
Disabling Tag Authorization for Testing
15.9.3. The authentication Tag
15.9.4. The accesscontrollist Tag
15.9.5. The csrfInput Tag
15.9.6. The csrfMetaTags Tag
16. Java Configuration
16.1. Hello Web Security Java Configuration
16.1.1. AbstractSecurityWebApplicationInitializer
16.1.2. AbstractSecurityWebApplicationInitializer without Existing Spring
16.1.3. AbstractSecurityWebApplicationInitializer with Spring MVC
16.2. HttpSecurity
16.3. Multiple HttpSecurity
16.4. Custom DSLs
16.5. Post Processing Configured Objects
17. Security Namespace Configuration
17.1. Introduction
17.1.1. Design of the Namespace
17.2. Getting Started with Security Namespace Configuration
17.2.1. web.xml Configuration
17.2.2. A Minimal <http> Configuration
Setting a Default Post-Login Destination
17.3. Advanced Web Features
17.3.1. Adding in Your Own Filters
17.4. Method Security
17.5. The Default AccessDecisionManager
17.5.1. Customizing the AccessDecisionManager
18. Testing
18.1. Testing Method Security
18.1.1. Security Test Setup
18.1.2. @WithMockUser
18.1.3. @WithAnonymousUser
18.1.4. @WithUserDetails
18.1.5. @WithSecurityContext
18.1.6. Test Meta Annotations
18.2. Spring MVC Test Integration
18.2.1. Setting Up MockMvc and Spring Security
18.2.2. SecurityMockMvcRequestPostProcessors
Testing with CSRF Protection
Running a Test as a User in Spring MVC Test
Running as a User in Spring MVC Test with RequestPostProcessor
Testing HTTP Basic Authentication
18.2.3. SecurityMockMvcRequestBuilders
Testing Form Based Authentication
Testing Bearer Authentication
Testing Logout
18.2.4. SecurityMockMvcResultMatchers
Unauthenticated Assertion
Authenticated Assertion
19. Spring Security Crypto Module
19.1. Introduction
19.2. Encryptors
19.2.1. BytesEncryptor
19.2.2. TextEncryptor
19.3. Key Generators
19.3.1. BytesKeyGenerator
19.3.2. StringKeyGenerator
19.4. Password Encoding
20. Appendix
20.1. Security Database Schema
20.1.1. User Schema
For Oracle database
Group Authorities
20.1.2. Persistent Login (Remember-Me) Schema
20.1.3. ACL Schema
HyperSQL
PostgreSQL
MySQL and MariaDB
Microsoft SQL Server
Oracle Database
20.2. The Security Namespace
20.2.1. Web Application Security
<debug>
<http>
<access-denied-handler>
<cors>
<headers>
<cache-control>
<hsts>
<hpkp>
<pins>
<pin>
<content-security-policy>
<referrer-policy>
<feature-policy>
<frame-options>
<xss-protection>
<content-type-options>
<header>
<anonymous>
<csrf>
<custom-filter>
<expression-handler>
<form-login>
<http-basic>
<http-firewall> Element
<intercept-url>
<jee>
<logout>
<openid-login>
<attribute-exchange>
<openid-attribute>
<port-mappings>
<port-mapping>
<remember-me>
<request-cache> Element
<session-management>
<concurrency-control>
<x509>
<filter-chain-map>
<filter-chain>
<filter-security-metadata-source>
20.2.2. WebSocket Security
<websocket-message-broker>
<intercept-message>
20.2.3. Authentication Services
<authentication-manager>
<authentication-provider>
<jdbc-user-service>
<password-encoder>
<user-service>
<user>
20.2.4. Method Security
<global-method-security>
<after-invocation-provider>
<pre-post-annotation-handling>
<invocation-attribute-factory>
<post-invocation-advice>
<pre-invocation-advice>
Securing Methods using
<intercept-methods>
<method-security-metadata-source>
<protect>
20.2.5. LDAP Namespace Options
Defining the LDAP Server using the
<ldap-authentication-provider>
<password-compare>
<ldap-user-service>
20.3. Spring Security Dependencies
20.3.1. spring-security-core
20.3.2. spring-security-remoting
20.3.3. spring-security-web
20.3.4. spring-security-ldap
20.3.5. spring-security-config
20.3.6. spring-security-acl
20.3.7. spring-security-cas
20.3.8. spring-security-openid
20.3.9. spring-security-taglibs
20.4. Proxy Server Configuration
20.5. Spring Security FAQ
20.5.1. General Questions
Will Spring Security take care of all my application security requirements?
Why not just use web.xml security?
What Java and Spring Framework versions are required?
I’m new to Spring Security and I need to build an application that supports CAS single sign-on over HTTPS, while allowing Basic authentication locally for certain URLs, authenticating against multiple back end user information sources (LDAP and JDBC). I’ve copied some configuration files I found but it doesn’t work.
20.5.2. Common Problems
When I try to log in, I get an error message that says "Bad Credentials". What’s wrong?
My application goes into an "endless loop" when I try to login, what’s going on?
I get an exception with the message "Access is denied (user is anonymous);". What’s wrong?
Why can I still see a secured page even after I’ve logged out of my application?
I get an exception with the message "An Authentication object was not found in the SecurityContext". What’s wrong?
I can’t get LDAP authentication to work.
Session Management
I’m using Spring Security’s concurrent session control to prevent users from logging in more than once at a time.
Why does the session Id change when I authenticate through Spring Security?
I’m using Tomcat (or some other servlet container) and have enabled HTTPS for my login page, switching back to HTTP afterwards.
I’m not switching between HTTP and HTTPS but my session is still getting lost
I’m trying to use the concurrent session-control support but it won’t let me log back in, even if I’m sure I’ve logged out and haven’t exceeded the allowed sessions.
Spring Security is creating a session somewhere, even though I’ve configured it not to, by setting the create-session attribute to never.
I get a 403 Forbidden when performing a POST
I’m forwarding a request to another URL using the RequestDispatcher, but my security constraints aren’t being applied.
I have added Spring Security’s <global-method-security> element to my application context but if I add security annotations to my Spring MVC controller beans (Struts actions etc.) then they don’t seem to have an effect.
I have a user who has definitely been authenticated, but when I try to access the SecurityContextHolder during some requests, the Authentication is null.
The authorize JSP Tag doesn’t respect my method security annotations when using the URL attribute.
20.5.3. Spring Security Architecture Questions
How do I know which package class X is in?
How do the namespace elements map to conventional bean configurations?
What does "ROLE_" mean and why do I need it on my role names?
How do I know which dependencies to add to my application to work with Spring Security?
What dependencies are needed to run an embedded ApacheDS LDAP server?
What is a UserDetailsService and do I need one?
20.5.4. Common "Howto" Requests
I need to login in with more information than just the username.
How do I apply different intercept-url constraints where only the fragment value of the requested URLs differs (e.g./foo#bar and /foo#blah?
How do I access the user’s IP Address (or other web-request data) in a UserDetailsService?
How do I access the HttpSession from a UserDetailsService?
How do I access the user’s password in a UserDetailsService?
How do I define the secured URLs within an application dynamically?
How do I authenticate against LDAP but load user roles from a database?
I want to modify the property of a bean that is created by the namespace, but there is nothing in the schema to support it.
III. Reactive Applications
21. WebFlux Security
21.1. Minimal WebFlux Security Configuration
21.2. Explicit WebFlux Security Configuration
22. Protection Against Exploits
22.1. Cross Site Request Forgery (CSRF) for WebFlux Environments
22.1.1. Using Spring Security CSRF Protection
Use proper HTTP verbs
Configure CSRF Protection
Include the CSRF Token
22.1.2. CSRF Considerations
Logging In
Logging Out
CSRF and Session Timeouts
Multipart (file upload)
HiddenHttpMethodFilter
22.2. Security HTTP Response Headers
22.2.1. Default Security Headers
22.2.2. Cache Control
22.2.3. Content Type Options
22.2.4. HTTP Strict Transport Security (HSTS)
22.2.5. X-Frame-Options
22.2.6. X-XSS-Protection
22.2.7. Content Security Policy (CSP)
Configuring Content Security Policy
Additional Resources
22.2.8. Referrer Policy
Configuring Referrer Policy
22.2.9. Feature Policy
Configuring Feature Policy
22.2.10. Clear Site Data
Configuring Clear Site Data
22.3. Redirect to HTTPS
23. OAuth2 WebFlux
23.1. OAuth 2.0 Login
23.1.1. Spring Boot 2.0 Sample
Initial setup
Setting the redirect URI
Configure application.yml
Boot up the application
23.1.2. Using OpenID Provider Configuration
23.1.3. Explicit OAuth2 Login Configuration
23.2. OAuth2 Client
23.3. OAuth 2.0 Resource Server
23.3.1. Dependencies
23.3.2. Minimal Configuration for JWTs
Specifying the Authorization Server
Startup Expectations
Runtime Expectations
Specifying the Authorization Server JWK Set Uri Directly
Overriding or Replacing Boot Auto Configuration
23.3.3. Configuring Trusted Algorithms
Via Spring Boot
Using a Builder
Trusting a Single Asymmetric Key
Trusting a Single Symmetric Key
Configuring Authorization
Configuring Validation
Minimal Configuration for Introspection
Looking Up Attributes Post-Authentication
Overriding or Replacing Boot Auto Configuration
Configuring Authorization
Using Introspection with JWTs
Calling a /userinfo Endpoint
23.3.4. Bearer Token Propagation
24. @RegisteredOAuth2AuthorizedClient
25. Reactive X.509 Authentication
26. WebClient
26.1. WebClient OAuth2 Setup
26.2. Implicit OAuth2AuthorizedClient
26.3. Explicit OAuth2AuthorizedClient
26.4. clientRegistrationId
27. EnableReactiveMethodSecurity
28. Reactive Test Support
28.1. Testing Reactive Method Security
28.2. WebTestClientSupport
28.2.1. Authentication
28.2.2. CSRF Support
28.2.3. Testing Bearer Authentication
mockJwt() WebTestClientConfigurer
authentication() WebTestClientConfigurer
29. RSocket Security
29.1. Minimal RSocket Security Configuration
29.2. Adding SecuritySocketAcceptorInterceptor
29.3. RSocket Authentication
29.3.1. Authentication at Setup vs Request Time
29.3.2. Basic Authentication
29.3.3. JWT
29.4. RSocket Authorization

Spring Security is a framework that provides authentication, authorization, and protection against common attacks. With first class support for both imperative and reactive applications, it is the de-facto standard for securing Spring-based applications.

Part I. Preface

This section discusses the logistics of Spring Security.

1. Prerequisites

Spring Security requires a Java 8 or higher Runtime Environment.

As Spring Security aims to operate in a self-contained manner, you do not need to place any special configuration files in your Java Runtime Environment. In particular, you need not configure a special Java Authentication and Authorization Service (JAAS) policy file or place Spring Security into common classpath locations.

Similarly, if you use an EJB Container or Servlet Container, you need not put any special configuration files anywhere nor include Spring Security in a server classloader. All the required files are contained within your application.

This design offers maximum deployment time flexibility, as you can copy your target artifact (be it a JAR, WAR, or EAR) from one system to another and it immediately works.

2. Spring Security Community

Welcome to the Spring Security Community! This section discusses how you can make the most of our vast community.

2.1 Getting Help

If you need help with Spring Security, we are here to help. The following are some of the best ways to get help:

2.2 Becoming Involved

We welcome your involvement in the Spring Security project. There are many ways to contribute, including answering questions on StackOverflow, writing new code, improving existing code, assisting with documentation, developing samples or tutorials, reporting bugs, or simply making suggestions. For more information, see our Contributing documentation.

2.3 Source Code

You can find Spring Security’s source code on GitHub at https://github.com/spring-projects/spring-security/

2.4 Apache 2 License

Spring Security is Open Source software released under the Apache 2.0 license.

2.5 Social Media

You can follow @SpringSecurity and the Spring Security team on Twitter to stay up to date with the latest news. You can also follow @SpringCentral to keep up to date with the entire Spring portfolio.

3. What’s New in Spring Security 5.2

Spring Security 5.2 provides a number of new features. Below are the highlights of the release.

3.1 Servlet

3.2 WebFlux

3.3 Core

4. Getting Spring Security

This section discusses all you need to know about getting the Spring Security binaries. See Section 2.3, “Source Code” for how to obtain the source code.

4.1 Release Numbering

Spring Security versions are formatted as MAJOR.MINOR.PATCH such that:

  • MAJOR versions may contain breaking changes. Typically, these are done to provide improved security to match modern security practices.
  • MINOR versions contain enhancements but are considered passive updates
  • PATCH level should be perfectly compatible, forwards and backwards, with the possible exception of changes that fix bugs.

4.2 Usage with Maven

As most open source projects, Spring Security deploys its dependencies as Maven artifacts. The topics in this section provide detail on how to consume Spring Security when using Maven.

4.2.1 Spring Boot with Maven

Spring Boot provides a spring-boot-starter-security starter that aggregates Spring Security-related dependencies together. The simplest and preferred way to use the starter is to use Spring Initializr by using an IDE integration (Eclipse, IntelliJ, NetBeans) or through https://start.spring.io.

Alternatively, you can manually add the starter, as the following example shows:

Example 4.1. pom.xml

<dependencies>
    <!-- ... other dependency elements ... -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
</dependencies>

Since Spring Boot provides a Maven BOM to manage dependency versions, you do not need to specify a version. If you wish to override the Spring Security version, you may do so by providing a Maven property, as the following example shows:

Example 4.2. pom.xml

<properties>
    <!-- ... -->
    <spring-security.version>5.2.1.RELEASE</spring-security.version>
</dependencies>

Since Spring Security makes breaking changes only in major releases, it is safe to use a newer version of Spring Security with Spring Boot. However, at times, you may need to update the version of Spring Framework as well. You can do so by adding a Maven property, as the following example shows:

Example 4.3. pom.xml

<properties>
    <!-- ... -->
    <spring.version>5.2.1.RELEASE</spring.version>
</dependencies>

If you use additional features (such as LDAP, OpenID, and others), you need to also include the appropriate Chapter 6, Project Modules.

4.2.2 Maven Without Spring Boot

When you use Spring Security without Spring Boot, the preferred way is to use Spring Security’s BOM to ensure a consistent version of Spring Security is used throughout the entire project. The following example shows how to do so:

Example 4.4. pom.xml

<dependencyManagement>
    <dependencies>
        <!-- ... other dependency elements ... -->
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-bom</artifactId>
            <version>5.2.1.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

A minimal Spring Security Maven set of dependencies typically looks like the following:

Example 4.5. pom.xml

<dependencies>
    <!-- ... other dependency elements ... -->
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-config</artifactId>
    </dependency>
</dependencies>

If you use additional features (such as LDAP, OpenID, and others), you need to also include the appropriate Chapter 6, Project Modules.

Spring Security builds against Spring Framework 5.2.1.RELEASE but should generally work with any newer version of Spring Framework 5.x. Many users are likely to run afoul of the fact that Spring Security’s transitive dependencies resolve Spring Framework 5.2.1.RELEASE, which can cause strange classpath problems. The easiest way to resolve this is to use the spring-framework-bom within the <dependencyManagement> section of your pom.xml as the following example shows:

Example 4.6. pom.xml

<dependencyManagement>
    <dependencies>
        <!-- ... other dependency elements ... -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-framework-bom</artifactId>
            <version>5.2.1.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

The preceding example ensures that all the transitive dependencies of Spring Security use the Spring 5.2.1.RELEASE modules.

[Note]Note

This approach uses Maven’s “bill of materials” (BOM) concept and is only available in Maven 2.0.9+. For additional details about how dependencies are resolved, see Maven’s Introduction to the Dependency Mechanism documentation.

4.2.3 Maven Repositories

All GA releases (that is, versions ending in .RELEASE) are deployed to Maven Central, so no additional Maven repositories need to be declared in your pom.

If you use a SNAPSHOT version, you need to ensure that you have the Spring Snapshot repository defined, as the following example shows:

Example 4.7. pom.xml

<repositories>
    <!-- ... possibly other repository elements ... -->
    <repository>
        <id>spring-snapshot</id>
        <name>Spring Snapshot Repository</name>
        <url>https://repo.spring.io/snapshot</url>
    </repository>
</repositories>

If you use a milestone or release candidate version, you need to ensure that you have the Spring Milestone repository defined, as the following example shows:

Example 4.8. pom.xml

<repositories>
    <!-- ... possibly other repository elements ... -->
    <repository>
        <id>spring-milestone</id>
        <name>Spring Milestone Repository</name>
        <url>https://repo.spring.io/milestone</url>
    </repository>
</repositories>

4.3 Gradle

As most open source projects, Spring Security deploys its dependencies as Maven artifacts, which allows for for first-class Gradle support. The following topics provide detail on how to consume Spring Security when using Gradle.

4.3.1 Spring Boot with Gradle

Spring Boot provides a spring-boot-starter-security starter that aggregates Spring Security related dependencies together. The simplest and preferred method to use the starter is to use Spring Initializr by using an IDE integration (Eclipse, IntelliJ, NetBeans) or through https://start.spring.io.

Alternatively, you can manually add the starter, as the following example shows:

Example 4.9. build.gradle

dependencies {
    compile "org.springframework.boot:spring-boot-starter-security"
}

Since Spring Boot provides a Maven BOM to manage dependency versions, you need not specify a version. If you wish to override the Spring Security version, you may do so by providing a Gradle property, as the following example shows:

Example 4.10. build.gradle

ext['spring-security.version']='5.2.1.RELEASE'

Since Spring Security makes breaking changes only in major releases, it is safe to use a newer version of Spring Security with Spring Boot. However, at times, you may need to update the version of Spring Framework as well. You can do so by adding a Gradle property, as the following example shows:

Example 4.11. build.gradle

ext['spring.version']='5.2.1.RELEASE'

If you use additional features (such as LDAP, OpenID, and others), you need to also include the appropriate Chapter 6, Project Modules.

4.3.2 Gradle Without Spring Boot

When you use Spring Security without Spring Boot, the preferred way is to use Spring Security’s BOM to ensure a consistent version of Spring Security is used throughout the entire project. You can do so by using the Dependency Management Plugin, as the following example shows:

Example 4.12. build.gradle

plugins {
    id "io.spring.dependency-management" version "1.0.6.RELEASE"
}

dependencyManagement {
    imports {
        mavenBom 'org.springframework.security:spring-security-bom:5.2.1.RELEASE'
    }
}

A minimal Spring Security Maven set of dependencies typically looks like the following:

Example 4.13. build.gradle

dependencies {
    compile "org.springframework.security:spring-security-web"
    compile "org.springframework.security:spring-security-config"
}

If you use additional features (such as LDAP, OpenID, and others), you need to also include the appropriate Chapter 6, Project Modules.

Spring Security builds against Spring Framework 5.2.1.RELEASE but should generally work with any newer version of Spring Framework 5.x. {JB} Many users are likely to run afoul of the fact that Spring Security’s transitive dependencies resolve Spring Framework 5.2.1.RELEASE, which can cause strange classpath problems. The easiest way to resolve this is to use the spring-framework-bom within your <dependencyManagement> section of your pom.xml. You can do so by using the Dependency Management Plugin, as the following example shows:

Example 4.14. build.gradle

plugins {
    id "io.spring.dependency-management" version "1.0.6.RELEASE"
}

dependencyManagement {
    imports {
        mavenBom 'org.springframework:spring-framework-bom:5.2.1.RELEASE'
    }
}

The preceding example ensures that all the transitive dependencies of Spring Security use the Spring 5.2.1.RELEASE modules.

4.3.3 Gradle Repositories

All GA releases (that is, versions ending in .RELEASE) are deployed to Maven Central, so using the mavenCentral() repository is sufficient for GA releases. The following example shows how to do so:

Example 4.15. build.gradle

repositories {
    mavenCentral()
}

If you use a SNAPSHOT version, you need to ensure you have the Spring Snapshot repository defined, as the following example shows:

Example 4.16. build.gradle

repositories {
    maven { url 'https://repo.spring.io/snapshot' }
}

If you use a milestone or release candidate version, you need to ensure that you have the Spring Milestone repository defined, as the following example shows:

Example 4.17. build.gradle

repositories {
    maven { url 'https://repo.spring.io/milestone' }
}

5. Features

Spring Security provides comprehensive support for authentication, authorization, and protection against common exploits. It also provides integration with other libraries to simplify its usage.

5.1 Protection Against Exploits

Spring Security provides protection against common exploits. Whenever possible, the protection is enabled by default. Below you will find high level description of the various exploits that Spring Security protects against.

5.1.1 Cross Site Request Forgery (CSRF)

Spring provides comprehensive support for protecting against Cross Site Request Forgery (CSRF) attacks. In the following sections we will explore:

[Note]Note

This portion of the documentation discusses the general topic of CSRF protection. Refer to the relevant sections for specific information on CSRF protection for servlet and WebFlux based applications.

What is a CSRF Attack?

The best way to understand a CSRF attack is by taking a look at a concrete example.

Assume that your bank’s website provides a form that allows transferring money from the currently logged in user to another bank account. For example, the transfer form might look like:

Example 5.1. Transfer form

<form method="post"
    action="/transfer">
<input type="text"
    name="amount"/>
<input type="text"
    name="routingNumber"/>
<input type="text"
    name="account"/>
<input type="submit"
    value="Transfer"/>
</form>

The corresponding HTTP request might look like:

Example 5.2. Transfer HTTP request

POST /transfer HTTP/1.1
Host: bank.example.com
Cookie: JSESSIONID=randomid
Content-Type: application/x-www-form-urlencoded

amount=100.00&routingNumber=1234&account=9876

Now pretend you authenticate to your bank’s website and then, without logging out, visit an evil website. The evil website contains an HTML page with the following form:

Example 5.3. Evil transfer form

<form method="post"
    action="https://bank.example.com/transfer">
<input type="hidden"
    name="amount"
    value="100.00"/>
<input type="hidden"
    name="routingNumber"
    value="evilsRoutingNumber"/>
<input type="hidden"
    name="account"
    value="evilsAccountNumber"/>
<input type="submit"
    value="Win Money!"/>
</form>

You like to win money, so you click on the submit button. In the process, you have unintentionally transferred $100 to a malicious user. This happens because, while the evil website cannot see your cookies, the cookies associated with your bank are still sent along with the request.

Worst yet, this whole process could have been automated using JavaScript. This means you didn’t even need to click on the button. Furthermore, it could just as easily happen when visiting an honest site that is a victim of a XSS attack. So how do we protect our users from such attacks?

Protecting Against CSRF Attacks

The reason that a CSRF attack is possible is that the HTTP request from the victim’s website and the request from the attacker’s website are exactly the same. This means there is no way to reject requests coming from the evil website and allow requests coming from the bank’s website. To protect against CSRF attacks we need to ensure there is something in the request that the evil site is unable to provide so we can differentiate the two requests.

Spring provides two mechanisms to protect against CSRF attacks:

[Note]Note

Both protections require require that the section called “Safe Methods Must be Idempotent”

Safe Methods Must be Idempotent

In order for either protection against CSRF to work, the application must ensure that "safe" HTTP methods are idempotent. This means that requests with the HTTP method GET, HEAD, OPTIONS, and TRACE should not change the state of the application.

Synchronizer Token Pattern

The predominant and most comprehensive way to protect against CSRF attacks is to use the Synchronizer Token Pattern. This solution is to ensure that each HTTP request requires, in addition to our session cookie, a secure random generated value called a CSRF token must be present in the HTTP request.

When an HTTP request is submitted, the server must look up the expected CSRF token and compare it against the actual CSRF token in the HTTP request. If the values do not match, the HTTP request should be rejected.

The key to this working is that the actual CSRF token should be in a part of the HTTP request that is not automatically included by the browser. For example, requiring the actual CSRF token in an HTTP parameter or an HTTP header will protect against CSRF attacks. Requiring the actual CSRF token in a cookie does not work because cookies are automatically included in the HTTP request by the browser.

We can relax the expectations to only require the actual CSRF token for each HTTP request that updates state of the application. For that to work, our application must ensure that safe HTTP methods are idempotent. This improves usability since we want to allow linking to our website using links from external sites. Additionally, we do not want to include the random token in HTTP GET as this can cause the tokens to be leaked.

Let’s take a look at how our example would change when using the Synchronizer Token Pattern. Assume the actual CSRF token is required to be in an HTTP parameter named _csrf. Our application’s transfer form would look like:

Example 5.4. Synchronizer Token Form

<form method="post"
    action="/transfer">
<input type="hidden"
    name="_csrf"
    value="4bfd1575-3ad1-4d21-96c7-4ef2d9f86721"/>
<input type="text"
    name="amount"/>
<input type="text"
    name="routingNumber"/>
<input type="hidden"
    name="account"/>
<input type="submit"
    value="Transfer"/>
</form>

The form now contains a hidden input with the value of the CSRF token. External sites cannot read the CSRF token since the same origin policy ensures the evil site cannot read the response.

The corresponding HTTP request to transfer money would look like this:

Example 5.5. Synchronizer Token request

POST /transfer HTTP/1.1
Host: bank.example.com
Cookie: JSESSIONID=randomid
Content-Type: application/x-www-form-urlencoded

amount=100.00&routingNumber=1234&account=9876&_csrf=4bfd1575-3ad1-4d21-96c7-4ef2d9f86721

You will notice that the HTTP request now contains the _csrf parameter with a secure random value. The evil website will not be able to provide the correct value for the _csrf parameter (which must be explicitly provided on the evil website) and the transfer will fail when the server compares the actual CSRF token to the expected CSRF token.

SameSite Attribute

An emerging way to protect against CSRF Attacks is to specify the SameSite Attribute on cookies. A server can specify the SameSite attribute when setting a cookie to indicate that the cookie should not be sent when coming from external sites.

[Note]Note

Spring Security does not directly control the creation of the session cookie, so it does not provide support for the SameSite attribute. Spring Session provides support for the SameSite attribute in servlet based applications. Spring Framework’s CookieWebSessionIdResolver provides out of the box support for the SameSite attribute in WebFlux based applications.

An example, HTTP response header with the SameSite attribute might look like:

Example 5.6. SameSite HTTP response

Set-Cookie: JSESSIONID=randomid; Domain=bank.example.com; Secure; HttpOnly; SameSite=Lax

Valid values for the SameSite attribute are:

  • Strict - when specified any request coming from the same-site will include the cookie. Otherwise, the cookie will not be included in the HTTP request.
  • Lax - when specified cookies will be sent when coming from the same-site or when the request comes from top-level navigations and the method is idempotent. Otherwise, the cookie will not be included in the HTTP request.

Let’s take a look at how our example could be protected using the SameSite attribute. The bank application can protect against CSRF by specifying the SameSite attribute on the session cookie.

With the SameSite attribute set on our session cookie, the browser will continue to send the JSESSIONID cookie with requests coming from the banking website. However, the browser will no longer send the JSESSIONID cookie with a transfer request coming from the evil website. Since the session is no longer present in the transfer request coming from the evil website, the application is protected from the CSRF attack.

There are some important considerations that one should be aware about when using SameSite attribute to protect against CSRF attacks.

Setting the SameSite attribute to Strict provides a stronger defense but can confuse users. Consider a user that stays logged into a social media site hosted at https://social.example.com. The user receives an email at https://email.example.org that includes a link to the social media site. If the user clicks on the link, they would rightfully expect to be authenticated to the social media site. However, if the SameSite attribute is Strict the cookie would not be sent and so the user would not be authenticated.

[Note]Note

We could improve the protection and usability of SameSite protection against CSRF attacks by implementing gh-7537.

Another obvious consideration is that in order for the SameSite attribute to protect users, the browser must support the SameSite attribute. Most modern browsers do support the SameSite attribute. However, older browsers that are still in use may not.

For this reason, it is generally recommended to use the SameSite attribute as a defense in depth rather than the sole protection against CSRF attacks.

When to use CSRF protection

When should you use CSRF protection? Our recommendation is to use CSRF protection for any request that could be processed by a browser by normal users. If you are only creating a service that is used by non-browser clients, you will likely want to disable CSRF protection.

CSRF protection and JSON

A common question is "do I need to protect JSON requests made by javascript?" The short answer is, it depends. However, you must be very careful as there are CSRF exploits that can impact JSON requests. For example, a malicious user can create a CSRF with JSON using the following form:

Example 5.7. CSRF with JSON form

<form action="https://bank.example.com/transfer" method="post" enctype="text/plain">
    <input name='{"amount":100,"routingNumber":"evilsRoutingNumber","account":"evilsAccountNumber", "ignore_me":"' value='test"}' type='hidden'>
    <input type="submit"
        value="Win Money!"/>
</form>

This will produce the following JSON structure

Example 5.8. CSRF with JSON request

{ "amount": 100,
"routingNumber": "evilsRoutingNumber",
"account": "evilsAccountNumber",
"ignore_me": "=test"
}

If an application were not validating the Content-Type, then it would be exposed to this exploit. Depending on the setup, a Spring MVC application that validates the Content-Type could still be exploited by updating the URL suffix to end with .json as shown below:

Example 5.9. CSRF with JSON Spring MVC form

<form action="https://bank.example.com/transfer.json" method="post" enctype="text/plain">
    <input name='{"amount":100,"routingNumber":"evilsRoutingNumber","account":"evilsAccountNumber", "ignore_me":"' value='test"}' type='hidden'>
    <input type="submit"
        value="Win Money!"/>
</form>

CSRF and Stateless Browser Applications

What if my application is stateless? That doesn’t necessarily mean you are protected. In fact, if a user does not need to perform any actions in the web browser for a given request, they are likely still vulnerable to CSRF attacks.

For example, consider an application that uses a custom cookie that contains all the state within it for authentication instead of the JSESSIONID. When the CSRF attack is made the custom cookie will be sent with the request in the same manner that the JSESSIONID cookie was sent in our previous example. This application will be vulnerable to CSRF attacks.

Applications that use basic authentication are also vulnerable to CSRF attacks. The application is vulnerable since the browser will automatically include the username and password in any requests in the same manner that the JSESSIONID cookie was sent in our previous example.

CSRF Considerations

There are a few special considerations to consider when implementing protection against CSRF attacks.

Logging In

In order to protect against forging log in requests the log in HTTP request should be protected against CSRF attacks. Protecting against forging log in requests is necessary so that a malicious user cannot read a victim’s sensitive information. The attack is executed by:

  • A malicious user performs a CSRF log in using the malicious user’s credentials. The victim is now authenticated as the malicious user.
  • The malicious user then tricks the victim to visit the compromised website and enter sensitive information
  • The information is associated to the malicious user’s account so the malicious user can log in with their own credentials and view the vicitim’s sensitive information

A possible complication to ensuring log in HTTP requests are protected against CSRF attacks is that the user might experience a session timeout that causes the request to be rejected. A session timeout is surprising to users who do not expect to need to have a session in order to log in. For more information refer to the section called “CSRF and Session Timeouts”.

Logging Out

In order to protect against forging log out requests, the log out HTTP request should be protected against CSRF attacks. Protecting against forging log out requests is necessary so a malicious user cannot read a victim’s sensitive information. For details on the attack refer to this blog post.

A possible complication to ensuring log out HTTP requests are protected against CSRF attacks is that the user might experience a session timeout that causes the request to be rejected. A session timeout is surprising to users who do not expect to need to have a session in order to log out. For more information refer to the section called “CSRF and Session Timeouts”.

CSRF and Session Timeouts

More often than not, the expected CSRF token is stored in the session. This means that as soon as the session expires the server will not find an expected CSRF token and reject the HTTP request. There are a number of options to solve timeouts each of which come with trade offs.

  • The best way to mitigate the timeout is by using JavaScript to request a CSRF token on form submission. The form is then updated with the CSRF token and submitted.
  • Another option is to have some JavaScript that lets the user know their session is about to expire. The user can click a button to continue and refresh the session.
  • Finally, the expected CSRF token could be stored in a cookie. This allows the expected CSRF token to outlive the session.

    One might ask why the expected CSRF token isn’t stored in a cookie by default. This is because there are known exploits in which headers (i.e. specify the cookies) can be set by another domain. This is the same reason Ruby on Rails no longer skips CSRF checks when the header X-Requested-With is present. See this webappsec.org thread for details on how to perform the exploit. Another disadvantage is that by removing the state (i.e. the timeout) you lose the ability to forcibly terminate the token if it is compromised.

Multipart (file upload)

Protecting multipart requests (file uploads) from CSRF attacks causes a chicken and the egg problem. In order to prevent a CSRF attack from occurring, the body of the HTTP request must be read to obtain actual CSRF token. However, reading the body means that the file will be uploaded which means an external site can upload a file.

There are two options to using CSRF protection with multipart/form-data. Each option has its trade-offs.

[Note]Note

Before you integrate Spring Security’s CSRF protection with multipart file upload, ensure that you can upload without the CSRF protection first. More information about using multipart forms with Spring can be found within the 1.1.11. Multipart Resolver section of the Spring reference and the MultipartFilter javadoc.

Place CSRF Token in the Body

The first option is to include the actual CSRF token in the body of the request. By placing the CSRF token in the body, the body will be read before authorization is performed. This means that anyone can place temporary files on your server. However, only authorized users will be able to submit a File that is processed by your application. In general, this is the recommended approach because the temporary file uplaod should have a negligible impact on most servers.

Include CSRF Token in URL

If allowing unauthorized users to upload temporary files is not acceptable, an alternative is to include the expected CSRF token as a query parameter in the action attribute of the form. The disadvantage to this approach is that query parameters can be leaked. More generally, it is considered best practice to place sensitive data within the body or headers to ensure it is not leaked. Additional information can be found in RFC 2616 Section 15.1.3 Encoding Sensitive Information in URI’s.

HiddenHttpMethodFilter

In some applications a form parameter can be used to override the HTTP method. For example, the form below could be used to treat the HTTP method as a delete rather than a post.

Example 5.10. CSRF Hidden HTTP Method Form

<form action="/process"
    method="post">
    <!-- ... -->
    <input type="hidden"
        name="_method"
        value="delete"/>
</form>

Overriding the HTTP method occurs in a filter. That filter must be placed before Spring Security’s support. Note that overriding only happens on a post, so this is actually unlikely to cause any real problems. However, it is still best practice to ensure it is placed before Spring Security’s filters.

6. Project Modules

In Spring Security 3.0, the codebase was sub-divided into separate jars which more clearly separate different functionality areas and third-party dependencies. If you use Maven to build your project, these are the modules you should add to your pom.xml. Even if you do not use Maven, we recommend that you consult the pom.xml files to get an idea of third-party dependencies and versions. Another good idea is to examine the libraries that are included in the sample applications.

6.1 Core — spring-security-core.jar

This module contains core authentication and access-contol classes and interfaces, remoting support, and basic provisioning APIs. It is required by any application that uses Spring Security. It supports standalone applications, remote clients, method (service layer) security, and JDBC user provisioning. It contains the following top-level packages:

  • org.springframework.security.core
  • org.springframework.security.access
  • org.springframework.security.authentication
  • org.springframework.security.provisioning

6.2 Remoting — spring-security-remoting.jar

This module provides integration with Spring Remoting. You do not need this unless you are writing a remote client that uses Spring Remoting. The main package is org.springframework.security.remoting.

6.3 Web — spring-security-web.jar

This module contains filters and related web-security infrastructure code. It contains anything with a servlet API dependency. You need it if you require Spring Security web authentication services and URL-based access-control. The main package is org.springframework.security.web.

6.4 Config — spring-security-config.jar

This module contains the security namespace parsing code and Java configuration code. You need it if you use the Spring Security XML namespace for configuration or Spring Security’s Java Configuration support. The main package is org.springframework.security.config. None of the classes are intended for direct use in an application.

6.5 LDAP — spring-security-ldap.jar

This module provides LDAP authentication and provisioning code. It is required if you need to use LDAP authentication or manage LDAP user entries. The top-level package is org.springframework.security.ldap.

6.6 OAuth 2.0 Core — spring-security-oauth2-core.jar

spring-security-oauth2-core.jar contains core classes and interfaces that provide support for the OAuth 2.0 Authorization Framework and for OpenID Connect Core 1.0. It is required by applications that use OAuth 2.0 or OpenID Connect Core 1.0, such as client, resource server, and authorization server. The top-level package is org.springframework.security.oauth2.core.

6.7 OAuth 2.0 Client — spring-security-oauth2-client.jar

spring-security-oauth2-client.jar contains Spring Security’s client support for OAuth 2.0 Authorization Framework and OpenID Connect Core 1.0. It is required by applications that use OAuth 2.0 Login or OAuth Client support. The top-level package is org.springframework.security.oauth2.client.

6.8 OAuth 2.0 JOSE — spring-security-oauth2-jose.jar

spring-security-oauth2-jose.jar contains Spring Security’s support for the JOSE (Javascript Object Signing and Encryption) framework. The JOSE framework is intended to provide a method to securely transfer claims between parties. It is built from a collection of specifications:

  • JSON Web Token (JWT)
  • JSON Web Signature (JWS)
  • JSON Web Encryption (JWE)
  • JSON Web Key (JWK)

It contains the following top-level packages:

  • org.springframework.security.oauth2.jwt
  • org.springframework.security.oauth2.jose

6.9 OAuth 2.0 Resource Server — spring-security-oauth2-resource-server.jar

spring-security-oauth2-resource-server.jar contains Spring Security’s support for OAuth 2.0 Resource Servers. It is used to protect APIs via OAuth 2.0 Bearer Tokens. The top-level package is org.springframework.security.oauth2.server.resource.

6.10 ACL — spring-security-acl.jar

This module contains a specialized domain object ACL implementation. It is used to apply security to specific domain object instances within your application. The top-level package is org.springframework.security.acls.

6.11 CAS — spring-security-cas.jar

This module contains Spring Security’s CAS client integration. You should use it if you want to use Spring Security web authentication with a CAS single sign-on server. The top-level package is org.springframework.security.cas.

6.12 OpenID — spring-security-openid.jar

This module contains OpenID web authentication support. It is used to authenticate users against an external OpenID server. The top-level package is org.springframework.security.openid. It requires OpenID4Java.

6.13 Test — spring-security-test.jar

This module contains support for testing with Spring Security.

7. Samples

Spring Security includes many samples applications.

Part II. Servlet Applications

Spring Security integrates with the Servlet Container by using a standard Servlet Filter. This means it works with any application that runs in a Servlet Container. More concretely, you do not need to use Spring in your Servlet-based application to take advantage of Spring Security.

8. Hello Spring Security

This section covers a minimal Spring Security application that uses Spring Boot, Java Configuration, or XML Configuration.

8.1 Hello Spring Security (Boot)

This section covers the minimum setup for how to use Spring Security with Spring Boot. For how to use Spring Security with Java Configuration, see Section 8.2, “Hello Spring Security (Java Configuration)”. For how to use Spring Security with XML Configuration, see Section 8.3, “Hello Spring Security (XML)”.

[Note]Note

The completed application can be found at samples/boot/helloworld

8.1.1 Updating Dependencies

The only step you need to do is update the dependencies by using Maven or Gradle. For your convenience, you can download a minimal Spring Boot + Spring Security application by clicking here.

8.1.2 Starting Hello Spring Security Boot

You can now run the Spring Boot application by using the Maven Plugin’s run goal. The following example shows how to do so (and the beginning of the output from doing so):

Example 8.1. Running Spring Boot Application

$ ./mvn spring-boot:run
...
INFO 23689 --- [  restartedMain] .s.s.UserDetailsServiceAutoConfiguration :

Using generated security password: 8e557245-73e2-4286-969a-ff57fe326336

...

8.1.3 Spring Boot Auto Configuration

Spring Boot automatically:

  • Enables Spring Security’s default configuration, which creates a servlet Filter as a bean named springSecurityFilterChain. This bean is responsible for all the security (protecting the application URLs, validating submitted username and passwords, redirecting to the log in form, and so on) within your application.
  • Creates a UserDetailsService bean with a username of user and a randomly generated password that is logged to the console.
  • Registers the Filter with a bean named springSecurityFilterChain with the Servlet container for every request.

Spring Boot is not configuring much, but it does a lot. A summary of the features follows:

8.2 Hello Spring Security (Java Configuration)

This section covers how to use Spring Security with Java Configuration. For how to use Spring Security with XML configuration, see Section 8.3, “Hello Spring Security (XML)”. For how to use Spring Security with Spring Boot configuration, see Section 8.1, “Hello Spring Security (Boot)”.

[Note]Note

You can find the completed application at samples/javaconfig/helloworld.

8.2.1 Updating Dependencies

The first step is to update the dependencies by using Maven or Gradle.

8.2.2 Minimal @EnableWebSecurity Configuration

The first step is to create our Spring Security Java configuration. The configuration creates a servlet Filter (known as the springSecurityFilterChain), which is responsible for all the security features (protecting the application URLs, validating submitted username and passwords, redirecting to the log in form, and so on) within your application. The following example shows the most basic example of a Spring Security Java Configuration:

Example 8.2. WebSecurity.java

import org.springframework.context.annotation.*;
import org.springframework.security.config.annotation.web.configuration.*;
import org.springframework.security.core.userdetails.*;
import org.springframework.security.provisioning.*;

@EnableWebSecurity
public class WebSecurityConfig {

    // @formatter:off
    @Bean
    public UserDetailsService userDetailsService() {
        UserDetails user = User.withDefaultPasswordEncoder()
            .username("user")
            .password("password")
            .roles("USER")
            .build();
        return  new InMemoryUserDetailsManager(user);
    }
    // @formatter:on
}

There really is not much to this configuration, but it does a lot. A summary of the features follows:

8.2.3 Using AbstractSecurityWebApplicationInitializer

The next step is to register the springSecurityFilterChain with the war. Spring Security provides a base class (AbstractSecurityWebApplicationInitializer) that leverages Spring’s WebApplicationInitializer support.

The following example shows an example configuration:

Example 8.3. SecurityInitializer.java

import org.springframework.security.web.context.*;

public class SecurityInitializer
    extends AbstractSecurityWebApplicationInitializer {

    public SecurityInitializer() {
        super(WebSecurityConfig.class);
    }
}

The SecurityInitializer does the following things:

  • Adds a ContextLoaderListener that loads the WebSecurityConfig.
  • Finds the bean of type Filter named springSecurityFilterChain and registers it to process every URL in the application.
[Note]Note

If you are integrating with a Spring MVC application, be sure to configure the DispatcherServlet to load the configuration from the root ApplicationContext. The following example shows how to do so:

Example 8.4. MvcInitializer.java

public class MvcInitializer extends
        AbstractAnnotationConfigDispatcherServletInitializer {

    // the Root Config is registered in SecurityInitializer
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    // the Spring MVC configuration should be added to SecurityInitializer constructor
    // i.e.
    // super(MvcConfig.class, WebSecurityConfig.class);
    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

}

8.3 Hello Spring Security (XML)

This section covers how to use Spring Security with XML Configuration. For how to use Spring Security with Java configuration, see Section 8.2, “Hello Spring Security (Java Configuration)”. For how to use Spring Security with Spring Boot configuration, see Section 8.1, “Hello Spring Security (Boot)”.

8.3.1 Updating Dependencies

The first step is to update the dependencies by using Maven or Gradle.

8.3.2 Minimal <http> Configuration

In this section, we discuss how to use Spring Security with XML Configuration.

[Note]Note

The completed application can be found at samples/xml/helloworld

The first step is to create our Spring Security XML Configuration. The configuration creates a Servlet Filter (known as the springSecurityFilterChain), which is responsible for all the security (protecting the application URLs, validating submitted username and passwords, redirecting to the log in form, and so on) within your application. The following example shows the most basic example of a Spring Security XML Configuration:

Example 8.5. src/main/webapp/WEB-INF/spring/security.xml

<b:beans xmlns="http://www.springframework.org/schema/security"
         xmlns:b="http://www.springframework.org/schema/beans"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
                        http://www.springframework.org/schema/security https://www.springframework.org/schema/security/spring-security.xsd">
    <http />

    <user-service>
        <user name="user" password="{noop}password" authorities="ROLE_USER" />
    </user-service>
</b:beans>

There really is not much to this configuration, but it does a lot. A summary of the features follows:

8.3.3 web.xml Configuration

The next step is to ensure that our Security configuration is being read in. To do so, we need to ensure a ContextLoaderListener is registered and the contextConfigLocation is including the configuration. The following example shows how to do so:

Example 8.6. src/main/webapp/WEB-INF/web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
  http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

    <!--
        Loads the Spring configurations from contextConfigLocation
    -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!--
        The locations of the Spring Configuration. In this case, all configuration is
        in /WEB-INF/spring/
    -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/spring/*.xml
        </param-value>
    </context-param>

    <!--
        DelegatingFilterProxy looks for a Spring bean by the name of filter (springSecurityFilterChain) and delegates
        all work to that Bean. This is how the Servlet Container can a Spring Bean to act as a Servlet Filter.
    -->
    <filter>
        <filter-name>springSecurityFilterChain</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>springSecurityFilterChain</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

[Note]Note

If you integrate with an existing Spring MVC application, be sure to configure the DispatcherServlet to load the configuration from the root ApplicationContext. The following example shows how to do so:

src/main/webapp/WEB-INF/web.xml. 

<servlet>
    <servlet-name>spring</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!-- Load Spring MVC configuration from root ApplicationContext (context-param from above) -->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value></param-value>
    </init-param>
</servlet>

<servlet-mapping>
  <servlet-name>spring</servlet-name>
  <url-pattern>/</url-pattern>
</servlet-mapping>

9. Architecture and Implementation

Once you are familiar with setting up and running some namespace-configuration based applications, you may wish to develop more of an understanding of how the framework actually works behind the namespace facade. Like most software, Spring Security has certain central interfaces, classes and conceptual abstractions that are commonly used throughout the framework. In this part of the reference guide we will look at some of these and see how they work together to support authentication and access-control within Spring Security.

9.1 Technical Overview

9.1.1 Runtime Environment

Spring Security 5.2.1.RELEASE requires a Java 8 Runtime Environment or higher. As Spring Security aims to operate in a self-contained manner, there is no need to place any special configuration files into your Java Runtime Environment. In particular, there is no need to configure a special Java Authentication and Authorization Service (JAAS) policy file or place Spring Security into common classpath locations.

Similarly, if you are using an EJB Container or Servlet Container there is no need to put any special configuration files anywhere, nor include Spring Security in a server classloader. All the required files will be contained within your application.

This design offers maximum deployment time flexibility, as you can simply copy your target artifact (be it a JAR, WAR or EAR) from one system to another and it will immediately work.

9.1.2 Core Components

As of Spring Security 3.0, the contents of the spring-security-core jar were stripped down to the bare minimum. It no longer contains any code related to web-application security, LDAP or namespace configuration. We’ll take a look here at some of the Java types that you’ll find in the core module. They represent the building blocks of the framework, so if you ever need to go beyond a simple namespace configuration then it’s important that you understand what they are, even if you don’t actually need to interact with them directly.

SecurityContextHolder, SecurityContext and Authentication Objects

The most fundamental object is SecurityContextHolder. This is where we store details of the present security context of the application, which includes details of the principal currently using the application. By default the SecurityContextHolder uses a ThreadLocal to store these details, which means that the security context is always available to methods in the same thread of execution, even if the security context is not explicitly passed around as an argument to those methods. Using a ThreadLocal in this way is quite safe if care is taken to clear the thread after the present principal’s request is processed. Of course, Spring Security takes care of this for you automatically so there is no need to worry about it.

Some applications aren’t entirely suitable for using a ThreadLocal, because of the specific way they work with threads. For example, a Swing client might want all threads in a Java Virtual Machine to use the same security context. SecurityContextHolder can be configured with a strategy on startup to specify how you would like the context to be stored. For a standalone application you would use the SecurityContextHolder.MODE_GLOBAL strategy. Other applications might want to have threads spawned by the secure thread also assume the same security identity. This is achieved by using SecurityContextHolder.MODE_INHERITABLETHREADLOCAL. You can change the mode from the default SecurityContextHolder.MODE_THREADLOCAL in two ways. The first is to set a system property, the second is to call a static method on SecurityContextHolder. Most applications won’t need to change from the default, but if you do, take a look at the JavaDoc for SecurityContextHolder to learn more.

Obtaining information about the current user

Inside the SecurityContextHolder we store details of the principal currently interacting with the application. Spring Security uses an Authentication object to represent this information. You won’t normally need to create an Authentication object yourself, but it is fairly common for users to query the Authentication object. You can use the following code block - from anywhere in your application - to obtain the name of the currently authenticated user, for example:

Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();

if (principal instanceof UserDetails) {
String username = ((UserDetails)principal).getUsername();
} else {
String username = principal.toString();
}

The object returned by the call to getContext() is an instance of the SecurityContext interface. This is the object that is kept in thread-local storage. As we’ll see below, most authentication mechanisms within Spring Security return an instance of UserDetails as the principal.

The UserDetailsService

Another item to note from the above code fragment is that you can obtain a principal from the Authentication object. The principal is just an Object. Most of the time this can be cast into a UserDetails object. UserDetails is a core interface in Spring Security. It represents a principal, but in an extensible and application-specific way. Think of UserDetails as the adapter between your own user database and what Spring Security needs inside the SecurityContextHolder. Being a representation of something from your own user database, quite often you will cast the UserDetails to the original object that your application provided, so you can call business-specific methods (like getEmail(), getEmployeeNumber() and so on).

By now you’re probably wondering, so when do I provide a UserDetails object? How do I do that? I thought you said this thing was declarative and I didn’t need to write any Java code - what gives? The short answer is that there is a special interface called UserDetailsService. The only method on this interface accepts a String-based username argument and returns a UserDetails:

UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;

This is the most common approach to loading information for a user within Spring Security and you will see it used throughout the framework whenever information on a user is required.

