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
 106 #if INET6
 107 #include <netinet/ip6.h>
 108 #include <netinet6/ip6_var.h>
 109 #include <netinet6/ip6protosw.h>
 110 #endif
 111
 112
 113 #include <net/net_osdep.h>
 114
 115 #ifndef __APPLE__
 116 #include <sys/kernel.h>
 117 #include <sys/malloc.h>
 118 MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
 119 #endif
 120
 121 static void encap_init(struct protosw *, struct domain *);
 122 static void encap_add(struct encaptab *);
 123 static int mask_match(const struct encaptab *, const struct sockaddr *,
 124                 const struct sockaddr *);
 125 static void encap_fillarg(struct mbuf *, const struct encaptab *);
 126
 127 #ifndef LIST_HEAD_INITIALIZER
 128 /* rely upon BSS initialization */
 129 LIST_HEAD(, encaptab) encaptab;
 130 #else
 131 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
 132 #endif
 133
 134 static void
 135 encap_init(struct protosw *pp, struct domain *dp)
 136 {
 137 #pragma unused(dp)
 138         static int encap_initialized = 0;
 139
 140         VERIFY((pp->pr_flags & (PR_INITIALIZED|PR_ATTACHED)) == PR_ATTACHED);
 141
 142         /* This gets called by more than one protocols, so initialize once */
 143         if (encap_initialized)
 144                 return;
 145         encap_initialized = 1;
 146 #if 0
 147         /*
 148          * we cannot use LIST_INIT() here, since drivers may want to call
 149          * encap_attach(), on driver attach.  encap_init() will be called
 150          * on AF_INET{,6} initialization, which happens after driver
 151          * initialization - using LIST_INIT() here can nuke encap_attach()
 152          * from drivers.
 153          */
 154         LIST_INIT(&encaptab);
 155 #endif
 156 }
 157
 158 void
 159 encap4_init(struct protosw *pp, struct domain *dp)
 160 {
 161         encap_init(pp, dp);
 162 }
 163
 164 void
 165 encap6_init(struct ip6protosw *pp, struct domain *dp)
 166 {
 167         encap_init((struct protosw *)pp, dp);
 168 }
 169
 170 #if INET
 171 void
 172 encap4_input(m, off)
 173         struct mbuf *m;
 174         int off;
 175 {
 176         int proto;
 177         struct ip *ip;
 178         struct sockaddr_in s, d;
 179         const struct protosw *psw;
 180         struct encaptab *ep, *match;
 181         int prio, matchprio;
 182
 183 #ifndef __APPLE__
 184         va_start(ap, m);
 185         off = va_arg(ap, int);
 186         proto = va_arg(ap, int);
 187         va_end(ap);
 188 #endif
 189
 190         /* Expect 32-bit aligned data pointer on strict-align platforms */
 191         MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 192
 193         ip = mtod(m, struct ip *);
 194 #ifdef __APPLE__
 195         proto = ip->ip_p;
 196 #endif
 197
 198         bzero(&s, sizeof(s));
 199         s.sin_family = AF_INET;
 200         s.sin_len = sizeof(struct sockaddr_in);
 201         s.sin_addr = ip->ip_src;
 202         bzero(&d, sizeof(d));
 203         d.sin_family = AF_INET;
 204         d.sin_len = sizeof(struct sockaddr_in);
 205         d.sin_addr = ip->ip_dst;
 206
 207         match = NULL;
 208         matchprio = 0;
 209         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 210                 if (ep->af != AF_INET)
 211                         continue;
 212                 if (ep->proto >= 0 && ep->proto != proto)
 213                         continue;
 214                 if (ep->func)
 215                         prio = (*ep->func)(m, off, proto, ep->arg);
 216                 else {
 217                         /*
 218                          * it's inbound traffic, we need to match in reverse
 219                          * order
 220                          */
 221                         prio = mask_match(ep, (struct sockaddr *)&d,
 222                             (struct sockaddr *)&s);
 223                 }
 224
 225                 /*
 226                  * We prioritize the matches by using bit length of the
 227                  * matches.  mask_match() and user-supplied matching function
 228                  * should return the bit length of the matches (for example,
 229                  * if both src/dst are matched for IPv4, 64 should be returned).
 230                  * 0 or negative return value means "it did not match".
 231                  *
 232                  * The question is, since we have two "mask" portion, we
 233                  * cannot really define total order between entries.
 234                  * For example, which of these should be preferred?
 235                  * mask_match() returns 48 (32 + 16) for both of them.
 236                  *      src=3ffe::/16, dst=3ffe:501::/32
 237                  *      src=3ffe:501::/32, dst=3ffe::/16
 238                  *
 239                  * We need to loop through all the possible candidates
 240                  * to get the best match - the search takes O(n) for
 241                  * n attachments (i.e. interfaces).
