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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
  22 #include <linux/netfilter_ipv6.h>
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_helper.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_l3proto.h>
  27 #include <net/netfilter/nf_conntrack_core.h>
  28
  29 #if 0
  30 #define DEBUGP printk
  31 #else
  32 #define DEBUGP(format, args...)
  33 #endif
  34
  35 static int ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  36                              struct nf_conntrack_tuple *tuple)
  37 {
  38         u_int32_t _addrs[8], *ap;
  39
  40         ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
  41                                 sizeof(_addrs), _addrs);
  42         if (ap == NULL)
  43                 return 0;
  44
  45         memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
  46         memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
  47
  48         return 1;
  49 }
  50
  51 static int ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  52                              const struct nf_conntrack_tuple *orig)
  53 {
  54         memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
  55         memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));
  56
  57         return 1;
  58 }
  59
  60 static int ipv6_print_tuple(struct seq_file *s,
  61                             const struct nf_conntrack_tuple *tuple)
  62 {
  63         return seq_printf(s, "src=" NIP6_FMT " dst=" NIP6_FMT " ",
  64                           NIP6(*((struct in6_addr *)tuple->src.u3.ip6)),
  65                           NIP6(*((struct in6_addr *)tuple->dst.u3.ip6)));
  66 }
  67
  68 static int ipv6_print_conntrack(struct seq_file *s,
  69                                 const struct nf_conn *conntrack)
  70 {
  71         return 0;
  72 }
  73
  74 /*
  75  * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
  76  *
  77  * This function parses (probably truncated) exthdr set "hdr"
  78  * of length "len". "nexthdrp" initially points to some place,
  79  * where type of the first header can be found.
  80  *
  81  * It skips all well-known exthdrs, and returns pointer to the start
  82  * of unparsable area i.e. the first header with unknown type.
  83  * if success, *nexthdr is updated by type/protocol of this header.
  84  *
  85  * NOTES: - it may return pointer pointing beyond end of packet,
  86  *          if the last recognized header is truncated in the middle.
  87  *        - if packet is truncated, so that all parsed headers are skipped,
  88  *          it returns -1.
  89  *        - if packet is fragmented, return pointer of the fragment header.
  90  *        - ESP is unparsable for now and considered like
  91  *          normal payload protocol.
  92  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  93  */
  94
  95 int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
  96                            int len)
  97 {
  98         u8 nexthdr = *nexthdrp;
  99
 100         while (ipv6_ext_hdr(nexthdr)) {
 101                 struct ipv6_opt_hdr hdr;
 102                 int hdrlen;
 103
 104                 if (len < (int)sizeof(struct ipv6_opt_hdr))
 105                         return -1;
 106                 if (nexthdr == NEXTHDR_NONE)
 107                         break;
 108                 if (nexthdr == NEXTHDR_FRAGMENT)
 109                         break;
 110                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 111                         BUG();
 112                 if (nexthdr == NEXTHDR_AUTH)
 113                         hdrlen = (hdr.hdrlen+2)<<2;
 114                 else
 115                         hdrlen = ipv6_optlen(&hdr);
 116
 117                 nexthdr = hdr.nexthdr;
 118                 len -= hdrlen;
 119                 start += hdrlen;
 120         }
 121
 122         *nexthdrp = nexthdr;
 123         return start;
 124 }
 125
 126 static int
 127 ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
 128              u_int8_t *protonum)
 129 {
 130         unsigned int extoff = (u8 *)(ipv6_hdr(*pskb) + 1) - (*pskb)->data;
 131         unsigned char pnum = ipv6_hdr(*pskb)->nexthdr;
 132         int protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 133                                              (*pskb)->len - extoff);
 134         /*
 135          * (protoff == (*pskb)->len) mean that the packet doesn't have no data
 136          * except of IPv6 & ext headers. but it's tracked anyway. - YK
 137          */
 138         if ((protoff < 0) || (protoff > (*pskb)->len)) {
 139                 DEBUGP("ip6_conntrack_core: can't find proto in pkt\n");
 140                 NF_CT_STAT_INC_ATOMIC(error);
 141                 NF_CT_STAT_INC_ATOMIC(invalid);
 142                 return -NF_ACCEPT;
 143         }
 144
 145         *dataoff = protoff;
 146         *protonum = pnum;
 147         return NF_ACCEPT;
 148 }
 149
 150 static u_int32_t ipv6_get_features(const struct nf_conntrack_tuple *tuple)
 151 {
 152         return NF_CT_F_BASIC;
 153 }
 154
 155 static unsigned int ipv6_confirm(unsigned int hooknum,
 156                                  struct sk_buff **pskb,
 157                                  const struct net_device *in,
 158                                  const struct net_device *out,
 159                                  int (*okfn)(struct sk_buff *))
 160 {
 161         struct nf_conn *ct;
 162         struct nf_conn_help *help;
 163         struct nf_conntrack_helper *helper;
 164         enum ip_conntrack_info ctinfo;
 165         unsigned int ret, protoff;
 166         unsigned int extoff = (u8 *)(ipv6_hdr(*pskb) + 1) - (*pskb)->data;
 167         unsigned char pnum = ipv6_hdr(*pskb)->nexthdr;
 168
 169
