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         ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
  35         if (ptr == NULL)
  36                 return false;
  37
  38         opts->options = 0;
  39         while (length > 0) {
  40                 int opcode = *ptr++;
  41                 int opsize;
  42
  43                 switch (opcode) {
  44                 case TCPOPT_EOL:
  45                         return true;
  46                 case TCPOPT_NOP:
  47                         length--;
  48                         continue;
  49                 default:
  50                         opsize = *ptr++;
  51                         if (opsize < 2)
  52                                 return true;
  53                         if (opsize > length)
  54                                 return true;
  55
  56                         switch (opcode) {
  57                         case TCPOPT_MSS:
  58                                 if (opsize == TCPOLEN_MSS) {
  59                                         opts->mss_option = get_unaligned_be16(ptr);
  60                                         opts->options |= NF_SYNPROXY_OPT_MSS;
  61                                 }
  62                                 break;
  63                         case TCPOPT_WINDOW:
  64                                 if (opsize == TCPOLEN_WINDOW) {
  65                                         opts->wscale = *ptr;
  66                                         if (opts->wscale > TCP_MAX_WSCALE)
  67                                                 opts->wscale = TCP_MAX_WSCALE;
  68                                         opts->options |= NF_SYNPROXY_OPT_WSCALE;
  69                                 }
  70                                 break;
  71                         case TCPOPT_TIMESTAMP:
  72                                 if (opsize == TCPOLEN_TIMESTAMP) {
  73                                         opts->tsval = get_unaligned_be32(ptr);
  74                                         opts->tsecr = get_unaligned_be32(ptr + 4);
  75                                         opts->options |= NF_SYNPROXY_OPT_TIMESTAMP;
  76                                 }
  77                                 break;
  78                         case TCPOPT_SACK_PERM:
  79                                 if (opsize == TCPOLEN_SACK_PERM)
  80                                         opts->options |= NF_SYNPROXY_OPT_SACK_PERM;
  81                                 break;
  82                         }
  83
  84                         ptr += opsize - 2;
  85                         length -= opsize;
  86                 }
  87         }
  88         return true;
  89 }
  90 EXPORT_SYMBOL_GPL(synproxy_parse_options);
  91
  92 static unsigned int
  93 synproxy_options_size(const struct synproxy_options *opts)
  94 {
  95         unsigned int size = 0;
  96
  97         if (opts->options & NF_SYNPROXY_OPT_MSS)
  98                 size += TCPOLEN_MSS_ALIGNED;
  99         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
 100                 size += TCPOLEN_TSTAMP_ALIGNED;
 101         else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
 102                 size += TCPOLEN_SACKPERM_ALIGNED;
 103         if (opts->options & NF_SYNPROXY_OPT_WSCALE)
 104                 size += TCPOLEN_WSCALE_ALIGNED;
 105
 106         return size;
 107 }
 108
 109 static void
 110 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
 111 {
 112         __be32 *ptr = (__be32 *)(th + 1);
 113         u8 options = opts->options;
 114
 115         if (options & NF_SYNPROXY_OPT_MSS)
 116                 *ptr++ = htonl((TCPOPT_MSS << 24) |
 117                                (TCPOLEN_MSS << 16) |
 118                                opts->mss_option);
 119
 120         if (options & NF_SYNPROXY_OPT_TIMESTAMP) {
 121                 if (options & NF_SYNPROXY_OPT_SACK_PERM)
 122                         *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
 123                                        (TCPOLEN_SACK_PERM << 16) |
 124                                        (TCPOPT_TIMESTAMP << 8) |
 125                                        TCPOLEN_TIMESTAMP);
 126                 else
 127                         *ptr++ = htonl((TCPOPT_NOP << 24) |
 128                                        (TCPOPT_NOP << 16) |
 129                                        (TCPOPT_TIMESTAMP << 8) |
 130                                        TCPOLEN_TIMESTAMP);
 131
 132                 *ptr++ = htonl(opts->tsval);
 133                 *ptr++ = htonl(opts->tsecr);
 134         } else if (options & NF_SYNPROXY_OPT_SACK_PERM)
 135                 *ptr++ = htonl((TCPOPT_NOP << 24) |
 136                                (TCPOPT_NOP << 16) |
 137                                (TCPOPT_SACK_PERM << 8) |
 138                                TCPOLEN_SACK_PERM);
 139
 140         if (options & NF_SYNPROXY_OPT_WSCALE)
 141                 *ptr++ = htonl((TCPOPT_NOP << 24) |
 142                                (TCPOPT_WINDOW << 16) |
 143                                (TCPOLEN_WINDOW << 8) |
 144                                opts->wscale);
 145 }
 146
 147 void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
 148                                     struct synproxy_options *opts)
 149 {
 150         opts->tsecr = opts->tsval;
 151         opts->tsval = tcp_time_stamp_raw() & ~0x3f;
 152
 153         if (opts->options & NF_SYNPROXY_OPT_WSCALE) {
 154                 opts->tsval |= opts->wscale;
 155                 opts->wscale = info->wscale;
 156         } else
 157                 opts->tsval |= 0xf;
 158
 159         if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
 160                 opts->tsval |= 1 << 4;
 161
 162         if (opts->options & NF_SYNPROXY_OPT_ECN)
 163                 opts->tsval |= 1 << 5;
 164 }
 165 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
