netfilter: nf_flow_table_offload: add IPv6 support

Add nf_flow_rule_route_ipv6() and use it from the IPv6 and the inet
flowtable type definitions. Rename the nf_flow_rule_route() function to
nf_flow_rule_route_ipv4().

Adjust maximum number of actions, which now becomes 16 to leave
sufficient room for the IPv6 address mangling for NAT.

Signed-off-by: Pablo Neira Ayuso <[e-mail]>

include/net/netfilter/nf_flow_table.h

···
 int nf_flow_table_offload_setup(struct nf_flowtable *flowtable,
 				struct net_device *dev,
 				enum flow_block_command cmd);
-int nf_flow_rule_route(struct net *net, const struct flow_offload *flow,
-		       enum flow_offload_tuple_dir dir,
-		       struct nf_flow_rule *flow_rule);
+int nf_flow_rule_route_ipv4(struct net *net, const struct flow_offload *flow,
+			    enum flow_offload_tuple_dir dir,
+			    struct nf_flow_rule *flow_rule);
+int nf_flow_rule_route_ipv6(struct net *net, const struct flow_offload *flow,
+			    enum flow_offload_tuple_dir dir,
+			    struct nf_flow_rule *flow_rule);
 
 int nf_flow_table_offload_init(void);
 void nf_flow_table_offload_exit(void);

net/ipv4/netfilter/nf_flow_table_ipv4.c

···
 	.family		= NFPROTO_IPV4,
 	.init		= nf_flow_table_init,
 	.setup		= nf_flow_table_offload_setup,
-	.action		= nf_flow_rule_route,
+	.action		= nf_flow_rule_route_ipv4,
 	.free		= nf_flow_table_free,
 	.hook		= nf_flow_offload_ip_hook,
 	.owner		= THIS_MODULE,

net/ipv6/netfilter/nf_flow_table_ipv6.c

···
 	.family		= NFPROTO_IPV6,
 	.init		= nf_flow_table_init,
 	.setup		= nf_flow_table_offload_setup,
-	.action		= nf_flow_rule_route,
+	.action		= nf_flow_rule_route_ipv6,
 	.free		= nf_flow_table_free,
 	.hook		= nf_flow_offload_ipv6_hook,
 	.owner		= THIS_MODULE,

net/netfilter/nf_flow_table_inet.c

···
 	return NF_ACCEPT;
 }
 
+static int nf_flow_rule_route_inet(struct net *net,
+				   const struct flow_offload *flow,
+				   enum flow_offload_tuple_dir dir,
+				   struct nf_flow_rule *flow_rule)
+{
+	const struct flow_offload_tuple *flow_tuple = &flow->tuplehash[dir].tuple;
+	int err;
+
+	switch (flow_tuple->l3proto) {
+	case NFPROTO_IPV4:
+		err = nf_flow_rule_route_ipv4(net, flow, dir, flow_rule);
+		break;
+	case NFPROTO_IPV6:
+		err = nf_flow_rule_route_ipv6(net, flow, dir, flow_rule);
+		break;
+	default:
+		err = -1;
+		break;
+	}
+
+	return err;
+}
+
 static struct nf_flowtable_type flowtable_inet = {
 	.family		= NFPROTO_INET,
 	.init		= nf_flow_table_init,
 	.setup		= nf_flow_table_offload_setup,
-	.action		= nf_flow_rule_route,
+	.action		= nf_flow_rule_route_inet,
 	.free		= nf_flow_table_free,
 	.hook		= nf_flow_offload_inet_hook,
 	.owner		= THIS_MODULE,