 242                  */
 243                 if (prio <= 0)
 244                         continue;
 245                 if (prio > matchprio) {
 246                         matchprio = prio;
 247                         match = ep;
 248                 }
 249         }
 250
 251         if (match) {
 252                 /* found a match, "match" has the best one */
 253                 psw = (const struct protosw *)match->psw;
 254                 if (psw && psw->pr_input) {
 255                         encap_fillarg(m, match);
 256                         (*psw->pr_input)(m, off);
 257                 } else
 258                         m_freem(m);
 259                 return;
 260         }
 261
 262         /* last resort: inject to raw socket */
 263         rip_input(m, off);
 264 }
 265 #endif
 266
 267 #if INET6
 268 int
 269 encap6_input(struct mbuf **mp, int *offp, int proto)
 270 {
 271         struct mbuf *m = *mp;
 272         struct ip6_hdr *ip6;
 273         struct sockaddr_in6 s, d;
 274         const struct ip6protosw *psw;
 275         struct encaptab *ep, *match;
 276         int prio, matchprio;
 277
 278         /* Expect 32-bit aligned data pointer on strict-align platforms */
 279         MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 280
 281         ip6 = mtod(m, struct ip6_hdr *);
 282         bzero(&s, sizeof(s));
 283         s.sin6_family = AF_INET6;
 284         s.sin6_len = sizeof(struct sockaddr_in6);
 285         s.sin6_addr = ip6->ip6_src;
 286         bzero(&d, sizeof(d));
 287         d.sin6_family = AF_INET6;
 288         d.sin6_len = sizeof(struct sockaddr_in6);
 289         d.sin6_addr = ip6->ip6_dst;
 290
 291         match = NULL;
 292         matchprio = 0;
 293         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 294                 if (ep->af != AF_INET6)
 295                         continue;
 296                 if (ep->proto >= 0 && ep->proto != proto)
 297                         continue;
 298                 if (ep->func)
 299                         prio = (*ep->func)(m, *offp, proto, ep->arg);
 300                 else {
 301                         /*
 302                          * it's inbound traffic, we need to match in reverse
 303                          * order
 304                          */
 305                         prio = mask_match(ep, (struct sockaddr *)&d,
 306                             (struct sockaddr *)&s);
 307                 }
 308
 309                 /* see encap4_input() for issues here */
 310                 if (prio <= 0)
 311                         continue;
 312                 if (prio > matchprio) {
 313                         matchprio = prio;
 314                         match = ep;
 315                 }
 316         }
 317
 318         if (match) {
 319                 /* found a match */
 320                 psw = (const struct ip6protosw *)match->psw;
 321                 if (psw && psw->pr_input) {
 322                         encap_fillarg(m, match);
 323                         return (*psw->pr_input)(mp, offp, proto);
 324                 } else {
 325                         m_freem(m);
 326                         return IPPROTO_DONE;
 327                 }
 328         }
 329
 330         /* last resort: inject to raw socket */
 331         return rip6_input(mp, offp, proto);
 332 }
 333 #endif
 334
 335 static void
 336 encap_add(ep)
 337         struct encaptab *ep;
 338 {
 339
 340         LIST_INSERT_HEAD(&encaptab, ep, chain);
 341 }
 342
 343 /*
 344  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
 345  * length of mask (sm and dm) is assumed to be same as sp/dp.
 346  * Return value will be necessary as input (cookie) for encap_detach().
 347  */
 348 const struct encaptab *
 349 encap_attach(af, proto, sp, sm, dp, dm, psw, arg)
 350         int af;
 351         int proto;
 352         const struct sockaddr *sp, *sm;
 353         const struct sockaddr *dp, *dm;
 354         const struct protosw *psw;
 355         void *arg;
 356 {
 357         struct encaptab *ep;
 358         int error;
 359
 360         /* sanity check on args */
 361         if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) {
 362                 error = EINVAL;
 363                 goto fail;
 364         }
 365         if (sp->sa_len != dp->sa_len) {
 366                 error = EINVAL;
 367                 goto fail;
 368         }
 369         if (af != sp->sa_family || af != dp->sa_family) {
 370                 error = EINVAL;
 371                 goto fail;
 372         }
 373
 374         /* check if anyone have already attached with exactly same config */
 375         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 376                 if (ep->af != af)
 377                         continue;
 378                 if (ep->proto != proto)
 379                         continue;
 380                 if (ep->src.ss_len != sp->sa_len ||
 381                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
 382                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
 383                         continue;
 384                 if (ep->dst.ss_len != dp->sa_len ||
 385                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
