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   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 inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  38 {
  39         return (n - len + 16) & 0x7;
  40 }
  41
  42 static inline void *mip6_padn(__u8 *data, __u8 padlen)
  43 {
  44         if (!data)
  45                 return NULL;
  46         if (padlen == 1) {
  47                 data[0] = IPV6_TLV_PAD0;
  48         } else if (padlen > 1) {
  49                 data[0] = IPV6_TLV_PADN;
  50                 data[1] = padlen - 2;
  51                 if (padlen > 2)
  52                         memset(data+2, 0, data[1]);
  53         }
  54         return data + padlen;
  55 }
  56
  57 static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
  58 {
  59         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
  60 }
  61
  62 static int mip6_mh_len(int type)
  63 {
  64         int len = 0;
  65
  66         switch (type) {
  67         case IP6_MH_TYPE_BRR:
  68                 len = 0;
  69                 break;
  70         case IP6_MH_TYPE_HOTI:
  71         case IP6_MH_TYPE_COTI:
  72         case IP6_MH_TYPE_BU:
  73         case IP6_MH_TYPE_BACK:
  74                 len = 1;
  75                 break;
  76         case IP6_MH_TYPE_HOT:
  77         case IP6_MH_TYPE_COT:
  78         case IP6_MH_TYPE_BERROR:
  79                 len = 2;
  80                 break;
  81         }
  82         return len;
  83 }
  84
  85 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  86 {
  87         struct ip6_mh *mh;
  88
  89         if (!pskb_may_pull(skb, (skb_transport_offset(skb)) + 8) ||
  90             !pskb_may_pull(skb, (skb_transport_offset(skb) +
  91                                  ((skb_transport_header(skb)[1] + 1) << 3))))
  92                 return -1;
  93
  94         mh = (struct ip6_mh *)skb_transport_header(skb);
  95
  96         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
  97                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
  98                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
  99                 mip6_param_prob(skb, 0, ((&mh->ip6mh_hdrlen) -
 100                                          skb_network_header(skb)));
 101                 return -1;
 102         }
 103
 104         if (mh->ip6mh_proto != IPPROTO_NONE) {
 105                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
 106                                mh->ip6mh_proto);
 107                 mip6_param_prob(skb, 0, ((&mh->ip6mh_proto) -
 108                                          skb_network_header(skb)));
 109                 return -1;
 110         }
 111
 112         return 0;
 113 }
 114
 115 struct mip6_report_rate_limiter {
 116         spinlock_t lock;
 117         struct timeval stamp;
 118         int iif;
 119         struct in6_addr src;
 120         struct in6_addr dst;
 121 };
 122
 123 static struct mip6_report_rate_limiter mip6_report_rl = {
 124         .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
 125 };
 126
 127 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 128 {
 129         struct ipv6hdr *iph = ipv6_hdr(skb);
 130         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 131         int err = destopt->nexthdr;
 132
 133         spin_lock(&x->lock);
 134         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 135             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 136                 err = -ENOENT;
 137         spin_unlock(&x->lock);
 138
 139         return err;
 140 }
 141
 142 /* Destination Option Header is inserted.
 143  * IP Header's src address is replaced with Home Address Option in
 144  * Destination Option Header.
