netfilter: nf_tables: Add support for IPv6 NAT

This patch generalizes the NAT expression to support both IPv4 and IPv6
using the existing IPv4/IPv6 NAT infrastructure. This also adds the
NAT chain type for IPv6.

This patch collapses the following patches that were posted to the
netfilter-devel mailing list, from Tomasz:

* nf_tables: Change NFTA_NAT_ attributes to better semantic significance
* nf_tables: Split IPv4 NAT into NAT expression and IPv4 NAT chain
* nf_tables: Add support for IPv6 NAT expression
* nf_tables: Add support for IPv6 NAT chain
* nf_tables: Fix up build issue on IPv6 NAT support

And, from Pablo Neira Ayuso:

* fix missing dependencies in nft_chain_nat

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -695,18 +695,20 @@ enum nft_nat_types {
  * enum nft_nat_attributes - nf_tables nat expression netlink attributes
  *
  * @NFTA_NAT_TYPE: NAT type (NLA_U32: nft_nat_types)
- * @NFTA_NAT_ADDR_MIN: source register of address range start (NLA_U32: nft_registers)
- * @NFTA_NAT_ADDR_MAX: source register of address range end (NLA_U32: nft_registers)
- * @NFTA_NAT_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
- * @NFTA_NAT_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
+ * @NFTA_NAT_FAMILY: NAT family (NLA_U32)
+ * @NFTA_NAT_REG_ADDR_MIN: source register of address range start (NLA_U32: nft_registers)
+ * @NFTA_NAT_REG_ADDR_MAX: source register of address range end (NLA_U32: nft_registers)
+ * @NFTA_NAT_REG_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
+ * @NFTA_NAT_REG_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
  */
 enum nft_nat_attributes {
 	NFTA_NAT_UNSPEC,
 	NFTA_NAT_TYPE,
-	NFTA_NAT_ADDR_MIN,
-	NFTA_NAT_ADDR_MAX,
-	NFTA_NAT_PROTO_MIN,
-	NFTA_NAT_PROTO_MAX,
+	NFTA_NAT_FAMILY,
+	NFTA_NAT_REG_ADDR_MIN,
+	NFTA_NAT_REG_ADDR_MAX,
+	NFTA_NAT_REG_PROTO_MIN,
+	NFTA_NAT_REG_PROTO_MAX,
 	__NFTA_NAT_MAX
 };
 #define NFTA_NAT_MAX		(__NFTA_NAT_MAX - 1)

net/ipv4/netfilter/Kconfig

@@ -50,6 +50,7 @@ config NFT_CHAIN_ROUTE_IPV4
 
 config NFT_CHAIN_NAT_IPV4
 	depends on NF_TABLES_IPV4
+	depends on NF_NAT_IPV4 && NFT_NAT
 	tristate "IPv4 nf_tables nat chain support"
 
 config IP_NF_IPTABLES

net/ipv4/netfilter/nft_chain_nat_ipv4.c

@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
  * Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
+ * Copyright (c) 2012 Intel Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -14,10 +15,8 @@
 #include <linux/list.h>
 #include <linux/skbuff.h>
 #include <linux/ip.h>
-#include <linux/netlink.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv4.h>
-#include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_conntrack.h>
 #include <net/netfilter/nf_nat.h>
@@ -27,147 +26,6 @@
 #include <net/netfilter/nf_nat_l3proto.h>
 #include <net/ip.h>
 
