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
  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         enum ip_conntrack_info ctinfo;
 164         unsigned int ret, protoff;
 165         unsigned int extoff = (u8 *)(ipv6_hdr(*pskb) + 1) - (*pskb)->data;
 166         unsigned char pnum = ipv6_hdr(*pskb)->nexthdr;
 167
 168
 169         /* This is where we call the helper: as the packet goes out. */
 170         ct = nf_ct_get(*pskb, &ctinfo);
 171         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 172                 goto out;
 173
 174         help = nfct_help(ct);
 175         if (!help || !help->helper)
 176                 goto out;
 177
 178         protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
 179                                          (*pskb)->len - extoff);
 180         if (protoff < 0 || protoff > (*pskb)->len ||
 181             pnum == NEXTHDR_FRAGMENT) {
 182                 DEBUGP("proto header not found\n");
 183                 return NF_ACCEPT;
 184         }
 185
 186         ret = help->helper->help(pskb, protoff, ct, ctinfo);
 187         if (ret != NF_ACCEPT)
 188                 return ret;
 189 out:
 190         /* We've seen it coming out the other side: confirm it */
 191         return nf_conntrack_confirm(pskb);
 192 }
 193
 194 static unsigned int ipv6_defrag(unsigned int hooknum,
 195                                 struct sk_buff **pskb,
 196                                 const struct net_device *in,
 197                                 const struct net_device *out,
 198                                 int (*okfn)(struct sk_buff *))
 199 {
 200         struct sk_buff *reasm;
 201
 202         /* Previously seen (loopback)?  */
 203         if ((*pskb)->nfct)
 204                 return NF_ACCEPT;
 205
 206         reasm = nf_ct_frag6_gather(*pskb);
 207
 208         /* queued */
 209         if (reasm == NULL)
 210                 return NF_STOLEN;
 211
 212         /* error occured or not fragmented */
 213         if (reasm == *pskb)
 214                 return NF_ACCEPT;
 215
 216         nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
 217                            (struct net_device *)out, okfn);
 218
 219         return NF_STOLEN;
 220 }
 221
 222 static unsigned int ipv6_conntrack_in(unsigned int hooknum,
 223                                       struct sk_buff **pskb,
 224                                       const struct net_device *in,
 225                                       const struct net_device *out,
 226                                       int (*okfn)(struct sk_buff *))
 227 {
 228         struct sk_buff *reasm = (*pskb)->nfct_reasm;
 229
 230         /* This packet is fragmented and has reassembled packet. */
 231         if (reasm) {
 232                 /* Reassembled packet isn't parsed yet ? */
 233                 if (!reasm->nfct) {
 234                         unsigned int ret;
 235
 236                         ret = nf_conntrack_in(PF_INET6, hooknum, &reasm);
 237                         if (ret != NF_ACCEPT)
 238                                 return ret;
 239                 }
 240                 nf_conntrack_get(reasm->nfct);
 241                 (*pskb)->nfct = reasm->nfct;
 242                 (*pskb)->nfctinfo = reasm->nfctinfo;
 243                 return NF_ACCEPT;
 244         }
 245
 246         return nf_conntrack_in(PF_INET6, hooknum, pskb);
 247 }
 248
 249 static unsigned int ipv6_conntrack_local(unsigned int hooknum,
 250                                          struct sk_buff **pskb,
 251                                          const struct net_device *in,
 252                                          const struct net_device *out,
 253                                          int (*okfn)(struct sk_buff *))
 254 {
 255         /* root is playing with raw sockets. */
 256         if ((*pskb)->len < sizeof(struct ipv6hdr)) {
 257                 if (net_ratelimit())
 258                         printk("ipv6_conntrack_local: packet too short\n");
 259                 return NF_ACCEPT;
 260         }
 261         return ipv6_conntrack_in(hooknum, pskb, in, out, okfn);
 262 }
 263
 264 static struct nf_hook_ops ipv6_conntrack_ops[] = {
