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 int udp6_ufo_send_check(struct sk_buff *skb)
  21 {
  22         const struct ipv6hdr *ipv6h;
  23         struct udphdr *uh;
  24
  25         if (!pskb_may_pull(skb, sizeof(*uh)))
  26                 return -EINVAL;
  27
  28         if (likely(!skb->encapsulation)) {
  29                 ipv6h = ipv6_hdr(skb);
  30                 uh = udp_hdr(skb);
  31
  32                 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
  33                                              IPPROTO_UDP, 0);
  34                 skb->csum_start = skb_transport_header(skb) - skb->head;
  35                 skb->csum_offset = offsetof(struct udphdr, check);
  36                 skb->ip_summed = CHECKSUM_PARTIAL;
  37         }
  38
  39         return 0;
  40 }
  41
  42 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  43                                          netdev_features_t features)
  44 {
  45         struct sk_buff *segs = ERR_PTR(-EINVAL);
  46         unsigned int mss;
  47         unsigned int unfrag_ip6hlen, unfrag_len;
  48         struct frag_hdr *fptr;
  49         u8 *packet_start, *prevhdr;
  50         u8 nexthdr;
  51         u8 frag_hdr_sz = sizeof(struct frag_hdr);
  52         int offset;
  53         __wsum csum;
  54         int tnl_hlen;
  55
  56         mss = skb_shinfo(skb)->gso_size;
  57         if (unlikely(skb->len <= mss))
  58                 goto out;
  59
  60         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  61                 /* Packet is from an untrusted source, reset gso_segs. */
  62                 int type = skb_shinfo(skb)->gso_type;
  63
  64                 if (unlikely(type & ~(SKB_GSO_UDP |
  65                                       SKB_GSO_DODGY |
  66                                       SKB_GSO_UDP_TUNNEL |
  67                                       SKB_GSO_UDP_TUNNEL_CSUM |
  68                                       SKB_GSO_GRE |
  69                                       SKB_GSO_GRE_CSUM |
  70                                       SKB_GSO_IPIP |
  71                                       SKB_GSO_SIT |
  72                                       SKB_GSO_MPLS) ||
  73                              !(type & (SKB_GSO_UDP))))
  74                         goto out;
  75
  76                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  77
  78                 segs = NULL;
  79                 goto out;
  80         }
  81
  82         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  83             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  84                 segs = skb_udp_tunnel_segment(skb, features);
  85         else {
  86                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  87                  * do checksum of UDP packets sent as multiple IP fragments.
  88                  */
  89                 offset = skb_checksum_start_offset(skb);
  90                 csum = skb_checksum(skb, offset, skb->len - offset, 0);
  91                 offset += skb->csum_offset;
  92                 *(__sum16 *)(skb->data + offset) = csum_fold(csum);
  93                 skb->ip_summed = CHECKSUM_NONE;
  94
  95                 /* Check if there is enough headroom to insert fragment header. */
  96                 tnl_hlen = skb_tnl_header_len(skb);
  97                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  98                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  99                                 goto out;
 100                 }
 101
 102                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
 103                  * bytes to insert fragment header.
 104                  */
 105                 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 106                 nexthdr = *prevhdr;
 107                 *prevhdr = NEXTHDR_FRAGMENT;
 108                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
 109                              unfrag_ip6hlen + tnl_hlen;
 110                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
 111                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
 112
 113                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
 114                 skb->mac_header -= frag_hdr_sz;
 115                 skb->network_header -= frag_hdr_sz;
 116
 117                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 118                 fptr->nexthdr = nexthdr;
 119                 fptr->reserved = 0;
 120                 fptr->identification = skb_shinfo(skb)->ip6_frag_id;
 121
 122                 /* Fragment the skb. ipv6 header and the remaining fields of the
 123                  * fragment header are updated in ipv6_gso_segment()
 124                  */
 125                 segs = skb_segment(skb, features);
 126         }
 127
 128 out:
 129         return segs;
 130 }
 131
 132 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
 133                                          struct sk_buff *skb)
 134 {
 135         struct udphdr *uh = udp_gro_udphdr(skb);
 136
 137         if (unlikely(!uh))
 138                 goto flush;
 139
 140         /* Don't bother verifying checksum if we're going to flush anyway. */
 141         if (NAPI_GRO_CB(skb)->flush)
 142                 goto skip;
 143
 144         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 145                                                  ip6_gro_compute_pseudo))
 146                 goto flush;
 147         else if (uh->check)
 148                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 149                                              ip6_gro_compute_pseudo);
 150
 151 skip:
 152         return udp_gro_receive(head, skb, uh);
 153
 154 flush:
 155         NAPI_GRO_CB(skb)->flush = 1;
 156         return NULL;
 157 }
 158
 159 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 160 {
 161         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 162         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 163
 164         if (uh->check)
 165                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 166                                           &ipv6h->daddr, 0);
 167
 168         return udp_gro_complete(skb, nhoff);
 169 }
 170
 171 static const struct net_offload udpv6_offload = {
 172         .callbacks = {
 173                 .gso_send_check =       udp6_ufo_send_check,
 174                 .gso_segment    =       udp6_ufo_fragment,
 175                 .gro_receive    =       udp6_gro_receive,
 176                 .gro_complete   =       udp6_gro_complete,
 177         },
 178 };
 179
 180 int __init udp_offload_init(void)
 181 {
 182         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 183 }