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
 159         nexthdr = *skb_mac_header(skb);
 160         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
 161
 162         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 163         dstopt->nexthdr = nexthdr;
 164
 165         hao = mip6_padn((char *)(dstopt + 1),
 166                         calc_padlen(sizeof(*dstopt), 6));
 167
 168         hao->type = IPV6_TLV_HAO;
 169         hao->length = sizeof(*hao) - 2;
 170         BUG_TRAP(hao->length == 16);
 171
 172         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 173
 174         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 175         spin_lock_bh(&x->lock);
 176         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 177         spin_unlock_bh(&x->lock);
 178
 179         BUG_TRAP(len == x->props.header_len);
 180         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 181
 182         return 0;
 183 }
 184
 185 static inline int mip6_report_rl_allow(struct timeval *stamp,
 186                                        struct in6_addr *dst,
 187                                        struct in6_addr *src, int iif)
 188 {
 189         int allow = 0;
 190
 191         spin_lock_bh(&mip6_report_rl.lock);
 192         if (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_equal(&mip6_report_rl.src, src) ||
 196             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 197                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 198                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 199                 mip6_report_rl.iif = iif;
 200                 ipv6_addr_copy(&mip6_report_rl.src, src);
 201                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 202                 allow = 1;
 203         }
 204         spin_unlock_bh(&mip6_report_rl.lock);
 205         return allow;
 206 }
 207
 208 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 209 {
 210         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 211         struct ipv6_destopt_hao *hao = NULL;
 212         struct xfrm_selector sel;
 213         int offset;
 214         struct timeval stamp;
 215         int err = 0;
 216
 217         if (unlikely(fl->proto == IPPROTO_MH &&
 218                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 219                 goto out;
 220
 221         if (likely(opt->dsthao)) {
 222                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 223                 if (likely(offset >= 0))
 224                         hao = (struct ipv6_destopt_hao *)
 225                                         (skb_network_header(skb) + offset);
 226         }
 227
 228         skb_get_timestamp(skb, &stamp);
 229
 230         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 231                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 232                                   opt->iif))
 233                 goto out;
 234
 235         memset(&sel, 0, sizeof(sel));
 236         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 237                sizeof(sel.daddr));
 238         sel.prefixlen_d = 128;
 239         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 240                sizeof(sel.saddr));
 241         sel.prefixlen_s = 128;
 242         sel.family = AF_INET6;
 243         sel.proto = fl->proto;
 244         sel.dport = xfrm_flowi_dport(fl);
 245         if (sel.dport)
 246                 sel.dport_mask = htons(~0);
 247         sel.sport = xfrm_flowi_sport(fl);
 248         if (sel.sport)
 249                 sel.sport_mask = htons(~0);
 250         sel.ifindex = fl->oif;
 251
 252         err = km_report(IPPROTO_DSTOPTS, &sel,
 253                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 254
 255  out:
 256         return err;
 257 }
 258
 259 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 260                                u8 **nexthdr)
 261 {
 262         u16 offset = sizeof(struct ipv6hdr);
 263         struct ipv6_opt_hdr *exthdr =
 264                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 265         const unsigned char *nh = skb_network_header(skb);
 266         unsigned int packet_len = skb->tail - skb->network_header;
 267         int found_rhdr = 0;
 268
 269         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 270
 271         while (offset + 1 <= packet_len) {
 272
 273                 switch (**nexthdr) {
 274                 case NEXTHDR_HOP:
 275                         break;
 276                 case NEXTHDR_ROUTING:
 277                         found_rhdr = 1;
 278                         break;
 279                 case NEXTHDR_DEST:
 280                         /*
 281                          * HAO MUST NOT appear more than once.
 282                          * XXX: It is better to try to find by the end of
 283                          * XXX: packet if HAO exists.
 284                          */
 285                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 286                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 287                                 return offset;
 288                         }
 289
 290                         if (found_rhdr)
 291                                 return offset;
 292
 293                         break;
 294                 default:
 295                         return offset;
 296                 }
 297
 298                 offset += ipv6_optlen(exthdr);
 299                 *nexthdr = &exthdr->nexthdr;
 300                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 301         }
 302
 303         return offset;
 304 }
 305
 306 static int mip6_destopt_init_state(struct xfrm_state *x)
 307 {
 308         if (x->id.spi) {
 309                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 310                        x->id.spi);
 311                 return -EINVAL;
 312         }
 313         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 314                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 315                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 316                 return -EINVAL;
 317         }
 318
 319         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 320                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 321                 sizeof(struct ipv6_destopt_hao);
 322         BUG_TRAP(x->props.header_len == 24);
 323
 324         return 0;
 325 }
 326
 327 /*
 328  * Do nothing about destroying since it has no specific operation for
 329  * destination options header unlike IPsec protocols.
