net/ipv6/ip6_offload.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	IPV6 GSO/GRO offload support
  *	Linux INET6 implementation
  */

 #include <linux/kernel.h>
 #include <linux/socket.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/printk.h>

 #include <net/protocol.h>
 #include <net/ipv6.h>
 #include <net/inet_common.h>
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <net/gro.h>

 #include "ip6_offload.h"

 /* All GRO functions are always builtin, except UDP over ipv6, which lays in
  * ipv6 module, as it depends on UDPv6 lookup function, so we need special care
  * when ipv6 is built as a module
  */
 #if IS_BUILTIN(CONFIG_IPV6)
 #define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__)
 #else
 #define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_1(f, f2, __VA_ARGS__)
 #endif

 #define indirect_call_gro_receive_l4(f2, f1, cb, head, skb)	\
 ({								\
 	unlikely(gro_recursion_inc_test(skb)) ?			\
 		NAPI_GRO_CB(skb)->flush |= 1, NULL :		\
 		INDIRECT_CALL_L4(cb, f2, f1, head, skb);	\
 })

 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
 {
 	const struct net_offload *ops = NULL;

 	for (;;) {
 		struct ipv6_opt_hdr *opth;
 		int len;

 		if (proto != NEXTHDR_HOP) {
 			ops = rcu_dereference(inet6_offloads[proto]);

 			if (unlikely(!ops))
 				break;

 			if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
 				break;
 		}

 		if (unlikely(!pskb_may_pull(skb, 8)))
 			break;

 		opth = (void *)skb->data;
 		len = ipv6_optlen(opth);

 		if (unlikely(!pskb_may_pull(skb, len)))
 			break;

 		opth = (void *)skb->data;
 		proto = opth->nexthdr;
 		__skb_pull(skb, len);
 	}

 	return proto;
 }

 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 	netdev_features_t features)
 {
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
 	struct ipv6hdr *ipv6h;
 	const struct net_offload *ops;
 	int proto, nexthdr;
 	struct frag_hdr *fptr;
 	unsigned int payload_len;
 	u8 *prevhdr;
 	int offset = 0;
 	bool encap, udpfrag;
 	int nhoff;
 	bool gso_partial;

 	skb_reset_network_header(skb);
 	nexthdr = ipv6_has_hopopt_jumbo(skb);
 	if (nexthdr) {
 		const int hophdr_len = sizeof(struct hop_jumbo_hdr);
 		int err;

 		err = skb_cow_head(skb, 0);
 		if (err < 0)
 			return ERR_PTR(err);

 		/* remove the HBH header.
 		 * Layout: [Ethernet header][IPv6 header][HBH][TCP header]
 		 */
 		memmove(skb_mac_header(skb) + hophdr_len,
 			skb_mac_header(skb),
 			ETH_HLEN + sizeof(struct ipv6hdr));
 		skb->data += hophdr_len;
 		skb->len -= hophdr_len;
 		skb->network_header += hophdr_len;
 		skb->mac_header += hophdr_len;
 		ipv6h = (struct ipv6hdr *)skb->data;
 		ipv6h->nexthdr = nexthdr;
 	}
 	nhoff = skb_network_header(skb) - skb_mac_header(skb);
 	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 		goto out;

 	encap = SKB_GSO_CB(skb)->encap_level > 0;
 	if (encap)
 		features &= skb->dev->hw_enc_features;
 	SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);

 	ipv6h = ipv6_hdr(skb);
 	__skb_pull(skb, sizeof(*ipv6h));
 	segs = ERR_PTR(-EPROTONOSUPPORT);

 	proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);

 	if (skb->encapsulation &&
 	    skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 | SKB_GSO_IPXIP6))
 		udpfrag = proto == IPPROTO_UDP && encap &&
 			  (skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
 	else
 		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation &&
 			  (skb_shinfo(skb)->gso_type & SKB_GSO_UDP);

 	ops = rcu_dereference(inet6_offloads[proto]);
 	if (likely(ops && ops->callbacks.gso_segment)) {
 		skb_reset_transport_header(skb);
 		segs = ops->callbacks.gso_segment(skb, features);
 		if (!segs)
 			skb->network_header = skb_mac_header(skb) + nhoff - skb->head;
 	}

 	if (IS_ERR_OR_NULL(segs))
 		goto out;

