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 void ipv6_print_tuple(struct seq_file *s,
  64                             const struct nf_conntrack_tuple *tuple)
  65 {
  66         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 nf_hook_state *state)
 101 {
 102         struct nf_conn *ct;
 103         const struct nf_conn_help *help;
 104         const struct nf_conntrack_helper *helper;
 105         enum ip_conntrack_info ctinfo;
 106         __be16 frag_off;
 107         int protoff;
 108         u8 nexthdr;
 109
 110         /* This is where we call the helper: as the packet goes out. */
 111         ct = nf_ct_get(skb, &ctinfo);
 112         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 113                 return NF_ACCEPT;
 114
 115         help = nfct_help(ct);
 116         if (!help)
 117                 return NF_ACCEPT;
 118         /* rcu_read_lock()ed by nf_hook_slow */
 119         helper = rcu_dereference(help->helper);
 120         if (!helper)
 121                 return NF_ACCEPT;
 122
 123         nexthdr = ipv6_hdr(skb)->nexthdr;
 124         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
 125                                    &frag_off);
 126         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 127                 pr_debug("proto header not found\n");
 128                 return NF_ACCEPT;
 129         }
 130
 131         return helper->help(skb, protoff, ct, ctinfo);
 132 }
 133
 134 static unsigned int ipv6_confirm(const struct nf_hook_ops *ops,
 135                                  struct sk_buff *skb,
 136                                  const struct nf_hook_state *state)
 137 {
 138         struct nf_conn *ct;
 139         enum ip_conntrack_info ctinfo;
 140         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 141         int protoff;
 142         __be16 frag_off;
 143
 144         ct = nf_ct_get(skb, &ctinfo);
 145         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 146                 goto out;
 147
 148         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
 149                                    &frag_off);
 150         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 151                 pr_debug("proto header not found\n");
 152                 goto out;
 153         }
 154
 155         /* adjust seqs for loopback traffic only in outgoing direction */
 156         if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
 157             !nf_is_loopback_packet(skb)) {
 158                 if (!nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) {
 159                         NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
 160                         return NF_DROP;
 161                 }
 162         }
 163 out:
 164         /* We've seen it coming out the other side: confirm it */
 165         return nf_conntrack_confirm(skb);
 166 }
 167
 168 static unsigned int ipv6_conntrack_in(const struct nf_hook_ops *ops,
 169                                       struct sk_buff *skb,
 170                                       const struct nf_hook_state *state)
 171 {
 172         return nf_conntrack_in(state->net, PF_INET6, ops->hooknum, skb);
 173 }
 174
 175 static unsigned int ipv6_conntrack_local(const struct nf_hook_ops *ops,
 176                                          struct sk_buff *skb,
 177                                          const struct nf_hook_state *state)
 178 {
 179         /* root is playing with raw sockets. */
 180         if (skb->len < sizeof(struct ipv6hdr)) {
 181                 net_notice_ratelimited("ipv6_conntrack_local: packet too short\n");
 182                 return NF_ACCEPT;
 183         }
 184         return nf_conntrack_in(state->net, PF_INET6, ops->hooknum, skb);
 185 }
 186
 187 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 188         {
 189                 .hook           = ipv6_conntrack_in,
 190                 .owner          = THIS_MODULE,
 191                 .pf             = NFPROTO_IPV6,
 192                 .hooknum        = NF_INET_PRE_ROUTING,
 193                 .priority       = NF_IP6_PRI_CONNTRACK,
 194         },
 195         {
 196                 .hook           = ipv6_conntrack_local,
 197                 .owner          = THIS_MODULE,
 198                 .pf             = NFPROTO_IPV6,
 199                 .hooknum        = NF_INET_LOCAL_OUT,
 200                 .priority       = NF_IP6_PRI_CONNTRACK,
 201         },
 202         {
 203                 .hook           = ipv6_helper,
 204                 .owner          = THIS_MODULE,
 205                 .pf             = NFPROTO_IPV6,
 206                 .hooknum        = NF_INET_POST_ROUTING,
 207                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 208         },
 209         {
 210                 .hook           = ipv6_confirm,
 211                 .owner          = THIS_MODULE,
 212                 .pf             = NFPROTO_IPV6,
 213                 .hooknum        = NF_INET_POST_ROUTING,
 214                 .priority       = NF_IP6_PRI_LAST,
