linux/net/unix, branch v3.4.69

net: unix: inherit SOCK_PASS{CRED, SEC} flags from socket to fix race

2013-11-04T12:23:41Z

[ Upstream commit 90c6bd34f884cd9cee21f1d152baf6c18bcac949 ] In the case of credentials passing in unix stream sockets (dgram sockets seem not affected), we get a rather sparse race after commit 16e5726 ("af_unix: dont send SCM_CREDENTIALS by default"). We have a stream server on receiver side that requests credential passing from senders (e.g. nc -U). Since we need to set SO_PASSCRED on each spawned/accepted socket on server side to 1 first (as it's not inherited), it can happen that in the time between accept() and setsockopt() we get interrupted, the sender is being scheduled and continues with passing data to our receiver. At that time SO_PASSCRED is neither set on sender nor receiver side, hence in cmsg's SCM_CREDENTIALS we get eventually pid:0, uid:65534, gid:65534 (== overflow{u,g}id) instead of what we actually would like to see. On the sender side, here nc -U, the tests in maybe_add_creds() invoked through unix_stream_sendmsg() would fail, as at that exact time, as mentioned, the sender has neither SO_PASSCRED on his side nor sees it on the server side, and we have a valid 'other' socket in place. Thus, sender believes it would just look like a normal connection, not needing/requesting SO_PASSCRED at that time. As reverting 16e5726 would not be an option due to the significant performance regression reported when having creds always passed, one way/trade-off to prevent that would be to set SO_PASSCRED on the listener socket and allow inheriting these flags to the spawned socket on server side in accept(). It seems also logical to do so if we'd tell the listener socket to pass those flags onwards, and would fix the race. Before, strace: recvmsg(4, {msg_name(0)=NULL, msg_iov(1)=[{"blub\n", 4096}], msg_controllen=32, {cmsg_len=28, cmsg_level=SOL_SOCKET, cmsg_type=SCM_CREDENTIALS{pid=0, uid=65534, gid=65534}}, msg_flags=0}, 0) = 5 After, strace: recvmsg(4, {msg_name(0)=NULL, msg_iov(1)=[{"blub\n", 4096}], msg_controllen=32, {cmsg_len=28, cmsg_level=SOL_SOCKET, cmsg_type=SCM_CREDENTIALS{pid=11580, uid=1000, gid=1000}}, msg_flags=0}, 0) = 5 Signed-off-by: Daniel Borkmann Cc: Eric Dumazet Cc: Eric W. Biederman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

unix_diag: fix info leak

2013-11-04T12:23:41Z

[ Upstream commit 6865d1e834be84ddd5808d93d5035b492346c64a ] When filling the netlink message we miss to wipe the pad field, therefore leak one byte of heap memory to userland. Fix this by setting pad to 0. Signed-off-by: Mathias Krause Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

af_unix: If we don't care about credentials coallesce all messages

2013-05-01T16:41:07Z

[ Upstream commit 0e82e7f6dfeec1013339612f74abc2cdd29d43d2 ] It was reported that the following LSB test case failed https://lsbbugs.linuxfoundation.org/attachment.cgi?id=2144 because we were not coallescing unix stream messages when the application was expecting us to. The problem was that the first send was before the socket was accepted and thus sock->sk_socket was NULL in maybe_add_creds, and the second send after the socket was accepted had a non-NULL value for sk->socket and thus we could tell the credentials were not needed so we did not bother. The unnecessary credentials on the first message cause unix_stream_recvmsg to start verifying that all messages had the same credentials before coallescing and then the coallescing failed because the second message had no credentials. Ignoring credentials when we don't care in unix_stream_recvmsg fixes a long standing pessimization which would fail to coallesce messages when reading from a unix stream socket if the senders were different even if we did not care about their credentials. I have tested this and verified that the in the LSB test case mentioned above that the messages do coallesce now, while the were failing to coallesce without this change. Reported-by: Karel Srot Reported-by: Ding Tianhong Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

unix: fix a race condition in unix_release()

2013-04-05T17:04:39Z

[ Upstream commit ded34e0fe8fe8c2d595bfa30626654e4b87621e0 ] As reported by Jan, and others over the past few years, there is a race condition caused by unix_release setting the sock->sk pointer to NULL before properly marking the socket as dead/orphaned. This can cause a problem with the LSM hook security_unix_may_send() if there is another socket attempting to write to this partially released socket in between when sock->sk is set to NULL and it is marked as dead/orphaned. This patch fixes this by only setting sock->sk to NULL after the socket has been marked as dead; I also take the opportunity to make unix_release_sock() a void function as it only ever returned 0/success. Dave, I think this one should go on the -stable pile. Special thanks to Jan for coming up with a reproducer for this problem. Reported-by: Jan Stancek Signed-off-by: Paul Moore Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

af_netlink: force credentials passing [CVE-2012-3520]

2012-10-02T17:29:37Z

[ Upstream commit e0e3cea46d31d23dc40df0a49a7a2c04fe8edfea ] Pablo Neira Ayuso discovered that avahi and potentially NetworkManager accept spoofed Netlink messages because of a kernel bug. The kernel passes all-zero SCM_CREDENTIALS ancillary data to the receiver if the sender did not provide such data, instead of not including any such data at all or including the correct data from the peer (as it is the case with AF_UNIX). This bug was introduced in commit 16e572626961 (af_unix: dont send SCM_CREDENTIALS by default) This patch forces passing credentials for netlink, as before the regression. Another fix would be to not add SCM_CREDENTIALS in netlink messages if not provided by the sender, but it might break some programs. With help from Florian Weimer & Petr Matousek This issue is designated as CVE-2012-3520 Signed-off-by: Eric Dumazet Cc: Petr Matousek Cc: Florian Weimer Cc: Pablo Neira Ayuso Signed-off-by: David S. Miller

