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 <net/ip.h>
  12 #include <net/ipv6.h>
  13 #include <net/ip6_route.h>
  14 #include <net/neighbour.h>
  15 #include <net/netfilter/nf_flow_table.h>
  16 #include <net/netfilter/nf_conntrack_acct.h>
  17 /* For layer 4 checksum field offset. */
  18 #include <linux/tcp.h>
  19 #include <linux/udp.h>
  20
  21 static int nf_flow_state_check(struct flow_offload *flow, int proto,
  22                                struct sk_buff *skb, unsigned int thoff)
  23 {
  24         struct tcphdr *tcph;
  25
  26         if (proto != IPPROTO_TCP)
  27                 return 0;
  28
  29         tcph = (void *)(skb_network_header(skb) + thoff);
  30         if (unlikely(tcph->fin || tcph->rst)) {
  31                 flow_offload_teardown(flow);
  32                 return -1;
  33         }
  34
  35         return 0;
  36 }
  37
  38 static void nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
  39                                __be32 addr, __be32 new_addr)
  40 {
  41         struct tcphdr *tcph;
  42
  43         tcph = (void *)(skb_network_header(skb) + thoff);
  44         inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
  45 }
  46
  47 static void nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
  48                                __be32 addr, __be32 new_addr)
  49 {
  50         struct udphdr *udph;
  51
  52         udph = (void *)(skb_network_header(skb) + thoff);
  53         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
  54                 inet_proto_csum_replace4(&udph->check, skb, addr,
  55                                          new_addr, true);
  56                 if (!udph->check)
  57                         udph->check = CSUM_MANGLED_0;
  58         }
  59 }
  60
  61 static void nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
  62                                    unsigned int thoff, __be32 addr,
  63                                    __be32 new_addr)
  64 {
  65         switch (iph->protocol) {
  66         case IPPROTO_TCP:
  67                 nf_flow_nat_ip_tcp(skb, thoff, addr, new_addr);
  68                 break;
  69         case IPPROTO_UDP:
  70                 nf_flow_nat_ip_udp(skb, thoff, addr, new_addr);
  71                 break;
  72         }
  73 }
  74
  75 static void nf_flow_snat_ip(const struct flow_offload *flow,
  76                             struct sk_buff *skb, struct iphdr *iph,
  77                             unsigned int thoff, enum flow_offload_tuple_dir dir)
  78 {
  79         __be32 addr, new_addr;
  80
  81         switch (dir) {
  82         case FLOW_OFFLOAD_DIR_ORIGINAL:
  83                 addr = iph->saddr;
  84                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
  85                 iph->saddr = new_addr;
  86                 break;
  87         case FLOW_OFFLOAD_DIR_REPLY:
  88                 addr = iph->daddr;
  89                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
  90                 iph->daddr = new_addr;
  91                 break;
  92         }
  93         csum_replace4(&iph->check, addr, new_addr);
  94
  95         nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
  96 }
  97
  98 static void nf_flow_dnat_ip(const struct flow_offload *flow,
  99                             struct sk_buff *skb, struct iphdr *iph,
 100                             unsigned int thoff, enum flow_offload_tuple_dir dir)
 101 {
 102         __be32 addr, new_addr;
 103
 104         switch (dir) {
 105         case FLOW_OFFLOAD_DIR_ORIGINAL:
 106                 addr = iph->daddr;
 107                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
 108                 iph->daddr = new_addr;
 109                 break;
 110         case FLOW_OFFLOAD_DIR_REPLY:
 111                 addr = iph->saddr;
 112                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
 113                 iph->saddr = new_addr;
 114                 break;
 115         }
 116         csum_replace4(&iph->check, addr, new_addr);
 117
 118         nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
 119 }
 120
 121 static void nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
 122                           unsigned int thoff, enum flow_offload_tuple_dir dir,
 123                           struct iphdr *iph)
 124 {
 125         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 126                 nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir);
 127                 nf_flow_snat_ip(flow, skb, iph, thoff, dir);
 128         }
 129         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 130                 nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir);
 131                 nf_flow_dnat_ip(flow, skb, iph, thoff, dir);
 132         }
 133 }
 134
 135 static bool ip_has_options(unsigned int thoff)
 136 {
 137         return thoff != sizeof(struct iphdr);
 138 }
 139
 140 static void nf_flow_tuple_encap(struct sk_buff *skb,
 141                                 struct flow_offload_tuple *tuple)
 142 {
 143         struct vlan_ethhdr *veth;
 144         struct pppoe_hdr *phdr;
 145         int i = 0;
 146
 147         if (skb_vlan_tag_present(skb)) {
 148                 tuple->encap[i].id = skb_vlan_tag_get(skb);
