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/gso.h>
  12 #include <net/ip.h>
  13 #include <net/ipv6.h>
  14 #include <net/ip6_route.h>
  15 #include <net/neighbour.h>
  16 #include <net/netfilter/nf_flow_table.h>
  17 #include <net/netfilter/nf_conntrack_acct.h>
  18 /* For layer 4 checksum field offset. */
  19 #include <linux/tcp.h>
  20 #include <linux/udp.h>
  21
  22 static int nf_flow_state_check(struct flow_offload *flow, int proto,
  23                                struct sk_buff *skb, unsigned int thoff)
  24 {
  25         struct tcphdr *tcph;
  26
  27         if (proto != IPPROTO_TCP)
  28                 return 0;
  29
  30         tcph = (void *)(skb_network_header(skb) + thoff);
  31         if (unlikely(tcph->fin || tcph->rst)) {
  32                 flow_offload_teardown(flow);
  33                 return -1;
  34         }
  35
  36         return 0;
  37 }
  38
  39 static void nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
  40                                __be32 addr, __be32 new_addr)
  41 {
  42         struct tcphdr *tcph;
  43
  44         tcph = (void *)(skb_network_header(skb) + thoff);
  45         inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
  46 }
  47
  48 static void nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
  49                                __be32 addr, __be32 new_addr)
  50 {
  51         struct udphdr *udph;
  52
  53         udph = (void *)(skb_network_header(skb) + thoff);
  54         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
  55                 inet_proto_csum_replace4(&udph->check, skb, addr,
  56                                          new_addr, true);
  57                 if (!udph->check)
  58                         udph->check = CSUM_MANGLED_0;
  59         }
  60 }
  61
  62 static void nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
  63                                    unsigned int thoff, __be32 addr,
  64                                    __be32 new_addr)
  65 {
  66         switch (iph->protocol) {
  67         case IPPROTO_TCP:
  68                 nf_flow_nat_ip_tcp(skb, thoff, addr, new_addr);
  69                 break;
  70         case IPPROTO_UDP:
  71                 nf_flow_nat_ip_udp(skb, thoff, addr, new_addr);
  72                 break;
  73         }
  74 }
  75
  76 static void nf_flow_snat_ip(const struct flow_offload *flow,
  77                             struct sk_buff *skb, struct iphdr *iph,
  78                             unsigned int thoff, enum flow_offload_tuple_dir dir)
  79 {
  80         __be32 addr, new_addr;
  81
  82         switch (dir) {
  83         case FLOW_OFFLOAD_DIR_ORIGINAL:
  84                 addr = iph->saddr;
  85                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
  86                 iph->saddr = new_addr;
  87                 break;
  88         case FLOW_OFFLOAD_DIR_REPLY:
  89                 addr = iph->daddr;
  90                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
  91                 iph->daddr = new_addr;
  92                 break;
  93         }
  94         csum_replace4(&iph->check, addr, new_addr);
  95
  96         nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
  97 }
  98
  99 static void nf_flow_dnat_ip(const struct flow_offload *flow,
 100                             struct sk_buff *skb, struct iphdr *iph,
 101                             unsigned int thoff, enum flow_offload_tuple_dir dir)
 102 {
 103         __be32 addr, new_addr;
 104
 105         switch (dir) {
 106         case FLOW_OFFLOAD_DIR_ORIGINAL:
 107                 addr = iph->daddr;
 108                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
 109                 iph->daddr = new_addr;
 110                 break;
 111         case FLOW_OFFLOAD_DIR_REPLY:
 112                 addr = iph->saddr;
 113                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
 114                 iph->saddr = new_addr;
 115                 break;
 116         }
 117         csum_replace4(&iph->check, addr, new_addr);
 118
 119         nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
 120 }
 121
 122 static void nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
 123                           unsigned int thoff, enum flow_offload_tuple_dir dir,
 124                           struct iphdr *iph)
 125 {
 126         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 127                 nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir);
 128                 nf_flow_snat_ip(flow, skb, iph, thoff, dir);
 129         }
 130         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 131                 nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir);
 132                 nf_flow_dnat_ip(flow, skb, iph, thoff, dir);
