netfilter: nf_tables: merge ipv4 and ipv6 nat chain types

Florian Westphal · ummakynes · commit db8ab38880e0 · 2019-03-01T14:36:59.000+01:00
Merge the ipv4 and ipv6 nat chain type. This is the last
missing piece which allows to provide inet family support
for nat in a follow patch.

The kconfig knobs for ipv4/ipv6 nat chain are removed, the
nat chain type will be built unconditionally if NFT_NAT
expression is enabled.

Before:
   text	   data	    bss	    dec	    hex	filename
   1576     896       0    2472     9a8 nft_chain_nat_ipv4.ko
   1697     896       0    2593     a21 nft_chain_nat_ipv6.ko

After:
   text	   data	    bss	    dec	    hex	filename
   1832     896       0    2728     aa8 nft_chain_nat.ko

Signed-off-by: Florian Westphal &lt;fw@strlen.de&gt;
Signed-off-by: Pablo Neira Ayuso &lt;pablo@netfilter.org&gt;
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
@@ -95,19 +95,6 @@ config NF_REJECT_IPV4
 	default m if NETFILTER_ADVANCED=n
 
 if NF_NAT
-
-if NF_TABLES
-config NFT_CHAIN_NAT_IPV4
-	depends on NF_TABLES_IPV4
-	tristate "IPv4 nf_tables nat chain support"
-	help
-	  This option enables the "nat" chain for IPv4 in nf_tables. This
-	  chain type is used to perform Network Address Translation (NAT)
-	  packet transformations such as the source, destination address and
-	  source and destination ports.
-
-endif # NF_TABLES
-
 config NF_NAT_SNMP_BASIC
 	tristate "Basic SNMP-ALG support"
 	depends on NF_CONNTRACK_SNMP
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
@@ -25,7 +25,6 @@ $(obj)/nf_nat_snmp_basic_main.o: $(obj)/nf_nat_snmp_basic.asn1.h
 obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o
 
 obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV4) += nft_chain_route_ipv4.o
-obj-$(CONFIG_NFT_CHAIN_NAT_IPV4) += nft_chain_nat_ipv4.o
 obj-$(CONFIG_NFT_REJECT_IPV4) += nft_reject_ipv4.o
 obj-$(CONFIG_NFT_FIB_IPV4) += nft_fib_ipv4.o
 obj-$(CONFIG_NFT_DUP_IPV4) += nft_dup_ipv4.o
diff --git a/net/ipv4/netfilter/nft_chain_nat_ipv4.c b/net/ipv4/netfilter/nft_chain_nat_ipv4.c
diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
@@ -31,17 +31,6 @@ config NFT_CHAIN_ROUTE_IPV6
 	  fields such as the source, destination, flowlabel, hop-limit and
 	  the packet mark.
 
-if NF_NAT
-
-config NFT_CHAIN_NAT_IPV6
-	tristate "IPv6 nf_tables nat chain support"
-	help
-	  This option enables the "nat" chain for IPv6 in nf_tables. This
-	  chain type is used to perform Network Address Translation (NAT)
-	  packet transformations such as the source, destination address and
-	  source and destination ports.
-endif # NF_NAT
-
 config NFT_REJECT_IPV6
 	select NF_REJECT_IPV6
 	default NFT_REJECT
diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile
@@ -28,7 +28,6 @@ obj-$(CONFIG_NF_DUP_IPV6) += nf_dup_ipv6.o
 
 # nf_tables
 obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o
-obj-$(CONFIG_NFT_CHAIN_NAT_IPV6) += nft_chain_nat_ipv6.o
 obj-$(CONFIG_NFT_REJECT_IPV6) += nft_reject_ipv6.o
 obj-$(CONFIG_NFT_DUP_IPV6) += nft_dup_ipv6.o
 obj-$(CONFIG_NFT_FIB_IPV6) += nft_fib_ipv6.o
diff --git a/net/ipv6/netfilter/nft_chain_nat_ipv6.c b/net/ipv6/netfilter/nft_chain_nat_ipv6.c
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
@@ -550,6 +550,7 @@ config NFT_REDIR
 config NFT_NAT
 	depends on NF_CONNTRACK
 	select NF_NAT
+	depends on NF_TABLES_IPV4 || NF_TABLES_IPV6
 	tristate "Netfilter nf_tables nat module"
 	help
 	  This option adds the "nat" expression that you can use to perform
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
@@ -110,6 +110,8 @@ obj-$(CONFIG_NFT_OSF)		+= nft_osf.o
 obj-$(CONFIG_NFT_TPROXY)	+= nft_tproxy.o
 obj-$(CONFIG_NFT_XFRM)		+= nft_xfrm.o
 
