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  1. 18 1月, 2010 1 次提交
  3. 30 11月, 2009 1 次提交
  5. 11 11月, 2009 1 次提交
  7. 06 11月, 2009 1 次提交
  9. 19 10月, 2009 1 次提交
    • T
      AF_UNIX: Fix deadlock on connecting to shutdown socket · 77238f2b
      由 Tomoki Sekiyama 提交于 
      I found a deadlock bug in UNIX domain socket, which makes able to DoS
attack against the local machine by non-root users.

How to reproduce:
1. Make a listening AF_UNIX/SOCK_STREAM socket with an abstruct
    namespace(*), and shutdown(2) it.
 2. Repeat connect(2)ing to the listening socket from the other sockets
    until the connection backlog is full-filled.
 3. connect(2) takes the CPU forever. If every core is taken, the
    system hangs.

PoC code: (Run as many times as cores on SMP machines.)

int main(void)
{
	int ret;
	int csd;
	int lsd;
	struct sockaddr_un sun;

	/* make an abstruct name address (*) */
	memset(&sun, 0, sizeof(sun));
	sun.sun_family = PF_UNIX;
	sprintf(&sun.sun_path[1], "%d", getpid());

	/* create the listening socket and shutdown */
	lsd = socket(AF_UNIX, SOCK_STREAM, 0);
	bind(lsd, (struct sockaddr *)&sun, sizeof(sun));
	listen(lsd, 1);
	shutdown(lsd, SHUT_RDWR);

	/* connect loop */
	alarm(15); /* forcely exit the loop after 15 sec */
	for (;;) {
		csd = socket(AF_UNIX, SOCK_STREAM, 0);
		ret = connect(csd, (struct sockaddr *)&sun, sizeof(sun));
		if (-1 == ret) {
			perror("connect()");
			break;
		}
		puts("Connection OK");
	}
	return 0;
}

(*) Make sun_path[0] = 0 to use the abstruct namespace.
    If a file-based socket is used, the system doesn't deadlock because
    of context switches in the file system layer.

Why this happens:
 Error checks between unix_socket_connect() and unix_wait_for_peer() are
 inconsistent. The former calls the latter to wait until the backlog is
 processed. Despite the latter returns without doing anything when the
 socket is shutdown, the former doesn't check the shutdown state and
 just retries calling the latter forever.

Patch:
 The patch below adds shutdown check into unix_socket_connect(), so
 connect(2) to the shutdown socket will return -ECONREFUSED.
Signed-off-by: NTomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Signed-off-by: NMasanori Yoshida <masanori.yoshida.tv@hitachi.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      77238f2b
  11. 07 10月, 2009 1 次提交
  13. 12 9月, 2009 1 次提交
    • M
      net: unix: fix sending fds in multiple buffers · 8ba69ba6
      由 Miklos Szeredi 提交于 
      Kalle Olavi Niemitalo reported that:

  "..., when one process calls sendmsg once to send 43804 bytes of
  data and one file descriptor, and another process then calls recvmsg
  three times to receive the 16032+16032+11740 bytes, each of those
  recvmsg calls returns the file descriptor in the ancillary data.  I
  confirmed this with strace.  The behaviour differs from Linux
  2.6.26, where reportedly only one of those recvmsg calls (I think
  the first one) returned the file descriptor."

This bug was introduced by a patch from me titled "net: unix: fix inflight
counting bug in garbage collector", commit 6209344f.

And the reason is, quoting Kalle:

  "Before your patch, unix_attach_fds() would set scm->fp = NULL, so
  that if the loop in unix_stream_sendmsg() ran multiple iterations,
  it could not call unix_attach_fds() again.  But now,
  unix_attach_fds() leaves scm->fp unchanged, and I think this causes
  it to be called multiple times and duplicate the same file
  descriptors to each struct sk_buff."