 265         {
 266                 .hook           = ipv6_defrag,
 267                 .owner          = THIS_MODULE,
 268                 .pf             = PF_INET6,
 269                 .hooknum        = NF_IP6_PRE_ROUTING,
 270                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 271         },
 272         {
 273                 .hook           = ipv6_conntrack_in,
 274                 .owner          = THIS_MODULE,
 275                 .pf             = PF_INET6,
 276                 .hooknum        = NF_IP6_PRE_ROUTING,
 277                 .priority       = NF_IP6_PRI_CONNTRACK,
 278         },
 279         {
 280                 .hook           = ipv6_conntrack_local,
 281                 .owner          = THIS_MODULE,
 282                 .pf             = PF_INET6,
 283                 .hooknum        = NF_IP6_LOCAL_OUT,
 284                 .priority       = NF_IP6_PRI_CONNTRACK,
 285         },
 286         {
 287                 .hook           = ipv6_defrag,
 288                 .owner          = THIS_MODULE,
 289                 .pf             = PF_INET6,
 290                 .hooknum        = NF_IP6_LOCAL_OUT,
 291                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
 292         },
 293         {
 294                 .hook           = ipv6_confirm,
 295                 .owner          = THIS_MODULE,
 296                 .pf             = PF_INET6,
 297                 .hooknum        = NF_IP6_POST_ROUTING,
 298                 .priority       = NF_IP6_PRI_LAST,
 299         },
 300         {
 301                 .hook           = ipv6_confirm,
 302                 .owner          = THIS_MODULE,
 303                 .pf             = PF_INET6,
 304                 .hooknum        = NF_IP6_LOCAL_IN,
 305                 .priority       = NF_IP6_PRI_LAST-1,
 306         },
 307 };
 308
 309 #ifdef CONFIG_SYSCTL
 310 static ctl_table nf_ct_ipv6_sysctl_table[] = {
 311         {
 312                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_TIMEOUT,
 313                 .procname       = "nf_conntrack_frag6_timeout",
 314                 .data           = &nf_ct_frag6_timeout,
 315                 .maxlen         = sizeof(unsigned int),
 316                 .mode           = 0644,
 317                 .proc_handler   = &proc_dointvec_jiffies,
 318         },
 319         {
 320                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
 321                 .procname       = "nf_conntrack_frag6_low_thresh",
 322                 .data           = &nf_ct_frag6_low_thresh,
 323                 .maxlen         = sizeof(unsigned int),
 324                 .mode           = 0644,
 325                 .proc_handler   = &proc_dointvec,
 326         },
 327         {
 328                 .ctl_name       = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
 329                 .procname       = "nf_conntrack_frag6_high_thresh",
 330                 .data           = &nf_ct_frag6_high_thresh,
 331                 .maxlen         = sizeof(unsigned int),
 332                 .mode           = 0644,
 333                 .proc_handler   = &proc_dointvec,
 334         },
 335         { .ctl_name = 0 }
 336 };
 337 #endif
 338
 339 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 340
 341 #include <linux/netfilter/nfnetlink.h>
 342 #include <linux/netfilter/nfnetlink_conntrack.h>
 343
 344 static int ipv6_tuple_to_nfattr(struct sk_buff *skb,
 345                                 const struct nf_conntrack_tuple *tuple)
 346 {
 347         NFA_PUT(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
 348                 &tuple->src.u3.ip6);
 349         NFA_PUT(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
 350                 &tuple->dst.u3.ip6);
 351         return 0;
 352
 353 nfattr_failure:
 354         return -1;
 355 }
 356
 357 static const size_t cta_min_ip[CTA_IP_MAX] = {
 358         [CTA_IP_V6_SRC-1]       = sizeof(u_int32_t)*4,
 359         [CTA_IP_V6_DST-1]       = sizeof(u_int32_t)*4,
 360 };
 361
 362 static int ipv6_nfattr_to_tuple(struct nfattr *tb[],
 363                                 struct nf_conntrack_tuple *t)
 364 {
