text: /*
   *	IPV6 GSO/GRO offload support
   *	Linux INET6 implementation
   *
   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   */
  
  #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 "ip6_offload.h"
  
  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;
  	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);
  	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;
  	else
  		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
  
  	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 (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)
  			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;
  
  		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;
  }
  
  static struct sk_buff **ipv6_gro_receive(struct sk_buff **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);
  
  	rcu_read_lock();
  	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_unlock;
  
  		iph = ipv6_hdr(skb);
  	}
  
  	NAPI_GRO_CB(skb)->proto = proto;
  
  	flush--;
  	nlen = skb_network_header_len(skb);
  
  	for (p = *head; p; p = p->next) {
  		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 suffcient, right?
  		 */
  		 if ((first_word & htonl(0xF00FFFFF)) ||
  		    memcmp(&iph->nexthdr, &iph2->nexthdr,
  			   nlen - offsetof(struct ipv6hdr, nexthdr))) {
  			NAPI_GRO_CB(p)->same_flow = 0;
  			continue;
  		}
  		/* flush if Traffic Class fields are different */
  		NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
  		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 = call_gro_receive(ops->callbacks.gro_receive, head, skb);
  
  out_unlock:
  	rcu_read_unlock();
  
  out:
  	skb_gro_flush_final(skb, pp, flush);
  
  	return pp;
  }
  
  static struct sk_buff **sit_ip6ip6_gro_receive(struct sk_buff **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 sk_buff **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);
  }
  
  static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
  {
  	const struct net_offload *ops;
  	struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
  	int err = -ENOSYS;
  
  	if (skb->encapsulation) {
  		skb_set_inner_protocol(skb, cpu_to_be16(ETH_P_IPV6));
  		skb_set_inner_network_header(skb, nhoff);
  	}
  
  	iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
  
  	rcu_read_lock();
  
  	nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
  	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
  		goto out_unlock;
  
  	err = ops->callbacks.gro_complete(skb, nhoff);
  
  out_unlock:
  	rcu_read_unlock();
  
  	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 const struct net_offload sit_offload = {
  	.callbacks = {
  		.gso_segment	= ipv6_gso_segment,
  		.gro_receive    = sit_ip6ip6_gro_receive,
  		.gro_complete   = sit_gro_complete,
  	},
  };
  
  static const struct net_offload ip4ip6_offload = {
  	.callbacks = {
  		.gso_segment	= inet_gso_segment,
  		.gro_receive    = ip4ip6_gro_receive,
  		.gro_complete   = ip4ip6_gro_complete,
  	},
  };
  
  static const struct net_offload ip6ip6_offload = {
  	.callbacks = {
  		.gso_segment	= ipv6_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);
  