net/netfilter/nf_flow_table_ip.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/init.h>
   4 #include <linux/module.h>
   5 #include <linux/netfilter.h>
   6 #include <linux/rhashtable.h>
   7 #include <linux/ip.h>
   8 #include <linux/ipv6.h>
   9 #include <linux/netdevice.h>
  10 #include <linux/if_ether.h>
  11 #include <linux/if_pppox.h>
  12 #include <linux/ppp_defs.h>
  13 #include <net/ip.h>
  14 #include <net/ipv6.h>
  15 #include <net/ip6_route.h>
  16 #include <net/neighbour.h>
  17 #include <net/netfilter/nf_flow_table.h>
  18 #include <net/netfilter/nf_conntrack_acct.h>
  19 /* For layer 4 checksum field offset. */
  20 #include <linux/tcp.h>
  21 #include <linux/udp.h>
  22
  23 static int nf_flow_state_check(struct flow_offload *flow, int proto,
  24                                struct sk_buff *skb, unsigned int thoff)
  25 {
  26         struct tcphdr *tcph;
  27
  28         if (proto != IPPROTO_TCP)
  29                 return 0;
  30
  31         tcph = (void *)(skb_network_header(skb) + thoff);
  32         if (unlikely(tcph->fin || tcph->rst)) {
  33                 flow_offload_teardown(flow);
  34                 return -1;
  35         }
  36
  37         return 0;
  38 }
  39
  40 static void nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
  41                                __be32 addr, __be32 new_addr)
  42 {
  43         struct tcphdr *tcph;
  44
  45         tcph = (void *)(skb_network_header(skb) + thoff);
  46         inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
  47 }
  48
  49 static void nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
  50                                __be32 addr, __be32 new_addr)
  51 {
  52         struct udphdr *udph;
  53
  54         udph = (void *)(skb_network_header(skb) + thoff);
  55         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
  56                 inet_proto_csum_replace4(&udph->check, skb, addr,
  57                                          new_addr, true);
  58                 if (!udph->check)
  59                         udph->check = CSUM_MANGLED_0;
  60         }
  61 }
  62
  63 static void nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
  64                                    unsigned int thoff, __be32 addr,
  65                                    __be32 new_addr)
  66 {
  67         switch (iph->protocol) {
  68         case IPPROTO_TCP:
  69                 nf_flow_nat_ip_tcp(skb, thoff, addr, new_addr);
  70                 break;
  71         case IPPROTO_UDP:
  72                 nf_flow_nat_ip_udp(skb, thoff, addr, new_addr);
  73                 break;
  74         }
  75 }
  76
  77 static void nf_flow_snat_ip(const struct flow_offload *flow,
  78                             struct sk_buff *skb, struct iphdr *iph,
  79                             unsigned int thoff, enum flow_offload_tuple_dir dir)
  80 {
  81         __be32 addr, new_addr;
  82
  83         switch (dir) {
  84         case FLOW_OFFLOAD_DIR_ORIGINAL:
  85                 addr = iph->saddr;
  86                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
  87                 iph->saddr = new_addr;
  88                 break;
  89         case FLOW_OFFLOAD_DIR_REPLY:
  90                 addr = iph->daddr;
  91                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
  92                 iph->daddr = new_addr;
  93                 break;
  94         }
  95         csum_replace4(&iph->check, addr, new_addr);
  96
  97         nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
  98 }
  99
 100 static void nf_flow_dnat_ip(const struct flow_offload *flow,
 101                             struct sk_buff *skb, struct iphdr *iph,
 102                             unsigned int thoff, enum flow_offload_tuple_dir dir)
 103 {
 104         __be32 addr, new_addr;
 105
 106         switch (dir) {
 107         case FLOW_OFFLOAD_DIR_ORIGINAL:
 108                 addr = iph->daddr;
 109                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
 110                 iph->daddr = new_addr;
 111                 break;
 112         case FLOW_OFFLOAD_DIR_REPLY:
 113                 addr = iph->saddr;
 114                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
 115                 iph->saddr = new_addr;
 116                 break;
 117         }
 118         csum_replace4(&iph->check, addr, new_addr);
 119
 120         nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
 121 }
 122
 123 static void nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
 124                           unsigned int thoff, enum flow_offload_tuple_dir dir,
 125                           struct iphdr *iph)
 126 {
 127         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 128                 nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir);
 129                 nf_flow_snat_ip(flow, skb, iph, thoff, dir);
 130         }
