Re: [PATCH 2/2] KEYS: Add per-user_namespace registers for persistentper-UID kerberos caches

From: Daniel Kahn Gillmor
Date: Thu Aug 01 2013 - 14:01:29 EST

On 08/01/2013 01:39 PM, David Howells wrote:
> The uid is -1 or the user's own UID for the user's own cache or the uid of some
> other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to
> mess with the cache.

Is the goal here eventually to be able to avoid the upcall to rpc.gssd
entirely? It seems a little bit roundabout to have the kernel call up
into userspace for the credentials, only to talk to a process which then
calls back into the kernel for something that the kernel has already
well-defined internally.

It seems like a non-privileged user could use this to store arbitrary
data in this keyring as a way of hiding what would otherwise be
filesystem activity or using it for some sort of odd/sneaky IPC
mechanism. Is this an intentional side effect?

Sorry if these are obvious questions. feel free to point me to
already-documented answers if they exist.

Thanks for all your work on this!



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