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
  33         mss = skb_shinfo(skb)->gso_size;
  34         if (unlikely(skb->len <= mss))
  35                 goto out;
  36
  37         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  38                 /* Packet is from an untrusted source, reset gso_segs. */
  39                 int type = skb_shinfo(skb)->gso_type;
  40
  41                 if (unlikely(type & ~(SKB_GSO_UDP |
  42                                       SKB_GSO_DODGY |
  43                                       SKB_GSO_UDP_TUNNEL |
  44                                       SKB_GSO_UDP_TUNNEL_CSUM |
  45                                       SKB_GSO_TUNNEL_REMCSUM |
  46                                       SKB_GSO_GRE |
  47                                       SKB_GSO_GRE_CSUM |
  48                                       SKB_GSO_IPIP |
  49                                       SKB_GSO_SIT) ||
  50                              !(type & (SKB_GSO_UDP))))
  51                         goto out;
  52
  53                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  54
  55                 /* Set the IPv6 fragment id if not set yet */
  56                 if (!skb_shinfo(skb)->ip6_frag_id)
  57                         ipv6_proxy_select_ident(dev_net(skb->dev), skb);
  58
  59                 segs = NULL;
  60                 goto out;
  61         }
  62
  63         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  64             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  65                 segs = skb_udp_tunnel_segment(skb, features, true);
  66         else {
  67                 const struct ipv6hdr *ipv6h;
  68                 struct udphdr *uh;
  69
  70                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  71                         goto out;
  72
  73                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  74                  * do checksum of UDP packets sent as multiple IP fragments.
  75                  */
  76
  77                 uh = udp_hdr(skb);
  78                 ipv6h = ipv6_hdr(skb);
  79
  80                 uh->check = 0;
  81                 csum = skb_checksum(skb, 0, skb->len, 0);
  82                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  83                                           &ipv6h->daddr, csum);
  84                 if (uh->check == 0)
  85                         uh->check = CSUM_MANGLED_0;
  86
  87                 skb->ip_summed = CHECKSUM_NONE;
  88
  89                 /* If there is no outer header we can fake a checksum offload
  90                  * due to the fact that we have already done the checksum in
  91                  * software prior to segmenting the frame.
  92                  */
  93                 if (!skb->encap_hdr_csum)
  94                         features |= NETIF_F_HW_CSUM;
  95
  96                 /* Check if there is enough headroom to insert fragment header. */
  97                 tnl_hlen = skb_tnl_header_len(skb);
  98                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  99                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
 100                                 goto out;
 101                 }
 102
 103                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
 104                  * bytes to insert fragment header.
 105                  */
 106                 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 107                 nexthdr = *prevhdr;
 108                 *prevhdr = NEXTHDR_FRAGMENT;
 109                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
 110                              unfrag_ip6hlen + tnl_hlen;
 111                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
 112                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
 113
 114                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
 115                 skb->mac_header -= frag_hdr_sz;
 116                 skb->network_header -= frag_hdr_sz;
 117
 118                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 119                 fptr->nexthdr = nexthdr;
 120                 fptr->reserved = 0;
 121                 if (!skb_shinfo(skb)->ip6_frag_id)
 122                         ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 123                 fptr->identification = skb_shinfo(skb)->ip6_frag_id;
 124
 125                 /* Fragment the skb. ipv6 header and the remaining fields of the
 126                  * fragment header are updated in ipv6_gso_segment()
 127                  */
 128                 segs = skb_segment(skb, features);
 129         }
 130
 131 out:
 132         return segs;
 133 }
 134
 135 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
 136                                          struct sk_buff *skb)
 137 {
 138         struct udphdr *uh = udp_gro_udphdr(skb);
 139
 140         if (unlikely(!uh))
 141                 goto flush;
 142
 143         /* Don't bother verifying checksum if we're going to flush anyway. */
 144         if (NAPI_GRO_CB(skb)->flush)
 145                 goto skip;
 146
 147         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 148                                                  ip6_gro_compute_pseudo))
 149                 goto flush;
 150         else if (uh->check)
 151                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 152                                              ip6_gro_compute_pseudo);
 153
 154 skip:
 155         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 156         return udp_gro_receive(head, skb, uh);
 157
 158 flush:
 159         NAPI_GRO_CB(skb)->flush = 1;
 160         return NULL;
 161 }
 162
 163 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 164 {
 165         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 166         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 167
 168         if (uh->check) {
 169                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 170                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 171                                           &ipv6h->daddr, 0);
 172         } else {
 173                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 174         }
 175
 176         return udp_gro_complete(skb, nhoff);
 177 }
 178
 179 static const struct net_offload udpv6_offload = {
 180         .callbacks = {
 181                 .gso_segment    =       udp6_ufo_fragment,
 182                 .gro_receive    =       udp6_gro_receive,
 183                 .gro_complete   =       udp6_gro_complete,
 184         },
 185 };
 186
 187 int __init udp_offload_init(void)
 188 {
 189         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 190 }