 131         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 132                 nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir);
 133                 nf_flow_dnat_ip(flow, skb, iph, thoff, dir);
 134         }
 135 }
 136
 137 static bool ip_has_options(unsigned int thoff)
 138 {
 139         return thoff != sizeof(struct iphdr);
 140 }
 141
 142 static void nf_flow_tuple_encap(struct sk_buff *skb,
 143                                 struct flow_offload_tuple *tuple)
 144 {
 145         struct vlan_ethhdr *veth;
 146         struct pppoe_hdr *phdr;
 147         int i = 0;
 148
 149         if (skb_vlan_tag_present(skb)) {
 150                 tuple->encap[i].id = skb_vlan_tag_get(skb);
 151                 tuple->encap[i].proto = skb->vlan_proto;
 152                 i++;
 153         }
 154         switch (skb->protocol) {
 155         case htons(ETH_P_8021Q):
 156                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 157                 tuple->encap[i].id = ntohs(veth->h_vlan_TCI);
 158                 tuple->encap[i].proto = skb->protocol;
 159                 break;
 160         case htons(ETH_P_PPP_SES):
 161                 phdr = (struct pppoe_hdr *)skb_mac_header(skb);
 162                 tuple->encap[i].id = ntohs(phdr->sid);
 163                 tuple->encap[i].proto = skb->protocol;
 164                 break;
 165         }
 166 }
 167
 168 static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev,
 169                             struct flow_offload_tuple *tuple, u32 *hdrsize,
 170                             u32 offset)
 171 {
 172         struct flow_ports *ports;
 173         unsigned int thoff;
 174         struct iphdr *iph;
 175
 176         if (!pskb_may_pull(skb, sizeof(*iph) + offset))
 177                 return -1;
 178
 179         iph = (struct iphdr *)(skb_network_header(skb) + offset);
 180         thoff = (iph->ihl * 4);
 181
 182         if (ip_is_fragment(iph) ||
 183             unlikely(ip_has_options(thoff)))
 184                 return -1;
 185
 186         thoff += offset;
 187
 188         switch (iph->protocol) {
 189         case IPPROTO_TCP:
 190                 *hdrsize = sizeof(struct tcphdr);
 191                 break;
 192         case IPPROTO_UDP:
 193                 *hdrsize = sizeof(struct udphdr);
 194                 break;
 195         default:
 196                 return -1;
 197         }
 198
 199         if (iph->ttl <= 1)
 200                 return -1;
 201
 202         if (!pskb_may_pull(skb, thoff + *hdrsize))
 203                 return -1;
 204
 205         iph = (struct iphdr *)(skb_network_header(skb) + offset);
 206         ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 207
 208         tuple->src_v4.s_addr    = iph->saddr;
 209         tuple->dst_v4.s_addr    = iph->daddr;
 210         tuple->src_port         = ports->source;
 211         tuple->dst_port         = ports->dest;
 212         tuple->l3proto          = AF_INET;
 213         tuple->l4proto          = iph->protocol;
 214         tuple->iifidx           = dev->ifindex;
 215         nf_flow_tuple_encap(skb, tuple);
 216
 217         return 0;
 218 }
 219
 220 /* Based on ip_exceeds_mtu(). */
 221 static bool nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
 222 {
 223         if (skb->len <= mtu)
 224                 return false;
 225
 226         if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
 227                 return false;
 228
 229         return true;
 230 }
 231
 232 static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
 233                                       const struct nf_hook_state *state,
 234                                       struct dst_entry *dst)
 235 {
 236         skb_orphan(skb);
 237         skb_dst_set_noref(skb, dst);
 238         dst_output(state->net, state->sk, skb);
 239         return NF_STOLEN;
 240 }
 241
 242 static inline __be16 nf_flow_pppoe_proto(const struct sk_buff *skb)
 243 {
 244         __be16 proto;
 245
 246         proto = *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
 247                              sizeof(struct pppoe_hdr)));
 248         switch (proto) {
 249         case htons(PPP_IP):
 250                 return htons(ETH_P_IP);
 251         case htons(PPP_IPV6):
 252                 return htons(ETH_P_IPV6);
 253         }
 254
 255         return 0;
 256 }
 257
 258 static bool nf_flow_skb_encap_protocol(const struct sk_buff *skb, __be16 proto,
 259                                        u32 *offset)
 260 {
 261         struct vlan_ethhdr *veth;
 262
 263         switch (skb->protocol) {
 264         case htons(ETH_P_8021Q):
 265                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 266                 if (veth->h_vlan_encapsulated_proto == proto) {
 267                         *offset += VLAN_HLEN;
 268                         return true;
 269                 }
 270                 break;
 271         case htons(ETH_P_PPP_SES):
 272                 if (nf_flow_pppoe_proto(skb) == proto) {
