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         iph = (struct ipv6hdr *)skb->data;
 157         iph->payload_len = htons(skb->len - sizeof(*iph));
 158
 159         nexthdr = *skb_network_header(skb);
 160         *skb_network_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         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 176
 177         BUG_TRAP(len == x->props.header_len);
 178         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 179
 180         return 0;
 181 }
 182
 183 static inline int mip6_report_rl_allow(struct timeval *stamp,
 184                                        struct in6_addr *dst,
 185                                        struct in6_addr *src, int iif)
 186 {
 187         int allow = 0;
 188
 189         spin_lock_bh(&mip6_report_rl.lock);
 190         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 191             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 192             mip6_report_rl.iif != iif ||
 193             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 194             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 195                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 196                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 197                 mip6_report_rl.iif = iif;
 198                 ipv6_addr_copy(&mip6_report_rl.src, src);
 199                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 200                 allow = 1;
 201         }
 202         spin_unlock_bh(&mip6_report_rl.lock);
 203         return allow;
 204 }
 205
 206 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 207 {
 208         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 209         struct ipv6_destopt_hao *hao = NULL;
 210         struct xfrm_selector sel;
 211         int offset;
 212         struct timeval stamp;
 213         int err = 0;
 214
 215         if (unlikely(fl->proto == IPPROTO_MH &&
 216                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 217                 goto out;
 218
 219         if (likely(opt->dsthao)) {
 220                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 221                 if (likely(offset >= 0))
 222                         hao = (struct ipv6_destopt_hao *)
 223                                         (skb_network_header(skb) + offset);
 224         }
 225
 226         skb_get_timestamp(skb, &stamp);
 227
 228         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 229                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 230                                   opt->iif))
 231                 goto out;
 232
 233         memset(&sel, 0, sizeof(sel));
 234         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 235                sizeof(sel.daddr));
 236         sel.prefixlen_d = 128;
 237         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 238                sizeof(sel.saddr));
 239         sel.prefixlen_s = 128;
 240         sel.family = AF_INET6;
 241         sel.proto = fl->proto;
 242         sel.dport = xfrm_flowi_dport(fl);
 243         if (sel.dport)
 244                 sel.dport_mask = htons(~0);
 245         sel.sport = xfrm_flowi_sport(fl);
 246         if (sel.sport)
 247                 sel.sport_mask = htons(~0);
 248         sel.ifindex = fl->oif;
 249
 250         err = km_report(IPPROTO_DSTOPTS, &sel,
 251                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 252
 253  out:
 254         return err;
 255 }
 256
 257 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 258                                u8 **nexthdr)
 259 {
 260         u16 offset = sizeof(struct ipv6hdr);
 261         struct ipv6_opt_hdr *exthdr =
 262                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 263         const unsigned char *nh = skb_network_header(skb);
 264         unsigned int packet_len = skb->tail - skb->network_header;
 265         int found_rhdr = 0;
 266
 267         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 268
 269         while (offset + 1 <= packet_len) {
 270
 271                 switch (**nexthdr) {
 272                 case NEXTHDR_HOP:
 273                         break;
 274                 case NEXTHDR_ROUTING:
 275                         found_rhdr = 1;
 276                         break;
 277                 case NEXTHDR_DEST:
 278                         /*
 279                          * HAO MUST NOT appear more than once.
 280                          * XXX: It is better to try to find by the end of
 281                          * XXX: packet if HAO exists.
 282                          */
 283                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 284                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 285                                 return offset;
 286                         }
 287
 288                         if (found_rhdr)
 289                                 return offset;
 290
 291                         break;
 292                 default:
 293                         return offset;
 294                 }
 295
 296                 offset += ipv6_optlen(exthdr);
 297                 *nexthdr = &exthdr->nexthdr;
 298                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 299         }
 300
 301         return offset;
 302 }
 303
 304 static int mip6_destopt_init_state(struct xfrm_state *x)
 305 {
 306         if (x->id.spi) {
 307                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 308                        x->id.spi);
 309                 return -EINVAL;
 310         }
 311         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 312                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 313                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 314                 return -EINVAL;
 315         }
 316
 317         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 318                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 319                 sizeof(struct ipv6_destopt_hao);
 320         BUG_TRAP(x->props.header_len == 24);
 321
 322         return 0;
 323 }
 324
 325 /*
 326  * Do nothing about destroying since it has no specific operation for
 327  * destination options header unlike IPsec protocols.
 328  */
 329 static void mip6_destopt_destroy(struct xfrm_state *x)
 330 {
 331 }
 332
 333 static struct xfrm_type mip6_destopt_type =
 334 {
 335         .description    = "MIP6DESTOPT",
 336         .owner          = THIS_MODULE,
 337         .proto          = IPPROTO_DSTOPTS,
 338         .flags          = XFRM_TYPE_NON_FRAGMENT,
 339         .init_state     = mip6_destopt_init_state,
 340         .destructor     = mip6_destopt_destroy,
 341         .input          = mip6_destopt_input,
 342         .output         = mip6_destopt_output,
 343         .reject         = mip6_destopt_reject,
 344         .hdr_offset     = mip6_destopt_offset,
 345         .local_addr     = mip6_xfrm_addr,
 346 };
 347
 348 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 349 {
 350         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 351
 352         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 353             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 354                 return -ENOENT;
 355
 356         return rt2->rt_hdr.nexthdr;
 357 }
 358
 359 /* Routing Header type 2 is inserted.