On successful authentication, UserDetails is used to build the Authentication object that is stored in the SecurityContextHolder (more on this below). The good news is that we provide a number of UserDetailsService implementations, including one that uses an in-memory map (InMemoryDaoImpl) and another that uses JDBC (JdbcDaoImpl). Most users tend to write their own, though, with their implementations often simply sitting on top of an existing Data Access Object (DAO) that represents their employees, customers, or other users of the application. Remember the advantage that whatever your UserDetailsService returns can always be obtained from the SecurityContextHolder using the above code fragment.

[Note]Note

There is often some confusion about UserDetailsService. It is purely a DAO for user data and performs no other function other than to supply that data to other components within the framework. In particular, it does not authenticate the user, which is done by the AuthenticationManager. In many cases it makes more sense to implement AuthenticationProvider directly if you require a custom authentication process.

GrantedAuthority

Besides the principal, another important method provided by Authentication is getAuthorities(). This method provides an array of GrantedAuthority objects. A GrantedAuthority is, not surprisingly, an authority that is granted to the principal. Such authorities are usually "roles", such as ROLE_ADMINISTRATOR or ROLE_HR_SUPERVISOR. These roles are later on configured for web authorization, method authorization and domain object authorization. Other parts of Spring Security are capable of interpreting these authorities, and expect them to be present. GrantedAuthority objects are usually loaded by the UserDetailsService.

Usually the GrantedAuthority objects are application-wide permissions. They are not specific to a given domain object. Thus, you wouldn’t likely have a GrantedAuthority to represent a permission to Employee object number 54, because if there are thousands of such authorities you would quickly run out of memory (or, at the very least, cause the application to take a long time to authenticate a user). Of course, Spring Security is expressly designed to handle this common requirement, but you’d instead use the project’s domain object security capabilities for this purpose.

Summary

Just to recap, the major building blocks of Spring Security that we’ve seen so far are:

  • SecurityContextHolder, to provide access to the SecurityContext.
  • SecurityContext, to hold the Authentication and possibly request-specific security information.
  • Authentication, to represent the principal in a Spring Security-specific manner.
  • GrantedAuthority, to reflect the application-wide permissions granted to a principal.
  • UserDetails, to provide the necessary information to build an Authentication object from your application’s DAOs or other source of security data.
  • UserDetailsService, to create a UserDetails when passed in a String-based username (or certificate ID or the like).

Now that you’ve gained an understanding of these repeatedly-used components, let’s take a closer look at the process of authentication.

9.1.3 Authentication

Spring Security can participate in many different authentication environments. While we recommend people use Spring Security for authentication and not integrate with existing Container Managed Authentication, it is nevertheless supported - as is integrating with your own proprietary authentication system.

What is authentication in Spring Security?

Let’s consider a standard authentication scenario that everyone is familiar with.

  1. A user is prompted to log in with a username and password.
  2. The system (successfully) verifies that the password is correct for the username.
  3. The context information for that user is obtained (their list of roles and so on).
  4. A security context is established for the user
  5. The user proceeds, potentially to perform some operation which is potentially protected by an access control mechanism which checks the required permissions for the operation against the current security context information.

The first four items constitute the authentication process so we’ll take a look at how these take place within Spring Security.

  1. The username and password are obtained and combined into an instance of UsernamePasswordAuthenticationToken (an instance of the Authentication interface, which we saw earlier).
  2. The token is passed to an instance of AuthenticationManager for validation.
  3. The AuthenticationManager returns a fully populated Authentication instance on successful authentication.
  4. The security context is established by calling SecurityContextHolder.getContext().setAuthentication(…​), passing in the returned authentication object.

From that point on, the user is considered to be authenticated. Let’s look at some code as an example.

import org.springframework.security.authentication.*;
import org.springframework.security.core.*;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;

public class AuthenticationExample {
private static AuthenticationManager am = new SampleAuthenticationManager();

public static void main(String[] args) throws Exception {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    while(true) {
    System.out.println("Please enter your username:");
    String name = in.readLine();
    System.out.println("Please enter your password:");
    String password = in.readLine();
    try {
        Authentication request = new UsernamePasswordAuthenticationToken(name, password);
        Authentication result = am.authenticate(request);
        SecurityContextHolder.getContext().setAuthentication(result);
        break;
    } catch(AuthenticationException e) {
        System.out.println("Authentication failed: " + e.getMessage());
    }
    }
    System.out.println("Successfully authenticated. Security context contains: " +
            SecurityContextHolder.getContext().getAuthentication());
}
}

class SampleAuthenticationManager implements AuthenticationManager {
static final List<GrantedAuthority> AUTHORITIES = new ArrayList<GrantedAuthority>();

static {
    AUTHORITIES.add(new SimpleGrantedAuthority("ROLE_USER"));
}

public Authentication authenticate(Authentication auth) throws AuthenticationException {
    if (auth.getName().equals(auth.getCredentials())) {
    return new UsernamePasswordAuthenticationToken(auth.getName(),
        auth.getCredentials(), AUTHORITIES);
    }
    throw new BadCredentialsException("Bad Credentials");
}
}

Here we have written a little program that asks the user to enter a username and password and performs the above sequence. The AuthenticationManager which we’ve implemented here will authenticate any user whose username and password are the same. It assigns a single role to every user. The output from the above will be something like:

Please enter your username:
bob
Please enter your password:
password
Authentication failed: Bad Credentials
Please enter your username:
bob
Please enter your password:
bob
Successfully authenticated. Security context contains: \
org.springframew[email protected]441d0230: \
Principal: bob; Password: [PROTECTED]; \
Authenticated: true; Details: null; \
Granted Authorities: ROLE_USER

Note that you don’t normally need to write any code like this. The process will normally occur internally, in a web authentication filter for example. We’ve just included the code here to show that the question of what actually constitutes authentication in Spring Security has quite a simple answer. A user is authenticated when the SecurityContextHolder contains a fully populated Authentication object.

Setting the SecurityContextHolder Contents Directly

In fact, Spring Security doesn’t mind how you put the Authentication object inside the SecurityContextHolder. The only critical requirement is that the SecurityContextHolder contains an Authentication which represents a principal before the AbstractSecurityInterceptor (which we’ll see more about later) needs to authorize a user operation.

You can (and many users do) write their own filters or MVC controllers to provide interoperability with authentication systems that are not based on Spring Security. For example, you might be using Container-Managed Authentication which makes the current user available from a ThreadLocal or JNDI location. Or you might work for a company that has a legacy proprietary authentication system, which is a corporate "standard" over which you have little control. In situations like this it’s quite easy to get Spring Security to work, and still provide authorization capabilities. All you need to do is write a filter (or equivalent) that reads the third-party user information from a location, build a Spring Security-specific Authentication object, and put it into the SecurityContextHolder. In this case you also need to think about things which are normally taken care of automatically by the built-in authentication infrastructure. For example, you might need to pre-emptively create an HTTP session to cache the context between requests, before you write the response to the client [1].

If you’re wondering how the AuthenticationManager is implemented in a real world example, we’ll look at that in the core services chapter.

9.1.4 Authentication in a Web Application

Now let’s explore the situation where you are using Spring Security in a web application (without web.xml security enabled). How is a user authenticated and the security context established?

Consider a typical web application’s authentication process:

  1. You visit the home page, and click on a link.
  2. A request goes to the server, and the server decides that you’ve asked for a protected resource.
  3. As you’re not presently authenticated, the server sends back a response indicating that you must authenticate. The response will either be an HTTP response code, or a redirect to a particular web page.
  4. Depending on the authentication mechanism, your browser will either redirect to the specific web page so that you can fill out the form, or the browser will somehow retrieve your identity (via a BASIC authentication dialogue box, a cookie, a X.509 certificate etc.).
  5. The browser will send back a response to the server. This will either be an HTTP POST containing the contents of the form that you filled out, or an HTTP header containing your authentication details.
  6. Next the server will decide whether or not the presented credentials are valid. If they’re valid, the next step will happen. If they’re invalid, usually your browser will be asked to try again (so you return to step two above).
  7. The original request that you made to cause the authentication process will be retried. Hopefully you’ve authenticated with sufficient granted authorities to access the protected resource. If you have sufficient access, the request will be successful. Otherwise, you’ll receive back an HTTP error code 403, which means "forbidden".

Spring Security has distinct classes responsible for most of the steps described above. The main participants (in the order that they are used) are the ExceptionTranslationFilter, an AuthenticationEntryPoint and an "authentication mechanism", which is responsible for calling the AuthenticationManager which we saw in the previous section.

ExceptionTranslationFilter

ExceptionTranslationFilter is a Spring Security filter that has responsibility for detecting any Spring Security exceptions that are thrown. Such exceptions will generally be thrown by an AbstractSecurityInterceptor, which is the main provider of authorization services. We will discuss AbstractSecurityInterceptor in the next section, but for now we just need to know that it produces Java exceptions and knows nothing about HTTP or how to go about authenticating a principal. Instead the ExceptionTranslationFilter offers this service, with specific responsibility for either returning error code 403 (if the principal has been authenticated and therefore simply lacks sufficient access - as per step seven above), or launching an AuthenticationEntryPoint (if the principal has not been authenticated and therefore we need to go commence step three).

AuthenticationEntryPoint

The AuthenticationEntryPoint is responsible for step three in the above list. As you can imagine, each web application will have a default authentication strategy (well, this can be configured like nearly everything else in Spring Security, but let’s keep it simple for now). Each major authentication system will have its own AuthenticationEntryPoint implementation, which typically performs one of the actions described in step 3.

Authentication Mechanism

Once your browser submits your authentication credentials (either as an HTTP form post or HTTP header) there needs to be something on the server that "collects" these authentication details. By now we’re at step six in the above list. In Spring Security we have a special name for the function of collecting authentication details from a user agent (usually a web browser), referring to it as the "authentication mechanism". Examples are form-base login and Basic authentication. Once the authentication details have been collected from the user agent, an Authentication "request" object is built and then presented to the AuthenticationManager.

After the authentication mechanism receives back the fully-populated Authentication object, it will deem the request valid, put the Authentication into the SecurityContextHolder, and cause the original request to be retried (step seven above). If, on the other hand, the AuthenticationManager rejected the request, the authentication mechanism will ask the user agent to retry (step two above).

Storing the SecurityContext between requests

Depending on the type of application, there may need to be a strategy in place to store the security context between user operations. In a typical web application, a user logs in once and is subsequently identified by their session Id. The server caches the principal information for the duration session. In Spring Security, the responsibility for storing the SecurityContext between requests falls to the SecurityContextPersistenceFilter, which by default stores the context as an HttpSession attribute between HTTP requests. It restores the context to the SecurityContextHolder for each request and, crucially, clears the SecurityContextHolder when the request completes. You shouldn’t interact directly with the HttpSession for security purposes. There is simply no justification for doing so - always use the SecurityContextHolder instead.

Many other types of application (for example, a stateless RESTful web service) do not use HTTP sessions and will re-authenticate on every request. However, it is still important that the SecurityContextPersistenceFilter is included in the chain to make sure that the SecurityContextHolder is cleared after each request.

[Note]Note

In an application which receives concurrent requests in a single session, the same SecurityContext instance will be shared between threads. Even though a ThreadLocal is being used, it is the same instance that is retrieved from the HttpSession for each thread. This has implications if you wish to temporarily change the context under which a thread is running. If you just use SecurityContextHolder.getContext(), and call setAuthentication(anAuthentication) on the returned context object, then the Authentication object will change in all concurrent threads which share the same SecurityContext instance. You can customize the behaviour of SecurityContextPersistenceFilter to create a completely new SecurityContext for each request, preventing changes in one thread from affecting another. Alternatively you can create a new instance just at the point where you temporarily change the context. The method SecurityContextHolder.createEmptyContext() always returns a new context instance.

9.1.5 Access-Control (Authorization) in Spring Security

The main interface responsible for making access-control decisions in Spring Security is the AccessDecisionManager. It has a decide method which takes an Authentication object representing the principal requesting access, a "secure object" (see below) and a list of security metadata attributes which apply for the object (such as a list of roles which are required for access to be granted).

Security and AOP Advice

If you’re familiar with AOP, you’d be aware there are different types of advice available: before, after, throws and around. An around advice is very useful, because an advisor can elect whether or not to proceed with a method invocation, whether or not to modify the response, and whether or not to throw an exception. Spring Security provides an around advice for method invocations as well as web requests. We achieve an around advice for method invocations using Spring’s standard AOP support and we achieve an around advice for web requests using a standard Filter.

For those not familiar with AOP, the key point to understand is that Spring Security can help you protect method invocations as well as web requests. Most people are interested in securing method invocations on their services layer. This is because the services layer is where most business logic resides in current-generation Java EE applications. If you just need to secure method invocations in the services layer, Spring’s standard AOP will be adequate. If you need to secure domain objects directly, you will likely find that AspectJ is worth considering.

You can elect to perform method authorization using AspectJ or Spring AOP, or you can elect to perform web request authorization using filters. You can use zero, one, two or three of these approaches together. The mainstream usage pattern is to perform some web request authorization, coupled with some Spring AOP method invocation authorization on the services layer.

Secure Objects and the AbstractSecurityInterceptor

So what is a "secure object" anyway? Spring Security uses the term to refer to any object that can have security (such as an authorization decision) applied to it. The most common examples are method invocations and web requests.

Each supported secure object type has its own interceptor class, which is a subclass of AbstractSecurityInterceptor. Importantly, by the time the AbstractSecurityInterceptor is called, the SecurityContextHolder will contain a valid Authentication if the principal has been authenticated.

AbstractSecurityInterceptor provides a consistent workflow for handling secure object requests, typically:

  1. Look up the "configuration attributes" associated with the present request
  2. Submitting the secure object, current Authentication and configuration attributes to the AccessDecisionManager for an authorization decision
  3. Optionally change the Authentication under which the invocation takes place
  4. Allow the secure object invocation to proceed (assuming access was granted)
  5. Call the AfterInvocationManager if configured, once the invocation has returned. If the invocation raised an exception, the AfterInvocationManager will not be invoked.
What are Configuration Attributes?

A "configuration attribute" can be thought of as a String that has special meaning to the classes used by AbstractSecurityInterceptor. They are represented by the interface ConfigAttribute within the framework. They may be simple role names or have more complex meaning, depending on the how sophisticated the AccessDecisionManager implementation is. The AbstractSecurityInterceptor is configured with a SecurityMetadataSource which it uses to look up the attributes for a secure object. Usually this configuration will be hidden from the user. Configuration attributes will be entered as annotations on secured methods or as access attributes on secured URLs. For example, when we saw something like <intercept-url pattern='/secure/**' access='ROLE_A,ROLE_B'/> in the namespace introduction, this is saying that the configuration attributes ROLE_A and ROLE_B apply to web requests matching the given pattern. In practice, with the default AccessDecisionManager configuration, this means that anyone who has a GrantedAuthority matching either of these two attributes will be allowed access. Strictly speaking though, they are just attributes and the interpretation is dependent on the AccessDecisionManager implementation. The use of the prefix ROLE_ is a marker to indicate that these attributes are roles and should be consumed by Spring Security’s RoleVoter. This is only relevant when a voter-based AccessDecisionManager is in use. We’ll see how the AccessDecisionManager is implemented in the authorization chapter.

RunAsManager

Assuming AccessDecisionManager decides to allow the request, the AbstractSecurityInterceptor will normally just proceed with the request. Having said that, on rare occasions users may want to replace the Authentication inside the SecurityContext with a different Authentication, which is handled by the AccessDecisionManager calling a RunAsManager. This might be useful in reasonably unusual situations, such as if a services layer method needs to call a remote system and present a different identity. Because Spring Security automatically propagates security identity from one server to another (assuming you’re using a properly-configured RMI or HttpInvoker remoting protocol client), this may be useful.

AfterInvocationManager

Following the secure object invocation proceeding and then returning - which may mean a method invocation completing or a filter chain proceeding - the AbstractSecurityInterceptor gets one final chance to handle the invocation. At this stage the AbstractSecurityInterceptor is interested in possibly modifying the return object. We might want this to happen because an authorization decision couldn’t be made "on the way in" to a secure object invocation. Being highly pluggable, AbstractSecurityInterceptor will pass control to an AfterInvocationManager to actually modify the object if needed. This class can even entirely replace the object, or throw an exception, or not change it in any way as it chooses. The after-invocation checks will only be executed if the invocation is successful. If an exception occurs, the additional checks will be skipped.

AbstractSecurityInterceptor and its related objects are shown in Figure 9.1, “Security interceptors and the "secure object" model”

Figure 9.1. Security interceptors and the "secure object" model

Abstract Security Interceptor

Extending the Secure Object Model

Only developers contemplating an entirely new way of intercepting and authorizing requests would need to use secure objects directly. For example, it would be possible to build a new secure object to secure calls to a messaging system. Anything that requires security and also provides a way of intercepting a call (like the AOP around advice semantics) is capable of being made into a secure object. Having said that, most Spring applications will simply use the three currently supported secure object types (AOP Alliance MethodInvocation, AspectJ JoinPoint and web request FilterInvocation) with complete transparency.

9.2 Core Services

Now that we have a high-level overview of the Spring Security architecture and its core classes, let’s take a closer look at one or two of the core interfaces and their implementations, in particular the AuthenticationManager, UserDetailsService and the AccessDecisionManager. These crop up regularly throughout the remainder of this document so it’s important you know how they are configured and how they operate.

9.2.1 The AuthenticationManager, ProviderManager and AuthenticationProvider

The AuthenticationManager is just an interface, so the implementation can be anything we choose, but how does it work in practice? What if we need to check multiple authentication databases or a combination of different authentication services such as a database and an LDAP server?

The default implementation in Spring Security is called ProviderManager and rather than handling the authentication request itself, it delegates to a list of configured AuthenticationProvider s, each of which is queried in turn to see if it can perform the authentication. Each provider will either throw an exception or return a fully populated Authentication object. Remember our good friends, UserDetails and UserDetailsService? If not, head back to the previous chapter and refresh your memory. The most common approach to verifying an authentication request is to load the corresponding UserDetails and check the loaded password against the one that has been entered by the user. This is the approach used by the DaoAuthenticationProvider (see below). The loaded UserDetails object - and particularly the GrantedAuthority s it contains - will be used when building the fully populated Authentication object which is returned from a successful authentication and stored in the SecurityContext.

If you are using the namespace, an instance of ProviderManager is created and maintained internally, and you add providers to it by using the namespace authentication provider elements (see the namespace chapter). In this case, you should not declare a ProviderManager bean in your application context. However, if you are not using the namespace then you would declare it like so:

<bean id="authenticationManager"
        class="org.springframework.security.authentication.ProviderManager">
    <constructor-arg>
        <list>
            <ref local="daoAuthenticationProvider"/>
            <ref local="anonymousAuthenticationProvider"/>
            <ref local="ldapAuthenticationProvider"/>
        </list>
    </constructor-arg>
</bean>

In the above example we have three providers. They are tried in the order shown (which is implied by the use of a List), with each provider able to attempt authentication, or skip authentication by simply returning null. If all implementations return null, the ProviderManager will throw a ProviderNotFoundException. If you’re interested in learning more about chaining providers, please refer to the ProviderManager Javadoc.

Authentication mechanisms such as a web form-login processing filter are injected with a reference to the ProviderManager and will call it to handle their authentication requests. The providers you require will sometimes be interchangeable with the authentication mechanisms, while at other times they will depend on a specific authentication mechanism. For example, DaoAuthenticationProvider and LdapAuthenticationProvider are compatible with any mechanism which submits a simple username/password authentication request and so will work with form-based logins or HTTP Basic authentication. On the other hand, some authentication mechanisms create an authentication request object which can only be interpreted by a single type of AuthenticationProvider. An example of this would be JA-SIG CAS, which uses the notion of a service ticket and so can therefore only be authenticated by a CasAuthenticationProvider. You needn’t be too concerned about this, because if you forget to register a suitable provider, you’ll simply receive a ProviderNotFoundException when an attempt to authenticate is made.

Erasing Credentials on Successful Authentication

By default (from Spring Security 3.1 onwards) the ProviderManager will attempt to clear any sensitive credentials information from the Authentication object which is returned by a successful authentication request. This prevents information like passwords being retained longer than necessary.

This may cause issues when you are using a cache of user objects, for example, to improve performance in a stateless application. If the Authentication contains a reference to an object in the cache (such as a UserDetails instance) and this has its credentials removed, then it will no longer be possible to authenticate against the cached value. You need to take this into account if you are using a cache. An obvious solution is to make a copy of the object first, either in the cache implementation or in the AuthenticationProvider which creates the returned Authentication object. Alternatively, you can disable the eraseCredentialsAfterAuthentication property on ProviderManager. See the Javadoc for more information.

DaoAuthenticationProvider

The simplest AuthenticationProvider implemented by Spring Security is DaoAuthenticationProvider, which is also one of the earliest supported by the framework. It leverages a UserDetailsService (as a DAO) in order to lookup the username, password and GrantedAuthority s. It authenticates the user simply by comparing the password submitted in a UsernamePasswordAuthenticationToken against the one loaded by the UserDetailsService. Configuring the provider is quite simple:

<bean id="daoAuthenticationProvider"
    class="org.springframework.security.authentication.dao.DaoAuthenticationProvider">
<property name="userDetailsService" ref="inMemoryDaoImpl"/>
<property name="passwordEncoder" ref="passwordEncoder"/>
</bean>

The PasswordEncoder is optional. A PasswordEncoder provides encoding and decoding of passwords presented in the UserDetails object that is returned from the configured UserDetailsService. This will be discussed in more detail below.

9.2.2 UserDetailsService Implementations

As mentioned in the earlier in this reference guide, most authentication providers take advantage of the UserDetails and UserDetailsService interfaces. Recall that the contract for UserDetailsService is a single method:

UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;

The returned UserDetails is an interface that provides getters that guarantee non-null provision of authentication information such as the username, password, granted authorities and whether the user account is enabled or disabled. Most authentication providers will use a UserDetailsService, even if the username and password are not actually used as part of the authentication decision. They may use the returned UserDetails object just for its GrantedAuthority information, because some other system (like LDAP or X.509 or CAS etc) has undertaken the responsibility of actually validating the credentials.

Given UserDetailsService is so simple to implement, it should be easy for users to retrieve authentication information using a persistence strategy of their choice. Having said that, Spring Security does include a couple of useful base implementations, which we’ll look at below.

In-Memory Authentication

Is easy to use create a custom UserDetailsService implementation that extracts information from a persistence engine of choice, but many applications do not require such complexity. This is particularly true if you’re building a prototype application or just starting integrating Spring Security, when you don’t really want to spend time configuring databases or writing UserDetailsService implementations. For this sort of situation, a simple option is to use the user-service element from the security namespace:

<user-service id="userDetailsService">
<!-- Password is prefixed with {noop} to indicate to DelegatingPasswordEncoder that
NoOpPasswordEncoder should be used. This is not safe for production, but makes reading
in samples easier. Normally passwords should be hashed using BCrypt -->
<user name="jimi" password="{noop}jimispassword" authorities="ROLE_USER, ROLE_ADMIN" />
<user name="bob" password="{noop}bobspassword" authorities="ROLE_USER" />
</user-service>

This also supports the use of an external properties file:

<user-service id="userDetailsService" properties="users.properties"/>

The properties file should contain entries in the form

username=password,grantedAuthority[,grantedAuthority][,enabled|disabled]

For example

jimi=jimispassword,ROLE_USER,ROLE_ADMIN,enabled
bob=bobspassword,ROLE_USER,enabled

JdbcDaoImpl

Spring Security also includes a UserDetailsService that can obtain authentication information from a JDBC data source. Internally Spring JDBC is used, so it avoids the complexity of a fully-featured object relational mapper (ORM) just to store user details. If your application does use an ORM tool, you might prefer to write a custom UserDetailsService to reuse the mapping files you’ve probably already created. Returning to JdbcDaoImpl, an example configuration is shown below:

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.hsqldb.jdbcDriver"/>
<property name="url" value="jdbc:hsqldb:hsql://localhost:9001"/>
<property name="username" value="sa"/>
<property name="password" value=""/>
</bean>

<bean id="userDetailsService"
    class="org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl">
<property name="dataSource" ref="dataSource"/>
</bean>

You can use different relational database management systems by modifying the DriverManagerDataSource shown above. You can also use a global data source obtained from JNDI, as with any other Spring configuration.

Authority Groups

By default, JdbcDaoImpl loads the authorities for a single user with the assumption that the authorities are mapped directly to users (see the database schema appendix). An alternative approach is to partition the authorities into groups and assign groups to the user. Some people prefer this approach as a means of administering user rights. See the JdbcDaoImpl Javadoc for more information on how to enable the use of group authorities. The group schema is also included in the appendix.



[1] It isn’t possible to create a session once the response has been committed.

10. Authentication

10.1 In-Memory Authentication

We have already seen an example of configuring in-memory authentication for a single user. Below is an example to configure multiple users:

@Bean
public UserDetailsService userDetailsService() throws Exception {
    // ensure the passwords are encoded properly
    UserBuilder users = User.withDefaultPasswordEncoder();
    InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
    manager.createUser(users.username("user").password("password").roles("USER").build());
    manager.createUser(users.username("admin").password("password").roles("USER","ADMIN").build());
    return manager;
}

10.2 JDBC Authentication

You can find the updates to support JDBC based authentication. The example below assumes that you have already defined a DataSource within your application. The jdbc-javaconfig sample provides a complete example of using JDBC based authentication.

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
    // ensure the passwords are encoded properly
    UserBuilder users = User.withDefaultPasswordEncoder();
    auth
        .jdbcAuthentication()
            .dataSource(dataSource)
            .withDefaultSchema()
            .withUser(users.username("user").password("password").roles("USER"))
            .withUser(users.username("admin").password("password").roles("USER","ADMIN"));
}

10.3 LDAP Authentication

10.3.1 Overview

LDAP is often used by organizations as a central repository for user information and as an authentication service. It can also be used to store the role information for application users.

There are many different scenarios for how an LDAP server may be configured so Spring Security’s LDAP provider is fully configurable. It uses separate strategy interfaces for authentication and role retrieval and provides default implementations which can be configured to handle a wide range of situations.

You should be familiar with LDAP before trying to use it with Spring Security. The following link provides a good introduction to the concepts involved and a guide to setting up a directory using the free LDAP server OpenLDAP: http://www.zytrax.com/books/ldap/. Some familiarity with the JNDI APIs used to access LDAP from Java may also be useful. We don’t use any third-party LDAP libraries (Mozilla, JLDAP etc.) in the LDAP provider, but extensive use is made of Spring LDAP, so some familiarity with that project may be useful if you plan on adding your own customizations.

When using LDAP authentication, it is important to ensure that you configure LDAP connection pooling properly. If you are unfamiliar with how to do this, you can refer to the Java LDAP documentation.

10.3.2 Using LDAP with Spring Security

LDAP authentication in Spring Security can be roughly divided into the following stages.

  • Obtaining the unique LDAP "Distinguished Name", or DN, from the login name. This will often mean performing a search in the directory, unless the exact mapping of usernames to DNs is known in advance. So a user might enter the name "joe" when logging in, but the actual name used to authenticate to LDAP will be the full DN, such as uid=joe,ou=users,dc=spring,dc=io.
  • Authenticating the user, either by "binding" as that user or by performing a remote "compare" operation of the user’s password against the password attribute in the directory entry for the DN.
  • Loading the list of authorities for the user.

The exception is when the LDAP directory is just being used to retrieve user information and authenticate against it locally. This may not be possible as directories are often set up with limited read access for attributes such as user passwords.

We will look at some configuration scenarios below. For full information on available configuration options, please consult the security namespace schema (information from which should be available in your XML editor).

10.4 Configuring an LDAP Server

The first thing you need to do is configure the server against which authentication should take place. This is done using the <ldap-server> element from the security namespace. This can be configured to point at an external LDAP server, using the url attribute:

<ldap-server url="ldap://springframework.org:389/dc=springframework,dc=org" />
[Note]Note

spring-security provides integration with apacheds and unboundid as a embedded ldap servers. You can choose between them using the attribute mode in ldap-server.

10.4.1 Using an Embedded Test Server

The <ldap-server> element can also be used to create an embedded server, which can be very useful for testing and demonstrations. In this case you use it without the url attribute:

<ldap-server root="dc=springframework,dc=org"/>

Here we’ve specified that the root DIT of the directory should be "dc=springframework,dc=org", which is the default. Used this way, the namespace parser will create an embedded Apache Directory server and scan the classpath for any LDIF files, which it will attempt to load into the server. You can customize this behaviour using the ldif attribute, which defines an LDIF resource to be loaded:

<ldap-server ldif="classpath:users.ldif" />

This makes it a lot easier to get up and running with LDAP, since it can be inconvenient to work all the time with an external server. It also insulates the user from the complex bean configuration needed to wire up an Apache Directory server. Using plain Spring Beans the configuration would be much more cluttered. You must have the necessary Apache Directory dependency jars available for your application to use. These can be obtained from the LDAP sample application.

10.4.2 Using Bind Authentication

This is the most common LDAP authentication scenario.

<ldap-authentication-provider user-dn-pattern="uid={0},ou=people"/>

This simple example would obtain the DN for the user by substituting the user login name in the supplied pattern and attempting to bind as that user with the login password. This is OK if all your users are stored under a single node in the directory. If instead you wished to configure an LDAP search filter to locate the user, you could use the following:

<ldap-authentication-provider user-search-filter="(uid={0})"
        user-search-base="ou=people"/>

If used with the server definition above, this would perform a search under the DN ou=people,dc=springframework,dc=org using the value of the user-search-filter attribute as a filter. Again the user login name is substituted for the parameter in the filter name, so it will search for an entry with the uid attribute equal to the user name. If user-search-base isn’t supplied, the search will be performed from the root.

10.4.3 Loading Authorities

How authorities are loaded from groups in the LDAP directory is controlled by the following attributes.

  • group-search-base. Defines the part of the directory tree under which group searches should be performed.
  • group-role-attribute. The attribute which contains the name of the authority defined by the group entry. Defaults to cn
  • group-search-filter. The filter which is used to search for group membership. The default is uniqueMember={0}, corresponding to the groupOfUniqueNames LDAP class [2]. In this case, the substituted parameter is the full distinguished name of the user. The parameter {1} can be used if you want to filter on the login name.

So if we used the following configuration

<ldap-authentication-provider user-dn-pattern="uid={0},ou=people"
        group-search-base="ou=groups" />

and authenticated successfully as user "ben", the subsequent loading of authorities would perform a search under the directory entry ou=groups,dc=springframework,dc=org, looking for entries which contain the attribute uniqueMember with value uid=ben,ou=people,dc=springframework,dc=org. By default the authority names will have the prefix ROLE_ prepended. You can change this using the role-prefix attribute. If you don’t want any prefix, use role-prefix="none". For more information on loading authorities, see the Javadoc for the DefaultLdapAuthoritiesPopulator class.

10.5 Implementation Classes

The namespace configuration options we’ve used above are simple to use and much more concise than using Spring beans explicitly. There are situations when you may need to know how to configure Spring Security LDAP directly in your application context. You may wish to customize the behaviour of some of the classes, for example. If you’re happy using namespace configuration then you can skip this section and the next one.

The main LDAP provider class, LdapAuthenticationProvider, doesn’t actually do much itself but delegates the work to two other beans, an LdapAuthenticator and an LdapAuthoritiesPopulator which are responsible for authenticating the user and retrieving the user’s set of GrantedAuthority s respectively.

10.5.1 LdapAuthenticator Implementations

The authenticator is also responsible for retrieving any required user attributes. This is because the permissions on the attributes may depend on the type of authentication being used. For example, if binding as the user, it may be necessary to read them with the user’s own permissions.

There are currently two authentication strategies supplied with Spring Security:

  • Authentication directly to the LDAP server ("bind" authentication).
  • Password comparison, where the password supplied by the user is compared with the one stored in the repository. This can either be done by retrieving the value of the password attribute and checking it locally or by performing an LDAP "compare" operation, where the supplied password is passed to the server for comparison and the real password value is never retrieved.

Common Functionality

Before it is possible to authenticate a user (by either strategy), the distinguished name (DN) has to be obtained from the login name supplied to the application. This can be done either by simple pattern-matching (by setting the setUserDnPatterns array property) or by setting the userSearch property. For the DN pattern-matching approach, a standard Java pattern format is used, and the login name will be substituted for the parameter {0}. The pattern should be relative to the DN that the configured SpringSecurityContextSource will bind to (see the section on connecting to the LDAP server for more information on this). For example, if you are using an LDAP server with the URL ldap://monkeymachine.co.uk/dc=springframework,dc=org, and have a pattern uid={0},ou=greatapes, then a login name of "gorilla" will map to a DN uid=gorilla,ou=greatapes,dc=springframework,dc=org. Each configured DN pattern will be tried in turn until a match is found. For information on using a search, see the section on search objects below. A combination of the two approaches can also be used - the patterns will be checked first and if no matching DN is found, the search will be used.

BindAuthenticator

The class BindAuthenticator in the package org.springframework.security.ldap.authentication implements the bind authentication strategy. It simply attempts to bind as the user.

PasswordComparisonAuthenticator

The class PasswordComparisonAuthenticator implements the password comparison authentication strategy.

10.5.2 Connecting to the LDAP Server

The beans discussed above have to be able to connect to the server. They both have to be supplied with a SpringSecurityContextSource which is an extension of Spring LDAP’s ContextSource. Unless you have special requirements, you will usually configure a DefaultSpringSecurityContextSource bean, which can be configured with the URL of your LDAP server and optionally with the username and password of a "manager" user which will be used by default when binding to the server (instead of binding anonymously). For more information read the Javadoc for this class and for Spring LDAP’s AbstractContextSource.

10.5.3 LDAP Search Objects

Often a more complicated strategy than simple DN-matching is required to locate a user entry in the directory. This can be encapsulated in an LdapUserSearch instance which can be supplied to the authenticator implementations, for example, to allow them to locate a user. The supplied implementation is FilterBasedLdapUserSearch.

FilterBasedLdapUserSearch

This bean uses an LDAP filter to match the user object in the directory. The process is explained in the Javadoc for the corresponding search method on the JDK DirContext class. As explained there, the search filter can be supplied with parameters. For this class, the only valid parameter is {0} which will be replaced with the user’s login name.

10.5.4 LdapAuthoritiesPopulator

After authenticating the user successfully, the LdapAuthenticationProvider will attempt to load a set of authorities for the user by calling the configured LdapAuthoritiesPopulator bean. The DefaultLdapAuthoritiesPopulator is an implementation which will load the authorities by searching the directory for groups of which the user is a member (typically these will be groupOfNames or groupOfUniqueNames entries in the directory). Consult the Javadoc for this class for more details on how it works.

If you want to use LDAP only for authentication, but load the authorities from a difference source (such as a database) then you can provide your own implementation of this interface and inject that instead.

10.5.5 Spring Bean Configuration

A typical configuration, using some of the beans we’ve discussed here, might look like this:

<bean id="contextSource"
        class="org.springframework.security.ldap.DefaultSpringSecurityContextSource">
    <constructor-arg value="ldap://monkeymachine:389/dc=springframework,dc=org"/>
    <property name="userDn" value="cn=manager,dc=springframework,dc=org"/>
    <property name="password" value="password"/>
</bean>

<bean id="ldapAuthProvider"
        class="org.springframework.security.ldap.authentication.LdapAuthenticationProvider">
    <constructor-arg>
        <bean class="org.springframework.security.ldap.authentication.BindAuthenticator">
            <constructor-arg ref="contextSource"/>
            <property name="userDnPatterns">
                <list><value>uid={0},ou=people</value></list>
            </property>
        </bean>
    </constructor-arg>
    <constructor-arg>
        <bean class="org.springframework.security.ldap.userdetails.DefaultLdapAuthoritiesPopulator">
            <constructor-arg ref="contextSource"/>
            <constructor-arg value="ou=groups"/>
            <property name="groupRoleAttribute" value="ou"/>
        </bean>
    </constructor-arg>
</bean>

This would set up the provider to access an LDAP server with URL ldap://monkeymachine:389/dc=springframework,dc=org. Authentication will be performed by attempting to bind with the DN uid=<user-login-name>,ou=people,dc=springframework,dc=org. After successful authentication, roles will be assigned to the user by searching under the DN ou=groups,dc=springframework,dc=org with the default filter (member=<user’s-DN>). The role name will be taken from the "ou" attribute of each match.

To configure a user search object, which uses the filter (uid=<user-login-name>) for use instead of the DN-pattern (or in addition to it), you would configure the following bean

<bean id="userSearch"
        class="org.springframework.security.ldap.search.FilterBasedLdapUserSearch">
    <constructor-arg index="0" value=""/>
    <constructor-arg index="1" value="(uid={0})"/>
    <constructor-arg index="2" ref="contextSource" />
</bean>

and use it by setting the BindAuthenticator bean’s userSearch property. The authenticator would then call the search object to obtain the correct user’s DN before attempting to bind as this user.

10.5.6 LDAP Attributes and Customized UserDetails

The net result of an authentication using LdapAuthenticationProvider is the same as a normal Spring Security authentication using the standard UserDetailsService interface. A UserDetails object is created and stored in the returned Authentication object. As with using a UserDetailsService, a common requirement is to be able to customize this implementation and add extra properties. When using LDAP, these will normally be attributes from the user entry. The creation of the UserDetails object is controlled by the provider’s UserDetailsContextMapper strategy, which is responsible for mapping user objects to and from LDAP context data:

public interface UserDetailsContextMapper {

    UserDetails mapUserFromContext(DirContextOperations ctx, String username,
            Collection<GrantedAuthority> authorities);

    void mapUserToContext(UserDetails user, DirContextAdapter ctx);
}

Only the first method is relevant for authentication. If you provide an implementation of this interface and inject it into the LdapAuthenticationProvider, you have control over exactly how the UserDetails object is created. The first parameter is an instance of Spring LDAP’s DirContextOperations which gives you access to the LDAP attributes which were loaded during authentication. The username parameter is the name used to authenticate and the final parameter is the collection of authorities loaded for the user by the configured LdapAuthoritiesPopulator.

The way the context data is loaded varies slightly depending on the type of authentication you are using. With the BindAuthenticator, the context returned from the bind operation will be used to read the attributes, otherwise the data will be read using the standard context obtained from the configured ContextSource (when a search is configured to locate the user, this will be the data returned by the search object).

10.6 Active Directory Authentication

Active Directory supports its own non-standard authentication options, and the normal usage pattern doesn’t fit too cleanly with the standard LdapAuthenticationProvider. Typically authentication is performed using the domain username (in the form [email protected]), rather than using an LDAP distinguished name. To make this easier, Spring Security 3.1 has an authentication provider which is customized for a typical Active Directory setup.

10.6.1 ActiveDirectoryLdapAuthenticationProvider

Configuring ActiveDirectoryLdapAuthenticationProvider is quite straightforward. You just need to supply the domain name and an LDAP URL supplying the address of the server [3]. An example configuration would then look like this:

<bean id="adAuthenticationProvider"
        class="org.springframework.security.ldap.authentication.ad.ActiveDirectoryLdapAuthenticationProvider">
    <constructor-arg value="mydomain.com" />
    <constructor-arg value="ldap://adserver.mydomain.com/" />
</bean>

Note that there is no need to specify a separate ContextSource in order to define the server location - the bean is completely self-contained. A user named "Sharon", for example, would then be able to authenticate by entering either the username sharon or the full Active Directory userPrincipalName, namely [email protected]. The user’s directory entry will then be located, and the attributes returned for possible use in customizing the created UserDetails object (a UserDetailsContextMapper can be injected for this purpose, as described above). All interaction with the directory takes place with the identity of the user themselves. There is no concept of a "manager" user.

By default, the user authorities are obtained from the memberOf attribute values of the user entry. The authorities allocated to the user can again be customized using a UserDetailsContextMapper. You can also inject a GrantedAuthoritiesMapper into the provider instance to control the authorities which end up in the Authentication object.

Active Directory Error Codes

By default, a failed result will cause a standard Spring Security BadCredentialsException. If you set the property convertSubErrorCodesToExceptions to true, the exception messages will be parsed to attempt to extract the Active Directory-specific error code and raise a more specific exception. Check the class Javadoc for more information.

10.7 LDAP Java Configuration

You can find the updates to support LDAP based authentication. The ldap-javaconfig sample provides a complete example of using LDAP based authentication.

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
    auth
        .ldapAuthentication()
            .userDnPatterns("uid={0},ou=people")
            .groupSearchBase("ou=groups");
}

The example above uses the following LDIF and an embedded Apache DS LDAP instance.

users.ldif. 

dn: ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: organizationalUnit
ou: groups

dn: ou=people,dc=springframework,dc=org
objectclass: top
objectclass: organizationalUnit
ou: people

dn: uid=admin,ou=people,dc=springframework,dc=org
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Rod Johnson
sn: Johnson
uid: admin
userPassword: password

dn: uid=user,ou=people,dc=springframework,dc=org
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Dianne Emu
sn: Emu
uid: user
userPassword: password

dn: cn=user,ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: groupOfNames
cn: user
uniqueMember: uid=admin,ou=people,dc=springframework,dc=org
uniqueMember: uid=user,ou=people,dc=springframework,dc=org

dn: cn=admin,ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: groupOfNames
cn: admin
uniqueMember: uid=admin,ou=people,dc=springframework,dc=org

10.8 AuthenticationProvider

10.8.1 AuthenticationProvider Java Configuration

You can define custom authentication by exposing a custom AuthenticationProvider as a bean. For example, the following will customize authentication assuming that SpringAuthenticationProvider implements AuthenticationProvider:

[Note]Note

This is only used if the AuthenticationManagerBuilder has not been populated

@Bean
public SpringAuthenticationProvider springAuthenticationProvider() {
    return new SpringAuthenticationProvider();
}

10.8.2 AuthenticationProvider XML Configuration

In practice you will need a more scalable source of user information than a few names added to the application context file. Most likely you will want to store your user information in something like a database or an LDAP server. LDAP namespace configuration is dealt with in the LDAP chapter, so we won’t cover it here. If you have a custom implementation of Spring Security’s UserDetailsService, called "myUserDetailsService" in your application context, then you can authenticate against this using

<authentication-manager>
    <authentication-provider user-service-ref='myUserDetailsService'/>
</authentication-manager>

If you want to use a database, then you can use

<authentication-manager>
<authentication-provider>
    <jdbc-user-service data-source-ref="securityDataSource"/>
</authentication-provider>
</authentication-manager>

Where "securityDataSource" is the name of a DataSource bean in the application context, pointing at a database containing the standard Spring Security user data tables. Alternatively, you could configure a Spring Security JdbcDaoImpl bean and point at that using the user-service-ref attribute:

<authentication-manager>
<authentication-provider user-service-ref='myUserDetailsService'/>
</authentication-manager>

<beans:bean id="myUserDetailsService"
    class="org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl">
<beans:property name="dataSource" ref="dataSource"/>
</beans:bean>

You can also use standard AuthenticationProvider beans as follows

<authentication-manager>
    <authentication-provider ref='myAuthenticationProvider'/>
</authentication-manager>

where myAuthenticationProvider is the name of a bean in your application context which implements AuthenticationProvider. You can use multiple authentication-provider elements, in which case the providers will be queried in the order they are declared. See Section 10.11, “The Authentication Manager and the Namespace” for more information on how the Spring Security AuthenticationManager is configured using the namespace.

10.9 UserDetailsService

You can define custom authentication by exposing a custom UserDetailsService as a bean. For example, the following will customize authentication assuming that SpringDataUserDetailsService implements UserDetailsService:

[Note]Note

This is only used if the AuthenticationManagerBuilder has not been populated and no AuthenticationProviderBean is defined.

@Bean
public SpringDataUserDetailsService springDataUserDetailsService() {
    return new SpringDataUserDetailsService();
}

You can also customize how passwords are encoded by exposing a PasswordEncoder as a bean. For example, if you use bcrypt you can add a bean definition as shown below:

@Bean
public BCryptPasswordEncoder passwordEncoder() {
    return new BCryptPasswordEncoder();
}

10.10 Password Encoding

Spring Security’s PasswordEncoder interface is used to perform a one way transformation of a password to allow the password to be stored securely. Given PasswordEncoder is a one way transformation, it is not intended when the password transformation needs to be two way (i.e. storing credentials used to authenticate to a database). Typically PasswordEncoder is used for storing a password that needs to be compared to a user provided password at the time of authentication.

10.10.1 Password History

Throughout the years the standard mechanism for storing passwords has evolved. In the beginning passwords were stored in plain text. The passwords were assumed to be safe because the data store the passwords were saved in required credentials to access it. However, malicious users were able to find ways to get large "data dumps" of usernames and passwords using attacks like SQL Injection. As more and more user credentials became public security experts realized we needed to do more to protect users passwords.

Developers were then encouraged to store passwords after running them through a one way hash such as SHA-256. When a user tried to authenticate, the hashed password would be compared to the hash of the password that they typed. This meant that the system only needed to store the one way hash of the password. If a breach occurred, then only the one way hashes of the passwords were exposed. Since the hashes were one way and it was computationally difficult to guess the passwords given the hash, it would not be worth the effort to figure out each password in the system. To defeat this new system malicious users decided to create lookup tables known as Rainbow Tables. Rather than doing the work of guessing each password every time, they computed the password once and stored it in a lookup table.

To mitigate the effectiveness of Rainbow Tables, developers were encouraged to use salted passwords. Instead of using just the password as input to the hash function, random bytes (known as salt) would be generated for every users' password. The salt and the user’s password would be ran through the hash function which produced a unique hash. The salt would be stored alongside the user’s password in clear text. Then when a user tried to authenticate, the hashed password would be compared to the hash of the stored salt and the password that they typed. The unique salt meant that Rainbow Tables were no longer effective because the hash was different for every salt and password combination.

In modern times we realize that cryptographic hashes (like SHA-256) are no longer secure. The reason is that with modern hardware we can perform billions of hash calculations a second. This means that we can crack each password individually with ease.

Developers are now encouraged to leverage adaptive one-way functions to store a password. Validation of passwords with adaptive one-way functions are intentionally resource (i.e. CPU, memory, etc) intensive. An adaptive one-way function allows configuring a "work factor" which can grow as hardware gets better. It is recommended that the "work factor" be tuned to take about 1 second to verify a password on your system. This trade off is to make it difficult for attackers to crack the password, but not so costly it puts excessive burden on your own system. Spring Security has attempted to provide a good starting point for the "work factor", but users are encouraged to customize the "work factor" for their own system since the performance will vary drastically from system to system. Examples of adaptive one-way functions that should be used include bcrypt, PBKDF2, scrypt, and Argon2.

Because adaptive one-way functions are intentionally resource intensive, validating a username and password for every request will degrade performance of an application significantly. There is nothing Spring Security (or any other library) can do to speed up the validation of the password since security is gained by making the validation resource intensive. Users are encouraged to exchange the long term credentials (i.e. username and password) for a short term credential (i.e. session, OAuth Token, etc). The short term credential can be validated quickly without any loss in security.

10.10.2 DelegatingPasswordEncoder

Prior to Spring Security 5.0 the default PasswordEncoder was NoOpPasswordEncoder which required plain text passwords. Based upon the Password History section you might expect that the default PasswordEncoder is now something like BCryptPasswordEncoder. However, this ignores three real world problems:

  • There are many applications using old password encodings that cannot easily migrate
  • The best practice for password storage will change again.
  • As a framework Spring Security cannot make breaking changes frequently

Instead Spring Security introduces DelegatingPasswordEncoder which solves all of the problems by:

  • Ensuring that passwords are encoded using the current password storage recommendations
  • Allowing for validating passwords in modern and legacy formats
  • Allowing for upgrading the encoding in the future

You can easily construct an instance of DelegatingPasswordEncoder using PasswordEncoderFactories.

PasswordEncoder passwordEncoder =
    PasswordEncoderFactories.createDelegatingPasswordEncoder();

Alternatively, you may create your own custom instance. For example:

String idForEncode = "bcrypt";
Map encoders = new HashMap<>();
encoders.put(idForEncode, new BCryptPasswordEncoder());
encoders.put("noop", NoOpPasswordEncoder.getInstance());
encoders.put("pbkdf2", new Pbkdf2PasswordEncoder());
encoders.put("scrypt", new SCryptPasswordEncoder());
encoders.put("sha256", new StandardPasswordEncoder());

PasswordEncoder passwordEncoder =
    new DelegatingPasswordEncoder(idForEncode, encoders);

Password Storage Format

The general format for a password is:

{id}encodedPassword

Such that id is an identifier used to look up which PasswordEncoder should be used and encodedPassword is the original encoded password for the selected PasswordEncoder. The id must be at the beginning of the password, start with { and end with }. If the id cannot be found, the id will be null. For example, the following might be a list of passwords encoded using different id. All of the original passwords are "password".

{bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG 1
{noop}password 2
{pbkdf2}5d923b44a6d129f3ddf3e3c8d29412723dcbde72445e8ef6bf3b508fbf17fa4ed4d6b99ca763d8dc 3
{scrypt}$e0801$8bWJaSu2IKSn9Z9kM+TPXfOc/9bdYSrN1oD9qfVThWEwdRTnO7re7Ei+fUZRJ68k9lTyuTeUp4of4g24hHnazw==$OAOec05+bXxvuu/1qZ6NUR+xQYvYv7BeL1QxwRpY5Pc=  4
{sha256}97cde38028ad898ebc02e690819fa220e88c62e0699403e94fff291cfffaf8410849f27605abcbc0 5

1

The first password would have a PasswordEncoder id of bcrypt and encodedPassword of $2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG. When matching it would delegate to BCryptPasswordEncoder

2

The second password would have a PasswordEncoder id of noop and encodedPassword of password. When matching it would delegate to NoOpPasswordEncoder

3

The third password would have a PasswordEncoder id of pbkdf2 and encodedPassword of 5d923b44a6d129f3ddf3e3c8d29412723dcbde72445e8ef6bf3b508fbf17fa4ed4d6b99ca763d8dc. When matching it would delegate to Pbkdf2PasswordEncoder

4

The fourth password would have a PasswordEncoder id of scrypt and encodedPassword of $e0801$8bWJaSu2IKSn9Z9kM+TPXfOc/9bdYSrN1oD9qfVThWEwdRTnO7re7Ei+fUZRJ68k9lTyuTeUp4of4g24hHnazw==$OAOec05+bXxvuu/1qZ6NUR+xQYvYv7BeL1QxwRpY5Pc= When matching it would delegate to SCryptPasswordEncoder

5

The final password would have a PasswordEncoder id of sha256 and encodedPassword of 97cde38028ad898ebc02e690819fa220e88c62e0699403e94fff291cfffaf8410849f27605abcbc0. When matching it would delegate to StandardPasswordEncoder

[Note]Note

Some users might be concerned that the storage format is provided for a potential hacker. This is not a concern because the storage of the password does not rely on the algorithm being a secret. Additionally, most formats are easy for an attacker to figure out without the prefix. For example, BCrypt passwords often start with $2a$.

Password Encoding

The idForEncode passed into the constructor determines which PasswordEncoder will be used for encoding passwords. In the DelegatingPasswordEncoder we constructed above, that means that the result of encoding password would be delegated to BCryptPasswordEncoder and be prefixed with {bcrypt}. The end result would look like:

{bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

Password Matching

Matching is done based upon the {id} and the mapping of the id to the PasswordEncoder provided in the constructor. Our example in the section called “Password Storage Format” provides a working example of how this is done. By default, the result of invoking matches(CharSequence, String) with a password and an id that is not mapped (including a null id) will result in an IllegalArgumentException. This behavior can be customized using DelegatingPasswordEncoder.setDefaultPasswordEncoderForMatches(PasswordEncoder).

By using the id we can match on any password encoding, but encode passwords using the most modern password encoding. This is important, because unlike encryption, password hashes are designed so that there is no simple way to recover the plaintext. Since there is no way to recover the plaintext, it makes it difficult to migrate the passwords. While it is simple for users to migrate NoOpPasswordEncoder, we chose to include it by default to make it simple for the getting started experience.

Getting Started Experience

If you are putting together a demo or a sample, it is a bit cumbersome to take time to hash the passwords of your users. There are convenience mechanisms to make this easier, but this is still not intended for production.

User user = User.withDefaultPasswordEncoder()
  .username("user")
  .password("password")
  .roles("user")
  .build();
System.out.println(user.getPassword());
// {bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

If you are creating multiple users, you can also reuse the builder.

UserBuilder users = User.withDefaultPasswordEncoder();
User user = users
  .username("user")
  .password("password")
  .roles("USER")
  .build();
User admin = users
  .username("admin")
  .password("password")
  .roles("USER","ADMIN")
  .build();

This does hash the password that is stored, but the passwords are still exposed in memory and in the compiled source code. Therefore, it is still not considered secure for a production environment. For production, you should hash your passwords externally.

Troubleshooting

The following error occurs when one of the passwords that are stored has no id as described in the section called “Password Storage Format”.

java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"
    at org.springframework.security.crypto.password.DelegatingPasswordEncoder$UnmappedIdPasswordEncoder.matches(DelegatingPasswordEncoder.java:233)
    at org.springframework.security.crypto.password.DelegatingPasswordEncoder.matches(DelegatingPasswordEncoder.java:196)

The easiest way to resolve the error is to switch to explicitly provide the PasswordEncoder that you passwords are encoded with. The easiest way to resolve it is to figure out how your passwords are currently being stored and explicitly provide the correct PasswordEncoder. If you are migrating from Spring Security 4.2.x you can revert to the previous behavior by exposing a NoOpPasswordEncoder bean. For example, if you are using Java Configuration, you can create a configuration that looks like:

[Warning]Warning

Reverting to NoOpPasswordEncoder is not considered to be secure. You should instead migrate to using DelegatingPasswordEncoder to support secure password encoding.

@Bean
public static NoOpPasswordEncoder passwordEncoder() {
    return NoOpPasswordEncoder.getInstance();
}

if you are using XML configuration, you can expose a PasswordEncoder with the id passwordEncoder:

<b:bean id="passwordEncoder"
        class="org.springframework.security.crypto.password.NoOpPasswordEncoder" factory-method="getInstance"/>

Alternatively, you can prefix all of your passwords with the correct id and continue to use DelegatingPasswordEncoder. For example, if you are using BCrypt, you would migrate your password from something like:

$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

to

{bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

For a complete listing of the mappings refer to the Javadoc on PasswordEncoderFactories.

10.10.3 BCryptPasswordEncoder

The BCryptPasswordEncoder implementation uses the widely supported bcrypt algorithm to hash the passwords. In order to make it more resistent to password cracking, bcrypt is deliberately slow. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.

// Create an encoder with strength 16
BCryptPasswordEncoder encoder = new BCryptPasswordEncoder(16);
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

10.10.4 Argon2PasswordEncoder

The Argon2PasswordEncoder implementation uses the Argon2 algorithm to hash the passwords. Argon2 is the winner of the Password Hashing Competition. In order to defeat password cracking on custom hardware, Argon2 is a deliberately slow algorithm that requires large amounts of memory. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system. The current implementation if the Argon2PasswordEncoder requires BouncyCastle.

// Create an encoder with all the defaults
Argon2PasswordEncoder encoder = new Argon2PasswordEncoder();
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

10.10.5 Pbkdf2PasswordEncoder

The Pbkdf2PasswordEncoder implementation uses the PBKDF2 algorithm to hash the passwords. In order to defeat password cracking PBKDF2 is a deliberately slow algorithm. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system. This algorithm is a good choice when FIPS certification is required.

// Create an encoder with all the defaults
Pbkdf2PasswordEncoder encoder = new Pbkdf2PasswordEncoder();
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

10.10.6 SCryptPasswordEncoder

The SCryptPasswordEncoder implementation uses scrypt algorithm to hash the passwords. In order to defeat password cracking on custom hardware scrypt is a deliberately slow algorithm that requires large amounts of memory. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.

// Create an encoder with all the defaults
SCryptPasswordEncoder encoder = new SCryptPasswordEncoder();
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

10.10.7 Other PasswordEncoders

There are a significant number of other PasswordEncoder implementations that exist entirely for backward compatibility. They are all deprecated to indicate that they are no longer considered secure. However, there are no plans to remove them since it is difficult to migrate existing legacy systems.

10.10.8 Password Encoder XML Configuration

Passwords should always be encoded using a secure hashing algorithm designed for the purpose (not a standard algorithm like SHA or MD5). This is supported by the <password-encoder> element. With bcrypt encoded passwords, the original authentication provider configuration would look like this:

<beans:bean name="bcryptEncoder"
    class="org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder"/>

<authentication-manager>
<authentication-provider>
    <password-encoder ref="bcryptEncoder"/>
    <user-service>
    <user name="jimi" password="$2a$10$ddEWZUl8aU0GdZPPpy7wbu82dvEw/pBpbRvDQRqA41y6mK1CoH00m"
            authorities="ROLE_USER, ROLE_ADMIN" />
    <user name="bob" password="$2a$10$/elFpMBnAYYig6KRR5bvOOYeZr1ie1hSogJryg9qDlhza4oCw1Qka"
            authorities="ROLE_USER" />
    </user-service>
</authentication-provider>
</authentication-manager>

bcrypt is a good choice for most cases, unless you have a legacy system which forces you to use a different algorithm. If you are using a simple hashing algorithm or, even worse, storing plain text passwords, then you should consider migrating to a more secure option like bcrypt.

10.11 The Authentication Manager and the Namespace

The main interface which provides authentication services in Spring Security is the AuthenticationManager. This is usually an instance of Spring Security’s ProviderManager class, which you may already be familiar with if you’ve used the framework before. If not, it will be covered later, in the technical overview chapter. The bean instance is registered using the authentication-manager namespace element. You can’t use a custom AuthenticationManager if you are using either HTTP or method security through the namespace, but this should not be a problem as you have full control over the AuthenticationProvider s that are used.

You may want to register additional AuthenticationProvider beans with the ProviderManager and you can do this using the <authentication-provider> element with the ref attribute, where the value of the attribute is the name of the provider bean you want to add. For example:

<authentication-manager>
<authentication-provider ref="casAuthenticationProvider"/>
</authentication-manager>

<bean id="casAuthenticationProvider"
    class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
...
</bean>

Another common requirement is that another bean in the context may require a reference to the AuthenticationManager. You can easily register an alias for the AuthenticationManager and use this name elsewhere in your application context.

<security:authentication-manager alias="authenticationManager">
...
</security:authentication-manager>

<bean id="customizedFormLoginFilter"
    class="com.somecompany.security.web.CustomFormLoginFilter">
<property name="authenticationManager" ref="authenticationManager"/>
...
</bean>

10.12 Session Management

HTTP session related functionality is handled by a combination of the SessionManagementFilter and the SessionAuthenticationStrategy interface, which the filter delegates to. Typical usage includes session-fixation protection attack prevention, detection of session timeouts and restrictions on how many sessions an authenticated user may have open concurrently.

10.12.1 Detecting Timeouts

You can configure Spring Security to detect the submission of an invalid session ID and redirect the user to an appropriate URL. This is achieved through the session-management element:

<http>
...
<session-management invalid-session-url="/invalidSession.htm" />
</http>

Note that if you use this mechanism to detect session timeouts, it may falsely report an error if the user logs out and then logs back in without closing the browser. This is because the session cookie is not cleared when you invalidate the session and will be resubmitted even if the user has logged out. You may be able to explicitly delete the JSESSIONID cookie on logging out, for example by using the following syntax in the logout handler:

<http>
<logout delete-cookies="JSESSIONID" />
</http>

Unfortunately this can’t be guaranteed to work with every servlet container, so you will need to test it in your environment

[Note]Note

=== If you are running your application behind a proxy, you may also be able to remove the session cookie by configuring the proxy server. For example, using Apache HTTPD’s mod_headers, the following directive would delete the JSESSIONID cookie by expiring it in the response to a logout request (assuming the application is deployed under the path /tutorial):

<LocationMatch "/tutorial/logout">
Header always set Set-Cookie "JSESSIONID=;Path=/tutorial;Expires=Thu, 01 Jan 1970 00:00:00 GMT"
</LocationMatch>

===

10.12.2 Concurrent Session Control

If you wish to place constraints on a single user’s ability to log in to your application, Spring Security supports this out of the box with the following simple additions. First you need to add the following listener to your web.xml file to keep Spring Security updated about session lifecycle events:

<listener>
<listener-class>
    org.springframework.security.web.session.HttpSessionEventPublisher
</listener-class>
</listener>

Then add the following lines to your application context:

<http>
...
<session-management>
    <concurrency-control max-sessions="1" />
</session-management>
</http>

This will prevent a user from logging in multiple times - a second login will cause the first to be invalidated. Often you would prefer to prevent a second login, in which case you can use

<http>
...
<session-management>
    <concurrency-control max-sessions="1" error-if-maximum-exceeded="true" />
</session-management>
</http>

The second login will then be rejected. By "rejected", we mean that the user will be sent to the authentication-failure-url if form-based login is being used. If the second authentication takes place through another non-interactive mechanism, such as "remember-me", an "unauthorized" (401) error will be sent to the client. If instead you want to use an error page, you can add the attribute session-authentication-error-url to the session-management element.

If you are using a customized authentication filter for form-based login, then you have to configure concurrent session control support explicitly. More details can be found in the Session Management chapter.

10.12.3 Session Fixation Attack Protection

Session fixation attacks are a potential risk where it is possible for a malicious attacker to create a session by accessing a site, then persuade another user to log in with the same session (by sending them a link containing the session identifier as a parameter, for example). Spring Security protects against this automatically by creating a new session or otherwise changing the session ID when a user logs in. If you don’t require this protection, or it conflicts with some other requirement, you can control the behavior using the session-fixation-protection attribute on <session-management>, which has four options

  • none - Don’t do anything. The original session will be retained.
  • newSession - Create a new "clean" session, without copying the existing session data (Spring Security-related attributes will still be copied).
  • migrateSession - Create a new session and copy all existing session attributes to the new session. This is the default in Servlet 3.0 or older containers.
  • changeSessionId - Do not create a new session. Instead, use the session fixation protection provided by the Servlet container (HttpServletRequest#changeSessionId()). This option is only available in Servlet 3.1 (Java EE 7) and newer containers. Specifying it in older containers will result in an exception. This is the default in Servlet 3.1 and newer containers.

When session fixation protection occurs, it results in a SessionFixationProtectionEvent being published in the application context. If you use changeSessionId, this protection will also result in any javax.servlet.http.HttpSessionIdListener s being notified, so use caution if your code listens for both events. See the Session Management chapter for additional information.

10.12.4 SessionManagementFilter

The SessionManagementFilter checks the contents of the SecurityContextRepository against the current contents of the SecurityContextHolder to determine whether a user has been authenticated during the current request, typically by a non-interactive authentication mechanism, such as pre-authentication or remember-me [4]. If the repository contains a security context, the filter does nothing. If it doesn’t, and the thread-local SecurityContext contains a (non-anonymous) Authentication object, the filter assumes they have been authenticated by a previous filter in the stack. It will then invoke the configured SessionAuthenticationStrategy.

If the user is not currently authenticated, the filter will check whether an invalid session ID has been requested (because of a timeout, for example) and will invoke the configured InvalidSessionStrategy, if one is set. The most common behaviour is just to redirect to a fixed URL and this is encapsulated in the standard implementation SimpleRedirectInvalidSessionStrategy. The latter is also used when configuring an invalid session URL through the namespace,as described earlier.

10.12.5 SessionAuthenticationStrategy

SessionAuthenticationStrategy is used by both SessionManagementFilter and AbstractAuthenticationProcessingFilter, so if you are using a customized form-login class, for example, you will need to inject it into both of these. In this case, a typical configuration, combining the namespace and custom beans might look like this:

<http>
<custom-filter position="FORM_LOGIN_FILTER" ref="myAuthFilter" />
<session-management session-authentication-strategy-ref="sas"/>
</http>

<beans:bean id="myAuthFilter" class=
"org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter">
    <beans:property name="sessionAuthenticationStrategy" ref="sas" />
    ...
</beans:bean>

<beans:bean id="sas" class=
"org.springframework.security.web.authentication.session.SessionFixationProtectionStrategy" />

Note that the use of the default, SessionFixationProtectionStrategy may cause issues if you are storing beans in the session which implement HttpSessionBindingListener, including Spring session-scoped beans. See the Javadoc for this class for more information.

10.12.6 Concurrency Control

Spring Security is able to prevent a principal from concurrently authenticating to the same application more than a specified number of times. Many ISVs take advantage of this to enforce licensing, whilst network administrators like this feature because it helps prevent people from sharing login names. You can, for example, stop user "Batman" from logging onto the web application from two different sessions. You can either expire their previous login or you can report an error when they try to log in again, preventing the second login. Note that if you are using the second approach, a user who has not explicitly logged out (but who has just closed their browser, for example) will not be able to log in again until their original session expires.

Concurrency control is supported by the namespace, so please check the earlier namespace chapter for the simplest configuration. Sometimes you need to customize things though.

The implementation uses a specialized version of SessionAuthenticationStrategy, called ConcurrentSessionControlAuthenticationStrategy.

[Note]Note

Previously the concurrent authentication check was made by the ProviderManager, which could be injected with a ConcurrentSessionController. The latter would check if the user was attempting to exceed the number of permitted sessions. However, this approach required that an HTTP session be created in advance, which is undesirable. In Spring Security 3, the user is first authenticated by the AuthenticationManager and once they are successfully authenticated, a session is created and the check is made whether they are allowed to have another session open.

To use concurrent session support, you’ll need to add the following to web.xml:

<listener>
    <listener-class>
    org.springframework.security.web.session.HttpSessionEventPublisher
    </listener-class>
</listener>

In addition, you will need to add the ConcurrentSessionFilter to your FilterChainProxy. The ConcurrentSessionFilter requires two constructor arguments, sessionRegistry, which generally points to an instance of SessionRegistryImpl, and sessionInformationExpiredStrategy, which defines the strategy to apply when a session has expired. A configuration using the namespace to create the FilterChainProxy and other default beans might look like this:

<http>
<custom-filter position="CONCURRENT_SESSION_FILTER" ref="concurrencyFilter" />
<custom-filter position="FORM_LOGIN_FILTER" ref="myAuthFilter" />

<session-management session-authentication-strategy-ref="sas"/>
</http>

<beans:bean id="redirectSessionInformationExpiredStrategy"
class="org.springframework.security.web.session.SimpleRedirectSessionInformationExpiredStrategy">
<beans:constructor-arg name="invalidSessionUrl" value="/session-expired.htm" />
</beans:bean>

<beans:bean id="concurrencyFilter"
class="org.springframework.security.web.session.ConcurrentSessionFilter">
<beans:constructor-arg name="sessionRegistry" ref="sessionRegistry" />
<beans:constructor-arg name="sessionInformationExpiredStrategy" ref="redirectSessionInformationExpiredStrategy" />
</beans:bean>

<beans:bean id="myAuthFilter" class=
"org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter">
<beans:property name="sessionAuthenticationStrategy" ref="sas" />
<beans:property name="authenticationManager" ref="authenticationManager" />
</beans:bean>

<beans:bean id="sas" class="org.springframework.security.web.authentication.session.CompositeSessionAuthenticationStrategy">
<beans:constructor-arg>
    <beans:list>
    <beans:bean class="org.springframework.security.web.authentication.session.ConcurrentSessionControlAuthenticationStrategy">
        <beans:constructor-arg ref="sessionRegistry"/>
        <beans:property name="maximumSessions" value="1" />
        <beans:property name="exceptionIfMaximumExceeded" value="true" />
    </beans:bean>
    <beans:bean class="org.springframework.security.web.authentication.session.SessionFixationProtectionStrategy">
    </beans:bean>
    <beans:bean class="org.springframework.security.web.authentication.session.RegisterSessionAuthenticationStrategy">
        <beans:constructor-arg ref="sessionRegistry"/>
    </beans:bean>
    </beans:list>
</beans:constructor-arg>
</beans:bean>

<beans:bean id="sessionRegistry"
    class="org.springframework.security.core.session.SessionRegistryImpl" />

Adding the listener to web.xml causes an ApplicationEvent to be published to the Spring ApplicationContext every time a HttpSession commences or terminates. This is critical, as it allows the SessionRegistryImpl to be notified when a session ends. Without it, a user will never be able to log back in again once they have exceeded their session allowance, even if they log out of another session or it times out.

Querying the SessionRegistry for currently authenticated users and their sessions

Setting up concurrency-control, either through the namespace or using plain beans has the useful side effect of providing you with a reference to the SessionRegistry which you can use directly within your application, so even if you don’t want to restrict the number of sessions a user may have, it may be worth setting up the infrastructure anyway. You can set the maximumSession property to -1 to allow unlimited sessions. If you’re using the namespace, you can set an alias for the internally-created SessionRegistry using the session-registry-alias attribute, providing a reference which you can inject into your own beans.

The getAllPrincipals() method supplies you with a list of the currently authenticated users. You can list a user’s sessions by calling the getAllSessions(Object principal, boolean includeExpiredSessions) method, which returns a list of SessionInformation objects. You can also expire a user’s session by calling expireNow() on a SessionInformation instance. When the user returns to the application, they will be prevented from proceeding. You may find these methods useful in an administration application, for example. Have a look at the Javadoc for more information.

10.13 Remember-Me Authentication

10.13.1 Overview

Remember-me or persistent-login authentication refers to web sites being able to remember the identity of a principal between sessions. This is typically accomplished by sending a cookie to the browser, with the cookie being detected during future sessions and causing automated login to take place. Spring Security provides the necessary hooks for these operations to take place, and has two concrete remember-me implementations. One uses hashing to preserve the security of cookie-based tokens and the other uses a database or other persistent storage mechanism to store the generated tokens.

Note that both implementations require a UserDetailsService. If you are using an authentication provider which doesn’t use a UserDetailsService (for example, the LDAP provider) then it won’t work unless you also have a UserDetailsService bean in your application context.

10.13.2 Simple Hash-Based Token Approach

This approach uses hashing to achieve a useful remember-me strategy. In essence a cookie is sent to the browser upon successful interactive authentication, with the cookie being composed as follows:

base64(username + ":" + expirationTime + ":" +
md5Hex(username + ":" + expirationTime + ":" password + ":" + key))

username:          As identifiable to the UserDetailsService
password:          That matches the one in the retrieved UserDetails
expirationTime:    The date and time when the remember-me token expires, expressed in milliseconds
key:               A private key to prevent modification of the remember-me token

As such the remember-me token is valid only for the period specified, and provided that the username, password and key does not change. Notably, this has a potential security issue in that a captured remember-me token will be usable from any user agent until such time as the token expires. This is the same issue as with digest authentication. If a principal is aware a token has been captured, they can easily change their password and immediately invalidate all remember-me tokens on issue. If more significant security is needed you should use the approach described in the next section. Alternatively remember-me services should simply not be used at all.

If you are familiar with the topics discussed in the chapter on namespace configuration, you can enable remember-me authentication just by adding the <remember-me> element:

<http>
...
<remember-me key="myAppKey"/>
</http>

The UserDetailsService will normally be selected automatically. If you have more than one in your application context, you need to specify which one should be used with the user-service-ref attribute, where the value is the name of your UserDetailsService bean.

10.13.3 Persistent Token Approach

This approach is based on the article http://jaspan.com/improved_persistent_login_cookie_best_practice with some minor modifications [5]. To use the this approach with namespace configuration, you would supply a datasource reference:

<http>
...
<remember-me data-source-ref="someDataSource"/>
</http>

The database should contain a persistent_logins table, created using the following SQL (or equivalent):

create table persistent_logins (username varchar(64) not null,
                                series varchar(64) primary key,
                                token varchar(64) not null,
                                last_used timestamp not null)

10.13.4 Remember-Me Interfaces and Implementations

Remember-me is used with UsernamePasswordAuthenticationFilter, and is implemented via hooks in the AbstractAuthenticationProcessingFilter superclass. It is also used within BasicAuthenticationFilter. The hooks will invoke a concrete RememberMeServices at the appropriate times. The interface looks like this:

Authentication autoLogin(HttpServletRequest request, HttpServletResponse response);

void loginFail(HttpServletRequest request, HttpServletResponse response);

void loginSuccess(HttpServletRequest request, HttpServletResponse response,
    Authentication successfulAuthentication);

Please refer to the Javadoc for a fuller discussion on what the methods do, although note at this stage that AbstractAuthenticationProcessingFilter only calls the loginFail() and loginSuccess() methods. The autoLogin() method is called by RememberMeAuthenticationFilter whenever the SecurityContextHolder does not contain an Authentication. This interface therefore provides the underlying remember-me implementation with sufficient notification of authentication-related events, and delegates to the implementation whenever a candidate web request might contain a cookie and wish to be remembered. This design allows any number of remember-me implementation strategies. We’ve seen above that Spring Security provides two implementations. We’ll look at these in turn.

TokenBasedRememberMeServices

This implementation supports the simpler approach described in Section 10.13.2, “Simple Hash-Based Token Approach”. TokenBasedRememberMeServices generates a RememberMeAuthenticationToken, which is processed by RememberMeAuthenticationProvider. A key is shared between this authentication provider and the TokenBasedRememberMeServices. In addition, TokenBasedRememberMeServices requires A UserDetailsService from which it can retrieve the username and password for signature comparison purposes, and generate the RememberMeAuthenticationToken to contain the correct GrantedAuthority s. Some sort of logout command should be provided by the application that invalidates the cookie if the user requests this. TokenBasedRememberMeServices also implements Spring Security’s LogoutHandler interface so can be used with LogoutFilter to have the cookie cleared automatically.

The beans required in an application context to enable remember-me services are as follows:

<bean id="rememberMeFilter" class=
"org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter">
<property name="rememberMeServices" ref="rememberMeServices"/>
<property name="authenticationManager" ref="theAuthenticationManager" />
</bean>

<bean id="rememberMeServices" class=
"org.springframework.security.web.authentication.rememberme.TokenBasedRememberMeServices">
<property name="userDetailsService" ref="myUserDetailsService"/>
<property name="key" value="springRocks"/>
</bean>

<bean id="rememberMeAuthenticationProvider" class=
"org.springframework.security.authentication.RememberMeAuthenticationProvider">
<property name="key" value="springRocks"/>
</bean>

Don’t forget to add your RememberMeServices implementation to your UsernamePasswordAuthenticationFilter.setRememberMeServices() property, include the RememberMeAuthenticationProvider in your AuthenticationManager.setProviders() list, and add RememberMeAuthenticationFilter into your FilterChainProxy (typically immediately after your UsernamePasswordAuthenticationFilter).

PersistentTokenBasedRememberMeServices

This class can be used in the same way as TokenBasedRememberMeServices, but it additionally needs to be configured with a PersistentTokenRepository to store the tokens. There are two standard implementations.

  • InMemoryTokenRepositoryImpl which is intended for testing only.
  • JdbcTokenRepositoryImpl which stores the tokens in a database.

The database schema is described above in Section 10.13.3, “Persistent Token Approach”.

10.14 OpenID Support

The namespace supports OpenID login either instead of, or in addition to normal form-based login, with a simple change:

<http>
<intercept-url pattern="/**" access="ROLE_USER" />
<openid-login />
</http>

You should then register yourself with an OpenID provider (such as myopenid.com), and add the user information to your in-memory <user-service>:

<user name="https://jimi.hendrix.myopenid.com/" authorities="ROLE_USER" />

You should be able to login using the myopenid.com site to authenticate. It is also possible to select a specific UserDetailsService bean for use OpenID by setting the user-service-ref attribute on the openid-login element. See the previous section on authentication providers for more information. Note that we have omitted the password attribute from the above user configuration, since this set of user data is only being used to load the authorities for the user. A random password will be generated internally, preventing you from accidentally using this user data as an authentication source elsewhere in your configuration.

10.14.1 Attribute Exchange

Support for OpenID attribute exchange. As an example, the following configuration would attempt to retrieve the email and full name from the OpenID provider, for use by the application:

<openid-login>
<attribute-exchange>
    <openid-attribute name="email" type="https://axschema.org/contact/email" required="true"/>
    <openid-attribute name="name" type="https://axschema.org/namePerson"/>
</attribute-exchange>
</openid-login>

The "type" of each OpenID attribute is a URI, determined by a particular schema, in this case https://axschema.org/. If an attribute must be retrieved for successful authentication, the required attribute can be set. The exact schema and attributes supported will depend on your OpenID provider. The attribute values are returned as part of the authentication process and can be accessed afterwards using the following code:

OpenIDAuthenticationToken token =
    (OpenIDAuthenticationToken)SecurityContextHolder.getContext().getAuthentication();
List<OpenIDAttribute> attributes = token.getAttributes();

The OpenIDAttribute contains the attribute type and the retrieved value (or values in the case of multi-valued attributes). We’ll see more about how the SecurityContextHolder class is used when we look at core Spring Security components in the technical overview chapter. Multiple attribute exchange configurations are also be supported, if you wish to use multiple identity providers. You can supply multiple attribute-exchange elements, using an identifier-matcher attribute on each. This contains a regular expression which will be matched against the OpenID identifier supplied by the user. See the OpenID sample application in the codebase for an example configuration, providing different attribute lists for the Google, Yahoo and MyOpenID providers.

10.15 Anonymous Authentication

10.15.1 Overview

It’s generally considered good security practice to adopt a "deny-by-default" where you explicitly specify what is allowed and disallow everything else. Defining what is accessible to unauthenticated users is a similar situation, particularly for web applications. Many sites require that users must be authenticated for anything other than a few URLs (for example the home and login pages). In this case it is easiest to define access configuration attributes for these specific URLs rather than have for every secured resource. Put differently, sometimes it is nice to say ROLE_SOMETHING is required by default and only allow certain exceptions to this rule, such as for login, logout and home pages of an application. You could also omit these pages from the filter chain entirely, thus bypassing the access control checks, but this may be undesirable for other reasons, particularly if the pages behave differently for authenticated users.

This is what we mean by anonymous authentication. Note that there is no real conceptual difference between a user who is "anonymously authenticated" and an unauthenticated user. Spring Security’s anonymous authentication just gives you a more convenient way to configure your access-control attributes. Calls to servlet API calls such as getCallerPrincipal, for example, will still return null even though there is actually an anonymous authentication object in the SecurityContextHolder.

There are other situations where anonymous authentication is useful, such as when an auditing interceptor queries the SecurityContextHolder to identify which principal was responsible for a given operation. Classes can be authored more robustly if they know the SecurityContextHolder always contains an Authentication object, and never null.

10.15.2 Configuration

Anonymous authentication support is provided automatically when using the HTTP configuration Spring Security 3.0 and can be customized (or disabled) using the <anonymous> element. You don’t need to configure the beans described here unless you are using traditional bean configuration.

Three classes that together provide the anonymous authentication feature. AnonymousAuthenticationToken is an implementation of Authentication, and stores the GrantedAuthority s which apply to the anonymous principal. There is a corresponding AnonymousAuthenticationProvider, which is chained into the ProviderManager so that AnonymousAuthenticationToken s are accepted. Finally, there is an AnonymousAuthenticationFilter, which is chained after the normal authentication mechanisms and automatically adds an AnonymousAuthenticationToken to the SecurityContextHolder if there is no existing Authentication held there. The definition of the filter and authentication provider appears as follows:

<bean id="anonymousAuthFilter"
    class="org.springframework.security.web.authentication.AnonymousAuthenticationFilter">
<property name="key" value="foobar"/>
<property name="userAttribute" value="anonymousUser,ROLE_ANONYMOUS"/>
</bean>

<bean id="anonymousAuthenticationProvider"
    class="org.springframework.security.authentication.AnonymousAuthenticationProvider">
<property name="key" value="foobar"/>
</bean>

The key is shared between the filter and authentication provider, so that tokens created by the former are accepted by the latter [6]. The userAttribute is expressed in the form of usernameInTheAuthenticationToken,grantedAuthority[,grantedAuthority]. This is the same syntax as used after the equals sign for the userMap property of InMemoryDaoImpl.

As explained earlier, the benefit of anonymous authentication is that all URI patterns can have security applied to them. For example:

<bean id="filterSecurityInterceptor"
    class="org.springframework.security.web.access.intercept.FilterSecurityInterceptor">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="accessDecisionManager" ref="httpRequestAccessDecisionManager"/>
<property name="securityMetadata">
    <security:filter-security-metadata-source>
    <security:intercept-url pattern='/index.jsp' access='ROLE_ANONYMOUS,ROLE_USER'/>
    <security:intercept-url pattern='/hello.htm' access='ROLE_ANONYMOUS,ROLE_USER'/>
    <security:intercept-url pattern='/logoff.jsp' access='ROLE_ANONYMOUS,ROLE_USER'/>
    <security:intercept-url pattern='/login.jsp' access='ROLE_ANONYMOUS,ROLE_USER'/>
    <security:intercept-url pattern='/**' access='ROLE_USER'/>
    </security:filter-security-metadata-source>" +
</property>
</bean>

10.15.3 AuthenticationTrustResolver

Rounding out the anonymous authentication discussion is the AuthenticationTrustResolver interface, with its corresponding AuthenticationTrustResolverImpl implementation. This interface provides an isAnonymous(Authentication) method, which allows interested classes to take into account this special type of authentication status. The ExceptionTranslationFilter uses this interface in processing AccessDeniedException s. If an AccessDeniedException is thrown, and the authentication is of an anonymous type, instead of throwing a 403 (forbidden) response, the filter will instead commence the AuthenticationEntryPoint so the principal can authenticate properly. This is a necessary distinction, otherwise principals would always be deemed "authenticated" and never be given an opportunity to login via form, basic, digest or some other normal authentication mechanism.

You will often see the ROLE_ANONYMOUS attribute in the above interceptor configuration replaced with IS_AUTHENTICATED_ANONYMOUSLY, which is effectively the same thing when defining access controls. This is an example of the use of the AuthenticatedVoter which we will see in the authorization chapter. It uses an AuthenticationTrustResolver to process this particular configuration attribute and grant access to anonymous users. The AuthenticatedVoter approach is more powerful, since it allows you to differentiate between anonymous, remember-me and fully-authenticated users. If you don’t need this functionality though, then you can stick with ROLE_ANONYMOUS, which will be processed by Spring Security’s standard RoleVoter.

10.16 Pre-Authentication Scenarios

There are situations where you want to use Spring Security for authorization, but the user has already been reliably authenticated by some external system prior to accessing the application. We refer to these situations as "pre-authenticated" scenarios. Examples include X.509, Siteminder and authentication by the Java EE container in which the application is running. When using pre-authentication, Spring Security has to

  • Identify the user making the request.
  • Obtain the authorities for the user.

The details will depend on the external authentication mechanism. A user might be identified by their certificate information in the case of X.509, or by an HTTP request header in the case of Siteminder. If relying on container authentication, the user will be identified by calling the getUserPrincipal() method on the incoming HTTP request. In some cases, the external mechanism may supply role/authority information for the user but in others the authorities must be obtained from a separate source, such as a UserDetailsService.

10.16.1 Pre-Authentication Framework Classes

Because most pre-authentication mechanisms follow the same pattern, Spring Security has a set of classes which provide an internal framework for implementing pre-authenticated authentication providers. This removes duplication and allows new implementations to be added in a structured fashion, without having to write everything from scratch. You don’t need to know about these classes if you want to use something like X.509 authentication, as it already has a namespace configuration option which is simpler to use and get started with. If you need to use explicit bean configuration or are planning on writing your own implementation then an understanding of how the provided implementations work will be useful. You will find classes under the org.springframework.security.web.authentication.preauth. We just provide an outline here so you should consult the Javadoc and source where appropriate.

AbstractPreAuthenticatedProcessingFilter

This class will check the current contents of the security context and, if empty, it will attempt to extract user information from the HTTP request and submit it to the AuthenticationManager. Subclasses override the following methods to obtain this information:

protected abstract Object getPreAuthenticatedPrincipal(HttpServletRequest request);

protected abstract Object getPreAuthenticatedCredentials(HttpServletRequest request);

After calling these, the filter will create a PreAuthenticatedAuthenticationToken containing the returned data and submit it for authentication. By "authentication" here, we really just mean further processing to perhaps load the user’s authorities, but the standard Spring Security authentication architecture is followed.

Like other Spring Security authentication filters, the pre-authentication filter has an authenticationDetailsSource property which by default will create a WebAuthenticationDetails object to store additional information such as the session-identifier and originating IP address in the details property of the Authentication object. In cases where user role information can be obtained from the pre-authentication mechanism, the data is also stored in this property, with the details implementing the GrantedAuthoritiesContainer interface. This enables the authentication provider to read the authorities which were externally allocated to the user. We’ll look at a concrete example next.

J2eeBasedPreAuthenticatedWebAuthenticationDetailsSource

If the filter is configured with an authenticationDetailsSource which is an instance of this class, the authority information is obtained by calling the isUserInRole(String role) method for each of a pre-determined set of "mappable roles". The class gets these from a configured MappableAttributesRetriever. Possible implementations include hard-coding a list in the application context and reading the role information from the <security-role> information in a web.xml file. The pre-authentication sample application uses the latter approach.

There is an additional stage where the roles (or attributes) are mapped to Spring Security GrantedAuthority objects using a configured Attributes2GrantedAuthoritiesMapper. The default will just add the usual ROLE_ prefix to the names, but it gives you full control over the behaviour.

PreAuthenticatedAuthenticationProvider

The pre-authenticated provider has little more to do than load the UserDetails object for the user. It does this by delegating to an AuthenticationUserDetailsService. The latter is similar to the standard UserDetailsService but takes an Authentication object rather than just user name:

public interface AuthenticationUserDetailsService {
    UserDetails loadUserDetails(Authentication token) throws UsernameNotFoundException;
}

This interface may have also other uses but with pre-authentication it allows access to the authorities which were packaged in the Authentication object, as we saw in the previous section. The PreAuthenticatedGrantedAuthoritiesUserDetailsService class does this. Alternatively, it may delegate to a standard UserDetailsService via the UserDetailsByNameServiceWrapper implementation.

Http403ForbiddenEntryPoint

The AuthenticationEntryPoint was discussed in the technical overview chapter. Normally it is responsible for kick-starting the authentication process for an unauthenticated user (when they try to access a protected resource), but in the pre-authenticated case this doesn’t apply. You would only configure the ExceptionTranslationFilter with an instance of this class if you aren’t using pre-authentication in combination with other authentication mechanisms. It will be called if the user is rejected by the AbstractPreAuthenticatedProcessingFilter resulting in a null authentication. It always returns a 403-forbidden response code if called.

10.16.2 Concrete Implementations

X.509 authentication is covered in its own chapter. Here we’ll look at some classes which provide support for other pre-authenticated scenarios.

Request-Header Authentication (Siteminder)

An external authentication system may supply information to the application by setting specific headers on the HTTP request. A well-known example of this is Siteminder, which passes the username in a header called SM_USER. This mechanism is supported by the class RequestHeaderAuthenticationFilter which simply extracts the username from the header. It defaults to using the name SM_USER as the header name. See the Javadoc for more details.

[Tip]Tip

Note that when using a system like this, the framework performs no authentication checks at all and it is extremely important that the external system is configured properly and protects all access to the application. If an attacker is able to forge the headers in their original request without this being detected then they could potentially choose any username they wished.

Siteminder Example Configuration

A typical configuration using this filter would look like this:

<security:http>
<!-- Additional http configuration omitted -->
<security:custom-filter position="PRE_AUTH_FILTER" ref="siteminderFilter" />
</security:http>

<bean id="siteminderFilter" class="org.springframework.security.web.authentication.preauth.RequestHeaderAuthenticationFilter">
<property name="principalRequestHeader" value="SM_USER"/>
<property name="authenticationManager" ref="authenticationManager" />
</bean>

<bean id="preauthAuthProvider" class="org.springframework.security.web.authentication.preauth.PreAuthenticatedAuthenticationProvider">
<property name="preAuthenticatedUserDetailsService">
    <bean id="userDetailsServiceWrapper"
        class="org.springframework.security.core.userdetails.UserDetailsByNameServiceWrapper">
    <property name="userDetailsService" ref="userDetailsService"/>
    </bean>
</property>
</bean>

<security:authentication-manager alias="authenticationManager">
<security:authentication-provider ref="preauthAuthProvider" />
</security:authentication-manager>

We’ve assumed here that the security namespace is being used for configuration. It’s also assumed that you have added a UserDetailsService (called "userDetailsService") to your configuration to load the user’s roles.

Java EE Container Authentication

The class J2eePreAuthenticatedProcessingFilter will extract the username from the userPrincipal property of the HttpServletRequest. Use of this filter would usually be combined with the use of Java EE roles as described above in the section called “J2eeBasedPreAuthenticatedWebAuthenticationDetailsSource”.

There is a sample application in the codebase which uses this approach, so get hold of the code from github and have a look at the application context file if you are interested. The code is in the samples/xml/preauth directory.

10.17 Java Authentication and Authorization Service (JAAS) Provider

10.17.1 Overview

Spring Security provides a package able to delegate authentication requests to the Java Authentication and Authorization Service (JAAS). This package is discussed in detail below.

10.17.2 AbstractJaasAuthenticationProvider

The AbstractJaasAuthenticationProvider is the basis for the provided JAAS AuthenticationProvider implementations. Subclasses must implement a method that creates the LoginContext. The AbstractJaasAuthenticationProvider has a number of dependencies that can be injected into it that are discussed below.

JAAS CallbackHandler

Most JAAS LoginModule s require a callback of some sort. These callbacks are usually used to obtain the username and password from the user.

In a Spring Security deployment, Spring Security is responsible for this user interaction (via the authentication mechanism). Thus, by the time the authentication request is delegated through to JAAS, Spring Security’s authentication mechanism will already have fully-populated an Authentication object containing all the information required by the JAAS LoginModule.

Therefore, the JAAS package for Spring Security provides two default callback handlers, JaasNameCallbackHandler and JaasPasswordCallbackHandler. Each of these callback handlers implement JaasAuthenticationCallbackHandler. In most cases these callback handlers can simply be used without understanding the internal mechanics.

For those needing full control over the callback behavior, internally AbstractJaasAuthenticationProvider wraps these JaasAuthenticationCallbackHandler s with an InternalCallbackHandler. The InternalCallbackHandler is the class that actually implements JAAS normal CallbackHandler interface. Any time that the JAAS LoginModule is used, it is passed a list of application context configured InternalCallbackHandler s. If the LoginModule requests a callback against the InternalCallbackHandler s, the callback is in-turn passed to the JaasAuthenticationCallbackHandler s being wrapped.

JAAS AuthorityGranter

JAAS works with principals. Even "roles" are represented as principals in JAAS. Spring Security, on the other hand, works with Authentication objects. Each Authentication object contains a single principal, and multiple GrantedAuthority s. To facilitate mapping between these different concepts, Spring Security’s JAAS package includes an AuthorityGranter interface.

An AuthorityGranter is responsible for inspecting a JAAS principal and returning a set of String s, representing the authorities assigned to the principal. For each returned authority string, the AbstractJaasAuthenticationProvider creates a JaasGrantedAuthority (which implements Spring Security’s GrantedAuthority interface) containing the authority string and the JAAS principal that the AuthorityGranter was passed. The AbstractJaasAuthenticationProvider obtains the JAAS principals by firstly successfully authenticating the user’s credentials using the JAAS LoginModule, and then accessing the LoginContext it returns. A call to LoginContext.getSubject().getPrincipals() is made, with each resulting principal passed to each AuthorityGranter defined against the AbstractJaasAuthenticationProvider.setAuthorityGranters(List) property.

Spring Security does not include any production AuthorityGranter s given that every JAAS principal has an implementation-specific meaning. However, there is a TestAuthorityGranter in the unit tests that demonstrates a simple AuthorityGranter implementation.

10.17.3 DefaultJaasAuthenticationProvider

The DefaultJaasAuthenticationProvider allows a JAAS Configuration object to be injected into it as a dependency. It then creates a LoginContext using the injected JAAS Configuration. This means that DefaultJaasAuthenticationProvider is not bound any particular implementation of Configuration as JaasAuthenticationProvider is.

InMemoryConfiguration

In order to make it easy to inject a Configuration into DefaultJaasAuthenticationProvider, a default in-memory implementation named InMemoryConfiguration is provided. The implementation constructor accepts a Map where each key represents a login configuration name and the value represents an Array of AppConfigurationEntry s. InMemoryConfiguration also supports a default Array of AppConfigurationEntry objects that will be used if no mapping is found within the provided Map. For details, refer to the class level javadoc of InMemoryConfiguration.

DefaultJaasAuthenticationProvider Example Configuration

While the Spring configuration for InMemoryConfiguration can be more verbose than the standarad JAAS configuration files, using it in conjuction with DefaultJaasAuthenticationProvider is more flexible than JaasAuthenticationProvider since it not dependant on the default Configuration implementation.

An example configuration of DefaultJaasAuthenticationProvider using InMemoryConfiguration is provided below. Note that custom implementations of Configuration can easily be injected into DefaultJaasAuthenticationProvider as well.

<bean id="jaasAuthProvider"
class="org.springframework.security.authentication.jaas.DefaultJaasAuthenticationProvider">
<property name="configuration">
<bean class="org.springframework.security.authentication.jaas.memory.InMemoryConfiguration">
<constructor-arg>
    <map>
    <!--
    SPRINGSECURITY is the default loginContextName
    for AbstractJaasAuthenticationProvider
    -->
    <entry key="SPRINGSECURITY">
    <array>
    <bean class="javax.security.auth.login.AppConfigurationEntry">
        <constructor-arg value="sample.SampleLoginModule" />
        <constructor-arg>
        <util:constant static-field=
            "javax.security.auth.login.AppConfigurationEntry$LoginModuleControlFlag.REQUIRED"/>
        </constructor-arg>
        <constructor-arg>
        <map></map>
        </constructor-arg>
        </bean>
    </array>
    </entry>
    </map>
    </constructor-arg>
</bean>
</property>
<property name="authorityGranters">
<list>
    <!-- You will need to write your own implementation of AuthorityGranter -->
    <bean class="org.springframework.security.authentication.jaas.TestAuthorityGranter"/>
</list>
</property>
</bean>

10.17.4 JaasAuthenticationProvider

The JaasAuthenticationProvider assumes the default Configuration is an instance of ConfigFile. This assumption is made in order to attempt to update the Configuration. The JaasAuthenticationProvider then uses the default Configuration to create the LoginContext.

Let’s assume we have a JAAS login configuration file, /WEB-INF/login.conf, with the following contents:

JAASTest {
    sample.SampleLoginModule required;
};

Like all Spring Security beans, the JaasAuthenticationProvider is configured via the application context. The following definitions would correspond to the above JAAS login configuration file:

<bean id="jaasAuthenticationProvider"
class="org.springframework.security.authentication.jaas.JaasAuthenticationProvider">
<property name="loginConfig" value="/WEB-INF/login.conf"/>
<property name="loginContextName" value="JAASTest"/>
<property name="callbackHandlers">
<list>
<bean
    class="org.springframework.security.authentication.jaas.JaasNameCallbackHandler"/>
<bean
    class="org.springframework.security.authentication.jaas.JaasPasswordCallbackHandler"/>
</list>
</property>
<property name="authorityGranters">
    <list>
    <bean class="org.springframework.security.authentication.jaas.TestAuthorityGranter"/>
    </list>
</property>
</bean>

10.17.5 Running as a Subject

If configured, the JaasApiIntegrationFilter will attempt to run as the Subject on the JaasAuthenticationToken. This means that the Subject can be accessed using:

Subject subject = Subject.getSubject(AccessController.getContext());

This integration can easily be configured using the jaas-api-provision attribute. This feature is useful when integrating with legacy or external API’s that rely on the JAAS Subject being populated.

10.18 CAS Authentication

10.18.1 Overview

JA-SIG produces an enterprise-wide single sign on system known as CAS. Unlike other initiatives, JA-SIG’s Central Authentication Service is open source, widely used, simple to understand, platform independent, and supports proxy capabilities. Spring Security fully supports CAS, and provides an easy migration path from single-application deployments of Spring Security through to multiple-application deployments secured by an enterprise-wide CAS server.

You can learn more about CAS at https://www.apereo.org. You will also need to visit this site to download the CAS Server files.

10.18.2 How CAS Works

Whilst the CAS web site contains documents that detail the architecture of CAS, we present the general overview again here within the context of Spring Security. Spring Security 3.x supports CAS 3. At the time of writing, the CAS server was at version 3.4.

Somewhere in your enterprise you will need to setup a CAS server. The CAS server is simply a standard WAR file, so there isn’t anything difficult about setting up your server. Inside the WAR file you will customise the login and other single sign on pages displayed to users.

When deploying a CAS 3.4 server, you will also need to specify an AuthenticationHandler in the deployerConfigContext.xml included with CAS. The AuthenticationHandler has a simple method that returns a boolean as to whether a given set of Credentials is valid. Your AuthenticationHandler implementation will need to link into some type of backend authentication repository, such as an LDAP server or database. CAS itself includes numerous AuthenticationHandler s out of the box to assist with this. When you download and deploy the server war file, it is set up to successfully authenticate users who enter a password matching their username, which is useful for testing.

Apart from the CAS server itself, the other key players are of course the secure web applications deployed throughout your enterprise. These web applications are known as "services". There are three types of services. Those that authenticate service tickets, those that can obtain proxy tickets, and those that authenticate proxy tickets. Authenticating a proxy ticket differs because the list of proxies must be validated and often times a proxy ticket can be reused.

