tree 697e247a7a99c81af7ba4d7ad5d9cdf9941b3741
parent 38bbca6b6f164e08a4a9cdfd719fff679af98375
author Kevin Coffman <kwc@citi.umich.edu> 1209456082 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1209481576 -0700

keys: check starting keyring as part of search

Check the starting keyring as part of the search to (a) see if that is what
we're searching for, and (b) to check it is still valid for searching.

The scenario: User in process A does things that cause things to be created in
its process session keyring.  The user then does an su to another user and
starts a new process, B.  The two processes now share the same process session
keyring.

Process B does an NFS access which results in an upcall to gssd.  When gssd
attempts to instantiate the context key (to be linked into the process session
keyring), it is denied access even though it has an authorization key.

The order of calls is:

   keyctl_instantiate_key()
      lookup_user_key()				    (the default: case)
         search_process_keyrings(current)
	    search_process_keyrings(rka->context)   (recursive call)
	       keyring_search_aux()

keyring_search_aux() verifies the keys and keyrings underneath the top-level
keyring it is given, but that top-level keyring is neither fully validated nor
checked to see if it is the thing being searched for.

This patch changes keyring_search_aux() to:
1) do more validation on the top keyring it is given and
2) check whether that top-level keyring is the thing being searched for

Signed-off-by: Kevin Coffman <kwc@citi.umich.edu>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Paul Moore <paul.moore@hp.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Kevin Coffman <kwc@citi.umich.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>