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 [%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x > %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x]\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 && fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 238                 goto out;
 239
 240         if (likely(opt->dsthao)) {
 241                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 242                 if (likely(offset >= 0))
 243                         hao = (struct ipv6_destopt_hao *)(skb->nh.raw + offset);
 244         }
 245
 246         skb_get_timestamp(skb, &stamp);
 247
 248         if (!mip6_report_rl_allow(&stamp, &skb->nh.ipv6h->daddr,
 249                                   hao ? &hao->addr : &skb->nh.ipv6h->saddr,
 250                                   opt->iif))
 251                 goto out;
 252
 253         memset(&sel, 0, sizeof(sel));
 254         memcpy(&sel.daddr, (xfrm_address_t *)&skb->nh.ipv6h->daddr,
 255                sizeof(sel.daddr));
 256         sel.prefixlen_d = 128;
 257         memcpy(&sel.saddr, (xfrm_address_t *)&skb->nh.ipv6h->saddr,
 258                sizeof(sel.saddr));
 259         sel.prefixlen_s = 128;
 260         sel.family = AF_INET6;
 261         sel.proto = fl->proto;
 262         sel.dport = xfrm_flowi_dport(fl);
 263         if (sel.dport)
 264                 sel.dport_mask = ~((__u16)0);
 265         sel.sport = xfrm_flowi_sport(fl);
 266         if (sel.sport)
 267                 sel.sport_mask = ~((__u16)0);
 268         sel.ifindex = fl->oif;
 269
 270         err = km_report(IPPROTO_DSTOPTS, &sel,
 271                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 272
 273  out:
 274         return err;
 275 }
 276
 277 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 278                                u8 **nexthdr)
 279 {
 280         u16 offset = sizeof(struct ipv6hdr);
 281         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 282         unsigned int packet_len = skb->tail - skb->nh.raw;
 283         int found_rhdr = 0;
 284
 285         *nexthdr = &skb->nh.ipv6h->nexthdr;
 286
 287         while (offset + 1 <= packet_len) {
 288
 289                 switch (**nexthdr) {
 290                 case NEXTHDR_HOP:
 291                         break;
 292                 case NEXTHDR_ROUTING:
 293                         found_rhdr = 1;
 294                         break;
 295                 case NEXTHDR_DEST:
 296                         /*
 297                          * HAO MUST NOT appear more than once.
 298                          * XXX: It is better to try to find by the end of
 299                          * XXX: packet if HAO exists.
 300                          */
 301                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 302                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 303                                 return offset;
 304                         }
 305
 306                         if (found_rhdr)
 307                                 return offset;
 308
 309                         break;
 310                 default:
 311                         return offset;
 312                 }
 313
 314                 offset += ipv6_optlen(exthdr);
 315                 *nexthdr = &exthdr->nexthdr;
 316                 exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 317         }
 318
 319         return offset;
 320 }
 321
 322 static int mip6_destopt_init_state(struct xfrm_state *x)
 323 {
 324         if (x->id.spi) {
 325                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 326                        x->id.spi);
 327                 return -EINVAL;
 328         }
 329         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 330                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 331                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 332                 return -EINVAL;
 333         }
 334
 335         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 336                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 337                 sizeof(struct ipv6_destopt_hao);
 338         BUG_TRAP(x->props.header_len == 24);
 339
 340         return 0;
 341 }
 342
 343 /*
 344  * Do nothing about destroying since it has no specific operation for
 345  * destination options header unlike IPsec protocols.
 346  */
 347 static void mip6_destopt_destroy(struct xfrm_state *x)
 348 {
 349 }
 350
 351 static struct xfrm_type mip6_destopt_type =
 352 {
 353         .description    = "MIP6DESTOPT",
 354         .owner          = THIS_MODULE,
 355         .proto          = IPPROTO_DSTOPTS,
 356         .flags          = XFRM_TYPE_NON_FRAGMENT,
 357         .init_state     = mip6_destopt_init_state,
 358         .destructor     = mip6_destopt_destroy,
 359         .input          = mip6_destopt_input,
 360         .output         = mip6_destopt_output,
 361         .reject         = mip6_destopt_reject,
 362         .hdr_offset     = mip6_destopt_offset,
 363         .local_addr     = mip6_xfrm_addr,
 364 };
 365
 366 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 367 {
 368         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 369
 370         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 371             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 372                 return -ENOENT;
 373
 374         return rt2->rt_hdr.nexthdr;
 375 }
 376
 377 /* Routing Header type 2 is inserted.
