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_mac_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(const struct sk_buff *skb, __be16 proto,
 277                                        u32 *offset)
 278 {
 279         struct vlan_ethhdr *veth;
 280
 281         switch (skb->protocol) {
 282         case htons(ETH_P_8021Q):
 283                 veth = (struct vlan_ethhdr *)skb_mac_header(skb);
 284                 if (veth->h_vlan_encapsulated_proto == proto) {
 285                         *offset += VLAN_HLEN;
 286                         return true;
 287                 }
 288                 break;
 289         case htons(ETH_P_PPP_SES):
 290                 if (nf_flow_pppoe_proto(skb) == proto) {
 291                         *offset += PPPOE_SES_HLEN;
 292                         return true;
 293                 }
 294                 break;
 295         }
 296
 297         return false;
 298 }
 299
 300 static void nf_flow_encap_pop(struct sk_buff *skb,
 301                               struct flow_offload_tuple_rhash *tuplehash)
 302 {
 303         struct vlan_hdr *vlan_hdr;
 304         int i;
 305
 306         for (i = 0; i < tuplehash->tuple.encap_num; i++) {
 307                 if (skb_vlan_tag_present(skb)) {
 308                         __vlan_hwaccel_clear_tag(skb);
 309                         continue;
 310                 }
 311                 switch (skb->protocol) {
 312                 case htons(ETH_P_8021Q):
 313                         vlan_hdr = (struct vlan_hdr *)skb->data;
 314                         __skb_pull(skb, VLAN_HLEN);
 315                         vlan_set_encap_proto(skb, vlan_hdr);
 316                         skb_reset_network_header(skb);
 317                         break;
 318                 case htons(ETH_P_PPP_SES):
 319                         skb->protocol = nf_flow_pppoe_proto(skb);
 320                         skb_pull(skb, PPPOE_SES_HLEN);
 321                         skb_reset_network_header(skb);
 322                         break;
 323                 }
 324         }
 325 }
 326
 327 static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,
 328                                        const struct flow_offload_tuple_rhash *tuplehash,
 329                                        unsigned short type)
 330 {
 331         struct net_device *outdev;
 332
 333         outdev = dev_get_by_index_rcu(net, tuplehash->tuple.out.ifidx);
 334         if (!outdev)
 335                 return NF_DROP;
 336
 337         skb->dev = outdev;
 338         dev_hard_header(skb, skb->dev, type, tuplehash->tuple.out.h_dest,
 339                         tuplehash->tuple.out.h_source, skb->len);
 340         dev_queue_xmit(skb);
 341
 342         return NF_STOLEN;
 343 }
 344
 345 static struct flow_offload_tuple_rhash *
 346 nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx,
 347                        struct nf_flowtable *flow_table, struct sk_buff *skb)
 348 {
 349         struct flow_offload_tuple tuple = {};
 350
 351         if (skb->protocol != htons(ETH_P_IP) &&
 352             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &ctx->offset))
 353                 return NULL;
 354
 355         if (nf_flow_tuple_ip(ctx, skb, &tuple) < 0)
 356                 return NULL;
 357
 358         return flow_offload_lookup(flow_table, &tuple);
 359 }
 360
 361 static int nf_flow_offload_forward(struct nf_flowtable_ctx *ctx,
 362                                    struct nf_flowtable *flow_table,
 363                                    struct flow_offload_tuple_rhash *tuplehash,
 364                                    struct sk_buff *skb)
 365 {
 366         enum flow_offload_tuple_dir dir;
 367         struct flow_offload *flow;
 368         unsigned int thoff, mtu;
 369         struct iphdr *iph;
 370
 371         dir = tuplehash->tuple.dir;
 372         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 373
 374         mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset;
 375         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 376                 return 0;
 377
 378         iph = (struct iphdr *)(skb_network_header(skb) + ctx->offset);
 379         thoff = (iph->ihl * 4) + ctx->offset;
 380         if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
 381                 return 0;
 382
 383         if (!nf_flow_dst_check(&tuplehash->tuple)) {
 384                 flow_offload_teardown(flow);
 385                 return 0;
 386         }
 387
 388         if (skb_try_make_writable(skb, thoff + ctx->hdrsize))
 389                 return -1;
 390
 391         flow_offload_refresh(flow_table, flow, false);
 392
 393         nf_flow_encap_pop(skb, tuplehash);
 394         thoff -= ctx->offset;
 395
 396         iph = ip_hdr(skb);