 145  */
 146 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 147 {
 148         struct ipv6hdr *iph;
 149         struct ipv6_destopt_hdr *dstopt;
 150         struct ipv6_destopt_hao *hao;
 151         u8 nexthdr;
 152         int len;
 153
 154         skb_push(skb, -skb_network_offset(skb));
 155         iph = ipv6_hdr(skb);
 156
 157         nexthdr = *skb_mac_header(skb);
 158         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
 159
 160         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 161         dstopt->nexthdr = nexthdr;
 162
 163         hao = mip6_padn((char *)(dstopt + 1),
 164                         calc_padlen(sizeof(*dstopt), 6));
 165
 166         hao->type = IPV6_TLV_HAO;
 167         BUILD_BUG_ON(sizeof(*hao) != 18);
 168         hao->length = sizeof(*hao) - 2;
 169
 170         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 171
 172         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 173         spin_lock_bh(&x->lock);
 174         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 175         spin_unlock_bh(&x->lock);
 176
 177         WARN_ON(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 net *net = xs_net(x);
 209         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 210         struct ipv6_destopt_hao *hao = NULL;
 211         struct xfrm_selector sel;
 212         int offset;
 213         struct timeval stamp;
 214         int err = 0;
 215
 216         if (unlikely(fl->proto == IPPROTO_MH &&
 217                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 218                 goto out;
 219
 220         if (likely(opt->dsthao)) {
 221                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 222                 if (likely(offset >= 0))
 223                         hao = (struct ipv6_destopt_hao *)
 224                                         (skb_network_header(skb) + offset);
 225         }
 226
 227         skb_get_timestamp(skb, &stamp);
 228
 229         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 230                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 231                                   opt->iif))
 232                 goto out;
 233
 234         memset(&sel, 0, sizeof(sel));
 235         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 236                sizeof(sel.daddr));
 237         sel.prefixlen_d = 128;
 238         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 239                sizeof(sel.saddr));
 240         sel.prefixlen_s = 128;
 241         sel.family = AF_INET6;
 242         sel.proto = fl->proto;
 243         sel.dport = xfrm_flowi_dport(fl);
 244         if (sel.dport)
 245                 sel.dport_mask = htons(~0);
 246         sel.sport = xfrm_flowi_sport(fl);
 247         if (sel.sport)
 248                 sel.sport_mask = htons(~0);
 249         sel.ifindex = fl->oif;
 250
 251         err = km_report(net, IPPROTO_DSTOPTS, &sel,
 252                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 253
 254  out:
 255         return err;
 256 }
 257
 258 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 259                                u8 **nexthdr)
 260 {
 261         u16 offset = sizeof(struct ipv6hdr);
 262         struct ipv6_opt_hdr *exthdr =
 263                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 264         const unsigned char *nh = skb_network_header(skb);
 265         unsigned int packet_len = skb->tail - skb->network_header;
 266         int found_rhdr = 0;
 267
 268         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 269
 270         while (offset + 1 <= packet_len) {
 271
 272                 switch (**nexthdr) {
 273                 case NEXTHDR_HOP:
 274                         break;
 275                 case NEXTHDR_ROUTING:
 276                         found_rhdr = 1;
 277                         break;
 278                 case NEXTHDR_DEST:
 279                         /*
 280                          * HAO MUST NOT appear more than once.
 281                          * XXX: It is better to try to find by the end of
 282                          * XXX: packet if HAO exists.
 283                          */
 284                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 285                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 286                                 return offset;
 287                         }
 288
 289                         if (found_rhdr)
 290                                 return offset;
 291
 292                         break;
 293                 default:
 294                         return offset;
 295                 }
 296
 297                 offset += ipv6_optlen(exthdr);
 298                 *nexthdr = &exthdr->nexthdr;
 299                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 300         }
 301
 302         return offset;
 303 }
 304
 305 static int mip6_destopt_init_state(struct xfrm_state *x)
 306 {
 307         if (x->id.spi) {
 308                 printk(KERN_INFO "%s: spi is not 0: %u\n", __func__,
 309                        x->id.spi);
 310                 return -EINVAL;
 311         }
 312         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 313                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 314                        __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 315                 return -EINVAL;
 316         }
 317
 318         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 319                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 320                 sizeof(struct ipv6_destopt_hao);
 321         WARN_ON(x->props.header_len != 24);
 322
 323         return 0;
 324 }
 325
 326 /*
 327  * Do nothing about destroying since it has no specific operation for
 328  * destination options header unlike IPsec protocols.
