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, see <http://www.gnu.org/licenses/>.
  17  */
  18 /*
  19  * Authors:
  20  *      Noriaki TAKAMIYA @USAGI
  21  *      Masahide NAKAMURA @USAGI
  22  */
  23
  24 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  25
  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/rawv6.h>
  35 #include <net/xfrm.h>
  36 #include <net/mip6.h>
  37
  38 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  39 {
  40         return (n - len + 16) & 0x7;
  41 }
  42
  43 static inline void *mip6_padn(__u8 *data, __u8 padlen)
  44 {
  45         if (!data)
  46                 return NULL;
  47         if (padlen == 1) {
  48                 data[0] = IPV6_TLV_PAD1;
  49         } else if (padlen > 1) {
  50                 data[0] = IPV6_TLV_PADN;
  51                 data[1] = padlen - 2;
  52                 if (padlen > 2)
  53                         memset(data+2, 0, data[1]);
  54         }
  55         return data + padlen;
  56 }
  57
  58 static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
  59 {
  60         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
  61 }
  62
  63 static int mip6_mh_len(int type)
  64 {
  65         int len = 0;
  66
  67         switch (type) {
  68         case IP6_MH_TYPE_BRR:
  69                 len = 0;
  70                 break;
  71         case IP6_MH_TYPE_HOTI:
  72         case IP6_MH_TYPE_COTI:
  73         case IP6_MH_TYPE_BU:
  74         case IP6_MH_TYPE_BACK:
  75                 len = 1;
  76                 break;
  77         case IP6_MH_TYPE_HOT:
  78         case IP6_MH_TYPE_COT:
  79         case IP6_MH_TYPE_BERROR:
  80                 len = 2;
  81                 break;
  82         }
  83         return len;
  84 }
  85
  86 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  87 {
  88         struct ip6_mh _hdr;
  89         const struct ip6_mh *mh;
  90
  91         mh = skb_header_pointer(skb, skb_transport_offset(skb),
  92                                 sizeof(_hdr), &_hdr);
  93         if (!mh)
  94                 return -1;
  95
  96         if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
  97                 return -1;
  98
  99         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
 100                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
 101                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
 102                 mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
 103                                 skb_network_header_len(skb));
 104                 return -1;
 105         }
 106
 107         if (mh->ip6mh_proto != IPPROTO_NONE) {
 108                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
 109                                mh->ip6mh_proto);
 110                 mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
 111                                 skb_network_header_len(skb));
 112                 return -1;
 113         }
 114
 115         return 0;
 116 }
 117
 118 struct mip6_report_rate_limiter {
 119         spinlock_t lock;
 120         struct timeval stamp;
 121         int iif;
 122         struct in6_addr src;
 123         struct in6_addr dst;
 124 };
 125
 126 static struct mip6_report_rate_limiter mip6_report_rl = {
 127         .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
 128 };
 129
 130 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 131 {
 132         const struct ipv6hdr *iph = ipv6_hdr(skb);
 133         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 134         int err = destopt->nexthdr;
 135
 136         spin_lock(&x->lock);
 137         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 138             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 139                 err = -ENOENT;
 140         spin_unlock(&x->lock);
 141
 142         return err;
 143 }
 144
 145 /* Destination Option Header is inserted.
 146  * IP Header's src address is replaced with Home Address Option in
 147  * Destination Option Header.
 148  */
 149 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 150 {
 151         struct ipv6hdr *iph;
 152         struct ipv6_destopt_hdr *dstopt;
 153         struct ipv6_destopt_hao *hao;
 154         u8 nexthdr;
 155         int len;
 156
 157         skb_push(skb, -skb_network_offset(skb));
 158         iph = ipv6_hdr(skb);
 159
 160         nexthdr = *skb_mac_header(skb);
 161         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
 162
 163         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 164         dstopt->nexthdr = nexthdr;
 165
 166         hao = mip6_padn((char *)(dstopt + 1),
 167                         calc_padlen(sizeof(*dstopt), 6));
 168
 169         hao->type = IPV6_TLV_HAO;
 170         BUILD_BUG_ON(sizeof(*hao) != 18);
 171         hao->length = sizeof(*hao) - 2;
 172
 173         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 174
 175         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 176         spin_lock_bh(&x->lock);
 177         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 178         spin_unlock_bh(&x->lock);
 179
 180         WARN_ON(len != x->props.header_len);
 181         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 182
 183         return 0;
 184 }
 185
 186 static inline int mip6_report_rl_allow(struct timeval *stamp,
 187                                        const struct in6_addr *dst,
 188                                        const struct in6_addr *src, int iif)
 189 {
 190         int allow = 0;
 191
 192         spin_lock_bh(&mip6_report_rl.lock);
 193         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 194             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 195             mip6_report_rl.iif != iif ||
 196             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 197             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 198                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 199                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 200                 mip6_report_rl.iif = iif;
 201                 mip6_report_rl.src = *src;
 202                 mip6_report_rl.dst = *dst;
 203                 allow = 1;
 204         }