 397         nf_flow_nat_ip(flow, skb, thoff, dir, iph);
 398
 399         ip_decrease_ttl(iph);
 400         skb_clear_tstamp(skb);
 401
 402         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 403                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 404
 405         return 1;
 406 }
 407
 408 unsigned int
 409 nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 410                         const struct nf_hook_state *state)
 411 {
 412         struct flow_offload_tuple_rhash *tuplehash;
 413         struct nf_flowtable *flow_table = priv;
 414         enum flow_offload_tuple_dir dir;
 415         struct nf_flowtable_ctx ctx = {
 416                 .in     = state->in,
 417         };
 418         struct flow_offload *flow;
 419         struct net_device *outdev;
 420         struct rtable *rt;
 421         __be32 nexthop;
 422         int ret;
 423
 424         tuplehash = nf_flow_offload_lookup(&ctx, flow_table, skb);
 425         if (!tuplehash)
 426                 return NF_ACCEPT;
 427
 428         ret = nf_flow_offload_forward(&ctx, flow_table, tuplehash, skb);
 429         if (ret < 0)
 430                 return NF_DROP;
 431         else if (ret == 0)
 432                 return NF_ACCEPT;
 433
 434         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 435                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 436                 memset(skb->cb, 0, sizeof(struct inet_skb_parm));
 437                 IPCB(skb)->iif = skb->dev->ifindex;
 438                 IPCB(skb)->flags = IPSKB_FORWARDED;
 439                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 440         }
 441
 442         dir = tuplehash->tuple.dir;
 443         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 444
 445         switch (tuplehash->tuple.xmit_type) {
 446         case FLOW_OFFLOAD_XMIT_NEIGH:
 447                 rt = (struct rtable *)tuplehash->tuple.dst_cache;
 448                 outdev = rt->dst.dev;
 449                 skb->dev = outdev;
 450                 nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
 451                 skb_dst_set_noref(skb, &rt->dst);
 452                 neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
 453                 ret = NF_STOLEN;
 454                 break;
 455         case FLOW_OFFLOAD_XMIT_DIRECT:
 456                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IP);
 457                 if (ret == NF_DROP)
 458                         flow_offload_teardown(flow);
 459                 break;
 460         default:
 461                 WARN_ON_ONCE(1);
 462                 ret = NF_DROP;
 463                 break;
 464         }
 465
 466         return ret;
 467 }
 468 EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
 469
 470 static void nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
 471                                  struct in6_addr *addr,
 472                                  struct in6_addr *new_addr,
 473                                  struct ipv6hdr *ip6h)
 474 {
 475         struct tcphdr *tcph;
 476
 477         tcph = (void *)(skb_network_header(skb) + thoff);
 478         inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
 479                                   new_addr->s6_addr32, true);
 480 }
 481
 482 static void nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
 483                                  struct in6_addr *addr,
 484                                  struct in6_addr *new_addr)
 485 {
 486         struct udphdr *udph;
 487
 488         udph = (void *)(skb_network_header(skb) + thoff);
 489         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 490                 inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
 491                                           new_addr->s6_addr32, true);
 492                 if (!udph->check)
 493                         udph->check = CSUM_MANGLED_0;
 494         }
 495 }
 496
 497 static void nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
 498                                      unsigned int thoff, struct in6_addr *addr,
 499                                      struct in6_addr *new_addr)
 500 {
 501         switch (ip6h->nexthdr) {
 502         case IPPROTO_TCP:
 503                 nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr, ip6h);
 504                 break;
 505         case IPPROTO_UDP:
 506                 nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr);
 507                 break;
 508         }
 509 }
 510
 511 static void nf_flow_snat_ipv6(const struct flow_offload *flow,
 512                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 513                               unsigned int thoff,
 514                               enum flow_offload_tuple_dir dir)