 365         if (!tb[CTA_IP_V6_SRC-1] || !tb[CTA_IP_V6_DST-1])
 366                 return -EINVAL;
 367
 368         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 369                 return -EINVAL;
 370
 371         memcpy(&t->src.u3.ip6, NFA_DATA(tb[CTA_IP_V6_SRC-1]),
 372                sizeof(u_int32_t) * 4);
 373         memcpy(&t->dst.u3.ip6, NFA_DATA(tb[CTA_IP_V6_DST-1]),
 374                sizeof(u_int32_t) * 4);
 375
 376         return 0;
 377 }
 378 #endif
 379
 380 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
 381         .l3proto                = PF_INET6,
 382         .name                   = "ipv6",
 383         .pkt_to_tuple           = ipv6_pkt_to_tuple,
 384         .invert_tuple           = ipv6_invert_tuple,
 385         .print_tuple            = ipv6_print_tuple,
 386         .print_conntrack        = ipv6_print_conntrack,
 387         .prepare                = ipv6_prepare,
 388 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 389         .tuple_to_nfattr        = ipv6_tuple_to_nfattr,
 390         .nfattr_to_tuple        = ipv6_nfattr_to_tuple,
 391 #endif
 392 #ifdef CONFIG_SYSCTL
 393         .ctl_table_path         = nf_net_netfilter_sysctl_path,
 394         .ctl_table              = nf_ct_ipv6_sysctl_table,
 395 #endif
 396         .get_features           = ipv6_get_features,
 397         .me                     = THIS_MODULE,
 398 };
 399
 400 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
 401 MODULE_LICENSE("GPL");
 402 MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");
 403
 404 static int __init nf_conntrack_l3proto_ipv6_init(void)
 405 {
 406         int ret = 0;
 407
 408         need_conntrack();
 409
 410         ret = nf_ct_frag6_init();
 411         if (ret < 0) {
 412                 printk("nf_conntrack_ipv6: can't initialize frag6.\n");
 413                 return ret;
 414         }
 415         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp6);
 416         if (ret < 0) {
 417                 printk("nf_conntrack_ipv6: can't register tcp.\n");
 418                 goto cleanup_frag6;
 419         }
 420
 421         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp6);
 422         if (ret < 0) {
 423                 printk("nf_conntrack_ipv6: can't register udp.\n");
 424                 goto cleanup_tcp;
 425         }
 426
 427         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmpv6);
 428         if (ret < 0) {
 429                 printk("nf_conntrack_ipv6: can't register icmpv6.\n");
 430                 goto cleanup_udp;
 431         }
 432
 433         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv6);
 434         if (ret < 0) {
 435                 printk("nf_conntrack_ipv6: can't register ipv6\n");
 436                 goto cleanup_icmpv6;
 437         }
 438
 439         ret = nf_register_hooks(ipv6_conntrack_ops,
 440                                 ARRAY_SIZE(ipv6_conntrack_ops));
 441         if (ret < 0) {
 442                 printk("nf_conntrack_ipv6: can't register pre-routing defrag "
 443                        "hook.\n");
 444                 goto cleanup_ipv6;
 445         }
 446         return ret;
 447
 448  cleanup_ipv6:
 449         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 450  cleanup_icmpv6:
 451         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 452  cleanup_udp:
 453         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 454  cleanup_tcp:
 455         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 456  cleanup_frag6:
 457         nf_ct_frag6_cleanup();
 458         return ret;
 459 }
 460
 461 static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 462 {
 463         synchronize_net();
 464         nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 465         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 466         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 467         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 468         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 469         nf_ct_frag6_cleanup();
 470 }
 471
 472 module_init(nf_conntrack_l3proto_ipv6_init);
 473 module_exit(nf_conntrack_l3proto_ipv6_fini);