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/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/xfrm.h>
  34 #include <net/mip6.h>
  35
  36 static xfrm_address_t *mip6_xfrm_addr(struct xfrm_state *x, xfrm_address_t *addr)
  37 {
  38         return x->coaddr;
  39 }
  40
  41 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  42 {
  43         return (n - len + 16) & 0x7;
  44 }
  45
  46 static inline void *mip6_padn(__u8 *data, __u8 padlen)
  47 {
  48         if (!data)
  49                 return NULL;
  50         if (padlen == 1) {
  51                 data[0] = MIP6_OPT_PAD_1;
  52         } else if (padlen > 1) {
  53                 data[0] = MIP6_OPT_PAD_N;
  54                 data[1] = padlen - 2;
  55                 if (padlen > 2)
  56                         memset(data+2, 0, data[1]);
  57         }
  58         return data + padlen;
  59 }
  60
  61 static inline void mip6_param_prob(struct sk_buff *skb, int code, int pos)
  62 {
  63         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
  64 }
  65
  66 static int mip6_mh_len(int type)
  67 {
  68         int len = 0;
  69
  70         switch (type) {
  71         case IP6_MH_TYPE_BRR:
  72                 len = 0;
  73                 break;
  74         case IP6_MH_TYPE_HOTI:
  75         case IP6_MH_TYPE_COTI:
  76         case IP6_MH_TYPE_BU:
  77         case IP6_MH_TYPE_BACK:
  78                 len = 1;
  79                 break;
  80         case IP6_MH_TYPE_HOT:
  81         case IP6_MH_TYPE_COT:
  82         case IP6_MH_TYPE_BERROR:
  83                 len = 2;
  84                 break;
  85         }
  86         return len;
  87 }
  88
  89 int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  90 {
  91         struct ip6_mh *mh;
  92
  93         if (!pskb_may_pull(skb, (skb_transport_offset(skb)) + 8) ||
  94             !pskb_may_pull(skb, (skb_transport_offset(skb) +
  95                                  ((skb_transport_header(skb)[1] + 1) << 3))))
  96                 return -1;
  97
  98         mh = (struct ip6_mh *)skb_transport_header(skb);
  99
 100         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
 101                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
 102                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
 103                 mip6_param_prob(skb, 0, ((&mh->ip6mh_hdrlen) -
 104                                          skb_network_header(skb)));
 105                 return -1;
 106         }
 107
 108         if (mh->ip6mh_proto != IPPROTO_NONE) {
 109                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
 110                                mh->ip6mh_proto);
 111                 mip6_param_prob(skb, 0, ((&mh->ip6mh_proto) -
 112                                          skb_network_header(skb)));
 113                 return -1;
 114         }
 115
 116         return 0;
 117 }
 118
 119 struct mip6_report_rate_limiter {
 120         spinlock_t lock;
 121         struct timeval 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         struct ipv6hdr *iph = ipv6_hdr(skb);
 134         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 135
 136         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 137             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 138                 return -ENOENT;
 139
 140         return destopt->nexthdr;
 141 }
 142
 143 /* Destination Option Header is inserted.
 144  * IP Header's src address is replaced with Home Address Option in
 145  * Destination Option Header.
