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 void ipv6_print_tuple(struct seq_file *s,
  71                             const struct nf_conntrack_tuple *tuple)
  72 {
  73         seq_printf(s, "src=%pI6 dst=%pI6 ",
  74                    tuple->src.u3.ip6, tuple->dst.u3.ip6);
  75 }
  76
  77 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
  78                             unsigned int *dataoff, u_int8_t *protonum)
  79 {
  80         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
  81         __be16 frag_off;
  82         int protoff;
  83         u8 nexthdr;
  84
  85         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
  86                           &nexthdr, sizeof(nexthdr)) != 0) {
  87                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
  88                 return -NF_ACCEPT;
  89         }
  90         protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
  91         /*
  92          * (protoff == skb->len) means the packet has not data, just
  93          * IPv6 and possibly extensions headers, but it is tracked anyway
  94          */
  95         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
  96                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
  97                 return -NF_ACCEPT;
  98         }
  99
 100         *dataoff = protoff;
 101         *protonum = nexthdr;
 102         return NF_ACCEPT;
 103 }
 104
 105 static unsigned int ipv6_helper(void *priv,
 106                                 struct sk_buff *skb,
 107                                 const struct nf_hook_state *state)
 108 {
 109         struct nf_conn *ct;
 110         const struct nf_conn_help *help;
 111         const struct nf_conntrack_helper *helper;
 112         enum ip_conntrack_info ctinfo;
 113         __be16 frag_off;
 114         int protoff;
 115         u8 nexthdr;
 116
 117         /* This is where we call the helper: as the packet goes out. */
 118         ct = nf_ct_get(skb, &ctinfo);
 119         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 120                 return NF_ACCEPT;
 121
 122         help = nfct_help(ct);
 123         if (!help)
 124                 return NF_ACCEPT;
 125         /* rcu_read_lock()ed by nf_hook_thresh */
 126         helper = rcu_dereference(help->helper);
 127         if (!helper)
 128                 return NF_ACCEPT;
 129
 130         nexthdr = ipv6_hdr(skb)->nexthdr;
 131         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
 132                                    &frag_off);
 133         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 134                 pr_debug("proto header not found\n");
 135                 return NF_ACCEPT;
 136         }
 137
 138         return helper->help(skb, protoff, ct, ctinfo);
 139 }
 140
 141 static unsigned int ipv6_confirm(void *priv,
 142                                  struct sk_buff *skb,
 143                                  const struct nf_hook_state *state)
 144 {
 145         struct nf_conn *ct;
 146         enum ip_conntrack_info ctinfo;
 147         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 148         int protoff;
 149         __be16 frag_off;
 150
 151         ct = nf_ct_get(skb, &ctinfo);
 152         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
 153                 goto out;
 154
 155         protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
 156                                    &frag_off);
 157         if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
 158                 pr_debug("proto header not found\n");
 159                 goto out;
 160         }
 161
 162         /* adjust seqs for loopback traffic only in outgoing direction */
 163         if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
 164             !nf_is_loopback_packet(skb)) {
 165                 if (!nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) {
 166                         NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
 167                         return NF_DROP;
 168                 }
 169         }
 170 out:
 171         /* We've seen it coming out the other side: confirm it */
 172         return nf_conntrack_confirm(skb);
 173 }
 174
 175 static unsigned int ipv6_conntrack_in(void *priv,
 176                                       struct sk_buff *skb,
 177                                       const struct nf_hook_state *state)
 178 {
 179         return nf_conntrack_in(state->net, PF_INET6, state->hook, skb);
 180 }
 181
 182 static unsigned int ipv6_conntrack_local(void *priv,
 183                                          struct sk_buff *skb,
 184                                          const struct nf_hook_state *state)
 185 {
 186         /* root is playing with raw sockets. */
 187         if (skb->len < sizeof(struct ipv6hdr)) {
 188                 net_notice_ratelimited("ipv6_conntrack_local: packet too short\n");
 189                 return NF_ACCEPT;
 190         }
 191         return nf_conntrack_in(state->net, PF_INET6, state->hook, skb);
 192 }