 273                         *offset += PPPOE_SES_HLEN;
 274                         return true;
 275                 }
 276                 break;
 277         }
 278
 279         return false;
 280 }
 281
 282 static void nf_flow_encap_pop(struct sk_buff *skb,
 283                               struct flow_offload_tuple_rhash *tuplehash)
 284 {
 285         struct vlan_hdr *vlan_hdr;
 286         int i;
 287
 288         for (i = 0; i < tuplehash->tuple.encap_num; i++) {
 289                 if (skb_vlan_tag_present(skb)) {
 290                         __vlan_hwaccel_clear_tag(skb);
 291                         continue;
 292                 }
 293                 switch (skb->protocol) {
 294                 case htons(ETH_P_8021Q):
 295                         vlan_hdr = (struct vlan_hdr *)skb->data;
 296                         __skb_pull(skb, VLAN_HLEN);
 297                         vlan_set_encap_proto(skb, vlan_hdr);
 298                         skb_reset_network_header(skb);
 299                         break;
 300                 case htons(ETH_P_PPP_SES):
 301                         skb->protocol = nf_flow_pppoe_proto(skb);
 302                         skb_pull(skb, PPPOE_SES_HLEN);
 303                         skb_reset_network_header(skb);
 304                         break;
 305                 }
 306         }
 307 }
 308
 309 static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,
 310                                        const struct flow_offload_tuple_rhash *tuplehash,
 311                                        unsigned short type)
 312 {
 313         struct net_device *outdev;
 314
 315         outdev = dev_get_by_index_rcu(net, tuplehash->tuple.out.ifidx);
 316         if (!outdev)
 317                 return NF_DROP;
 318
 319         skb->dev = outdev;
 320         dev_hard_header(skb, skb->dev, type, tuplehash->tuple.out.h_dest,
 321                         tuplehash->tuple.out.h_source, skb->len);
 322         dev_queue_xmit(skb);
 323
 324         return NF_STOLEN;
 325 }
 326
 327 unsigned int
 328 nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 329                         const struct nf_hook_state *state)
 330 {
 331         struct flow_offload_tuple_rhash *tuplehash;
 332         struct nf_flowtable *flow_table = priv;
 333         struct flow_offload_tuple tuple = {};
 334         enum flow_offload_tuple_dir dir;
 335         struct flow_offload *flow;
 336         struct net_device *outdev;
 337         u32 hdrsize, offset = 0;
 338         unsigned int thoff, mtu;
 339         struct rtable *rt;
 340         struct iphdr *iph;
 341         __be32 nexthop;
 342         int ret;
 343
 344         if (skb->protocol != htons(ETH_P_IP) &&
 345             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &offset))
 346                 return NF_ACCEPT;
 347
 348         if (nf_flow_tuple_ip(skb, state->in, &tuple, &hdrsize, offset) < 0)
 349                 return NF_ACCEPT;
 350
 351         tuplehash = flow_offload_lookup(flow_table, &tuple);
 352         if (tuplehash == NULL)
 353                 return NF_ACCEPT;
 354
 355         dir = tuplehash->tuple.dir;
 356         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 357
 358         mtu = flow->tuplehash[dir].tuple.mtu + offset;
 359         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 360                 return NF_ACCEPT;
 361
 362         iph = (struct iphdr *)(skb_network_header(skb) + offset);
 363         thoff = (iph->ihl * 4) + offset;
 364         if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
 365                 return NF_ACCEPT;
 366
 367         if (skb_try_make_writable(skb, thoff + hdrsize))
 368                 return NF_DROP;
 369
 370         flow_offload_refresh(flow_table, flow);
 371
 372         nf_flow_encap_pop(skb, tuplehash);
 373         thoff -= offset;
 374
 375         iph = ip_hdr(skb);
 376         nf_flow_nat_ip(flow, skb, thoff, dir, iph);
 377
 378         ip_decrease_ttl(iph);
 379         skb->tstamp = 0;
 380
 381         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 382                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 383
 384         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 385                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 386                 memset(skb->cb, 0, sizeof(struct inet_skb_parm));
 387                 IPCB(skb)->iif = skb->dev->ifindex;
 388                 IPCB(skb)->flags = IPSKB_FORWARDED;
 389                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 390         }
 391
 392         switch (tuplehash->tuple.xmit_type) {
 393         case FLOW_OFFLOAD_XMIT_NEIGH:
 394                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 395                 outdev = rt->dst.dev;
 396                 skb->dev = outdev;
 397                 nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
