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         (*pos)++;
 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->sk, 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                 fallthrough;
 708         case TCP_CONNTRACK_SYN_SENT:
 709                 if (!synproxy_parse_options(skb, thoff, th, &opts))
 710                         return NF_DROP;
 711
 712                 if (!th->syn && th->ack &&
 713                     CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
 714                         /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
 715                          * therefore we need to add 1 to make the SYN sequence
 716                          * number match the one of first SYN.
 717                          */
 718                         if (synproxy_recv_client_ack(net, skb, th, &opts,
 719                                                      ntohl(th->seq) + 1)) {
 720                                 this_cpu_inc(snet->stats->cookie_retrans);
 721                                 consume_skb(skb);
 722                                 return NF_STOLEN;
 723                         } else {
 724                                 return NF_DROP;
 725                         }
 726                 }
 727
 728                 synproxy->isn = ntohl(th->ack_seq);
 729                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
 730                         synproxy->its = opts.tsecr;
 731
 732                 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 733                 break;
 734         case TCP_CONNTRACK_SYN_RECV:
 735                 if (!th->syn || !th->ack)
 736                         break;
 737
 738                 if (!synproxy_parse_options(skb, thoff, th, &opts))
 739                         return NF_DROP;
 740
 741                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
 742                         synproxy->tsoff = opts.tsval - synproxy->its;
 743                         nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 744                 }
 745
 746                 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
 747                                   NF_SYNPROXY_OPT_WSCALE |
 748                                   NF_SYNPROXY_OPT_SACK_PERM);
 749
 750                 swap(opts.tsval, opts.tsecr);
 751                 synproxy_send_server_ack(net, state, skb, th, &opts);
 752
 753                 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
 754                 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
 755
 756                 swap(opts.tsval, opts.tsecr);
 757                 synproxy_send_client_ack(net, skb, th, &opts);
 758
 759                 consume_skb(skb);
 760                 return NF_STOLEN;
 761         default:
 762                 break;
 763         }
 764
 765         synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
 766         return NF_ACCEPT;
 767 }
 768 EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
 769
 770 static const struct nf_hook_ops ipv4_synproxy_ops[] = {
 771         {
 772                 .hook           = ipv4_synproxy_hook,
 773                 .pf             = NFPROTO_IPV4,
 774                 .hooknum        = NF_INET_LOCAL_IN,
 775                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 776         },
 777         {
 778                 .hook           = ipv4_synproxy_hook,
 779                 .pf             = NFPROTO_IPV4,
 780                 .hooknum        = NF_INET_POST_ROUTING,
 781                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 782         },
 783 };
 784
 785 int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
 786 {
 787         int err;
 788
 789         if (snet->hook_ref4 == 0) {
 790                 err = nf_register_net_hooks(net, ipv4_synproxy_ops,
 791                                             ARRAY_SIZE(ipv4_synproxy_ops));
 792                 if (err)
 793                         return err;
 794         }
 795
 796         snet->hook_ref4++;
 797         return 0;
 798 }
 799 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
 800
 801 void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
 802 {
 803         snet->hook_ref4--;
 804         if (snet->hook_ref4 == 0)
 805                 nf_unregister_net_hooks(net, ipv4_synproxy_ops,
 806                                         ARRAY_SIZE(ipv4_synproxy_ops));
 807 }
 808 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
 809
 810 #if IS_ENABLED(CONFIG_IPV6)
 811 static struct ipv6hdr *
 812 synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
 813                        const struct in6_addr *saddr,
 814                        const struct in6_addr *daddr)
 815 {
 816         struct ipv6hdr *iph;
 817
 818         skb_reset_network_header(skb);
 819         iph = skb_put(skb, sizeof(*iph));
 820         ip6_flow_hdr(iph, 0, 0);
 821         iph->hop_limit  = net->ipv6.devconf_all->hop_limit;
