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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
  22 #include <linux/netfilter_ipv6.h>
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_helper.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_l3proto.h>
  27 #include <net/netfilter/nf_conntrack_core.h>
  28
  29 static int ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  30                              struct nf_conntrack_tuple *tuple)
  31 {
  32         u_int32_t _addrs[8], *ap;
  33
  34         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  35                                 sizeof(_addrs), _addrs);
  36         if (ap == NULL)
  37                 return 0;
  38
  39         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  40         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  41
  42         return 1;
  43 }
  44
  45 static int ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  46                              const struct nf_conntrack_tuple *orig)
  47 {
  48         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  49         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  50
  51         return 1;
  52 }
  53
  54 static int ipv6_print_tuple(struct seq_file *s,
  55                             const struct nf_conntrack_tuple *tuple)
  56 {
  57         return seq_printf(s, "src=" NIP6_FMT " dst=" NIP6_FMT " ",
  58                           NIP6(*((struct in6_addr *)tuple->src.u3.ip6)),
  59                           NIP6(*((struct in6_addr *)tuple->dst.u3.ip6)));
  60 }
  61
  62 static int ipv6_print_conntrack(struct seq_file *s,
  63                                 const struct nf_conn *conntrack)
  64 {
  65         return 0;
  66 }
  67
  68 /*
  69  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  70  *
  71  * This function parses (probably truncated) exthdr set "hdr"
  72  * of length "len". "nexthdrp" initially points to some place,
  73  * where type of the first header can be found.
  74  *
  75  * It skips all well-known exthdrs, and returns pointer to the start
  76  * of unparsable area i.e. the first header with unknown type.
  77  * if success, *nexthdr is updated by type/protocol of this header.
  78  *
  79  * NOTES: - it may return pointer pointing beyond end of packet,
  80  *          if the last recognized header is truncated in the middle.
  81  *        - if packet is truncated, so that all parsed headers are skipped,
  82  *          it returns -1.
  83  *        - if packet is fragmented, return pointer of the fragment header.
  84  *        - ESP is unparsable for now and considered like
  85  *          normal payload protocol.
  86  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  87  */
  88
  89 static int nf_ct_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
  90                                   u8 *nexthdrp, int len)
  91 {
  92         u8 nexthdr = *nexthdrp;
  93
  94         while (ipv6_ext_hdr(nexthdr)) {
  95                 struct ipv6_opt_hdr hdr;
  96                 int hdrlen;
  97
  98                 if (len < (int)sizeof(struct ipv6_opt_hdr))
  99                         return -1;
 100                 if (nexthdr == NEXTHDR_NONE)
 101                         break;
 102                 if (nexthdr == NEXTHDR_FRAGMENT)
 103                         break;
 104                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 105                         BUG();
 106                 if (nexthdr == NEXTHDR_AUTH)
 107                         hdrlen = (hdr.hdrlen+2)<<2;
 108                 else
 109                         hdrlen = ipv6_optlen(&hdr);
 110
 111                 nexthdr = hdr.nexthdr;
 112                 len -= hdrlen;
 113                 start += hdrlen;
 114         }
 115
 116         *nexthdrp = nexthdr;
 117         return start;
 118 }
 119
 120 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
 121                             unsigned int *dataoff, u_int8_t *protonum)
 122 {
 123         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
 124         unsigned char pnum;
 125         int protoff;
 126
 127         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
 128                           &pnum, sizeof(pnum)) != 0) {
 129                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
 130                 return -NF_ACCEPT;
 131         }
 132         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff);
 133         /*
 134          * (protoff == skb->len) mean that the packet doesn't have no data
 135          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 136          */
 137         if ((protoff < 0) || (protoff > skb->len)) {
 138                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
 139                 return -NF_ACCEPT;
 140         }
 141
 142         *dataoff = protoff;
 143         *protonum = pnum;
 144         return NF_ACCEPT;
 145 }
 146
 147 static unsigned int ipv6_confirm(unsigned int hooknum,
 148                                  struct sk_buff **pskb,
 149                                  const struct net_device *in,
 150                                  const struct net_device *out,
 151                                  int (*okfn)(struct sk_buff *))
 152 {
 153         struct nf_conn *ct;
 154         struct nf_conn_help *help;
 155         struct nf_conntrack_helper *helper;
 156         enum ip_conntrack_info ctinfo;
 157         unsigned int ret, protoff;
 158         unsigned int extoff = (u8 *)(ipv6_hdr(*pskb) + 1) - (*pskb)->data;
 159         unsigned char pnum = ipv6_hdr(*pskb)->nexthdr;
 160
 161
 162         /* This is where we call the helper: as the packet goes out. */
 163         ct = nf_ct_get(*pskb, &ctinfo);
 164         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 165                 goto out;
 166
 167         help = nfct_help(ct);
 168         if (!help)
