net/ipv6/tcpv6_offload.c

   1 /*
   2  *      IPV6 GSO/GRO offload support
   3  *      Linux INET6 implementation
   4  *
   5  *      This program is free software; you can redistribute it and/or
   6  *      modify it under the terms of the GNU General Public License
   7  *      as published by the Free Software Foundation; either version
   8  *      2 of the License, or (at your option) any later version.
   9  *
  10  *      TCPv6 GSO/GRO support
  11  */
  12 #include <linux/skbuff.h>
  13 #include <net/protocol.h>
  14 #include <net/tcp.h>
  15 #include <net/ip6_checksum.h>
  16 #include "ip6_offload.h"
  17
  18 static int tcp_v6_gso_send_check(struct sk_buff *skb)
  19 {
  20         const struct ipv6hdr *ipv6h;
  21         struct tcphdr *th;
  22
  23         if (!pskb_may_pull(skb, sizeof(*th)))
  24                 return -EINVAL;
  25
  26         ipv6h = ipv6_hdr(skb);
  27         th = tcp_hdr(skb);
  28
  29         th->check = 0;
  30         skb->ip_summed = CHECKSUM_PARTIAL;
  31         __tcp_v6_send_check(skb, &ipv6h->saddr, &ipv6h->daddr);
  32         return 0;
  33 }
  34
  35 static struct sk_buff **tcp6_gro_receive(struct sk_buff **head,
  36                                          struct sk_buff *skb)
  37 {
  38         const struct ipv6hdr *iph = skb_gro_network_header(skb);
  39         __wsum wsum;
  40
  41         /* Don't bother verifying checksum if we're going to flush anyway. */
  42         if (NAPI_GRO_CB(skb)->flush)
  43                 goto skip_csum;
  44
  45         wsum = skb->csum;
  46
  47         switch (skb->ip_summed) {
  48         case CHECKSUM_NONE:
  49                 wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb),
  50                                     wsum);
  51
  52                 /* fall through */
  53
  54         case CHECKSUM_COMPLETE:
  55                 if (!tcp_v6_check(skb_gro_len(skb), &iph->saddr, &iph->daddr,
  56                                   wsum)) {
  57                         skb->ip_summed = CHECKSUM_UNNECESSARY;
  58                         break;
  59                 }
  60
  61                 NAPI_GRO_CB(skb)->flush = 1;
  62                 return NULL;
  63         }
  64
  65 skip_csum:
  66         return tcp_gro_receive(head, skb);
  67 }
  68
  69 static int tcp6_gro_complete(struct sk_buff *skb, int thoff)
  70 {
  71         const struct ipv6hdr *iph = ipv6_hdr(skb);
  72         struct tcphdr *th = tcp_hdr(skb);
  73
  74         th->check = ~tcp_v6_check(skb->len - thoff, &iph->saddr,
  75                                   &iph->daddr, 0);
  76         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
  77
  78         return tcp_gro_complete(skb);
  79 }
  80
  81 static const struct net_offload tcpv6_offload = {
  82         .callbacks = {
  83                 .gso_send_check =       tcp_v6_gso_send_check,
  84                 .gso_segment    =       tcp_gso_segment,
  85                 .gro_receive    =       tcp6_gro_receive,
  86                 .gro_complete   =       tcp6_gro_complete,
  87         },
  88 };
  89
  90 int __init tcpv6_offload_init(void)
  91 {
  92         return inet6_add_offload(&tcpv6_offload, IPPROTO_TCP);
  93 }