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  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  12  *      - support Layer 3 protocol independent connection tracking.
  13  *        Based on the original ip_conntrack code which had the following
  14  *        copyright information:
  15  *              (C) 1999-2001 Paul `Rusty' Russell
  16  *              (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
  17  *
  18  * 23 Mar 2004: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  19  *      - add get_features() to support various size of conntrack
  20  *        structures.
  21  */
  22
  23 #include <linux/types.h>
  24 #include <linux/ipv6.h>
  25 #include <linux/in6.h>
  26 #include <linux/netfilter.h>
  27 #include <linux/module.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/icmp.h>
  30 #include <linux/sysctl.h>
  31 #include <net/ipv6.h>
  32
  33 #include <linux/netfilter_ipv6.h>
  34 #include <net/netfilter/nf_conntrack.h>
  35 #include <net/netfilter/nf_conntrack_helper.h>
  36 #include <net/netfilter/nf_conntrack_l4proto.h>
  37 #include <net/netfilter/nf_conntrack_l3proto.h>
  38 #include <net/netfilter/nf_conntrack_core.h>
  39
  40 #if 0
  41 #define DEBUGP printk
  42 #else
  43 #define DEBUGP(format, args...)
  44 #endif
  45
  46 static int ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  47                              struct nf_conntrack_tuple *tuple)
  48 {
  49         u_int32_t _addrs[8], *ap;
  50
  51         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  52                                 sizeof(_addrs), _addrs);
  53         if (ap == NULL)
  54                 return 0;
  55
  56         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  57         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  58
  59         return 1;
  60 }
  61
  62 static int ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  63                              const struct nf_conntrack_tuple *orig)
  64 {
  65         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  66         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  67
  68         return 1;
  69 }
  70
  71 static int ipv6_print_tuple(struct seq_file *s,
  72                             const struct nf_conntrack_tuple *tuple)
  73 {
  74         return seq_printf(s, "src=" NIP6_FMT " dst=" NIP6_FMT " ",
  75                           NIP6(*((struct in6_addr *)tuple->src.u3.ip6)),
  76                           NIP6(*((struct in6_addr *)tuple->dst.u3.ip6)));
  77 }
  78
  79 static int ipv6_print_conntrack(struct seq_file *s,
  80                                 const struct nf_conn *conntrack)
  81 {
  82         return 0;
  83 }
  84
  85 /*
  86  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  87  *
  88  * This function parses (probably truncated) exthdr set "hdr"
  89  * of length "len". "nexthdrp" initially points to some place,
  90  * where type of the first header can be found.
  91  *
  92  * It skips all well-known exthdrs, and returns pointer to the start
  93  * of unparsable area i.e. the first header with unknown type.
  94  * if success, *nexthdr is updated by type/protocol of this header.
  95  *
  96  * NOTES: - it may return pointer pointing beyond end of packet,
  97  *          if the last recognized header is truncated in the middle.
  98  *        - if packet is truncated, so that all parsed headers are skipped,
  99  *          it returns -1.
 100  *        - if packet is fragmented, return pointer of the fragment header.
 101  *        - ESP is unparsable for now and considered like
 102  *          normal payload protocol.