poll: add poll_requested_events() and poll_does_not_wait() functions

2012-03-23T23:58:38Z

In some cases the poll() implementation in a driver has to do different things depending on the events the caller wants to poll for. An example is when a driver needs to start a DMA engine if the caller polls for POLLIN, but doesn't want to do that if POLLIN is not requested but instead only POLLOUT or POLLPRI is requested. This is something that can happen in the video4linux subsystem among others. Unfortunately, the current epoll/poll/select implementation doesn't provide that information reliably. The poll_table_struct does have it: it has a key field with the event mask. But once a poll() call matches one or more bits of that mask any following poll() calls are passed a NULL poll_table pointer. Also, the eventpoll implementation always left the key field at ~0 instead of using the requested events mask. This was changed in eventpoll.c so the key field now contains the actual events that should be polled for as set by the caller. The solution to the NULL poll_table pointer is to set the qproc field to NULL in poll_table once poll() matches the events, not the poll_table pointer itself. That way drivers can obtain the mask through a new poll_requested_events inline. The poll_table_struct can still be NULL since some kernel code calls it internally (netfs_state_poll() in ./drivers/staging/pohmelfs/netfs.h). In that case poll_requested_events() returns ~0 (i.e. all events). Very rarely drivers might want to know whether poll_wait will actually wait. If another earlier file descriptor in the set already matched the events the caller wanted to wait for, then the kernel will return from the select() call without waiting. This might be useful information in order to avoid doing expensive work. A new helper function poll_does_not_wait() is added that drivers can use to detect this situation. This is now used in sock_poll_wait() in include/net/sock.h. This was the only place in the kernel that needed this information. Drivers should no longer access any of the poll_table internals, but use the poll_requested_events() and poll_does_not_wait() access functions instead. In order to enforce that the poll_table fields are now prepended with an underscore and a comment was added warning against using them directly. This required a change in unix_dgram_poll() in unix/af_unix.c which used the key field to get the requested events. It's been replaced by a call to poll_requested_events(). For qproc it was especially important to change its name since the behavior of that field changes with this patch since this function pointer can now be NULL when that wasn't possible in the past. Any driver accessing the qproc or key fields directly will now fail to compile. Some notes regarding the correctness of this patch: the driver's poll() function is called with a 'struct poll_table_struct *wait' argument. This pointer may or may not be NULL, drivers can never rely on it being one or the other as that depends on whether or not an earlier file descriptor in the select()'s fdset matched the requested events. There are only three things a driver can do with the wait argument: 1) obtain the key field: events = wait ? wait->key : ~0; This will still work although it should be replaced with the new poll_requested_events() function (which does exactly the same). This will now even work better, since wait is no longer set to NULL unnecessarily. 2) use the qproc callback. This could be deadly since qproc can now be NULL. Renaming qproc should prevent this from happening. There are no kernel drivers that actually access this callback directly, BTW. 3) test whether wait == NULL to determine whether poll would return without waiting. This is no longer sufficient as the correct test is now wait == NULL || wait->_qproc == NULL. However, the worst that can happen here is a slight performance hit in the case where wait != NULL and wait->_qproc == NULL. In that case the driver will assume that poll_wait() will actually add the fd to the set of waiting file descriptors. Of course, poll_wait() will not do that since it tests for wait->_qproc. This will not break anything, though. There is only one place in the whole kernel where this happens (sock_poll_wait() in include/net/sock.h) and that code will be replaced by a call to poll_does_not_wait() in the next patch. Note that even if wait->_qproc != NULL drivers cannot rely on poll_wait() actually waiting. The next file descriptor from the set might match the event mask and thus any possible waits will never happen. Signed-off-by: Hans Verkuil Reviewed-by: Jonathan Corbet Reviewed-by: Al Viro Cc: Davide Libenzi Signed-off-by: Hans de Goede Cc: Mauro Carvalho Chehab Cc: David Miller Cc: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2012-03-21T20:36:41Z

Pull vfs pile 1 from Al Viro: "This is _not_ all; in particular, Miklos' and Jan's stuff is not there yet." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits) ext4: initialization of ext4_li_mtx needs to be done earlier debugfs-related mode_t whack-a-mole hfsplus: add an ioctl to bless files hfsplus: change finder_info to u32 hfsplus: initialise userflags qnx4: new helper - try_extent() qnx4: get rid of qnx4_bread/qnx4_getblk take removal of PF_FORKNOEXEC to flush_old_exec() trim includes in inode.c um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it um: embed ->stub_pages[] into mmu_context gadgetfs: list_for_each_safe() misuse ocfs2: fix leaks on failure exits in module_init ecryptfs: make register_filesystem() the last potential failure exit ntfs: forgets to unregister sysctls on register_filesystem() failure logfs: missing cleanup on register_filesystem() failure jfs: mising cleanup on register_filesystem() failure make configfs_pin_fs() return root dentry on success configfs: configfs_create_dir() has parent dentry in dentry->d_parent configfs: sanitize configfs_create() ...

switch touch_atime to struct path

2012-03-21T01:29:41Z

Signed-off-by: Al Viro

switch unix_sock to struct path

2012-03-21T01:29:41Z

Signed-off-by: Al Viro

netlink: add netlink_dump_control structure for netlink_dump_start()

2012-02-26T19:10:06Z

Davem considers that the argument list of this interface is getting out of control. This patch tries to address this issue following his proposal: struct netlink_dump_control c = { .dump = dump, .done = done, ... }; netlink_dump_start(..., &c); Suggested by David S. Miller. Signed-off-by: Pablo Neira Ayuso Signed-off-by: David S. Miller