# Spring MVC Integration

Spring Security provides a number of optional integrations with Spring MVC. This section covers the integration in further detail.

# @EnableWebMvcSecurity

As of Spring Security 4.0, @EnableWebMvcSecurity is deprecated.
The replacement is @EnableWebSecurity which will determine adding the Spring MVC features based upon the classpath.

To enable Spring Security integration with Spring MVC add the @EnableWebSecurity annotation to your configuration.

Spring Security provides the configuration using Spring MVC’s WebMvcConfigurer (opens new window).
This means that if you are using more advanced options, like integrating with WebMvcConfigurationSupport directly, then you will need to manually provide the Spring Security configuration.

# MvcRequestMatcher

Spring Security provides deep integration with how Spring MVC matches on URLs with MvcRequestMatcher. This is helpful to ensure your Security rules match the logic used to handle your requests.

In order to use MvcRequestMatcher you must place the Spring Security Configuration in the same ApplicationContext as your DispatcherServlet. This is necessary because Spring Security’s MvcRequestMatcher expects a HandlerMappingIntrospector bean with the name of mvcHandlerMappingIntrospector to be registered by your Spring MVC configuration that is used to perform the matching.

For a web.xml this means that you should place your configuration in the DispatcherServlet.xml.

<listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

<!-- All Spring Configuration (both MVC and Security) are in /WEB-INF/spring/ -->
<context-param>
  <param-name>contextConfigLocation</param-name>
  <param-value>/WEB-INF/spring/*.xml</param-value>
</context-param>

<servlet>
  <servlet-name>spring</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <!-- Load from the ContextLoaderListener -->
  <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>

Below WebSecurityConfiguration in placed in the DispatcherServlets ApplicationContext.

Java

public class SecurityInitializer extends
    AbstractAnnotationConfigDispatcherServletInitializer {

  @Override
  protected Class<?>[] getRootConfigClasses() {
    return null;
  }

  @Override
  protected Class<?>[] getServletConfigClasses() {
    return new Class[] { RootConfiguration.class,
        WebMvcConfiguration.class };
  }

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

Kotlin

class SecurityInitializer : AbstractAnnotationConfigDispatcherServletInitializer() {
    override fun getRootConfigClasses(): Array<Class<*>>? {
        return null
    }

    override fun getServletConfigClasses(): Array<Class<*>> {
        return arrayOf(
            RootConfiguration::class.java,
            WebMvcConfiguration::class.java
        )
    }

    override fun getServletMappings(): Array<String> {
        return arrayOf("/")
    }
}
It is always recommended to provide authorization rules by matching on the HttpServletRequest and method security.

Providing authorization rules by matching on HttpServletRequest is good because it happens very early in the code path and helps reduce the attack surface (opens new window).
Method security ensures that if someone has bypassed the web authorization rules, that your application is still secured.
This is what is known as Defence in Depth (opens new window)

Consider a controller that is mapped as follows:

Java

@RequestMapping("/admin")
public String admin() {

Kotlin

@RequestMapping("/admin")
fun admin(): String {

If we wanted to restrict access to this controller method to admin users, a developer can provide authorization rules by matching on the HttpServletRequest with the following:

Java

protected configure(HttpSecurity http) throws Exception {
	http
		.authorizeHttpRequests(authorize -> authorize
			.antMatchers("/admin").hasRole("ADMIN")
		);
}

Kotlin

override fun configure(http: HttpSecurity) {
    http {
        authorizeRequests {
            authorize(AntPathRequestMatcher("/admin"), hasRole("ADMIN"))
        }
    }
}

or in XML

<http>
	<intercept-url pattern="/admin" access="hasRole('ADMIN')"/>
</http>

With either configuration, the URL /admin will require the authenticated user to be an admin user. However, depending on our Spring MVC configuration, the URL /admin.html will also map to our admin() method. Additionally, depending on our Spring MVC configuration, the URL /admin/ will also map to our admin() method.

The problem is that our security rule is only protecting /admin. We could add additional rules for all the permutations of Spring MVC, but this would be quite verbose and tedious.

Instead, we can leverage Spring Security’s MvcRequestMatcher. The following configuration will protect the same URLs that Spring MVC will match on by using Spring MVC to match on the URL.

