bsd/netinet6/ah_output.c

   1 /*
   2  * Copyright (c) 2008-2011 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
  29 /*      $FreeBSD: src/sys/netinet6/ah_output.c,v 1.1.2.3 2001/07/03 11:01:49 ume Exp $  */
  30 /*      $KAME: ah_output.c,v 1.30 2001/02/21 00:50:53 itojun Exp $      */
  31
  32 /*
  33  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
  34  * All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions
  38  * are met:
  39  * 1. Redistributions of source code must retain the above copyright
  40  *    notice, this list of conditions and the following disclaimer.
  41  * 2. Redistributions in binary form must reproduce the above copyright
  42  *    notice, this list of conditions and the following disclaimer in the
  43  *    documentation and/or other materials provided with the distribution.
  44  * 3. Neither the name of the project nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61 /*
  62  * RFC1826/2402 authentication header.
  63  */
  64
  65 #define _IP_VHL
  66
  67 #include <sys/param.h>
  68 #include <sys/systm.h>
  69 #include <sys/malloc.h>
  70 #include <sys/mbuf.h>
  71 #include <sys/domain.h>
  72 #include <sys/protosw.h>
  73 #include <sys/socket.h>
  74 #include <sys/socketvar.h>
  75 #include <sys/errno.h>
  76 #include <sys/time.h>
  77 #include <sys/kernel.h>
  78 #include <sys/syslog.h>
  79
  80 #include <net/if.h>
  81 #include <net/route.h>
  82
  83 #include <netinet/in.h>
  84
  85 #include <netinet/in_systm.h>
  86 #include <netinet/ip.h>
  87 #include <netinet/in_var.h>
  88
  89 #if INET6
  90 #include <netinet/ip6.h>
  91 #include <netinet6/ip6_var.h>
  92 #include <netinet/icmp6.h>
  93 #endif
  94
  95 #include <netinet6/ipsec.h>
  96 #if INET6
  97 #include <netinet6/ipsec6.h>
  98 #endif
  99 #include <netinet6/ah.h>
 100 #if INET6
 101 #include <netinet6/ah6.h>
 102 #endif
 103 #include <netkey/key.h>
 104 #include <netkey/keydb.h>
 105
 106 #include <net/net_osdep.h>
 107
 108 #if INET
 109 static struct in_addr *ah4_finaldst(struct mbuf *);
 110 #endif
 111
 112 extern lck_mtx_t *sadb_mutex;
 113
 114 /*
 115  * compute AH header size.
 116  * transport mode only.  for tunnel mode, we should implement
 117  * virtual interface, and control MTU/MSS by the interface MTU.
 118  */
 119 size_t
 120 ah_hdrsiz(struct ipsecrequest *isr)
 121 {
 122         /* sanity check */
 123         if (isr == NULL) {
 124                 panic("ah_hdrsiz: NULL was passed.\n");
 125         }
 126
 127         if (isr->saidx.proto != IPPROTO_AH) {
 128                 panic("unsupported mode passed to ah_hdrsiz");
 129         }
 130
 131 #if 0
 132         {
 133                 lck_mtx_lock(sadb_mutex);
 134                 const struct ah_algorithm *algo;
 135                 size_t hdrsiz;
 136
 137                 /*%%%%% this needs to change - no sav in ipsecrequest any more */
 138                 if (isr->sav == NULL) {
 139                         goto estimate;
 140                 }
 141                 if (isr->sav->state != SADB_SASTATE_MATURE
 142                     && isr->sav->state != SADB_SASTATE_DYING) {
 143                         goto estimate;
 144                 }
 145
 146                 /* we need transport mode AH. */
 147                 algo = ah_algorithm_lookup(isr->sav->alg_auth);
 148                 if (!algo) {
 149                         goto estimate;
 150                 }
 151
 152                 /*
 153                  * XXX
 154                  * right now we don't calcurate the padding size.  simply
 155                  * treat the padding size as constant, for simplicity.
 156                  *
 157                  * XXX variable size padding support
 158                  */
 159                 hdrsiz = (((*algo->sumsiz)(isr->sav) + 3) & ~(4 - 1));
 160                 if (isr->sav->flags & SADB_X_EXT_OLD) {
 161                         hdrsiz += sizeof(struct ah);
 162                 } else {
 163                         hdrsiz += sizeof(struct newah);
 164                 }
 165
 166                 lck_mtx_unlock(sadb_mutex);
 167                 return hdrsiz;
 168         }
 169
 170 estimate:
 171 #endif
 172
 173         //lck_mtx_unlock(sadb_mutex);
 174         /* ASSUMING:
 175          *      sizeof(struct newah) > sizeof(struct ah).