 515 {
 516         struct in6_addr addr, new_addr;
 517
 518         switch (dir) {
 519         case FLOW_OFFLOAD_DIR_ORIGINAL:
 520                 addr = ip6h->saddr;
 521                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
 522                 ip6h->saddr = new_addr;
 523                 break;
 524         case FLOW_OFFLOAD_DIR_REPLY:
 525                 addr = ip6h->daddr;
 526                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
 527                 ip6h->daddr = new_addr;
 528                 break;
 529         }
 530
 531         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 532 }
 533
 534 static void nf_flow_dnat_ipv6(const struct flow_offload *flow,
 535                               struct sk_buff *skb, struct ipv6hdr *ip6h,
 536                               unsigned int thoff,
 537                               enum flow_offload_tuple_dir dir)
 538 {
 539         struct in6_addr addr, new_addr;
 540
 541         switch (dir) {
 542         case FLOW_OFFLOAD_DIR_ORIGINAL:
 543                 addr = ip6h->daddr;
 544                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
 545                 ip6h->daddr = new_addr;
 546                 break;
 547         case FLOW_OFFLOAD_DIR_REPLY:
 548                 addr = ip6h->saddr;
 549                 new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
 550                 ip6h->saddr = new_addr;
 551                 break;
 552         }
 553
 554         nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
 555 }
 556
 557 static void nf_flow_nat_ipv6(const struct flow_offload *flow,
 558                              struct sk_buff *skb,
 559                              enum flow_offload_tuple_dir dir,
 560                              struct ipv6hdr *ip6h)
 561 {
 562         unsigned int thoff = sizeof(*ip6h);
 563
 564         if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 565                 nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 566                 nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir);
 567         }
 568         if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 569                 nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir);
 570                 nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir);
 571         }
 572 }
 573
 574 static int nf_flow_tuple_ipv6(struct nf_flowtable_ctx *ctx, struct sk_buff *skb,
 575                               struct flow_offload_tuple *tuple)
 576 {
 577         struct flow_ports *ports;
 578         struct ipv6hdr *ip6h;
 579         unsigned int thoff;
 580         u8 nexthdr;
 581
 582         thoff = sizeof(*ip6h) + ctx->offset;
 583         if (!pskb_may_pull(skb, thoff))
 584                 return -1;
 585
 586         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
 587
 588         nexthdr = ip6h->nexthdr;
 589         switch (nexthdr) {
 590         case IPPROTO_TCP:
 591                 ctx->hdrsize = sizeof(struct tcphdr);
 592                 break;
 593         case IPPROTO_UDP:
 594                 ctx->hdrsize = sizeof(struct udphdr);
 595                 break;
 596 #ifdef CONFIG_NF_CT_PROTO_GRE
 597         case IPPROTO_GRE:
 598                 ctx->hdrsize = sizeof(struct gre_base_hdr);
 599                 break;
 600 #endif
 601         default:
 602                 return -1;
 603         }
 604
 605         if (ip6h->hop_limit <= 1)
 606                 return -1;
 607
 608         if (!pskb_may_pull(skb, thoff + ctx->hdrsize))
 609                 return -1;
 610
 611         switch (nexthdr) {
 612         case IPPROTO_TCP:
 613         case IPPROTO_UDP:
 614                 ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
 615                 tuple->src_port         = ports->source;
 616                 tuple->dst_port         = ports->dest;
 617                 break;
 618         case IPPROTO_GRE: {
 619                 struct gre_base_hdr *greh;
 620
 621                 greh = (struct gre_base_hdr *)(skb_network_header(skb) + thoff);
 622                 if ((greh->flags & GRE_VERSION) != GRE_VERSION_0)
 623                         return -1;
 624                 break;
 625         }
 626         }
 627
 628         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
 629
 630         tuple->src_v6           = ip6h->saddr;
 631         tuple->dst_v6           = ip6h->daddr;
 632         tuple->l3proto          = AF_INET6;
 633         tuple->l4proto          = nexthdr;
 634         tuple->iifidx           = ctx->in->ifindex;
 635         nf_flow_tuple_encap(skb, tuple);
 636
 637         return 0;
 638 }
 639
 640 static int nf_flow_offload_ipv6_forward(struct nf_flowtable_ctx *ctx,
