net/netfilter/nf_synproxy_core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/skbuff.h>
   8 #include <asm/unaligned.h>
   9 #include <net/tcp.h>
  10 #include <net/netns/generic.h>
  11 #include <linux/proc_fs.h>
  12
  13 #include <linux/netfilter_ipv6.h>
  14 #include <linux/netfilter/nf_synproxy.h>
  15
  16 #include <net/netfilter/nf_conntrack.h>
  17 #include <net/netfilter/nf_conntrack_ecache.h>
  18 #include <net/netfilter/nf_conntrack_extend.h>
  19 #include <net/netfilter/nf_conntrack_seqadj.h>
  20 #include <net/netfilter/nf_conntrack_synproxy.h>
  21 #include <net/netfilter/nf_conntrack_zones.h>
  22 #include <net/netfilter/nf_synproxy.h>
  23
  24 unsigned int synproxy_net_id;
  25 EXPORT_SYMBOL_GPL(synproxy_net_id);
  26
  27 bool
  28 synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
  29                        const struct tcphdr *th, struct synproxy_options *opts)
  30 {
  31         int length = (th->doff * 4) - sizeof(*th);
  32         u8 buf[40], *ptr;
  33
  34         if (unlikely(length < 0))
  35                 return false;
  36
  37         ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
  38         if (ptr == NULL)
  39                 return false;
  40
  41         opts->options = 0;
  42         while (length > 0) {
  43                 int opcode = *ptr++;
  44                 int opsize;
  45
  46                 switch (opcode) {
  47                 case TCPOPT_EOL:
  48                         return true;
  49                 case TCPOPT_NOP:
  50                         length--;
  51                         continue;
  52                 default:
  53                         if (length < 2)
  54                                 return true;
  55                         opsize = *ptr++;
  56                         if (opsize < 2)
  57                                 return true;
  58                         if (opsize > length)
  59                                 return true;
  60
  61                         switch (opcode) {
  62                         case TCPOPT_MSS:
  63                                 if (opsize == TCPOLEN_MSS) {
  64                                         opts->mss_option = get_unaligned_be16(ptr);
  65                                         opts->options |= NF_SYNPROXY_OPT_MSS;
  66                                 }
  67                                 break;
  68                         case TCPOPT_WINDOW:
  69                                 if (opsize == TCPOLEN_WINDOW) {
  70                                         opts->wscale = *ptr;
  71                                         if (opts->wscale > TCP_MAX_WSCALE)
  72                                                 opts->wscale = TCP_MAX_WSCALE;
  73                                         opts->options |= NF_SYNPROXY_OPT_WSCALE;
  74                                 }
  75                                 break;
  76                         case TCPOPT_TIMESTAMP:
  77                                 if (opsize == TCPOLEN_TIMESTAMP) {
  78                                         opts->tsval = get_unaligned_be32(ptr);
  79                                         opts->tsecr = get_unaligned_be32(ptr + 4);
  80                                         opts->options |= NF_SYNPROXY_OPT_TIMESTAMP;
  81                                 }
  82                                 break;
  83                         case TCPOPT_SACK_PERM:
  84                                 if (opsize == TCPOLEN_SACK_PERM)
  85                                         opts->options |= NF_SYNPROXY_OPT_SACK_PERM;
  86                                 break;
  87                         }
  88
  89                         ptr += opsize - 2;
  90                         length -= opsize;
  91                 }
  92         }
  93         return true;
  94 }
  95 EXPORT_SYMBOL_GPL(synproxy_parse_options);
  96
  97 static unsigned int
  98 synproxy_options_size(const struct synproxy_options *opts)
  99 {
 100         unsigned int size = 0;
 101
 102         if (opts->options & NF_SYNPROXY_OPT_MSS)
 103                 size += TCPOLEN_MSS_ALIGNED;
 104         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
 105                 size += TCPOLEN_TSTAMP_ALIGNED;
 106         else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
 107                 size += TCPOLEN_SACKPERM_ALIGNED;
 108         if (opts->options & NF_SYNPROXY_OPT_WSCALE)
 109                 size += TCPOLEN_WSCALE_ALIGNED;
 110
 111         return size;
 112 }
 113
 114 static void
 115 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
 116 {
 117         __be32 *ptr = (__be32 *)(th + 1);
 118         u8 options = opts->options;
 119
 120         if (options & NF_SYNPROXY_OPT_MSS)
 121                 *ptr++ = htonl((TCPOPT_MSS << 24) |
 122                                (TCPOLEN_MSS << 16) |
 123                                opts->mss_option);
 124
 125         if (options & NF_SYNPROXY_OPT_TIMESTAMP) {
 126                 if (options & NF_SYNPROXY_OPT_SACK_PERM)
 127                         *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
 128                                        (TCPOLEN_SACK_PERM << 16) |
 129                                        (TCPOPT_TIMESTAMP << 8) |
 130                                        TCPOLEN_TIMESTAMP);
 131                 else
 132                         *ptr++ = htonl((TCPOPT_NOP << 24) |
 133                                        (TCPOPT_NOP << 16) |
 134                                        (TCPOPT_TIMESTAMP << 8) |
 135                                        TCPOLEN_TIMESTAMP);
 136
 137                 *ptr++ = htonl(opts->tsval);
 138                 *ptr++ = htonl(opts->tsecr);
 139         } else if (options & NF_SYNPROXY_OPT_SACK_PERM)
 140                 *ptr++ = htonl((TCPOPT_NOP << 24) |
 141                                (TCPOPT_NOP << 16) |
 142                                (TCPOPT_SACK_PERM << 8) |