 149                 tuple->encap[i].proto = skb->vlan_proto;
 150                 i++;
 151         }
 152         switch (skb->protocol) {
 153         case htons(ETH_P_8021Q):
 154                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 155                 tuple->encap[i].id = ntohs(veth->h_vlan_TCI);
 156                 tuple->encap[i].proto = skb->protocol;
 157                 break;
 158         case htons(ETH_P_PPP_SES):
 159                 phdr = (struct pppoe_hdr *)skb_mac_header(skb);
 160                 tuple->encap[i].id = ntohs(phdr->sid);
 161                 tuple->encap[i].proto = skb->protocol;
 162                 break;
 163         }
 164 }
 165
 166 static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev,
 167                             struct flow_offload_tuple *tuple, u32 *hdrsize,
 168                             u32 offset)
 169 {
 170         struct flow_ports *ports;
 171         unsigned int thoff;
 172         struct iphdr *iph;
 173         u8 ipproto;
 174
 175         if (!pskb_may_pull(skb, sizeof(*iph) + offset))
 176                 return -1;
 177
 178         iph = (struct iphdr *)(skb_network_header(skb) + offset);
 179         thoff = (iph->ihl * 4);
 180
 181         if (ip_is_fragment(iph) ||
 182             unlikely(ip_has_options(thoff)))
 183                 return -1;
 184
 185         thoff += offset;
 186
 187         ipproto = iph->protocol;
 188         switch (ipproto) {
 189         case IPPROTO_TCP:
 190                 *hdrsize = sizeof(struct tcphdr);
 191                 break;
 192         case IPPROTO_UDP:
 193                 *hdrsize = sizeof(struct udphdr);
 194                 break;
 195 #ifdef CONFIG_NF_CT_PROTO_GRE
 196         case IPPROTO_GRE:
 197                 *hdrsize = sizeof(struct gre_base_hdr);
 198                 break;
 199 #endif
 200         default:
 201                 return -1;
 202         }
 203
 204         if (iph->ttl <= 1)
 205                 return -1;
 206
 207         if (!pskb_may_pull(skb, thoff + *hdrsize))
 208                 return -1;
 209
 210         switch (ipproto) {
 211         case IPPROTO_TCP:
 212         case IPPROTO_UDP:
 213                 ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 214                 tuple->src_port         = ports->source;
 215                 tuple->dst_port         = ports->dest;
 216                 break;
 217         case IPPROTO_GRE: {
 218                 struct gre_base_hdr *greh;
 219
 220                 greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
 221                 if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
 222                         return -1;
 223                 break;
 224         }
 225         }
 226
 227         iph = (struct iphdr *)(skb_network_header(skb) + offset);
 228
 229         tuple->src_v4.s_addr    = iph->saddr;
 230         tuple->dst_v4.s_addr    = iph->daddr;
 231         tuple->l3proto          = AF_INET;
 232         tuple->l4proto          = ipproto;
 233         tuple->iifidx           = dev->ifindex;
 234         nf_flow_tuple_encap(skb, tuple);
 235
 236         return 0;
 237 }
 238
 239 /* Based on ip_exceeds_mtu(). */
 240 static bool nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
 241 {
 242         if (skb->len <= mtu)
 243                 return false;
 244
 245         if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
 246                 return false;
 247
 248         return true;
 249 }
 250
 251 static inline bool nf_flow_dst_check(struct flow_offload_tuple *tuple)
 252 {
 253         if (tuple->xmit_type != FLOW_OFFLOAD_XMIT_NEIGH &&
 254             tuple->xmit_type != FLOW_OFFLOAD_XMIT_XFRM)
 255                 return true;
 256
 257         return dst_check(tuple->dst_cache, tuple->dst_cookie);
 258 }
 259
 260 static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
 261                                       const struct nf_hook_state *state,
 262                                       struct dst_entry *dst)
 263 {
 264         skb_orphan(skb);
 265         skb_dst_set_noref(skb, dst);
 266         dst_output(state->net, state->sk, skb);
 267         return NF_STOLEN;
 268 }
 269
 270 static bool nf_flow_skb_encap_protocol(const struct sk_buff *skb, __be16 proto,
 271                                        u32 *offset)
 272 {
 273         struct vlan_ethhdr *veth;
 274
 275         switch (skb->protocol) {
 276         case htons(ETH_P_8021Q):
 277                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 278                 if (veth->h_vlan_encapsulated_proto == proto) {
 279                         *offset += VLAN_HLEN;
 280                         return true;
 281                 }
 282                 break;
 283         case htons(ETH_P_PPP_SES):
 284                 if (nf_flow_pppoe_proto(skb) == proto) {
 285                         *offset += PPPOE_SES_HLEN;
 286                         return true;
 287                 }
 288                 break;
 289         }
 290
 291         return false;
 292 }
 293
 294 static void nf_flow_encap_pop(struct sk_buff *skb,
 295                               struct flow_offload_tuple_rhash *tuplehash)
 296 {
 297         struct vlan_hdr *vlan_hdr;
