path: root/net/unix
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2017-06-09af_unix: Add sockaddr length checks before accessing sa_family in bind and ↵Mateusz Jurczyk-1/+6
connect handlers Verify that the caller-provided sockaddr structure is large enough to contain the sa_family field, before accessing it in bind() and connect() handlers of the AF_UNIX socket. Since neither syscall enforces a minimum size of the corresponding memory region, very short sockaddrs (zero or one byte long) result in operating on uninitialized memory while referencing .sa_family. Signed-off-by: Mateusz Jurczyk <> Signed-off-by: David S. Miller <>
2017-04-06af_unix: Use designated initializersKees Cook-1/+1
Prepare to mark sensitive kernel structures for randomization by making sure they're using designated initializers. These were identified during allyesconfig builds of x86, arm, and arm64, and the initializer fixes were extracted from grsecurity. In this case, NULL initialize with { } instead of undesignated NULLs. Signed-off-by: Kees Cook <> Signed-off-by: David S. Miller <>
2017-03-21net: unix: properly re-increment inflight counter of GC discarded candidatesAndrey Ulanov-8/+9
Dmitry has reported that a BUG_ON() condition in unix_notinflight() may be triggered by a simple code that forwards unix socket in an SCM_RIGHTS message. That is caused by incorrect unix socket GC implementation in unix_gc(). The GC first collects list of candidates, then (a) decrements their "children's" inflight counter, (b) checks which inflight counters are now 0, and then (c) increments all inflight counters back. (a) and (c) are done by calling scan_children() with inc_inflight or dec_inflight as the second argument. Commit 6209344f5a37 ("net: unix: fix inflight counting bug in garbage collector") changed scan_children() such that it no longer considers sockets that do not have UNIX_GC_CANDIDATE flag. It also added a block of code that that unsets this flag _before_ invoking scan_children(, dec_iflight, ). This may lead to incorrect inflight counters for some sockets. This change fixes this bug by changing order of operations: UNIX_GC_CANDIDATE is now unset only after all inflight counters are restored to the original state. kernel BUG at net/unix/garbage.c:149! RIP: 0010:[<ffffffff8717ebf4>] [<ffffffff8717ebf4>] unix_notinflight+0x3b4/0x490 net/unix/garbage.c:149 Call Trace: [<ffffffff8716cfbf>] unix_detach_fds.isra.19+0xff/0x170 net/unix/af_unix.c:1487 [<ffffffff8716f6a9>] unix_destruct_scm+0xf9/0x210 net/unix/af_unix.c:1496 [<ffffffff86a90a01>] skb_release_head_state+0x101/0x200 net/core/skbuff.c:655 [<ffffffff86a9808a>] skb_release_all+0x1a/0x60 net/core/skbuff.c:668 [<ffffffff86a980ea>] __kfree_skb+0x1a/0x30 net/core/skbuff.c:684 [<ffffffff86a98284>] kfree_skb+0x184/0x570 net/core/skbuff.c:705 [<ffffffff871789d5>] unix_release_sock+0x5b5/0xbd0 net/unix/af_unix.c:559 [<ffffffff87179039>] unix_release+0x49/0x90 net/unix/af_unix.c:836 [<ffffffff86a694b2>] sock_release+0x92/0x1f0 net/socket.c:570 [<ffffffff86a6962b>] sock_close+0x1b/0x20 net/socket.c:1017 [<ffffffff81a76b8e>] __fput+0x34e/0x910 fs/file_table.c:208 [<ffffffff81a771da>] ____fput+0x1a/0x20 fs/file_table.c:244 [<ffffffff81483ab0>] task_work_run+0x1a0/0x280 kernel/task_work.c:116 [< inline >] exit_task_work include/linux/task_work.h:21 [<ffffffff8141287a>] do_exit+0x183a/0x2640 kernel/exit.c:828 [<ffffffff8141383e>] do_group_exit+0x14e/0x420 kernel/exit.c:931 [<ffffffff814429d3>] get_signal+0x663/0x1880 kernel/signal.c:2307 [<ffffffff81239b45>] do_signal+0xc5/0x2190 arch/x86/kernel/signal.c:807 [<ffffffff8100666a>] exit_to_usermode_loop+0x1ea/0x2d0 arch/x86/entry/common.c:156 [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:190 [<ffffffff81009693>] syscall_return_slowpath+0x4d3/0x570 arch/x86/entry/common.c:259 [<ffffffff881478e6>] entry_SYSCALL_64_fastpath+0xc4/0xc6 Link: Signed-off-by: Andrey Ulanov <> Reported-by: Dmitry Vyukov <> Fixes: 6209344 ("net: unix: fix inflight counting bug in garbage collector") Signed-off-by: David S. Miller <>
2017-03-09net: Work around lockdep limitation in sockets that use socketsDavid Howells-2/+3
Lockdep issues a circular dependency warning when AFS issues an operation through AF_RXRPC from a context in which the VFS/VM holds the mmap_sem. The theory lockdep comes up with is as follows: (1) If the pagefault handler decides it needs to read pages from AFS, it calls AFS with mmap_sem held and AFS begins an AF_RXRPC call, but creating a call requires the socket lock: mmap_sem must be taken before sk_lock-AF_RXRPC (2) afs_open_socket() opens an AF_RXRPC socket and binds it. rxrpc_bind() binds the underlying UDP socket whilst holding its socket lock. inet_bind() takes its own socket lock: sk_lock-AF_RXRPC must be taken before sk_lock-AF_INET (3) Reading from a TCP socket into a userspace buffer might cause a fault and thus cause the kernel to take the mmap_sem, but the TCP socket is locked whilst doing this: sk_lock-AF_INET must be taken before mmap_sem However, lockdep's theory is wrong in this instance because it deals only with lock classes