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   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 <linux/sysctl.h>
  20 #include <net/ipv6.h>
  21 #include <net/inet_frag.h>
  22
  23 #include <linux/netfilter_bridge.h>
  24 #include <linux/netfilter_ipv6.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_log.h>
  33
  34 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  35                               struct nf_conntrack_tuple *tuple)
  36 {
  37         const u_int32_t *ap;
  38         u_int32_t _addrs[8];
  39
  40         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  41                                 sizeof(_addrs), _addrs);
  42         if (ap == NULL)
  43                 return false;
  44
  45         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  46         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  47
  48         return true;
  49 }
  50
  51 static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  52                               const struct nf_conntrack_tuple *orig)
  53 {
  54         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  55         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  56
  57         return true;
  58 }
  59
  60 static int ipv6_print_tuple(struct seq_file *s,
  61                             const struct nf_conntrack_tuple *tuple)
  62 {
  63         return seq_printf(s, "src=%pI6 dst=%pI6 ",
  64                           tuple->src.u3.ip6, tuple->dst.u3.ip6);
  65 }
  66
  67 /*
  68  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  69  *
  70  * This function parses (probably truncated) exthdr set "hdr"
  71  * of length "len". "nexthdrp" initially points to some place,
  72  * where type of the first header can be found.
  73  *
  74  * It skips all well-known exthdrs, and returns pointer to the start
  75  * of unparsable area i.e. the first header with unknown type.
  76  * if success, *nexthdr is updated by type/protocol of this header.
  77  *
  78  * NOTES: - it may return pointer pointing beyond end of packet,
  79  *          if the last recognized header is truncated in the middle.
  80  *        - if packet is truncated, so that all parsed headers are skipped,
  81  *          it returns -1.
  82  *        - if packet is fragmented, return pointer of the fragment header.
  83  *        - ESP is unparsable for now and considered like
  84  *          normal payload protocol.
  85  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  86  */
  87
  88 static int nf_ct_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
  89                                   u8 *nexthdrp, int len)
  90 {
  91         u8 nexthdr = *nexthdrp;
  92
  93         while (ipv6_ext_hdr(nexthdr)) {
  94                 struct ipv6_opt_hdr hdr;
  95                 int hdrlen;
  96
  97                 if (len < (int)sizeof(struct ipv6_opt_hdr))
  98                         return -1;
  99                 if (nexthdr == NEXTHDR_NONE)
 100                         break;
 101                 if (nexthdr == NEXTHDR_FRAGMENT)
 102                         break;
 103                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 104                         BUG();
 105                 if (nexthdr == NEXTHDR_AUTH)
 106                         hdrlen = (hdr.hdrlen+2)<<2;
 107                 else
 108                         hdrlen = ipv6_optlen(&hdr);
 109
 110                 nexthdr = hdr.nexthdr;
 111                 len -= hdrlen;
 112                 start += hdrlen;
 113         }
 114
 115         *nexthdrp = nexthdr;
 116         return start;
 117 }
 118
 119 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
 120                             unsigned int *dataoff, u_int8_t *protonum)
 121 {
 122         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
 123         unsigned char pnum;
 124         int protoff;
 125
 126         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
 127                           &pnum, sizeof(pnum)) != 0) {
 128                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
 129                 return -NF_ACCEPT;
 130         }
 131         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff);
 132         /*
 133          * (protoff == skb->len) mean that the packet doesn't have no data
 134          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 135          */
 136         if ((protoff < 0) || (protoff > skb->len)) {
 137                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
 138                 return -NF_ACCEPT;
 139         }
 140
 141         *dataoff = protoff;
 142         *protonum = pnum;
 143         return NF_ACCEPT;
 144 }
 145
 146 static unsigned int ipv6_confirm(unsigned int hooknum,
 147                                  struct sk_buff *skb,
 148                                  const struct net_device *in,
 149                                  const struct net_device *out,
 150                                  int (*okfn)(struct sk_buff *))
 151 {
 152         struct nf_conn *ct;
 153         const struct nf_conn_help *help;
 154         const struct nf_conntrack_helper *helper;
 155         enum ip_conntrack_info ctinfo;
 156         unsigned int ret, protoff;
 157         unsigned int extoff = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;
 158         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 159
 160
 161         /* This is where we call the helper: as the packet goes out. */
 162         ct = nf_ct_get(skb, &ctinfo);
 163         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 164                 goto out;
 165
 166         help = nfct_help(ct);
 167         if (!help)
 168                 goto out;
 169         /* rcu_read_lock()ed by nf_hook_slow */
 170         helper = rcu_dereference(help->helper);
 171         if (!helper)
