net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c

   1 /*
   2  * Copyright (C)2004 USAGI/WIDE Project
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Author:
   9  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/ipv6.h>
  14 #include <linux/in6.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/module.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/icmp.h>
  19 #include <net/ipv6.h>
  20 #include <net/inet_frag.h>
  21
  22 #include <linux/netfilter_bridge.h>
  23 #include <linux/netfilter_ipv6.h>
  24 #include <linux/netfilter_ipv6/ip6_tables.h>
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_helper.h>
  27 #include <net/netfilter/nf_conntrack_l4proto.h>
  28 #include <net/netfilter/nf_conntrack_l3proto.h>
  29 #include <net/netfilter/nf_conntrack_core.h>
  30 #include <net/netfilter/nf_conntrack_zones.h>
  31 #include <net/netfilter/nf_conntrack_seqadj.h>
  32 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  33 #include <net/netfilter/nf_nat_helper.h>
  34 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
  35 #include <net/netfilter/nf_log.h>
  36
  37 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  38                               struct nf_conntrack_tuple *tuple)
  39 {
  40         const u_int32_t *ap;
  41         u_int32_t _addrs[8];
  42
  43         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  44                                 sizeof(_addrs), _addrs);
  45         if (ap == NULL)
  46                 return false;
  47
  48         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  49         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  50
  51         return true;
  52 }
  53
  54 static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  55                               const struct nf_conntrack_tuple *orig)
  56 {
  57         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  58         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  59
  60         return true;
  61 }
  62
  63 static int ipv6_print_tuple(struct seq_file *s,
  64                             const struct nf_conntrack_tuple *tuple)
  65 {
  66         return seq_printf(s, "src=%pI6 dst=%pI6 ",
  67                           tuple->src.u3.ip6, tuple->dst.u3.ip6);
  68 }
  69
  70 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
  71                             unsigned int *dataoff, u_int8_t *protonum)
  72 {
  73         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
  74         __be16 frag_off;
  75         int protoff;
  76         u8 nexthdr;
  77
  78         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
  79                           &nexthdr, sizeof(nexthdr)) != 0) {
  80                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
  81                 return -NF_ACCEPT;
  82         }
  83         protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
  84         /*
  85          * (protoff == skb->len) means the packet has not data, just
  86          * IPv6 and possibly extensions headers, but it is tracked anyway
  87          */
  88         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
  89                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
  90                 return -NF_ACCEPT;
  91         }
  92
  93         *dataoff = protoff;
  94         *protonum = nexthdr;
  95         return NF_ACCEPT;
  96 }
  97
  98 static unsigned int ipv6_helper(const struct nf_hook_ops *ops,
  99                                 struct sk_buff *skb,
 100                                 const struct net_device *in,
 101                                 const struct net_device *out,
 102                                 int (*okfn)(struct sk_buff *))
 103 {
 104         struct nf_conn *ct;
 105         const struct nf_conn_help *help;
 106         const struct nf_conntrack_helper *helper;
 107         enum ip_conntrack_info ctinfo;
 108         __be16 frag_off;
 109         int protoff;
 110         u8 nexthdr;
 111
 112         /* This is where we call the helper: as the packet goes out. */
 113         ct = nf_ct_get(skb, &ctinfo);
 114         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 115                 return NF_ACCEPT;
 116
 117         help = nfct_help(ct);
 118         if (!help)
 119                 return NF_ACCEPT;
 120         /* rcu_read_lock()ed by nf_hook_slow */
 121         helper = rcu_dereference(help->helper);
 122         if (!helper)
 123                 return NF_ACCEPT;
 124
 125         nexthdr = ipv6_hdr(skb)->nexthdr;
 126         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
 127                                    &frag_off);
 128         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 129                 pr_debug("proto header not found\n");
 130                 return NF_ACCEPT;
 131         }
 132
 133         return helper->help(skb, protoff, ct, ctinfo);
 134 }
 135
 136 static unsigned int ipv6_confirm(const struct nf_hook_ops *ops,
 137                                  struct sk_buff *skb,
 138                                  const struct net_device *in,
 139                                  const struct net_device *out,
 140                                  int (*okfn)(struct sk_buff *))
 141 {
 142         struct nf_conn *ct;
 143         enum ip_conntrack_info ctinfo;
 144         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 145         int protoff;
 146         __be16 frag_off;
