bsd/netinet/ip_encap.c

   1 /*
   2  * Copyright (c) 2000-2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*      $FreeBSD: src/sys/netinet/ip_encap.c,v 1.1.2.2 2001/07/03 11:01:46 ume Exp $    */
  29 /*      $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $       */
  30
  31 /*
  32  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
  33  * All rights reserved.
  34  *
  35  * Redistribution and use in source and binary forms, with or without
  36  * modification, are permitted provided that the following conditions
  37  * are met:
  38  * 1. Redistributions of source code must retain the above copyright
  39  *    notice, this list of conditions and the following disclaimer.
  40  * 2. Redistributions in binary form must reproduce the above copyright
  41  *    notice, this list of conditions and the following disclaimer in the
  42  *    documentation and/or other materials provided with the distribution.
  43  * 3. Neither the name of the project nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  */
  59 /*
  60  * My grandfather said that there's a devil inside tunnelling technology...
  61  *
  62  * We have surprisingly many protocols that want packets with IP protocol
  63  * #4 or #41.  Here's a list of protocols that want protocol #41:
  64  *      RFC1933 configured tunnel
  65  *      RFC1933 automatic tunnel
  66  *      RFC2401 IPsec tunnel
  67  *      RFC2473 IPv6 generic packet tunnelling
  68  *      RFC2529 6over4 tunnel
  69  *      mobile-ip6 (uses RFC2473)
  70  *      6to4 tunnel
  71  * Here's a list of protocol that want protocol #4:
  72  *      RFC1853 IPv4-in-IPv4 tunnelling
  73  *      RFC2003 IPv4 encapsulation within IPv4
  74  *      RFC2344 reverse tunnelling for mobile-ip4
  75  *      RFC2401 IPsec tunnel
  76  * Well, what can I say.  They impose different en/decapsulation mechanism
  77  * from each other, so they need separate protocol handler.  The only one
  78  * we can easily determine by protocol # is IPsec, which always has
  79  * AH/ESP/IPComp header right after outer IP header.
  80  *
  81  * So, clearly good old protosw does not work for protocol #4 and #41.
  82  * The code will let you match protocol via src/dst address pair.
  83  */
  84 /* XXX is M_NETADDR correct? */
  85
  86 #include <sys/param.h>
  87 #include <sys/systm.h>
  88 #include <sys/socket.h>
  89 #include <sys/sockio.h>
  90 #include <sys/mbuf.h>
  91 #include <sys/mcache.h>
  92 #include <sys/errno.h>
  93 #include <sys/domain.h>
  94 #include <sys/protosw.h>
  95 #include <sys/queue.h>
  96
  97 #include <net/if.h>
  98 #include <net/route.h>
  99
 100 #include <netinet/in.h>
 101 #include <netinet/in_systm.h>
 102 #include <netinet/ip.h>
 103 #include <netinet/ip_var.h>
 104 #include <netinet/ip_encap.h>
 105 #if MROUTING
 106 #include <netinet/ip_mroute.h>
 107 #endif /* MROUTING */
 108
 109 #if INET6
 110 #include <netinet/ip6.h>
 111 #include <netinet6/ip6_var.h>
 112 #include <netinet6/ip6protosw.h>
 113 #endif
 114
 115
 116 #include <net/net_osdep.h>
 117
 118 #ifndef __APPLE__
 119 #include <sys/kernel.h>
 120 #include <sys/malloc.h>
 121 MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
 122 #endif
 123
 124 static void encap_init(struct protosw *, struct domain *);
 125 static void encap_add(struct encaptab *);
 126 static int mask_match(const struct encaptab *, const struct sockaddr *,
 127                 const struct sockaddr *);
 128 static void encap_fillarg(struct mbuf *, const struct encaptab *);
 129
 130 #ifndef LIST_HEAD_INITIALIZER
 131 /* rely upon BSS initialization */
 132 LIST_HEAD(, encaptab) encaptab;
 133 #else
 134 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
 135 #endif
 136
 137 static void
 138 encap_init(struct protosw *pp, struct domain *dp)
 139 {
 140 #pragma unused(dp)
 141         static int encap_initialized = 0;
 142
 143         VERIFY((pp->pr_flags & (PR_INITIALIZED|PR_ATTACHED)) == PR_ATTACHED);
 144
 145         /* This gets called by more than one protocols, so initialize once */
 146         if (encap_initialized)
 147                 return;
 148         encap_initialized = 1;
 149 #if 0
 150         /*
 151          * we cannot use LIST_INIT() here, since drivers may want to call
 152          * encap_attach(), on driver attach.  encap_init() will be called
 153          * on AF_INET{,6} initialization, which happens after driver
 154          * initialization - using LIST_INIT() here can nuke encap_attach()
 155          * from drivers.
