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Date: Sun, 22 Dec 2013 04:15:38 +0100
From: Hannes Frederic Sowa <hannes@...essinduktion.org>
To: Pablo Neira Ayuso <pablo@...filter.org>,
Daniel Borkmann <dborkman@...hat.com>,
netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
kaber@...sh.net
Subject: [PATCH iptables] iptables: snat: add randomize-full support
From: Daniel Borkmann <dborkman@...hat.com>
This patch provides the user space part for dnat in order to make
randomize-full support available in {ip,nf}tables. It allows for
enabling full port randomization that was motivated in [1] and
introduced to the kernel in [2].
Joint work between Hannes Frederic Sowa and Daniel Borkmann.
[1] https://sites.google.com/site/hayashulman/files/NIC-derandomisation.pdf
[2] http://patchwork.ozlabs.org/patch/304306/
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
---
extensions/libip6t_SNAT.c | 18 ++++++++++++++----
extensions/libipt_SNAT.c | 18 ++++++++++++++----
extensions/libxt_SNAT.man | 7 ++++++-
include/linux/netfilter/nf_nat.h | 12 ++++++++----
4 files changed, 42 insertions(+), 13 deletions(-)
diff --git a/extensions/libip6t_SNAT.c b/extensions/libip6t_SNAT.c
index 7382ad0..8eb50b8 100644
--- a/extensions/libip6t_SNAT.c
+++ b/extensions/libip6t_SNAT.c
@@ -18,11 +18,13 @@
enum {
O_TO_SRC = 0,
O_RANDOM,
+ O_RANDOM_FULLY,
O_PERSISTENT,
O_X_TO_SRC,
- F_TO_SRC = 1 << O_TO_SRC,
- F_RANDOM = 1 << O_RANDOM,
- F_X_TO_SRC = 1 << O_X_TO_SRC,
+ F_TO_SRC = 1 << O_TO_SRC,
+ F_RANDOM = 1 << O_RANDOM,
+ F_RANDOM_FULLY = 1 << O_RANDOM_FULLY,
+ F_X_TO_SRC = 1 << O_X_TO_SRC,
};
static void SNAT_help(void)
@@ -31,13 +33,14 @@ static void SNAT_help(void)
"SNAT target options:\n"
" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
" Address to map source to.\n"
-"[--random] [--persistent]\n");
+"[--random] [--random-fully] [--persistent]\n");
}
static const struct xt_option_entry SNAT_opts[] = {
{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
.flags = XTOPT_MAND | XTOPT_MULTI},
{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
+ {.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE},
{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
@@ -180,10 +183,13 @@ static void SNAT_parse(struct xt_option_call *cb)
static void SNAT_fcheck(struct xt_fcheck_call *cb)
{
static const unsigned int f = F_TO_SRC | F_RANDOM;
+ static const unsigned int r = F_TO_SRC | F_RANDOM_FULLY;
struct nf_nat_range *range = cb->data;
if ((cb->xflags & f) == f)
range->flags |= NF_NAT_RANGE_PROTO_RANDOM;
+ if ((cb->xflags & r) == r)
+ range->flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;
}
static void print_range(const struct nf_nat_range *range)
@@ -215,6 +221,8 @@ static void SNAT_print(const void *ip, const struct xt_entry_target *target,
print_range(range);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" random");
+ if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
+ printf(" random-fully");
if (range->flags & NF_NAT_RANGE_PERSISTENT)
printf(" persistent");
}
@@ -227,6 +235,8 @@ static void SNAT_save(const void *ip, const struct xt_entry_target *target)
print_range(range);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" --random");
+ if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
+ printf(" --random-fully");
if (range->flags & NF_NAT_RANGE_PERSISTENT)
printf(" --persistent");
}
diff --git a/extensions/libipt_SNAT.c b/extensions/libipt_SNAT.c
index 1a24f3d..78d2c2b 100644
--- a/extensions/libipt_SNAT.c
+++ b/extensions/libipt_SNAT.c
@@ -11,11 +11,13 @@
enum {
O_TO_SRC = 0,
O_RANDOM,
+ O_RANDOM_FULLY,
O_PERSISTENT,
O_X_TO_SRC,
