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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/ipv6/nf_conntrack_ipv6.h>
  31 #include <net/netfilter/nf_log.h>
  32
  33 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  34                               struct nf_conntrack_tuple *tuple)
  35 {
  36         const u_int32_t *ap;
  37         u_int32_t _addrs[8];
  38
  39         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  40                                 sizeof(_addrs), _addrs);
  41         if (ap == NULL)
  42                 return false;
  43
  44         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  45         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  46
  47         return true;
  48 }
  49
  50 static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  51                               const struct nf_conntrack_tuple *orig)
  52 {
  53         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  54         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  55
  56         return true;
  57 }
  58
  59 static int ipv6_print_tuple(struct seq_file *s,
  60                             const struct nf_conntrack_tuple *tuple)
  61 {
  62         return seq_printf(s, "src=%pI6 dst=%pI6 ",
  63                           tuple->src.u3.ip6, tuple->dst.u3.ip6);
  64 }
  65
  66 /*
  67  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  68  *
  69  * This function parses (probably truncated) exthdr set "hdr"
  70  * of length "len". "nexthdrp" initially points to some place,
  71  * where type of the first header can be found.
  72  *
  73  * It skips all well-known exthdrs, and returns pointer to the start
  74  * of unparsable area i.e. the first header with unknown type.
  75  * if success, *nexthdr is updated by type/protocol of this header.
  76  *
  77  * NOTES: - it may return pointer pointing beyond end of packet,
  78  *          if the last recognized header is truncated in the middle.
  79  *        - if packet is truncated, so that all parsed headers are skipped,
  80  *          it returns -1.
  81  *        - if packet is fragmented, return pointer of the fragment header.
  82  *        - ESP is unparsable for now and considered like
  83  *          normal payload protocol.
  84  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  85  */
  86
  87 static int nf_ct_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
  88                                   u8 *nexthdrp, int len)
  89 {
  90         u8 nexthdr = *nexthdrp;
  91
  92         while (ipv6_ext_hdr(nexthdr)) {
  93                 struct ipv6_opt_hdr hdr;
  94                 int hdrlen;
  95
  96                 if (len < (int)sizeof(struct ipv6_opt_hdr))
  97                         return -1;
  98                 if (nexthdr == NEXTHDR_NONE)
  99                         break;
 100                 if (nexthdr == NEXTHDR_FRAGMENT)
 101                         break;
 102                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 103                         BUG();
 104                 if (nexthdr == NEXTHDR_AUTH)
 105                         hdrlen = (hdr.hdrlen+2)<<2;
 106                 else
 107                         hdrlen = ipv6_optlen(&hdr);
 108
 109                 nexthdr = hdr.nexthdr;
 110                 len -= hdrlen;
 111                 start += hdrlen;
 112         }
 113
 114         *nexthdrp = nexthdr;
 115         return start;
 116 }
 117
 118 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
 119                             unsigned int *dataoff, u_int8_t *protonum)
 120 {
 121         unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
 122         unsigned char pnum;
 123         int protoff;
 124
 125         if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
 126                           &pnum, sizeof(pnum)) != 0) {
 127                 pr_debug("ip6_conntrack_core: can't get nexthdr\n");
 128                 return -NF_ACCEPT;
 129         }
 130         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff);
 131         /*
 132          * (protoff == skb->len) mean that the packet doesn't have no data
 133          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 134          */
 135         if ((protoff < 0) || (protoff > skb->len)) {
 136                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
 137                 return -NF_ACCEPT;
 138         }
 139
 140         *dataoff = protoff;
 141         *protonum = pnum;
 142         return NF_ACCEPT;
 143 }
 144
 145 static unsigned int ipv6_confirm(unsigned int hooknum,
 146                                  struct sk_buff *skb,
 147                                  const struct net_device *in,
 148                                  const struct net_device *out,
 149                                  int (*okfn)(struct sk_buff *))
 150 {
 151         struct nf_conn *ct;
 152         const struct nf_conn_help *help;
 153         const struct nf_conntrack_helper *helper;
 154         enum ip_conntrack_info ctinfo;
 155         unsigned int ret, protoff;
 156         unsigned int extoff = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;
 157         unsigned char pnum = ipv6_hdr(skb)->nexthdr;
 158
 159
 160         /* This is where we call the helper: as the packet goes out. */
 161         ct = nf_ct_get(skb, &ctinfo);
 162         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 163                 goto out;
 164
 165         help = nfct_help(ct);
 166         if (!help)
 167                 goto out;
 168         /* rcu_read_lock()ed by nf_hook_slow */
 169         helper = rcu_dereference(help->helper);
 170         if (!helper)
 171                 goto out;
 172
 173         protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum,
