1 files changed, 50 insertions, 23 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 3c95304a0817..dd419d286204 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -316,7 +316,8 @@ static void unix_write_space(struct sock *sk)
         if (unix_writable(sk)) {
                 wq = rcu_dereference(sk->sk_wq);
                 if (wq_has_sleeper(wq))
-                        wake_up_interruptible_sync(&wq->wait);
+                        wake_up_interruptible_sync_poll(&wq->wait,
+                                POLLOUT | POLLWRNORM | POLLWRBAND);
                 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
         }
         rcu_read_unlock();
@@ -1156,7 +1157,7 @@ restart:
                 goto restart;
         }
 
-        err = security_unix_stream_connect(sock, other->sk_socket, newsk);
+        err = security_unix_stream_connect(sk, other, newsk);
         if (err) {
                 unix_state_unlock(sk);
                 goto out_unlock;
@@ -1343,9 +1344,25 @@ static void unix_destruct_scm(struct sk_buff *skb)
         sock_wfree(skb);
 }
 
+#define MAX_RECURSION_LEVEL 4
+
 static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 {
         int i;
+        unsigned char max_level = 0;
+        int unix_sock_count = 0;
+
+        for (i = scm->fp->count - 1; i >= 0; i--) {
+                struct sock *sk = unix_get_socket(scm->fp->fp[i]);
+
+                if (sk) {
+                        unix_sock_count++;
+                        max_level = max(max_level,
+                                        unix_sk(sk)->recursion_level);
+                }
+        }
+        if (unlikely(max_level > MAX_RECURSION_LEVEL))
+                return -ETOOMANYREFS;
 
         /*
          * Need to duplicate file references for the sake of garbage
@@ -1356,9 +1373,11 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
         if (!UNIXCB(skb).fp)
                 return -ENOMEM;
 
-        for (i = scm->fp->count-1; i >= 0; i--)
-                unix_inflight(scm->fp->fp[i]);
-        return 0;
+        if (unix_sock_count) {
+                for (i = scm->fp->count - 1; i >= 0; i--)
+                        unix_inflight(scm->fp->fp[i]);
+        }
+        return max_level;
 }
 
 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
@@ -1393,6 +1412,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
         struct sk_buff *skb;
         long timeo;
         struct scm_cookie tmp_scm;
+        int max_level;
 
         if (NULL == siocb->scm)
                 siocb->scm = &tmp_scm;
@@ -1431,8 +1451,9 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
                 goto out;
 
         err = unix_scm_to_skb(siocb->scm, skb, true);
-        if (err)
+        if (err < 0)
                 goto out_free;
+        max_level = err + 1;
         unix_get_secdata(siocb->scm, skb);
 
         skb_reset_transport_header(skb);
@@ -1514,6 +1535,8 @@ restart:
         if (sock_flag(other, SOCK_RCVTSTAMP))
                 __net_timestamp(skb);
         skb_queue_tail(&other->sk_receive_queue, skb);
+        if (max_level > unix_sk(other)->recursion_level)
+                unix_sk(other)->recursion_level = max_level;
         unix_state_unlock(other);
         other->sk_data_ready(other, len);
         sock_put(other);
@@ -1544,6 +1567,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
         int sent = 0;
         struct scm_cookie tmp_scm;
         bool fds_sent = false;
+        int max_level;
 
         if (NULL == siocb->scm)
                 siocb->scm = &tmp_scm;
@@ -1607,10 +1631,11 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
 
                 /* Only send the fds in the first buffer */
                 err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
-                if (err) {
+                if (err < 0) {
                         kfree_skb(skb);
                         goto out_err;
                 }
+                max_level = err + 1;
                 fds_sent = true;
 
                 err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
@@ -1626,6 +1651,8 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                         goto pipe_err_free;
 
                 skb_queue_tail(&other->sk_receive_queue, skb);
+                if (max_level > unix_sk(other)->recursion_level)
+                        unix_sk(other)->recursion_level = max_level;
                 unix_state_unlock(other);
                 other->sk_data_ready(other, size);
                 sent += size;
@@ -1710,7 +1737,8 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
                 goto out_unlock;
         }
 
-        wake_up_interruptible_sync(&u->peer_wait);
+        wake_up_interruptible_sync_poll(&u->peer_wait,
+                                        POLLOUT | POLLWRNORM | POLLWRBAND);
 
         if (msg->msg_name)
                 unix_copy_addr(msg, skb->sk);
@@ -1845,6 +1873,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
                 unix_state_lock(sk);
                 skb = skb_dequeue(&sk->sk_receive_queue);
                 if (skb == NULL) {
+                        unix_sk(sk)->recursion_level = 0;
                         if (copied >= target)
                                 goto unlock;
 
@@ -2072,13 +2101,12 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
                 mask |= POLLERR;
         if (sk->sk_shutdown & RCV_SHUTDOWN)
-                mask |= POLLRDHUP;
+                mask |= POLLRDHUP | POLLIN | POLLRDNORM;
         if (sk->sk_shutdown == SHUTDOWN_MASK)
                 mask |= POLLHUP;
 
         /* readable? */
-        if (!skb_queue_empty(&sk->sk_receive_queue) ||
-            (sk->sk_shutdown & RCV_SHUTDOWN))
+        if (!skb_queue_empty(&sk->sk_receive_queue))
                 mask |= POLLIN | POLLRDNORM;
 
         /* Connection-based need to check for termination and startup */
@@ -2090,20 +2118,19 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
                         return mask;
         }
 
-        /* writable? */
-        writable = unix_writable(sk);
-        if (writable) {
-                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;
-                        }
+        /* No write status requested, avoid expensive OUT tests. */
+        if (wait && !(wait->key & (POLLWRBAND | POLLWRNORM | POLLOUT)))
+                return mask;
 
-                        sock_put(other);
+        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)