Fix this by introducing a flag that is cleared at the start and set
when the fds attached to the first buffer.  The resulting code should
work equivalently to the one on 2.6.26.
Reported-by: NKalle Olavi Niemitalo <kon@iki.fi>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8ba69ba6
  15. 10 7月, 2009 1 次提交
    • J
      net: adding memory barrier to the poll and receive callbacks · a57de0b4
      由 Jiri Olsa 提交于 
      Adding memory barrier after the poll_wait function, paired with
receive callbacks. Adding fuctions sock_poll_wait and sk_has_sleeper
to wrap the memory barrier.

Without the memory barrier, following race can happen.
The race fires, when following code paths meet, and the tp->rcv_nxt
and __add_wait_queue updates stay in CPU caches.

CPU1                         CPU2

sys_select                   receive packet
  ...                        ...
  __add_wait_queue           update tp->rcv_nxt
  ...                        ...
  tp->rcv_nxt check          sock_def_readable
  ...                        {
  schedule                      ...
                                if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
                                        wake_up_interruptible(sk->sk_sleep)
                                ...
                             }

If there was no cache the code would work ok, since the wait_queue and
rcv_nxt are opposit to each other.

Meaning that once tp->rcv_nxt is updated by CPU2, the CPU1 either already
passed the tp->rcv_nxt check and sleeps, or will get the new value for
tp->rcv_nxt and will return with new data mask.
In both cases the process (CPU1) is being added to the wait queue, so the
waitqueue_active (CPU2) call cannot miss and will wake up CPU1.

The bad case is when the __add_wait_queue changes done by CPU1 stay in its
cache, and so does the tp->rcv_nxt update on CPU2 side.  The CPU1 will then
endup calling schedule and sleep forever if there are no more data on the
socket.

Calls to poll_wait in following modules were ommited:
	net/bluetooth/af_bluetooth.c
	net/irda/af_irda.c
	net/irda/irnet/irnet_ppp.c
	net/mac80211/rc80211_pid_debugfs.c
	net/phonet/socket.c
	net/rds/af_rds.c
	net/rfkill/core.c
	net/sunrpc/cache.c
	net/sunrpc/rpc_pipe.c
	net/tipc/socket.c
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a57de0b4
  17. 18 6月, 2009 1 次提交
  19. 01 4月, 2009 1 次提交
  21. 27 2月, 2009 1 次提交
  23. 01 1月, 2009 1 次提交
  25. 27 11月, 2008 1 次提交
  27. 26 11月, 2008 1 次提交
  29. 24 11月, 2008 2 次提交
  31. 20 11月, 2008 2 次提交
  33. 17 11月, 2008 3 次提交
  35. 14 11月, 2008 1 次提交
  37. 10 11月, 2008 1 次提交
    • M
      net: unix: fix inflight counting bug in garbage collector · 6209344f
      由 Miklos Szeredi 提交于 
      Previously I assumed that the receive queues of candidates don't
change during the GC.  This is only half true, nothing can be received
from the queues (see comment in unix_gc()), but buffers could be added
through the other half of the socket pair, which may still have file
descriptors referring to it.

This can result in inc_inflight_move_tail() erronously increasing the
"inflight" counter for a unix socket for which dec_inflight() wasn't
previously called.  This in turn can trigger the "BUG_ON(total_refs <
inflight_refs)" in a later garbage collection run.