 166
 167 static void
 168 synproxy_check_timestamp_cookie(struct synproxy_options *opts)
 169 {
 170         opts->wscale = opts->tsecr & 0xf;
 171         if (opts->wscale != 0xf)
 172                 opts->options |= NF_SYNPROXY_OPT_WSCALE;
 173
 174         opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0;
 175
 176         opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0;
 177 }
 178
 179 static unsigned int
 180 synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
 181                        struct tcphdr *th, struct nf_conn *ct,
 182                        enum ip_conntrack_info ctinfo,
 183                        const struct nf_conn_synproxy *synproxy)
 184 {
 185         unsigned int optoff, optend;
 186         __be32 *ptr, old;
 187
 188         if (synproxy->tsoff == 0)
 189                 return 1;
 190
 191         optoff = protoff + sizeof(struct tcphdr);
 192         optend = protoff + th->doff * 4;
 193
 194         if (skb_ensure_writable(skb, optend))
 195                 return 0;
 196
 197         while (optoff < optend) {
 198                 unsigned char *op = skb->data + optoff;
 199
 200                 switch (op[0]) {
 201                 case TCPOPT_EOL:
 202                         return 1;
 203                 case TCPOPT_NOP:
 204                         optoff++;
 205                         continue;
 206                 default:
 207                         if (optoff + 1 == optend ||
 208                             optoff + op[1] > optend ||
 209                             op[1] < 2)
 210                                 return 0;
 211                         if (op[0] == TCPOPT_TIMESTAMP &&
 212                             op[1] == TCPOLEN_TIMESTAMP) {
 213                                 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 214                                         ptr = (__be32 *)&op[2];
 215                                         old = *ptr;
 216                                         *ptr = htonl(ntohl(*ptr) -
 217                                                      synproxy->tsoff);
 218                                 } else {
 219                                         ptr = (__be32 *)&op[6];
 220                                         old = *ptr;
 221                                         *ptr = htonl(ntohl(*ptr) +
 222                                                      synproxy->tsoff);
 223                                 }
 224                                 inet_proto_csum_replace4(&th->check, skb,
 225                                                          old, *ptr, false);
 226                                 return 1;
 227                         }
 228                         optoff += op[1];
 229                 }
 230         }
 231         return 1;
 232 }
 233
 234 static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = {
 235         .len            = sizeof(struct nf_conn_synproxy),
 236         .align          = __alignof__(struct nf_conn_synproxy),
 237         .id             = NF_CT_EXT_SYNPROXY,
 238 };
 239
 240 #ifdef CONFIG_PROC_FS
 241 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 242 {
 243         struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
 244         int cpu;
 245
 246         if (*pos == 0)
 247                 return SEQ_START_TOKEN;
 248
 249         for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
 250                 if (!cpu_possible(cpu))
 251                         continue;
 252                 *pos = cpu + 1;
 253                 return per_cpu_ptr(snet->stats, cpu);
 254         }
 255
 256         return NULL;
 257 }
 258
 259 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 260 {
 261         struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
 262         int cpu;
 263
 264         for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
 265                 if (!cpu_possible(cpu))
 266                         continue;
 267                 *pos = cpu + 1;
 268                 return per_cpu_ptr(snet->stats, cpu);
 269         }
 270
 271         return NULL;
 272 }
 273
 274 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
 275 {
 276         return;
 277 }
 278
 279 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
 280 {
 281         struct synproxy_stats *stats = v;
 282
 283         if (v == SEQ_START_TOKEN) {
 284                 seq_puts(seq, "entries\t\tsyn_received\t"
 285                               "cookie_invalid\tcookie_valid\t"
 286                               "cookie_retrans\tconn_reopened\n");
 287                 return 0;
 288         }
 289
 290         seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
 291                    stats->syn_received,
 292                    stats->cookie_invalid,
 293                    stats->cookie_valid,
 294                    stats->cookie_retrans,
 295                    stats->conn_reopened);
 296
 297         return 0;
 298 }
 299
 300 static const struct seq_operations synproxy_cpu_seq_ops = {
 301         .start          = synproxy_cpu_seq_start,
 302         .next           = synproxy_cpu_seq_next,
 303         .stop           = synproxy_cpu_seq_stop,
 304         .show           = synproxy_cpu_seq_show,
 305 };
 306
 307 static int __net_init synproxy_proc_init(struct net *net)
 308 {
 309         if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
 310                         &synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
 311                 return -ENOMEM;
 312         return 0;
 313 }
 314
 315 static void __net_exit synproxy_proc_exit(struct net *net)
 316 {
 317         remove_proc_entry("synproxy", net->proc_net_stat);
 318 }
 319 #else
 320 static int __net_init synproxy_proc_init(struct net *net)
 321 {
 322         return 0;
 323 }
 324
 325 static void __net_exit synproxy_proc_exit(struct net *net)