+obj-$(CONFIG_NFT_NAT)		+= nft_chain_nat.o
+
 # nf_tables netdev
 obj-$(CONFIG_NFT_DUP_NETDEV)	+= nft_dup_netdev.o
 obj-$(CONFIG_NFT_FWD_NETDEV)	+= nft_fwd_netdev.o
diff --git a/net/netfilter/nft_chain_nat.c b/net/netfilter/nft_chain_nat.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/module.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_ipv4.h>
+#include <net/netfilter/nf_tables_ipv6.h>
+
+static unsigned int nft_nat_do_chain(void *priv, struct sk_buff *skb,
+				     const struct nf_hook_state *state)
+{
+	struct nft_pktinfo pkt;
+
+	nft_set_pktinfo(&pkt, skb, state);
+
+	switch (state->pf) {
+#ifdef CONFIG_NF_TABLES_IPV4
+	case NFPROTO_IPV4:
+		nft_set_pktinfo_ipv4(&pkt, skb);
+		break;
+#endif
+#ifdef CONFIG_NF_TABLES_IPV6
+	case NFPROTO_IPV6:
+		nft_set_pktinfo_ipv6(&pkt, skb);
+		break;
+#endif
+	default:
+		break;
+	}
+
+	return nft_do_chain(&pkt, priv);
+}
+
+#ifdef CONFIG_NF_TABLES_IPV4
+static const struct nft_chain_type nft_chain_nat_ipv4 = {
+	.name		= "nat",
+	.type		= NFT_CHAIN_T_NAT,
+	.family		= NFPROTO_IPV4,
+	.owner		= THIS_MODULE,
+	.hook_mask	= (1 << NF_INET_PRE_ROUTING) |
+			  (1 << NF_INET_POST_ROUTING) |
+			  (1 << NF_INET_LOCAL_OUT) |
+			  (1 << NF_INET_LOCAL_IN),
+	.hooks		= {
+		[NF_INET_PRE_ROUTING]	= nft_nat_do_chain,
+		[NF_INET_POST_ROUTING]	= nft_nat_do_chain,
+		[NF_INET_LOCAL_OUT]	= nft_nat_do_chain,
+		[NF_INET_LOCAL_IN]	= nft_nat_do_chain,
+	},
+	.ops_register = nf_nat_ipv4_register_fn,
+	.ops_unregister = nf_nat_ipv4_unregister_fn,
+};
+#endif
+
+#ifdef CONFIG_NF_TABLES_IPV6
+static const struct nft_chain_type nft_chain_nat_ipv6 = {
+	.name		= "nat",
+	.type		= NFT_CHAIN_T_NAT,
+	.family		= NFPROTO_IPV6,
+	.owner		= THIS_MODULE,
+	.hook_mask	= (1 << NF_INET_PRE_ROUTING) |
+			  (1 << NF_INET_POST_ROUTING) |
+			  (1 << NF_INET_LOCAL_OUT) |
+			  (1 << NF_INET_LOCAL_IN),
+	.hooks		= {
+		[NF_INET_PRE_ROUTING]	= nft_nat_do_chain,
+		[NF_INET_POST_ROUTING]	= nft_nat_do_chain,
+		[NF_INET_LOCAL_OUT]	= nft_nat_do_chain,
+		[NF_INET_LOCAL_IN]	= nft_nat_do_chain,
+	},
+	.ops_register		= nf_nat_ipv6_register_fn,
+	.ops_unregister		= nf_nat_ipv6_unregister_fn,
+};
+#endif
+
+static int __init nft_chain_nat_init(void)
+{
+#ifdef CONFIG_NF_TABLES_IPV6
+	nft_register_chain_type(&nft_chain_nat_ipv6);
+#endif
+#ifdef CONFIG_NF_TABLES_IPV4
+	nft_register_chain_type(&nft_chain_nat_ipv4);
+#endif
+
+	return 0;
+}
+
+static void __exit nft_chain_nat_exit(void)
+{
+#ifdef CONFIG_NF_TABLES_IPV4
+	nft_unregister_chain_type(&nft_chain_nat_ipv4);
+#endif
+#ifdef CONFIG_NF_TABLES_IPV6
+	nft_unregister_chain_type(&nft_chain_nat_ipv6);
+#endif
+}
+
+module_init(nft_chain_nat_init);
+module_exit(nft_chain_nat_exit);
+
+MODULE_LICENSE("GPL");
+#ifdef CONFIG_NF_TABLES_IPV4
+MODULE_ALIAS_NFT_CHAIN(AF_INET, "nat");
+#endif
+#ifdef CONFIG_NF_TABLES_IPV6
+MODULE_ALIAS_NFT_CHAIN(AF_INET6, "nat");
+#endif
