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/config.h>
  26 #include <linux/module.h>
  27 #include <linux/skbuff.h>
  28 #include <linux/time.h>
  29 #include <linux/ipv6.h>
  30 #include <linux/icmpv6.h>
  31 #include <net/sock.h>
  32 #include <net/ipv6.h>
  33 #include <net/ip6_checksum.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 int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  91 {
  92         struct ip6_mh *mh;
  93         int mhlen;
  94
  95         if (!pskb_may_pull(skb, (skb->h.raw - skb->data) + 8) ||
  96             !pskb_may_pull(skb, (skb->h.raw - skb->data) + ((skb->h.raw[1] + 1) << 3)))
  97                 return -1;
  98
  99         mh = (struct ip6_mh *)skb->h.raw;
 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) - skb->nh.raw);
 105                 return -1;
 106         }
 107         mhlen = (mh->ip6mh_hdrlen + 1) << 3;
 108
 109         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 110                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 111                 if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
 112                                     &skb->nh.ipv6h->daddr,
 113                                     mhlen, IPPROTO_MH,
 114                                     skb->csum)) {
 115                         LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH hw checksum failed\n");
 116                         skb->ip_summed = CHECKSUM_NONE;
 117                 }
 118         }
 119         if (skb->ip_summed == CHECKSUM_NONE) {
 120                 if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
 121                                     &skb->nh.ipv6h->daddr,
 122                                     mhlen, IPPROTO_MH,
 123                                     skb_checksum(skb, 0, mhlen, 0))) {
 124                         LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH checksum failed "
 125                                        "[" NIP6_FMT " > " NIP6_FMT "]\n",
 126                                        NIP6(skb->nh.ipv6h->saddr),
 127                                        NIP6(skb->nh.ipv6h->daddr));
 128                         return -1;
 129                 }
 130                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 131         }
 132
 133         if (mh->ip6mh_proto != IPPROTO_NONE) {
 134                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
 135                                mh->ip6mh_proto);
 136                 mip6_param_prob(skb, 0, (&mh->ip6mh_proto) - skb->nh.raw);
 137                 return -1;
 138         }
 139
 140         return 0;
 141 }
 142
 143 struct mip6_report_rate_limiter {
 144         spinlock_t lock;
 145         struct timeval stamp;
 146         int iif;
 147         struct in6_addr src;
 148         struct in6_addr dst;
 149 };
 150
 151 static struct mip6_report_rate_limiter mip6_report_rl = {
 152         .lock = SPIN_LOCK_UNLOCKED
 153 };
 154
 155 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 156 {
 157         struct ipv6hdr *iph = skb->nh.ipv6h;
 158         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 159
 160         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 161             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 162                 return -ENOENT;
 163
 164         return destopt->nexthdr;
 165 }
 166
 167 /* Destination Option Header is inserted.
 168  * IP Header's src address is replaced with Home Address Option in
 169  * Destination Option Header.
 170  */
 171 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 172 {
 173         struct ipv6hdr *iph;
 174         struct ipv6_destopt_hdr *dstopt;
 175         struct ipv6_destopt_hao *hao;
 176         u8 nexthdr;
 177         int len;
 178
 179         iph = (struct ipv6hdr *)skb->data;
 180         iph->payload_len = htons(skb->len - sizeof(*iph));
 181
 182         nexthdr = *skb->nh.raw;
 183         *skb->nh.raw = IPPROTO_DSTOPTS;
 184
 185         dstopt = (struct ipv6_destopt_hdr *)skb->h.raw;
 186         dstopt->nexthdr = nexthdr;
 187
 188         hao = mip6_padn((char *)(dstopt + 1),
 189                         calc_padlen(sizeof(*dstopt), 6));
 190
 191         hao->type = IPV6_TLV_HAO;
 192         hao->length = sizeof(*hao) - 2;
 193         BUG_TRAP(hao->length == 16);
 194
 195         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 196
 197         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 198         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 199
 200         BUG_TRAP(len == x->props.header_len);
 201         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 202
 203         return 0;
 204 }
 205
 206 static inline int mip6_report_rl_allow(struct timeval *stamp,
 207                                        struct in6_addr *dst,
 208                                        struct in6_addr *src, int iif)
 209 {
 210         int allow = 0;
 211
 212         spin_lock_bh(&mip6_report_rl.lock);
 213         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 214             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 215             mip6_report_rl.iif != iif ||
 216             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 217             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 218                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 219                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 220                 mip6_report_rl.iif = iif;
 221                 ipv6_addr_copy(&mip6_report_rl.src, src);
 222                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 223                 allow = 1;
 224         }
 225         spin_unlock_bh(&mip6_report_rl.lock);
