linux/net/netfilter/nf_synproxy_core.c
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   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
  24unsigned int synproxy_net_id;
  25EXPORT_SYMBOL_GPL(synproxy_net_id);
  26
  27bool
  28synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
  29                       const struct tcphdr *th, struct synproxy_options *opts)
  30{
  31        int length = (th->doff * 4) - sizeof(*th);
  32        u8 buf[40], *ptr;
  33
  34        if (unlikely(length < 0))
  35                return false;
  36
  37        ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
  38        if (ptr == NULL)
  39                return false;
  40
  41        opts->options = 0;
  42        while (length > 0) {
  43                int opcode = *ptr++;
  44                int opsize;
  45
  46                switch (opcode) {
  47                case TCPOPT_EOL:
  48                        return true;
  49                case TCPOPT_NOP:
  50                        length--;
  51                        continue;
  52                default:
  53                        if (length < 2)
  54                                return true;
  55                        opsize = *ptr++;
  56                        if (opsize < 2)
  57                                return true;
  58                        if (opsize > length)
  59                                return true;
  60
  61                        switch (opcode) {
  62                        case TCPOPT_MSS:
  63                                if (opsize == TCPOLEN_MSS) {
  64                                        opts->mss_option = get_unaligned_be16(ptr);
  65                                        opts->options |= NF_SYNPROXY_OPT_MSS;
  66                                }
  67                                break;
  68                        case TCPOPT_WINDOW:
  69                                if (opsize == TCPOLEN_WINDOW) {
  70                                        opts->wscale = *ptr;
  71                                        if (opts->wscale > TCP_MAX_WSCALE)
  72                                                opts->wscale = TCP_MAX_WSCALE;
  73                                        opts->options |= NF_SYNPROXY_OPT_WSCALE;
  74                                }
  75                                break;
  76                        case TCPOPT_TIMESTAMP:
  77                                if (opsize == TCPOLEN_TIMESTAMP) {
  78                                        opts->tsval = get_unaligned_be32(ptr);
  79                                        opts->tsecr = get_unaligned_be32(ptr + 4);
  80                                        opts->options |= NF_SYNPROXY_OPT_TIMESTAMP;
  81                                }
  82                                break;
  83                        case TCPOPT_SACK_PERM:
  84                                if (opsize == TCPOLEN_SACK_PERM)
  85                                        opts->options |= NF_SYNPROXY_OPT_SACK_PERM;
  86                                break;
  87                        }
  88
  89                        ptr += opsize - 2;
  90                        length -= opsize;
  91                }
  92        }
  93        return true;
  94}
  95EXPORT_SYMBOL_GPL(synproxy_parse_options);
  96
  97static unsigned int
  98synproxy_options_size(const struct synproxy_options *opts)
  99{
 100        unsigned int size = 0;
 101
 102        if (opts->options & NF_SYNPROXY_OPT_MSS)
 103                size += TCPOLEN_MSS_ALIGNED;
 104        if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
 105                size += TCPOLEN_TSTAMP_ALIGNED;
 106        else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
 107                size += TCPOLEN_SACKPERM_ALIGNED;
 108        if (opts->options & NF_SYNPROXY_OPT_WSCALE)
 109                size += TCPOLEN_WSCALE_ALIGNED;
 110
 111        return size;
 112}
 113
 114static void
 115synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
 116{
 117        __be32 *ptr = (__be32 *)(th + 1);
 118        u8 options = opts->options;
 119
 120        if (options & NF_SYNPROXY_OPT_MSS)
 121                *ptr++ = htonl((TCPOPT_MSS << 24) |
 122                               (TCPOLEN_MSS << 16) |
 123                               opts->mss_option);
 124
 125        if (options & NF_SYNPROXY_OPT_TIMESTAMP) {
 126                if (options & NF_SYNPROXY_OPT_SACK_PERM)
 127                        *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
 128                                       (TCPOLEN_SACK_PERM << 16) |
 129                                       (TCPOPT_TIMESTAMP << 8) |
 130                                       TCPOLEN_TIMESTAMP);
 131                else
 132                        *ptr++ = htonl((TCPOPT_NOP << 24) |
 133                                       (TCPOPT_NOP << 16) |
 134                                       (TCPOPT_TIMESTAMP << 8) |
 135                                       TCPOLEN_TIMESTAMP);
 136
 137                *ptr++ = htonl(opts->tsval);
 138                *ptr++ = htonl(opts->tsecr);
 139        } else if (options & NF_SYNPROXY_OPT_SACK_PERM)
 140                *ptr++ = htonl((TCPOPT_NOP << 24) |
 141                               (TCPOPT_NOP << 16) |
 142                               (TCPOPT_SACK_PERM << 8) |
 143                               TCPOLEN_SACK_PERM);
 144
 145        if (options & NF_SYNPROXY_OPT_WSCALE)
 146                *ptr++ = htonl((TCPOPT_NOP << 24) |
 147                               (TCPOPT_WINDOW << 16) |
 148                               (TCPOLEN_WINDOW << 8) |
 149                               opts->wscale);
 150}
 151
 152void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
 153                                    struct synproxy_options *opts)
 154{
 155        opts->tsecr = opts->tsval;
 156        opts->tsval = tcp_time_stamp_raw() & ~0x3f;