 143                                TCPOLEN_SACK_PERM);
 144
 145         if (options & NF_SYNPROXY_OPT_WSCALE)
 146                 *ptr++ = htonl((TCPOPT_NOP << 24) |
 147                                (TCPOPT_WINDOW << 16) |
 148                                (TCPOLEN_WINDOW << 8) |
 149                                opts->wscale);
 150 }
 151
 152 void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
 153                                     struct synproxy_options *opts)
 154 {
 155         opts->tsecr = opts->tsval;
 156         opts->tsval = tcp_time_stamp_raw() & ~0x3f;
 157
 158         if (opts->options & NF_SYNPROXY_OPT_WSCALE) {
 159                 opts->tsval |= opts->wscale;
 160                 opts->wscale = info->wscale;
 161         } else
 162                 opts->tsval |= 0xf;
 163
 164         if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
 165                 opts->tsval |= 1 << 4;
 166
 167         if (opts->options & NF_SYNPROXY_OPT_ECN)
 168                 opts->tsval |= 1 << 5;
 169 }
 170 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
 171
 172 static void
 173 synproxy_check_timestamp_cookie(struct synproxy_options *opts)
 174 {
 175         opts->wscale = opts->tsecr & 0xf;
 176         if (opts->wscale != 0xf)
 177                 opts->options |= NF_SYNPROXY_OPT_WSCALE;
 178
 179         opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0;
 180
 181         opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0;
 182 }
 183
 184 static unsigned int
 185 synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
 186                        struct tcphdr *th, struct nf_conn *ct,
 187                        enum ip_conntrack_info ctinfo,
 188                        const struct nf_conn_synproxy *synproxy)
 189 {
 190         unsigned int optoff, optend;
 191         __be32 *ptr, old;
 192
 193         if (synproxy->tsoff == 0)
 194                 return 1;
 195
 196         optoff = protoff + sizeof(struct tcphdr);
 197         optend = protoff + th->doff * 4;
 198
 199         if (skb_ensure_writable(skb, optend))
 200                 return 0;
 201
 202         while (optoff < optend) {
 203                 unsigned char *op = skb->data + optoff;
 204
 205                 switch (op[0]) {
 206                 case TCPOPT_EOL:
 207                         return 1;
 208                 case TCPOPT_NOP:
 209                         optoff++;
 210                         continue;
 211                 default:
 212                         if (optoff + 1 == optend ||
 213                             optoff + op[1] > optend ||
 214                             op[1] < 2)
 215                                 return 0;
 216                         if (op[0] == TCPOPT_TIMESTAMP &&
 217                             op[1] == TCPOLEN_TIMESTAMP) {
 218                                 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 219                                         ptr = (__be32 *)&op[2];
 220                                         old = *ptr;
 221                                         *ptr = htonl(ntohl(*ptr) -
 222                                                      synproxy->tsoff);
 223                                 } else {
 224                                         ptr = (__be32 *)&op[6];
 225                                         old = *ptr;
 226                                         *ptr = htonl(ntohl(*ptr) +
 227                                                      synproxy->tsoff);
 228                                 }
 229                                 inet_proto_csum_replace4(&th->check, skb,
 230                                                          old, *ptr, false);
 231                                 return 1;
 232                         }
 233                         optoff += op[1];
 234                 }
 235         }
 236         return 1;
 237 }
 238
 239 #ifdef CONFIG_PROC_FS
 240 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 241 {
 242         struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
 243         int cpu;
 244
 245         if (*pos == 0)
 246                 return SEQ_START_TOKEN;
 247
 248         for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
 249                 if (!cpu_possible(cpu))
 250                         continue;
 251                 *pos = cpu + 1;
 252                 return per_cpu_ptr(snet->stats, cpu);
 253         }
 254
 255         return NULL;
 256 }
 257
 258 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 259 {
 260         struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
 261         int cpu;
 262
 263         for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
 264                 if (!cpu_possible(cpu))
 265                         continue;
 266                 *pos = cpu + 1;
 267                 return per_cpu_ptr(snet->stats, cpu);
 268         }
 269         (*pos)++;
 270         return NULL;
 271 }
 272
 273 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
 274 {
 275         return;
 276 }
 277
 278 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
 279 {
 280         struct synproxy_stats *stats = v;
 281
 282         if (v == SEQ_START_TOKEN) {
 283                 seq_puts(seq, "entries\t\tsyn_received\t"
 284                               "cookie_invalid\tcookie_valid\t"
 285                               "cookie_retrans\tconn_reopened\n");
 286                 return 0;
 287         }
 288
 289         seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
 290                    stats->syn_received,
 291                    stats->cookie_invalid,
 292                    stats->cookie_valid,
 293                    stats->cookie_retrans,
 294                    stats->conn_reopened);
 295
 296         return 0;
 297 }
 298
 299 static const struct seq_operations synproxy_cpu_seq_ops = {
 300         .start          = synproxy_cpu_seq_start,
 301         .next           = synproxy_cpu_seq_next,