 	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);

 	for (skb = segs; skb; skb = skb->next) {
 		ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
 		if (gso_partial && skb_is_gso(skb))
 			payload_len = skb_shinfo(skb)->gso_size +
 				      SKB_GSO_CB(skb)->data_offset +
 				      skb->head - (unsigned char *)(ipv6h + 1);
 		else
 			payload_len = skb->len - nhoff - sizeof(*ipv6h);
 		ipv6h->payload_len = htons(payload_len);
 		skb->network_header = (u8 *)ipv6h - skb->head;
 		skb_reset_mac_len(skb);

 		if (udpfrag) {
 			int err = ip6_find_1stfragopt(skb, &prevhdr);
 			if (err < 0) {
 				kfree_skb_list(segs);
 				return ERR_PTR(err);
 			}
 			fptr = (struct frag_hdr *)((u8 *)ipv6h + err);
 			fptr->frag_off = htons(offset);
 			if (skb->next)
 				fptr->frag_off |= htons(IP6_MF);
 			offset += (ntohs(ipv6h->payload_len) -
 				   sizeof(struct frag_hdr));
 		}
 		if (encap)
 			skb_reset_inner_headers(skb);
 	}

 out:
 	return segs;
 }

 /* Return the total length of all the extension hdrs, following the same
  * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
  */
 static int ipv6_exthdrs_len(struct ipv6hdr *iph,
 			    const struct net_offload **opps)
 {
 	struct ipv6_opt_hdr *opth = (void *)iph;
 	int len = 0, proto, optlen = sizeof(*iph);

 	proto = iph->nexthdr;
 	for (;;) {
 		if (proto != NEXTHDR_HOP) {
 			*opps = rcu_dereference(inet6_offloads[proto]);
 			if (unlikely(!(*opps)))
 				break;
 			if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
 				break;
 		}
 		opth = (void *)opth + optlen;
 		optlen = ipv6_optlen(opth);
 		len += optlen;
 		proto = opth->nexthdr;
 	}
 	return len;
 }

 INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
 							 struct sk_buff *skb)
 {
 	const struct net_offload *ops;
 	struct sk_buff *pp = NULL;
 	struct sk_buff *p;
 	struct ipv6hdr *iph;
 	unsigned int nlen;
 	unsigned int hlen;
 	unsigned int off;
 	u16 flush = 1;
 	int proto;

 	off = skb_gro_offset(skb);
 	hlen = off + sizeof(*iph);
 	iph = skb_gro_header_fast(skb, off);
 	if (skb_gro_header_hard(skb, hlen)) {
 		iph = skb_gro_header_slow(skb, hlen, off);
 		if (unlikely(!iph))
 			goto out;
 	}

 	skb_set_network_header(skb, off);
 	skb_gro_pull(skb, sizeof(*iph));
 	skb_set_transport_header(skb, skb_gro_offset(skb));

 	flush += ntohs(iph->payload_len) != skb_gro_len(skb);

 	proto = iph->nexthdr;
 	ops = rcu_dereference(inet6_offloads[proto]);
 	if (!ops || !ops->callbacks.gro_receive) {
 		__pskb_pull(skb, skb_gro_offset(skb));
 		skb_gro_frag0_invalidate(skb);
 		proto = ipv6_gso_pull_exthdrs(skb, proto);
 		skb_gro_pull(skb, -skb_transport_offset(skb));
 		skb_reset_transport_header(skb);
 		__skb_push(skb, skb_gro_offset(skb));

 		ops = rcu_dereference(inet6_offloads[proto]);
 		if (!ops || !ops->callbacks.gro_receive)
 			goto out;

 		iph = ipv6_hdr(skb);
 	}

 	NAPI_GRO_CB(skb)->proto = proto;

 	flush--;
 	nlen = skb_network_header_len(skb);

 	list_for_each_entry(p, head, list) {
 		const struct ipv6hdr *iph2;
 		__be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */

 		if (!NAPI_GRO_CB(p)->same_flow)
 			continue;

 		iph2 = (struct ipv6hdr *)(p->data + off);
 		first_word = *(__be32 *)iph ^ *(__be32 *)iph2;