 298         int i;
 299
 300         for (i = 0; i < tuplehash->tuple.encap_num; i++) {
 301                 if (skb_vlan_tag_present(skb)) {
 302                         __vlan_hwaccel_clear_tag(skb);
 303                         continue;
 304                 }
 305                 switch (skb->protocol) {
 306                 case htons(ETH_P_8021Q):
 307                         vlan_hdr = (struct vlan_hdr *)skb->data;
 308                         __skb_pull(skb, VLAN_HLEN);
 309                         vlan_set_encap_proto(skb, vlan_hdr);
 310                         skb_reset_network_header(skb);
 311                         break;
 312                 case htons(ETH_P_PPP_SES):
 313                         skb->protocol = nf_flow_pppoe_proto(skb);
 314                         skb_pull(skb, PPPOE_SES_HLEN);
 315                         skb_reset_network_header(skb);
 316                         break;
 317                 }
 318         }
 319 }
 320
 321 static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,
 322                                        const struct flow_offload_tuple_rhash *tuplehash,
 323                                        unsigned short type)
 324 {
 325         struct net_device *outdev;
 326
 327         outdev = dev_get_by_index_rcu(net, tuplehash->tuple.out.ifidx);
 328         if (!outdev)
 329                 return NF_DROP;
 330
 331         skb->dev = outdev;
 332         dev_hard_header(skb, skb->dev, type, tuplehash->tuple.out.h_dest,
 333                         tuplehash->tuple.out.h_source, skb->len);
 334         dev_queue_xmit(skb);
 335
 336         return NF_STOLEN;
 337 }
 338
 339 unsigned int
 340 nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 341                         const struct nf_hook_state *state)
 342 {
 343         struct flow_offload_tuple_rhash *tuplehash;
 344         struct nf_flowtable *flow_table = priv;
 345         struct flow_offload_tuple tuple = {};
 346         enum flow_offload_tuple_dir dir;
 347         struct flow_offload *flow;
 348         struct net_device *outdev;
 349         u32 hdrsize, offset = 0;
 350         unsigned int thoff, mtu;
 351         struct rtable *rt;
 352         struct iphdr *iph;
 353         __be32 nexthop;
 354         int ret;
 355
 356         if (skb->protocol != htons(ETH_P_IP) &&
 357             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &offset))
 358                 return NF_ACCEPT;
 359
 360         if (nf_flow_tuple_ip(skb, state->in, &tuple, &hdrsize, offset) < 0)
 361                 return NF_ACCEPT;
 362
 363         tuplehash = flow_offload_lookup(flow_table, &tuple);
 364         if (tuplehash == NULL)
 365                 return NF_ACCEPT;
 366
 367         dir = tuplehash->tuple.dir;
 368         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 369
 370         mtu = flow->tuplehash[dir].tuple.mtu + offset;
 371         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 372                 return NF_ACCEPT;
 373
 374         iph = (struct iphdr *)(skb_network_header(skb) + offset);
 375         thoff = (iph->ihl * 4) + offset;
 376         if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
 377                 return NF_ACCEPT;
 378
 379         if (!nf_flow_dst_check(&tuplehash->tuple)) {
 380                 flow_offload_teardown(flow);
 381                 return NF_ACCEPT;
 382         }
 383
 384         if (skb_try_make_writable(skb, thoff + hdrsize))
 385                 return NF_DROP;
 386
 387         flow_offload_refresh(flow_table, flow);
 388
 389         nf_flow_encap_pop(skb, tuplehash);
 390         thoff -= offset;
 391
 392         iph = ip_hdr(skb);
 393         nf_flow_nat_ip(flow, skb, thoff, dir, iph);
 394
 395         ip_decrease_ttl(iph);
 396         skb_clear_tstamp(skb);
 397
 398         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 399                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 400
 401         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 402                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 403                 memset(skb->cb, 0, sizeof(struct inet_skb_parm));
 404                 IPCB(skb)->iif = skb->dev->ifindex;
 405                 IPCB(skb)->flags = IPSKB_FORWARDED;
 406                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 407         }
 408
 409         switch (tuplehash->tuple.xmit_type) {
 410         case FLOW_OFFLOAD_XMIT_NEIGH:
 411                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 412                 outdev = rt->dst.dev;
 413                 skb->dev = outdev;
 414                 nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
 415                 skb_dst_set_noref(skb, &rt->dst);
 416                 neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
 417                 ret = NF_STOLEN;
 418                 break;
 419         case FLOW_OFFLOAD_XMIT_DIRECT:
 420                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IP);
 421                 if (ret == NF_DROP)
 422                         flow_offload_teardown(flow);
 423                 break;
 424         default:
 425                 WARN_ON_ONCE(1);
 426                 ret = NF_DROP;