 302         .stop           = synproxy_cpu_seq_stop,
 303         .show           = synproxy_cpu_seq_show,
 304 };
 305
 306 static int __net_init synproxy_proc_init(struct net *net)
 307 {
 308         if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
 309                         &synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
 310                 return -ENOMEM;
 311         return 0;
 312 }
 313
 314 static void __net_exit synproxy_proc_exit(struct net *net)
 315 {
 316         remove_proc_entry("synproxy", net->proc_net_stat);
 317 }
 318 #else
 319 static int __net_init synproxy_proc_init(struct net *net)
 320 {
 321         return 0;
 322 }
 323
 324 static void __net_exit synproxy_proc_exit(struct net *net)
 325 {
 326         return;
 327 }
 328 #endif /* CONFIG_PROC_FS */
 329
 330 static int __net_init synproxy_net_init(struct net *net)
 331 {
 332         struct synproxy_net *snet = synproxy_pernet(net);
 333         struct nf_conn *ct;
 334         int err = -ENOMEM;
 335
 336         ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
 337         if (!ct)
 338                 goto err1;
 339
 340         if (!nfct_seqadj_ext_add(ct))
 341                 goto err2;
 342         if (!nfct_synproxy_ext_add(ct))
 343                 goto err2;
 344
 345         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 346         snet->tmpl = ct;
 347
 348         snet->stats = alloc_percpu(struct synproxy_stats);
 349         if (snet->stats == NULL)
 350                 goto err2;
 351
 352         err = synproxy_proc_init(net);
 353         if (err < 0)
 354                 goto err3;
 355
 356         return 0;
 357
 358 err3:
 359         free_percpu(snet->stats);
 360 err2:
 361         nf_ct_tmpl_free(ct);
 362 err1:
 363         return err;
 364 }
 365
 366 static void __net_exit synproxy_net_exit(struct net *net)
 367 {
 368         struct synproxy_net *snet = synproxy_pernet(net);
 369
 370         nf_ct_put(snet->tmpl);
 371         synproxy_proc_exit(net);
 372         free_percpu(snet->stats);
 373 }
 374
 375 static struct pernet_operations synproxy_net_ops = {
 376         .init           = synproxy_net_init,
 377         .exit           = synproxy_net_exit,
 378         .id             = &synproxy_net_id,
 379         .size           = sizeof(struct synproxy_net),
 380 };
 381
 382 static int __init synproxy_core_init(void)
 383 {
 384         return register_pernet_subsys(&synproxy_net_ops);
 385 }
 386
 387 static void __exit synproxy_core_exit(void)
 388 {
 389         unregister_pernet_subsys(&synproxy_net_ops);
 390 }
 391
 392 module_init(synproxy_core_init);
 393 module_exit(synproxy_core_exit);
 394
 395 static struct iphdr *
 396 synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
 397                   __be32 daddr)
 398 {
 399         struct iphdr *iph;
 400
 401         skb_reset_network_header(skb);
 402         iph = skb_put(skb, sizeof(*iph));
 403         iph->version    = 4;
 404         iph->ihl        = sizeof(*iph) / 4;
 405         iph->tos        = 0;
 406         iph->id         = 0;
 407         iph->frag_off   = htons(IP_DF);
 408         iph->ttl        = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
 409         iph->protocol   = IPPROTO_TCP;
 410         iph->check      = 0;
 411         iph->saddr      = saddr;
 412         iph->daddr      = daddr;
 413
 414         return iph;
 415 }
 416
 417 static void
 418 synproxy_send_tcp(struct net *net,
 419                   const struct sk_buff *skb, struct sk_buff *nskb,
 420                   struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 421                   struct iphdr *niph, struct tcphdr *nth,
 422                   unsigned int tcp_hdr_size)
 423 {
 424         nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0);
 425         nskb->ip_summed   = CHECKSUM_PARTIAL;
 426         nskb->csum_start  = (unsigned char *)nth - nskb->head;
 427         nskb->csum_offset = offsetof(struct tcphdr, check);
 428
 429         skb_dst_set_noref(nskb, skb_dst(skb));
 430         nskb->protocol = htons(ETH_P_IP);
 431         if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC))
 432                 goto free_nskb;
 433
 434         if (nfct) {
 435                 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 436                 nf_conntrack_get(nfct);
 437         }
 438
 439         ip_local_out(net, nskb->sk, nskb);
 440         return;
 441
 442 free_nskb:
 443         kfree_skb(nskb);
 444 }
 445
 446 void
 447 synproxy_send_client_synack(struct net *net,
 448                             const struct sk_buff *skb, const struct tcphdr *th,
 449                             const struct synproxy_options *opts)
 450 {
 451         struct sk_buff *nskb;
 452         struct iphdr *iph, *niph;
 453         struct tcphdr *nth;
 454         unsigned int tcp_hdr_size;
 455         u16 mss = opts->mss_encode;
 456
 457         iph = ip_hdr(skb);
 458
 459         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 460         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 461                          GFP_ATOMIC);
 462         if (!nskb)
 463                 return;
 464         skb_reserve(nskb, MAX_TCP_HEADER);
 465
 466         niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
 467
 468         skb_reset_transport_header(nskb);
 469         nth = skb_put(nskb, tcp_hdr_size);
 470         nth->source     = th->dest;
 471         nth->dest       = th->source;
 472         nth->seq        = htonl(__cookie_v4_init_sequence(iph, th, &mss));
 473         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 474         tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 475         if (opts->options & NF_SYNPROXY_OPT_ECN)
 476                 tcp_flag_word(nth) |= TCP_FLAG_ECE;
 477         nth->doff       = tcp_hdr_size / 4;
 478         nth->window     = 0;
 479         nth->check      = 0;
 480         nth->urg_ptr    = 0;