 		/* All fields must match except length and Traffic Class.
 		 * XXX skbs on the gro_list have all been parsed and pulled
 		 * already so we don't need to compare nlen
 		 * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
 		 * memcmp() alone below is sufficient, right?
 		 */
 		 if ((first_word & htonl(0xF00FFFFF)) ||
 		     !ipv6_addr_equal(&iph->saddr, &iph2->saddr) ||
 		     !ipv6_addr_equal(&iph->daddr, &iph2->daddr) ||
 		     iph->nexthdr != iph2->nexthdr) {
 not_same_flow:
 			NAPI_GRO_CB(p)->same_flow = 0;
 			continue;
 		}
 		if (unlikely(nlen > sizeof(struct ipv6hdr))) {
 			if (memcmp(iph + 1, iph2 + 1,
 				   nlen - sizeof(struct ipv6hdr)))
 				goto not_same_flow;
 		}
 		/* flush if Traffic Class fields are different */
 		NAPI_GRO_CB(p)->flush |= !!((first_word & htonl(0x0FF00000)) |
 			(__force __be32)(iph->hop_limit ^ iph2->hop_limit));
 		NAPI_GRO_CB(p)->flush |= flush;

 		/* If the previous IP ID value was based on an atomic
 		 * datagram we can overwrite the value and ignore it.
 		 */
 		if (NAPI_GRO_CB(skb)->is_atomic)
 			NAPI_GRO_CB(p)->flush_id = 0;
 	}

 	NAPI_GRO_CB(skb)->is_atomic = true;
 	NAPI_GRO_CB(skb)->flush |= flush;

 	skb_gro_postpull_rcsum(skb, iph, nlen);

 	pp = indirect_call_gro_receive_l4(tcp6_gro_receive, udp6_gro_receive,
 					 ops->callbacks.gro_receive, head, skb);

 out:
 	skb_gro_flush_final(skb, pp, flush);

 	return pp;
 }

 static struct sk_buff *sit_ip6ip6_gro_receive(struct list_head *head,
 					      struct sk_buff *skb)
 {
 	/* Common GRO receive for SIT and IP6IP6 */

 	if (NAPI_GRO_CB(skb)->encap_mark) {
 		NAPI_GRO_CB(skb)->flush = 1;
 		return NULL;
 	}

 	NAPI_GRO_CB(skb)->encap_mark = 1;

 	return ipv6_gro_receive(head, skb);
 }

 static struct sk_buff *ip4ip6_gro_receive(struct list_head *head,
 					  struct sk_buff *skb)
 {
 	/* Common GRO receive for SIT and IP6IP6 */

 	if (NAPI_GRO_CB(skb)->encap_mark) {
 		NAPI_GRO_CB(skb)->flush = 1;
 		return NULL;
 	}

 	NAPI_GRO_CB(skb)->encap_mark = 1;

 	return inet_gro_receive(head, skb);
 }

 INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct net_offload *ops;
 	struct ipv6hdr *iph;
 	int err = -ENOSYS;
 	u32 payload_len;

 	if (skb->encapsulation) {
 		skb_set_inner_protocol(skb, cpu_to_be16(ETH_P_IPV6));
 		skb_set_inner_network_header(skb, nhoff);
 	}

 	payload_len = skb->len - nhoff - sizeof(*iph);
 	if (unlikely(payload_len > IPV6_MAXPLEN)) {
 		struct hop_jumbo_hdr *hop_jumbo;
 		int hoplen = sizeof(*hop_jumbo);

