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/config.h>
  24 #include <linux/types.h>
  25 #include <linux/ipv6.h>
  26 #include <linux/in6.h>
  27 #include <linux/netfilter.h>
  28 #include <linux/module.h>
  29 #include <linux/skbuff.h>
  30 #include <linux/icmp.h>
  31 #include <linux/sysctl.h>
  32 #include <net/ipv6.h>
  33
  34 #include <linux/netfilter_ipv6.h>
  35 #include <net/netfilter/nf_conntrack.h>
  36 #include <net/netfilter/nf_conntrack_helper.h>
  37 #include <net/netfilter/nf_conntrack_protocol.h>
  38 #include <net/netfilter/nf_conntrack_l3proto.h>
  39 #include <net/netfilter/nf_conntrack_core.h>
  40
  41 #if 0
  42 #define DEBUGP printk
  43 #else
  44 #define DEBUGP(format, args...)
  45 #endif
  46
  47 DECLARE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat);
  48
  49 static int ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  50                              struct nf_conntrack_tuple *tuple)
  51 {
  52         u_int32_t _addrs[8], *ap;
  53
  54         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  55                                 sizeof(_addrs), _addrs);
  56         if (ap == NULL)
  57                 return 0;
  58
  59         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  60         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  61
  62         return 1;
  63 }
  64
  65 static int ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  66                              const struct nf_conntrack_tuple *orig)
  67 {
  68         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  69         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  70
  71         return 1;
  72 }
  73
  74 static int ipv6_print_tuple(struct seq_file *s,
  75                             const struct nf_conntrack_tuple *tuple)
  76 {
  77         return seq_printf(s, "src=%x:%x:%x:%x:%x:%x:%x:%x dst=%x:%x:%x:%x:%x:%x:%x:%x ",
  78                           NIP6(*((struct in6_addr *)tuple->src.u3.ip6)),
  79                           NIP6(*((struct in6_addr *)tuple->dst.u3.ip6)));
  80 }
  81
  82 static int ipv6_print_conntrack(struct seq_file *s,
  83                                 const struct nf_conn *conntrack)
  84 {
  85         return 0;
  86 }
  87
  88 /*
  89  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  90  *
  91  * This function parses (probably truncated) exthdr set "hdr"
  92  * of length "len". "nexthdrp" initially points to some place,
  93  * where type of the first header can be found.
  94  *
  95  * It skips all well-known exthdrs, and returns pointer to the start
  96  * of unparsable area i.e. the first header with unknown type.
  97  * if success, *nexthdr is updated by type/protocol of this header.
  98  *
  99  * NOTES: - it may return pointer pointing beyond end of packet,
 100  *          if the last recognized header is truncated in the middle.
 101  *        - if packet is truncated, so that all parsed headers are skipped,
 102  *          it returns -1.
 103  *        - if packet is fragmented, return pointer of the fragment header.
 104  *        - ESP is unparsable for now and considered like
 105  *          normal payload protocol.