 822         iph->nexthdr    = IPPROTO_TCP;
 823         iph->saddr      = *saddr;
 824         iph->daddr      = *daddr;
 825
 826         return iph;
 827 }
 828
 829 static void
 830 synproxy_send_tcp_ipv6(struct net *net,
 831                        const struct sk_buff *skb, struct sk_buff *nskb,
 832                        struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 833                        struct ipv6hdr *niph, struct tcphdr *nth,
 834                        unsigned int tcp_hdr_size)
 835 {
 836         struct dst_entry *dst;
 837         struct flowi6 fl6;
 838         int err;
 839
 840         nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
 841         nskb->ip_summed   = CHECKSUM_PARTIAL;
 842         nskb->csum_start  = (unsigned char *)nth - nskb->head;
 843         nskb->csum_offset = offsetof(struct tcphdr, check);
 844
 845         memset(&fl6, 0, sizeof(fl6));
 846         fl6.flowi6_proto = IPPROTO_TCP;
 847         fl6.saddr = niph->saddr;
 848         fl6.daddr = niph->daddr;
 849         fl6.fl6_sport = nth->source;
 850         fl6.fl6_dport = nth->dest;
 851         security_skb_classify_flow((struct sk_buff *)skb,
 852                                    flowi6_to_flowi_common(&fl6));
 853         err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
 854         if (err) {
 855                 goto free_nskb;
 856         }
 857
 858         dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
 859         if (IS_ERR(dst))
 860                 goto free_nskb;
 861
 862         skb_dst_set(nskb, dst);
 863
 864         if (nfct) {
 865                 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 866                 nf_conntrack_get(nfct);
 867         }
 868
 869         ip6_local_out(net, nskb->sk, nskb);
 870         return;
 871
 872 free_nskb:
 873         kfree_skb(nskb);
 874 }
 875
 876 void
 877 synproxy_send_client_synack_ipv6(struct net *net,
 878                                  const struct sk_buff *skb,
 879                                  const struct tcphdr *th,
 880                                  const struct synproxy_options *opts)
 881 {
 882         struct sk_buff *nskb;
 883         struct ipv6hdr *iph, *niph;
 884         struct tcphdr *nth;
 885         unsigned int tcp_hdr_size;
 886         u16 mss = opts->mss_encode;
 887
 888         iph = ipv6_hdr(skb);
 889
 890         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 891         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 892                          GFP_ATOMIC);
 893         if (!nskb)
 894                 return;
 895         skb_reserve(nskb, MAX_TCP_HEADER);
 896
 897         niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 898
 899         skb_reset_transport_header(nskb);
 900         nth = skb_put(nskb, tcp_hdr_size);
 901         nth->source     = th->dest;
 902         nth->dest       = th->source;
 903         nth->seq        = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss));
 904         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 905         tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 906         if (opts->options & NF_SYNPROXY_OPT_ECN)
 907                 tcp_flag_word(nth) |= TCP_FLAG_ECE;
 908         nth->doff       = tcp_hdr_size / 4;
 909         nth->window     = 0;
 910         nth->check      = 0;
 911         nth->urg_ptr    = 0;
 912
 913         synproxy_build_options(nth, opts);
 914
 915         synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
 916                                IP_CT_ESTABLISHED_REPLY, niph, nth,
 917                                tcp_hdr_size);
 918 }
 919 EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
 920
 921 static void
 922 synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb,
 923                               const struct tcphdr *th,
 924                               const struct synproxy_options *opts, u32 recv_seq)
 925 {
 926         struct synproxy_net *snet = synproxy_pernet(net);
 927         struct sk_buff *nskb;
 928         struct ipv6hdr *iph, *niph;
 929         struct tcphdr *nth;
 930         unsigned int tcp_hdr_size;
 931
 932         iph = ipv6_hdr(skb);
 933
 934         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 935         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 936                          GFP_ATOMIC);
 937         if (!nskb)
 938                 return;
 939         skb_reserve(nskb, MAX_TCP_HEADER);
 940
 941         niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
 942
 943         skb_reset_transport_header(nskb);
 944         nth = skb_put(nskb, tcp_hdr_size);
 945         nth->source     = th->source;
 946         nth->dest       = th->dest;
 947         nth->seq        = htonl(recv_seq - 1);
 948         /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 949          * sequence number translation once a connection tracking entry exists.