 157
 158        if (opts->options & NF_SYNPROXY_OPT_WSCALE) {
 159                opts->tsval |= opts->wscale;
 160                opts->wscale = info->wscale;
 161        } else
 162                opts->tsval |= 0xf;
 163
 164        if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
 165                opts->tsval |= 1 << 4;
 166
 167        if (opts->options & NF_SYNPROXY_OPT_ECN)
 168                opts->tsval |= 1 << 5;
 169}
 170EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
 171
 172static void
 173synproxy_check_timestamp_cookie(struct synproxy_options *opts)
 174{
 175        opts->wscale = opts->tsecr & 0xf;
 176        if (opts->wscale != 0xf)
 177                opts->options |= NF_SYNPROXY_OPT_WSCALE;
 178
 179        opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0;
 180
 181        opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0;
 182}
 183
 184static unsigned int
 185synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
 186                       struct tcphdr *th, struct nf_conn *ct,
 187                       enum ip_conntrack_info ctinfo,
 188                       const struct nf_conn_synproxy *synproxy)
 189{
 190        unsigned int optoff, optend;
 191        __be32 *ptr, old;
 192
 193        if (synproxy->tsoff == 0)
 194                return 1;
 195
 196        optoff = protoff + sizeof(struct tcphdr);
 197        optend = protoff + th->doff * 4;
 198
 199        if (skb_ensure_writable(skb, optend))
 200                return 0;
 201
 202        while (optoff < optend) {
 203                unsigned char *op = skb->data + optoff;
 204
 205                switch (op[0]) {
 206                case TCPOPT_EOL:
 207                        return 1;
 208                case TCPOPT_NOP:
 209                        optoff++;
 210                        continue;
 211                default:
 212                        if (optoff + 1 == optend ||
 213                            optoff + op[1] > optend ||
 214                            op[1] < 2)
 215                                return 0;
 216                        if (op[0] == TCPOPT_TIMESTAMP &&
 217                            op[1] == TCPOLEN_TIMESTAMP) {
 218                                if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 219                                        ptr = (__be32 *)&op[2];
 220                                        old = *ptr;
 221                                        *ptr = htonl(ntohl(*ptr) -
 222                                                     synproxy->tsoff);
 223                                } else {
 224                                        ptr = (__be32 *)&op[6];
 225                                        old = *ptr;
 226                                        *ptr = htonl(ntohl(*ptr) +
 227                                                     synproxy->tsoff);
 228                                }
 229                                inet_proto_csum_replace4(&th->check, skb,
 230                                                         old, *ptr, false);
 231                                return 1;
 232                        }
 233                        optoff += op[1];
 234                }
 235        }
 236        return 1;
 237}
 238
 239static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = {
 240        .len            = sizeof(struct nf_conn_synproxy),
 241        .align          = __alignof__(struct nf_conn_synproxy),
 242        .id             = NF_CT_EXT_SYNPROXY,
 243};
 244
 245#ifdef CONFIG_PROC_FS
 246static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 247{
 248        struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
 249        int cpu;
 250
 251        if (*pos == 0)
 252                return SEQ_START_TOKEN;
 253
 254        for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
 255                if (!cpu_possible(cpu))
 256                        continue;
 257                *pos = cpu + 1;
 258                return per_cpu_ptr(snet->stats, cpu);
 259        }
 260
 261        return NULL;
 262}
 263
 264static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 265{
 266        struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
 267        int cpu;
 268
 269        for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
 270                if (!cpu_possible(cpu))
 271                        continue;
 272                *pos = cpu + 1;
 273                return per_cpu_ptr(snet->stats, cpu);
 274        }
 275        (*pos)++;
 276        return NULL;
 277}
 278
 279static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
 280{
 281        return;
 282}
 283
 284static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
 285{
 286        struct synproxy_stats *stats = v;
 287
 288        if (v == SEQ_START_TOKEN) {
 289                seq_puts(seq, "entries\t\tsyn_received\t"
 290                              "cookie_invalid\tcookie_valid\t"
 291                              "cookie_retrans\tconn_reopened\n");
 292                return 0;
 293        }
 294
 295        seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
 296                   stats->syn_received,
 297                   stats->cookie_invalid,
 298                   stats->cookie_valid,
 299                   stats->cookie_retrans,
 300                   stats->conn_reopened);
 301
 302        return 0;
 303}
 304
 305static const struct seq_operations synproxy_cpu_seq_ops = {
 306        .start          = synproxy_cpu_seq_start,
 307        .next           = synproxy_cpu_seq_next,
 308        .stop           = synproxy_cpu_seq_stop,
 309        .show           = synproxy_cpu_seq_show,
 310};
 311
 312static int __net_init synproxy_proc_init(struct net *net)
 313{
 314        if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