 427                 break;
 428         }
 429
 430         return ret;
 431 }
 432 EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
 433
 434 static void nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
 435                                  struct in6_addr *addr,
 436                                  struct in6_addr *new_addr,
 437                                  struct ipv6hdr *ip6h)
 438 {
 439         struct tcphdr *tcph;
 440
 441         tcph = (void *)(skb_network_header(skb) + thoff);
 442         inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
 443                                   new_addr->s6_addr32, true);
 444 }
 445
 446 static void nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
 447                                  struct in6_addr *addr,
 448                                  struct in6_addr *new_addr)
 449 {
 450         struct udphdr *udph;
 451
 452         udph = (void *)(skb_network_header(skb) + thoff);
 453         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 454                 inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
 455                                           new_addr->s6_addr32, true);
 456                 if (!udph->check)
 457                         udph->check = CSUM_MANGLED_0;
 458         }
 459 }
 460
 461 static void nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
 462                                      unsigned int thoff, struct in6_addr *addr,
 463                                      struct in6_addr *new_addr)
 464 {
 465         switch (ip6h->nexthdr) {
 466         case IPPROTO_TCP:
 467                 nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr, ip6h);
 468                 break;
 469         case IPPROTO_UDP:
 470                 nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr);
 471                 break;
 472         }
 473 }
 474
 475 static void nf_flow_snat_ipv6(const struct flow_offload *flow,
 476                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 477                               unsigned int thoff,
 478                               enum flow_offload_tuple_dir dir)
 479 {
 480         struct in6_addr addr, new_addr;
 481
 482         switch (dir) {
 483         case FLOW_OFFLOAD_DIR_ORIGINAL:
 484                 addr = ip6h->saddr;
 485                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
 486                 ip6h->saddr = new_addr;
 487                 break;
 488         case FLOW_OFFLOAD_DIR_REPLY:
 489                 addr = ip6h->daddr;
 490                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
 491                 ip6h->daddr = new_addr;
 492                 break;
 493         }
 494
 495         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 496 }
 497
 498 static void nf_flow_dnat_ipv6(const struct flow_offload *flow,
 499                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 500                               unsigned int thoff,
 501                               enum flow_offload_tuple_dir dir)
 502 {
 503         struct in6_addr addr, new_addr;
 504
 505         switch (dir) {
 506         case FLOW_OFFLOAD_DIR_ORIGINAL:
 507                 addr = ip6h->daddr;
 508                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
 509                 ip6h->daddr = new_addr;
 510                 break;
 511         case FLOW_OFFLOAD_DIR_REPLY:
 512                 addr = ip6h->saddr;
 513                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
 514                 ip6h->saddr = new_addr;
 515                 break;
 516         }
 517
 518         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 519 }
 520
 521 static void nf_flow_nat_ipv6(const struct flow_offload *flow,
 522                              struct sk_buff *skb,
 523                              enum flow_offload_tuple_dir dir,
 524                              struct ipv6hdr *ip6h)
 525 {
 526         unsigned int thoff = sizeof(*ip6h);
 527
 528         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 529                 nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 530                 nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir);
 531         }
 532         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 533                 nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 534                 nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir);
 535         }
 536 }
 537
 538 static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
 539                               struct flow_offload_tuple *tuple, u32 *hdrsize,
 540                               u32 offset)
 541 {
 542         struct flow_ports *ports;
 543         struct ipv6hdr *ip6h;
 544         unsigned int thoff;
 545         u8 nexthdr;
 546
 547         thoff = sizeof(*ip6h) + offset;
 548         if (!pskb_may_pull(skb, thoff))
 549                 return -1;
 550
 551         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 552
 553         nexthdr = ip6h->nexthdr;
 554         switch (nexthdr) {
 555         case IPPROTO_TCP:
 556                 *hdrsize = sizeof(struct tcphdr);
 557                 break;
 558         case IPPROTO_UDP:
 559                 *hdrsize = sizeof(struct udphdr);