 326 {
 327         return;
 328 }
 329 #endif /* CONFIG_PROC_FS */
 330
 331 static int __net_init synproxy_net_init(struct net *net)
 332 {
 333         struct synproxy_net *snet = synproxy_pernet(net);
 334         struct nf_conn *ct;
 335         int err = -ENOMEM;
 336
 337         ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
 338         if (!ct)
 339                 goto err1;
 340
 341         if (!nfct_seqadj_ext_add(ct))
 342                 goto err2;
 343         if (!nfct_synproxy_ext_add(ct))
 344                 goto err2;
 345
 346         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 347         nf_conntrack_get(&ct->ct_general);
 348         snet->tmpl = ct;
 349
 350         snet->stats = alloc_percpu(struct synproxy_stats);
 351         if (snet->stats == NULL)
 352                 goto err2;
 353
 354         err = synproxy_proc_init(net);
 355         if (err < 0)
 356                 goto err3;
 357
 358         return 0;
 359
 360 err3:
 361         free_percpu(snet->stats);
 362 err2:
 363         nf_ct_tmpl_free(ct);
 364 err1:
 365         return err;
 366 }
 367
 368 static void __net_exit synproxy_net_exit(struct net *net)
 369 {
 370         struct synproxy_net *snet = synproxy_pernet(net);
 371
 372         nf_ct_put(snet->tmpl);
 373         synproxy_proc_exit(net);
 374         free_percpu(snet->stats);
 375 }
 376
 377 static struct pernet_operations synproxy_net_ops = {
 378         .init           = synproxy_net_init,
 379         .exit           = synproxy_net_exit,
 380         .id             = &synproxy_net_id,
 381         .size           = sizeof(struct synproxy_net),
 382 };
 383
 384 static int __init synproxy_core_init(void)
 385 {
 386         int err;
 387
 388         err = nf_ct_extend_register(&nf_ct_synproxy_extend);
 389         if (err < 0)
 390                 goto err1;
 391
 392         err = register_pernet_subsys(&synproxy_net_ops);
 393         if (err < 0)
 394                 goto err2;
 395
 396         return 0;
 397
 398 err2:
 399         nf_ct_extend_unregister(&nf_ct_synproxy_extend);
 400 err1:
 401         return err;
 402 }
 403
 404 static void __exit synproxy_core_exit(void)
 405 {
 406         unregister_pernet_subsys(&synproxy_net_ops);
 407         nf_ct_extend_unregister(&nf_ct_synproxy_extend);
 408 }
 409
 410 module_init(synproxy_core_init);
 411 module_exit(synproxy_core_exit);
 412
 413 static struct iphdr *
 414 synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
 415                   __be32 daddr)
 416 {
 417         struct iphdr *iph;
 418
 419         skb_reset_network_header(skb);
 420         iph = skb_put(skb, sizeof(*iph));
 421         iph->version    = 4;
 422         iph->ihl        = sizeof(*iph) / 4;
 423         iph->tos        = 0;
 424         iph->id         = 0;
 425         iph->frag_off   = htons(IP_DF);
 426         iph->ttl        = net->ipv4.sysctl_ip_default_ttl;
 427         iph->protocol   = IPPROTO_TCP;
 428         iph->check      = 0;
 429         iph->saddr      = saddr;
 430         iph->daddr      = daddr;
 431
 432         return iph;
 433 }
 434
 435 static void
 436 synproxy_send_tcp(struct net *net,
 437                   const struct sk_buff *skb, struct sk_buff *nskb,
 438                   struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 439                   struct iphdr *niph, struct tcphdr *nth,
 440                   unsigned int tcp_hdr_size)
 441 {
 442         nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0);
 443         nskb->ip_summed   = CHECKSUM_PARTIAL;
 444         nskb->csum_start  = (unsigned char *)nth - nskb->head;
 445         nskb->csum_offset = offsetof(struct tcphdr, check);
 446
 447         skb_dst_set_noref(nskb, skb_dst(skb));
 448         nskb->protocol = htons(ETH_P_IP);
 449         if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
 450                 goto free_nskb;
 451
 452         if (nfct) {
 453                 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 454                 nf_conntrack_get(nfct);
 455         }
 456
 457         ip_local_out(net, nskb->sk, nskb);
 458         return;
 459
 460 free_nskb:
 461         kfree_skb(nskb);
 462 }
 463
 464 void
 465 synproxy_send_client_synack(struct net *net,
 466                             const struct sk_buff *skb, const struct tcphdr *th,
 467                             const struct synproxy_options *opts)
 468 {
 469         struct sk_buff *nskb;
 470         struct iphdr *iph, *niph;
 471         struct tcphdr *nth;
 472         unsigned int tcp_hdr_size;
 473         u16 mss = opts->mss_encode;
 474
 475         iph = ip_hdr(skb);
 476
 477         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 478         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 479                          GFP_ATOMIC);
 480         if (!nskb)
 481                 return;
 482         skb_reserve(nskb, MAX_TCP_HEADER);
 483
 484         niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
 485
 486         skb_reset_transport_header(nskb);
 487         nth = skb_put(nskb, tcp_hdr_size);
 488         nth->source     = th->dest;
 489         nth->dest       = th->source;
 490         nth->seq        = htonl(__cookie_v4_init_sequence(iph, th, &mss));
 491         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 492         tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 493         if (opts->options & NF_SYNPROXY_OPT_ECN)
 494                 tcp_flag_word(nth) |= TCP_FLAG_ECE;
 495         nth->doff       = tcp_hdr_size / 4;
 496         nth->window     = 0;
 497         nth->check      = 0;
 498         nth->urg_ptr    = 0;
 499
 500         synproxy_build_options(nth, opts);
 501
 502         synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
 503                           IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