 		/* Move network header left */
 		memmove(skb_mac_header(skb) - hoplen, skb_mac_header(skb),
 			skb->transport_header - skb->mac_header);
 		skb->data -= hoplen;
 		skb->len += hoplen;
 		skb->mac_header -= hoplen;
 		skb->network_header -= hoplen;
 		iph = (struct ipv6hdr *)(skb->data + nhoff);
 		hop_jumbo = (struct hop_jumbo_hdr *)(iph + 1);

 		/* Build hop-by-hop options */
 		hop_jumbo->nexthdr = iph->nexthdr;
 		hop_jumbo->hdrlen = 0;
 		hop_jumbo->tlv_type = IPV6_TLV_JUMBO;
 		hop_jumbo->tlv_len = 4;
 		hop_jumbo->jumbo_payload_len = htonl(payload_len + hoplen);

 		iph->nexthdr = NEXTHDR_HOP;
 		iph->payload_len = 0;
 	} else {
 		iph = (struct ipv6hdr *)(skb->data + nhoff);
 		iph->payload_len = htons(payload_len);
 	}

 	nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out;

 	err = INDIRECT_CALL_L4(ops->callbacks.gro_complete, tcp6_gro_complete,
 			       udp6_gro_complete, skb, nhoff);

 out:
 	return err;
 }

 static int sit_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	skb->encapsulation = 1;
 	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
 	return ipv6_gro_complete(skb, nhoff);
 }

 static int ip6ip6_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	skb->encapsulation = 1;
 	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
 	return ipv6_gro_complete(skb, nhoff);
 }

 static int ip4ip6_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	skb->encapsulation = 1;
 	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
 	return inet_gro_complete(skb, nhoff);
 }

 static struct packet_offload ipv6_packet_offload __read_mostly = {
 	.type = cpu_to_be16(ETH_P_IPV6),
 	.callbacks = {
 		.gso_segment = ipv6_gso_segment,
 		.gro_receive = ipv6_gro_receive,
 		.gro_complete = ipv6_gro_complete,
 	},
 };

 static struct sk_buff *sit_gso_segment(struct sk_buff *skb,
 				       netdev_features_t features)
 {
 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP4))
 		return ERR_PTR(-EINVAL);

 	return ipv6_gso_segment(skb, features);
 }

 static struct sk_buff *ip4ip6_gso_segment(struct sk_buff *skb,
 					  netdev_features_t features)
 {
 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP6))
 		return ERR_PTR(-EINVAL);

 	return inet_gso_segment(skb, features);
 }

 static struct sk_buff *ip6ip6_gso_segment(struct sk_buff *skb,
 					  netdev_features_t features)
 {
 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP6))
 		return ERR_PTR(-EINVAL);

 	return ipv6_gso_segment(skb, features);
 }

 static const struct net_offload sit_offload = {
 	.callbacks = {
 		.gso_segment	= sit_gso_segment,
 		.gro_receive    = sit_ip6ip6_gro_receive,
 		.gro_complete   = sit_gro_complete,
 	},
 };

 static const struct net_offload ip4ip6_offload = {
 	.callbacks = {
 		.gso_segment	= ip4ip6_gso_segment,
 		.gro_receive    = ip4ip6_gro_receive,
 		.gro_complete   = ip4ip6_gro_complete,
 	},
 };

 static const struct net_offload ip6ip6_offload = {
 	.callbacks = {
 		.gso_segment	= ip6ip6_gso_segment,
 		.gro_receive    = sit_ip6ip6_gro_receive,
 		.gro_complete   = ip6ip6_gro_complete,
 	},
 };
 static int __init ipv6_offload_init(void)
 {

 	if (tcpv6_offload_init() < 0)
 		pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
 	if (ipv6_exthdrs_offload_init() < 0)
 		pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);

 	dev_add_offload(&ipv6_packet_offload);

 	inet_add_offload(&sit_offload, IPPROTO_IPV6);
 	inet6_add_offload(&ip6ip6_offload, IPPROTO_IPV6);
 	inet6_add_offload(&ip4ip6_offload, IPPROTO_IPIP);

 	return 0;
 }

 fs_initcall(ipv6_offload_init);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* IPV6 GSO/GRO offload support
	* Linux INET6 implementation
	*/

