linux/net/ipv6/mip6.c
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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27#include <linux/module.h>
  28#include <linux/skbuff.h>
  29#include <linux/time.h>
  30#include <linux/ipv6.h>
  31#include <linux/icmpv6.h>
  32#include <net/sock.h>
  33#include <net/ipv6.h>
  34#include <net/ip6_checksum.h>
  35#include <net/rawv6.h>
  36#include <net/xfrm.h>
  37#include <net/mip6.h>
  38
  39static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  40{
  41        return (n - len + 16) & 0x7;
  42}
  43
  44static inline void *mip6_padn(__u8 *data, __u8 padlen)
  45{
  46        if (!data)
  47                return NULL;
  48        if (padlen == 1) {
  49                data[0] = IPV6_TLV_PAD1;
  50        } else if (padlen > 1) {
  51                data[0] = IPV6_TLV_PADN;
  52                data[1] = padlen - 2;
  53                if (padlen > 2)
  54                        memset(data+2, 0, data[1]);
  55        }
  56        return data + padlen;
  57}
  58
  59static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
  60{
  61        icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
  62}
  63
  64static int mip6_mh_len(int type)
  65{
  66        int len = 0;
  67
  68        switch (type) {
  69        case IP6_MH_TYPE_BRR:
  70                len = 0;
  71                break;
  72        case IP6_MH_TYPE_HOTI:
  73        case IP6_MH_TYPE_COTI:
  74        case IP6_MH_TYPE_BU:
  75        case IP6_MH_TYPE_BACK:
  76                len = 1;
  77                break;
  78        case IP6_MH_TYPE_HOT:
  79        case IP6_MH_TYPE_COT:
  80        case IP6_MH_TYPE_BERROR:
  81                len = 2;
  82                break;
  83        }
  84        return len;
  85}
  86
  87static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
  88{
  89        struct ip6_mh _hdr;
  90        const struct ip6_mh *mh;
  91
  92        mh = skb_header_pointer(skb, skb_transport_offset(skb),
  93                                sizeof(_hdr), &_hdr);
  94        if (!mh)
  95                return -1;
  96
  97        if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
  98                return -1;
  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, 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                LIMIT_NETDEBUG(KERN_DEBUG "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
 119struct 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
 127static struct mip6_report_rate_limiter mip6_report_rl = {
 128        .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
 129};
 130
 131static 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 */
 150static 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
 187static inline int mip6_report_rl_allow(struct timeval *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 (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_equal(&mip6_report_rl.src, src) ||
 198            !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 199                mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
 200                mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
 201                mip6_report_rl.iif = iif;
 202                mip6_report_rl.src = *src;
 203                mip6_report_rl.dst = *dst;
 204                allow = 1;
 205        }
 206        spin_unlock_bh(&mip6_report_rl.lock);
 207        return allow;
 208}
 209
 210static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
 211                               const struct flowi *fl)
 212{
 213        struct net *net = xs_net(x);
 214        struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 215        const struct flowi6 *fl6 = &fl->u.ip6;
 216        struct ipv6_destopt_hao *hao = NULL;
 217        struct xfrm_selector sel;
 218        int offset;
 219        struct timeval stamp;
 220        int err = 0;
 221
 222        if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
 223                     fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
 224                goto out;
 225
 226        if (likely(opt->dsthao)) {
 227                offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 228                if (likely(offset >= 0))
 229                        hao = (struct ipv6_destopt_hao *)
 230                                        (skb_network_header(skb) + offset);
 231        }
 232
 233        skb_get_timestamp(skb, &stamp);
 234
 235        if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
 236                                  hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 237                                  opt->iif))
 238                goto out;
 239
 240        memset(&sel, 0, sizeof(sel));
 241        memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 242               sizeof(sel.daddr));
 243        sel.prefixlen_d = 128;
 244        memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 245               sizeof(sel.saddr));
 246        sel.prefixlen_s = 128;
 247        sel.family = AF_INET6;
 248        sel.proto = fl6->flowi6_proto;
 249        sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
 250        if (sel.dport)
 251                sel.dport_mask = htons(~0);
 252        sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
 253        if (sel.sport)
 254                sel.sport_mask = htons(~0);
 255        sel.ifindex = fl6->flowi6_oif;
 256
 257        err = km_report(net, IPPROTO_DSTOPTS, &sel,
 258                        (hao ? (xfrm_address_t *)&hao->addr : NULL));
 259
 260 out:
 261        return err;
 262}
 263
 264static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 265                               u8 **nexthdr)
