From 73ed5d25dce0354ea381d6dc93005c3085fae03d Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Tue, 10 Nov 2015 16:23:15 +0100 Subject: af-unix: fix use-after-free with concurrent readers while splicing 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 (http://github.com/google/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 --- net/unix/af_unix.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index aaa0b58d6aba..12b886f07982 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -441,6 +441,7 @@ static void unix_release_sock(struct sock *sk, int embrion) if (state == TCP_LISTEN) unix_release_sock(skb->sk, 1); /* passed fds are erased in the kfree_skb hook */ + UNIXCB(skb).consumed = skb->len; kfree_skb(skb); } @@ -2072,6 +2073,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state) do { int chunk; + bool drop_skb; struct sk_buff *skb, *last; unix_state_lock(sk); @@ -2152,7 +2154,11 @@ unlock: } chunk = min_t(unsigned int, unix_skb_len(skb) - skip, size); + skb_get(skb); chunk = state->recv_actor(skb, skip, chunk, state); + drop_skb = !unix_skb_len(skb); + /* skb is only safe to use if !drop_skb */ + consume_skb(skb); if (chunk < 0) { if (copied == 0) copied = -EFAULT; @@ -2161,6 +2167,18 @@ unlock: copied += chunk; size -= chunk; + if (drop_skb) { + /* the skb was touched by a concurrent reader; + * we should not expect anything from this skb + * anymore and assume it invalid - we can be + * sure it was dropped from the socket queue + * + * let's report a short read + */ + err = 0; + break; + } + /* Mark read part of skb as used */ if (!(flags & MSG_PEEK)) { UNIXCB(skb).consumed += chunk; -- cgit v1.2.3 From 8844f97238ca6c1ca92a5d6c69f53efd361a266f Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Mon, 16 Nov 2015 16:25:56 +0100 Subject: af_unix: don't append consumed skbs to sk_receive_queue 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 (http://github.com/google/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 --- net/unix/af_unix.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 12b886f07982..a8352db5c5b5 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1800,6 +1800,7 @@ alloc_skb: * this - does no harm */ consume_skb(newskb); + newskb = NULL; } if (skb_append_pagefrags(skb, page, offset, size)) { -- cgit v1.2.3 From a3a116e04cc6a94d595ead4e956ab1bc1d2f4746 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Tue, 17 Nov 2015 15:10:59 +0100 Subject: af_unix: take receive queue lock while appending new skb 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 --- net/unix/af_unix.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index a8352db5c5b5..955ec152cb71 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1813,8 +1813,11 @@ alloc_skb: skb->truesize += size; atomic_add(size, &sk->sk_wmem_alloc); - if (newskb) + if (newskb) { + spin_lock(&other->sk_receive_queue.lock); __skb_queue_tail(&other->sk_receive_queue, newskb); + spin_unlock(&other->sk_receive_queue.lock); + } unix_state_unlock(other); mutex_unlock(&unix_sk(other)->readlock); -- cgit v1.2.3 From 7d267278a9ece963d77eefec61630223fce08c6c Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Fri, 20 Nov 2015 22:07:23 +0000 Subject: unix: avoid use-after-free in ep_remove_wait_queue 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 --- include/net/af_unix.h | 1 + net/unix/af_unix.c | 183 ++++++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 165 insertions(+), 19 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/include/net/af_unix.h b/include/net/af_unix.h index b36d837c701e..2a91a0561a47 100644 --- a/include/net/af_unix.h +++ b/include/net/af_unix.h @@ -62,6 +62,7 @@ struct unix_sock { #define UNIX_GC_CANDIDATE 0 #define UNIX_GC_MAYBE_CYCLE 1 struct socket_wq peer_wq; + wait_queue_t peer_wake; }; static inline struct unix_sock *unix_sk(const struct sock *sk) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 955ec152cb71..4e95bdf973d9 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -326,6 +326,118 @@ found: return s; } +/* Support code for asymmetrically connected dgram sockets + * + * If a datagram socket is connected to a socket not itself connected + * to the first socket (eg, /dev/log), clients may only enqueue more + * messages if the present receive queue of the server socket is not + * "too large". This means there's a second writeability condition + * poll and sendmsg need to test. The dgram recv code will do a wake + * up on the peer_wait wait queue of a socket upon reception of a + * datagram which needs to be propagated to sleeping would-be writers + * since these might not have sent anything so far. This can't be + * accomplished via poll_wait because the lifetime of the server + * socket might be less than that of its clients if these break their + * association with it or if the server socket is closed while clients + * are still connected to it and there's no way to inform "a polling + * implementation" that it should let go of a certain wait queue + * + * In order to propagate a wake up, a wait_queue_t of the client + * socket is enqueued on the peer_wait queue of the server socket + * whose wake function does a wake_up on the ordinary client socket + * wait queue. This connection is established whenever a write (or + * poll for write) hit the flow control condition and broken when the + * association to the server socket is dissolved or after a wake up + * was relayed. + */ + +static int unix_dgram_peer_wake_relay(wait_queue_t *q, unsigned mode, int flags, + void *key) +{ + struct unix_sock *u; + wait_queue_head_t *u_sleep; + + u = container_of(q, struct unix_sock, peer_wake); + + __remove_wait_queue(&unix_sk(u->peer_wake.private)->peer_wait, + q); + u->peer_wake.private = NULL; + + /* relaying can only happen while the wq still exists */ + u_sleep = sk_sleep(&u->sk); + if (u_sleep) + wake_up_interruptible_poll(u_sleep, key); + + return 0; +} + +static int unix_dgram_peer_wake_connect(struct sock *sk, struct sock *other) +{ + struct unix_sock *u, *u_other; + int rc; + + u = unix_sk(sk); + u_other = unix_sk(other); + rc = 0; + spin_lock(&u_other->peer_wait.lock); + + if (!u->peer_wake.private) { + u->peer_wake.private = other; + __add_wait_queue(&u_other->peer_wait, &u->peer_wake); + + rc = 1; + } + + spin_unlock(&u_other->peer_wait.lock); + return rc; +} + +static void