 106  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
 107  */
 108
 109 int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
 110                            int len)
 111 {
 112         u8 nexthdr = *nexthdrp;
 113
 114         while (ipv6_ext_hdr(nexthdr)) {
 115                 struct ipv6_opt_hdr hdr;
 116                 int hdrlen;
 117
 118                 if (len < (int)sizeof(struct ipv6_opt_hdr))
 119                         return -1;
 120                 if (nexthdr == NEXTHDR_NONE)
 121                         break;
 122                 if (nexthdr == NEXTHDR_FRAGMENT)
 123                         break;
 124                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 125                         BUG();
 126                 if (nexthdr == NEXTHDR_AUTH)
 127                         hdrlen = (hdr.hdrlen+2)<<2;
 128                 else
 129                         hdrlen = ipv6_optlen(&hdr);
 130
 131                 nexthdr = hdr.nexthdr;
 132                 len -= hdrlen;
 133                 start += hdrlen;
 134         }
 135
 136         *nexthdrp = nexthdr;
 137         return start;
 138 }
 139
 140 static int
 141 ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
 142              u_int8_t *protonum)
 143 {
 144         unsigned int extoff;
 145         unsigned char pnum;
 146         int protoff;
 147
 148         extoff = (u8*)((*pskb)->nh.ipv6h + 1) - (*pskb)->data;
 149         pnum = (*pskb)->nh.ipv6h->nexthdr;
 150
 151         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 152                                          (*pskb)->len - extoff);
 153
 154         /*
 155          * (protoff == (*pskb)->len) mean that the packet doesn't have no data
 156          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 157          */
 158         if ((protoff < 0) || (protoff > (*pskb)->len)) {
 159                 DEBUGP("ip6_conntrack_core: can't find proto in pkt\n");
 160                 NF_CT_STAT_INC(error);
 161                 NF_CT_STAT_INC(invalid);
 162                 return -NF_ACCEPT;
 163         }
 164
 165         *dataoff = protoff;
 166         *protonum = pnum;
 167         return NF_ACCEPT;
 168 }
 169
 170 static u_int32_t ipv6_get_features(const struct nf_conntrack_tuple *tuple)
 171 {
 172         return NF_CT_F_BASIC;
 173 }
 174
 175 static unsigned int ipv6_confirm(unsigned int hooknum,
 176                                  struct sk_buff **pskb,
 177                                  const struct net_device *in,
 178                                  const struct net_device *out,
 179                                  int (*okfn)(struct sk_buff *))
 180 {
 181         struct nf_conn *ct;
 182         enum ip_conntrack_info ctinfo;
 183
 184         /* This is where we call the helper: as the packet goes out. */
 185         ct = nf_ct_get(*pskb, &ctinfo);
 186         if (ct && ct->helper) {
 187                 unsigned int ret, protoff;
 188                 unsigned int extoff = (u8*)((*pskb)->nh.ipv6h + 1)
 189                                       - (*pskb)->data;
 190                 unsigned char pnum = (*pskb)->nh.ipv6h->nexthdr;
 191
 192                 protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 193                                                  (*pskb)->len - extoff);
 194                 if (protoff < 0 || protoff > (*pskb)->len ||
 195                     pnum == NEXTHDR_FRAGMENT) {
 196                         DEBUGP("proto header not found\n");
 197                         return NF_ACCEPT;
 198                 }
 199
 200                 ret = ct->helper->help(pskb, protoff, ct, ctinfo);
 201                 if (ret != NF_ACCEPT)
 202                         return ret;
 203         }
 204
 205         /* We've seen it coming out the other side: confirm it */
 206
 207         return nf_conntrack_confirm(pskb);
 208 }
 209
 210 extern struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb);
 211 extern void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
 212                                struct net_device *in,
 213                                struct net_device *out,
 214                                int (*okfn)(struct sk_buff *));
 215 static unsigned int ipv6_defrag(unsigned int hooknum,
 216                                 struct sk_buff **pskb,