 103  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
 104  */
 105
 106 int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
 107                            int len)
 108 {
 109         u8 nexthdr = *nexthdrp;
 110
 111         while (ipv6_ext_hdr(nexthdr)) {
 112                 struct ipv6_opt_hdr hdr;
 113                 int hdrlen;
 114
 115                 if (len < (int)sizeof(struct ipv6_opt_hdr))
 116                         return -1;
 117                 if (nexthdr == NEXTHDR_NONE)
 118                         break;
 119                 if (nexthdr == NEXTHDR_FRAGMENT)
 120                         break;
 121                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 122                         BUG();
 123                 if (nexthdr == NEXTHDR_AUTH)
 124                         hdrlen = (hdr.hdrlen+2)<<2;
 125                 else
 126                         hdrlen = ipv6_optlen(&hdr);
 127
 128                 nexthdr = hdr.nexthdr;
 129                 len -= hdrlen;
 130                 start += hdrlen;
 131         }
 132
 133         *nexthdrp = nexthdr;
 134         return start;
 135 }
 136
 137 static int
 138 ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
 139              u_int8_t *protonum)
 140 {
 141         unsigned int extoff;
 142         unsigned char pnum;
 143         int protoff;
 144
 145         extoff = (u8*)((*pskb)->nh.ipv6h + 1) - (*pskb)->data;
 146         pnum = (*pskb)->nh.ipv6h->nexthdr;
 147
 148         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 149                                          (*pskb)->len - extoff);
 150
 151         /*
 152          * (protoff == (*pskb)->len) mean that the packet doesn't have no data
 153          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 154          */
 155         if ((protoff < 0) || (protoff > (*pskb)->len)) {
 156                 DEBUGP("ip6_conntrack_core: can't find proto in pkt\n");
 157                 NF_CT_STAT_INC(error);
 158                 NF_CT_STAT_INC(invalid);
 159                 return -NF_ACCEPT;
 160         }
 161
 162         *dataoff = protoff;
 163         *protonum = pnum;
 164         return NF_ACCEPT;
 165 }
 166
 167 static u_int32_t ipv6_get_features(const struct nf_conntrack_tuple *tuple)
 168 {
 169         return NF_CT_F_BASIC;
 170 }
 171
 172 static unsigned int ipv6_confirm(unsigned int hooknum,
 173                                  struct sk_buff **pskb,
 174                                  const struct net_device *in,
 175                                  const struct net_device *out,
 176                                  int (*okfn)(struct sk_buff *))
 177 {
 178         struct nf_conn *ct;
 179         struct nf_conn_help *help;
 180         enum ip_conntrack_info ctinfo;
 181         unsigned int ret, protoff;
 182         unsigned int extoff = (u8*)((*pskb)->nh.ipv6h + 1)
 183                               - (*pskb)->data;
 184         unsigned char pnum = (*pskb)->nh.ipv6h->nexthdr;
 185
 186
 187         /* This is where we call the helper: as the packet goes out. */
 188         ct = nf_ct_get(*pskb, &ctinfo);
 189         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 190                 goto out;
 191
 192         help = nfct_help(ct);
 193         if (!help || !help->helper)
 194                 goto out;
 195
 196         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 197                                          (*pskb)->len - extoff);
 198         if (protoff < 0 || protoff > (*pskb)->len ||
 199             pnum == NEXTHDR_FRAGMENT) {
 200                 DEBUGP("proto header not found\n");
 201                 return NF_ACCEPT;
 202         }
 203
 204         ret = help->helper->help(pskb, protoff, ct, ctinfo);
 205         if (ret != NF_ACCEPT)
 206                 return ret;
 207 out:
 208         /* We've seen it coming out the other side: confirm it */
 209         return nf_conntrack_confirm(pskb);
 210 }
 211
 212 static unsigned int ipv6_defrag(unsigned int hooknum,
 213                                 struct sk_buff **pskb,
 214                                 const struct net_device *in,
 215                                 const struct net_device *out,
 216                                 int (*okfn)(struct sk_buff *))
 217 {
 218         struct sk_buff *reasm;
 219
 220         /* Previously seen (loopback)?  */
 221         if ((*pskb)->nfct)
 222                 return NF_ACCEPT;
 223
 224         reasm = nf_ct_frag6_gather(*pskb);
 225
 226         /* queued */
 227         if (reasm == NULL)
 228                 return NF_STOLEN;
 229
 230         /* error occured or not fragmented */
 231         if (reasm == *pskb)
 232                 return NF_ACCEPT;
 233
 234         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 235                            (struct net_device *)out, okfn);
 236
 237         return NF_STOLEN;
 238 }
 239
 240 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 241                                       struct sk_buff **pskb,