and not individual locks. The AF_INET lock in (2) isn't really equivalent to the AF_INET lock in (3) as the former deals with a socket entirely internal to the kernel that never sees userspace. This is a limitation in the design of lockdep. Fix the general case by: (1) Double up all the locking keys used in sockets so that one set are used if the socket is created by userspace and the other set is used if the socket is created by the kernel. (2) Store the kern parameter passed to sk_alloc() in a variable in the sock struct (sk_kern_sock). This informs sock_lock_init(), sock_init_data() and sk_clone_lock() as to the lock keys to be used. Note that the child created by sk_clone_lock() inherits the parent's kern setting. (3) Add a 'kern' parameter to ->accept() that is analogous to the one passed in to ->create() that distinguishes whether kernel_accept() or sys_accept4() was the caller and can be passed to sk_alloc(). Note that a lot of accept functions merely dequeue an already allocated socket. I haven't touched these as the new socket already exists before we get the parameter. Note also that there are a couple of places where I've made the accepted socket unconditionally kernel-based: irda_accept() rds_rcp_accept_one() tcp_accept_from_sock() because they follow a sock_create_kern() and accept off of that. Whilst creating this, I noticed that lustre and ocfs don't create sockets through sock_create_kern() and thus they aren't marked as for-kernel, though they appear to be internal. I wonder if these should do that so that they use the new set of lock keys. Signed-off-by: David Howells <> Signed-off-by: David S. Miller <>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar-1/+1
<linux/sched/signal.h> We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <> Cc: Mike Galbraith <> Cc: Peter Zijlstra <> Cc: Thomas Gleixner <> Cc: Signed-off-by: Ingo Molnar <>
2017-02-02unix: add ioctl to open a unix socket file with O_PATHAndrey Vagin-0/+41
This ioctl opens a file to which a socket is bound and returns a file descriptor. The caller has to have CAP_NET_ADMIN in the socket network namespace. Currently it is impossible to get a path and a mount point for a socket file. socket_diag reports address, device ID and inode number for unix sockets. An address can contain a relative path or a file may be moved somewhere. And these properties say nothing about a mount namespace and a mount point of a socket file. With the introduced ioctl, we can get a path by reading /proc/self/fd/X and get mnt_id from /proc/self/fdinfo/X. In CRIU we are going to use this ioctl to dump and restore unix socket. Here is an example how it can be used: $ strace -e socket,bind,ioctl ./test /tmp/test_sock socket(AF_UNIX, SOCK_STREAM, 0) = 3 bind(3, {sa_family=AF_UNIX, sun_path="test_sock"}, 11) = 0 ioctl(3, SIOCUNIXFILE, 0) = 4 ^Z $ ss -a | grep test_sock u_str LISTEN 0 1 test_sock 17798 * 0 $ ls -l /proc/760/fd/{3,4} lrwx------ 1 root root 64 Feb 1 09:41 3 -> 'socket:[17798]' l--------- 1 root root 64 Feb 1 09:41 4 -> /tmp/test_sock $ cat /proc/760/fdinfo/4 pos: 0 flags: 012000000 mnt_id: 40 $ cat /proc/self/mountinfo | grep "^40\s" 40 19 0:37 / /tmp rw shared:23 - tmpfs tmpfs rw Signed-off-by: Andrei Vagin <> Signed-off-by: David S. Miller <>
2017-01-24af_unix: move unix_mknod() out of bindlockWANG Cong-11/+16
Dmitry reported a deadlock scenario: unix_bind() path: u->bindlock ==> sb_writer do_splice() path: sb_writer ==> pipe->mutex ==> u->bindlock In the unix_bind() code path, unix_mknod() does not have to be done with u->bindlock held, since it is a pure fs operation, so we can just move unix_mknod() out. Reported-by: Dmitry Vyukov <> Tested-by: Dmitry Vyukov <> Cc: Rainer Weikusat <> Cc: Al Viro <> Signed-off-by: Cong Wang <> Signed-off-by: David S. Miller <>
2016-12-24Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds-1/+1
This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <> Signed-off-by: Linus Torvalds <>
2016-12-16Merge branch 'overlayfs-linus' of ↵Linus Torvalds-3/+3
git:// Pull overlayfs updates from Miklos Szeredi: "This update contains: - try to clone on copy-up - allow renaming a directory - split source into managable chunks - misc cleanups and fixes It does not contain the read-only fd data inconsistency fix, which Al didn't like. I'll leave that to the next year..." * 'overlayfs-linus' of git:// (36 commits) ovl: fix reStructuredText syntax errors in documentation ovl: fix return value of ovl_fill_super ovl: clean up kstat usage ovl: fold ovl_copy_up_truncate() into ovl_copy_up() ovl: create directories inside merged parent opaque ovl: opaque cleanup ovl: show redirect_dir mount option ovl: allow setting max size of redirect ovl: allow redirect_dir to default to "on" ovl: check for emptiness of redirect dir ovl: redirect on rename-dir ovl: lookup redirects ovl: consolidate lookup for underlying layers ovl: fix nested overlayfs mount ovl: check namelen ovl: split super.c ovl: use d_is_dir() ovl: simplify lookup ovl: check lower existence of rename target ovl: rename: simplify handling of lower/merged directory ...