 133         }
 134 }
 135
 136 static bool ip_has_options(unsigned int thoff)
 137 {
 138         return thoff != sizeof(struct iphdr);
 139 }
 140
 141 static void nf_flow_tuple_encap(struct sk_buff *skb,
 142                                 struct flow_offload_tuple *tuple)
 143 {
 144         struct vlan_ethhdr *veth;
 145         struct pppoe_hdr *phdr;
 146         int i = 0;
 147
 148         if (skb_vlan_tag_present(skb)) {
 149                 tuple->encap[i].id = skb_vlan_tag_get(skb);
 150                 tuple->encap[i].proto = skb->vlan_proto;
 151                 i++;
 152         }
 153         switch (skb->protocol) {
 154         case htons(ETH_P_8021Q):
 155                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 156                 tuple->encap[i].id = ntohs(veth->h_vlan_TCI);
 157                 tuple->encap[i].proto = skb->protocol;
 158                 break;
 159         case htons(ETH_P_PPP_SES):
 160                 phdr = (struct pppoe_hdr *)skb_network_header(skb);
 161                 tuple->encap[i].id = ntohs(phdr->sid);
 162                 tuple->encap[i].proto = skb->protocol;
 163                 break;
 164         }
 165 }
 166
 167 struct nf_flowtable_ctx {
 168         const struct net_device *in;
 169         u32                     offset;
 170         u32                     hdrsize;
 171 };
 172
 173 static int nf_flow_tuple_ip(struct nf_flowtable_ctx *ctx, struct sk_buff *skb,
 174                             struct flow_offload_tuple *tuple)
 175 {
 176         struct flow_ports *ports;
 177         unsigned int thoff;
 178         struct iphdr *iph;
 179         u8 ipproto;
 180
 181         if (!pskb_may_pull(skb, sizeof(*iph) + ctx->offset))
 182                 return -1;
 183
 184         iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
 185         thoff = (iph->ihl * 4);
 186
 187         if (ip_is_fragment(iph) ||
 188             unlikely(ip_has_options(thoff)))
 189                 return -1;
 190
 191         thoff += ctx->offset;
 192
 193         ipproto = iph->protocol;
 194         switch (ipproto) {
 195         case IPPROTO_TCP:
 196                 ctx->hdrsize = sizeof(struct tcphdr);
 197                 break;
 198         case IPPROTO_UDP:
 199                 ctx->hdrsize = sizeof(struct udphdr);
 200                 break;
 201 #ifdef CONFIG_NF_CT_PROTO_GRE
 202         case IPPROTO_GRE:
 203                 ctx->hdrsize = sizeof(struct gre_base_hdr);
 204                 break;
 205 #endif
 206         default:
 207                 return -1;
 208         }
 209
 210         if (iph->ttl <= 1)
 211                 return -1;
 212
 213         if (!pskb_may_pull(skb, thoff + ctx->hdrsize))
 214                 return -1;
 215
 216         switch (ipproto) {
 217         case IPPROTO_TCP:
 218         case IPPROTO_UDP:
 219                 ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 220                 tuple->src_port         = ports->source;
 221                 tuple->dst_port         = ports->dest;
 222                 break;
 223         case IPPROTO_GRE: {
 224                 struct gre_base_hdr *greh;
 225
 226                 greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
 227                 if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
 228                         return -1;
 229                 break;
 230         }
 231         }
 232
 233         iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
 234
 235         tuple->src_v4.s_addr    = iph->saddr;
 236         tuple->dst_v4.s_addr    = iph->daddr;
 237         tuple->l3proto          = AF_INET;
 238         tuple->l4proto          = ipproto;
 239         tuple->iifidx           = ctx->in->ifindex;
 240         nf_flow_tuple_encap(skb, tuple);
 241
 242         return 0;
 243 }
 244
 245 /* Based on ip_exceeds_mtu(). */
 246 static bool nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
 247 {
 248         if (skb->len <= mtu)
 249                 return false;
 250
 251         if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
 252                 return false;
 253
 254         return true;
 255 }
 256
 257 static inline bool nf_flow_dst_check(struct flow_offload_tuple *tuple)
 258 {
 259         if (tuple->xmit_type != FLOW_OFFLOAD_XMIT_NEIGH &&
 260             tuple->xmit_type != FLOW_OFFLOAD_XMIT_XFRM)
 261                 return true;
 262
 263         return dst_check(tuple->dst_cache, tuple->dst_cookie);
 264 }
 265
 266 static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
 267                                       const struct nf_hook_state *state,
 268                                       struct dst_entry *dst)
 269 {
 270         skb_orphan(skb);
 271         skb_dst_set_noref(skb, dst);