 504 }
 505 EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
 506
 507 static void
 508 synproxy_send_server_syn(struct net *net,
 509                          const struct sk_buff *skb, const struct tcphdr *th,
 510                          const struct synproxy_options *opts, u32 recv_seq)
 511 {
 512         struct synproxy_net *snet = synproxy_pernet(net);
 513         struct sk_buff *nskb;
 514         struct iphdr *iph, *niph;
 515         struct tcphdr *nth;
 516         unsigned int tcp_hdr_size;
 517
 518         iph = ip_hdr(skb);
 519
 520         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 521         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 522                          GFP_ATOMIC);
 523         if (!nskb)
 524                 return;
 525         skb_reserve(nskb, MAX_TCP_HEADER);
 526
 527         niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
 528
 529         skb_reset_transport_header(nskb);
 530         nth = skb_put(nskb, tcp_hdr_size);
 531         nth->source     = th->source;
 532         nth->dest       = th->dest;
 533         nth->seq        = htonl(recv_seq - 1);
 534         /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 535          * sequence number translation once a connection tracking entry exists.
 536          */
 537         nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 538         tcp_flag_word(nth) = TCP_FLAG_SYN;
 539         if (opts->options & NF_SYNPROXY_OPT_ECN)
 540                 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 541         nth->doff       = tcp_hdr_size / 4;
 542         nth->window     = th->window;
 543         nth->check      = 0;
 544         nth->urg_ptr    = 0;
 545
 546         synproxy_build_options(nth, opts);
 547
 548         synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
 549                           niph, nth, tcp_hdr_size);
 550 }
 551
 552 static void
 553 synproxy_send_server_ack(struct net *net,
 554                          const struct ip_ct_tcp *state,
 555                          const struct sk_buff *skb, const struct tcphdr *th,
 556                          const struct synproxy_options *opts)
 557 {
 558         struct sk_buff *nskb;
 559         struct iphdr *iph, *niph;
 560         struct tcphdr *nth;
 561         unsigned int tcp_hdr_size;
 562
 563         iph = ip_hdr(skb);
 564
 565         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 566         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 567                          GFP_ATOMIC);
 568         if (!nskb)
 569                 return;
 570         skb_reserve(nskb, MAX_TCP_HEADER);
 571
 572         niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
 573
 574         skb_reset_transport_header(nskb);
 575         nth = skb_put(nskb, tcp_hdr_size);
 576         nth->source     = th->dest;
 577         nth->dest       = th->source;
 578         nth->seq        = htonl(ntohl(th->ack_seq));
 579         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 580         tcp_flag_word(nth) = TCP_FLAG_ACK;
 581         nth->doff       = tcp_hdr_size / 4;
 582         nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
 583         nth->check      = 0;
 584         nth->urg_ptr    = 0;
 585
 586         synproxy_build_options(nth, opts);
 587
 588         synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
 589 }
 590
 591 static void
 592 synproxy_send_client_ack(struct net *net,
 593                          const struct sk_buff *skb, const struct tcphdr *th,
 594                          const struct synproxy_options *opts)
 595 {
 596         struct sk_buff *nskb;
 597         struct iphdr *iph, *niph;
 598         struct tcphdr *nth;
 599         unsigned int tcp_hdr_size;
 600
 601         iph = ip_hdr(skb);
 602
 603         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 604         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 605                          GFP_ATOMIC);
 606         if (!nskb)
 607                 return;
 608         skb_reserve(nskb, MAX_TCP_HEADER);
 609
 610         niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
 611
 612         skb_reset_transport_header(nskb);
 613         nth = skb_put(nskb, tcp_hdr_size);
 614         nth->source     = th->source;
 615         nth->dest       = th->dest;
 616         nth->seq        = htonl(ntohl(th->seq) + 1);
 617         nth->ack_seq    = th->ack_seq;
 618         tcp_flag_word(nth) = TCP_FLAG_ACK;
 619         nth->doff       = tcp_hdr_size / 4;
 620         nth->window     = htons(ntohs(th->window) >> opts->wscale);
 621         nth->check      = 0;
 622         nth->urg_ptr    = 0;
 623
 624         synproxy_build_options(nth, opts);
 625
 626         synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
 627                           IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
 628 }
 629
 630 bool
 631 synproxy_recv_client_ack(struct net *net,
 632                          const struct sk_buff *skb, const struct tcphdr *th,
 633                          struct synproxy_options *opts, u32 recv_seq)
 634 {
 635         struct synproxy_net *snet = synproxy_pernet(net);
 636         int mss;
 637
 638         mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1);
 639         if (mss == 0) {
 640                 this_cpu_inc(snet->stats->cookie_invalid);
 641                 return false;
 642         }
 643
 644         this_cpu_inc(snet->stats->cookie_valid);
 645         opts->mss_option = mss;
 646         opts->options |= NF_SYNPROXY_OPT_MSS;
 647
 648         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
 649                 synproxy_check_timestamp_cookie(opts);
 650
 651         synproxy_send_server_syn(net, skb, th, opts, recv_seq);
 652         return true;
 653 }
 654 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
 655
 656 unsigned int