 217                                 const struct net_device *in,
 218                                 const struct net_device *out,
 219                                 int (*okfn)(struct sk_buff *))
 220 {
 221         struct sk_buff *reasm;
 222
 223         /* Previously seen (loopback)?  */
 224         if ((*pskb)->nfct)
 225                 return NF_ACCEPT;
 226
 227         reasm = nf_ct_frag6_gather(*pskb);
 228
 229         /* queued */
 230         if (reasm == NULL)
 231                 return NF_STOLEN;
 232
 233         /* error occured or not fragmented */
 234         if (reasm == *pskb)
 235                 return NF_ACCEPT;
 236
 237         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 238                            (struct net_device *)out, okfn);
 239
 240         return NF_STOLEN;
 241 }
 242
 243 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 244                                       struct sk_buff **pskb,
 245                                       const struct net_device *in,
 246                                       const struct net_device *out,
 247                                       int (*okfn)(struct sk_buff *))
 248 {
 249         struct sk_buff *reasm = (*pskb)->nfct_reasm;
 250
 251         /* This packet is fragmented and has reassembled packet. */
 252         if (reasm) {
 253                 /* Reassembled packet isn't parsed yet ? */
 254                 if (!reasm->nfct) {
 255                         unsigned int ret;
 256
 257                         ret = nf_conntrack_in(PF_INET6, hooknum, &reasm);
 258                         if (ret != NF_ACCEPT)
 259                                 return ret;
 260                 }
 261                 nf_conntrack_get(reasm->nfct);
 262                 (*pskb)->nfct = reasm->nfct;
 263                 return NF_ACCEPT;
 264         }
 265
 266         return nf_conntrack_in(PF_INET6, hooknum, pskb);
 267 }
 268
 269 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 270                                          struct sk_buff **pskb,
 271                                          const struct net_device *in,
 272                                          const struct net_device *out,
 273                                          int (*okfn)(struct sk_buff *))
 274 {
 275         /* root is playing with raw sockets. */
 276         if ((*pskb)->len < sizeof(struct ipv6hdr)) {
 277                 if (net_ratelimit())
 278                         printk("ipv6_conntrack_local: packet too short\n");
 279                 return NF_ACCEPT;
 280         }
 281         return ipv6_conntrack_in(hooknum, pskb, in, out, okfn);
 282 }
 283
 284 /* Connection tracking may drop packets, but never alters them, so
 285    make it the first hook. */
 286 static struct nf_hook_ops ipv6_conntrack_defrag_ops = {
 287         .hook           = ipv6_defrag,
 288         .owner          = THIS_MODULE,
 289         .pf             = PF_INET6,
 290         .hooknum        = NF_IP6_PRE_ROUTING,
 291         .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 292 };
 293
 294 static struct nf_hook_ops ipv6_conntrack_in_ops = {
 295         .hook           = ipv6_conntrack_in,
 296         .owner          = THIS_MODULE,
 297         .pf             = PF_INET6,
 298         .hooknum        = NF_IP6_PRE_ROUTING,
 299         .priority       = NF_IP6_PRI_CONNTRACK,
 300 };
 301
 302 static struct nf_hook_ops ipv6_conntrack_local_out_ops = {
 303         .hook           = ipv6_conntrack_local,
 304         .owner          = THIS_MODULE,
 305         .pf             = PF_INET6,
 306         .hooknum        = NF_IP6_LOCAL_OUT,
 307         .priority       = NF_IP6_PRI_CONNTRACK,
 308 };
 309
 310 static struct nf_hook_ops ipv6_conntrack_defrag_local_out_ops = {
 311         .hook           = ipv6_defrag,
 312         .owner          = THIS_MODULE,
 313         .pf             = PF_INET6,
 314         .hooknum        = NF_IP6_LOCAL_OUT,
 315         .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 316 };
 317
 318 /* Refragmenter; last chance. */
 319 static struct nf_hook_ops ipv6_conntrack_out_ops = {
 320         .hook           = ipv6_confirm,
 321         .owner          = THIS_MODULE,
 322         .pf             = PF_INET6,
 323         .hooknum        = NF_IP6_POST_ROUTING,
 324         .priority       = NF_IP6_PRI_LAST,
 325 };
