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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_ipv6.h>
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <net/netfilter/nf_conntrack_helper.h>
  26 #include <net/netfilter/nf_conntrack_l4proto.h>
  27 #include <net/netfilter/nf_conntrack_l3proto.h>
  28 #include <net/netfilter/nf_conntrack_core.h>
  29 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  30
  31 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  32                               struct nf_conntrack_tuple *tuple)
  33 {
  34         const u_int32_t *ap;
  35         u_int32_t _addrs[8];
  36
  37         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  38                                 sizeof(_addrs), _addrs);
  39         if (ap == NULL)
  40                 return false;
  41
  42         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  43         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  44
  45         return true;
  46 }
  47
  48 static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  49                               const struct nf_conntrack_tuple *orig)
  50 {
  51         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  52         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  53
  54         return true;
  55 }
  56
  57 static int ipv6_print_tuple(struct seq_file *s,
  58                             const struct nf_conntrack_tuple *tuple)
  59 {
  60         return seq_printf(s, "src=%pI6 dst=%pI6 ",
  61                           tuple->src.u3.ip6, tuple->dst.u3.ip6);
  62 }
  63
  64 /*
  65  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  66  *
  67  * This function parses (probably truncated) exthdr set "hdr"
  68  * of length "len". "nexthdrp" initially points to some place,
  69  * where type of the first header can be found.
  70  *
  71  * It skips all well-known exthdrs, and returns pointer to the start
  72  * of unparsable area i.e. the first header with unknown type.
  73  * if success, *nexthdr is updated by type/protocol of this header.
  74  *
  75  * NOTES: - it may return pointer pointing beyond end of packet,
  76  *          if the last recognized header is truncated in the middle.
  77  *        - if packet is truncated, so that all parsed headers are skipped,
  78  *          it returns -1.
  79  *        - if packet is fragmented, return pointer of the fragment header.
  80  *        - ESP is unparsable for now and considered like
  81  *          normal payload protocol.
  82  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  83  */
  84
  85 static int nf_ct_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
  86                                   u8 *nexthdrp, int len)
  87 {
  88         u8 nexthdr = *nexthdrp;
  89
  90         while (ipv6_ext_hdr(nexthdr)) {
  91                 struct ipv6_opt_hdr hdr;
  92                 int hdrlen;
  93
  94                 if (len < (int)sizeof(struct ipv6_opt_hdr))
  95                         return -1;
  96                 if (nexthdr == NEXTHDR_NONE)
  97                         break;
  98                 if (nexthdr == NEXTHDR_FRAGMENT)
  99                         break;
 100                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 101                         BUG();
 102                 if (nexthdr == NEXTHDR_AUTH)
 103                         hdrlen = (hdr.hdrlen+2)<<2;
 104                 else
 105                         hdrlen = ipv6_optlen(&hdr);
 106
 107                 nexthdr = hdr.nexthdr;
 108                 len -= hdrlen;
 109                 start += hdrlen;
 110         }
 111
 112         *nexthdrp = nexthdr;
 113         return start;
 114 }
 115
 116 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
 117                             unsigned int *dataoff, u_int8_t *protonum)
 118 {
 119         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
 120         unsigned char pnum;
 121         int protoff;
 122
 123         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
 124                           &pnum, sizeof(pnum)) != 0) {
 125                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
 126                 return -NF_ACCEPT;
 127         }
 128         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff);
 129         /*
 130          * (protoff == skb->len) mean that the packet doesn't have no data
 131          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 132          */
 133         if ((protoff < 0) || (protoff > skb->len)) {
 134                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
 135                 return -NF_ACCEPT;
 136         }
 137
 138         *dataoff = protoff;
 139         *protonum = pnum;
 140         return NF_ACCEPT;
 141 }
 142
 143 static unsigned int ipv6_confirm(unsigned int hooknum,
 144                                  struct sk_buff *skb,
 145                                  const struct net_device *in,
 146                                  const struct net_device *out,
 147                                  int (*okfn)(struct sk_buff *))
 148 {
 149         struct nf_conn *ct;
 150         const struct nf_conn_help *help;
 151         const struct nf_conntrack_helper *helper;
 152         enum ip_conntrack_info ctinfo;
 153         unsigned int ret, protoff;
 154         unsigned int extoff = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;
 155         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 156
 157
 158         /* This is where we call the helper: as the packet goes out. */