 657 ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
 658                    const struct nf_hook_state *nhs)
 659 {
 660         struct net *net = nhs->net;
 661         struct synproxy_net *snet = synproxy_pernet(net);
 662         enum ip_conntrack_info ctinfo;
 663         struct nf_conn *ct;
 664         struct nf_conn_synproxy *synproxy;
 665         struct synproxy_options opts = {};
 666         const struct ip_ct_tcp *state;
 667         struct tcphdr *th, _th;
 668         unsigned int thoff;
 669
 670         ct = nf_ct_get(skb, &ctinfo);
 671         if (!ct)
 672                 return NF_ACCEPT;
 673
 674         synproxy = nfct_synproxy(ct);
 675         if (!synproxy)
 676                 return NF_ACCEPT;
 677
 678         if (nf_is_loopback_packet(skb) ||
 679             ip_hdr(skb)->protocol != IPPROTO_TCP)
 680                 return NF_ACCEPT;
 681
 682         thoff = ip_hdrlen(skb);
 683         th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
 684         if (!th)
 685                 return NF_DROP;
 686
 687         state = &ct->proto.tcp;
 688         switch (state->state) {
 689         case TCP_CONNTRACK_CLOSE:
 690                 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
 691                         nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
 692                                                       ntohl(th->seq) + 1);
 693                         break;
 694                 }
 695
 696                 if (!th->syn || th->ack ||
 697                     CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
 698                         break;
 699
 700                 /* Reopened connection - reset the sequence number and timestamp
 701                  * adjustments, they will get initialized once the connection is
 702                  * reestablished.
 703                  */
 704                 nf_ct_seqadj_init(ct, ctinfo, 0);
 705                 synproxy->tsoff = 0;
 706                 this_cpu_inc(snet->stats->conn_reopened);
 707
 708                 /* fall through */
 709         case TCP_CONNTRACK_SYN_SENT:
 710                 if (!synproxy_parse_options(skb, thoff, th, &opts))
 711                         return NF_DROP;
 712
 713                 if (!th->syn && th->ack &&
 714                     CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
 715                         /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
 716                          * therefore we need to add 1 to make the SYN sequence
 717                          * number match the one of first SYN.
 718                          */
 719                         if (synproxy_recv_client_ack(net, skb, th, &opts,
 720                                                      ntohl(th->seq) + 1)) {
 721                                 this_cpu_inc(snet->stats->cookie_retrans);
 722                                 consume_skb(skb);
 723                                 return NF_STOLEN;
 724                         } else {
 725                                 return NF_DROP;
 726                         }
 727                 }
 728
 729                 synproxy->isn = ntohl(th->ack_seq);
 730                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
 731                         synproxy->its = opts.tsecr;
 732
 733                 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 734                 break;
 735         case TCP_CONNTRACK_SYN_RECV:
 736                 if (!th->syn || !th->ack)
 737                         break;
 738
 739                 if (!synproxy_parse_options(skb, thoff, th, &opts))
 740                         return NF_DROP;
 741
 742                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
 743                         synproxy->tsoff = opts.tsval - synproxy->its;
 744                         nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 745                 }
 746
 747                 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
 748                                   NF_SYNPROXY_OPT_WSCALE |
 749                                   NF_SYNPROXY_OPT_SACK_PERM);
 750
 751                 swap(opts.tsval, opts.tsecr);
 752                 synproxy_send_server_ack(net, state, skb, th, &opts);
 753
 754                 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
 755                 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
 756
 757                 swap(opts.tsval, opts.tsecr);
 758                 synproxy_send_client_ack(net, skb, th, &opts);
 759
 760                 consume_skb(skb);
 761                 return NF_STOLEN;
 762         default:
 763                 break;
 764         }
 765
 766         synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
 767         return NF_ACCEPT;
 768 }
 769 EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
 770
 771 static const struct nf_hook_ops ipv4_synproxy_ops[] = {
 772         {
 773                 .hook           = ipv4_synproxy_hook,
 774                 .pf             = NFPROTO_IPV4,
 775                 .hooknum        = NF_INET_LOCAL_IN,
 776                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 777         },
 778         {
 779                 .hook           = ipv4_synproxy_hook,
 780                 .pf             = NFPROTO_IPV4,
 781                 .hooknum        = NF_INET_POST_ROUTING,
 782                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 783         },
 784 };
 785
 786 int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
 787 {
 788         int err;
 789
 790         if (snet->hook_ref4 == 0) {
 791                 err = nf_register_net_hooks(net, ipv4_synproxy_ops,
 792                                             ARRAY_SIZE(ipv4_synproxy_ops));
 793                 if (err)
 794                         return err;
 795         }
 796
