Grant permission to single class

Question

I'm working with a security policy on Tomcat 6. I've successfully granted permissions to my entire webapp, but would like to grant some permissions only to specific classes. However, when I try this, my doPrivileged block receives an AccessControlException.

Because I've been successful granting to a more general code base, I went back to that codebase, and tested as I added each additional subdirectory. In this manner, the most specific grant I'm able to make work is:

grant codeBase "file:${catalina.home}/webapps/ROOT/WEB-INF/-" { ... }

If I add "classes/", as in:

grant codeBase "file:${catalina.home}/webapps/ROOT/WEB-INF/classes/-" { ... }

then I resume seeing the AccessControlException. The class I'm trying to allow is located beneath the classes directory. The webapp was deployed as a .war file, and unpacked by Tomcat.

What am I doing wrong here? I'm intending to follow the example provided in the catalina.policy provided with Tomcat.

Answer 1

The finest granularity for assigning permissions using the Java default policy file format is per-code source (ie, per-JAR or per-class-directory). As a workaround, you could split each distinctly privileged class into its own JAR in WEB-INF/lib and grant specific permissions to that JAR.

A custom ClassLoader could be made to create unique ProtectionDomains for each defineClass. The ProtectionDomains could either statically grant per-class permissions, or they could create specialized ProtectionDomains to allow a custom Policy to dynamically grant per-class permissions.