2016-12-16Revert "af_unix: fix hard linked sockets on overlay"Miklos Szeredi-3/+3
This reverts commit eb0a4a47ae89aaa0674ab3180de6a162f3be2ddf. Since commit 51f7e52dc943 ("ovl: share inode for hard link") there's no need to call d_real_inode() to check two overlay inodes for equality. Side effect of this revert is that it's no longer possible to connect one socket on overlayfs to one on the underlying layer (something which didn't make sense anyway). Signed-off-by: Miklos Szeredi <>
2016-11-22Merge git:// S. Miller-6/+11
All conflicts were simple overlapping changes except perhaps for the Thunder driver. That driver has a change_mtu method explicitly for sending a message to the hardware. If that fails it returns an error. Normally a driver doesn't need an ndo_change_mtu method becuase those are usually just range changes, which are now handled generically. But since this extra operation is needed in the Thunder driver, it has to stay. However, if the message send fails we have to restore the original MTU before the change because the entire call chain expects that if an error is thrown by ndo_change_mtu then the MTU did not change. Therefore code is added to nicvf_change_mtu to remember the original MTU, and to restore it upon nicvf_update_hw_max_frs() failue. Signed-off-by: David S. Miller <>
2016-11-18af_unix: conditionally use freezable blocking calls in readWANG Cong-6/+11
Commit 2b15af6f95 ("af_unix: use freezable blocking calls in read") converts schedule_timeout() to its freezable version, it was probably correct at that time, but later, commit 2b514574f7e8 ("net: af_unix: implement splice for stream af_unix sockets") breaks the strong requirement for a freezable sleep, according to commit 0f9548ca1091: We shouldn't try_to_freeze if locks are held. Holding a lock can cause a deadlock if the lock is later acquired in the suspend or hibernate path (e.g. by dpm). Holding a lock can also cause a deadlock in the case of cgroup_freezer if a lock is held inside a frozen cgroup that is later acquired by a process outside that group. The pipe_lock is still held at that point. So use freezable version only for the recvmsg call path, avoid impact for Android. Fixes: 2b514574f7e8 ("net: af_unix: implement splice for stream af_unix sockets") Reported-by: Dmitry Vyukov <> Cc: Tejun Heo <> Cc: Colin Cross <> Cc: Rafael J. Wysocki <> Cc: Hannes Frederic Sowa <> Signed-off-by: Cong Wang <> Signed-off-by: David S. Miller <>
2016-11-15Merge git:// S. Miller-1/+2
Several cases of bug fixes in 'net' overlapping other changes in 'net-next-. Signed-off-by: David S. Miller <>
2016-11-07udp: do fwd memory scheduling on dequeuePaolo Abeni-2/+2
A new argument is added to __skb_recv_datagram to provide an explicit skb destructor, invoked under the receive queue lock. The UDP protocol uses such argument to perform memory reclaiming on dequeue, so that the UDP protocol does not set anymore skb->desctructor. Instead explicit memory reclaiming is performed at close() time and when skbs are removed from the receive queue. The in kernel UDP protocol users now need to call a skb_recv_udp() variant instead of skb_recv_datagram() to properly perform memory accounting on dequeue. Overall, this allows acquiring only once the receive queue lock on dequeue. Tested using pktgen with random src port, 64 bytes packet, wire-speed on a 10G link as sender and udp_sink as the receiver, using an l4 tuple rxhash to stress the contention, and one or more udp_sink instances with reuseport. nr sinks vanilla patched 1 440 560 3 2150 2300 6 3650 3800 9 4450 4600 12 6250 6450 v1 -> v2: - do rmem and allocated memory scheduling under the receive lock - do bulk scheduling in first_packet_length() and in udp_destruct_sock() - avoid the typdef for the dequeue callback Suggested-by: Eric Dumazet <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: Paolo Abeni <> Acked-by: Eric Dumazet <> Signed-off-by: David S. Miller <>
2016-11-01unix: escape all null bytes in abstract unix domain socketIsaac Boukris-1/+2
Abstract unix domain socket may embed null characters, these should be translated to '@' when printed out to proc the same way the null prefix is currently being translated. This helps for tools such as netstat, lsof and the proc based implementation in ss to show all the significant bytes of the name (instead of getting cut at the first null occurrence). Signed-off-by: Isaac Boukris <> Signed-off-by: David S. Miller <>
2016-10-03skb_splice_bits(): get rid of callbackAl Viro-16/+1
since pipe_lock is the outermost now, we don't need to drop/regain socket locks around the call of splice_to_pipe() from skb_splice_bits(), which kills the need to have a socket-specific callback; we can just call splice_to_pipe() and be done with that. Signed-off-by: Al Viro <>
2016-09-04af_unix: split 'u->readlock' into two: 'iolock' and 'bindlock'Linus Torvalds-22/+23