 360  * IP Header's dst address is replaced with Routing Header's Home Address.
 361  */
 362 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 363 {
 364         struct ipv6hdr *iph;
 365         struct rt2_hdr *rt2;
 366         u8 nexthdr;
 367
 368         iph = (struct ipv6hdr *)skb->data;
 369         iph->payload_len = htons(skb->len - sizeof(*iph));
 370
 371         nexthdr = *skb_network_header(skb);
 372         *skb_network_header(skb) = IPPROTO_ROUTING;
 373
 374         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 375         rt2->rt_hdr.nexthdr = nexthdr;
 376         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 377         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 378         rt2->rt_hdr.segments_left = 1;
 379         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 380
 381         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 382
 383         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 384         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 385
 386         return 0;
 387 }
 388
 389 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 390                              u8 **nexthdr)
 391 {
 392         u16 offset = sizeof(struct ipv6hdr);
 393         struct ipv6_opt_hdr *exthdr =
 394                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 395         const unsigned char *nh = skb_network_header(skb);
 396         unsigned int packet_len = skb->tail - skb->network_header;
 397         int found_rhdr = 0;
 398
 399         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 400
 401         while (offset + 1 <= packet_len) {
 402
 403                 switch (**nexthdr) {
 404                 case NEXTHDR_HOP:
 405                         break;
 406                 case NEXTHDR_ROUTING:
 407                         if (offset + 3 <= packet_len) {
 408                                 struct ipv6_rt_hdr *rt;
 409                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 410                                 if (rt->type != 0)
 411                                         return offset;
 412                         }
 413                         found_rhdr = 1;
 414                         break;
 415                 case NEXTHDR_DEST:
 416                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 417                                 return offset;
 418
 419                         if (found_rhdr)
 420                                 return offset;
 421
 422                         break;
 423                 default:
 424                         return offset;
 425                 }
 426
 427                 offset += ipv6_optlen(exthdr);
 428                 *nexthdr = &exthdr->nexthdr;
 429                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 430         }
 431
 432         return offset;
 433 }
 434
 435 static int mip6_rthdr_init_state(struct xfrm_state *x)
 436 {
 437         if (x->id.spi) {
 438                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 439                        x->id.spi);
 440                 return -EINVAL;
 441         }
 442         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 443                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 444                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 445                 return -EINVAL;
 446         }
 447
 448         x->props.header_len = sizeof(struct rt2_hdr);
 449
 450         return 0;
 451 }
 452
 453 /*
 454  * Do nothing about destroying since it has no specific operation for routing
 455  * header type 2 unlike IPsec protocols.
 456  */
 457 static void mip6_rthdr_destroy(struct xfrm_state *x)
 458 {
 459 }
 460
 461 static struct xfrm_type mip6_rthdr_type =
 462 {
 463         .description    = "MIP6RT",
 464         .owner          = THIS_MODULE,
 465         .proto          = IPPROTO_ROUTING,
 466         .flags          = XFRM_TYPE_NON_FRAGMENT,
 467         .init_state     = mip6_rthdr_init_state,
 468         .destructor     = mip6_rthdr_destroy,
 469         .input          = mip6_rthdr_input,
 470         .output         = mip6_rthdr_output,
 471         .hdr_offset     = mip6_rthdr_offset,
 472         .remote_addr    = mip6_xfrm_addr,
 473 };
 474
 475 static int __init mip6_init(void)
 476 {
 477         printk(KERN_INFO "Mobile IPv6\n");
 478
 479         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 480                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 481                 goto mip6_destopt_xfrm_fail;
 482         }
 483         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 484                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 485                 goto mip6_rthdr_xfrm_fail;
 486         }
 487         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 488                 printk(KERN_INFO "%s: can't add rawv6 mh filter\n", __FUNCTION__);
 489                 goto mip6_rawv6_mh_fail;
 490         }
 491
 492
 493         return 0;
 494
 495  mip6_rawv6_mh_fail:
 496         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 497  mip6_rthdr_xfrm_fail:
 498         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 499  mip6_destopt_xfrm_fail:
 500         return -EAGAIN;
 501 }
 502
 503 static void __exit mip6_fini(void)
 504 {
 505         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 506                 printk(KERN_INFO "%s: can't remove rawv6 mh filter\n", __FUNCTION__);
 507         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 508                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 509         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 510                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 511 }
 512
 513 module_init(mip6_init);
 514 module_exit(mip6_fini);
 515
 516 MODULE_LICENSE("GPL");
 517 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 518 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);