 272         dst_output(state->net, state->sk, skb);
 273         return NF_STOLEN;
 274 }
 275
 276 static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto,
 277                                        u32 *offset)
 278 {
 279         struct vlan_ethhdr *veth;
 280         __be16 inner_proto;
 281
 282         switch (skb->protocol) {
 283         case htons(ETH_P_8021Q):
 284                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 285                 if (veth->h_vlan_encapsulated_proto == proto) {
 286                         *offset += VLAN_HLEN;
 287                         return true;
 288                 }
 289                 break;
 290         case htons(ETH_P_PPP_SES):
 291                 if (nf_flow_pppoe_proto(skb, &inner_proto) &&
 292                     inner_proto == proto) {
 293                         *offset += PPPOE_SES_HLEN;
 294                         return true;
 295                 }
 296                 break;
 297         }
 298
 299         return false;
 300 }
 301
 302 static void nf_flow_encap_pop(struct sk_buff *skb,
 303                               struct flow_offload_tuple_rhash *tuplehash)
 304 {
 305         struct vlan_hdr *vlan_hdr;
 306         int i;
 307
 308         for (i = 0; i < tuplehash->tuple.encap_num; i++) {
 309                 if (skb_vlan_tag_present(skb)) {
 310                         __vlan_hwaccel_clear_tag(skb);
 311                         continue;
 312                 }
 313                 switch (skb->protocol) {
 314                 case htons(ETH_P_8021Q):
 315                         vlan_hdr = (struct vlan_hdr *)skb->data;
 316                         __skb_pull(skb, VLAN_HLEN);
 317                         vlan_set_encap_proto(skb, vlan_hdr);
 318                         skb_reset_network_header(skb);
 319                         break;
 320                 case htons(ETH_P_PPP_SES):
 321                         skb->protocol = __nf_flow_pppoe_proto(skb);
 322                         skb_pull(skb, PPPOE_SES_HLEN);
 323                         skb_reset_network_header(skb);
 324                         break;
 325                 }
 326         }
 327 }
 328
 329 static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,
 330                                        const struct flow_offload_tuple_rhash *tuplehash,
 331                                        unsigned short type)
 332 {
 333         struct net_device *outdev;
 334
 335         outdev = dev_get_by_index_rcu(net, tuplehash->tuple.out.ifidx);
 336         if (!outdev)
 337                 return NF_DROP;
 338
 339         skb->dev = outdev;
 340         dev_hard_header(skb, skb->dev, type, tuplehash->tuple.out.h_dest,
 341                         tuplehash->tuple.out.h_source, skb->len);
 342         dev_queue_xmit(skb);
 343
 344         return NF_STOLEN;
 345 }
 346
 347 static struct flow_offload_tuple_rhash *
 348 nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx,
 349                        struct nf_flowtable *flow_table, struct sk_buff *skb)
 350 {
 351         struct flow_offload_tuple tuple = {};
 352
 353         if (skb->protocol != htons(ETH_P_IP) &&
 354             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &ctx->offset))
 355                 return NULL;
 356
 357         if (nf_flow_tuple_ip(ctx, skb, &tuple) < 0)
 358                 return NULL;
 359
 360         return flow_offload_lookup(flow_table, &tuple);
 361 }
 362
 363 static int nf_flow_offload_forward(struct nf_flowtable_ctx *ctx,
 364                                    struct nf_flowtable *flow_table,
 365                                    struct flow_offload_tuple_rhash *tuplehash,
 366                                    struct sk_buff *skb)
 367 {
 368         enum flow_offload_tuple_dir dir;
 369         struct flow_offload *flow;
 370         unsigned int thoff, mtu;
 371         struct iphdr *iph;
 372
 373         dir = tuplehash->tuple.dir;
 374         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 375
 376         mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset;
 377         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 378                 return 0;
 379
 380         iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
 381         thoff = (iph->ihl * 4) + ctx->offset;
 382         if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
 383                 return 0;
 384
 385         if (!nf_flow_dst_check(&tuplehash->tuple)) {
 386                 flow_offload_teardown(flow);
 387                 return 0;
 388         }
 389
 390         if (skb_try_make_writable(skb, thoff + ctx->hdrsize))
 391                 return -1;
 392
 393         flow_offload_refresh(flow_table, flow, false);
 394
 395         nf_flow_encap_pop(skb, tuplehash);
