net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c

   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 enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
 191                                                 struct sk_buff *skb)
 192 {
 193         if (hooknum == NF_INET_PRE_ROUTING)
 194                 return IP6_DEFRAG_CONNTRACK_IN;
 195         else
 196                 return IP6_DEFRAG_CONNTRACK_OUT;
 197
 198 }
 199
 200 static unsigned int ipv6_defrag(unsigned int hooknum,
 201                                 struct sk_buff *skb,
 202                                 const struct net_device *in,
 203                                 const struct net_device *out,
 204                                 int (*okfn)(struct sk_buff *))
 205 {
 206         struct sk_buff *reasm;
 207
 208         /* Previously seen (loopback)?  */
 209         if (skb->nfct)
 210                 return NF_ACCEPT;
 211
 212         reasm = nf_ct_frag6_gather(skb, nf_ct6_defrag_user(hooknum, skb));
 213         /* queued */
 214         if (reasm == NULL)
 215                 return NF_STOLEN;
 216
 217         /* error occured or not fragmented */
 218         if (reasm == skb)
 219                 return NF_ACCEPT;
 220
 221         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 222                            (struct net_device *)out, okfn);
 223
 224         return NF_STOLEN;
 225 }
 226
 227 static unsigned int __ipv6_conntrack_in(struct net *net,
 228                                         unsigned int hooknum,
 229                                         struct sk_buff *skb,
 230                                         int (*okfn)(struct sk_buff *))
 231 {
 232         struct sk_buff *reasm = skb->nfct_reasm;
 233
 234         /* This packet is fragmented and has reassembled packet. */
 235         if (reasm) {
 236                 /* Reassembled packet isn't parsed yet ? */
 237                 if (!reasm->nfct) {
 238                         unsigned int ret;
 239
 240                         ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
 241                         if (ret != NF_ACCEPT)
 242                                 return ret;
 243                 }
 244                 nf_conntrack_get(reasm->nfct);
 245                 skb->nfct = reasm->nfct;
 246                 skb->nfctinfo = reasm->nfctinfo;
 247                 return NF_ACCEPT;
 248         }
 249
 250         return nf_conntrack_in(net, PF_INET6, hooknum, skb);
 251 }
 252
 253 static unsigned int ipv6_conntrack_in(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         return __ipv6_conntrack_in(dev_net(in), hooknum, skb, okfn);
 260 }
 261
 262 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 263                                          struct sk_buff *skb,
 264                                          const struct net_device *in,
 265                                          const struct net_device *out,
 266                                          int (*okfn)(struct sk_buff *))
 267 {
 268         /* root is playing with raw sockets. */
 269         if (skb->len < sizeof(struct ipv6hdr)) {
 270                 if (net_ratelimit())
 271                         printk("ipv6_conntrack_local: packet too short\n");
 272                 return NF_ACCEPT;
 273         }
 274         return __ipv6_conntrack_in(dev_net(out), hooknum, skb, okfn);
 275 }
 276
 277 static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
 278         {
 279                 .hook           = ipv6_defrag,
 280                 .owner          = THIS_MODULE,
 281                 .pf             = NFPROTO_IPV6,
 282                 .hooknum        = NF_INET_PRE_ROUTING,
 283                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 284         },
 285         {
 286                 .hook           = ipv6_conntrack_in,
 287                 .owner          = THIS_MODULE,
 288                 .pf             = NFPROTO_IPV6,
 289                 .hooknum        = NF_INET_PRE_ROUTING,
 290                 .priority       = NF_IP6_PRI_CONNTRACK,
 291         },
 292         {
 293                 .hook           = ipv6_conntrack_local,
 294                 .owner          = THIS_MODULE,
 295                 .pf             = NFPROTO_IPV6,
 296                 .hooknum        = NF_INET_LOCAL_OUT,
 297                 .priority       = NF_IP6_PRI_CONNTRACK,
 298         },
 299         {
 300                 .hook           = ipv6_defrag,
 301                 .owner          = THIS_MODULE,
 302                 .pf             = NFPROTO_IPV6,
 303                 .hooknum        = NF_INET_LOCAL_OUT,
 304                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 305         },
 306         {
 307                 .hook           = ipv6_confirm,
 308                 .owner          = THIS_MODULE,
 309                 .pf             = NFPROTO_IPV6,
 310                 .hooknum        = NF_INET_POST_ROUTING,
 311                 .priority       = NF_IP6_PRI_LAST,
 312         },
 313         {
 314                 .hook           = ipv6_confirm,
 315                 .owner          = THIS_MODULE,
 316                 .pf             = NFPROTO_IPV6,
 317                 .hooknum        = NF_INET_LOCAL_IN,
