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