Right now we use the 'readlock' both for protecting some of the af_unix IO path and for making the bind be single-threaded. The two are independent, but using the same lock makes for a nasty deadlock due to ordering with regards to filesystem locking. The bind locking would want to nest outside the VSF pathname locking, but the IO locking wants to nest inside some of those same locks. We tried to fix this earlier with commit c845acb324aa ("af_unix: Fix splice-bind deadlock") which moved the readlock inside the vfs locks, but that caused problems with overlayfs that will then call back into filesystem routines that take the lock in the wrong order anyway. Splitting the locks means that we can go back to having the bind lock be the outermost lock, and we don't have any deadlocks with lock ordering. Acked-by: Rainer Weikusat <> Acked-by: Al Viro <> Signed-off-by: Linus Torvalds <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2016-09-04Revert "af_unix: Fix splice-bind deadlock"Linus Torvalds-40/+26
This reverts commit c845acb324aa85a39650a14e7696982ceea75dc1. It turns out that it just replaces one deadlock with another one: we can still get the wrong lock ordering with the readlock due to overlayfs calling back into the filesystem layer and still taking the vfs locks after the readlock. The proper solution ends up being to just split the readlock into two pieces: the bind lock (taken *outside* the vfs locks) and the IO lock (taken *inside* the filesystem locks). The two locks are independent anyway. Signed-off-by: Linus Torvalds <> Reviewed-by: Shmulik Ladkani <> Signed-off-by: David S. Miller <>
2016-07-26af_unix: charge buffers to kmemcgVladimir Davydov-0/+1
Unix sockets can consume a significant amount of system memory, hence they should be accounted to kmemcg. Since unix socket buffers are always allocated from process context, all we need to do to charge them to kmemcg is set __GFP_ACCOUNT in sock->sk_allocation mask. Eric asked: > 1) What happens when a buffer, allocated from socket <A> lands in a > different socket <B>, maybe owned by another user/process. > > Who owns it now, in term of kmemcg accounting ? We never move memcg charges. E.g. if two processes from different cgroups are sharing a memory region, each page will be charged to the process which touched it first. Or if two processes are working with the same directory tree, inodes and dentries will be charged to the first user. The same is fair for unix socket buffers - they will be charged to the sender. > 2) Has performance impact been evaluated ? I ran netperf STREAM_STREAM with default options in a kmemcg on a 4 core x2 HT box. The results are below: # clients bandwidth (10^6bits/sec) base patched 1 67643 +- 725 64874 +- 353 - 4.0 % 4 193585 +- 2516 186715 +- 1460 - 3.5 % 8 194820 +- 377 187443 +- 1229 - 3.7 % So the accounting doesn't come for free - it takes ~4% of performance. I believe we could optimize it by using per cpu batching not only on charge, but also on uncharge in memcg core, but that's beyond the scope of this patch set - I'll take a look at this later. Anyway, if performance impact is found to be unacceptable, it is always possible to disable kmem accounting at boot time (cgroup.memory=nokmem) or not use memory cgroups at runtime at all (thanks to jump labels there'll be no overhead even if they are compiled in). Link: Signed-off-by: Vladimir Davydov <> Cc: "David S. Miller" <> Cc: Johannes Weiner <> Cc: Michal Hocko <> Cc: Eric Dumazet <> Cc: Minchan Kim <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2016-06-12Merge branch 'overlayfs-af_unix-fix' into overlayfs-linusMiklos Szeredi-3/+3
2016-05-20af_unix: fix hard linked sockets on overlayMiklos Szeredi-3/+3
Overlayfs uses separate inodes even in the case of hard links on the underlying filesystems. This is a problem for AF_UNIX socket implementation which indexes sockets based on the inode. This resulted in hard linked sockets not working. The fix is to use the real, underlying inode. Test case follows: -- ovl-sock-test.c -- #include <unistd.h> #include <err.h> #include <sys/socket.h> #include <sys/un.h> #define SOCK "test-sock" #define SOCK2 "test-sock2" int main(void) { int fd, fd2; struct sockaddr_un addr = { .sun_family = AF_UNIX, .sun_path = SOCK, }; struct sockaddr_un addr2 = { .sun_family = AF_UNIX, .sun_path = SOCK2, }; unlink(SOCK); unlink(SOCK2); if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) err(1, "socket"); if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1) err(1, "bind"); if (listen(fd, 0) == -1) err(1, "listen"); if (link(SOCK, SOCK2) == -1) err(1, "link"); if ((fd2 = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) err(1, "socket"); if (connect(fd2, (struct sockaddr *) &addr2, sizeof(addr2)) == -1) err (1, "connect"); return 0; } ---- Reported-by: Alexander Morozov <> Signed-off-by: Miklos Szeredi <> Cc: <>
2016-03-28constify security_path_{mkdir,mknod,symlink}Al Viro-1/+1
... as well as unix_mknod() and may_o_create() Signed-off-by: Al Viro <>
2016-02-23Merge git:// S. Miller-15/+25