 215         },
 216         {
 217                 .hook           = ipv6_helper,
 218                 .owner          = THIS_MODULE,
 219                 .pf             = NFPROTO_IPV6,
 220                 .hooknum        = NF_INET_LOCAL_IN,
 221                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 222         },
 223         {
 224                 .hook           = ipv6_confirm,
 225                 .owner          = THIS_MODULE,
 226                 .pf             = NFPROTO_IPV6,
 227                 .hooknum        = NF_INET_LOCAL_IN,
 228                 .priority       = NF_IP6_PRI_LAST-1,
 229         },
 230 };
 231
 232 static int
 233 ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 234 {
 235         const struct inet_sock *inet = inet_sk(sk);
 236         const struct ipv6_pinfo *inet6 = inet6_sk(sk);
 237         const struct nf_conntrack_tuple_hash *h;
 238         struct sockaddr_in6 sin6;
 239         struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
 240         struct nf_conn *ct;
 241
 242         tuple.src.u3.in6 = sk->sk_v6_rcv_saddr;
 243         tuple.src.u.tcp.port = inet->inet_sport;
 244         tuple.dst.u3.in6 = sk->sk_v6_daddr;
 245         tuple.dst.u.tcp.port = inet->inet_dport;
 246         tuple.dst.protonum = sk->sk_protocol;
 247
 248         if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP)
 249                 return -ENOPROTOOPT;
 250
 251         if (*len < 0 || (unsigned int) *len < sizeof(sin6))
 252                 return -EINVAL;
 253
 254         h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
 255         if (!h) {
 256                 pr_debug("IP6T_SO_ORIGINAL_DST: Can't find %pI6c/%u-%pI6c/%u.\n",
 257                          &tuple.src.u3.ip6, ntohs(tuple.src.u.tcp.port),
 258                          &tuple.dst.u3.ip6, ntohs(tuple.dst.u.tcp.port));
 259                 return -ENOENT;
 260         }
 261
 262         ct = nf_ct_tuplehash_to_ctrack(h);
 263
 264         sin6.sin6_family = AF_INET6;
 265         sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
 266         sin6.sin6_flowinfo = inet6->flow_label & IPV6_FLOWINFO_MASK;
 267         memcpy(&sin6.sin6_addr,
 268                 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
 269                                         sizeof(sin6.sin6_addr));
 270
 271         nf_ct_put(ct);
 272         sin6.sin6_scope_id = ipv6_iface_scope_id(&sin6.sin6_addr,
 273                                                  sk->sk_bound_dev_if);
 274         return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
 275 }
 276
 277 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 278
 279 #include <linux/netfilter/nfnetlink.h>
 280 #include <linux/netfilter/nfnetlink_conntrack.h>
 281
 282 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 283                                 const struct nf_conntrack_tuple *tuple)
 284 {
 285         if (nla_put_in6_addr(skb, CTA_IP_V6_SRC, &tuple->src.u3.in6) ||
 286             nla_put_in6_addr(skb, CTA_IP_V6_DST, &tuple->dst.u3.in6))
 287                 goto nla_put_failure;
 288         return 0;
 289
 290 nla_put_failure:
 291         return -1;
 292 }
 293
 294 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 295         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 296         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 297 };
 298
 299 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 300                                 struct nf_conntrack_tuple *t)
 301 {
 302         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 303                 return -EINVAL;
 304
 305         t->src.u3.in6 = nla_get_in6_addr(tb[CTA_IP_V6_SRC]);
 306         t->dst.u3.in6 = nla_get_in6_addr(tb[CTA_IP_V6_DST]);
 307
 308         return 0;
 309 }
 310
 311 static int ipv6_nlattr_tuple_size(void)
 312 {
 313         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 314 }
 315 #endif
 316
 317 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 318         .l3proto                = PF_INET6,
 319         .name                   = "ipv6",
 320         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 321         .invert_tuple           = ipv6_invert_tuple,
 322         .print_tuple            = ipv6_print_tuple,
 323         .get_l4proto            = ipv6_get_l4proto,
 324 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 325         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 326         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 327         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 328         .nla_policy             = ipv6_nla_policy,
 329 #endif
 330         .me                     = THIS_MODULE,
 331 };
 332
 333 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 334 MODULE_LICENSE("GPL");
 335 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 336
 337 static struct nf_sockopt_ops so_getorigdst6 = {
 338         .pf             = NFPROTO_IPV6,
 339         .get_optmin     = IP6T_SO_ORIGINAL_DST,
