src: add nat persistent and random options

This patch adds more configuration options to the nat expression.

The syntax is as follow:
 % nft add rule nat postrouting <snat|dnat> <nat_arguments> [flags]

Flags are: random, persistent, random-fully.
Example:

 % nft add rule nat postrouting dnat 1.1.1.1 random,persistent

A requirement is to cache some [recent] copies of kernel headers.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 73 insertions, 2 deletions

diff --git a/include/linux/netfilter/nf_conntrack_tuple_common.h b/include/linux/netfilter/nf_conntrack_tuple_common.h
index 8e145f0d..8ab31184 100644
--- a/include/linux/netfilter/nf_conntrack_tuple_common.h
+++ b/include/linux/netfilter/nf_conntrack_tuple_common.h
@@ -1,13 +1,41 @@
 #ifndef _NF_CONNTRACK_TUPLE_COMMON_H
 #define _NF_CONNTRACK_TUPLE_COMMON_H
 
-enum ip_conntrack_dir
-{
+#include <linux/types.h>
+
+enum ip_conntrack_dir {
 	IP_CT_DIR_ORIGINAL,
 	IP_CT_DIR_REPLY,
 	IP_CT_DIR_MAX
 };
 
+/* The protocol-specific manipulable parts of the tuple: always in
+ * network order
+ */
+union nf_conntrack_man_proto {
+	/* Add other protocols here. */
+	__be16 all;
+
+	struct {
+		__be16 port;
+	} tcp;
+	struct {
+		__be16 port;
+	} udp;
+	struct {
+		__be16 id;
+	} icmp;
+	struct {
+		__be16 port;
+	} dccp;
+	struct {
+		__be16 port;
+	} sctp;
+	struct {
+		__be16 key;	/* GRE key is 32bit, PPtP only uses 16bit */
+	} gre;
+};
+
 #define CTINFO2DIR(ctinfo) ((ctinfo) >= IP_CT_IS_REPLY ? IP_CT_DIR_REPLY : IP_CT_DIR_ORIGINAL)
 
 #endif /* _NF_CONNTRACK_TUPLE_COMMON_H */
diff --git a/include/linux/netfilter/nf_nat.h b/include/linux/netfilter/nf_nat.h
new file mode 100644
index 00000000..0880781a
--- /dev/null
+++ b/include/linux/netfilter/nf_nat.h
@@ -0,0 +1,42 @@
+#ifndef _NETFILTER_NF_NAT_H
+#define _NETFILTER_NF_NAT_H
+
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_conntrack_tuple_common.h>
+
+#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)
+
+#define NF_NAT_RANGE_MASK					\
+	(NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED |	\
+	 NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PERSISTENT |	\
+	 NF_NAT_RANGE_PROTO_RANDOM_FULLY)
+
+struct nf_nat_ipv4_range {
+	unsigned int			flags;
+	__be32				min_ip;
+	__be32				max_ip;
+	union nf_conntrack_man_proto	min;
+	union nf_conntrack_man_proto	max;
+};
+
+struct nf_nat_ipv4_multi_range_compat {
+	unsigned int			rangesize;
+	struct nf_nat_ipv4_range	range[1];
+};
+
+struct nf_nat_range {
+	unsigned int			flags;
+	union nf_inet_addr		min_addr;
+	union nf_inet_addr		max_addr;
+	union nf_conntrack_man_proto	min_proto;
+	union nf_conntrack_man_proto	max_proto;
+};
+
+#endif /* _NETFILTER_NF_NAT_H */
diff --git a/include/statement.h b/include/statement.h
index 574835cd..e5232542 100644
--- a/include/statement.h
+++ b/include/statement.h
@@ -68,6 +68,7 @@ struct nat_stmt {
 	enum nft_nat_types	type;
 	struct expr		*addr;
 	struct expr		*proto;
+	uint32_t		flags;
 };
 
 extern struct stmt *nat_stmt_alloc(const struct location *loc);