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, 17 insertions, 0 deletions

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1cd5c15174b8..d96c1da4b17c 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -299,6 +299,13 @@ static struct ctl_table ipv4_table[] = {
                 .mode           = 0644,
                 .proc_handler   = ipv4_local_port_range,
         },
+        {
+                .procname       = "ip_local_reserved_ports",
+                .data           = NULL, /* initialized in sysctl_ipv4_init */
+                .maxlen         = 65536,
+                .mode           = 0644,
+                .proc_handler   = proc_do_large_bitmap,
+        },
 #ifdef CONFIG_IP_MULTICAST
         {
                 .procname       = "igmp_max_memberships",
@@ -736,6 +743,16 @@ static __net_initdata struct pernet_operations ipv4_sysctl_ops = {
 static __init int sysctl_ipv4_init(void)
 {
         struct ctl_table_header *hdr;
+        struct ctl_table *i;
+
+        for (i = ipv4_table; i->procname; i++) {
+                if (strcmp(i->procname, "ip_local_reserved_ports") == 0) {
+                        i->data = sysctl_local_reserved_ports;
+                        break;
+                }
+        }
+        if (!i->procname)
+                return -EINVAL;
 
         hdr = register_sysctl_paths(net_ipv4_ctl_path, ipv4_table);
         if (hdr == NULL)