Spring Security and CAS Interaction Sequence

The basic interaction between a web browser, CAS server and a Spring Security-secured service is as follows:

  • The web user is browsing the service’s public pages. CAS or Spring Security is not involved.
  • The user eventually requests a page that is either secure or one of the beans it uses is secure. Spring Security’s ExceptionTranslationFilter will detect the AccessDeniedException or AuthenticationException.
  • Because the user’s Authentication object (or lack thereof) caused an AuthenticationException, the ExceptionTranslationFilter will call the configured AuthenticationEntryPoint. If using CAS, this will be the CasAuthenticationEntryPoint class.
  • The CasAuthenticationEntryPoint will redirect the user’s browser to the CAS server. It will also indicate a service parameter, which is the callback URL for the Spring Security service (your application). For example, the URL to which the browser is redirected might be https://my.company.com/cas/login?service=https%3A%2F%2Fserver3.company.com%2Fwebapp%2Flogin/cas.
  • After the user’s browser redirects to CAS, they will be prompted for their username and password. If the user presents a session cookie which indicates they’ve previously logged on, they will not be prompted to login again (there is an exception to this procedure, which we’ll cover later). CAS will use the PasswordHandler (or AuthenticationHandler if using CAS 3.0) discussed above to decide whether the username and password is valid.
  • Upon successful login, CAS will redirect the user’s browser back to the original service. It will also include a ticket parameter, which is an opaque string representing the "service ticket". Continuing our earlier example, the URL the browser is redirected to might be https://server3.company.com/webapp/login/cas?ticket=ST-0-ER94xMJmn6pha35CQRoZ.
  • Back in the service web application, the CasAuthenticationFilter is always listening for requests to /login/cas (this is configurable, but we’ll use the defaults in this introduction). The processing filter will construct a UsernamePasswordAuthenticationToken representing the service ticket. The principal will be equal to CasAuthenticationFilter.CAS_STATEFUL_IDENTIFIER, whilst the credentials will be the service ticket opaque value. This authentication request will then be handed to the configured AuthenticationManager.
  • The AuthenticationManager implementation will be the ProviderManager, which is in turn configured with the CasAuthenticationProvider. The CasAuthenticationProvider only responds to UsernamePasswordAuthenticationToken s containing the CAS-specific principal (such as CasAuthenticationFilter.CAS_STATEFUL_IDENTIFIER) and CasAuthenticationToken s (discussed later).
  • CasAuthenticationProvider will validate the service ticket using a TicketValidator implementation. This will typically be a Cas20ServiceTicketValidator which is one of the classes included in the CAS client library. In the event the application needs to validate proxy tickets, the Cas20ProxyTicketValidator is used. The TicketValidator makes an HTTPS request to the CAS server in order to validate the service ticket. It may also include a proxy callback URL, which is included in this example: https://my.company.com/cas/proxyValidate?service=https%3A%2F%2Fserver3.company.com%2Fwebapp%2Flogin/cas&ticket=ST-0-ER94xMJmn6pha35CQRoZ&pgtUrl=https://server3.company.com/webapp/login/cas/proxyreceptor.
  • Back on the CAS server, the validation request will be received. If the presented service ticket matches the service URL the ticket was issued to, CAS will provide an affirmative response in XML indicating the username. If any proxy was involved in the authentication (discussed below), the list of proxies is also included in the XML response.
  • [OPTIONAL] If the request to the CAS validation service included the proxy callback URL (in the pgtUrl parameter), CAS will include a pgtIou string in the XML response. This pgtIou represents a proxy-granting ticket IOU. The CAS server will then create its own HTTPS connection back to the pgtUrl. This is to mutually authenticate the CAS server and the claimed service URL. The HTTPS connection will be used to send a proxy granting ticket to the original web application. For example, https://server3.company.com/webapp/login/cas/proxyreceptor?pgtIou=PGTIOU-0-R0zlgrl4pdAQwBvJWO3vnNpevwqStbSGcq3vKB2SqSFFRnjPHt&pgtId=PGT-1-si9YkkHLrtACBo64rmsi3v2nf7cpCResXg5MpESZFArbaZiOKH.
  • The Cas20TicketValidator will parse the XML received from the CAS server. It will return to the CasAuthenticationProvider a TicketResponse, which includes the username (mandatory), proxy list (if any were involved), and proxy-granting ticket IOU (if the proxy callback was requested).
  • Next CasAuthenticationProvider will call a configured CasProxyDecider. The CasProxyDecider indicates whether the proxy list in the TicketResponse is acceptable to the service. Several implementations are provided with Spring Security: RejectProxyTickets, AcceptAnyCasProxy and NamedCasProxyDecider. These names are largely self-explanatory, except NamedCasProxyDecider which allows a List of trusted proxies to be provided.
  • CasAuthenticationProvider will next request a AuthenticationUserDetailsService to load the GrantedAuthority objects that apply to the user contained in the Assertion.
  • If there were no problems, CasAuthenticationProvider constructs a CasAuthenticationToken including the details contained in the TicketResponse and the GrantedAuthoritys.
  • Control then returns to CasAuthenticationFilter, which places the created CasAuthenticationToken in the security context.
  • The user’s browser is redirected to the original page that caused the AuthenticationException (or a custom destination depending on the configuration).

It’s good that you’re still here! Let’s now look at how this is configured

10.18.3 Configuration of CAS Client

The web application side of CAS is made easy due to Spring Security. It is assumed you already know the basics of using Spring Security, so these are not covered again below. We’ll assume a namespace based configuration is being used and add in the CAS beans as required. Each section builds upon the previous section. A fullCAS sample application can be found in the Spring Security Samples.

Service Ticket Authentication

This section describes how to setup Spring Security to authenticate Service Tickets. Often times this is all a web application requires. You will need to add a ServiceProperties bean to your application context. This represents your CAS service:

<bean id="serviceProperties"
    class="org.springframework.security.cas.ServiceProperties">
<property name="service"
    value="https://localhost:8443/cas-sample/login/cas"/>
<property name="sendRenew" value="false"/>
</bean>

The service must equal a URL that will be monitored by the CasAuthenticationFilter. The sendRenew defaults to false, but should be set to true if your application is particularly sensitive. What this parameter does is tell the CAS login service that a single sign on login is unacceptable. Instead, the user will need to re-enter their username and password in order to gain access to the service.

The following beans should be configured to commence the CAS authentication process (assuming you’re using a namespace configuration):

<security:http entry-point-ref="casEntryPoint">
...
<security:custom-filter position="CAS_FILTER" ref="casFilter" />
</security:http>

<bean id="casFilter"
    class="org.springframework.security.cas.web.CasAuthenticationFilter">
<property name="authenticationManager" ref="authenticationManager"/>
</bean>

<bean id="casEntryPoint"
    class="org.springframework.security.cas.web.CasAuthenticationEntryPoint">
<property name="loginUrl" value="https://localhost:9443/cas/login"/>
<property name="serviceProperties" ref="serviceProperties"/>
</bean>

For CAS to operate, the ExceptionTranslationFilter must have its authenticationEntryPoint property set to the CasAuthenticationEntryPoint bean. This can easily be done using entry-point-ref as is done in the example above. The CasAuthenticationEntryPoint must refer to the ServiceProperties bean (discussed above), which provides the URL to the enterprise’s CAS login server. This is where the user’s browser will be redirected.

The CasAuthenticationFilter has very similar properties to the UsernamePasswordAuthenticationFilter (used for form-based logins). You can use these properties to customize things like behavior for authentication success and failure.

Next you need to add a CasAuthenticationProvider and its collaborators:

<security:authentication-manager alias="authenticationManager">
<security:authentication-provider ref="casAuthenticationProvider" />
</security:authentication-manager>

<bean id="casAuthenticationProvider"
    class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
<property name="authenticationUserDetailsService">
    <bean class="org.springframework.security.core.userdetails.UserDetailsByNameServiceWrapper">
    <constructor-arg ref="userService" />
    </bean>
</property>
<property name="serviceProperties" ref="serviceProperties" />
<property name="ticketValidator">
    <bean class="org.jasig.cas.client.validation.Cas20ServiceTicketValidator">
    <constructor-arg index="0" value="https://localhost:9443/cas" />
    </bean>
</property>
<property name="key" value="an_id_for_this_auth_provider_only"/>
</bean>

<security:user-service id="userService">
<!-- Password is prefixed with {noop} to indicate to DelegatingPasswordEncoder that
NoOpPasswordEncoder should be used.
This is not safe for production, but makes reading
in samples easier.
Normally passwords should be hashed using BCrypt -->
<security:user name="joe" password="{noop}joe" authorities="ROLE_USER" />
...
</security:user-service>

The CasAuthenticationProvider uses a UserDetailsService instance to load the authorities for a user, once they have been authenticated by CAS. We’ve shown a simple in-memory setup here. Note that the CasAuthenticationProvider does not actually use the password for authentication, but it does use the authorities.

The beans are all reasonably self-explanatory if you refer back to the How CAS Works section.

This completes the most basic configuration for CAS. If you haven’t made any mistakes, your web application should happily work within the framework of CAS single sign on. No other parts of Spring Security need to be concerned about the fact CAS handled authentication. In the following sections we will discuss some (optional) more advanced configurations.

Single Logout

The CAS protocol supports Single Logout and can be easily added to your Spring Security configuration. Below are updates to the Spring Security configuration that handle Single Logout

<security:http entry-point-ref="casEntryPoint">
...
<security:logout logout-success-url="/cas-logout.jsp"/>
<security:custom-filter ref="requestSingleLogoutFilter" before="LOGOUT_FILTER"/>
<security:custom-filter ref="singleLogoutFilter" before="CAS_FILTER"/>
</security:http>

<!-- This filter handles a Single Logout Request from the CAS Server -->
<bean id="singleLogoutFilter" class="org.jasig.cas.client.session.SingleSignOutFilter"/>

<!-- This filter redirects to the CAS Server to signal Single Logout should be performed -->
<bean id="requestSingleLogoutFilter"
    class="org.springframework.security.web.authentication.logout.LogoutFilter">
<constructor-arg value="https://localhost:9443/cas/logout"/>
<constructor-arg>
    <bean class=
        "org.springframework.security.web.authentication.logout.SecurityContextLogoutHandler"/>
</constructor-arg>
<property name="filterProcessesUrl" value="/logout/cas"/>
</bean>

The logout element logs the user out of the local application, but does not terminate the session with the CAS server or any other applications that have been logged into. The requestSingleLogoutFilter filter will allow the URL of /spring_security_cas_logout to be requested to redirect the application to the configured CAS Server logout URL. Then the CAS Server will send a Single Logout request to all the services that were signed into. The singleLogoutFilter handles the Single Logout request by looking up the HttpSession in a static Map and then invalidating it.

It might be confusing why both the logout element and the singleLogoutFilter are needed. It is considered best practice to logout locally first since the SingleSignOutFilter just stores the HttpSession in a static Map in order to call invalidate on it. With the configuration above, the flow of logout would be:

  • The user requests /logout which would log the user out of the local application and send the user to the logout success page.
  • The logout success page, /cas-logout.jsp, should instruct the user to click a link pointing to /logout/cas in order to logout out of all applications.
  • When the user clicks the link, the user is redirected to the CAS single logout URL (https://localhost:9443/cas/logout).
  • On the CAS Server side, the CAS single logout URL then submits single logout requests to all the CAS Services. On the CAS Service side, JASIG’s SingleSignOutFilter processes the logout request by invaliditing the original session.

The next step is to add the following to your web.xml

<filter>
<filter-name>characterEncodingFilter</filter-name>
<filter-class>
    org.springframework.web.filter.CharacterEncodingFilter
</filter-class>
<init-param>
    <param-name>encoding</param-name>
    <param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
<listener-class>
    org.jasig.cas.client.session.SingleSignOutHttpSessionListener
</listener-class>
</listener>

When using the SingleSignOutFilter you might encounter some encoding issues. Therefore it is recommended to add the CharacterEncodingFilter to ensure that the character encoding is correct when using the SingleSignOutFilter. Again, refer to JASIG’s documentation for details. The SingleSignOutHttpSessionListener ensures that when an HttpSession expires, the mapping used for single logout is removed.

Authenticating to a Stateless Service with CAS

This section describes how to authenticate to a service using CAS. In other words, this section discusses how to setup a client that uses a service that authenticates with CAS. The next section describes how to setup a stateless service to Authenticate using CAS.

Configuring CAS to Obtain Proxy Granting Tickets

In order to authenticate to a stateless service, the application needs to obtain a proxy granting ticket (PGT). This section describes how to configure Spring Security to obtain a PGT building upon thencas-st[Service Ticket Authentication] configuration.

The first step is to include a ProxyGrantingTicketStorage in your Spring Security configuration. This is used to store PGT’s that are obtained by the CasAuthenticationFilter so that they can be used to obtain proxy tickets. An example configuration is shown below

<!--
NOTE: In a real application you should not use an in memory implementation.
You will also want to ensure to clean up expired tickets by calling
ProxyGrantingTicketStorage.cleanup()
-->
<bean id="pgtStorage" class="org.jasig.cas.client.proxy.ProxyGrantingTicketStorageImpl"/>

The next step is to update the CasAuthenticationProvider to be able to obtain proxy tickets. To do this replace the Cas20ServiceTicketValidator with a Cas20ProxyTicketValidator. The proxyCallbackUrl should be set to a URL that the application will receive PGT’s at. Last, the configuration should also reference the ProxyGrantingTicketStorage so it can use a PGT to obtain proxy tickets. You can find an example of the configuration changes that should be made below.

<bean id="casAuthenticationProvider"
    class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
...
<property name="ticketValidator">
    <bean class="org.jasig.cas.client.validation.Cas20ProxyTicketValidator">
    <constructor-arg value="https://localhost:9443/cas"/>
        <property name="proxyCallbackUrl"
        value="https://localhost:8443/cas-sample/login/cas/proxyreceptor"/>
    <property name="proxyGrantingTicketStorage" ref="pgtStorage"/>
    </bean>
</property>
</bean>

The last step is to update the CasAuthenticationFilter to accept PGT and to store them in the ProxyGrantingTicketStorage. It is important the proxyReceptorUrl matches the proxyCallbackUrl of the Cas20ProxyTicketValidator. An example configuration is shown below.

<bean id="casFilter"
        class="org.springframework.security.cas.web.CasAuthenticationFilter">
    ...
    <property name="proxyGrantingTicketStorage" ref="pgtStorage"/>
    <property name="proxyReceptorUrl" value="/login/cas/proxyreceptor"/>
</bean>
Calling a Stateless Service Using a Proxy Ticket

Now that Spring Security obtains PGTs, you can use them to create proxy tickets which can be used to authenticate to a stateless service. The CAS sample application contains a working example in the ProxyTicketSampleServlet. Example code can be found below:

protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
// NOTE: The CasAuthenticationToken can also be obtained using
// SecurityContextHolder.getContext().getAuthentication()
final CasAuthenticationToken token = (CasAuthenticationToken) request.getUserPrincipal();
// proxyTicket could be reused to make calls to the CAS service even if the
// target url differs
final String proxyTicket = token.getAssertion().getPrincipal().getProxyTicketFor(targetUrl);

// Make a remote call using the proxy ticket
final String serviceUrl = targetUrl+"?ticket="+URLEncoder.encode(proxyTicket, "UTF-8");
String proxyResponse = CommonUtils.getResponseFromServer(serviceUrl, "UTF-8");
...
}

Proxy Ticket Authentication

The CasAuthenticationProvider distinguishes between stateful and stateless clients. A stateful client is considered any that submits to the filterProcessUrl of the CasAuthenticationFilter. A stateless client is any that presents an authentication request to CasAuthenticationFilter on a URL other than the filterProcessUrl.

Because remoting protocols have no way of presenting themselves within the context of an HttpSession, it isn’t possible to rely on the default practice of storing the security context in the session between requests. Furthermore, because the CAS server invalidates a ticket after it has been validated by the TicketValidator, presenting the same proxy ticket on subsequent requests will not work.

One obvious option is to not use CAS at all for remoting protocol clients. However, this would eliminate many of the desirable features of CAS. As a middle-ground, the CasAuthenticationProvider uses a StatelessTicketCache. This is used solely for stateless clients which use a principal equal to CasAuthenticationFilter.CAS_STATELESS_IDENTIFIER. What happens is the CasAuthenticationProvider will store the resulting CasAuthenticationToken in the StatelessTicketCache, keyed on the proxy ticket. Accordingly, remoting protocol clients can present the same proxy ticket and the CasAuthenticationProvider will not need to contact the CAS server for validation (aside from the first request). Once authenticated, the proxy ticket could be used for URLs other than the original target service.

This section builds upon the previous sections to accommodate proxy ticket authentication. The first step is to specify to authenticate all artifacts as shown below.

<bean id="serviceProperties"
    class="org.springframework.security.cas.ServiceProperties">
...
<property name="authenticateAllArtifacts" value="true"/>
</bean>

The next step is to specify serviceProperties and the authenticationDetailsSource for the CasAuthenticationFilter. The serviceProperties property instructs the CasAuthenticationFilter to attempt to authenticate all artifacts instead of only ones present on the filterProcessUrl. The ServiceAuthenticationDetailsSource creates a ServiceAuthenticationDetails that ensures the current URL, based upon the HttpServletRequest, is used as the service URL when validating the ticket. The method for generating the service URL can be customized by injecting a custom AuthenticationDetailsSource that returns a custom ServiceAuthenticationDetails.

<bean id="casFilter"
    class="org.springframework.security.cas.web.CasAuthenticationFilter">
...
<property name="serviceProperties" ref="serviceProperties"/>
<property name="authenticationDetailsSource">
    <bean class=
    "org.springframework.security.cas.web.authentication.ServiceAuthenticationDetailsSource">
    <constructor-arg ref="serviceProperties"/>
    </bean>
</property>
</bean>

You will also need to update the CasAuthenticationProvider to handle proxy tickets. To do this replace the Cas20ServiceTicketValidator with a Cas20ProxyTicketValidator. You will need to configure the statelessTicketCache and which proxies you want to accept. You can find an example of the updates required to accept all proxies below.

<bean id="casAuthenticationProvider"
    class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
...
<property name="ticketValidator">
    <bean class="org.jasig.cas.client.validation.Cas20ProxyTicketValidator">
    <constructor-arg value="https://localhost:9443/cas"/>
    <property name="acceptAnyProxy" value="true"/>
    </bean>
</property>
<property name="statelessTicketCache">
    <bean class="org.springframework.security.cas.authentication.EhCacheBasedTicketCache">
    <property name="cache">
        <bean class="net.sf.ehcache.Cache"
            init-method="initialise" destroy-method="dispose">
        <constructor-arg value="casTickets"/>
        <constructor-arg value="50"/>
        <constructor-arg value="true"/>
        <constructor-arg value="false"/>
        <constructor-arg value="3600"/>
        <constructor-arg value="900"/>
        </bean>
    </property>
    </bean>
</property>
</bean>

10.19 X.509 Authentication

10.19.1 Overview

The most common use of X.509 certificate authentication is in verifying the identity of a server when using SSL, most commonly when using HTTPS from a browser. The browser will automatically check that the certificate presented by a server has been issued (ie digitally signed) by one of a list of trusted certificate authorities which it maintains.

You can also use SSL with "mutual authentication"; the server will then request a valid certificate from the client as part of the SSL handshake. The server will authenticate the client by checking that its certificate is signed by an acceptable authority. If a valid certificate has been provided, it can be obtained through the servlet API in an application. Spring Security X.509 module extracts the certificate using a filter. It maps the certificate to an application user and loads that user’s set of granted authorities for use with the standard Spring Security infrastructure.

You should be familiar with using certificates and setting up client authentication for your servlet container before attempting to use it with Spring Security. Most of the work is in creating and installing suitable certificates and keys. For example, if you’re using Tomcat then read the instructions here https://tomcat.apache.org/tomcat-6.0-doc/ssl-howto.html. It’s important that you get this working before trying it out with Spring Security

10.19.2 Adding X.509 Authentication to Your Web Application

Enabling X.509 client authentication is very straightforward. Just add the <x509/> element to your http security namespace configuration.

<http>
...
    <x509 subject-principal-regex="CN=(.*?)," user-service-ref="userService"/>;
</http>

The element has two optional attributes:

  • subject-principal-regex. The regular expression used to extract a username from the certificate’s subject name. The default value is shown above. This is the username which will be passed to the UserDetailsService to load the authorities for the user.
  • user-service-ref. This is the bean Id of the UserDetailsService to be used with X.509. It isn’t needed if there is only one defined in your application context.

The subject-principal-regex should contain a single group. For example the default expression "CN=(.*?)," matches the common name field. So if the subject name in the certificate is "CN=Jimi Hendrix, OU=…​", this will give a user name of "Jimi Hendrix". The matches are case insensitive. So "emailAddress=(.*?)," will match "EMAILADDRESS=[email protected],CN=…​" giving a user name "[email protected]". If the client presents a certificate and a valid username is successfully extracted, then there should be a valid Authentication object in the security context. If no certificate is found, or no corresponding user could be found then the security context will remain empty. This means that you can easily use X.509 authentication with other options such as a form-based login.

10.19.3 Setting up SSL in Tomcat

There are some pre-generated certificates in the samples/certificate directory in the Spring Security project. You can use these to enable SSL for testing if you don’t want to generate your own. The file server.jks contains the server certificate, private key and the issuing certificate authority certificate. There are also some client certificate files for the users from the sample applications. You can install these in your browser to enable SSL client authentication.

To run tomcat with SSL support, drop the server.jks file into the tomcat conf directory and add the following connector to the server.xml file

<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" scheme="https" secure="true"
            clientAuth="true" sslProtocol="TLS"
            keystoreFile="${catalina.home}/conf/server.jks"
            keystoreType="JKS" keystorePass="password"
            truststoreFile="${catalina.home}/conf/server.jks"
            truststoreType="JKS" truststorePass="password"
/>

clientAuth can also be set to want if you still want SSL connections to succeed even if the client doesn’t provide a certificate. Clients which don’t present a certificate won’t be able to access any objects secured by Spring Security unless you use a non-X.509 authentication mechanism, such as form authentication.

10.20 Run-As Authentication Replacement

10.20.1 Overview

The AbstractSecurityInterceptor is able to temporarily replace the Authentication object in the SecurityContext and SecurityContextHolder during the secure object callback phase. This only occurs if the original Authentication object was successfully processed by the AuthenticationManager and AccessDecisionManager. The RunAsManager will indicate the replacement Authentication object, if any, that should be used during the SecurityInterceptorCallback.

By temporarily replacing the Authentication object during the secure object callback phase, the secured invocation will be able to call other objects which require different authentication and authorization credentials. It will also be able to perform any internal security checks for specific GrantedAuthority objects. Because Spring Security provides a number of helper classes that automatically configure remoting protocols based on the contents of the SecurityContextHolder, these run-as replacements are particularly useful when calling remote web services

10.20.2 Configuration

A RunAsManager interface is provided by Spring Security:

Authentication buildRunAs(Authentication authentication, Object object,
    List<ConfigAttribute> config);

boolean supports(ConfigAttribute attribute);

boolean supports(Class clazz);

The first method returns the Authentication object that should replace the existing Authentication object for the duration of the method invocation. If the method returns null, it indicates no replacement should be made. The second method is used by the AbstractSecurityInterceptor as part of its startup validation of configuration attributes. The supports(Class) method is called by a security interceptor implementation to ensure the configured RunAsManager supports the type of secure object that the security interceptor will present.

One concrete implementation of a RunAsManager is provided with Spring Security. The RunAsManagerImpl class returns a replacement RunAsUserToken if any ConfigAttribute starts with RUN_AS_. If any such ConfigAttribute is found, the replacement RunAsUserToken will contain the same principal, credentials and granted authorities as the original Authentication object, along with a new SimpleGrantedAuthority for each RUN_AS_ ConfigAttribute. Each new SimpleGrantedAuthority will be prefixed with ROLE_, followed by the RUN_AS ConfigAttribute. For example, a RUN_AS_SERVER will result in the replacement RunAsUserToken containing a ROLE_RUN_AS_SERVER granted authority.

The replacement RunAsUserToken is just like any other Authentication object. It needs to be authenticated by the AuthenticationManager, probably via delegation to a suitable AuthenticationProvider. The RunAsImplAuthenticationProvider performs such authentication. It simply accepts as valid any RunAsUserToken presented.

To ensure malicious code does not create a RunAsUserToken and present it for guaranteed acceptance by the RunAsImplAuthenticationProvider, the hash of a key is stored in all generated tokens. The RunAsManagerImpl and RunAsImplAuthenticationProvider is created in the bean context with the same key:

<bean id="runAsManager"
    class="org.springframework.security.access.intercept.RunAsManagerImpl">
<property name="key" value="my_run_as_password"/>
</bean>

<bean id="runAsAuthenticationProvider"
    class="org.springframework.security.access.intercept.RunAsImplAuthenticationProvider">
<property name="key" value="my_run_as_password"/>
</bean>

By using the same key, each RunAsUserToken can be validated it was created by an approved RunAsManagerImpl. The RunAsUserToken is immutable after creation for security reasons

10.21 Form Login

10.21.1 Form Login Java Configuration

You might be wondering where the login form came from when you were prompted to log in, since we made no mention of any HTML files or JSPs. Since Spring Security’s default configuration does not explicitly set a URL for the login page, Spring Security generates one automatically, based on the features that are enabled and using standard values for the URL which processes the submitted login, the default target URL the user will be sent to after logging in and so on.

While the automatically generated log in page is convenient to get up and running quickly, most applications will want to provide their own login page. When we want to change the default configuration, we can customize the WebSecurityConfigurerAdapter that we mentioned earlier by extending it like so:

public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    // ...
}

And then override the configure method as seen below:

protected void configure(HttpSecurity http) throws Exception {
    http
        .authorizeRequests(authorizeRequests ->
            authorizeRequests
                .anyRequest().authenticated()
        )
        .formLogin(formLogin ->
            formLogin
                .loginPage("/login") 1
                .permitAll()         2
        );
}

1

The updated configuration specifies the location of the log in page.

2

We must grant all users (i.e. unauthenticated users) access to our log in page. The formLogin().permitAll() method allows granting access to all users for all URLs associated with form based log in.

An example log in page implemented with JSPs for our current configuration can be seen below:

[Note]Note

The login page below represents our current configuration. We could easily update our configuration if some of the defaults do not meet our needs.

<c:url value="/login" var="loginUrl"/>
<form action="${loginUrl}" method="post">       1
    <c:if test="${param.error != null}">        2
        <p>
            Invalid username and password.
        </p>
    </c:if>
    <c:if test="${param.logout != null}">       3
        <p>
            You have been logged out.
        </p>
    </c:if>
    <p>
        <label for="username">Username</label>
        <input type="text" id="username" name="username"/>  4
    </p>
    <p>
        <label for="password">Password</label>
        <input type="password" id="password" name="password"/>  5
    </p>
    <input type="hidden"                        6
        name="${_csrf.parameterName}"
        value="${_csrf.token}"/>
    <button type="submit" class="btn">Log in</button>
</form>

1

A POST to the /login URL will attempt to authenticate the user

2

If the query parameter error exists, authentication was attempted and failed

3

If the query parameter logout exists, the user was successfully logged out

4

The username must be present as the HTTP parameter named username

5

The password must be present as the HTTP parameter named password

6

We must the section called “Include the CSRF Token” To learn more read the Section 5.1.1, “Cross Site Request Forgery (CSRF)” section of the reference

10.21.2 Form Login XML Configuration

Form and Basic Login Options

You might be wondering where the login form came from when you were prompted to log in, since we made no mention of any HTML files or JSPs. In fact, since we didn’t explicitly set a URL for the login page, Spring Security generates one automatically, based on the features that are enabled and using standard values for the URL which processes the submitted login, the default target URL the user will be sent to after logging in and so on. However, the namespace offers plenty of support to allow you to customize these options. For example, if you want to supply your own login page, you could use:

<http>
<intercept-url pattern="/login.jsp*" access="IS_AUTHENTICATED_ANONYMOUSLY"/>
<intercept-url pattern="/**" access="ROLE_USER" />
<form-login login-page='/login.jsp'/>
</http>

Also note that we’ve added an extra intercept-url element to say that any requests for the login page should be available to anonymous users [7] and also the AuthenticatedVoter class for more details on how the value IS_AUTHENTICATED_ANONYMOUSLY is processed.]. Otherwise the request would be matched by the pattern /** and it wouldn’t be possible to access the login page itself! This is a common configuration error and will result in an infinite loop in the application. Spring Security will emit a warning in the log if your login page appears to be secured. It is also possible to have all requests matching a particular pattern bypass the security filter chain completely, by defining a separate http element for the pattern like this:

<http pattern="/css/**" security="none"/>
<http pattern="/login.jsp*" security="none"/>

<http use-expressions="false">
<intercept-url pattern="/**" access="ROLE_USER" />
<form-login login-page='/login.jsp'/>
</http>

From Spring Security 3.1 it is now possible to use multiple http elements to define separate security filter chain configurations for different request patterns. If the pattern attribute is omitted from an http element, it matches all requests. Creating an unsecured pattern is a simple example of this syntax, where the pattern is mapped to an empty filter chain [8]. We’ll look at this new syntax in more detail in the chapter on the Security Filter Chain.

It’s important to realise that these unsecured requests will be completely oblivious to any Spring Security web-related configuration or additional attributes such as requires-channel, so you will not be able to access information on the current user or call secured methods during the request. Use access='IS_AUTHENTICATED_ANONYMOUSLY' as an alternative if you still want the security filter chain to be applied.

If you want to use basic authentication instead of form login, then change the configuration to

<http use-expressions="false">
<intercept-url pattern="/**" access="ROLE_USER" />
<http-basic />
</http>

Basic authentication will then take precedence and will be used to prompt for a login when a user attempts to access a protected resource. Form login is still available in this configuration if you wish to use it, for example through a login form embedded in another web page.

10.22 Basic and Digest Authentication

Basic and digest authentication are alternative authentication mechanisms which are popular in web applications. Basic authentication is often used with stateless clients which pass their credentials on each request. It’s quite common to use it in combination with form-based authentication where an application is used through both a browser-based user interface and as a web-service. However, basic authentication transmits the password as plain text so it should only really be used over an encrypted transport layer such as HTTPS.

10.22.1 BasicAuthenticationFilter

BasicAuthenticationFilter is responsible for processing basic authentication credentials presented in HTTP headers. This can be used for authenticating calls made by Spring remoting protocols (such as Hessian and Burlap), as well as normal browser user agents (such as Firefox and Internet Explorer). The standard governing HTTP Basic Authentication is defined by RFC 1945, Section 11, and BasicAuthenticationFilter conforms with this RFC. Basic Authentication is an attractive approach to authentication, because it is very widely deployed in user agents and implementation is extremely simple (it’s just a Base64 encoding of the username:password, specified in an HTTP header).

10.22.2 Configuration

To implement HTTP Basic Authentication, you need to add a BasicAuthenticationFilter to your filter chain. The application context should contain BasicAuthenticationFilter and its required collaborator:

<bean id="basicAuthenticationFilter"
class="org.springframework.security.web.authentication.www.BasicAuthenticationFilter">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="authenticationEntryPoint" ref="authenticationEntryPoint"/>
</bean>

<bean id="authenticationEntryPoint"
class="org.springframework.security.web.authentication.www.BasicAuthenticationEntryPoint">
<property name="realmName" value="Name Of Your Realm"/>
</bean>

The configured AuthenticationManager processes each authentication request. If authentication fails, the configured AuthenticationEntryPoint will be used to retry the authentication process. Usually you will use the filter in combination with a BasicAuthenticationEntryPoint, which returns a 401 response with a suitable header to retry HTTP Basic authentication. If authentication is successful, the resulting Authentication object will be placed into the SecurityContextHolder as usual.

If the authentication event was successful, or authentication was not attempted because the HTTP header did not contain a supported authentication request, the filter chain will continue as normal. The only time the filter chain will be interrupted is if authentication fails and the AuthenticationEntryPoint is called.

10.23 DigestAuthenticationFilter

DigestAuthenticationFilter is capable of processing digest authentication credentials presented in HTTP headers. Digest Authentication attempts to solve many of the weaknesses of Basic authentication, specifically by ensuring credentials are never sent in clear text across the wire. Many user agents support Digest Authentication, including Mozilla Firefox and Internet Explorer. The standard governing HTTP Digest Authentication is defined by RFC 2617, which updates an earlier version of the Digest Authentication standard prescribed by RFC 2069. Most user agents implement RFC 2617. Spring Security’s DigestAuthenticationFilter is compatible with the “auth” quality of protection (qop) prescribed by RFC 2617, which also provides backward compatibility with RFC 2069. Digest Authentication is a more attractive option if you need to use unencrypted HTTP (i.e. no TLS/HTTPS) and wish to maximise security of the authentication process. Indeed Digest Authentication is a mandatory requirement for the WebDAV protocol, as noted by RFC 2518 Section 17.1.

[Note]Note

You should not use Digest in modern applications because it is not considered secure. The most obvious problem is that you must store your passwords in plaintext, encrypted, or an MD5 format. All of these storage formats are considered insecure. Instead, you should use a one way adaptive password hash (i.e. bCrypt, PBKDF2, SCrypt, etc).

Central to Digest Authentication is a "nonce". This is a value the server generates. Spring Security’s nonce adopts the following format:

base64(expirationTime + ":" + md5Hex(expirationTime + ":" + key))
expirationTime:   The date and time when the nonce expires, expressed in milliseconds
key:              A private key to prevent modification of the nonce token

The DigestAuthenticationEntryPoint has a property specifying the key used for generating the nonce tokens, along with a nonceValiditySeconds property for determining the expiration time (default 300, which equals five minutes). Whist ever the nonce is valid, the digest is computed by concatenating various strings including the username, password, nonce, URI being requested, a client-generated nonce (merely a random value which the user agent generates each request), the realm name etc, then performing an MD5 hash. Both the server and user agent perform this digest computation, resulting in different hash codes if they disagree on an included value (eg password). In Spring Security implementation, if the server-generated nonce has merely expired (but the digest was otherwise valid), the DigestAuthenticationEntryPoint will send a "stale=true" header. This tells the user agent there is no need to disturb the user (as the password and username etc is correct), but simply to try again using a new nonce.

An appropriate value for the nonceValiditySeconds parameter of DigestAuthenticationEntryPoint depends on your application. Extremely secure applications should note that an intercepted authentication header can be used to impersonate the principal until the expirationTime contained in the nonce is reached. This is the key principle when selecting an appropriate setting, but it would be unusual for immensely secure applications to not be running over TLS/HTTPS in the first instance.

Because of the more complex implementation of Digest Authentication, there are often user agent issues. For example, Internet Explorer fails to present an “opaque” token on subsequent requests in the same session. Spring Security filters therefore encapsulate all state information into the “nonce” token instead. In our testing, Spring Security’s implementation works reliably with Mozilla Firefox and Internet Explorer, correctly handling nonce timeouts etc.

10.23.1 Configuration

Now that we’ve reviewed the theory, let’s see how to use it. To implement HTTP Digest Authentication, it is necessary to define DigestAuthenticationFilter in the filter chain. The application context will need to define the DigestAuthenticationFilter and its required collaborators:

<bean id="digestFilter" class=
    "org.springframework.security.web.authentication.www.DigestAuthenticationFilter">
<property name="userDetailsService" ref="jdbcDaoImpl"/>
<property name="authenticationEntryPoint" ref="digestEntryPoint"/>
<property name="userCache" ref="userCache"/>
</bean>

<bean id="digestEntryPoint" class=
    "org.springframework.security.web.authentication.www.DigestAuthenticationEntryPoint">
<property name="realmName" value="Contacts Realm via Digest Authentication"/>
<property name="key" value="acegi"/>
<property name="nonceValiditySeconds" value="10"/>
</bean>

The configured UserDetailsService is needed because DigestAuthenticationFilter must have direct access to the clear text password of a user. Digest Authentication will NOT work if you are using encoded passwords in your DAO [9]. The DAO collaborator, along with the UserCache, are typically shared directly with a DaoAuthenticationProvider. The authenticationEntryPoint property must be DigestAuthenticationEntryPoint, so that DigestAuthenticationFilter can obtain the correct realmName and key for digest calculations.

Like BasicAuthenticationFilter, if authentication is successful an Authentication request token will be placed into the SecurityContextHolder. If the authentication event was successful, or authentication was not attempted because the HTTP header did not contain a Digest Authentication request, the filter chain will continue as normal. The only time the filter chain will be interrupted is if authentication fails and the AuthenticationEntryPoint is called, as discussed in the previous paragraph.

Digest Authentication’s RFC offers a range of additional features to further increase security. For example, the nonce can be changed on every request. Despite this, Spring Security implementation was designed to minimise the complexity of the implementation (and the doubtless user agent incompatibilities that would emerge), and avoid needing to store server-side state. You are invited to review RFC 2617 if you wish to explore these features in more detail. As far as we are aware, Spring Security’s implementation does comply with the minimum standards of this RFC.

10.24 Handling Logouts

10.24.1 Logout Java Configuration

When using the WebSecurityConfigurerAdapter, logout capabilities are automatically applied. The default is that accessing the URL /logout will log the user out by:

  • Invalidating the HTTP Session
  • Cleaning up any RememberMe authentication that was configured
  • Clearing the SecurityContextHolder
  • Redirect to /login?logout

Similar to configuring login capabilities, however, you also have various options to further customize your logout requirements:

protected void configure(HttpSecurity http) throws Exception {
    http
        .logout(logout ->                                                       1
            logout
                .logoutUrl("/my/logout")                                        2
                .logoutSuccessUrl("/my/index")                                  3
                .logoutSuccessHandler(logoutSuccessHandler)                     4
                .invalidateHttpSession(true)                                    5
                .addLogoutHandler(logoutHandler)                                6
                .deleteCookies(cookieNamesToClear)                              7
        )
        ...
}

1

Provides logout support. This is automatically applied when using WebSecurityConfigurerAdapter.

2

The URL that triggers log out to occur (default is /logout). If CSRF protection is enabled (default), then the request must also be a POST. For more information, please consult the JavaDoc.

3

The URL to redirect to after logout has occurred. The default is /login?logout. For more information, please consult the JavaDoc.

4

Let’s you specify a custom LogoutSuccessHandler. If this is specified, logoutSuccessUrl() is ignored. For more information, please consult the JavaDoc.

5

Specify whether to invalidate the HttpSession at the time of logout. This is true by default. Configures the SecurityContextLogoutHandler under the covers. For more information, please consult the JavaDoc.

6

Adds a LogoutHandler. SecurityContextLogoutHandler is added as the last LogoutHandler by default.

7

Allows specifying the names of cookies to be removed on logout success. This is a shortcut for adding a CookieClearingLogoutHandler explicitly.

[Note]Note

=== Logouts can of course also be configured using the XML Namespace notation. Please see the documentation for the logout element in the Spring Security XML Namespace section for further details. ===

Generally, in order to customize logout functionality, you can add LogoutHandler and/or LogoutSuccessHandler implementations. For many common scenarios, these handlers are applied under the covers when using the fluent API.

10.24.2 Logout XML Configuration

The logout element adds support for logging out by navigating to a particular URL. The default logout URL is /logout, but you can set it to something else using the logout-url attribute. More information on other available attributes may be found in the namespace appendix.

10.24.3 LogoutHandler

Generally, LogoutHandler implementations indicate classes that are able to participate in logout handling. They are expected to be invoked to perform necessary clean-up. As such they should not throw exceptions. Various implementations are provided:

Please see Section 10.13.4, “Remember-Me Interfaces and Implementations” for details.

Instead of providing LogoutHandler implementations directly, the fluent API also provides shortcuts that provide the respective LogoutHandler implementations under the covers. E.g. deleteCookies() allows specifying the names of one or more cookies to be removed on logout success. This is a shortcut compared to adding a CookieClearingLogoutHandler.

10.24.4 LogoutSuccessHandler

The LogoutSuccessHandler is called after a successful logout by the LogoutFilter, to handle e.g. redirection or forwarding to the appropriate destination. Note that the interface is almost the same as the LogoutHandler but may raise an exception.

The following implementations are provided:

As mentioned above, you don’t need to specify the SimpleUrlLogoutSuccessHandler directly. Instead, the fluent API provides a shortcut by setting the logoutSuccessUrl(). This will setup the SimpleUrlLogoutSuccessHandler under the covers. The provided URL will be redirected to after a logout has occurred. The default is /login?logout.

The HttpStatusReturningLogoutSuccessHandler can be interesting in REST API type scenarios. Instead of redirecting to a URL upon the successful logout, this LogoutSuccessHandler allows you to provide a plain HTTP status code to be returned. If not configured a status code 200 will be returned by default.

10.24.5 Further Logout-Related References

10.25 Setting a Custom AuthenticationEntryPoint

If you aren’t using form login, OpenID or basic authentication through the namespace, you may want to define an authentication filter and entry point using a traditional bean syntax and link them into the namespace, as we’ve just seen. The corresponding AuthenticationEntryPoint can be set using the entry-point-ref attribute on the <http> element.

The CAS sample application is a good example of the use of custom beans with the namespace, including this syntax. If you aren’t familiar with authentication entry points, they are discussed in the technical overview chapter.



[2] Note that this is different from the default configuration of the underlying DefaultLdapAuthoritiesPopulator which uses member={0}.

[3] It is also possible to obtain the server’s IP address using a DNS lookup. This is not currently supported, but hopefully will be in a future version.

[4] Authentication by mechanisms which perform a redirect after authenticating (such as form-login) will not be detected by SessionManagementFilter, as the filter will not be invoked during the authenticating request. Session-management functionality has to be handled separately in these cases.

[5] Essentially, the username is not included in the cookie, to prevent exposing a valid login name unecessarily. There is a discussion on this in the comments section of this article.

[6] The use of the key property should not be regarded as providing any real security here. It is merely a book-keeping exercise. If you are sharing a ProviderManager which contains an AnonymousAuthenticationProvider in a scenario where it is possible for an authenticating client to construct the Authentication object (such as with RMI invocations), then a malicious client could submit an AnonymousAuthenticationToken which it had created itself (with chosen username and authority list). If the key is guessable or can be found out, then the token would be accepted by the anonymous provider. This isn’t a problem with normal usage but if you are using RMI you would be best to use a customized ProviderManager which omits the anonymous provider rather than sharing the one you use for your HTTP authentication mechanisms.

[8] The use of multiple <http> elements is an important feature, allowing the namespace to simultaneously support both stateful and stateless paths within the same application, for example. The previous syntax, using the attribute filters="none" on an intercept-url element is incompatible with this change and is no longer supported in 3.1.

[9] It is possible to encode the password in the format HEX( MD5(username:realm:password) ) provided the DigestAuthenticationFilter.passwordAlreadyEncoded is set to true. However, other password encodings will not work with digest authentication.

11. Authorization

The advanced authorization capabilities within Spring Security represent one of the most compelling reasons for its popularity. Irrespective of how you choose to authenticate - whether using a Spring Security-provided mechanism and provider, or integrating with a container or other non-Spring Security authentication authority - you will find the authorization services can be used within your application in a consistent and simple way.

In this part we’ll explore the different AbstractSecurityInterceptor implementations, which were introduced in Part I. We then move on to explore how to fine-tune authorization through use of domain access control lists.

11.1 Authorization Architecture

11.1.1 Authorities

As we saw in the technical overview, all Authentication implementations store a list of GrantedAuthority objects. These represent the authorities that have been granted to the principal. the GrantedAuthority objects are inserted into the Authentication object by the AuthenticationManager and are later read by AccessDecisionManager s when making authorization decisions.

GrantedAuthority is an interface with only one method:

String getAuthority();

This method allows AccessDecisionManager s to obtain a precise String representation of the GrantedAuthority. By returning a representation as a String, a GrantedAuthority can be easily "read" by most AccessDecisionManager s. If a GrantedAuthority cannot be precisely represented as a String, the GrantedAuthority is considered "complex" and getAuthority() must return null.

An example of a "complex" GrantedAuthority would be an implementation that stores a list of operations and authority thresholds that apply to different customer account numbers. Representing this complex GrantedAuthority as a String would be quite difficult, and as a result the getAuthority() method should return null. This will indicate to any AccessDecisionManager that it will need to specifically support the GrantedAuthority implementation in order to understand its contents.

Spring Security includes one concrete GrantedAuthority implementation, SimpleGrantedAuthority. This allows any user-specified String to be converted into a GrantedAuthority. All AuthenticationProvider s included with the security architecture use SimpleGrantedAuthority to populate the Authentication object.

11.1.2 Pre-Invocation Handling

As we’ve also seen in the Technical Overview chapter, Spring Security provides interceptors which control access to secure objects such as method invocations or web requests. A pre-invocation decision on whether the invocation is allowed to proceed is made by the AccessDecisionManager.

The AccessDecisionManager

The AccessDecisionManager is called by the AbstractSecurityInterceptor and is responsible for making final access control decisions. the AccessDecisionManager interface contains three methods:

void decide(Authentication authentication, Object secureObject,
    Collection<ConfigAttribute> attrs) throws AccessDeniedException;

boolean supports(ConfigAttribute attribute);

boolean supports(Class clazz);

The AccessDecisionManager's decide method is passed all the relevant information it needs in order to make an authorization decision. In particular, passing the secure Object enables those arguments contained in the actual secure object invocation to be inspected. For example, let’s assume the secure object was a MethodInvocation. It would be easy to query the MethodInvocation for any Customer argument, and then implement some sort of security logic in the AccessDecisionManager to ensure the principal is permitted to operate on that customer. Implementations are expected to throw an AccessDeniedException if access is denied.

The supports(ConfigAttribute) method is called by the AbstractSecurityInterceptor at startup time to determine if the AccessDecisionManager can process the passed ConfigAttribute. The supports(Class) method is called by a security interceptor implementation to ensure the configured AccessDecisionManager supports the type of secure object that the security interceptor will present.

Voting-Based AccessDecisionManager Implementations

Whilst users can implement their own AccessDecisionManager to control all aspects of authorization, Spring Security includes several AccessDecisionManager implementations that are based on voting. Figure 11.1, “Voting Decision Manager” illustrates the relevant classes.

Figure 11.1. Voting Decision Manager

access decision voting

Using this approach, a series of AccessDecisionVoter implementations are polled on an authorization decision. The AccessDecisionManager then decides whether or not to throw an AccessDeniedException based on its assessment of the votes.

The AccessDecisionVoter interface has three methods:

int vote(Authentication authentication, Object object, Collection<ConfigAttribute> attrs);

boolean supports(ConfigAttribute attribute);

boolean supports(Class clazz);

Concrete implementations return an int, with possible values being reflected in the AccessDecisionVoter static fields ACCESS_ABSTAIN, ACCESS_DENIED and ACCESS_GRANTED. A voting implementation will return ACCESS_ABSTAIN if it has no opinion on an authorization decision. If it does have an opinion, it must return either ACCESS_DENIED or ACCESS_GRANTED.

There are three concrete AccessDecisionManager s provided with Spring Security that tally the votes. The ConsensusBased implementation will grant or deny access based on the consensus of non-abstain votes. Properties are provided to control behavior in the event of an equality of votes or if all votes are abstain. The AffirmativeBased implementation will grant access if one or more ACCESS_GRANTED votes were received (i.e. a deny vote will be ignored, provided there was at least one grant vote). Like the ConsensusBased implementation, there is a parameter that controls the behavior if all voters abstain. The UnanimousBased provider expects unanimous ACCESS_GRANTED votes in order to grant access, ignoring abstains. It will deny access if there is any ACCESS_DENIED vote. Like the other implementations, there is a parameter that controls the behaviour if all voters abstain.

It is possible to implement a custom AccessDecisionManager that tallies votes differently. For example, votes from a particular AccessDecisionVoter might receive additional weighting, whilst a deny vote from a particular voter may have a veto effect.

RoleVoter

The most commonly used AccessDecisionVoter provided with Spring Security is the simple RoleVoter, which treats configuration attributes as simple role names and votes to grant access if the user has been assigned that role.

It will vote if any ConfigAttribute begins with the prefix ROLE_. It will vote to grant access if there is a GrantedAuthority which returns a String representation (via the getAuthority() method) exactly equal to one or more ConfigAttributes starting with the prefix ROLE_. If there is no exact match of any ConfigAttribute starting with ROLE_, the RoleVoter will vote to deny access. If no ConfigAttribute begins with ROLE_, the voter will abstain.

AuthenticatedVoter

Another voter which we’ve implicitly seen is the AuthenticatedVoter, which can be used to differentiate between anonymous, fully-authenticated and remember-me authenticated users. Many sites allow certain limited access under remember-me authentication, but require a user to confirm their identity by logging in for full access.

When we’ve used the attribute IS_AUTHENTICATED_ANONYMOUSLY to grant anonymous access, this attribute was being processed by the AuthenticatedVoter. See the Javadoc for this class for more information.

Custom Voters

Obviously, you can also implement a custom AccessDecisionVoter and you can put just about any access-control logic you want in it. It might be specific to your application (business-logic related) or it might implement some security administration logic. For example, you’ll find a blog article on the Spring web site which describes how to use a voter to deny access in real-time to users whose accounts have been suspended.

11.1.3 After Invocation Handling

Whilst the AccessDecisionManager is called by the AbstractSecurityInterceptor before proceeding with the secure object invocation, some applications need a way of modifying the object actually returned by the secure object invocation. Whilst you could easily implement your own AOP concern to achieve this, Spring Security provides a convenient hook that has several concrete implementations that integrate with its ACL capabilities.

Figure 11.2, “After Invocation Implementation” illustrates Spring Security’s AfterInvocationManager and its concrete implementations.

Figure 11.2. After Invocation Implementation

after invocation

Like many other parts of Spring Security, AfterInvocationManager has a single concrete implementation, AfterInvocationProviderManager, which polls a list of AfterInvocationProvider s. Each AfterInvocationProvider is allowed to modify the return object or throw an AccessDeniedException. Indeed multiple providers can modify the object, as the result of the previous provider is passed to the next in the list.

Please be aware that if you’re using AfterInvocationManager, you will still need configuration attributes that allow the MethodSecurityInterceptor's AccessDecisionManager to allow an operation. If you’re using the typical Spring Security included AccessDecisionManager implementations, having no configuration attributes defined for a particular secure method invocation will cause each AccessDecisionVoter to abstain from voting. In turn, if the AccessDecisionManager property “allowIfAllAbstainDecisions” is false, an AccessDeniedException will be thrown. You may avoid this potential issue by either (i) setting “allowIfAllAbstainDecisions” to true (although this is generally not recommended) or (ii) simply ensure that there is at least one configuration attribute that an AccessDecisionVoter will vote to grant access for. This latter (recommended) approach is usually achieved through a ROLE_USER or ROLE_AUTHENTICATED configuration attribute.

