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