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                 net_dbg_ratelimited("mip6: MH message too short: %d vs >=%d\n",
 101                                     mh->ip6mh_hdrlen,
 102                                     mip6_mh_len(mh->ip6mh_type));
 103                 mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
 104                                 skb_network_header_len(skb));
 105                 return -1;
 106         }
 107
 108         if (mh->ip6mh_proto != IPPROTO_NONE) {
 109                 net_dbg_ratelimited("mip6: MH invalid payload proto = %d\n",
 110                                     mh->ip6mh_proto);
 111                 mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
 112                                 skb_network_header_len(skb));
 113                 return -1;
 114         }
 115
 116         return 0;
 117 }
 118
 119 struct mip6_report_rate_limiter {
 120         spinlock_t lock;
 121         ktime_t stamp;
 122         int iif;
 123         struct in6_addr src;
 124         struct in6_addr dst;
 125 };
 126
 127 static struct mip6_report_rate_limiter mip6_report_rl = {
 128         .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
 129 };
 130
 131 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 132 {
 133         const struct ipv6hdr *iph = ipv6_hdr(skb);
 134         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 135         int err = destopt->nexthdr;
 136
 137         spin_lock(&x->lock);
 138         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 139             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 140                 err = -ENOENT;
 141         spin_unlock(&x->lock);
 142
 143         return err;
 144 }
 145
 146 /* Destination Option Header is inserted.
 147  * IP Header's src address is replaced with Home Address Option in
 148  * Destination Option Header.
 149  */
 150 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 151 {
 152         struct ipv6hdr *iph;
 153         struct ipv6_destopt_hdr *dstopt;
 154         struct ipv6_destopt_hao *hao;
 155         u8 nexthdr;
 156         int len;
 157
 158         skb_push(skb, -skb_network_offset(skb));
 159         iph = ipv6_hdr(skb);
 160
 161         nexthdr = *skb_mac_header(skb);
 162         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
 163
 164         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 165         dstopt->nexthdr = nexthdr;
 166
 167         hao = mip6_padn((char *)(dstopt + 1),
 168                         calc_padlen(sizeof(*dstopt), 6));
 169
 170         hao->type = IPV6_TLV_HAO;
 171         BUILD_BUG_ON(sizeof(*hao) != 18);
 172         hao->length = sizeof(*hao) - 2;
 173
 174         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 175
 176         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 177         spin_lock_bh(&x->lock);
 178         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 179         spin_unlock_bh(&x->lock);
 180
 181         WARN_ON(len != x->props.header_len);
 182         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 183
 184         return 0;
 185 }
 186
 187 static inline int mip6_report_rl_allow(ktime_t stamp,
 188                                        const struct in6_addr *dst,
 189                                        const struct in6_addr *src, int iif)
 190 {
 191         int allow = 0;
 192
 193         spin_lock_bh(&mip6_report_rl.lock);
 194         if (!ktime_equal(mip6_report_rl.stamp, stamp) ||
 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 = stamp;
 199                 mip6_report_rl.iif = iif;
 200                 mip6_report_rl.src = *src;
 201                 mip6_report_rl.dst = *dst;
 202                 allow = 1;
 203         }
 204         spin_unlock_bh(&mip6_report_rl.lock);
 205         return allow;
 206 }
 207
 208 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
 209                                const struct flowi *fl)
 210 {
 211         struct net *net = xs_net(x);
 212         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 213         const struct flowi6 *fl6 = &fl->u.ip6;
 214         struct ipv6_destopt_hao *hao = NULL;
 215         struct xfrm_selector sel;
 216         int offset;
 217         ktime_t stamp;
 218         int err = 0;
 219
 220         if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
 221                      fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
 222                 goto out;
 223
 224         if (likely(opt->dsthao)) {
 225                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 226                 if (likely(offset >= 0))
 227                         hao = (struct ipv6_destopt_hao *)
 228                                         (skb_network_header(skb) + offset);
 229         }
 230
 231         stamp = skb_get_ktime(skb);
 232
 233         if (!mip6_report_rl_allow(stamp, &ipv6_hdr(skb)->daddr,
 234                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 235                                   opt->iif))