unix_dgram_peer_wake_disconnect(struct sock *sk, + struct sock *other) +{ + struct unix_sock *u, *u_other; + + u = unix_sk(sk); + u_other = unix_sk(other); + spin_lock(&u_other->peer_wait.lock); + + if (u->peer_wake.private == other) { + __remove_wait_queue(&u_other->peer_wait, &u->peer_wake); + u->peer_wake.private = NULL; + } + + spin_unlock(&u_other->peer_wait.lock); +} + +static void unix_dgram_peer_wake_disconnect_wakeup(struct sock *sk, + struct sock *other) +{ + unix_dgram_peer_wake_disconnect(sk, other); + wake_up_interruptible_poll(sk_sleep(sk), + POLLOUT | + POLLWRNORM | + POLLWRBAND); +} + +/* preconditions: + * - unix_peer(sk) == other + * - association is stable + */ +static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other) +{ + int connected; + + connected = unix_dgram_peer_wake_connect(sk, other); + + if (unix_recvq_full(other)) + return 1; + + if (connected) + unix_dgram_peer_wake_disconnect(sk, other); + + return 0; +} + static int unix_writable(const struct sock *sk) { return sk->sk_state != TCP_LISTEN && @@ -431,6 +543,8 @@ static void unix_release_sock(struct sock *sk, int embrion) skpair->sk_state_change(skpair); sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP); } + + unix_dgram_peer_wake_disconnect(sk, skpair); sock_put(skpair); /* It may now die */ unix_peer(sk) = NULL; } @@ -666,6 +780,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern) INIT_LIST_HEAD(&u->link); mutex_init(&u->readlock); /* single task reading lock */ init_waitqueue_head(&u->peer_wait); + init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay); unix_insert_socket(unix_sockets_unbound(sk), sk); out: if (sk == NULL) @@ -1033,6 +1148,8 @@ restart: if (unix_peer(sk)) { struct sock *old_peer = unix_peer(sk); unix_peer(sk) = other; + unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer); + unix_state_double_unlock(sk, other); if (other != old_peer) @@ -1472,6 +1589,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, struct scm_cookie scm; int max_level; int data_len = 0; + int sk_locked; wait_for_unix_gc(); err = scm_send(sock, msg, &scm, false); @@ -1550,12 +1668,14 @@ restart: goto out_free; } + sk_locked = 0; unix_state_lock(other); +restart_locked: err = -EPERM; if (!unix_may_send(sk, other)) goto out_unlock; - if (sock_flag(other, SOCK_DEAD)) { + if (unlikely(sock_flag(other, SOCK_DEAD))) { /* * Check with 1003.1g - what should * datagram error @@ -1563,10 +1683,14 @@ restart: unix_state_unlock(other); sock_put(other); + if (!sk_locked) + unix_state_lock(sk); + err = 0; - unix_state_lock(sk); if (unix_peer(sk) == other) { unix_peer(sk) = NULL; + unix_dgram_peer_wake_disconnect_wakeup(sk, other); + unix_state_unlock(sk); unix_dgram_disconnected(sk, other); @@ -1592,21 +1716,38 @@ restart: goto out_unlock; } - if (unix_peer(other) != sk && unix_recvq_full(other)) { - if (!timeo) { - err = -EAGAIN; - goto out_unlock; + if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { + if (timeo) { + timeo = unix_wait_for_peer(other, timeo); + + err = sock_intr_errno(timeo); + if (signal_pending(current)) + goto out_free; + + goto restart; } - timeo = unix_wait_for_peer(other, timeo); + if (!sk_locked) { + unix_state_unlock(other); + unix_state_double_lock(sk, other); + } - err = sock_intr_errno(timeo); - if (signal_pending(current)) - goto out_free; + if (unix_peer(sk) != other || + unix_dgram_peer_wake_me(sk, other)) { + err = -EAGAIN; + sk_locked = 1; + goto out_unlock; + } - goto restart; + if (!sk_locked) { + sk_locked = 1; + goto restart_locked; + } } + if (unlikely(sk_locked)) + unix_state_unlock(sk); + if (sock_flag(other, SOCK_RCVTSTAMP)) __net_timestamp(skb); maybe_add_creds(skb, sock, other); @@ -1620,6 +1761,8 @@ restart: return len; out_unlock: + if (sk_locked) + unix_state_unlock(sk); unix_state_unlock(other); out_free: kfree_skb(skb); @@ -2476,14 +2619,16 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock, return mask; writable = unix_writable(sk); - other = unix_peer_get(sk); - if (other) { - if (unix_peer(other) != sk) { - sock_poll_wait(file, &unix_sk(other)->peer_wait, wait); - if (unix_recvq_full(other)) - writable = 0; - } - sock_put(other); + if (writable) { + unix_state_lock(sk); + + other = unix_peer(sk); + if (other && unix_peer(other) != sk && + unix_recvq_full(other) && + unix_dgram_peer_wake_me(sk, other)) + writable = 0; + + unix_state_unlock(sk); } if (writable) -- cgit v1.2.3 From 1ce0bf50ae2233c7115a18c0c623662d177b434c Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 26 Nov 2015 13:55:39 +0800 Subject: net: Generalise wq_has_sleeper helper 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 --- crypto/algif_aead.c | 4 ++-- crypto/algif_skcipher.c | 4 ++-- include/linux/wait.h | 21 +++++++++++++++++++++ include/net/sock.h | 15 +++++---------- net/atm/common.c | 4 ++-- net/core/sock.c | 8 ++++---- net/core/stream.c | 2 +- net/dccp/output.c | 2 +- net/iucv/af_iucv.c | 2 +- net/rxrpc/af_rxrpc.c | 2 +- net/sctp/socket.c | 2 +- net/tipc/socket.c | 4 ++-- net/unix/af_unix.c | 2 +- 13 files changed, 44 insertions(+), 28 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c index 0aa6fdfb448a..fb99f30849d2 100644 --- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -106,7 +106,7 @@ static void aead_wmem_wakeup(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLRDNORM | POLLRDBAND); @@ -157,7 +157,7 @@ static void aead_data_wakeup(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLRDNORM | POLLRDBAND); diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index af31a0ee4057..0e6702e41472 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -238,7 +238,7 @@ static void skcipher_wmem_wakeup(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLRDNORM | POLLRDBAND); @@ -288,7 +288,7 @@ static void skcipher_data_wakeup(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLRDNORM | POLLRDBAND); diff --git a/include/linux/wait.h b/include/linux/wait.h index 1e1bf9f963a9..6aa09a875fbd 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -107,6 +107,27 @@ static inline int waitqueue_active(wait_queue_head_t *q) return !list_empty(&q->task_list); } +/** + * wq_has_sleeper - check if there are any waiting processes + * @wq: wait queue head + * + * Returns true if wq has waiting processes + * + * Please refer to the comment for waitqueue_active. + */ +static inline bool