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 (tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_NEIGH ||
 368             tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM) {
 369                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 370                 if (!dst_check(&rt->dst, 0)) {
 371                         flow_offload_teardown(flow);
 372                         return NF_ACCEPT;
 373                 }
 374         }
 375
 376         if (skb_try_make_writable(skb, thoff + hdrsize))
 377                 return NF_DROP;
 378
 379         flow_offload_refresh(flow_table, flow);
 380
 381         nf_flow_encap_pop(skb, tuplehash);
 382         thoff -= offset;
 383
 384         iph = ip_hdr(skb);
 385         nf_flow_nat_ip(flow, skb, thoff, dir, iph);
 386
 387         ip_decrease_ttl(iph);
 388         skb->tstamp = 0;
 389
 390         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 391                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 392
 393         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 394                 memset(skb->cb, 0, sizeof(struct inet_skb_parm));
 395                 IPCB(skb)->iif = skb->dev->ifindex;
 396                 IPCB(skb)->flags = IPSKB_FORWARDED;
 397                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 398         }
 399
 400         switch (tuplehash->tuple.xmit_type) {
 401         case FLOW_OFFLOAD_XMIT_NEIGH:
 402                 outdev = rt->dst.dev;
 403                 skb->dev = outdev;
 404                 nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
 405                 skb_dst_set_noref(skb, &rt->dst);
 406                 neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
 407                 ret = NF_STOLEN;
 408                 break;
 409         case FLOW_OFFLOAD_XMIT_DIRECT:
 410                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IP);
 411                 if (ret == NF_DROP)
 412                         flow_offload_teardown(flow);
 413                 break;
 414         }
 415
 416         return ret;
 417 }
 418 EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
 419
 420 static void nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
 421                                  struct in6_addr *addr,
 422                                  struct in6_addr *new_addr,
 423                                  struct ipv6hdr *ip6h)
 424 {
 425         struct tcphdr *tcph;
 426
 427         tcph = (void *)(skb_network_header(skb) + thoff);
 428         inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
 429                                   new_addr->s6_addr32, true);
 430 }
 431
 432 static void nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
 433                                  struct in6_addr *addr,
 434                                  struct in6_addr *new_addr)
 435 {
 436         struct udphdr *udph;
 437
 438         udph = (void *)(skb_network_header(skb) + thoff);
 439         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 440                 inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
 441                                           new_addr->s6_addr32, true);
 442                 if (!udph->check)
 443                         udph->check = CSUM_MANGLED_0;
 444         }
 445 }
 446
 447 static void nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
 448                                      unsigned int thoff, struct in6_addr *addr,
 449                                      struct in6_addr *new_addr)
 450 {
 451         switch (ip6h->nexthdr) {
 452         case IPPROTO_TCP:
 453                 nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr, ip6h);
 454                 break;
 455         case IPPROTO_UDP:
 456                 nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr);
 457                 break;
 458         }
 459 }
 460
 461 static void nf_flow_snat_ipv6(const struct flow_offload *flow,
 462                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 463                               unsigned int thoff,
 464                               enum flow_offload_tuple_dir dir)
 465 {
 466         struct in6_addr addr, new_addr;
 467
 468         switch (dir) {
 469         case FLOW_OFFLOAD_DIR_ORIGINAL:
 470                 addr = ip6h->saddr;
 471                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
 472                 ip6h->saddr = new_addr;
 473                 break;
 474         case FLOW_OFFLOAD_DIR_REPLY:
 475                 addr = ip6h->daddr;
 476                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
 477                 ip6h->daddr = new_addr;
 478                 break;
 479         }
 480
 481         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 482 }
 483
 484 static void nf_flow_dnat_ipv6(const struct flow_offload *flow,
 485                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 486                               unsigned int thoff,
 487                               enum flow_offload_tuple_dir dir)
 488 {
 489         struct in6_addr addr, new_addr;
 490
 491         switch (dir) {
 492         case FLOW_OFFLOAD_DIR_ORIGINAL:
 493                 addr = ip6h->daddr;
 494                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
 495                 ip6h->daddr = new_addr;
 496                 break;
 497         case FLOW_OFFLOAD_DIR_REPLY:
 498                 addr = ip6h->saddr;
 499                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
 500                 ip6h->saddr = new_addr;
 501                 break;
 502         }
 503
 504         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 505 }
 506
 507 static void nf_flow_nat_ipv6(const struct flow_offload *flow,
 508                              struct sk_buff *skb,
 509                              enum flow_offload_tuple_dir dir,