 174                                          skb->len - extoff);
 175         if (protoff > skb->len || pnum == NEXTHDR_FRAGMENT) {
 176                 pr_debug("proto header not found\n");
 177                 return NF_ACCEPT;
 178         }
 179
 180         ret = helper->help(skb, protoff, ct, ctinfo);
 181         if (ret != NF_ACCEPT) {
 182                 nf_log_packet(NFPROTO_IPV6, hooknum, skb, in, out, NULL,
 183                               "nf_ct_%s: dropping packet", helper->name);
 184                 return ret;
 185         }
 186 out:
 187         /* We've seen it coming out the other side: confirm it */
 188         return nf_conntrack_confirm(skb);
 189 }
 190
 191 static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
 192                                                 struct sk_buff *skb)
 193 {
 194 #ifdef CONFIG_BRIDGE_NETFILTER
 195         if (skb->nf_bridge &&
 196             skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
 197                 return IP6_DEFRAG_CONNTRACK_BRIDGE_IN;
 198 #endif
 199         if (hooknum == NF_INET_PRE_ROUTING)
 200                 return IP6_DEFRAG_CONNTRACK_IN;
 201         else
 202                 return IP6_DEFRAG_CONNTRACK_OUT;
 203
 204 }
 205
 206 static unsigned int ipv6_defrag(unsigned int hooknum,
 207                                 struct sk_buff *skb,
 208                                 const struct net_device *in,
 209                                 const struct net_device *out,
 210                                 int (*okfn)(struct sk_buff *))
 211 {
 212         struct sk_buff *reasm;
 213
 214         /* Previously seen (loopback)?  */
 215         if (skb->nfct)
 216                 return NF_ACCEPT;
 217
 218         reasm = nf_ct_frag6_gather(skb, nf_ct6_defrag_user(hooknum, skb));
 219         /* queued */
 220         if (reasm == NULL)
 221                 return NF_STOLEN;
 222
 223         /* error occured or not fragmented */
 224         if (reasm == skb)
 225                 return NF_ACCEPT;
 226
 227         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 228                            (struct net_device *)out, okfn);
 229
 230         return NF_STOLEN;
 231 }
 232
 233 static unsigned int __ipv6_conntrack_in(struct net *net,
 234                                         unsigned int hooknum,
 235                                         struct sk_buff *skb,
 236                                         int (*okfn)(struct sk_buff *))
 237 {
 238         struct sk_buff *reasm = skb->nfct_reasm;
 239
 240         /* This packet is fragmented and has reassembled packet. */
 241         if (reasm) {
 242                 /* Reassembled packet isn't parsed yet ? */
 243                 if (!reasm->nfct) {
 244                         unsigned int ret;
 245
 246                         ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
 247                         if (ret != NF_ACCEPT)
 248                                 return ret;
 249                 }
 250                 nf_conntrack_get(reasm->nfct);
 251                 skb->nfct = reasm->nfct;
 252                 skb->nfctinfo = reasm->nfctinfo;
 253                 return NF_ACCEPT;
 254         }
 255
 256         return nf_conntrack_in(net, PF_INET6, hooknum, skb);
 257 }
 258
 259 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 260                                       struct sk_buff *skb,
 261                                       const struct net_device *in,
 262                                       const struct net_device *out,
 263                                       int (*okfn)(struct sk_buff *))
 264 {
 265         return __ipv6_conntrack_in(dev_net(in), hooknum, skb, okfn);
 266 }
 267
 268 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 269                                          struct sk_buff *skb,
 270                                          const struct net_device *in,
 271                                          const struct net_device *out,
 272                                          int (*okfn)(struct sk_buff *))
 273 {
 274         /* root is playing with raw sockets. */
 275         if (skb->len < sizeof(struct ipv6hdr)) {
 276                 if (net_ratelimit())
 277                         printk("ipv6_conntrack_local: packet too short\n");
 278                 return NF_ACCEPT;
 279         }
 280         return __ipv6_conntrack_in(dev_net(out), hooknum, skb, okfn);
 281 }
 282
 283 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 284         {
 285                 .hook           = ipv6_defrag,
 286                 .owner          = THIS_MODULE,
 287                 .pf             = NFPROTO_IPV6,
 288                 .hooknum        = NF_INET_PRE_ROUTING,
 289                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 290         },
 291         {
 292                 .hook           = ipv6_conntrack_in,
 293                 .owner          = THIS_MODULE,
 294                 .pf             = NFPROTO_IPV6,
 295                 .hooknum        = NF_INET_PRE_ROUTING,
 296                 .priority       = NF_IP6_PRI_CONNTRACK,
 297         },
 298         {
 299                 .hook           = ipv6_conntrack_local,
 300                 .owner          = THIS_MODULE,
 301                 .pf             = NFPROTO_IPV6,
 302                 .hooknum        = NF_INET_LOCAL_OUT,
 303                 .priority       = NF_IP6_PRI_CONNTRACK,
 304         },
 305         {
 306                 .hook           = ipv6_defrag,
 307                 .owner          = THIS_MODULE,
 308                 .pf             = NFPROTO_IPV6,
 309                 .hooknum        = NF_INET_LOCAL_OUT,
 310                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 311         },