 159         ct = nf_ct_get(skb, &ctinfo);
 160         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 161                 goto out;
 162
 163         help = nfct_help(ct);
 164         if (!help)
 165                 goto out;
 166         /* rcu_read_lock()ed by nf_hook_slow */
 167         helper = rcu_dereference(help->helper);
 168         if (!helper)
 169                 goto out;
 170
 171         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum,
 172                                          skb->len - extoff);
 173         if (protoff > skb->len || pnum == NEXTHDR_FRAGMENT) {
 174                 pr_debug("proto header not found\n");
 175                 return NF_ACCEPT;
 176         }
 177
 178         ret = helper->help(skb, protoff, ct, ctinfo);
 179         if (ret != NF_ACCEPT)
 180                 return ret;
 181 out:
 182         /* We've seen it coming out the other side: confirm it */
 183         return nf_conntrack_confirm(skb);
 184 }
 185
 186 static unsigned int ipv6_defrag(unsigned int hooknum,
 187                                 struct sk_buff *skb,
 188                                 const struct net_device *in,
 189                                 const struct net_device *out,
 190                                 int (*okfn)(struct sk_buff *))
 191 {
 192         struct sk_buff *reasm;
 193
 194         /* Previously seen (loopback)?  */
 195         if (skb->nfct)
 196                 return NF_ACCEPT;
 197
 198         reasm = nf_ct_frag6_gather(skb);
 199
 200         /* queued */
 201         if (reasm == NULL)
 202                 return NF_STOLEN;
 203
 204         /* error occured or not fragmented */
 205         if (reasm == skb)
 206                 return NF_ACCEPT;
 207
 208         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 209                            (struct net_device *)out, okfn);
 210
 211         return NF_STOLEN;
 212 }
 213
 214 static unsigned int __ipv6_conntrack_in(struct net *net,
 215                                         unsigned int hooknum,
 216                                         struct sk_buff *skb,
 217                                         int (*okfn)(struct sk_buff *))
 218 {
 219         struct sk_buff *reasm = skb->nfct_reasm;
 220
 221         /* This packet is fragmented and has reassembled packet. */
 222         if (reasm) {
 223                 /* Reassembled packet isn't parsed yet ? */
 224                 if (!reasm->nfct) {
 225                         unsigned int ret;
 226
 227                         ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
 228                         if (ret != NF_ACCEPT)
 229                                 return ret;
 230                 }
 231                 nf_conntrack_get(reasm->nfct);
 232                 skb->nfct = reasm->nfct;
 233                 skb->nfctinfo = reasm->nfctinfo;
 234                 return NF_ACCEPT;
 235         }
 236
 237         return nf_conntrack_in(net, PF_INET6, hooknum, skb);
 238 }
 239
 240 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 241                                       struct sk_buff *skb,
 242                                       const struct net_device *in,
 243                                       const struct net_device *out,
 244                                       int (*okfn)(struct sk_buff *))
 245 {
 246         return __ipv6_conntrack_in(dev_net(in), hooknum, skb, okfn);
 247 }
 248
 249 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 250                                          struct sk_buff *skb,
 251                                          const struct net_device *in,
 252                                          const struct net_device *out,
 253                                          int (*okfn)(struct sk_buff *))
 254 {
 255         /* root is playing with raw sockets. */
 256         if (skb->len < sizeof(struct ipv6hdr)) {
 257                 if (net_ratelimit())
 258                         printk("ipv6_conntrack_local: packet too short\n");
 259                 return NF_ACCEPT;
 260         }
 261         return __ipv6_conntrack_in(dev_net(out), hooknum, skb, okfn);
 262 }
 263
 264 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 265         {
 266                 .hook           = ipv6_defrag,
 267                 .owner          = THIS_MODULE,
 268                 .pf             = NFPROTO_IPV6,
 269                 .hooknum        = NF_INET_PRE_ROUTING,
 270                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 271         },
 272         {
 273                 .hook           = ipv6_conntrack_in,
 274                 .owner          = THIS_MODULE,
 275                 .pf             = NFPROTO_IPV6,
 276                 .hooknum        = NF_INET_PRE_ROUTING,
 277                 .priority       = NF_IP6_PRI_CONNTRACK,
 278         },
 279         {
 280                 .hook           = ipv6_conntrack_local,
 281                 .owner          = THIS_MODULE,
 282                 .pf             = NFPROTO_IPV6,
 283                 .hooknum        = NF_INET_LOCAL_OUT,
 284                 .priority       = NF_IP6_PRI_CONNTRACK,
 285         },
 286         {
 287                 .hook           = ipv6_defrag,
 288                 .owner          = THIS_MODULE,
 289                 .pf             = NFPROTO_IPV6,
 290                 .hooknum        = NF_INET_LOCAL_OUT,
 291                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 292         },
 293         {
