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 int conntrack6_net_id;
  38 static DEFINE_MUTEX(register_ipv6_hooks);
  39
  40 struct conntrack6_net {
  41         unsigned int users;
  42 };
  43
  44 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  45                               struct nf_conntrack_tuple *tuple)
  46 {
  47         const u_int32_t *ap;
  48         u_int32_t _addrs[8];
  49
  50         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  51                                 sizeof(_addrs), _addrs);
  52         if (ap == NULL)
  53                 return false;
  54
  55         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  56         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  57
  58         return true;
  59 }
  60
  61 static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  62                               const struct nf_conntrack_tuple *orig)
  63 {
  64         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  65         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  66
  67         return true;
  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(void *priv,
  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_thresh */
 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(void *priv,
 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(void *priv,
 169                                       struct sk_buff *skb,
 170                                       const struct nf_hook_state *state)
 171 {
 172         return nf_conntrack_in(state->net, PF_INET6, state->hook, skb);
 173 }
 174
 175 static unsigned int ipv6_conntrack_local(void *priv,
 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, state->hook, skb);
 185 }
 186
 187 static const struct nf_hook_ops ipv6_conntrack_ops[] = {
 188         {
 189                 .hook           = ipv6_conntrack_in,
 190                 .pf             = NFPROTO_IPV6,
 191                 .hooknum        = NF_INET_PRE_ROUTING,
 192                 .priority       = NF_IP6_PRI_CONNTRACK,
 193         },
 194         {
 195                 .hook           = ipv6_conntrack_local,
 196                 .pf             = NFPROTO_IPV6,
 197                 .hooknum        = NF_INET_LOCAL_OUT,
 198                 .priority       = NF_IP6_PRI_CONNTRACK,
 199         },
 200         {
 201                 .hook           = ipv6_helper,
 202                 .pf             = NFPROTO_IPV6,
 203                 .hooknum        = NF_INET_POST_ROUTING,
 204                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 205         },
 206         {
 207                 .hook           = ipv6_confirm,
 208                 .pf             = NFPROTO_IPV6,
 209                 .hooknum        = NF_INET_POST_ROUTING,
 210                 .priority       = NF_IP6_PRI_LAST,
 211         },
 212         {
 213                 .hook           = ipv6_helper,
 214                 .pf             = NFPROTO_IPV6,
 215                 .hooknum        = NF_INET_LOCAL_IN,
 216                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 217         },
 218         {
 219                 .hook           = ipv6_confirm,
 220                 .pf             = NFPROTO_IPV6,
 221                 .hooknum        = NF_INET_LOCAL_IN,
 222                 .priority       = NF_IP6_PRI_LAST-1,
 223         },
 224 };
 225
 226 static int
 227 ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 228 {
 229         struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
 230         const struct ipv6_pinfo *inet6 = inet6_sk(sk);
 231         const struct inet_sock *inet = inet_sk(sk);
 232         const struct nf_conntrack_tuple_hash *h;
 233         struct sockaddr_in6 sin6;
 234         struct nf_conn *ct;
 235         __be32 flow_label;
 236         int bound_dev_if;
 237
 238         lock_sock(sk);
 239         tuple.src.u3.in6 = sk->sk_v6_rcv_saddr;
 240         tuple.src.u.tcp.port = inet->inet_sport;
 241         tuple.dst.u3.in6 = sk->sk_v6_daddr;
 242         tuple.dst.u.tcp.port = inet->inet_dport;
 243         tuple.dst.protonum = sk->sk_protocol;
 244         bound_dev_if = sk->sk_bound_dev_if;
 245         flow_label = inet6->flow_label;
 246         release_sock(sk);
 247
 248         if (tuple.dst.protonum != IPPROTO_TCP &&
 249             tuple.dst.protonum != IPPROTO_SCTP)
 250                 return -ENOPROTOOPT;
 251
 252         if (*len < 0 || (unsigned int) *len < sizeof(sin6))
 253                 return -EINVAL;
 254
 255         h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
 256         if (!h) {
 257                 pr_debug("IP6T_SO_ORIGINAL_DST: Can't find %pI6c/%u-%pI6c/%u.\n",
 258                          &tuple.src.u3.ip6, ntohs(tuple.src.u.tcp.port),
 259                          &tuple.dst.u3.ip6, ntohs(tuple.dst.u.tcp.port));
 260                 return -ENOENT;
 261         }
 262
 263         ct = nf_ct_tuplehash_to_ctrack(h);
 264
 265         sin6.sin6_family = AF_INET6;
 266         sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
 267         sin6.sin6_flowinfo = flow_label & IPV6_FLOWINFO_MASK;
 268         memcpy(&sin6.sin6_addr,
 269                 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
 270                                         sizeof(sin6.sin6_addr));
 271
 272         nf_ct_put(ct);
 273         sin6.sin6_scope_id = ipv6_iface_scope_id(&sin6.sin6_addr, 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 #endif
 311
 312 static int ipv6_hooks_register(struct net *net)
 313 {
 314         struct conntrack6_net *cnet = net_generic(net, conntrack6_net_id);
 315         int err = 0;
