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                 opth = (void *)skb->data;
  50                 proto = opth->nexthdr;
  51                 __skb_pull(skb, len);
  52         }
  53
  54         return proto;
  55 }
  56
  57 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
  58         netdev_features_t features)
  59 {
  60         struct sk_buff *segs = ERR_PTR(-EINVAL);
  61         struct ipv6hdr *ipv6h;
  62         const struct net_offload *ops;
  63         int proto;
  64         struct frag_hdr *fptr;
  65         unsigned int unfrag_ip6hlen;
  66         u8 *prevhdr;
  67         int offset = 0;
  68         bool encap, udpfrag;
  69         int nhoff;
  70
  71         if (unlikely(skb_shinfo(skb)->gso_type &
  72                      ~(SKB_GSO_TCPV4 |
  73                        SKB_GSO_UDP |
  74                        SKB_GSO_DODGY |
  75                        SKB_GSO_TCP_ECN |
  76                        SKB_GSO_TCP_FIXEDID |
  77                        SKB_GSO_TCPV6 |
  78                        SKB_GSO_GRE |
  79                        SKB_GSO_GRE_CSUM |
  80                        SKB_GSO_IPIP |
  81                        SKB_GSO_SIT |
  82                        SKB_GSO_UDP_TUNNEL |
  83                        SKB_GSO_UDP_TUNNEL_CSUM |
  84                        SKB_GSO_TUNNEL_REMCSUM |
  85                        0)))
  86                 goto out;
  87
  88         skb_reset_network_header(skb);
  89         nhoff = skb_network_header(skb) - skb_mac_header(skb);
  90         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
  91                 goto out;
  92
  93         encap = SKB_GSO_CB(skb)->encap_level > 0;
  94         if (encap)
  95                 features &= skb->dev->hw_enc_features;
  96         SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
  97
  98         ipv6h = ipv6_hdr(skb);
  99         __skb_pull(skb, sizeof(*ipv6h));
 100         segs = ERR_PTR(-EPROTONOSUPPORT);
 101
 102         proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 103
 104         if (skb->encapsulation &&
 105             skb_shinfo(skb)->gso_type & (SKB_GSO_SIT|SKB_GSO_IPIP))
 106                 udpfrag = proto == IPPROTO_UDP && encap;
 107         else
 108                 udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
 109
 110         ops = rcu_dereference(inet6_offloads[proto]);
 111         if (likely(ops && ops->callbacks.gso_segment)) {
 112                 skb_reset_transport_header(skb);
 113                 segs = ops->callbacks.gso_segment(skb, features);
 114         }
 115
 116         if (IS_ERR(segs))
 117                 goto out;
 118
 119         for (skb = segs; skb; skb = skb->next) {
 120                 ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
 121                 ipv6h->payload_len = htons(skb->len - nhoff - sizeof(*ipv6h));
 122                 skb->network_header = (u8 *)ipv6h - skb->head;
 123
 124                 if (udpfrag) {
 125                         unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 126                         fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
 127                         fptr->frag_off = htons(offset);
 128                         if (skb->next)
 129                                 fptr->frag_off |= htons(IP6_MF);
 130                         offset += (ntohs(ipv6h->payload_len) -
 131                                    sizeof(struct frag_hdr));
 132                 }
 133                 if (encap)
 134                         skb_reset_inner_headers(skb);
 135         }
 136
 137 out:
 138         return segs;
 139 }
 140
 141 /* Return the total length of all the extension hdrs, following the same
 142  * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
 143  */
 144 static int ipv6_exthdrs_len(struct ipv6hdr *iph,
 145                             const struct net_offload **opps)
 146 {
 147         struct ipv6_opt_hdr *opth = (void *)iph;
 148         int len = 0, proto, optlen = sizeof(*iph);
 149
 150         proto = iph->nexthdr;
 151         for (;;) {
 152                 if (proto != NEXTHDR_HOP) {
 153                         *opps = rcu_dereference(inet6_offloads[proto]);
 154                         if (unlikely(!(*opps)))
 155                                 break;
 156                         if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
 157                                 break;
 158                 }
 159                 opth = (void *)opth + optlen;
 160                 optlen = ipv6_optlen(opth);
 161                 len += optlen;
 162                 proto = opth->nexthdr;
 163         }
 164         return len;
 165 }
 166
 167 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 168                                          struct sk_buff *skb)
 169 {
 170         const struct net_offload *ops;
 171         struct sk_buff **pp = NULL;
 172         struct sk_buff *p;
 173         struct ipv6hdr *iph;
 174         unsigned int nlen;
 175         unsigned int hlen;
 176         unsigned int off;
 177         u16 flush = 1;
 178         int proto;
 179
 180         off = skb_gro_offset(skb);
 181         hlen = off + sizeof(*iph);
 182         iph = skb_gro_header_fast(skb, off);
 183         if (skb_gro_header_hard(skb, hlen)) {
 184                 iph = skb_gro_header_slow(skb, hlen, off);
 185                 if (unlikely(!iph))
 186                         goto out;
 187         }
 188
 189         skb_set_network_header(skb, off);
 190         skb_gro_pull(skb, sizeof(*iph));
 191         skb_set_transport_header(skb, skb_gro_offset(skb));
 192
 193         flush += ntohs(iph->payload_len) != skb_gro_len(skb);
 194
 195         rcu_read_lock();
 196         proto = iph->nexthdr;
 197         ops = rcu_dereference(inet6_offloads[proto]);
 198         if (!ops || !ops->callbacks.gro_receive) {
 199                 __pskb_pull(skb, skb_gro_offset(skb));
 200                 proto = ipv6_gso_pull_exthdrs(skb, proto);
 201                 skb_gro_pull(skb, -skb_transport_offset(skb));
 202                 skb_reset_transport_header(skb);
 203                 __skb_push(skb, skb_gro_offset(skb));
 204
 205                 ops = rcu_dereference(inet6_offloads[proto]);
 206                 if (!ops || !ops->callbacks.gro_receive)
 207                         goto out_unlock;
 208
 209                 iph = ipv6_hdr(skb);
 210         }
 211
 212         NAPI_GRO_CB(skb)->proto = proto;
 213
 214         flush--;
 215         nlen = skb_network_header_len(skb);
 216
 217         for (p = *head; p; p = p->next) {
 218                 const struct ipv6hdr *iph2;
 219                 __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
 220
 221                 if (!NAPI_GRO_CB(p)->same_flow)
 222                         continue;
 223
 224                 iph2 = (struct ipv6hdr *)(p->data + off);
 225                 first_word = *(__be32 *)iph ^ *(__be32 *)iph2;
 226
 227                 /* All fields must match except length and Traffic Class.
