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Follow up on Servlet 3.0 Security Annotations

Thursday Oct 29, 2009

In May 2009, I discussed the Servlet 3.0 security annotations in one of my blogs, Servlet 3.0 Security Annotations. At that time, the annotations were defined similar to those in EJB. During the discussion in JSR 315 expert group, two issues were identified as follows:

In JSR 250, type level annotations only apply to methods declared in that class, not those inherited. This is an issue for servlets as they extend javax.servlet.http.HttpServlet.
The doGet method et al may not correspond to http method GET et al as the logic can be overrided in service method of the servlet.

Thanks to Ronald Monzilo for discussions in Servlet 3.0 security. The following is the update on Servlet 3.0 security annotations:

As in servlet 2.5, @DenyAll, @PermitAll, @RolesAllowed will not apply to servlets. @TransportProtected will not be added to JSR 250.
The following new annotations will be added to javax.servlet.annotation:
- ServletSecurity
- HttpConstraint
- HttpMethodConstraint
Note that @ServletSecurity is a type level annotation and the rests are used as parameters in @ServletSecurity.
With the above new annotations, one can resolve the issue mentioned above. In addition, it covers the new use case where one want to have security constraint for extended http methods only, for instance FOO.

In this blog, I will illustrate how those annotation work. For convenient of readers of my previous blogs, I will first illustrate the four scenarios mentioned in my previous blog, Servlet 3.0 Security Annotations with the new annotations. Then I have an additional example.

Example 1: For all Http Methods

@WebServlet("/myurl")
@ServletSecurity(@HttpConstraint(rolesAllowed={"javaee"}))
public class TestServlet extends HttpServlet {
...
}

In this case, all http methods are protected and accessible only by users with role javaee.

Example 2: Http Method Level

@WebServlet("/myurl")
@ServletSecurity(httpMethodConstraints={ @HttpMethodConstraint("GET"),
    @HttpMethodConstraint(value="POST", rolesAllowed={"javaee"}),
    @HttpMethodConstraint(value="TRACE", emptyRoleSemantic=ServletSecurity.EmptyRoleSemantic.DENY) })
public class TestServlet extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException {
        ...
    }

    protected void doPost(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException {
        ...
    }

    protected void doTrace(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException {
        ...
    }
}

The behaviors of the above servlet can be summarized as follows:

Http method Behavior
GET all can access GET method
POST only authenticated users with role javaee can access POST method
TRACE no one can access TRACE method

Http method	Behavior
GET	all can access GET method
POST	only authenticated users with role javaee can access POST method
TRACE	no one can access TRACE method

Example 3: A General Constraint for all Http methods with some Exceptional Cases

@WebServlet("/myurl")
@ServletSecurity(value=@HttpConstraint(rolesAllowed={"javaee"}),
    httpMethodConstraints={ @HttpMethodConstraint(value="POST", rolesAllowed={"staff"}),
    @HttpMethodConstraint("TRACE") })
public class TestServlet extends HttpServlet {
    ...

    protected void doPost(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException {
        ...
    }

    protected void doTrace(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException {
        ...
    }
}

The behaviors of the above servlet can be summarized as follows:

Http method Behavior
POST only authenticated users with role staff can access POST method
TRACE all can access TRACE method
methods other than POST and TRACE only authenticated users with role javaee can access
Note that in the previous definitions, the exceptional cases must be the standard http methods. There is no such restriction for the new annotations as illustrated by the Example 5 below.

Http method	Behavior
POST	only authenticated users with role staff can access POST method
TRACE	all can access TRACE method
methods other than POST and TRACE	only authenticated users with role javaee can access

Example 4: Https and protected for a given role

@WebServlet("/myurl")
@ServletSecurity(value=@HttpConstraint(
    transportGuarantee=ServletSecurity.TransportGuarantee.CONFIDENTIAL),
    httpMethodConstraints={ @HttpMethodConstraint(value="TRACE", transportGuarantee=ServletSecurity.TransportGuarantee.NONE, rolesAllowed={"javaee"}) })
public class TestServlet extends HttpServlet {
    ...

    protected void doTrace(HttpServletRequest req, HttpServletResponse res)
        throws IOException, ServletException {

        ...
    }
}

The behaviors of the above servlet can be summarized as follows:

Http method Behavior
TRACE Https is supported. It just is not required. Only authenticated users with role javaee can access TRACE method
methods other than TRACE require https

Http method	Behavior
TRACE	Https is supported. It just is not required. Only authenticated users with role javaee can access TRACE method
methods other than TRACE	require https

Example 5: Protect FOO only

@WebServlet("/myurl")
@ServletSecurity(value=@HttpConstraint,
httpMethodConstraints={ @HttpMethodConstraint(value="FOO", rolesAllowed={"javaee"}) })
public class TestServlet extends HttpServlet {
...
}

The behaviors of the above servlet can be summarized as follows:

Http method Behavior
FOO only authenticated users with role staff can access POST method
methods other than FOO all can access