bsd/netinet/ip_encap.c

   1 /*
   2  * Copyright (c) 2000-2016 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(struct mbuf *m, int off)
 173 {
 174         int proto;
 175         struct ip *ip;
 176         struct sockaddr_in s, d;
 177         const struct protosw *psw;
 178         struct encaptab *ep, *match;
 179         int prio, matchprio;
 180
 181 #ifndef __APPLE__
 182         va_start(ap, m);
 183         off = va_arg(ap, int);
 184         proto = va_arg(ap, int);
 185         va_end(ap);
 186 #endif
 187
 188         /* Expect 32-bit aligned data pointer on strict-align platforms */
 189         MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 190
 191         ip = mtod(m, struct ip *);
 192 #ifdef __APPLE__
 193         proto = ip->ip_p;
 194 #endif
 195
 196         bzero(&s, sizeof(s));
 197         s.sin_family = AF_INET;
 198         s.sin_len = sizeof(struct sockaddr_in);
 199         s.sin_addr = ip->ip_src;
 200         bzero(&d, sizeof(d));
 201         d.sin_family = AF_INET;
 202         d.sin_len = sizeof(struct sockaddr_in);
 203         d.sin_addr = ip->ip_dst;
 204
 205         match = NULL;
 206         matchprio = 0;
 207         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 208                 if (ep->af != AF_INET)
 209                         continue;
 210                 if (ep->proto >= 0 && ep->proto != proto)
 211                         continue;
 212                 if (ep->func)
 213                         prio = (*ep->func)(m, off, proto, ep->arg);
 214                 else {
 215                         /*
 216                          * it's inbound traffic, we need to match in reverse
 217                          * order
 218                          */
 219                         prio = mask_match(ep, (struct sockaddr *)&d,
 220                             (struct sockaddr *)&s);
 221                 }
 222
 223                 /*
 224                  * We prioritize the matches by using bit length of the
 225                  * matches.  mask_match() and user-supplied matching function
 226                  * should return the bit length of the matches (for example,
 227                  * if both src/dst are matched for IPv4, 64 should be returned).
 228                  * 0 or negative return value means "it did not match".
 229                  *
 230                  * The question is, since we have two "mask" portion, we
 231                  * cannot really define total order between entries.
 232                  * For example, which of these should be preferred?
 233                  * mask_match() returns 48 (32 + 16) for both of them.
 234                  *      src=3ffe::/16, dst=3ffe:501::/32
 235                  *      src=3ffe:501::/32, dst=3ffe::/16
 236                  *
 237                  * We need to loop through all the possible candidates
 238                  * to get the best match - the search takes O(n) for
 239                  * n attachments (i.e. interfaces).
 240                  */
 241                 if (prio <= 0)
 242                         continue;
 243                 if (prio > matchprio) {
 244                         matchprio = prio;
 245                         match = ep;
 246                 }
 247         }
 248
 249         if (match) {
 250                 /* found a match, "match" has the best one */
 251                 psw = (const struct protosw *)match->psw;
 252                 if (psw && psw->pr_input) {
 253                         encap_fillarg(m, match);
 254                         (*psw->pr_input)(m, off);
 255                 } else
 256                         m_freem(m);
 257                 return;
 258         }
 259
 260         /* last resort: inject to raw socket */
 261         rip_input(m, off);
 262 }
 263 #endif
 264
 265 #if INET6
 266 int
 267 encap6_input(struct mbuf **mp, int *offp, int proto)
 268 {
 269         struct mbuf *m = *mp;
 270         struct ip6_hdr *ip6;
 271         struct sockaddr_in6 s, d;
 272         const struct ip6protosw *psw;
 273         struct encaptab *ep, *match;
 274         int prio, matchprio;
 275
 276         /* Expect 32-bit aligned data pointer on strict-align platforms */
 277         MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 278
 279         ip6 = mtod(m, struct ip6_hdr *);
 280         bzero(&s, sizeof(s));
 281         s.sin6_family = AF_INET6;
