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, 1 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index f3e00c5cd1ed..9de6a698f91d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -233,7 +233,8 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
                          */
                         do {
                                 if (low <= snum && snum <= high &&
-                                    !test_bit(snum >> udptable->log, bitmap))
+                                    !test_bit(snum >> udptable->log, bitmap) &&
+                                    !inet_is_reserved_local_port(snum))
                                         goto found;
                                 snum += rand;
                         } while (snum != first);