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