linux-kernel - [224/262] NFS/sunrpc: dont use a credential with extra groups.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20111109212723.118204274@clark.kroah.org>
Date:	Wed, 09 Nov 2011 13:29:06 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, NeilBrown <neilb@...e.de>,
	Trond Myklebust <Trond.Myklebust@...app.com>
Subject: [224/262] NFS/sunrpc: dont use a credential with extra groups.

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@...e.de>

commit dc6f55e9f8dac4b6479be67c5c9128ad37bb491f upstream.

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 <neilb@...e.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 net/sunrpc/auth_unix.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/sunrpc/auth_unix.c
+++ b/net/sunrpc/auth_unix.c
@@ -129,6 +129,9 @@ unx_match(struct auth_cred *acred, struc
 	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;
 }

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/