 326
 327 static struct nf_hook_ops ipv6_conntrack_local_in_ops = {
 328         .hook           = ipv6_confirm,
 329         .owner          = THIS_MODULE,
 330         .pf             = PF_INET6,
 331         .hooknum        = NF_IP6_LOCAL_IN,
 332         .priority       = NF_IP6_PRI_LAST-1,
 333 };
 334
 335 #ifdef CONFIG_SYSCTL
 336
 337 /* From nf_conntrack_proto_icmpv6.c */
 338 extern unsigned long nf_ct_icmpv6_timeout;
 339
 340 /* From nf_conntrack_frag6.c */
 341 extern unsigned long nf_ct_frag6_timeout;
 342 extern unsigned int nf_ct_frag6_low_thresh;
 343 extern unsigned int nf_ct_frag6_high_thresh;
 344
 345 static struct ctl_table_header *nf_ct_ipv6_sysctl_header;
 346
 347 static ctl_table nf_ct_sysctl_table[] = {
 348         {
 349                 .ctl_name       = NET_NF_CONNTRACK_ICMPV6_TIMEOUT,
 350                 .procname       = "nf_conntrack_icmpv6_timeout",
 351                 .data           = &nf_ct_icmpv6_timeout,
 352                 .maxlen         = sizeof(unsigned int),
 353                 .mode           = 0644,
 354                 .proc_handler   = &proc_dointvec_jiffies,
 355         },
 356         {
 357                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_TIMEOUT,
 358                 .procname       = "nf_conntrack_frag6_timeout",
 359                 .data           = &nf_ct_frag6_timeout,
 360                 .maxlen         = sizeof(unsigned int),
 361                 .mode           = 0644,
 362                 .proc_handler   = &proc_dointvec_jiffies,
 363         },
 364         {
 365                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
 366                 .procname       = "nf_conntrack_frag6_low_thresh",
 367                 .data           = &nf_ct_frag6_low_thresh,
 368                 .maxlen         = sizeof(unsigned int),
 369                 .mode           = 0644,
 370                 .proc_handler   = &proc_dointvec,
 371         },
 372         {
 373                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
 374                 .procname       = "nf_conntrack_frag6_high_thresh",
 375                 .data           = &nf_ct_frag6_high_thresh,
 376                 .maxlen         = sizeof(unsigned int),
 377                 .mode           = 0644,
 378                 .proc_handler   = &proc_dointvec,
 379         },
 380         { .ctl_name = 0 }
 381 };
 382
 383 static ctl_table nf_ct_netfilter_table[] = {
 384         {
 385                 .ctl_name       = NET_NETFILTER,
 386                 .procname       = "netfilter",
 387                 .mode           = 0555,
 388                 .child          = nf_ct_sysctl_table,
 389         },
 390         { .ctl_name = 0 }
 391 };
 392
 393 static ctl_table nf_ct_net_table[] = {
 394         {
 395                 .ctl_name       = CTL_NET,
 396                 .procname       = "net",
 397                 .mode           = 0555,
 398                 .child          = nf_ct_netfilter_table,
 399         },
 400         { .ctl_name = 0 }
 401 };
 402 #endif
 403
 404 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
 405         .l3proto                = PF_INET6,
 406         .name                   = "ipv6",
 407         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 408         .invert_tuple           = ipv6_invert_tuple,
 409         .print_tuple            = ipv6_print_tuple,
 410         .print_conntrack        = ipv6_print_conntrack,
 411         .prepare                = ipv6_prepare,
 412         .get_features           = ipv6_get_features,
 413         .me                     = THIS_MODULE,
 414 };
 415
 416 extern struct nf_conntrack_protocol nf_conntrack_protocol_tcp6;
 417 extern struct nf_conntrack_protocol nf_conntrack_protocol_udp6;
 418 extern struct nf_conntrack_protocol nf_conntrack_protocol_icmpv6;
 419 extern int nf_ct_frag6_init(void);
 420 extern void nf_ct_frag6_cleanup(void);
 421 static int init_or_cleanup(int init)
 422 {
 423         int ret = 0;
 424
 425         if (!init) goto cleanup;
 426
 427         ret = nf_ct_frag6_init();
 428         if (ret < 0) {
 429                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 430                 goto cleanup_nothing;
 431         }
 432         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_tcp6);
 433         if (ret < 0) {