wq_has_sleeper(wait_queue_head_t *wq) +{ + /* + * We need to be sure we are in sync with the + * add_wait_queue modifications to the wait queue. + * + * This memory barrier should be paired with one on the + * waiting side. + */ + smp_mb(); + return waitqueue_active(wq); +} + extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait); extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); diff --git a/include/net/sock.h b/include/net/sock.h index 7f89e4ba18d1..62d35afcb3ac 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -58,6 +58,7 @@ #include #include #include +#include #include #include @@ -1879,12 +1880,12 @@ static inline bool sk_has_allocations(const struct sock *sk) } /** - * wq_has_sleeper - check if there are any waiting processes + * skwq_has_sleeper - check if there are any waiting processes * @wq: struct socket_wq * * Returns true if socket_wq has waiting processes * - * The purpose of the wq_has_sleeper and sock_poll_wait is to wrap the memory + * The purpose of the skwq_has_sleeper and sock_poll_wait is to wrap the memory * barrier call. They were added due to the race found within the tcp code. * * Consider following tcp code paths: @@ -1910,15 +1911,9 @@ static inline bool sk_has_allocations(const struct sock *sk) * data on the socket. * */ -static inline bool wq_has_sleeper(struct socket_wq *wq) +static inline bool skwq_has_sleeper(struct socket_wq *wq) { - /* We need to be sure we are in sync with the - * add_wait_queue modifications to the wait queue. - * - * This memory barrier is paired in the sock_poll_wait. - */ - smp_mb(); - return wq && waitqueue_active(&wq->wait); + return wq && wq_has_sleeper(&wq->wait); } /** diff --git a/net/atm/common.c b/net/atm/common.c index 49a872db7e42..6dc12305799e 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -96,7 +96,7 @@ static void vcc_def_wakeup(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up(&wq->wait); rcu_read_unlock(); } @@ -117,7 +117,7 @@ static void vcc_write_space(struct sock *sk) if (vcc_writable(sk)) { wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible(&wq->wait); sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); diff --git a/net/core/sock.c b/net/core/sock.c index 1e4dd54bfb5a..2769bd3a4d7c 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2283,7 +2283,7 @@ static void sock_def_wakeup(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_all(&wq->wait); rcu_read_unlock(); } @@ -2294,7 +2294,7 @@ static void sock_def_error_report(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_poll(&wq->wait, POLLERR); sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR); rcu_read_unlock(); @@ -2306,7 +2306,7 @@ static void sock_def_readable(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND); sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); @@ -2324,7 +2324,7 @@ static void sock_def_write_space(struct sock *sk) */ if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf) { wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLWRNORM | POLLWRBAND); diff --git a/net/core/stream.c b/net/core/stream.c index d70f77a0c889..8ff9d63b4265 100644 --- a/net/core/stream.c +++ b/net/core/stream.c @@ -35,7 +35,7 @@ void sk_stream_write_space(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_poll(&wq->wait, POLLOUT | POLLWRNORM | POLLWRBAND); if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN)) diff --git a/net/dccp/output.c b/net/dccp/output.c index 4ce912e691d0..b66c84db0766 100644 --- a/net/dccp/output.c +++ b/net/dccp/output.c @@ -201,7 +201,7 @@ void dccp_write_space(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible(&wq->wait); /* Should agree with poll, otherwise some programs break */ if (sock_writeable(sk)) diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index fcb2752419c6..4f0aa91470c6 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -303,7 +303,7 @@ static void iucv_sock_wake_msglim(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_all(&wq->wait); sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); rcu_read_unlock(); diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c index 1f8a144a5dc2..7e2d1057d8bc 100644 --- a/net/rxrpc/af_rxrpc.c +++ b/net/rxrpc/af_rxrpc.c @@ -67,7 +67,7 @@ static void rxrpc_write_space(struct sock *sk) if (rxrpc_writable(sk)) { struct socket_wq *wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible(&wq->wait); sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); } diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 897c01c029ca..ec10b66354b8 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -6978,7 +6978,7 @@ void sctp_data_ready(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLRDNORM | POLLRDBAND); sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 552dbaba9cf3..525acf6dd1c6 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -1492,7 +1492,7 @@ static void tipc_write_space(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLWRNORM | POLLWRBAND); rcu_read_unlock(); @@ -1509,7 +1509,7 @@ static void tipc_data_ready(struct sock *sk) rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLRDNORM | POLLRDBAND); rcu_read_unlock(); diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 955ec152cb71..efb706e1d1c0 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -339,7 +339,7 @@ static void unix_write_space(struct sock *sk) rcu_read_lock(); if (unix_writable(sk)) { wq = rcu_dereference(sk->sk_wq); - if (wq_has_sleeper(wq)) + if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLWRNORM | POLLWRBAND); sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); -- cgit v1.2.3 From 9490f886b192964796285907d777ff00fba1fa0f Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Thu, 26 Nov 2015 12:08:18 +0100 Subject: af-unix: passcred support for sendpage 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 --- net/unix/af_unix.c | 79 +++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 64 insertions(+), 15 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 4e95bdf973d9..6ced74690eee 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1551,6 +1551,14 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen return err; } +static bool unix_passcred_enabled(const struct socket *sock, + const struct sock *other) +{ + return test_bit(SOCK_PASSCRED, &sock->flags) || + !other->sk_socket || + test_bit(SOCK_PASSCRED, &other->sk_socket->flags); +} + /* * Some