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