1 files changed, 763 insertions, 0 deletions

diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
new file mode 100644
index 000000000..e45fade76
--- /dev/null
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -0,0 +1,763 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/rhashtable.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/netdevice.h>
+#include <linux/if_ether.h>
+#include <net/gso.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/neighbour.h>
+#include <net/netfilter/nf_flow_table.h>
+#include <net/netfilter/nf_conntrack_acct.h>
+/* For layer 4 checksum field offset. */
+#include <linux/tcp.h>
+#include <linux/udp.h>
+
+static int nf_flow_state_check(struct flow_offload *flow, int proto,
+			       struct sk_buff *skb, unsigned int thoff)
+{
+	struct tcphdr *tcph;
+
+	if (proto != IPPROTO_TCP)
+		return 0;
+
+	tcph = (void *)(skb_network_header(skb) + thoff);
+	if (unlikely(tcph->fin || tcph->rst)) {
+		flow_offload_teardown(flow);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
+			       __be32 addr, __be32 new_addr)
+{
+	struct tcphdr *tcph;
+
+	tcph = (void *)(skb_network_header(skb) + thoff);
+	inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
+}
+
+static void nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
+			       __be32 addr, __be32 new_addr)
+{
+	struct udphdr *udph;
+
+	udph = (void *)(skb_network_header(skb) + thoff);
+	if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
+		inet_proto_csum_replace4(&udph->check, skb, addr,
+					 new_addr, true);
+		if (!udph->check)
+			udph->check = CSUM_MANGLED_0;
+	}
+}
+
+static void nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
+				   unsigned int thoff, __be32 addr,
+				   __be32 new_addr)
+{
+	switch (iph->protocol) {
+	case IPPROTO_TCP:
+		nf_flow_nat_ip_tcp(skb, thoff, addr, new_addr);
+		break;
+	case IPPROTO_UDP:
+		nf_flow_nat_ip_udp(skb, thoff, addr, new_addr);
+		break;
+	}
+}
+
+static void nf_flow_snat_ip(const struct flow_offload *flow,
+			    struct sk_buff *skb, struct iphdr *iph,
+			    unsigned int thoff, enum flow_offload_tuple_dir dir)
+{
+	__be32 addr, new_addr;
+
+	switch (dir) {
+	case FLOW_OFFLOAD_DIR_ORIGINAL:
+		addr = iph->saddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
+		iph->saddr = new_addr;
+		break;
+	case FLOW_OFFLOAD_DIR_REPLY:
+		addr = iph->daddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
+		iph->daddr = new_addr;
+		break;
+	}
+	csum_replace4(&iph->check, addr, new_addr);
+
+	nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
+}
+
+static void nf_flow_dnat_ip(const struct flow_offload *flow,
+			    struct sk_buff *skb, struct iphdr *iph,
+			    unsigned int thoff, enum flow_offload_tuple_dir dir)
+{
+	__be32 addr, new_addr;
+
+	switch (dir) {
+	case FLOW_OFFLOAD_DIR_ORIGINAL:
+		addr = iph->daddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
+		iph->daddr = new_addr;
+		break;
+	case FLOW_OFFLOAD_DIR_REPLY:
+		addr = iph->saddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
+		iph->saddr = new_addr;
+		break;
+	}
+	csum_replace4(&iph->check, addr, new_addr);
+
+	nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
+}
+
+static void nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
+			  unsigned int thoff, enum flow_offload_tuple_dir dir,
+			  struct iphdr *iph)
+{
+	if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
+		nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir);
+		nf_flow_snat_ip(flow, skb, iph, thoff, dir);
+	}
+	if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
+		nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir);
+		nf_flow_dnat_ip(flow, skb, iph, thoff, dir);
+	}
+}
+
+static bool ip_has_options(unsigned int thoff)
+{
+	return thoff != sizeof(struct iphdr);
+}
+
+static void nf_flow_tuple_encap(struct sk_buff *skb,
+				struct flow_offload_tuple *tuple)
+{
+	struct vlan_ethhdr *veth;
+	struct pppoe_hdr *phdr;
+	int i = 0;
+
+	if (skb_vlan_tag_present(skb)) {