Conflicts: drivers/net/phy/bcm7xxx.c drivers/net/phy/marvell.c drivers/net/vxlan.c All three conflicts were cases of simple overlapping changes. Signed-off-by: David S. Miller <>
2016-02-19af_unix: Don't use continue to re-execute unix_stream_read_generic loopRainer Weikusat-1/+2
The unix_stream_read_generic function tries to use a continue statement to restart the receive loop after waiting for a message. This may not work as intended as the caller might use a recvmsg call to peek at control messages without specifying a message buffer. If this was the case, the continue will cause the function to return without an error and without the credential information if the function had to wait for a message while it had returned with the credentials otherwise. Change to using goto to restart the loop without checking the condition first in this case so that credentials are returned either way. Signed-off-by: Rainer Weikusat <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2016-02-19unix_diag: fix incorrect sign extension in unix_lookup_by_inoDmitry V. Levin-1/+1
The value passed by unix_diag_get_exact to unix_lookup_by_ino has type __u32, but unix_lookup_by_ino's argument ino has type int, which is not a problem yet. However, when ino is compared with sock_i_ino return value of type unsigned long, ino is sign extended to signed long, and this results to incorrect comparison on 64-bit architectures for inode numbers greater than INT_MAX. This bug was found by strace test suite. Fixes: 5d3cae8bc39d ("unix_diag: Dumping exact socket core") Signed-off-by: Dmitry V. Levin <> Acked-by: Cong Wang <> Signed-off-by: David S. Miller <>
2016-02-16af_unix: Guard against other == sk in unix_dgram_sendmsgRainer Weikusat-1/+6
The unix_dgram_sendmsg routine use the following test if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { to determine if sk and other are in an n:1 association (either established via connect or by using sendto to send messages to an unrelated socket identified by address). This isn't correct as the specified address could have been bound to the sending socket itself or because this socket could have been connected to itself by the time of the unix_peer_get but disconnected before the unix_state_lock(other). In both cases, the if-block would be entered despite other == sk which might either block the sender unintentionally or lead to trying to unlock the same spin lock twice for a non-blocking send. Add a other != sk check to guard against this. Fixes: 7d267278a9ec ("unix: avoid use-after-free in ep_remove_wait_queue") Reported-By: Philipp Hahn <> Signed-off-by: Rainer Weikusat <> Tested-by: Philipp Hahn <> Signed-off-by: David S. Miller <>
2016-02-16af_unix: Don't set err in unix_stream_read_generic unless there was an errorRainer Weikusat-6/+10
The present unix_stream_read_generic contains various code sequences of the form err = -EDISASTER; if (<test>) goto out; This has the unfortunate side effect of possibly causing the error code to bleed through to the final out: return copied ? : err; and then to be wrongly returned if no data was copied because the caller didn't supply a data buffer, as demonstrated by the program available at Change it such that err is only set if an error condition was detected. Fixes: 3822b5c2fc62 ("af_unix: Revert 'lock_interruptible' in stream receive code") Reported-by: Joseph Salisbury <> Signed-off-by: Rainer Weikusat <> Signed-off-by: David S. Miller <>
2016-02-08unix: correctly track in-flight fds in sending process user_structHannes Frederic Sowa-6/+6
The commit referenced in the Fixes tag incorrectly accounted the number of in-flight fds over a unix domain socket to the original opener of the file-descriptor. This allows another process to arbitrary deplete the original file-openers resource limit for the maximum of open files. Instead the sending processes and its struct cred should be credited. To do so, we add a reference counted struct user_struct pointer to the scm_fp_list and use it to account for the number of inflight unix fds. Fixes: 712f4aad406bb1 ("unix: properly account for FDs passed over unix sockets") Reported-by: David Herrmann <> Cc: David Herrmann <> Cc: Willy Tarreau <> Cc: Linus Torvalds <> Suggested-by: Linus Torvalds <> Signed-off-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2016-02-07net: drop write-only stack variableDavid Herrmann-4/+1
Remove a write-only stack variable from unix_attach_fds(). This is a left-over from the security fix in: commit 712f4aad406bb1ed67f3f98d04c044191f0ff593 Author: willy tarreau <> Date: Sun Jan 10 07:54:56 2016 +0100 unix: properly account for FDs passed over unix sockets Signed-off-by: David Herrmann <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2016-01-24af_unix: fix struct pid memory leakEric Dumazet-0/+1
Dmitry reported a struct pid leak detected by a syzkaller program. Bug happens in unix_stream_recvmsg() when we break the loop when a signal is pending, without properly releasing scm. Fixes: b3ca9b02b007 ("net: fix multithreaded signal handling in unix recv routines") Reported-by: Dmitry Vyukov <> Signed-off-by: Eric Dumazet <> Cc: Rainer Weikusat <> Signed-off-by: David S. Miller <>
