Difficulties loading custom security Policy object.....

Question

I just finished reading the white paper entitled �When java.policy Just Isn�t Good Enough� and I found a lot of good information for creating my own extension of java.security.Policy. I�m having a difficult time figuring out how to (best) load the policy, and I�ll explain why, but first I�d like to make sure that I�m extending the Policy class correctly. Don�t worry, I�ll be as brief as possible. My class looks something like this with a few more permissions than what i've included here (for brevity):
public class MyPolicy extends Policy {
            private static MyPolicy INSTANCE = new MyPolicy();
            private PermissionCollection perms = new Permissions();
            private MyPolicy() {
                        constructPerms();
            public static MyPolicy getInstance() {
                        return INSTANCE;
            public PermissionCollection getPermissions(CodeSource arg0) {
                        return perms;
            public void refresh() {
                        // permissions won't change, so nothing necessary here!
            public void constructPerms() {
                        // I�m adding other permissions, but here are a few basic ones just for the idea:
                        perms.add(new PropertyPermission("java.version", "read"));
                        perms.add(new PropertyPermission("java.vendor", "read"));
                        perms.add(new PropertyPermission("java.vendor.url", "read"));
}I have this class in a package that will reside inside of a jar on the target machine. The jar will be wrapped in an executable, and we�ll be distributing a JRE directory that will reside in the same (installation) directory as the executable. I�m not sure how to specify this as my Policy implementation on startup of the JVM. For security reasons, I want to rely as little as possible on security stuff outside of my exe-wrapped-jarfile. I can pass whatever parameters I want to the JVM, including �Xbootclasspath, but I�m not sure what I need to get things working this way.
I tried another approach. I don�t really like it, but I just wanted to try it this way to test my Policy implementation. I edited my java.policy file to look like this:
grant {
            // Custom permissions to allow app to load
            // and then set MyPolicy as Policy object:
            permission java.security.SecurityPermission "getPolicy";
            permission java.security.SecurityPermission "setPolicy";
            permission java.util.PropertyPermission "stuff.*", "read,write";
};And then in my main() method, I loaded it like this:
Policy myPolicy = MyPolicy.getInstance();
Policy.setPolicy(myPolicy);But that doesn�t seem to work because I�m getting an AccessControlException: access denied (java.awt.AWTPermission replaceKeyboardFocusManager)
Even though I have this permission in my implementation:
perms.add(new AWTPermission("replaceKeyboardFocusManager"));Do you have any ideas what I�m doing wrong, or how I could fix them? Any information would be greatly appreciated. Thanks in advance!
Steve

Answer 1

Hey
I have just finished such a policy implemention - boy could I have done with your help!
I've never seen the java.security.debug property before - not to say it doesn't exist, but don't confuse system properties and security properties. Try setting it programmatically via Security.setProperty() or the Java Admin console [if you can], or even in the JRE WebStart uses via the java.security file.
When you run it locally with security switched on, do you observe the 3-to-1 behaviour also? I'm not sure if this is important - depends on your answer. As for the checks being performed from the same stack frame, the AC iterates over the protection domains as it checks them; the 3-to-1 behaviour is the result of there being 3 extra frames to check, possibly due to the fact your executing from JWS [although I'd expect JWS to be considered system code]. If the execution in AC gets to return null; then Debug.isOn("failure") must evaluate to true [...I'd slump in my chair at this point] but there's no way to figure out accurately what the semantics of this is AS THERE'S NO FRICKIN SRC AVAILABLE [...this really annoys me]. The only thing I can suggest for that is to not try and switch debugging on.
I suspect you are using JAAS [hence the dynamic policy need]? I have an idea if you are.
I totally know what you mean about the sleepless nights mate - I'm glad I done it all now, learnt all about security within Java which I knew nothing about 6 months ago.
Warm regads,
D