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/ipv6/nf_conntrack_ipv6.h>
  32 #include <net/netfilter/nf_nat_helper.h>
  33 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
  34 #include <net/netfilter/nf_log.h>
  35
  36 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  37                               struct nf_conntrack_tuple *tuple)
  38 {
  39         const u_int32_t *ap;
  40         u_int32_t _addrs[8];
  41
  42         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  43                                 sizeof(_addrs), _addrs);
  44         if (ap == NULL)
  45                 return false;
  46
  47         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  48         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  49
  50         return true;
  51 }
  52
  53 static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  54                               const struct nf_conntrack_tuple *orig)
  55 {
  56         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  57         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  58
  59         return true;
  60 }
  61
  62 static int ipv6_print_tuple(struct seq_file *s,
  63                             const struct nf_conntrack_tuple *tuple)
  64 {
  65         return seq_printf(s, "src=%pI6 dst=%pI6 ",
  66                           tuple->src.u3.ip6, tuple->dst.u3.ip6);
  67 }
  68
  69 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
  70                             unsigned int *dataoff, u_int8_t *protonum)
  71 {
  72         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
  73         __be16 frag_off;
  74         int protoff;
  75         u8 nexthdr;
  76
  77         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
  78                           &nexthdr, sizeof(nexthdr)) != 0) {
  79                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
  80                 return -NF_ACCEPT;
  81         }
  82         protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
  83         /*
  84          * (protoff == skb->len) mean that the packet doesn't have no data
  85          * except of IPv6 & ext headers. but it's tracked anyway. - YK
  86          */
  87         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
  88                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
  89                 return -NF_ACCEPT;
  90         }
  91
  92         *dataoff = protoff;
  93         *protonum = nexthdr;
  94         return NF_ACCEPT;
  95 }
  96
  97 static unsigned int ipv6_helper(unsigned int hooknum,
  98                                 struct sk_buff *skb,
  99                                 const struct net_device *in,
 100                                 const struct net_device *out,
 101                                 int (*okfn)(struct sk_buff *))
 102 {
 103         struct nf_conn *ct;
 104         const struct nf_conn_help *help;
 105         const struct nf_conntrack_helper *helper;
 106         enum ip_conntrack_info ctinfo;
 107         unsigned int ret;
 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         ret = helper->help(skb, protoff, ct, ctinfo);
 134         if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) {
 135                 nf_log_packet(NFPROTO_IPV6, hooknum, skb, in, out, NULL,
 136                               "nf_ct_%s: dropping packet", helper->name);
 137         }
 138         return ret;
 139 }
 140
 141 static unsigned int ipv6_confirm(unsigned int hooknum,
 142                                  struct sk_buff *skb,
 143                                  const struct net_device *in,
 144                                  const struct net_device *out,
 145                                  int (*okfn)(struct sk_buff *))
 146 {
 147         struct nf_conn *ct;
 148         enum ip_conntrack_info ctinfo;
 149         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 150         int protoff;
 151         __be16 frag_off;
 152
 153         ct = nf_ct_get(skb, &ctinfo);
 154         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 155                 goto out;
 156
 157         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
 158                                    &frag_off);
 159         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 160                 pr_debug("proto header not found\n");
 161                 goto out;
 162         }
 163
 164         /* adjust seqs for loopback traffic only in outgoing direction */
 165         if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
 166             !nf_is_loopback_packet(skb)) {
 167                 typeof(nf_nat_seq_adjust_hook) seq_adjust;
 168
 169                 seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
 170                 if (!seq_adjust ||
 171                     !seq_adjust(skb, ct, ctinfo, protoff)) {
 172                         NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
 173                         return NF_DROP;
 174                 }
 175         }
 176 out:
 177         /* We've seen it coming out the other side: confirm it */
 178         return nf_conntrack_confirm(skb);
 179 }
 180
 181 static unsigned int __ipv6_conntrack_in(struct net *net,
 182                                         unsigned int hooknum,
 183                                         struct sk_buff *skb,
 184                                         const struct net_device *in,
 185                                         const struct net_device *out,
 186                                         int (*okfn)(struct sk_buff *))
 187 {
 188         struct sk_buff *reasm = skb->nfct_reasm;
 189         const struct nf_conn_help *help;
 190         struct nf_conn *ct;
 191         enum ip_conntrack_info ctinfo;
 192
 193         /* This packet is fragmented and has reassembled packet. */
 194         if (reasm) {
 195                 /* Reassembled packet isn't parsed yet ? */
 196                 if (!reasm->nfct) {
 197                         unsigned int ret;
 198
 199                         ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
 200                         if (ret != NF_ACCEPT)
 201                                 return ret;
 202                 }
 203
 204                 /* Conntrack helpers need the entire reassembled packet in the
 205                  * POST_ROUTING hook. In case of unconfirmed connections NAT
 206                  * might reassign a helper, so the entire packet is also
 207                  * required.
