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, 6 insertions, 0 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index e0a3e3537b14..70eb3507c406 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -37,6 +37,9 @@ struct local_ports sysctl_local_ports __read_mostly = {
         .range = { 32768, 61000 },
 };
 
+unsigned long *sysctl_local_reserved_ports;
+EXPORT_SYMBOL(sysctl_local_reserved_ports);
+
 void inet_get_local_port_range(int *low, int *high)
 {
         unsigned seq;
@@ -108,6 +111,8 @@ again:
 
                 smallest_size = -1;
                 do {
+                        if (inet_is_reserved_local_port(rover))
+                                goto next_nolock;
                         head = &hashinfo->bhash[inet_bhashfn(net, rover,
                                         hashinfo->bhash_size)];
                         spin_lock(&head->lock);
@@ -130,6 +135,7 @@ again:
                         break;
                 next:
                         spin_unlock(&head->lock);
+                next_nolock:
                         if (++rover > high)
                                 rover = low;
                 } while (--remaining > 0);