 950          */
 951         nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 952         tcp_flag_word(nth) = TCP_FLAG_SYN;
 953         if (opts->options & NF_SYNPROXY_OPT_ECN)
 954                 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 955         nth->doff       = tcp_hdr_size / 4;
 956         nth->window     = th->window;
 957         nth->check      = 0;
 958         nth->urg_ptr    = 0;
 959
 960         synproxy_build_options(nth, opts);
 961
 962         synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
 963                                IP_CT_NEW, niph, nth, tcp_hdr_size);
 964 }
 965
 966 static void
 967 synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state,
 968                               const struct sk_buff *skb,
 969                               const struct tcphdr *th,
 970                               const struct synproxy_options *opts)
 971 {
 972         struct sk_buff *nskb;
 973         struct ipv6hdr *iph, *niph;
 974         struct tcphdr *nth;
 975         unsigned int tcp_hdr_size;
 976
 977         iph = ipv6_hdr(skb);
 978
 979         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 980         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 981                          GFP_ATOMIC);
 982         if (!nskb)
 983                 return;
 984         skb_reserve(nskb, MAX_TCP_HEADER);
 985
 986         niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 987
 988         skb_reset_transport_header(nskb);
 989         nth = skb_put(nskb, tcp_hdr_size);
 990         nth->source     = th->dest;
 991         nth->dest       = th->source;
 992         nth->seq        = htonl(ntohl(th->ack_seq));
 993         nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 994         tcp_flag_word(nth) = TCP_FLAG_ACK;
 995         nth->doff       = tcp_hdr_size / 4;
 996         nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
 997         nth->check      = 0;
 998         nth->urg_ptr    = 0;
 999
1000         synproxy_build_options(nth, opts);
1001
1002         synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth,
1003                                tcp_hdr_size);
1004 }
1005
1006 static void
1007 synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
1008                               const struct tcphdr *th,
1009                               const struct synproxy_options *opts)
1010 {
1011         struct sk_buff *nskb;
1012         struct ipv6hdr *iph, *niph;
1013         struct tcphdr *nth;
1014         unsigned int tcp_hdr_size;
1015
1016         iph = ipv6_hdr(skb);
1017
1018         tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
1019         nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
1020                          GFP_ATOMIC);
1021         if (!nskb)
1022                 return;
1023         skb_reserve(nskb, MAX_TCP_HEADER);
1024
1025         niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
1026
1027         skb_reset_transport_header(nskb);
1028         nth = skb_put(nskb, tcp_hdr_size);
1029         nth->source     = th->source;
1030         nth->dest       = th->dest;
1031         nth->seq        = htonl(ntohl(th->seq) + 1);
1032         nth->ack_seq    = th->ack_seq;
1033         tcp_flag_word(nth) = TCP_FLAG_ACK;
1034         nth->doff       = tcp_hdr_size / 4;
1035         nth->window     = htons(ntohs(th->window) >> opts->wscale);
1036         nth->check      = 0;
1037         nth->urg_ptr    = 0;
1038
1039         synproxy_build_options(nth, opts);
1040
1041         synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
1042                                IP_CT_ESTABLISHED_REPLY, niph, nth,
1043                                tcp_hdr_size);
1044 }
1045
1046 bool
1047 synproxy_recv_client_ack_ipv6(struct net *net,
1048                               const struct sk_buff *skb,
1049                               const struct tcphdr *th,
1050                               struct synproxy_options *opts, u32 recv_seq)
1051 {
1052         struct synproxy_net *snet = synproxy_pernet(net);
1053         int mss;
1054
1055         mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
1056         if (mss == 0) {
1057                 this_cpu_inc(snet->stats->cookie_invalid);
1058                 return false;
1059         }
1060
1061         this_cpu_inc(snet->stats->cookie_valid);
1062         opts->mss_option = mss;
1063         opts->options |= NF_SYNPROXY_OPT_MSS;
1064
1065         if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
1066                 synproxy_check_timestamp_cookie(opts);
1067
1068         synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
1069         return true;
1070 }
1071 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
1072
1073 unsigned int
1074 ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
1075                    const struct nf_hook_state *nhs)
1076 {
1077         struct net *net = nhs->net;
1078         struct synproxy_net *snet = synproxy_pernet(net);
1079         enum ip_conntrack_info ctinfo;
1080         struct nf_conn *ct;
1081         struct nf_conn_synproxy *synproxy;
1082         struct synproxy_options opts = {};
1083         const struct ip_ct_tcp *state;
1084         struct tcphdr *th, _th;
1085         __be16 frag_off;
1086         u8 nexthdr;
1087         int thoff;
1088
1089         ct = nf_ct_get(skb, &ctinfo);
1090         if (!ct)
1091                 return NF_ACCEPT;
1092
1093         synproxy = nfct_synproxy(ct);
1094         if (!synproxy)
1095                 return NF_ACCEPT;
1096
1097         if (nf_is_loopback_packet(skb))
1098                 return NF_ACCEPT;
1099
1100         nexthdr = ipv6_hdr(skb)->nexthdr;
1101         thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
1102                                  &frag_off);
1103         if (thoff < 0 || nexthdr != IPPROTO_TCP)
1104                 return NF_ACCEPT;
1105
1106         th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
1107         if (!th)
1108                 return NF_DROP;
1109
1110         state = &ct->proto.tcp;
1111         switch (state->state) {
1112         case TCP_CONNTRACK_CLOSE:
1113                 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
1114                         nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
1115                                                       ntohl(th->seq) + 1);
1116                         break;
1117                 }
1118
1119                 if (!th->syn || th->ack ||
1120                     CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
1121                         break;
1122
1123                 /* Reopened connection - reset the sequence number and timestamp
1124                  * adjustments, they will get initialized once the connection is
1125                  * reestablished.
