Spring Method Security介绍

最后修改: 2022-05-20T18:28:02+00:00

1. 概述

简单来说，Spring Security支持方法级别授权认证。

通常，我们可以通过例如限制哪些角色能够执行某方法来保护我们的服务层，并使用专用的方法级安全性测试支持对其进行测试。

在本文中，我们将首先回顾一些Security注解用法。 然后，我们将重点介绍使用不同策略测试方法的安全性。

2. 开启 Method Security

首先，要使用Method Security，需要先添加spring-security-config依赖：

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-config</artifactId>
</dependency>

最新版本可以从 Maven仓库找上找到。

如果我们想使用Spring Boot，我们可以使用spring-boot-starter-security依赖，它里面包含了spring-security-config。

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

同样，最新版本可以从 Maven仓库上找到。

下一步, 我们需要开启global Method Security:

@Configuration
@EnableGlobalMethodSecurity(
  prePostEnabled = true, 
  securedEnabled = true, 
  jsr250Enabled = true)
public class MethodSecurityConfig 
  extends GlobalMethodSecurityConfiguration {
}
  • prePostEnabled 属性开启Spring Security pre/post 注解
  • securedEnabled 属性决定是否开启@Secured注解
  • jsr250Enabled 属性运行我们使用@RoleAllowed注解

我们将在下一部分中探索有关这些注释的更多信息。

3. 应用 Method Security

3.1. 使用@Secured注解

@Secured注解在方式上指定允许访问的角色列表。只有拥有至少一个指定角色的用户，才能访问该方法。

让我们定义一个 getUsername 方法：

@Secured("ROLE_VIEWER")
public String getUsername() {
    SecurityContext securityContext = SecurityContextHolder.getContext();
    return securityContext.getAuthentication().getName();
}

这里，@Secured(“ROLE_VIEWER”)注解定义了只有拥有ROLE_VIEWER角色的用户，才能执行getUsername方法。

此外，我们可以在@Secured中定义多个角色

@Secured({ "ROLE_VIEWER", "ROLE_EDITOR" })
public boolean isValidUsername(String username) {
    return userRoleRepository.isValidUsername(username);
}

这个例子中，注解声明了如果用户具有ROLE_VIEWER或ROLE_EDITOR角色，则可以调用isValidUsername方法。

@Secured注解不支持Spring表达式语言 (SpEL)。

3.2. 使用@RoleAllowed注解

** @RolesAllowed是 JSR-250 定义的 Java 标准注解，作用和@Secured等效。**

Basically, we can use the @RoleAllowed annotation in a similar way as @Secured. Thus, we could re-define getUsername and isValidUsername methods: @RoleAllowed用法和@Secured基本类似。我们可以使用@RoleAllowed注解重新定义getUsername和isValidUsername方法：

@RolesAllowed("ROLE_VIEWER")
public String getUsername2() {
    //...
}
    
@RolesAllowed({ "ROLE_VIEWER", "ROLE_EDITOR" })
public boolean isValidUsername2(String username) {
    //...
}

类似的, 具有ROLE_VIEWER角色的用户才能执行getUsername2。

具有ROLE_VIEWER或ROLE_EDITOR角色的用户才能调用isValidUsername2方法。

3.3. 使用@PreAuthorize和@PostAuthorize注解

Both @PreAuthorize and @PostAuthorize annotations provide expression-based access control. Hence, predicates can be written using SpEL (Spring Expression Language).

The @PreAuthorize annotation checks the given expression before entering the method, whereas, the @PostAuthorize annotation verifies it after the execution of the method and could alter the result.

Now, let's declare a getUsernameInUpperCase method as below:

@PreAuthorize("hasRole('ROLE_VIEWER')")
public String getUsernameInUpperCase() {
    return getUsername().toUpperCase();
}

The @PreAuthorize(“hasRole(‘ROLE_VIEWER')”) has the same meaning as @Secured(“ROLE_VIEWER”) which we used in the previous section. Feel free to discover more security expressions details in previous articles.

Consequently, the annotation @Secured({“ROLE_VIEWER”,”ROLE_EDITOR”}) can be replaced with @PreAuthorize(“hasRole(‘ROLE_VIEWER') or hasRole(‘ROLE_EDITOR')”):

@PreAuthorize("hasRole('ROLE_VIEWER') or hasRole('ROLE_EDITOR')")
public boolean isValidUsername3(String username) {
    //...
}

Moreover, we can actually use the method argument as part of the expression:

@PreAuthorize("#username == authentication.principal.username")
public String getMyRoles(String username) {
    //...
}

Here, a user can invoke the getMyRoles method only if the value of the argument username is the same as current principal's username.