 315                        &synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
 316                return -ENOMEM;
 317        return 0;
 318}
 319
 320static void __net_exit synproxy_proc_exit(struct net *net)
 321{
 322        remove_proc_entry("synproxy", net->proc_net_stat);
 323}
 324#else
 325static int __net_init synproxy_proc_init(struct net *net)
 326{
 327        return 0;
 328}
 329
 330static void __net_exit synproxy_proc_exit(struct net *net)
 331{
 332        return;
 333}
 334#endif /* CONFIG_PROC_FS */
 335
 336static int __net_init synproxy_net_init(struct net *net)
 337{
 338        struct synproxy_net *snet = synproxy_pernet(net);
 339        struct nf_conn *ct;
 340        int err = -ENOMEM;
 341
 342        ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
 343        if (!ct)
 344                goto err1;
 345
 346        if (!nfct_seqadj_ext_add(ct))
 347                goto err2;
 348        if (!nfct_synproxy_ext_add(ct))
 349                goto err2;
 350
 351        __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 352        nf_conntrack_get(&ct->ct_general);
 353        snet->tmpl = ct;
 354
 355        snet->stats = alloc_percpu(struct synproxy_stats);
 356        if (snet->stats == NULL)
 357                goto err2;
 358
 359        err = synproxy_proc_init(net);
 360        if (err < 0)
 361                goto err3;
 362
 363        return 0;
 364
 365err3:
 366        free_percpu(snet->stats);
 367err2:
 368        nf_ct_tmpl_free(ct);
 369err1:
 370        return err;
 371}
 372
 373static void __net_exit synproxy_net_exit(struct net *net)
 374{
 375        struct synproxy_net *snet = synproxy_pernet(net);
 376
 377        nf_ct_put(snet->tmpl);
 378        synproxy_proc_exit(net);
 379        free_percpu(snet->stats);
 380}
 381
 382static struct pernet_operations synproxy_net_ops = {
 383        .init           = synproxy_net_init,
 384        .exit           = synproxy_net_exit,
 385        .id             = &synproxy_net_id,
 386        .size           = sizeof(struct synproxy_net),
 387};
 388
 389static int __init synproxy_core_init(void)
 390{
 391        int err;
 392
 393        err = nf_ct_extend_register(&nf_ct_synproxy_extend);
 394        if (err < 0)
 395                goto err1;
 396
 397        err = register_pernet_subsys(&synproxy_net_ops);
 398        if (err < 0)
 399                goto err2;
 400
 401        return 0;
 402
 403err2:
 404        nf_ct_extend_unregister(&nf_ct_synproxy_extend);
 405err1:
 406        return err;
 407}
 408
 409static void __exit synproxy_core_exit(void)
 410{
 411        unregister_pernet_subsys(&synproxy_net_ops);
 412        nf_ct_extend_unregister(&nf_ct_synproxy_extend);
 413}
 414
 415module_init(synproxy_core_init);
 416module_exit(synproxy_core_exit);
 417
 418static struct iphdr *
 419synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
 420                  __be32 daddr)
 421{
 422        struct iphdr *iph;
 423
 424        skb_reset_network_header(skb);
 425        iph = skb_put(skb, sizeof(*iph));
 426        iph->version    = 4;
 427        iph->ihl        = sizeof(*iph) / 4;
 428        iph->tos        = 0;
 429        iph->id         = 0;
 430        iph->frag_off   = htons(IP_DF);
 431        iph->ttl        = net->ipv4.sysctl_ip_default_ttl;
 432        iph->protocol   = IPPROTO_TCP;
 433        iph->check      = 0;
 434        iph->saddr      = saddr;
 435        iph->daddr      = daddr;
 436
 437        return iph;
 438}
 439
 440static void
 441synproxy_send_tcp(struct net *net,
 442                  const struct sk_buff *skb, struct sk_buff *nskb,
 443                  struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 444                  struct iphdr *niph, struct tcphdr *nth,
 445                  unsigned int tcp_hdr_size)
 446{
 447        nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0);
 448        nskb->ip_summed   = CHECKSUM_PARTIAL;
 449        nskb->csum_start  = (unsigned char *)nth - nskb->head;
 450        nskb->csum_offset = offsetof(struct tcphdr, check);
 451
 452        skb_dst_set_noref(nskb, skb_dst(skb));
 453        nskb->protocol = htons(ETH_P_IP);
 454        if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC))
 455                goto free_nskb;
 456
 457        if (nfct) {
 458                nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 459                nf_conntrack_get(nfct);
 460        }
 461
 462        ip_local_out(net, nskb->sk, nskb);
 463        return;
 464
 465free_nskb:
 466        kfree_skb(nskb);
 467}
 468
 469void
 470synproxy_send_client_synack(struct net *net,
 471                            const struct sk_buff *skb, const struct tcphdr *th,
 472                            const struct synproxy_options *opts)
 473{
 474        struct sk_buff *nskb;
 475        struct iphdr *iph, *niph;
 476        struct tcphdr *nth;
 477        unsigned int tcp_hdr_size;
 478        u16 mss = opts->mss_encode;
 479
 480        iph = ip_hdr(skb);
 481
 482        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 483        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 484                         GFP_ATOMIC);
 485        if (!nskb)
 486                return;
 487        skb_reserve(nskb, MAX_TCP_HEADER);
 488
 489        niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
 490
 491        skb_reset_transport_header(nskb);
 492        nth = skb_put(nskb, tcp_hdr_size);
 493        nth->source     = th->dest;
 494        nth->dest       = th->source;
 495        nth->seq        = htonl(__cookie_v4_init_sequence(iph, th, &mss));
 496        nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 497        tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 498        if (opts->options & NF_SYNPROXY_OPT_ECN)
 499                tcp_flag_word(nth) |= TCP_FLAG_ECE;
 500        nth->doff       = tcp_hdr_size / 4;
