[[servlet-authorization-authorizationfilter]]
= Authorize HttpServletRequests with AuthorizationFilter
:figures: servlet/authorization

This section builds on xref:servlet/architecture.adoc#servlet-architecture[Servlet Architecture and Implementation] by digging deeper into how xref:servlet/authorization/index.adoc#servlet-authorization[authorization] works within Servlet-based applications.

[NOTE]
`AuthorizationFilter` supersedes xref:servlet/authorization/authorize-requests.adoc#servlet-authorization-filtersecurityinterceptor[`FilterSecurityInterceptor`].
To remain backward compatible, `FilterSecurityInterceptor` remains the default.
This section discusses how `AuthorizationFilter` works and how to override the default configuration.

The {security-api-url}org/springframework/security/web/access/intercept/AuthorizationFilter.html[`AuthorizationFilter`] provides xref:servlet/authorization/index.adoc#servlet-authorization[authorization] for ``HttpServletRequest``s.
It is inserted into the xref:servlet/architecture.adoc#servlet-filterchainproxy[FilterChainProxy] as one of the xref:servlet/architecture.adoc#servlet-security-filters[Security Filters].

You can override the default when you declare a `SecurityFilterChain`.
Instead of using xref:servlet/authorization/authorize-http-requests.adoc#servlet-authorize-requests-defaults[`authorizeRequests`], use `authorizeHttpRequests`, like so:

.Use authorizeHttpRequests
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http) throws AuthenticationException {
    http
        .authorizeHttpRequests((authorize) -> authorize
            .anyRequest().authenticated();
        )
        // ...

    return http.build();
}
----
====

This improves on `authorizeRequests` in a number of ways:

1. Uses the simplified `AuthorizationManager` API instead of metadata sources, config attributes, decision managers, and voters.
This simplifies reuse and customization.
2. Delays `Authentication` lookup.
Instead of the authentication needing to be looked up for every request, it will only look it up in requests where an authorization decision requires authentication.
3. Bean-based configuration support.

When `authorizeHttpRequests` is used instead of `authorizeRequests`, then {security-api-url}org/springframework/security/web/access/intercept/AuthorizationFilter.html[`AuthorizationFilter`] is used instead of xref:servlet/authorization/authorize-requests.adoc#servlet-authorization-filtersecurityinterceptor[`FilterSecurityInterceptor`].

.Authorize HttpServletRequest
image::{figures}/authorizationfilter.png[]

* image:{icondir}/number_1.png[] First, the `AuthorizationFilter` obtains an  xref:servlet/authentication/architecture.adoc#servlet-authentication-authentication[Authentication] from the xref:servlet/authentication/architecture.adoc#servlet-authentication-securitycontextholder[SecurityContextHolder].
It wraps this in an `Supplier` in order to delay lookup.
* image:{icondir}/number_2.png[] Second, `AuthorizationFilter` creates a {security-api-url}org/springframework/security/web/FilterInvocation.html[`FilterInvocation`] from the `HttpServletRequest`, `HttpServletResponse`, and `FilterChain`.
// FIXME: link to FilterInvocation
* image:{icondir}/number_3.png[] Next, it passes the `Supplier<Authentication>` and `FilterInvocation` to the xref:servlet/architecture.adoc#authz-authorization-manager[`AuthorizationManager`].
** image:{icondir}/number_4.png[] If authorization is denied, an `AccessDeniedException` is thrown.
In this case the xref:servlet/architecture.adoc#servlet-exceptiontranslationfilter[`ExceptionTranslationFilter`] handles the `AccessDeniedException`.
** image:{icondir}/number_5.png[] If access is granted, `AuthorizationFilter` continues with the xref:servlet/architecture.adoc#servlet-filters-review[FilterChain] which allows the application to process normally.

We can configure Spring Security to have different rules by adding more rules in order of precedence.

.Authorize Requests
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http) throws Exception {
	http
		// ...
		.authorizeHttpRequests(authorize -> authorize                                  // <1>
			.mvcMatchers("/resources/**", "/signup", "/about").permitAll()         // <2>
			.mvcMatchers("/admin/**").hasRole("ADMIN")                             // <3>
			.mvcMatchers("/db/**").access("hasRole('ADMIN') and hasRole('DBA')")   // <4>
			.anyRequest().denyAll()                                                // <5>
		);

	return http.build();
}
----
====
<1> There are multiple authorization rules specified.
Each rule 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 is denied access.
This is a good strategy if you do not want to accidentally forget to update your authorization rules.

You can take a bean-based approach by constructing your own xref:servlet/authorization/architecture.adoc#authz-delegate-authorization-manager[`RequestMatcherDelegatingAuthorizationManager`] like so:

.Configure RequestMatcherDelegatingAuthorizationManager
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http, AuthorizationManager<RequestAuthorizationContext> access)
        throws AuthenticationException {
    http
        .authorizeHttpRequests((authorize) -> authorize
            .anyRequest().access(access)
        )
        // ...

    return http.build();
}

@Bean
AuthorizationManager<RequestAuthorizationContext> requestMatcherAuthorizationManager(HandlerMappingIntrospector introspector) {
    RequestMatcher permitAll =
            new AndRequestMatcher(
                    new MvcRequestMatcher(introspector, "/resources/**"),
                    new MvcRequestMatcher(introspector, "/signup"),
                    new MvcRequestMatcher(introspector, "/about"));
    RequestMatcher admin = new MvcRequestMatcher(introspector, "/admin/**");
    RequestMatcher db = new MvcRequestMatcher(introspector, "/db/**");
    RequestMatcher any = AnyRequestMatcher.INSTANCE;
    AuthorizationManager<HttpRequestServlet> manager = RequestMatcherDelegatingAuthorizationManager.builder()
            .add(permitAll, (context) -> new AuthorizationDecision(true))
            .add(admin, AuthorityAuthorizationManager.hasRole("ADMIN"))
            .add(db, AuthorityAuthorizationManager.hasRole("DBA"))
            .add(any, new AuthenticatedAuthorizationManager())
            .build();
    return (context) -> manager.check(context.getRequest());
}
----
====

You can also wire xref:servlet/authorization/architecture.adoc#authz-custom-authorization-manager[your own custom authorization managers] for any request matcher.

Here is an example of mapping a custom authorization manager to the `my/authorized/endpoint`:

.Custom Authorization Manager
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http) throws Exception {
    http
        .authorizeHttpRequests((authorize) -> authorize
            .mvcMatchers("/my/authorized/endpoint").access(new CustomAuthorizationManager());
        )
        // ...

    return http.build();
}
----
====

Or you can provide it for all requests as seen below:

.Custom Authorization Manager for All Requests
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http) throws Exception {
    http
        .authorizeHttpRequests((authorize) -> authorize
            .anyRequest.access(new CustomAuthorizationManager());
        )
        // ...

    return http.build();
}
----
====

By default, the `AuthorizationFilter` applies to all dispatcher types.
We can configure Spring Security to not apply the authorization rules to all dispatcher types by using the `shouldFilterAllDispatcherTypes` method:

.Set shouldFilterAllDispatcherTypes to false
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http) throws Exception {
    http
        .authorizeHttpRequests((authorize) -> authorize
            .shouldFilterAllDispatcherTypes(false)
            .anyRequest.authenticated()
        )
        // ...

    return http.build();
}
----
====