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