 226         return allow;
 227 }
 228
 229 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 230 {
 231         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 232         struct ipv6_destopt_hao *hao = NULL;
 233         struct xfrm_selector sel;
 234         int offset;
 235         struct timeval stamp;
 236         int err = 0;
 237
 238         if (unlikely(fl->proto == IPPROTO_MH &&
 239                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 240                 goto out;
 241
 242         if (likely(opt->dsthao)) {
 243                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 244                 if (likely(offset >= 0))
 245                         hao = (struct ipv6_destopt_hao *)(skb->nh.raw + offset);
 246         }
 247
 248         skb_get_timestamp(skb, &stamp);
 249
 250         if (!mip6_report_rl_allow(&stamp, &skb->nh.ipv6h->daddr,
 251                                   hao ? &hao->addr : &skb->nh.ipv6h->saddr,
 252                                   opt->iif))
 253                 goto out;
 254
 255         memset(&sel, 0, sizeof(sel));
 256         memcpy(&sel.daddr, (xfrm_address_t *)&skb->nh.ipv6h->daddr,
 257                sizeof(sel.daddr));
 258         sel.prefixlen_d = 128;
 259         memcpy(&sel.saddr, (xfrm_address_t *)&skb->nh.ipv6h->saddr,
 260                sizeof(sel.saddr));
 261         sel.prefixlen_s = 128;
 262         sel.family = AF_INET6;
 263         sel.proto = fl->proto;
 264         sel.dport = xfrm_flowi_dport(fl);
 265         if (sel.dport)
 266                 sel.dport_mask = ~((__u16)0);
 267         sel.sport = xfrm_flowi_sport(fl);
 268         if (sel.sport)
 269                 sel.sport_mask = ~((__u16)0);
 270         sel.ifindex = fl->oif;
 271
 272         err = km_report(IPPROTO_DSTOPTS, &sel,
 273                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 274
 275  out:
 276         return err;
 277 }
 278
 279 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 280                                u8 **nexthdr)
 281 {
 282         u16 offset = sizeof(struct ipv6hdr);
 283         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 284         unsigned int packet_len = skb->tail - skb->nh.raw;
 285         int found_rhdr = 0;
 286
 287         *nexthdr = &skb->nh.ipv6h->nexthdr;
 288
 289         while (offset + 1 <= packet_len) {
 290
 291                 switch (**nexthdr) {
 292                 case NEXTHDR_HOP:
 293                         break;
 294                 case NEXTHDR_ROUTING:
 295                         found_rhdr = 1;
 296                         break;
 297                 case NEXTHDR_DEST:
 298                         /*
 299                          * HAO MUST NOT appear more than once.
 300                          * XXX: It is better to try to find by the end of
 301                          * XXX: packet if HAO exists.
 302                          */
 303                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 304                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 305                                 return offset;
 306                         }
 307
 308                         if (found_rhdr)
 309                                 return offset;
 310
 311                         break;
 312                 default:
 313                         return offset;
 314                 }
 315
 316                 offset += ipv6_optlen(exthdr);
 317                 *nexthdr = &exthdr->nexthdr;
 318                 exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 319         }
 320
 321         return offset;
 322 }
 323
 324 static int mip6_destopt_init_state(struct xfrm_state *x)
 325 {
 326         if (x->id.spi) {
 327                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 328                        x->id.spi);
 329                 return -EINVAL;
 330         }
 331         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 332                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 333                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 334                 return -EINVAL;
 335         }
 336
 337         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 338                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 339                 sizeof(struct ipv6_destopt_hao);
 340         BUG_TRAP(x->props.header_len == 24);
 341
 342         return 0;
 343 }
 344
 345 /*
 346  * Do nothing about destroying since it has no specific operation for
 347  * destination options header unlike IPsec protocols.
 348  */
 349 static void mip6_destopt_destroy(struct xfrm_state *x)
 350 {
 351 }
 352
 353 static struct xfrm_type mip6_destopt_type =
 354 {
 355         .description    = "MIP6DESTOPT",
 356         .owner          = THIS_MODULE,
 357         .proto          = IPPROTO_DSTOPTS,
 358         .flags          = XFRM_TYPE_NON_FRAGMENT,
 359         .init_state     = mip6_destopt_init_state,
 360         .destructor     = mip6_destopt_destroy,
 361         .input          = mip6_destopt_input,
 362         .output         = mip6_destopt_output,
 363         .reject         = mip6_destopt_reject,
 364         .hdr_offset     = mip6_destopt_offset,
 365         .local_addr     = mip6_xfrm_addr,
 366 };
 367
 368 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 369 {
 370         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 371
 372         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 373             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 374                 return -ENOENT;
 375
 376         return rt2->rt_hdr.nexthdr;
 377 }
 378
 379 /* Routing Header type 2 is inserted.