 434                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 435                 goto cleanup_frag6;
 436         }
 437
 438         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_udp6);
 439         if (ret < 0) {
 440                 printk("nf_conntrack_ipv6: can't register udp.\n");
 441                 goto cleanup_tcp;
 442         }
 443
 444         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_icmpv6);
 445         if (ret < 0) {
 446                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 447                 goto cleanup_udp;
 448         }
 449
 450         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 451         if (ret < 0) {
 452                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 453                 goto cleanup_icmpv6;
 454         }
 455
 456         ret = nf_register_hook(&ipv6_conntrack_defrag_ops);
 457         if (ret < 0) {
 458                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 459                        "hook.\n");
 460                 goto cleanup_ipv6;
 461         }
 462
 463         ret = nf_register_hook(&ipv6_conntrack_defrag_local_out_ops);
 464         if (ret < 0) {
 465                 printk("nf_conntrack_ipv6: can't register local_out defrag "
 466                        "hook.\n");
 467                 goto cleanup_defragops;
 468         }
 469
 470         ret = nf_register_hook(&ipv6_conntrack_in_ops);
 471         if (ret < 0) {
 472                 printk("nf_conntrack_ipv6: can't register pre-routing hook.\n");
 473                 goto cleanup_defraglocalops;
 474         }
 475
 476         ret = nf_register_hook(&ipv6_conntrack_local_out_ops);
 477         if (ret < 0) {
 478                 printk("nf_conntrack_ipv6: can't register local out hook.\n");
 479                 goto cleanup_inops;
 480         }
 481
 482         ret = nf_register_hook(&ipv6_conntrack_out_ops);
 483         if (ret < 0) {
 484                 printk("nf_conntrack_ipv6: can't register post-routing hook.\n");
 485                 goto cleanup_inandlocalops;
 486         }
 487
 488         ret = nf_register_hook(&ipv6_conntrack_local_in_ops);
 489         if (ret < 0) {
 490                 printk("nf_conntrack_ipv6: can't register local in hook.\n");
 491                 goto cleanup_inoutandlocalops;
 492         }
 493
 494 #ifdef CONFIG_SYSCTL
 495         nf_ct_ipv6_sysctl_header = register_sysctl_table(nf_ct_net_table, 0);
 496         if (nf_ct_ipv6_sysctl_header == NULL) {
 497                 printk("nf_conntrack: can't register to sysctl.\n");
 498                 ret = -ENOMEM;
 499                 goto cleanup_localinops;
 500         }
 501 #endif
 502         return ret;
 503
 504  cleanup:
 505         synchronize_net();
 506 #ifdef CONFIG_SYSCTL
 507         unregister_sysctl_table(nf_ct_ipv6_sysctl_header);
 508  cleanup_localinops:
 509 #endif
 510         nf_unregister_hook(&ipv6_conntrack_local_in_ops);
 511  cleanup_inoutandlocalops:
 512         nf_unregister_hook(&ipv6_conntrack_out_ops);
 513  cleanup_inandlocalops:
 514         nf_unregister_hook(&ipv6_conntrack_local_out_ops);
 515  cleanup_inops:
 516         nf_unregister_hook(&ipv6_conntrack_in_ops);
 517  cleanup_defraglocalops:
 518         nf_unregister_hook(&ipv6_conntrack_defrag_local_out_ops);
 519  cleanup_defragops:
 520         nf_unregister_hook(&ipv6_conntrack_defrag_ops);
 521  cleanup_ipv6:
 522         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 523  cleanup_icmpv6:
 524         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_icmpv6);
 525  cleanup_udp:
 526         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_udp6);
 527  cleanup_tcp:
 528         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_tcp6);
 529  cleanup_frag6:
 530         nf_ct_frag6_cleanup();
 531  cleanup_nothing:
 532         return ret;
 533 }
 534
 535 MODULE_LICENSE("GPL");
 536 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 537
 538 static int __init init(void)
 539 {
 540         need_nf_conntrack();
 541         return init_or_cleanup(1);
 542 }
 543
 544 static void __exit fini(void)
 545 {
 546         init_or_cleanup(0);
 547 }
 548
 549 module_init(init);
 550 module_exit(fini);
 551
 552 void need_ip6_conntrack(void)
 553 {
 554 }
 555
 556 EXPORT_SYMBOL(need_ip6_conntrack);