It's worth to note that @PreAuthorize expressions can be replaced by @PostAuthorize ones.

Let's rewrite getMyRoles:

@PostAuthorize("#username == authentication.principal.username")
public String getMyRoles2(String username) {
    //...
}

In the previous example, however, the authorization would get delayed after the execution of the target method.

Additionally, the @PostAuthorize annotation provides the ability to access the method result:

@PostAuthorize
  ("returnObject.username == authentication.principal.nickName")
public CustomUser loadUserDetail(String username) {
    return userRoleRepository.loadUserByUserName(username);
}

In this example, the loadUserDetail method would only execute successfully if the username of the returned CustomUser is equal to the current authentication principal's nickname.

In this section, we mostly use simple Spring expressions. For more complex scenarios, we could create custom security expressions.

3.4. Using @PreFilter and @PostFilter Annotations

Spring Security provides the @PreFilter annotation to filter a collection argument before executing the method:

@PreFilter("filterObject != authentication.principal.username")
public String joinUsernames(List<String> usernames) {
    return usernames.stream().collect(Collectors.joining(";"));
}

In this example, we're joining all usernames except for the one who is authenticated.

Here, in our expression, we use the name filterObject to represent the current object in the collection.

However, if the method has more than one argument which is a collection type, we need to use the filterTarget property to specify which argument we want to filter:

@PreFilter
  (value = "filterObject != authentication.principal.username",
  filterTarget = "usernames")
public String joinUsernamesAndRoles(
  List<String> usernames, List<String> roles) {
 
    return usernames.stream().collect(Collectors.joining(";")) 
      + ":" + roles.stream().collect(Collectors.joining(";"));
}

Additionally, we can also filter the returned collection of a method by using @PostFilter annotation:

@PostFilter("filterObject != authentication.principal.username")
public List<String> getAllUsernamesExceptCurrent() {
    return userRoleRepository.getAllUsernames();
}

In this case, the name filterObject refers to the current object in the returned collection.

With that configuration, Spring Security will iterate through the returned list and remove any value matching the principal's username.

Spring Security – @PreFilter and @PostFilter article describes both annotations in greater detail.

3.5. Method Security Meta-Annotation

We typically find ourselves in a situation where we protect different methods using the same security configuration.

In this case, we can define a security meta-annotation:

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@PreAuthorize("hasRole('VIEWER')")
public @interface IsViewer {
}

Next, we can directly use the @IsViewer annotation to secure our method:

@IsViewer
public String getUsername4() {
    //...
}

Security meta-annotations are a great idea because they add more semantics and decouple our business logic from the security framework.

3.6. Security Annotation at the Class Level

If we find ourselves using the same security annotation for every method within one class, we can consider putting that annotation at class level:

@Service
@PreAuthorize("hasRole('ROLE_ADMIN')")
public class SystemService {

    public String getSystemYear(){
        //...
    }
 
    public String getSystemDate(){
        //...
    }
}

In above example, the security rule hasRole(‘ROLE_ADMIN') will be applied to both getSystemYear and getSystemDate methods.

3.7. Multiple Security Annotations on a Method

We can also use multiple security annotations on one method:

@PreAuthorize("#username == authentication.principal.username")
@PostAuthorize("returnObject.username == authentication.principal.nickName")
public CustomUser securedLoadUserDetail(String username) {
    return userRoleRepository.loadUserByUserName(username);
}

Hence, Spring will verify authorization both before and after the execution of the securedLoadUserDetail method.

4. Important Considerations

There are two points we'd like to remind regarding method security:

  • By default, Spring AOP proxying is used to apply method security – if a secured method A is called by another method within the same class, security in A is ignored altogether. This means method A will execute without any security checking. The same applies to private methods
  • Spring SecurityContext is thread-bound – by default, the security context isn't propagated to child-threads. For more information, we can refer to Spring Security Context Propagation article

5. Testing Method Security

5.1. Configuration

To test Spring Security with JUnit, we need the spring-security-test dependency:

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-test</artifactId>
</dependency>

We don't need to specify the dependency version because we're using the Spring Boot plugin. We can find the latest version of this dependency on Maven Central.

Next, let's configure a simple Spring Integration test by specifying the runner and the ApplicationContext configuration:

@RunWith(SpringRunner.class)
@ContextConfiguration
public class MethodSecurityIntegrationTest {
    // ...
}

5.2. Testing Username and Roles

Now that our configuration is ready, let's try to test our getUsername method which we secured with the @Secured(“ROLE_VIEWER”) annotation_:_

@Secured("ROLE_VIEWER")
public String getUsername() {
    SecurityContext securityContext = SecurityContextHolder.getContext();
    return securityContext.getAuthentication().getName();
}

Since we use the @Secured annotation here, it requires a user to be authenticated to invoke the method. Otherwise, we'll get an AuthenticationCredentialsNotFoundException.