 340         .get_optmax     = IP6T_SO_ORIGINAL_DST + 1,
 341         .get            = ipv6_getorigdst,
 342         .owner          = THIS_MODULE,
 343 };
 344
 345 static int ipv6_net_init(struct net *net)
 346 {
 347         int ret = 0;
 348
 349         ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_tcp6);
 350         if (ret < 0) {
 351                 pr_err("nf_conntrack_tcp6: pernet registration failed\n");
 352                 goto out;
 353         }
 354         ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_udp6);
 355         if (ret < 0) {
 356                 pr_err("nf_conntrack_udp6: pernet registration failed\n");
 357                 goto cleanup_tcp6;
 358         }
 359         ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_icmpv6);
 360         if (ret < 0) {
 361                 pr_err("nf_conntrack_icmp6: pernet registration failed\n");
 362                 goto cleanup_udp6;
 363         }
 364         ret = nf_ct_l3proto_pernet_register(net, &nf_conntrack_l3proto_ipv6);
 365         if (ret < 0) {
 366                 pr_err("nf_conntrack_ipv6: pernet registration failed.\n");
 367                 goto cleanup_icmpv6;
 368         }
 369         return 0;
 370  cleanup_icmpv6:
 371         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmpv6);
 372  cleanup_udp6:
 373         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp6);
 374  cleanup_tcp6:
 375         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp6);
 376  out:
 377         return ret;
 378 }
 379
 380 static void ipv6_net_exit(struct net *net)
 381 {
 382         nf_ct_l3proto_pernet_unregister(net, &nf_conntrack_l3proto_ipv6);
 383         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmpv6);
 384         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp6);
 385         nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp6);
 386 }
 387
 388 static struct pernet_operations ipv6_net_ops = {
 389         .init = ipv6_net_init,
 390         .exit = ipv6_net_exit,
 391 };
 392
 393 static int __init nf_conntrack_l3proto_ipv6_init(void)
 394 {
 395         int ret = 0;
 396
 397         need_conntrack();
 398         nf_defrag_ipv6_enable();
 399
 400         ret = nf_register_sockopt(&so_getorigdst6);
 401         if (ret < 0) {
 402                 pr_err("Unable to register netfilter socket option\n");
 403                 return ret;
 404         }
 405
 406         ret = register_pernet_subsys(&ipv6_net_ops);
 407         if (ret < 0)
 408                 goto cleanup_sockopt;
 409
 410         ret = nf_register_hooks(ipv6_conntrack_ops,
 411                                 ARRAY_SIZE(ipv6_conntrack_ops));
 412         if (ret < 0) {
 413                 pr_err("nf_conntrack_ipv6: can't register pre-routing defrag "
 414                        "hook.\n");
 415                 goto cleanup_pernet;
 416         }
 417
 418         ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_tcp6);
 419         if (ret < 0) {
 420                 pr_err("nf_conntrack_ipv6: can't register tcp6 proto.\n");
 421                 goto cleanup_hooks;
 422         }
 423
 424         ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_udp6);
 425         if (ret < 0) {
 426                 pr_err("nf_conntrack_ipv6: can't register udp6 proto.\n");
 427                 goto cleanup_tcp6;
 428         }
 429
 430         ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 431         if (ret < 0) {
 432                 pr_err("nf_conntrack_ipv6: can't register icmpv6 proto.\n");
 433                 goto cleanup_udp6;
 434         }
 435
 436         ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv6);
 437         if (ret < 0) {
 438                 pr_err("nf_conntrack_ipv6: can't register ipv6 proto.\n");
 439                 goto cleanup_icmpv6;
 440         }
 441         return ret;
 442
 443  cleanup_icmpv6:
 444         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 445  cleanup_udp6:
 446         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 447  cleanup_tcp6:
 448         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 449  cleanup_hooks:
 450         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 451  cleanup_pernet:
 452         unregister_pernet_subsys(&ipv6_net_ops);
 453  cleanup_sockopt:
 454         nf_unregister_sockopt(&so_getorigdst6);
 455         return ret;
 456 }
 457
 458 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 459 {
 460         synchronize_net();
 461         nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 462         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 463         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 464         nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 465         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 466         unregister_pernet_subsys(&ipv6_net_ops);
 467         nf_unregister_sockopt(&so_getorigdst6);
 468 }
 469
 470 module_init(nf_conntrack_l3proto_ipv6_init);
 471 module_exit(nf_conntrack_l3proto_ipv6_fini);