+		tuple->encap[i].id = skb_vlan_tag_get(skb);
+		tuple->encap[i].proto = skb->vlan_proto;
+		i++;
+	}
+	switch (skb->protocol) {
+	case htons(ETH_P_8021Q):
+		veth = (struct vlan_ethhdr *)skb_mac_header(skb);
+		tuple->encap[i].id = ntohs(veth->h_vlan_TCI);
+		tuple->encap[i].proto = skb->protocol;
+		break;
+	case htons(ETH_P_PPP_SES):
+		phdr = (struct pppoe_hdr *)skb_mac_header(skb);
+		tuple->encap[i].id = ntohs(phdr->sid);
+		tuple->encap[i].proto = skb->protocol;
+		break;
+	}
+}
+
+struct nf_flowtable_ctx {
+	const struct net_device	*in;
+	u32			offset;
+	u32			hdrsize;
+};
+
+static int nf_flow_tuple_ip(struct nf_flowtable_ctx *ctx, struct sk_buff *skb,
+			    struct flow_offload_tuple *tuple)
+{
+	struct flow_ports *ports;
+	unsigned int thoff;
+	struct iphdr *iph;
+	u8 ipproto;
+
+	if (!pskb_may_pull(skb, sizeof(*iph) + ctx->offset))
+		return -1;
+
+	iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
+	thoff = (iph->ihl * 4);
+
+	if (ip_is_fragment(iph) ||
+	    unlikely(ip_has_options(thoff)))
+		return -1;
+
+	thoff += ctx->offset;
+
+	ipproto = iph->protocol;
+	switch (ipproto) {
+	case IPPROTO_TCP:
+		ctx->hdrsize = sizeof(struct tcphdr);
+		break;
+	case IPPROTO_UDP:
+		ctx->hdrsize = sizeof(struct udphdr);
+		break;
+#ifdef CONFIG_NF_CT_PROTO_GRE
+	case IPPROTO_GRE:
+		ctx->hdrsize = sizeof(struct gre_base_hdr);
+		break;
+#endif
+	default:
+		return -1;
+	}
+
+	if (iph->ttl <= 1)
+		return -1;
+
+	if (!pskb_may_pull(skb, thoff + ctx->hdrsize))
+		return -1;
+
+	switch (ipproto) {
+	case IPPROTO_TCP:
+	case IPPROTO_UDP:
+		ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
+		tuple->src_port		= ports->source;
+		tuple->dst_port		= ports->dest;
+		break;
+	case IPPROTO_GRE: {
+		struct gre_base_hdr *greh;
+
+		greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
+		if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
+			return -1;
+		break;
+	}
+	}
+
+	iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
+
+	tuple->src_v4.s_addr	= iph->saddr;
+	tuple->dst_v4.s_addr	= iph->daddr;
+	tuple->l3proto		= AF_INET;
+	tuple->l4proto		= ipproto;
+	tuple->iifidx		= ctx->in->ifindex;
+	nf_flow_tuple_encap(skb, tuple);
+
+	return 0;
+}
+
+/* Based on ip_exceeds_mtu(). */
+static bool nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
+{
+	if (skb->len <= mtu)
+		return false;
+
+	if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
+		return false;
+
+	return true;
+}
+
+static inline bool nf_flow_dst_check(struct flow_offload_tuple *tuple)
+{
+	if (tuple->xmit_type != FLOW_OFFLOAD_XMIT_NEIGH &&
+	    tuple->xmit_type != FLOW_OFFLOAD_XMIT_XFRM)
+		return true;
+
+	return dst_check(tuple->dst_cache, tuple->dst_cookie);
+}
+
+static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
+				      const struct nf_hook_state *state,
+				      struct dst_entry *dst)
+{
+	skb_orphan(skb);
+	skb_dst_set_noref(skb, dst);
+	dst_output(state->net, state->sk, skb);
+	return NF_STOLEN;
+}
+
+static bool nf_flow_skb_encap_protocol(const struct sk_buff *skb, __be16 proto,
+				       u32 *offset)
+{
+	struct vlan_ethhdr *veth;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_8021Q):
+		veth = (struct vlan_ethhdr *)skb_mac_header(skb);
+		if (veth->h_vlan_encapsulated_proto == proto) {
+			*offset += VLAN_HLEN;
+			return true;
+		}
+		break;
+	case htons(ETH_P_PPP_SES):
+		if (nf_flow_pppoe_proto(skb) == proto) {
+			*offset += PPPOE_SES_HLEN;
+			return true;
+		}
+		break;
+	}
+
+	return false;
+}
+
+static void nf_flow_encap_pop(struct sk_buff *skb,
+			      struct flow_offload_tuple_rhash *tuplehash)
+{
+	struct vlan_hdr *vlan_hdr;
+	int i;
+
+	for (i = 0; i < tuplehash->tuple.encap_num; i++) {
+		if (skb_vlan_tag_present(skb)) {
+			__vlan_hwaccel_clear_tag(skb);
+			continue;
+		}
+		switch (skb->protocol) {
+		case htons(ETH_P_8021Q):
+			vlan_hdr = (struct vlan_hdr *)skb->data;
+			__skb_pull(skb, VLAN_HLEN);
+			vlan_set_encap_proto(skb, vlan_hdr);