 147
 148         ct = nf_ct_get(skb, &ctinfo);
 149         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 150                 goto out;
 151
 152         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
 153                                    &frag_off);
 154         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 155                 pr_debug("proto header not found\n");
 156                 goto out;
 157         }
 158
 159         /* adjust seqs for loopback traffic only in outgoing direction */
 160         if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
 161             !nf_is_loopback_packet(skb)) {
 162                 if (!nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) {
 163                         NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
 164                         return NF_DROP;
 165                 }
 166         }
 167 out:
 168         /* We've seen it coming out the other side: confirm it */
 169         return nf_conntrack_confirm(skb);
 170 }
 171
 172 static unsigned int __ipv6_conntrack_in(struct net *net,
 173                                         unsigned int hooknum,
 174                                         struct sk_buff *skb,
 175                                         const struct net_device *in,
 176                                         const struct net_device *out,
 177                                         int (*okfn)(struct sk_buff *))
 178 {
 179         struct sk_buff *reasm = skb->nfct_reasm;
 180         const struct nf_conn_help *help;
 181         struct nf_conn *ct;
 182         enum ip_conntrack_info ctinfo;
 183
 184         /* This packet is fragmented and has reassembled packet. */
 185         if (reasm) {
 186                 /* Reassembled packet isn't parsed yet ? */
 187                 if (!reasm->nfct) {
 188                         unsigned int ret;
 189
 190                         ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
 191                         if (ret != NF_ACCEPT)
 192                                 return ret;
 193                 }
 194
 195                 /* Conntrack helpers need the entire reassembled packet in the
 196                  * POST_ROUTING hook. In case of unconfirmed connections NAT
 197                  * might reassign a helper, so the entire packet is also
 198                  * required.
 199                  */
 200                 ct = nf_ct_get(reasm, &ctinfo);
 201                 if (ct != NULL && !nf_ct_is_untracked(ct)) {
 202                         help = nfct_help(ct);
 203                         if ((help && help->helper) || !nf_ct_is_confirmed(ct)) {
 204                                 nf_conntrack_get_reasm(reasm);
 205                                 NF_HOOK_THRESH(NFPROTO_IPV6, hooknum, reasm,
 206                                                (struct net_device *)in,
 207                                                (struct net_device *)out,
 208                                                okfn, NF_IP6_PRI_CONNTRACK + 1);
 209                                 return NF_DROP_ERR(-ECANCELED);
 210                         }
 211                 }
 212
 213                 nf_conntrack_get(reasm->nfct);
 214                 skb->nfct = reasm->nfct;
 215                 skb->nfctinfo = reasm->nfctinfo;
 216                 return NF_ACCEPT;
 217         }
 218
 219         return nf_conntrack_in(net, PF_INET6, hooknum, skb);
 220 }
 221
 222 static unsigned int ipv6_conntrack_in(const struct nf_hook_ops *ops,
 223                                       struct sk_buff *skb,
 224                                       const struct net_device *in,
 225                                       const struct net_device *out,
 226                                       int (*okfn)(struct sk_buff *))
 227 {
 228         return __ipv6_conntrack_in(dev_net(in), ops->hooknum, skb, in, out,
 229                                    okfn);
 230 }
 231
 232 static unsigned int ipv6_conntrack_local(const struct nf_hook_ops *ops,
 233                                          struct sk_buff *skb,
 234                                          const struct net_device *in,
 235                                          const struct net_device *out,
 236                                          int (*okfn)(struct sk_buff *))
 237 {
 238         /* root is playing with raw sockets. */
 239         if (skb->len < sizeof(struct ipv6hdr)) {
 240                 net_notice_ratelimited("ipv6_conntrack_local: packet too short\n");
 241                 return NF_ACCEPT;
 242         }
 243         return __ipv6_conntrack_in(dev_net(out), ops->hooknum, skb, in, out,
 244                                    okfn);
 245 }
 246
 247 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 248         {
 249                 .hook           = ipv6_conntrack_in,
 250                 .owner          = THIS_MODULE,
 251                 .pf             = NFPROTO_IPV6,
 252                 .hooknum        = NF_INET_PRE_ROUTING,
 253                 .priority       = NF_IP6_PRI_CONNTRACK,
 254         },
 255         {
 256                 .hook           = ipv6_conntrack_local,
 257                 .owner          = THIS_MODULE,
 258                 .pf             = NFPROTO_IPV6,
 259                 .hooknum        = NF_INET_LOCAL_OUT,
 260                 .priority       = NF_IP6_PRI_CONNTRACK,
 261         },
 262         {