11.1.4 Hierarchical Roles

It is a common requirement that a particular role in an application should automatically "include" other roles. For example, in an application which has the concept of an "admin" and a "user" role, you may want an admin to be able to do everything a normal user can. To achieve this, you can either make sure that all admin users are also assigned the "user" role. Alternatively, you can modify every access constraint which requires the "user" role to also include the "admin" role. This can get quite complicated if you have a lot of different roles in your application.

The use of a role-hierarchy allows you to configure which roles (or authorities) should include others. An extended version of Spring Security’s RoleVoter, RoleHierarchyVoter, is configured with a RoleHierarchy, from which it obtains all the "reachable authorities" which the user is assigned. A typical configuration might look like this:

<bean id="roleVoter" class="org.springframework.security.access.vote.RoleHierarchyVoter">
    <constructor-arg ref="roleHierarchy" />
</bean>
<bean id="roleHierarchy"
        class="org.springframework.security.access.hierarchicalroles.RoleHierarchyImpl">
    <property name="hierarchy">
        <value>
            ROLE_ADMIN > ROLE_STAFF
            ROLE_STAFF > ROLE_USER
            ROLE_USER > ROLE_GUEST
        </value>
    </property>
</bean>

Here we have four roles in a hierarchy ROLE_ADMIN ⇒ ROLE_STAFF ⇒ ROLE_USER ⇒ ROLE_GUEST. A user who is authenticated with ROLE_ADMIN, will behave as if they have all four roles when security constraints are evaluated against an AccessDecisionManager configured with the above RoleHierarchyVoter. The > symbol can be thought of as meaning "includes".

Role hierarchies offer a convenient means of simplifying the access-control configuration data for your application and/or reducing the number of authorities which you need to assign to a user. For more complex requirements you may wish to define a logical mapping between the specific access-rights your application requires and the roles that are assigned to users, translating between the two when loading the user information.

11.2 Secure Object Implementations

11.2.1 AOP Alliance (MethodInvocation) Security Interceptor

Prior to Spring Security 2.0, securing MethodInvocation s needed quite a lot of boiler plate configuration. Now the recommended approach for method security is to use namespace configuration. This way the method security infrastructure beans are configured automatically for you so you don’t really need to know about the implementation classes. We’ll just provide a quick overview of the classes that are involved here.

Method security is enforced using a MethodSecurityInterceptor, which secures MethodInvocation s. Depending on the configuration approach, an interceptor may be specific to a single bean or shared between multiple beans. The interceptor uses a MethodSecurityMetadataSource instance to obtain the configuration attributes that apply to a particular method invocation. MapBasedMethodSecurityMetadataSource is used to store configuration attributes keyed by method names (which can be wildcarded) and will be used internally when the attributes are defined in the application context using the <intercept-methods> or <protect-point> elements. Other implementations will be used to handle annotation-based configuration.

Explicit MethodSecurityInterceptor Configuration

You can of course configure a MethodSecurityIterceptor directly in your application context for use with one of Spring AOP’s proxying mechanisms:

<bean id="bankManagerSecurity" class=
    "org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="accessDecisionManager" ref="accessDecisionManager"/>
<property name="afterInvocationManager" ref="afterInvocationManager"/>
<property name="securityMetadataSource">
    <sec:method-security-metadata-source>
    <sec:protect method="com.mycompany.BankManager.delete*" access="ROLE_SUPERVISOR"/>
    <sec:protect method="com.mycompany.BankManager.getBalance" access="ROLE_TELLER,ROLE_SUPERVISOR"/>
    </sec:method-security-metadata-source>
</property>
</bean>

11.2.2 AspectJ (JoinPoint) Security Interceptor

The AspectJ security interceptor is very similar to the AOP Alliance security interceptor discussed in the previous section. Indeed we will only discuss the differences in this section.

The AspectJ interceptor is named AspectJSecurityInterceptor. Unlike the AOP Alliance security interceptor, which relies on the Spring application context to weave in the security interceptor via proxying, the AspectJSecurityInterceptor is weaved in via the AspectJ compiler. It would not be uncommon to use both types of security interceptors in the same application, with AspectJSecurityInterceptor being used for domain object instance security and the AOP Alliance MethodSecurityInterceptor being used for services layer security.

Let’s first consider how the AspectJSecurityInterceptor is configured in the Spring application context:

<bean id="bankManagerSecurity" class=
    "org.springframework.security.access.intercept.aspectj.AspectJMethodSecurityInterceptor">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="accessDecisionManager" ref="accessDecisionManager"/>
<property name="afterInvocationManager" ref="afterInvocationManager"/>
<property name="securityMetadataSource">
    <sec:method-security-metadata-source>
    <sec:protect method="com.mycompany.BankManager.delete*" access="ROLE_SUPERVISOR"/>
    <sec:protect method="com.mycompany.BankManager.getBalance" access="ROLE_TELLER,ROLE_SUPERVISOR"/>
    </sec:method-security-metadata-source>
</property>
</bean>

As you can see, aside from the class name, the AspectJSecurityInterceptor is exactly the same as the AOP Alliance security interceptor. Indeed the two interceptors can share the same securityMetadataSource, as the SecurityMetadataSource works with java.lang.reflect.Method s rather than an AOP library-specific class. Of course, your access decisions have access to the relevant AOP library-specific invocation (ie MethodInvocation or JoinPoint) and as such can consider a range of addition criteria when making access decisions (such as method arguments).

Next you’ll need to define an AspectJ aspect. For example:

package org.springframework.security.samples.aspectj;

import org.springframework.security.access.intercept.aspectj.AspectJSecurityInterceptor;
import org.springframework.security.access.intercept.aspectj.AspectJCallback;
import org.springframework.beans.factory.InitializingBean;

public aspect DomainObjectInstanceSecurityAspect implements InitializingBean {

    private AspectJSecurityInterceptor securityInterceptor;

    pointcut domainObjectInstanceExecution(): target(PersistableEntity)
        && execution(public * *(..)) && !within(DomainObjectInstanceSecurityAspect);

    Object around(): domainObjectInstanceExecution() {
        if (this.securityInterceptor == null) {
            return proceed();
        }

        AspectJCallback callback = new AspectJCallback() {
            public Object proceedWithObject() {
                return proceed();
            }
        };

        return this.securityInterceptor.invoke(thisJoinPoint, callback);
    }

    public AspectJSecurityInterceptor getSecurityInterceptor() {
        return securityInterceptor;
    }

    public void setSecurityInterceptor(AspectJSecurityInterceptor securityInterceptor) {
        this.securityInterceptor = securityInterceptor;
    }

    public void afterPropertiesSet() throws Exception {
        if (this.securityInterceptor == null)
            throw new IllegalArgumentException("securityInterceptor required");
        }
    }
}

In the above example, the security interceptor will be applied to every instance of PersistableEntity, which is an abstract class not shown (you can use any other class or pointcut expression you like). For those curious, AspectJCallback is needed because the proceed(); statement has special meaning only within an around() body. The AspectJSecurityInterceptor calls this anonymous AspectJCallback class when it wants the target object to continue.

You will need to configure Spring to load the aspect and wire it with the AspectJSecurityInterceptor. A bean declaration which achieves this is shown below:

<bean id="domainObjectInstanceSecurityAspect"
    class="security.samples.aspectj.DomainObjectInstanceSecurityAspect"
    factory-method="aspectOf">
<property name="securityInterceptor" ref="bankManagerSecurity"/>
</bean>

That’s it! Now you can create your beans from anywhere within your application, using whatever means you think fit (eg new Person();) and they will have the security interceptor applied.

11.3 Expression-Based Access Control

Spring Security 3.0 introduced the ability to use Spring EL expressions as an authorization mechanism in addition to the simple use of configuration attributes and access-decision voters which have seen before. Expression-based access control is built on the same architecture but allows complicated Boolean logic to be encapsulated in a single expression.

11.3.1 Overview

Spring Security uses Spring EL for expression support and you should look at how that works if you are interested in understanding the topic in more depth. Expressions are evaluated with a "root object" as part of the evaluation context. Spring Security uses specific classes for web and method security as the root object, in order to provide built-in expressions and access to values such as the current principal.

Common Built-In Expressions

The base class for expression root objects is SecurityExpressionRoot. This provides some common expressions which are available in both web and method security.

Table 11.1. Common built-in expressions

ExpressionDescription

hasRole([role])

Returns true if the current principal has the specified role. By default if the supplied role does not start with 'ROLE_' it will be added. This can be customized by modifying the defaultRolePrefix on DefaultWebSecurityExpressionHandler.

hasAnyRole([role1,role2])

Returns true if the current principal has any of the supplied roles (given as a comma-separated list of strings). By default if the supplied role does not start with 'ROLE_' it will be added. This can be customized by modifying the defaultRolePrefix on DefaultWebSecurityExpressionHandler.

hasAuthority([authority])

Returns true if the current principal has the specified authority.

hasAnyAuthority([authority1,authority2])

Returns true if the current principal has any of the supplied authorities (given as a comma-separated list of strings)

principal

Allows direct access to the principal object representing the current user

authentication

Allows direct access to the current Authentication object obtained from the SecurityContext

permitAll

Always evaluates to true

denyAll

Always evaluates to false

isAnonymous()

Returns true if the current principal is an anonymous user

isRememberMe()

Returns true if the current principal is a remember-me user

isAuthenticated()

Returns true if the user is not anonymous

isFullyAuthenticated()

Returns true if the user is not an anonymous or a remember-me user

hasPermission(Object target, Object permission)

Returns true if the user has access to the provided target for the given permission. For example, hasPermission(domainObject, 'read')

hasPermission(Object targetId, String targetType, Object permission)

Returns true if the user has access to the provided target for the given permission. For example, hasPermission(1, 'com.example.domain.Message', 'read')


11.3.2 Web Security Expressions

To use expressions to secure individual URLs, you would first need to set the use-expressions attribute in the <http> element to true. Spring Security will then expect the access attributes of the <intercept-url> elements to contain Spring EL expressions. The expressions should evaluate to a Boolean, defining whether access should be allowed or not. For example:

<http>
    <intercept-url pattern="/admin*"
        access="hasRole('admin') and hasIpAddress('192.168.1.0/24')"/>
    ...
</http>

Here we have defined that the "admin" area of an application (defined by the URL pattern) should only be available to users who have the granted authority "admin" and whose IP address matches a local subnet. We’ve already seen the built-in hasRole expression in the previous section. The expression hasIpAddress is an additional built-in expression which is specific to web security. It is defined by the WebSecurityExpressionRoot class, an instance of which is used as the expression root object when evaluation web-access expressions. This object also directly exposed the HttpServletRequest object under the name request so you can invoke the request directly in an expression. If expressions are being used, a WebExpressionVoter will be added to the AccessDecisionManager which is used by the namespace. So if you aren’t using the namespace and want to use expressions, you will have to add one of these to your configuration.

Referring to Beans in Web Security Expressions

If you wish to extend the expressions that are available, you can easily refer to any Spring Bean you expose. For example, assuming you have a Bean with the name of webSecurity that contains the following method signature:

public class WebSecurity {
        public boolean check(Authentication authentication, HttpServletRequest request) {
                ...
        }
}

You could refer to the method using:

<http>
    <intercept-url pattern="/user/**"
        access="@webSecurity.check(authentication,request)"/>
    ...
</http>

or in Java configuration

http
        .authorizeRequests()
                .antMatchers("/user/**").access("@webSecurity.check(authentication,request)")
                ...

Path Variables in Web Security Expressions

At times it is nice to be able to refer to path variables within a URL. For example, consider a RESTful application that looks up a user by id from the URL path in the format /user/{userId}.

You can easily refer to the path variable by placing it in the pattern. For example, if you had a Bean with the name of webSecurity that contains the following method signature:

public class WebSecurity {
        public boolean checkUserId(Authentication authentication, int id) {
                ...
        }
}

You could refer to the method using:

<http>
    <intercept-url pattern="/user/{userId}/**"
        access="@webSecurity.checkUserId(authentication,#userId)"/>
    ...
</http>

or in Java configuration

http
    .authorizeRequests(authorizeRequests ->
        authorizeRequests
            .antMatchers("/user/{userId}/**").access("@webSecurity.checkUserId(authentication,#userId)")
            ...
    );

In both configurations URLs that match would pass in the path variable (and convert it) into checkUserId method. For example, if the URL were /user/123/resource, then the id passed in would be 123.

11.3.3 Method Security Expressions

Method security is a bit more complicated than a simple allow or deny rule. Spring Security 3.0 introduced some new annotations in order to allow comprehensive support for the use of expressions.

@Pre and @Post Annotations

There are four annotations which support expression attributes to allow pre and post-invocation authorization checks and also to support filtering of submitted collection arguments or return values. They are @PreAuthorize, @PreFilter, @PostAuthorize and @PostFilter. Their use is enabled through the global-method-security namespace element:

<global-method-security pre-post-annotations="enabled"/>
Access Control using @PreAuthorize and @PostAuthorize

The most obviously useful annotation is @PreAuthorize which decides whether a method can actually be invoked or not. For example (from the"Contacts" sample application)

@PreAuthorize("hasRole('USER')")
public void create(Contact contact);

which means that access will only be allowed for users with the role "ROLE_USER". Obviously the same thing could easily be achieved using a traditional configuration and a simple configuration attribute for the required role. But what about:

@PreAuthorize("hasPermission(#contact, 'admin')")
public void deletePermission(Contact contact, Sid recipient, Permission permission);

Here we’re actually using a method argument as part of the expression to decide whether the current user has the "admin"permission for the given contact. The built-in hasPermission() expression is linked into the Spring Security ACL module through the application context, as we’llsee below. You can access any of the method arguments by name as expression variables.

There are a number of ways in which Spring Security can resolve the method arguments. Spring Security uses DefaultSecurityParameterNameDiscoverer to discover the parameter names. By default, the following options are tried for a method as a whole.

  • If Spring Security’s @P annotation is present on a single argument to the method, the value will be used. This is useful for interfaces compiled with a JDK prior to JDK 8 which do not contain any information about the parameter names. For example:

    import org.springframework.security.access.method.P;
    
    ...
    
    @PreAuthorize("#c.name == authentication.name")
    public void doSomething(@P("c") Contact contact);

    Behind the scenes this use implemented using AnnotationParameterNameDiscoverer which can be customized to support the value attribute of any specified annotation.

  • If Spring Data’s @Param annotation is present on at least one parameter for the method, the value will be used. This is useful for interfaces compiled with a JDK prior to JDK 8 which do not contain any information about the parameter names. For example:

    import org.springframework.data.repository.query.Param;
    
    ...
    
    @PreAuthorize("#n == authentication.name")
    Contact findContactByName(@Param("n") String name);

    Behind the scenes this use implemented using AnnotationParameterNameDiscoverer which can be customized to support the value attribute of any specified annotation.

  • If JDK 8 was used to compile the source with the -parameters argument and Spring 4+ is being used, then the standard JDK reflection API is used to discover the parameter names. This works on both classes and interfaces.
  • Last, if the code was compiled with the debug symbols, the parameter names will be discovered using the debug symbols. This will not work for interfaces since they do not have debug information about the parameter names. For interfaces, annotations or the JDK 8 approach must be used.

Any Spring-EL functionality is available within the expression, so you can also access properties on the arguments. For example, if you wanted a particular method to only allow access to a user whose username matched that of the contact, you could write

@PreAuthorize("#contact.name == authentication.name")
public void doSomething(Contact contact);

Here we are accessing another built-in expression, authentication, which is the Authentication stored in the security context. You can also access its "principal" property directly, using the expression principal. The value will often be a UserDetails instance, so you might use an expression like principal.username or principal.enabled.

Less commonly, you may wish to perform an access-control check after the method has been invoked. This can be achieved using the @PostAuthorize annotation. To access the return value from a method, use the built-in name returnObject in the expression.

Filtering using @PreFilter and @PostFilter

As you may already be aware, Spring Security supports filtering of collections and arrays and this can now be achieved using expressions. This is most commonly performed on the return value of a method. For example:

@PreAuthorize("hasRole('USER')")
@PostFilter("hasPermission(filterObject, 'read') or hasPermission(filterObject, 'admin')")
public List<Contact> getAll();

When using the @PostFilter annotation, Spring Security iterates through the returned collection and removes any elements for which the supplied expression is false. The name filterObject refers to the current object in the collection. You can also filter before the method call, using @PreFilter, though this is a less common requirement. The syntax is just the same, but if there is more than one argument which is a collection type then you have to select one by name using the filterTarget property of this annotation.

Note that filtering is obviously not a substitute for tuning your data retrieval queries. If you are filtering large collections and removing many of the entries then this is likely to be inefficient.

Built-In Expressions

There are some built-in expressions which are specific to method security, which we have already seen in use above. The filterTarget and returnValue values are simple enough, but the use of the hasPermission() expression warrants a closer look.

The PermissionEvaluator interface

hasPermission() expressions are delegated to an instance of PermissionEvaluator. It is intended to bridge between the expression system and Spring Security’s ACL system, allowing you to specify authorization constraints on domain objects, based on abstract permissions. It has no explicit dependencies on the ACL module, so you could swap that out for an alternative implementation if required. The interface has two methods:

boolean hasPermission(Authentication authentication, Object targetDomainObject,
                            Object permission);

boolean hasPermission(Authentication authentication, Serializable targetId,
                            String targetType, Object permission);

which map directly to the available versions of the expression, with the exception that the first argument (the Authentication object) is not supplied. The first is used in situations where the domain object, to which access is being controlled, is already loaded. Then expression will return true if the current user has the given permission for that object. The second version is used in cases where the object is not loaded, but its identifier is known. An abstract "type" specifier for the domain object is also required, allowing the correct ACL permissions to be loaded. This has traditionally been the Java class of the object, but does not have to be as long as it is consistent with how the permissions are loaded.

To use hasPermission() expressions, you have to explicitly configure a PermissionEvaluator in your application context. This would look something like this:

<security:global-method-security pre-post-annotations="enabled">
<security:expression-handler ref="expressionHandler"/>
</security:global-method-security>

<bean id="expressionHandler" class=
"org.springframework.security.access.expression.method.DefaultMethodSecurityExpressionHandler">
    <property name="permissionEvaluator" ref="myPermissionEvaluator"/>
</bean>

Where myPermissionEvaluator is the bean which implements PermissionEvaluator. Usually this will be the implementation from the ACL module which is called AclPermissionEvaluator. See the "Contacts" sample application configuration for more details.

Method Security Meta Annotations

You can make use of meta annotations for method security to make your code more readable. This is especially convenient if you find that you are repeating the same complex expression throughout your code base. For example, consider the following:

@PreAuthorize("#contact.name == authentication.name")

Instead of repeating this everywhere, we can create a meta annotation that can be used instead.

@Retention(RetentionPolicy.RUNTIME)
@PreAuthorize("#contact.name == authentication.name")
public @interface ContactPermission {}

Meta annotations can be used for any of the Spring Security method security annotations. In order to remain compliant with the specification JSR-250 annotations do not support meta annotations.

11.4 Authorize Requests

Our examples have only required users to be authenticated and have done so for every URL in our application. We can specify custom requirements for our URLs by adding multiple children to our http.authorizeRequests() method. For example:

protected void configure(HttpSecurity http) throws Exception {
    http
        .authorizeRequests(authorizeRequests ->                                        1
            authorizeRequests
                .antMatchers("/resources/**", "/signup", "/about").permitAll()         2
                .antMatchers("/admin/**").hasRole("ADMIN")                             3
                .antMatchers("/db/**").access("hasRole('ADMIN') and hasRole('DBA')")   4
                .anyRequest().authenticated()                                          5
        )
        .formLogin(withDefaults());
}

1

There are multiple children to the http.authorizeRequests() method each matcher is considered in the order they were declared.

2

We specified multiple URL patterns that any user can access. Specifically, any user can access a request if the URL starts with "/resources/", equals "/signup", or equals "/about".

3

Any URL that starts with "/admin/" will be restricted to users who have the role "ROLE_ADMIN". You will notice that since we are invoking the hasRole method we do not need to specify the "ROLE_" prefix.

4

Any URL that starts with "/db/" requires the user to have both "ROLE_ADMIN" and "ROLE_DBA". You will notice that since we are using the hasRole expression we do not need to specify the "ROLE_" prefix.

5

Any URL that has not already been matched on only requires that the user be authenticated

11.5 Method Security

From version 2.0 onwards Spring Security has improved support substantially for adding security to your service layer methods. It provides support for JSR-250 annotation security as well as the framework’s original @Secured annotation. From 3.0 you can also make use of new expression-based annotations. You can apply security to a single bean, using the intercept-methods element to decorate the bean declaration, or you can secure multiple beans across the entire service layer using the AspectJ style pointcuts.

11.5.1 EnableGlobalMethodSecurity

We can enable annotation-based security using the @EnableGlobalMethodSecurity annotation on any @Configuration instance. For example, the following would enable Spring Security’s @Secured annotation.

@EnableGlobalMethodSecurity(securedEnabled = true)
public class MethodSecurityConfig {
// ...
}

Adding an annotation to a method (on a class or interface) would then limit the access to that method accordingly. Spring Security’s native annotation support defines a set of attributes for the method. These will be passed to the AccessDecisionManager for it to make the actual decision:

public interface BankService {

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account readAccount(Long id);

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account[] findAccounts();

@Secured("ROLE_TELLER")
public Account post(Account account, double amount);
}

Support for JSR-250 annotations can be enabled using

@EnableGlobalMethodSecurity(jsr250Enabled = true)
public class MethodSecurityConfig {
// ...
}

These are standards-based and allow simple role-based constraints to be applied but do not have the power Spring Security’s native annotations. To use the new expression-based syntax, you would use

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class MethodSecurityConfig {
// ...
}

and the equivalent Java code would be

public interface BankService {

@PreAuthorize("isAnonymous()")
public Account readAccount(Long id);

@PreAuthorize("isAnonymous()")
public Account[] findAccounts();

@PreAuthorize("hasAuthority('ROLE_TELLER')")
public Account post(Account account, double amount);
}

11.5.2 GlobalMethodSecurityConfiguration

Sometimes you may need to perform operations that are more complicated than are possible with the @EnableGlobalMethodSecurity annotation allow. For these instances, you can extend the GlobalMethodSecurityConfiguration ensuring that the @EnableGlobalMethodSecurity annotation is present on your subclass. For example, if you wanted to provide a custom MethodSecurityExpressionHandler, you could use the following configuration:

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class MethodSecurityConfig extends GlobalMethodSecurityConfiguration {
    @Override
    protected MethodSecurityExpressionHandler createExpressionHandler() {
        // ... create and return custom MethodSecurityExpressionHandler ...
        return expressionHandler;
    }
}

For additional information about methods that can be overridden, refer to the GlobalMethodSecurityConfiguration Javadoc.

11.5.3 The <global-method-security> Element

This element is used to enable annotation-based security in your application (by setting the appropriate attributes on the element), and also to group together security pointcut declarations which will be applied across your entire application context. You should only declare one <global-method-security> element. The following declaration would enable support for Spring Security’s @Secured:

<global-method-security secured-annotations="enabled" />

Adding an annotation to a method (on an class or interface) would then limit the access to that method accordingly. Spring Security’s native annotation support defines a set of attributes for the method. These will be passed to the AccessDecisionManager for it to make the actual decision:

public interface BankService {

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account readAccount(Long id);

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account[] findAccounts();

@Secured("ROLE_TELLER")
public Account post(Account account, double amount);
}

Support for JSR-250 annotations can be enabled using

<global-method-security jsr250-annotations="enabled" />

These are standards-based and allow simple role-based constraints to be applied but do not have the power Spring Security’s native annotations. To use the new expression-based syntax, you would use

<global-method-security pre-post-annotations="enabled" />

and the equivalent Java code would be

public interface BankService {

@PreAuthorize("isAnonymous()")
public Account readAccount(Long id);

@PreAuthorize("isAnonymous()")
public Account[] findAccounts();

@PreAuthorize("hasAuthority('ROLE_TELLER')")
public Account post(Account account, double amount);
}

Expression-based annotations are a good choice if you need to define simple rules that go beyond checking the role names against the user’s list of authorities.

[Note]Note

=== The annotated methods will only be secured for instances which are defined as Spring beans (in the same application context in which method-security is enabled). If you want to secure instances which are not created by Spring (using the new operator, for example) then you need to use AspectJ. ===

[Note]Note

=== You can enable more than one type of annotation in the same application, but only one type should be used for any interface or class as the behaviour will not be well-defined otherwise. If two annotations are found which apply to a particular method, then only one of them will be applied. ===

11.5.4 Adding Security Pointcuts using protect-pointcut

The use of protect-pointcut is particularly powerful, as it allows you to apply security to many beans with only a simple declaration. Consider the following example:

<global-method-security>
<protect-pointcut expression="execution(* com.mycompany.*Service.*(..))"
    access="ROLE_USER"/>
</global-method-security>

This will protect all methods on beans declared in the application context whose classes are in the com.mycompany package and whose class names end in "Service". Only users with the ROLE_USER role will be able to invoke these methods. As with URL matching, the most specific matches must come first in the list of pointcuts, as the first matching expression will be used. Security annotations take precedence over pointcuts.

11.6 Domain Object Security (ACLs)

11.6.1 Overview

Complex applications often will find the need to define access permissions not simply at a web request or method invocation level. Instead, security decisions need to comprise both who (Authentication), where (MethodInvocation) and what (SomeDomainObject). In other words, authorization decisions also need to consider the actual domain object instance subject of a method invocation.

Imagine you’re designing an application for a pet clinic. There will be two main groups of users of your Spring-based application: staff of the pet clinic, as well as the pet clinic’s customers. The staff will have access to all of the data, whilst your customers will only be able to see their own customer records. To make it a little more interesting, your customers can allow other users to see their customer records, such as their "puppy preschool" mentor or president of their local "Pony Club". Using Spring Security as the foundation, you have several approaches that can be used:

  • Write your business methods to enforce the security. You could consult a collection within the Customer domain object instance to determine which users have access. By using the SecurityContextHolder.getContext().getAuthentication(), you’ll be able to access the Authentication object.
  • Write an AccessDecisionVoter to enforce the security from the GrantedAuthority[] s stored in the Authentication object. This would mean your AuthenticationManager would need to populate the Authentication with custom GrantedAuthority[]s representing each of the Customer domain object instances the principal has access to.
  • Write an AccessDecisionVoter to enforce the security and open the target Customer domain object directly. This would mean your voter needs access to a DAO that allows it to retrieve the Customer object. It would then access the Customer object’s collection of approved users and make the appropriate decision.

Each one of these approaches is perfectly legitimate. However, the first couples your authorization checking to your business code. The main problems with this include the enhanced difficulty of unit testing and the fact it would be more difficult to reuse the Customer authorization logic elsewhere. Obtaining the GrantedAuthority[] s from the Authentication object is also fine, but will not scale to large numbers of Customer s. If a user might be able to access 5,000 Customer s (unlikely in this case, but imagine if it were a popular vet for a large Pony Club!) the amount of memory consumed and time required to construct the Authentication object would be undesirable. The final method, opening the Customer directly from external code, is probably the best of the three. It achieves separation of concerns, and doesn’t misuse memory or CPU cycles, but it is still inefficient in that both the AccessDecisionVoter and the eventual business method itself will perform a call to the DAO responsible for retrieving the Customer object. Two accesses per method invocation is clearly undesirable. In addition, with every approach listed you’ll need to write your own access control list (ACL) persistence and business logic from scratch.

Fortunately, there is another alternative, which we’ll talk about below.

11.6.2 Key Concepts

Spring Security’s ACL services are shipped in the spring-security-acl-xxx.jar. You will need to add this JAR to your classpath to use Spring Security’s domain object instance security capabilities.

Spring Security’s domain object instance security capabilities centre on the concept of an access control list (ACL). Every domain object instance in your system has its own ACL, and the ACL records details of who can and can’t work with that domain object. With this in mind, Spring Security delivers three main ACL-related capabilities to your application:

  • A way of efficiently retrieving ACL entries for all of your domain objects (and modifying those ACLs)
  • A way of ensuring a given principal is permitted to work with your objects, before methods are called
  • A way of ensuring a given principal is permitted to work with your objects (or something they return), after methods are called

As indicated by the first bullet point, one of the main capabilities of the Spring Security ACL module is providing a high-performance way of retrieving ACLs. This ACL repository capability is extremely important, because every domain object instance in your system might have several access control entries, and each ACL might inherit from other ACLs in a tree-like structure (this is supported out-of-the-box by Spring Security, and is very commonly used). Spring Security’s ACL capability has been carefully designed to provide high performance retrieval of ACLs, together with pluggable caching, deadlock-minimizing database updates, independence from ORM frameworks (we use JDBC directly), proper encapsulation, and transparent database updating.

Given databases are central to the operation of the ACL module, let’s explore the four main tables used by default in the implementation. The tables are presented below in order of size in a typical Spring Security ACL deployment, with the table with the most rows listed last:

  • ACL_SID allows us to uniquely identify any principal or authority in the system ("SID" stands for "security identity"). The only columns are the ID, a textual representation of the SID, and a flag to indicate whether the textual representation refers to a principal name or a GrantedAuthority. Thus, there is a single row for each unique principal or GrantedAuthority. When used in the context of receiving a permission, a SID is generally called a "recipient".
  • ACL_CLASS allows us to uniquely identify any domain object class in the system. The only columns are the ID and the Java class name. Thus, there is a single row for each unique Class we wish to store ACL permissions for.
  • ACL_OBJECT_IDENTITY stores information for each unique domain object instance in the system. Columns include the ID, a foreign key to the ACL_CLASS table, a unique identifier so we know which ACL_CLASS instance we’re providing information for, the parent, a foreign key to the ACL_SID table to represent the owner of the domain object instance, and whether we allow ACL entries to inherit from any parent ACL. We have a single row for every domain object instance we’re storing ACL permissions for.
  • Finally, ACL_ENTRY stores the individual permissions assigned to each recipient. Columns include a foreign key to the ACL_OBJECT_IDENTITY, the recipient (ie a foreign key to ACL_SID), whether we’ll be auditing or not, and the integer bit mask that represents the actual permission being granted or denied. We have a single row for every recipient that receives a permission to work with a domain object.

As mentioned in the last paragraph, the ACL system uses integer bit masking. Don’t worry, you need not be aware of the finer points of bit shifting to use the ACL system, but suffice to say that we have 32 bits we can switch on or off. Each of these bits represents a permission, and by default the permissions are read (bit 0), write (bit 1), create (bit 2), delete (bit 3) and administer (bit 4). It’s easy to implement your own Permission instance if you wish to use other permissions, and the remainder of the ACL framework will operate without knowledge of your extensions.

It is important to understand that the number of domain objects in your system has absolutely no bearing on the fact we’ve chosen to use integer bit masking. Whilst you have 32 bits available for permissions, you could have billions of domain object instances (which will mean billions of rows in ACL_OBJECT_IDENTITY and quite probably ACL_ENTRY). We make this point because we’ve found sometimes people mistakenly believe they need a bit for each potential domain object, which is not the case.

Now that we’ve provided a basic overview of what the ACL system does, and what it looks like at a table structure, let’s explore the key interfaces. The key interfaces are:

  • Acl: Every domain object has one and only one Acl object, which internally holds the AccessControlEntry s as well as knows the owner of the Acl. An Acl does not refer directly to the domain object, but instead to an ObjectIdentity. The Acl is stored in the ACL_OBJECT_IDENTITY table.
  • AccessControlEntry: An Acl holds multiple AccessControlEntry s, which are often abbreviated as ACEs in the framework. Each ACE refers to a specific tuple of Permission, Sid and Acl. An ACE can also be granting or non-granting and contain audit settings. The ACE is stored in the ACL_ENTRY table.
  • Permission: A permission represents a particular immutable bit mask, and offers convenience functions for bit masking and outputting information. The basic permissions presented above (bits 0 through 4) are contained in the BasePermission class.
  • Sid: The ACL module needs to refer to principals and GrantedAuthority[] s. A level of indirection is provided by the Sid interface, which is an abbreviation of "security identity". Common classes include PrincipalSid (to represent the principal inside an Authentication object) and GrantedAuthoritySid. The security identity information is stored in the ACL_SID table.
  • ObjectIdentity: Each domain object is represented internally within the ACL module by an ObjectIdentity. The default implementation is called ObjectIdentityImpl.
  • AclService: Retrieves the Acl applicable for a given ObjectIdentity. In the included implementation (JdbcAclService), retrieval operations are delegated to a LookupStrategy. The LookupStrategy provides a highly optimized strategy for retrieving ACL information, using batched retrievals (BasicLookupStrategy) and supporting custom implementations that leverage materialized views, hierarchical queries and similar performance-centric, non-ANSI SQL capabilities.
  • MutableAclService: Allows a modified Acl to be presented for persistence. It is not essential to use this interface if you do not wish.

Please note that our out-of-the-box AclService and related database classes all use ANSI SQL. This should therefore work with all major databases. At the time of writing, the system had been successfully tested using Hypersonic SQL, PostgreSQL, Microsoft SQL Server and Oracle.

Two samples ship with Spring Security that demonstrate the ACL module. The first is the Contacts Sample, and the other is the Document Management System (DMS) Sample. We suggest taking a look over these for examples.

11.6.3 Getting Started

To get starting using Spring Security’s ACL capability, you will need to store your ACL information somewhere. This necessitates the instantiation of a DataSource using Spring. The DataSource is then injected into a JdbcMutableAclService and BasicLookupStrategy instance. The latter provides high-performance ACL retrieval capabilities, and the former provides mutator capabilities. Refer to one of the samples that ship with Spring Security for an example configuration. You’ll also need to populate the database with the four ACL-specific tables listed in the last section (refer to the ACL samples for the appropriate SQL statements).

Once you’ve created the required schema and instantiated JdbcMutableAclService, you’ll next need to ensure your domain model supports interoperability with the Spring Security ACL package. Hopefully ObjectIdentityImpl will prove sufficient, as it provides a large number of ways in which it can be used. Most people will have domain objects that contain a public Serializable getId() method. If the return type is long, or compatible with long (eg an int), you will find you need not give further consideration to ObjectIdentity issues. Many parts of the ACL module rely on long identifiers. If you’re not using long (or an int, byte etc), there is a very good chance you’ll need to reimplement a number of classes. We do not intend to support non-long identifiers in Spring Security’s ACL module, as longs are already compatible with all database sequences, the most common identifier data type, and are of sufficient length to accommodate all common usage scenarios.

The following fragment of code shows how to create an Acl, or modify an existing Acl:

// Prepare the information we'd like in our access control entry (ACE)
ObjectIdentity oi = new ObjectIdentityImpl(Foo.class, new Long(44));
Sid sid = new PrincipalSid("Samantha");
Permission p = BasePermission.ADMINISTRATION;

// Create or update the relevant ACL
MutableAcl acl = null;
try {
acl = (MutableAcl) aclService.readAclById(oi);
} catch (NotFoundException nfe) {
acl = aclService.createAcl(oi);
}

// Now grant some permissions via an access control entry (ACE)
acl.insertAce(acl.getEntries().length, p, sid, true);
aclService.updateAcl(acl);

In the example above, we’re retrieving the ACL associated with the "Foo" domain object with identifier number 44. We’re then adding an ACE so that a principal named "Samantha" can "administer" the object. The code fragment is relatively self-explanatory, except the insertAce method. The first argument to the insertAce method is determining at what position in the Acl the new entry will be inserted. In the example above, we’re just putting the new ACE at the end of the existing ACEs. The final argument is a Boolean indicating whether the ACE is granting or denying. Most of the time it will be granting (true), but if it is denying (false), the permissions are effectively being blocked.

Spring Security does not provide any special integration to automatically create, update or delete ACLs as part of your DAO or repository operations. Instead, you will need to write code like shown above for your individual domain objects. It’s worth considering using AOP on your services layer to automatically integrate the ACL information with your services layer operations. We’ve found this quite an effective approach in the past.

Once you’ve used the above techniques to store some ACL information in the database, the next step is to actually use the ACL information as part of authorization decision logic. You have a number of choices here. You could write your own AccessDecisionVoter or AfterInvocationProvider that respectively fires before or after a method invocation. Such classes would use AclService to retrieve the relevant ACL and then call Acl.isGranted(Permission[] permission, Sid[] sids, boolean administrativeMode) to decide whether permission is granted or denied. Alternately, you could use our AclEntryVoter, AclEntryAfterInvocationProvider or AclEntryAfterInvocationCollectionFilteringProvider classes. All of these classes provide a declarative-based approach to evaluating ACL information at runtime, freeing you from needing to write any code. Please refer to the sample applications to learn how to use these classes.

12. OAuth2

12.1 OAuth 2.0 Login

The OAuth 2.0 Login feature provides an application with the capability to have users log in to the application by using their existing account at an OAuth 2.0 Provider (e.g. GitHub) or OpenID Connect 1.0 Provider (such as Google). OAuth 2.0 Login implements the use cases: "Login with Google" or "Login with GitHub".

[Note]Note

OAuth 2.0 Login is implemented by using the Authorization Code Grant, as specified in the OAuth 2.0 Authorization Framework and OpenID Connect Core 1.0.

12.1.1 Spring Boot 2.x Sample

Spring Boot 2.x brings full auto-configuration capabilities for OAuth 2.0 Login.

This section shows how to configure the OAuth 2.0 Login sample using Google as the Authentication Provider and covers the following topics:

Initial setup

To use Google’s OAuth 2.0 authentication system for login, you must set up a project in the Google API Console to obtain OAuth 2.0 credentials.

[Note]Note

Google’s OAuth 2.0 implementation for authentication conforms to the OpenID Connect 1.0 specification and is OpenID Certified.

Follow the instructions on the OpenID Connect page, starting in the section, "Setting up OAuth 2.0".

After completing the "Obtain OAuth 2.0 credentials" instructions, you should have a new OAuth Client with credentials consisting of a Client ID and a Client Secret.

Setting the redirect URI

The redirect URI is the path in the application that the end-user’s user-agent is redirected back to after they have authenticated with Google and have granted access to the OAuth Client (created in the previous step) on the Consent page.

In the "Set a redirect URI" sub-section, ensure that the Authorized redirect URIs field is set to http://localhost:8080/login/oauth2/code/google.

[Tip]Tip

The default redirect URI template is {baseUrl}/login/oauth2/code/{registrationId}. The registrationId is a unique identifier for the ClientRegistration.

[Important]Important

If the OAuth Client is running behind a proxy server, it is recommended to check Proxy Server Configuration to ensure the application is correctly configured. Also, see the supported URI template variables for redirect-uri.

Configure application.yml

Now that you have a new OAuth Client with Google, you need to configure the application to use the OAuth Client for the authentication flow. To do so:

  1. Go to application.yml and set the following configuration:

    spring:
      security:
        oauth2:
          client:
            registration:   1
              google:   2
                client-id: google-client-id
                client-secret: google-client-secret

    Example 12.1. OAuth Client properties

    1

    spring.security.oauth2.client.registration is the base property prefix for OAuth Client properties.

    2

    Following the base property prefix is the ID for the ClientRegistration, such as google.


  2. Replace the values in the client-id and client-secret property with the OAuth 2.0 credentials you created earlier.

Boot up the application

Launch the Spring Boot 2.x sample and go to http://localhost:8080. You are then redirected to the default auto-generated login page, which displays a link for Google.

Click on the Google link, and you are then redirected to Google for authentication.

After authenticating with your Google account credentials, the next page presented to you is the Consent screen. The Consent screen asks you to either allow or deny access to the OAuth Client you created earlier. Click Allow to authorize the OAuth Client to access your email address and basic profile information.

At this point, the OAuth Client retrieves your email address and basic profile information from the UserInfo Endpoint and establishes an authenticated session.

12.1.2 Spring Boot 2.x Property Mappings

The following table outlines the mapping of the Spring Boot 2.x OAuth Client properties to the ClientRegistration properties.

Spring Boot 2.xClientRegistration

spring.security.oauth2.client.registration.[registrationId]

registrationId

spring.security.oauth2.client.registration.[registrationId].client-id

clientId

spring.security.oauth2.client.registration.[registrationId].client-secret

clientSecret

spring.security.oauth2.client.registration.[registrationId].client-authentication-method

clientAuthenticationMethod

spring.security.oauth2.client.registration.[registrationId].authorization-grant-type

authorizationGrantType

spring.security.oauth2.client.registration.[registrationId].redirect-uri

redirectUriTemplate

spring.security.oauth2.client.registration.[registrationId].scope

scopes

spring.security.oauth2.client.registration.[registrationId].client-name

clientName

spring.security.oauth2.client.provider.[providerId].authorization-uri

providerDetails.authorizationUri

spring.security.oauth2.client.provider.[providerId].token-uri

providerDetails.tokenUri

spring.security.oauth2.client.provider.[providerId].jwk-set-uri

providerDetails.jwkSetUri

spring.security.oauth2.client.provider.[providerId].user-info-uri

providerDetails.userInfoEndpoint.uri

spring.security.oauth2.client.provider.[providerId].user-info-authentication-method

providerDetails.userInfoEndpoint.authenticationMethod

spring.security.oauth2.client.provider.[providerId].userNameAttribute

providerDetails.userInfoEndpoint.userNameAttributeName

[Tip]Tip

A ClientRegistration can be initially configured using discovery of an OpenID Connect Provider’s Configuration endpoint or an Authorization Server’s Metadata endpoint, by specifying the spring.security.oauth2.client.provider.[providerId].issuer-uri property.

12.1.3 CommonOAuth2Provider

CommonOAuth2Provider pre-defines a set of default client properties for a number of well known providers: Google, GitHub, Facebook, and Okta.

For example, the authorization-uri, token-uri, and user-info-uri do not change often for a Provider. Therefore, it makes sense to provide default values in order to reduce the required configuration.

As demonstrated previously, when we configured a Google client, only the client-id and client-secret properties are required.

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          google:
            client-id: google-client-id
            client-secret: google-client-secret
[Tip]Tip

The auto-defaulting of client properties works seamlessly here because the registrationId (google) matches the GOOGLE enum (case-insensitive) in CommonOAuth2Provider.

For cases where you may want to specify a different registrationId, such as google-login, you can still leverage auto-defaulting of client properties by configuring the provider property.

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          google-login: 1
            provider: google    2
            client-id: google-client-id
            client-secret: google-client-secret

1

The registrationId is set to google-login.

2

The provider property is set to google, which will leverage the auto-defaulting of client properties set in CommonOAuth2Provider.GOOGLE.getBuilder().

12.1.4 Configuring Custom Provider Properties

There are some OAuth 2.0 Providers that support multi-tenancy, which results in different protocol endpoints for each tenant (or sub-domain).

For example, an OAuth Client registered with Okta is assigned to a specific sub-domain and have their own protocol endpoints.

For these cases, Spring Boot 2.x provides the following base property for configuring custom provider properties: spring.security.oauth2.client.provider.[providerId].

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
        provider:
          okta: 1
            authorization-uri: https://your-subdomain.oktapreview.com/oauth2/v1/authorize
            token-uri: https://your-subdomain.oktapreview.com/oauth2/v1/token
            user-info-uri: https://your-subdomain.oktapreview.com/oauth2/v1/userinfo
            user-name-attribute: sub
            jwk-set-uri: https://your-subdomain.oktapreview.com/oauth2/v1/keys

1

The base property (spring.security.oauth2.client.provider.okta) allows for custom configuration of protocol endpoint locations.

12.1.5 Overriding Spring Boot 2.x Auto-configuration

The Spring Boot 2.x auto-configuration class for OAuth Client support is OAuth2ClientAutoConfiguration.

It performs the following tasks:

  • Registers a ClientRegistrationRepository @Bean composed of ClientRegistration(s) from the configured OAuth Client properties.
  • Provides a WebSecurityConfigurerAdapter @Configuration and enables OAuth 2.0 Login through httpSecurity.oauth2Login().

If you need to override the auto-configuration based on your specific requirements, you may do so in the following ways:

Register a ClientRegistrationRepository @Bean

The following example shows how to register a ClientRegistrationRepository @Bean:

@Configuration
public class OAuth2LoginConfig {

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
    }

    private ClientRegistration googleClientRegistration() {
        return ClientRegistration.withRegistrationId("google")
            .clientId("google-client-id")
            .clientSecret("google-client-secret")
            .clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
            .authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
            .redirectUriTemplate("{baseUrl}/login/oauth2/code/{registrationId}")
            .scope("openid", "profile", "email", "address", "phone")
            .authorizationUri("https://accounts.google.com/o/oauth2/v2/auth")
            .tokenUri("https://www.googleapis.com/oauth2/v4/token")
            .userInfoUri("https://www.googleapis.com/oauth2/v3/userinfo")
            .userNameAttributeName(IdTokenClaimNames.SUB)
            .jwkSetUri("https://www.googleapis.com/oauth2/v3/certs")
            .clientName("Google")
            .build();
    }
}

Provide a WebSecurityConfigurerAdapter

The following example shows how to provide a WebSecurityConfigurerAdapter with @EnableWebSecurity and enable OAuth 2.0 login through httpSecurity.oauth2Login():

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests(authorizeRequests ->
                authorizeRequests
                    .anyRequest().authenticated()
            )
            .oauth2Login(withDefaults());
    }
}

Completely Override the Auto-configuration

The following example shows how to completely override the auto-configuration by registering a ClientRegistrationRepository @Bean and providing a WebSecurityConfigurerAdapter.

@Configuration
public class OAuth2LoginConfig {

    @EnableWebSecurity
    public static class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                .authorizeRequests(authorizeRequests ->
                    authorizeRequests
                        .anyRequest().authenticated()
                )
                .oauth2Login(withDefaults());
        }
    }

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
    }

    private ClientRegistration googleClientRegistration() {
        return ClientRegistration.withRegistrationId("google")
            .clientId("google-client-id")
            .clientSecret("google-client-secret")
            .clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
            .authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
            .redirectUriTemplate("{baseUrl}/login/oauth2/code/{registrationId}")
            .scope("openid", "profile", "email", "address", "phone")
            .authorizationUri("https://accounts.google.com/o/oauth2/v2/auth")
            .tokenUri("https://www.googleapis.com/oauth2/v4/token")
            .userInfoUri("https://www.googleapis.com/oauth2/v3/userinfo")
            .userNameAttributeName(IdTokenClaimNames.SUB)
            .jwkSetUri("https://www.googleapis.com/oauth2/v3/certs")
            .clientName("Google")
            .build();
    }
}

12.1.6 Java Configuration without Spring Boot 2.x

If you are not able to use Spring Boot 2.x and would like to configure one of the pre-defined providers in CommonOAuth2Provider (for example, Google), apply the following configuration:

@Configuration
public class OAuth2LoginConfig {

    @EnableWebSecurity
    public static class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                .authorizeRequests(authorizeRequests ->
                    authorizeRequests
                        .anyRequest().authenticated()
                )
                .oauth2Login(withDefaults());
        }
    }

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
    }

    @Bean
    public OAuth2AuthorizedClientService authorizedClientService(
            ClientRegistrationRepository clientRegistrationRepository) {
        return new InMemoryOAuth2AuthorizedClientService(clientRegistrationRepository);
    }

    @Bean
    public OAuth2AuthorizedClientRepository authorizedClientRepository(
            OAuth2AuthorizedClientService authorizedClientService) {
        return new AuthenticatedPrincipalOAuth2AuthorizedClientRepository(authorizedClientService);
    }

    private ClientRegistration googleClientRegistration() {
        return CommonOAuth2Provider.GOOGLE.getBuilder("google")
            .clientId("google-client-id")
            .clientSecret("google-client-secret")
            .build();
    }
}

12.1.7 Advanced Configuration

HttpSecurity.oauth2Login() provides a number of configuration options for customizing OAuth 2.0 Login. The main configuration options are grouped into their protocol endpoint counterparts.

For example, oauth2Login().authorizationEndpoint() allows configuring the Authorization Endpoint, whereas oauth2Login().tokenEndpoint() allows configuring the Token Endpoint.

The following code shows an example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .authorizationEndpoint(authorizationEndpoint ->
                        authorizationEndpoint
                            ...
                    )
                    .redirectionEndpoint(redirectionEndpoint ->
                        redirectionEndpoint
                            ...
                    )
                    .tokenEndpoint(tokenEndpoint ->
                        tokenEndpoint
                            ...
                    )
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            ...
                    )
            );
    }
}

The main goal of the oauth2Login() DSL was to closely align with the naming, as defined in the specifications.

The OAuth 2.0 Authorization Framework defines the Protocol Endpoints as follows:

The authorization process utilizes two authorization server endpoints (HTTP resources):

  • Authorization Endpoint: Used by the client to obtain authorization from the resource owner via user-agent redirection.
  • Token Endpoint: Used by the client to exchange an authorization grant for an access token, typically with client authentication.

As well as one client endpoint:

  • Redirection Endpoint: Used by the authorization server to return responses containing authorization credentials to the client via the resource owner user-agent.

The OpenID Connect Core 1.0 specification defines the UserInfo Endpoint as follows:

The UserInfo Endpoint is an OAuth 2.0 Protected Resource that returns claims about the authenticated end-user. To obtain the requested claims about the end-user, the client makes a request to the UserInfo Endpoint by using an access token obtained through OpenID Connect Authentication. These claims are normally represented by a JSON object that contains a collection of name-value pairs for the claims.

