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->h.raw - skb->data) + 8) ||
  94             !pskb_may_pull(skb, (skb->h.raw - skb->data) + ((skb->h.raw[1] + 1) << 3)))
  95                 return -1;
  96
  97         mh = (struct ip6_mh *)skb->h.raw;
  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, ((&mh->ip6mh_hdrlen) -
 103                                          skb_network_header(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, ((&mh->ip6mh_proto) -
 111                                          skb_network_header(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
 128 };
 129
 130 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 131 {
 132         struct ipv6hdr *iph = skb->nh.ipv6h;
 133         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 134
 135         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 136             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 137                 return -ENOENT;
 138
 139         return destopt->nexthdr;
 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         iph = (struct ipv6hdr *)skb->data;
 155         iph->payload_len = htons(skb->len - sizeof(*iph));
 156
 157         nexthdr = *skb_network_header(skb);
 158         *skb_network_header(skb) = IPPROTO_DSTOPTS;
 159
 160         dstopt = (struct ipv6_destopt_hdr *)skb->h.raw;
 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         hao->length = sizeof(*hao) - 2;
 168         BUG_TRAP(hao->length == 16);
 169
 170         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
 171
 172         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 173         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 174
 175         BUG_TRAP(len == x->props.header_len);
 176         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
 177
 178         return 0;
 179 }
 180
 181 static inline int mip6_report_rl_allow(struct timeval *stamp,
 182                                        struct in6_addr *dst,
 183                                        struct in6_addr *src, int iif)
 184 {
 185         int allow = 0;
 186
 187         spin_lock_bh(&mip6_report_rl.lock);
 188         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
 189             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
 190             mip6_report_rl.iif != iif ||
 191             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 192             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 193                 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_copy(&mip6_report_rl.src, src);
 197                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
 198                 allow = 1;
 199         }
 200         spin_unlock_bh(&mip6_report_rl.lock);
 201         return allow;
 202 }
 203
 204 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
 205 {
 206         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 207         struct ipv6_destopt_hao *hao = NULL;
 208         struct xfrm_selector sel;
 209         int offset;
 210         struct timeval stamp;
 211         int err = 0;
 212
 213         if (unlikely(fl->proto == IPPROTO_MH &&
 214                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
 215                 goto out;
 216
 217         if (likely(opt->dsthao)) {
 218                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 219                 if (likely(offset >= 0))
 220                         hao = (struct ipv6_destopt_hao *)
 221                                         (skb_network_header(skb) + offset);
 222         }
 223
 224         skb_get_timestamp(skb, &stamp);
 225
 226         if (!mip6_report_rl_allow(&stamp, &skb->nh.ipv6h->daddr,
 227                                   hao ? &hao->addr : &skb->nh.ipv6h->saddr,
 228                                   opt->iif))
 229                 goto out;
 230
 231         memset(&sel, 0, sizeof(sel));
 232         memcpy(&sel.daddr, (xfrm_address_t *)&skb->nh.ipv6h->daddr,
 233                sizeof(sel.daddr));
 234         sel.prefixlen_d = 128;
 235         memcpy(&sel.saddr, (xfrm_address_t *)&skb->nh.ipv6h->saddr,
 236                sizeof(sel.saddr));
 237         sel.prefixlen_s = 128;
 238         sel.family = AF_INET6;
 239         sel.proto = fl->proto;
 240         sel.dport = xfrm_flowi_dport(fl);
 241         if (sel.dport)
 242                 sel.dport_mask = htons(~0);
 243         sel.sport = xfrm_flowi_sport(fl);
 244         if (sel.sport)
 245                 sel.sport_mask = htons(~0);
 246         sel.ifindex = fl->oif;
 247
 248         err = km_report(IPPROTO_DSTOPTS, &sel,
 249                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
 250
 251  out:
 252         return err;
 253 }
 254
 255 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 256                                u8 **nexthdr)
 257 {
 258         u16 offset = sizeof(struct ipv6hdr);
 259         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 260         const unsigned char *nh = skb_network_header(skb);
 261         unsigned int packet_len = skb->tail - nh;
 262         int found_rhdr = 0;
 263
 264         *nexthdr = &skb->nh.ipv6h->nexthdr;
 265
 266         while (offset + 1 <= packet_len) {
 267
 268                 switch (**nexthdr) {
 269                 case NEXTHDR_HOP:
 270                         break;
 271                 case NEXTHDR_ROUTING:
 272                         found_rhdr = 1;
 273                         break;
 274                 case NEXTHDR_DEST:
 275                         /*
 276                          * HAO MUST NOT appear more than once.
 277                          * XXX: It is better to try to find by the end of
 278                          * XXX: packet if HAO exists.
 279                          */
 280                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
 281                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
 282                                 return offset;
 283                         }
 284
 285                         if (found_rhdr)
 286                                 return offset;
 287
 288                         break;
 289                 default:
 290                         return offset;
 291                 }
 292
 293                 offset += ipv6_optlen(exthdr);
 294                 *nexthdr = &exthdr->nexthdr;
 295                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 296         }
 297
 298         return offset;
 299 }
 300
 301 static int mip6_destopt_init_state(struct xfrm_state *x)
 302 {
 303         if (x->id.spi) {
 304                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 305                        x->id.spi);
 306                 return -EINVAL;
 307         }
 308         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 309                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 310                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 311                 return -EINVAL;
 312         }
 313
 314         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 315                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 316                 sizeof(struct ipv6_destopt_hao);
 317         BUG_TRAP(x->props.header_len == 24);
 318
 319         return 0;
 320 }
 321
 322 /*
 323  * Do nothing about destroying since it has no specific operation for
 324  * destination options header unlike IPsec protocols.
