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->encapsulation && skb_shinfo(skb)->gso_type &
  39             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  40                 segs = skb_udp_tunnel_segment(skb, features, true);
  41         else {
  42                 const struct ipv6hdr *ipv6h;
  43                 struct udphdr *uh;
  44
  45                 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
  46                         goto out;
  47
  48                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  49                         goto out;
  50
  51                 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
  52                         return __udp_gso_segment(skb, features);
  53
  54                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  55                  * do checksum of UDP packets sent as multiple IP fragments.
  56                  */
  57
  58                 uh = udp_hdr(skb);
  59                 ipv6h = ipv6_hdr(skb);
  60
  61                 uh->check = 0;
  62                 csum = skb_checksum(skb, 0, skb->len, 0);
  63                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  64                                           &ipv6h->daddr, csum);
  65                 if (uh->check == 0)
  66                         uh->check = CSUM_MANGLED_0;
  67
  68                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  69
  70                 /* If there is no outer header we can fake a checksum offload
  71                  * due to the fact that we have already done the checksum in
  72                  * software prior to segmenting the frame.
  73                  */
  74                 if (!skb->encap_hdr_csum)
  75                         features |= NETIF_F_HW_CSUM;
  76
  77                 /* Check if there is enough headroom to insert fragment header. */
  78                 tnl_hlen = skb_tnl_header_len(skb);
  79                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  80                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  81                                 goto out;
  82                 }
  83
  84                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  85                  * bytes to insert fragment header.
  86                  */
  87                 err = ip6_find_1stfragopt(skb, &prevhdr);
  88                 if (err < 0)
  89                         return ERR_PTR(err);
  90                 unfrag_ip6hlen = err;
  91                 nexthdr = *prevhdr;
  92                 *prevhdr = NEXTHDR_FRAGMENT;
  93                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  94                              unfrag_ip6hlen + tnl_hlen;
  95                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  96                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  97
  98                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
  99                 skb->mac_header -= frag_hdr_sz;
 100                 skb->network_header -= frag_hdr_sz;
 101
 102                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 103                 fptr->nexthdr = nexthdr;
 104                 fptr->reserved = 0;
 105                 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 106
 107                 /* Fragment the skb. ipv6 header and the remaining fields of the
 108                  * fragment header are updated in ipv6_gso_segment()
 109                  */
 110                 segs = skb_segment(skb, features);
 111         }
 112
 113 out:
 114         return segs;
 115 }
 116
 117 static struct sk_buff *udp6_gro_receive(struct list_head *head,
 118                                         struct sk_buff *skb)
 119 {
 120         struct udphdr *uh = udp_gro_udphdr(skb);
 121
 122         if (unlikely(!uh))
 123                 goto flush;
 124
 125         /* Don't bother verifying checksum if we're going to flush anyway. */
 126         if (NAPI_GRO_CB(skb)->flush)
 127                 goto skip;
 128
 129         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 130                                                  ip6_gro_compute_pseudo))
 131                 goto flush;
 132         else if (uh->check)
 133                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 134                                              ip6_gro_compute_pseudo);
 135
 136 skip:
 137         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 138         return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb);
 139
 140 flush:
 141         NAPI_GRO_CB(skb)->flush = 1;
 142         return NULL;
 143 }
 144
 145 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 146 {
 147         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 148         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 149
 150         if (uh->check) {
 151                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 152                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 153                                           &ipv6h->daddr, 0);
 154         } else {
 155                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 156         }
 157
 158         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 159 }
 160
 161 static const struct net_offload udpv6_offload = {
 162         .callbacks = {
 163                 .gso_segment    =       udp6_ufo_fragment,
 164                 .gro_receive    =       udp6_gro_receive,
 165                 .gro_complete   =       udp6_gro_complete,
 166         },
 167 };
 168
 169 int udpv6_offload_init(void)
 170 {
 171         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 172 }
 173
 174 int udpv6_offload_exit(void)
 175 {
 176         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 177 }