netfilter: flow table support for the mixed IPv4/IPv6 family

This patch adds the IPv6 flow table type, that implements the datapath
flow table to forward IPv6 traffic.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_flow_table.h

@@ -111,6 +111,11 @@ struct flow_ports {
 	__be16 source, dest;
 };
 
+unsigned int nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
+				     const struct nf_hook_state *state);
+unsigned int nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
+				       const struct nf_hook_state *state);
+
 #define MODULE_ALIAS_NF_FLOWTABLE(family)	\
 	MODULE_ALIAS("nf-flowtable-" __stringify(family))
 

net/ipv4/netfilter/nf_flow_table_ipv4.c

@@ -202,7 +202,7 @@ static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rtable *rt)
 	return false;
 }
 
-static unsigned int
+unsigned int
 nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 			const struct nf_hook_state *state)
 {
@@ -254,6 +254,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 
 	return NF_STOLEN;
 }
+EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
 
 static struct nf_flowtable_type flowtable_ipv4 = {
 	.family		= NFPROTO_IPV4,

net/ipv6/netfilter/nf_flow_table_ipv6.c

@@ -196,7 +196,7 @@ static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rt6_info *rt)
 	return false;
 }
 
-static unsigned int
+unsigned int
 nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 			  const struct nf_hook_state *state)
 {
@@ -248,6 +248,7 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 
 	return NF_STOLEN;
 }
+EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);
 
 static struct nf_flowtable_type flowtable_ipv6 = {
 	.family		= NFPROTO_IPV6,

net/netfilter/Kconfig

@@ -657,6 +657,14 @@ endif # NF_TABLES_NETDEV
 
 endif # NF_TABLES
 
+config NF_FLOW_TABLE_INET
+	select NF_FLOW_TABLE
+	tristate "Netfilter flow table mixed IPv4/IPv6 module"
+	help
+          This option adds the flow table mixed IPv4/IPv6 support.
+
+	  To compile it as a module, choose M here.
+
 config NF_FLOW_TABLE
 	tristate "Netfilter flow table module"
 	help

net/netfilter/Makefile

@@ -111,6 +111,7 @@ obj-$(CONFIG_NFT_FWD_NETDEV)	+= nft_fwd_netdev.o
 
 # flow table infrastructure
 obj-$(CONFIG_NF_FLOW_TABLE)	+= nf_flow_table.o
+obj-$(CONFIG_NF_FLOW_TABLE_INET) += nf_flow_table_inet.o
 
 # generic X tables 
 obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o

net/netfilter/nf_flow_table_inet.c

+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/rhashtable.h>
+#include <net/netfilter/nf_flow_table.h>
+#include <net/netfilter/nf_tables.h>
+
+static unsigned int
+nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb,
+			  const struct nf_hook_state *state)
+{
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		return nf_flow_offload_ip_hook(priv, skb, state);
+	case htons(ETH_P_IPV6):
+		return nf_flow_offload_ipv6_hook(priv, skb, state);
+	}
+
+	return NF_ACCEPT;
+}
+
+static struct nf_flowtable_type flowtable_inet = {
+	.family		= NFPROTO_INET,
+	.params		= &nf_flow_offload_rhash_params,
+	.gc		= nf_flow_offload_work_gc,
+	.hook		= nf_flow_offload_inet_hook,
+	.owner		= THIS_MODULE,
+};
+
+static int __init nf_flow_inet_module_init(void)
+{
+	nft_register_flowtable_type(&flowtable_inet);
+
+	return 0;
+}
+
+static void __exit nf_flow_inet_module_exit(void)
+{
+	nft_unregister_flowtable_type(&flowtable_inet);
+}
+
+module_init(nf_flow_inet_module_init);
+module_exit(nf_flow_inet_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NF_FLOWTABLE(1); /* NFPROTO_INET */