	#include <linux/kernel.h>
	#include <linux/socket.h>
	#include <linux/netdevice.h>
	#include <linux/skbuff.h>
	#include <linux/printk.h>

	#include <net/protocol.h>
	#include <net/ipv6.h>
	#include <net/inet_common.h>
	#include <net/tcp.h>
	#include <net/udp.h>
	#include <net/gro.h>

	#include "ip6_offload.h"

	/* All GRO functions are always builtin, except UDP over ipv6, which lays in
	* ipv6 module, as it depends on UDPv6 lookup function, so we need special care
	* when ipv6 is built as a module
	*/
	#if IS_BUILTIN(CONFIG_IPV6)
	#define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__)
	#else
	#define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_1(f, f2, __VA_ARGS__)
	#endif

	#define indirect_call_gro_receive_l4(f2, f1, cb, head, skb) \
	({ \
	unlikely(gro_recursion_inc_test(skb)) ? \
	NAPI_GRO_CB(skb)->flush \|= 1, NULL : \
	INDIRECT_CALL_L4(cb, f2, f1, head, skb); \
	})

	static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
	{
	const struct net_offload *ops = NULL;

	for (;;) {
	struct ipv6_opt_hdr *opth;
	int len;

	if (proto != NEXTHDR_HOP) {
	ops = rcu_dereference(inet6_offloads[proto]);

	if (unlikely(!ops))
	break;

	if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
	break;
	}

	if (unlikely(!pskb_may_pull(skb, 8)))
	break;

	opth = (void *)skb->data;
	len = ipv6_optlen(opth);

	if (unlikely(!pskb_may_pull(skb, len)))
	break;

	opth = (void *)skb->data;
	proto = opth->nexthdr;
	__skb_pull(skb, len);
	}

	return proto;
	}

	static struct sk_buff ipv6_gso_segment(struct sk_buff skb,
	netdev_features_t features)
	{
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	struct ipv6hdr *ipv6h;
	const struct net_offload *ops;
	int proto, nexthdr;
	struct frag_hdr *fptr;
	unsigned int payload_len;
	u8 *prevhdr;
	int offset = 0;
	bool encap, udpfrag;
	int nhoff;
	bool gso_partial;

	skb_reset_network_header(skb);
	nexthdr = ipv6_has_hopopt_jumbo(skb);
	if (nexthdr) {
	const int hophdr_len = sizeof(struct hop_jumbo_hdr);
	int err;

	err = skb_cow_head(skb, 0);
	if (err < 0)
	return ERR_PTR(err);

	/* remove the HBH header.
	* Layout: [Ethernet header][IPv6 header][HBH][TCP header]
	*/
	memmove(skb_mac_header(skb) + hophdr_len,
	skb_mac_header(skb),
	ETH_HLEN + sizeof(struct ipv6hdr));
	skb->data += hophdr_len;
	skb->len -= hophdr_len;
	skb->network_header += hophdr_len;
	skb->mac_header += hophdr_len;
	ipv6h = (struct ipv6hdr *)skb->data;
	ipv6h->nexthdr = nexthdr;
	}
	nhoff = skb_network_header(skb) - skb_mac_header(skb);
	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
	goto out;

	encap = SKB_GSO_CB(skb)->encap_level > 0;
	if (encap)
	features &= skb->dev->hw_enc_features;
	SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);

	ipv6h = ipv6_hdr(skb);
	__skb_pull(skb, sizeof(*ipv6h));
	segs = ERR_PTR(-EPROTONOSUPPORT);

	proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);

	if (skb->encapsulation &&
	skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 \| SKB_GSO_IPXIP6))
	udpfrag = proto == IPPROTO_UDP && encap &&
	(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
	else
	udpfrag = proto == IPPROTO_UDP && !skb->encapsulation &&
	(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);

	ops = rcu_dereference(inet6_offloads[proto]);
	if (likely(ops && ops->callbacks.gso_segment)) {
	skb_reset_transport_header(skb);
	segs = ops->callbacks.gso_segment(skb, features);
	if (!segs)
	skb->network_header = skb_mac_header(skb) + nhoff - skb->head;
	}

	if (IS_ERR_OR_NULL(segs))
	goto out;