 169                 goto out;
 170         /* rcu_read_lock()ed by nf_hook_slow */
 171         helper = rcu_dereference(help->helper);
 172         if (!helper)
 173                 goto out;
 174
 175         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 176                                          (*pskb)->len - extoff);
 177         if (protoff > (*pskb)->len || pnum == NEXTHDR_FRAGMENT) {
 178                 pr_debug("proto header not found\n");
 179                 return NF_ACCEPT;
 180         }
 181
 182         ret = helper->help(pskb, protoff, ct, ctinfo);
 183         if (ret != NF_ACCEPT)
 184                 return ret;
 185 out:
 186         /* We've seen it coming out the other side: confirm it */
 187         return nf_conntrack_confirm(pskb);
 188 }
 189
 190 static unsigned int ipv6_defrag(unsigned int hooknum,
 191                                 struct sk_buff **pskb,
 192                                 const struct net_device *in,
 193                                 const struct net_device *out,
 194                                 int (*okfn)(struct sk_buff *))
 195 {
 196         struct sk_buff *reasm;
 197
 198         /* Previously seen (loopback)?  */
 199         if ((*pskb)->nfct)
 200                 return NF_ACCEPT;
 201
 202         reasm = nf_ct_frag6_gather(*pskb);
 203
 204         /* queued */
 205         if (reasm == NULL)
 206                 return NF_STOLEN;
 207
 208         /* error occured or not fragmented */
 209         if (reasm == *pskb)
 210                 return NF_ACCEPT;
 211
 212         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 213                            (struct net_device *)out, okfn);
 214
 215         return NF_STOLEN;
 216 }
 217
 218 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 219                                       struct sk_buff **pskb,
 220                                       const struct net_device *in,
 221                                       const struct net_device *out,
 222                                       int (*okfn)(struct sk_buff *))
 223 {
 224         struct sk_buff *reasm = (*pskb)->nfct_reasm;
 225
 226         /* This packet is fragmented and has reassembled packet. */
 227         if (reasm) {
 228                 /* Reassembled packet isn't parsed yet ? */
 229                 if (!reasm->nfct) {
 230                         unsigned int ret;
 231
 232                         ret = nf_conntrack_in(PF_INET6, hooknum, &reasm);
 233                         if (ret != NF_ACCEPT)
 234                                 return ret;
 235                 }
 236                 nf_conntrack_get(reasm->nfct);
 237                 (*pskb)->nfct = reasm->nfct;
 238                 (*pskb)->nfctinfo = reasm->nfctinfo;
 239                 return NF_ACCEPT;
 240         }
 241
 242         return nf_conntrack_in(PF_INET6, hooknum, pskb);
 243 }
 244
 245 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 246                                          struct sk_buff **pskb,
 247                                          const struct net_device *in,
 248                                          const struct net_device *out,
 249                                          int (*okfn)(struct sk_buff *))
 250 {
 251         /* root is playing with raw sockets. */
 252         if ((*pskb)->len < sizeof(struct ipv6hdr)) {
 253                 if (net_ratelimit())
 254                         printk("ipv6_conntrack_local: packet too short\n");
 255                 return NF_ACCEPT;
 256         }
 257         return ipv6_conntrack_in(hooknum, pskb, in, out, okfn);
 258 }
 259
 260 static struct nf_hook_ops ipv6_conntrack_ops[] = {
 261         {
 262                 .hook           = ipv6_defrag,
 263                 .owner          = THIS_MODULE,
 264                 .pf             = PF_INET6,
 265                 .hooknum        = NF_IP6_PRE_ROUTING,
 266                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 267         },
 268         {
 269                 .hook           = ipv6_conntrack_in,
 270                 .owner          = THIS_MODULE,
 271                 .pf             = PF_INET6,
 272                 .hooknum        = NF_IP6_PRE_ROUTING,
 273                 .priority       = NF_IP6_PRI_CONNTRACK,
 274         },
 275         {
 276                 .hook           = ipv6_conntrack_local,
 277                 .owner          = THIS_MODULE,
 278                 .pf             = PF_INET6,
 279                 .hooknum        = NF_IP6_LOCAL_OUT,
 280                 .priority       = NF_IP6_PRI_CONNTRACK,
 281         },
 282         {
 283                 .hook           = ipv6_defrag,
 284                 .owner          = THIS_MODULE,
 285                 .pf             = PF_INET6,
 286                 .hooknum        = NF_IP6_LOCAL_OUT,
 287                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 288         },
 289         {
 290                 .hook           = ipv6_confirm,
 291                 .owner          = THIS_MODULE,
 292                 .pf             = PF_INET6,
 293                 .hooknum        = NF_IP6_POST_ROUTING,
 294                 .priority       = NF_IP6_PRI_LAST,
 295         },
 296         {
 297                 .hook           = ipv6_confirm,
 298                 .owner          = THIS_MODULE,
 299                 .pf             = PF_INET6,
 300                 .hooknum        = NF_IP6_LOCAL_IN,
 301                 .priority       = NF_IP6_PRI_LAST-1,
 302         },
 303 };
 304
 305 #ifdef CONFIG_SYSCTL
 306 static ctl_table nf_ct_ipv6_sysctl_table[] = {
 307         {
 308                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_TIMEOUT,
 309                 .procname       = "nf_conntrack_frag6_timeout",
 310                 .data           = &nf_ct_frag6_timeout,
 311                 .maxlen         = sizeof(unsigned int),