1126                  */
1127                 nf_ct_seqadj_init(ct, ctinfo, 0);
1128                 synproxy->tsoff = 0;
1129                 this_cpu_inc(snet->stats->conn_reopened);
1130                 fallthrough;
1131         case TCP_CONNTRACK_SYN_SENT:
1132                 if (!synproxy_parse_options(skb, thoff, th, &opts))
1133                         return NF_DROP;
1134
1135                 if (!th->syn && th->ack &&
1136                     CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
1137                         /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
1138                          * therefore we need to add 1 to make the SYN sequence
1139                          * number match the one of first SYN.
1140                          */
1141                         if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
1142                                                           ntohl(th->seq) + 1)) {
1143                                 this_cpu_inc(snet->stats->cookie_retrans);
1144                                 consume_skb(skb);
1145                                 return NF_STOLEN;
1146                         } else {
1147                                 return NF_DROP;
1148                         }
1149                 }
1150
1151                 synproxy->isn = ntohl(th->ack_seq);
1152                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
1153                         synproxy->its = opts.tsecr;
1154
1155                 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1156                 break;
1157         case TCP_CONNTRACK_SYN_RECV:
1158                 if (!th->syn || !th->ack)
1159                         break;
1160
1161                 if (!synproxy_parse_options(skb, thoff, th, &opts))
1162                         return NF_DROP;
1163
1164                 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
1165                         synproxy->tsoff = opts.tsval - synproxy->its;
1166                         nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1167                 }
1168
1169                 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
1170                                   NF_SYNPROXY_OPT_WSCALE |
1171                                   NF_SYNPROXY_OPT_SACK_PERM);
1172
1173                 swap(opts.tsval, opts.tsecr);
1174                 synproxy_send_server_ack_ipv6(net, state, skb, th, &opts);
1175
1176                 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
1177                 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
1178
1179                 swap(opts.tsval, opts.tsecr);
1180                 synproxy_send_client_ack_ipv6(net, skb, th, &opts);
1181
1182                 consume_skb(skb);
1183                 return NF_STOLEN;
1184         default:
1185                 break;
1186         }
1187
1188         synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
1189         return NF_ACCEPT;
1190 }
1191 EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
1192
1193 static const struct nf_hook_ops ipv6_synproxy_ops[] = {
1194         {
1195                 .hook           = ipv6_synproxy_hook,
1196                 .pf             = NFPROTO_IPV6,
1197                 .hooknum        = NF_INET_LOCAL_IN,
1198                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1199         },
1200         {
1201                 .hook           = ipv6_synproxy_hook,
1202                 .pf             = NFPROTO_IPV6,
1203                 .hooknum        = NF_INET_POST_ROUTING,
1204                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1205         },
1206 };
1207
1208 int
1209 nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
1210 {
1211         int err;
1212
1213         if (snet->hook_ref6 == 0) {
1214                 err = nf_register_net_hooks(net, ipv6_synproxy_ops,
1215                                             ARRAY_SIZE(ipv6_synproxy_ops));
1216                 if (err)
1217                         return err;
1218         }
1219
1220         snet->hook_ref6++;
1221         return 0;
1222 }
1223 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
1224
1225 void
1226 nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
1227 {
1228         snet->hook_ref6--;
1229         if (snet->hook_ref6 == 0)
1230                 nf_unregister_net_hooks(net, ipv6_synproxy_ops,
1231                                         ARRAY_SIZE(ipv6_synproxy_ops));
1232 }
1233 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
1234 #endif /* CONFIG_IPV6 */
1235
1236 MODULE_LICENSE("GPL");
1237 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
1238 MODULE_DESCRIPTION("nftables SYNPROXY expression support");