 263                 .hook           = ipv6_helper,
 264                 .owner          = THIS_MODULE,
 265                 .pf             = NFPROTO_IPV6,
 266                 .hooknum        = NF_INET_POST_ROUTING,
 267                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 268         },
 269         {
 270                 .hook           = ipv6_confirm,
 271                 .owner          = THIS_MODULE,
 272                 .pf             = NFPROTO_IPV6,
 273                 .hooknum        = NF_INET_POST_ROUTING,
 274                 .priority       = NF_IP6_PRI_LAST,
 275         },
 276         {
 277                 .hook           = ipv6_helper,
 278                 .owner          = THIS_MODULE,
 279                 .pf             = NFPROTO_IPV6,
 280                 .hooknum        = NF_INET_LOCAL_IN,
 281                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 282         },
 283         {
 284                 .hook           = ipv6_confirm,
 285                 .owner          = THIS_MODULE,
 286                 .pf             = NFPROTO_IPV6,
 287                 .hooknum        = NF_INET_LOCAL_IN,
 288                 .priority       = NF_IP6_PRI_LAST-1,
 289         },
 290 };
 291
 292 static int
 293 ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 294 {
 295         const struct inet_sock *inet = inet_sk(sk);
 296         const struct ipv6_pinfo *inet6 = inet6_sk(sk);
 297         const struct nf_conntrack_tuple_hash *h;
 298         struct sockaddr_in6 sin6;
 299         struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
 300         struct nf_conn *ct;
 301
 302         tuple.src.u3.in6 = sk->sk_v6_rcv_saddr;
 303         tuple.src.u.tcp.port = inet->inet_sport;
 304         tuple.dst.u3.in6 = sk->sk_v6_daddr;
 305         tuple.dst.u.tcp.port = inet->inet_dport;
 306         tuple.dst.protonum = sk->sk_protocol;
 307
 308         if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP)
 309                 return -ENOPROTOOPT;
 310
 311         if (*len < 0 || (unsigned int) *len < sizeof(sin6))
 312                 return -EINVAL;
 313
 314         h = nf_conntrack_find_get(sock_net(sk), NF_CT_DEFAULT_ZONE, &tuple);
 315         if (!h) {
 316                 pr_debug("IP6T_SO_ORIGINAL_DST: Can't find %pI6c/%u-%pI6c/%u.\n",
 317                          &tuple.src.u3.ip6, ntohs(tuple.src.u.tcp.port),
 318                          &tuple.dst.u3.ip6, ntohs(tuple.dst.u.tcp.port));
 319                 return -ENOENT;
 320         }
 321
 322         ct = nf_ct_tuplehash_to_ctrack(h);
 323
 324         sin6.sin6_family = AF_INET6;
 325         sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
 326         sin6.sin6_flowinfo = inet6->flow_label & IPV6_FLOWINFO_MASK;
 327         memcpy(&sin6.sin6_addr,
 328                 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
 329                                         sizeof(sin6.sin6_addr));
 330
 331         nf_ct_put(ct);
 332         sin6.sin6_scope_id = ipv6_iface_scope_id(&sin6.sin6_addr,
 333                                                  sk->sk_bound_dev_if);
 334         return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
 335 }
 336
 337 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 338
 339 #include <linux/netfilter/nfnetlink.h>
 340 #include <linux/netfilter/nfnetlink_conntrack.h>
 341
 342 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 343                                 const struct nf_conntrack_tuple *tuple)
 344 {
 345         if (nla_put(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 346                     &tuple->src.u3.ip6) ||
 347             nla_put(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 348                     &tuple->dst.u3.ip6))
 349                 goto nla_put_failure;
 350         return 0;
 351
 352 nla_put_failure:
 353         return -1;
 354 }
 355
 356 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 357         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 358         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 359 };
 360
 361 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 362                                 struct nf_conntrack_tuple *t)
 363 {
 364         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 365                 return -EINVAL;
 366
 367         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 368                sizeof(u_int32_t) * 4);
 369         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 370                sizeof(u_int32_t) * 4);
 371
 372         return 0;
 373 }
 374
 375 static int ipv6_nlattr_tuple_size(void)
 376 {
 377         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 378 }
 379 #endif
 380
 381 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 382         .l3proto                = PF_INET6,
 383         .name                   = "ipv6",
 384         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 385         .invert_tuple           = ipv6_invert_tuple,
 386         .print_tuple            = ipv6_print_tuple,
 387         .get_l4proto            = ipv6_get_l4proto,
 388 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 389         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 390         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 391         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 392         .nla_policy             = ipv6_nla_policy,
