From 26bfb8b57063f52b867f9b6c8d1742fcb5bd656c Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:27 -0700 Subject: af_unix: Set sk->sk_state under unix_state_lock() for truly disconencted peer. When a SOCK_DGRAM socket connect()s to another socket, the both sockets' sk->sk_state are changed to TCP_ESTABLISHED so that we can register them to BPF SOCKMAP. When the socket disconnects from the peer by connect(AF_UNSPEC), the state is set back to TCP_CLOSE. Then, the peer's state is also set to TCP_CLOSE, but the update is done locklessly and unconditionally. Let's say socket A connect()ed to B, B connect()ed to C, and A disconnects from B. After the first two connect()s, all three sockets' sk->sk_state are TCP_ESTABLISHED: $ ss -xa Netid State Recv-Q Send-Q Local Address:Port Peer Address:PortProcess u_dgr ESTAB 0 0 @A 641 * 642 u_dgr ESTAB 0 0 @B 642 * 643 u_dgr ESTAB 0 0 @C 643 * 0 And after the disconnect, B's state is TCP_CLOSE even though it's still connected to C and C's state is TCP_ESTABLISHED. $ ss -xa Netid State Recv-Q Send-Q Local Address:Port Peer Address:PortProcess u_dgr UNCONN 0 0 @A 641 * 0 u_dgr UNCONN 0 0 @B 642 * 643 u_dgr ESTAB 0 0 @C 643 * 0 In this case, we cannot register B to SOCKMAP. So, when a socket disconnects from the peer, we should not set TCP_CLOSE to the peer if the peer is connected to yet another socket, and this must be done under unix_state_lock(). Note that we use WRITE_ONCE() for sk->sk_state as there are many lockless readers. These data-races will be fixed in the following patches. Fixes: 83301b5367a9 ("af_unix: Set TCP_ESTABLISHED for datagram sockets too") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 10 ++++++++-- 1 file changed, 8 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 25b49efc0926..b162164b7a42 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -570,7 +570,6 @@ static void unix_dgram_disconnected(struct sock *sk, struct sock *other) sk_error_report(other); } } - other->sk_state = TCP_CLOSE; } static void unix_sock_destructor(struct sock *sk) @@ -1424,8 +1423,15 @@ restart: unix_state_double_unlock(sk, other); - if (other != old_peer) + if (other != old_peer) { unix_dgram_disconnected(sk, old_peer); + + unix_state_lock(old_peer); + if (!unix_peer(old_peer)) + WRITE_ONCE(old_peer->sk_state, TCP_CLOSE); + unix_state_unlock(old_peer); + } + sock_put(old_peer); } else { unix_peer(sk) = other; -- cgit From 942238f9735a4a4ebf8274b218d9a910158941d1 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:28 -0700 Subject: af_unix: Annodate data-races around sk->sk_state for writers. sk->sk_state is changed under unix_state_lock(), but it's read locklessly in many places. This patch adds WRITE_ONCE() on the writer side. We will add READ_ONCE() to the lockless readers in the following patches. Fixes: 83301b5367a9 ("af_unix: Set TCP_ESTABLISHED for datagram sockets too") Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index b162164b7a42..424d021a4d7d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -616,7 +616,7 @@ static void unix_release_sock(struct sock *sk, int embrion) u->path.dentry = NULL; u->path.mnt = NULL; state = sk->sk_state; - sk->sk_state = TCP_CLOSE; + WRITE_ONCE(sk->sk_state, TCP_CLOSE); skpair = unix_peer(sk); unix_peer(sk) = NULL; @@ -738,7 +738,8 @@ static int unix_listen(struct socket *sock, int backlog) if (backlog > sk->sk_max_ack_backlog) wake_up_interruptible_all(&u->peer_wait); sk->sk_max_ack_backlog = backlog; - sk->sk_state = TCP_LISTEN; + WRITE_ONCE(sk->sk_state, TCP_LISTEN); + /* set credentials so connect can copy them */ init_peercred(sk); err = 0; @@ -1401,7 +1402,8 @@ restart: if (err) goto out_unlock; - sk->sk_state = other->sk_state = TCP_ESTABLISHED; + WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED); + WRITE_ONCE(other->sk_state, TCP_ESTABLISHED); } else { /* * 1003.1g breaking