 396         thoff -= ctx->offset;
 397
 398         iph = ip_hdr(skb);
 399         nf_flow_nat_ip(flow, skb, thoff, dir, iph);
 400
 401         ip_decrease_ttl(iph);
 402         skb_clear_tstamp(skb);
 403
 404         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 405                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 406
 407         return 1;
 408 }
 409
 410 unsigned int
 411 nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 412                         const struct nf_hook_state *state)
 413 {
 414         struct flow_offload_tuple_rhash *tuplehash;
 415         struct nf_flowtable *flow_table = priv;
 416         enum flow_offload_tuple_dir dir;
 417         struct nf_flowtable_ctx ctx = {
 418                 .in     = state->in,
 419         };
 420         struct flow_offload *flow;
 421         struct net_device *outdev;
 422         struct rtable *rt;
 423         __be32 nexthop;
 424         int ret;
 425
 426         tuplehash = nf_flow_offload_lookup(&ctx, flow_table, skb);
 427         if (!tuplehash)
 428                 return NF_ACCEPT;
 429
 430         ret = nf_flow_offload_forward(&ctx, flow_table, tuplehash, skb);
 431         if (ret < 0)
 432                 return NF_DROP;
 433         else if (ret == 0)
 434                 return NF_ACCEPT;
 435
 436         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 437                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 438                 memset(skb->cb, 0, sizeof(struct inet_skb_parm));
 439                 IPCB(skb)->iif = skb->dev->ifindex;
 440                 IPCB(skb)->flags = IPSKB_FORWARDED;
 441                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 442         }
 443
 444         dir = tuplehash->tuple.dir;
 445         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 446
 447         switch (tuplehash->tuple.xmit_type) {
 448         case FLOW_OFFLOAD_XMIT_NEIGH:
 449                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 450                 outdev = rt->dst.dev;
 451                 skb->dev = outdev;
 452                 nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
 453                 skb_dst_set_noref(skb, &rt->dst);
 454                 neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
 455                 ret = NF_STOLEN;
 456                 break;
 457         case FLOW_OFFLOAD_XMIT_DIRECT:
 458                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IP);
 459                 if (ret == NF_DROP)
 460                         flow_offload_teardown(flow);
 461                 break;
 462         default:
 463                 WARN_ON_ONCE(1);
 464                 ret = NF_DROP;
 465                 break;
 466         }
 467
 468         return ret;
 469 }
 470 EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
 471
 472 static void nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
 473                                  struct in6_addr *addr,
 474                                  struct in6_addr *new_addr,
 475                                  struct ipv6hdr *ip6h)
 476 {
 477         struct tcphdr *tcph;
 478
 479         tcph = (void *)(skb_network_header(skb) + thoff);
 480         inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
 481                                   new_addr->s6_addr32, true);
 482 }
 483
 484 static void nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
 485                                  struct in6_addr *addr,
 486                                  struct in6_addr *new_addr)
 487 {
 488         struct udphdr *udph;
 489
 490         udph = (void *)(skb_network_header(skb) + thoff);
 491         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 492                 inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
 493                                           new_addr->s6_addr32, true);
 494                 if (!udph->check)
 495                         udph->check = CSUM_MANGLED_0;
 496         }
 497 }
 498
 499 static void nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
 500                                      unsigned int thoff, struct in6_addr *addr,
 501                                      struct in6_addr *new_addr)
 502 {
 503         switch (ip6h->nexthdr) {
 504         case IPPROTO_TCP:
 505                 nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr, ip6h);
 506                 break;
 507         case IPPROTO_UDP:
 508                 nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr);
 509                 break;
 510         }
 511 }
 512
 513 static void nf_flow_snat_ipv6(const struct flow_offload *flow,
 514                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 515                               unsigned int thoff,