 398                 skb_dst_set_noref(skb, &rt->dst);
 399                 neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
 400                 ret = NF_STOLEN;
 401                 break;
 402         case FLOW_OFFLOAD_XMIT_DIRECT:
 403                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IP);
 404                 if (ret == NF_DROP)
 405                         flow_offload_teardown(flow);
 406                 break;
 407         }
 408
 409         return ret;
 410 }
 411 EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
 412
 413 static void nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
 414                                  struct in6_addr *addr,
 415                                  struct in6_addr *new_addr,
 416                                  struct ipv6hdr *ip6h)
 417 {
 418         struct tcphdr *tcph;
 419
 420         tcph = (void *)(skb_network_header(skb) + thoff);
 421         inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
 422                                   new_addr->s6_addr32, true);
 423 }
 424
 425 static void nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
 426                                  struct in6_addr *addr,
 427                                  struct in6_addr *new_addr)
 428 {
 429         struct udphdr *udph;
 430
 431         udph = (void *)(skb_network_header(skb) + thoff);
 432         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 433                 inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
 434                                           new_addr->s6_addr32, true);
 435                 if (!udph->check)
 436                         udph->check = CSUM_MANGLED_0;
 437         }
 438 }
 439
 440 static void nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
 441                                      unsigned int thoff, struct in6_addr *addr,
 442                                      struct in6_addr *new_addr)
 443 {
 444         switch (ip6h->nexthdr) {
 445         case IPPROTO_TCP:
 446                 nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr, ip6h);
 447                 break;
 448         case IPPROTO_UDP:
 449                 nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr);
 450                 break;
 451         }
 452 }
 453
 454 static void nf_flow_snat_ipv6(const struct flow_offload *flow,
 455                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 456                               unsigned int thoff,
 457                               enum flow_offload_tuple_dir dir)
 458 {
 459         struct in6_addr addr, new_addr;
 460
 461         switch (dir) {
 462         case FLOW_OFFLOAD_DIR_ORIGINAL:
 463                 addr = ip6h->saddr;
 464                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
 465                 ip6h->saddr = new_addr;
 466                 break;
 467         case FLOW_OFFLOAD_DIR_REPLY:
 468                 addr = ip6h->daddr;
 469                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
 470                 ip6h->daddr = new_addr;
 471                 break;
 472         }
 473
 474         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 475 }
 476
 477 static void nf_flow_dnat_ipv6(const struct flow_offload *flow,
 478                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 479                               unsigned int thoff,
 480                               enum flow_offload_tuple_dir dir)
 481 {
 482         struct in6_addr addr, new_addr;
 483
 484         switch (dir) {
 485         case FLOW_OFFLOAD_DIR_ORIGINAL:
 486                 addr = ip6h->daddr;
 487                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
 488                 ip6h->daddr = new_addr;
 489                 break;
 490         case FLOW_OFFLOAD_DIR_REPLY:
 491                 addr = ip6h->saddr;
 492                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
 493                 ip6h->saddr = new_addr;
 494                 break;
 495         }
 496
 497         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 498 }
 499
 500 static void nf_flow_nat_ipv6(const struct flow_offload *flow,
 501                              struct sk_buff *skb,
 502                              enum flow_offload_tuple_dir dir,
 503                              struct ipv6hdr *ip6h)
 504 {
 505         unsigned int thoff = sizeof(*ip6h);
 506
 507         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 508                 nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 509                 nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir);
 510         }
 511         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 512                 nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 513                 nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir);
 514         }
 515 }
 516
 517 static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