2016-01-11Merge git:// S. Miller-9/+28
Conflicts: drivers/net/bonding/bond_main.c drivers/net/ethernet/mellanox/mlxsw/spectrum.h drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c The bond_main.c and mellanox switch conflicts were cases of overlapping changes. Signed-off-by: David S. Miller <>
2016-01-11unix: properly account for FDs passed over unix socketswilly tarreau-9/+28
It is possible for a process to allocate and accumulate far more FDs than the process' limit by sending them over a unix socket then closing them to keep the process' fd count low. This change addresses this problem by keeping track of the number of FDs in flight per user and preventing non-privileged processes from having more FDs in flight than their configured FD limit. Reported-by: Reported-by: Tetsuo Handa <> Mitigates: CVE-2013-4312 (Linux 2.0+) Suggested-by: Linus Torvalds <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: Willy Tarreau <> Signed-off-by: David S. Miller <>
2016-01-06Merge git:// S. Miller-26/+40
2016-01-04af_unix: Fix splice-bind deadlockRainer Weikusat-26/+40
On 2015/11/06, Dmitry Vyukov reported a deadlock involving the splice system call and AF_UNIX sockets, The situation was analyzed as (a while ago) A: socketpair() B: splice() from a pipe to /mnt/regular_file does sb_start_write() on /mnt C: try to freeze /mnt wait for B to finish with /mnt A: bind() try to bind our socket to /mnt/new_socket_name lock our socket, see it not bound yet decide that it needs to create something in /mnt try to do sb_start_write() on /mnt, block (it's waiting for C). D: splice() from the same pipe to our socket lock the pipe, see that socket is connected try to lock the socket, block waiting for A B: get around to actually feeding a chunk from pipe to file, try to lock the pipe. Deadlock. on 2015/11/10 by Al Viro, The patch fixes this by removing the kern_path_create related code from unix_mknod and executing it as part of unix_bind prior acquiring the readlock of the socket in question. This means that A (as used above) will sb_start_write on /mnt before it acquires the readlock, hence, it won't indirectly block B which first did a sb_start_write and then waited for a thread trying to acquire the readlock. Consequently, A being blocked by C waiting for B won't cause a deadlock anymore (effectively, both A and B acquire two locks in opposite order in the situation described above). Dmitry Vyukov(<>) tested the original patch. Signed-off-by: Rainer Weikusat <> Signed-off-by: David S. Miller <>
2015-12-17Merge git:// S. Miller-10/+3
Conflicts: drivers/net/geneve.c Here we had an overlapping change, where in 'net' the extraneous stats bump was being removed whilst in 'net-next' the final argument to udp_tunnel6_xmit_skb() was being changed. Signed-off-by: David S. Miller <>
2015-12-17af_unix: Revert 'lock_interruptible' in stream receive codeRainer Weikusat-10/+3
With b3ca9b02b00704053a38bfe4c31dbbb9c13595d0, the AF_UNIX SOCK_STREAM receive code was changed from using mutex_lock(&u->readlock) to mutex_lock_interruptible(&u->readlock) to prevent signals from being delayed for an indefinite time if a thread sleeping on the mutex happened to be selected for handling the signal. But this was never a problem with the stream receive code (as opposed to its datagram counterpart) as that never went to sleep waiting for new messages with the mutex held and thus, wouldn't cause secondary readers to block on the mutex waiting for the sleeping primary reader. As the interruptible locking makes the code more complicated in exchange for no benefit, change it back to using mutex_lock. Signed-off-by: Rainer Weikusat <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2015-12-06af_unix: fix unix_dgram_recvmsg entry lockingRainer Weikusat-15/+20
The current unix_dgram_recvsmg code acquires the u->readlock mutex in order to protect access to the peek offset prior to calling __skb_recv_datagram for actually receiving data. This implies that a blocking reader will go to sleep with this mutex held if there's presently no data to return to userspace. Two non-desirable side effects of this are that a later non-blocking read call on the same socket will block on the ->readlock mutex until the earlier blocking call releases it (or the readers is interrupted) and that later blocking read calls will wait longer than the effective socket read timeout says they should: The timeout will only start 'ticking' once such a reader hits the schedule_timeout in wait_for_more_packets (core.c) while the time it already had to wait until it could acquire the mutex is unaccounted for. The patch avoids both by using the __skb_try_recv_datagram and __skb_wait_for_more packets functions created by the first patch to implement a unix_dgram_recvmsg read loop which releases the readlock mutex prior to going to sleep and reacquires it as needed afterwards. Non-blocking readers will thus immediately return with -EAGAIN if there's no data available regardless of any concurrent blocking readers and all blocking readers will end up sleeping via schedule_timeout, thus honouring the configured socket receive timeout. Signed-off-by: Rainer Weikusat <> Signed-off-by: David S. Miller <>
