Security decisions from the past: to cache or not to cache

We haven’t been abducted, yet. While working on an interesting research project, we found something about Apple’s Kernel Authorization framework that might be a bit odd. From their documentation:

When writing a vnode scope listener, be aware that not every file system operation will trigger an authorization request. For example, if an actor successfully requests KAUTH_VNODE_SEARCH on a directory, the system may cache that result and grant future requests without invoking your listener for each one.

Albeit we haven’t verified this any further, it’s at very least interesting. Does that mean that a security decision might be cached and applied again under potentially circumstances? Huh. It’s true that a vnode scope listener can be one hell of a performance black-hole, but race conditions due to cached decisions is worse than slowing down file system operations, especially if the module overrides other policies.