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                 int type = skb_shinfo(skb)->gso_type;
  41
  42                 if (unlikely(type & ~(SKB_GSO_UDP |
  43                                       SKB_GSO_DODGY |
  44                                       SKB_GSO_UDP_TUNNEL |
  45                                       SKB_GSO_UDP_TUNNEL_CSUM |
  46                                       SKB_GSO_TUNNEL_REMCSUM |
  47                                       SKB_GSO_GRE |
  48                                       SKB_GSO_GRE_CSUM |
  49                                       SKB_GSO_IPIP |
  50                                       SKB_GSO_SIT) ||
  51                              !(type & (SKB_GSO_UDP))))
  52                         goto out;
  53
  54                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  55
  56                 /* Set the IPv6 fragment id if not set yet */
  57                 if (!skb_shinfo(skb)->ip6_frag_id)
  58                         ipv6_proxy_select_ident(dev_net(skb->dev), skb);
  59
  60                 segs = NULL;
  61                 goto out;
  62         }
  63
  64         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  65             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  66                 segs = skb_udp_tunnel_segment(skb, features, true);
  67         else {
  68                 const struct ipv6hdr *ipv6h;
  69                 struct udphdr *uh;
  70
  71                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  72                         goto out;
  73
  74                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  75                  * do checksum of UDP packets sent as multiple IP fragments.
  76                  */
  77
  78                 uh = udp_hdr(skb);
  79                 ipv6h = ipv6_hdr(skb);
  80
  81                 uh->check = 0;
  82                 csum = skb_checksum(skb, 0, skb->len, 0);
  83                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  84                                           &ipv6h->daddr, csum);
  85
  86                 if (uh->check == 0)
  87                         uh->check = CSUM_MANGLED_0;
  88
  89                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  90
  91                 /* Check if there is enough headroom to insert fragment header. */
  92                 tnl_hlen = skb_tnl_header_len(skb);
  93                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  94                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  95                                 goto out;
  96                 }
  97
  98                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  99                  * bytes to insert fragment header.
 100                  */
 101                 err = ip6_find_1stfragopt(skb, &prevhdr);
 102                 if (err < 0)
 103                         return ERR_PTR(err);
 104                 unfrag_ip6hlen = err;
 105                 nexthdr = *prevhdr;
 106                 *prevhdr = NEXTHDR_FRAGMENT;
 107                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
 108                              unfrag_ip6hlen + tnl_hlen;
 109                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
 110                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
 111
 112                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
 113                 skb->mac_header -= frag_hdr_sz;
 114                 skb->network_header -= frag_hdr_sz;
 115
 116                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 117                 fptr->nexthdr = nexthdr;
 118                 fptr->reserved = 0;
 119                 if (!skb_shinfo(skb)->ip6_frag_id)
 120                         ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 121                 fptr->identification = skb_shinfo(skb)->ip6_frag_id;
 122
 123                 /* Fragment the skb. ipv6 header and the remaining fields of the
 124                  * fragment header are updated in ipv6_gso_segment()
 125                  */
 126                 segs = skb_segment(skb, features);
 127         }
 128
 129 out:
 130         return segs;
 131 }
 132
 133 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
 134                                          struct sk_buff *skb)
 135 {
 136         struct udphdr *uh = udp_gro_udphdr(skb);
 137
 138         if (unlikely(!uh))
 139                 goto flush;
 140
 141         /* Don't bother verifying checksum if we're going to flush anyway. */
 142         if (NAPI_GRO_CB(skb)->flush)
 143                 goto skip;
 144
 145         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 146                                                  ip6_gro_compute_pseudo))
 147                 goto flush;
 148         else if (uh->check)
 149                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 150                                              ip6_gro_compute_pseudo);
 151
 152 skip:
 153         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 154         return udp_gro_receive(head, skb, uh);
 155
 156 flush:
 157         NAPI_GRO_CB(skb)->flush = 1;
 158         return NULL;
 159 }
 160
 161 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 162 {
 163         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 164         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 165
 166         if (uh->check) {
 167                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 168                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 169                                           &ipv6h->daddr, 0);
 170         } else {
 171                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 172         }
 173
 174         return udp_gro_complete(skb, nhoff);
 175 }
 176
 177 static const struct net_offload udpv6_offload = {
 178         .callbacks = {
 179                 .gso_segment    =       udp6_ufo_fragment,
 180                 .gro_receive    =       udp6_gro_receive,
 181                 .gro_complete   =       udp6_gro_complete,
 182         },
 183 };
 184
 185 int __init udp_offload_init(void)
 186 {
 187         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 188 }