 518                               struct flow_offload_tuple *tuple, u32 *hdrsize,
 519                               u32 offset)
 520 {
 521         struct flow_ports *ports;
 522         struct ipv6hdr *ip6h;
 523         unsigned int thoff;
 524
 525         thoff = sizeof(*ip6h) + offset;
 526         if (!pskb_may_pull(skb, thoff))
 527                 return -1;
 528
 529         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 530
 531         switch (ip6h->nexthdr) {
 532         case IPPROTO_TCP:
 533                 *hdrsize = sizeof(struct tcphdr);
 534                 break;
 535         case IPPROTO_UDP:
 536                 *hdrsize = sizeof(struct udphdr);
 537                 break;
 538         default:
 539                 return -1;
 540         }
 541
 542         if (ip6h->hop_limit <= 1)
 543                 return -1;
 544
 545         if (!pskb_may_pull(skb, thoff + *hdrsize))
 546                 return -1;
 547
 548         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 549         ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 550
 551         tuple->src_v6           = ip6h->saddr;
 552         tuple->dst_v6           = ip6h->daddr;
 553         tuple->src_port         = ports->source;
 554         tuple->dst_port         = ports->dest;
 555         tuple->l3proto          = AF_INET6;
 556         tuple->l4proto          = ip6h->nexthdr;
 557         tuple->iifidx           = dev->ifindex;
 558         nf_flow_tuple_encap(skb, tuple);
 559
 560         return 0;
 561 }
 562
 563 unsigned int
 564 nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 565                           const struct nf_hook_state *state)
 566 {
 567         struct flow_offload_tuple_rhash *tuplehash;
 568         struct nf_flowtable *flow_table = priv;
 569         struct flow_offload_tuple tuple = {};
 570         enum flow_offload_tuple_dir dir;
 571         const struct in6_addr *nexthop;
 572         struct flow_offload *flow;
 573         struct net_device *outdev;
 574         unsigned int thoff, mtu;
 575         u32 hdrsize, offset = 0;
 576         struct ipv6hdr *ip6h;
 577         struct rt6_info *rt;
 578         int ret;
 579
 580         if (skb->protocol != htons(ETH_P_IPV6) &&
 581             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IPV6), &offset))
 582                 return NF_ACCEPT;
 583
 584         if (nf_flow_tuple_ipv6(skb, state->in, &tuple, &hdrsize, offset) < 0)
 585                 return NF_ACCEPT;
 586
 587         tuplehash = flow_offload_lookup(flow_table, &tuple);
 588         if (tuplehash == NULL)
 589                 return NF_ACCEPT;
 590
 591         dir = tuplehash->tuple.dir;
 592         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 593
 594         mtu = flow->tuplehash[dir].tuple.mtu + offset;
 595         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 596                 return NF_ACCEPT;
 597
 598         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 599         thoff = sizeof(*ip6h) + offset;
 600         if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
 601                 return NF_ACCEPT;
 602
 603         if (skb_try_make_writable(skb, thoff + hdrsize))
 604                 return NF_DROP;
 605
 606         flow_offload_refresh(flow_table, flow);
 607
 608         nf_flow_encap_pop(skb, tuplehash);
 609
 610         ip6h = ipv6_hdr(skb);
 611         nf_flow_nat_ipv6(flow, skb, dir, ip6h);
 612
 613         ip6h->hop_limit--;
 614         skb->tstamp = 0;
 615
 616         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 617                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 618
 619         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 620                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 621                 memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 622                 IP6CB(skb)->iif = skb->dev->ifindex;
 623                 IP6CB(skb)->flags = IP6SKB_FORWARDED;
 624                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 625         }
 626
 627         switch (tuplehash->tuple.xmit_type) {
 628         case FLOW_OFFLOAD_XMIT_NEIGH:
 629                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 630                 outdev = rt->dst.dev;
 631                 skb->dev = outdev;
 632                 nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
 633                 skb_dst_set_noref(skb, &rt->dst);
 634                 neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
 635                 ret = NF_STOLEN;
 636                 break;
 637         case FLOW_OFFLOAD_XMIT_DIRECT:
 638                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IPV6);
 639                 if (ret == NF_DROP)
 640                         flow_offload_teardown(flow);
 641                 break;
 642         }
 643
 644         return ret;
 645 }
 646 EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);