 393 #endif
 394         .me                     = THIS_MODULE,
 395 };
 396
 397 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 398 MODULE_LICENSE("GPL");
 399 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 400
 401 static struct nf_sockopt_ops so_getorigdst6 = {
 402         .pf             = NFPROTO_IPV6,
 403         .get_optmin     = IP6T_SO_ORIGINAL_DST,
 404         .get_optmax     = IP6T_SO_ORIGINAL_DST + 1,
 405         .get            = ipv6_getorigdst,
 406         .owner          = THIS_MODULE,
 407 };
 408
 409 static int ipv6_net_init(struct net *net)
 410 {
 411         int ret = 0;
 412
 413         ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_tcp6);
 414         if (ret < 0) {
 415                 pr_err("nf_conntrack_tcp6: pernet registration failed\n");
 416                 goto out;
 417         }
 418         ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_udp6);
 419         if (ret < 0) {
 420                 pr_err("nf_conntrack_udp6: pernet registration failed\n");
 421                 goto cleanup_tcp6;
 422         }
 423         ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_icmpv6);
 424         if (ret < 0) {
 425                 pr_err("nf_conntrack_icmp6: pernet registration failed\n");
 426                 goto cleanup_udp6;
 427         }
 428         ret = nf_ct_l3proto_pernet_register(net, &nf_conntrack_l3proto_ipv6);
 429         if (ret < 0) {
 430                 pr_err("nf_conntrack_ipv6: pernet registration failed.\n");
 431                 goto cleanup_icmpv6;
 432         }
 433         return 0;
 434  cleanup_icmpv6:
 435         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmpv6);
 436  cleanup_udp6:
 437         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp6);
 438  cleanup_tcp6:
 439         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp6);
 440  out:
 441         return ret;
 442 }
 443
 444 static void ipv6_net_exit(struct net *net)
 445 {
 446         nf_ct_l3proto_pernet_unregister(net, &nf_conntrack_l3proto_ipv6);
 447         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmpv6);
 448         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp6);
 449         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp6);
 450 }
 451
 452 static struct pernet_operations ipv6_net_ops = {
 453         .init = ipv6_net_init,
 454         .exit = ipv6_net_exit,
 455 };
 456
 457 static int __init nf_conntrack_l3proto_ipv6_init(void)
 458 {
 459         int ret = 0;
 460
 461         need_conntrack();
 462         nf_defrag_ipv6_enable();
 463
 464         ret = nf_register_sockopt(&so_getorigdst6);
 465         if (ret < 0) {
 466                 pr_err("Unable to register netfilter socket option\n");
 467                 return ret;
 468         }
 469
 470         ret = register_pernet_subsys(&ipv6_net_ops);
 471         if (ret < 0)
 472                 goto cleanup_sockopt;
 473
 474         ret = nf_register_hooks(ipv6_conntrack_ops,
 475                                 ARRAY_SIZE(ipv6_conntrack_ops));
 476         if (ret < 0) {
 477                 pr_err("nf_conntrack_ipv6: can't register pre-routing defrag "
 478                        "hook.\n");
 479                 goto cleanup_pernet;
 480         }
 481
 482         ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_tcp6);
 483         if (ret < 0) {
 484                 pr_err("nf_conntrack_ipv6: can't register tcp6 proto.\n");
 485                 goto cleanup_hooks;
 486         }
 487
 488         ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_udp6);
 489         if (ret < 0) {
 490                 pr_err("nf_conntrack_ipv6: can't register udp6 proto.\n");
 491                 goto cleanup_tcp6;
 492         }
 493
 494         ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 495         if (ret < 0) {
 496                 pr_err("nf_conntrack_ipv6: can't register icmpv6 proto.\n");
 497                 goto cleanup_udp6;
 498         }
 499
 500         ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv6);
 501         if (ret < 0) {
 502                 pr_err("nf_conntrack_ipv6: can't register ipv6 proto.\n");
 503                 goto cleanup_icmpv6;
 504         }
 505         return ret;
 506
 507  cleanup_icmpv6:
 508         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 509  cleanup_udp6:
 510         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 511  cleanup_tcp6:
 512         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 513  cleanup_hooks:
 514         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 515  cleanup_pernet:
 516         unregister_pernet_subsys(&ipv6_net_ops);
 517  cleanup_sockopt:
 518         nf_unregister_sockopt(&so_getorigdst6);
 519         return ret;
 520 }
 521
 522 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 523 {
 524         synchronize_net();
 525         nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 526         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 527         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 528         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 529         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 530         unregister_pernet_subsys(&ipv6_net_ops);
 531         nf_unregister_sockopt(&so_getorigdst6);
 532 }
 533
 534 module_init(nf_conntrack_l3proto_ipv6_init);
 535 module_exit(nf_conntrack_l3proto_ipv6_fini);