 380  * IP Header's dst address is replaced with Routing Header's Home Address.
 381  */
 382 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 383 {
 384         struct ipv6hdr *iph;
 385         struct rt2_hdr *rt2;
 386         u8 nexthdr;
 387
 388         iph = (struct ipv6hdr *)skb->data;
 389         iph->payload_len = htons(skb->len - sizeof(*iph));
 390
 391         nexthdr = *skb->nh.raw;
 392         *skb->nh.raw = IPPROTO_ROUTING;
 393
 394         rt2 = (struct rt2_hdr *)skb->h.raw;
 395         rt2->rt_hdr.nexthdr = nexthdr;
 396         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 397         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 398         rt2->rt_hdr.segments_left = 1;
 399         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 400
 401         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 402
 403         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 404         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 405
 406         return 0;
 407 }
 408
 409 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 410                              u8 **nexthdr)
 411 {
 412         u16 offset = sizeof(struct ipv6hdr);
 413         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 414         unsigned int packet_len = skb->tail - skb->nh.raw;
 415         int found_rhdr = 0;
 416
 417         *nexthdr = &skb->nh.ipv6h->nexthdr;
 418
 419         while (offset + 1 <= packet_len) {
 420
 421                 switch (**nexthdr) {
 422                 case NEXTHDR_HOP:
 423                         break;
 424                 case NEXTHDR_ROUTING:
 425                         if (offset + 3 <= packet_len) {
 426                                 struct ipv6_rt_hdr *rt;
 427                                 rt = (struct ipv6_rt_hdr *)(skb->nh.raw + offset);
 428                                 if (rt->type != 0)
 429                                         return offset;
 430                         }
 431                         found_rhdr = 1;
 432                         break;
 433                 case NEXTHDR_DEST:
 434                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 435                                 return offset;
 436
 437                         if (found_rhdr)
 438                                 return offset;
 439
 440                         break;
 441                 default:
 442                         return offset;
 443                 }
 444
 445                 offset += ipv6_optlen(exthdr);
 446                 *nexthdr = &exthdr->nexthdr;
 447                 exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 448         }
 449
 450         return offset;
 451 }
 452
 453 static int mip6_rthdr_init_state(struct xfrm_state *x)
 454 {
 455         if (x->id.spi) {
 456                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 457                        x->id.spi);
 458                 return -EINVAL;
 459         }
 460         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 461                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 462                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 463                 return -EINVAL;
 464         }
 465
 466         x->props.header_len = sizeof(struct rt2_hdr);
 467
 468         return 0;
 469 }
 470
 471 /*
 472  * Do nothing about destroying since it has no specific operation for routing
 473  * header type 2 unlike IPsec protocols.
 474  */
 475 static void mip6_rthdr_destroy(struct xfrm_state *x)
 476 {
 477 }
 478
 479 static struct xfrm_type mip6_rthdr_type =
 480 {
 481         .description    = "MIP6RT",
 482         .owner          = THIS_MODULE,
 483         .proto          = IPPROTO_ROUTING,
 484         .flags          = XFRM_TYPE_NON_FRAGMENT,
 485         .init_state     = mip6_rthdr_init_state,
 486         .destructor     = mip6_rthdr_destroy,
 487         .input          = mip6_rthdr_input,
 488         .output         = mip6_rthdr_output,
 489         .hdr_offset     = mip6_rthdr_offset,
 490         .remote_addr    = mip6_xfrm_addr,
 491 };
 492
 493 int __init mip6_init(void)
 494 {
 495         printk(KERN_INFO "Mobile IPv6\n");
 496
 497         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 498                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 499                 goto mip6_destopt_xfrm_fail;
 500         }
 501         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 502                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 503                 goto mip6_rthdr_xfrm_fail;
 504         }
 505         return 0;
 506
 507  mip6_rthdr_xfrm_fail:
 508         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 509  mip6_destopt_xfrm_fail:
 510         return -EAGAIN;
 511 }
 512
 513 void __exit mip6_fini(void)
 514 {
 515         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 516                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 517         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 518                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 519 }