nfsd: fix krb5 handling of anonymous principals

krb5 mounts started failing as of
683428fae8c73d7d7da0fa2e0b6beb4d8df4e808 "sunrpc: Update svcgss xdr
handle to rpsec_contect cache".

The problem is that mounts are usually done with some host principal
which isn't normally mapped to any user, in which case svcgssd passes
down uid -1, which the kernel is then expected to map to the
export-specific anonymous uid or gid.

The new uid_valid/gid_valid checks were therefore causing that downcall
to fail.

(Note the regression may not have been seen with older userspace that
tended to map unknown principals to an anonymous id on their own rather
than leaving it to the kernel.)

Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
sunrpc: don't attempt to cancel unitialized work

As of dc107402ae06286a9ed33c32daf3f35514a7cb8d "SUNRPC: make AF_LOCAL connect synchronous", we no longer initialize connect_worker in the
AF_LOCAL case, resulting in warnings like:

    WARNING: at lib/debugobjects.c:261 debug_print_object+0x8c/0xb0() Hardware name: Bochs
    ODEBUG: assert_init not available (active state 0) object type: timer_list hint: stub_timer+0x0/0x20
    Modules linked in: iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi nfsd auth_rpcgss nfs_acl lockd sunrpc
    Pid: 4816, comm: nfsd Tainted: G        W    3.8.0-rc2-00049-gdc10740 #801
    Call Trace:
     [<ffffffff8156ec00>] ? free_obj_work+0x60/0xa0
     [<ffffffff81046aaf>] warn_slowpath_common+0x7f/0xc0
     [<ffffffff81046ba6>] warn_slowpath_fmt+0x46/0x50
     [<ffffffff8156eccc>] debug_print_object+0x8c/0xb0
     [<ffffffff81055030>] ? timer_debug_hint+0x10/0x10
     [<ffffffff8156f7e3>] debug_object_assert_init+0xe3/0x120
     [<ffffffff81057ebb>] del_timer+0x2b/0x80
     [<ffffffff8109c4e6>] ? mark_held_locks+0x86/0x110
     [<ffffffff81065a29>] try_to_grab_pending+0xd9/0x150
     [<ffffffff81065b57>] __cancel_work_timer+0x27/0xc0
     [<ffffffff81065c03>] cancel_delayed_work_sync+0x13/0x20
     [<ffffffffa0007067>] xs_destroy+0x27/0x80 [sunrpc]
     [<ffffffffa00040d8>] xprt_destroy+0x78/0xa0 [sunrpc]
     [<ffffffffa0006241>] xprt_put+0x21/0x30 [sunrpc]
     [<ffffffffa00030cf>] rpc_free_client+0x10f/0x1a0 [sunrpc]
     [<ffffffffa0002ff3>] ? rpc_free_client+0x33/0x1a0 [sunrpc]
     [<ffffffffa0002f7e>] rpc_release_client+0x6e/0xb0 [sunrpc]
     [<ffffffffa000325d>] rpc_shutdown_client+0xfd/0x1b0 [sunrpc]
     [<ffffffffa0017196>] rpcb_put_local+0x106/0x130 [sunrpc]
    ...

Acked-by: "Myklebust, Trond" <Trond.Myklebust@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
libceph: fix decoding of pgids

In 4f6a7e5ee1393ec4b243b39dac9f36992d161540 we effectively dropped support
for the legacy encoding for the OSDMap and incremental.  However, we didn't
fix the decoding for the pgid.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
keys: fix race with concurrent install_user_keyrings()

This fixes CVE-2013-1792.

There is a race in install_user_keyrings() that can cause a NULL pointer
dereference when called concurrently for the same user if the uid and
uid-session keyrings are not yet created.  It might be possible for an
unprivileged user to trigger this by calling keyctl() from userspace in
parallel immediately after logging in.

Assume that we have two threads both executing lookup_user_key(), both
looking for KEY_SPEC_USER_SESSION_KEYRING.

	THREAD A			THREAD B
	===============================	===============================
					==>call install_user_keyrings();
	if (!cred->user->session_keyring)
	==>call install_user_keyrings()
					...
					user->uid_keyring = uid_keyring;
	if (user->uid_keyring)
		return 0;
	<==
	key = cred->user->session_keyring [== NULL]
					user->session_keyring = session_keyring;
	atomic_inc(&key->usage); [oops]

At the point thread A dereferences cred->user->session_keyring, thread B
hasn't updated user->session_keyring yet, but thread A assumes it is
populated because install_user_keyrings() returned ok.

The race window is really small but can be exploited if, for example,
thread B is interrupted or preempted after initializing uid_keyring, but
before doing setting session_keyring.

This couldn't be reproduced on a stock kernel.  However, after placing
systemtap probe on 'user->session_keyring = session_keyring;' that
introduced some delay, the kernel could be crashed reliably.

Fix this by checking both pointers before deciding whether to return.
Alternatively, the test could be done away with entirely as it is checked
inside the mutex - but since the mutex is global, that may not be the best
way.

Signed-off-by: David Howells <dhowells@redhat.com>
Reported-by: Mateusz Guzik <mguzik@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
vfs: fix pipe counter breakage

If you open a pipe for neither read nor write, the pipe code will not
add any usage counters to the pipe, causing the 'struct pipe_inode_info"
to be potentially released early.

That doesn't normally matter, since you cannot actually use the pipe,
but the pipe release code - particularly fasync handling - still expects
the actual pipe infrastructure to all be there.  And rather than adding
NULL pointer checks, let's just disallow this case, the same way we
already do for the named pipe ("fifo") case.

This is ancient going back to pre-2.4 days, and until trinity, nobody
naver noticed.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge branch 'for-3.9' of git://linux-nfs.org/~bfields/linux

Pull nfsd bugfixes from Bruce Fields:
 "Some minor fallout from the user-namespace work broke most krb5 mounts
  to nfsd, and I screwed up a change to the AF_LOCAL rpc code."

* 'for-3.9' of git://linux-nfs.org/~bfields/linux:
  sunrpc: don't attempt to cancel unitialized work
  nfsd: fix krb5 handling of anonymous principals
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

Pull Ceph fix from Sage Weil:
 "This fixes a bug in the new message decoding that just went in during
  the last window."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  libceph: fix decoding of pgids
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull key management race fix from James Morris.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  keys: fix race with concurrent install_user_keyrings()