 501        nth->window     = 0;
 502        nth->check      = 0;
 503        nth->urg_ptr    = 0;
 504
 505        synproxy_build_options(nth, opts);
 506
 507        synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
 508                          IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
 509}
 510EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
 511
 512static void
 513synproxy_send_server_syn(struct net *net,
 514                         const struct sk_buff *skb, const struct tcphdr *th,
 515                         const struct synproxy_options *opts, u32 recv_seq)
 516{
 517        struct synproxy_net *snet = synproxy_pernet(net);
 518        struct sk_buff *nskb;
 519        struct iphdr *iph, *niph;
 520        struct tcphdr *nth;
 521        unsigned int tcp_hdr_size;
 522
 523        iph = ip_hdr(skb);
 524
 525        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 526        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 527                         GFP_ATOMIC);
 528        if (!nskb)
 529                return;
 530        skb_reserve(nskb, MAX_TCP_HEADER);
 531
 532        niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
 533
 534        skb_reset_transport_header(nskb);
 535        nth = skb_put(nskb, tcp_hdr_size);
 536        nth->source     = th->source;
 537        nth->dest       = th->dest;
 538        nth->seq        = htonl(recv_seq - 1);
 539        /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 540         * sequence number translation once a connection tracking entry exists.
 541         */
 542        nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 543        tcp_flag_word(nth) = TCP_FLAG_SYN;
 544        if (opts->options & NF_SYNPROXY_OPT_ECN)
 545                tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 546        nth->doff       = tcp_hdr_size / 4;
 547        nth->window     = th->window;
 548        nth->check      = 0;
 549        nth->urg_ptr    = 0;
 550
 551        synproxy_build_options(nth, opts);
 552
 553        synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
 554                          niph, nth, tcp_hdr_size);
 555}
 556
 557static void
 558synproxy_send_server_ack(struct net *net,
 559                         const struct ip_ct_tcp *state,
 560                         const struct sk_buff *skb, const struct tcphdr *th,
 561                         const struct synproxy_options *opts)
 562{
 563        struct sk_buff *nskb;
 564        struct iphdr *iph, *niph;
 565        struct tcphdr *nth;
 566        unsigned int tcp_hdr_size;
 567
 568        iph = ip_hdr(skb);
 569
 570        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 571        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 572                         GFP_ATOMIC);
 573        if (!nskb)
 574                return;
 575        skb_reserve(nskb, MAX_TCP_HEADER);
 576
 577        niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
 578
 579        skb_reset_transport_header(nskb);
 580        nth = skb_put(nskb, tcp_hdr_size);
 581        nth->source     = th->dest;
 582        nth->dest       = th->source;
 583        nth->seq        = htonl(ntohl(th->ack_seq));
 584        nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 585        tcp_flag_word(nth) = TCP_FLAG_ACK;
 586        nth->doff       = tcp_hdr_size / 4;
 587        nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
 588        nth->check      = 0;
 589        nth->urg_ptr    = 0;
 590
 591        synproxy_build_options(nth, opts);
 592
 593        synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
 594}
 595
 596static void
 597synproxy_send_client_ack(struct net *net,
 598                         const struct sk_buff *skb, const struct tcphdr *th,
 599                         const struct synproxy_options *opts)
 600{
 601        struct sk_buff *nskb;
 602        struct iphdr *iph, *niph;
 603        struct tcphdr *nth;
 604        unsigned int tcp_hdr_size;
 605
 606        iph = ip_hdr(skb);
 607
 608        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 609        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 610                         GFP_ATOMIC);
 611        if (!nskb)
 612                return;
 613        skb_reserve(nskb, MAX_TCP_HEADER);
 614
 615        niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
 616
 617        skb_reset_transport_header(nskb);
 618        nth = skb_put(nskb, tcp_hdr_size);
 619        nth->source     = th->source;
 620        nth->dest       = th->dest;
 621        nth->seq        = htonl(ntohl(th->seq) + 1);
 622        nth->ack_seq    = th->ack_seq;
 623        tcp_flag_word(nth) = TCP_FLAG_ACK;
 624        nth->doff       = tcp_hdr_size / 4;
 625        nth->window     = htons(ntohs(th->window) >> opts->wscale);
 626        nth->check      = 0;
 627        nth->urg_ptr    = 0;
 628
 629        synproxy_build_options(nth, opts);
 630
 631        synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
 632                          IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
 633}
 634
 635bool
 636synproxy_recv_client_ack(struct net *net,
 637                         const struct sk_buff *skb, const struct tcphdr *th,
 638                         struct synproxy_options *opts, u32 recv_seq)
 639{
 640        struct synproxy_net *snet = synproxy_pernet(net);
 641        int mss;
 642
 643        mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1);
 644        if (mss == 0) {
 645                this_cpu_inc(snet->stats->cookie_invalid);
 646                return false;
 647        }
 648
 649        this_cpu_inc(snet->stats->cookie_valid);
 650        opts->mss_option = mss;
 651        opts->options |= NF_SYNPROXY_OPT_MSS;
 652
 653        if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
 654                synproxy_check_timestamp_cookie(opts);