+			skb_reset_network_header(skb);
+			break;
+		case htons(ETH_P_PPP_SES):
+			skb->protocol = nf_flow_pppoe_proto(skb);
+			skb_pull(skb, PPPOE_SES_HLEN);
+			skb_reset_network_header(skb);
+			break;
+		}
+	}
+}
+
+static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,
+				       const struct flow_offload_tuple_rhash *tuplehash,
+				       unsigned short type)
+{
+	struct net_device *outdev;
+
+	outdev = dev_get_by_index_rcu(net, tuplehash->tuple.out.ifidx);
+	if (!outdev)
+		return NF_DROP;
+
+	skb->dev = outdev;
+	dev_hard_header(skb, skb->dev, type, tuplehash->tuple.out.h_dest,
+			tuplehash->tuple.out.h_source, skb->len);
+	dev_queue_xmit(skb);
+
+	return NF_STOLEN;
+}
+
+static struct flow_offload_tuple_rhash *
+nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx,
+		       struct nf_flowtable *flow_table, struct sk_buff *skb)
+{
+	struct flow_offload_tuple tuple = {};
+
+	if (skb->protocol != htons(ETH_P_IP) &&
+	    !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &ctx->offset))
+		return NULL;
+
+	if (nf_flow_tuple_ip(ctx, skb, &tuple) < 0)
+		return NULL;
+
+	return flow_offload_lookup(flow_table, &tuple);
+}
+
+static int nf_flow_offload_forward(struct nf_flowtable_ctx *ctx,
+				   struct nf_flowtable *flow_table,
+				   struct flow_offload_tuple_rhash *tuplehash,
+				   struct sk_buff *skb)
+{
+	enum flow_offload_tuple_dir dir;
+	struct flow_offload *flow;
+	unsigned int thoff, mtu;
+	struct iphdr *iph;
+
+	dir = tuplehash->tuple.dir;
+	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
+
+	mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset;
+	if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
+		return 0;
+
+	iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
+	thoff = (iph->ihl * 4) + ctx->offset;
+	if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
+		return 0;
+
+	if (!nf_flow_dst_check(&tuplehash->tuple)) {
+		flow_offload_teardown(flow);
+		return 0;
+	}
+
+	if (skb_try_make_writable(skb, thoff + ctx->hdrsize))
+		return -1;
+
+	flow_offload_refresh(flow_table, flow, false);
+
+	nf_flow_encap_pop(skb, tuplehash);
+	thoff -= ctx->offset;
+
+	iph = ip_hdr(skb);
+	nf_flow_nat_ip(flow, skb, thoff, dir, iph);
+
+	ip_decrease_ttl(iph);
+	skb_clear_tstamp(skb);
+
+	if (flow_table->flags & NF_FLOWTABLE_COUNTER)
+		nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
+
+	return 1;
+}
+
+unsigned int
+nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
+			const struct nf_hook_state *state)
+{
+	struct flow_offload_tuple_rhash *tuplehash;
+	struct nf_flowtable *flow_table = priv;
+	enum flow_offload_tuple_dir dir;
+	struct nf_flowtable_ctx ctx = {
+		.in	= state->in,
+	};
+	struct flow_offload *flow;
+	struct net_device *outdev;
+	struct rtable *rt;
+	__be32 nexthop;
+	int ret;
+
+	tuplehash = nf_flow_offload_lookup(&ctx, flow_table, skb);
+	if (!tuplehash)
+		return NF_ACCEPT;
+
+	ret = nf_flow_offload_forward(&ctx, flow_table, tuplehash, skb);
+	if (ret < 0)
+		return NF_DROP;
+	else if (ret == 0)
+		return NF_ACCEPT;
+
+	if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
+		rt = (struct rtable *)tuplehash->tuple.dst_cache;
+		memset(skb->cb, 0, sizeof(struct inet_skb_parm));
+		IPCB(skb)->iif = skb->dev->ifindex;
+		IPCB(skb)->flags = IPSKB_FORWARDED;
+		return nf_flow_xmit_xfrm(skb, state, &rt->dst);
+	}
+
+	dir = tuplehash->tuple.dir;
+	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
+
+	switch (tuplehash->tuple.xmit_type) {
+	case FLOW_OFFLOAD_XMIT_NEIGH:
+		rt = (struct rtable *)tuplehash->tuple.dst_cache;
+		outdev = rt->dst.dev;
+		skb->dev = outdev;
+		nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
+		skb_dst_set_noref(skb, &rt->dst);
+		neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
+		ret = NF_STOLEN;
+		break;
+	case FLOW_OFFLOAD_XMIT_DIRECT:
+		ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IP);
+		if (ret == NF_DROP)
+			flow_offload_teardown(flow);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		ret = NF_DROP;