 481
 482         synproxy_build_options(nth, opts);
 483
 484         synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
 485                           IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
 486 }
 487 EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
 488
 489 static void
 490 synproxy_send_server_syn(struct net *net,
 491                          const struct sk_buff *skb, const struct tcphdr *th,
 492                          const struct synproxy_options *opts, u32 recv_seq)
 493 {
 494         struct synproxy_net *snet = synproxy_pernet(net);
 495         struct sk_buff *nskb;
 496         struct iphdr *iph, *niph;
 497         struct tcphdr *nth;
 498         unsigned int tcp_hdr_size;
 499
 500         iph = ip_hdr(skb);
 501
 502         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 503         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 504                          GFP_ATOMIC);
 505         if (!nskb)
 506                 return;
 507         skb_reserve(nskb, MAX_TCP_HEADER);
 508
 509         niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
 510
 511         skb_reset_transport_header(nskb);
 512         nth = skb_put(nskb, tcp_hdr_size);
 513         nth->source     = th->source;
 514         nth->dest       = th->dest;
 515         nth->seq        = htonl(recv_seq - 1);
 516         /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 517          * sequence number translation once a connection tracking entry exists.
 518          */
 519         nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 520         tcp_flag_word(nth) = TCP_FLAG_SYN;
 521         if (opts->options & NF_SYNPROXY_OPT_ECN)
 522                 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 523         nth->doff       = tcp_hdr_size / 4;
 524         nth->window     = th->window;
 525         nth->check      = 0;
 526         nth->urg_ptr    = 0;
 527
 528         synproxy_build_options(nth, opts);
 529
 530         synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
 531                           niph, nth, tcp_hdr_size);
 532 }
 533
 534 static void
 535 synproxy_send_server_ack(struct net *net,
 536                          const struct ip_ct_tcp *state,
 537                          const struct sk_buff *skb, const struct tcphdr *th,
 538                          const struct synproxy_options *opts)
 539 {
 540         struct sk_buff *nskb;
 541         struct iphdr *iph, *niph;
 542         struct tcphdr *nth;
 543         unsigned int tcp_hdr_size;
 544
 545         iph = ip_hdr(skb);
 546
 547         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 548         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 549                          GFP_ATOMIC);
 550         if (!nskb)
 551                 return;
 552         skb_reserve(nskb, MAX_TCP_HEADER);
 553
 554         niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
 555
 556         skb_reset_transport_header(nskb);
 557         nth = skb_put(nskb, tcp_hdr_size);
 558         nth->source     = th->dest;
 559         nth->dest       = th->source;
 560         nth->seq        = htonl(ntohl(th->ack_seq));
 561         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 562         tcp_flag_word(nth) = TCP_FLAG_ACK;
 563         nth->doff       = tcp_hdr_size / 4;
 564         nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
 565         nth->check      = 0;
 566         nth->urg_ptr    = 0;
 567
 568         synproxy_build_options(nth, opts);
 569
 570         synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
 571 }
 572
 573 static void
 574 synproxy_send_client_ack(struct net *net,
 575                          const struct sk_buff *skb, const struct tcphdr *th,
 576                          const struct synproxy_options *opts)
 577 {
 578         struct sk_buff *nskb;
 579         struct iphdr *iph, *niph;
 580         struct tcphdr *nth;
 581         unsigned int tcp_hdr_size;
 582
 583         iph = ip_hdr(skb);
 584
 585         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 586         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 587                          GFP_ATOMIC);
 588         if (!nskb)
 589                 return;
 590         skb_reserve(nskb, MAX_TCP_HEADER);
 591
 592         niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
 593
 594         skb_reset_transport_header(nskb);
 595         nth = skb_put(nskb, tcp_hdr_size);
 596         nth->source     = th->source;
 597         nth->dest       = th->dest;
 598         nth->seq        = htonl(ntohl(th->seq) + 1);
 599         nth->ack_seq    = th->ack_seq;
 600         tcp_flag_word(nth) = TCP_FLAG_ACK;
 601         nth->doff       = tcp_hdr_size / 4;
 602         nth->window     = htons(ntohs(th->window) >> opts->wscale);
 603         nth->check      = 0;
 604         nth->urg_ptr    = 0;
 605
 606         synproxy_build_options(nth, opts);
 607
 608         synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
 609                           IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
 610 }
 611
 612 bool
 613 synproxy_recv_client_ack(struct net *net,
 614                          const struct sk_buff *skb, const struct tcphdr *th,
 615                          struct synproxy_options *opts, u32 recv_seq)
 616 {
 617         struct synproxy_net *snet = synproxy_pernet(net);
 618         int mss;
 619
 620         mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1);
 621         if (mss == 0) {
 622                 this_cpu_inc(snet->stats->cookie_invalid);
 623                 return false;
 624         }
 625
 626         this_cpu_inc(snet->stats->cookie_valid);
 627         opts->mss_option = mss;
 628         opts->options |= NF_SYNPROXY_OPT_MSS;
 629
 630         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
 631                 synproxy_check_timestamp_cookie(opts);
 632
