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_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  39                 /* Packet is from an untrusted source, reset gso_segs. */
  40
  41                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  42
  43                 /* Set the IPv6 fragment id if not set yet */
  44                 if (!skb_shinfo(skb)->ip6_frag_id)
  45                         ipv6_proxy_select_ident(dev_net(skb->dev), skb);
  46
  47                 segs = NULL;
  48                 goto out;
  49         }
  50
  51         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  52             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  53                 segs = skb_udp_tunnel_segment(skb, features, true);
  54         else {
  55                 const struct ipv6hdr *ipv6h;
  56                 struct udphdr *uh;
  57
  58                 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
  59                         goto out;
  60
  61                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  62                         goto out;
  63
  64                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  65                  * do checksum of UDP packets sent as multiple IP fragments.
  66                  */
  67
  68                 uh = udp_hdr(skb);
  69                 ipv6h = ipv6_hdr(skb);
  70
  71                 uh->check = 0;
  72                 csum = skb_checksum(skb, 0, skb->len, 0);
  73                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  74                                           &ipv6h->daddr, csum);
  75                 if (uh->check == 0)
  76                         uh->check = CSUM_MANGLED_0;
  77
  78                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  79
  80                 /* If there is no outer header we can fake a checksum offload
  81                  * due to the fact that we have already done the checksum in
  82                  * software prior to segmenting the frame.
  83                  */
  84                 if (!skb->encap_hdr_csum)
  85                         features |= NETIF_F_HW_CSUM;
  86
  87                 /* Check if there is enough headroom to insert fragment header. */
  88                 tnl_hlen = skb_tnl_header_len(skb);
  89                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  90                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  91                                 goto out;
  92                 }
  93
  94                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  95                  * bytes to insert fragment header.
  96                  */
  97                 err = ip6_find_1stfragopt(skb, &prevhdr);
  98                 if (err < 0)
  99                         return ERR_PTR(err);
 100                 unfrag_ip6hlen = err;
 101                 nexthdr = *prevhdr;
 102                 *prevhdr = NEXTHDR_FRAGMENT;
 103                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
 104                              unfrag_ip6hlen + tnl_hlen;
 105                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
 106                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
 107
 108                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
 109                 skb->mac_header -= frag_hdr_sz;
 110                 skb->network_header -= frag_hdr_sz;
 111
 112                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 113                 fptr->nexthdr = nexthdr;
 114                 fptr->reserved = 0;
 115                 if (!skb_shinfo(skb)->ip6_frag_id)
 116                         ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 117                 fptr->identification = skb_shinfo(skb)->ip6_frag_id;
 118
 119                 /* Fragment the skb. ipv6 header and the remaining fields of the
 120                  * fragment header are updated in ipv6_gso_segment()
 121                  */
 122                 segs = skb_segment(skb, features);
 123         }
 124
 125 out:
 126         return segs;
 127 }
 128
 129 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
 130                                          struct sk_buff *skb)
 131 {
 132         struct udphdr *uh = udp_gro_udphdr(skb);
 133
 134         if (unlikely(!uh))
 135                 goto flush;
 136
 137         /* Don't bother verifying checksum if we're going to flush anyway. */
 138         if (NAPI_GRO_CB(skb)->flush)
 139                 goto skip;
 140
 141         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 142                                                  ip6_gro_compute_pseudo))
 143                 goto flush;
 144         else if (uh->check)
 145                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 146                                              ip6_gro_compute_pseudo);
 147
 148 skip:
 149         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 150         return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb);
 151
 152 flush:
 153         NAPI_GRO_CB(skb)->flush = 1;
 154         return NULL;
 155 }
 156
 157 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 158 {
 159         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 160         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 161
 162         if (uh->check) {
 163                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 164                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 165                                           &ipv6h->daddr, 0);
 166         } else {
 167                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 168         }
 169
 170         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 171 }
 172
 173 static const struct net_offload udpv6_offload = {
 174         .callbacks = {
 175                 .gso_segment    =       udp6_ufo_fragment,
 176                 .gro_receive    =       udp6_gro_receive,
 177                 .gro_complete   =       udp6_gro_complete,
 178         },
 179 };
 180
 181 int udpv6_offload_init(void)
 182 {
 183         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 184 }
 185
 186 int udpv6_offload_exit(void)
 187 {
 188         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 189 }