[NETFILTER]: nf_nat: add helpers for common NAT protocol operations

Add generic ->in_range and ->unique_tuple ops to avoid duplicating them
again and again for future NAT modules and save a few bytes of text:

net/ipv4/netfilter/nf_nat_proto_tcp.c:
  tcp_in_range     |  -62 (removed)
  tcp_unique_tuple | -259 # 271 -> 12, # inlines: 1 -> 0, size inlines: 7 -> 0
 2 functions changed, 321 bytes removed

net/ipv4/netfilter/nf_nat_proto_udp.c:
  udp_in_range     |  -62 (removed)
  udp_unique_tuple | -259 # 271 -> 12, # inlines: 1 -> 0, size inlines: 7 -> 0
 2 functions changed, 321 bytes removed

net/ipv4/netfilter/nf_nat_proto_gre.c:
  gre_in_range |  -62 (removed)
 1 function changed, 62 bytes removed

vmlinux:
 5 functions changed, 704 bytes removed

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 4 insertions, 61 deletions

diff --git a/net/ipv4/netfilter/nf_nat_proto_tcp.c b/net/ipv4/netfilter/nf_nat_proto_tcp.c
index ffd5d1589ec..f8c498fc24f 100644
--- a/net/ipv4/netfilter/nf_nat_proto_tcp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_tcp.c
@@ -8,7 +8,6 @@
 
 #include <linux/types.h>
 #include <linux/init.h>
-#include <linux/random.h>
 #include <linux/ip.h>
 #include <linux/tcp.h>
 
@@ -19,22 +18,7 @@
 #include <net/netfilter/nf_nat_protocol.h>
 #include <net/netfilter/nf_nat_core.h>
 
-static int
-tcp_in_range(const struct nf_conntrack_tuple *tuple,
-             enum nf_nat_manip_type maniptype,
-             const union nf_conntrack_man_proto *min,
-             const union nf_conntrack_man_proto *max)
-{
-        __be16 port;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                port = tuple->src.u.tcp.port;
-        else
-                port = tuple->dst.u.tcp.port;
-
-        return ntohs(port) >= ntohs(min->tcp.port) &&
-               ntohs(port) <= ntohs(max->tcp.port);
-}
+static u_int16_t tcp_port_rover;
 
 static int
 tcp_unique_tuple(struct nf_conntrack_tuple *tuple,
@@ -42,49 +26,8 @@ tcp_unique_tuple(struct nf_conntrack_tuple *tuple,
                  enum nf_nat_manip_type maniptype,
                  const struct nf_conn *ct)
 {
-        static u_int16_t port;
-        __be16 *portptr;
-        unsigned int range_size, min, i;
-
-        if (maniptype == IP_NAT_MANIP_SRC)
-                portptr = &tuple->src.u.tcp.port;
-        else
-                portptr = &tuple->dst.u.tcp.port;
-
-        /* If no range specified... */
-        if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
-                /* If it's dst rewrite, can't change port */
-                if (maniptype == IP_NAT_MANIP_DST)
-                        return 0;
-
-                /* Map privileged onto privileged. */
-                if (ntohs(*portptr) < 1024) {
-                        /* Loose convention: >> 512 is credential passing */
-                        if (ntohs(*portptr)<512) {
-                                min = 1;
-                                range_size = 511 - min + 1;
-                        } else {
-                                min = 600;
-                                range_size = 1023 - min + 1;
-                        }
-                } else {
-                        min = 1024;
-                        range_size = 65535 - 1024 + 1;
-                }
-        } else {
-                min = ntohs(range->min.tcp.port);
-                range_size = ntohs(range->max.tcp.port) - min + 1;
-        }
-
-        if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
-                port =  net_random();
-
-        for (i = 0; i < range_size; i++, port++) {
-                *portptr = htons(min + port % range_size);
-                if (!nf_nat_used_tuple(tuple, ct))
-                        return 1;
-        }
-        return 0;
+        return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
+                                         &tcp_port_rover);
 }
 
 static int
@@ -142,7 +85,7 @@ const struct nf_nat_protocol nf_nat_protocol_tcp = {
         .protonum               = IPPROTO_TCP,
         .me                     = THIS_MODULE,
         .manip_pkt              = tcp_manip_pkt,
-        .in_range               = tcp_in_range,
+        .in_range               = nf_nat_proto_in_range,
         .unique_tuple           = tcp_unique_tuple,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
         .range_to_nlattr        = nf_nat_port_range_to_nlattr,