net/ipv6/mip6.c

   1 /*
   2  * Copyright (C)2003-2006 Helsinki University of Technology
   3  * Copyright (C)2003-2006 USAGI/WIDE Project
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 /*
  20  * Authors:
  21  *      Noriaki TAKAMIYA @USAGI
  22  *      Masahide NAKAMURA @USAGI
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/time.h>
  28 #include <linux/ipv6.h>
  29 #include <linux/icmpv6.h>
  30 #include <net/sock.h>
  31 #include <net/ipv6.h>
  32 #include <net/ip6_checksum.h>
  33 #include <net/rawv6.h>
  34 #include <net/xfrm.h>
  35 #include <net/mip6.h>
  36
  37 static xfrm_address_t *mip6_xfrm_addr(struct xfrm_state *x, xfrm_address_t *addr)
  38 {
  39         return x->coaddr;
  40 }
  41
  42 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  43 {
  44         return (n - len + 16) & 0x7;
  45 }
  46
  47 static inline void *mip6_padn(__u8 *data, __u8 padlen)
  48 {
  49         if (!data)
  50                 return NULL;
  51         if (padlen == 1) {
  52                 data[0] = MIP6_OPT_PAD_1;
  53         } else if (padlen > 1) {
  54                 data[0] = MIP6_OPT_PAD_N;
  55                 data[1] = padlen - 2;
  56                 if (padlen > 2)
  57                         memset(data+2, 0, data[1]);
  58         }
  59         return data + padlen;
  60 }
  61
  62 static inline void mip6_param_prob(struct sk_buff *skb, int code, int pos)
  63 {
  64         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
  65 }
  66
  67 static int mip6_mh_len(int type)
  68 {
  69         int len = 0;
  70
  71         switch (type) {
  72         case IP6_MH_TYPE_BRR:
  73                 len = 0;
  74                 break;
  75         case IP6_MH_TYPE_HOTI:
  76         case IP6_MH_TYPE_COTI:
  77         case IP6_MH_TYPE_BU:
  78         case IP6_MH_TYPE_BACK:
  79                 len = 1;
  80                 break;
  81         case IP6_MH_TYPE_HOT:
  82         case IP6_MH_TYPE_COT:
  83         case IP6_MH_TYPE_BERROR:
  84                 len = 2;
  85                 break;
  86         }
  87         return len;
  88 }
  89
  90 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  91 {
  92         struct ip6_mh *mh;
  93
  94         if (!pskb_may_pull(skb, (skb_transport_offset(skb)) + 8) ||
  95             !pskb_may_pull(skb, (skb_transport_offset(skb) +
  96                                  ((skb_transport_header(skb)[1] + 1) << 3))))
  97                 return -1;
  98
  99         mh = (struct ip6_mh *)skb_transport_header(skb);
 100
 101         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
 102                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
 103                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
 104                 mip6_param_prob(skb, 0, ((&mh->ip6mh_hdrlen) -
 105                                          skb_network_header(skb)));
 106                 return -1;
 107         }
 108
 109         if (mh->ip6mh_proto != IPPROTO_NONE) {
 110                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
 111                                mh->ip6mh_proto);
 112                 mip6_param_prob(skb, 0, ((&mh->ip6mh_proto) -
 113                                          skb_network_header(skb)));
 114                 return -1;
 115         }
 116
 117         return 0;
 118 }
 119
 120 struct mip6_report_rate_limiter {
 121         spinlock_t lock;
 122         struct timeval stamp;
 123         int iif;
 124         struct in6_addr src;
 125         struct in6_addr dst;
 126 };
 127
 128 static struct mip6_report_rate_limiter mip6_report_rl = {
 129         .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
 130 };
 131
 132 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 133 {
 134         struct ipv6hdr *iph = ipv6_hdr(skb);
 135         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 136
 137         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 138             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 139                 return -ENOENT;
 140
 141         return destopt->nexthdr;
 142 }
 143
 144 /* Destination Option Header is inserted.
 145  * IP Header's src address is replaced with Home Address Option in
 146  * Destination Option Header.