 633         synproxy_send_server_syn(net, skb, th, opts, recv_seq);
 634         return true;
 635 }
 636 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
 637
 638 unsigned int
 639 ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
 640                    const struct nf_hook_state *nhs)
 641 {
 642         struct net *net = nhs->net;
 643         struct synproxy_net *snet = synproxy_pernet(net);
 644         enum ip_conntrack_info ctinfo;
 645         struct nf_conn *ct;
 646         struct nf_conn_synproxy *synproxy;
 647         struct synproxy_options opts = {};
 648         const struct ip_ct_tcp *state;
 649         struct tcphdr *th, _th;
 650         unsigned int thoff;
 651
 652         ct = nf_ct_get(skb, &ctinfo);
 653         if (!ct)
 654                 return NF_ACCEPT;
 655
 656         synproxy = nfct_synproxy(ct);
 657         if (!synproxy)
 658                 return NF_ACCEPT;
 659
 660         if (nf_is_loopback_packet(skb) ||
 661             ip_hdr(skb)->protocol != IPPROTO_TCP)
 662                 return NF_ACCEPT;
 663
 664         thoff = ip_hdrlen(skb);
 665         th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
 666         if (!th)
 667                 return NF_DROP;
 668
 669         state = &ct->proto.tcp;
 670         switch (state->state) {
 671         case TCP_CONNTRACK_CLOSE:
 672                 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
 673                         nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
 674                                                       ntohl(th->seq) + 1);
 675                         break;
 676                 }
 677
 678                 if (!th->syn || th->ack ||
 679                     CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
 680                         break;
 681
 682                 /* Reopened connection - reset the sequence number and timestamp
 683                  * adjustments, they will get initialized once the connection is
 684                  * reestablished.
 685                  */
 686                 nf_ct_seqadj_init(ct, ctinfo, 0);
 687                 synproxy->tsoff = 0;
 688                 this_cpu_inc(snet->stats->conn_reopened);
 689                 fallthrough;
 690         case TCP_CONNTRACK_SYN_SENT:
 691                 if (!synproxy_parse_options(skb, thoff, th, &opts))
 692                         return NF_DROP;
 693
 694                 if (!th->syn && th->ack &&
 695                     CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
 696                         /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
 697                          * therefore we need to add 1 to make the SYN sequence
 698                          * number match the one of first SYN.
 699                          */
 700                         if (synproxy_recv_client_ack(net, skb, th, &opts,
 701                                                      ntohl(th->seq) + 1)) {
 702                                 this_cpu_inc(snet->stats->cookie_retrans);
 703                                 consume_skb(skb);
 704                                 return NF_STOLEN;
 705                         } else {
 706                                 return NF_DROP;
 707                         }
 708                 }
 709
 710                 synproxy->isn = ntohl(th->ack_seq);
 711                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
 712                         synproxy->its = opts.tsecr;
 713
 714                 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 715                 break;
 716         case TCP_CONNTRACK_SYN_RECV:
 717                 if (!th->syn || !th->ack)
 718                         break;
 719
 720                 if (!synproxy_parse_options(skb, thoff, th, &opts))
 721                         return NF_DROP;
 722
 723                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
 724                         synproxy->tsoff = opts.tsval - synproxy->its;
 725                         nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 726                 }
 727
 728                 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
 729                                   NF_SYNPROXY_OPT_WSCALE |
 730                                   NF_SYNPROXY_OPT_SACK_PERM);
 731
 732                 swap(opts.tsval, opts.tsecr);
 733                 synproxy_send_server_ack(net, state, skb, th, &opts);
 734
 735                 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
 736                 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
 737
 738                 swap(opts.tsval, opts.tsecr);
 739                 synproxy_send_client_ack(net, skb, th, &opts);
 740
 741                 consume_skb(skb);
 742                 return NF_STOLEN;
 743         default:
 744                 break;
 745         }
 746
 747         synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
 748         return NF_ACCEPT;
 749 }
 750 EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
 751
 752 static const struct nf_hook_ops ipv4_synproxy_ops[] = {
 753         {
 754                 .hook           = ipv4_synproxy_hook,
 755                 .pf             = NFPROTO_IPV4,
 756                 .hooknum        = NF_INET_LOCAL_IN,
 757                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 758         },
 759         {
 760                 .hook           = ipv4_synproxy_hook,
 761                 .pf             = NFPROTO_IPV4,
 762                 .hooknum        = NF_INET_POST_ROUTING,
 763                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 764         },
 765 };
 766
 767 int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
 768 {
 769         int err;
 770
 771         if (snet->hook_ref4 == 0) {
 772                 err = nf_register_net_hooks(net, ipv4_synproxy_ops,
 773                                             ARRAY_SIZE(ipv4_synproxy_ops));
 774                 if (err)