 236                 goto out;
 237
 238         memset(&sel, 0, sizeof(sel));
 239         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 240                sizeof(sel.daddr));
 241         sel.prefixlen_d = 128;
 242         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 243                sizeof(sel.saddr));
 244         sel.prefixlen_s = 128;
 245         sel.family = AF_INET6;
 246         sel.proto = fl6->flowi6_proto;
 247         sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
 248         if (sel.dport)
 249                 sel.dport_mask = htons(~0);
 250         sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
 251         if (sel.sport)
 252                 sel.sport_mask = htons(~0);
 253         sel.ifindex = fl6->flowi6_oif;
 254
 255         err = km_report(net, IPPROTO_DSTOPTS, &sel,
 256                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 257
 258  out:
 259         return err;
 260 }
 261
 262 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 263                                u8 **nexthdr)
 264 {
 265         u16 offset = sizeof(struct ipv6hdr);
 266         struct ipv6_opt_hdr *exthdr =
 267                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 268         const unsigned char *nh = skb_network_header(skb);
 269         unsigned int packet_len = skb_tail_pointer(skb) -
 270                 skb_network_header(skb);
 271         int found_rhdr = 0;
 272
 273         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 274
 275         while (offset + 1 <= packet_len) {
 276
 277                 switch (**nexthdr) {
 278                 case NEXTHDR_HOP:
 279                         break;
 280                 case NEXTHDR_ROUTING:
 281                         found_rhdr = 1;
 282                         break;
 283                 case NEXTHDR_DEST:
 284                         /*
 285                          * HAO MUST NOT appear more than once.
 286                          * XXX: It is better to try to find by the end of
 287                          * XXX: packet if HAO exists.
 288                          */
 289                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 290                                 net_dbg_ratelimited("mip6: hao exists already, override\n");
 291                                 return offset;
 292                         }
 293
 294                         if (found_rhdr)
 295                                 return offset;
 296
 297                         break;
 298                 default:
 299                         return offset;
 300                 }
 301
 302                 offset += ipv6_optlen(exthdr);
 303                 *nexthdr = &exthdr->nexthdr;
 304                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 305         }
 306
 307         return offset;
 308 }
 309
 310 static int mip6_destopt_init_state(struct xfrm_state *x)
 311 {
 312         if (x->id.spi) {
 313                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
 314                 return -EINVAL;
 315         }
 316         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 317                 pr_info("%s: state's mode is not %u: %u\n",
 318                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 319                 return -EINVAL;
 320         }
 321
 322         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 323                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 324                 sizeof(struct ipv6_destopt_hao);
 325         WARN_ON(x->props.header_len != 24);
 326
 327         return 0;
 328 }
 329
 330 /*
 331  * Do nothing about destroying since it has no specific operation for
 332  * destination options header unlike IPsec protocols.
 333  */
 334 static void mip6_destopt_destroy(struct xfrm_state *x)
 335 {
 336 }
 337
 338 static const struct xfrm_type mip6_destopt_type = {
 339         .description    = "MIP6DESTOPT",
 340         .owner          = THIS_MODULE,
 341         .proto          = IPPROTO_DSTOPTS,
 342         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
 343         .init_state     = mip6_destopt_init_state,
 344         .destructor     = mip6_destopt_destroy,
 345         .input          = mip6_destopt_input,
 346         .output         = mip6_destopt_output,
 347         .reject         = mip6_destopt_reject,
 348         .hdr_offset     = mip6_destopt_offset,
 349 };
 350
 351 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 352 {
 353         const struct ipv6hdr *iph = ipv6_hdr(skb);
 354         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 355         int err = rt2->rt_hdr.nexthdr;
 356
 357         spin_lock(&x->lock);
 358         if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
 359             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 360                 err = -ENOENT;
 361         spin_unlock(&x->lock);
 362
 363         return err;
 364 }
 365
 366 /* Routing Header type 2 is inserted.
 367  * IP Header's dst address is replaced with Routing Header's Home Address.