 329  */
 330 static void mip6_destopt_destroy(struct xfrm_state *x)
 331 {
 332 }
 333
 334 static const struct xfrm_type mip6_destopt_type =
 335 {
 336         .description    = "MIP6DESTOPT",
 337         .owner          = THIS_MODULE,
 338         .proto          = IPPROTO_DSTOPTS,
 339         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
 340         .init_state     = mip6_destopt_init_state,
 341         .destructor     = mip6_destopt_destroy,
 342         .input          = mip6_destopt_input,
 343         .output         = mip6_destopt_output,
 344         .reject         = mip6_destopt_reject,
 345         .hdr_offset     = mip6_destopt_offset,
 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         int err = rt2->rt_hdr.nexthdr;
 352
 353         spin_lock(&x->lock);
 354         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 355             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 356                 err = -ENOENT;
 357         spin_unlock(&x->lock);
 358
 359         return err;
 360 }
 361
 362 /* Routing Header type 2 is inserted.
 363  * IP Header's dst address is replaced with Routing Header's Home Address.
 364  */
 365 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 366 {
 367         struct ipv6hdr *iph;
 368         struct rt2_hdr *rt2;
 369         u8 nexthdr;
 370
 371         skb_push(skb, -skb_network_offset(skb));
 372         iph = ipv6_hdr(skb);
 373
 374         nexthdr = *skb_mac_header(skb);
 375         *skb_mac_header(skb) = IPPROTO_ROUTING;
 376
 377         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 378         rt2->rt_hdr.nexthdr = nexthdr;
 379         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 380         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 381         rt2->rt_hdr.segments_left = 1;
 382         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 383
 384         WARN_ON(rt2->rt_hdr.hdrlen != 2);
 385
 386         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 387         spin_lock_bh(&x->lock);
 388         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 389         spin_unlock_bh(&x->lock);
 390
 391         return 0;
 392 }
 393
 394 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 395                              u8 **nexthdr)
 396 {
 397         u16 offset = sizeof(struct ipv6hdr);
 398         struct ipv6_opt_hdr *exthdr =
 399                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 400         const unsigned char *nh = skb_network_header(skb);
 401         unsigned int packet_len = skb->tail - skb->network_header;
 402         int found_rhdr = 0;
 403
 404         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 405
 406         while (offset + 1 <= packet_len) {
 407
 408                 switch (**nexthdr) {
 409                 case NEXTHDR_HOP:
 410                         break;
 411                 case NEXTHDR_ROUTING:
 412                         if (offset + 3 <= packet_len) {
 413                                 struct ipv6_rt_hdr *rt;
 414                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 415                                 if (rt->type != 0)
 416                                         return offset;
 417                         }
 418                         found_rhdr = 1;
 419                         break;
 420                 case NEXTHDR_DEST:
 421                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 422                                 return offset;
 423
 424                         if (found_rhdr)
 425                                 return offset;
 426
 427                         break;
 428                 default:
 429                         return offset;
 430                 }
 431
 432                 offset += ipv6_optlen(exthdr);
 433                 *nexthdr = &exthdr->nexthdr;
 434                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 435         }
 436
 437         return offset;
 438 }
 439
 440 static int mip6_rthdr_init_state(struct xfrm_state *x)
 441 {
 442         if (x->id.spi) {
 443                 printk(KERN_INFO "%s: spi is not 0: %u\n", __func__,
 444                        x->id.spi);
 445                 return -EINVAL;
 446         }
 447         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 448                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 449                        __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 450                 return -EINVAL;
 451         }
 452
 453         x->props.header_len = sizeof(struct rt2_hdr);
 454
 455         return 0;
 456 }
 457
 458 /*
 459  * Do nothing about destroying since it has no specific operation for routing
 460  * header type 2 unlike IPsec protocols.
 461  */
 462 static void mip6_rthdr_destroy(struct xfrm_state *x)
 463 {
 464 }
 465
 466 static const struct xfrm_type mip6_rthdr_type =
 467 {
 468         .description    = "MIP6RT",
 469         .owner          = THIS_MODULE,
 470         .proto          = IPPROTO_ROUTING,
 471         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
 472         .init_state     = mip6_rthdr_init_state,
 473         .destructor     = mip6_rthdr_destroy,
 474         .input          = mip6_rthdr_input,
 475         .output         = mip6_rthdr_output,
 476         .hdr_offset     = mip6_rthdr_offset,
 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", __func__);
 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", __func__);
 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", __func__);
 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", __func__);
 511         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 512                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __func__);
 513         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 514                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __func__);
 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);