 208                  */
 209                 ct = nf_ct_get(reasm, &ctinfo);
 210                 if (ct != NULL && !nf_ct_is_untracked(ct)) {
 211                         help = nfct_help(ct);
 212                         if ((help && help->helper) || !nf_ct_is_confirmed(ct)) {
 213                                 nf_conntrack_get_reasm(skb);
 214                                 NF_HOOK_THRESH(NFPROTO_IPV6, hooknum, reasm,
 215                                                (struct net_device *)in,
 216                                                (struct net_device *)out,
 217                                                okfn, NF_IP6_PRI_CONNTRACK + 1);
 218                                 return NF_DROP_ERR(-ECANCELED);
 219                         }
 220                 }
 221
 222                 nf_conntrack_get(reasm->nfct);
 223                 skb->nfct = reasm->nfct;
 224                 skb->nfctinfo = reasm->nfctinfo;
 225                 return NF_ACCEPT;
 226         }
 227
 228         return nf_conntrack_in(net, PF_INET6, hooknum, skb);
 229 }
 230
 231 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 232                                       struct sk_buff *skb,
 233                                       const struct net_device *in,
 234                                       const struct net_device *out,
 235                                       int (*okfn)(struct sk_buff *))
 236 {
 237         return __ipv6_conntrack_in(dev_net(in), hooknum, skb, in, out, okfn);
 238 }
 239
 240 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 241                                          struct sk_buff *skb,
 242                                          const struct net_device *in,
 243                                          const struct net_device *out,
 244                                          int (*okfn)(struct sk_buff *))
 245 {
 246         /* root is playing with raw sockets. */
 247         if (skb->len < sizeof(struct ipv6hdr)) {
 248                 net_notice_ratelimited("ipv6_conntrack_local: packet too short\n");
 249                 return NF_ACCEPT;
 250         }
 251         return __ipv6_conntrack_in(dev_net(out), hooknum, skb, in, out, okfn);
 252 }
 253
 254 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 255         {
 256                 .hook           = ipv6_conntrack_in,
 257                 .owner          = THIS_MODULE,
 258                 .pf             = NFPROTO_IPV6,
 259                 .hooknum        = NF_INET_PRE_ROUTING,
 260                 .priority       = NF_IP6_PRI_CONNTRACK,
 261         },
 262         {
 263                 .hook           = ipv6_conntrack_local,
 264                 .owner          = THIS_MODULE,
 265                 .pf             = NFPROTO_IPV6,
 266                 .hooknum        = NF_INET_LOCAL_OUT,
 267                 .priority       = NF_IP6_PRI_CONNTRACK,
 268         },
 269         {
 270                 .hook           = ipv6_helper,
 271                 .owner          = THIS_MODULE,
 272                 .pf             = NFPROTO_IPV6,
 273                 .hooknum        = NF_INET_POST_ROUTING,
 274                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 275         },
 276         {
 277                 .hook           = ipv6_confirm,
 278                 .owner          = THIS_MODULE,
 279                 .pf             = NFPROTO_IPV6,
 280                 .hooknum        = NF_INET_POST_ROUTING,
 281                 .priority       = NF_IP6_PRI_LAST,
 282         },
 283         {
 284                 .hook           = ipv6_helper,
 285                 .owner          = THIS_MODULE,
 286                 .pf             = NFPROTO_IPV6,
 287                 .hooknum        = NF_INET_LOCAL_IN,
 288                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 289         },
 290         {
 291                 .hook           = ipv6_confirm,
 292                 .owner          = THIS_MODULE,
 293                 .pf             = NFPROTO_IPV6,
 294                 .hooknum        = NF_INET_LOCAL_IN,
 295                 .priority       = NF_IP6_PRI_LAST-1,
 296         },
 297 };
 298
 299 static int
 300 ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 301 {
 302         const struct inet_sock *inet = inet_sk(sk);