 147  */
 148 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 149 {
 150         struct ipv6hdr *iph;
 151         struct ipv6_destopt_hdr *dstopt;
 152         struct ipv6_destopt_hao *hao;
 153         u8 nexthdr;
 154         int len;
 155
 156         skb_push(skb, -skb_network_offset(skb));
 157         iph = ipv6_hdr(skb);
 158         iph->payload_len = htons(skb->len - sizeof(*iph));
 159
 160         nexthdr = *skb_mac_header(skb);
 161         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
 162
 163         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 164         dstopt->nexthdr = nexthdr;
 165
 166         hao = mip6_padn((char *)(dstopt + 1),
 167                         calc_padlen(sizeof(*dstopt), 6));
 168
 169         hao->type = IPV6_TLV_HAO;
 170         hao->length = sizeof(*hao) - 2;
 171         BUG_TRAP(hao->length == 16);
 172
 173         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 174
 175         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 176         spin_lock_bh(&x->lock);
 177         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 178         spin_unlock_bh(&x->lock);
 179
 180         BUG_TRAP(len == x->props.header_len);
 181         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 182
 183         return 0;
 184 }
 185
 186 static inline int mip6_report_rl_allow(struct timeval *stamp,
 187                                        struct in6_addr *dst,
 188                                        struct in6_addr *src, int iif)
 189 {
 190         int allow = 0;
 191
 192         spin_lock_bh(&mip6_report_rl.lock);
 193         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 194             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 195             mip6_report_rl.iif != iif ||
 196             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 197             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 198                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 199                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 200                 mip6_report_rl.iif = iif;
 201                 ipv6_addr_copy(&mip6_report_rl.src, src);
 202                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 203                 allow = 1;
 204         }
 205         spin_unlock_bh(&mip6_report_rl.lock);
 206         return allow;
 207 }
 208
 209 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 210 {
 211         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 212         struct ipv6_destopt_hao *hao = NULL;
 213         struct xfrm_selector sel;
 214         int offset;
 215         struct timeval stamp;
 216         int err = 0;
 217
 218         if (unlikely(fl->proto == IPPROTO_MH &&
 219                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 220                 goto out;
 221
 222         if (likely(opt->dsthao)) {
 223                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 224                 if (likely(offset >= 0))
 225                         hao = (struct ipv6_destopt_hao *)
 226                                         (skb_network_header(skb) + offset);
 227         }
 228
 229         skb_get_timestamp(skb, &stamp);
 230
 231         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 232                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 233                                   opt->iif))
 234                 goto out;
 235
 236         memset(&sel, 0, sizeof(sel));
 237         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 238                sizeof(sel.daddr));
 239         sel.prefixlen_d = 128;
 240         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 241                sizeof(sel.saddr));
 242         sel.prefixlen_s = 128;
 243         sel.family = AF_INET6;
 244         sel.proto = fl->proto;
 245         sel.dport = xfrm_flowi_dport(fl);
 246         if (sel.dport)
 247                 sel.dport_mask = htons(~0);
 248         sel.sport = xfrm_flowi_sport(fl);
 249         if (sel.sport)
 250                 sel.sport_mask = htons(~0);
 251         sel.ifindex = fl->oif;
 252
 253         err = km_report(IPPROTO_DSTOPTS, &sel,
 254                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 255
 256  out:
 257         return err;
 258 }
 259
 260 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 261                                u8 **nexthdr)
 262 {
 263         u16 offset = sizeof(struct ipv6hdr);
 264         struct ipv6_opt_hdr *exthdr =
 265                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 266         const unsigned char *nh = skb_network_header(skb);
 267         unsigned int packet_len = skb->tail - skb->network_header;
 268         int found_rhdr = 0;
 269
 270         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 271
 272         while (offset + 1 <= packet_len) {
 273
 274                 switch (**nexthdr) {
 275                 case NEXTHDR_HOP:
 276                         break;
 277                 case NEXTHDR_ROUTING:
 278                         found_rhdr = 1;
 279                         break;
 280                 case NEXTHDR_DEST:
 281                         /*
 282                          * HAO MUST NOT appear more than once.
 283                          * XXX: It is better to try to find by the end of
 284                          * XXX: packet if HAO exists.
 285                          */
 286                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 287                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 288                                 return offset;
 289                         }
 290
 291                         if (found_rhdr)
 292                                 return offset;
 293
 294                         break;
 295                 default:
 296                         return offset;
 297                 }
 298
 299                 offset += ipv6_optlen(exthdr);
 300                 *nexthdr = &exthdr->nexthdr;
 301                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 302         }
 303
 304         return offset;
 305 }
 306
 307 static int mip6_destopt_init_state(struct xfrm_state *x)
 308 {
 309         if (x->id.spi) {
 310                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 311                        x->id.spi);
 312                 return -EINVAL;
 313         }
 314         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 315                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 316                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 317                 return -EINVAL;
 318         }
 319
 320         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 321                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 322                 sizeof(struct ipv6_destopt_hao);
 323         BUG_TRAP(x->props.header_len == 24);
 324
 325         return 0;
 326 }
 327
 328 /*
 329  * Do nothing about destroying since it has no specific operation for
 330  * destination options header unlike IPsec protocols.
 331  */
 332 static void mip6_destopt_destroy(struct xfrm_state *x)
 333 {
 334 }
 335
 336 static struct xfrm_type mip6_destopt_type =
 337 {
 338         .description    = "MIP6DESTOPT",
 339         .owner          = THIS_MODULE,
 340         .proto          = IPPROTO_DSTOPTS,
 341         .flags          = XFRM_TYPE_NON_FRAGMENT,
 342         .init_state     = mip6_destopt_init_state,
 343         .destructor     = mip6_destopt_destroy,
 344         .input          = mip6_destopt_input,
 345         .output         = mip6_destopt_output,
 346         .reject         = mip6_destopt_reject,
 347         .hdr_offset     = mip6_destopt_offset,
 348         .local_addr     = mip6_xfrm_addr,
 349 };
 350
 351 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 352 {
 353         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 354
 355         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 356             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 357                 return -ENOENT;
 358
 359         return rt2->rt_hdr.nexthdr;
 360 }
 361
 362 /* Routing Header type 2 is inserted.