 156          */
 157         LIST_INIT(&encaptab);
 158 #endif
 159 }
 160
 161 void
 162 encap4_init(struct protosw *pp, struct domain *dp)
 163 {
 164         encap_init(pp, dp);
 165 }
 166
 167 void
 168 encap6_init(struct ip6protosw *pp, struct domain *dp)
 169 {
 170         encap_init((struct protosw *)pp, dp);
 171 }
 172
 173 #if INET
 174 void
 175 encap4_input(m, off)
 176         struct mbuf *m;
 177         int off;
 178 {
 179         int proto;
 180         struct ip *ip;
 181         struct sockaddr_in s, d;
 182         const struct protosw *psw;
 183         struct encaptab *ep, *match;
 184         int prio, matchprio;
 185
 186 #ifndef __APPLE__
 187         va_start(ap, m);
 188         off = va_arg(ap, int);
 189         proto = va_arg(ap, int);
 190         va_end(ap);
 191 #endif
 192
 193         /* Expect 32-bit aligned data pointer on strict-align platforms */
 194         MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 195
 196         ip = mtod(m, struct ip *);
 197 #ifdef __APPLE__
 198         proto = ip->ip_p;
 199 #endif
 200
 201         bzero(&s, sizeof(s));
 202         s.sin_family = AF_INET;
 203         s.sin_len = sizeof(struct sockaddr_in);
 204         s.sin_addr = ip->ip_src;
 205         bzero(&d, sizeof(d));
 206         d.sin_family = AF_INET;
 207         d.sin_len = sizeof(struct sockaddr_in);
 208         d.sin_addr = ip->ip_dst;
 209
 210         match = NULL;
 211         matchprio = 0;
 212         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 213                 if (ep->af != AF_INET)
 214                         continue;
 215                 if (ep->proto >= 0 && ep->proto != proto)
 216                         continue;
 217                 if (ep->func)
 218                         prio = (*ep->func)(m, off, proto, ep->arg);
 219                 else {
 220                         /*
 221                          * it's inbound traffic, we need to match in reverse
 222                          * order
 223                          */
 224                         prio = mask_match(ep, (struct sockaddr *)&d,
 225                             (struct sockaddr *)&s);
 226                 }
 227
 228                 /*
 229                  * We prioritize the matches by using bit length of the
 230                  * matches.  mask_match() and user-supplied matching function
 231                  * should return the bit length of the matches (for example,
 232                  * if both src/dst are matched for IPv4, 64 should be returned).
 233                  * 0 or negative return value means "it did not match".
 234                  *
 235                  * The question is, since we have two "mask" portion, we
 236                  * cannot really define total order between entries.
 237                  * For example, which of these should be preferred?
 238                  * mask_match() returns 48 (32 + 16) for both of them.
 239                  *      src=3ffe::/16, dst=3ffe:501::/32
 240                  *      src=3ffe:501::/32, dst=3ffe::/16
 241                  *
 242                  * We need to loop through all the possible candidates
 243                  * to get the best match - the search takes O(n) for
 244                  * n attachments (i.e. interfaces).
