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[NETFILTER]: NAT: optional source port randomization support

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This patch adds support to NAT to randomize source ports.

Signed-off-by: Eric Leblond <eric@inl.fr>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Leblond 2007-02-07 15:10:09 -08:00 committed by David S. Miller
parent cdd289a2f8
commit 41f4689a7c
10 changed files with 48 additions and 4 deletions
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1
include/linux/netfilter_ipv4/ip_nat.h
View File

@ -16,6 +16,7 @@ enum ip_nat_manip_type
#define IP_NAT_RANGE_MAP_IPS 1
#define IP_NAT_RANGE_PROTO_SPECIFIED 2
#define IP_NAT_RANGE_PROTO_RANDOM 4 /* add randomness to "port" selection */
/* NAT sequence number modifications */
struct ip_nat_seq {

1
include/net/netfilter/nf_nat.h
View File

@ -16,6 +16,7 @@ enum nf_nat_manip_type
#define IP_NAT_RANGE_MAP_IPS 1
#define IP_NAT_RANGE_PROTO_SPECIFIED 2
#define IP_NAT_RANGE_PROTO_RANDOM 4
/* NAT sequence number modifications */
struct nf_nat_seq {

8
net/ipv4/netfilter/ip_nat_core.c
View File

@ -246,6 +246,7 @@ get_unique_tuple(struct ip_conntrack_tuple *tuple,
if (maniptype == IP_NAT_MANIP_SRC) {
if (find_appropriate_src(orig_tuple, tuple, range)) {
DEBUGP("get_unique_tuple: Found current src map\n");
if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
if (!ip_nat_used_tuple(tuple, conntrack))
return;
}
@ -261,6 +262,13 @@ get_unique_tuple(struct ip_conntrack_tuple *tuple,
proto = ip_nat_proto_find_get(orig_tuple->dst.protonum);
/* Change protocol info to have some randomization */
if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
proto->unique_tuple(tuple, range, maniptype, conntrack);
ip_nat_proto_put(proto);
return;
}
/* Only bother mapping if it's not already in range and unique */
if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)
|| proto->in_range(tuple, maniptype, &range->min, &range->max))

5
net/ipv4/netfilter/ip_nat_proto_tcp.c
View File

@ -8,6 +8,7 @@
#include <linux/types.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/netfilter.h>
#include <linux/ip.h>
#include <linux/tcp.h>
@ -75,6 +76,10 @@ tcp_unique_tuple(struct ip_conntrack_tuple *tuple,
range_size = ntohs(range->max.tcp.port) - min + 1;
}
/* Start from random port to avoid prediction */
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 (!ip_nat_used_tuple(tuple, conntrack)) {

5
net/ipv4/netfilter/ip_nat_proto_udp.c
View File

@ -8,6 +8,7 @@
#include <linux/types.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/netfilter.h>
#include <linux/ip.h>
#include <linux/udp.h>
@ -74,6 +75,10 @@ udp_unique_tuple(struct ip_conntrack_tuple *tuple,
range_size = ntohs(range->max.udp.port) - min + 1;
}
/* Start from random port to avoid prediction */
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 (!ip_nat_used_tuple(tuple, conntrack))

4
net/ipv4/netfilter/ip_nat_rule.c
View File

@ -193,6 +193,10 @@ static int ipt_dnat_checkentry(const char *tablename,
printk("DNAT: multiple ranges no longer supported\n");
return 0;
}
if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM) {
printk("DNAT: port randomization not supported\n");
return 0;
}
return 1;
}

8
net/ipv4/netfilter/nf_nat_core.c
View File

@ -254,6 +254,7 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
if (maniptype == IP_NAT_MANIP_SRC) {
if (find_appropriate_src(orig_tuple, tuple, range)) {
DEBUGP("get_unique_tuple: Found current src map\n");
if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
if (!nf_nat_used_tuple(tuple, ct))
return;
}
@ -269,6 +270,13 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
proto = nf_nat_proto_find_get(orig_tuple->dst.protonum);
/* Change protocol info to have some randomization */
if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
proto->unique_tuple(tuple, range, maniptype, ct);
nf_nat_proto_put(proto);
return;
}
/* Only bother mapping if it's not already in range and unique */
if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
proto->in_range(tuple, maniptype, &range->min, &range->max)) &&

4
net/ipv4/netfilter/nf_nat_proto_tcp.c
View File

@ -8,6 +8,7 @@
#include <linux/types.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/ip.h>
#include <linux/tcp.h>
@ -75,6 +76,9 @@ tcp_unique_tuple(struct nf_conntrack_tuple *tuple,
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))

4
net/ipv4/netfilter/nf_nat_proto_udp.c
View File

@ -8,6 +8,7 @@
#include <linux/types.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/ip.h>
#include <linux/udp.h>
@ -73,6 +74,9 @@ udp_unique_tuple(struct nf_conntrack_tuple *tuple,
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))

4
net/ipv4/netfilter/nf_nat_rule.c
View File

@ -226,6 +226,10 @@ static int ipt_dnat_checkentry(const char *tablename,
printk("DNAT: multiple ranges no longer supported\n");
return 0;
}
if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM) {
printk("DNAT: port randomization not supported\n");
return 0;
}
return 1;
}