	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);

	for (skb = segs; skb; skb = skb->next) {
	ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
	if (gso_partial && skb_is_gso(skb))
	payload_len = skb_shinfo(skb)->gso_size +
	SKB_GSO_CB(skb)->data_offset +
	skb->head - (unsigned char *)(ipv6h + 1);
	else
	payload_len = skb->len - nhoff - sizeof(*ipv6h);
	ipv6h->payload_len = htons(payload_len);
	skb->network_header = (u8 *)ipv6h - skb->head;
	skb_reset_mac_len(skb);

	if (udpfrag) {
	int err = ip6_find_1stfragopt(skb, &prevhdr);
	if (err < 0) {
	kfree_skb_list(segs);
	return ERR_PTR(err);
	}
	fptr = (struct frag_hdr )((u8 )ipv6h + err);
	fptr->frag_off = htons(offset);
	if (skb->next)
	fptr->frag_off \|= htons(IP6_MF);
	offset += (ntohs(ipv6h->payload_len) -
	sizeof(struct frag_hdr));
	}
	if (encap)
	skb_reset_inner_headers(skb);
	}

	out:
	return segs;
	}

	/* Return the total length of all the extension hdrs, following the same
	* logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
	*/
	static int ipv6_exthdrs_len(struct ipv6hdr *iph,
	const struct net_offload **opps)
	{
	struct ipv6_opt_hdr opth = (void )iph;
	int len = 0, proto, optlen = sizeof(*iph);

	proto = iph->nexthdr;
	for (;;) {
	if (proto != NEXTHDR_HOP) {
	*opps = rcu_dereference(inet6_offloads[proto]);
	if (unlikely(!(*opps)))
	break;
	if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
	break;
	}
	opth = (void *)opth + optlen;
	optlen = ipv6_optlen(opth);
	len += optlen;
	proto = opth->nexthdr;
	}
	return len;
	}

	INDIRECT_CALLABLE_SCOPE struct sk_buff ipv6_gro_receive(struct list_head head,
	struct sk_buff *skb)
	{
	const struct net_offload *ops;
	struct sk_buff *pp = NULL;
	struct sk_buff *p;
	struct ipv6hdr *iph;
	unsigned int nlen;
	unsigned int hlen;
	unsigned int off;
	u16 flush = 1;
	int proto;

	off = skb_gro_offset(skb);
	hlen = off + sizeof(*iph);
	iph = skb_gro_header_fast(skb, off);
	if (skb_gro_header_hard(skb, hlen)) {
	iph = skb_gro_header_slow(skb, hlen, off);
	if (unlikely(!iph))
	goto out;
	}

	skb_set_network_header(skb, off);
	skb_gro_pull(skb, sizeof(*iph));
	skb_set_transport_header(skb, skb_gro_offset(skb));

	flush += ntohs(iph->payload_len) != skb_gro_len(skb);

	proto = iph->nexthdr;
	ops = rcu_dereference(inet6_offloads[proto]);
	if (!ops \|\| !ops->callbacks.gro_receive) {
	__pskb_pull(skb, skb_gro_offset(skb));
	skb_gro_frag0_invalidate(skb);
	proto = ipv6_gso_pull_exthdrs(skb, proto);
	skb_gro_pull(skb, -skb_transport_offset(skb));
	skb_reset_transport_header(skb);
	__skb_push(skb, skb_gro_offset(skb));

	ops = rcu_dereference(inet6_offloads[proto]);
	if (!ops \|\| !ops->callbacks.gro_receive)
	goto out;

	iph = ipv6_hdr(skb);
	}

	NAPI_GRO_CB(skb)->proto = proto;

	flush--;
	nlen = skb_network_header_len(skb);

	list_for_each_entry(p, head, list) {
	const struct ipv6hdr *iph2;
	__be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */

	if (!NAPI_GRO_CB(p)->same_flow)
	continue;

	iph2 = (struct ipv6hdr *)(p->data + off);
	first_word = (__be32 )iph ^ (__be32 )iph2;