+		break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
+
+static void nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
+				 struct in6_addr *addr,
+				 struct in6_addr *new_addr,
+				 struct ipv6hdr *ip6h)
+{
+	struct tcphdr *tcph;
+
+	tcph = (void *)(skb_network_header(skb) + thoff);
+	inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
+				  new_addr->s6_addr32, true);
+}
+
+static void nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
+				 struct in6_addr *addr,
+				 struct in6_addr *new_addr)
+{
+	struct udphdr *udph;
+
+	udph = (void *)(skb_network_header(skb) + thoff);
+	if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
+		inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
+					  new_addr->s6_addr32, true);
+		if (!udph->check)
+			udph->check = CSUM_MANGLED_0;
+	}
+}
+
+static void nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
+				     unsigned int thoff, struct in6_addr *addr,
+				     struct in6_addr *new_addr)
+{
+	switch (ip6h->nexthdr) {
+	case IPPROTO_TCP:
+		nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr, ip6h);
+		break;
+	case IPPROTO_UDP:
+		nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr);
+		break;
+	}
+}
+
+static void nf_flow_snat_ipv6(const struct flow_offload *flow,
+			      struct sk_buff *skb, struct ipv6hdr *ip6h,
+			      unsigned int thoff,
+			      enum flow_offload_tuple_dir dir)
+{
+	struct in6_addr addr, new_addr;
+
+	switch (dir) {
+	case FLOW_OFFLOAD_DIR_ORIGINAL:
+		addr = ip6h->saddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
+		ip6h->saddr = new_addr;
+		break;
+	case FLOW_OFFLOAD_DIR_REPLY:
+		addr = ip6h->daddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
+		ip6h->daddr = new_addr;
+		break;
+	}
+
+	nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
+}
+
+static void nf_flow_dnat_ipv6(const struct flow_offload *flow,
+			      struct sk_buff *skb, struct ipv6hdr *ip6h,
+			      unsigned int thoff,
+			      enum flow_offload_tuple_dir dir)
+{
+	struct in6_addr addr, new_addr;
+
+	switch (dir) {
+	case FLOW_OFFLOAD_DIR_ORIGINAL:
+		addr = ip6h->daddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
+		ip6h->daddr = new_addr;
+		break;
+	case FLOW_OFFLOAD_DIR_REPLY:
+		addr = ip6h->saddr;
+		new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
+		ip6h->saddr = new_addr;
+		break;
+	}
+
+	nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
+}
+
+static void nf_flow_nat_ipv6(const struct flow_offload *flow,
+			     struct sk_buff *skb,
+			     enum flow_offload_tuple_dir dir,
+			     struct ipv6hdr *ip6h)
+{
+	unsigned int thoff = sizeof(*ip6h);
+
+	if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
+		nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir);
+		nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir);
+	}
+	if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
+		nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir);
+		nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir);
+	}
+}
+
+static int nf_flow_tuple_ipv6(struct nf_flowtable_ctx *ctx, struct sk_buff *skb,
+			      struct flow_offload_tuple *tuple)
+{
+	struct flow_ports *ports;
+	struct ipv6hdr *ip6h;
+	unsigned int thoff;
+	u8 nexthdr;
+
+	thoff = sizeof(*ip6h) + ctx->offset;
+	if (!pskb_may_pull(skb, thoff))
+		return -1;
+
+	ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
+
+	nexthdr = ip6h->nexthdr;
+	switch (nexthdr) {
+	case IPPROTO_TCP:
+		ctx->hdrsize = sizeof(struct tcphdr);
+		break;
+	case IPPROTO_UDP:
+		ctx->hdrsize = sizeof(struct udphdr);
+		break;
+#ifdef CONFIG_NF_CT_PROTO_GRE
+	case IPPROTO_GRE:
+		ctx->hdrsize = sizeof(struct gre_base_hdr);
+		break;
+#endif
+	default:
+		return -1;
+	}
+
+	if (ip6h->hop_limit <= 1)
+		return -1;
+
+	if (!pskb_may_pull(skb, thoff + ctx->hdrsize))
+		return -1;
+
+	switch (nexthdr) {
+	case IPPROTO_TCP:
+	case IPPROTO_UDP:
+		ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