-struct nft_nat {
-	enum nft_registers	sreg_addr_min:8;
-	enum nft_registers	sreg_addr_max:8;
-	enum nft_registers	sreg_proto_min:8;
-	enum nft_registers	sreg_proto_max:8;
-	enum nf_nat_manip_type	type;
-};
-
-static void nft_nat_eval(const struct nft_expr *expr,
-			 struct nft_data data[NFT_REG_MAX + 1],
-			 const struct nft_pktinfo *pkt)
-{
-	const struct nft_nat *priv = nft_expr_priv(expr);
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo);
-	struct nf_nat_range range;
-
-	memset(&range, 0, sizeof(range));
-	if (priv->sreg_addr_min) {
-		range.min_addr.ip = data[priv->sreg_addr_min].data[0];
-		range.max_addr.ip = data[priv->sreg_addr_max].data[0];
-		range.flags |= NF_NAT_RANGE_MAP_IPS;
-	}
-
-	if (priv->sreg_proto_min) {
-		range.min_proto.all = data[priv->sreg_proto_min].data[0];
-		range.max_proto.all = data[priv->sreg_proto_max].data[0];
-		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
-	}
-
-	data[NFT_REG_VERDICT].verdict =
-		nf_nat_setup_info(ct, &range, priv->type);
-}
-
-static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
-	[NFTA_NAT_ADDR_MIN]	= { .type = NLA_U32 },
-	[NFTA_NAT_ADDR_MAX]	= { .type = NLA_U32 },
-	[NFTA_NAT_PROTO_MIN]	= { .type = NLA_U32 },
-	[NFTA_NAT_PROTO_MAX]	= { .type = NLA_U32 },
-	[NFTA_NAT_TYPE]		= { .type = NLA_U32 },
-};
-
-static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
-			const struct nlattr * const tb[])
-{
-	struct nft_nat *priv = nft_expr_priv(expr);
-	int err;
-
-	if (tb[NFTA_NAT_TYPE] == NULL)
-		return -EINVAL;
-
-	switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
-	case NFT_NAT_SNAT:
-		priv->type = NF_NAT_MANIP_SRC;
-		break;
-	case NFT_NAT_DNAT:
-		priv->type = NF_NAT_MANIP_DST;
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	if (tb[NFTA_NAT_ADDR_MIN]) {
-		priv->sreg_addr_min = ntohl(nla_get_be32(tb[NFTA_NAT_ADDR_MIN]));
-		err = nft_validate_input_register(priv->sreg_addr_min);
-		if (err < 0)
-			return err;
-	}
-
-	if (tb[NFTA_NAT_ADDR_MAX]) {
-		priv->sreg_addr_max = ntohl(nla_get_be32(tb[NFTA_NAT_ADDR_MAX]));
-		err = nft_validate_input_register(priv->sreg_addr_max);
-		if (err < 0)
-			return err;
-	} else
-		priv->sreg_addr_max = priv->sreg_addr_min;
-
-	if (tb[NFTA_NAT_PROTO_MIN]) {
-		priv->sreg_proto_min = ntohl(nla_get_be32(tb[NFTA_NAT_PROTO_MIN]));
-		err = nft_validate_input_register(priv->sreg_proto_min);
-		if (err < 0)
-			return err;
-	}
-
-	if (tb[NFTA_NAT_PROTO_MAX]) {
-		priv->sreg_proto_max = ntohl(nla_get_be32(tb[NFTA_NAT_PROTO_MAX]));
-		err = nft_validate_input_register(priv->sreg_proto_max);
-		if (err < 0)
-			return err;
-	} else
-		priv->sreg_proto_max = priv->sreg_proto_min;
-
-	return 0;
-}
-
-static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
-{
-	const struct nft_nat *priv = nft_expr_priv(expr);
-
-	switch (priv->type) {
-	case NF_NAT_MANIP_SRC:
-		if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
-			goto nla_put_failure;
-		break;
-	case NF_NAT_MANIP_DST:
-		if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
-			goto nla_put_failure;
-		break;
-	}
-
-	if (nla_put_be32(skb, NFTA_NAT_ADDR_MIN, htonl(priv->sreg_addr_min)))
-		goto nla_put_failure;
-	if (nla_put_be32(skb, NFTA_NAT_ADDR_MAX, htonl(priv->sreg_addr_max)))
-		goto nla_put_failure;
-	if (nla_put_be32(skb, NFTA_NAT_PROTO_MIN, htonl(priv->sreg_proto_min)))
-		goto nla_put_failure;
-	if (nla_put_be32(skb, NFTA_NAT_PROTO_MAX, htonl(priv->sreg_proto_max)))
-		goto nla_put_failure;
-	return 0;
-
-nla_put_failure:
-	return -1;
-}
-
-static struct nft_expr_type nft_nat_type;
-static const struct nft_expr_ops nft_nat_ops = {
-	.type		= &nft_nat_type,
-	.size		= NFT_EXPR_SIZE(sizeof(struct nft_nat)),
-	.eval		= nft_nat_eval,
-	.init		= nft_nat_init,
-	.dump		= nft_nat_dump,
-};
-
-static struct nft_expr_type nft_nat_type __read_mostly = {
-	.name		= "nat",
-	.ops		= &nft_nat_ops,
-	.policy		= nft_nat_policy,
-	.maxattr	= NFTA_NAT_MAX,
-	.owner		= THIS_MODULE,
-};
-
 /*
  * NAT chains
  */
@@ -306,7 +164,7 @@ static unsigned int nf_nat_output(const struct nf_hook_ops *ops,
 	return ret;
 }
 
-struct nf_chain_type nft_chain_nat_ipv4 = {
+static struct nf_chain_type nft_chain_nat_ipv4 = {
 	.family		= NFPROTO_IPV4,
 	.name		= "nat",
 	.type		= NFT_CHAIN_T_NAT,
@@ -331,20 +189,11 @@ static int __init nft_chain_nat_init(void)
 	if (err < 0)
 		return err;
 
-	err = nft_register_expr(&nft_nat_type);
-	if (err < 0)
-		goto err;
-
 	return 0;
-
-err:
-	nft_unregister_chain_type(&nft_chain_nat_ipv4);
-	return err;
 }
 
 static void __exit nft_chain_nat_exit(void)
 {
-	nft_unregister_expr(&nft_nat_type);
 	nft_unregister_chain_type(&nft_chain_nat_ipv4);
 }
 
@@ -354,4 +203,3 @@ module_exit(nft_chain_nat_exit);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 MODULE_ALIAS_NFT_CHAIN(AF_INET, "nat");
-MODULE_ALIAS_NFT_EXPR("nat");

net/ipv6/netfilter/Kconfig

@@ -33,6 +33,11 @@ config NFT_CHAIN_ROUTE_IPV6
 	depends on NF_TABLES_IPV6
 	tristate "IPv6 nf_tables route chain support"
 
+config NFT_CHAIN_NAT_IPV6
+	depends on NF_TABLES_IPV6
+	depends on NF_NAT_IPV6 && NFT_NAT
+	tristate "IPv6 nf_tables nat chain support"
+
 config IP6_NF_IPTABLES
 	tristate "IP6 tables support (required for filtering)"
 	depends on INET && IPV6

net/ipv6/netfilter/Makefile

@@ -26,6 +26,7 @@ obj-$(CONFIG_NF_DEFRAG_IPV6) += nf_defrag_ipv6.o
 # nf_tables
 obj-$(CONFIG_NF_TABLES_IPV6) += nf_tables_ipv6.o
 obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o
+obj-$(CONFIG_NFT_CHAIN_NAT_IPV6) += nft_chain_nat_ipv6.o
 
 # matches
 obj-$(CONFIG_IP6_NF_MATCH_AH) += ip6t_ah.o