 245                  */
 246                 if (prio <= 0)
 247                         continue;
 248                 if (prio > matchprio) {
 249                         matchprio = prio;
 250                         match = ep;
 251                 }
 252         }
 253
 254         if (match) {
 255                 /* found a match, "match" has the best one */
 256                 psw = (const struct protosw *)match->psw;
 257                 if (psw && psw->pr_input) {
 258                         encap_fillarg(m, match);
 259                         (*psw->pr_input)(m, off);
 260                 } else
 261                         m_freem(m);
 262                 return;
 263         }
 264
 265         /* for backward compatibility */
 266 # if MROUTING
 267 #  define COMPATFUNC    ipip_input
 268 # endif /*MROUTING*/
 269
 270 #if COMPATFUNC
 271         if (proto == IPPROTO_IPV4) {
 272                 COMPATFUNC(m, off);
 273                 return;
 274         }
 275 #endif
 276
 277         /* last resort: inject to raw socket */
 278         rip_input(m, off);
 279 }
 280 #endif
 281
 282 #if INET6
 283 int
 284 encap6_input(struct mbuf **mp, int *offp, int proto)
 285 {
 286         struct mbuf *m = *mp;
 287         struct ip6_hdr *ip6;
 288         struct sockaddr_in6 s, d;
 289         const struct ip6protosw *psw;
 290         struct encaptab *ep, *match;
 291         int prio, matchprio;
 292
 293         /* Expect 32-bit aligned data pointer on strict-align platforms */
 294         MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 295
 296         ip6 = mtod(m, struct ip6_hdr *);
 297         bzero(&s, sizeof(s));
 298         s.sin6_family = AF_INET6;
 299         s.sin6_len = sizeof(struct sockaddr_in6);
 300         s.sin6_addr = ip6->ip6_src;
 301         bzero(&d, sizeof(d));
 302         d.sin6_family = AF_INET6;
 303         d.sin6_len = sizeof(struct sockaddr_in6);
 304         d.sin6_addr = ip6->ip6_dst;
 305
 306         match = NULL;
 307         matchprio = 0;
 308         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 309                 if (ep->af != AF_INET6)
 310                         continue;
 311                 if (ep->proto >= 0 && ep->proto != proto)
 312                         continue;
 313                 if (ep->func)
 314                         prio = (*ep->func)(m, *offp, proto, ep->arg);
 315                 else {
 316                         /*
 317                          * it's inbound traffic, we need to match in reverse
 318                          * order
 319                          */
 320                         prio = mask_match(ep, (struct sockaddr *)&d,
 321                             (struct sockaddr *)&s);
 322                 }
 323
 324                 /* see encap4_input() for issues here */
 325                 if (prio <= 0)
 326                         continue;
 327                 if (prio > matchprio) {
 328                         matchprio = prio;
 329                         match = ep;
 330                 }
 331         }
 332
 333         if (match) {
 334                 /* found a match */
 335                 psw = (const struct ip6protosw *)match->psw;
 336                 if (psw && psw->pr_input) {
 337                         encap_fillarg(m, match);
 338                         return (*psw->pr_input)(mp, offp, proto);
 339                 } else {
 340                         m_freem(m);
 341                         return IPPROTO_DONE;
 342                 }
 343         }
 344
 345         /* last resort: inject to raw socket */
 346         return rip6_input(mp, offp, proto);
 347 }
 348 #endif
 349
 350 static void
 351 encap_add(ep)
 352         struct encaptab *ep;
 353 {
 354
 355         LIST_INSERT_HEAD(&encaptab, ep, chain);
 356 }
 357
 358 /*
 359  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
 360  * length of mask (sm and dm) is assumed to be same as sp/dp.
 361  * Return value will be necessary as input (cookie) for encap_detach().
 362  */
 363 const struct encaptab *
 364 encap_attach(af, proto, sp, sm, dp, dm, psw, arg)
 365         int af;
 366         int proto;
 367         const struct sockaddr *sp, *sm;
 368         const struct sockaddr *dp, *dm;
 369         const struct protosw *psw;
 370         void *arg;
 371 {
 372         struct encaptab *ep;
 373         int error;
 374
 375         /* sanity check on args */
 376         if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) {
 377                 error = EINVAL;
 378                 goto fail;
 379         }
 380         if (sp->sa_len != dp->sa_len) {
 381                 error = EINVAL;
 382                 goto fail;
 383         }
 384         if (af != sp->sa_family || af != dp->sa_family) {
 385                 error = EINVAL;
 386                 goto fail;
 387         }
 388
 389         /* check if anyone have already attached with exactly same config */
 390         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 391                 if (ep->af != af)
 392                         continue;
 393                 if (ep->proto != proto)
 394                         continue;
 395                 if (ep->src.ss_len != sp->sa_len ||
 396                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
 397                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
 398                         continue;