 176          *      16 = (16 + 3) & ~(4 - 1).
 177          */
 178         return sizeof(struct newah) + 16;
 179 }
 180
 181 #if INET
 182 /*
 183  * Modify the packet so that it includes the authentication data.
 184  * The mbuf passed must start with IPv4 header.
 185  *
 186  * assumes that the first mbuf contains IPv4 header + option only.
 187  * the function does not modify m.
 188  */
 189 int
 190 ah4_output(struct mbuf *m, struct secasvar *sav)
 191 {
 192         const struct ah_algorithm *algo;
 193         u_int32_t spi;
 194         u_char *ahdrpos;
 195         u_char *ahsumpos = NULL;
 196         size_t hlen = 0;        /*IP header+option in bytes*/
 197         size_t plen = 0;        /*AH payload size in bytes*/
 198         size_t ahlen = 0;       /*plen + sizeof(ah)*/
 199         struct ip *ip;
 200         struct in_addr dst = { 0 };
 201         struct in_addr *finaldst;
 202         int error;
 203
 204         /* sanity checks */
 205         if ((sav->flags & SADB_X_EXT_OLD) == 0 && !sav->replay) {
 206                 ip = mtod(m, struct ip *);
 207                 ipseclog((LOG_DEBUG, "ah4_output: internal error: "
 208                     "sav->replay is null: %x->%x, SPI=%u\n",
 209                     (u_int32_t)ntohl(ip->ip_src.s_addr),
 210                     (u_int32_t)ntohl(ip->ip_dst.s_addr),
 211                     (u_int32_t)ntohl(sav->spi)));
 212                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 213                 m_freem(m);
 214                 return EINVAL;
 215         }
 216
 217         algo = ah_algorithm_lookup(sav->alg_auth);
 218         if (!algo) {
 219                 ipseclog((LOG_ERR, "ah4_output: unsupported algorithm: "
 220                     "SPI=%u\n", (u_int32_t)ntohl(sav->spi)));
 221                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 222                 m_freem(m);
 223                 return EINVAL;
 224         }
 225         spi = sav->spi;
 226
 227         /*
 228          * determine the size to grow.
 229          */
 230         if (sav->flags & SADB_X_EXT_OLD) {
 231                 /* RFC 1826 */
 232                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1); /*XXX pad to 8byte?*/
 233                 ahlen = plen + sizeof(struct ah);
 234         } else {
 235                 /* RFC 2402 */
 236                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1); /*XXX pad to 8byte?*/
 237                 ahlen = plen + sizeof(struct newah);
 238         }
 239
 240         /*
 241          * grow the mbuf to accomodate AH.
 242          */
 243         ip = mtod(m, struct ip *);
 244 #ifdef _IP_VHL
 245         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 246 #else
 247         hlen = ip->ip_hl << 2;
 248 #endif
 249
 250         if (m->m_len != hlen) {
 251                 panic("ah4_output: assumption failed (first mbuf length)");
 252         }
 253         if (M_LEADINGSPACE(m->m_next) < ahlen) {
 254                 struct mbuf *n;
 255                 MGET(n, M_DONTWAIT, MT_DATA);
 256                 if (!n) {
 257                         ipseclog((LOG_DEBUG, "ENOBUFS in ah4_output %d\n",
 258                             __LINE__));
 259                         m_freem(m);
 260                         return ENOBUFS;
 261                 }
 262                 n->m_len = ahlen;
 263                 n->m_next = m->m_next;
 264                 m->m_next = n;
 265                 m->m_pkthdr.len += ahlen;
 266                 ahdrpos = mtod(n, u_char *);
 267         } else {
 268                 m->m_next->m_len += ahlen;
 269                 m->m_next->m_data -= ahlen;
 270                 m->m_pkthdr.len += ahlen;
 271                 ahdrpos = mtod(m->m_next, u_char *);
 272         }
 273
 274         ip = mtod(m, struct ip *);      /*just to be sure*/
 275
 276         /*
 277          * initialize AH.