apps rely on write() giving SCM_CREDENTIALS * We include credentials if source or destination socket @@ -1561,14 +1569,41 @@ static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock, { if (UNIXCB(skb).pid) return; - if (test_bit(SOCK_PASSCRED, &sock->flags) || - !other->sk_socket || - test_bit(SOCK_PASSCRED, &other->sk_socket->flags)) { + if (unix_passcred_enabled(sock, other)) { UNIXCB(skb).pid = get_pid(task_tgid(current)); current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid); } } +static int maybe_init_creds(struct scm_cookie *scm, + struct socket *socket, + const struct sock *other) +{ + int err; + struct msghdr msg = { .msg_controllen = 0 }; + + err = scm_send(socket, &msg, scm, false); + if (err) + return err; + + if (unix_passcred_enabled(socket, other)) { + scm->pid = get_pid(task_tgid(current)); + current_uid_gid(&scm->creds.uid, &scm->creds.gid); + } + return err; +} + +static bool unix_skb_scm_eq(struct sk_buff *skb, + struct scm_cookie *scm) +{ + const struct unix_skb_parms *u = &UNIXCB(skb); + + return u->pid == scm->pid && + uid_eq(u->uid, scm->creds.uid) && + gid_eq(u->gid, scm->creds.gid) && + unix_secdata_eq(scm, skb); +} + /* * Send AF_UNIX data. */ @@ -1884,8 +1919,10 @@ out_err: static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page, int offset, size_t size, int flags) { - int err = 0; - bool send_sigpipe = true; + int err; + bool send_sigpipe = false; + bool init_scm = true; + struct scm_cookie scm; struct sock *other, *sk = socket->sk; struct sk_buff *skb, *newskb = NULL, *tail = NULL; @@ -1903,7 +1940,7 @@ alloc_skb: newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT, &err, 0); if (!newskb) - return err; + goto err; } /* we must acquire readlock as we modify already present @@ -1912,12 +1949,12 @@ alloc_skb: err = mutex_lock_interruptible(&unix_sk(other)->readlock); if (err) { err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS; - send_sigpipe = false; goto err; } if (sk->sk_shutdown & SEND_SHUTDOWN) { err = -EPIPE; + send_sigpipe = true; goto err_unlock; } @@ -1926,17 +1963,27 @@ alloc_skb: if (sock_flag(other, SOCK_DEAD) || other->sk_shutdown & RCV_SHUTDOWN) { err = -EPIPE; + send_sigpipe = true; goto err_state_unlock; } + if (init_scm) { + err = maybe_init_creds(&scm, socket, other); + if (err) + goto err_state_unlock; + init_scm = false; + } + skb = skb_peek_tail(&other->sk_receive_queue); if (tail && tail == skb) { skb = newskb; - } else if (!skb) { - if (newskb) + } else if (!skb || !unix_skb_scm_eq(skb, &scm)) { + if (newskb) { skb = newskb; - else + } else { + tail = skb; goto alloc_skb; + } } else if (newskb) { /* this is fast path, we don't necessarily need to * call to kfree_skb even though with newskb == NULL @@ -1957,6 +2004,9 @@ alloc_skb: atomic_add(size, &sk->sk_wmem_alloc); if (newskb) { + err = unix_scm_to_skb(&scm, skb, false); + if (err) + goto err_state_unlock; spin_lock(&other->sk_receive_queue.lock); __skb_queue_tail(&other->sk_receive_queue, newskb); spin_unlock(&other->sk_receive_queue.lock); @@ -1966,7 +2016,7 @@ alloc_skb: mutex_unlock(&unix_sk(other)->readlock); other->sk_data_ready(other); - + scm_destroy(&scm); return size; err_state_unlock: @@ -1977,6 +2027,8 @@ err: kfree_skb(newskb); if (send_sigpipe && !(flags & MSG_NOSIGNAL)) send_sig(SIGPIPE, current, 0); + if (!init_scm) + scm_destroy(&scm); return err; } @@ -2280,10 +2332,7 @@ unlock: if (check_creds) { /* Never glue messages from different writers */ - if ((UNIXCB(skb).pid != scm.pid) || - !uid_eq(UNIXCB(skb).uid, scm.creds.uid) || - !gid_eq(UNIXCB(skb).gid, scm.creds.gid) || - !unix_secdata_eq(&scm, skb)) + if (!unix_skb_scm_eq(skb, &scm)) break; } else if (test_bit(SOCK_PASSCRED, &sock->flags)) { /* Copy credentials */ -- cgit v1.2.3 From 77b75f4d8cf105b599beef38724f8171e557919d Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Thu, 26 Nov 2015 19:23:15 +0000 Subject: unix: use wq_has_sleeper in unix_dgram_recvmsg 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 --- net/unix/af_unix.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index efb706e1d1c0..ac011b97097d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1914,8 +1914,10 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, goto out_unlock; } - wake_up_interruptible_sync_poll(&u->peer_wait, - POLLOUT | POLLWRNORM | POLLWRBAND); + if (wq_has_sleeper(&u->peer_wait)) + wake_up_interruptible_sync_poll(&u->peer_wait, + POLLOUT | POLLWRNORM | + POLLWRBAND); if (msg->msg_name) unix_copy_addr(msg, skb->sk); -- cgit v1.2.3 From 9cd3e072b0be17446e37d7414eac8a3499e0601e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 29 Nov 2015 20:03:10 -0800 Subject: net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA 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 --- crypto/algif_aead.c | 4 ++-- crypto/algif_skcipher.c | 6 +++--- drivers/net/macvtap.c | 4 ++-- drivers/net/tun.c | 4 ++-- fs/dlm/lowcomms.c | 4 ++-- include/linux/net.h | 6 +++--- include/net/sock.h | 10 ++++++++++ net/bluetooth/af_bluetooth.c | 6 +++--- net/caif/caif_socket.c | 4 ++-- net/core/datagram.c | 2 +- net/core/sock.c | 8 ++++---- net/core/stream.c | 4 ++-- net/dccp/proto.c | 3 +-- net/decnet/af_decnet.c | 8 ++++---- net/ipv4/tcp.c | 7 +++---- net/iucv/af_iucv.c | 2 +- net/nfc/llcp_sock.c | 2 +- net/rxrpc/ar-output.c | 2 +- net/sctp/socket.c | 2 +- net/socket.c | 4 ++-- net/sunrpc/xprtsock.c | 14 +++++++------- net/unix/af_unix.c | 6 +++--- 22 files changed, 60 insertions(+), 52 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c index 0aa6fdfb448a..6d4d4569447e 100644 --- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -125,7 +125,7 @@ static int aead_wait_for_data(struct sock *sk, unsigned flags) if (flags & MSG_DONTWAIT) return -EAGAIN; - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); for (;;) { if (signal_pending(current)) @@ -139,7 +139,7 @@ static int aead_wait_for_data(struct sock *sk, unsigned flags) } finish_wait(sk_sleep(sk), &wait); - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); return err; } diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index af31a0ee4057..ca9efe17db1a 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -212,7 +212,7 @@ static int skcipher_wait_for_wmem(struct sock *sk, unsigned flags) if (flags & MSG_DONTWAIT) return -EAGAIN; - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); for (;;) { if (signal_pending(current)) @@ -258,7 +258,7 @@ static int skcipher_wait_for_data(struct sock *sk, unsigned flags) return -EAGAIN; } - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); for (;;) { if (signal_pending(current)) @@ -272,7 +272,7 @@ static int skcipher_wait_for_data(struct sock *sk, unsigned flags) } finish_wait(sk_sleep(sk), &wait); - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); return err; } diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 54036ae0a388..0fc521941c71 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -498,7 +498,7 @@ static void macvtap_sock_write_space(struct sock *sk) wait_queue_head_t *wqueue; if (!sock_writeable(sk) || - !test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags)) + !