 325  */
 326 static void mip6_destopt_destroy(struct xfrm_state *x)
 327 {
 328 }
 329
 330 static struct xfrm_type mip6_destopt_type =
 331 {
 332         .description    = "MIP6DESTOPT",
 333         .owner          = THIS_MODULE,
 334         .proto          = IPPROTO_DSTOPTS,
 335         .flags          = XFRM_TYPE_NON_FRAGMENT,
 336         .init_state     = mip6_destopt_init_state,
 337         .destructor     = mip6_destopt_destroy,
 338         .input          = mip6_destopt_input,
 339         .output         = mip6_destopt_output,
 340         .reject         = mip6_destopt_reject,
 341         .hdr_offset     = mip6_destopt_offset,
 342         .local_addr     = mip6_xfrm_addr,
 343 };
 344
 345 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 346 {
 347         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 348
 349         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
 350             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 351                 return -ENOENT;
 352
 353         return rt2->rt_hdr.nexthdr;
 354 }
 355
 356 /* Routing Header type 2 is inserted.
 357  * IP Header's dst address is replaced with Routing Header's Home Address.
 358  */
 359 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 360 {
 361         struct ipv6hdr *iph;
 362         struct rt2_hdr *rt2;
 363         u8 nexthdr;
 364
 365         iph = (struct ipv6hdr *)skb->data;
 366         iph->payload_len = htons(skb->len - sizeof(*iph));
 367
 368         nexthdr = *skb_network_header(skb);
 369         *skb_network_header(skb) = IPPROTO_ROUTING;
 370
 371         rt2 = (struct rt2_hdr *)skb->h.raw;
 372         rt2->rt_hdr.nexthdr = nexthdr;
 373         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 374         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 375         rt2->rt_hdr.segments_left = 1;
 376         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 377
 378         BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
 379
 380         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 381         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 382
 383         return 0;
 384 }
 385
 386 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 387                              u8 **nexthdr)
 388 {
 389         u16 offset = sizeof(struct ipv6hdr);
 390         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
 391         const unsigned char *nh = skb_network_header(skb);
 392         unsigned int packet_len = skb->tail - nh;
 393         int found_rhdr = 0;
 394
 395         *nexthdr = &skb->nh.ipv6h->nexthdr;
 396
 397         while (offset + 1 <= packet_len) {
 398
 399                 switch (**nexthdr) {
 400                 case NEXTHDR_HOP:
 401                         break;
 402                 case NEXTHDR_ROUTING:
 403                         if (offset + 3 <= packet_len) {
 404                                 struct ipv6_rt_hdr *rt;
 405                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
 406                                 if (rt->type != 0)
 407                                         return offset;
 408                         }
 409                         found_rhdr = 1;
 410                         break;
 411                 case NEXTHDR_DEST:
 412                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 413                                 return offset;
 414
 415                         if (found_rhdr)
 416                                 return offset;
 417
 418                         break;
 419                 default:
 420                         return offset;
 421                 }
 422
 423                 offset += ipv6_optlen(exthdr);
 424                 *nexthdr = &exthdr->nexthdr;
 425                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 426         }
 427
 428         return offset;
 429 }
 430
 431 static int mip6_rthdr_init_state(struct xfrm_state *x)
 432 {
 433         if (x->id.spi) {
 434                 printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
 435                        x->id.spi);
 436                 return -EINVAL;
 437         }
 438         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 439                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
 440                        __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 441                 return -EINVAL;
 442         }
 443
 444         x->props.header_len = sizeof(struct rt2_hdr);
 445
 446         return 0;
 447 }
 448
 449 /*
 450  * Do nothing about destroying since it has no specific operation for routing
 451  * header type 2 unlike IPsec protocols.
 452  */
 453 static void mip6_rthdr_destroy(struct xfrm_state *x)
 454 {
 455 }
 456
 457 static struct xfrm_type mip6_rthdr_type =
 458 {
 459         .description    = "MIP6RT",
 460         .owner          = THIS_MODULE,
 461         .proto          = IPPROTO_ROUTING,
 462         .flags          = XFRM_TYPE_NON_FRAGMENT,
 463         .init_state     = mip6_rthdr_init_state,
 464         .destructor     = mip6_rthdr_destroy,
 465         .input          = mip6_rthdr_input,
 466         .output         = mip6_rthdr_output,
 467         .hdr_offset     = mip6_rthdr_offset,
 468         .remote_addr    = mip6_xfrm_addr,
 469 };
 470
 471 int __init mip6_init(void)
 472 {
 473         printk(KERN_INFO "Mobile IPv6\n");
 474
 475         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 476                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
 477                 goto mip6_destopt_xfrm_fail;
 478         }
 479         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 480                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
 481                 goto mip6_rthdr_xfrm_fail;
 482         }
 483         return 0;
 484
 485  mip6_rthdr_xfrm_fail:
 486         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 487  mip6_destopt_xfrm_fail:
 488         return -EAGAIN;
 489 }
 490
 491 void __exit mip6_fini(void)
 492 {
 493         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 494                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
 495         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 496                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 497 }