 368  */
 369 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 370 {
 371         struct ipv6hdr *iph;
 372         struct rt2_hdr *rt2;
 373         u8 nexthdr;
 374
 375         skb_push(skb, -skb_network_offset(skb));
 376         iph = ipv6_hdr(skb);
 377
 378         nexthdr = *skb_mac_header(skb);
 379         *skb_mac_header(skb) = IPPROTO_ROUTING;
 380
 381         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 382         rt2->rt_hdr.nexthdr = nexthdr;
 383         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 384         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 385         rt2->rt_hdr.segments_left = 1;
 386         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 387
 388         WARN_ON(rt2->rt_hdr.hdrlen != 2);
 389
 390         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 391         spin_lock_bh(&x->lock);
 392         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 393         spin_unlock_bh(&x->lock);
 394
 395         return 0;
 396 }
 397
 398 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 399                              u8 **nexthdr)
 400 {
 401         u16 offset = sizeof(struct ipv6hdr);
 402         struct ipv6_opt_hdr *exthdr =
 403                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 404         const unsigned char *nh = skb_network_header(skb);
 405         unsigned int packet_len = skb_tail_pointer(skb) -
 406                 skb_network_header(skb);
 407         int found_rhdr = 0;
 408
 409         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 410
 411         while (offset + 1 <= packet_len) {
 412
 413                 switch (**nexthdr) {
 414                 case NEXTHDR_HOP:
 415                         break;
 416                 case NEXTHDR_ROUTING:
 417                         if (offset + 3 <= packet_len) {
 418                                 struct ipv6_rt_hdr *rt;
 419                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 420                                 if (rt->type != 0)
 421                                         return offset;
 422                         }
 423                         found_rhdr = 1;
 424                         break;
 425                 case NEXTHDR_DEST:
 426                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 427                                 return offset;
 428
 429                         if (found_rhdr)
 430                                 return offset;
 431
 432                         break;
 433                 default:
 434                         return offset;
 435                 }
 436
 437                 offset += ipv6_optlen(exthdr);
 438                 *nexthdr = &exthdr->nexthdr;
 439                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 440         }
 441
 442         return offset;
 443 }
 444
 445 static int mip6_rthdr_init_state(struct xfrm_state *x)
 446 {
 447         if (x->id.spi) {
 448                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
 449                 return -EINVAL;
 450         }
 451         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 452                 pr_info("%s: state's mode is not %u: %u\n",
 453                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 454                 return -EINVAL;
 455         }
 456
 457         x->props.header_len = sizeof(struct rt2_hdr);
 458
 459         return 0;
 460 }
 461
 462 /*
 463  * Do nothing about destroying since it has no specific operation for routing
 464  * header type 2 unlike IPsec protocols.
 465  */
 466 static void mip6_rthdr_destroy(struct xfrm_state *x)
 467 {
 468 }
 469
 470 static const struct xfrm_type mip6_rthdr_type = {
 471         .description    = "MIP6RT",
 472         .owner          = THIS_MODULE,
 473         .proto          = IPPROTO_ROUTING,
 474         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
 475         .init_state     = mip6_rthdr_init_state,
 476         .destructor     = mip6_rthdr_destroy,
 477         .input          = mip6_rthdr_input,
 478         .output         = mip6_rthdr_output,
 479         .hdr_offset     = mip6_rthdr_offset,
 480 };
 481
 482 static int __init mip6_init(void)
 483 {
 484         pr_info("Mobile IPv6\n");
 485
 486         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 487                 pr_info("%s: can't add xfrm type(destopt)\n", __func__);
 488                 goto mip6_destopt_xfrm_fail;
 489         }
 490         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 491                 pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
 492                 goto mip6_rthdr_xfrm_fail;
 493         }
 494         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 495                 pr_info("%s: can't add rawv6 mh filter\n", __func__);
 496                 goto mip6_rawv6_mh_fail;
 497         }
 498
 499
 500         return 0;
 501
 502  mip6_rawv6_mh_fail:
 503         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 504  mip6_rthdr_xfrm_fail:
 505         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 506  mip6_destopt_xfrm_fail:
 507         return -EAGAIN;
 508 }
 509
 510 static void __exit mip6_fini(void)
 511 {
 512         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 513                 pr_info("%s: can't remove rawv6 mh filter\n", __func__);
 514         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 515                 pr_info("%s: can't remove xfrm type(rthdr)\n", __func__);
 516         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 517                 pr_info("%s: can't remove xfrm type(destopt)\n", __func__);
 518 }
 519
 520 module_init(mip6_init);
 521 module_exit(mip6_fini);
 522
 523 MODULE_LICENSE("GPL");
 524 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 525 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);