 775                         return err;
 776         }
 777
 778         snet->hook_ref4++;
 779         return 0;
 780 }
 781 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
 782
 783 void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
 784 {
 785         snet->hook_ref4--;
 786         if (snet->hook_ref4 == 0)
 787                 nf_unregister_net_hooks(net, ipv4_synproxy_ops,
 788                                         ARRAY_SIZE(ipv4_synproxy_ops));
 789 }
 790 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
 791
 792 #if IS_ENABLED(CONFIG_IPV6)
 793 static struct ipv6hdr *
 794 synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
 795                        const struct in6_addr *saddr,
 796                        const struct in6_addr *daddr)
 797 {
 798         struct ipv6hdr *iph;
 799
 800         skb_reset_network_header(skb);
 801         iph = skb_put(skb, sizeof(*iph));
 802         ip6_flow_hdr(iph, 0, 0);
 803         iph->hop_limit  = net->ipv6.devconf_all->hop_limit;
 804         iph->nexthdr    = IPPROTO_TCP;
 805         iph->saddr      = *saddr;
 806         iph->daddr      = *daddr;
 807
 808         return iph;
 809 }
 810
 811 static void
 812 synproxy_send_tcp_ipv6(struct net *net,
 813                        const struct sk_buff *skb, struct sk_buff *nskb,
 814                        struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 815                        struct ipv6hdr *niph, struct tcphdr *nth,
 816                        unsigned int tcp_hdr_size)
 817 {
 818         struct dst_entry *dst;
 819         struct flowi6 fl6;
 820         int err;
 821
 822         nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
 823         nskb->ip_summed   = CHECKSUM_PARTIAL;
 824         nskb->csum_start  = (unsigned char *)nth - nskb->head;
 825         nskb->csum_offset = offsetof(struct tcphdr, check);
 826
 827         memset(&fl6, 0, sizeof(fl6));
 828         fl6.flowi6_proto = IPPROTO_TCP;
 829         fl6.saddr = niph->saddr;
 830         fl6.daddr = niph->daddr;
 831         fl6.fl6_sport = nth->source;
 832         fl6.fl6_dport = nth->dest;
 833         security_skb_classify_flow((struct sk_buff *)skb,
 834                                    flowi6_to_flowi_common(&fl6));
 835         err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
 836         if (err) {
 837                 goto free_nskb;
 838         }
 839
 840         dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
 841         if (IS_ERR(dst))
 842                 goto free_nskb;
 843
 844         skb_dst_set(nskb, dst);
 845
 846         if (nfct) {
 847                 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 848                 nf_conntrack_get(nfct);
 849         }
 850
 851         ip6_local_out(net, nskb->sk, nskb);
 852         return;
 853
 854 free_nskb:
 855         kfree_skb(nskb);
 856 }
 857
 858 void
 859 synproxy_send_client_synack_ipv6(struct net *net,
 860                                  const struct sk_buff *skb,
 861                                  const struct tcphdr *th,
 862                                  const struct synproxy_options *opts)
 863 {
 864         struct sk_buff *nskb;
 865         struct ipv6hdr *iph, *niph;
 866         struct tcphdr *nth;
 867         unsigned int tcp_hdr_size;
 868         u16 mss = opts->mss_encode;
 869
 870         iph = ipv6_hdr(skb);
 871
 872         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 873         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 874                          GFP_ATOMIC);
 875         if (!nskb)
 876                 return;
 877         skb_reserve(nskb, MAX_TCP_HEADER);
 878
 879         niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 880
 881         skb_reset_transport_header(nskb);
 882         nth = skb_put(nskb, tcp_hdr_size);
 883         nth->source     = th->dest;
 884         nth->dest       = th->source;
 885         nth->seq        = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss));
 886         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 887         tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 888         if (opts->options & NF_SYNPROXY_OPT_ECN)
 889                 tcp_flag_word(nth) |= TCP_FLAG_ECE;
 890         nth->doff       = tcp_hdr_size / 4;
 891         nth->window     = 0;
 892         nth->check      = 0;
 893         nth->urg_ptr    = 0;
 894
 895         synproxy_build_options(nth, opts);
 896
 897         synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
 898                                IP_CT_ESTABLISHED_REPLY, niph, nth,
 899                                tcp_hdr_size);
 900 }
 901 EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
 902
 903 static void
 904 synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb,
 905                               const struct tcphdr *th,
 906                               const struct synproxy_options *opts, u32 recv_seq)
 907 {
 908         struct synproxy_net *snet = synproxy_pernet(net);
 909         struct sk_buff *nskb;
 910         struct ipv6hdr *iph, *niph;
 911         struct tcphdr *nth;
 912         unsigned int tcp_hdr_size;
 913
 914         iph = ipv6_hdr(skb);
 915
 916         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 917         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 918                          GFP_ATOMIC);
 919         if (!nskb)
 920                 return;
 921         skb_reserve(nskb, MAX_TCP_HEADER);
 922
 923         niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
 924
 925         skb_reset_transport_header(nskb);
 926         nth = skb_put(nskb, tcp_hdr_size);
 927         nth->source     = th->source;
 928         nth->dest       = th->dest;
 929         nth->seq        = htonl(recv_seq - 1);
 930         /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 931          * sequence number translation once a connection tracking entry exists.