- F_TO_SRC = 1 << O_TO_SRC,
- F_RANDOM = 1 << O_RANDOM,
- F_X_TO_SRC = 1 << O_X_TO_SRC,
+ F_TO_SRC = 1 << O_TO_SRC,
+ F_RANDOM = 1 << O_RANDOM,
+ F_RANDOM_FULLY = 1 << O_RANDOM_FULLY,
+ F_X_TO_SRC = 1 << O_X_TO_SRC,
};
/* Source NAT data consists of a multi-range, indicating where to map
@@ -32,13 +34,14 @@ static void SNAT_help(void)
"SNAT target options:\n"
" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
" Address to map source to.\n"
-"[--random] [--persistent]\n");
+"[--random] [--random-fully] [--persistent]\n");
}
static const struct xt_option_entry SNAT_opts[] = {
{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
.flags = XTOPT_MAND | XTOPT_MULTI},
{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
+ {.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE},
{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
@@ -185,10 +188,13 @@ static void SNAT_parse(struct xt_option_call *cb)
static void SNAT_fcheck(struct xt_fcheck_call *cb)
{
static const unsigned int f = F_TO_SRC | F_RANDOM;
+ static const unsigned int r = F_TO_SRC | F_RANDOM_FULLY;
struct nf_nat_ipv4_multi_range_compat *mr = cb->data;
if ((cb->xflags & f) == f)
mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM;
+ if ((cb->xflags & r) == r)
+ mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;
}
static void print_range(const struct nf_nat_ipv4_range *r)
@@ -222,6 +228,8 @@ static void SNAT_print(const void *ip, const struct xt_entry_target *target,
print_range(&info->mr.range[i]);
if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" random");
+ if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
+ printf(" random-fully");
if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT)
printf(" persistent");
}
@@ -237,6 +245,8 @@ static void SNAT_save(const void *ip, const struct xt_entry_target *target)
print_range(&info->mr.range[i]);
if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" --random");
+ if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
+ printf(" --random-fully");
if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT)
printf(" --persistent");
}
diff --git a/extensions/libxt_SNAT.man b/extensions/libxt_SNAT.man
index f0620a2..8cd0b80 100644
--- a/extensions/libxt_SNAT.man
+++ b/extensions/libxt_SNAT.man
@@ -29,7 +29,12 @@ anymore.
\fB\-\-random\fP
If option
\fB\-\-random\fP
-is used then port mapping will be randomized (kernel >= 2.6.21).
+is used then port mapping will be randomized through a hash-based algorithm (kernel >= 2.6.21).
+.TP
+\fB\-\-random-fully\fP
+If option
+\fB\-\-random-fully\fP
+is used then port mapping will be fully randomized through a PRNG (kernel >= 3.14).
.TP
\fB\-\-persistent\fP
Gives a client the same source-/destination-address for each connection.
diff --git a/include/linux/netfilter/nf_nat.h b/include/linux/netfilter/nf_nat.h
index bf0cc37..1ad3659 100644
--- a/include/linux/netfilter/nf_nat.h
+++ b/include/linux/netfilter/nf_nat.h
@@ -4,10 +4,14 @@
#include <linux/netfilter.h>
#include <linux/netfilter/nf_conntrack_tuple_common.h>
-#define NF_NAT_RANGE_MAP_IPS 1
-#define NF_NAT_RANGE_PROTO_SPECIFIED 2
-#define NF_NAT_RANGE_PROTO_RANDOM 4
-#define NF_NAT_RANGE_PERSISTENT 8
+#define NF_NAT_RANGE_MAP_IPS (1 << 0)
+#define NF_NAT_RANGE_PROTO_SPECIFIED (1 << 1)
+#define NF_NAT_RANGE_PROTO_RANDOM (1 << 2)
+#define NF_NAT_RANGE_PERSISTENT (1 << 3)
+#define NF_NAT_RANGE_PROTO_RANDOM_FULLY (1 << 4)
+
+#define NF_NAT_RANGE_PROTO_RANDOM_ALL \
+ (NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PROTO_RANDOM_FULLY)
struct nf_nat_ipv4_range {
unsigned int flags;
--
1.8.3.1
--
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