net/ipv6/ip6_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
  11 #include <linux/kernel.h>
  12 #include <linux/socket.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/printk.h>
  16
  17 #include <net/protocol.h>
  18 #include <net/ipv6.h>
  19
  20 #include "ip6_offload.h"
  21
  22 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
  23 {
  24         const struct net_offload *ops = NULL;
  25
  26         for (;;) {
  27                 struct ipv6_opt_hdr *opth;
  28                 int len;
  29
  30                 if (proto != NEXTHDR_HOP) {
  31                         ops = rcu_dereference(inet6_offloads[proto]);
  32
  33                         if (unlikely(!ops))
  34                                 break;
  35
  36                         if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
  37                                 break;
  38                 }
  39
  40                 if (unlikely(!pskb_may_pull(skb, 8)))
  41                         break;
  42
  43                 opth = (void *)skb->data;
  44                 len = ipv6_optlen(opth);
  45
  46                 if (unlikely(!pskb_may_pull(skb, len)))
  47                         break;
  48
  49                 proto = opth->nexthdr;
  50                 __skb_pull(skb, len);
  51         }
  52
  53         return proto;
  54 }
  55
  56 static int ipv6_gso_send_check(struct sk_buff *skb)
  57 {
  58         const struct ipv6hdr *ipv6h;
  59         const struct net_offload *ops;
  60         int err = -EINVAL;
  61
  62         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
  63                 goto out;
  64
  65         ipv6h = ipv6_hdr(skb);
  66         __skb_pull(skb, sizeof(*ipv6h));
  67         err = -EPROTONOSUPPORT;
  68
  69         ops = rcu_dereference(inet6_offloads[
  70                 ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr)]);
  71
  72         if (likely(ops && ops->callbacks.gso_send_check)) {
  73                 skb_reset_transport_header(skb);
  74                 err = ops->callbacks.gso_send_check(skb);
  75         }
  76
  77 out:
  78         return err;
  79 }
  80
  81 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
  82         netdev_features_t features)
  83 {
  84         struct sk_buff *segs = ERR_PTR(-EINVAL);
  85         struct ipv6hdr *ipv6h;
  86         const struct net_offload *ops;
  87         int proto;
  88         struct frag_hdr *fptr;
  89         unsigned int unfrag_ip6hlen;
  90         u8 *prevhdr;
  91         int offset = 0;
  92         bool tunnel;
  93         int nhoff;
  94
  95         if (unlikely(skb_shinfo(skb)->gso_type &
  96                      ~(SKB_GSO_UDP |
  97                        SKB_GSO_DODGY |
  98                        SKB_GSO_TCP_ECN |
  99                        SKB_GSO_GRE |
 100                        SKB_GSO_IPIP |
 101                        SKB_GSO_UDP_TUNNEL |
 102                        SKB_GSO_MPLS |
 103                        SKB_GSO_TCPV6 |
 104                        0)))
 105                 goto out;
 106
 107         skb_reset_network_header(skb);
 108         nhoff = skb_network_header(skb) - skb_mac_header(skb);
 109         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 110                 goto out;
 111
 112         tunnel = SKB_GSO_CB(skb)->encap_level > 0;
 113         if (tunnel)
 114                 features = skb->dev->hw_enc_features & netif_skb_features(skb);
 115         SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
 116
 117         ipv6h = ipv6_hdr(skb);
 118         __skb_pull(skb, sizeof(*ipv6h));
 119         segs = ERR_PTR(-EPROTONOSUPPORT);
 120
 121         proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 122
 123         ops = rcu_dereference(inet6_offloads[proto]);
 124         if (likely(ops && ops->callbacks.gso_segment)) {
 125                 skb_reset_transport_header(skb);
 126                 segs = ops->callbacks.gso_segment(skb, features);
 127         }
 128
 129         if (IS_ERR(segs))
 130                 goto out;
 131
 132         for (skb = segs; skb; skb = skb->next) {
 133                 ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
 134                 ipv6h->payload_len = htons(skb->len - nhoff - sizeof(*ipv6h));
 135                 if (tunnel) {
 136                         skb_reset_inner_headers(skb);
 137                         skb->encapsulation = 1;
 138                 }
 139                 skb->network_header = (u8 *)ipv6h - skb->head;
 140
 141                 if (!tunnel && proto == IPPROTO_UDP) {
 142                         unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 143                         fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
 144                         fptr->frag_off = htons(offset);
 145                         if (skb->next != NULL)
 146                                 fptr->frag_off |= htons(IP6_MF);
 147                         offset += (ntohs(ipv6h->payload_len) -
 148                                    sizeof(struct frag_hdr));