 932          */
 933         nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 934         tcp_flag_word(nth) = TCP_FLAG_SYN;
 935         if (opts->options & NF_SYNPROXY_OPT_ECN)
 936                 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 937         nth->doff       = tcp_hdr_size / 4;
 938         nth->window     = th->window;
 939         nth->check      = 0;
 940         nth->urg_ptr    = 0;
 941
 942         synproxy_build_options(nth, opts);
 943
 944         synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
 945                                IP_CT_NEW, niph, nth, tcp_hdr_size);
 946 }
 947
 948 static void
 949 synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state,
 950                               const struct sk_buff *skb,
 951                               const struct tcphdr *th,
 952                               const struct synproxy_options *opts)
 953 {
 954         struct sk_buff *nskb;
 955         struct ipv6hdr *iph, *niph;
 956         struct tcphdr *nth;
 957         unsigned int tcp_hdr_size;
 958
 959         iph = ipv6_hdr(skb);
 960
 961         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 962         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 963                          GFP_ATOMIC);
 964         if (!nskb)
 965                 return;
 966         skb_reserve(nskb, MAX_TCP_HEADER);
 967
 968         niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 969
 970         skb_reset_transport_header(nskb);
 971         nth = skb_put(nskb, tcp_hdr_size);
 972         nth->source     = th->dest;
 973         nth->dest       = th->source;
 974         nth->seq        = htonl(ntohl(th->ack_seq));
 975         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 976         tcp_flag_word(nth) = TCP_FLAG_ACK;
 977         nth->doff       = tcp_hdr_size / 4;
 978         nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
 979         nth->check      = 0;
 980         nth->urg_ptr    = 0;
 981
 982         synproxy_build_options(nth, opts);
 983
 984         synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth,
 985                                tcp_hdr_size);
 986 }
 987
 988 static void
 989 synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
 990                               const struct tcphdr *th,
 991                               const struct synproxy_options *opts)
 992 {
 993         struct sk_buff *nskb;
 994         struct ipv6hdr *iph, *niph;
 995         struct tcphdr *nth;
 996         unsigned int tcp_hdr_size;
 997
 998         iph = ipv6_hdr(skb);
 999
1000         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
1001         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
1002                          GFP_ATOMIC);
1003         if (!nskb)
1004                 return;
1005         skb_reserve(nskb, MAX_TCP_HEADER);
1006
1007         niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
1008
1009         skb_reset_transport_header(nskb);
1010         nth = skb_put(nskb, tcp_hdr_size);
1011         nth->source     = th->source;
1012         nth->dest       = th->dest;
1013         nth->seq        = htonl(ntohl(th->seq) + 1);
1014         nth->ack_seq    = th->ack_seq;
1015         tcp_flag_word(nth) = TCP_FLAG_ACK;
1016         nth->doff       = tcp_hdr_size / 4;
1017         nth->window     = htons(ntohs(th->window) >> opts->wscale);
1018         nth->check      = 0;
1019         nth->urg_ptr    = 0;
1020
1021         synproxy_build_options(nth, opts);
1022
1023         synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
1024                                IP_CT_ESTABLISHED_REPLY, niph, nth,
1025                                tcp_hdr_size);
1026 }
1027
1028 bool
1029 synproxy_recv_client_ack_ipv6(struct net *net,
1030                               const struct sk_buff *skb,
1031                               const struct tcphdr *th,
1032                               struct synproxy_options *opts, u32 recv_seq)
1033 {
1034         struct synproxy_net *snet = synproxy_pernet(net);
1035         int mss;
1036
1037         mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
1038         if (mss == 0) {
1039                 this_cpu_inc(snet->stats->cookie_invalid);
1040                 return false;
1041         }
1042
1043         this_cpu_inc(snet->stats->cookie_valid);
1044         opts->mss_option = mss;
1045         opts->options |= NF_SYNPROXY_OPT_MSS;
1046
1047         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
1048                 synproxy_check_timestamp_cookie(opts);
1049
1050         synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
1051         return true;
1052 }
1053 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
1054
1055 unsigned int
1056 ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
1057                    const struct nf_hook_state *nhs)
1058 {
1059         struct net *net = nhs->net;
1060         struct synproxy_net *snet = synproxy_pernet(net);
1061         enum ip_conntrack_info ctinfo;
1062         struct nf_conn *ct;
1063         struct nf_conn_synproxy *synproxy;
1064         struct synproxy_options opts = {};
1065         const struct ip_ct_tcp *state;
1066         struct tcphdr *th, _th;
1067         __be16 frag_off;
1068         u8 nexthdr;
1069         int thoff;
1070
1071         ct = nf_ct_get(skb, &ctinfo);
1072         if (!ct)
1073                 return NF_ACCEPT;
1074
1075         synproxy = nfct_synproxy(ct);
1076         if (!synproxy)
1077                 return NF_ACCEPT;
1078
1079         if (nf_is_loopback_packet(skb))
1080                 return NF_ACCEPT;
1081
1082         nexthdr = ipv6_hdr(skb)->nexthdr;
1083         thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
1084                                  &frag_off);
1085         if (thoff < 0 || nexthdr != IPPROTO_TCP)
1086                 return NF_ACCEPT;
1087
1088         th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
1089         if (!th)
1090                 return NF_DROP;
1091
1092         state = &ct->proto.tcp;
1093         switch (state->state) {
1094         case TCP_CONNTRACK_CLOSE:
1095                 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
1096                         nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
1097                                                       ntohl(th->seq) + 1);
1098                         break;
1099                 }
1100
1101                 if (!th->syn || th->ack ||
1102                     CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
1103                         break;
1104
1105                 /* Reopened connection - reset the sequence number and timestamp
1106                  * adjustments, they will get initialized once the connection is
1107                  * reestablished.