 282         s.sin6_len = sizeof(struct sockaddr_in6);
 283         s.sin6_addr = ip6->ip6_src;
 284         bzero(&d, sizeof(d));
 285         d.sin6_family = AF_INET6;
 286         d.sin6_len = sizeof(struct sockaddr_in6);
 287         d.sin6_addr = ip6->ip6_dst;
 288
 289         match = NULL;
 290         matchprio = 0;
 291         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 292                 if (ep->af != AF_INET6)
 293                         continue;
 294                 if (ep->proto >= 0 && ep->proto != proto)
 295                         continue;
 296                 if (ep->func)
 297                         prio = (*ep->func)(m, *offp, proto, ep->arg);
 298                 else {
 299                         /*
 300                          * it's inbound traffic, we need to match in reverse
 301                          * order
 302                          */
 303                         prio = mask_match(ep, (struct sockaddr *)&d,
 304                             (struct sockaddr *)&s);
 305                 }
 306
 307                 /* see encap4_input() for issues here */
 308                 if (prio <= 0)
 309                         continue;
 310                 if (prio > matchprio) {
 311                         matchprio = prio;
 312                         match = ep;
 313                 }
 314         }
 315
 316         if (match) {
 317                 /* found a match */
 318                 psw = (const struct ip6protosw *)match->psw;
 319                 if (psw && psw->pr_input) {
 320                         encap_fillarg(m, match);
 321                         return (*psw->pr_input)(mp, offp, proto);
 322                 } else {
 323                         m_freem(m);
 324                         return IPPROTO_DONE;
 325                 }
 326         }
 327
 328         /* last resort: inject to raw socket */
 329         return rip6_input(mp, offp, proto);
 330 }
 331 #endif
 332
 333 static void
 334 encap_add(struct encaptab *ep)
 335 {
 336         LIST_INSERT_HEAD(&encaptab, ep, chain);
 337 }
 338
 339 /*
 340  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
 341  * length of mask (sm and dm) is assumed to be same as sp/dp.
 342  * Return value will be necessary as input (cookie) for encap_detach().
 343  */
 344 const struct encaptab *
 345 encap_attach(int af, int proto, const struct sockaddr *sp,
 346         const struct sockaddr *sm, const struct sockaddr *dp,
 347         const struct sockaddr *dm, const struct protosw *psw, void *arg)
 348 {
 349         struct encaptab *ep;
 350         int error;
 351
 352         /* sanity check on args */
 353         if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) {
 354                 error = EINVAL;
 355                 goto fail;
 356         }
 357         if (sp->sa_len != dp->sa_len) {
 358                 error = EINVAL;
 359                 goto fail;
 360         }
 361         if (af != sp->sa_family || af != dp->sa_family) {
 362                 error = EINVAL;
 363                 goto fail;
 364         }
 365
 366         /* check if anyone have already attached with exactly same config */
 367         for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
 368                 if (ep->af != af)
 369                         continue;
 370                 if (ep->proto != proto)
 371                         continue;
 372                 if (ep->src.ss_len != sp->sa_len ||
 373                     bcmp(&ep->src, sp, sp->sa_len) != 0 ||
 374                     bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
 375                         continue;
 376                 if (ep->dst.ss_len != dp->sa_len ||
 377                     bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
 378                     bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
 379                         continue;
 380
 381                 error = EEXIST;
 382                 goto fail;
 383         }
 384
 385         ep = _MALLOC(sizeof(*ep), M_NETADDR, M_WAITOK | M_ZERO); /* XXX */
 386         if (ep == NULL) {
 387                 error = ENOBUFS;
 388                 goto fail;
 389         }
 390
 391         ep->af = af;
 392         ep->proto = proto;
 393         bcopy(sp, &ep->src, sp->sa_len);
 394         bcopy(sm, &ep->srcmask, sp->sa_len);
 395         bcopy(dp, &ep->dst, dp->sa_len);
 396         bcopy(dm, &ep->dstmask, dp->sa_len);
 397         ep->psw = psw;