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags)) return; wqueue = sk_sleep(sk); @@ -585,7 +585,7 @@ static unsigned int macvtap_poll(struct file *file, poll_table * wait) mask |= POLLIN | POLLRDNORM; if (sock_writeable(&q->sk) || - (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &q->sock.flags) && + (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) && sock_writeable(&q->sk))) mask |= POLLOUT | POLLWRNORM; diff --git a/drivers/net/tun.c b/drivers/net/tun.c index b1878faea397..f0db770e8b2f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1040,7 +1040,7 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) mask |= POLLIN | POLLRDNORM; if (sock_writeable(sk) || - (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags) && + (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags) && sock_writeable(sk))) mask |= POLLOUT | POLLWRNORM; @@ -1488,7 +1488,7 @@ static void tun_sock_write_space(struct sock *sk) if (!sock_writeable(sk)) return; - if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags)) + if (!test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags)) return; wqueue = sk_sleep(sk); diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c index 87e9d796cf7d..3a37bd3f9637 100644 --- a/fs/dlm/lowcomms.c +++ b/fs/dlm/lowcomms.c @@ -421,7 +421,7 @@ static void lowcomms_write_space(struct sock *sk) if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) { con->sock->sk->sk_write_pending--; - clear_bit(SOCK_ASYNC_NOSPACE, &con->sock->flags); + clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags); } if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) @@ -1448,7 +1448,7 @@ static void send_to_sock(struct connection *con) msg_flags); if (ret == -EAGAIN || ret == 0) { if (ret == -EAGAIN && - test_bit(SOCK_ASYNC_NOSPACE, &con->sock->flags) && + test_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags) && !test_and_set_bit(CF_APP_LIMITED, &con->flags)) { /* Notify TCP that we're limited by the * application window size. diff --git a/include/linux/net.h b/include/linux/net.h index 70ac5e28e6b7..f514e4dd5521 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -34,8 +34,8 @@ struct inode; struct file; struct net; -#define SOCK_ASYNC_NOSPACE 0 -#define SOCK_ASYNC_WAITDATA 1 +#define SOCKWQ_ASYNC_NOSPACE 0 +#define SOCKWQ_ASYNC_WAITDATA 1 #define SOCK_NOSPACE 2 #define SOCK_PASSCRED 3 #define SOCK_PASSSEC 4 @@ -96,7 +96,7 @@ struct socket_wq { * struct socket - general BSD socket * @state: socket state (%SS_CONNECTED, etc) * @type: socket type (%SOCK_STREAM, etc) - * @flags: socket flags (%SOCK_ASYNC_NOSPACE, etc) + * @flags: socket flags (%SOCK_NOSPACE, etc) * @ops: protocol specific socket operations * @file: File back pointer for gc * @sk: internal networking protocol agnostic socket representation diff --git a/include/net/sock.h b/include/net/sock.h index 7f89e4ba18d1..c155d09d8af4 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2005,6 +2005,16 @@ static inline unsigned long sock_wspace(struct sock *sk) return amt; } +static inline void sk_set_bit(int nr, struct sock *sk) +{ + set_bit(nr, &sk->sk_socket->flags); +} + +static inline void sk_clear_bit(int nr, struct sock *sk) +{ + clear_bit(nr, &sk->sk_socket->flags); +} + static inline void sk_wake_async(struct sock *sk, int how, int band) { if (sock_flag(sk, SOCK_FASYNC)) diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index a3bffd1ec2b4..70306cc9d814 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -271,11 +271,11 @@ static long bt_sock_data_wait(struct sock *sk, long timeo) if (signal_pending(current) || !timeo) break; - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); release_sock(sk); timeo = schedule_timeout(timeo); lock_sock(sk); - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); } __set_current_state(TASK_RUNNING); @@ -441,7 +441,7 @@ unsigned int bt_sock_poll(struct file *file, struct socket *sock, if (!test_bit(BT_SK_SUSPEND, &bt_sk(sk)->flags) && sock_writeable(sk)) mask |= POLLOUT | POLLWRNORM | POLLWRBAND; else - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); return mask; } diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c index cc858919108e..aa209b1066c9 100644 --- a/net/caif/caif_socket.c +++ b/net/caif/caif_socket.c @@ -323,7 +323,7 @@ static long caif_stream_data_wait(struct sock *sk, long timeo) !timeo) break; - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); release_sock(sk); timeo = schedule_timeout(timeo); lock_sock(sk); @@ -331,7 +331,7 @@ static long caif_stream_data_wait(struct sock *sk, long timeo) if (sock_flag(sk, SOCK_DEAD)) break; - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); } finish_wait(sk_sleep(sk), &wait); diff --git a/net/core/datagram.c b/net/core/datagram.c index 617088aee21d..d62af69ad844 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -785,7 +785,7 @@ unsigned int datagram_poll(struct file *file, struct socket *sock, if (sock_writeable(sk)) mask |= POLLOUT | POLLWRNORM | POLLWRBAND; else - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); return mask; } diff --git a/net/core/sock.c b/net/core/sock.c index 1e4dd54bfb5a..9d79569935a3 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1815,7 +1815,7 @@ static long sock_wait_for_wmem(struct sock *sk, long timeo) { DEFINE_WAIT(wait); - clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); for (;;) { if (!timeo) break; @@ -1861,7 +1861,7 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, if (sk_wmem_alloc_get(sk) < sk->sk_sndbuf) break; - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); err = -EAGAIN; if (!timeo) @@ -2048,9 +2048,9 @@ int sk_wait_data(struct sock *sk, long *timeo, const struct sk_buff *skb) DEFINE_WAIT(wait); prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); rc = sk_wait_event(sk, timeo, skb_peek_tail(&sk->sk_receive_queue) != skb); - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); finish_wait(sk_sleep(sk), &wait); return rc; } diff --git a/net/core/stream.c b/net/core/stream.c index d70f77a0c889..43309428644d 100644 --- a/net/core/stream.c +++ b/net/core/stream.c @@ -126,7 +126,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p) current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2; while (1) { - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); @@ -139,7 +139,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p) } if (signal_pending(current)) goto do_interrupted; - clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); if (sk_stream_memory_free(sk) && !vm_wait) break; diff --git a/net/dccp/proto.c b/net/dccp/proto.c index b5cf13a28009..41e65804ddf5 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -339,8 +339,7 @@ unsigned int dccp_poll(struct file *file, struct socket *sock, if (sk_stream_is_writeable(sk)) { mask |= POLLOUT | POLLWRNORM; } else { /* send SIGIO later */ - set_bit(SOCK_ASYNC_NOSPACE, - &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); /* Race breaker. If space is freed after diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c index 675cf94e04f8..eebf5ac8ce18 100644 --- a/net/decnet/af_decnet.c +++ b/net/decnet/af_decnet.c @@ -1747,9 +1747,9 @@ static int dn_recvmsg(struct socket *sock, struct msghdr *msg, size_t size, } prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); sk_wait_event(sk, &timeo, dn_data_ready(sk, queue, flags, target)); - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); finish_wait(sk_sleep(sk), &wait); } @@ -2004,10 +2004,10 @@ static int dn_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) } prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); sk_wait_event(sk, &timeo, !dn_queue_too_long(scp, queue, flags)); - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); finish_wait(sk_sleep(sk), &wait); continue; } diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index c1728771cf89..c82cca18c90f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -517,8 +517,7 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) if (sk_stream_is_writeable(sk)) { mask |= POLLOUT | POLLWRNORM; } else { /* send SIGIO later */ - set_bit(SOCK_ASYNC_NOSPACE, - &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); /* Race breaker. If space is freed after @@ -906,7 +905,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, goto out_err; } - clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); mss_now = tcp_send_mss(sk, &size_goal, flags); copied = 0; @@ -1134,7 +1133,7 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) } /* This should be in poll */ - clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); mss_now = tcp_send_mss(sk, &size_goal, flags); diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index fcb2752419c6..435608c4306d 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -1483,7 +1483,7 @@ unsigned int iucv_sock_poll(struct file *file, struct socket *sock, if (sock_writeable(sk) && iucv_below_msglim(sk)) mask |= POLLOUT | POLLWRNORM | POLLWRBAND; else - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); return mask; } diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c index b7de0da46acd..ecf0a0196f18 100644 --- a/net/nfc/llcp_sock.c +++ b/net/nfc/llcp_sock.c @@ -572,7 +572,7 @@ static unsigned int llcp_sock_poll(struct file *file, struct socket *sock, if (sock_writeable(sk) && sk->sk_state == LLCP_CONNECTED) mask |= POLLOUT | POLLWRNORM | POLLWRBAND; else - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); pr_debug("mask 0x%x\n", mask); diff --git a/net/rxrpc/ar-output.c b/net/rxrpc/ar-output.c index a40d3afe93b7..14c4e12c47b0 100644 --- a/net/rxrpc/ar-output.c +++ b/net/rxrpc/ar-output.c @@ -531,7 +531,7 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); /* this should be in poll */ - clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) return -EPIPE; diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 897c01c029ca..2353985d689c 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -6458,7 +6458,7 @@ unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait) if (sctp_writeable(sk)) { mask |= POLLOUT | POLLWRNORM; } else { - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); /* * Since the socket is not locked, the buffer * might be made available after the writeable check and diff --git a/net/socket.c b/net/socket.c index dd2c247c99e3..16be908205fc 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1072,11 +1072,11 @@ int sock_wake_async(struct socket *sock, int how, int band) } switch (how) { case SOCK_WAKE_WAITD: - if (test_bit(SOCK_ASYNC_WAITDATA, &sock->flags)) + if (test_bit(SOCKWQ_ASYNC_WAITDATA, &sock->flags)) break; goto call_kill; case SOCK_WAKE_SPACE: - if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags)) + if (!test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sock->flags)) break; /* fall through */ case SOCK_WAKE_IO: diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 1d1a70498910..2ffaf6a79499 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -398,7 +398,7 @@ static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, if (unlikely(!sock)) return -ENOTSOCK; - clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags); + clear_bit(SOCKWQ_ASYNC_NOSPACE, &sock->flags); if (base != 0) { addr = NULL; addrlen = 0; @@ -442,7 +442,7 @@ static void xs_nospace_callback(struct rpc_task *task) struct sock_xprt *transport = container_of(task->tk_rqstp->rq_xprt, struct sock_xprt, xprt); transport->inet->sk_write_pending--; - clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags); + clear_bit(SOCKWQ_ASYNC_NOSPACE, &transport->sock->flags); } /** @@ -467,7 +467,7 @@ static int xs_nospace(struct rpc_task *task) /* Don't race with disconnect */ if (xprt_connected(xprt)) { - if (test_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags)) { + if (test_bit(SOCKWQ_ASYNC_NOSPACE, &transport->sock->flags)) { /* * Notify TCP that we're limited by the application * window size @@ -478,7 +478,7 @@ static int xs_nospace(struct rpc_task *task) xprt_wait_for_buffer_space(task, xs_nospace_callback); } } else { - clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags); + clear_bit(SOCKWQ_ASYNC_NOSPACE, &transport->sock->flags); ret = -ENOTCONN; } @@ -626,7 +626,7 @@ process_status: case -EPERM: /* When the server has died, an ICMP port unreachable message * prompts ECONNREFUSED. */ - clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags); + clear_bit(SOCKWQ_ASYNC_NOSPACE, &transport->sock->flags); } return status; @@ -715,7 +715,7 @@ static int xs_tcp_send_request(struct rpc_task *task) case -EADDRINUSE: case -ENOBUFS: case -EPIPE: - clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags); + clear_bit(SOCKWQ_ASYNC_NOSPACE, &transport->sock->flags); } return status; @@ -1618,7 +1618,7 @@ static void xs_write_space(struct sock *sk) if (unlikely(!