1108                  */
1109                 nf_ct_seqadj_init(ct, ctinfo, 0);
1110                 synproxy->tsoff = 0;
1111                 this_cpu_inc(snet->stats->conn_reopened);
1112                 fallthrough;
1113         case TCP_CONNTRACK_SYN_SENT:
1114                 if (!synproxy_parse_options(skb, thoff, th, &opts))
1115                         return NF_DROP;
1116
1117                 if (!th->syn && th->ack &&
1118                     CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
1119                         /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
1120                          * therefore we need to add 1 to make the SYN sequence
1121                          * number match the one of first SYN.
1122                          */
1123                         if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
1124                                                           ntohl(th->seq) + 1)) {
1125                                 this_cpu_inc(snet->stats->cookie_retrans);
1126                                 consume_skb(skb);
1127                                 return NF_STOLEN;
1128                         } else {
1129                                 return NF_DROP;
1130                         }
1131                 }
1132
1133                 synproxy->isn = ntohl(th->ack_seq);
1134                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
1135                         synproxy->its = opts.tsecr;
1136
1137                 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1138                 break;
1139         case TCP_CONNTRACK_SYN_RECV:
1140                 if (!th->syn || !th->ack)
1141                         break;
1142
1143                 if (!synproxy_parse_options(skb, thoff, th, &opts))
1144                         return NF_DROP;
1145
1146                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
1147                         synproxy->tsoff = opts.tsval - synproxy->its;
1148                         nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1149                 }
1150
1151                 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
1152                                   NF_SYNPROXY_OPT_WSCALE |
1153                                   NF_SYNPROXY_OPT_SACK_PERM);
1154
1155                 swap(opts.tsval, opts.tsecr);
1156                 synproxy_send_server_ack_ipv6(net, state, skb, th, &opts);
1157
1158                 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
1159                 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
1160
1161                 swap(opts.tsval, opts.tsecr);
1162                 synproxy_send_client_ack_ipv6(net, skb, th, &opts);
1163
1164                 consume_skb(skb);
1165                 return NF_STOLEN;
1166         default:
1167                 break;
1168         }
1169
1170         synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
1171         return NF_ACCEPT;
1172 }
1173 EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
1174
1175 static const struct nf_hook_ops ipv6_synproxy_ops[] = {
1176         {
1177                 .hook           = ipv6_synproxy_hook,
1178                 .pf             = NFPROTO_IPV6,
1179                 .hooknum        = NF_INET_LOCAL_IN,
1180                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1181         },
1182         {
1183                 .hook           = ipv6_synproxy_hook,
1184                 .pf             = NFPROTO_IPV6,
1185                 .hooknum        = NF_INET_POST_ROUTING,
1186                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1187         },
1188 };
1189
1190 int
1191 nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
1192 {
1193         int err;
1194
1195         if (snet->hook_ref6 == 0) {
1196                 err = nf_register_net_hooks(net, ipv6_synproxy_ops,
1197                                             ARRAY_SIZE(ipv6_synproxy_ops));
1198                 if (err)
1199                         return err;
1200         }
1201
1202         snet->hook_ref6++;
1203         return 0;
1204 }
1205 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
1206
1207 void
1208 nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
1209 {
1210         snet->hook_ref6--;
1211         if (snet->hook_ref6 == 0)
1212                 nf_unregister_net_hooks(net, ipv6_synproxy_ops,
1213                                         ARRAY_SIZE(ipv6_synproxy_ops));
1214 }
1215 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
1216 #endif /* CONFIG_IPV6 */
1217
1218 MODULE_LICENSE("GPL");
1219 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
1220 MODULE_DESCRIPTION("nftables SYNPROXY expression support");