Authorize HttpServletRequest with FilterSecurityInterceptor

This section builds on Servlet Architecture and Implementation by digging deeper into how authorization works within Servlet based applications.

The FilterSecurityInterceptor provides authorization for HttpServletRequests. It is inserted into the FilterChainProxy as one of the Security Filters.

Figure 1. Authorize HttpServletRequest

First, the FilterSecurityInterceptor obtains an Authentication from the SecurityContextHolder.
Second, FilterSecurityInterceptor creates a FilterInvocation from the HttpServletRequest, HttpServletResponse, and FilterChain that are passed into the FilterSecurityInterceptor.
Next, it passes the FilterInvocation to SecurityMetadataSource to get the ConfigAttributes.
Finally, it passes the Authentication, FilterInvocation, and ConfigAttributes to the AccessDecisionManager.
- If authorization is denied, an AccessDeniedException is thrown. In this case the ExceptionTranslationFilter handles the AccessDeniedException.
- If access is granted, FilterSecurityInterceptor continues with the FilterChain which allows the application to process normally.

By default, Spring Security’s authorization will require all requests to be authenticated. The explicit configuration looks like:

Example 1. Every Request Must be Authenticated

Java

protected void configure(HttpSecurity http) throws Exception {
	http
		// ...
		.authorizeRequests(authorize -> authorize
			.anyRequest().authenticated()
		);
}

XML

<http>
	<!-- ... -->
	<intercept-url pattern="/**" access="authenticated"/>
</http>

Kotlin

fun configure(http: HttpSecurity) {
    http {
        // ...
        authorizeRequests {
            authorize(anyRequest, authenticated)
        }
    }
}

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

Example 2. Authorize Requests

Java

protected void configure(HttpSecurity http) throws Exception {
	http
		// ...
		.authorizeRequests(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)
		);
}

XML

<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

fun configure(http: HttpSecurity) {
   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)
        }
    }
}

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.