 330  */
 331 static void mip6_destopt_destroy(struct xfrm_state *x)
 332 {
 333 }
 334
 335 static struct xfrm_type mip6_destopt_type =
 336 {
 337         .description    = "MIP6DESTOPT",
 338         .owner          = THIS_MODULE,
 339         .proto          = IPPROTO_DSTOPTS,
 340         .flags          = XFRM_TYPE_NON_FRAGMENT,
 341         .init_state     = mip6_destopt_init_state,
 342         .destructor     = mip6_destopt_destroy,
 343         .input          = mip6_destopt_input,
 344         .output         = mip6_destopt_output,
 345         .reject         = mip6_destopt_reject,
 346         .hdr_offset     = mip6_destopt_offset,
 347         .local_addr     = mip6_xfrm_addr,
 348 };
 349
 350 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 351 {
 352         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 353
 354         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 355             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 356                 return -ENOENT;
 357
 358         return rt2->rt_hdr.nexthdr;
 359 }
 360
 361 /* Routing Header type 2 is inserted.
 362  * IP Header's dst address is replaced with Routing Header's Home Address.
 363  */
 364 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 365 {
 366         struct ipv6hdr *iph;
 367         struct rt2_hdr *rt2;
 368         u8 nexthdr;
 369
 370         skb_push(skb, -skb_network_offset(skb));
 371         iph = ipv6_hdr(skb);
 372
 373         nexthdr = *skb_mac_header(skb);
 374         *skb_mac_header(skb) = IPPROTO_ROUTING;
 375
 376         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 377         rt2->rt_hdr.nexthdr = nexthdr;
 378         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 379         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 380         rt2->rt_hdr.segments_left = 1;
 381         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 382
 383         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 384
 385         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 386         spin_lock_bh(&x->lock);
 387         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 388         spin_unlock_bh(&x->lock);
 389
 390         return 0;
 391 }
 392
 393 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 394                              u8 **nexthdr)
 395 {
 396         u16 offset = sizeof(struct ipv6hdr);
 397         struct ipv6_opt_hdr *exthdr =
 398                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 399         const unsigned char *nh = skb_network_header(skb);
 400         unsigned int packet_len = skb->tail - skb->network_header;
 401         int found_rhdr = 0;
 402
 403         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 404
 405         while (offset + 1 <= packet_len) {
 406
 407                 switch (**nexthdr) {
 408                 case NEXTHDR_HOP:
 409                         break;
 410                 case NEXTHDR_ROUTING:
 411                         if (offset + 3 <= packet_len) {
 412                                 struct ipv6_rt_hdr *rt;
 413                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 414                                 if (rt->type != 0)
 415                                         return offset;
 416                         }
 417                         found_rhdr = 1;
 418                         break;
 419                 case NEXTHDR_DEST:
 420                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 421                                 return offset;
 422
 423                         if (found_rhdr)
 424                                 return offset;
 425
 426                         break;
 427                 default:
 428                         return offset;
 429                 }
 430
 431                 offset += ipv6_optlen(exthdr);
 432                 *nexthdr = &exthdr->nexthdr;
 433                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 434         }
 435
 436         return offset;
 437 }
 438
 439 static int mip6_rthdr_init_state(struct xfrm_state *x)
 440 {
 441         if (x->id.spi) {
 442                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 443                        x->id.spi);
 444                 return -EINVAL;
 445         }
 446         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 447                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 448                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 449                 return -EINVAL;
 450         }
 451
 452         x->props.header_len = sizeof(struct rt2_hdr);
 453
 454         return 0;
 455 }
 456
 457 /*
 458  * Do nothing about destroying since it has no specific operation for routing
 459  * header type 2 unlike IPsec protocols.
 460  */
 461 static void mip6_rthdr_destroy(struct xfrm_state *x)
 462 {
 463 }
 464
 465 static struct xfrm_type mip6_rthdr_type =
 466 {
 467         .description    = "MIP6RT",
 468         .owner          = THIS_MODULE,
 469         .proto          = IPPROTO_ROUTING,
 470         .flags          = XFRM_TYPE_NON_FRAGMENT,
 471         .init_state     = mip6_rthdr_init_state,
 472         .destructor     = mip6_rthdr_destroy,
 473         .input          = mip6_rthdr_input,
 474         .output         = mip6_rthdr_output,
 475         .hdr_offset     = mip6_rthdr_offset,
 476         .remote_addr    = mip6_xfrm_addr,
 477 };
 478
 479 static int __init mip6_init(void)
 480 {
 481         printk(KERN_INFO "Mobile IPv6\n");
 482
 483         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 484                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 485                 goto mip6_destopt_xfrm_fail;
 486         }
 487         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 488                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 489                 goto mip6_rthdr_xfrm_fail;
 490         }
 491         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 492                 printk(KERN_INFO "%s: can't add rawv6 mh filter\n", __FUNCTION__);
 493                 goto mip6_rawv6_mh_fail;
 494         }
 495
 496
 497         return 0;
 498
 499  mip6_rawv6_mh_fail:
 500         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 501  mip6_rthdr_xfrm_fail:
 502         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 503  mip6_destopt_xfrm_fail:
 504         return -EAGAIN;
 505 }
 506
 507 static void __exit mip6_fini(void)
 508 {
 509         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 510                 printk(KERN_INFO "%s: can't remove rawv6 mh filter\n", __FUNCTION__);
 511         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 512                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 513         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 514                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 515 }
 516
 517 module_init(mip6_init);
 518 module_exit(mip6_fini);
 519
 520 MODULE_LICENSE("GPL");
 521 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 522 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);