net/ipv6/udp_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  *      UDPv6 GSO support
  11  */
  12 #include <linux/skbuff.h>
  13 #include <linux/netdevice.h>
  14 #include <net/protocol.h>
  15 #include <net/ipv6.h>
  16 #include <net/udp.h>
  17 #include <net/ip6_checksum.h>
  18 #include "ip6_offload.h"
  19
  20 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  21                                          netdev_features_t features)
  22 {
  23         struct sk_buff *segs = ERR_PTR(-EINVAL);
  24         unsigned int mss;
  25         unsigned int unfrag_ip6hlen, unfrag_len;
  26         struct frag_hdr *fptr;
  27         u8 *packet_start, *prevhdr;
  28         u8 nexthdr;
  29         u8 frag_hdr_sz = sizeof(struct frag_hdr);
  30         __wsum csum;
  31         int tnl_hlen;
  32         int err;
  33
  34         mss = skb_shinfo(skb)->gso_size;
  35         if (unlikely(skb->len <= mss))
  36                 goto out;
  37
  38         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  39             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  40                 segs = skb_udp_tunnel_segment(skb, features, true);
  41         else {
  42                 const struct ipv6hdr *ipv6h;
  43                 struct udphdr *uh;
  44
  45                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  46                         goto out;
  47
  48                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  49                  * do checksum of UDP packets sent as multiple IP fragments.
  50                  */
  51
  52                 uh = udp_hdr(skb);
  53                 ipv6h = ipv6_hdr(skb);
  54
  55                 uh->check = 0;
  56                 csum = skb_checksum(skb, 0, skb->len, 0);
  57                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  58                                           &ipv6h->daddr, csum);
  59                 if (uh->check == 0)
  60                         uh->check = CSUM_MANGLED_0;
  61
  62                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  63
  64                 /* If there is no outer header we can fake a checksum offload
  65                  * due to the fact that we have already done the checksum in
  66                  * software prior to segmenting the frame.
  67                  */
  68                 if (!skb->encap_hdr_csum)
  69                         features |= NETIF_F_HW_CSUM;
  70
  71                 /* Check if there is enough headroom to insert fragment header. */
  72                 tnl_hlen = skb_tnl_header_len(skb);
  73                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  74                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  75                                 goto out;
  76                 }
  77
  78                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  79                  * bytes to insert fragment header.
  80                  */
  81                 err = ip6_find_1stfragopt(skb, &prevhdr);
  82                 if (err < 0)
  83                         return ERR_PTR(err);
  84                 unfrag_ip6hlen = err;
  85                 nexthdr = *prevhdr;
  86                 *prevhdr = NEXTHDR_FRAGMENT;
  87                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  88                              unfrag_ip6hlen + tnl_hlen;
  89                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  90                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  91
  92                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
  93                 skb->mac_header -= frag_hdr_sz;
  94                 skb->network_header -= frag_hdr_sz;
  95
  96                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
  97                 fptr->nexthdr = nexthdr;
  98                 fptr->reserved = 0;
  99                 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 100
 101                 /* Fragment the skb. ipv6 header and the remaining fields of the
 102                  * fragment header are updated in ipv6_gso_segment()
 103                  */
 104                 segs = skb_segment(skb, features);
 105         }
 106
 107 out:
 108         return segs;
 109 }
 110
 111 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
 112                                          struct sk_buff *skb)
 113 {
 114         struct udphdr *uh = udp_gro_udphdr(skb);
 115
 116         if (unlikely(!uh))
 117                 goto flush;
 118
 119         /* Don't bother verifying checksum if we're going to flush anyway. */
 120         if (NAPI_GRO_CB(skb)->flush)
 121                 goto skip;
 122
 123         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 124                                                  ip6_gro_compute_pseudo))
 125                 goto flush;
 126         else if (uh->check)
 127                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 128                                              ip6_gro_compute_pseudo);
 129
 130 skip:
 131         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 132         return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb);
 133
 134 flush:
 135         NAPI_GRO_CB(skb)->flush = 1;
 136         return NULL;
 137 }
 138
 139 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 140 {
 141         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 142         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 143
 144         if (uh->check) {
 145                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 146                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 147                                           &ipv6h->daddr, 0);
 148         } else {
 149                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 150         }
 151
 152         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 153 }
 154
 155 static const struct net_offload udpv6_offload = {
 156         .callbacks = {
 157                 .gso_segment    =       udp6_ufo_fragment,
 158                 .gro_receive    =       udp6_gro_receive,
 159                 .gro_complete   =       udp6_gro_complete,
 160         },
 161 };
 162
 163 int udpv6_offload_init(void)
 164 {
 165         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 166 }
 167
 168 int udpv6_offload_exit(void)
 169 {
 170         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 171 }