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-rw-r--r--include/linux/netfilter_ipv4/ip_nat.h1
-rw-r--r--include/net/netfilter/nf_nat.h1
-rw-r--r--net/ipv4/netfilter/ip_nat_core.c12
-rw-r--r--net/ipv4/netfilter/ip_nat_proto_tcp.c5
-rw-r--r--net/ipv4/netfilter/ip_nat_proto_udp.c5
-rw-r--r--net/ipv4/netfilter/ip_nat_rule.c4
-rw-r--r--net/ipv4/netfilter/nf_nat_core.c12
-rw-r--r--net/ipv4/netfilter/nf_nat_proto_tcp.c4
-rw-r--r--net/ipv4/netfilter/nf_nat_proto_udp.c4
-rw-r--r--net/ipv4/netfilter/nf_nat_rule.c4
10 files changed, 48 insertions, 4 deletions
diff --git a/include/linux/netfilter_ipv4/ip_nat.h b/include/linux/netfilter_ipv4/ip_nat.h
index bdf553620ca1..bbca89aab813 100644
--- a/include/linux/netfilter_ipv4/ip_nat.h
+++ b/include/linux/netfilter_ipv4/ip_nat.h
@@ -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 {
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 61c62068ca6b..bc57dd7b9b5c 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -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 {
diff --git a/net/ipv4/netfilter/ip_nat_core.c b/net/ipv4/netfilter/ip_nat_core.c
index 9d1a5175dcd4..5e08c2bf887d 100644
--- a/net/ipv4/netfilter/ip_nat_core.c
+++ b/net/ipv4/netfilter/ip_nat_core.c
@@ -246,8 +246,9 @@ 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 (!ip_nat_used_tuple(tuple, conntrack))
- return;
+ 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))
diff --git a/net/ipv4/netfilter/ip_nat_proto_tcp.c b/net/ipv4/netfilter/ip_nat_proto_tcp.c
index b586d18b3fb3..14ff24f53a7a 100644
--- a/net/ipv4/netfilter/ip_nat_proto_tcp.c
+++ b/net/ipv4/netfilter/ip_nat_proto_tcp.c
@@ -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)) {
diff --git a/net/ipv4/netfilter/ip_nat_proto_udp.c b/net/ipv4/netfilter/ip_nat_proto_udp.c
index 5ced0877b32f..dfd521672891 100644
--- a/net/ipv4/netfilter/ip_nat_proto_udp.c
+++ b/net/ipv4/netfilter/ip_nat_proto_udp.c
@@ -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))
diff --git a/net/ipv4/netfilter/ip_nat_rule.c b/net/ipv4/netfilter/ip_nat_rule.c
index a176aa3031e0..6ebaad36c06d 100644
--- a/net/ipv4/netfilter/ip_nat_rule.c
+++ b/net/ipv4/netfilter/ip_nat_rule.c
@@ -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;
}
diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 86a92272b053..998b2557692c 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -254,8 +254,9 @@ 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 (!nf_nat_used_tuple(tuple, ct))
- return;
+ 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)) &&
diff --git a/net/ipv4/netfilter/nf_nat_proto_tcp.c b/net/ipv4/netfilter/nf_nat_proto_tcp.c
index 7e26a7e9bee1..439164c7a626 100644
--- a/net/ipv4/netfilter/nf_nat_proto_tcp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_tcp.c
@@ -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))
diff --git a/net/ipv4/netfilter/nf_nat_proto_udp.c b/net/ipv4/netfilter/nf_nat_proto_udp.c
index ab0ce4c8699f..8cae6e063bb6 100644
--- a/net/ipv4/netfilter/nf_nat_proto_udp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_udp.c
@@ -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))
diff --git a/net/ipv4/netfilter/nf_nat_rule.c b/net/ipv4/netfilter/nf_nat_rule.c
index b868ee0195d4..3745efe70302 100644
--- a/net/ipv4/netfilter/nf_nat_rule.c
+++ b/net/ipv4/netfilter/nf_nat_rule.c
@@ -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;
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.