 797         snet->hook_ref4++;
 798         return 0;
 799 }
 800 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
 801
 802 void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
 803 {
 804         snet->hook_ref4--;
 805         if (snet->hook_ref4 == 0)
 806                 nf_unregister_net_hooks(net, ipv4_synproxy_ops,
 807                                         ARRAY_SIZE(ipv4_synproxy_ops));
 808 }
 809 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
 810
 811 #if IS_ENABLED(CONFIG_IPV6)
 812 static struct ipv6hdr *
 813 synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
 814                        const struct in6_addr *saddr,
 815                        const struct in6_addr *daddr)
 816 {
 817         struct ipv6hdr *iph;
 818
 819         skb_reset_network_header(skb);
 820         iph = skb_put(skb, sizeof(*iph));
 821         ip6_flow_hdr(iph, 0, 0);
 822         iph->hop_limit  = net->ipv6.devconf_all->hop_limit;
 823         iph->nexthdr    = IPPROTO_TCP;
 824         iph->saddr      = *saddr;
 825         iph->daddr      = *daddr;
 826
 827         return iph;
 828 }
 829
 830 static void
 831 synproxy_send_tcp_ipv6(struct net *net,
 832                        const struct sk_buff *skb, struct sk_buff *nskb,
 833                        struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 834                        struct ipv6hdr *niph, struct tcphdr *nth,
 835                        unsigned int tcp_hdr_size)
 836 {
 837         struct dst_entry *dst;
 838         struct flowi6 fl6;
 839         int err;
 840
 841         nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
 842         nskb->ip_summed   = CHECKSUM_PARTIAL;
 843         nskb->csum_start  = (unsigned char *)nth - nskb->head;
 844         nskb->csum_offset = offsetof(struct tcphdr, check);
 845
 846         memset(&fl6, 0, sizeof(fl6));
 847         fl6.flowi6_proto = IPPROTO_TCP;
 848         fl6.saddr = niph->saddr;
 849         fl6.daddr = niph->daddr;
 850         fl6.fl6_sport = nth->source;
 851         fl6.fl6_dport = nth->dest;
 852         security_skb_classify_flow((struct sk_buff *)skb,
 853                                    flowi6_to_flowi(&fl6));
 854         err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
 855         if (err) {
 856                 goto free_nskb;
 857         }
 858
 859         dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
 860         if (IS_ERR(dst))
 861                 goto free_nskb;
 862
 863         skb_dst_set(nskb, dst);
 864
 865         if (nfct) {
 866                 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 867                 nf_conntrack_get(nfct);
 868         }
 869
 870         ip6_local_out(net, nskb->sk, nskb);
 871         return;
 872
 873 free_nskb:
 874         kfree_skb(nskb);
 875 }
 876
 877 void
 878 synproxy_send_client_synack_ipv6(struct net *net,
 879                                  const struct sk_buff *skb,
 880                                  const struct tcphdr *th,
 881                                  const struct synproxy_options *opts)
 882 {
 883         struct sk_buff *nskb;
 884         struct ipv6hdr *iph, *niph;
 885         struct tcphdr *nth;
 886         unsigned int tcp_hdr_size;
 887         u16 mss = opts->mss_encode;
 888
 889         iph = ipv6_hdr(skb);
 890
 891         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 892         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 893                          GFP_ATOMIC);
 894         if (!nskb)
 895                 return;
 896         skb_reserve(nskb, MAX_TCP_HEADER);
 897
 898         niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 899
 900         skb_reset_transport_header(nskb);
 901         nth = skb_put(nskb, tcp_hdr_size);
 902         nth->source     = th->dest;
 903         nth->dest       = th->source;
 904         nth->seq        = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss));
 905         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 906         tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 907         if (opts->options & NF_SYNPROXY_OPT_ECN)
 908                 tcp_flag_word(nth) |= TCP_FLAG_ECE;
 909         nth->doff       = tcp_hdr_size / 4;
 910         nth->window     = 0;
 911         nth->check      = 0;
 912         nth->urg_ptr    = 0;
 913
 914         synproxy_build_options(nth, opts);
 915
 916         synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
 917                                IP_CT_ESTABLISHED_REPLY, niph, nth,
 918                                tcp_hdr_size);
 919 }
 920 EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
 921
 922 static void
 923 synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb,
 924                               const struct tcphdr *th,
 925                               const struct synproxy_options *opts, u32 recv_seq)
 926 {
 927         struct synproxy_net *snet = synproxy_pernet(net);
 928         struct sk_buff *nskb;
 929         struct ipv6hdr *iph, *niph;
 930         struct tcphdr *nth;
 931         unsigned int tcp_hdr_size;
 932
 933         iph = ipv6_hdr(skb);
 934
 935         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 936         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 937                          GFP_ATOMIC);
 938         if (!nskb)
 939                 return;
 940         skb_reserve(nskb, MAX_TCP_HEADER);
 941
 942         niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
 943
 944         skb_reset_transport_header(nskb);
 945         nth = skb_put(nskb, tcp_hdr_size);
 946         nth->source     = th->source;
 947         nth->dest       = th->dest;
 948         nth->seq        = htonl(recv_seq - 1);
 949         /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 950          * sequence number translation once a connection tracking entry exists.