 193
 194 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 195         {
 196                 .hook           = ipv6_conntrack_in,
 197                 .pf             = NFPROTO_IPV6,
 198                 .hooknum        = NF_INET_PRE_ROUTING,
 199                 .priority       = NF_IP6_PRI_CONNTRACK,
 200         },
 201         {
 202                 .hook           = ipv6_conntrack_local,
 203                 .pf             = NFPROTO_IPV6,
 204                 .hooknum        = NF_INET_LOCAL_OUT,
 205                 .priority       = NF_IP6_PRI_CONNTRACK,
 206         },
 207         {
 208                 .hook           = ipv6_helper,
 209                 .pf             = NFPROTO_IPV6,
 210                 .hooknum        = NF_INET_POST_ROUTING,
 211                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 212         },
 213         {
 214                 .hook           = ipv6_confirm,
 215                 .pf             = NFPROTO_IPV6,
 216                 .hooknum        = NF_INET_POST_ROUTING,
 217                 .priority       = NF_IP6_PRI_LAST,
 218         },
 219         {
 220                 .hook           = ipv6_helper,
 221                 .pf             = NFPROTO_IPV6,
 222                 .hooknum        = NF_INET_LOCAL_IN,
 223                 .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
 224         },
 225         {
 226                 .hook           = ipv6_confirm,
 227                 .pf             = NFPROTO_IPV6,
 228                 .hooknum        = NF_INET_LOCAL_IN,
 229                 .priority       = NF_IP6_PRI_LAST-1,
 230         },
 231 };
 232
 233 static int
 234 ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 235 {
 236         const struct inet_sock *inet = inet_sk(sk);
 237         const struct ipv6_pinfo *inet6 = inet6_sk(sk);
 238         const struct nf_conntrack_tuple_hash *h;
 239         struct sockaddr_in6 sin6;
 240         struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
 241         struct nf_conn *ct;
 242
 243         tuple.src.u3.in6 = sk->sk_v6_rcv_saddr;
 244         tuple.src.u.tcp.port = inet->inet_sport;
 245         tuple.dst.u3.in6 = sk->sk_v6_daddr;
 246         tuple.dst.u.tcp.port = inet->inet_dport;
 247         tuple.dst.protonum = sk->sk_protocol;
 248
 249         if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != 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 = inet6->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,
 274                                                  sk->sk_bound_dev_if);
 275         return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
 276 }
 277
 278 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 279
 280 #include <linux/netfilter/nfnetlink.h>
 281 #include <linux/netfilter/nfnetlink_conntrack.h>
 282
 283 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 284                                 const struct nf_conntrack_tuple *tuple)
 285 {
 286         if (nla_put_in6_addr(skb, CTA_IP_V6_SRC, &tuple->src.u3.in6) ||
 287             nla_put_in6_addr(skb, CTA_IP_V6_DST, &tuple->dst.u3.in6))
 288                 goto nla_put_failure;
 289         return 0;
 290
 291 nla_put_failure:
 292         return -1;
 293 }
 294
 295 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 296         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 297         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 298 };
 299
 300 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 301                                 struct nf_conntrack_tuple *t)
 302 {
 303         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 304                 return -EINVAL;
 305
 306         t->src.u3.in6 = nla_get_in6_addr(tb[CTA_IP_V6_SRC]);
 307         t->dst.u3.in6 = nla_get_in6_addr(tb[CTA_IP_V6_DST]);
 308
 309         return 0;
 310 }
 311
 312 static int ipv6_nlattr_tuple_size(void)
 313 {
 314         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 315 }
 316 #endif
 317
 318 static int ipv6_hooks_register(struct net *net)
 319 {
 320         struct conntrack6_net *cnet = net_generic(net, conntrack6_net_id);
 321         int err = 0;
 322
 323         mutex_lock(&register_ipv6_hooks);
 324         cnet->users++;
 325         if (cnet->users > 1)
 326                 goto out_unlock;
 327
 328         err = nf_defrag_ipv6_enable(net);
 329         if (err < 0) {
 330                 cnet->users = 0;
 331                 goto out_unlock;
 332         }
 333
 334         err = nf_register_net_hooks(net, ipv6_conntrack_ops,
 335                                     ARRAY_SIZE(ipv6_conntrack_ops));
 336         if (err)
 337                 cnet->users = 0;
 338  out_unlock:
 339         mutex_unlock(&register_ipv6_hooks);
 340         return err;
 341 }
 342
 343 static void ipv6_hooks_unregister(struct net *net)
 344 {
 345         struct conntrack6_net *cnet = net_generic(net, conntrack6_net_id);
 346
 347         mutex_lock(&register_ipv6_hooks);
 348         if (cnet->users && (--cnet->users == 0))