 655
 656        synproxy_send_server_syn(net, skb, th, opts, recv_seq);
 657        return true;
 658}
 659EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
 660
 661unsigned int
 662ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
 663                   const struct nf_hook_state *nhs)
 664{
 665        struct net *net = nhs->net;
 666        struct synproxy_net *snet = synproxy_pernet(net);
 667        enum ip_conntrack_info ctinfo;
 668        struct nf_conn *ct;
 669        struct nf_conn_synproxy *synproxy;
 670        struct synproxy_options opts = {};
 671        const struct ip_ct_tcp *state;
 672        struct tcphdr *th, _th;
 673        unsigned int thoff;
 674
 675        ct = nf_ct_get(skb, &ctinfo);
 676        if (!ct)
 677                return NF_ACCEPT;
 678
 679        synproxy = nfct_synproxy(ct);
 680        if (!synproxy)
 681                return NF_ACCEPT;
 682
 683        if (nf_is_loopback_packet(skb) ||
 684            ip_hdr(skb)->protocol != IPPROTO_TCP)
 685                return NF_ACCEPT;
 686
 687        thoff = ip_hdrlen(skb);
 688        th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
 689        if (!th)
 690                return NF_DROP;
 691
 692        state = &ct->proto.tcp;
 693        switch (state->state) {
 694        case TCP_CONNTRACK_CLOSE:
 695                if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
 696                        nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
 697                                                      ntohl(th->seq) + 1);
 698                        break;
 699                }
 700
 701                if (!th->syn || th->ack ||
 702                    CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
 703                        break;
 704
 705                /* Reopened connection - reset the sequence number and timestamp
 706                 * adjustments, they will get initialized once the connection is
 707                 * reestablished.
 708                 */
 709                nf_ct_seqadj_init(ct, ctinfo, 0);
 710                synproxy->tsoff = 0;
 711                this_cpu_inc(snet->stats->conn_reopened);
 712                fallthrough;
 713        case TCP_CONNTRACK_SYN_SENT:
 714                if (!synproxy_parse_options(skb, thoff, th, &opts))
 715                        return NF_DROP;
 716
 717                if (!th->syn && th->ack &&
 718                    CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
 719                        /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
 720                         * therefore we need to add 1 to make the SYN sequence
 721                         * number match the one of first SYN.
 722                         */
 723                        if (synproxy_recv_client_ack(net, skb, th, &opts,
 724                                                     ntohl(th->seq) + 1)) {
 725                                this_cpu_inc(snet->stats->cookie_retrans);
 726                                consume_skb(skb);
 727                                return NF_STOLEN;
 728                        } else {
 729                                return NF_DROP;
 730                        }
 731                }
 732
 733                synproxy->isn = ntohl(th->ack_seq);
 734                if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
 735                        synproxy->its = opts.tsecr;
 736
 737                nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 738                break;
 739        case TCP_CONNTRACK_SYN_RECV:
 740                if (!th->syn || !th->ack)
 741                        break;
 742
 743                if (!synproxy_parse_options(skb, thoff, th, &opts))
 744                        return NF_DROP;
 745
 746                if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
 747                        synproxy->tsoff = opts.tsval - synproxy->its;
 748                        nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
 749                }
 750
 751                opts.options &= ~(NF_SYNPROXY_OPT_MSS |
 752                                  NF_SYNPROXY_OPT_WSCALE |
 753                                  NF_SYNPROXY_OPT_SACK_PERM);
 754
 755                swap(opts.tsval, opts.tsecr);
 756                synproxy_send_server_ack(net, state, skb, th, &opts);
 757
 758                nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
 759                nf_conntrack_event_cache(IPCT_SEQADJ, ct);
 760
 761                swap(opts.tsval, opts.tsecr);
 762                synproxy_send_client_ack(net, skb, th, &opts);
 763
 764                consume_skb(skb);
 765                return NF_STOLEN;
 766        default:
 767                break;
 768        }
 769
 770        synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
 771        return NF_ACCEPT;
 772}
 773EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
 774
 775static const struct nf_hook_ops ipv4_synproxy_ops[] = {
 776        {
 777                .hook           = ipv4_synproxy_hook,
 778                .pf             = NFPROTO_IPV4,
 779                .hooknum        = NF_INET_LOCAL_IN,
 780                .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 781        },
 782        {
 783                .hook           = ipv4_synproxy_hook,
 784                .pf             = NFPROTO_IPV4,
 785                .hooknum        = NF_INET_POST_ROUTING,
 786                .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
 787        },
 788};
 789
 790int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
 791{
 792        int err;
 793
 794        if (snet->hook_ref4 == 0) {
 795                err = nf_register_net_hooks(net, ipv4_synproxy_ops,
 796                                            ARRAY_SIZE(ipv4_synproxy_ops));