 146  */
 147 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 148 {
 149         struct ipv6hdr *iph;
 150         struct ipv6_destopt_hdr *dstopt;
 151         struct ipv6_destopt_hao *hao;
 152         u8 nexthdr;
 153         int len;
 154
 155         iph = (struct ipv6hdr *)skb->data;
 156         iph->payload_len = htons(skb->len - sizeof(*iph));
 157
 158         nexthdr = *skb_network_header(skb);
 159         *skb_network_header(skb) = IPPROTO_DSTOPTS;
 160
 161         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 162         dstopt->nexthdr = nexthdr;
 163
 164         hao = mip6_padn((char *)(dstopt + 1),
 165                         calc_padlen(sizeof(*dstopt), 6));
 166
 167         hao->type = IPV6_TLV_HAO;
 168         hao->length = sizeof(*hao) - 2;
 169         BUG_TRAP(hao->length == 16);
 170
 171         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 172
 173         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 174         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 175
 176         BUG_TRAP(len == x->props.header_len);
 177         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 178
 179         return 0;
 180 }
 181
 182 static inline int mip6_report_rl_allow(struct timeval *stamp,
 183                                        struct in6_addr *dst,
 184                                        struct in6_addr *src, int iif)
 185 {
 186         int allow = 0;
 187
 188         spin_lock_bh(&mip6_report_rl.lock);
 189         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 190             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 191             mip6_report_rl.iif != iif ||
 192             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 193             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 194                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 195                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 196                 mip6_report_rl.iif = iif;
 197                 ipv6_addr_copy(&mip6_report_rl.src, src);
 198                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 199                 allow = 1;
 200         }
 201         spin_unlock_bh(&mip6_report_rl.lock);
 202         return allow;
 203 }
 204
 205 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 206 {
 207         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 208         struct ipv6_destopt_hao *hao = NULL;
 209         struct xfrm_selector sel;
 210         int offset;
 211         struct timeval stamp;
 212         int err = 0;
 213
 214         if (unlikely(fl->proto == IPPROTO_MH &&
 215                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 216                 goto out;
 217
 218         if (likely(opt->dsthao)) {
 219                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 220                 if (likely(offset >= 0))
 221                         hao = (struct ipv6_destopt_hao *)
 222                                         (skb_network_header(skb) + offset);
 223         }
 224
 225         skb_get_timestamp(skb, &stamp);
 226
 227         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 228                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 229                                   opt->iif))
 230                 goto out;
 231
 232         memset(&sel, 0, sizeof(sel));
 233         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 234                sizeof(sel.daddr));
 235         sel.prefixlen_d = 128;
 236         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 237                sizeof(sel.saddr));
 238         sel.prefixlen_s = 128;
 239         sel.family = AF_INET6;
 240         sel.proto = fl->proto;
 241         sel.dport = xfrm_flowi_dport(fl);
 242         if (sel.dport)
 243                 sel.dport_mask = htons(~0);
 244         sel.sport = xfrm_flowi_sport(fl);
 245         if (sel.sport)
 246                 sel.sport_mask = htons(~0);
 247         sel.ifindex = fl->oif;
 248
 249         err = km_report(IPPROTO_DSTOPTS, &sel,
 250                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 251
 252  out:
 253         return err;
 254 }
 255
 256 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 257                                u8 **nexthdr)
 258 {
 259         u16 offset = sizeof(struct ipv6hdr);
 260         struct ipv6_opt_hdr *exthdr =
 261                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 262         const unsigned char *nh = skb_network_header(skb);
 263         unsigned int packet_len = skb->tail - skb->network_header;
 264         int found_rhdr = 0;
 265
 266         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 267
 268         while (offset + 1 <= packet_len) {
 269
 270                 switch (**nexthdr) {
 271                 case NEXTHDR_HOP:
 272                         break;
 273                 case NEXTHDR_ROUTING:
 274                         found_rhdr = 1;
 275                         break;
 276                 case NEXTHDR_DEST:
 277                         /*
 278                          * HAO MUST NOT appear more than once.
 279                          * XXX: It is better to try to find by the end of
 280                          * XXX: packet if HAO exists.
 281                          */
 282                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 283                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 284                                 return offset;
 285                         }
 286
 287                         if (found_rhdr)
 288                                 return offset;
 289
 290                         break;
 291                 default:
 292                         return offset;
 293                 }
 294
 295                 offset += ipv6_optlen(exthdr);
 296                 *nexthdr = &exthdr->nexthdr;
 297                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 298         }
 299
 300         return offset;
 301 }
 302
 303 static int mip6_destopt_init_state(struct xfrm_state *x)
 304 {
 305         if (x->id.spi) {
 306                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 307                        x->id.spi);
 308                 return -EINVAL;
 309         }
 310         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 311                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 312                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 313                 return -EINVAL;
 314         }
 315
 316         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 317                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 318                 sizeof(struct ipv6_destopt_hao);
 319         BUG_TRAP(x->props.header_len == 24);
 320
 321         return 0;
 322 }
 323
 324 /*
 325  * Do nothing about destroying since it has no specific operation for
 326  * destination options header unlike IPsec protocols.
 327  */
 328 static void mip6_destopt_destroy(struct xfrm_state *x)
 329 {
 330 }
 331
 332 static struct xfrm_type mip6_destopt_type =
 333 {
 334         .description    = "MIP6DESTOPT",
 335         .owner          = THIS_MODULE,
 336         .proto          = IPPROTO_DSTOPTS,
 337         .flags          = XFRM_TYPE_NON_FRAGMENT,
 338         .init_state     = mip6_destopt_init_state,
 339         .destructor     = mip6_destopt_destroy,
 340         .input          = mip6_destopt_input,
 341         .output         = mip6_destopt_output,
 342         .reject         = mip6_destopt_reject,
 343         .hdr_offset     = mip6_destopt_offset,
 344         .local_addr     = mip6_xfrm_addr,
 345 };
 346
 347 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 348 {
 349         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 350
 351         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 352             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 353                 return -ENOENT;
 354
 355         return rt2->rt_hdr.nexthdr;
 356 }
 357
 358 /* Routing Header type 2 is inserted.