Java

protected configure(HttpSecurity http) throws Exception {
	http
		.authorizeHttpRequests(authorize -> authorize
			.mvcMatchers("/admin").hasRole("ADMIN")
		);
}

Kotlin

override fun configure(http: HttpSecurity) {
    http {
        authorizeRequests {
            authorize("/admin", hasRole("ADMIN"))
        }
    }
}

or in XML

<http request-matcher="mvc">
	<intercept-url pattern="/admin" access="hasRole('ADMIN')"/>
</http>

# @AuthenticationPrincipal

Spring Security provides AuthenticationPrincipalArgumentResolver which can automatically resolve the current Authentication.getPrincipal() for Spring MVC arguments. By using @EnableWebSecurity you will automatically have this added to your Spring MVC configuration. If you use XML based configuration, you must add this yourself. For example:

<mvc:annotation-driven>
		<mvc:argument-resolvers>
				<bean class="org.springframework.security.web.method.annotation.AuthenticationPrincipalArgumentResolver" />
		</mvc:argument-resolvers>
</mvc:annotation-driven>

Once AuthenticationPrincipalArgumentResolver is properly configured, you can be entirely decoupled from Spring Security in your Spring MVC layer.

Consider a situation where a custom UserDetailsService that returns an Object that implements UserDetails and your own CustomUser Object. The CustomUser of the currently authenticated user could be accessed using the following code:

Java

@RequestMapping("/messages/inbox")
public ModelAndView findMessagesForUser() {
	Authentication authentication =
	SecurityContextHolder.getContext().getAuthentication();
	CustomUser custom = (CustomUser) authentication == null ? null : authentication.getPrincipal();

	// .. find messages for this user and return them ...
}

Kotlin

@RequestMapping("/messages/inbox")
open fun findMessagesForUser(): ModelAndView {
    val authentication: Authentication = SecurityContextHolder.getContext().authentication
    val custom: CustomUser? = if (authentication as CustomUser == null) null else authentication.principal

    // .. find messages for this user and return them ...
}

As of Spring Security 3.2 we can resolve the argument more directly by adding an annotation. For example:

Java

import org.springframework.security.core.annotation.AuthenticationPrincipal;

// ...

@RequestMapping("/messages/inbox")
public ModelAndView findMessagesForUser(@AuthenticationPrincipal CustomUser customUser) {

	// .. find messages for this user and return them ...
}

Kotlin

@RequestMapping("/messages/inbox")
open fun findMessagesForUser(@AuthenticationPrincipal customUser: CustomUser?): ModelAndView {

    // .. find messages for this user and return them ...
}

Sometimes it may be necessary to transform the principal in some way. For example, if CustomUser needed to be final it could not be extended. In this situation the UserDetailsService might returns an Object that implements UserDetails and provides a method named getCustomUser to access CustomUser. For example, it might look like:

Java

public class CustomUserUserDetails extends User {
		// ...
		public CustomUser getCustomUser() {
				return customUser;
		}
}

Kotlin

class CustomUserUserDetails(
    username: String?,
    password: String?,
    authorities: MutableCollection<out GrantedAuthority>?
) : User(username, password, authorities) {
    // ...
    val customUser: CustomUser? = null
}

We could then access the CustomUser using a SpEL expression (opens new window) that uses Authentication.getPrincipal() as the root object:

Java

import org.springframework.security.core.annotation.AuthenticationPrincipal;

// ...

@RequestMapping("/messages/inbox")
public ModelAndView findMessagesForUser(@AuthenticationPrincipal(expression = "customUser") CustomUser customUser) {

	// .. find messages for this user and return them ...
}

Kotlin

import org.springframework.security.core.annotation.AuthenticationPrincipal

// ...

@RequestMapping("/messages/inbox")
open fun findMessagesForUser(@AuthenticationPrincipal(expression = "customUser") customUser: CustomUser?): ModelAndView {

    // .. find messages for this user and return them ...
}

We can also refer to Beans in our SpEL expressions. For example, the following could be used if we were using JPA to manage our Users and we wanted to modify and save a property on the current user.

Java

import org.springframework.security.core.annotation.AuthenticationPrincipal;

// ...

@PutMapping("/users/self")
public ModelAndView updateName(@AuthenticationPrincipal(expression = "@jpaEntityManager.merge(#this)") CustomUser attachedCustomUser,
		@RequestParam String firstName) {

	// change the firstName on an attached instance which will be persisted to the database
	attachedCustomUser.setFirstName(firstName);

	// ...
}

Kotlin

import org.springframework.security.core.annotation.AuthenticationPrincipal

// ...

@PutMapping("/users/self")
open fun updateName(
    @AuthenticationPrincipal(expression = "@jpaEntityManager.merge(#this)") attachedCustomUser: CustomUser,
    @RequestParam firstName: String?
): ModelAndView {

    // change the firstName on an attached instance which will be persisted to the database
    attachedCustomUser.setFirstName(firstName)

    // ...
}

We can further remove our dependency on Spring Security by making @AuthenticationPrincipal a meta annotation on our own annotation. Below we demonstrate how we could do this on an annotation named @CurrentUser.