+		tuple->src_port		= ports->source;
+		tuple->dst_port		= ports->dest;
+		break;
+	case IPPROTO_GRE: {
+		struct gre_base_hdr *greh;
+
+		greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
+		if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
+			return -1;
+		break;
+	}
+	}
+
+	ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
+
+	tuple->src_v6		= ip6h->saddr;
+	tuple->dst_v6		= ip6h->daddr;
+	tuple->l3proto		= AF_INET6;
+	tuple->l4proto		= nexthdr;
+	tuple->iifidx		= ctx->in->ifindex;
+	nf_flow_tuple_encap(skb, tuple);
+
+	return 0;
+}
+
+static int nf_flow_offload_ipv6_forward(struct nf_flowtable_ctx *ctx,
+					struct nf_flowtable *flow_table,
+					struct flow_offload_tuple_rhash *tuplehash,
+					struct sk_buff *skb)
+{
+	enum flow_offload_tuple_dir dir;
+	struct flow_offload *flow;
+	unsigned int thoff, mtu;
+	struct ipv6hdr *ip6h;
+
+	dir = tuplehash->tuple.dir;
+	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
+
+	mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset;
+	if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
+		return 0;
+
+	ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
+	thoff = sizeof(*ip6h) + ctx->offset;
+	if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
+		return 0;
+
+	if (!nf_flow_dst_check(&tuplehash->tuple)) {
+		flow_offload_teardown(flow);
+		return 0;
+	}
+
+	if (skb_try_make_writable(skb, thoff + ctx->hdrsize))
+		return -1;
+
+	flow_offload_refresh(flow_table, flow, false);
+
+	nf_flow_encap_pop(skb, tuplehash);
+
+	ip6h = ipv6_hdr(skb);
+	nf_flow_nat_ipv6(flow, skb, dir, ip6h);
+
+	ip6h->hop_limit--;
+	skb_clear_tstamp(skb);
+
+	if (flow_table->flags & NF_FLOWTABLE_COUNTER)
+		nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
+
+	return 1;
+}
+
+static struct flow_offload_tuple_rhash *
+nf_flow_offload_ipv6_lookup(struct nf_flowtable_ctx *ctx,
+			    struct nf_flowtable *flow_table,
+			    struct sk_buff *skb)
+{
+	struct flow_offload_tuple tuple = {};
+
+	if (skb->protocol != htons(ETH_P_IPV6) &&
+	    !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IPV6), &ctx->offset))
+		return NULL;
+
+	if (nf_flow_tuple_ipv6(ctx, skb, &tuple) < 0)
+		return NULL;
+
+	return flow_offload_lookup(flow_table, &tuple);
+}
+
+unsigned int
+nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
+			  const struct nf_hook_state *state)
+{
+	struct flow_offload_tuple_rhash *tuplehash;
+	struct nf_flowtable *flow_table = priv;
+	enum flow_offload_tuple_dir dir;
+	struct nf_flowtable_ctx ctx = {
+		.in	= state->in,
+	};
+	const struct in6_addr *nexthop;
+	struct flow_offload *flow;
+	struct net_device *outdev;
+	struct rt6_info *rt;
+	int ret;
+
+	tuplehash = nf_flow_offload_ipv6_lookup(&ctx, flow_table, skb);
+	if (tuplehash == NULL)
+		return NF_ACCEPT;
+
+	ret = nf_flow_offload_ipv6_forward(&ctx, flow_table, tuplehash, skb);
+	if (ret < 0)
+		return NF_DROP;
+	else if (ret == 0)
+		return NF_ACCEPT;
+
+	if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
+		rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
+		memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
+		IP6CB(skb)->iif = skb->dev->ifindex;
+		IP6CB(skb)->flags = IP6SKB_FORWARDED;
+		return nf_flow_xmit_xfrm(skb, state, &rt->dst);
+	}
+
+	dir = tuplehash->tuple.dir;
+	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
+
+	switch (tuplehash->tuple.xmit_type) {
+	case FLOW_OFFLOAD_XMIT_NEIGH:
+		rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
+		outdev = rt->dst.dev;
+		skb->dev = outdev;
+		nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
+		skb_dst_set_noref(skb, &rt->dst);
+		neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
+		ret = NF_STOLEN;
+		break;
+	case FLOW_OFFLOAD_XMIT_DIRECT:
+		ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IPV6);
+		if (ret == NF_DROP)
+			flow_offload_teardown(flow);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		ret = NF_DROP;
+		break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);