(xprt = xprt_from_sock(sk)))) return; - if (test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags) == 0) + if (test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sock->flags) == 0) return; xprt_write_space(xprt); diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 6ced74690eee..45aebd966978 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2191,7 +2191,7 @@ static long unix_stream_data_wait(struct sock *sk, long timeo, !timeo) break; - set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); unix_state_unlock(sk); timeo = freezable_schedule_timeout(timeo); unix_state_lock(sk); @@ -2199,7 +2199,7 @@ static long unix_stream_data_wait(struct sock *sk, long timeo, if (sock_flag(sk, SOCK_DEAD)) break; - clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); } finish_wait(sk_sleep(sk), &wait); @@ -2683,7 +2683,7 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock, if (writable) mask |= POLLOUT | POLLWRNORM | POLLWRBAND; else - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); return mask; } -- cgit v1.2.3 From 64874280889e7c0b2c9266705363627d4c92cf01 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Sun, 6 Dec 2015 21:11:38 +0000 Subject: af_unix: fix unix_dgram_recvmsg entry locking 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 --- net/unix/af_unix.c | 35 ++++++++++++++++++++--------------- 1 file changed, 20 insertions(+), 15 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 502e572af3fd..1c3c1f3a3ec4 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2078,8 +2078,8 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, struct scm_cookie scm; struct sock *sk = sock->sk; struct unix_sock *u = unix_sk(sk); - int noblock = flags & MSG_DONTWAIT; - struct sk_buff *skb; + struct sk_buff *skb, *last; + long timeo; int err; int peeked, skip; @@ -2087,26 +2087,32 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, if (flags&MSG_OOB) goto out; - err = mutex_lock_interruptible(&u->readlock); - if (unlikely(err)) { - /* recvmsg() in non blocking mode is supposed to return -EAGAIN - * sk_rcvtimeo is not honored by mutex_lock_interruptible() - */ - err = noblock ? -EAGAIN : -ERESTARTSYS; - goto out; - } + timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); - skip = sk_peek_offset(sk, flags); + do { + mutex_lock(&u->readlock); - skb = __skb_recv_datagram(sk, flags, &peeked, &skip, &err); - if (!skb) { + skip = sk_peek_offset(sk, flags); + skb = __skb_try_recv_datagram(sk, flags, &peeked, &skip, &err, + &last); + if (skb) + break; + + mutex_unlock(&u->readlock); + + if (err != -EAGAIN) + break; + } while (timeo && + !__skb_wait_for_more_packets(sk, &err, &timeo, last)); + + if (!skb) { /* implies readlock unlocked */ unix_state_lock(sk); /* Signal EOF on disconnected non-blocking SEQPACKET socket. */ if (sk->sk_type == SOCK_SEQPACKET && err == -EAGAIN && (sk->sk_shutdown & RCV_SHUTDOWN)) err = 0; unix_state_unlock(sk); - goto out_unlock; + goto out; } if (wq_has_sleeper(&u->peer_wait)) @@ -2164,7 +2170,6 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, out_free: skb_free_datagram(sk, skb); -out_unlock: mutex_unlock(&u->readlock); out: return err; -- cgit v1.2.3 From 3822b5c2fc62e3de8a0f33806ff279fb7df92432 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Wed, 16 Dec 2015 20:09:25 +0000 Subject: af_unix: Revert 'lock_interruptible' in stream receive code 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 --- net/unix/af_unix.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 45aebd966978..a4631477cedf 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2256,14 +2256,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state) /* Lock the socket to prevent queue disordering * while sleeps in memcpy_tomsg */ - err = mutex_lock_interruptible(&u->readlock); - if (unlikely(err)) { - /* recvmsg() in non blocking mode is supposed to return -EAGAIN - * sk_rcvtimeo is not honored by mutex_lock_interruptible() - */ - err = noblock ? -EAGAIN : -ERESTARTSYS; - goto out; - } + mutex_lock(&u->readlock); if (flags & MSG_PEEK) skip = sk_peek_offset(sk, flags); @@ -2307,12 +2300,12 @@ again: timeo = unix_stream_data_wait(sk, timeo, last, last_len); - if (signal_pending(current) || - mutex_lock_interruptible(&u->readlock)) { + if (signal_pending(current)) { err = sock_intr_errno(timeo); goto out; } + mutex_lock(&u->readlock); continue; unlock: unix_state_unlock(sk); -- cgit v1.2.3 From c845acb324aa85a39650a14e7696982ceea75dc1 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Sun, 3 Jan 2016 18:56:38 +0000 Subject: af_unix: Fix splice-bind deadlock On 2015/11/06, Dmitry Vyukov reported a deadlock involving the splice system call and AF_UNIX sockets, http://lists.openwall.net/netdev/2015/11/06/24 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, http://lists.openwall.net/netdev/2015/11/10/4 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 --- net/unix/af_unix.c | 66 +++++++++++++++++++++++++++++++++--------------------- 1 file changed, 40 insertions(+), 26 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index a4631477cedf..ef05cd9403d4 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -953,32 +953,20 @@ fail: return NULL; } -static int unix_mknod(const char *sun_path, umode_t mode, struct path *res) +static int unix_mknod(struct dentry *dentry, struct path *path, umode_t mode, + struct path *res) { - struct dentry *dentry; - struct path path; - int err = 0; - /* - * Get the parent