 797                if (err)
 798                        return err;
 799        }
 800
 801        snet->hook_ref4++;
 802        return 0;
 803}
 804EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
 805
 806void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
 807{
 808        snet->hook_ref4--;
 809        if (snet->hook_ref4 == 0)
 810                nf_unregister_net_hooks(net, ipv4_synproxy_ops,
 811                                        ARRAY_SIZE(ipv4_synproxy_ops));
 812}
 813EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
 814
 815#if IS_ENABLED(CONFIG_IPV6)
 816static struct ipv6hdr *
 817synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
 818                       const struct in6_addr *saddr,
 819                       const struct in6_addr *daddr)
 820{
 821        struct ipv6hdr *iph;
 822
 823        skb_reset_network_header(skb);
 824        iph = skb_put(skb, sizeof(*iph));
 825        ip6_flow_hdr(iph, 0, 0);
 826        iph->hop_limit  = net->ipv6.devconf_all->hop_limit;
 827        iph->nexthdr    = IPPROTO_TCP;
 828        iph->saddr      = *saddr;
 829        iph->daddr      = *daddr;
 830
 831        return iph;
 832}
 833
 834static void
 835synproxy_send_tcp_ipv6(struct net *net,
 836                       const struct sk_buff *skb, struct sk_buff *nskb,
 837                       struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
 838                       struct ipv6hdr *niph, struct tcphdr *nth,
 839                       unsigned int tcp_hdr_size)
 840{
 841        struct dst_entry *dst;
 842        struct flowi6 fl6;
 843        int err;
 844
 845        nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
 846        nskb->ip_summed   = CHECKSUM_PARTIAL;
 847        nskb->csum_start  = (unsigned char *)nth - nskb->head;
 848        nskb->csum_offset = offsetof(struct tcphdr, check);
 849
 850        memset(&fl6, 0, sizeof(fl6));
 851        fl6.flowi6_proto = IPPROTO_TCP;
 852        fl6.saddr = niph->saddr;
 853        fl6.daddr = niph->daddr;
 854        fl6.fl6_sport = nth->source;
 855        fl6.fl6_dport = nth->dest;
 856        security_skb_classify_flow((struct sk_buff *)skb,
 857                                   flowi6_to_flowi_common(&fl6));
 858        err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
 859        if (err) {
 860                goto free_nskb;
 861        }
 862
 863        dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
 864        if (IS_ERR(dst))
 865                goto free_nskb;
 866
 867        skb_dst_set(nskb, dst);
 868
 869        if (nfct) {
 870                nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
 871                nf_conntrack_get(nfct);
 872        }
 873
 874        ip6_local_out(net, nskb->sk, nskb);
 875        return;
 876
 877free_nskb:
 878        kfree_skb(nskb);
 879}
 880
 881void
 882synproxy_send_client_synack_ipv6(struct net *net,
 883                                 const struct sk_buff *skb,
 884                                 const struct tcphdr *th,
 885                                 const struct synproxy_options *opts)
 886{
 887        struct sk_buff *nskb;
 888        struct ipv6hdr *iph, *niph;
 889        struct tcphdr *nth;
 890        unsigned int tcp_hdr_size;
 891        u16 mss = opts->mss_encode;
 892
 893        iph = ipv6_hdr(skb);
 894
 895        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 896        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 897                         GFP_ATOMIC);
 898        if (!nskb)
 899                return;
 900        skb_reserve(nskb, MAX_TCP_HEADER);
 901
 902        niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 903
 904        skb_reset_transport_header(nskb);
 905        nth = skb_put(nskb, tcp_hdr_size);
 906        nth->source     = th->dest;
 907        nth->dest       = th->source;
 908        nth->seq        = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss));
 909        nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 910        tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
 911        if (opts->options & NF_SYNPROXY_OPT_ECN)
 912                tcp_flag_word(nth) |= TCP_FLAG_ECE;
 913        nth->doff       = tcp_hdr_size / 4;
 914        nth->window     = 0;
 915        nth->check      = 0;
 916        nth->urg_ptr    = 0;
 917
 918        synproxy_build_options(nth, opts);
 919
 920        synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
 921                               IP_CT_ESTABLISHED_REPLY, niph, nth,
 922                               tcp_hdr_size);
 923}
 924EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
 925
 926static void
 927synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb,
 928                              const struct tcphdr *th,
 929                              const struct synproxy_options *opts, u32 recv_seq)
 930{
 931        struct synproxy_net *snet = synproxy_pernet(net);
 932        struct sk_buff *nskb;
 933        struct ipv6hdr *iph, *niph;
 934        struct tcphdr *nth;
 935        unsigned int tcp_hdr_size;
 936
 937        iph = ipv6_hdr(skb);
 938
 939        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 940        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 941                         GFP_ATOMIC);
 942        if (!nskb)
 943                return;
 944        skb_reserve(nskb, MAX_TCP_HEADER);
 945
 946        niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
 947
 948        skb_reset_transport_header(nskb);
 949        nth = skb_put(nskb, tcp_hdr_size);
 950        nth->source     = th->source;
 951        nth->dest       = th->dest;
 952        nth->seq        = htonl(recv_seq - 1);
 953        /* ack_seq is used to relay our ISN to the synproxy hook to initialize
 954         * sequence number translation once a connection tracking entry exists.
