[[servlet-authorization-filtersecurityinterceptor]]
= Authorize HttpServletRequest with FilterSecurityInterceptor
:figures: servlet/authorization

[NOTE]
====
`FilterSecurityInterceptor` is in the process of being replaced by xref:servlet/authorization/authorize-http-requests.adoc[`AuthorizationFilter`].
Consider using that instead.
====

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.

The {security-api-url}org/springframework/security/web/access/intercept/FilterSecurityInterceptor.html[`FilterSecurityInterceptor`] provides xref:servlet/authorization/index.adoc#servlet-authorization[authorization] for `HttpServletRequest` instances.
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].

The following image shows the role of `FilterSecurityInterceptor`:

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

image:{icondir}/number_1.png[] The `FilterSecurityInterceptor` obtains an xref:servlet/authentication/architecture.adoc#servlet-authentication-authentication[Authentication] from the xref:servlet/authentication/architecture.adoc#servlet-authentication-securitycontextholder[SecurityContextHolder].
image:{icondir}/number_2.png[] `FilterSecurityInterceptor` creates a {security-api-url}org/springframework/security/web/FilterInvocation.html[`FilterInvocation`] from the `HttpServletRequest`, `HttpServletResponse`, and `FilterChain` that are passed into the `FilterSecurityInterceptor`.
image:{icondir}/number_3.png[] It passes the `FilterInvocation` to `SecurityMetadataSource` to get the ``ConfigAttribute``s.
image:{icondir}/number_4.png[] It passes the `Authentication`, `FilterInvocation`, and ``ConfigAttribute``s to the `AccessDecisionManager`.
image:{icondir}/number_5.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_6.png[] If access is granted, `FilterSecurityInterceptor` continues with the xref:servlet/architecture.adoc#servlet-filters-review[`FilterChain`], which lets the application process normally.

// configuration (xml/java)

By default, Spring Security's authorization requires all requests to be authenticated.
The following listing shows the explicit configuration:

[[servlet-authorize-requests-defaults]]
.Every Request Must be Authenticated
====
.Java
[source,java,role="primary"]
----
@Bean
public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
	http
		// ...
		.authorizeRequests(authorize -> authorize
			.anyRequest().authenticated()
		);
	return http.build();
}
----

.XML
[source,xml,role="secondary"]
----
<http>
	<!-- ... -->
	<intercept-url pattern="/**" access="authenticated"/>
</http>
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun filterChain(http: HttpSecurity): SecurityFilterChain {
    http {
        // ...
        authorizeRequests {
            authorize(anyRequest, authenticated)
        }
    }
    return http.build()
}
----
====

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
public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
	http
		// ...
		.authorizeRequests(authorize -> authorize                                  // <1>
			.requestMatchers("/resources/**", "/signup", "/about").permitAll()         // <2>
			.requestMatchers("/admin/**").hasRole("ADMIN")                             // <3>
			.requestMatchers("/db/**").access("hasRole('ADMIN') and hasRole('DBA')")   // <4>
			.anyRequest().denyAll()                                                // <5>
		);
	return http.build();
}
----

.XML
[source,xml,role="secondary"]
----
<http> <!--1-->
	<!-- ... -->
	<!--2-->
	<intercept-url pattern="/resources/**" access="permitAll"/>
	<intercept-url pattern="/signup" access="permitAll"/>
	<intercept-url pattern="/about" access="permitAll"/>

	<intercept-url pattern="/admin/**" access="hasRole('ADMIN')"/> <!--3-->
	<intercept-url pattern="/db/**" access="hasRole('ADMIN') and hasRole('DBA')"/> <!--4-->
	<intercept-url pattern="/**" access="denyAll"/> <!--5-->
</http>
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun filterChain(http: HttpSecurity): SecurityFilterChain {
   http {
        authorizeRequests { // <1>
            authorize("/resources/**", permitAll) // <2>
            authorize("/signup", permitAll)
            authorize("/about", permitAll)

            authorize("/admin/**", hasRole("ADMIN")) // <3>
            authorize("/db/**", "hasRole('ADMIN') and hasRole('DBA')") // <4>
            authorize(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.
====


[[filtersecurityinterceptor-every-request]]
== Configure FilterSecurityInterceptor with Dispatcher Types

By default, the `FilterSecurityInterceptor` applies to every request.
This means that if a request is dispatched from a request that was already filtered, the `FilterSecurityInterceptor` will perform the same authorization checks on the dispatched request.
In some scenarios, you may not want to apply authorization on some dispatcher types:

.Permit ASYNC and ERROR dispatcher types
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityFilterChain web(HttpSecurity http) throws Exception {
    http
        .authorizeRequests((authorize) -> authorize
            .dispatcherTypeMatchers(DispatcherType.ASYNC, DispatcherType.ERROR).permitAll()
            .anyRequest.authenticated()
        )
        // ...

    return http.build();
}
----
.XML
[source,xml]
----
<http auto-config="true">
    <intercept-url request-matcher-ref="dispatcherTypeMatcher" access="permitAll" />
    <intercept-url pattern="/**" access="authenticated"/>
</http>

<b:bean id="dispatcherTypeMatcher" class="org.springframework.security.web.util.matcher.DispatcherTypeRequestMatcher">
    <b:constructor-arg value="ASYNC"/>
    <b:constructor-arg value="ERROR"/>
</b:bean>
----
====