 172                 goto out;
 173
 174         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum,
 175                                          skb->len - extoff);
 176         if (protoff > skb->len || pnum == NEXTHDR_FRAGMENT) {
 177                 pr_debug("proto header not found\n");
 178                 return NF_ACCEPT;
 179         }
 180
 181         ret = helper->help(skb, protoff, ct, ctinfo);
 182         if (ret != NF_ACCEPT) {
 183                 nf_log_packet(NFPROTO_IPV6, hooknum, skb, in, out, NULL,
 184                               "nf_ct_%s: dropping packet", helper->name);
 185                 return ret;
 186         }
 187 out:
 188         /* We've seen it coming out the other side: confirm it */
 189         return nf_conntrack_confirm(skb);
 190 }
 191
 192 static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
 193                                                 struct sk_buff *skb)
 194 {
 195         u16 zone = NF_CT_DEFAULT_ZONE;
 196
 197         if (skb->nfct)
 198                 zone = nf_ct_zone((struct nf_conn *)skb->nfct);
 199
 200 #ifdef CONFIG_BRIDGE_NETFILTER
 201         if (skb->nf_bridge &&
 202             skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
 203                 return IP6_DEFRAG_CONNTRACK_BRIDGE_IN + zone;
 204 #endif
 205         if (hooknum == NF_INET_PRE_ROUTING)
 206                 return IP6_DEFRAG_CONNTRACK_IN + zone;
 207         else
 208                 return IP6_DEFRAG_CONNTRACK_OUT + zone;
 209
 210 }
 211
 212 static unsigned int ipv6_defrag(unsigned int hooknum,
 213                                 struct sk_buff *skb,
 214                                 const struct net_device *in,
 215                                 const struct net_device *out,
 216                                 int (*okfn)(struct sk_buff *))
 217 {
 218         struct sk_buff *reasm;
 219
 220         /* Previously seen (loopback)?  */
 221         if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
 222                 return NF_ACCEPT;
 223
 224         reasm = nf_ct_frag6_gather(skb, nf_ct6_defrag_user(hooknum, skb));
 225         /* queued */
 226         if (reasm == NULL)
 227                 return NF_STOLEN;
 228
 229         /* error occured or not fragmented */
 230         if (reasm == skb)
 231                 return NF_ACCEPT;
 232
 233         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 234                            (struct net_device *)out, okfn);
 235
 236         return NF_STOLEN;
 237 }
 238
 239 static unsigned int __ipv6_conntrack_in(struct net *net,
 240                                         unsigned int hooknum,
 241                                         struct sk_buff *skb,
 242                                         int (*okfn)(struct sk_buff *))
 243 {
 244         struct sk_buff *reasm = skb->nfct_reasm;
 245
 246         /* This packet is fragmented and has reassembled packet. */
 247         if (reasm) {
 248                 /* Reassembled packet isn't parsed yet ? */
 249                 if (!reasm->nfct) {
 250                         unsigned int ret;
 251
 252                         ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
 253                         if (ret != NF_ACCEPT)
 254                                 return ret;
 255                 }
 256                 nf_conntrack_get(reasm->nfct);
 257                 skb->nfct = reasm->nfct;
 258                 skb->nfctinfo = reasm->nfctinfo;
 259                 return NF_ACCEPT;
 260         }
 261
 262         return nf_conntrack_in(net, PF_INET6, hooknum, skb);
 263 }
 264
 265 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 266                                       struct sk_buff *skb,
 267                                       const struct net_device *in,
 268                                       const struct net_device *out,
 269                                       int (*okfn)(struct sk_buff *))
 270 {
 271         return __ipv6_conntrack_in(dev_net(in), hooknum, skb, okfn);
 272 }
 273
 274 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 275                                          struct sk_buff *skb,
 276                                          const struct net_device *in,
 277                                          const struct net_device *out,
 278                                          int (*okfn)(struct sk_buff *))
 279 {
 280         /* root is playing with raw sockets. */
 281         if (skb->len < sizeof(struct ipv6hdr)) {
 282                 if (net_ratelimit())
 283                         pr_notice("ipv6_conntrack_local: packet too short\n");
 284                 return NF_ACCEPT;
 285         }
 286         return __ipv6_conntrack_in(dev_net(out), hooknum, skb, okfn);
 287 }
 288
 289 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 290         {
 291                 .hook           = ipv6_defrag,
 292                 .owner          = THIS_MODULE,
 293                 .pf             = NFPROTO_IPV6,
 294                 .hooknum        = NF_INET_PRE_ROUTING,
 295                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 296         },
 297         {
 298                 .hook           = ipv6_conntrack_in,
 299                 .owner          = THIS_MODULE,
 300                 .pf             = NFPROTO_IPV6,
 301                 .hooknum        = NF_INET_PRE_ROUTING,
 302                 .priority       = NF_IP6_PRI_CONNTRACK,
 303         },
 304         {
 305                 .hook           = ipv6_conntrack_local,
 306                 .owner          = THIS_MODULE,
 307                 .pf             = NFPROTO_IPV6,
 308                 .hooknum        = NF_INET_LOCAL_OUT,
 309                 .priority       = NF_IP6_PRI_CONNTRACK,
 310         },
 311         {
 312                 .hook           = ipv6_defrag,