 170         /* This is where we call the helper: as the packet goes out. */
 171         ct = nf_ct_get(*pskb, &ctinfo);
 172         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 173                 goto out;
 174
 175         help = nfct_help(ct);
 176         if (!help)
 177                 goto out;
 178         /* rcu_read_lock()ed by nf_hook_slow */
 179         helper = rcu_dereference(help->helper);
 180         if (!helper)
 181                 goto out;
 182
 183         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 184                                          (*pskb)->len - extoff);
 185         if (protoff > (*pskb)->len || pnum == NEXTHDR_FRAGMENT) {
 186                 DEBUGP("proto header not found\n");
 187                 return NF_ACCEPT;
 188         }
 189
 190         ret = helper->help(pskb, protoff, ct, ctinfo);
 191         if (ret != NF_ACCEPT)
 192                 return ret;
 193 out:
 194         /* We've seen it coming out the other side: confirm it */
 195         return nf_conntrack_confirm(pskb);
 196 }
 197
 198 static unsigned int ipv6_defrag(unsigned int hooknum,
 199                                 struct sk_buff **pskb,
 200                                 const struct net_device *in,
 201                                 const struct net_device *out,
 202                                 int (*okfn)(struct sk_buff *))
 203 {
 204         struct sk_buff *reasm;
 205
 206         /* Previously seen (loopback)?  */
 207         if ((*pskb)->nfct)
 208                 return NF_ACCEPT;
 209
 210         reasm = nf_ct_frag6_gather(*pskb);
 211
 212         /* queued */
 213         if (reasm == NULL)
 214                 return NF_STOLEN;
 215
 216         /* error occured or not fragmented */
 217         if (reasm == *pskb)
 218                 return NF_ACCEPT;
 219
 220         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 221                            (struct net_device *)out, okfn);
 222
 223         return NF_STOLEN;
 224 }
 225
 226 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 227                                       struct sk_buff **pskb,
 228                                       const struct net_device *in,
 229                                       const struct net_device *out,
 230                                       int (*okfn)(struct sk_buff *))
 231 {
 232         struct sk_buff *reasm = (*pskb)->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(PF_INET6, hooknum, &reasm);
 241                         if (ret != NF_ACCEPT)
 242                                 return ret;
 243                 }
 244                 nf_conntrack_get(reasm->nfct);
 245                 (*pskb)->nfct = reasm->nfct;
 246                 (*pskb)->nfctinfo = reasm->nfctinfo;
 247                 return NF_ACCEPT;
 248         }
 249
 250         return nf_conntrack_in(PF_INET6, hooknum, pskb);
 251 }
 252
 253 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 254                                          struct sk_buff **pskb,
 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 ((*pskb)->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(hooknum, pskb, in, out, okfn);
 266 }
 267
 268 static struct nf_hook_ops ipv6_conntrack_ops[] = {
 269         {
 270                 .hook           = ipv6_defrag,
 271                 .owner          = THIS_MODULE,
 272                 .pf             = PF_INET6,
 273                 .hooknum        = NF_IP6_PRE_ROUTING,
 274                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 275         },
 276         {
 277                 .hook           = ipv6_conntrack_in,
 278                 .owner          = THIS_MODULE,
 279                 .pf             = PF_INET6,
 280                 .hooknum        = NF_IP6_PRE_ROUTING,
 281                 .priority       = NF_IP6_PRI_CONNTRACK,
 282         },
 283         {
 284                 .hook           = ipv6_conntrack_local,
 285                 .owner          = THIS_MODULE,
 286                 .pf             = PF_INET6,
 287                 .hooknum        = NF_IP6_LOCAL_OUT,
 288                 .priority       = NF_IP6_PRI_CONNTRACK,
 289         },
 290         {
 291                 .hook           = ipv6_defrag,
 292                 .owner          = THIS_MODULE,
 293                 .pf             = PF_INET6,
 294                 .hooknum        = NF_IP6_LOCAL_OUT,
 295                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 296         },
 297         {
 298                 .hook           = ipv6_confirm,
 299                 .owner          = THIS_MODULE,
 300                 .pf             = PF_INET6,
 301                 .hooknum        = NF_IP6_POST_ROUTING,
 302                 .priority       = NF_IP6_PRI_LAST,
 303         },
 304         {
 305                 .hook           = ipv6_confirm,
 306                 .owner          = THIS_MODULE,
 307                 .pf             = PF_INET6,
 308                 .hooknum        = NF_IP6_LOCAL_IN,
 309                 .priority       = NF_IP6_PRI_LAST-1,
 310         },
 311 };
 312
 313 #ifdef CONFIG_SYSCTL
 314 static ctl_table nf_ct_ipv6_sysctl_table[] = {
 315         {
 316                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_TIMEOUT,
 317                 .procname       = "nf_conntrack_frag6_timeout",
 318                 .data           = &nf_ct_frag6_timeout,
 319                 .maxlen         = sizeof(unsigned int),
 320                 .mode           = 0644,
 321                 .proc_handler   = &proc_dointvec_jiffies,
 322         },
 323         {
 324                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
 325                 .procname       = "nf_conntrack_frag6_low_thresh",