 312         {
 313                 .hook           = ipv6_confirm,
 314                 .owner          = THIS_MODULE,
 315                 .pf             = NFPROTO_IPV6,
 316                 .hooknum        = NF_INET_POST_ROUTING,
 317                 .priority       = NF_IP6_PRI_LAST,
 318         },
 319         {
 320                 .hook           = ipv6_confirm,
 321                 .owner          = THIS_MODULE,
 322                 .pf             = NFPROTO_IPV6,
 323                 .hooknum        = NF_INET_LOCAL_IN,
 324                 .priority       = NF_IP6_PRI_LAST-1,
 325         },
 326 };
 327
 328 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 329
 330 #include <linux/netfilter/nfnetlink.h>
 331 #include <linux/netfilter/nfnetlink_conntrack.h>
 332
 333 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 334                                 const struct nf_conntrack_tuple *tuple)
 335 {
 336         NLA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 337                 &tuple->src.u3.ip6);
 338         NLA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 339                 &tuple->dst.u3.ip6);
 340         return 0;
 341
 342 nla_put_failure:
 343         return -1;
 344 }
 345
 346 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 347         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 348         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 349 };
 350
 351 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 352                                 struct nf_conntrack_tuple *t)
 353 {
 354         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 355                 return -EINVAL;
 356
 357         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 358                sizeof(u_int32_t) * 4);
 359         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 360                sizeof(u_int32_t) * 4);
 361
 362         return 0;
 363 }
 364
 365 static int ipv6_nlattr_tuple_size(void)
 366 {
 367         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 368 }
 369 #endif
 370
 371 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 372         .l3proto                = PF_INET6,
 373         .name                   = "ipv6",
 374         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 375         .invert_tuple           = ipv6_invert_tuple,
 376         .print_tuple            = ipv6_print_tuple,
 377         .get_l4proto            = ipv6_get_l4proto,
 378 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 379         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 380         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 381         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 382         .nla_policy             = ipv6_nla_policy,
 383 #endif
 384 #ifdef CONFIG_SYSCTL
 385         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 386         .ctl_table              = nf_ct_ipv6_sysctl_table,
 387 #endif
 388         .me                     = THIS_MODULE,
 389 };
 390
 391 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 392 MODULE_LICENSE("GPL");
 393 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 394
 395 static int __init nf_conntrack_l3proto_ipv6_init(void)
 396 {
 397         int ret = 0;
 398
 399         need_conntrack();
 400
 401         ret = nf_ct_frag6_init();
 402         if (ret < 0) {
 403                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 404                 return ret;
 405         }
 406         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 407         if (ret < 0) {
 408                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 409                 goto cleanup_frag6;
 410         }
 411
 412         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 413         if (ret < 0) {
 414                 printk("nf_conntrack_ipv6: can't register udp.\n");
 415                 goto cleanup_tcp;
 416         }
 417
 418         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 419         if (ret < 0) {
 420                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 421                 goto cleanup_udp;
 422         }
 423
 424         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 425         if (ret < 0) {
 426                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 427                 goto cleanup_icmpv6;
 428         }
 429
 430         ret = nf_register_hooks(ipv6_conntrack_ops,
 431                                 ARRAY_SIZE(ipv6_conntrack_ops));
 432         if (ret < 0) {
 433                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 434                        "hook.\n");
 435                 goto cleanup_ipv6;
 436         }
 437         return ret;
 438
 439  cleanup_ipv6:
 440         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 441  cleanup_icmpv6:
 442         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 443  cleanup_udp:
 444         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 445  cleanup_tcp:
 446         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 447  cleanup_frag6:
 448         nf_ct_frag6_cleanup();
 449         return ret;
 450 }
 451
 452 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 453 {
 454         synchronize_net();
 455         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 456         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 457         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 458         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 459         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 460         nf_ct_frag6_cleanup();
 461 }
 462
 463 module_init(nf_conntrack_l3proto_ipv6_init);
 464 module_exit(nf_conntrack_l3proto_ipv6_fini);