 318                 .priority       = NF_IP6_PRI_LAST-1,
 319         },
 320 };
 321
 322 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 323
 324 #include <linux/netfilter/nfnetlink.h>
 325 #include <linux/netfilter/nfnetlink_conntrack.h>
 326
 327 static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
 328                                 const struct nf_conntrack_tuple *tuple)
 329 {
 330         NLA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 331                 &tuple->src.u3.ip6);
 332         NLA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 333                 &tuple->dst.u3.ip6);
 334         return 0;
 335
 336 nla_put_failure:
 337         return -1;
 338 }
 339
 340 static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
 341         [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
 342         [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
 343 };
 344
 345 static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 346                                 struct nf_conntrack_tuple *t)
 347 {
 348         if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
 349                 return -EINVAL;
 350
 351         memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
 352                sizeof(u_int32_t) * 4);
 353         memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
 354                sizeof(u_int32_t) * 4);
 355
 356         return 0;
 357 }
 358
 359 static int ipv6_nlattr_tuple_size(void)
 360 {
 361         return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
 362 }
 363 #endif
 364
 365 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 366         .l3proto                = PF_INET6,
 367         .name                   = "ipv6",
 368         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 369         .invert_tuple           = ipv6_invert_tuple,
 370         .print_tuple            = ipv6_print_tuple,
 371         .get_l4proto            = ipv6_get_l4proto,
 372 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 373         .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
 374         .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
 375         .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
 376         .nla_policy             = ipv6_nla_policy,
 377 #endif
 378 #ifdef CONFIG_SYSCTL
 379         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 380         .ctl_table              = nf_ct_ipv6_sysctl_table,
 381 #endif
 382         .me                     = THIS_MODULE,
 383 };
 384
 385 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 386 MODULE_LICENSE("GPL");
 387 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 388
 389 static int __init nf_conntrack_l3proto_ipv6_init(void)
 390 {
 391         int ret = 0;
 392
 393         need_conntrack();
 394
 395         ret = nf_ct_frag6_init();
 396         if (ret < 0) {
 397                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 398                 return ret;
 399         }
 400         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 401         if (ret < 0) {
 402                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 403                 goto cleanup_frag6;
 404         }
 405
 406         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 407         if (ret < 0) {
 408                 printk("nf_conntrack_ipv6: can't register udp.\n");
 409                 goto cleanup_tcp;
 410         }
 411
 412         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 413         if (ret < 0) {
 414                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 415                 goto cleanup_udp;
 416         }
 417
 418         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 419         if (ret < 0) {
 420                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 421                 goto cleanup_icmpv6;
 422         }
 423
 424         ret = nf_register_hooks(ipv6_conntrack_ops,
 425                                 ARRAY_SIZE(ipv6_conntrack_ops));
 426         if (ret < 0) {
 427                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 428                        "hook.\n");
 429                 goto cleanup_ipv6;
 430         }
 431         return ret;
 432
 433  cleanup_ipv6:
 434         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 435  cleanup_icmpv6:
 436         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 437  cleanup_udp:
 438         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 439  cleanup_tcp:
 440         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 441  cleanup_frag6:
 442         nf_ct_frag6_cleanup();
 443         return ret;
 444 }
 445
 446 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 447 {
 448         synchronize_net();
 449         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 450         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 451         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 452         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 453         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 454         nf_ct_frag6_cleanup();
 455 }
 456
 457 module_init(nf_conntrack_l3proto_ipv6_init);
 458 module_exit(nf_conntrack_l3proto_ipv6_fini);