 510                              struct ipv6hdr *ip6h)
 511 {
 512         unsigned int thoff = sizeof(*ip6h);
 513
 514         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 515                 nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 516                 nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir);
 517         }
 518         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 519                 nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 520                 nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir);
 521         }
 522 }
 523
 524 static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
 525                               struct flow_offload_tuple *tuple, u32 *hdrsize,
 526                               u32 offset)
 527 {
 528         struct flow_ports *ports;
 529         struct ipv6hdr *ip6h;
 530         unsigned int thoff;
 531
 532         thoff = sizeof(*ip6h) + offset;
 533         if (!pskb_may_pull(skb, thoff))
 534                 return -1;
 535
 536         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 537
 538         switch (ip6h->nexthdr) {
 539         case IPPROTO_TCP:
 540                 *hdrsize = sizeof(struct tcphdr);
 541                 break;
 542         case IPPROTO_UDP:
 543                 *hdrsize = sizeof(struct udphdr);
 544                 break;
 545         default:
 546                 return -1;
 547         }
 548
 549         if (ip6h->hop_limit <= 1)
 550                 return -1;
 551
 552         if (!pskb_may_pull(skb, thoff + *hdrsize))
 553                 return -1;
 554
 555         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 556         ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 557
 558         tuple->src_v6           = ip6h->saddr;
 559         tuple->dst_v6           = ip6h->daddr;
 560         tuple->src_port         = ports->source;
 561         tuple->dst_port         = ports->dest;
 562         tuple->l3proto          = AF_INET6;
 563         tuple->l4proto          = ip6h->nexthdr;
 564         tuple->iifidx           = dev->ifindex;
 565         nf_flow_tuple_encap(skb, tuple);
 566
 567         return 0;
 568 }
 569
 570 unsigned int
 571 nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 572                           const struct nf_hook_state *state)
 573 {
 574         struct flow_offload_tuple_rhash *tuplehash;
 575         struct nf_flowtable *flow_table = priv;
 576         struct flow_offload_tuple tuple = {};
 577         enum flow_offload_tuple_dir dir;
 578         const struct in6_addr *nexthop;
 579         struct flow_offload *flow;
 580         struct net_device *outdev;
 581         unsigned int thoff, mtu;
 582         u32 hdrsize, offset = 0;
 583         struct ipv6hdr *ip6h;
 584         struct rt6_info *rt;
 585         int ret;
 586
 587         if (skb->protocol != htons(ETH_P_IPV6) &&
 588             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IPV6), &offset))
 589                 return NF_ACCEPT;
 590
 591         if (nf_flow_tuple_ipv6(skb, state->in, &tuple, &hdrsize, offset) < 0)
 592                 return NF_ACCEPT;
 593
 594         tuplehash = flow_offload_lookup(flow_table, &tuple);
 595         if (tuplehash == NULL)
 596                 return NF_ACCEPT;
 597
 598         dir = tuplehash->tuple.dir;
 599         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 600
 601         mtu = flow->tuplehash[dir].tuple.mtu + offset;
 602         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 603                 return NF_ACCEPT;
 604
 605         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 606         thoff = sizeof(*ip6h) + offset;
 607         if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
 608                 return NF_ACCEPT;
 609
 610         if (tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_NEIGH ||
 611             tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM) {
 612                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 613                 if (!dst_check(&rt->dst, 0)) {
 614                         flow_offload_teardown(flow);
 615                         return NF_ACCEPT;
 616                 }
 617         }
 618
 619         if (skb_try_make_writable(skb, thoff + hdrsize))
 620                 return NF_DROP;
 621
 622         flow_offload_refresh(flow_table, flow);
 623
 624         nf_flow_encap_pop(skb, tuplehash);
 625
 626         ip6h = ipv6_hdr(skb);
 627         nf_flow_nat_ipv6(flow, skb, dir, ip6h);
 628
 629         ip6h->hop_limit--;
 630         skb->tstamp = 0;
 631
 632         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 633                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 634
 635         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 636                 memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 637                 IP6CB(skb)->iif = skb->dev->ifindex;
 638                 IP6CB(skb)->flags = IP6SKB_FORWARDED;
 639                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 640         }
 641
 642         switch (tuplehash->tuple.xmit_type) {
 643         case FLOW_OFFLOAD_XMIT_NEIGH:
 644                 outdev = rt->dst.dev;
 645                 skb->dev = outdev;
 646                 nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
 647                 skb_dst_set_noref(skb, &rt->dst);
 648                 neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
 649                 ret = NF_STOLEN;
 650                 break;
 651         case FLOW_OFFLOAD_XMIT_DIRECT:
 652                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IPV6);
 653                 if (ret == NF_DROP)
 654                         flow_offload_teardown(flow);
 655                 break;
 656         }
 657
 658         return ret;
 659 }
 660 EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);