 326                 .data           = &nf_ct_frag6_low_thresh,
 327                 .maxlen         = sizeof(unsigned int),
 328                 .mode           = 0644,
 329                 .proc_handler   = &proc_dointvec,
 330         },
 331         {
 332                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
 333                 .procname       = "nf_conntrack_frag6_high_thresh",
 334                 .data           = &nf_ct_frag6_high_thresh,
 335                 .maxlen         = sizeof(unsigned int),
 336                 .mode           = 0644,
 337                 .proc_handler   = &proc_dointvec,
 338         },
 339         { .ctl_name = 0 }
 340 };
 341 #endif
 342
 343 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 344
 345 #include <linux/netfilter/nfnetlink.h>
 346 #include <linux/netfilter/nfnetlink_conntrack.h>
 347
 348 static int ipv6_tuple_to_nfattr(struct sk_buff *skb,
 349                                 const struct nf_conntrack_tuple *tuple)
 350 {
 351         NFA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 352                 &tuple->src.u3.ip6);
 353         NFA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 354                 &tuple->dst.u3.ip6);
 355         return 0;
 356
 357 nfattr_failure:
 358         return -1;
 359 }
 360
 361 static const size_t cta_min_ip[CTA_IP_MAX] = {
 362         [CTA_IP_V6_SRC-1]       = sizeof(u_int32_t)*4,
 363         [CTA_IP_V6_DST-1]       = sizeof(u_int32_t)*4,
 364 };
 365
 366 static int ipv6_nfattr_to_tuple(struct nfattr *tb[],
 367                                 struct nf_conntrack_tuple *t)
 368 {
 369         if (!tb[CTA_IP_V6_SRC-1] || !tb[CTA_IP_V6_DST-1])
 370                 return -EINVAL;
 371
 372         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 373                 return -EINVAL;
 374
 375         memcpy(&t->src.u3.ip6, NFA_DATA(tb[CTA_IP_V6_SRC-1]),
 376                sizeof(u_int32_t) * 4);
 377         memcpy(&t->dst.u3.ip6, NFA_DATA(tb[CTA_IP_V6_DST-1]),
 378                sizeof(u_int32_t) * 4);
 379
 380         return 0;
 381 }
 382 #endif
 383
 384 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
 385         .l3proto                = PF_INET6,
 386         .name                   = "ipv6",
 387         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 388         .invert_tuple           = ipv6_invert_tuple,
 389         .print_tuple            = ipv6_print_tuple,
 390         .print_conntrack        = ipv6_print_conntrack,
 391         .prepare                = ipv6_prepare,
 392 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 393         .tuple_to_nfattr        = ipv6_tuple_to_nfattr,
 394         .nfattr_to_tuple        = ipv6_nfattr_to_tuple,
 395 #endif
 396 #ifdef CONFIG_SYSCTL
 397         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 398         .ctl_table              = nf_ct_ipv6_sysctl_table,
 399 #endif
 400         .get_features           = ipv6_get_features,
 401         .me                     = THIS_MODULE,
 402 };
 403
 404 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 405 MODULE_LICENSE("GPL");
 406 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 407
 408 static int __init nf_conntrack_l3proto_ipv6_init(void)
 409 {
 410         int ret = 0;
 411
 412         need_conntrack();
 413
 414         ret = nf_ct_frag6_init();
 415         if (ret < 0) {
 416                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 417                 return ret;
 418         }
 419         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 420         if (ret < 0) {
 421                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 422                 goto cleanup_frag6;
 423         }
 424
 425         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 426         if (ret < 0) {
 427                 printk("nf_conntrack_ipv6: can't register udp.\n");
 428                 goto cleanup_tcp;
 429         }
 430
 431         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 432         if (ret < 0) {
 433                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 434                 goto cleanup_udp;
 435         }
 436
 437         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 438         if (ret < 0) {
 439                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 440                 goto cleanup_icmpv6;
 441         }
 442
 443         ret = nf_register_hooks(ipv6_conntrack_ops,
 444                                 ARRAY_SIZE(ipv6_conntrack_ops));
 445         if (ret < 0) {
 446                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 447                        "hook.\n");
 448                 goto cleanup_ipv6;
 449         }
 450         return ret;
 451
 452  cleanup_ipv6:
 453         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 454  cleanup_icmpv6:
 455         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 456  cleanup_udp:
 457         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 458  cleanup_tcp:
 459         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 460  cleanup_frag6:
 461         nf_ct_frag6_cleanup();
 462         return ret;
 463 }
 464
 465 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 466 {
 467         synchronize_net();
 468         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 469         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 470         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 471         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 472         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 473         nf_ct_frag6_cleanup();
 474 }
 475
 476 module_init(nf_conntrack_l3proto_ipv6_init);
 477 module_exit(nf_conntrack_l3proto_ipv6_fini);