 560                 break;
 561 #ifdef CONFIG_NF_CT_PROTO_GRE
 562         case IPPROTO_GRE:
 563                 *hdrsize = sizeof(struct gre_base_hdr);
 564                 break;
 565 #endif
 566         default:
 567                 return -1;
 568         }
 569
 570         if (ip6h->hop_limit <= 1)
 571                 return -1;
 572
 573         if (!pskb_may_pull(skb, thoff + *hdrsize))
 574                 return -1;
 575
 576         switch (nexthdr) {
 577         case IPPROTO_TCP:
 578         case IPPROTO_UDP:
 579                 ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 580                 tuple->src_port         = ports->source;
 581                 tuple->dst_port         = ports->dest;
 582                 break;
 583         case IPPROTO_GRE: {
 584                 struct gre_base_hdr *greh;
 585
 586                 greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
 587                 if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
 588                         return -1;
 589                 break;
 590         }
 591         }
 592
 593         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 594
 595         tuple->src_v6           = ip6h->saddr;
 596         tuple->dst_v6           = ip6h->daddr;
 597         tuple->l3proto          = AF_INET6;
 598         tuple->l4proto          = nexthdr;
 599         tuple->iifidx           = dev->ifindex;
 600         nf_flow_tuple_encap(skb, tuple);
 601
 602         return 0;
 603 }
 604
 605 unsigned int
 606 nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 607                           const struct nf_hook_state *state)
 608 {
 609         struct flow_offload_tuple_rhash *tuplehash;
 610         struct nf_flowtable *flow_table = priv;
 611         struct flow_offload_tuple tuple = {};
 612         enum flow_offload_tuple_dir dir;
 613         const struct in6_addr *nexthop;
 614         struct flow_offload *flow;
 615         struct net_device *outdev;
 616         unsigned int thoff, mtu;
 617         u32 hdrsize, offset = 0;
 618         struct ipv6hdr *ip6h;
 619         struct rt6_info *rt;
 620         int ret;
 621
 622         if (skb->protocol != htons(ETH_P_IPV6) &&
 623             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IPV6), &offset))
 624                 return NF_ACCEPT;
 625
 626         if (nf_flow_tuple_ipv6(skb, state->in, &tuple, &hdrsize, offset) < 0)
 627                 return NF_ACCEPT;
 628
 629         tuplehash = flow_offload_lookup(flow_table, &tuple);
 630         if (tuplehash == NULL)
 631                 return NF_ACCEPT;
 632
 633         dir = tuplehash->tuple.dir;
 634         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 635
 636         mtu = flow->tuplehash[dir].tuple.mtu + offset;
 637         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 638                 return NF_ACCEPT;
 639
 640         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + offset);
 641         thoff = sizeof(*ip6h) + offset;
 642         if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
 643                 return NF_ACCEPT;
 644
 645         if (!nf_flow_dst_check(&tuplehash->tuple)) {
 646                 flow_offload_teardown(flow);
 647                 return NF_ACCEPT;
 648         }
 649
 650         if (skb_try_make_writable(skb, thoff + hdrsize))
 651                 return NF_DROP;
 652
 653         flow_offload_refresh(flow_table, flow);
 654
 655         nf_flow_encap_pop(skb, tuplehash);
 656
 657         ip6h = ipv6_hdr(skb);
 658         nf_flow_nat_ipv6(flow, skb, dir, ip6h);
 659
 660         ip6h->hop_limit--;
 661         skb_clear_tstamp(skb);
 662
 663         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 664                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 665
 666         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 667                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 668                 memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 669                 IP6CB(skb)->iif = skb->dev->ifindex;
 670                 IP6CB(skb)->flags = IP6SKB_FORWARDED;
 671                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 672         }
 673
 674         switch (tuplehash->tuple.xmit_type) {
 675         case FLOW_OFFLOAD_XMIT_NEIGH:
 676                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 677                 outdev = rt->dst.dev;
 678                 skb->dev = outdev;
 679                 nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
 680                 skb_dst_set_noref(skb, &rt->dst);
 681                 neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
 682                 ret = NF_STOLEN;
 683                 break;
 684         case FLOW_OFFLOAD_XMIT_DIRECT:
 685                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IPV6);
 686                 if (ret == NF_DROP)
 687                         flow_offload_teardown(flow);
 688                 break;
 689         default:
 690                 WARN_ON_ONCE(1);
 691                 ret = NF_DROP;
 692                 break;
 693         }
 694
 695         return ret;
 696 }
 697 EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);