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/xfrm.h>
  34 #include <net/mip6.h>
  35
  36 static xfrm_address_t *mip6_xfrm_addr(struct xfrm_state *x, xfrm_address_t *addr)
  37 {
  38         return x->coaddr;
  39 }
  40
  41 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  42 {
  43         return (n - len + 16) & 0x7;
  44 }
  45
  46 static inline void *mip6_padn(__u8 *data, __u8 padlen)
  47 {
  48         if (!data)
  49                 return NULL;
  50         if (padlen == 1) {
  51                 data[0] = MIP6_OPT_PAD_1;
  52         } else if (padlen > 1) {
  53                 data[0] = MIP6_OPT_PAD_N;
  54                 data[1] = padlen - 2;
  55                 if (padlen > 2)
  56                         memset(data+2, 0, data[1]);
  57         }
  58         return data + padlen;
  59 }
  60
  61 static inline void mip6_param_prob(struct sk_buff *skb, int code, int pos)
  62 {
  63         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
  64 }
  65
  66 static int mip6_mh_len(int type)
  67 {
  68         int len = 0;
  69
  70         switch (type) {
  71         case IP6_MH_TYPE_BRR:
  72                 len = 0;
  73                 break;
  74         case IP6_MH_TYPE_HOTI:
  75         case IP6_MH_TYPE_COTI:
  76         case IP6_MH_TYPE_BU:
  77         case IP6_MH_TYPE_BACK:
  78                 len = 1;
  79                 break;
  80         case IP6_MH_TYPE_HOT:
  81         case IP6_MH_TYPE_COT:
  82         case IP6_MH_TYPE_BERROR:
  83                 len = 2;
  84                 break;
  85         }
  86         return len;
  87 }
  88
  89 int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  90 {
  91         struct ip6_mh *mh;
  92         int mhlen;
  93
  94         if (!pskb_may_pull(skb, (skb->h.raw - skb->data) + 8) ||
  95             !pskb_may_pull(skb, (skb->h.raw - skb->data) + ((skb->h.raw[1] + 1) << 3)))
  96                 return -1;
  97
  98         mh = (struct ip6_mh *)skb->h.raw;
  99
 100         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
 101                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
 102                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
 103                 mip6_param_prob(skb, 0, (&mh->ip6mh_hdrlen) - skb->nh.raw);
 104                 return -1;
 105         }
 106         mhlen = (mh->ip6mh_hdrlen + 1) << 3;
 107
 108         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 109                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 110                 if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
 111                                     &skb->nh.ipv6h->daddr,
 112                                     mhlen, IPPROTO_MH,
 113                                     skb->csum)) {
 114                         LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH hw checksum failed\n");
 115                         skb->ip_summed = CHECKSUM_NONE;
 116                 }
 117         }
 118         if (skb->ip_summed == CHECKSUM_NONE) {
 119                 if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
 120                                     &skb->nh.ipv6h->daddr,
 121                                     mhlen, IPPROTO_MH,
 122                                     skb_checksum(skb, 0, mhlen, 0))) {
 123                         LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH checksum failed "
 124                                        "[" NIP6_FMT " > " NIP6_FMT "]\n",
 125                                        NIP6(skb->nh.ipv6h->saddr),
 126                                        NIP6(skb->nh.ipv6h->daddr));
 127                         return -1;
 128                 }
 129                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 130         }
 131
 132         if (mh->ip6mh_proto != IPPROTO_NONE) {
 133                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
 134                                mh->ip6mh_proto);
 135                 mip6_param_prob(skb, 0, (&mh->ip6mh_proto) - skb->nh.raw);
 136                 return -1;
 137         }
 138
 139         return 0;
 140 }
 141
 142 struct mip6_report_rate_limiter {
 143         spinlock_t lock;
 144         struct timeval stamp;
 145         int iif;
 146         struct in6_addr src;
 147         struct in6_addr dst;
 148 };
 149
 150 static struct mip6_report_rate_limiter mip6_report_rl = {
 151         .lock = SPIN_LOCK_UNLOCKED
 152 };
 153
 154 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 155 {
 156         struct ipv6hdr *iph = skb->nh.ipv6h;
 157         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 158
 159         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 160             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 161                 return -ENOENT;
 162
 163         return destopt->nexthdr;
 164 }
 165
 166 /* Destination Option Header is inserted.
 167  * IP Header's src address is replaced with Home Address Option in
 168  * Destination Option Header.