 955         */
 956        nth->ack_seq    = htonl(ntohl(th->ack_seq) - 1);
 957        tcp_flag_word(nth) = TCP_FLAG_SYN;
 958        if (opts->options & NF_SYNPROXY_OPT_ECN)
 959                tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
 960        nth->doff       = tcp_hdr_size / 4;
 961        nth->window     = th->window;
 962        nth->check      = 0;
 963        nth->urg_ptr    = 0;
 964
 965        synproxy_build_options(nth, opts);
 966
 967        synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
 968                               IP_CT_NEW, niph, nth, tcp_hdr_size);
 969}
 970
 971static void
 972synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state,
 973                              const struct sk_buff *skb,
 974                              const struct tcphdr *th,
 975                              const struct synproxy_options *opts)
 976{
 977        struct sk_buff *nskb;
 978        struct ipv6hdr *iph, *niph;
 979        struct tcphdr *nth;
 980        unsigned int tcp_hdr_size;
 981
 982        iph = ipv6_hdr(skb);
 983
 984        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
 985        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
 986                         GFP_ATOMIC);
 987        if (!nskb)
 988                return;
 989        skb_reserve(nskb, MAX_TCP_HEADER);
 990
 991        niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
 992
 993        skb_reset_transport_header(nskb);
 994        nth = skb_put(nskb, tcp_hdr_size);
 995        nth->source     = th->dest;
 996        nth->dest       = th->source;
 997        nth->seq        = htonl(ntohl(th->ack_seq));
 998        nth->ack_seq    = htonl(ntohl(th->seq) + 1);
 999        tcp_flag_word(nth) = TCP_FLAG_ACK;
1000        nth->doff       = tcp_hdr_size / 4;
1001        nth->window     = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
1002        nth->check      = 0;
1003        nth->urg_ptr    = 0;
1004
1005        synproxy_build_options(nth, opts);
1006
1007        synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth,
1008                               tcp_hdr_size);
1009}
1010
1011static void
1012synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
1013                              const struct tcphdr *th,
1014                              const struct synproxy_options *opts)
1015{
1016        struct sk_buff *nskb;
1017        struct ipv6hdr *iph, *niph;
1018        struct tcphdr *nth;
1019        unsigned int tcp_hdr_size;
1020
1021        iph = ipv6_hdr(skb);
1022
1023        tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
1024        nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
1025                         GFP_ATOMIC);
1026        if (!nskb)
1027                return;
1028        skb_reserve(nskb, MAX_TCP_HEADER);
1029
1030        niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
1031
1032        skb_reset_transport_header(nskb);
1033        nth = skb_put(nskb, tcp_hdr_size);
1034        nth->source     = th->source;
1035        nth->dest       = th->dest;
1036        nth->seq        = htonl(ntohl(th->seq) + 1);
1037        nth->ack_seq    = th->ack_seq;
1038        tcp_flag_word(nth) = TCP_FLAG_ACK;
1039        nth->doff       = tcp_hdr_size / 4;
1040        nth->window     = htons(ntohs(th->window) >> opts->wscale);
1041        nth->check      = 0;
1042        nth->urg_ptr    = 0;
1043
1044        synproxy_build_options(nth, opts);
1045
1046        synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
1047                               IP_CT_ESTABLISHED_REPLY, niph, nth,
1048                               tcp_hdr_size);
1049}
1050
1051bool
1052synproxy_recv_client_ack_ipv6(struct net *net,
1053                              const struct sk_buff *skb,
1054                              const struct tcphdr *th,
1055                              struct synproxy_options *opts, u32 recv_seq)
1056{
1057        struct synproxy_net *snet = synproxy_pernet(net);
1058        int mss;
1059
1060        mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
1061        if (mss == 0) {
1062                this_cpu_inc(snet->stats->cookie_invalid);
1063                return false;
1064        }
1065
1066        this_cpu_inc(snet->stats->cookie_valid);
1067        opts->mss_option = mss;
1068        opts->options |= NF_SYNPROXY_OPT_MSS;
1069
1070        if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
1071                synproxy_check_timestamp_cookie(opts);
1072
1073        synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
1074        return true;
1075}
1076EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
1077
1078unsigned int
1079ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
1080                   const struct nf_hook_state *nhs)
1081{
1082        struct net *net = nhs->net;
1083        struct synproxy_net *snet = synproxy_pernet(net);
1084        enum ip_conntrack_info ctinfo;
1085        struct nf_conn *ct;
1086        struct nf_conn_synproxy *synproxy;
1087        struct synproxy_options opts = {};
1088        const struct ip_ct_tcp *state;
1089        struct tcphdr *th, _th;
1090        __be16 frag_off;
1091        u8 nexthdr;
1092        int thoff;
1093
1094        ct = nf_ct_get(skb, &ctinfo);
1095        if (!ct)
1096                return NF_ACCEPT;
1097
1098        synproxy = nfct_synproxy(ct);
1099        if (!synproxy)
1100                return NF_ACCEPT;
1101
1102        if (nf_is_loopback_packet(skb))
1103                return NF_ACCEPT;
1104
1105        nexthdr = ipv6_hdr(skb)->nexthdr;
1106        thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
1107                                 &frag_off);
1108        if (thoff < 0 || nexthdr != IPPROTO_TCP)
1109                return NF_ACCEPT;
1110
1111        th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
1112        if (!th)
1113                return NF_DROP;
1114
1115        state = &ct->proto.tcp;
1116        switch (state->state) {
1117        case TCP_CONNTRACK_CLOSE:
1118                if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
1119                        nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
1120                                                      ntohl(th->seq) + 1);
1121                        break;
1122                }
1123
1124                if (!th->syn || th->ack ||
1125                    CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
1126                        break;
1127
1128                /* Reopened connection - reset the sequence number and timestamp
1129                 * adjustments, they will get initialized once the connection is
1130                 * reestablished.