 205         spin_unlock_bh(&mip6_report_rl.lock);
 206         return allow;
 207 }
 208
 209 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
 210                                const struct flowi *fl)
 211 {
 212         struct net *net = xs_net(x);
 213         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 214         const struct flowi6 *fl6 = &fl->u.ip6;
 215         struct ipv6_destopt_hao *hao = NULL;
 216         struct xfrm_selector sel;
 217         int offset;
 218         struct timeval stamp;
 219         int err = 0;
 220
 221         if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
 222                      fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
 223                 goto out;
 224
 225         if (likely(opt->dsthao)) {
 226                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 227                 if (likely(offset >= 0))
 228                         hao = (struct ipv6_destopt_hao *)
 229                                         (skb_network_header(skb) + offset);
 230         }
 231
 232         skb_get_timestamp(skb, &stamp);
 233
 234         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 235                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 236                                   opt->iif))
 237                 goto out;
 238
 239         memset(&sel, 0, sizeof(sel));
 240         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 241                sizeof(sel.daddr));
 242         sel.prefixlen_d = 128;
 243         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 244                sizeof(sel.saddr));
 245         sel.prefixlen_s = 128;
 246         sel.family = AF_INET6;
 247         sel.proto = fl6->flowi6_proto;
 248         sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
 249         if (sel.dport)
 250                 sel.dport_mask = htons(~0);
 251         sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
 252         if (sel.sport)
 253                 sel.sport_mask = htons(~0);
 254         sel.ifindex = fl6->flowi6_oif;
 255
 256         err = km_report(net, IPPROTO_DSTOPTS, &sel,
 257                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 258
 259  out:
 260         return err;
 261 }
 262
 263 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 264                                u8 **nexthdr)
 265 {
 266         u16 offset = sizeof(struct ipv6hdr);
 267         struct ipv6_opt_hdr *exthdr =
 268                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 269         const unsigned char *nh = skb_network_header(skb);
 270         unsigned int packet_len = skb_tail_pointer(skb) -
 271                 skb_network_header(skb);
 272         int found_rhdr = 0;
 273
 274         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 275
 276         while (offset + 1 <= packet_len) {
 277
 278                 switch (**nexthdr) {
 279                 case NEXTHDR_HOP:
 280                         break;
 281                 case NEXTHDR_ROUTING:
 282                         found_rhdr = 1;
 283                         break;
 284                 case NEXTHDR_DEST:
 285                         /*
 286                          * HAO MUST NOT appear more than once.
 287                          * XXX: It is better to try to find by the end of
 288                          * XXX: packet if HAO exists.
 289                          */
 290                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 291                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 292                                 return offset;
 293                         }
 294
 295                         if (found_rhdr)
 296                                 return offset;
 297
 298                         break;
 299                 default:
 300                         return offset;
 301                 }
 302
 303                 offset += ipv6_optlen(exthdr);
 304                 *nexthdr = &exthdr->nexthdr;
 305                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 306         }
 307
 308         return offset;
 309 }
 310
 311 static int mip6_destopt_init_state(struct xfrm_state *x)
 312 {
 313         if (x->id.spi) {
 314                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
 315                 return -EINVAL;
 316         }
 317         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 318                 pr_info("%s: state's mode is not %u: %u\n",
 319                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 320                 return -EINVAL;
 321         }
 322
 323         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 324                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 325                 sizeof(struct ipv6_destopt_hao);
 326         WARN_ON(x->props.header_len != 24);
 327
 328         return 0;
 329 }
 330
 331 /*
 332  * Do nothing about destroying since it has no specific operation for
 333  * destination options header unlike IPsec protocols.
 334  */
 335 static void mip6_destopt_destroy(struct xfrm_state *x)
 336 {
 337 }
 338
 339 static const struct xfrm_type mip6_destopt_type = {
 340         .description    = "MIP6DESTOPT",
 341         .owner          = THIS_MODULE,
 342         .proto          = IPPROTO_DSTOPTS,
 343         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
 344         .init_state     = mip6_destopt_init_state,
 345         .destructor     = mip6_destopt_destroy,
 346         .input          = mip6_destopt_input,
 347         .output         = mip6_destopt_output,
 348         .reject         = mip6_destopt_reject,
 349         .hdr_offset     = mip6_destopt_offset,
 350 };
 351
 352 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 353 {
 354         const struct ipv6hdr *iph = ipv6_hdr(skb);
 355         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 356         int err = rt2->rt_hdr.nexthdr;
 357
 358         spin_lock(&x->lock);
 359         if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
 360             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 361                 err = -ENOENT;
 362         spin_unlock(&x->lock);
 363
 364         return err;
 365 }
 366
 367 /* Routing Header type 2 is inserted.
