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