connected state with AF_UNSPEC @@ -1418,7 +1420,7 @@ restart: unix_peer(sk) = other; if (!other) - sk->sk_state = TCP_CLOSE; + WRITE_ONCE(sk->sk_state, TCP_CLOSE); unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer); unix_state_double_unlock(sk, other); @@ -1639,7 +1641,7 @@ restart: copy_peercred(sk, other); sock->state = SS_CONNECTED; - sk->sk_state = TCP_ESTABLISHED; + WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED); sock_hold(newsk); smp_mb__after_atomic(); /* sock_hold() does an atomic_inc() */ @@ -2050,7 +2052,7 @@ restart_locked: unix_peer(sk) = NULL; unix_dgram_peer_wake_disconnect_wakeup(sk, other); - sk->sk_state = TCP_CLOSE; + WRITE_ONCE(sk->sk_state, TCP_CLOSE); unix_state_unlock(sk); unix_dgram_disconnected(sk, other); -- cgit From 3a0f38eb285c8c2eead4b3230c7ac2983707599d Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:29 -0700 Subject: af_unix: Annotate data-race of sk->sk_state in unix_inq_len(). ioctl(SIOCINQ) calls unix_inq_len() that checks sk->sk_state first and returns -EINVAL if it's TCP_LISTEN. Then, for SOCK_STREAM sockets, unix_inq_len() returns the number of bytes in recvq. However, unix_inq_len() does not hold unix_state_lock(), and the concurrent listen() might change the state after checking sk->sk_state. If the race occurs, 0 is returned for the listener, instead of -EINVAL, because the length of skb with embryo is 0. We could hold unix_state_lock() in unix_inq_len(), but it's overkill given the result is true for pre-listen() TCP_CLOSE state. So, let's use READ_ONCE() for sk->sk_state in unix_inq_len(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 424d021a4d7d..b37b53767b29 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -3017,7 +3017,7 @@ long unix_inq_len(struct sock *sk) struct sk_buff *skb; long amount = 0; - if (sk->sk_state == TCP_LISTEN) + if (READ_ONCE(sk->sk_state) == TCP_LISTEN) return -EINVAL; spin_lock(&sk->sk_receive_queue.lock); -- cgit From eb0718fb3e97ad0d6f4529b810103451c90adf94 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:30 -0700 Subject: af_unix: Annotate data-races around sk->sk_state in unix_write_space() and poll(). unix_poll() and unix_dgram_poll() read sk->sk_state locklessly and calls unix_writable() which also reads sk->sk_state without holding unix_state_lock(). Let's use READ_ONCE() in unix_poll() and unix_dgram_poll() and pass it to unix_writable(). While at it, we remove TCP_SYN_SENT check in unix_dgram_poll() as that state does not exist for AF_UNIX socket since the code was added. Fixes: 1586a5877db9 ("af_unix: do not report POLLOUT on listeners") Fixes: 3c73419c09a5 ("af_unix: fix 'poll for write'/ connected DGRAM sockets") Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index b37b53767b29..3bacf47cb94d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -530,9 +530,9 @@ static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other) return 0; } -static int unix_writable(const struct sock *sk) +static int unix_writable(const struct sock *sk, unsigned char state) { - return sk->sk_state != TCP_LISTEN && + return state != TCP_LISTEN && (refcount_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf; } @@ -541,7 +541,7 @@ static void unix_write_space(struct sock *sk) struct socket_wq *wq; rcu_read_lock(); - if (unix_writable(sk)) { + if (unix_writable(sk, READ_ONCE(sk->sk_state))) { wq = rcu_dereference(sk->sk_wq); if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, @@ -3129,12 +3129,14 @@ static int unix_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned lon static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wait) { struct sock *sk = sock->sk; + unsigned char state; __poll_t mask; u8 shutdown; sock_poll_wait(file, sock, wait); mask = 0; shutdown = READ_ONCE(sk->sk_shutdown); + state = READ_ONCE(sk->sk_state); /* exceptional events? */ if (READ_ONCE(sk->sk_err)) @@ -3156,14 +3158,14 @@ static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wa /* Connection-based need to check for termination and startup */ if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) && - sk->sk_state == TCP_CLOSE) + state == TCP_CLOSE) mask |= EPOLLHUP; /* * we set writable also when the other side has shut down the * connection. This prevents stuck sockets. */ - if (unix_writable(sk)) + if (unix_writable(sk, state)) mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND; return mask; @@ -3174,12 +3176,14 @@ static __poll_t unix_dgram_poll(struct file *file, struct socket *sock, { struct sock *sk = sock->sk, *other; unsigned int writable; + unsigned char state; __poll_t mask; u8 shutdown; sock_poll_wait(file, sock, wait); mask = 0; shutdown = READ_ONCE(sk->sk_shutdown); + state = READ_ONCE(sk->sk_state); /* exceptional events? */ if (READ_ONCE(sk->sk_err) || @@ -3199,19 +3203,14 @@ static __poll_t unix_dgram_poll(struct file *file, struct socket *sock, mask |= EPOLLIN | EPOLLRDNORM; /* Connection-based need to check for termination and startup */ - if (sk->sk_type == SOCK_SEQPACKET) { - if (sk->sk_state == TCP_CLOSE) - mask |= EPOLLHUP; - /* connection hasn't started yet? */ - if (sk->sk_state == TCP_SYN_SENT) - return mask; - } + if (sk->sk_type == SOCK_SEQPACKET && state == TCP_CLOSE) + mask |= EPOLLHUP; /* No write status requested, avoid expensive OUT tests. */ if (!(poll_requested_events(wait) & (EPOLLWRBAND|EPOLLWRNORM|EPOLLOUT))) return mask; - writable = unix_writable(sk); + writable = unix_writable(sk, state); if (writable) { unix_state_lock(sk); -- cgit From a9bf9c7dc6a5899c01cb8f6e773a66315a5cd4b7 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:31 -0700 Subject: af_unix: Annotate data-race of sk->sk_state in unix_stream_connect(). As small optimisation, unix_stream_connect() prefetches the client's sk->sk_state without unix_state_lock() and checks if it's TCP_CLOSE. Later, sk->sk_state is checked again under unix_state_lock(). Let's use READ_ONCE() for the first check and TCP_CLOSE directly for the second check. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 3bacf47cb94d..84552826530d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1481,7 +1481,6 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr, struct sk_buff *skb = NULL; long timeo; int err; - int st; err = unix_validate_addr(sunaddr, addr_len); if (err) @@ -1571,9 +1570,7 @@ restart: Well, and we have to recheck the state after socket locked. */ - st = sk->sk_state; - - switch (st) { + switch (READ_ONCE(sk->sk_state)) { case TCP_CLOSE: /* This is ok... continue with connect */ break; @@ -1588,7 +1585,7 @@ restart: unix_state_lock_nested(sk, U_LOCK_SECOND); - if (sk->sk_state != st) { + if (sk->sk_state != TCP_CLOSE) { unix_state_unlock(sk); unix_state_unlock(other); sock_put(other); -- cgit From 1b536948e805aab61a48c5aa5db10c9afee880bd Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:32 -0700 Subject: af_unix: Annotate data-race of sk->sk_state in unix_accept(). Once sk->sk_state is changed to TCP_LISTEN, it never changes. unix_accept() takes the advantage and reads sk->sk_state without holding unix_state_lock(). Let's use READ_ONCE() there. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 84552826530d..4763c26ae480 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1710,7 +1710,7 @@ static int unix_accept(struct socket *sock, struct socket *newsock, goto out; arg->err = -EINVAL; - if (sk->sk_state != TCP_LISTEN) + if (READ_ONCE(sk->sk_state) != TCP_LISTEN) goto out; /* If socket state is TCP_LISTEN it cannot change (for now...), -- cgit From 8a34d4e8d9742a24f74998f45a6a98edd923319b Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:33 -0700 Subject: af_unix: Annotate data-races around sk->sk_state in sendmsg() and recvmsg(). The following functions read sk->sk_state locklessly and proceed only if the state is TCP_ESTABLISHED. * unix_stream_sendmsg * unix_stream_read_generic * unix_seqpacket_sendmsg * unix_seqpacket_recvmsg Let's use READ_ONCE() there. Fixes: a05d2ad1c1f3 ("af_unix: Only allow recv on connected seqpacket sockets.") Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 4763c26ae480..4ef9c21783a5 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2226,7 +2226,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, } if (msg->msg_namelen) { - err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP; + err = READ_ONCE(sk->sk_state) == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP; goto out_err; } else { err = -ENOTCONN; @@ -2340,7 +2340,7 @@ static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg, if (err) return err; - if (sk->sk_state != TCP_ESTABLISHED) + if (READ_ONCE(sk->sk_state) != TCP_ESTABLISHED) return -ENOTCONN; if (msg->msg_namelen) @@ -2354,7 +2354,7 @@ static int unix_seqpacket_recvmsg(struct socket *sock, struct msghdr *msg, { struct sock *sk = sock->sk; - if (sk->sk_state != TCP_ESTABLISHED) + if (READ_ONCE(sk->sk_state) != TCP_ESTABLISHED) return -ENOTCONN; return unix_dgram_recvmsg(sock, msg, size, flags); @@ -2683,7 +2683,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state, size_t size = state->size; unsigned int last_len; - if (unlikely(sk->sk_state != TCP_ESTABLISHED)) { + if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED)) { err = -EINVAL; goto out; } -- cgit From af4c733b6b1aded4dc808fafece7dfe6e9d2ebb3 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:34 -0700 Subject: af_unix: Annotate data-race of sk->sk_state in unix_stream_read_skb(). unix_stream_read_skb() is called from sk->sk_data_ready() context where unix_state_lock() is not held. Let's use READ_ONCE() there. Fixes: 77462de14a43 ("af_unix: Add read_sock for stream socket types") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 4ef9c21783a5..e7b74207aa3b 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2659,7 +2659,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) { - if (unlikely(sk->sk_state != TCP_ESTABLISHED)) + if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED)) return -ENOTCONN; return unix_read_skb(sk, recv_actor); -- cgit From b0632e53e0da8054e36bc973f0eec69d30f1b7c6 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:36 -0700 Subject: af_unix: Annotate data-races around sk->sk_sndbuf. sk_setsockopt() changes sk->sk_sndbuf under lock_sock(), but it's not used in af_unix.c. Let's use READ_ONCE() to read sk->sk_sndbuf in unix_writable(), unix_dgram_sendmsg(), and unix_stream_sendmsg(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index e7b74207aa3b..de2a5e334a88 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -533,7 +533,7 @@ static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other) static int unix_writable(const struct sock *sk, unsigned char state) { return state != TCP_LISTEN && - (refcount_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf; + (refcount_read(&sk->sk_wmem_alloc) << 2) <= READ_ONCE(sk->sk_sndbuf); } static void unix_write_space(struct sock *sk) @@ -1967,7 +1967,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, } err = -EMSGSIZE; - if (len > sk->sk_sndbuf - 32) + if (len > READ_ONCE(sk->sk_sndbuf) - 32) goto out; if (len > SKB_MAX_ALLOC) { @@ -2247,7 +2247,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, &err, 0); } else { /* Keep two messages in the pipe so it schedules better */ - size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64); + size = min_t(int, size, (READ_ONCE(sk->sk_sndbuf) >> 1) - 64); /* allow fallback to order-0 allocations */ size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ); -- cgit From bd9f2d05731f6a112d0c7391a0d537bfc588dbe6 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:37 -0700 Subject: af_unix: Annotate data-race of net->unx.sysctl_max_dgram_qlen. net->unx.sysctl_max_dgram_qlen is exposed as a sysctl knob and can be changed concurrently. Let's use READ_ONCE() in unix_create1(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index de2a5e334a88..623ee39657e2 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -976,7 +976,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, sk->sk_hash = unix_unbound_hash(sk); sk->sk_allocation = GFP_KERNEL_ACCOUNT; sk->sk_write_space = unix_write_space; - sk->sk_max_ack_backlog = net->unx.sysctl_max_dgram_qlen; + sk->sk_max_ack_backlog = READ_ONCE(net->unx.sysctl_max_dgram_qlen); sk->sk_destruct = unix_sock_destructor; u = unix_sk(sk); u->listener = NULL; -- cgit From 45d872f0e65593176d880ec148f41ad7c02e40a7 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:38 -0700 Subject: af_unix: Use unix_recvq_full_lockless() in unix_stream_connect(). Once sk->sk_state is changed to TCP_LISTEN, it never changes. unix_accept() takes advantage of this characteristics; it does not hold the listener's unix_state_lock() and only acquires recvq lock to pop one skb. It means unix_state_lock() does not prevent the queue length from changing in unix_stream_connect(). Thus, we need to use unix_recvq_full_lockless() to avoid data-race. Now we remove unix_recvq_full() as no one uses it. Note that we can remove READ_ONCE() for sk->sk_max_ack_backlog in unix_recvq_full_lockless() because of the following reasons: (1) For SOCK_DGRAM, it is a written-once field in unix_create1() (2) For SOCK_STREAM and SOCK_SEQPACKET, it is changed under the listener's unix_state_lock() in unix_listen(), and we hold the lock in unix_stream_connect() Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 623ee39657e2..eb3ba3448ed3 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -221,15 +221,9 @@ static inline int unix_may_send(struct sock *sk, struct sock *osk) return unix_peer(osk) == NULL || unix_our_peer(sk, osk); } -static inline int unix_recvq_full(const struct sock *sk) -{ - return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; -} - static inline int unix_recvq_full_lockless(const struct sock *sk) { - return skb_queue_len_lockless(&sk->sk_receive_queue) > - READ_ONCE(sk->sk_max_ack_backlog); + return skb_queue_len_lockless(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; } struct sock *unix_peer_get(struct sock *s) @@ -1545,7 +1539,7 @@ restart: if (other->sk_shutdown & RCV_SHUTDOWN) goto out_unlock; - if (unix_recvq_full(other)) { + if (unix_recvq_full_lockless(other)) { err = -EAGAIN; if (!timeo) goto out_unlock; -- cgit From 83690b82d228b3570565ebd0b41873933238b97f Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 4 Jun 2024 09:52:39 -0700 Subject: af_unix: Use skb_queue_empty_lockless() in unix_release_sock(). If the socket type is SOCK_STREAM or SOCK_SEQPACKET, unix_release_sock() checks the length of the peer socket's recvq under unix_state_lock(). However, unix_stream_read_generic() calls skb_unlink() after releasing the lock. Also, for SOCK_SEQPACKET, __skb_try_recv_datagram() unlinks skb without unix_state_lock(). Thues, unix_state_lock() does not protect qlen. Let's use skb_queue_empty_lockless() in unix_release_sock(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/unix/af_unix.c') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index eb3ba3448ed3..80846279de9f 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -631,7 +631,7 @@ static void unix_release_sock(struct sock *sk, int embrion) unix_state_lock(skpair); /* No more writes */ WRITE_ONCE(skpair->sk_shutdown, SHUTDOWN_MASK); - if (!skb_queue_empty(&sk->sk_receive_queue) || embrion) + if (!skb_queue_empty_lockless(&sk->sk_receive_queue) || embrion) WRITE_ONCE(skpair->sk_err, ECONNRESET); unix_state_unlock(skpair); skpair->sk_state_change(skpair); -- cgit