 516                               enum flow_offload_tuple_dir dir)
 517 {
 518         struct in6_addr addr, new_addr;
 519
 520         switch (dir) {
 521         case FLOW_OFFLOAD_DIR_ORIGINAL:
 522                 addr = ip6h->saddr;
 523                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
 524                 ip6h->saddr = new_addr;
 525                 break;
 526         case FLOW_OFFLOAD_DIR_REPLY:
 527                 addr = ip6h->daddr;
 528                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
 529                 ip6h->daddr = new_addr;
 530                 break;
 531         }
 532
 533         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 534 }
 535
 536 static void nf_flow_dnat_ipv6(const struct flow_offload *flow,
 537                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 538                               unsigned int thoff,
 539                               enum flow_offload_tuple_dir dir)
 540 {
 541         struct in6_addr addr, new_addr;
 542
 543         switch (dir) {
 544         case FLOW_OFFLOAD_DIR_ORIGINAL:
 545                 addr = ip6h->daddr;
 546                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
 547                 ip6h->daddr = new_addr;
 548                 break;
 549         case FLOW_OFFLOAD_DIR_REPLY:
 550                 addr = ip6h->saddr;
 551                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
 552                 ip6h->saddr = new_addr;
 553                 break;
 554         }
 555
 556         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 557 }
 558
 559 static void nf_flow_nat_ipv6(const struct flow_offload *flow,
 560                              struct sk_buff *skb,
 561                              enum flow_offload_tuple_dir dir,
 562                              struct ipv6hdr *ip6h)
 563 {
 564         unsigned int thoff = sizeof(*ip6h);
 565
 566         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 567                 nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 568                 nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir);
 569         }
 570         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 571                 nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 572                 nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir);
 573         }
 574 }
 575
 576 static int nf_flow_tuple_ipv6(struct nf_flowtable_ctx *ctx, struct sk_buff *skb,
 577                               struct flow_offload_tuple *tuple)
 578 {
 579         struct flow_ports *ports;
 580         struct ipv6hdr *ip6h;
 581         unsigned int thoff;
 582         u8 nexthdr;
 583
 584         thoff = sizeof(*ip6h) + ctx->offset;
 585         if (!pskb_may_pull(skb, thoff))
 586                 return -1;
 587
 588         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
 589
 590         nexthdr = ip6h->nexthdr;
 591         switch (nexthdr) {
 592         case IPPROTO_TCP:
 593                 ctx->hdrsize = sizeof(struct tcphdr);
 594                 break;
 595         case IPPROTO_UDP:
 596                 ctx->hdrsize = sizeof(struct udphdr);
 597                 break;
 598 #ifdef CONFIG_NF_CT_PROTO_GRE
 599         case IPPROTO_GRE:
 600                 ctx->hdrsize = sizeof(struct gre_base_hdr);
 601                 break;
 602 #endif
 603         default:
 604                 return -1;
 605         }
 606
 607         if (ip6h->hop_limit <= 1)
 608                 return -1;
 609
 610         if (!pskb_may_pull(skb, thoff + ctx->hdrsize))
 611                 return -1;
 612
 613         switch (nexthdr) {
 614         case IPPROTO_TCP:
 615         case IPPROTO_UDP:
 616                 ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 617                 tuple->src_port         = ports->source;
 618                 tuple->dst_port         = ports->dest;
 619                 break;
 620         case IPPROTO_GRE: {
 621                 struct gre_base_hdr *greh;
 622
 623                 greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
 624                 if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
 625                         return -1;
 626                 break;
 627         }
 628         }
 629
 630         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
 631
 632         tuple->src_v6           = ip6h->saddr;
 633         tuple->dst_v6           = ip6h->daddr;
 634         tuple->l3proto          = AF_INET6;
 635         tuple->l4proto          = nexthdr;
 636         tuple->iifidx           = ctx->in->ifindex;
 637         nf_flow_tuple_encap(skb, tuple);
 638
 639         return 0;
 640 }
 641
 642 static int nf_flow_offload_ipv6_forward(struct nf_flowtable_ctx *ctx,
