authorization - How to dynamically decide <intercept-url> access attribute value in Spring Security?

Question

In Spring Security we use the intercept-url tag to define the access for URLs as below:

<intercept-url pattern="/**" access="ROLE_ADMIN" />
<intercept-url pattern="/student" access="ROLE_STUDENT" />

This is hard coded in applicationContext-security.xml. I want to read the access values from a database table instead. I have defined my own UserDetailsService and I read the roles for the logged in user from the database. How do I assign these roles to the URL patterns during runtime?

Answer 1

The FilterInvocationSecurityMetadataSourceParser class in Spring-security (try Ctrl/Cmd+Shift+T in STS with the source code) parses the intercept-url tags and creates instances of ExpressionBasedFilterInvocationSecurityMetadataSource, that extends DefaultFilterInvocationSecurityMetadataSource that implements FilterInvocationSecurityMetadataSource that extends SecurityMetadataSource.

What I did is to create a custom class that implements FilterInvocationSecurityMetadataSource, OptionsFromDataBaseFilterInvocationSecurityMetadataSource. I used DefaultFilterInvocationSecurityMetadataSource as base to use urlMatcher, to implement the support() method and something like that.

Then you must to implement these methods:

• Collection getAttributes(Object object), where you can access to database, searching for the 'object' being secured (normally the URL to access) to obtain the allowed ConfigAttribute's (normally the ROLE's)

• boolean supports(Class clazz)

• Collection getAllConfigAttributes()

Be careful with the later, because it's called at startup and maybe is not well configured at this time (I mean, with the datasources or persistence context autowired, depending on what are you using). The solution in a web environment is to configure the contextConfigLocation in the web.xml to load the applicationContext.xml before the applicationContext-security.xml

The final step is to customize the applicationContext-security.xml to load this bean.

For doing that, I used regular beans in this file instead of the security namespace:

    <beans:bean id="springSecurityFilterChain" class="org.springframework.security.web.FilterChainProxy">
    <filter-chain-map path-type="ant">
        <filter-chain pattern="/images/*" filters="none" />
        <filter-chain pattern="/resources/**" filters="none" />
        <filter-chain pattern="/**" filters="
        securityContextPersistenceFilter,
        logoutFilter,
        basicAuthenticationFilter,
        exceptionTranslationFilter,
        filterSecurityInterceptor" 
    />
    </filter-chain-map>
</beans:bean>

You have to define all the related beans. For instance:

    <beans:bean id="filterSecurityInterceptor" class="org.springframework.security.web.access.intercept.FilterSecurityInterceptor">
    <beans:property name="authenticationManager" ref="authenticationManager"></beans:property>
    <beans:property name="accessDecisionManager" ref="affirmativeBased"></beans:property>
    <beans:property name="securityMetadataSource" ref="optionsFromDataBaseFilterInvocationSecurityMetadataSource"></beans:property>
    <beans:property name="validateConfigAttributes" value="true"/></beans:bean>

I know that is not a well explained answer, but it's not as difficult as it seems.

Just use the spring source as base and you will obtain what you want.

Debugging with the data in your database, will help you a lot.