2015-12-03Merge git:// S. Miller-37/+231
Conflicts: drivers/net/ethernet/renesas/ravb_main.c kernel/bpf/syscall.c net/ipv4/ipmr.c All three conflicts were cases of overlapping changes. Signed-off-by: David S. Miller <>
2015-12-01net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATAEric Dumazet-3/+3
This patch is a cleanup to make following patch easier to review. Goal is to move SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA from (struct socket)->flags to a (struct socket_wq)->flags to benefit from RCU protection in sock_wake_async() To ease backports, we rename both constants. Two new helpers, sk_set_bit(int nr, struct sock *sk) and sk_clear_bit(int net, struct sock *sk) are added so that following patch can change their implementation. Signed-off-by: Eric Dumazet <> Signed-off-by: David S. Miller <>
2015-12-01unix: use wq_has_sleeper in unix_dgram_recvmsgRainer Weikusat-2/+4
The current unix_dgram_recvmsg does a wake up for every received datagram. This seems wasteful as only SOCK_DGRAM client sockets in an n:1 association with a server socket will ever wait because of the associated condition. The patch below changes the function such that the wake up only happens if wq_has_sleeper indicates that someone actually wants to be notified. Testing with SOCK_SEQPACKET and SOCK_DGRAM socket seems to confirm that this is an improvment. Signed-Off-By: Rainer Weikusat <> Signed-off-by: David S. Miller <>
2015-11-30af-unix: passcred support for sendpageHannes Frederic Sowa-15/+64
sendpage did not care about credentials at all. This could lead to situations in which because of fd passing between processes we could append data to skbs with different scm data. It is illegal to splice those skbs together. Instead we have to allocate a new skb and if requested fill out the scm details. Fixes: 869e7c62486ec ("net: af_unix: implement stream sendpage support") Reported-by: Al Viro <> Cc: Al Viro <> Cc: Eric Dumazet <> Signed-off-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2015-11-30net: Generalise wq_has_sleeper helperHerbert Xu-1/+1
The memory barrier in the helper wq_has_sleeper is needed by just about every user of waitqueue_active. This patch generalises it by making it take a wait_queue_head_t directly. The existing helper is renamed to skwq_has_sleeper. Signed-off-by: Herbert Xu <> Signed-off-by: David S. Miller <>
2015-11-23unix: avoid use-after-free in ep_remove_wait_queueRainer Weikusat-19/+164
Rainer Weikusat <> writes: An AF_UNIX datagram socket being the client in an n:1 association with some server socket is only allowed to send messages to the server if the receive queue of this socket contains at most sk_max_ack_backlog datagrams. This implies that prospective writers might be forced to go to sleep despite none of the message presently enqueued on the server receive queue were sent by them. In order to ensure that these will be woken up once space becomes again available, the present unix_dgram_poll routine does a second sock_poll_wait call with the peer_wait wait queue of the server socket as queue argument (unix_dgram_recvmsg does a wake up on this queue after a datagram was received). This is inherently problematic because the server socket is only guaranteed to remain alive for as long as the client still holds a reference to it. In case the connection is dissolved via connect or by the dead peer detection logic in unix_dgram_sendmsg, the server socket may be freed despite "the polling mechanism" (in particular, epoll) still has a pointer to the corresponding peer_wait queue. There's no way to forcibly deregister a wait queue with epoll. Based on an idea by Jason Baron, the patch below changes the code such that a wait_queue_t belonging to the client socket is enqueued on the peer_wait queue of the server whenever the peer receive queue full condition is detected by either a sendmsg or a poll. A wake up on the peer queue is then relayed to the ordinary wait queue of the client socket via wake function. The connection to the peer wait queue is again dissolved if either a wake up is about to be relayed or the client socket reconnects or a dead peer is detected or the client socket is itself closed. This enables removing the second sock_poll_wait from unix_dgram_poll, thus avoiding the use-after-free, while still ensuring that no blocked writer sleeps forever. Signed-off-by: Rainer Weikusat <> Fixes: ec0d215f9420 ("af_unix: fix 'poll for write'/connected DGRAM sockets") Reviewed-by: Jason Baron <> Signed-off-by: David S. Miller <>
2015-11-17af_unix: take receive queue lock while appending new skbHannes Frederic Sowa-1/+4