 378  * IP Header's dst address is replaced with Routing Header's Home Address.
 379  */
 380 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 381 {
 382         struct ipv6hdr *iph;
 383         struct rt2_hdr *rt2;
 384         u8 nexthdr;
 385
 386         iph = (struct ipv6hdr *)skb->data;
 387         iph->payload_len = htons(skb->len - sizeof(*iph));
 388
 389         nexthdr = *skb->nh.raw;
 390         *skb->nh.raw = IPPROTO_ROUTING;
 391
 392         rt2 = (struct rt2_hdr *)skb->h.raw;
 393         rt2->rt_hdr.nexthdr = nexthdr;
 394         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 395         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 396         rt2->rt_hdr.segments_left = 1;
 397         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 398
 399         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 400
 401         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 402         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 403
 404         return 0;
 405 }
 406
 407 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 408                              u8 **nexthdr)
 409 {
 410         u16 offset = sizeof(struct ipv6hdr);
 411         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 412         unsigned int packet_len = skb->tail - skb->nh.raw;
 413         int found_rhdr = 0;
 414
 415         *nexthdr = &skb->nh.ipv6h->nexthdr;
 416
 417         while (offset + 1 <= packet_len) {
 418
 419                 switch (**nexthdr) {
 420                 case NEXTHDR_HOP:
 421                         break;
 422                 case NEXTHDR_ROUTING:
 423                         if (offset + 3 <= packet_len) {
 424                                 struct ipv6_rt_hdr *rt;
 425                                 rt = (struct ipv6_rt_hdr *)(skb->nh.raw + offset);
 426                                 if (rt->type != 0)
 427                                         return offset;
 428                         }
 429                         found_rhdr = 1;
 430                         break;
 431                 case NEXTHDR_DEST:
 432                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 433                                 return offset;
 434
 435                         if (found_rhdr)
 436                                 return offset;
 437
 438                         break;
 439                 default:
 440                         return offset;
 441                 }
 442
 443                 offset += ipv6_optlen(exthdr);
 444                 *nexthdr = &exthdr->nexthdr;
 445                 exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 446         }
 447
 448         return offset;
 449 }
 450
 451 static int mip6_rthdr_init_state(struct xfrm_state *x)
 452 {
 453         if (x->id.spi) {
 454                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 455                        x->id.spi);
 456                 return -EINVAL;
 457         }
 458         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 459                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 460                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 461                 return -EINVAL;
 462         }
 463
 464         x->props.header_len = sizeof(struct rt2_hdr);
 465
 466         return 0;
 467 }
 468
 469 /*
 470  * Do nothing about destroying since it has no specific operation for routing
 471  * header type 2 unlike IPsec protocols.
 472  */
 473 static void mip6_rthdr_destroy(struct xfrm_state *x)
 474 {
 475 }
 476
 477 static struct xfrm_type mip6_rthdr_type =
 478 {
 479         .description    = "MIP6RT",
 480         .owner          = THIS_MODULE,
 481         .proto          = IPPROTO_ROUTING,
 482         .flags          = XFRM_TYPE_NON_FRAGMENT,
 483         .init_state     = mip6_rthdr_init_state,
 484         .destructor     = mip6_rthdr_destroy,
 485         .input          = mip6_rthdr_input,
 486         .output         = mip6_rthdr_output,
 487         .hdr_offset     = mip6_rthdr_offset,
 488         .remote_addr    = mip6_xfrm_addr,
 489 };
 490
 491 int __init mip6_init(void)
 492 {
 493         printk(KERN_INFO "Mobile IPv6\n");
 494
 495         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 496                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 497                 goto mip6_destopt_xfrm_fail;
 498         }
 499         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 500                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 501                 goto mip6_rthdr_xfrm_fail;
 502         }
 503         return 0;
 504
 505  mip6_rthdr_xfrm_fail:
 506         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 507  mip6_destopt_xfrm_fail:
 508         return -EAGAIN;
 509 }
 510
 511 void __exit mip6_fini(void)
 512 {
 513         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 514                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 515         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 516                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 517 }