 294                 .hook           = ipv6_confirm,
 295                 .owner          = THIS_MODULE,
 296                 .pf             = NFPROTO_IPV6,
 297                 .hooknum        = NF_INET_POST_ROUTING,
 298                 .priority       = NF_IP6_PRI_LAST,
 299         },
 300         {
 301                 .hook           = ipv6_confirm,
 302                 .owner          = THIS_MODULE,
 303                 .pf             = NFPROTO_IPV6,
 304                 .hooknum        = NF_INET_LOCAL_IN,
 305                 .priority       = NF_IP6_PRI_LAST-1,
 306         },
 307 };
 308
 309 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 310
 311 #include <linux/netfilter/nfnetlink.h>
 312 #include <linux/netfilter/nfnetlink_conntrack.h>
 313
 314 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 315                                 const struct nf_conntrack_tuple *tuple)
 316 {
 317         NLA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 318                 &tuple->src.u3.ip6);
 319         NLA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 320                 &tuple->dst.u3.ip6);
 321         return 0;
 322
 323 nla_put_failure:
 324         return -1;
 325 }
 326
 327 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 328         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 329         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 330 };
 331
 332 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 333                                 struct nf_conntrack_tuple *t)
 334 {
 335         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 336                 return -EINVAL;
 337
 338         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 339                sizeof(u_int32_t) * 4);
 340         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 341                sizeof(u_int32_t) * 4);
 342
 343         return 0;
 344 }
 345
 346 static int ipv6_nlattr_tuple_size(void)
 347 {
 348         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 349 }
 350 #endif
 351
 352 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 353         .l3proto                = PF_INET6,
 354         .name                   = "ipv6",
 355         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 356         .invert_tuple           = ipv6_invert_tuple,
 357         .print_tuple            = ipv6_print_tuple,
 358         .get_l4proto            = ipv6_get_l4proto,
 359 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 360         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 361         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 362         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 363         .nla_policy             = ipv6_nla_policy,
 364 #endif
 365 #ifdef CONFIG_SYSCTL
 366         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 367         .ctl_table              = nf_ct_ipv6_sysctl_table,
 368 #endif
 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 int __init nf_conntrack_l3proto_ipv6_init(void)
 377 {
 378         int ret = 0;
 379
 380         need_conntrack();
 381
 382         ret = nf_ct_frag6_init();
 383         if (ret < 0) {
 384                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 385                 return ret;
 386         }
 387         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 388         if (ret < 0) {
 389                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 390                 goto cleanup_frag6;
 391         }
 392
 393         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 394         if (ret < 0) {
 395                 printk("nf_conntrack_ipv6: can't register udp.\n");
 396                 goto cleanup_tcp;
 397         }
 398
 399         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 400         if (ret < 0) {
 401                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 402                 goto cleanup_udp;
 403         }
 404
 405         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 406         if (ret < 0) {
 407                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 408                 goto cleanup_icmpv6;
 409         }
 410
 411         ret = nf_register_hooks(ipv6_conntrack_ops,
 412                                 ARRAY_SIZE(ipv6_conntrack_ops));
 413         if (ret < 0) {
 414                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 415                        "hook.\n");
 416                 goto cleanup_ipv6;
 417         }
 418         return ret;
 419
 420  cleanup_ipv6:
 421         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 422  cleanup_icmpv6:
 423         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 424  cleanup_udp:
 425         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 426  cleanup_tcp:
 427         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 428  cleanup_frag6:
 429         nf_ct_frag6_cleanup();
 430         return ret;
 431 }
 432
 433 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 434 {
 435         synchronize_net();
 436         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 437         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 438         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 439         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 440         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 441         nf_ct_frag6_cleanup();
 442 }
 443
 444 module_init(nf_conntrack_l3proto_ipv6_init);
 445 module_exit(nf_conntrack_l3proto_ipv6_fini);