From dc6f55e9f8dac4b6479be67c5c9128ad37bb491f Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 25 Oct 2011 10:25:49 +1100 Subject: [PATCH] NFS/sunrpc: don't use a credential with extra groups. The sunrpc layer keeps a cache of recently used credentials and 'unx_match' is used to find the credential which matches the current process. However unx_match allows a match when the cached credential has extra groups at the end of uc_gids list which are not in the process group list. So if a process with a list of (say) 4 group accesses a file and gains access because of the last group in the list, then another process with the same uid and gid, and a gid list being the first tree of the gids of the original process tries to access the file, it will be granted access even though it shouldn't as the wrong rpc credential will be used. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Cc: stable@vger.kernel.org --- net/sunrpc/auth_unix.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sunrpc/auth_unix.c b/net/sunrpc/auth_unix.c index 4cb70dc6e7a..e50502d8ceb 100644 --- a/net/sunrpc/auth_unix.c +++ b/net/sunrpc/auth_unix.c @@ -129,6 +129,9 @@ unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags) for (i = 0; i < groups ; i++) if (cred->uc_gids[i] != GROUP_AT(acred->group_info, i)) return 0; + if (groups < NFS_NGROUPS && + cred->uc_gids[groups] != NOGROUP) + return 0; return 1; }