The following code shows the complete configuration options available for the oauth2Login() DSL:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .clientRegistrationRepository(this.clientRegistrationRepository())
                    .authorizedClientRepository(this.authorizedClientRepository())
                    .authorizedClientService(this.authorizedClientService())
                    .loginPage("/login")
                    .authorizationEndpoint(authorizationEndpoint ->
                        authorizationEndpoint
                            .baseUri(this.authorizationRequestBaseUri())
                            .authorizationRequestRepository(this.authorizationRequestRepository())
                            .authorizationRequestResolver(this.authorizationRequestResolver())
                    )
                    .redirectionEndpoint(redirectionEndpoint ->
                         redirectionEndpoint
                            .baseUri(this.authorizationResponseBaseUri())
                    )
                    .tokenEndpoint(tokenEndpoint ->
                        tokenEndpoint
                            .accessTokenResponseClient(this.accessTokenResponseClient())
                    )
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            .userAuthoritiesMapper(this.userAuthoritiesMapper())
                            .userService(this.oauth2UserService())
                            .oidcUserService(this.oidcUserService())
                            .customUserType(GitHubOAuth2User.class, "github")
                    )
            );
    }
}

The following sections go into more detail on each of the configuration options available:

OAuth 2.0 Login Page

By default, the OAuth 2.0 Login Page is auto-generated by the DefaultLoginPageGeneratingFilter. The default login page shows each configured OAuth Client with its ClientRegistration.clientName as a link, which is capable of initiating the Authorization Request (or OAuth 2.0 Login).

[Note]Note

In order for DefaultLoginPageGeneratingFilter to show links for configured OAuth Clients, the registered ClientRegistrationRepository needs to also implement Iterable<ClientRegistration>. See InMemoryClientRegistrationRepository for reference.

The link’s destination for each OAuth Client defaults to the following:

OAuth2AuthorizationRequestRedirectFilter.DEFAULT_AUTHORIZATION_REQUEST_BASE_URI + "/{registrationId}"

The following line shows an example:

<a href="/oauth2/authorization/google">Google</a>

To override the default login page, configure oauth2Login().loginPage() and (optionally) oauth2Login().authorizationEndpoint().baseUri().

The following listing shows an example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .loginPage("/login/oauth2")
                    ...
                    .authorizationEndpoint(authorizationEndpoint ->
                        authorizationEndpoint
                            .baseUri("/login/oauth2/authorization")
                            ...
                    )
            );
    }
}
[Important]Important

You need to provide a @Controller with a @RequestMapping("/login/oauth2") that is capable of rendering the custom login page.

[Tip]Tip

As noted earlier, configuring oauth2Login().authorizationEndpoint().baseUri() is optional. However, if you choose to customize it, ensure the link to each OAuth Client matches the authorizationEndpoint().baseUri().

The following line shows an example:

<a href="/login/oauth2/authorization/google">Google</a>

Redirection Endpoint

The Redirection Endpoint is used by the Authorization Server for returning the Authorization Response (which contains the authorization credentials) to the client via the Resource Owner user-agent.

[Tip]Tip

OAuth 2.0 Login leverages the Authorization Code Grant. Therefore, the authorization credential is the authorization code.

The default Authorization Response baseUri (redirection endpoint) is /login/oauth2/code/*, which is defined in OAuth2LoginAuthenticationFilter.DEFAULT_FILTER_PROCESSES_URI.

If you would like to customize the Authorization Response baseUri, configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .redirectionEndpoint(redirectionEndpoint ->
                        redirectionEndpoint
                            .baseUri("/login/oauth2/callback/*")
                            ...
                    )
            );
    }
}
[Important]Important

You also need to ensure the ClientRegistration.redirectUriTemplate matches the custom Authorization Response baseUri.

The following listing shows an example:

return CommonOAuth2Provider.GOOGLE.getBuilder("google")
    .clientId("google-client-id")
    .clientSecret("google-client-secret")
    .redirectUriTemplate("{baseUrl}/login/oauth2/callback/{registrationId}")
    .build();

UserInfo Endpoint

The UserInfo Endpoint includes a number of configuration options, as described in the following sub-sections:

Mapping User Authorities

After the user successfully authenticates with the OAuth 2.0 Provider, the OAuth2User.getAuthorities() (or OidcUser.getAuthorities()) may be mapped to a new set of GrantedAuthority instances, which will be supplied to OAuth2AuthenticationToken when completing the authentication.

[Tip]Tip

OAuth2AuthenticationToken.getAuthorities() is used for authorizing requests, such as in hasRole('USER') or hasRole('ADMIN').

There are a couple of options to choose from when mapping user authorities:

Using a GrantedAuthoritiesMapper

Provide an implementation of GrantedAuthoritiesMapper and configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            .userAuthoritiesMapper(this.userAuthoritiesMapper())
                            ...
                    )
            );
    }

    private GrantedAuthoritiesMapper userAuthoritiesMapper() {
        return (authorities) -> {
            Set<GrantedAuthority> mappedAuthorities = new HashSet<>();

            authorities.forEach(authority -> {
                if (OidcUserAuthority.class.isInstance(authority)) {
                    OidcUserAuthority oidcUserAuthority = (OidcUserAuthority)authority;

                    OidcIdToken idToken = oidcUserAuthority.getIdToken();
                    OidcUserInfo userInfo = oidcUserAuthority.getUserInfo();

                    // Map the claims found in idToken and/or userInfo
                    // to one or more GrantedAuthority's and add it to mappedAuthorities

                } else if (OAuth2UserAuthority.class.isInstance(authority)) {
                    OAuth2UserAuthority oauth2UserAuthority = (OAuth2UserAuthority)authority;

                    Map<String, Object> userAttributes = oauth2UserAuthority.getAttributes();

                    // Map the attributes found in userAttributes
                    // to one or more GrantedAuthority's and add it to mappedAuthorities

                }
            });

            return mappedAuthorities;
        };
    }
}

Alternatively, you may register a GrantedAuthoritiesMapper @Bean to have it automatically applied to the configuration, as shown in the following example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(withDefaults());
    }

    @Bean
    public GrantedAuthoritiesMapper userAuthoritiesMapper() {
        ...
    }
}
Delegation-based strategy with OAuth2UserService

This strategy is advanced compared to using a GrantedAuthoritiesMapper, however, it’s also more flexible as it gives you access to the OAuth2UserRequest and OAuth2User (when using an OAuth 2.0 UserService) or OidcUserRequest and OidcUser (when using an OpenID Connect 1.0 UserService).

The OAuth2UserRequest (and OidcUserRequest) provides you access to the associated OAuth2AccessToken, which is very useful in the cases where the delegator needs to fetch authority information from a protected resource before it can map the custom authorities for the user.

The following example shows how to implement and configure a delegation-based strategy using an OpenID Connect 1.0 UserService:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            .oidcUserService(this.oidcUserService())
                            ...
                    )
            );
    }

    private OAuth2UserService<OidcUserRequest, OidcUser> oidcUserService() {
        final OidcUserService delegate = new OidcUserService();

        return (userRequest) -> {
            // Delegate to the default implementation for loading a user
            OidcUser oidcUser = delegate.loadUser(userRequest);

            OAuth2AccessToken accessToken = userRequest.getAccessToken();
            Set<GrantedAuthority> mappedAuthorities = new HashSet<>();

            // TODO
            // 1) Fetch the authority information from the protected resource using accessToken
            // 2) Map the authority information to one or more GrantedAuthority's and add it to mappedAuthorities

            // 3) Create a copy of oidcUser but use the mappedAuthorities instead
            oidcUser = new DefaultOidcUser(mappedAuthorities, oidcUser.getIdToken(), oidcUser.getUserInfo());

            return oidcUser;
        };
    }
}
Configuring a Custom OAuth2User

CustomUserTypesOAuth2UserService is an implementation of an OAuth2UserService that provides support for custom OAuth2User types.

If the default implementation (DefaultOAuth2User) does not suit your needs, you can define your own implementation of OAuth2User.

The following code demonstrates how you would register a custom OAuth2User type for GitHub:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            .customUserType(GitHubOAuth2User.class, "github")
                            ...
                    )
            );
    }
}

The following code shows an example of a custom OAuth2User type for GitHub:

public class GitHubOAuth2User implements OAuth2User {
    private List<GrantedAuthority> authorities =
        AuthorityUtils.createAuthorityList("ROLE_USER");
    private Map<String, Object> attributes;
    private String id;
    private String name;
    private String login;
    private String email;

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return this.authorities;
    }

    @Override
    public Map<String, Object> getAttributes() {
        if (this.attributes == null) {
            this.attributes = new HashMap<>();
            this.attributes.put("id", this.getId());
            this.attributes.put("name", this.getName());
            this.attributes.put("login", this.getLogin());
            this.attributes.put("email", this.getEmail());
        }
        return attributes;
    }

    public String getId() {
        return this.id;
    }

    public void setId(String id) {
        this.id = id;
    }

    @Override
    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getLogin() {
        return this.login;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    public String getEmail() {
        return this.email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}
[Tip]Tip

id, name, login, and email are attributes returned in GitHub’s UserInfo Response. For detailed information returned from the UserInfo Endpoint, see the API documentation for "Get the authenticated user".

OAuth 2.0 UserService

DefaultOAuth2UserService is an implementation of an OAuth2UserService that supports standard OAuth 2.0 Provider’s.

[Note]Note

OAuth2UserService obtains the user attributes of the end-user (the resource owner) from the UserInfo Endpoint (by using the access token granted to the client during the authorization flow) and returns an AuthenticatedPrincipal in the form of an OAuth2User.

DefaultOAuth2UserService uses a RestOperations when requesting the user attributes at the UserInfo Endpoint.

If you need to customize the pre-processing of the UserInfo Request, you can provide DefaultOAuth2UserService.setRequestEntityConverter() with a custom Converter<OAuth2UserRequest, RequestEntity<?>>. The default implementation OAuth2UserRequestEntityConverter builds a RequestEntity representation of a UserInfo Request that sets the OAuth2AccessToken in the Authorization header by default.

On the other end, if you need to customize the post-handling of the UserInfo Response, you will need to provide DefaultOAuth2UserService.setRestOperations() with a custom configured RestOperations. The default RestOperations is configured as follows:

RestTemplate restTemplate = new RestTemplate();
restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());

OAuth2ErrorResponseErrorHandler is a ResponseErrorHandler that can handle an OAuth 2.0 Error (400 Bad Request). It uses an OAuth2ErrorHttpMessageConverter for converting the OAuth 2.0 Error parameters to an OAuth2Error.

Whether you customize DefaultOAuth2UserService or provide your own implementation of OAuth2UserService, you’ll need to configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            .userService(this.oauth2UserService())
                            ...
                    )
            );
    }

    private OAuth2UserService<OAuth2UserRequest, OAuth2User> oauth2UserService() {
        ...
    }
}
OpenID Connect 1.0 UserService

OidcUserService is an implementation of an OAuth2UserService that supports OpenID Connect 1.0 Provider’s.

The OidcUserService leverages the DefaultOAuth2UserService when requesting the user attributes at the UserInfo Endpoint.

If you need to customize the pre-processing of the UserInfo Request and/or the post-handling of the UserInfo Response, you will need to provide OidcUserService.setOauth2UserService() with a custom configured DefaultOAuth2UserService.

Whether you customize OidcUserService or provide your own implementation of OAuth2UserService for OpenID Connect 1.0 Provider’s, you’ll need to configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .userInfoEndpoint(userInfoEndpoint ->
                        userInfoEndpoint
                            .oidcUserService(this.oidcUserService())
                            ...
                    )
            );
    }

    private OAuth2UserService<OidcUserRequest, OidcUser> oidcUserService() {
        ...
    }
}

ID Token Signature Verification

OpenID Connect 1.0 Authentication introduces the ID Token, which is a security token that contains Claims about the Authentication of an End-User by an Authorization Server when used by a Client.

The ID Token is represented as a JSON Web Token (JWT) and MUST be signed using JSON Web Signature (JWS).

The OidcIdTokenDecoderFactory provides a JwtDecoder used for OidcIdToken signature verification. The default algorithm is RS256 but may be different when assigned during client registration. For these cases, a resolver may be configured to return the expected JWS algorithm assigned for a specific client.

The JWS algorithm resolver is a Function that accepts a ClientRegistration and returns the expected JwsAlgorithm for the client, eg. SignatureAlgorithm.RS256 or MacAlgorithm.HS256

The following code shows how to configure the OidcIdTokenDecoderFactory @Bean to default to MacAlgorithm.HS256 for all ClientRegistration:

@Bean
public JwtDecoderFactory<ClientRegistration> idTokenDecoderFactory() {
    OidcIdTokenDecoderFactory idTokenDecoderFactory = new OidcIdTokenDecoderFactory();
    idTokenDecoderFactory.setJwsAlgorithmResolver(clientRegistration -> MacAlgorithm.HS256);
    return idTokenDecoderFactory;
}
[Note]Note

For MAC based algorithms such as HS256, HS384 or HS512, the client-secret corresponding to the client-id is used as the symmetric key for signature verification.

[Tip]Tip

If more than one ClientRegistration is configured for OpenID Connect 1.0 Authentication, the JWS algorithm resolver may evaluate the provided ClientRegistration to determine which algorithm to return.

OpenID Connect 1.0 Logout

OpenID Connect Session Management 1.0 allows the ability to log out the End-User at the Provider using the Client. One of the strategies available is RP-Initiated Logout.

If the OpenID Provider supports both Session Management and Discovery, the client may obtain the end_session_endpoint URL from the OpenID Provider’s Discovery Metadata. This can be achieved by configuring the ClientRegistration with the issuer-uri, as in the following example:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            ...
        provider:
          okta:
            issuer-uri: https://dev-1234.oktapreview.com

…​and the OidcClientInitiatedLogoutSuccessHandler, which implements RP-Initiated Logout, may be configured as follows:

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private ClientRegistrationRepository clientRegistrationRepository;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests(authorizeRequests ->
                authorizeRequests
                    .anyRequest().authenticated()
            )
            .oauth2Login(withDefaults())
            .logout(logout ->
                logout
                    .logoutSuccessHandler(oidcLogoutSuccessHandler())
            );
    }

    private LogoutSuccessHandler oidcLogoutSuccessHandler() {
        OidcClientInitiatedLogoutSuccessHandler oidcLogoutSuccessHandler =
                new OidcClientInitiatedLogoutSuccessHandler(this.clientRegistrationRepository);

        // Sets the `URI` that the End-User's User Agent will be redirected to
        // after the logout has been performed at the Provider
        oidcLogoutSuccessHandler.setPostLogoutRedirectUri(URI.create("https://localhost:8080"));

        return oidcLogoutSuccessHandler;
    }
}

12.2 OAuth 2.0 Client

The OAuth 2.0 Client features provide support for the Client role as defined in the OAuth 2.0 Authorization Framework.

At a high-level, the core features available are:

HTTP Client support

The HttpSecurity.oauth2Client() DSL provides a number of configuration options for customizing the core components used by OAuth 2.0 Client. In addition, HttpSecurity.oauth2Client().authorizationCodeGrant() enables the customization of the Authorization Code grant.

The following code shows the complete configuration options provided by the HttpSecurity.oauth2Client() DSL:

@EnableWebSecurity
public class OAuth2ClientSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Client(oauth2Client ->
                oauth2Client
                    .clientRegistrationRepository(this.clientRegistrationRepository())
                    .authorizedClientRepository(this.authorizedClientRepository())
                    .authorizedClientService(this.authorizedClientService())
                    .authorizationCodeGrant(authorizationCodeGrant ->
                        authorizationCodeGrant
                            .authorizationRequestRepository(this.authorizationRequestRepository())
                            .authorizationRequestResolver(this.authorizationRequestResolver())
                            .accessTokenResponseClient(this.accessTokenResponseClient())
                    )
            );
    }
}

The OAuth2AuthorizedClientManager is responsible for managing the authorization (or re-authorization) of an OAuth 2.0 Client, in collaboration with one or more OAuth2AuthorizedClientProvider(s).

The following code shows an example of how to register an OAuth2AuthorizedClientManager @Bean and associate it with an OAuth2AuthorizedClientProvider composite that provides support for the authorization_code, refresh_token, client_credentials and password authorization grant types:

@Bean
public OAuth2AuthorizedClientManager authorizedClientManager(
        ClientRegistrationRepository clientRegistrationRepository,
        OAuth2AuthorizedClientRepository authorizedClientRepository) {

    OAuth2AuthorizedClientProvider authorizedClientProvider =
            OAuth2AuthorizedClientProviderBuilder.builder()
                    .authorizationCode()
                    .refreshToken()
                    .clientCredentials()
                    .password()
                    .build();

    DefaultOAuth2AuthorizedClientManager authorizedClientManager =
            new DefaultOAuth2AuthorizedClientManager(
                    clientRegistrationRepository, authorizedClientRepository);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    return authorizedClientManager;
}

The following sections will go into more detail on the core components used by OAuth 2.0 Client and the configuration options available:

12.2.1 Core Interfaces / Classes

ClientRegistration

ClientRegistration is a representation of a client registered with an OAuth 2.0 or OpenID Connect 1.0 Provider.

A client registration holds information, such as client id, client secret, authorization grant type, redirect URI, scope(s), authorization URI, token URI, and other details.

ClientRegistration and its properties are defined as follows:

public final class ClientRegistration {
    private String registrationId;  1
    private String clientId;    2
    private String clientSecret;    3
    private ClientAuthenticationMethod clientAuthenticationMethod;  4
    private AuthorizationGrantType authorizationGrantType;  5
    private String redirectUriTemplate; 6
    private Set<String> scopes; 7
    private ProviderDetails providerDetails;
    private String clientName;  8

    public class ProviderDetails {
        private String authorizationUri;    9
        private String tokenUri;    10
        private UserInfoEndpoint userInfoEndpoint;
        private String jwkSetUri;   11
        private Map<String, Object> configurationMetadata;  12

        public class UserInfoEndpoint {
            private String uri; 13
            private AuthenticationMethod authenticationMethod;  14
            private String userNameAttributeName;   15

        }
    }
}

1

registrationId: The ID that uniquely identifies the ClientRegistration.

2

clientId: The client identifier.

3

clientSecret: The client secret.

4

clientAuthenticationMethod: The method used to authenticate the Client with the Provider. The supported values are basic, post and none (public clients).

5

authorizationGrantType: The OAuth 2.0 Authorization Framework defines four Authorization Grant types. The supported values are authorization_code, client_credentials, password and implicit.

6

redirectUriTemplate: The client’s registered redirect URI that the Authorization Server redirects the end-user’s user-agent to after the end-user has authenticated and authorized access to the client.

7

scopes: The scope(s) requested by the client during the Authorization Request flow, such as openid, email, or profile.

8

clientName: A descriptive name used for the client. The name may be used in certain scenarios, such as when displaying the name of the client in the auto-generated login page.

9

authorizationUri: The Authorization Endpoint URI for the Authorization Server.

10

tokenUri: The Token Endpoint URI for the Authorization Server.

11

jwkSetUri: The URI used to retrieve the JSON Web Key (JWK) Set from the Authorization Server, which contains the cryptographic key(s) used to verify the JSON Web Signature (JWS) of the ID Token and optionally the UserInfo Response.

12

configurationMetadata: The OpenID Provider Configuration Information. This information will only be available if the Spring Boot 2.x property spring.security.oauth2.client.provider.[providerId].issuerUri is configured.

13

(userInfoEndpoint)uri: The UserInfo Endpoint URI used to access the claims/attributes of the authenticated end-user.

14

(userInfoEndpoint)authenticationMethod: The authentication method used when sending the access token to the UserInfo Endpoint. The supported values are header, form and query.

15

userNameAttributeName: The name of the attribute returned in the UserInfo Response that references the Name or Identifier of the end-user.

A ClientRegistration can be initially configured using discovery of an OpenID Connect Provider’s Configuration endpoint or an Authorization Server’s Metadata endpoint.

ClientRegistrations provides convenience methods for configuring a ClientRegistration in this way, as can be seen in the following example:

ClientRegistration clientRegistration =
    ClientRegistrations.fromIssuerLocation("https://idp.example.com/issuer").build();

The above code will query in series https://idp.example.com/issuer/.well-known/openid-configuration, and then https://idp.example.com/.well-known/openid-configuration/issuer, and finally https://idp.example.com/.well-known/oauth-authorization-server/issuer, stopping at the first to return a 200 response.

As an alternative, you can use ClientRegistrations.fromOidcIssuerLocation() to only query the OpenID Connect Provider’s Configuration endpoint.

ClientRegistrationRepository

The ClientRegistrationRepository serves as a repository for OAuth 2.0 / OpenID Connect 1.0 ClientRegistration(s).

[Note]Note

Client registration information is ultimately stored and owned by the associated Authorization Server. This repository provides the ability to retrieve a sub-set of the primary client registration information, which is stored with the Authorization Server.

Spring Boot 2.x auto-configuration binds each of the properties under spring.security.oauth2.client.registration.[registrationId] to an instance of ClientRegistration and then composes each of the ClientRegistration instance(s) within a ClientRegistrationRepository.

[Note]Note

The default implementation of ClientRegistrationRepository is InMemoryClientRegistrationRepository.

The auto-configuration also registers the ClientRegistrationRepository as a @Bean in the ApplicationContext so that it is available for dependency-injection, if needed by the application.

The following listing shows an example:

@Controller
public class OAuth2ClientController {

    @Autowired
    private ClientRegistrationRepository clientRegistrationRepository;

    @GetMapping("/")
    public String index() {
        ClientRegistration oktaRegistration =
            this.clientRegistrationRepository.findByRegistrationId("okta");

        ...

        return "index";
    }
}

OAuth2AuthorizedClient

OAuth2AuthorizedClient is a representation of an Authorized Client. A client is considered to be authorized when the end-user (Resource Owner) has granted authorization to the client to access its protected resources.

OAuth2AuthorizedClient serves the purpose of associating an OAuth2AccessToken (and optional OAuth2RefreshToken) to a ClientRegistration (client) and resource owner, who is the Principal end-user that granted the authorization.

OAuth2AuthorizedClientRepository / OAuth2AuthorizedClientService

OAuth2AuthorizedClientRepository is responsible for persisting OAuth2AuthorizedClient(s) between web requests. Whereas, the primary role of OAuth2AuthorizedClientService is to manage OAuth2AuthorizedClient(s) at the application-level.

From a developer perspective, the OAuth2AuthorizedClientRepository or OAuth2AuthorizedClientService provides the capability to lookup an OAuth2AccessToken associated with a client so that it may be used to initiate a protected resource request.

The following listing shows an example:

@Controller
public class OAuth2ClientController {

    @Autowired
    private OAuth2AuthorizedClientService authorizedClientService;

    @GetMapping("/")
    public String index(Authentication authentication) {
        OAuth2AuthorizedClient authorizedClient =
            this.authorizedClientService.loadAuthorizedClient("okta", authentication.getName());

        OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

        ...

        return "index";
    }
}
[Note]Note

Spring Boot 2.x auto-configuration registers an OAuth2AuthorizedClientRepository and/or OAuth2AuthorizedClientService @Bean in the ApplicationContext. However, the application may choose to override and register a custom OAuth2AuthorizedClientRepository or OAuth2AuthorizedClientService @Bean.

OAuth2AuthorizedClientManager / OAuth2AuthorizedClientProvider

The OAuth2AuthorizedClientManager is responsible for the overall management of OAuth2AuthorizedClient(s).

The primary responsibilities include:

  • Authorizing (or re-authorizing) an OAuth 2.0 Client, using an OAuth2AuthorizedClientProvider.
  • Delegating the persistence of an OAuth2AuthorizedClient, typically using an OAuth2AuthorizedClientService or OAuth2AuthorizedClientRepository.

An OAuth2AuthorizedClientProvider implements a strategy for authorizing (or re-authorizing) an OAuth 2.0 Client. Implementations will typically implement an authorization grant type, eg. authorization_code, client_credentials, etc.

The default implementation of OAuth2AuthorizedClientManager is DefaultOAuth2AuthorizedClientManager, which is associated with an OAuth2AuthorizedClientProvider that may support multiple authorization grant types using a delegation-based composite. The OAuth2AuthorizedClientProviderBuilder may be used to configure and build the delegation-based composite.

The following code shows an example of how to configure and build an OAuth2AuthorizedClientProvider composite that provides support for the authorization_code, refresh_token, client_credentials and password authorization grant types:

@Bean
public OAuth2AuthorizedClientManager authorizedClientManager(
        ClientRegistrationRepository clientRegistrationRepository,
        OAuth2AuthorizedClientRepository authorizedClientRepository) {

    OAuth2AuthorizedClientProvider authorizedClientProvider =
            OAuth2AuthorizedClientProviderBuilder.builder()
                    .authorizationCode()
                    .refreshToken()
                    .clientCredentials()
                    .password()
                    .build();

    DefaultOAuth2AuthorizedClientManager authorizedClientManager =
            new DefaultOAuth2AuthorizedClientManager(
                    clientRegistrationRepository, authorizedClientRepository);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    return authorizedClientManager;
}

The DefaultOAuth2AuthorizedClientManager is also associated with a contextAttributesMapper of type Function<OAuth2AuthorizeRequest, Map<String, Object>>, which is responsible for mapping attribute(s) from the OAuth2AuthorizeRequest to a Map of attributes to be associated to the OAuth2AuthorizationContext. This can be useful when you need to supply an OAuth2AuthorizedClientProvider with required (supported) attribute(s), eg. the PasswordOAuth2AuthorizedClientProvider requires the resource owner’s username and password to be available in OAuth2AuthorizationContext.getAttributes().

The following code shows an example of the contextAttributesMapper:

@Bean
public OAuth2AuthorizedClientManager authorizedClientManager(
        ClientRegistrationRepository clientRegistrationRepository,
        OAuth2AuthorizedClientRepository authorizedClientRepository) {

    OAuth2AuthorizedClientProvider authorizedClientProvider =
            OAuth2AuthorizedClientProviderBuilder.builder()
                    .password()
                    .refreshToken()
                    .build();

    DefaultOAuth2AuthorizedClientManager authorizedClientManager =
            new DefaultOAuth2AuthorizedClientManager(
                    clientRegistrationRepository, authorizedClientRepository);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    // Assuming the `username` and `password` are supplied as `HttpServletRequest` parameters,
    // map the `HttpServletRequest` parameters to `OAuth2AuthorizationContext.getAttributes()`
    authorizedClientManager.setContextAttributesMapper(contextAttributesMapper());

    return authorizedClientManager;
}

private Function<OAuth2AuthorizeRequest, Map<String, Object>> contextAttributesMapper() {
    return authorizeRequest -> {
        Map<String, Object> contextAttributes = Collections.emptyMap();
        HttpServletRequest servletRequest = authorizeRequest.getAttribute(HttpServletRequest.class.getName());
        String username = servletRequest.getParameter(OAuth2ParameterNames.USERNAME);
        String password = servletRequest.getParameter(OAuth2ParameterNames.PASSWORD);
        if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
            contextAttributes = new HashMap<>();

            // `PasswordOAuth2AuthorizedClientProvider` requires both attributes
            contextAttributes.put(OAuth2AuthorizationContext.USERNAME_ATTRIBUTE_NAME, username);
            contextAttributes.put(OAuth2AuthorizationContext.PASSWORD_ATTRIBUTE_NAME, password);
        }
        return contextAttributes;
    };
}

12.2.2 Authorization Grant Support

Authorization Code

[Note]Note

Please refer to the OAuth 2.0 Authorization Framework for further details on the Authorization Code grant.

Obtaining Authorization
[Note]Note

Please refer to the Authorization Request/Response protocol flow for the Authorization Code grant.

Initiating the Authorization Request

The OAuth2AuthorizationRequestRedirectFilter uses an OAuth2AuthorizationRequestResolver to resolve an OAuth2AuthorizationRequest and initiate the Authorization Code grant flow by redirecting the end-user’s user-agent to the Authorization Server’s Authorization Endpoint.

The primary role of the OAuth2AuthorizationRequestResolver is to resolve an OAuth2AuthorizationRequest from the provided web request. The default implementation DefaultOAuth2AuthorizationRequestResolver matches on the (default) path /oauth2/authorization/{registrationId} extracting the registrationId and using it to build the OAuth2AuthorizationRequest for the associated ClientRegistration.

Given the following Spring Boot 2.x properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: authorization_code
            redirect-uri: "{baseUrl}/authorized/okta"
            scope: read, write
        provider:
          okta:
            authorization-uri: https://dev-1234.oktapreview.com/oauth2/v1/authorize
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

A request with the base path /oauth2/authorization/okta will initiate the Authorization Request redirect by the OAuth2AuthorizationRequestRedirectFilter and ultimately start the Authorization Code grant flow.

[Note]Note

The AuthorizationCodeOAuth2AuthorizedClientProvider is an implementation of OAuth2AuthorizedClientProvider for the Authorization Code grant, which also initiates the Authorization Request redirect by the OAuth2AuthorizationRequestRedirectFilter.

If the OAuth 2.0 Client is a Public Client, then configure the OAuth 2.0 Client registration as follows:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-authentication-method: none
            authorization-grant-type: authorization_code
            redirect-uri: "{baseUrl}/authorized/okta"
            ...

Public Clients are supported using Proof Key for Code Exchange (PKCE). If the client is running in an untrusted environment (eg. native application or web browser-based application) and therefore incapable of maintaining the confidentiality of it’s credentials, PKCE will automatically be used when the following conditions are true:

  1. client-secret is omitted (or empty)
  2. client-authentication-method is set to "none" (ClientAuthenticationMethod.NONE)

The DefaultOAuth2AuthorizationRequestResolver also supports URI template variables for the redirect-uri using UriComponentsBuilder.

The following configuration uses all the supported URI template variables:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            ...
            redirect-uri: "{baseScheme}://{baseHost}{basePort}{basePath}/authorized/{registrationId}"
            ...
[Note]Note

{baseUrl} resolves to {baseScheme}://{baseHost}{basePort}{basePath}

Configuring the redirect-uri with URI template variables is especially useful when the OAuth 2.0 Client is running behind a Proxy Server. This ensures that the X-Forwarded-* headers are used when expanding the redirect-uri.

Customizing the Authorization Request

One of the primary use cases an OAuth2AuthorizationRequestResolver can realize is the ability to customize the Authorization Request with additional parameters above the standard parameters defined in the OAuth 2.0 Authorization Framework.

For example, OpenID Connect defines additional OAuth 2.0 request parameters for the Authorization Code Flow extending from the standard parameters defined in the OAuth 2.0 Authorization Framework. One of those extended parameters is the prompt parameter.

[Note]Note

OPTIONAL. Space delimited, case sensitive list of ASCII string values that specifies whether the Authorization Server prompts the End-User for reauthentication and consent. The defined values are: none, login, consent, select_account

The following example shows how to implement an OAuth2AuthorizationRequestResolver that customizes the Authorization Request for oauth2Login(), by including the request parameter prompt=consent.

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private ClientRegistrationRepository clientRegistrationRepository;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests(authorizeRequests ->
                authorizeRequests
                    .anyRequest().authenticated()
            )
            .oauth2Login(oauth2Login ->
                oauth2Login
                    .authorizationEndpoint(authorizationEndpoint ->
                        authorizationEndpoint
                            .authorizationRequestResolver(
                                new CustomAuthorizationRequestResolver(
                                        this.clientRegistrationRepository))    1
                    )
            );
    }
}

public class CustomAuthorizationRequestResolver implements OAuth2AuthorizationRequestResolver {
    private final OAuth2AuthorizationRequestResolver defaultAuthorizationRequestResolver;

    public CustomAuthorizationRequestResolver(
            ClientRegistrationRepository clientRegistrationRepository) {

        this.defaultAuthorizationRequestResolver =
                new DefaultOAuth2AuthorizationRequestResolver(
                        clientRegistrationRepository, "/oauth2/authorization");
    }

    @Override
    public OAuth2AuthorizationRequest resolve(HttpServletRequest request) {
        OAuth2AuthorizationRequest authorizationRequest =
                this.defaultAuthorizationRequestResolver.resolve(request);  2

        return authorizationRequest != null ?   3
                customAuthorizationRequest(authorizationRequest) :
                null;
    }

    @Override
    public OAuth2AuthorizationRequest resolve(
            HttpServletRequest request, String clientRegistrationId) {

        OAuth2AuthorizationRequest authorizationRequest =
                this.defaultAuthorizationRequestResolver.resolve(
                    request, clientRegistrationId);    4

        return authorizationRequest != null ?   5
                customAuthorizationRequest(authorizationRequest) :
                null;
    }

    private OAuth2AuthorizationRequest customAuthorizationRequest(
            OAuth2AuthorizationRequest authorizationRequest) {

        Map<String, Object> additionalParameters =
                new LinkedHashMap<>(authorizationRequest.getAdditionalParameters());
        additionalParameters.put("prompt", "consent");  6

        return OAuth2AuthorizationRequest.from(authorizationRequest)    7
                .additionalParameters(additionalParameters) 8
                .build();
    }
}

1

Configure the custom OAuth2AuthorizationRequestResolver

2 4

Attempt to resolve the OAuth2AuthorizationRequest using the DefaultOAuth2AuthorizationRequestResolver

3 5

If an OAuth2AuthorizationRequest was resolved than return a customized version else return null

6

Add custom parameters to the existing OAuth2AuthorizationRequest.additionalParameters

7

Create a copy of the default OAuth2AuthorizationRequest which returns an OAuth2AuthorizationRequest.Builder for further modifications

8

Override the default additionalParameters

[Tip]Tip

OAuth2AuthorizationRequest.Builder.build() constructs the OAuth2AuthorizationRequest.authorizationRequestUri, which represents the complete Authorization Request URI including all query parameters using the application/x-www-form-urlencoded format.

For the simple use case, where the additional request parameter is always the same for a specific provider, it can be added directly in the authorization-uri.

For example, if the value for the request parameter prompt is always consent for the provider okta, than simply configure as follows:

spring:
  security:
    oauth2:
      client:
        provider:
          okta:
            authorization-uri: https://dev-1234.oktapreview.com/oauth2/v1/authorize?prompt=consent

The preceding example shows the common use case of adding a custom parameter on top of the standard parameters. Alternatively, if your requirements are more advanced, than you can take full control in building the Authorization Request URI by simply overriding the OAuth2AuthorizationRequest.authorizationRequestUri property.

The following example shows a variation of the customAuthorizationRequest() method from the preceding example, and instead overrides the OAuth2AuthorizationRequest.authorizationRequestUri property.

private OAuth2AuthorizationRequest customAuthorizationRequest(
        OAuth2AuthorizationRequest authorizationRequest) {

    String customAuthorizationRequestUri = UriComponentsBuilder
            .fromUriString(authorizationRequest.getAuthorizationRequestUri())
            .queryParam("prompt", "consent")
            .build(true)
            .toUriString();

    return OAuth2AuthorizationRequest.from(authorizationRequest)
            .authorizationRequestUri(customAuthorizationRequestUri)
            .build();
}
Storing the Authorization Request

The AuthorizationRequestRepository is responsible for the persistence of the OAuth2AuthorizationRequest from the time the Authorization Request is initiated to the time the Authorization Response is received (the callback).

[Tip]Tip

The OAuth2AuthorizationRequest is used to correlate and validate the Authorization Response.

The default implementation of AuthorizationRequestRepository is HttpSessionOAuth2AuthorizationRequestRepository, which stores the OAuth2AuthorizationRequest in the HttpSession.

If you have a custom implementation of AuthorizationRequestRepository, you may configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2ClientSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Client(oauth2Client ->
                oauth2Client
                    .authorizationCodeGrant(authorizationCodeGrant ->
                        authorizationCodeGrant
                            .authorizationRequestRepository(this.authorizationRequestRepository())
                            ...
                    )
            );
    }
}
Requesting an Access Token
[Note]Note

Please refer to the Access Token Request/Response protocol flow for the Authorization Code grant.

The default implementation of OAuth2AccessTokenResponseClient for the Authorization Code grant is DefaultAuthorizationCodeTokenResponseClient, which uses a RestOperations for exchanging an authorization code for an access token at the Authorization Server’s Token Endpoint.

The DefaultAuthorizationCodeTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide DefaultAuthorizationCodeTokenResponseClient.setRequestEntityConverter() with a custom Converter<OAuth2AuthorizationCodeGrantRequest, RequestEntity<?>>. The default implementation OAuth2AuthorizationCodeGrantRequestEntityConverter builds a RequestEntity representation of a standard OAuth 2.0 Access Token Request. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

[Important]Important

The custom Converter must return a valid RequestEntity representation of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide DefaultAuthorizationCodeTokenResponseClient.setRestOperations() with a custom configured RestOperations. The default RestOperations is configured as follows:

RestTemplate restTemplate = new RestTemplate(Arrays.asList(
        new FormHttpMessageConverter(),
        new OAuth2AccessTokenResponseHttpMessageConverter()));

restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());
[Tip]Tip

Spring MVC FormHttpMessageConverter is required as it’s used when sending the OAuth 2.0 Access Token Request.

OAuth2AccessTokenResponseHttpMessageConverter is a HttpMessageConverter for an OAuth 2.0 Access Token Response. You can provide OAuth2AccessTokenResponseHttpMessageConverter.setTokenResponseConverter() with a custom Converter<Map<String, String>, OAuth2AccessTokenResponse> that is used for converting the OAuth 2.0 Access Token Response parameters to an OAuth2AccessTokenResponse.

OAuth2ErrorResponseErrorHandler is a ResponseErrorHandler that can handle an OAuth 2.0 Error, eg. 400 Bad Request. It uses an OAuth2ErrorHttpMessageConverter for converting the OAuth 2.0 Error parameters to an OAuth2Error.

Whether you customize DefaultAuthorizationCodeTokenResponseClient or provide your own implementation of OAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2ClientSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Client(oauth2Client ->
                oauth2Client
                    .authorizationCodeGrant(authorizationCodeGrant ->
                        authorizationCodeGrant
                            .accessTokenResponseClient(this.accessTokenResponseClient())
                            ...
                     )
            );
    }
}

Refresh Token

[Note]Note

Please refer to the OAuth 2.0 Authorization Framework for further details on the Refresh Token.

Refreshing an Access Token
[Note]Note

Please refer to the Access Token Request/Response protocol flow for the Refresh Token grant.

The default implementation of OAuth2AccessTokenResponseClient for the Refresh Token grant is DefaultRefreshTokenTokenResponseClient, which uses a RestOperations when refreshing an access token at the Authorization Server’s Token Endpoint.

The DefaultRefreshTokenTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide DefaultRefreshTokenTokenResponseClient.setRequestEntityConverter() with a custom Converter<OAuth2RefreshTokenGrantRequest, RequestEntity<?>>. The default implementation OAuth2RefreshTokenGrantRequestEntityConverter builds a RequestEntity representation of a standard OAuth 2.0 Access Token Request. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

[Important]Important

The custom Converter must return a valid RequestEntity representation of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide DefaultRefreshTokenTokenResponseClient.setRestOperations() with a custom configured RestOperations. The default RestOperations is configured as follows:

RestTemplate restTemplate = new RestTemplate(Arrays.asList(
        new FormHttpMessageConverter(),
        new OAuth2AccessTokenResponseHttpMessageConverter()));

restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());
[Tip]Tip

Spring MVC FormHttpMessageConverter is required as it’s used when sending the OAuth 2.0 Access Token Request.

OAuth2AccessTokenResponseHttpMessageConverter is a HttpMessageConverter for an OAuth 2.0 Access Token Response. You can provide OAuth2AccessTokenResponseHttpMessageConverter.setTokenResponseConverter() with a custom Converter<Map<String, String>, OAuth2AccessTokenResponse> that is used for converting the OAuth 2.0 Access Token Response parameters to an OAuth2AccessTokenResponse.

OAuth2ErrorResponseErrorHandler is a ResponseErrorHandler that can handle an OAuth 2.0 Error, eg. 400 Bad Request. It uses an OAuth2ErrorHttpMessageConverter for converting the OAuth 2.0 Error parameters to an OAuth2Error.

Whether you customize DefaultRefreshTokenTokenResponseClient or provide your own implementation of OAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

// Customize
OAuth2AccessTokenResponseClient<OAuth2RefreshTokenGrantRequest> refreshTokenTokenResponseClient = ...

OAuth2AuthorizedClientProvider authorizedClientProvider =
        OAuth2AuthorizedClientProviderBuilder.builder()
                .authorizationCode()
                .refreshToken(configurer -> configurer.accessTokenResponseClient(refreshTokenTokenResponseClient))
                .build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
[Note]Note

OAuth2AuthorizedClientProviderBuilder.builder().refreshToken() configures a RefreshTokenOAuth2AuthorizedClientProvider, which is an implementation of an OAuth2AuthorizedClientProvider for the Refresh Token grant.

The OAuth2RefreshToken may optionally be returned in the Access Token Response for the authorization_code and password grant types. If the OAuth2AuthorizedClient.getRefreshToken() is available and the OAuth2AuthorizedClient.getAccessToken() is expired, it will automatically be refreshed by the RefreshTokenOAuth2AuthorizedClientProvider.

Client Credentials

[Note]Note

Please refer to the OAuth 2.0 Authorization Framework for further details on the Client Credentials grant.

Requesting an Access Token
[Note]Note

Please refer to the Access Token Request/Response protocol flow for the Client Credentials grant.

The default implementation of OAuth2AccessTokenResponseClient for the Client Credentials grant is DefaultClientCredentialsTokenResponseClient, which uses a RestOperations when requesting an access token at the Authorization Server’s Token Endpoint.

The DefaultClientCredentialsTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide DefaultClientCredentialsTokenResponseClient.setRequestEntityConverter() with a custom Converter<OAuth2ClientCredentialsGrantRequest, RequestEntity<?>>. The default implementation OAuth2ClientCredentialsGrantRequestEntityConverter builds a RequestEntity representation of a standard OAuth 2.0 Access Token Request. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

[Important]Important

The custom Converter must return a valid RequestEntity representation of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide DefaultClientCredentialsTokenResponseClient.setRestOperations() with a custom configured RestOperations. The default RestOperations is configured as follows:

RestTemplate restTemplate = new RestTemplate(Arrays.asList(
        new FormHttpMessageConverter(),
        new OAuth2AccessTokenResponseHttpMessageConverter()));

restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());
[Tip]Tip

Spring MVC FormHttpMessageConverter is required as it’s used when sending the OAuth 2.0 Access Token Request.

OAuth2AccessTokenResponseHttpMessageConverter is a HttpMessageConverter for an OAuth 2.0 Access Token Response. You can provide OAuth2AccessTokenResponseHttpMessageConverter.setTokenResponseConverter() with a custom Converter<Map<String, String>, OAuth2AccessTokenResponse> that is used for converting the OAuth 2.0 Access Token Response parameters to an OAuth2AccessTokenResponse.

OAuth2ErrorResponseErrorHandler is a ResponseErrorHandler that can handle an OAuth 2.0 Error, eg. 400 Bad Request. It uses an OAuth2ErrorHttpMessageConverter for converting the OAuth 2.0 Error parameters to an OAuth2Error.

Whether you customize DefaultClientCredentialsTokenResponseClient or provide your own implementation of OAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

// Customize
OAuth2AccessTokenResponseClient<OAuth2ClientCredentialsGrantRequest> clientCredentialsTokenResponseClient = ...

OAuth2AuthorizedClientProvider authorizedClientProvider =
        OAuth2AuthorizedClientProviderBuilder.builder()
                .clientCredentials(configurer -> configurer.accessTokenResponseClient(clientCredentialsTokenResponseClient))
                .build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
[Note]Note

OAuth2AuthorizedClientProviderBuilder.builder().clientCredentials() configures a ClientCredentialsOAuth2AuthorizedClientProvider, which is an implementation of an OAuth2AuthorizedClientProvider for the Client Credentials grant.

Using the Access Token

Given the following Spring Boot 2.x properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: client_credentials
            scope: read, write
        provider:
          okta:
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

…​and the OAuth2AuthorizedClientManager @Bean:

@Bean
public OAuth2AuthorizedClientManager authorizedClientManager(
        ClientRegistrationRepository clientRegistrationRepository,
        OAuth2AuthorizedClientRepository authorizedClientRepository) {

    OAuth2AuthorizedClientProvider authorizedClientProvider =
            OAuth2AuthorizedClientProviderBuilder.builder()
                    .clientCredentials()
                    .build();

    DefaultOAuth2AuthorizedClientManager authorizedClientManager =
            new DefaultOAuth2AuthorizedClientManager(
                    clientRegistrationRepository, authorizedClientRepository);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    return authorizedClientManager;
}

You may obtain the OAuth2AccessToken as follows:

@Controller
public class OAuth2ClientController {

    @Autowired
    private OAuth2AuthorizedClientManager authorizedClientManager;

    @GetMapping("/")
    public String index(Authentication authentication,
                        HttpServletRequest servletRequest,
                        HttpServletResponse servletResponse) {

        OAuth2AuthorizeRequest authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
                .principal(authentication)
                .attributes(attrs -> {
                    attrs.put(HttpServletRequest.class.getName(), servletRequest);
                    attrs.put(HttpServletResponse.class.getName(), servletResponse);
                })
                .build();
        OAuth2AuthorizedClient authorizedClient = this.authorizedClientManager.authorize(authorizeRequest);

        OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

        ...

        return "index";
    }
}
[Note]Note

HttpServletRequest and HttpServletResponse are both OPTIONAL attributes. If not provided, it will default to ServletRequestAttributes using RequestContextHolder.getRequestAttributes().

Resource Owner Password Credentials

[Note]Note

Please refer to the OAuth 2.0 Authorization Framework for further details on the Resource Owner Password Credentials grant.

Requesting an Access Token
[Note]Note

Please refer to the Access Token Request/Response protocol flow for the Resource Owner Password Credentials grant.

The default implementation of OAuth2AccessTokenResponseClient for the Resource Owner Password Credentials grant is DefaultPasswordTokenResponseClient, which uses a RestOperations when requesting an access token at the Authorization Server’s Token Endpoint.

The DefaultPasswordTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide DefaultPasswordTokenResponseClient.setRequestEntityConverter() with a custom Converter<OAuth2PasswordGrantRequest, RequestEntity<?>>. The default implementation OAuth2PasswordGrantRequestEntityConverter builds a RequestEntity representation of a standard OAuth 2.0 Access Token Request. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

[Important]Important

The custom Converter must return a valid RequestEntity representation of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide DefaultPasswordTokenResponseClient.setRestOperations() with a custom configured RestOperations. The default RestOperations is configured as follows:

RestTemplate restTemplate = new RestTemplate(Arrays.asList(
        new FormHttpMessageConverter(),
        new OAuth2AccessTokenResponseHttpMessageConverter()));

restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());
[Tip]Tip

Spring MVC FormHttpMessageConverter is required as it’s used when sending the OAuth 2.0 Access Token Request.

OAuth2AccessTokenResponseHttpMessageConverter is a HttpMessageConverter for an OAuth 2.0 Access Token Response. You can provide OAuth2AccessTokenResponseHttpMessageConverter.setTokenResponseConverter() with a custom Converter<Map<String, String>, OAuth2AccessTokenResponse> that is used for converting the OAuth 2.0 Access Token Response parameters to an OAuth2AccessTokenResponse.

OAuth2ErrorResponseErrorHandler is a ResponseErrorHandler that can handle an OAuth 2.0 Error, eg. 400 Bad Request. It uses an OAuth2ErrorHttpMessageConverter for converting the OAuth 2.0 Error parameters to an OAuth2Error.

Whether you customize DefaultPasswordTokenResponseClient or provide your own implementation of OAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

// Customize
OAuth2AccessTokenResponseClient<OAuth2PasswordGrantRequest> passwordTokenResponseClient = ...

OAuth2AuthorizedClientProvider authorizedClientProvider =
        OAuth2AuthorizedClientProviderBuilder.builder()
                .password(configurer -> configurer.accessTokenResponseClient(passwordTokenResponseClient))
                .refreshToken()
                .build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
[Note]Note

OAuth2AuthorizedClientProviderBuilder.builder().password() configures a PasswordOAuth2AuthorizedClientProvider, which is an implementation of an OAuth2AuthorizedClientProvider for the Resource Owner Password Credentials grant.

Using the Access Token

Given the following Spring Boot 2.x properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: password
            scope: read, write
        provider:
          okta:
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

…​and the OAuth2AuthorizedClientManager @Bean:

@Bean
public OAuth2AuthorizedClientManager authorizedClientManager(
        ClientRegistrationRepository clientRegistrationRepository,
        OAuth2AuthorizedClientRepository authorizedClientRepository) {

    OAuth2AuthorizedClientProvider authorizedClientProvider =
            OAuth2AuthorizedClientProviderBuilder.builder()
                    .password()
                    .refreshToken()
                    .build();

    DefaultOAuth2AuthorizedClientManager authorizedClientManager =
            new DefaultOAuth2AuthorizedClientManager(
                    clientRegistrationRepository, authorizedClientRepository);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    // Assuming the `username` and `password` are supplied as `HttpServletRequest` parameters,
    // map the `HttpServletRequest` parameters to `OAuth2AuthorizationContext.getAttributes()`
    authorizedClientManager.setContextAttributesMapper(contextAttributesMapper());

    return authorizedClientManager;
}

private Function<OAuth2AuthorizeRequest, Map<String, Object>> contextAttributesMapper() {
    return authorizeRequest -> {
        Map<String, Object> contextAttributes = Collections.emptyMap();
        HttpServletRequest servletRequest = authorizeRequest.getAttribute(HttpServletRequest.class.getName());
        String username = servletRequest.getParameter(OAuth2ParameterNames.USERNAME);
        String password = servletRequest.getParameter(OAuth2ParameterNames.PASSWORD);
        if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
            contextAttributes = new HashMap<>();

            // `PasswordOAuth2AuthorizedClientProvider` requires both attributes
            contextAttributes.put(OAuth2AuthorizationContext.USERNAME_ATTRIBUTE_NAME, username);
            contextAttributes.put(OAuth2AuthorizationContext.PASSWORD_ATTRIBUTE_NAME, password);
        }
        return contextAttributes;
    };
}

You may obtain the OAuth2AccessToken as follows:

@Controller
public class OAuth2ClientController {

    @Autowired
    private OAuth2AuthorizedClientManager authorizedClientManager;

    @GetMapping("/")
    public String index(Authentication authentication,
                        HttpServletRequest servletRequest,
                        HttpServletResponse servletResponse) {

        OAuth2AuthorizeRequest authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
                .principal(authentication)
                .attributes(attrs -> {
                    attrs.put(HttpServletRequest.class.getName(), servletRequest);
                    attrs.put(HttpServletResponse.class.getName(), servletResponse);
                })
                .build();
        OAuth2AuthorizedClient authorizedClient = this.authorizedClientManager.authorize(authorizeRequest);

        OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

        ...

        return "index";
    }
}
[Note]Note

HttpServletRequest and HttpServletResponse are both OPTIONAL attributes. If not provided, it will default to ServletRequestAttributes using RequestContextHolder.getRequestAttributes().

