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_protocol.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 DECLARE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat);
  47
  48 static int ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  49                              struct nf_conntrack_tuple *tuple)
  50 {
  51         u_int32_t _addrs[8], *ap;
  52
  53         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  54                                 sizeof(_addrs), _addrs);
  55         if (ap == NULL)
  56                 return 0;
  57
  58         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  59         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  60
  61         return 1;
  62 }
  63
  64 static int ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  65                              const struct nf_conntrack_tuple *orig)
  66 {
  67         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  68         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  69
  70         return 1;
  71 }
  72
  73 static int ipv6_print_tuple(struct seq_file *s,
  74                             const struct nf_conntrack_tuple *tuple)
  75 {
  76         return seq_printf(s, "src=" NIP6_FMT " dst=" NIP6_FMT " ",
  77                           NIP6(*((struct in6_addr *)tuple->src.u3.ip6)),
  78                           NIP6(*((struct in6_addr *)tuple->dst.u3.ip6)));
  79 }
  80
  81 static int ipv6_print_conntrack(struct seq_file *s,
  82                                 const struct nf_conn *conntrack)
  83 {
  84         return 0;
  85 }
  86
  87 /*
  88  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  89  *
  90  * This function parses (probably truncated) exthdr set "hdr"
  91  * of length "len". "nexthdrp" initially points to some place,
  92  * where type of the first header can be found.
  93  *
  94  * It skips all well-known exthdrs, and returns pointer to the start
  95  * of unparsable area i.e. the first header with unknown type.
  96  * if success, *nexthdr is updated by type/protocol of this header.
  97  *
  98  * NOTES: - it may return pointer pointing beyond end of packet,
  99  *          if the last recognized header is truncated in the middle.
 100  *        - if packet is truncated, so that all parsed headers are skipped,
 101  *          it returns -1.
 102  *        - if packet is fragmented, return pointer of the fragment header.
 103  *        - ESP is unparsable for now and considered like
 104  *          normal payload protocol.
 105  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
 106  */
 107
 108 int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
 109                            int len)
 110 {
 111         u8 nexthdr = *nexthdrp;
 112
 113         while (ipv6_ext_hdr(nexthdr)) {
 114                 struct ipv6_opt_hdr hdr;
 115                 int hdrlen;
 116
 117                 if (len < (int)sizeof(struct ipv6_opt_hdr))
 118                         return -1;
 119                 if (nexthdr == NEXTHDR_NONE)
 120                         break;
 121                 if (nexthdr == NEXTHDR_FRAGMENT)
 122                         break;
 123                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 124                         BUG();
 125                 if (nexthdr == NEXTHDR_AUTH)
 126                         hdrlen = (hdr.hdrlen+2)<<2;
 127                 else
 128                         hdrlen = ipv6_optlen(&hdr);
 129
 130                 nexthdr = hdr.nexthdr;
 131                 len -= hdrlen;
 132                 start += hdrlen;
 133         }
 134
 135         *nexthdrp = nexthdr;
 136         return start;
 137 }
 138
 139 static int
 140 ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
 141              u_int8_t *protonum)
 142 {
 143         unsigned int extoff;
 144         unsigned char pnum;
 145         int protoff;
 146
 147         extoff = (u8*)((*pskb)->nh.ipv6h + 1) - (*pskb)->data;
 148         pnum = (*pskb)->nh.ipv6h->nexthdr;
 149
 150         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 151                                          (*pskb)->len - extoff);
 152
 153         /*
 154          * (protoff == (*pskb)->len) mean that the packet doesn't have no data
 155          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 156          */
 157         if ((protoff < 0) || (protoff > (*pskb)->len)) {
 158                 DEBUGP("ip6_conntrack_core: can't find proto in pkt\n");
 159                 NF_CT_STAT_INC(error);
 160                 NF_CT_STAT_INC(invalid);
 161                 return -NF_ACCEPT;
 162         }
 163
 164         *dataoff = protoff;
 165         *protonum = pnum;
 166         return NF_ACCEPT;
 167 }
 168
 169 static u_int32_t ipv6_get_features(const struct nf_conntrack_tuple *tuple)
 170 {
 171         return NF_CT_F_BASIC;
 172 }
 173
 174 static unsigned int ipv6_confirm(unsigned int hooknum,
 175                                  struct sk_buff **pskb,