 312                 .mode           = 0644,
 313                 .proc_handler   = &proc_dointvec_jiffies,
 314         },
 315         {
 316                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
 317                 .procname       = "nf_conntrack_frag6_low_thresh",
 318                 .data           = &nf_ct_frag6_low_thresh,
 319                 .maxlen         = sizeof(unsigned int),
 320                 .mode           = 0644,
 321                 .proc_handler   = &proc_dointvec,
 322         },
 323         {
 324                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
 325                 .procname       = "nf_conntrack_frag6_high_thresh",
 326                 .data           = &nf_ct_frag6_high_thresh,
 327                 .maxlen         = sizeof(unsigned int),
 328                 .mode           = 0644,
 329                 .proc_handler   = &proc_dointvec,
 330         },
 331         { .ctl_name = 0 }
 332 };
 333 #endif
 334
 335 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 336
 337 #include <linux/netfilter/nfnetlink.h>
 338 #include <linux/netfilter/nfnetlink_conntrack.h>
 339
 340 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 341                                 const struct nf_conntrack_tuple *tuple)
 342 {
 343         NLA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 344                 &tuple->src.u3.ip6);
 345         NLA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 346                 &tuple->dst.u3.ip6);
 347         return 0;
 348
 349 nla_put_failure:
 350         return -1;
 351 }
 352
 353 static const size_t cta_min_ip[CTA_IP_MAX+1] = {
 354         [CTA_IP_V6_SRC] = sizeof(u_int32_t)*4,
 355         [CTA_IP_V6_DST] = sizeof(u_int32_t)*4,
 356 };
 357
 358 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 359                                 struct nf_conntrack_tuple *t)
 360 {
 361         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 362                 return -EINVAL;
 363
 364         if (nlattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 365                 return -EINVAL;
 366
 367         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 368                sizeof(u_int32_t) * 4);
 369         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 370                sizeof(u_int32_t) * 4);
 371
 372         return 0;
 373 }
 374 #endif
 375
 376 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 377         .l3proto                = PF_INET6,
 378         .name                   = "ipv6",
 379         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 380         .invert_tuple           = ipv6_invert_tuple,
 381         .print_tuple            = ipv6_print_tuple,
 382         .print_conntrack        = ipv6_print_conntrack,
 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_to_tuple        = ipv6_nlattr_to_tuple,
 387 #endif
 388 #ifdef CONFIG_SYSCTL
 389         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 390         .ctl_table              = nf_ct_ipv6_sysctl_table,
 391 #endif
 392         .me                     = THIS_MODULE,
 393 };
 394
 395 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 396 MODULE_LICENSE("GPL");
 397 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 398
 399 static int __init nf_conntrack_l3proto_ipv6_init(void)
 400 {
 401         int ret = 0;
 402
 403         need_conntrack();
 404
 405         ret = nf_ct_frag6_init();
 406         if (ret < 0) {
 407                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 408                 return ret;
 409         }
 410         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 411         if (ret < 0) {
 412                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 413                 goto cleanup_frag6;
 414         }
 415
 416         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 417         if (ret < 0) {
 418                 printk("nf_conntrack_ipv6: can't register udp.\n");
 419                 goto cleanup_tcp;
 420         }
 421
 422         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 423         if (ret < 0) {
 424                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 425                 goto cleanup_udp;
 426         }
 427
 428         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 429         if (ret < 0) {
 430                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 431                 goto cleanup_icmpv6;
 432         }
 433
 434         ret = nf_register_hooks(ipv6_conntrack_ops,
 435                                 ARRAY_SIZE(ipv6_conntrack_ops));
 436         if (ret < 0) {
 437                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 438                        "hook.\n");
 439                 goto cleanup_ipv6;
 440         }
 441         return ret;
 442
 443  cleanup_ipv6:
 444         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 445  cleanup_icmpv6:
 446         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 447  cleanup_udp:
 448         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 449  cleanup_tcp:
 450         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 451  cleanup_frag6:
 452         nf_ct_frag6_cleanup();
 453         return ret;
 454 }
 455
 456 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 457 {
 458         synchronize_net();
 459         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 460         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 461         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 462         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 463         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 464         nf_ct_frag6_cleanup();
 465 }
 466
 467 module_init(nf_conntrack_l3proto_ipv6_init);
 468 module_exit(nf_conntrack_l3proto_ipv6_fini);