 266{
 267        u16 offset = sizeof(struct ipv6hdr);
 268        struct ipv6_opt_hdr *exthdr =
 269                                   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 270        const unsigned char *nh = skb_network_header(skb);
 271        unsigned int packet_len = skb->tail - skb->network_header;
 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
 311static 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 */
 335static void mip6_destopt_destroy(struct xfrm_state *x)
 336{
 337}
 338
 339static const struct xfrm_type mip6_destopt_type =
 340{
 341        .description    = "MIP6DESTOPT",
 342        .owner          = THIS_MODULE,
 343        .proto          = IPPROTO_DSTOPTS,
 344        .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
 345        .init_state     = mip6_destopt_init_state,
 346        .destructor     = mip6_destopt_destroy,
 347        .input          = mip6_destopt_input,
 348        .output         = mip6_destopt_output,
 349        .reject         = mip6_destopt_reject,
 350        .hdr_offset     = mip6_destopt_offset,
 351};
 352
 353static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 354{
 355        const struct ipv6hdr *iph = ipv6_hdr(skb);
 356        struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 357        int err = rt2->rt_hdr.nexthdr;
 358
 359        spin_lock(&x->lock);
 360        if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
 361            !ipv6_addr_any((struct in6_addr *)x->coaddr))
 362                err = -ENOENT;
 363        spin_unlock(&x->lock);
 364
 365        return err;
 366}
 367
 368/* Routing Header type 2 is inserted.
 369 * IP Header's dst address is replaced with Routing Header's Home Address.
 370 */
 371static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 372{
 373        struct ipv6hdr *iph;
 374        struct rt2_hdr *rt2;
 375        u8 nexthdr;
 376
 377        skb_push(skb, -skb_network_offset(skb));
 378        iph = ipv6_hdr(skb);
 379
 380        nexthdr = *skb_mac_header(skb);
 381        *skb_mac_header(skb) = IPPROTO_ROUTING;
 382
 383        rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 384        rt2->rt_hdr.nexthdr = nexthdr;
 385        rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 386        rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 387        rt2->rt_hdr.segments_left = 1;
 388        memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 389
 390        WARN_ON(rt2->rt_hdr.hdrlen != 2);
 391
 392        memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 393        spin_lock_bh(&x->lock);
 394        memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 395        spin_unlock_bh(&x->lock);
 396
 397        return 0;
 398}
 399
 400static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 401                             u8 **nexthdr)
 402{
 403        u16 offset = sizeof(struct ipv6hdr);
 404        struct ipv6_opt_hdr *exthdr =
 405                                   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 406        const unsigned char *nh = skb_network_header(skb);
 407        unsigned int packet_len = skb->tail - skb->network_header;
 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
 446static 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 */
 467static void mip6_rthdr_destroy(struct xfrm_state *x)
 468{
 469}
 470
 471static const struct xfrm_type mip6_rthdr_type =
 472{
 473        .description    = "MIP6RT",
 474        .owner          = THIS_MODULE,
 475        .proto          = IPPROTO_ROUTING,
 476        .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
 477        .init_state     = mip6_rthdr_init_state,
 478        .destructor     = mip6_rthdr_destroy,
 479        .input          = mip6_rthdr_input,
 480        .output         = mip6_rthdr_output,
 481        .hdr_offset     = mip6_rthdr_offset,
 482};
 483
 484static int __init mip6_init(void)
 485{
 486        pr_info("Mobile IPv6\n");
 487
 488        if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 489                pr_info("%s: can't add xfrm type(destopt)\n", __func__);
 490                goto mip6_destopt_xfrm_fail;
 491        }
 492        if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 493                pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
 494                goto mip6_rthdr_xfrm_fail;
 495        }
 496        if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 497                pr_info("%s: can't add rawv6 mh filter\n", __func__);
 498                goto mip6_rawv6_mh_fail;
 499        }
 500
 501
 502        return 0;
 503
 504 mip6_rawv6_mh_fail:
 505        xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 506 mip6_rthdr_xfrm_fail:
 507        xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 508 mip6_destopt_xfrm_fail:
 509        return -EAGAIN;
 510}
 511
 512static void __exit mip6_fini(void)
 513{
 514        if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 515                pr_info("%s: can't remove rawv6 mh filter\n", __func__);
 516        if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
 517                pr_info("%s: can't remove xfrm type(rthdr)\n", __func__);
 518        if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
 519                pr_info("%s: can't remove xfrm type(destopt)\n", __func__);
 520}
 521
 522module_init(mip6_init);
 523module_exit(mip6_fini);
 524
 525MODULE_LICENSE("GPL");
 526MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 527MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
 528
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