 228                  * XXX skbs on the gro_list have all been parsed and pulled
 229                  * already so we don't need to compare nlen
 230                  * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
 231                  * memcmp() alone below is suffcient, right?
 232                  */
 233                  if ((first_word & htonl(0xF00FFFFF)) ||
 234                     memcmp(&iph->nexthdr, &iph2->nexthdr,
 235                            nlen - offsetof(struct ipv6hdr, nexthdr))) {
 236                         NAPI_GRO_CB(p)->same_flow = 0;
 237                         continue;
 238                 }
 239                 /* flush if Traffic Class fields are different */
 240                 NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
 241                 NAPI_GRO_CB(p)->flush |= flush;
 242
 243                 /* Clear flush_id, there's really no concept of ID in IPv6. */
 244                 NAPI_GRO_CB(p)->flush_id = 0;
 245         }
 246
 247         NAPI_GRO_CB(skb)->flush |= flush;
 248
 249         skb_gro_postpull_rcsum(skb, iph, nlen);
 250
 251         pp = ops->callbacks.gro_receive(head, skb);
 252
 253 out_unlock:
 254         rcu_read_unlock();
 255
 256 out:
 257         NAPI_GRO_CB(skb)->flush |= flush;
 258
 259         return pp;
 260 }
 261
 262 static struct sk_buff **sit_gro_receive(struct sk_buff **head,
 263                                         struct sk_buff *skb)
 264 {
 265         if (NAPI_GRO_CB(skb)->encap_mark) {
 266                 NAPI_GRO_CB(skb)->flush = 1;
 267                 return NULL;
 268         }
 269
 270         NAPI_GRO_CB(skb)->encap_mark = 1;
 271
 272         return ipv6_gro_receive(head, skb);
 273 }
 274
 275 static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 276 {
 277         const struct net_offload *ops;
 278         struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
 279         int err = -ENOSYS;
 280
 281         if (skb->encapsulation)
 282                 skb_set_inner_network_header(skb, nhoff);
 283
 284         iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
 285
 286         rcu_read_lock();
 287
 288         nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
 289         if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 290                 goto out_unlock;
 291
 292         err = ops->callbacks.gro_complete(skb, nhoff);
 293
 294 out_unlock:
 295         rcu_read_unlock();
 296
 297         return err;
 298 }
 299
 300 static int sit_gro_complete(struct sk_buff *skb, int nhoff)
 301 {
 302         skb->encapsulation = 1;
 303         skb_shinfo(skb)->gso_type |= SKB_GSO_SIT;
 304         return ipv6_gro_complete(skb, nhoff);
 305 }
 306
 307 static struct packet_offload ipv6_packet_offload __read_mostly = {
 308         .type = cpu_to_be16(ETH_P_IPV6),
 309         .callbacks = {
 310                 .gso_segment = ipv6_gso_segment,
 311                 .gro_receive = ipv6_gro_receive,
 312                 .gro_complete = ipv6_gro_complete,
 313         },
 314 };
 315
 316 static const struct net_offload sit_offload = {
 317         .callbacks = {
 318                 .gso_segment    = ipv6_gso_segment,
 319                 .gro_receive    = sit_gro_receive,
 320                 .gro_complete   = sit_gro_complete,
 321         },
 322 };
 323
 324 static int __init ipv6_offload_init(void)
 325 {
 326
 327         if (tcpv6_offload_init() < 0)
 328                 pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
 329         if (ipv6_exthdrs_offload_init() < 0)
 330                 pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
 331
 332         dev_add_offload(&ipv6_packet_offload);
 333
 334         inet_add_offload(&sit_offload, IPPROTO_IPV6);
 335
 336         return 0;
 337 }
 338
 339 fs_initcall(ipv6_offload_init);