 313                 .owner          = THIS_MODULE,
 314                 .pf             = NFPROTO_IPV6,
 315                 .hooknum        = NF_INET_LOCAL_OUT,
 316                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 317         },
 318         {
 319                 .hook           = ipv6_confirm,
 320                 .owner          = THIS_MODULE,
 321                 .pf             = NFPROTO_IPV6,
 322                 .hooknum        = NF_INET_POST_ROUTING,
 323                 .priority       = NF_IP6_PRI_LAST,
 324         },
 325         {
 326                 .hook           = ipv6_confirm,
 327                 .owner          = THIS_MODULE,
 328                 .pf             = NFPROTO_IPV6,
 329                 .hooknum        = NF_INET_LOCAL_IN,
 330                 .priority       = NF_IP6_PRI_LAST-1,
 331         },
 332 };
 333
 334 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 335
 336 #include <linux/netfilter/nfnetlink.h>
 337 #include <linux/netfilter/nfnetlink_conntrack.h>
 338
 339 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 340                                 const struct nf_conntrack_tuple *tuple)
 341 {
 342         NLA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 343                 &tuple->src.u3.ip6);
 344         NLA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 345                 &tuple->dst.u3.ip6);
 346         return 0;
 347
 348 nla_put_failure:
 349         return -1;
 350 }
 351
 352 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 353         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 354         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 355 };
 356
 357 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 358                                 struct nf_conntrack_tuple *t)
 359 {
 360         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 361                 return -EINVAL;
 362
 363         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 364                sizeof(u_int32_t) * 4);
 365         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 366                sizeof(u_int32_t) * 4);
 367
 368         return 0;
 369 }
 370
 371 static int ipv6_nlattr_tuple_size(void)
 372 {
 373         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 374 }
 375 #endif
 376
 377 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 378         .l3proto                = PF_INET6,
 379         .name                   = "ipv6",
 380         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 381         .invert_tuple           = ipv6_invert_tuple,
 382         .print_tuple            = ipv6_print_tuple,
 383         .get_l4proto            = ipv6_get_l4proto,
 384 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 385         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 386         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 387         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 388         .nla_policy             = ipv6_nla_policy,
 389 #endif
 390 #ifdef CONFIG_SYSCTL
 391         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 392         .ctl_table              = nf_ct_ipv6_sysctl_table,
 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 int __init nf_conntrack_l3proto_ipv6_init(void)
 402 {
 403         int ret = 0;
 404
 405         need_conntrack();
 406
 407         ret = nf_ct_frag6_init();
 408         if (ret < 0) {
 409                 pr_err("nf_conntrack_ipv6: can't initialize frag6.\n");
 410                 return ret;
 411         }
 412         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 413         if (ret < 0) {
 414                 pr_err("nf_conntrack_ipv6: can't register tcp.\n");
 415                 goto cleanup_frag6;
 416         }
 417
 418         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 419         if (ret < 0) {
 420                 pr_err("nf_conntrack_ipv6: can't register udp.\n");
 421                 goto cleanup_tcp;
 422         }
 423
 424         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 425         if (ret < 0) {
 426                 pr_err("nf_conntrack_ipv6: can't register icmpv6.\n");
 427                 goto cleanup_udp;
 428         }
 429
 430         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 431         if (ret < 0) {
 432                 pr_err("nf_conntrack_ipv6: can't register ipv6\n");
 433                 goto cleanup_icmpv6;
 434         }
 435
 436         ret = nf_register_hooks(ipv6_conntrack_ops,
 437                                 ARRAY_SIZE(ipv6_conntrack_ops));
 438         if (ret < 0) {
 439                 pr_err("nf_conntrack_ipv6: can't register pre-routing defrag "
 440                        "hook.\n");
 441                 goto cleanup_ipv6;
 442         }
 443         return ret;
 444
 445  cleanup_ipv6:
 446         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 447  cleanup_icmpv6:
 448         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 449  cleanup_udp:
 450         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 451  cleanup_tcp:
 452         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 453  cleanup_frag6:
 454         nf_ct_frag6_cleanup();
 455         return ret;
 456 }
 457
 458 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 459 {
 460         synchronize_net();
 461         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 462         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 463         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 464         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 465         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 466         nf_ct_frag6_cleanup();
 467 }
 468
 469 module_init(nf_conntrack_l3proto_ipv6_init);
 470 module_exit(nf_conntrack_l3proto_ipv6_fini);