 242                                       const struct net_device *in,
 243                                       const struct net_device *out,
 244                                       int (*okfn)(struct sk_buff *))
 245 {
 246         struct sk_buff *reasm = (*pskb)->nfct_reasm;
 247
 248         /* This packet is fragmented and has reassembled packet. */
 249         if (reasm) {
 250                 /* Reassembled packet isn't parsed yet ? */
 251                 if (!reasm->nfct) {
 252                         unsigned int ret;
 253
 254                         ret = nf_conntrack_in(PF_INET6, hooknum, &reasm);
 255                         if (ret != NF_ACCEPT)
 256                                 return ret;
 257                 }
 258                 nf_conntrack_get(reasm->nfct);
 259                 (*pskb)->nfct = reasm->nfct;
 260                 return NF_ACCEPT;
 261         }
 262
 263         return nf_conntrack_in(PF_INET6, hooknum, pskb);
 264 }
 265
 266 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 267                                          struct sk_buff **pskb,
 268                                          const struct net_device *in,
 269                                          const struct net_device *out,
 270                                          int (*okfn)(struct sk_buff *))
 271 {
 272         /* root is playing with raw sockets. */
 273         if ((*pskb)->len < sizeof(struct ipv6hdr)) {
 274                 if (net_ratelimit())
 275                         printk("ipv6_conntrack_local: packet too short\n");
 276                 return NF_ACCEPT;
 277         }
 278         return ipv6_conntrack_in(hooknum, pskb, in, out, okfn);
 279 }
 280
 281 static struct nf_hook_ops ipv6_conntrack_ops[] = {
 282         {
 283                 .hook           = ipv6_defrag,
 284                 .owner          = THIS_MODULE,
 285                 .pf             = PF_INET6,
 286                 .hooknum        = NF_IP6_PRE_ROUTING,
 287                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 288         },
 289         {
 290                 .hook           = ipv6_conntrack_in,
 291                 .owner          = THIS_MODULE,
 292                 .pf             = PF_INET6,
 293                 .hooknum        = NF_IP6_PRE_ROUTING,
 294                 .priority       = NF_IP6_PRI_CONNTRACK,
 295         },
 296         {
 297                 .hook           = ipv6_conntrack_local,
 298                 .owner          = THIS_MODULE,
 299                 .pf             = PF_INET6,
 300                 .hooknum        = NF_IP6_LOCAL_OUT,
 301                 .priority       = NF_IP6_PRI_CONNTRACK,
 302         },
 303         {
 304                 .hook           = ipv6_defrag,
 305                 .owner          = THIS_MODULE,
 306                 .pf             = PF_INET6,
 307                 .hooknum        = NF_IP6_LOCAL_OUT,
 308                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 309         },
 310         {
 311                 .hook           = ipv6_confirm,
 312                 .owner          = THIS_MODULE,
 313                 .pf             = PF_INET6,
 314                 .hooknum        = NF_IP6_POST_ROUTING,
 315                 .priority       = NF_IP6_PRI_LAST,
 316         },
 317         {
 318                 .hook           = ipv6_confirm,
 319                 .owner          = THIS_MODULE,
 320                 .pf             = PF_INET6,
 321                 .hooknum        = NF_IP6_LOCAL_IN,
 322                 .priority       = NF_IP6_PRI_LAST-1,
 323         },
 324 };
 325
 326 #ifdef CONFIG_SYSCTL
 327 static ctl_table nf_ct_ipv6_sysctl_table[] = {
 328         {
 329                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_TIMEOUT,
 330                 .procname       = "nf_conntrack_frag6_timeout",
 331                 .data           = &nf_ct_frag6_timeout,
 332                 .maxlen         = sizeof(unsigned int),
 333                 .mode           = 0644,
 334                 .proc_handler   = &proc_dointvec_jiffies,
 335         },
 336         {
 337                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
 338                 .procname       = "nf_conntrack_frag6_low_thresh",
 339                 .data           = &nf_ct_frag6_low_thresh,
 340                 .maxlen         = sizeof(unsigned int),
 341                 .mode           = 0644,
 342                 .proc_handler   = &proc_dointvec,
 343         },
 344         {
 345                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
 346                 .procname       = "nf_conntrack_frag6_high_thresh",
 347                 .data           = &nf_ct_frag6_high_thresh,
 348                 .maxlen         = sizeof(unsigned int),
 349                 .mode           = 0644,
 350                 .proc_handler   = &proc_dointvec,
 351         },
 352         { .ctl_name = 0 }
 353 };
 354 #endif
 355
 356 #if defined(CONFIG_NF_CT_NETLINK) || \
 357     defined(CONFIG_NF_CT_NETLINK_MODULE)