	/* All fields must match except length and Traffic Class.
	* XXX skbs on the gro_list have all been parsed and pulled
	* already so we don't need to compare nlen
	* (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
	* memcmp() alone below is sufficient, right?
	*/
	if ((first_word & htonl(0xF00FFFFF)) \|\|
	!ipv6_addr_equal(&iph->saddr, &iph2->saddr) \|\|
	!ipv6_addr_equal(&iph->daddr, &iph2->daddr) \|\|
	iph->nexthdr != iph2->nexthdr) {
	not_same_flow:
	NAPI_GRO_CB(p)->same_flow = 0;
	continue;
	}
	if (unlikely(nlen > sizeof(struct ipv6hdr))) {
	if (memcmp(iph + 1, iph2 + 1,
	nlen - sizeof(struct ipv6hdr)))
	goto not_same_flow;
	}
	/* flush if Traffic Class fields are different */
	NAPI_GRO_CB(p)->flush \|= !!((first_word & htonl(0x0FF00000)) \|
	(__force __be32)(iph->hop_limit ^ iph2->hop_limit));
	NAPI_GRO_CB(p)->flush \|= flush;

	/* If the previous IP ID value was based on an atomic
	* datagram we can overwrite the value and ignore it.
	*/
	if (NAPI_GRO_CB(skb)->is_atomic)
	NAPI_GRO_CB(p)->flush_id = 0;
	}

	NAPI_GRO_CB(skb)->is_atomic = true;
	NAPI_GRO_CB(skb)->flush \|= flush;

	skb_gro_postpull_rcsum(skb, iph, nlen);

	pp = indirect_call_gro_receive_l4(tcp6_gro_receive, udp6_gro_receive,
	ops->callbacks.gro_receive, head, skb);

	out:
	skb_gro_flush_final(skb, pp, flush);

	return pp;
	}

	static struct sk_buff sit_ip6ip6_gro_receive(struct list_head head,
	struct sk_buff *skb)
	{
	/* Common GRO receive for SIT and IP6IP6 */

	if (NAPI_GRO_CB(skb)->encap_mark) {
	NAPI_GRO_CB(skb)->flush = 1;
	return NULL;
	}

	NAPI_GRO_CB(skb)->encap_mark = 1;

	return ipv6_gro_receive(head, skb);
	}

	static struct sk_buff ip4ip6_gro_receive(struct list_head head,
	struct sk_buff *skb)
	{
	/* Common GRO receive for SIT and IP6IP6 */

	if (NAPI_GRO_CB(skb)->encap_mark) {
	NAPI_GRO_CB(skb)->flush = 1;
	return NULL;
	}

	NAPI_GRO_CB(skb)->encap_mark = 1;

	return inet_gro_receive(head, skb);
	}

	INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
	{
	const struct net_offload *ops;
	struct ipv6hdr *iph;
	int err = -ENOSYS;
	u32 payload_len;

	if (skb->encapsulation) {
	skb_set_inner_protocol(skb, cpu_to_be16(ETH_P_IPV6));
	skb_set_inner_network_header(skb, nhoff);
	}

	payload_len = skb->len - nhoff - sizeof(*iph);
	if (unlikely(payload_len > IPV6_MAXPLEN)) {
	struct hop_jumbo_hdr *hop_jumbo;
	int hoplen = sizeof(*hop_jumbo);

	/* Move network header left */
	memmove(skb_mac_header(skb) - hoplen, skb_mac_header(skb),
	skb->transport_header - skb->mac_header);
	skb->data -= hoplen;
	skb->len += hoplen;
	skb->mac_header -= hoplen;
	skb->network_header -= hoplen;
	iph = (struct ipv6hdr *)(skb->data + nhoff);
	hop_jumbo = (struct hop_jumbo_hdr *)(iph + 1);