 951          */
 952         nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 953         tcp_flag_word(nth) = TCP_FLAG_SYN;
 954         if (opts->options & NF_SYNPROXY_OPT_ECN)
 955                 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 956         nth->doff       = tcp_hdr_size / 4;
 957         nth->window     = th->window;
 958         nth->check      = 0;
 959         nth->urg_ptr    = 0;
 960
 961         synproxy_build_options(nth, opts);
 962
 963         synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
 964                                IP_CT_NEW, niph, nth, tcp_hdr_size);
 965 }
 966
 967 static void
 968 synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state,
 969                               const struct sk_buff *skb,
 970                               const struct tcphdr *th,
 971                               const struct synproxy_options *opts)
 972 {
 973         struct sk_buff *nskb;
 974         struct ipv6hdr *iph, *niph;
 975         struct tcphdr *nth;
 976         unsigned int tcp_hdr_size;
 977
 978         iph = ipv6_hdr(skb);
 979
 980         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 981         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 982                          GFP_ATOMIC);
 983         if (!nskb)
 984                 return;
 985         skb_reserve(nskb, MAX_TCP_HEADER);
 986
 987         niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 988
 989         skb_reset_transport_header(nskb);
 990         nth = skb_put(nskb, tcp_hdr_size);
 991         nth->source     = th->dest;
 992         nth->dest       = th->source;
 993         nth->seq        = htonl(ntohl(th->ack_seq));
 994         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 995         tcp_flag_word(nth) = TCP_FLAG_ACK;
 996         nth->doff       = tcp_hdr_size / 4;
 997         nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
 998         nth->check      = 0;
 999         nth->urg_ptr    = 0;
1000
1001         synproxy_build_options(nth, opts);
1002
1003         synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth,
1004                                tcp_hdr_size);
1005 }
1006
1007 static void
1008 synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
1009                               const struct tcphdr *th,
1010                               const struct synproxy_options *opts)
1011 {
1012         struct sk_buff *nskb;
1013         struct ipv6hdr *iph, *niph;
1014         struct tcphdr *nth;
1015         unsigned int tcp_hdr_size;
1016
1017         iph = ipv6_hdr(skb);
1018
1019         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
1020         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
1021                          GFP_ATOMIC);
1022         if (!nskb)
1023                 return;
1024         skb_reserve(nskb, MAX_TCP_HEADER);
1025
1026         niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
1027
1028         skb_reset_transport_header(nskb);
1029         nth = skb_put(nskb, tcp_hdr_size);
1030         nth->source     = th->source;
1031         nth->dest       = th->dest;
1032         nth->seq        = htonl(ntohl(th->seq) + 1);
1033         nth->ack_seq    = th->ack_seq;
1034         tcp_flag_word(nth) = TCP_FLAG_ACK;
1035         nth->doff       = tcp_hdr_size / 4;
1036         nth->window     = htons(ntohs(th->window) >> opts->wscale);
1037         nth->check      = 0;
1038         nth->urg_ptr    = 0;
1039
1040         synproxy_build_options(nth, opts);
1041
1042         synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
1043                                IP_CT_ESTABLISHED_REPLY, niph, nth,
1044                                tcp_hdr_size);
1045 }
1046
1047 bool
1048 synproxy_recv_client_ack_ipv6(struct net *net,
1049                               const struct sk_buff *skb,
1050                               const struct tcphdr *th,
1051                               struct synproxy_options *opts, u32 recv_seq)
1052 {
1053         struct synproxy_net *snet = synproxy_pernet(net);
1054         int mss;
1055
1056         mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
1057         if (mss == 0) {
1058                 this_cpu_inc(snet->stats->cookie_invalid);
1059                 return false;
1060         }
1061
1062         this_cpu_inc(snet->stats->cookie_valid);
1063         opts->mss_option = mss;
1064         opts->options |= NF_SYNPROXY_OPT_MSS;
1065
1066         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
1067                 synproxy_check_timestamp_cookie(opts);
1068
1069         synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
1070         return true;
1071 }
1072 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
1073
1074 unsigned int
1075 ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
1076                    const struct nf_hook_state *nhs)
1077 {
1078         struct net *net = nhs->net;
1079         struct synproxy_net *snet = synproxy_pernet(net);
1080         enum ip_conntrack_info ctinfo;
1081         struct nf_conn *ct;
1082         struct nf_conn_synproxy *synproxy;
1083         struct synproxy_options opts = {};
1084         const struct ip_ct_tcp *state;
1085         struct tcphdr *th, _th;
1086         __be16 frag_off;
1087         u8 nexthdr;
1088         int thoff;
1089
1090         ct = nf_ct_get(skb, &ctinfo);
1091         if (!ct)
1092                 return NF_ACCEPT;
1093
1094         synproxy = nfct_synproxy(ct);
1095         if (!synproxy)
1096                 return NF_ACCEPT;
1097
1098         if (nf_is_loopback_packet(skb))
1099                 return NF_ACCEPT;
1100
1101         nexthdr = ipv6_hdr(skb)->nexthdr;
1102         thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
1103                                  &frag_off);
1104         if (thoff < 0 || nexthdr != IPPROTO_TCP)
1105                 return NF_ACCEPT;
1106
1107         th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
1108         if (!th)
1109                 return NF_DROP;
1110
1111         state = &ct->proto.tcp;
1112         switch (state->state) {
1113         case TCP_CONNTRACK_CLOSE:
1114                 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
1115                         nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
1116                                                       ntohl(th->seq) + 1);
1117                         break;
1118                 }
1119
1120                 if (!th->syn || th->ack ||
1121                     CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
1122                         break;
1123
1124                 /* Reopened connection - reset the sequence number and timestamp
1125                  * adjustments, they will get initialized once the connection is
1126                  * reestablished.