 349                 nf_unregister_net_hooks(net, ipv6_conntrack_ops,
 350                                         ARRAY_SIZE(ipv6_conntrack_ops));
 351         mutex_unlock(&register_ipv6_hooks);
 352 }
 353
 354 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 355         .l3proto                = PF_INET6,
 356         .name                   = "ipv6",
 357         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 358         .invert_tuple           = ipv6_invert_tuple,
 359         .print_tuple            = ipv6_print_tuple,
 360         .get_l4proto            = ipv6_get_l4proto,
 361 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 362         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 363         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 364         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 365         .nla_policy             = ipv6_nla_policy,
 366 #endif
 367         .net_ns_get             = ipv6_hooks_register,
 368         .net_ns_put             = ipv6_hooks_unregister,
 369         .me                     = THIS_MODULE,
 370 };
 371
 372 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 373 MODULE_LICENSE("GPL");
 374 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 375
 376 static struct nf_sockopt_ops so_getorigdst6 = {
 377         .pf             = NFPROTO_IPV6,
 378         .get_optmin     = IP6T_SO_ORIGINAL_DST,
 379         .get_optmax     = IP6T_SO_ORIGINAL_DST + 1,
 380         .get            = ipv6_getorigdst,
 381         .owner          = THIS_MODULE,
 382 };
 383
 384 static struct nf_conntrack_l4proto *builtin_l4proto6[] = {
 385         &nf_conntrack_l4proto_tcp6,
 386         &nf_conntrack_l4proto_udp6,
 387         &nf_conntrack_l4proto_icmpv6,
 388 #ifdef CONFIG_NF_CT_PROTO_DCCP
 389         &nf_conntrack_l4proto_dccp6,
 390 #endif
 391 #ifdef CONFIG_NF_CT_PROTO_SCTP
 392         &nf_conntrack_l4proto_sctp6,
 393 #endif
 394 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 395         &nf_conntrack_l4proto_udplite6,
 396 #endif
 397 };
 398
 399 static int ipv6_net_init(struct net *net)
 400 {
 401         int ret = 0;
 402
 403         ret = nf_ct_l4proto_pernet_register(net, builtin_l4proto6,
 404                                             ARRAY_SIZE(builtin_l4proto6));
 405         if (ret < 0)
 406                 return ret;
 407
 408         ret = nf_ct_l3proto_pernet_register(net, &nf_conntrack_l3proto_ipv6);
 409         if (ret < 0) {
 410                 pr_err("nf_conntrack_ipv6: pernet registration failed.\n");
 411                 nf_ct_l4proto_pernet_unregister(net, builtin_l4proto6,
 412                                                 ARRAY_SIZE(builtin_l4proto6));
 413         }
 414         return ret;
 415 }
 416
 417 static void ipv6_net_exit(struct net *net)
 418 {
 419         nf_ct_l3proto_pernet_unregister(net, &nf_conntrack_l3proto_ipv6);
 420         nf_ct_l4proto_pernet_unregister(net, builtin_l4proto6,
 421                                         ARRAY_SIZE(builtin_l4proto6));
 422 }
 423
 424 static struct pernet_operations ipv6_net_ops = {
 425         .init = ipv6_net_init,
 426         .exit = ipv6_net_exit,
 427         .id = &conntrack6_net_id,
 428         .size = sizeof(struct conntrack6_net),
 429 };
 430
 431 static int __init nf_conntrack_l3proto_ipv6_init(void)
 432 {
 433         int ret = 0;
 434
 435         need_conntrack();
 436
 437         ret = nf_register_sockopt(&so_getorigdst6);
 438         if (ret < 0) {
 439                 pr_err("Unable to register netfilter socket option\n");
 440                 return ret;
 441         }
 442
 443         ret = register_pernet_subsys(&ipv6_net_ops);
 444         if (ret < 0)
 445                 goto cleanup_sockopt;
 446
 447         ret = nf_ct_l4proto_register(builtin_l4proto6,
 448                                      ARRAY_SIZE(builtin_l4proto6));
 449         if (ret < 0)
 450                 goto cleanup_pernet;
 451
 452         ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv6);
 453         if (ret < 0) {
 454                 pr_err("nf_conntrack_ipv6: can't register ipv6 proto.\n");
 455                 goto cleanup_l4proto;
 456         }
 457         return ret;
 458 cleanup_l4proto:
 459         nf_ct_l4proto_unregister(builtin_l4proto6,
 460                                  ARRAY_SIZE(builtin_l4proto6));
 461  cleanup_pernet:
 462         unregister_pernet_subsys(&ipv6_net_ops);
 463  cleanup_sockopt:
 464         nf_unregister_sockopt(&so_getorigdst6);
 465         return ret;
 466 }
 467
 468 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 469 {
 470         synchronize_net();
 471         nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 472         nf_ct_l4proto_unregister(builtin_l4proto6,
 473                                  ARRAY_SIZE(builtin_l4proto6));
 474         unregister_pernet_subsys(&ipv6_net_ops);
 475         nf_unregister_sockopt(&so_getorigdst6);
 476 }
 477
 478 module_init(nf_conntrack_l3proto_ipv6_init);
 479 module_exit(nf_conntrack_l3proto_ipv6_fini);