 303         const struct ipv6_pinfo *inet6 = inet6_sk(sk);
 304         const struct nf_conntrack_tuple_hash *h;
 305         struct sockaddr_in6 sin6;
 306         struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
 307         struct nf_conn *ct;
 308
 309         tuple.src.u3.in6 = inet6->rcv_saddr;
 310         tuple.src.u.tcp.port = inet->inet_sport;
 311         tuple.dst.u3.in6 = inet6->daddr;
 312         tuple.dst.u.tcp.port = inet->inet_dport;
 313         tuple.dst.protonum = sk->sk_protocol;
 314
 315         if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP)
 316                 return -ENOPROTOOPT;
 317
 318         if (*len < 0 || (unsigned int) *len < sizeof(sin6))
 319                 return -EINVAL;
 320
 321         h = nf_conntrack_find_get(sock_net(sk), NF_CT_DEFAULT_ZONE, &tuple);
 322         if (!h) {
 323                 pr_debug("IP6T_SO_ORIGINAL_DST: Can't find %pI6c/%u-%pI6c/%u.\n",
 324                          &tuple.src.u3.ip6, ntohs(tuple.src.u.tcp.port),
 325                          &tuple.dst.u3.ip6, ntohs(tuple.dst.u.tcp.port));
 326                 return -ENOENT;
 327         }
 328
 329         ct = nf_ct_tuplehash_to_ctrack(h);
 330
 331         sin6.sin6_family = AF_INET6;
 332         sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
 333         sin6.sin6_flowinfo = inet6->flow_label & IPV6_FLOWINFO_MASK;
 334         memcpy(&sin6.sin6_addr,
 335                 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
 336                                         sizeof(sin6.sin6_addr));
 337
 338         nf_ct_put(ct);
 339
 340         if (ipv6_addr_type(&sin6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
 341                 sin6.sin6_scope_id = sk->sk_bound_dev_if;
 342         else
 343                 sin6.sin6_scope_id = 0;
 344
 345         return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
 346 }
 347
 348 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 349
 350 #include <linux/netfilter/nfnetlink.h>
 351 #include <linux/netfilter/nfnetlink_conntrack.h>
 352
 353 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 354                                 const struct nf_conntrack_tuple *tuple)
 355 {
 356         if (nla_put(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 357                     &tuple->src.u3.ip6) ||
 358             nla_put(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 359                     &tuple->dst.u3.ip6))
 360                 goto nla_put_failure;
 361         return 0;
 362
 363 nla_put_failure:
 364         return -1;
 365 }
 366
 367 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 368         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 369         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 370 };
 371
 372 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 373                                 struct nf_conntrack_tuple *t)
 374 {
 375         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 376                 return -EINVAL;
 377
 378         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 379                sizeof(u_int32_t) * 4);
 380         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 381                sizeof(u_int32_t) * 4);
 382
 383         return 0;
 384 }
 385
 386 static int ipv6_nlattr_tuple_size(void)
 387 {
 388         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 389 }
 390 #endif
 391
 392 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 393         .l3proto                = PF_INET6,
 394         .name                   = "ipv6",
 395         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 396         .invert_tuple           = ipv6_invert_tuple,
 397         .print_tuple            = ipv6_print_tuple,
 398         .get_l4proto            = ipv6_get_l4proto,
 399 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 400         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 401         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 402         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 403         .nla_policy             = ipv6_nla_policy,
 404 #endif
 405         .me                     = THIS_MODULE,
 406 };
 407
 408 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 409 MODULE_LICENSE("GPL");