 368  * IP Header's dst address is replaced with Routing Header's Home Address.
 369  */
 370 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 371 {
 372         struct ipv6hdr *iph;
 373         struct rt2_hdr *rt2;
 374         u8 nexthdr;
 375
 376         skb_push(skb, -skb_network_offset(skb));
 377         iph = ipv6_hdr(skb);
 378
 379         nexthdr = *skb_mac_header(skb);
 380         *skb_mac_header(skb) = IPPROTO_ROUTING;
 381
 382         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 383         rt2->rt_hdr.nexthdr = nexthdr;
 384         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 385         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 386         rt2->rt_hdr.segments_left = 1;
 387         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 388
 389         WARN_ON(rt2->rt_hdr.hdrlen != 2);
 390
 391         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 392         spin_lock_bh(&x->lock);
 393         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 394         spin_unlock_bh(&x->lock);
 395
 396         return 0;
 397 }
 398
 399 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 400                              u8 **nexthdr)
 401 {
 402         u16 offset = sizeof(struct ipv6hdr);
 403         struct ipv6_opt_hdr *exthdr =
 404                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 405         const unsigned char *nh = skb_network_header(skb);
 406         unsigned int packet_len = skb_tail_pointer(skb) -
 407                 skb_network_header(skb);
 408         int found_rhdr = 0;
 409
 410         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 411
 412         while (offset + 1 <= packet_len) {
 413
 414                 switch (**nexthdr) {
 415                 case NEXTHDR_HOP:
 416                         break;
 417                 case NEXTHDR_ROUTING:
 418                         if (offset + 3 <= packet_len) {
 419                                 struct ipv6_rt_hdr *rt;
 420                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 421                                 if (rt->type != 0)
 422                                         return offset;
 423                         }
 424                         found_rhdr = 1;
 425                         break;
 426                 case NEXTHDR_DEST:
 427                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 428                                 return offset;
 429
 430                         if (found_rhdr)
 431                                 return offset;
 432
 433                         break;
 434                 default:
 435                         return offset;
 436                 }
 437
 438                 offset += ipv6_optlen(exthdr);
 439                 *nexthdr = &exthdr->nexthdr;
 440                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 441         }
 442
 443         return offset;
 444 }
 445
 446 static int mip6_rthdr_init_state(struct xfrm_state *x)
 447 {
 448         if (x->id.spi) {
 449                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
 450                 return -EINVAL;
 451         }
 452         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 453                 pr_info("%s: state's mode is not %u: %u\n",
 454                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 455                 return -EINVAL;
 456         }
 457
 458         x->props.header_len = sizeof(struct rt2_hdr);
 459
 460         return 0;
 461 }
 462
 463 /*
 464  * Do nothing about destroying since it has no specific operation for routing
 465  * header type 2 unlike IPsec protocols.
 466  */
 467 static void mip6_rthdr_destroy(struct xfrm_state *x)
 468 {
 469 }
 470
 471 static const struct xfrm_type mip6_rthdr_type = {
 472         .description    = "MIP6RT",
 473         .owner          = THIS_MODULE,
 474         .proto          = IPPROTO_ROUTING,
 475         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
 476         .init_state     = mip6_rthdr_init_state,
 477         .destructor     = mip6_rthdr_destroy,
 478         .input          = mip6_rthdr_input,
 479         .output         = mip6_rthdr_output,
 480         .hdr_offset     = mip6_rthdr_offset,
 481 };
 482
 483 static int __init mip6_init(void)
 484 {
 485         pr_info("Mobile IPv6\n");
 486
 487         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 488                 pr_info("%s: can't add xfrm type(destopt)\n", __func__);
 489                 goto mip6_destopt_xfrm_fail;
 490         }
 491         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 492                 pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
 493                 goto mip6_rthdr_xfrm_fail;
 494         }
 495         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 496                 pr_info("%s: can't add rawv6 mh filter\n", __func__);
 497                 goto mip6_rawv6_mh_fail;
 498         }
 499
 500
 501         return 0;
 502
 503  mip6_rawv6_mh_fail:
 504         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 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 static void __exit mip6_fini(void)
 512 {
 513         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 514                 pr_info("%s: can't remove rawv6 mh filter\n", __func__);
 515         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 516                 pr_info("%s: can't remove xfrm type(rthdr)\n", __func__);
 517         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 518                 pr_info("%s: can't remove xfrm type(destopt)\n", __func__);
 519 }
 520
 521 module_init(mip6_init);
 522 module_exit(mip6_fini);
 523
 524 MODULE_LICENSE("GPL");
 525 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 526 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);