directory, calculate the hash for last - * component. - */ - dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0); - err = PTR_ERR(dentry); - if (IS_ERR(dentry)) - return err; + int err; - /* - * All right, let's create it. - */ - err = security_path_mknod(&path, dentry, mode, 0); + err = security_path_mknod(path, dentry, mode, 0); if (!err) { - err = vfs_mknod(d_inode(path.dentry), dentry, mode, 0); + err = vfs_mknod(d_inode(path->dentry), dentry, mode, 0); if (!err) { - res->mnt = mntget(path.mnt); + res->mnt = mntget(path->mnt); res->dentry = dget(dentry); } } - done_path_create(&path, dentry); + return err; } @@ -989,10 +977,12 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) struct unix_sock *u = unix_sk(sk); struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr; char *sun_path = sunaddr->sun_path; - int err; + int err, name_err; unsigned int hash; struct unix_address *addr; struct hlist_head *list; + struct path path; + struct dentry *dentry; err = -EINVAL; if (sunaddr->sun_family != AF_UNIX) @@ -1008,14 +998,34 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) goto out; addr_len = err; + name_err = 0; + dentry = NULL; + if (sun_path[0]) { + /* Get the parent directory, calculate the hash for last + * component. + */ + dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0); + + if (IS_ERR(dentry)) { + /* delay report until after 'already bound' check */ + name_err = PTR_ERR(dentry); + dentry = NULL; + } + } + err = mutex_lock_interruptible(&u->readlock); if (err) - goto out; + goto out_path; err = -EINVAL; if (u->addr) goto out_up; + if (name_err) { + err = name_err == -EEXIST ? -EADDRINUSE : name_err; + goto out_up; + } + err = -ENOMEM; addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL); if (!addr) @@ -1026,11 +1036,11 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) addr->hash = hash ^ sk->sk_type; atomic_set(&addr->refcnt, 1); - if (sun_path[0]) { - struct path path; + if (dentry) { + struct path u_path; umode_t mode = S_IFSOCK | (SOCK_INODE(sock)->i_mode & ~current_umask()); - err = unix_mknod(sun_path, mode, &path); + err = unix_mknod(dentry, &path, mode, &u_path); if (err) { if (err == -EEXIST) err = -EADDRINUSE; @@ -1038,9 +1048,9 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) goto out_up; } addr->hash = UNIX_HASH_SIZE; - hash = d_backing_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE-1); + hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1); spin_lock(&unix_table_lock); - u->path = path; + u->path = u_path; list = &unix_socket_table[hash]; } else { spin_lock(&unix_table_lock); @@ -1063,6 +1073,10 @@ out_unlock: spin_unlock(&unix_table_lock); out_up: mutex_unlock(&u->readlock); +out_path: + if (dentry) + done_path_create(&path, dentry); + out: return err; } -- cgit v1.2.3 From 712f4aad406bb1ed67f3f98d04c044191f0ff593 Mon Sep 17 00:00:00 2001 From: willy tarreau Date: Sun, 10 Jan 2016 07:54:56 +0100 Subject: unix: properly account for FDs passed over unix sockets 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: socketpair@gmail.com 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 --- include/linux/sched.h | 1 + net/unix/af_unix.c | 24 ++++++++++++++++++++---- net/unix/garbage.c | 13 ++++++++----- 3 files changed, 29 insertions(+), 9 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/include/linux/sched.h b/include/linux/sched.h index edad7a43edea..fbf25f19b3b5 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -830,6 +830,7 @@ struct user_struct { unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */ #endif unsigned long locked_shm; /* How many pages of mlocked shm ? */ + unsigned long unix_inflight; /* How many files in flight in unix sockets */ #ifdef CONFIG_KEYS struct key *uid_keyring; /* UID specific keyring */ diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index ef05cd9403d4..e3f85bc8b135 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1513,6 +1513,21 @@ static void unix_destruct_scm(struct sk_buff *skb) sock_wfree(skb); } +/* + * The "user->unix_inflight" variable is protected by the garbage + * collection lock, and we just read it locklessly here. If you go + * over the limit, there might be a tiny race in actually noticing + * it across threads. Tough. + */ +static inline bool too_many_unix_fds(struct task_struct *p) +{ + struct user_struct *user = current_user(); + + if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE))) + return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN); + return false; +} + #define MAX_RECURSION_LEVEL 4 static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb) @@ -1521,6 +1536,9 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb) unsigned char max_level = 0; int unix_sock_count = 0; + if (too_many_unix_fds(current)) + return -ETOOMANYREFS; + for (i = scm->fp->count - 1; i >= 0; i--) { struct sock *sk = unix_get_socket(scm->fp->fp[i]); @@ -1542,10 +1560,8 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb) if (!UNIXCB(skb).fp) return -ENOMEM; - if (unix_sock_count) { - for (i = scm->fp->count - 1; i >= 0; i--) - unix_inflight(scm->fp->fp[i]); - } + for (i = scm->fp->count - 1; i >= 0; i--) + unix_inflight(scm->fp->fp[i]); return max_level; } diff --git a/net/unix/garbage.c b/net/unix/garbage.c index a73a226f2d33..8fcdc2283af5 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -120,11 +120,11 @@ void unix_inflight(struct file *fp) { struct sock *s = unix_get_socket(fp); + spin_lock(&unix_gc_lock); + if (s) { struct unix_sock *u = unix_sk(s); - spin_lock(&unix_gc_lock); - if (atomic_long_inc_return(&u->inflight) == 1) { BUG_ON(!list_empty(&u->link)); list_add_tail(&u->link, &gc_inflight_list); @@ -132,25 +132,28 @@ void unix_inflight(struct file *fp) BUG_ON(list_empty(&u->link)); } unix_tot_inflight++; - spin_unlock(&unix_gc_lock); } + fp->f_cred->user->unix_inflight++; + spin_unlock(&unix_gc_lock); } void unix_notinflight(struct file *fp) { struct sock *s = unix_get_socket(fp); + spin_lock(&unix_gc_lock); + if (s) { struct unix_sock *u = unix_sk(s); - spin_lock(&unix_gc_lock); BUG_ON(list_empty(&u->link)); if (atomic_long_dec_and_test(&u->inflight)) list_del_init(&u->link); unix_tot_inflight--; - spin_unlock(&unix_gc_lock); } + fp->f_cred->user->unix_inflight--; + spin_unlock(&unix_gc_lock); } static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *), -- cgit v1.2.3