 149                 }
 150         }
 151
 152 out:
 153         return segs;
 154 }
 155
 156 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 157                                          struct sk_buff *skb)
 158 {
 159         const struct net_offload *ops;
 160         struct sk_buff **pp = NULL;
 161         struct sk_buff *p;
 162         struct ipv6hdr *iph;
 163         unsigned int nlen;
 164         unsigned int hlen;
 165         unsigned int off;
 166         int flush = 1;
 167         int proto;
 168         __wsum csum;
 169
 170         off = skb_gro_offset(skb);
 171         hlen = off + sizeof(*iph);
 172         iph = skb_gro_header_fast(skb, off);
 173         if (skb_gro_header_hard(skb, hlen)) {
 174                 iph = skb_gro_header_slow(skb, hlen, off);
 175                 if (unlikely(!iph))
 176                         goto out;
 177         }
 178
 179         skb_gro_pull(skb, sizeof(*iph));
 180         skb_set_transport_header(skb, skb_gro_offset(skb));
 181
 182         flush += ntohs(iph->payload_len) != skb_gro_len(skb);
 183
 184         rcu_read_lock();
 185         proto = iph->nexthdr;
 186         ops = rcu_dereference(inet6_offloads[proto]);
 187         if (!ops || !ops->callbacks.gro_receive) {
 188                 __pskb_pull(skb, skb_gro_offset(skb));
 189                 proto = ipv6_gso_pull_exthdrs(skb, proto);
 190                 skb_gro_pull(skb, -skb_transport_offset(skb));
 191                 skb_reset_transport_header(skb);
 192                 __skb_push(skb, skb_gro_offset(skb));
 193
 194                 ops = rcu_dereference(inet6_offloads[proto]);
 195                 if (!ops || !ops->callbacks.gro_receive)
 196                         goto out_unlock;
 197
 198                 iph = ipv6_hdr(skb);
 199         }
 200
 201         NAPI_GRO_CB(skb)->proto = proto;
 202
 203         flush--;
 204         nlen = skb_network_header_len(skb);
 205
 206         for (p = *head; p; p = p->next) {
 207                 const struct ipv6hdr *iph2;
 208                 __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
 209
 210                 if (!NAPI_GRO_CB(p)->same_flow)
 211                         continue;
 212
 213                 iph2 = ipv6_hdr(p);
 214                 first_word = *(__be32 *)iph ^ *(__be32 *)iph2 ;
 215
 216                 /* All fields must match except length and Traffic Class. */
 217                 if (nlen != skb_network_header_len(p) ||
 218                     (first_word & htonl(0xF00FFFFF)) ||
 219                     memcmp(&iph->nexthdr, &iph2->nexthdr,
 220                            nlen - offsetof(struct ipv6hdr, nexthdr))) {
 221                         NAPI_GRO_CB(p)->same_flow = 0;
 222                         continue;
 223                 }
 224                 /* flush if Traffic Class fields are different */
 225                 NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
 226                 NAPI_GRO_CB(p)->flush |= flush;
 227         }
 228
 229         NAPI_GRO_CB(skb)->flush |= flush;
 230
 231         csum = skb->csum;
 232         skb_postpull_rcsum(skb, iph, skb_network_header_len(skb));
 233
 234         pp = ops->callbacks.gro_receive(head, skb);
 235
 236         skb->csum = csum;
 237
 238 out_unlock:
 239         rcu_read_unlock();
 240
 241 out:
 242         NAPI_GRO_CB(skb)->flush |= flush;
 243
 244         return pp;
 245 }
 246
 247 static int ipv6_gro_complete(struct sk_buff *skb)
 248 {
 249         const struct net_offload *ops;
 250         struct ipv6hdr *iph = ipv6_hdr(skb);
 251         int err = -ENOSYS;
 252
 253         iph->payload_len = htons(skb->len - skb_network_offset(skb) -
 254                                  sizeof(*iph));
 255
 256         rcu_read_lock();
 257         ops = rcu_dereference(inet6_offloads[NAPI_GRO_CB(skb)->proto]);
 258         if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 259                 goto out_unlock;
 260
 261         err = ops->callbacks.gro_complete(skb);
 262
 263 out_unlock:
 264         rcu_read_unlock();
 265
 266         return err;
 267 }
 268
 269 static struct packet_offload ipv6_packet_offload __read_mostly = {
 270         .type = cpu_to_be16(ETH_P_IPV6),
 271         .callbacks = {
 272                 .gso_send_check = ipv6_gso_send_check,
 273                 .gso_segment = ipv6_gso_segment,
 274                 .gro_receive = ipv6_gro_receive,
 275                 .gro_complete = ipv6_gro_complete,
 276         },
 277 };
 278
 279 static int __init ipv6_offload_init(void)
 280 {
 281
 282         if (tcpv6_offload_init() < 0)
 283                 pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
 284         if (udp_offload_init() < 0)
 285                 pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
 286         if (ipv6_exthdrs_offload_init() < 0)
 287                 pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
 288
 289         dev_add_offload(&ipv6_packet_offload);
 290         return 0;
 291 }
 292
 293 fs_initcall(ipv6_offload_init);