It is important to realize that in order to remove the dependency on Spring Security, it is the consuming application that would create @CurrentUser.
This step is not strictly required, but assists in isolating your dependency to Spring Security to a more central location.

Java

@Target({ElementType.PARAMETER, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@AuthenticationPrincipal
public @interface CurrentUser {}

Kotlin

@Target(AnnotationTarget.VALUE_PARAMETER, AnnotationTarget.TYPE)
@Retention(AnnotationRetention.RUNTIME)
@MustBeDocumented
@AuthenticationPrincipal
annotation class CurrentUser

Now that @CurrentUser has been specified, we can use it to signal to resolve our CustomUser of the currently authenticated user. We have also isolated our dependency on Spring Security to a single file.

Java

@RequestMapping("/messages/inbox")
public ModelAndView findMessagesForUser(@CurrentUser CustomUser customUser) {

	// .. find messages for this user and return them ...
}

Kotlin

@RequestMapping("/messages/inbox")
open fun findMessagesForUser(@CurrentUser customUser: CustomUser?): ModelAndView {

    // .. find messages for this user and return them ...
}

# Spring MVC Async Integration

Spring Web MVC 3.2+ has excellent support for Asynchronous Request Processing (opens new window). With no additional configuration, Spring Security will automatically setup the SecurityContext to the Thread that invokes a Callable returned by your controllers. For example, the following method will automatically have its Callable invoked with the SecurityContext that was available when the Callable was created:

Java

@RequestMapping(method=RequestMethod.POST)
public Callable<String> processUpload(final MultipartFile file) {

return new Callable<String>() {
	public Object call() throws Exception {
	// ...
	return "someView";
	}
};
}

Kotlin

@RequestMapping(method = [RequestMethod.POST])
open fun processUpload(file: MultipartFile?): Callable<String> {
    return Callable {
        // ...
        "someView"
    }
}
Associating SecurityContext to Callable’s

More technically speaking, Spring Security integrates with WebAsyncManager.
The SecurityContext that is used to process the Callable is the SecurityContext that exists on the SecurityContextHolder at the time startCallableProcessing is invoked.

There is no automatic integration with a DeferredResult that is returned by controllers. This is because DeferredResult is processed by the users and thus there is no way of automatically integrating with it. However, you can still use Concurrency Support to provide transparent integration with Spring Security.

# Spring MVC and CSRF Integration

# Automatic Token Inclusion

Spring Security will automatically include the CSRF Token within forms that use the Spring MVC form tag (opens new window). For example, the following JSP:

<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page"
	xmlns:c="http://java.sun.com/jsp/jstl/core"
	xmlns:form="http://www.springframework.org/tags/form" version="2.0">
	<jsp:directive.page language="java" contentType="text/html" />
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
	<!-- ... -->

	<c:url var="logoutUrl" value="/logout"/>
	<form:form action="${logoutUrl}"
		method="post">
	<input type="submit"
		value="Log out" />
	<input type="hidden"
		name="${_csrf.parameterName}"
		value="${_csrf.token}"/>
	</form:form>

	<!-- ... -->
</html>
</jsp:root>

Will output HTML that is similar to the following:

<!-- ... -->

<form action="/context/logout" method="post">
<input type="submit" value="Log out"/>
<input type="hidden" name="_csrf" value="f81d4fae-7dec-11d0-a765-00a0c91e6bf6"/>
</form>

<!-- ... -->

# Resolving the CsrfToken

Spring Security provides CsrfTokenArgumentResolver which can automatically resolve the current CsrfToken for Spring MVC arguments. By using @EnableWebSecurity you will automatically have this added to your Spring MVC configuration. If you use XML based configuration, you must add this yourself.

Once CsrfTokenArgumentResolver is properly configured, you can expose the CsrfToken to your static HTML based application.

Java

@RestController
public class CsrfController {

	@RequestMapping("/csrf")
	public CsrfToken csrf(CsrfToken token) {
		return token;
	}
}

Kotlin

@RestController
class CsrfController {
    @RequestMapping("/csrf")
    fun csrf(token: CsrfToken): CsrfToken {
        return token
    }
}

It is important to keep the CsrfToken a secret from other domains. This means if you are using Cross Origin Sharing (CORS) (opens new window), you should NOT expose the CsrfToken to any external domains.

Spring DataWebSocket