 169  */
 170 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 171 {
 172         struct ipv6hdr *iph;
 173         struct ipv6_destopt_hdr *dstopt;
 174         struct ipv6_destopt_hao *hao;
 175         u8 nexthdr;
 176         int len;
 177
 178         iph = (struct ipv6hdr *)skb->data;
 179         iph->payload_len = htons(skb->len - sizeof(*iph));
 180
 181         nexthdr = *skb->nh.raw;
 182         *skb->nh.raw = IPPROTO_DSTOPTS;
 183
 184         dstopt = (struct ipv6_destopt_hdr *)skb->h.raw;
 185         dstopt->nexthdr = nexthdr;
 186
 187         hao = mip6_padn((char *)(dstopt + 1),
 188                         calc_padlen(sizeof(*dstopt), 6));
 189
 190         hao->type = IPV6_TLV_HAO;
 191         hao->length = sizeof(*hao) - 2;
 192         BUG_TRAP(hao->length == 16);
 193
 194         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 195
 196         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 197         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 198
 199         BUG_TRAP(len == x->props.header_len);
 200         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 201
 202         return 0;
 203 }
 204
 205 static inline int mip6_report_rl_allow(struct timeval *stamp,
 206                                        struct in6_addr *dst,
 207                                        struct in6_addr *src, int iif)
 208 {
 209         int allow = 0;
 210
 211         spin_lock_bh(&mip6_report_rl.lock);
 212         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 213             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 214             mip6_report_rl.iif != iif ||
 215             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 216             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 217                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 218                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 219                 mip6_report_rl.iif = iif;
 220                 ipv6_addr_copy(&mip6_report_rl.src, src);
 221                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 222                 allow = 1;
 223         }
 224         spin_unlock_bh(&mip6_report_rl.lock);
 225         return allow;
 226 }
 227
 228 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 229 {
 230         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 231         struct ipv6_destopt_hao *hao = NULL;
 232         struct xfrm_selector sel;
 233         int offset;
 234         struct timeval stamp;
 235         int err = 0;
 236
 237         if (unlikely(fl->proto == IPPROTO_MH &&
 238                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 239                 goto out;
 240
 241         if (likely(opt->dsthao)) {
 242                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 243                 if (likely(offset >= 0))
 244                         hao = (struct ipv6_destopt_hao *)(skb->nh.raw + offset);
 245         }
 246
 247         skb_get_timestamp(skb, &stamp);
 248
 249         if (!mip6_report_rl_allow(&stamp, &skb->nh.ipv6h->daddr,
 250                                   hao ? &hao->addr : &skb->nh.ipv6h->saddr,
 251                                   opt->iif))
 252                 goto out;
 253
 254         memset(&sel, 0, sizeof(sel));
 255         memcpy(&sel.daddr, (xfrm_address_t *)&skb->nh.ipv6h->daddr,
 256                sizeof(sel.daddr));
 257         sel.prefixlen_d = 128;
 258         memcpy(&sel.saddr, (xfrm_address_t *)&skb->nh.ipv6h->saddr,
 259                sizeof(sel.saddr));
 260         sel.prefixlen_s = 128;
 261         sel.family = AF_INET6;
 262         sel.proto = fl->proto;
 263         sel.dport = xfrm_flowi_dport(fl);
 264         if (sel.dport)
 265                 sel.dport_mask = htons(~0);
 266         sel.sport = xfrm_flowi_sport(fl);
 267         if (sel.sport)
 268                 sel.sport_mask = htons(~0);
 269         sel.ifindex = fl->oif;
 270
 271         err = km_report(IPPROTO_DSTOPTS, &sel,
 272                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 273
 274  out:
 275         return err;
 276 }
 277
 278 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 279                                u8 **nexthdr)
 280 {
 281         u16 offset = sizeof(struct ipv6hdr);
 282         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 283         unsigned int packet_len = skb->tail - skb->nh.raw;
 284         int found_rhdr = 0;
 285
 286         *nexthdr = &skb->nh.ipv6h->nexthdr;
 287
 288         while (offset + 1 <= packet_len) {
 289
 290                 switch (**nexthdr) {
 291                 case NEXTHDR_HOP:
 292                         break;
 293                 case NEXTHDR_ROUTING:
 294                         found_rhdr = 1;
 295                         break;
 296                 case NEXTHDR_DEST:
 297                         /*
 298                          * HAO MUST NOT appear more than once.
 299                          * XXX: It is better to try to find by the end of
 300                          * XXX: packet if HAO exists.
 301                          */
 302                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 303                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 304                                 return offset;
 305                         }
 306
 307                         if (found_rhdr)
 308                                 return offset;
 309
 310                         break;
 311                 default:
 312                         return offset;
 313                 }
 314
 315                 offset += ipv6_optlen(exthdr);
 316                 *nexthdr = &exthdr->nexthdr;
 317                 exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 318         }
 319
 320         return offset;
 321 }
 322
 323 static int mip6_destopt_init_state(struct xfrm_state *x)
 324 {
 325         if (x->id.spi) {
 326                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 327                        x->id.spi);
 328                 return -EINVAL;
 329         }
 330         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 331                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 332                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 333                 return -EINVAL;
 334         }
 335
 336         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 337                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 338                 sizeof(struct ipv6_destopt_hao);
 339         BUG_TRAP(x->props.header_len == 24);
 340
 341         return 0;
 342 }
 343
 344 /*
 345  * Do nothing about destroying since it has no specific operation for
 346  * destination options header unlike IPsec protocols.
