From 415e3d3e90ce9e18727e8843ae343eda5a58fad6 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Wed, 3 Feb 2016 02:11:03 +0100 Subject: unix: correctly track in-flight fds in sending process user_struct 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 --- net/unix/af_unix.c | 4 ++-- net/unix/garbage.c | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-) (limited to 'net/unix') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 49d5093eb055..29be035f9c65 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1496,7 +1496,7 @@ static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb) UNIXCB(skb).fp = NULL; for (i = scm->fp->count-1; i >= 0; i--) - unix_notinflight(scm->fp->fp[i]); + unix_notinflight(scm->fp->user, scm->fp->fp[i]); } static void unix_destruct_scm(struct sk_buff *skb) @@ -1561,7 +1561,7 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb) return -ENOMEM; for (i = scm->fp->count - 1; i >= 0; i--) - unix_inflight(scm->fp->fp[i]); + unix_inflight(scm->fp->user, scm->fp->fp[i]); return max_level; } diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 8fcdc2283af5..6a0d48525fcf 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -116,7 +116,7 @@ struct sock *unix_get_socket(struct file *filp) * descriptor if it is for an AF_UNIX socket. */ -void unix_inflight(struct file *fp) +void unix_inflight(struct user_struct *user, struct file *fp) { struct sock *s = unix_get_socket(fp); @@ -133,11 +133,11 @@ void unix_inflight(struct file *fp) } unix_tot_inflight++; } - fp->f_cred->user->unix_inflight++; + user->unix_inflight++; spin_unlock(&unix_gc_lock); } -void unix_notinflight(struct file *fp) +void unix_notinflight(struct user_struct *user, struct file *fp) { struct sock *s = unix_get_socket(fp); @@ -152,7 +152,7 @@ void unix_notinflight(struct file *fp) list_del_init(&u->link); unix_tot_inflight--; } - fp->f_cred->user->unix_inflight--; + user->unix_inflight--; spin_unlock(&unix_gc_lock); } -- cgit v1.2.3 From 1b92ee3d03af6643df395300ba7748f19ecdb0c5 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Mon, 8 Feb 2016 18:47:19 +0000 Subject: af_unix: Don't set err in unix_stream_read_generic unless there was an error The present unix_stream_read_generic contains various code sequences of the form err = -EDISASTER; if () 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 http://pad.lv/1540731 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 --- net/unix/af_unix.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'net/unix') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 29be035f9c65..df923caa8389 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2277,13 +2277,15 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state) size_t size = state->size; unsigned int last_len; - err = -EINVAL; - if (sk->sk_state != TCP_ESTABLISHED) + if (unlikely(sk->sk_state != TCP_ESTABLISHED)) { + err = -EINVAL; goto out; + } - err = -EOPNOTSUPP; - if (flags & MSG_OOB) + if (unlikely(flags & MSG_OOB)) { + err = -EOPNOTSUPP; goto out; + } target = sock_rcvlowat(sk, flags & MSG_WAITALL, size); timeo = sock_rcvtimeo(sk, noblock); @@ -2329,9 +2331,11 @@ again: goto unlock; unix_state_unlock(sk); - err = -EAGAIN; - if (!timeo) + if (!timeo) { + err = -EAGAIN; break; + } + mutex_unlock(&u->readlock); timeo = unix_stream_data_wait(sk, timeo, last, -- cgit v1.2.3 From a5527dda344fff0514b7989ef7a755729769daa1 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Thu, 11 Feb 2016 19:37:27 +0000 Subject: af_unix: Guard against other == sk in unix_dgram_sendmsg 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 --- net/unix/af_unix.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'net/unix') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index df923caa8389..c51e2831f498 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1781,7 +1781,12 @@ restart_locked: goto out_unlock; } - if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { + /* other == sk && unix_peer(other) != sk if + * - unix_peer(sk) == NULL, destination address bound to sk + * - unix_peer(sk) == sk by time of get but disconnected before lock + */ + if (other != sk && + unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { if (timeo) { timeo = unix_wait_for_peer(other, timeo); -- cgit v1.2.3 From b5f0549231ffb025337be5a625b0ff9f52b016f0 Mon Sep 17 00:00:00 2001 From: "Dmitry V. Levin" Date: Fri, 19 Feb 2016 04:27:48 +0300 Subject: unix_diag: fix incorrect sign extension in unix_lookup_by_ino 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 --- net/unix/diag.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/unix') diff --git a/net/unix/diag.c b/net/unix/diag.c index c512f64d5287..4d9679701a6d 100644 --- a/net/unix/diag.c +++ b/net/unix/diag.c @@ -220,7 +220,7 @@ done: return skb->len; } -static struct sock *unix_lookup_by_ino(int ino) +static struct sock *unix_lookup_by_ino(unsigned int ino) { int i; struct sock *sk; -- cgit v1.2.3 From 18eceb818dc37bbc783ec7ef7703f270cc6cd281 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Thu, 18 Feb 2016 12:39:46 +0000 Subject: af_unix: Don't use continue to re-execute unix_stream_read_generic loop 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 --- net/unix/af_unix.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/unix') diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index c51e2831f498..f75f847e688d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2312,6 +2312,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state) bool drop_skb; struct sk_buff *skb, *last; +redo: unix_state_lock(sk); if (sock_flag(sk, SOCK_DEAD)) { err = -ECONNRESET; @@ -2353,7 +2354,7 @@ again: } mutex_lock(&u->readlock); - continue; + goto redo; unlock: unix_state_unlock(sk); break; -- cgit v1.2.3