 176                                  const struct net_device *in,
 177                                  const struct net_device *out,
 178                                  int (*okfn)(struct sk_buff *))
 179 {
 180         struct nf_conn *ct;
 181         struct nf_conn_help *help;
 182         enum ip_conntrack_info ctinfo;
 183         unsigned int ret, protoff;
 184         unsigned int extoff = (u8*)((*pskb)->nh.ipv6h + 1)
 185                               - (*pskb)->data;
 186         unsigned char pnum = (*pskb)->nh.ipv6h->nexthdr;
 187
 188
 189         /* This is where we call the helper: as the packet goes out. */
 190         ct = nf_ct_get(*pskb, &ctinfo);
 191         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 192                 goto out;
 193
 194         help = nfct_help(ct);
 195         if (!help || !help->helper)
 196                 goto out;
 197
 198         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 199                                          (*pskb)->len - extoff);
 200         if (protoff < 0 || protoff > (*pskb)->len ||
 201             pnum == NEXTHDR_FRAGMENT) {
 202                 DEBUGP("proto header not found\n");
 203                 return NF_ACCEPT;
 204         }
 205
 206         ret = help->helper->help(pskb, protoff, ct, ctinfo);
 207         if (ret != NF_ACCEPT)
 208                 return ret;
 209 out:
 210         /* We've seen it coming out the other side: confirm it */
 211         return nf_conntrack_confirm(pskb);
 212 }
 213
 214 extern struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb);
 215 extern void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
 216                                struct net_device *in,
 217                                struct net_device *out,
 218                                int (*okfn)(struct sk_buff *));
 219 static unsigned int ipv6_defrag(unsigned int hooknum,
 220                                 struct sk_buff **pskb,
 221                                 const struct net_device *in,
 222                                 const struct net_device *out,
 223                                 int (*okfn)(struct sk_buff *))
 224 {
 225         struct sk_buff *reasm;
 226
 227         /* Previously seen (loopback)?  */
 228         if ((*pskb)->nfct)
 229                 return NF_ACCEPT;
 230
 231         reasm = nf_ct_frag6_gather(*pskb);
 232
 233         /* queued */
 234         if (reasm == NULL)
 235                 return NF_STOLEN;
 236
 237         /* error occured or not fragmented */
 238         if (reasm == *pskb)
 239                 return NF_ACCEPT;
 240
 241         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 242                            (struct net_device *)out, okfn);
 243
 244         return NF_STOLEN;
 245 }
 246
 247 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 248                                       struct sk_buff **pskb,
 249                                       const struct net_device *in,
 250                                       const struct net_device *out,
 251                                       int (*okfn)(struct sk_buff *))
 252 {
 253         struct sk_buff *reasm = (*pskb)->nfct_reasm;
 254
 255         /* This packet is fragmented and has reassembled packet. */
 256         if (reasm) {
 257                 /* Reassembled packet isn't parsed yet ? */
 258                 if (!reasm->nfct) {
 259                         unsigned int ret;
 260
 261                         ret = nf_conntrack_in(PF_INET6, hooknum, &reasm);
 262                         if (ret != NF_ACCEPT)
 263                                 return ret;
 264                 }
 265                 nf_conntrack_get(reasm->nfct);
 266                 (*pskb)->nfct = reasm->nfct;
 267                 return NF_ACCEPT;
 268         }
 269
 270         return nf_conntrack_in(PF_INET6, hooknum, pskb);
 271 }
 272
 273 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 274                                          struct sk_buff **pskb,
 275                                          const struct net_device *in,
 276                                          const struct net_device *out,
 277                                          int (*okfn)(struct sk_buff *))
 278 {
 279         /* root is playing with raw sockets. */
 280         if ((*pskb)->len < sizeof(struct ipv6hdr)) {
 281                 if (net_ratelimit())
 282                         printk("ipv6_conntrack_local: packet too short\n");
 283                 return NF_ACCEPT;
 284         }
 285         return ipv6_conntrack_in(hooknum, pskb, in, out, okfn);
 286 }
 287
 288 static struct nf_hook_ops ipv6_conntrack_ops[] = {
 289         {
 290                 .hook           = ipv6_defrag,
 291                 .owner          = THIS_MODULE,
 292                 .pf             = PF_INET6,
 293                 .hooknum        = NF_IP6_PRE_ROUTING,
 294                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 295         },