 358
 359 #include <linux/netfilter/nfnetlink.h>
 360 #include <linux/netfilter/nfnetlink_conntrack.h>
 361
 362 static int ipv6_tuple_to_nfattr(struct sk_buff *skb,
 363                                 const struct nf_conntrack_tuple *tuple)
 364 {
 365         NFA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 366                 &tuple->src.u3.ip6);
 367         NFA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 368                 &tuple->dst.u3.ip6);
 369         return 0;
 370
 371 nfattr_failure:
 372         return -1;
 373 }
 374
 375 static const size_t cta_min_ip[CTA_IP_MAX] = {
 376         [CTA_IP_V6_SRC-1]       = sizeof(u_int32_t)*4,
 377         [CTA_IP_V6_DST-1]       = sizeof(u_int32_t)*4,
 378 };
 379
 380 static int ipv6_nfattr_to_tuple(struct nfattr *tb[],
 381                                 struct nf_conntrack_tuple *t)
 382 {
 383         if (!tb[CTA_IP_V6_SRC-1] || !tb[CTA_IP_V6_DST-1])
 384                 return -EINVAL;
 385
 386         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 387                 return -EINVAL;
 388
 389         memcpy(&t->src.u3.ip6, NFA_DATA(tb[CTA_IP_V6_SRC-1]),
 390                sizeof(u_int32_t) * 4);
 391         memcpy(&t->dst.u3.ip6, NFA_DATA(tb[CTA_IP_V6_DST-1]),
 392                sizeof(u_int32_t) * 4);
 393
 394         return 0;
 395 }
 396 #endif
 397
 398 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
 399         .l3proto                = PF_INET6,
 400         .name                   = "ipv6",
 401         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 402         .invert_tuple           = ipv6_invert_tuple,
 403         .print_tuple            = ipv6_print_tuple,
 404         .print_conntrack        = ipv6_print_conntrack,
 405         .prepare                = ipv6_prepare,
 406 #if defined(CONFIG_NF_CT_NETLINK) || \
 407     defined(CONFIG_NF_CT_NETLINK_MODULE)
 408         .tuple_to_nfattr        = ipv6_tuple_to_nfattr,
 409         .nfattr_to_tuple        = ipv6_nfattr_to_tuple,
 410 #endif
 411 #ifdef CONFIG_SYSCTL
 412         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 413         .ctl_table              = nf_ct_ipv6_sysctl_table,
 414 #endif
 415         .get_features           = ipv6_get_features,
 416         .me                     = THIS_MODULE,
 417 };
 418
 419 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 420 MODULE_LICENSE("GPL");
 421 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 422
 423 static int __init nf_conntrack_l3proto_ipv6_init(void)
 424 {
 425         int ret = 0;
 426
 427         need_conntrack();
 428
 429         ret = nf_ct_frag6_init();
 430         if (ret < 0) {
 431                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 432                 return ret;
 433         }
 434         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 435         if (ret < 0) {
 436                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 437                 goto cleanup_frag6;
 438         }
 439
 440         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 441         if (ret < 0) {
 442                 printk("nf_conntrack_ipv6: can't register udp.\n");
 443                 goto cleanup_tcp;
 444         }
 445
 446         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 447         if (ret < 0) {
 448                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 449                 goto cleanup_udp;
 450         }
 451
 452         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 453         if (ret < 0) {
 454                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 455                 goto cleanup_icmpv6;
 456         }
 457
 458         ret = nf_register_hooks(ipv6_conntrack_ops,
 459                                 ARRAY_SIZE(ipv6_conntrack_ops));
 460         if (ret < 0) {
 461                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 462                        "hook.\n");
 463                 goto cleanup_ipv6;
 464         }
 465         return ret;
 466
 467  cleanup_ipv6:
 468         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 469  cleanup_icmpv6:
 470         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 471  cleanup_udp:
 472         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 473  cleanup_tcp:
 474         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 475  cleanup_frag6:
 476         nf_ct_frag6_cleanup();
 477         return ret;
 478 }
 479
 480 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 481 {
 482         synchronize_net();
 483         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 484         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 485         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 486         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 487         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 488         nf_ct_frag6_cleanup();
 489 }
 490
 491 module_init(nf_conntrack_l3proto_ipv6_init);
 492 module_exit(nf_conntrack_l3proto_ipv6_fini);