 399                 if (ep->dst.ss_len != dp->sa_len ||
 400                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
 401                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
 402                         continue;
 403
 404                 error = EEXIST;
 405                 goto fail;
 406         }
 407
 408         ep = _MALLOC(sizeof(*ep), M_NETADDR, M_WAITOK); /*XXX*/
 409         if (ep == NULL) {
 410                 error = ENOBUFS;
 411                 goto fail;
 412         }
 413         bzero(ep, sizeof(*ep));
 414
 415         ep->af = af;
 416         ep->proto = proto;
 417         bcopy(sp, &ep->src, sp->sa_len);
 418         bcopy(sm, &ep->srcmask, sp->sa_len);
 419         bcopy(dp, &ep->dst, dp->sa_len);
 420         bcopy(dm, &ep->dstmask, dp->sa_len);
 421         ep->psw = psw;
 422         ep->arg = arg;
 423
 424         encap_add(ep);
 425
 426         error = 0;
 427         return ep;
 428
 429 fail:
 430         return NULL;
 431 }
 432
 433 const struct encaptab *
 434 encap_attach_func(af, proto, func, psw, arg)
 435         int af;
 436         int proto;
 437         int (*func)(const struct mbuf *, int, int, void *);
 438         const struct protosw *psw;
 439         void *arg;
 440 {
 441         struct encaptab *ep;
 442         int error;
 443
 444         /* sanity check on args */
 445         if (!func) {
 446                 error = EINVAL;
 447                 goto fail;
 448         }
 449
 450         ep = _MALLOC(sizeof(*ep), M_NETADDR, M_WAITOK); /*XXX*/
 451         if (ep == NULL) {
 452                 error = ENOBUFS;
 453                 goto fail;
 454         }
 455         bzero(ep, sizeof(*ep));
 456
 457         ep->af = af;
 458         ep->proto = proto;
 459         ep->func = func;
 460         ep->psw = psw;
 461         ep->arg = arg;
 462
 463         encap_add(ep);
 464
 465         error = 0;
 466         return ep;
 467
 468 fail:
 469         return NULL;
 470 }
 471
 472 int
 473 encap_detach(cookie)
 474         const struct encaptab *cookie;
 475 {
 476         const struct encaptab *ep = cookie;
 477         struct encaptab *p;
 478
 479         for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
 480                 if (p == ep) {
 481                         LIST_REMOVE(p, chain);
 482                         _FREE(p, M_NETADDR);    /*XXX*/
 483                         return 0;
 484                 }
 485         }
 486
 487         return EINVAL;
 488 }
 489
 490 static int
 491 mask_match(ep, sp, dp)
 492         const struct encaptab *ep;
 493         const struct sockaddr *sp;
 494         const struct sockaddr *dp;
 495 {
 496         struct sockaddr_storage s;
 497         struct sockaddr_storage d;
 498         int i;
 499         const u_int8_t *p, *q;
 500         u_int8_t *r;
 501         int matchlen;
 502
 503         if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
 504                 return 0;
 505         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
 506                 return 0;
 507         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
 508                 return 0;
 509
 510         matchlen = 0;
 511
 512         p = (const u_int8_t *)sp;
 513         q = (const u_int8_t *)&ep->srcmask;
 514         r = (u_int8_t *)&s;
 515         for (i = 0 ; i < sp->sa_len; i++) {
 516                 r[i] = p[i] & q[i];
 517                 /* XXX estimate */
 518                 matchlen += (q[i] ? 8 : 0);
 519         }
 520
 521         p = (const u_int8_t *)dp;
 522         q = (const u_int8_t *)&ep->dstmask;
 523         r = (u_int8_t *)&d;
 524         for (i = 0 ; i < dp->sa_len; i++) {
 525                 r[i] = p[i] & q[i];
 526                 /* XXX rough estimate */
 527                 matchlen += (q[i] ? 8 : 0);
 528         }
 529
 530         /* need to overwrite len/family portion as we don't compare them */
 531         s.ss_len = sp->sa_len;
 532         s.ss_family = sp->sa_family;
 533         d.ss_len = dp->sa_len;
 534         d.ss_family = dp->sa_family;
 535
 536         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
 537             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
 538                 return matchlen;
 539         } else
 540                 return 0;
 541 }
 542
 543 struct encaptabtag {
 544         void*                   *arg;
 545 };
 546
 547 static void
 548 encap_fillarg(
 549         struct mbuf *m,
 550         const struct encaptab *ep)
 551 {
 552         struct m_tag    *tag;
 553         struct encaptabtag *et;
 554
 555         tag = m_tag_create(KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_ENCAP,
 556                                           sizeof(struct encaptabtag), M_WAITOK, m);
 557
 558         if (tag != NULL) {
 559                 et = (struct encaptabtag*)(tag + 1);
 560                 et->arg = ep->arg;
 561                 m_tag_prepend(m, tag);
 562         }
 563 }
 564
 565 void *
 566 encap_getarg(m)
 567         struct mbuf *m;
 568 {
 569         struct m_tag    *tag;
 570         struct encaptabtag *et;
 571         void *p = NULL;
 572
 573         tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_ENCAP, NULL);
 574         if (tag) {
 575                 et = (struct encaptabtag*)(tag + 1);
 576                 p = et->arg;
 577                 m_tag_delete(m, tag);
 578         }
 579
 580         return p;
 581 }