 410 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 411
 412 static struct nf_sockopt_ops so_getorigdst6 = {
 413         .pf             = NFPROTO_IPV6,
 414         .get_optmin     = IP6T_SO_ORIGINAL_DST,
 415         .get_optmax     = IP6T_SO_ORIGINAL_DST + 1,
 416         .get            = ipv6_getorigdst,
 417         .owner          = THIS_MODULE,
 418 };
 419
 420 static int ipv6_net_init(struct net *net)
 421 {
 422         int ret = 0;
 423
 424         ret = nf_conntrack_l4proto_register(net,
 425                                             &nf_conntrack_l4proto_tcp6);
 426         if (ret < 0) {
 427                 printk(KERN_ERR "nf_conntrack_l4proto_tcp6: protocol register failed\n");
 428                 goto out;
 429         }
 430         ret = nf_conntrack_l4proto_register(net,
 431                                             &nf_conntrack_l4proto_udp6);
 432         if (ret < 0) {
 433                 printk(KERN_ERR "nf_conntrack_l4proto_udp6: protocol register failed\n");
 434                 goto cleanup_tcp6;
 435         }
 436         ret = nf_conntrack_l4proto_register(net,
 437                                             &nf_conntrack_l4proto_icmpv6);
 438         if (ret < 0) {
 439                 printk(KERN_ERR "nf_conntrack_l4proto_icmp6: protocol register failed\n");
 440                 goto cleanup_udp6;
 441         }
 442         ret = nf_conntrack_l3proto_register(net,
 443                                             &nf_conntrack_l3proto_ipv6);
 444         if (ret < 0) {
 445                 printk(KERN_ERR "nf_conntrack_l3proto_ipv6: protocol register failed\n");
 446                 goto cleanup_icmpv6;
 447         }
 448         return 0;
 449  cleanup_icmpv6:
 450         nf_conntrack_l4proto_unregister(net,
 451                                         &nf_conntrack_l4proto_icmpv6);
 452  cleanup_udp6:
 453         nf_conntrack_l4proto_unregister(net,
 454                                         &nf_conntrack_l4proto_udp6);
 455  cleanup_tcp6:
 456         nf_conntrack_l4proto_unregister(net,
 457                                         &nf_conntrack_l4proto_tcp6);
 458  out:
 459         return ret;
 460 }
 461
 462 static void ipv6_net_exit(struct net *net)
 463 {
 464         nf_conntrack_l3proto_unregister(net,
 465                                         &nf_conntrack_l3proto_ipv6);
 466         nf_conntrack_l4proto_unregister(net,
 467                                         &nf_conntrack_l4proto_icmpv6);
 468         nf_conntrack_l4proto_unregister(net,
 469                                         &nf_conntrack_l4proto_udp6);
 470         nf_conntrack_l4proto_unregister(net,
 471                                         &nf_conntrack_l4proto_tcp6);
 472 }
 473
 474 static struct pernet_operations ipv6_net_ops = {
 475         .init = ipv6_net_init,
 476         .exit = ipv6_net_exit,
 477 };
 478
 479 static int __init nf_conntrack_l3proto_ipv6_init(void)
 480 {
 481         int ret = 0;
 482
 483         need_conntrack();
 484         nf_defrag_ipv6_enable();
 485
 486         ret = nf_register_sockopt(&so_getorigdst6);
 487         if (ret < 0) {
 488                 pr_err("Unable to register netfilter socket option\n");
 489                 return ret;
 490         }
 491
 492         ret = register_pernet_subsys(&ipv6_net_ops);
 493         if (ret < 0)
 494                 goto cleanup_pernet;
 495         ret = nf_register_hooks(ipv6_conntrack_ops,
 496                                 ARRAY_SIZE(ipv6_conntrack_ops));
 497         if (ret < 0) {
 498                 pr_err("nf_conntrack_ipv6: can't register pre-routing defrag "
 499                        "hook.\n");
 500                 goto cleanup_ipv6;
 501         }
 502         return ret;
 503
 504  cleanup_ipv6:
 505         unregister_pernet_subsys(&ipv6_net_ops);
 506  cleanup_pernet:
 507         nf_unregister_sockopt(&so_getorigdst6);
 508         return ret;
 509 }
 510
 511 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 512 {
 513         synchronize_net();
 514         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 515         unregister_pernet_subsys(&ipv6_net_ops);
 516         nf_unregister_sockopt(&so_getorigdst6);
 517 }
 518
 519 module_init(nf_conntrack_l3proto_ipv6_init);
 520 module_exit(nf_conntrack_l3proto_ipv6_fini);