1127                  */
1128                 nf_ct_seqadj_init(ct, ctinfo, 0);
1129                 synproxy->tsoff = 0;
1130                 this_cpu_inc(snet->stats->conn_reopened);
1131
1132                 /* fall through */
1133         case TCP_CONNTRACK_SYN_SENT:
1134                 if (!synproxy_parse_options(skb, thoff, th, &opts))
1135                         return NF_DROP;
1136
1137                 if (!th->syn && th->ack &&
1138                     CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
1139                         /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
1140                          * therefore we need to add 1 to make the SYN sequence
1141                          * number match the one of first SYN.
1142                          */
1143                         if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
1144                                                           ntohl(th->seq) + 1)) {
1145                                 this_cpu_inc(snet->stats->cookie_retrans);
1146                                 consume_skb(skb);
1147                                 return NF_STOLEN;
1148                         } else {
1149                                 return NF_DROP;
1150                         }
1151                 }
1152
1153                 synproxy->isn = ntohl(th->ack_seq);
1154                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
1155                         synproxy->its = opts.tsecr;
1156
1157                 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1158                 break;
1159         case TCP_CONNTRACK_SYN_RECV:
1160                 if (!th->syn || !th->ack)
1161                         break;
1162
1163                 if (!synproxy_parse_options(skb, thoff, th, &opts))
1164                         return NF_DROP;
1165
1166                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
1167                         synproxy->tsoff = opts.tsval - synproxy->its;
1168                         nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1169                 }
1170
1171                 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
1172                                   NF_SYNPROXY_OPT_WSCALE |
1173                                   NF_SYNPROXY_OPT_SACK_PERM);
1174
1175                 swap(opts.tsval, opts.tsecr);
1176                 synproxy_send_server_ack_ipv6(net, state, skb, th, &opts);
1177
1178                 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
1179                 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
1180
1181                 swap(opts.tsval, opts.tsecr);
1182                 synproxy_send_client_ack_ipv6(net, skb, th, &opts);
1183
1184                 consume_skb(skb);
1185                 return NF_STOLEN;
1186         default:
1187                 break;
1188         }
1189
1190         synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
1191         return NF_ACCEPT;
1192 }
1193 EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
1194
1195 static const struct nf_hook_ops ipv6_synproxy_ops[] = {
1196         {
1197                 .hook           = ipv6_synproxy_hook,
1198                 .pf             = NFPROTO_IPV6,
1199                 .hooknum        = NF_INET_LOCAL_IN,
1200                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1201         },
1202         {
1203                 .hook           = ipv6_synproxy_hook,
1204                 .pf             = NFPROTO_IPV6,
1205                 .hooknum        = NF_INET_POST_ROUTING,
1206                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1207         },
1208 };
1209
1210 int
1211 nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
1212 {
1213         int err;
1214
1215         if (snet->hook_ref6 == 0) {
1216                 err = nf_register_net_hooks(net, ipv6_synproxy_ops,
1217                                             ARRAY_SIZE(ipv6_synproxy_ops));
1218                 if (err)
1219                         return err;
1220         }
1221
1222         snet->hook_ref6++;
1223         return 0;
1224 }
1225 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
1226
1227 void
1228 nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
1229 {
1230         snet->hook_ref6--;
1231         if (snet->hook_ref6 == 0)
1232                 nf_unregister_net_hooks(net, ipv6_synproxy_ops,
1233                                         ARRAY_SIZE(ipv6_synproxy_ops));
1234 }
1235 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
1236 #endif /* CONFIG_IPV6 */
1237
1238 MODULE_LICENSE("GPL");
1239 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");