 641                                         struct nf_flowtable *flow_table,
 642                                         struct flow_offload_tuple_rhash *tuplehash,
 643                                         struct sk_buff *skb)
 644 {
 645         enum flow_offload_tuple_dir dir;
 646         struct flow_offload *flow;
 647         unsigned int thoff, mtu;
 648         struct ipv6hdr *ip6h;
 649
 650         dir = tuplehash->tuple.dir;
 651         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 652
 653         mtu = flow->tuplehash[dir].tuple.mtu + ctx->offset;
 654         if (unlikely(nf_flow_exceeds_mtu(skb, mtu)))
 655                 return 0;
 656
 657         ip6h = (struct ipv6hdr *)(skb_network_header(skb) + ctx->offset);
 658         thoff = sizeof(*ip6h) + ctx->offset;
 659         if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
 660                 return 0;
 661
 662         if (!nf_flow_dst_check(&tuplehash->tuple)) {
 663                 flow_offload_teardown(flow);
 664                 return 0;
 665         }
 666
 667         if (skb_try_make_writable(skb, thoff + ctx->hdrsize))
 668                 return -1;
 669
 670         flow_offload_refresh(flow_table, flow, false);
 671
 672         nf_flow_encap_pop(skb, tuplehash);
 673
 674         ip6h = ipv6_hdr(skb);
 675         nf_flow_nat_ipv6(flow, skb, dir, ip6h);
 676
 677         ip6h->hop_limit--;
 678         skb_clear_tstamp(skb);
 679
 680         if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 681                 nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 682
 683         return 1;
 684 }
 685
 686 static struct flow_offload_tuple_rhash *
 687 nf_flow_offload_ipv6_lookup(struct nf_flowtable_ctx *ctx,
 688                             struct nf_flowtable *flow_table,
 689                             struct sk_buff *skb)
 690 {
 691         struct flow_offload_tuple tuple = {};
 692
 693         if (skb->protocol != htons(ETH_P_IPV6) &&
 694             !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IPV6), &ctx->offset))
 695                 return NULL;
 696
 697         if (nf_flow_tuple_ipv6(ctx, skb, &tuple) < 0)
 698                 return NULL;
 699
 700         return flow_offload_lookup(flow_table, &tuple);
 701 }
 702
 703 unsigned int
 704 nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 705                           const struct nf_hook_state *state)
 706 {
 707         struct flow_offload_tuple_rhash *tuplehash;
 708         struct nf_flowtable *flow_table = priv;
 709         enum flow_offload_tuple_dir dir;
 710         struct nf_flowtable_ctx ctx = {
 711                 .in     = state->in,
 712         };
 713         const struct in6_addr *nexthop;
 714         struct flow_offload *flow;
 715         struct net_device *outdev;
 716         struct rt6_info *rt;
 717         int ret;
 718
 719         tuplehash = nf_flow_offload_ipv6_lookup(&ctx, flow_table, skb);
 720         if (tuplehash == NULL)
 721                 return NF_ACCEPT;
 722
 723         ret = nf_flow_offload_ipv6_forward(&ctx, flow_table, tuplehash, skb);
 724         if (ret < 0)
 725                 return NF_DROP;
 726         else if (ret == 0)
 727                 return NF_ACCEPT;
 728
 729         if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 730                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 731                 memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 732                 IP6CB(skb)->iif = skb->dev->ifindex;
 733                 IP6CB(skb)->flags = IP6SKB_FORWARDED;
 734                 return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 735         }
 736
 737         dir = tuplehash->tuple.dir;
 738         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 739
 740         switch (tuplehash->tuple.xmit_type) {
 741         case FLOW_OFFLOAD_XMIT_NEIGH:
 742                 rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
 743                 outdev = rt->dst.dev;
 744                 skb->dev = outdev;
 745                 nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
 746                 skb_dst_set_noref(skb, &rt->dst);
 747                 neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
 748                 ret = NF_STOLEN;
 749                 break;
 750         case FLOW_OFFLOAD_XMIT_DIRECT:
 751                 ret = nf_flow_queue_xmit(state->net, skb, tuplehash, ETH_P_IPV6);
 752                 if (ret == NF_DROP)
 753                         flow_offload_teardown(flow);
 754                 break;
 755         default:
 756                 WARN_ON_ONCE(1);
 757                 ret = NF_DROP;
 758                 break;
 759         }
 760
 761         return ret;
 762 }
 763 EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);