sctp: Allow only 1 listening socket with SO_REUSEADDR

When multiple socket bind to the same port with SO_REUSEADDR,
only 1 can be listining.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 9 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fd7ed9d46a48..79bece16aede 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -377,18 +377,19 @@ SCTP_STATIC int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
         if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
                 return -EACCES;
 
+        /* See if the address matches any of the addresses we may have
+         * already bound before checking against other endpoints.
+         */
+        if (sctp_bind_addr_match(bp, addr, sp))
+                return -EINVAL;
+
         /* Make sure we are allowed to bind here.
          * The function sctp_get_port_local() does duplicate address
          * detection.
          */
         addr->v4.sin_port = htons(snum);
         if ((ret = sctp_get_port_local(sk, addr))) {
-                if (ret == (long) sk) {
-                        /* This endpoint has a conflicting address. */
-                        return -EINVAL;
-                } else {
-                        return -EADDRINUSE;
-                }
+                return -EADDRINUSE;
         }
 
         /* Refresh ephemeral port.  */
@@ -5584,8 +5585,9 @@ pp_found:
                         struct sctp_endpoint *ep2;
                         ep2 = sctp_sk(sk2)->ep;
 
-                        if (reuse && sk2->sk_reuse &&
-                            sk2->sk_state != SCTP_SS_LISTENING)
+                        if (sk == sk2 ||
+                            (reuse && sk2->sk_reuse &&
+                             sk2->sk_state != SCTP_SS_LISTENING))
                                 continue;
 
                         if (sctp_bind_addr_conflict(&ep2->base.bind_addr, addr,
@@ -5702,8 +5704,13 @@ SCTP_STATIC int sctp_seqpacket_listen(struct sock *sk, int backlog)
         if (!ep->base.bind_addr.port) {
                 if (sctp_autobind(sk))
                         return -EAGAIN;
-        } else
+        } else {
+                if (sctp_get_port(sk, inet_sk(sk)->num)) {
+                        sk->sk_state = SCTP_SS_CLOSED;
+                        return -EADDRINUSE;
+                }
                 sctp_sk(sk)->bind_hash->fastreuse = 0;
+        }
 
         sctp_hash_endpoint(ep);
         return 0;