[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, 60 deletions

diff --git a/net/ipv4/netfilter/nf_nat_proto_udp.c b/net/ipv4/netfilter/nf_nat_proto_udp.c
index 4b8f49910ff..a182f5ac317 100644
--- a/net/ipv4/netfilter/nf_nat_proto_udp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_udp.c
@@ -8,7 +8,6 @@
 
 #include <linux/types.h>
 #include <linux/init.h>
-#include <linux/random.h>
 #include <linux/ip.h>
 #include <linux/udp.h>
 
@@ -18,22 +17,7 @@
 #include <net/netfilter/nf_nat_rule.h>
 #include <net/netfilter/nf_nat_protocol.h>
 
-static int
-udp_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.udp.port;
-	else
-		port = tuple->dst.u.udp.port;
-
-	return ntohs(port) >= ntohs(min->udp.port) &&
-	       ntohs(port) <= ntohs(max->udp.port);
-}
+static u_int16_t udp_port_rover;
 
 static int
 udp_unique_tuple(struct nf_conntrack_tuple *tuple,
@@ -41,48 +25,8 @@ udp_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.udp.port;
-	else
-		portptr = &tuple->dst.u.udp.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;
-
-		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.udp.port);
-		range_size = ntohs(range->max.udp.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,
+					 &udp_port_rover);
 }
 
 static int
@@ -132,7 +76,7 @@ const struct nf_nat_protocol nf_nat_protocol_udp = {
 	.protonum		= IPPROTO_UDP,
 	.me			= THIS_MODULE,
 	.manip_pkt		= udp_manip_pkt,
-	.in_range		= udp_in_range,
+	.in_range		= nf_nat_proto_in_range,
 	.unique_tuple		= udp_unique_tuple,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 	.range_to_nlattr	= nf_nat_port_range_to_nlattr,