net/netfilter/nf_flow_table_offload.c

···
 			    (u8 *)&addr, (u8 *)&mask);
 }
 
+static void flow_offload_ipv6_mangle(struct nf_flow_rule *flow_rule,
+				     unsigned int offset,
+				     u8 *addr, u8 *mask)
+{
+	struct flow_action_entry *entry;
+	int i;
+
+	for (i = 0; i < sizeof(struct in6_addr) / sizeof(u32); i += sizeof(u32)) {
+		entry = flow_action_entry_next(flow_rule);
+		flow_offload_mangle(entry, FLOW_ACT_MANGLE_HDR_TYPE_IP6,
+				    offset + i,
+				    &addr[i], mask);
+	}
+}
+
+static void flow_offload_ipv6_snat(struct net *net,
+				   const struct flow_offload *flow,
+				   enum flow_offload_tuple_dir dir,
+				   struct nf_flow_rule *flow_rule)
+{
+	u32 mask = ~htonl(0xffffffff);
+	const u8 *addr;
+	u32 offset;
+
+	switch (dir) {
+	case FLOW_OFFLOAD_DIR_ORIGINAL:
+		addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6.s6_addr;
+		offset = offsetof(struct ipv6hdr, saddr);
+		break;
+	case FLOW_OFFLOAD_DIR_REPLY:
+		addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6.s6_addr;
+		offset = offsetof(struct ipv6hdr, daddr);
+		break;
+	default:
+		return;
+	}
+
+	flow_offload_ipv6_mangle(flow_rule, offset, (u8 *)addr, (u8 *)&mask);
+}
+
+static void flow_offload_ipv6_dnat(struct net *net,
+				   const struct flow_offload *flow,
+				   enum flow_offload_tuple_dir dir,
+				   struct nf_flow_rule *flow_rule)
+{
+	u32 mask = ~htonl(0xffffffff);
+	const u8 *addr;
+	u32 offset;
+
+	switch (dir) {
+	case FLOW_OFFLOAD_DIR_ORIGINAL:
+		addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6.s6_addr;
+		offset = offsetof(struct ipv6hdr, daddr);
+		break;
+	case FLOW_OFFLOAD_DIR_REPLY:
+		addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6.s6_addr;
+		offset = offsetof(struct ipv6hdr, saddr);
+		break;
+	default:
+		return;
+	}
+
+	flow_offload_ipv6_mangle(flow_rule, offset, (u8 *)addr, (u8 *)&mask);
+}
+
 static int flow_offload_l4proto(const struct flow_offload *flow)
 {
 	u8 protonum = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.l4proto;
···
 	dev_hold(rt->dst.dev);
 }
 
-int nf_flow_rule_route(struct net *net, const struct flow_offload *flow,
-		       enum flow_offload_tuple_dir dir,
-		       struct nf_flow_rule *flow_rule)
+int nf_flow_rule_route_ipv4(struct net *net, const struct flow_offload *flow,
+			    enum flow_offload_tuple_dir dir,
+			    struct nf_flow_rule *flow_rule)
 {
 	if (flow_offload_eth_src(net, flow, dir, flow_rule) < 0 ||
 	    flow_offload_eth_dst(net, flow, dir, flow_rule) < 0)
···
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(nf_flow_rule_route);
+EXPORT_SYMBOL_GPL(nf_flow_rule_route_ipv4);
+
+int nf_flow_rule_route_ipv6(struct net *net, const struct flow_offload *flow,
+			    enum flow_offload_tuple_dir dir,
+			    struct nf_flow_rule *flow_rule)
+{
+	if (flow_offload_eth_src(net, flow, dir, flow_rule) < 0 ||
+	    flow_offload_eth_dst(net, flow, dir, flow_rule) < 0)
+		return -1;
+
+	if (flow->flags & FLOW_OFFLOAD_SNAT) {
+		flow_offload_ipv6_snat(net, flow, dir, flow_rule);
+		flow_offload_port_snat(net, flow, dir, flow_rule);
+	}
+	if (flow->flags & FLOW_OFFLOAD_DNAT) {
+		flow_offload_ipv6_dnat(net, flow, dir, flow_rule);
+		flow_offload_port_dnat(net, flow, dir, flow_rule);
+	}
+
+	flow_offload_redirect(flow, dir, flow_rule);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_flow_rule_route_ipv6);
+
+#define NF_FLOW_RULE_ACTION_MAX	16
 
 static struct nf_flow_rule *
 nf_flow_offload_rule_alloc(struct net *net,
···
 	if (!flow_rule)
 		goto err_flow;
 
-	flow_rule->rule = flow_rule_alloc(10);
+	flow_rule->rule = flow_rule_alloc(NF_FLOW_RULE_ACTION_MAX);
 	if (!flow_rule->rule)
 		goto err_flow_rule;