 296         {
 297                 .hook           = ipv6_conntrack_in,
 298                 .owner          = THIS_MODULE,
 299                 .pf             = PF_INET6,
 300                 .hooknum        = NF_IP6_PRE_ROUTING,
 301                 .priority       = NF_IP6_PRI_CONNTRACK,
 302         },
 303         {
 304                 .hook           = ipv6_conntrack_local,
 305                 .owner          = THIS_MODULE,
 306                 .pf             = PF_INET6,
 307                 .hooknum        = NF_IP6_LOCAL_OUT,
 308                 .priority       = NF_IP6_PRI_CONNTRACK,
 309         },
 310         {
 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                 .hook           = ipv6_confirm,
 319                 .owner          = THIS_MODULE,
 320                 .pf             = PF_INET6,
 321                 .hooknum        = NF_IP6_POST_ROUTING,
 322                 .priority       = NF_IP6_PRI_LAST,
 323         },
 324         {
 325                 .hook           = ipv6_confirm,
 326                 .owner          = THIS_MODULE,
 327                 .pf             = PF_INET6,
 328                 .hooknum        = NF_IP6_LOCAL_IN,
 329                 .priority       = NF_IP6_PRI_LAST-1,
 330         },
 331 };
 332
 333 #ifdef CONFIG_SYSCTL
 334
 335 /* From nf_conntrack_proto_icmpv6.c */
 336 extern unsigned int nf_ct_icmpv6_timeout;
 337
 338 /* From nf_conntrack_frag6.c */
 339 extern unsigned int nf_ct_frag6_timeout;
 340 extern unsigned int nf_ct_frag6_low_thresh;
 341 extern unsigned int nf_ct_frag6_high_thresh;
 342
 343 static struct ctl_table_header *nf_ct_ipv6_sysctl_header;
 344
 345 static ctl_table nf_ct_sysctl_table[] = {
 346         {
 347                 .ctl_name       = NET_NF_CONNTRACK_ICMPV6_TIMEOUT,
 348                 .procname       = "nf_conntrack_icmpv6_timeout",
 349                 .data           = &nf_ct_icmpv6_timeout,
 350                 .maxlen         = sizeof(unsigned int),
 351                 .mode           = 0644,
 352                 .proc_handler   = &proc_dointvec_jiffies,
 353         },
 354         {
 355                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_TIMEOUT,
 356                 .procname       = "nf_conntrack_frag6_timeout",
 357                 .data           = &nf_ct_frag6_timeout,
 358                 .maxlen         = sizeof(unsigned int),
 359                 .mode           = 0644,
 360                 .proc_handler   = &proc_dointvec_jiffies,
 361         },
 362         {
 363                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
 364                 .procname       = "nf_conntrack_frag6_low_thresh",
 365                 .data           = &nf_ct_frag6_low_thresh,
 366                 .maxlen         = sizeof(unsigned int),
 367                 .mode           = 0644,
 368                 .proc_handler   = &proc_dointvec,
 369         },
 370         {
 371                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
 372                 .procname       = "nf_conntrack_frag6_high_thresh",
 373                 .data           = &nf_ct_frag6_high_thresh,
 374                 .maxlen         = sizeof(unsigned int),
 375                 .mode           = 0644,
 376                 .proc_handler   = &proc_dointvec,
 377         },
 378         { .ctl_name = 0 }
 379 };
 380
 381 static ctl_table nf_ct_netfilter_table[] = {
 382         {
 383                 .ctl_name       = NET_NETFILTER,
 384                 .procname       = "netfilter",
 385                 .mode           = 0555,
 386                 .child          = nf_ct_sysctl_table,
 387         },
 388         { .ctl_name = 0 }
 389 };
 390
 391 static ctl_table nf_ct_net_table[] = {
 392         {
 393                 .ctl_name       = CTL_NET,
 394                 .procname       = "net",
 395                 .mode           = 0555,
 396                 .child          = nf_ct_netfilter_table,
 397         },
 398         { .ctl_name = 0 }
 399 };
 400 #endif
 401
 402 #if defined(CONFIG_NF_CT_NETLINK) || \
 403     defined(CONFIG_NF_CT_NETLINK_MODULE)
 404
 405 #include <linux/netfilter/nfnetlink.h>
 406 #include <linux/netfilter/nfnetlink_conntrack.h>
 407
 408 static int ipv6_tuple_to_nfattr(struct sk_buff *skb,
 409                                 const struct nf_conntrack_tuple *tuple)
 410 {
 411         NFA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 412                 &tuple->src.u3.ip6);
 413         NFA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 414                 &tuple->dst.u3.ip6);
 415         return 0;
 416
 417 nfattr_failure:
 418         return -1;
 419 }
 420
 421 static const size_t cta_min_ip[CTA_IP_MAX] = {
 422         [CTA_IP_V6_SRC-1]       = sizeof(u_int32_t)*4,
 423         [CTA_IP_V6_DST-1]       = sizeof(u_int32_t)*4,
 424 };
 425
 426 static int ipv6_nfattr_to_tuple(struct nfattr *tb[],
 427                                 struct nf_conntrack_tuple *t)
