From 41f4689a7c8cd76b77864461b3c58fde8f322b2c Mon Sep 17 00:00:00 2001 From: Eric Leblond Date: Wed, 7 Feb 2007 15:10:09 -0800 Subject: [PATCH] [NETFILTER]: NAT: optional source port randomization support This patch adds support to NAT to randomize source ports. Signed-off-by: Eric Leblond Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- include/linux/netfilter_ipv4/ip_nat.h | 1 + include/net/netfilter/nf_nat.h | 1 + net/ipv4/netfilter/ip_nat_core.c | 12 ++++++++++-- net/ipv4/netfilter/ip_nat_proto_tcp.c | 5 +++++ net/ipv4/netfilter/ip_nat_proto_udp.c | 5 +++++ net/ipv4/netfilter/ip_nat_rule.c | 4 ++++ net/ipv4/netfilter/nf_nat_core.c | 12 ++++++++++-- net/ipv4/netfilter/nf_nat_proto_tcp.c | 4 ++++ net/ipv4/netfilter/nf_nat_proto_udp.c | 4 ++++ net/ipv4/netfilter/nf_nat_rule.c | 4 ++++ 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 #include +#include #include #include #include @@ -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 #include +#include #include #include #include @@ -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 #include +#include #include #include @@ -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 #include +#include #include #include @@ -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; } -- 2.39.5