 643                                         struct nf_flowtable *flow_table,
 644                                         struct flow_offload_tuple_rhash *tuplehash,
 645                                         struct sk_buff *skb)
 646 {
 647         enum flow_offload_tuple_dir dir;
 648         struct flow_offload *flow;
 649         unsigned int thoff, mtu;
 650         struct ipv6hdr *ip6h;
 651
 652         dir = tuplehash->tuple.dir;
 653         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 654
 655         mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset;
 656         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 657                 return 0;
 658
 659         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
 660         thoff = sizeof(*ip6h) + ctx->offset;
 661         if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
 662                 return 0;
 663
 664         if (!nf_flow_dst_check(&tuplehash->tuple)) {
 665                 flow_offload_teardown(flow);
 666                 return 0;
 667         }
 668
 669         if (skb_try_make_writable(skb, thoff + ctx->hdrsize))
 670                 return -1;
 671
 672         flow_offload_refresh(flow_table, flow, false);
 673
 674         nf_flow_encap_pop(skb, tuplehash);
 675
 676         ip6h = ipv6_hdr(skb);
 677         nf_flow_nat_ipv6(flow, skb, dir, ip6h);
 678
 679         ip6h->hop_limit--;
 680         skb_clear_tstamp(skb);
 681
 682         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 683                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 684
 685         return 1;
 686 }
 687
 688 static struct flow_offload_tuple_rhash *
 689 nf_flow_offload_ipv6_lookup(struct nf_flowtable_ctx *ctx,
 690                             struct nf_flowtable *flow_table,
 691                             struct sk_buff *skb)
 692 {
 693         struct flow_offload_tuple tuple = {};
 694
 695         if (skb->protocol != htons(ETH_P_IPV6) &&
 696             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IPV6), &ctx->offset))
 697                 return NULL;
 698
 699         if (nf_flow_tuple_ipv6(ctx, skb, &tuple) < 0)
 700                 return NULL;
 701
 702         return flow_offload_lookup(flow_table, &tuple);
 703 }
 704
 705 unsigned int
 706 nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 707                           const struct nf_hook_state *state)
 708 {
 709         struct flow_offload_tuple_rhash *tuplehash;
 710         struct nf_flowtable *flow_table = priv;
 711         enum flow_offload_tuple_dir dir;
 712         struct nf_flowtable_ctx ctx = {
 713                 .in     = state->in,
 714         };
 715         const struct in6_addr *nexthop;
 716         struct flow_offload *flow;
 717         struct net_device *outdev;
 718         struct rt6_info *rt;
 719         int ret;
 720
 721         tuplehash = nf_flow_offload_ipv6_lookup(&ctx, flow_table, skb);
 722         if (tuplehash == NULL)
 723                 return NF_ACCEPT;
 724
 725         ret = nf_flow_offload_ipv6_forward(&ctx, flow_table, tuplehash, skb);
 726         if (ret < 0)
 727                 return NF_DROP;
 728         else if (ret == 0)
 729                 return NF_ACCEPT;
 730
 731         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 732                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 733                 memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 734                 IP6CB(skb)->iif = skb->dev->ifindex;
 735                 IP6CB(skb)->flags = IP6SKB_FORWARDED;
 736                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 737         }
 738
 739         dir = tuplehash->tuple.dir;
 740         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 741
 742         switch (tuplehash->tuple.xmit_type) {
 743         case FLOW_OFFLOAD_XMIT_NEIGH:
 744                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 745                 outdev = rt->dst.dev;
 746                 skb->dev = outdev;
 747                 nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
 748                 skb_dst_set_noref(skb, &rt->dst);
 749                 neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
 750                 ret = NF_STOLEN;
 751                 break;
 752         case FLOW_OFFLOAD_XMIT_DIRECT:
 753                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IPV6);
 754                 if (ret == NF_DROP)
 755                         flow_offload_teardown(flow);
 756                 break;
 757         default:
 758                 WARN_ON_ONCE(1);
 759                 ret = NF_DROP;
 760                 break;
 761         }
 762
 763         return ret;
 764 }
 765 EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);