While possibly in future we don't necessarily need to use sk_buff_head.lock this is a rather larger change, as it affects the af_unix fd garbage collector, diag and socket cleanups. This is too much for a stable patch. For the time being grab sk_buff_head.lock without disabling bh and irqs, so don't use locked skb_queue_tail. Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support") Cc: Eric Dumazet <> Signed-off-by: Hannes Frederic Sowa <> Reported-by: Eric Dumazet <> Acked-by: Eric Dumazet <> Signed-off-by: David S. Miller <>
2015-11-16af_unix: don't append consumed skbs to sk_receive_queueHannes Frederic Sowa-0/+1
In case multiple writes to a unix stream socket race we could end up in a situation where we pre-allocate a new skb for use in unix_stream_sendpage but have to free it again in the locked section because another skb has been appended meanwhile, which we must use. Accidentally we didn't clear the pointer after consuming it and so we touched freed memory while appending it to the sk_receive_queue. So, clear the pointer after consuming the skb. This bug has been found with syzkaller ( by Dmitry Vyukov. Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support") Reported-by: Dmitry Vyukov <> Cc: Dmitry Vyukov <> Cc: Eric Dumazet <> Signed-off-by: Hannes Frederic Sowa <> Acked-by: Eric Dumazet <> Signed-off-by: David S. Miller <>
2015-11-15af-unix: fix use-after-free with concurrent readers while splicingHannes Frederic Sowa-0/+18
During splicing an af-unix socket to a pipe we have to drop all af-unix socket locks. While doing so we allow another reader to enter unix_stream_read_generic which can read, copy and finally free another skb. If exactly this skb is just in process of being spliced we get a use-after-free report by kasan. First, we must make sure to not have a free while the skb is used during the splice operation. We simply increment its use counter before unlocking the reader lock. Stream sockets have the nice characteristic that we don't care about zero length writes and they never reach the peer socket's queue. That said, we can take the UNIXCB.consumed field as the indicator if the skb was already freed from the socket's receive queue. If the skb was fully consumed after we locked the reader side again we know it has been dropped by a second reader. We indicate a short read to user space and abort the current splice operation. This bug has been found with syzkaller ( by Dmitry Vyukov. Fixes: 2b514574f7e8 ("net: af_unix: implement splice for stream af_unix sockets") Reported-by: Dmitry Vyukov <> Cc: Dmitry Vyukov <> Cc: Eric Dumazet <> Acked-by: Eric Dumazet <> Signed-off-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <>
2015-10-25af_unix: do not report POLLOUT on listenersEric Dumazet-2/+3
poll(POLLOUT) on a listener should not report fd is ready for a write(). This would break some applications using poll() and = -1, as they would not block in poll() Signed-off-by: Eric Dumazet <> Reported-by: Alan Burlison <> Tested-by: Eric Dumazet <> Signed-off-by: David S. Miller <>
2015-10-05net/unix: fix logic about sk_peek_offsetAndrey Vagin-5/+7
Now send with MSG_PEEK can return data from multiple SKBs. Unfortunately we take into account the peek offset for each skb, that is wrong. We need to apply the peek offset only once. In addition, the peek offset should be used only if MSG_PEEK is set. Cc: "David S. Miller" <> (maintainer:NETWORKING Cc: Eric Dumazet <> (commit_signer:1/14=7%) Cc: Aaron Conole <> Fixes: 9f389e35674f ("af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag") Signed-off-by: Andrey Vagin <> Tested-by: Aaron Conole <> Signed-off-by: David S. Miller <>
2015-09-29af_unix: return data from multiple SKBs on recv() with MSG_PEEK flagAaron Conole-1/+14
AF_UNIX sockets now return multiple skbs from recv() when MSG_PEEK flag is set. This is referenced in kernel bugzilla #12323 @ As described both in the BZ and lkml thread @ calling recv() with MSG_PEEK on an AF_UNIX socket only reads a single skb, where the desired effect is to return as much skb data has been queued, until hitting the recv buffer size (whichever comes first). The modified MSG_PEEK path will now move to the next skb in the tree and jump to the again: label, rather than following the natural loop structure. This requires duplicating some of the loop head actions. This was tested using the python socketpair python code attached to the bugzilla issue. Signed-off-by: Aaron Conole <> Signed-off-by: David S. Miller <>
2015-06-10net/unix: support SCM_SECURITY for stream socketsStephen Smalley-4/+16
SCM_SECURITY was originally only implemented for datagram sockets, not for stream sockets. However, SCM_CREDENTIALS is supported on Unix stream sockets. For consistency, implement Unix stream support for SCM_SECURITY as well. Also clean up the existing code and get rid of the superfluous UNIXSID macro. Motivated by, where systemd was using SCM_CREDENTIALS and assumed wrongly that SCM_SECURITY was also supported on Unix stream sockets. Signed-off-by: Stephen Smalley <> Acked-by: Paul Moore <> Signed-off-by: David S. Miller <>