 386                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
 387                         continue;
 388
 389                 error = EEXIST;
 390                 goto fail;
 391         }
 392
 393         ep = _MALLOC(sizeof(*ep), M_NETADDR, M_WAITOK | M_ZERO); /* XXX */
 394         if (ep == NULL) {
 395                 error = ENOBUFS;
 396                 goto fail;
 397         }
 398
 399         ep->af = af;
 400         ep->proto = proto;
 401         bcopy(sp, &ep->src, sp->sa_len);
 402         bcopy(sm, &ep->srcmask, sp->sa_len);
 403         bcopy(dp, &ep->dst, dp->sa_len);
 404         bcopy(dm, &ep->dstmask, dp->sa_len);
 405         ep->psw = psw;
 406         ep->arg = arg;
 407
 408         encap_add(ep);
 409
 410         error = 0;
 411         return ep;
 412
 413 fail:
 414         return NULL;
 415 }
 416
 417 const struct encaptab *
 418 encap_attach_func(af, proto, func, psw, arg)
 419         int af;
 420         int proto;
 421         int (*func)(const struct mbuf *, int, int, void *);
 422         const struct protosw *psw;
 423         void *arg;
 424 {
 425         struct encaptab *ep;
 426         int error;
 427
 428         /* sanity check on args */
 429         if (!func) {
 430                 error = EINVAL;
 431                 goto fail;
 432         }
 433
 434         ep = _MALLOC(sizeof(*ep), M_NETADDR, M_WAITOK | M_ZERO); /* XXX */
 435         if (ep == NULL) {
 436                 error = ENOBUFS;
 437                 goto fail;
 438         }
 439
 440         ep->af = af;
 441         ep->proto = proto;
 442         ep->func = func;
 443         ep->psw = psw;
 444         ep->arg = arg;
 445
 446         encap_add(ep);
 447
 448         error = 0;
 449         return ep;
 450
 451 fail:
 452         return NULL;
 453 }
 454
 455 int
 456 encap_detach(cookie)
 457         const struct encaptab *cookie;
 458 {
 459         const struct encaptab *ep = cookie;
 460         struct encaptab *p;
 461
 462         for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
 463                 if (p == ep) {
 464                         LIST_REMOVE(p, chain);
 465                         _FREE(p, M_NETADDR);    /*XXX*/
 466                         return 0;
 467                 }
 468         }
 469
 470         return EINVAL;
 471 }
 472
 473 static int
 474 mask_match(ep, sp, dp)
 475         const struct encaptab *ep;
 476         const struct sockaddr *sp;
 477         const struct sockaddr *dp;
 478 {
 479         struct sockaddr_storage s;
 480         struct sockaddr_storage d;
 481         int i;
 482         const u_int8_t *p, *q;
 483         u_int8_t *r;
 484         int matchlen;
 485
 486         if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
 487                 return 0;
 488         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
 489                 return 0;
 490         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
 491                 return 0;
 492
 493         matchlen = 0;
 494
 495         p = (const u_int8_t *)sp;
 496         q = (const u_int8_t *)&ep->srcmask;
 497         r = (u_int8_t *)&s;
 498         for (i = 0 ; i < sp->sa_len; i++) {
 499                 r[i] = p[i] & q[i];
 500                 /* XXX estimate */
 501                 matchlen += (q[i] ? 8 : 0);
 502         }
 503
 504         p = (const u_int8_t *)dp;
 505         q = (const u_int8_t *)&ep->dstmask;
 506         r = (u_int8_t *)&d;
 507         for (i = 0 ; i < dp->sa_len; i++) {
 508                 r[i] = p[i] & q[i];
 509                 /* XXX rough estimate */
 510                 matchlen += (q[i] ? 8 : 0);
 511         }
 512
 513         /* need to overwrite len/family portion as we don't compare them */
 514         s.ss_len = sp->sa_len;
 515         s.ss_family = sp->sa_family;
 516         d.ss_len = dp->sa_len;
 517         d.ss_family = dp->sa_family;
 518
 519         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
 520             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
 521                 return matchlen;
 522         } else
 523                 return 0;
 524 }
 525
 526 struct encaptabtag {
 527         void*                   *arg;
 528 };
 529
 530 static void
 531 encap_fillarg(
 532         struct mbuf *m,
 533         const struct encaptab *ep)
 534 {
 535         struct m_tag    *tag;
 536         struct encaptabtag *et;
 537
 538         tag = m_tag_create(KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_ENCAP,
 539                                           sizeof(struct encaptabtag), M_WAITOK, m);
 540
 541         if (tag != NULL) {
 542                 et = (struct encaptabtag*)(tag + 1);
 543                 et->arg = ep->arg;
 544                 m_tag_prepend(m, tag);
 545         }
 546 }
 547
 548 void *
 549 encap_getarg(m)
 550         struct mbuf *m;
 551 {
 552         struct m_tag    *tag;
 553         struct encaptabtag *et;
 554         void *p = NULL;
 555
 556         tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_ENCAP, NULL);
 557         if (tag) {
 558                 et = (struct encaptabtag*)(tag + 1);
 559                 p = et->arg;
 560                 m_tag_delete(m, tag);
 561         }
 562
 563         return p;
 564 }