net: reserve ports for applications using fixed port numbers

(Dropped the infiniband part, because Tetsuo modified the related code,
I will send a separate patch for it once this is accepted.)

This patch introduces /proc/sys/net/ipv4/ip_local_reserved_ports which
allows users to reserve ports for third-party applications.

The reserved ports will not be used by automatic port assignments
(e.g. when calling connect() or bind() with port number 0). Explicit
port allocation behavior is unchanged.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index ba1add0b13c3..ca44917872d2 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5433,6 +5433,8 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
                         rover++;
                         if ((rover < low) || (rover > high))
                                 rover = low;
+                        if (inet_is_reserved_local_port(rover))
+                                continue;
                         index = sctp_phashfn(rover);
                         head = &sctp_port_hashtable[index];
                         sctp_spin_lock(&head->lock);