 359  * IP Header's dst address is replaced with Routing Header's Home Address.
 360  */
 361 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 362 {
 363         struct ipv6hdr *iph;
 364         struct rt2_hdr *rt2;
 365         u8 nexthdr;
 366
 367         iph = (struct ipv6hdr *)skb->data;
 368         iph->payload_len = htons(skb->len - sizeof(*iph));
 369
 370         nexthdr = *skb_network_header(skb);
 371         *skb_network_header(skb) = IPPROTO_ROUTING;
 372
 373         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 374         rt2->rt_hdr.nexthdr = nexthdr;
 375         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 376         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 377         rt2->rt_hdr.segments_left = 1;
 378         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 379
 380         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 381
 382         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 383         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 384
 385         return 0;
 386 }
 387
 388 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 389                              u8 **nexthdr)
 390 {
 391         u16 offset = sizeof(struct ipv6hdr);
 392         struct ipv6_opt_hdr *exthdr =
 393                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 394         const unsigned char *nh = skb_network_header(skb);
 395         unsigned int packet_len = skb->tail - skb->network_header;
 396         int found_rhdr = 0;
 397
 398         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 399
 400         while (offset + 1 <= packet_len) {
 401
 402                 switch (**nexthdr) {
 403                 case NEXTHDR_HOP:
 404                         break;
 405                 case NEXTHDR_ROUTING:
 406                         if (offset + 3 <= packet_len) {
 407                                 struct ipv6_rt_hdr *rt;
 408                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 409                                 if (rt->type != 0)
 410                                         return offset;
 411                         }
 412                         found_rhdr = 1;
 413                         break;
 414                 case NEXTHDR_DEST:
 415                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 416                                 return offset;
 417
 418                         if (found_rhdr)
 419                                 return offset;
 420
 421                         break;
 422                 default:
 423                         return offset;
 424                 }
 425
 426                 offset += ipv6_optlen(exthdr);
 427                 *nexthdr = &exthdr->nexthdr;
 428                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 429         }
 430
 431         return offset;
 432 }
 433
 434 static int mip6_rthdr_init_state(struct xfrm_state *x)
 435 {
 436         if (x->id.spi) {
 437                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 438                        x->id.spi);
 439                 return -EINVAL;
 440         }
 441         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 442                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 443                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 444                 return -EINVAL;
 445         }
 446
 447         x->props.header_len = sizeof(struct rt2_hdr);
 448
 449         return 0;
 450 }
 451
 452 /*
 453  * Do nothing about destroying since it has no specific operation for routing
 454  * header type 2 unlike IPsec protocols.
 455  */
 456 static void mip6_rthdr_destroy(struct xfrm_state *x)
 457 {
 458 }
 459
 460 static struct xfrm_type mip6_rthdr_type =
 461 {
 462         .description    = "MIP6RT",
 463         .owner          = THIS_MODULE,
 464         .proto          = IPPROTO_ROUTING,
 465         .flags          = XFRM_TYPE_NON_FRAGMENT,
 466         .init_state     = mip6_rthdr_init_state,
 467         .destructor     = mip6_rthdr_destroy,
 468         .input          = mip6_rthdr_input,
 469         .output         = mip6_rthdr_output,
 470         .hdr_offset     = mip6_rthdr_offset,
 471         .remote_addr    = mip6_xfrm_addr,
 472 };
 473
 474 int __init mip6_init(void)
 475 {
 476         printk(KERN_INFO "Mobile IPv6\n");
 477
 478         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 479                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 480                 goto mip6_destopt_xfrm_fail;
 481         }
 482         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 483                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 484                 goto mip6_rthdr_xfrm_fail;
 485         }
 486         return 0;
 487
 488  mip6_rthdr_xfrm_fail:
 489         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 490  mip6_destopt_xfrm_fail:
 491         return -EAGAIN;
 492 }
 493
 494 void __exit mip6_fini(void)
 495 {
 496         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 497                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 498         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 499                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 500 }