1131                 */
1132                nf_ct_seqadj_init(ct, ctinfo, 0);
1133                synproxy->tsoff = 0;
1134                this_cpu_inc(snet->stats->conn_reopened);
1135                fallthrough;
1136        case TCP_CONNTRACK_SYN_SENT:
1137                if (!synproxy_parse_options(skb, thoff, th, &opts))
1138                        return NF_DROP;
1139
1140                if (!th->syn && th->ack &&
1141                    CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
1142                        /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
1143                         * therefore we need to add 1 to make the SYN sequence
1144                         * number match the one of first SYN.
1145                         */
1146                        if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
1147                                                          ntohl(th->seq) + 1)) {
1148                                this_cpu_inc(snet->stats->cookie_retrans);
1149                                consume_skb(skb);
1150                                return NF_STOLEN;
1151                        } else {
1152                                return NF_DROP;
1153                        }
1154                }
1155
1156                synproxy->isn = ntohl(th->ack_seq);
1157                if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
1158                        synproxy->its = opts.tsecr;
1159
1160                nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1161                break;
1162        case TCP_CONNTRACK_SYN_RECV:
1163                if (!th->syn || !th->ack)
1164                        break;
1165
1166                if (!synproxy_parse_options(skb, thoff, th, &opts))
1167                        return NF_DROP;
1168
1169                if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
1170                        synproxy->tsoff = opts.tsval - synproxy->its;
1171                        nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1172                }
1173
1174                opts.options &= ~(NF_SYNPROXY_OPT_MSS |
1175                                  NF_SYNPROXY_OPT_WSCALE |
1176                                  NF_SYNPROXY_OPT_SACK_PERM);
1177
1178                swap(opts.tsval, opts.tsecr);
1179                synproxy_send_server_ack_ipv6(net, state, skb, th, &opts);
1180
1181                nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
1182                nf_conntrack_event_cache(IPCT_SEQADJ, ct);
1183
1184                swap(opts.tsval, opts.tsecr);
1185                synproxy_send_client_ack_ipv6(net, skb, th, &opts);
1186
1187                consume_skb(skb);
1188                return NF_STOLEN;
1189        default:
1190                break;
1191        }
1192
1193        synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
1194        return NF_ACCEPT;
1195}
1196EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
1197
1198static const struct nf_hook_ops ipv6_synproxy_ops[] = {
1199        {
1200                .hook           = ipv6_synproxy_hook,
1201                .pf             = NFPROTO_IPV6,
1202                .hooknum        = NF_INET_LOCAL_IN,
1203                .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1204        },
1205        {
1206                .hook           = ipv6_synproxy_hook,
1207                .pf             = NFPROTO_IPV6,
1208                .hooknum        = NF_INET_POST_ROUTING,
1209                .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1210        },
1211};
1212
1213int
1214nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
1215{
1216        int err;
1217
1218        if (snet->hook_ref6 == 0) {
1219                err = nf_register_net_hooks(net, ipv6_synproxy_ops,
1220                                            ARRAY_SIZE(ipv6_synproxy_ops));
1221                if (err)
1222                        return err;
1223        }
1224
1225        snet->hook_ref6++;
1226        return 0;
1227}
1228EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
1229
1230void
1231nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
1232{
1233        snet->hook_ref6--;
1234        if (snet->hook_ref6 == 0)
1235                nf_unregister_net_hooks(net, ipv6_synproxy_ops,
1236                                        ARRAY_SIZE(ipv6_synproxy_ops));
1237}
1238EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
1239#endif /* CONFIG_IPV6 */
1240
1241MODULE_LICENSE("GPL");
1242MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
1243MODULE_DESCRIPTION("nftables SYNPROXY expression support");
1244