Hence, we need to provide a user to test our secured method. To achieve this, we decorate the test method with @WithMockUser and provide a user and roles:

@Test
@WithMockUser(username = "john", roles = { "VIEWER" })
public void givenRoleViewer_whenCallGetUsername_thenReturnUsername() {
    String userName = userRoleService.getUsername();
    
    assertEquals("john", userName);
}

We've provided an authenticated user whose username is john and whose role is ROLE_VIEWER. If we don't specify the username or role, the default username is user and default role is ROLE_USER.

Note that it isn't necessary to add the ROLE_ prefix here, Spring Security will add that prefix automatically.

If we don't want to have that prefix, we can consider using authority instead of role.

For example, let's declare a getUsernameInLowerCase method:

@PreAuthorize("hasAuthority('SYS_ADMIN')")
public String getUsernameLC(){
    return getUsername().toLowerCase();
}

We could test that using authorities:

@Test
@WithMockUser(username = "JOHN", authorities = { "SYS_ADMIN" })
public void givenAuthoritySysAdmin_whenCallGetUsernameLC_thenReturnUsername() {
    String username = userRoleService.getUsernameInLowerCase();

    assertEquals("john", username);
}

Conveniently, if we want to use the same user for many test cases, we can declare the @WithMockUser annotation at test class:

@RunWith(SpringRunner.class)
@ContextConfiguration
@WithMockUser(username = "john", roles = { "VIEWER" })
public class MockUserAtClassLevelIntegrationTest {
    //...
}

If we wanted to run our test as an anonymous user, we could use the @WithAnonymousUser annotation:

@Test(expected = AccessDeniedException.class)
@WithAnonymousUser
public void givenAnomynousUser_whenCallGetUsername_thenAccessDenied() {
    userRoleService.getUsername();
}

In the example above, we expect an AccessDeniedException because the anonymous user isn't granted the role ROLE_VIEWER or the authority SYS_ADMIN.

5.3. Testing With a Custom UserDetailsService

For most applications, it's common to use a custom class as authentication principal. In this case, the custom class needs to implement the _org.springframework.security.core.userdetails._UserDetails interface.

In this article, we declare a CustomUser class which extends the existing implementation of UserDetails, which is _org.springframework.security.core.userdetails._User:

public class CustomUser extends User {
    private String nickName;
    // getter and setter
}

Let's take back the example with the @PostAuthorize annotation in section 3:

@PostAuthorize("returnObject.username == authentication.principal.nickName")
public CustomUser loadUserDetail(String username) {
    return userRoleRepository.loadUserByUserName(username);
}

In this case, the method would only execute successfully if the username of the returned CustomUser is equal to the current authentication principal's nickname.

If we wanted to test that method**, we could provide an implementation of UserDetailsService which could load our CustomUser based on the username**:

@Test
@WithUserDetails(
  value = "john", 
  userDetailsServiceBeanName = "userDetailService")
public void whenJohn_callLoadUserDetail_thenOK() {
 
    CustomUser user = userService.loadUserDetail("jane");

    assertEquals("jane", user.getNickName());
}

Here, the @WithUserDetails annotation states that we'll use a UserDetailsService to initialize our authenticated user. The service is referred by the userDetailsServiceBeanName property_._ This UserDetailsService might be a real implementation or a fake for testing purposes.

Additionally, the service will use the value of the property value as the username to load UserDetails.

Conveniently, we can also decorate with a @WithUserDetails annotation at the class level, similarly to what we did with the @WithMockUser annotation_._

5.4. Testing With Meta Annotations

We often find ourselves reusing the same user/roles over and over again in various tests.

For these situations, it's convenient to create a meta-annotation.

Taking back the previous example @WithMockUser(username=”john”, roles={“VIEWER”}), we can declare a meta-annotation as:

@Retention(RetentionPolicy.RUNTIME)
@WithMockUser(value = "john", roles = "VIEWER")
public @interface WithMockJohnViewer { }

Then we can simply use @WithMockJohnViewer in our test:

@Test
@WithMockJohnViewer
public void givenMockedJohnViewer_whenCallGetUsername_thenReturnUsername() {
    String userName = userRoleService.getUsername();

    assertEquals("john", userName);
}

Likewise, we can use meta-annotations to create domain-specific users using @WithUserDetails.

6. 总结

In this tutorial, we've explored various options for using Method Security in Spring Security.

We also have gone through a few techniques to easily test method security and learned how to reuse mocked users in different tests.

All examples of this tutorial can be found over on Github.