 398         ep->arg = arg;
 399
 400         encap_add(ep);
 401
 402         error = 0;
 403         return ep;
 404
 405 fail:
 406         return NULL;
 407 }
 408
 409 const struct encaptab *
 410 encap_attach_func( int af, int proto,
 411         int (*func)(const struct mbuf *, int, int, void *),
 412         const struct protosw *psw, void *arg)
 413 {
 414         struct encaptab *ep;
 415         int error;
 416
 417         /* sanity check on args */
 418         if (!func) {
 419                 error = EINVAL;
 420                 goto fail;
 421         }
 422
 423         ep = _MALLOC(sizeof(*ep), M_NETADDR, M_WAITOK | M_ZERO); /* XXX */
 424         if (ep == NULL) {
 425                 error = ENOBUFS;
 426                 goto fail;
 427         }
 428
 429         ep->af = af;
 430         ep->proto = proto;
 431         ep->func = func;
 432         ep->psw = psw;
 433         ep->arg = arg;
 434
 435         encap_add(ep);
 436
 437         error = 0;
 438         return ep;
 439
 440 fail:
 441         return NULL;
 442 }
 443
 444 int
 445 encap_detach(const struct encaptab *cookie)
 446 {
 447         const struct encaptab *ep = cookie;
 448         struct encaptab *p;
 449
 450         for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
 451                 if (p == ep) {
 452                         LIST_REMOVE(p, chain);
 453                         _FREE(p, M_NETADDR);    /*XXX*/
 454                         return 0;
 455                 }
 456         }
 457
 458         return EINVAL;
 459 }
 460
 461 static int
 462 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
 463         const struct sockaddr *dp)
 464 {
 465         struct sockaddr_storage s;
 466         struct sockaddr_storage d;
 467         int i;
 468         const u_int8_t *p, *q;
 469         u_int8_t *r;
 470         int matchlen;
 471
 472         if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
 473                 return 0;
 474         if (sp->sa_family != ep->af || dp->sa_family != ep->af)
 475                 return 0;
 476         if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
 477                 return 0;
 478
 479         matchlen = 0;
 480
 481         p = (const u_int8_t *)sp;
 482         q = (const u_int8_t *)&ep->srcmask;
 483         r = (u_int8_t *)&s;
 484         for (i = 0 ; i < sp->sa_len; i++) {
 485                 r[i] = p[i] & q[i];
 486                 /* XXX estimate */
 487                 matchlen += (q[i] ? 8 : 0);
 488         }
 489
 490         p = (const u_int8_t *)dp;
 491         q = (const u_int8_t *)&ep->dstmask;
 492         r = (u_int8_t *)&d;
 493         for (i = 0 ; i < dp->sa_len; i++) {
 494                 r[i] = p[i] & q[i];
 495                 /* XXX rough estimate */
 496                 matchlen += (q[i] ? 8 : 0);
 497         }
 498
 499         /* need to overwrite len/family portion as we don't compare them */
 500         s.ss_len = sp->sa_len;
 501         s.ss_family = sp->sa_family;
 502         d.ss_len = dp->sa_len;
 503         d.ss_family = dp->sa_family;
 504
 505         if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
 506             bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
 507                 return matchlen;
 508         } else
 509                 return 0;
 510 }
 511
 512 struct encaptabtag {
 513         void*                   *arg;
 514 };
 515
 516 static void
 517 encap_fillarg(
 518         struct mbuf *m,
 519         const struct encaptab *ep)
 520 {
 521         struct m_tag    *tag;
 522         struct encaptabtag *et;
 523
 524         tag = m_tag_create(KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_ENCAP,
 525                                           sizeof(struct encaptabtag), M_WAITOK, m);
 526
 527         if (tag != NULL) {
 528                 et = (struct encaptabtag*)(tag + 1);
 529                 et->arg = ep->arg;
 530                 m_tag_prepend(m, tag);
 531         }
 532 }
 533
 534 void *
 535 encap_getarg(struct mbuf *m)
 536 {
 537         struct m_tag    *tag;
 538         struct encaptabtag *et;
 539         void *p = NULL;
 540
 541         tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_ENCAP, NULL);
 542         if (tag) {
 543                 et = (struct encaptabtag*)(tag + 1);
 544                 p = et->arg;
 545                 m_tag_delete(m, tag);
 546         }
 547
 548         return p;
 549 }