 347  */
 348 static void mip6_destopt_destroy(struct xfrm_state *x)
 349 {
 350 }
 351
 352 static struct xfrm_type mip6_destopt_type =
 353 {
 354         .description    = "MIP6DESTOPT",
 355         .owner          = THIS_MODULE,
 356         .proto          = IPPROTO_DSTOPTS,
 357         .flags          = XFRM_TYPE_NON_FRAGMENT,
 358         .init_state     = mip6_destopt_init_state,
 359         .destructor     = mip6_destopt_destroy,
 360         .input          = mip6_destopt_input,
 361         .output         = mip6_destopt_output,
 362         .reject         = mip6_destopt_reject,
 363         .hdr_offset     = mip6_destopt_offset,
 364         .local_addr     = mip6_xfrm_addr,
 365 };
 366
 367 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 368 {
 369         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 370
 371         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 372             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 373                 return -ENOENT;
 374
 375         return rt2->rt_hdr.nexthdr;
 376 }
 377
 378 /* Routing Header type 2 is inserted.
 379  * IP Header's dst address is replaced with Routing Header's Home Address.
 380  */
 381 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 382 {
 383         struct ipv6hdr *iph;
 384         struct rt2_hdr *rt2;
 385         u8 nexthdr;
 386
 387         iph = (struct ipv6hdr *)skb->data;
 388         iph->payload_len = htons(skb->len - sizeof(*iph));
 389
 390         nexthdr = *skb->nh.raw;
 391         *skb->nh.raw = IPPROTO_ROUTING;
 392
 393         rt2 = (struct rt2_hdr *)skb->h.raw;
 394         rt2->rt_hdr.nexthdr = nexthdr;
 395         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 396         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 397         rt2->rt_hdr.segments_left = 1;
 398         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 399
 400         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 401
 402         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 403         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 404
 405         return 0;
 406 }
 407
 408 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 409                              u8 **nexthdr)
 410 {
 411         u16 offset = sizeof(struct ipv6hdr);
 412         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 413         unsigned int packet_len = skb->tail - skb->nh.raw;
 414         int found_rhdr = 0;
 415
 416         *nexthdr = &skb->nh.ipv6h->nexthdr;
 417
 418         while (offset + 1 <= packet_len) {
 419
 420                 switch (**nexthdr) {
 421                 case NEXTHDR_HOP:
 422                         break;
 423                 case NEXTHDR_ROUTING:
 424                         if (offset + 3 <= packet_len) {
 425                                 struct ipv6_rt_hdr *rt;
 426                                 rt = (struct ipv6_rt_hdr *)(skb->nh.raw + offset);
 427                                 if (rt->type != 0)
 428                                         return offset;
 429                         }
 430                         found_rhdr = 1;
 431                         break;
 432                 case NEXTHDR_DEST:
 433                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 434                                 return offset;
 435
 436                         if (found_rhdr)
 437                                 return offset;
 438
 439                         break;
 440                 default:
 441                         return offset;
 442                 }
 443
 444                 offset += ipv6_optlen(exthdr);
 445                 *nexthdr = &exthdr->nexthdr;
 446                 exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 447         }
 448
 449         return offset;
 450 }
 451
 452 static int mip6_rthdr_init_state(struct xfrm_state *x)
 453 {
 454         if (x->id.spi) {
 455                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 456                        x->id.spi);
 457                 return -EINVAL;
 458         }
 459         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 460                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 461                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 462                 return -EINVAL;
 463         }
 464
 465         x->props.header_len = sizeof(struct rt2_hdr);
 466
 467         return 0;
 468 }
 469
 470 /*
 471  * Do nothing about destroying since it has no specific operation for routing
 472  * header type 2 unlike IPsec protocols.
 473  */
 474 static void mip6_rthdr_destroy(struct xfrm_state *x)
 475 {
 476 }
 477
 478 static struct xfrm_type mip6_rthdr_type =
 479 {
 480         .description    = "MIP6RT",
 481         .owner          = THIS_MODULE,
 482         .proto          = IPPROTO_ROUTING,
 483         .flags          = XFRM_TYPE_NON_FRAGMENT,
 484         .init_state     = mip6_rthdr_init_state,
 485         .destructor     = mip6_rthdr_destroy,
 486         .input          = mip6_rthdr_input,
 487         .output         = mip6_rthdr_output,
 488         .hdr_offset     = mip6_rthdr_offset,
 489         .remote_addr    = mip6_xfrm_addr,
 490 };
 491
 492 int __init mip6_init(void)
 493 {
 494         printk(KERN_INFO "Mobile IPv6\n");
 495
 496         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 497                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 498                 goto mip6_destopt_xfrm_fail;
 499         }
 500         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 501                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 502                 goto mip6_rthdr_xfrm_fail;
 503         }
 504         return 0;
 505
 506  mip6_rthdr_xfrm_fail:
 507         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 508  mip6_destopt_xfrm_fail:
 509         return -EAGAIN;
 510 }
 511
 512 void __exit mip6_fini(void)
 513 {
 514         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 515                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 516         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 517                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 518 }