12.2.3 Additional Features

Resolving an Authorized Client

The @RegisteredOAuth2AuthorizedClient annotation provides the capability of resolving a method parameter to an argument value of type OAuth2AuthorizedClient. This is a convenient alternative compared to accessing the OAuth2AuthorizedClient using the OAuth2AuthorizedClientManager or OAuth2AuthorizedClientService.

@Controller
public class OAuth2ClientController {

    @GetMapping("/")
    public String index(@RegisteredOAuth2AuthorizedClient("okta") OAuth2AuthorizedClient authorizedClient) {
        OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

        ...

        return "index";
    }
}

The @RegisteredOAuth2AuthorizedClient annotation is handled by OAuth2AuthorizedClientArgumentResolver, which directly uses an OAuth2AuthorizedClientManager and therefore inherits it’s capabilities.

12.2.4 WebClient integration for Servlet Environments

The OAuth 2.0 Client support integrates with WebClient using an ExchangeFilterFunction.

The ServletOAuth2AuthorizedClientExchangeFilterFunction provides a simple mechanism for requesting protected resources by using an OAuth2AuthorizedClient and including the associated OAuth2AccessToken as a Bearer Token. It directly uses an OAuth2AuthorizedClientManager and therefore inherits the following capabilities:

  • An OAuth2AccessToken will be requested if the client has not yet been authorized.

    • authorization_code - triggers the Authorization Request redirect to initiate the flow
    • client_credentials - the access token is obtained directly from the Token Endpoint
    • password - the access token is obtained directly from the Token Endpoint
  • If the OAuth2AccessToken is expired, it will be refreshed (or renewed) if an OAuth2AuthorizedClientProvider is available to perform the authorization

The following code shows an example of how to configure WebClient with OAuth 2.0 Client support:

@Bean
WebClient webClient(OAuth2AuthorizedClientManager authorizedClientManager) {
    ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2Client =
            new ServletOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
    return WebClient.builder()
            .apply(oauth2Client.oauth2Configuration())
            .build();
}

Providing the Authorized Client

The ServletOAuth2AuthorizedClientExchangeFilterFunction determines the client to use (for a request) by resolving the OAuth2AuthorizedClient from the ClientRequest.attributes() (request attributes).

The following code shows how to set an OAuth2AuthorizedClient as a request attribute:

@GetMapping("/")
public String index(@RegisteredOAuth2AuthorizedClient("okta") OAuth2AuthorizedClient authorizedClient) {
    String resourceUri = ...

    String body = webClient
            .get()
            .uri(resourceUri)
            .attributes(oauth2AuthorizedClient(authorizedClient))   1
            .retrieve()
            .bodyToMono(String.class)
            .block();

    ...

    return "index";
}

1

oauth2AuthorizedClient() is a static method in ServletOAuth2AuthorizedClientExchangeFilterFunction.

The following code shows how to set the ClientRegistration.getRegistrationId() as a request attribute:

@GetMapping("/")
public String index() {
    String resourceUri = ...

    String body = webClient
            .get()
            .uri(resourceUri)
            .attributes(clientRegistrationId("okta"))   1
            .retrieve()
            .bodyToMono(String.class)
            .block();

    ...

    return "index";
}

1

clientRegistrationId() is a static method in ServletOAuth2AuthorizedClientExchangeFilterFunction.

Defaulting the Authorized Client

If neither OAuth2AuthorizedClient or ClientRegistration.getRegistrationId() is provided as a request attribute, the ServletOAuth2AuthorizedClientExchangeFilterFunction can determine the default client to use depending on it’s configuration.

If setDefaultOAuth2AuthorizedClient(true) is configured and the user has authenticated using HttpSecurity.oauth2Login(), the OAuth2AccessToken associated with the current OAuth2AuthenticationToken is used.

The following code shows the specific configuration:

@Bean
WebClient webClient(OAuth2AuthorizedClientManager authorizedClientManager) {
    ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2Client =
            new ServletOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
    oauth2Client.setDefaultOAuth2AuthorizedClient(true);
    return WebClient.builder()
            .apply(oauth2Client.oauth2Configuration())
            .build();
}
[Warning]Warning

It is recommended to be cautious with this feature since all HTTP requests will receive the access token.

Alternatively, if setDefaultClientRegistrationId("okta") is configured with a valid ClientRegistration, the OAuth2AccessToken associated with the OAuth2AuthorizedClient is used.

The following code shows the specific configuration:

@Bean
WebClient webClient(OAuth2AuthorizedClientManager authorizedClientManager) {
    ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2Client =
            new ServletOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
    oauth2Client.setDefaultClientRegistrationId("okta");
    return WebClient.builder()
            .apply(oauth2Client.oauth2Configuration())
            .build();
}
[Warning]Warning

It is recommended to be cautious with this feature since all HTTP requests will receive the access token.

12.3 OAuth 2.0 Resource Server

Spring Security supports protecting endpoints using two forms of OAuth 2.0 Bearer Tokens:

  • JWT
  • Opaque Tokens

This is handy in circumstances where an application has delegated its authority management to an authorization server (for example, Okta or Ping Identity). This authorization server can be consulted by resource servers to authorize requests.

[Note]Note

Working samples for both JWTs and Opaque Tokens are available in the Spring Security repository.

12.3.1 Dependencies

Most Resource Server support is collected into spring-security-oauth2-resource-server. However, the support for decoding and verifying JWTs is in spring-security-oauth2-jose, meaning that both are necessary in order to have a working resource server that supports JWT-encoded Bearer Tokens.

12.3.2 Minimal Configuration for JWTs

When using Spring Boot, configuring an application as a resource server consists of two basic steps. First, include the needed dependencies and second, indicate the location of the authorization server.

Specifying the Authorization Server

In a Spring Boot application, to specify which authorization server to use, simply do:

spring:
  security:
    oauth2:
      resourceserver:
        jwt:
          issuer-uri: https://idp.example.com/issuer

Where https://idp.example.com/issuer is the value contained in the iss claim for JWT tokens that the authorization server will issue. Resource Server will use this property to further self-configure, discover the authorization server’s public keys, and subsequently validate incoming JWTs.

[Note]Note

To use the issuer-uri property, it must also be true that one of https://idp.example.com/issuer/.well-known/openid-configuration, https://idp.example.com/.well-known/openid-configuration/issuer, or https://idp.example.com/.well-known/oauth-authorization-server/issuer is a supported endpoint for the authorization server. This endpoint is referred to as a Provider Configuration endpoint or a Authorization Server Metadata endpoint.

And that’s it!

Startup Expectations

When this property and these dependencies are used, Resource Server will automatically configure itself to validate JWT-encoded Bearer Tokens.

It achieves this through a deterministic startup process:

  1. Hit the Provider Configuration or Authorization Server Metadata endpoint, processing the response for the jwks_url property
  2. Configure the validation strategy to query jwks_url for valid public keys
  3. Configure the validation strategy to validate each JWTs iss claim against https://idp.example.com.

A consequence of this process is that the authorization server must be up and receiving requests in order for Resource Server to successfully start up.

[Note]Note

If the authorization server is down when Resource Server queries it (given appropriate timeouts), then startup will fail.

Runtime Expectations

Once the application is started up, Resource Server will attempt to process any request containing an Authorization: Bearer header:

GET / HTTP/1.1
Authorization: Bearer some-token-value # Resource Server will process this

So long as this scheme is indicated, Resource Server will attempt to process the request according to the Bearer Token specification.

Given a well-formed JWT, Resource Server will:

  1. Validate its signature against a public key obtained from the jwks_url endpoint during startup and matched against the JWTs header
  2. Validate the JWTs exp and nbf timestamps and the JWTs iss claim, and
  3. Map each scope to an authority with the prefix SCOPE_.
[Note]Note

As the authorization server makes available new keys, Spring Security will automatically rotate the keys used to validate the JWT tokens.

The resulting Authentication#getPrincipal, by default, is a Spring Security Jwt object, and Authentication#getName maps to the JWT’s sub property, if one is present.

From here, consider jumping to:

How to Configure without Tying Resource Server startup to an authorization server’s availability

How to Configure without Spring Boot

12.3.3 Specifying the Authorization Server JWK Set Uri Directly

If the authorization server doesn’t support any configuration endpoints, or if Resource Server must be able to start up independently from the authorization server, then the jwk-set-uri can be supplied as well:

spring:
  security:
    oauth2:
      resourceserver:
        jwt:
          issuer-uri: https://idp.example.com
          jwk-set-uri: https://idp.example.com/.well-known/jwks.json
[Note]Note

The JWK Set uri is not standardized, but can typically be found in the authorization server’s documentation

Consequently, Resource Server will not ping the authorization server at startup. We still specify the issuer-uri so that Resource Server still validates the iss claim on incoming JWTs.

[Note]Note

This property can also be supplied directly on the DSL.

12.3.4 Overriding or Replacing Boot Auto Configuration

There are two @Bean s that Spring Boot generates on Resource Server’s behalf.

The first is a WebSecurityConfigurerAdapter that configures the app as a resource server. When including spring-security-oauth2-jose, this WebSecurityConfigurerAdapter looks like:

protected void configure(HttpSecurity http) {
    http
        .authorizeRequests()
            .anyRequest().authenticated()
            .and()
        .oauth2ResourceServer(OAuth2ResourceServerConfigurer::jwt)
}

If the application doesn’t expose a WebSecurityConfigurerAdapter bean, then Spring Boot will expose the above default one.

Replacing this is as simple as exposing the bean within the application:

@EnableWebSecurity
public class MyCustomSecurityConfiguration extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .mvcMatchers("/messages/**").hasAuthority("SCOPE_message:read")
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .jwtAuthenticationConverter(myConverter());
    }
}

The above requires the scope of message:read for any URL that starts with /messages/.

Methods on the oauth2ResourceServer DSL will also override or replace auto configuration.

For example, the second @Bean Spring Boot creates is a JwtDecoder, which decodes String tokens into validated instances of Jwt:

@Bean
public JwtDecoder jwtDecoder() {
    return JwtDecoders.fromIssuerLocation(issuerUri);
}
[Note]Note

Calling JwtDecoders#fromIssuerLocation is what invokes the Provider Configuration or Authorization Server Metadata endpoint in order to derive the JWK Set Uri.

If the application doesn’t expose a JwtDecoder bean, then Spring Boot will expose the above default one.

And its configuration can be overridden using jwkSetUri() or replaced using decoder().

Using jwkSetUri()

An authorization server’s JWK Set Uri can be configured as a configuration property or it can be supplied in the DSL:

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .jwkSetUri("https://idp.example.com/.well-known/jwks.json");
    }
}

Using jwkSetUri() takes precedence over any configuration property.

Using decoder()

More powerful than jwkSetUri() is decoder(), which will completely replace any Boot auto configuration of JwtDecoder:

@EnableWebSecurity
public class DirectlyConfiguredJwtDecoder extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .decoder(myCustomDecoder());
    }
}

This is handy when deeper configuration, like validation, mapping, or request timeouts, is necessary.

Exposing a JwtDecoder @Bean

Or, exposing a JwtDecoder @Bean has the same effect as decoder():

@Bean
public JwtDecoder jwtDecoder() {
    return NimbusJwtDecoder.withJwkSetUri(jwkSetUri).build();
}

12.3.5 Configuring Trusted Algorithms

By default, NimbusJwtDecoder, and hence Resource Server, will only trust and verify tokens using RS256.

You can customize this via Spring Boot, the NimbusJwtDecoder builder, or from the JWK Set response.

Via Spring Boot

The simplest way to set the algorithm is as a property:

spring:
  security:
    oauth2:
      resourceserver:
        jwt:
          jws-algorithm: RS512
          jwk-set-uri: https://idp.example.org/.well-known/jwks.json

Using a Builder

For greater power, though, we can use a builder that ships with NimbusJwtDecoder:

@Bean
JwtDecoder jwtDecoder() {
    return NimbusJwtDecoder.fromJwkSetUri(this.jwkSetUri)
            .jwsAlgorithm(RS512).build();
}

Calling jwsAlgorithm more than once will configure NimbusJwtDecoder to trust more than one algorithm, like so:

@Bean
JwtDecoder jwtDecoder() {
    return NimbusJwtDecoder.fromJwkSetUri(this.jwkSetUri)
            .jwsAlgorithm(RS512).jwsAlgorithm(EC512).build();
}

Or, you can call jwsAlgorithms:

@Bean
JwtDecoder jwtDecoder() {
    return NimbusJwtDecoder.fromJwkSetUri(this.jwkSetUri)
            .jwsAlgorithms(algorithms -> {
                    algorithms.add(RS512);
                    algorithms.add(EC512);
            }).build();
}

From JWK Set response

Since Spring Security’s JWT support is based off of Nimbus, you can use all it’s great features as well.

For example, Nimbus has a JWSKeySelector implementation that will select the set of algorithms based on the JWK Set URI response. You can use it to generate a NimbusJwtDecoder like so:

@Bean
public JwtDecoder jwtDecoder() {
    // makes a request to the JWK Set endpoint
    JWSKeySelector<SecurityContext> jwsKeySelector =
            JWSAlgorithmFamilyJWSKeySelector.fromJWKSetURL(this.jwkSetUrl);

    DefaultJWTProcessor<SecurityContext> jwtProcessor =
            new DefaultJWTProcessor<>();
    jwtProcessor.setJWSKeySelector(jwsKeySelector);

    return new NimbusJwtDecoder(jwtProcessor);
}

12.3.6 Trusting a Single Asymmetric Key

Simpler than backing a Resource Server with a JWK Set endpoint is to hard-code an RSA public key. The public key can be provided via Spring Boot or by Using a Builder.

Via Spring Boot

Specifying a key via Spring Boot is quite simple. The key’s location can be specified like so:

spring:
  security:
    oauth2:
      resourceserver:
        jwt:
          public-key-location: classpath:my-key.pub

Or, to allow for a more sophisticated lookup, you can post-process the RsaKeyConversionServicePostProcessor:

@Bean
BeanFactoryPostProcessor conversionServiceCustomizer() {
    return beanFactory ->
        beanFactory.getBean(RsaKeyConversionServicePostProcessor.class)
                .setResourceLoader(new CustomResourceLoader());
}

Specify your key’s location:

key.location: hfds://my-key.pub

And then autowire the value:

@Value("${key.location}")
RSAPublicKey key;

Using a Builder

To wire an RSAPublicKey directly, you can simply use the appropriate NimbusJwtDecoder builder, like so:

@Bean
public JwtDecoder jwtDecoder() {
    return NimbusJwtDecoder.withPublicKey(this.key).build();
}

12.3.7 Trusting a Single Symmetric Key

Using a single symmetric key is also simple. You can simply load in your SecretKey and use the appropriate NimbusJwtDecoder builder, like so:

@Bean
public JwtDecoder jwtDecoder() {
    return NimbusJwtDecoder.withSecretKey(this.key).build();
}

12.3.8 Configuring Authorization

A JWT that is issued from an OAuth 2.0 Authorization Server will typically either have a scope or scp attribute, indicating the scopes (or authorities) it’s been granted, for example:

{ …​, "scope" : "messages contacts"}

When this is the case, Resource Server will attempt to coerce these scopes into a list of granted authorities, prefixing each scope with the string "SCOPE_".

This means that to protect an endpoint or method with a scope derived from a JWT, the corresponding expressions should include this prefix:

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests(authorizeRequests -> authorizeRequests
                .mvcMatchers("/contacts/**").hasAuthority("SCOPE_contacts")
                .mvcMatchers("/messages/**").hasAuthority("SCOPE_messages")
                .anyRequest().authenticated()
            )
            .oauth2ResourceServer(OAuth2ResourceServerConfigurer::jwt);
    }
}

Or similarly with method security:

@PreAuthorize("hasAuthority('SCOPE_messages')")
public List<Message> getMessages(...) {}

Extracting Authorities Manually

However, there are a number of circumstances where this default is insufficient. For example, some authorization servers don’t use the scope attribute, but instead have their own custom attribute. Or, at other times, the resource server may need to adapt the attribute or a composition of attributes into internalized authorities.

To this end, the DSL exposes jwtAuthenticationConverter():

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .jwtAuthenticationConverter(grantedAuthoritiesExtractor());
    }
}

Converter<Jwt, AbstractAuthenticationToken> grantedAuthoritiesExtractor() {
    JwtAuthenticationConverter jwtAuthenticationConverter =
            new JwtAuthenticationConverter();
    jwtAuthenticationConverter.setJwtGrantedAuthoritiesConverter
            (new GrantedAuthoritiesExtractor());
    return jwtAuthenticationConveter;
}

which is responsible for converting a Jwt into an Authentication. As part of its configuration, we can supply a subsidiary converter to go from Jwt to a Collection of granted authorities.

That final converter might be something like GrantedAuthoritiesExtractor below:

static class GrantedAuthoritiesExtractor
        implements Converter<Jwt, Collection<GrantedAuthority>> {

    public Collection<GrantedAuthority> convert(Jwt jwt) {
        Collection<String> authorities = (Collection<String>)
                jwt.getClaims().get("mycustomclaim");

        return authorities.stream()
                .map(SimpleGrantedAuthority::new)
                .collect(Collectors.toList());
    }
}

For more flexibility, the DSL supports entirely replacing the converter with any class that implements Converter<Jwt, AbstractAuthenticationToken>:

static class CustomAuthenticationConverter implements Converter<Jwt, AbstractAuthenticationToken> {
    public AbstractAuthenticationToken convert(Jwt jwt) {
        return new CustomAuthenticationToken(jwt);
    }
}

12.3.9 Configuring Validation

Using minimal Spring Boot configuration, indicating the authorization server’s issuer uri, Resource Server will default to verifying the iss claim as well as the exp and nbf timestamp claims.

In circumstances where validation needs to be customized, Resource Server ships with two standard validators and also accepts custom OAuth2TokenValidator instances.

Customizing Timestamp Validation

JWT’s typically have a window of validity, with the start of the window indicated in the nbf claim and the end indicated in the exp claim.

However, every server can experience clock drift, which can cause tokens to appear expired to one server, but not to another. This can cause some implementation heartburn as the number of collaborating servers increases in a distributed system.

Resource Server uses JwtTimestampValidator to verify a token’s validity window, and it can be configured with a clockSkew to alleviate the above problem:

@Bean
JwtDecoder jwtDecoder() {
     NimbusJwtDecoder jwtDecoder = (NimbusJwtDecoder)
             JwtDecoders.fromIssuerLocation(issuerUri);

     OAuth2TokenValidator<Jwt> withClockSkew = new DelegatingOAuth2TokenValidator<>(
            new JwtTimestampValidator(Duration.ofSeconds(60)),
            new IssuerValidator(issuerUri));

     jwtDecoder.setJwtValidator(withClockSkew);

     return jwtDecoder;
}
[Note]Note

By default, Resource Server configures a clock skew of 30 seconds.

Configuring a Custom Validator

Adding a check for the aud claim is simple with the OAuth2TokenValidator API:

public class AudienceValidator implements OAuth2TokenValidator<Jwt> {
    OAuth2Error error = new OAuth2Error("invalid_token", "The required audience is missing", null);

    public OAuth2TokenValidatorResult validate(Jwt jwt) {
        if (jwt.getAudience().contains("messaging")) {
            return OAuth2TokenValidatorResult.success();
        } else {
            return OAuth2TokenValidatorResult.failure(error);
        }
    }
}

Then, to add into a resource server, it’s a matter of specifying the JwtDecoder instance:

@Bean
JwtDecoder jwtDecoder() {
    NimbusJwtDecoder jwtDecoder = (NimbusJwtDecoder)
        JwtDecoders.fromIssuerLocation(issuerUri);

    OAuth2TokenValidator<Jwt> audienceValidator = new AudienceValidator();
    OAuth2TokenValidator<Jwt> withIssuer = JwtValidators.createDefaultWithIssuer(issuerUri);
    OAuth2TokenValidator<Jwt> withAudience = new DelegatingOAuth2TokenValidator<>(withIssuer, audienceValidator);

    jwtDecoder.setJwtValidator(withAudience);

    return jwtDecoder;
}

12.3.10 Configuring Claim Set Mapping

Spring Security uses the Nimbus library for parsing JWTs and validating their signatures. Consequently, Spring Security is subject to Nimbus’s interpretation of each field value and how to coerce each into a Java type.

For example, because Nimbus remains Java 7 compatible, it doesn’t use Instant to represent timestamp fields.

And it’s entirely possible to use a different library or for JWT processing, which may make its own coercion decisions that need adjustment.

Or, quite simply, a resource server may want to add or remove claims from a JWT for domain-specific reasons.

For these purposes, Resource Server supports mapping the JWT claim set with MappedJwtClaimSetConverter.

Customizing the Conversion of a Single Claim

By default, MappedJwtClaimSetConverter will attempt to coerce claims into the following types:

Claim

Java Type

aud

Collection<String>

exp

Instant

iat

Instant

iss

String

jti

String

nbf

Instant

sub

String

An individual claim’s conversion strategy can be configured using MappedJwtClaimSetConverter.withDefaults:

@Bean
JwtDecoder jwtDecoder() {
    NimbusJwtDecoder jwtDecoder = NimbusJwtDecoder.withJwkSetUri(jwkSetUri).build();

    MappedJwtClaimSetConverter converter = MappedJwtClaimSetConverter
            .withDefaults(Collections.singletonMap("sub", this::lookupUserIdBySub));
    jwtDecoder.setClaimSetConverter(converter);

    return jwtDecoder;
}

This will keep all the defaults, except it will override the default claim converter for sub.

Adding a Claim

MappedJwtClaimSetConverter can also be used to add a custom claim, for example, to adapt to an existing system:

MappedJwtClaimSetConverter.withDefaults(Collections.singletonMap("custom", custom -> "value"));

Removing a Claim

And removing a claim is also simple, using the same API:

MappedJwtClaimSetConverter.withDefaults(Collections.singletonMap("legacyclaim", legacy -> null));

Renaming a Claim

In more sophisticated scenarios, like consulting multiple claims at once or renaming a claim, Resource Server accepts any class that implements Converter<Map<String, Object>, Map<String,Object>>:

public class UsernameSubClaimAdapter implements Converter<Map<String, Object>, Map<String, Object>> {
    private final MappedJwtClaimSetConverter delegate =
            MappedJwtClaimSetConverter.withDefaults(Collections.emptyMap());

    public Map<String, Object> convert(Map<String, Object> claims) {
        Map<String, Object> convertedClaims = this.delegate.convert(claims);

        String username = (String) convertedClaims.get("user_name");
        convertedClaims.put("sub", username);

        return convertedClaims;
    }
}

And then, the instance can be supplied like normal:

@Bean
JwtDecoder jwtDecoder() {
    NimbusJwtDecoder jwtDecoder = NimbusJwtDecoder.withJwkSetUri(jwkSetUri).build();
    jwtDecoder.setClaimSetConverter(new UsernameSubClaimAdapter());
    return jwtDecoder;
}

12.3.11 Configuring Timeouts

By default, Resource Server uses connection and socket timeouts of 30 seconds each for coordinating with the authorization server.

This may be too short in some scenarios. Further, it doesn’t take into account more sophisticated patterns like back-off and discovery.

To adjust the way in which Resource Server connects to the authorization server, NimbusJwtDecoder accepts an instance of RestOperations:

@Bean
public JwtDecoder jwtDecoder(RestTemplateBuilder builder) {
    RestOperations rest = builder
            .setConnectionTimeout(60000)
            .setReadTimeout(60000)
            .build();

    NimbusJwtDecoder jwtDecoder = NimbusJwtDecoder.withJwkSetUri(jwkSetUri).restOperations(rest).build();
    return jwtDecoder;
}

12.3.12 Minimal Configuration for Introspection

Typically, an opaque token can be verified via an OAuth 2.0 Introspection Endpoint, hosted by the authorization server. This can be handy when revocation is a requirement.

When using Spring Boot, configuring an application as a resource server that uses introspection consists of two basic steps. First, include the needed dependencies and second, indicate the introspection endpoint details.

Specifying the Authorization Server

To specify where the introspection endpoint is, simply do:

security:
  oauth2:
    resourceserver:
      opaque-token:
        introspection-uri: https://idp.example.com/introspect
        client-id: client
        client-secret: secret

Where https://idp.example.com/introspect is the introspection endpoint hosted by your authorization server and client-id and client-secret are the credentials needed to hit that endpoint.

Resource Server will use these properties to further self-configure and subsequently validate incoming JWTs.

[Note]Note

When using introspection, the authorization server’s word is the law. If the authorization server responses that the token is valid, then it is.

And that’s it!

Startup Expectations

When this property and these dependencies are used, Resource Server will automatically configure itself to validate Opaque Bearer Tokens.

This startup process is quite a bit simpler than for JWTs since no endpoints need to be discovered and no additional validation rules get added.

Runtime Expectations

Once the application is started up, Resource Server will attempt to process any request containing an Authorization: Bearer header:

GET / HTTP/1.1
Authorization: Bearer some-token-value # Resource Server will process this

So long as this scheme is indicated, Resource Server will attempt to process the request according to the Bearer Token specification.

Given an Opaque Token, Resource Server will

  1. Query the provided introspection endpoint using the provided credentials and the token
  2. Inspect the response for an { 'active' : true } attribute
  3. Map each scope to an authority with the prefix SCOPE_

The resulting Authentication#getPrincipal, by default, is a Spring Security OAuth2AuthenticatedPrincipal object, and Authentication#getName maps to the token’s sub property, if one is present.

From here, you may want to jump to:

12.3.13 Looking Up Attributes Post-Authentication

Once a token is authenticated, an instance of BearerTokenAuthentication is set in the SecurityContext.

This means that it’s available in @Controller methods when using @EnableWebMvc in your configuration:

@GetMapping("/foo")
public String foo(BearerTokenAuthentication authentication) {
    return authentication.getTokenAttributes().get("sub") + " is the subject";
}

Since BearerTokenAuthentication holds an OAuth2AuthenticatedPrincipal, that also means that it’s available to controller methods, too:

@GetMapping("/foo")
public String foo(@AuthenticationPrincipal OAuth2AuthenticatedPrincipal principal) {
    return principal.getAttribute("sub") + " is the subject";
}

Looking Up Attributes Via SpEL

Of course, this also means that attributes can be accessed via SpEL.

For example, if using @EnableGlobalMethodSecurity so that you can use @PreAuthorize annotations, you can do:

@PreAuthorize("principal?.attributes['sub'] == 'foo'")
public String forFoosEyesOnly() {
    return "foo";
}

12.3.14 Overriding or Replacing Boot Auto Configuration

There are two @Bean s that Spring Boot generates on Resource Server’s behalf.

The first is a WebSecurityConfigurerAdapter that configures the app as a resource server. When use Opaque Token, this WebSecurityConfigurerAdapter looks like:

protected void configure(HttpSecurity http) {
    http
        .authorizeRequests()
            .anyRequest().authenticated()
            .and()
        .oauth2ResourceServer(OAuth2ResourceServerConfigurer::opaqueToken)
}

If the application doesn’t expose a WebSecurityConfigurerAdapter bean, then Spring Boot will expose the above default one.

Replacing this is as simple as exposing the bean within the application:

@EnableWebSecurity
public class MyCustomSecurityConfiguration extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .mvcMatchers("/messages/**").hasAuthority("SCOPE_message:read")
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .opaqueToken()
                    .introspector(myIntrospector());
    }
}

The above requires the scope of message:read for any URL that starts with /messages/.

Methods on the oauth2ResourceServer DSL will also override or replace auto configuration.

For example, the second @Bean Spring Boot creates is an OpaqueTokenIntrospector, which decodes String tokens into validated instances of OAuth2AuthenticatedPrincipal:

@Bean
public OpaqueTokenIntrospector introspector() {
    return new NimbusOpaqueTokenIntrospector(introspectionUri, clientId, clientSecret);
}

If the application doesn’t expose a OpaqueTokenIntrospector bean, then Spring Boot will expose the above default one.

And its configuration can be overridden using introspectionUri() and introspectionClientCredentials() or replaced using introspector().

Using introspectionUri()

An authorization server’s Introspection Uri can be configured as a configuration property or it can be supplied in the DSL:

@EnableWebSecurity
public class DirectlyConfiguredIntrospectionUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .opaqueToken()
                    .introspectionUri("https://idp.example.com/introspect")
                    .introspectionClientCredentials("client", "secret");
    }
}

Using introspectionUri() takes precedence over any configuration property.

Using introspector()

More powerful than introspectionUri() is introspector(), which will completely replace any Boot auto configuration of OpaqueTokenIntrospector:

@EnableWebSecurity
public class DirectlyConfiguredIntrospector extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .opaqueToken()
                    .introspector(myCustomIntrospector());
    }
}

This is handy when deeper configuration, like authority mapping, JWT revocation, or request timeouts, is necessary.

Exposing a OpaqueTokenIntrospector @Bean

Or, exposing a OpaqueTokenIntrospector @Bean has the same effect as introspector():

@Bean
public OpaqueTokenIntrospector introspector() {
    return new NimbusOpaqueTokenIntrospector(introspectionUri, clientId, clientSecret);
}

12.3.15 Configuring Authorization

An OAuth 2.0 Introspection endpoint will typically return a scope attribute, indicating the scopes (or authorities) it’s been granted, for example:

{ …​, "scope" : "messages contacts"}

When this is the case, Resource Server will attempt to coerce these scopes into a list of granted authorities, prefixing each scope with the string "SCOPE_".

This means that to protect an endpoint or method with a scope derived from an Opaque Token, the corresponding expressions should include this prefix:

@EnableWebSecurity
public class MappedAuthorities extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests(authorizeRequests -> authorizeRequests
                .mvcMatchers("/contacts/**").hasAuthority("SCOPE_contacts")
                .mvcMatchers("/messages/**").hasAuthority("SCOPE_messages")
                .anyRequest().authenticated()
            )
            .oauth2ResourceServer(OAuth2ResourceServerConfigurer::opaqueToken);
    }
}

Or similarly with method security:

@PreAuthorize("hasAuthority('SCOPE_messages')")
public List<Message> getMessages(...) {}

Extracting Authorities Manually

By default, Opaque Token support will extract the scope claim from an introspection response and parse it into individual GrantedAuthority instances.

For example, if the introspection response were:

{
    "active" : true,
    "scope" : "message:read message:write"
}

Then Resource Server would generate an Authentication with two authorities, one for message:read and the other for message:write.

This can, of course, be customized using a custom OpaqueTokenIntrospector that takes a look at the attribute set and converts in its own way:

public class CustomAuthoritiesOpaqueTokenIntrospector implements OpaqueTokenIntrospector {
    private OpaqueTokenIntrospector delegate =
            new NimbusOpaqueTokenIntrospector("https://idp.example.org/introspect", "client", "secret");

    public OAuth2AuthenticatedPrincipal introspect(String token) {
        OAuth2AuthenticatedPrincipal principal = this.delegate.introspect(token);
        return new DefaultOAuth2AuthenticatedPrincipal(
                principal.getName(), principal.getAttributes(), extractAuthorities(principal));
    }

    private Collection<GrantedAuthority> extractAuthorities(OAuth2AuthenticatedPrincipal principal) {
        List<String> scopes = principal.getAttribute(OAuth2IntrospectionClaimNames.SCOPE);
        return scopes.stream()
                .map(SimpleGrantedAuthority::new)
                .collect(Collectors.toList());
    }
}

Thereafter, this custom introspector can be configured simply by exposing it as a @Bean:

@Bean
public OpaqueTokenIntrospector introspector() {
    return new CustomAuthoritiesOpaqueTokenIntrospector();
}

12.3.16 Configuring Timeouts

By default, Resource Server uses connection and socket timeouts of 30 seconds each for coordinating with the authorization server.

This may be too short in some scenarios. Further, it doesn’t take into account more sophisticated patterns like back-off and discovery.

To adjust the way in which Resource Server connects to the authorization server, NimbusOpaqueTokenIntrospector accepts an instance of RestOperations:

@Bean
public OpaqueTokenIntrospector introspector(RestTemplateBuilder builder) {
    RestOperations rest = builder
            .basicAuthentication(clientId, clientSecret)
            .setConnectionTimeout(60000)
            .setReadTimeout(60000)
            .build();

    return new NimbusOpaqueTokenIntrospector(introspectionUri, rest);
}

12.3.17 Using Introspection with JWTs

A common question is whether or not introspection is compatible with JWTs. Spring Security’s Opaque Token support has been designed to not care about the format of the token — it will gladly pass any token to the introspection endpoint provided.

So, let’s say that you’ve got a requirement that requires you to check with the authorization server on each request, in case the JWT has been revoked.

Even though you are using the JWT format for the token, your validation method is introspection, meaning you’d want to do:

spring:
  security:
    oauth2:
      resourceserver:
        opaque-token:
          introspection-uri: https://idp.example.org/introspection
          client-id: client
          client-secret: secret

In this case, the resulting Authentication would be BearerTokenAuthentication. Any attributes in the corresponding OAuth2AuthenticatedPrincipal would be whatever was returned by the introspection endpoint.

But, let’s say that, oddly enough, the introspection endpoint only returns whether or not the token is active. Now what?

In this case, you can create a custom OpaqueTokenIntrospector that still hits the endpoint, but then updates the returned principal to have the JWTs claims as the attributes:

public class JwtOpaqueTokenIntrospector implements OpaqueTokenIntrospector {
    private OpaqueTokenIntrospector delegate =
            new NimbusOpaqueTokenIntrospector("https://idp.example.org/introspect", "client", "secret");
    private JwtDecoder jwtDecoder = new NimbusJwtDecoder(new ParseOnlyJWTProcessor());

    public OAuth2AuthenticatedPrincipal introspect(String token) {
        OAuth2AuthenticatedPrincipal principal = this.delegate.introspect(token);
        try {
            Jwt jwt = this.jwtDecoder.decode(token);
            return new DefaultOAuth2AuthenticatedPrincipal(jwt.getClaims(), NO_AUTHORITIES);
        } catch (JwtException e) {
            throw new OAuth2IntrospectionException(e);
        }
    }

    private static class ParseOnlyJWTProcessor extends DefaultJWTProcessor<SecurityContext> {
        JWTClaimsSet process(SignedJWT jwt, SecurityContext context)
                throws JOSEException {
            return jwt.getJWTClaimSet();
        }
    }
}

Thereafter, this custom introspector can be configured simply by exposing it as a @Bean:

@Bean
public OpaqueTokenIntrospector introspector() {
    return new JwtOpaqueTokenIntropsector();
}

12.3.18 Calling a /userinfo Endpoint

Generally speaking, a Resource Server doesn’t care about the underlying user, but instead about the authorities that have been granted.

That said, at times it can be valuable to tie the authorization statement back to a user.

If an application is also using spring-security-oauth2-client, having set up the appropriate ClientRegistrationRepository, then this is quite simple with a custom OpaqueTokenIntrospector. This implementation below does three things:

  • Delegates to the introspection endpoint, to affirm the token’s validity
  • Looks up the appropriate client registration associated with the /userinfo endpoint
  • Invokes and returns the response from the /userinfo endpoint
public class UserInfoOpaqueTokenIntrospector implements OpaqueTokenIntrospector {
    private final OpaqueTokenIntrospector delegate =
            new NimbusOpaqueTokenIntrospector("https://idp.example.org/introspect", "client", "secret");
    private final OAuth2UserService oauth2UserService = new DefaultOAuth2UserService();

    private final ClientRegistrationRepository repository;

    // ... constructor

    @Override
    public OAuth2AuthenticatedPrincipal introspect(String token) {
        OAuth2AuthenticatedPrincipal authorized = this.delegate.introspect(token);
        Instant issuedAt = authorized.getAttribute(ISSUED_AT);
        Instant expiresAt = authorized.getAttribute(EXPIRES_AT);
        ClientRegistration clientRegistration = this.repository.findByRegistrationId("registration-id");
        OAuth2AccessToken token = new OAuth2AccessToken(BEARER, token, issuedAt, expiresAt);
        OAuth2UserRequest oauth2UserRequest = new OAuth2UserRequest(clientRegistration, token);
        return this.oauth2UserService.loadUser(oauth2UserRequest);
    }
}

If you aren’t using spring-security-oauth2-client, it’s still quite simple. You will simply need to invoke the /userinfo with your own instance of WebClient:

public class UserInfoOpaqueTokenIntrospector implements OpaqueTokenIntrospector {
    private final OpaqueTokenIntrospector delegate =
            new NimbusOpaqueTokenIntrospector("https://idp.example.org/introspect", "client", "secret");
    private final WebClient rest = WebClient.create();

    @Override
    public OAuth2AuthenticatedPrincipal introspect(String token) {
        OAuth2AuthenticatedPrincipal authorized = this.delegate.introspect(token);
        return makeUserInfoRequest(authorized);
    }
}

Either way, having created your OpaqueTokenIntrospector, you should publish it as a @Bean to override the defaults:

@Bean
OpaqueTokenIntrospector introspector() {
    return new UserInfoOpaqueTokenIntrospector(...);
}

12.3.19 Supporting both JWT and Opaque Token

In some cases, you may have a need to access both kinds of tokens. For example, you may support more than one tenant where one tenant issues JWTs and the other issues opaque tokens.

If this decision must be made at request-time, then you can use an AuthenticationManagerResolver to achieve it, like so:

@Bean
AuthenticationManagerResolver<HttpServletRequest> tokenAuthenticationManagerResolver() {
    BearerTokenResolver bearerToken = new DefaultBearerTokenResolver();
    JwtAuthenticationProvider jwt = jwt();
    OpaqueTokenAuthenticationProvider opaqueToken = opaqueToken();

    return request -> {
        String token = bearerToken.resolve(request);
        if (isAJwt(token)) {
            return jwt::authenticate;
        } else {
            return opaqueToken::authenticate;
        }
    }
}

And then specify this AuthenticationManagerResolver in the DSL:

http
    .authorizeRequests()
        .anyRequest().authenticated()
        .and()
    .oauth2ResourceServer()
        .authenticationManagerResolver(this.tokenAuthenticationManagerResolver);

12.3.20 Multi-tenancy

A resource server is considered multi-tenant when there are multiple strategies for verifying a bearer token, keyed by some tenant identifier.

For example, your resource server may accept bearer tokens from two different authorization servers. Or, your authorization server may represent a multiplicity of issuers.

In each case, there are two things that need to be done and trade-offs associated with how you choose to do them:

  1. Resolve the tenant
  2. Propagate the tenant

Resolving the Tenant By Request Material

Resolving the tenant by request material can be done my implementing an AuthenticationManagerResolver, which determines the AuthenticationManager at runtime, like so:

@Component
public class TenantAuthenticationManagerResolver
        implements AuthenticationManagerResolver<HttpServletRequest> {
    private final BearerTokenResolver resolver = new DefaultBearerTokenResolver();
    private final TenantRepository tenants; 1

    private final Map<String, AuthenticationManager> authenticationManagers = new ConcurrentHashMap<>(); 2

    public TenantAuthenticationManagerResolver(TenantRepository tenants) {
        this.tenants = tenants;
    }

    @Override
    public AuthenticationManager resolve(HttpServletRequest request) {
        return this.authenticationManagers.computeIfAbsent(toTenant(request), this::fromTenant);
    }

    private String toTenant(HttpServletRequest request) {
        String[] pathParts = request.getRequestURI().split("/");
        return pathParts.length > 0 ? pathParts[1] : null;
    }

    private AuthenticationManager fromTenant(String tenant) {
        return Optional.ofNullable(this.tenants.get(tenant)) 3
                .map(JwtDecoders::fromIssuerLocation) 4
                .map(JwtAuthenticationProvider::new)
                .orElseThrow(() -> new IllegalArgumentException("unknown tenant"))::authenticate;
    }
}

1

A hypothetical source for tenant information

2

A cache for `AuthenticationManager`s, keyed by tenant identifier

3

Looking up the tenant is more secure than simply computing the issuer location on the fly - the lookup acts as a tenant whitelist

4

Create a JwtDecoder via the discovery endpoint - the lazy lookup here means that you don’t need to configure all tenants at startup

And then specify this AuthenticationManagerResolver in the DSL:

http
    .authorizeRequests()
        .anyRequest().authenticated()
        .and()
    .oauth2ResourceServer()
        .authenticationManagerResolver(this.tenantAuthenticationManagerResolver);

Resolving the Tenant By Claim

Resolving the tenant by claim is similar to doing so by request material. The only real difference is the toTenant method implementation:

@Component
public class TenantAuthenticationManagerResolver implements AuthenticationManagerResolver<HttpServletRequest> {
    private final BearerTokenResolver resolver = new DefaultBearerTokenResolver();
    private final TenantRepository tenants; 1

    private final Map<String, AuthenticationManager> authenticationManagers = new ConcurrentHashMap<>(); 2

    public TenantAuthenticationManagerResolver(TenantRepository tenants) {
        this.tenants = tenants;
    }

    @Override
    public AuthenticationManager resolve(HttpServletRequest request) {
        return this.authenticationManagers.computeIfAbsent(toTenant(request), this::fromTenant); 3
    }

    private String toTenant(HttpServletRequest request) {
        try {
            String token = this.resolver.resolve(request);
            return (String) JWTParser.parse(token).getJWTClaimsSet().getIssuer();
        } catch (Exception e) {
            throw new IllegalArgumentException(e);
        }
    }

    private AuthenticationManager fromTenant(String tenant) {
        return Optional.ofNullable(this.tenants.get(tenant)) 4
                .map(JwtDecoders::fromIssuerLocation) 5
                .map(JwtAuthenticationProvider::new)
                .orElseThrow(() -> new IllegalArgumentException("unknown tenant"))::authenticate;
    }
}

1

A hypothetical source for tenant information

2

A cache for `AuthenticationManager`s, keyed by tenant identifier

3 4

Looking up the tenant is more secure than simply computing the issuer location on the fly - the lookup acts as a tenant whitelist

5

Create a JwtDecoder via the discovery endpoint - the lazy lookup here means that you don’t need to configure all tenants at startup

http
    .authorizeRequests()
        .anyRequest().authenticated()
        .and()
    .oauth2ResourceServer()
        .authenticationManagerResolver(this.tenantAuthenticationManagerResolver);

Parsing the Claim Only Once

You may have observed that this strategy, while simple, comes with the trade-off that the JWT is parsed once by the AuthenticationManagerResolver and then again by the JwtDecoder.

This extra parsing can be alleviated by configuring the JwtDecoder directly with a JWTClaimSetAwareJWSKeySelector from Nimbus:

@Component
public class TenantJWSKeySelector
    implements JWTClaimSetAwareJWSKeySelector<SecurityContext> {

    private final TenantRepository tenants; 1
    private final Map<String, JWSKeySelector<SecurityContext>> selectors = new ConcurrentHashMap<>(); 2

    public TenantJWSKeySelector(TenantRepository tenants) {
        this.tenants = tenants;
    }

    @Override
    public List<? extends Key> selectKeys(JWSHeader jwsHeader, JWTClaimsSet jwtClaimsSet, SecurityContext securityContext)
            throws KeySourceException {
        return this.selectors.computeIfAbsent(toTenant(jwtClaimsSet), this::fromTenant)
                .selectJWSKeys(jwsHeader, securityContext);
    }

    private String toTenant(JWTClaimsSet claimSet) {
        return (String) claimSet.getClaim("iss");
    }

    private JWSKeySelector<SecurityContext> fromTenant(String tenant) {
        return Optional.ofNullable(this.tenantRepository.findById(tenant)) 3
                .map(t -> t.getAttrbute("jwks_uri"))
                .map(this::fromUri)
                .orElseThrow(() -> new IllegalArgumentException("unknown tenant"));
    }

    private JWSKeySelector<SecurityContext> fromUri(String uri) {
        try {
            return JWSAlgorithmFamilyJWSKeySelector.fromJWKSetURL(new URL(uri)); 4
        } catch (Exception e) {
            throw new IllegalArgumentException(e);
        }
    }
}

1

A hypothetical source for tenant information

2

A cache for `JWKKeySelector`s, keyed by tenant identifier

3

Looking up the tenant is more secure than simply calculating the JWK Set endpoint on the fly - the lookup acts as a tenant whitelist

4

Create a JWSKeySelector via the types of keys that come back from the JWK Set endpoint - the lazy lookup here means that you don’t need to configure all tenants at startup

The above key selector is a composition of many key selectors. It chooses which key selector to use based on the iss claim in the JWT.

[Note]Note

To use this approach, make sure that the authorization server is configured to include the claim set as part of the token’s signature. Without this, you have no guarantee that the issuer hasn’t been altered by a bad actor.

Next, we can construct a JWTProcessor:

@Bean
JWTProcessor jwtProcessor(JWTClaimSetJWSKeySelector keySelector) {
    ConfigurableJWTProcessor<SecurityContext> jwtProcessor =
            new DefaultJWTProcessor();
    jwtProcessor.setJWTClaimSetJWSKeySelector(keySelector);
    return jwtProcessor;
}

As you are already seeing, the trade-off for moving tenant-awareness down to this level is more configuration. We have just a bit more.

Next, we still want to make sure you are validating the issuer. But, since the issuer may be different per JWT, then you’ll need a tenant-aware validator, too:

@Component
public class TenantJwtIssuerValidator implements OAuth2TokenValidator<Jwt> {
    private final TenantRepository tenants;
    private final Map<String, JwtIssuerValidator> validators = new ConcurrentHashMap<>();

    public TenantJwtIssuerValidator(TenantRepository tenants) {
        this.tenants = tenants;
    }

    @Override
    public OAuth2TokenValidatorResult validate(Jwt token) {
        return this.validators.computeIfAbsent(toTenant(token), this::fromTenant)
                .validate(token);
    }

    private String toTenant(Jwt jwt) {
        return jwt.getIssuer();
    }

    private JwtIssuerValidator fromTenant(String tenant) {
        return Optional.ofNullable(this.tenants.findById(tenant))
                .map(t -> t.getAttribute("issuer"))
                .map(JwtIssuerValidator::new)
                .orElseThrow(() -> new IllegalArgumentException("unknown tenant"));
    }
}

Now that we have a tenant-aware processor and a tenant-aware validator, we can proceed with creating our JwtDecoder:

@Bean
JwtDecoder jwtDecoder(JWTProcessor jwtProcessor, OAuth2TokenValidator<Jwt> jwtValidator) {
    NimbusJwtDecoder decoder = new NimbusJwtDecoder(processor);
    OAuth2TokenValidator<Jwt> validator = new DelegatingOAuth2TokenValidator<>
            (JwtValidators.createDefault(), this.jwtValidator);
    decoder.setJwtValidator(validator);
    return decoder;
}

We’ve finished talking about resolving the tenant.

If you’ve chosen to resolve the tenant by request material, then you’ll need to make sure you address your downstream resource servers in the same way. For example, if you are resolving it by subdomain, you’ll need to address the downstream resource server using the same subdomain.

However, if you resolve it by a claim in the bearer token, read on to learn about Spring Security’s support for bearer token propagation.

12.3.21 Bearer Token Resolution

By default, Resource Server looks for a bearer token in the Authorization header. This, however, can be customized in a couple of ways.

Reading the Bearer Token from a Custom Header

For example, you may have a need to read the bearer token from a custom header. To achieve this, you can wire a HeaderBearerTokenResolver instance into the DSL, as you can see in the following example:

http
    .oauth2ResourceServer()
        .bearerTokenResolver(new HeaderBearerTokenResolver("x-goog-iap-jwt-assertion"));

Reading the Bearer Token from a Form Parameter

Or, you may wish to read the token from a form parameter, which you can do by configuring the DefaultBearerTokenResolver, as you can see below:

DefaultBearerTokenResolver resolver = new DefaultBearerTokenResolver();
resolver.setAllowFormEncodedBodyParameter(true);
http
    .oauth2ResourceServer()
        .bearerTokenResolver(resolver);

12.3.22 Bearer Token Propagation

Now that you’re in possession of a bearer token, it might be handy to pass that to downstream services. This is quite simple with ServletBearerExchangeFilterFunction, which you can see in the following example:

@Bean
public WebClient rest() {
    return WebClient.builder()
            .filter(new ServletBearerExchangeFilterFunction())
            .build();
}

When the above WebClient is used to perform requests, Spring Security will look up the current Authentication and extract any AbstractOAuth2Token credential. Then, it will propagate that token in the Authorization header.