 428 {
 429         if (!tb[CTA_IP_V6_SRC-1] || !tb[CTA_IP_V6_DST-1])
 430                 return -EINVAL;
 431
 432         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 433                 return -EINVAL;
 434
 435         memcpy(&t->src.u3.ip6, NFA_DATA(tb[CTA_IP_V6_SRC-1]),
 436                sizeof(u_int32_t) * 4);
 437         memcpy(&t->dst.u3.ip6, NFA_DATA(tb[CTA_IP_V6_DST-1]),
 438                sizeof(u_int32_t) * 4);
 439
 440         return 0;
 441 }
 442 #endif
 443
 444 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
 445         .l3proto                = PF_INET6,
 446         .name                   = "ipv6",
 447         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 448         .invert_tuple           = ipv6_invert_tuple,
 449         .print_tuple            = ipv6_print_tuple,
 450         .print_conntrack        = ipv6_print_conntrack,
 451         .prepare                = ipv6_prepare,
 452 #if defined(CONFIG_NF_CT_NETLINK) || \
 453     defined(CONFIG_NF_CT_NETLINK_MODULE)
 454         .tuple_to_nfattr        = ipv6_tuple_to_nfattr,
 455         .nfattr_to_tuple        = ipv6_nfattr_to_tuple,
 456 #endif
 457         .get_features           = ipv6_get_features,
 458         .me                     = THIS_MODULE,
 459 };
 460
 461 extern struct nf_conntrack_protocol nf_conntrack_protocol_tcp6;
 462 extern struct nf_conntrack_protocol nf_conntrack_protocol_udp6;
 463 extern struct nf_conntrack_protocol nf_conntrack_protocol_icmpv6;
 464 extern int nf_ct_frag6_init(void);
 465 extern void nf_ct_frag6_cleanup(void);
 466
 467 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 468 MODULE_LICENSE("GPL");
 469 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 470
 471 static int __init nf_conntrack_l3proto_ipv6_init(void)
 472 {
 473         int ret = 0;
 474
 475         need_conntrack();
 476
 477         ret = nf_ct_frag6_init();
 478         if (ret < 0) {
 479                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 480                 return ret;
 481         }
 482         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_tcp6);
 483         if (ret < 0) {
 484                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 485                 goto cleanup_frag6;
 486         }
 487
 488         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_udp6);
 489         if (ret < 0) {
 490                 printk("nf_conntrack_ipv6: can't register udp.\n");
 491                 goto cleanup_tcp;
 492         }
 493
 494         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_icmpv6);
 495         if (ret < 0) {
 496                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 497                 goto cleanup_udp;
 498         }
 499
 500         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 501         if (ret < 0) {
 502                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 503                 goto cleanup_icmpv6;
 504         }
 505
 506         ret = nf_register_hooks(ipv6_conntrack_ops,
 507                                 ARRAY_SIZE(ipv6_conntrack_ops));
 508         if (ret < 0) {
 509                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 510                        "hook.\n");
 511                 goto cleanup_ipv6;
 512         }
 513 #ifdef CONFIG_SYSCTL
 514         nf_ct_ipv6_sysctl_header = register_sysctl_table(nf_ct_net_table, 0);
 515         if (nf_ct_ipv6_sysctl_header == NULL) {
 516                 printk("nf_conntrack: can't register to sysctl.\n");
 517                 ret = -ENOMEM;
 518                 goto cleanup_hooks;
 519         }
 520 #endif
 521         return ret;
 522
 523 #ifdef CONFIG_SYSCTL
 524  cleanup_hooks:
 525         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 526 #endif
 527  cleanup_ipv6:
 528         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 529  cleanup_icmpv6:
 530         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_icmpv6);
 531  cleanup_udp:
 532         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_udp6);
 533  cleanup_tcp:
 534         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_tcp6);
 535  cleanup_frag6:
 536         nf_ct_frag6_cleanup();
 537         return ret;
 538 }
 539
 540 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 541 {
 542         synchronize_net();
 543 #ifdef CONFIG_SYSCTL
 544         unregister_sysctl_table(nf_ct_ipv6_sysctl_header);
 545 #endif
 546         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 547         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 548         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_icmpv6);
 549         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_udp6);
 550         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_tcp6);
 551         nf_ct_frag6_cleanup();
 552 }
 553
 554 module_init(nf_conntrack_l3proto_ipv6_init);
 555 module_exit(nf_conntrack_l3proto_ipv6_fini);