 316
 317         mutex_lock(&register_ipv6_hooks);
 318         cnet->users++;
 319         if (cnet->users > 1)
 320                 goto out_unlock;
 321
 322         err = nf_defrag_ipv6_enable(net);
 323         if (err < 0) {
 324                 cnet->users = 0;
 325                 goto out_unlock;
 326         }
 327
 328         err = nf_register_net_hooks(net, ipv6_conntrack_ops,
 329                                     ARRAY_SIZE(ipv6_conntrack_ops));
 330         if (err)
 331                 cnet->users = 0;
 332  out_unlock:
 333         mutex_unlock(&register_ipv6_hooks);
 334         return err;
 335 }
 336
 337 static void ipv6_hooks_unregister(struct net *net)
 338 {
 339         struct conntrack6_net *cnet = net_generic(net, conntrack6_net_id);
 340
 341         mutex_lock(&register_ipv6_hooks);
 342         if (cnet->users && (--cnet->users == 0))
 343                 nf_unregister_net_hooks(net, ipv6_conntrack_ops,
 344                                         ARRAY_SIZE(ipv6_conntrack_ops));
 345         mutex_unlock(&register_ipv6_hooks);
 346 }
 347
 348 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 349         .l3proto                = PF_INET6,
 350         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 351         .invert_tuple           = ipv6_invert_tuple,
 352         .get_l4proto            = ipv6_get_l4proto,
 353 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 354         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 355         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 356         .nla_policy             = ipv6_nla_policy,
 357         .nla_size               = NLA_ALIGN(NLA_HDRLEN + sizeof(u32[4])) +
 358                                   NLA_ALIGN(NLA_HDRLEN + sizeof(u32[4])),
 359 #endif
 360         .net_ns_get             = ipv6_hooks_register,
 361         .net_ns_put             = ipv6_hooks_unregister,
 362         .me                     = THIS_MODULE,
 363 };
 364
 365 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 366 MODULE_LICENSE("GPL");
 367 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 368
 369 static struct nf_sockopt_ops so_getorigdst6 = {
 370         .pf             = NFPROTO_IPV6,
 371         .get_optmin     = IP6T_SO_ORIGINAL_DST,
 372         .get_optmax     = IP6T_SO_ORIGINAL_DST + 1,
 373         .get            = ipv6_getorigdst,
 374         .owner          = THIS_MODULE,
 375 };
 376
 377 static struct nf_conntrack_l4proto *builtin_l4proto6[] = {
 378         &nf_conntrack_l4proto_tcp6,
 379         &nf_conntrack_l4proto_udp6,
 380         &nf_conntrack_l4proto_icmpv6,
 381 #ifdef CONFIG_NF_CT_PROTO_DCCP
 382         &nf_conntrack_l4proto_dccp6,
 383 #endif
 384 #ifdef CONFIG_NF_CT_PROTO_SCTP
 385         &nf_conntrack_l4proto_sctp6,
 386 #endif
 387 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 388         &nf_conntrack_l4proto_udplite6,
 389 #endif
 390 };
 391
 392 static int ipv6_net_init(struct net *net)
 393 {
 394         return nf_ct_l4proto_pernet_register(net, builtin_l4proto6,
 395                                              ARRAY_SIZE(builtin_l4proto6));
 396 }
 397
 398 static void ipv6_net_exit(struct net *net)
 399 {
 400         nf_ct_l4proto_pernet_unregister(net, builtin_l4proto6,
 401                                         ARRAY_SIZE(builtin_l4proto6));
 402 }
 403
 404 static struct pernet_operations ipv6_net_ops = {
 405         .init = ipv6_net_init,
 406         .exit = ipv6_net_exit,
 407         .id = &conntrack6_net_id,
 408         .size = sizeof(struct conntrack6_net),
 409 };
 410
 411 static int __init nf_conntrack_l3proto_ipv6_init(void)
 412 {
 413         int ret = 0;
 414
 415         need_conntrack();
 416
 417 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 418         if (WARN_ON(nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1) !=
 419             nf_conntrack_l3proto_ipv6.nla_size))
 420                 return -EINVAL;
 421 #endif
 422
 423         ret = nf_register_sockopt(&so_getorigdst6);
 424         if (ret < 0) {
 425                 pr_err("Unable to register netfilter socket option\n");
 426                 return ret;
 427         }
 428
 429         ret = register_pernet_subsys(&ipv6_net_ops);
 430         if (ret < 0)
 431                 goto cleanup_sockopt;
 432
 433         ret = nf_ct_l4proto_register(builtin_l4proto6,
 434                                      ARRAY_SIZE(builtin_l4proto6));
 435         if (ret < 0)
 436                 goto cleanup_pernet;
 437
 438         ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv6);
 439         if (ret < 0) {
 440                 pr_err("nf_conntrack_ipv6: can't register ipv6 proto.\n");
 441                 goto cleanup_l4proto;
 442         }
 443         return ret;
 444 cleanup_l4proto:
 445         nf_ct_l4proto_unregister(builtin_l4proto6,
 446                                  ARRAY_SIZE(builtin_l4proto6));
 447  cleanup_pernet:
 448         unregister_pernet_subsys(&ipv6_net_ops);
 449  cleanup_sockopt:
 450         nf_unregister_sockopt(&so_getorigdst6);
 451         return ret;
 452 }
 453
 454 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 455 {
 456         synchronize_net();
 457         nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 458         nf_ct_l4proto_unregister(builtin_l4proto6,
 459                                  ARRAY_SIZE(builtin_l4proto6));
 460         unregister_pernet_subsys(&ipv6_net_ops);
 461         nf_unregister_sockopt(&so_getorigdst6);
 462 }
 463
 464 module_init(nf_conntrack_l3proto_ipv6_init);
 465 module_exit(nf_conntrack_l3proto_ipv6_fini);