Fix this by only manipulating the "inflight" counter for sockets which
are candidates themselves.  Duplicating the file references in
unix_attach_fds() is also needed to prevent a socket becoming a
candidate for GC while the skb that contains it is not yet queued.
Reported-by: NAndrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6209344f
  39. 02 11月, 2008 2 次提交
  41. 23 10月, 2008 1 次提交
  43. 14 10月, 2008 1 次提交
  45. 27 7月, 2008 1 次提交
  47. 26 7月, 2008 1 次提交
  49. 28 6月, 2008 1 次提交
    • R
      af_unix: fix 'poll for write'/connected DGRAM sockets · ec0d215f
      由 Rainer Weikusat 提交于 
      For n:1 'datagram connections' (eg /dev/log), the unix_dgram_sendmsg
routine implements a form of receiver-imposed flow control by
comparing the length of the receive queue of the 'peer socket' with
the max_ack_backlog value stored in the corresponding sock structure,
either blocking the thread which caused the send-routine to be called
or returning EAGAIN. This routine is used by both SOCK_DGRAM and
SOCK_SEQPACKET sockets. The poll-implementation for these socket types
is datagram_poll from core/datagram.c. A socket is deemed to be
writeable by this routine when the memory presently consumed by
datagrams owned by it is less than the configured socket send buffer
size. This is always wrong for PF_UNIX non-stream sockets connected to
server sockets dealing with (potentially) multiple clients if the
abovementioned receive queue is currently considered to be full.
'poll' will then return, indicating that the socket is writeable, but
a subsequent write result in EAGAIN, effectively causing an (usual)
application to 'poll for writeability by repeated send request with
O_NONBLOCK set' until it has consumed its time quantum.

The change below uses a suitably modified variant of the datagram_poll
routines for both type of PF_UNIX sockets, which tests if the
recv-queue of the peer a socket is connected to is presently
considered to be 'full' as part of the 'is this socket
writeable'-checking code. The socket being polled is additionally
put onto the peer_wait wait queue associated with its peer, because the
unix_dgram_recvmsg routine does a wake up on this queue after a
datagram was received and the 'other wakeup call' is done implicitly
as part of skb destruction, meaning, a process blocked in poll
because of a full peer receive queue could otherwise sleep forever
if no datagram owned by its socket was already sitting on this queue.
Among this change is a small (inline) helper routine named
'unix_recvq_full', which consolidates the actual testing code (in three
different places) into a single location.
Signed-off-by: NRainer Weikusat <rweikusat@mssgmbh.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ec0d215f
  51. 18 6月, 2008 1 次提交
    • R
      af_unix: fix 'poll for write'/ connected DGRAM sockets · 3c73419c
      由 Rainer Weikusat 提交于 
      The unix_dgram_sendmsg routine implements a (somewhat crude)
form of receiver-imposed flow control by comparing the length of the
receive queue of the 'peer socket' with the max_ack_backlog value
stored in the corresponding sock structure, either blocking
the thread which caused the send-routine to be called or returning
EAGAIN. This routine is used by both SOCK_DGRAM and SOCK_SEQPACKET
sockets. The poll-implementation for these socket types is
datagram_poll from core/datagram.c. A socket is deemed to be writeable
by this routine when the memory presently consumed by datagrams
owned by it is less than the configured socket send buffer size. This
is always wrong for connected PF_UNIX non-stream sockets when the
abovementioned receive queue is currently considered to be full.
'poll' will then return, indicating that the socket is writeable, but
a subsequent write result in EAGAIN, effectively causing an
(usual) application to 'poll for writeability by repeated send request
with O_NONBLOCK set' until it has consumed its time quantum.

The change below uses a suitably modified variant of the datagram_poll
routines for both type of PF_UNIX sockets, which tests if the
recv-queue of the peer a socket is connected to is presently
considered to be 'full' as part of the 'is this socket
writeable'-checking code. The socket being polled is additionally
put onto the peer_wait wait queue associated with its peer, because the
unix_dgram_sendmsg routine does a wake up on this queue after a
datagram was received and the 'other wakeup call' is done implicitly
as part of skb destruction, meaning, a process blocked in poll
because of a full peer receive queue could otherwise sleep forever
if no datagram owned by its socket was already sitting on this queue.
Among this change is a small (inline) helper routine named
'unix_recvq_full', which consolidates the actual testing code (in three
different places) into a single location.
Signed-off-by: NRainer Weikusat <rweikusat@mssgmbh.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3c73419c
  53. 12 6月, 2008 1 次提交
  55. 24 4月, 2008 1 次提交
  57. 19 4月, 2008 1 次提交
  59. 13 4月, 2008 1 次提交
  61. 26 3月, 2008 3 次提交
  63. 06 3月, 2008 1 次提交
  65. 15 2月, 2008 1 次提交