 363  * IP Header's dst address is replaced with Routing Header's Home Address.
 364  */
 365 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 366 {
 367         struct ipv6hdr *iph;
 368         struct rt2_hdr *rt2;
 369         u8 nexthdr;
 370
 371         skb_push(skb, -skb_network_offset(skb));
 372         iph = ipv6_hdr(skb);
 373         iph->payload_len = htons(skb->len - sizeof(*iph));
 374
 375         nexthdr = *skb_mac_header(skb);
 376         *skb_mac_header(skb) = IPPROTO_ROUTING;
 377
 378         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 379         rt2->rt_hdr.nexthdr = nexthdr;
 380         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 381         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 382         rt2->rt_hdr.segments_left = 1;
 383         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 384
 385         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 386
 387         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 388         spin_lock_bh(&x->lock);
 389         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 390         spin_unlock_bh(&x->lock);
 391
 392         return 0;
 393 }
 394
 395 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 396                              u8 **nexthdr)
 397 {
 398         u16 offset = sizeof(struct ipv6hdr);
 399         struct ipv6_opt_hdr *exthdr =
 400                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 401         const unsigned char *nh = skb_network_header(skb);
 402         unsigned int packet_len = skb->tail - skb->network_header;
 403         int found_rhdr = 0;
 404
 405         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 406
 407         while (offset + 1 <= packet_len) {
 408
 409                 switch (**nexthdr) {
 410                 case NEXTHDR_HOP:
 411                         break;
 412                 case NEXTHDR_ROUTING:
 413                         if (offset + 3 <= packet_len) {
 414                                 struct ipv6_rt_hdr *rt;
 415                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 416                                 if (rt->type != 0)
 417                                         return offset;
 418                         }
 419                         found_rhdr = 1;
 420                         break;
 421                 case NEXTHDR_DEST:
 422                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 423                                 return offset;
 424
 425                         if (found_rhdr)
 426                                 return offset;
 427
 428                         break;
 429                 default:
 430                         return offset;
 431                 }
 432
 433                 offset += ipv6_optlen(exthdr);
 434                 *nexthdr = &exthdr->nexthdr;
 435                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 436         }
 437
 438         return offset;
 439 }
 440
 441 static int mip6_rthdr_init_state(struct xfrm_state *x)
 442 {
 443         if (x->id.spi) {
 444                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 445                        x->id.spi);
 446                 return -EINVAL;
 447         }
 448         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 449                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 450                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 451                 return -EINVAL;
 452         }
 453
 454         x->props.header_len = sizeof(struct rt2_hdr);
 455
 456         return 0;
 457 }
 458
 459 /*
 460  * Do nothing about destroying since it has no specific operation for routing
 461  * header type 2 unlike IPsec protocols.
 462  */
 463 static void mip6_rthdr_destroy(struct xfrm_state *x)
 464 {
 465 }
 466
 467 static struct xfrm_type mip6_rthdr_type =
 468 {
 469         .description    = "MIP6RT",
 470         .owner          = THIS_MODULE,
 471         .proto          = IPPROTO_ROUTING,
 472         .flags          = XFRM_TYPE_NON_FRAGMENT,
 473         .init_state     = mip6_rthdr_init_state,
 474         .destructor     = mip6_rthdr_destroy,
 475         .input          = mip6_rthdr_input,
 476         .output         = mip6_rthdr_output,
 477         .hdr_offset     = mip6_rthdr_offset,
 478         .remote_addr    = mip6_xfrm_addr,
 479 };
 480
 481 static int __init mip6_init(void)
 482 {
 483         printk(KERN_INFO "Mobile IPv6\n");
 484
 485         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 486                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 487                 goto mip6_destopt_xfrm_fail;
 488         }
 489         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 490                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 491                 goto mip6_rthdr_xfrm_fail;
 492         }
 493         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 494                 printk(KERN_INFO "%s: can't add rawv6 mh filter\n", __FUNCTION__);
 495                 goto mip6_rawv6_mh_fail;
 496         }
 497
 498
 499         return 0;
 500
 501  mip6_rawv6_mh_fail:
 502         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 503  mip6_rthdr_xfrm_fail:
 504         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 505  mip6_destopt_xfrm_fail:
 506         return -EAGAIN;
 507 }
 508
 509 static void __exit mip6_fini(void)
 510 {
 511         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 512                 printk(KERN_INFO "%s: can't remove rawv6 mh filter\n", __FUNCTION__);
 513         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 514                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 515         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 516                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 517 }
 518
 519 module_init(mip6_init);
 520 module_exit(mip6_fini);
 521
 522 MODULE_LICENSE("GPL");
 523 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 524 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);