For example:

this.rest.get()
        .uri("https://other-service.example.com/endpoint")
        .retrieve()
        .bodyToMono(String.class)
        .block()

Will invoke the https://other-service.example.com/endpoint, adding the bearer token Authorization header for you.

In places where you need to override this behavior, it’s a simple matter of supplying the header yourself, like so:

this.rest.get()
        .uri("https://other-service.example.com/endpoint")
        .headers(headers -> headers.setBearerAuth(overridingToken))
        .retrieve()
        .bodyToMono(String.class)
        .block()

In this case, the filter will fall back and simply forward the request onto the rest of the web filter chain.

[Note]Note

Unlike the OAuth 2.0 Client filter function, this filter function makes no attempt to renew the token, should it be expired. To obtain this level of support, please use the OAuth 2.0 Client filter.

RestTemplate support

There is no dedicated support for RestTemplate at the moment, but you can achieve propagation quite simply with your own interceptor:

@Bean
RestTemplate rest() {
    RestTemplate rest = new RestTemplate();
    rest.getInterceptors().add((request, body, execution) -> {
        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
        if (authentication == null) {
            return execution.execute(request, body);
        }

        if (!(authentication.getCredentials() instanceof AbstractOAuth2Token)) {
            return execution.execute(request, body);
        }

        AbstractOAuth2Token token = (AbstractOAuth2Token) authentication.getCredentials();
        request.getHeaders().setBearerAuth(token.getTokenValue());
        return execution.execute(request, body);
    });
    return rest;
}

13. SAML2

13.1 SAML 2.0 Login

The SAML 2.0 Login, saml2Login(), feature provides an application with the capability to have users log in to the application by using their existing account at an SAML 2.0 Identity Provider (Okta, ADFS, etc).

[Note]Note

SAML 2.0 Login is implemented by using the Web Browser SSO Profile, as specified in SAML 2 Profiles. Our implementation is currently limited to a simple authentication scheme.

13.1.1 SAML 2 Support in Spring Security

SAML 2 Service Provider, SP a.k.a. a relying party, support existed as an independent project since 2009. The 1.0.x branch is still in use, including in the Cloud Foundry User Account and Authentication Server that also created a SAML 2.0 Identity Provider implementation based on the SP implementation.

In 2018 we experimented with creating an updated implementation of both a Service Provider and Identity Provider as a standalone library. After careful, and lengthy, deliberation we, the Spring Security team, decided to discontinue that effort. While this effort created a replacement for that standalone 1.0.x library we didn’t feel that we should build a library on top of another library.

Instead we opted to provide framework support for SAML 2 authentication as part of core Spring Security instead.

13.1.2 Saml 2 Login - High Level Concepts

saml2Login() is aimed to support a fraction of the SAML 2 feature set with a focus on authentication being a Service Provider, SP, a relying party, receiving XML assertions from an Identity Provider, aka an asserting party.

A SAML 2 login, or authentication, is the concept that the SP receives and validates an XML message called an assertion from an IDP.

There are currently two supported authentication flows

  1. IDP Initiated flow - example: You login in directly to Okta, and then select a web application to be authenticated for. Okta, the IDP, sends an assertion to the web application, the SP.
  2. SP Initiated flow - example: You access a web application, a SP, the application sends an authentication request to the IDP requesting an assertion. Upon successful authentication on the IDP, the IDP sends an assertion to the SP.

13.1.3 Saml 2 Login - Current Feature Set

  1. Service Provider (SP/Relying Party) is identified by entityId = {baseUrl}/saml2/service-provider-metadata/{registrationId}
  2. Receive assertion embedded in a SAML response via Http-POST or Http-Redirect at {baseUrl}/login/saml2/sso/{registrationId}
  3. Requires the assertion to be signed, unless the response is signed
  4. Supports encrypted assertions
  5. Supports encrypted NameId elements
  6. Allows for extraction of assertion attributes into authorities using a Converter<Assertion, Collection<? extends GrantedAuthority>>
  7. Allows mapping and white listing of authorities using a GrantedAuthoritiesMapper
  8. Public keys in java.security.cert.X509Certificate format.
  9. SP Initiated Authentication via an AuthNRequest

Saml 2 Login - Not Yet Supported

  1. Mappings assertion conditions and attributes to session features (timeout, tracking, etc)
  2. Single logout
  3. Dynamic metadata generation
  4. Receiving and validating standalone assertion (not wrapped in a response object)

13.1.4 Saml 2 Login - Introduction to Java Configuration

To add saml2Login() to a Spring Security filter chain, the minimal Java configuration requires a configuration repository, the RelyingPartyRegistrationRepository, that contains the SAML configuration and the invocation of the HttpSecurity.saml2Login() method:

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Bean
    public RelyingPartyRegistrationRepository relyingPartyRegistrationRepository() {
        //SAML configuration
        //Mapping this application to one or more Identity Providers
        return new InMemoryRelyingPartyRegistrationRepository(...);
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .saml2Login()
        ;
    }
}

The bean declaration is a convenient, but optional, approach. You can directly wire up the repository using a method call

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .saml2Login()
                .relyingPartyRegistrationRepository(...)
        ;
    }
}

RelyingPartyRegistration

The RelyingPartyRegistration object represents the mapping between this application, the SP, and the asserting party, the IDP.

URI Patterns

URI patterns are frequenty used to automatically generate URIs based on an incoming request. The URI patterns in saml2Login can contain the following variables

  • baseUrl
  • registrationId
  • baseScheme
  • baseHost
  • basePort

For example:

{baseUrl}/login/saml2/sso/{registrationId}
Relying Party
  • registrationId - (required) a unique identifer for this configuration mapping. This identifier may be used in URI paths, so care should be taken that no URI encoding is required.
  • localEntityIdTemplate - (optional) A URI pattern that creates an entity ID for this application based on the incoming request. The default is {baseUrl}/saml2/service-provider-metadata/{registrationId} and for a small sample application it would look like
http://localhost:8080/saml2/service-provider-metadata/my-test-configuration

There is no requirement that this configuration option is a pattern, it can be a fixed URI value.

  • remoteIdpEntityId - (required) the entity ID of the Identity Provider. Always a fixed URI value or string, no patterns allowed.
  • assertionConsumerServiceUrlTemplate - (optional) A URI pattern that denotes the assertion consumer service URI to be sent with any AuthNRequest from the SP to the IDP during the SP initiated flow. While this can be a pattern the actual URI must resolve to the ACS endpoint on the SP. The default value is {baseUrl}/login/saml2/sso/{registrationId} and maps directly to the Saml2WebSsoAuthenticationFilter endpoint
  • idpWebSsoUrl - (required) a fixed URI value for the IDP Single Sign On endpoint where the SP sends the AuthNRequest messages.
  • credentials - A list of credentials, private keys and x509 certificates, used for message signing, verification, encryption and decryption. This list can contain redundant credentials to allow for easy rotation of credentials. For example

    • [0] - X509Certificate{VERIFICATION,ENCRYPTION} - The IDP’s first public key used for verification and encryption.
    • [1] - X509Certificate/{VERIFICATION,ENCRYPTION} - The IDP’s second verification key used for verification. Encryption is always done using the first ENCRYPTION key in the list.
    • [2] - PrivateKey/X509Certificate{SIGNING,DECRYPTION} - The SP’s first signing and decryption credential.
    • [3] - PrivateKey/X509Certificate{SIGNING,DECRYPTION} - The SP’s second decryption credential. Signing is always done using the first SIGNING key in the list.

When an incoming message is received, signatures are always required, the system will first attempt to validate the signature using the certificate at index [0] and only move to the second credential if the first one fails.

In a similar fashion, the SP configured private keys are used for decryption and attempted in the same order. The first SP credential (type=SIGNING) will be used when messages to the IDP are signed.

Duplicated Relying Party Configurations

In the use case where an application uses multiple identity providers it becomes obvious that some configuration is duplicated between two RelyingPartyRegistration objects

  • localEntityIdTemplate
  • credentials (all SP credentials, IDP credentials change)
  • assertionConsumerServiceUrlTemplate

While there is some drawback in duplicating configuration values the back end configuration repository does not need to replicate this data storage model.

There is a benefit that comes with this setup. Credentials may be more easily rotated for some identity providers vs others. This object model can ensure that there is no disruption when configuration is changed in a multi IDP use case and you’re not able to rotate credentials on all the identity providers.

Service Provider Metadata

The Spring Security SAML 2 implementation does not yet provide an endpoint for downloading SP metadata in XML format. The minimal pieces that are exchanged

  • entity ID - defaults to {baseUrl}/saml2/service-provider-metadata/{registrationId} Other known configuration names that also use this same value

    • Audience Restriction
  • single signon URL - defaults to {baseUrl}/login/saml2/sso/{registrationId} Other known configuration names that also use this same value

    • Recipient URL
    • Destination URL
    • Assertion Consumer Service URL
  • X509Certificate - the certificate that you configure as part of your {SIGNING,DECRYPTION} credentials must be shared with the Identity Provider

Authentication Requests - SP Initiated Flow

To initiate an authentication from the web application, a simple redirect to

{baseUrl}/saml2/authenticate/{registrationId}

The endpoint will generate an AuthNRequest by invoking the createAuthenticationRequest method on a configurable factory. Just expose the Saml2AuthenticationRequestFactory as a bean in your configuration.

public interface Saml2AuthenticationRequestFactory {
    String createAuthenticationRequest(Saml2AuthenticationRequest request);
}

13.1.5 Spring Boot 2.x Sample

We are currently working with the the Spring Boot team on the Auto Configuration for Spring Security SAML Login. In the meantime, we have provided a Spring Boot sample that supports a Yaml configuration.

To run the sample, follow these three steps

  1. Launch the Spring Boot application

    • ./gradlew :spring-security-samples-boot-saml2login:bootRun
  2. Open a browser

  3. This will take you to an identity provider, log in using:

    • User: user
    • Password: password

Multiple Identity Provider Sample

It’s very simple to use multiple providers, but there are some defaults that may trip you up if you don’t pay attention. In our SAML configuration of RelyingPartyRegistration objects, we default an SP entity ID to

{baseUrl}/saml2/service-provider-metadata/{registrationId}

That means in our two provider configuration, our system would look like

registration-1 (Identity Provider 1) - Our local SP Entity ID is:
http://localhost:8080/saml2/service-provider-metadata/registration-1

registration-2 (Identity Provider 2) - Our local SP Entity ID is:
http://localhost:8080/saml2/service-provider-metadata/registration-2

In this configuration, illustrated in the sample below, to the outside world, we have actually created two virtual Service Provider identities hosted within the same application.

spring:
  security:
    saml2:
      login:
        relying-parties:
          - entity-id: &idp-entity-id https://simplesaml-for-spring-saml.cfapps.io/saml2/idp/metadata.php
            registration-id: simplesamlphp
            web-sso-url: &idp-sso-url https://simplesaml-for-spring-saml.cfapps.io/saml2/idp/SSOService.php
            signing-credentials: &service-provider-credentials
              - private-key: |
                  -----BEGIN PRIVATE KEY-----
                  MIICeAIBADANBgkqhkiG9w0BAQEFAASCAmIwggJeAgEAAoGBANG7v8QjQGU3MwQE
                  ...................SHORTENED FOR READ ABILITY...................
                  INrtuLp4YHbgk1mi
                  -----END PRIVATE KEY-----
                certificate: |
                  -----BEGIN CERTIFICATE-----
                  MIICgTCCAeoCCQCuVzyqFgMSyDANBgkqhkiG9w0BAQsFADCBhDELMAkGA1UEBhMC
                  ...................SHORTENED FOR READ ABILITY...................
                  RZ/nbTJ7VTeZOSyRoVn5XHhpuJ0B
                  -----END CERTIFICATE-----
            verification-credentials: &idp-certificates
              - |
                -----BEGIN CERTIFICATE-----
                MIIEEzCCAvugAwIBAgIJAIc1qzLrv+5nMA0GCSqGSIb3DQEBCwUAMIGfMQswCQYD
                ...................SHORTENED FOR READ ABILITY...................
                lx13Y1YlQ4/tlpgTgfIJxKV6nyPiLoK0nywbMd+vpAirDt2Oc+hk
                -----END CERTIFICATE-----
          - entity-id: *idp-entity-id
            registration-id: simplesamlphp2
            web-sso-url: *idp-sso-url
            signing-credentials: *service-provider-credentials
            verification-credentials: *idp-certificates

If this is not desirable, you can manually override the local SP entity ID by using the

localEntityIdTemplate = {baseUrl}/saml2/service-provider-metadata

If we change our local SP entity ID to this value, it is still important that we give out the correct single sign on URL (the assertion consumer service URL) for each registered identity provider based on the registration Id. {baseUrl}/login/saml2/sso/{registrationId}

14. Protection Against Exploits

14.1 Cross Site Request Forgery (CSRF) for Servlet Environments

This section discusses Spring Security’s Cross Site Request Forgery (CSRF) support for servlet environments.

14.1.1 Using Spring Security CSRF Protection

The steps to using Spring Security’s CSRF protection are outlined below:

Use proper HTTP verbs

The first step to protecting against CSRF attacks is to ensure your website uses proper HTTP verbs. This is covered in detail in Safe Methods Must be Idempotent.

Configure CSRF Protection

The next step is to configure Spring Security’s CSRF protection within your application. Spring Security’s CSRF protection is enabled by default, but you may need to customize the configuration. Below are a few common customizations.

Custom CsrfTokenRepository

By default Spring Security stores the expected CSRF token in the HttpSession using HttpSessionCsrfTokenRepository. There can be cases where users will want to configure a custom CsrfTokenRepository. For example, it might be desirable to persist the CsrfToken in a cookie to support a JavaScript based application.

By default the CookieCsrfTokenRepository will write to a cookie named XSRF-TOKEN and read it from a header named X-XSRF-TOKEN or the HTTP parameter _csrf. These defaults come from AngularJS

You can configure CookieCsrfTokenRepository in XML using the following:

Example 14.1. Store CSRF Token in a Cookie with XML Configuration

<http>
    <!-- ... -->
    <csrf token-repository-ref="tokenRepository"/>
</http>
<b:bean id="tokenRepository"
    class="org.springframework.security.web.csrf.CookieCsrfTokenRepository"
    p:cookieHttpOnly="false"/>

[Note]Note

The sample explicitly sets cookieHttpOnly=false. This is necessary to allow JavaScript (i.e. AngularJS) to read it. If you do not need the ability to read the cookie with JavaScript directly, it is recommended to omit cookieHttpOnly=false to improve security.

You can configure CookieCsrfTokenRepository in Java Configuration using:

Example 14.2. Store CSRF Token in a Cookie with Java Configuration

@EnableWebSecurity
public class WebSecurityConfig extends
        WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) {
        http
            .csrf(csrf ->
                csrf
                    .csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse())
            );
    }
}

[Note]Note

The sample explicitly sets cookieHttpOnly=false. This is necessary to allow JavaScript (i.e. AngularJS) to read it. If you do not need the ability to read the cookie with JavaScript directly, it is recommended to omit cookieHttpOnly=false (by using new CookieCsrfTokenRepository() instead) to improve security.

Disable CSRF Protection

CSRF protection is enabled by default. However, it is simple to disable CSRF protection if it makes sense for your application.

The XML configuration below will disable CSRF protection.

Example 14.3. Disable CSRF XML Configuration

<http>
    <!-- ... -->
    <csrf disabled="true"/>
</http>

The Java configuration below will disable CSRF protection.

Example 14.4. Disable CSRF Java Configuration

@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends
        WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) {
        http
            .csrf(csrf ->
                csrf.disable()
            );
    }
}

Include the CSRF Token

In order for the synchronizer token pattern to protect against CSRF attacks, we must include the actual CSRF token in the HTTP request. This must be included in a part of the request (i.e. form parameter, HTTP header, etc) that is not automatically included in the HTTP request by the browser.

Spring Security’s CsrfFilter exposes a CsrfToken as an HttpServletRequest attribute named _csrf. This means that any view technology can access the CsrfToken to expose the expected token as either a form or meta tag. Fortunately, there are integrations listed below that make including the token in form and ajax requests even easier.

Form URL Encoded

In order to post an HTML form the CSRF token must be included in the form as a hidden input. For example, the rendered HTML might look like:

Example 14.5. CSRF Token HTML

<input type="hidden"
    name="_csrf"
    value="4bfd1575-3ad1-4d21-96c7-4ef2d9f86721"/>

Next we will discuss various ways of including the CSRF token in a form as a hidden input.

Automatic CSRF Token Inclusion

Spring Security’s CSRF support provides integration with Spring’s RequestDataValueProcessor via its CsrfRequestDataValueProcessor. This means that if you leverage Spring’s form tag library, Thymleaf, or any other view technology that integrates with RequestDataValueProcessor, then forms that have an unsafe HTTP method (i.e. post) will automatically include the actual CSRF token.

csrfInput Tag

If you are using JSPs, then you can use Spring’s form tag library. However, if that is not an option, you can also easily include the token with the csrfInput tag.

CsrfToken Request Attribute

If the other options for including the actual CSRF token in the request do not work, you can take advantage of the fact that the CsrfToken is exposed as an HttpServletRequest attribute named _csrf.

An example of doing this with a JSP is shown below:

Example 14.6. CSRF Token in Form with Request Attribute

<c:url var="logoutUrl" value="/logout"/>
<form action="${logoutUrl}"
    method="post">
<input type="submit"
    value="Log out" />
<input type="hidden"
    name="${_csrf.parameterName}"
    value="${_csrf.token}"/>
</form>

Ajax and JSON Requests

If you are using JSON, then it is not possible to submit the CSRF token within an HTTP parameter. Instead you can submit the token within a HTTP header.

In the following sections we will discuss various ways of including the CSRF token as an HTTP request header in JavaScript based applications.

Automatic Inclusion

Spring Security can easily be configured to store the expected CSRF token in a cookie. By storing the expected CSRF in a cookie, JavaScript frameworks like AngularJS will automatically include the actual CSRF token in the HTTP request headers.

Meta tags

An alternative pattern to exposing the CSRF in a cookie is to include the CSRF token within your meta tags. The HTML might look something like this:

Example 14.7. CSRF meta tag HTML

<html>
<head>
    <meta name="_csrf" content="4bfd1575-3ad1-4d21-96c7-4ef2d9f86721"/>
    <meta name="_csrf_header" content="X-CSRF-TOKEN"/>
    <!-- ... -->
</head>
<!-- ... -->

Once the meta tags contained the CSRF token, the JavaScript code would read the meta tags and include the CSRF token as a header. If you were using jQuery, this could be done with the following:

Example 14.8. AJAX send CSRF Token

$(function () {
    var token = $("meta[name='_csrf']").attr("content");
    var header = $("meta[name='_csrf_header']").attr("content");
    $(document).ajaxSend(function(e, xhr, options) {
        xhr.setRequestHeader(header, token);
    });
});

csrfMeta tag

If you are using JSPs a simple way to write the CSRF token to the meta tags is by leveraging the csrfMeta tag.

CsrfToken Request Attribute

If the other options for including the actual CSRF token in the request do not work, you can take advantage of the fact that the CsrfToken is exposed as an HttpServletRequest attribute named _csrf. An example of doing this with a JSP is shown below:

Example 14.9. CSRF meta tag JSP

<html>
<head>
    <meta name="_csrf" content="${_csrf.token}"/>
    <!-- default header name is X-CSRF-TOKEN -->
    <meta name="_csrf_header" content="${_csrf.headerName}"/>
    <!-- ... -->
</head>
<!-- ... -->

14.1.2 CSRF Considerations

There are a few special considerations to consider when implementing protection against CSRF attacks. This section discusses those considerations as it pertains to servlet environments. Refer to the section called “CSRF Considerations” for a more general discussion.

Logging In

It is important to require CSRF for log in requests to protect against forging log in attempts. Spring Security’s servlet support does this out of the box.

Logging Out

It is important to require CSRF for log out requests to protect against forging log out attempts. If CSRF protection is enabled (default), Spring Security’s LogoutFilter to only process HTTP POST. This ensures that log out requires a CSRF token and that a malicious user cannot forcibly log out your users.

The easiest approach is to use a form to log out. If you really want a link, you can use JavaScript to have the link perform a POST (i.e. maybe on a hidden form). For browsers with JavaScript that is disabled, you can optionally have the link take the user to a log out confirmation page that will perform the POST.

If you really want to use HTTP GET with logout you can do so, but remember this is generally not recommended. For example, the following Java Configuration will perform logout with the URL /logout is requested with any HTTP method:

Example 14.10. Log out with HTTP GET

@EnableWebSecurity
public class WebSecurityConfig extends
        WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) {
        http
            .logout(logout ->
                logout
                    .logoutRequestMatcher(new AntPathRequestMatcher("/logout"))
            );
    }
}

CSRF and Session Timeouts

By default Spring Security stores the CSRF token in the HttpSession. This can lead to a situation where the session expires which means there is not an expected CSRF token to validate against.

We’ve already discussed general solutions to session timeouts. This section discusses the specifics of CSRF timeouts as it pertains to the servlet support.

It is simple to change storage of the expected CSRF token to be in a cookie. For details, refer to the the section called “Custom CsrfTokenRepository” section.

If a token does expire, you might want to customize how it is handled by specifying a custom AccessDeniedHandler. The custom AccessDeniedHandler can process the InvalidCsrfTokenException any way you like. For an example of how to customize the AccessDeniedHandler refer to the provided links for both xml and Java configuration.

Multipart (file upload)

We have already discussed how protecting multipart requests (file uploads) from CSRF attacks causes a chicken and the egg problem. This section discusses how to implement placing the CSRF token in the body and url within a servlet application.

[Note]Note

More information about using multipart forms with Spring can be found within the 1.1.11. Multipart Resolver section of the Spring reference and the MultipartFilter javadoc.

Place CSRF Token in the Body

We have already discussed the tradeoffs of placing the CSRF token in the body. In this section we will discuss how to configure Spring Security to read the CSRF from the body.

In order to read the CSRF token from the body, the MultipartFilter is specified before the Spring Security filter. Specifying the MultipartFilter before the Spring Security filter means that there is no authorization for invoking the MultipartFilter which means anyone can place temporary files on your server. However, only authorized users will be able to submit a File that is processed by your application. In general, this is the recommended approach because the temporary file upload should have a negligible impact on most servers.

To ensure MultipartFilter is specified before the Spring Security filter with java configuration, users can override beforeSpringSecurityFilterChain as shown below:

Example 14.11. Initializer MultipartFilter

public class SecurityApplicationInitializer extends AbstractSecurityWebApplicationInitializer {

    @Override
    protected void beforeSpringSecurityFilterChain(ServletContext servletContext) {
        insertFilters(servletContext, new MultipartFilter());
    }
}

To ensure MultipartFilter is specified before the Spring Security filter with XML configuration, users can ensure the <filter-mapping> element of the MultipartFilter is placed before the springSecurityFilterChain within the web.xml as shown below:

Example 14.12. web.xml - MultipartFilter

<filter>
    <filter-name>MultipartFilter</filter-name>
    <filter-class>org.springframework.web.multipart.support.MultipartFilter</filter-class>
</filter>
<filter>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
    <filter-name>MultipartFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>springSecurityFilterChain</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Include CSRF Token in URL

If allowing unauthorized users to upload temporary files is not acceptable, an alternative is to place the MultipartFilter after the Spring Security filter and include the CSRF as a query parameter in the action attribute of the form. Since the CsrfToken is exposed as an HttpServletRequest request attribute, we can use that to create an action with the CSRF token in it. An example with a jsp is shown below

Example 14.13. CSRF Token in Action

<form method="post"
    action="./upload?${_csrf.parameterName}=${_csrf.token}"
    enctype="multipart/form-data">

HiddenHttpMethodFilter

We have already discussed the trade-offs of placing the CSRF token in the body.

In Spring’s Servlet support, overriding the HTTP method is done using HiddenHttpMethodFilter. More information can be found in HTTP Method Conversion section of the reference documentation.

14.2 Security HTTP Response Headers

This section discusses Spring Security’s support for adding various security headers to the response.

14.2.1 Default Security Headers

Spring Security allows users to easily inject the default security headers to assist in protecting their application. The default for Spring Security is to include the following headers:

Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Content-Type-Options: nosniff
Strict-Transport-Security: max-age=31536000 ; includeSubDomains
X-Frame-Options: DENY
X-XSS-Protection: 1; mode=block
[Note]Note

Strict-Transport-Security is only added on HTTPS requests

For additional details on each of these headers, refer to the corresponding sections:

While each of these headers are considered best practice, it should be noted that not all clients utilize the headers, so additional testing is encouraged.

You can customize specific headers. For example, assume that want your HTTP response headers to look like the following:

Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block

Specifically, you want all of the default headers with the following customizations:

You can easily do this with the following Java Configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
        WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .frameOptions(frameOptions ->
                        frameOptions.sameOrigin()
                    )
                    .httpStrictTransportSecurity(hsts ->
                        hsts.disable()
                    )
            );
    }
}

Alternatively, if you are using Spring Security XML Configuration, you can use the following:

<http>
    <!-- ... -->

    <headers>
        <frame-options policy="SAMEORIGIN" />
        <hsts disable="true"/>
    </headers>
</http>

If you do not want the defaults to be added and want explicit control over what should be used, you can disable the defaults. An example for both Java and XML based configuration is provided below:

If you are using Spring Security’s Java Configuration the following will only add Cache Control.

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    // do not use any default headers unless explicitly listed
                    .defaultsDisabled()
                    .cacheControl(withDefaults())
            );
    }
}

The following XML will only add Cache Control.

<http>
    <!-- ... -->

    <headers defaults-disabled="true">
        <cache-control/>
    </headers>
</http>

If necessary, you can disable all of the HTTP Security response headers with the following Java Configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers.disable()
            );
    }
}

If necessary, you can disable all of the HTTP Security response headers with the following XML configuration below:

<http>
    <!-- ... -->

    <headers disabled="true" />
</http>

14.2.2 Cache Control

In the past Spring Security required you to provide your own cache control for your web application. This seemed reasonable at the time, but browser caches have evolved to include caches for secure connections as well. This means that a user may view an authenticated page, log out, and then a malicious user can use the browser history to view the cached page. To help mitigate this Spring Security has added cache control support which will insert the following headers into you response.

Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0

Simply adding the <headers> element with no child elements will automatically add Cache Control and quite a few other protections. However, if you only want cache control, you can enable this feature using Spring Security’s XML namespace with the <cache-control> element and the [email protected] attribute.

<http>
    <!-- ... -->

    <headers defaults-disable="true">
        <cache-control />
    </headers>
</http>

Similarly, you can enable only cache control within Java Configuration with the following:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .defaultsDisabled()
                    .cacheControl(withDefaults())
            );
    }
}

If you actually want to cache specific responses, your application can selectively invoke HttpServletResponse.setHeader(String,String) to override the header set by Spring Security. This is useful to ensure things like CSS, JavaScript, and images are properly cached.

When using Spring Web MVC, this is typically done within your configuration. For example, the following configuration will ensure that the cache headers are set for all of your resources:

@EnableWebMvc
public class WebMvcConfiguration implements WebMvcConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry
            .addResourceHandler("/resources/**")
            .addResourceLocations("/resources/")
            .setCachePeriod(31556926);
    }

    // ...
}

14.2.3 Content Type Options

Historically browsers, including Internet Explorer, would try to guess the content type of a request using content sniffing. This allowed browsers to improve the user experience by guessing the content type on resources that had not specified the content type. For example, if a browser encountered a JavaScript file that did not have the content type specified, it would be able to guess the content type and then execute it.

[Note]Note

=== There are many additional things one should do (i.e. only display the document in a distinct domain, ensure Content-Type header is set, sanitize the document, etc) when allowing content to be uploaded. However, these measures are out of the scope of what Spring Security provides. It is also important to point out when disabling content sniffing, you must specify the content type in order for things to work properly. ===

The problem with content sniffing is that this allowed malicious users to use polyglots (i.e. a file that is valid as multiple content types) to execute XSS attacks. For example, some sites may allow users to submit a valid postscript document to a website and view it. A malicious user might create a postscript document that is also a valid JavaScript file and execute a XSS attack with it.

Content sniffing can be disabled by adding the following header to our response:

X-Content-Type-Options: nosniff

Just as with the cache control element, the nosniff directive is added by default when using the <headers> element with no child elements. However, if you want more control over which headers are added you can use the <content-type-options> element and the [email protected] attribute as shown below:

<http>
    <!-- ... -->

    <headers defaults-disabled="true">
        <content-type-options />
    </headers>
</http>

The X-Content-Type-Options header is added by default with Spring Security Java configuration. If you want more control over the headers, you can explicitly specify the content type options with the following:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .defaultsDisabled()
                    .contentTypeOptions(withDefaults())
            );
    }
}

14.2.4 HTTP Strict Transport Security (HSTS)

When you type in your bank’s website, do you enter mybank.example.com or do you enter https://mybank.example.com? If you omit the https protocol, you are potentially vulnerable to Man in the Middle attacks. Even if the website performs a redirect to https://mybank.example.com a malicious user could intercept the initial HTTP request and manipulate the response (i.e. redirect to https://mibank.example.com and steal their credentials).

Many users omit the https protocol and this is why HTTP Strict Transport Security (HSTS) was created. Once mybank.example.com is added as a HSTS host, a browser can know ahead of time that any request to mybank.example.com should be interpreted as https://mybank.example.com. This greatly reduces the possibility of a Man in the Middle attack occurring.

[Note]Note

=== In accordance with RFC6797, the HSTS header is only injected into HTTPS responses. In order for the browser to acknowledge the header, the browser must first trust the CA that signed the SSL certificate used to make the connection (not just the SSL certificate). ===

One way for a site to be marked as a HSTS host is to have the host preloaded into the browser. Another is to add the "Strict-Transport-Security" header to the response. For example the following would instruct the browser to treat the domain as an HSTS host for a year (there are approximately 31536000 seconds in a year):

Strict-Transport-Security: max-age=31536000 ; includeSubDomains ; preload

The optional includeSubDomains directive instructs Spring Security that subdomains (i.e. secure.mybank.example.com) should also be treated as an HSTS domain.

The optional preload directive instructs Spring Security that domain should be preloaded in browser as HSTS domain. For more details on HSTS preload please see https://hstspreload.org.

As with the other headers, Spring Security adds HSTS by default. You can customize HSTS headers with the <hsts> element as shown below:

<http>
    <!-- ... -->

    <headers>
        <hsts
            include-subdomains="true"
            max-age-seconds="31536000" preload="true" />
    </headers>
</http>

Similarly, you can enable only HSTS headers with Java Configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .httpStrictTransportSecurity(hsts ->
                        hsts
                            .includeSubDomains(true)
                            .preload(true)
                            .maxAgeInSeconds(31536000)
                    )
            );
    }
}

14.2.5 HTTP Public Key Pinning (HPKP)

HTTP Public Key Pinning (HPKP) is a security feature that tells a web client to associate a specific cryptographic public key with a certain web server to prevent Man in the Middle (MITM) attacks with forged certificates.

To ensure the authenticity of a server’s public key used in TLS sessions, this public key is wrapped into a X.509 certificate which is usually signed by a certificate authority (CA). Web clients such as browsers trust a lot of these CAs, which can all create certificates for arbitrary domain names. If an attacker is able to compromise a single CA, they can perform MITM attacks on various TLS connections. HPKP can circumvent this threat for the HTTPS protocol by telling the client which public key belongs to a certain web server. HPKP is a Trust on First Use (TOFU) technique. The first time a web server tells a client via a special HTTP header which public keys belong to it, the client stores this information for a given period of time. When the client visits the server again, it expects a certificate containing a public key whose fingerprint is already known via HPKP. If the server delivers an unknown public key, the client should present a warning to the user.

[Note]Note

=== Because the user-agent needs to validate the pins against the SSL certificate chain, the HPKP header is only injected into HTTPS responses. ===

Enabling this feature for your site is as simple as returning the Public-Key-Pins HTTP header when your site is accessed over HTTPS. For example, the following would instruct the user-agent to only report pin validation failures to a given URI (via the report-uri directive) for 2 pins:

Public-Key-Pins-Report-Only: max-age=5184000 ; pin-sha256="d6qzRu9zOECb90Uez27xWltNsj0e1Md7GkYYkVoZWmM=" ; pin-sha256="E9CZ9INDbd+2eRQozYqqbQ2yXLVKB9+xcprMF+44U1g=" ; report-uri="https://example.net/pkp-report" ; includeSubDomains

A pin validation failure report is a standard JSON structure that can be captured either by the web application’s own API or by a publicly hosted HPKP reporting service, such as, REPORT-URI.

The optional includeSubDomains directive instructs the browser to also validate subdomains with the given pins.

Opposed to the other headers, Spring Security does not add HPKP by default. You can customize HPKP headers with the <hpkp> element as shown below:

<http>
    <!-- ... -->

    <headers>
        <hpkp
            include-subdomains="true"
            report-uri="https://example.net/pkp-report">
            <pins>
                    <pin algorithm="sha256">d6qzRu9zOECb90Uez27xWltNsj0e1Md7GkYYkVoZWmM=</pin>
                    <pin algorithm="sha256">E9CZ9INDbd+2eRQozYqqbQ2yXLVKB9+xcprMF+44U1g=</pin>
            </pins>
        </hpkp>
    </headers>
</http>

Similarly, you can enable HPKP headers with Java Configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .httpPublicKeyPinning(hpkp ->
                        hpkp
                            .includeSubDomains(true)
                            .reportUri("https://example.net/pkp-report")
                            .addSha256Pins("d6qzRu9zOECb90Uez27xWltNsj0e1Md7GkYYkVoZWmM=", "E9CZ9INDbd+2eRQozYqqbQ2yXLVKB9+xcprMF+44U1g=")
                    )
            );
    }
}

14.2.6 X-Frame-Options

Allowing your website to be added to a frame can be a security issue. For example, using clever CSS styling users could be tricked into clicking on something that they were not intending (video demo). For example, a user that is logged into their bank might click a button that grants access to other users. This sort of attack is known as Clickjacking.

[Note]Note

=== Another modern approach to dealing with clickjacking is to use Section 14.2.8, “Content Security Policy (CSP)”. ===

There are a number ways to mitigate clickjacking attacks. For example, to protect legacy browsers from clickjacking attacks you can use frame breaking code. While not perfect, the frame breaking code is the best you can do for the legacy browsers.

A more modern approach to address clickjacking is to use X-Frame-Options header:

X-Frame-Options: DENY

The X-Frame-Options response header instructs the browser to prevent any site with this header in the response from being rendered within a frame. By default, Spring Security disables rendering within an iframe.

You can customize X-Frame-Options with the frame-options element. For example, the following will instruct Spring Security to use "X-Frame-Options: SAMEORIGIN" which allows iframes within the same domain:

<http>
    <!-- ... -->

    <headers>
        <frame-options
        policy="SAMEORIGIN" />
    </headers>
</http>

Similarly, you can customize frame options to use the same origin within Java Configuration using the following:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .frameOptions(frameOptions ->
                        frameOptions
                            .sameOrigin()
                    )
            );
    }
}

14.2.7 X-XSS-Protection

Some browsers have built in support for filtering out reflected XSS attacks. This is by no means foolproof, but does assist in XSS protection.

The filtering is typically enabled by default, so adding the header typically just ensures it is enabled and instructs the browser what to do when a XSS attack is detected. For example, the filter might try to change the content in the least invasive way to still render everything. At times, this type of replacement can become a XSS vulnerability in itself. Instead, it is best to block the content rather than attempt to fix it. To do this we can add the following header:

X-XSS-Protection: 1; mode=block

This header is included by default. However, we can customize it if we wanted. For example:

<http>
    <!-- ... -->

    <headers>
        <xss-protection block="false"/>
    </headers>
</http>

Similarly, you can customize XSS protection within Java Configuration with the following:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .xssProtection(xssProtection ->
                        xssProtection
                            .block(false)
                    )
            );
    }
}

14.2.8 Content Security Policy (CSP)

Content Security Policy (CSP) is a mechanism that web applications can leverage to mitigate content injection vulnerabilities, such as cross-site scripting (XSS). CSP is a declarative policy that provides a facility for web application authors to declare and ultimately inform the client (user-agent) about the sources from which the web application expects to load resources.

[Note]Note

=== Content Security Policy is not intended to solve all content injection vulnerabilities. Instead, CSP can be leveraged to help reduce the harm caused by content injection attacks. As a first line of defense, web application authors should validate their input and encode their output. ===

A web application may employ the use of CSP by including one of the following HTTP headers in the response:

  • Content-Security-Policy
  • Content-Security-Policy-Report-Only

Each of these headers are used as a mechanism to deliver a security policy to the client. A security policy contains a set of security policy directives (for example, script-src and object-src), each responsible for declaring the restrictions for a particular resource representation.

For example, a web application can declare that it expects to load scripts from specific, trusted sources, by including the following header in the response:

Content-Security-Policy: script-src https://trustedscripts.example.com

An attempt to load a script from another source other than what is declared in the script-src directive will be blocked by the user-agent. Additionally, if the report-uri directive is declared in the security policy, then the violation will be reported by the user-agent to the declared URL.

For example, if a web application violates the declared security policy, the following response header will instruct the user-agent to send violation reports to the URL specified in the policy’s report-uri directive.

Content-Security-Policy: script-src https://trustedscripts.example.com; report-uri /csp-report-endpoint/

Violation reports are standard JSON structures that can be captured either by the web application’s own API or by a publicly hosted CSP violation reporting service, such as, REPORT-URI.

The Content-Security-Policy-Report-Only header provides the capability for web application authors and administrators to monitor security policies, rather than enforce them. This header is typically used when experimenting and/or developing security policies for a site. When a policy is deemed effective, it can be enforced by using the Content-Security-Policy header field instead.

Given the following response header, the policy declares that scripts may be loaded from one of two possible sources.

Content-Security-Policy-Report-Only: script-src 'self' https://trustedscripts.example.com; report-uri /csp-report-endpoint/

If the site violates this policy, by attempting to load a script from evil.com, the user-agent will send a violation report to the declared URL specified by the report-uri directive, but still allow the violating resource to load nevertheless.

Configuring Content Security Policy

It’s important to note that Spring Security does not add Content Security Policy by default. The web application author must declare the security policy(s) to enforce and/or monitor for the protected resources.

For example, given the following security policy:

script-src 'self' https://trustedscripts.example.com; object-src https://trustedplugins.example.com; report-uri /csp-report-endpoint/

You can enable the CSP header using XML configuration with the <content-security-policy> element as shown below:

<http>
    <!-- ... -->

    <headers>
        <content-security-policy
            policy-directives="script-src 'self' https://trustedscripts.example.com; object-src https://trustedplugins.example.com; report-uri /csp-report-endpoint/" />
    </headers>
</http>

To enable the CSP 'report-only' header, configure the element as follows:

<http>
    <!-- ... -->

    <headers>
        <content-security-policy
            policy-directives="script-src 'self' https://trustedscripts.example.com; object-src https://trustedplugins.example.com; report-uri /csp-report-endpoint/"
            report-only="true" />
    </headers>
</http>

Similarly, you can enable the CSP header using Java configuration as shown below:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .contentSecurityPolicy(csp ->
                        csp
                            .policyDirectives("script-src 'self' https://trustedscripts.example.com; object-src https://trustedplugins.example.com; report-uri /csp-report-endpoint/")
                       )
            );
    }
}

To enable the CSP 'report-only' header, provide the following Java configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .contentSecurityPolicy(csp ->
                        csp
                            .policyDirectives("script-src 'self' https://trustedscripts.example.com; object-src https://trustedplugins.example.com; report-uri /csp-report-endpoint/")
                            .reportOnly()
                    )
            );
    }
}

Additional Resources

Applying Content Security Policy to a web application is often a non-trivial undertaking. The following resources may provide further assistance in developing effective security policies for your site.

An Introduction to Content Security Policy

CSP Guide - Mozilla Developer Network

W3C Candidate Recommendation

14.2.9 Referrer Policy

Referrer Policy is a mechanism that web applications can leverage to manage the referrer field, which contains the last page the user was on.

Spring Security’s approach is to use Referrer Policy header, which provides different policies:

Referrer-Policy: same-origin

The Referrer-Policy response header instructs the browser to let the destination knows the source where the user was previously.

Configuring Referrer Policy

Spring Security doesn’t add Referrer Policy header by default.

You can enable the Referrer-Policy header using XML configuration with the <referrer-policy> element as shown below:

<http>
    <!-- ... -->

    <headers>
        <referrer-policy policy="same-origin" />
    </headers>
</http>

Similarly, you can enable the Referrer Policy header using Java configuration as shown below:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .referrerPolicy(referrerPolicy ->
                        referrerPolicy
                            .policy(ReferrerPolicy.SAME_ORIGIN)
                    )
            );
    }
}

14.2.10 Feature Policy

Feature Policy is a mechanism that allows web developers to selectively enable, disable, and modify the behavior of certain APIs and web features in the browser.

Feature-Policy: geolocation 'self'

With Feature Policy, developers can opt-in to a set of "policies" for the browser to enforce on specific features used throughout your site. These policies restrict what APIs the site can access or modify the browser’s default behavior for certain features.

Configuring Feature Policy

Spring Security doesn’t add Feature Policy header by default.

You can enable the Feature-Policy header using XML configuration with the <feature-policy> element as shown below:

<http>
    <!-- ... -->

    <headers>
        <feature-policy policy-directives="geolocation 'self'" />
    </headers>
</http>

Similarly, you can enable the Feature Policy header using Java configuration as shown below:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .featurePolicy("geolocation 'self'")
            );
    }
}

14.2.11 Clear Site Data

Clear Site Data is a mechanism by which any browser-side data - cookies, local storage, and the like - can be removed when an HTTP response contains this header:

Clear-Site-Data: "cache", "cookies", "storage", "executionContexts"

This is a nice clean-up action to perform on logout.

Configuring Clear Site Data

Spring Security doesn’t add the Clear Site Data header by default.

You can configure your application to send down this header on logout like so:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .logout()
                .addLogoutHandler(new HeaderWriterLogoutHandler(new ClearSiteDataHeaderWriter(CACHE, COOKIES)));
    }
}
[Note]Note

It’s not recommended that you configure this header writer via the headers() directive. The reason for this is that any session state, say the JSESSIONID cookie, would be removed, effectively logging the user out.

14.2.12 Custom Headers

Spring Security has mechanisms to make it convenient to add the more common security headers to your application. However, it also provides hooks to enable adding custom headers.

Static Headers

There may be times you wish to inject custom security headers into your application that are not supported out of the box. For example, given the following custom security header:

X-Custom-Security-Header: header-value

When using the XML namespace, these headers can be added to the response using the <header> element as shown below:

<http>
    <!-- ... -->

    <headers>
        <header name="X-Custom-Security-Header" value="header-value"/>
    </headers>
</http>

Similarly, the headers could be added to the response using Java Configuration as shown in the following:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .addHeaderWriter(new StaticHeadersWriter("X-Custom-Security-Header","header-value"))
            );
    }
}

Headers Writer

When the namespace or Java configuration does not support the headers you want, you can create a custom HeadersWriter instance or even provide a custom implementation of the HeadersWriter.

Let’s take a look at an example of using an custom instance of XFrameOptionsHeaderWriter. Perhaps you want to allow framing of content for the same origin. This is easily supported by setting the policy attribute to "SAMEORIGIN", but let’s take a look at a more explicit example using the ref attribute.

<http>
    <!-- ... -->

    <headers>
        <header ref="frameOptionsWriter"/>
    </headers>
</http>
<!-- Requires the c-namespace.
See https://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#beans-c-namespace
-->
<beans:bean id="frameOptionsWriter"
    class="org.springframework.security.web.header.writers.frameoptions.XFrameOptionsHeaderWriter"
    c:frameOptionsMode="SAMEORIGIN"/>

We could also restrict framing of content to the same origin with Java configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers(headers ->
                headers
                    .addHeaderWriter(new XFrameOptionsHeaderWriter(XFrameOptionsMode.SAMEORIGIN))
            );
    }
}

DelegatingRequestMatcherHeaderWriter

At times you may want to only write a header for certain requests. For example, perhaps you want to only protect your log in page from being framed. You could use the DelegatingRequestMatcherHeaderWriter to do so. When using the XML namespace configuration, this can be done with the following:

<http>
    <!-- ... -->

    <headers>
        <frame-options disabled="true"/>
        <header ref="headerWriter"/>
    </headers>
</http>

<beans:bean id="headerWriter"
    class="org.springframework.security.web.header.writers.DelegatingRequestMatcherHeaderWriter">
    <beans:constructor-arg>
        <bean class="org.springframework.security.web.util.matcher.AntPathRequestMatcher"
            c:pattern="/login"/>
    </beans:constructor-arg>
    <beans:constructor-arg>
        <beans:bean
            class="org.springframework.security.web.header.writers.frameoptions.XFrameOptionsHeaderWriter"/>
    </beans:constructor-arg>
</beans:bean>

We could also prevent framing of content to the log in page using java configuration:

@EnableWebSecurity
public class WebSecurityConfig extends
WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        RequestMatcher matcher = new AntPathRequestMatcher("/login");
        DelegatingRequestMatcherHeaderWriter headerWriter =
            new DelegatingRequestMatcherHeaderWriter(matcher,new XFrameOptionsHeaderWriter());
        http
            // ...
            .headers(headers ->
                headers
                    .frameOptions(frameOptions ->
                        frameOptions.disable()
                    )
                    .addHeaderWriter(headerWriter)
            );
    }
}

14.3 HTTPS

14.3.1 Adding HTTP/HTTPS Channel Security

If your application supports both HTTP and HTTPS, and you require that particular URLs can only be accessed over HTTPS, then this is directly supported using the requires-channel attribute on <intercept-url>:

<http>
<intercept-url pattern="/secure/**" access="ROLE_USER" requires-channel="https"/>
<intercept-url pattern="/**" access="ROLE_USER" requires-channel="any"/>
...
</http>

With this configuration in place, if a user attempts to access anything matching the "/secure/**" pattern using HTTP, they will first be redirected to an HTTPS URL [10]. The available options are "http", "https" or "any". Using the value "any" means that either HTTP or HTTPS can be used.

If your application uses non-standard ports for HTTP and/or HTTPS, you can specify a list of port mappings as follows:

<http>
...
<port-mappings>
    <port-mapping http="9080" https="9443"/>
</port-mappings>
</http>

Note that in order to be truly secure, an application should not use HTTP at all or switch between HTTP and HTTPS. It should start in HTTPS (with the user entering an HTTPS URL) and use a secure connection throughout to avoid any possibility of man-in-the-middle attacks.



[10] For more details on how channel-processing is implemented, see the Javadoc for ChannelProcessingFilter and related classes.

15. Integrations

15.1 Servlet API integration

This section describes how Spring Security is integrated with the Servlet API. The servletapi-xml sample application demonstrates the usage of each of these methods.

15.1.1 Servlet 2.5+ Integration

HttpServletRequest.getRemoteUser()

The HttpServletRequest.getRemoteUser() will return the result of SecurityContextHolder.getContext().getAuthentication().getName() which is typically the current username. This can be useful if you want to display the current username in your application. Additionally, checking if this is null can be used to indicate if a user has authenticated or is anonymous. Knowing if the user is authenticated or not can be useful for determining if certain UI elements should be shown or not (i.e. a log out link should only be displayed if the user is authenticated).

HttpServletRequest.getUserPrincipal()

The HttpServletRequest.getUserPrincipal() will return the result of SecurityContextHolder.getContext().getAuthentication(). This means it is an Authentication which is typically an instance of UsernamePasswordAuthenticationToken when using username and password based authentication. This can be useful if you need additional information about your user. For example, you might have created a custom UserDetailsService that returns a custom UserDetails containing a first and last name for your user. You could obtain this information with the following:

Authentication auth = httpServletRequest.getUserPrincipal();
// assume integrated custom UserDetails called MyCustomUserDetails
// by default, typically instance of UserDetails
MyCustomUserDetails userDetails = (MyCustomUserDetails) auth.getPrincipal();
String firstName = userDetails.getFirstName();
String lastName = userDetails.getLastName();
[Note]Note

It should be noted that it is typically bad practice to perform so much logic throughout your application. Instead, one should centralize it to reduce any coupling of Spring Security and the Servlet API’s.

HttpServletRequest.isUserInRole(String)

The HttpServletRequest.isUserInRole(String) will determine if SecurityContextHolder.getContext().getAuthentication().getAuthorities() contains a GrantedAuthority with the role passed into isUserInRole(String). Typically users should not pass in the "ROLE_" prefix into this method since it is added automatically. For example, if you want to determine if the current user has the authority "ROLE_ADMIN", you could use the following:

boolean isAdmin = httpServletRequest.isUserInRole("ADMIN");

This might be useful to determine if certain UI components should be displayed. For example, you might display admin links only if the current user is an admin.

15.1.2 Servlet 3+ Integration

The following section describes the Servlet 3 methods that Spring Security integrates with.

HttpServletRequest.authenticate(HttpServletRequest,HttpServletResponse)

The HttpServletRequest.authenticate(HttpServletRequest,HttpServletResponse) method can be used to ensure that a user is authenticated. If they are not authenticated, the configured AuthenticationEntryPoint will be used to request the user to authenticate (i.e. redirect to the login page).

HttpServletRequest.login(String,String)

The HttpServletRequest.login(String,String) method can be used to authenticate the user with the current AuthenticationManager. For example, the following would attempt to authenticate with the username "user" and password "password":

try {
httpServletRequest.login("user","password");
} catch