	/* Build hop-by-hop options */
	hop_jumbo->nexthdr = iph->nexthdr;
	hop_jumbo->hdrlen = 0;
	hop_jumbo->tlv_type = IPV6_TLV_JUMBO;
	hop_jumbo->tlv_len = 4;
	hop_jumbo->jumbo_payload_len = htonl(payload_len + hoplen);

	iph->nexthdr = NEXTHDR_HOP;
	iph->payload_len = 0;
	} else {
	iph = (struct ipv6hdr *)(skb->data + nhoff);
	iph->payload_len = htons(payload_len);
	}

	nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
	if (WARN_ON(!ops \|\| !ops->callbacks.gro_complete))
	goto out;

	err = INDIRECT_CALL_L4(ops->callbacks.gro_complete, tcp6_gro_complete,
	udp6_gro_complete, skb, nhoff);

	out:
	return err;
	}

	static int sit_gro_complete(struct sk_buff *skb, int nhoff)
	{
	skb->encapsulation = 1;
	skb_shinfo(skb)->gso_type \|= SKB_GSO_IPXIP4;
	return ipv6_gro_complete(skb, nhoff);
	}

	static int ip6ip6_gro_complete(struct sk_buff *skb, int nhoff)
	{
	skb->encapsulation = 1;
	skb_shinfo(skb)->gso_type \|= SKB_GSO_IPXIP6;
	return ipv6_gro_complete(skb, nhoff);
	}

	static int ip4ip6_gro_complete(struct sk_buff *skb, int nhoff)
	{
	skb->encapsulation = 1;
	skb_shinfo(skb)->gso_type \|= SKB_GSO_IPXIP6;
	return inet_gro_complete(skb, nhoff);
	}

	static struct packet_offload ipv6_packet_offload __read_mostly = {
	.type = cpu_to_be16(ETH_P_IPV6),
	.callbacks = {
	.gso_segment = ipv6_gso_segment,
	.gro_receive = ipv6_gro_receive,
	.gro_complete = ipv6_gro_complete,
	},
	};

	static struct sk_buff sit_gso_segment(struct sk_buff skb,
	netdev_features_t features)
	{
	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP4))
	return ERR_PTR(-EINVAL);

	return ipv6_gso_segment(skb, features);
	}

	static struct sk_buff ip4ip6_gso_segment(struct sk_buff skb,
	netdev_features_t features)
	{
	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP6))
	return ERR_PTR(-EINVAL);

	return inet_gso_segment(skb, features);
	}

	static struct sk_buff ip6ip6_gso_segment(struct sk_buff skb,
	netdev_features_t features)
	{
	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP6))
	return ERR_PTR(-EINVAL);

	return ipv6_gso_segment(skb, features);
	}

	static const struct net_offload sit_offload = {
	.callbacks = {
	.gso_segment = sit_gso_segment,
	.gro_receive = sit_ip6ip6_gro_receive,
	.gro_complete = sit_gro_complete,
	},
	};

	static const struct net_offload ip4ip6_offload = {
	.callbacks = {
	.gso_segment = ip4ip6_gso_segment,
	.gro_receive = ip4ip6_gro_receive,
	.gro_complete = ip4ip6_gro_complete,
	},
	};

	static const struct net_offload ip6ip6_offload = {
	.callbacks = {
	.gso_segment = ip6ip6_gso_segment,
	.gro_receive = sit_ip6ip6_gro_receive,
	.gro_complete = ip6ip6_gro_complete,
	},
	};
	static int __init ipv6_offload_init(void)
	{

	if (tcpv6_offload_init() < 0)
	pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
	if (ipv6_exthdrs_offload_init() < 0)
	pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);

	dev_add_offload(&ipv6_packet_offload);

	inet_add_offload(&sit_offload, IPPROTO_IPV6);
	inet6_add_offload(&ip6ip6_offload, IPPROTO_IPV6);
	inet6_add_offload(&ip4ip6_offload, IPPROTO_IPIP);

	return 0;
	}

	fs_initcall(ipv6_offload_init);