May 31, 2012

Security annotations in Spring Controller methods


There are few things you need to know for securing your controller methods using security annotations.You will need to first configure global-method-security in you context

<sec:global-method-security    secured-annotations="enabled" pre-post-annotations="enabled"/>

If you method annotations are @Secured set secured-annotations=enabled and if you plan to use @PreAuthorize or @PostAuthorize enable pre-post-annotations=enabled.

The placement of this tag is also important, you need to place this tag in your mvc-context.xml instead of security-context.xml, your mvc-context.xml is the one configured for the DispatcherServlet.

Web.xml

<context-param>
              <param-name>contextConfigLocation</param-name>
              <param-value>/WEB-INF/spring/mvc-context.xml /WEB-INF/spring/security-context.xml</param-value>
       </context-param>
<!-- Processes application requests -->
       <servlet>
              <servlet-name>appServlet</servlet-name>
              <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
              <init-param>
                     <param-name>contextConfigLocation</param-name>
                     <param-value>/WEB-INF/spring/mvc-context.xml</param-value>
              </init-param>
              <load-on-startup>1</load-on-startup>
       </servlet>


There are suggestions to place global-method-security tag after component-scan tag in your context, but I didn't think it made any difference in my case.

<context:component-scan base-package="com.ironmountain.imconnect" />
<sec:global-method-security    secured-annotations="enabled" pre-post-annotations="enabled"/>



After this, you might hit Add CGLIB to the class path exception during initialization:

Initialization of bean failed; nested exception is org.springframework.aop.framework.AopConfigException: Cannot proxy target class because CGLIB2 is not available. Add CGLIB to the class path or specify proxy interfaces.


If so, you will need to add dependency for CGLIB.

The reason you need CGLIB is that, by default, Spring uses Java Dynamic Proxies to implement Aspect Oriented Programming support. This requires you to "program to interfaces rather than classes".
But we like to leverage component-scan wiring for controllers using @Controller annotation, which means controller are concrete classes and not implementation classes.
Meaning we need to generate class level proxies for security annotated classes, which requires CGLIB dependency.

So all this got my security annotation to work for access denied scenarios, but for  success scenarios I still got this error after the method was properly executed.

No mapping found for HTTP request with URI [/imchome/app/users] in DispatcherServlet with name 'appServlet'

My controller was declared as
@Controller
@RequestMapping(value = "/users")
public class ManageUsersController implements InitializingBean
{

And I had configured Tuckey’s URLrewriting filter to clean the URL from /imchome/app/users to /imchome/users.

My Controller worked perfectly fine, if I removed the secured annotations.

After hours of debugging, I realized that the problem was that my controller was implementing InitlizingBean interface.
By implementing InitlizingBean interface my controller became an implementation class, which should be wired through interface using spring’s dynamic proxy. Since I was creating the controller using component-scan as a concerete class, it was giving problem.

My solution was to not have my controller implement InitlizingBean.

So to get the security annotation to work (Spring AOP), you either need to have an implementation class created through its interface using Spring’s dynamic proxy or have a concrete class which generates a dynamic class proxy using CGLIB. PS: even if you implement a blank interface, you will need to follow the first option.