The new security manager and policies are almost ready to merge back into trunk.
Any svn merge tips would be much appreciated. First, I'd like to move some policy implementation classes that are at present public in org.apache.river.*, into package private net.jini.* namespaces, to reduce the public api. Not all of the code will be included, classes, like ConcurrentPermissions (and all policy cache associated classes), even though far better than Permissions, will be discarded, as recent developments (eliminating policy cache) have made them redundant. DelegatePermission is still there, designed to work with delegate wrapper classes that encapsulate sockets and and file handles, to enable removal of temporarily granted permissions. Example: A downloaded proxy is granted a SocketPermission to contact its server, if during deserialisation, the proxy modifies some public static fields (java.xml.* vulnerabilities ring a bell?) by replacing some platform classes with its own, it leaves some of its own proxy code on the stack context. The proxy after being downloaded is found to be untrusted and discarded. Every time the object the proxy has injected into the platform is accessed, it steals information and sends it back to its originating host. If a DelegatePermission(SocketPermission p) is granted instead, the proxy recieves a socket that denies access when the permission is revoked, when trust can't be verified. The proxy could still perform a denial of service, by causing an out of memory error during deserialisation. DelegatePermission can also be used to grant temporary or limited access to Principals, eg after downloading 1GB, downloads are revoked and regranted at the next monthly cycle, something sililar could be used to limit writes to the file system. Obviously you'll need to buffer the input or output streams, to balance how often checks are performed, that is, if you choose to utilise it. A DelegateSocketFactory that can be used to encapsulate existing SocketFactory's will be released at a later date to enable DelegatePermission controlled streams and channels. Note any ProtectionDomains with SocketPermission will still have access to the same channel. DelegatePermission is intended to be a dynamically or runtime granted Permission. To function it requires a DelegateSecurityManager, each stack context domain must have permission either for the DelegatePermission or it's representative Permission. This was one motivation for a securitymanager cache, it needed to be as fast as possible and non blocking, unlike policy cache. Using delegates is of course optional. The other thing I was toying with was using deny as well as grant in policy files: Where denials would be checked first by the policy prior to checking grants: So you could deny a proxy access to the local network, whilst granting it access to the entire internet, with two simple policy statements. Or you could allow access to a directory, but deny access to a user policy file contained in that directory, for principal based grants. The syntax would be identical to a grant statement in policy files, except deny replaces grant. But then I realised despite the advantages, it adds complexity, because the deny statement could have unintended scope narrowing / widening consequences and Permissions like SocketPermission don't work as well as intended, it would be simpler to dynamically grant Permissions on an as needed basis. So any last remaining traces of deny must be removed. Instead of using deny in policy grants, I figure that proxy's can optionally include permissions.perms files under META-INF in their jar files as a hint to clients. By using the least priviledge model and limiting the GrantPermissions given to Principals administrators can limit Permissions users can grant to proxy's. The proxy developers would need to be aware they might not be granted all the permissions they'd like and offer reduced functionality by catching SecurityException. Regards, Peter.