 278          */
 279         if (sav->flags & SADB_X_EXT_OLD) {
 280                 struct ah *ahdr;
 281
 282                 ahdr = (struct ah *)(void *)ahdrpos;
 283                 ahsumpos = (u_char *)(ahdr + 1);
 284                 ahdr->ah_len = plen >> 2;
 285                 ahdr->ah_nxt = ip->ip_p;
 286                 ahdr->ah_reserve = htons(0);
 287                 ahdr->ah_spi = spi;
 288                 bzero(ahdr + 1, plen);
 289         } else {
 290                 struct newah *ahdr;
 291
 292                 ahdr = (struct newah *)(void *)ahdrpos;
 293                 ahsumpos = (u_char *)(ahdr + 1);
 294                 ahdr->ah_len = (plen >> 2) + 1; /* plus one for seq# */
 295                 ahdr->ah_nxt = ip->ip_p;
 296                 ahdr->ah_reserve = htons(0);
 297                 ahdr->ah_spi = spi;
 298                 if (sav->replay->count == ~0) {
 299                         if ((sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
 300                                 /* XXX Is it noisy ? */
 301                                 ipseclog((LOG_WARNING,
 302                                     "replay counter overflowed. %s\n",
 303                                     ipsec_logsastr(sav)));
 304                                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 305                                 m_freem(m);
 306                                 return EINVAL;
 307                         }
 308                 }
 309                 lck_mtx_lock(sadb_mutex);
 310                 sav->replay->count++;
 311                 lck_mtx_unlock(sadb_mutex);
 312                 /*
 313                  * XXX sequence number must not be cycled, if the SA is
 314                  * installed by IKE daemon.
 315                  */
 316                 ahdr->ah_seq = htonl(sav->replay->count);
 317                 bzero(ahdr + 1, plen);
 318         }
 319
 320         /*
 321          * modify IPv4 header.
 322          */
 323         ip->ip_p = IPPROTO_AH;
 324         if (ahlen < (IP_MAXPACKET - ntohs(ip->ip_len))) {
 325                 ip->ip_len = htons(ntohs(ip->ip_len) + ahlen);
 326         } else {
 327                 ipseclog((LOG_ERR, "IPv4 AH output: size exceeds limit\n"));
 328                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 329                 m_freem(m);
 330                 return EMSGSIZE;
 331         }
 332
 333         /*
 334          * If there is source routing option, update destination field in
 335          * the IPv4 header to the final destination.
 336          * Note that we do not need to update source routing option itself
 337          * (as done in IPv4 AH processing -- see ip6_output()), since
 338          * source routing option is not part of the ICV computation.
 339          */
 340         finaldst = ah4_finaldst(m);
 341         if (finaldst) {
 342                 dst.s_addr = ip->ip_dst.s_addr;
 343                 ip->ip_dst.s_addr = finaldst->s_addr;
 344         }
 345
 346         /*
 347          * calcurate the checksum, based on security association
 348          * and the algorithm specified.
 349          */
 350         error = ah4_calccksum(m, (caddr_t)ahsumpos, plen, algo, sav);
 351         if (error) {
 352                 ipseclog((LOG_ERR,
 353                     "error after ah4_calccksum, called from ah4_output"));
 354                 m_freem(m);
 355                 m = NULL;
 356                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 357                 return error;
 358         }
 359
 360         if (finaldst) {
 361                 ip = mtod(m, struct ip *);      /*just to make sure*/
 362                 ip->ip_dst.s_addr = dst.s_addr;
 363         }
 364         lck_mtx_lock(sadb_stat_mutex);
 365         ipsecstat.out_success++;
 366         ipsecstat.out_ahhist[sav->alg_auth]++;
 367         lck_mtx_unlock(sadb_stat_mutex);
 368         key_sa_recordxfer(sav, m);
 369
 370         return 0;
 371 }
 372 #endif
 373
 374 /* Calculate AH length */
 375 int
 376 ah_hdrlen(struct secasvar *sav)
 377 {
 378         const struct ah_algorithm *algo;
 379         int plen, ahlen;
 380
 381         algo = ah_algorithm_lookup(sav->alg_auth);
 382         if (!algo) {
 383                 return 0;
 384         }
 385         if (sav->flags & SADB_X_EXT_OLD) {
 386                 /* RFC 1826 */
 387                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1);   /*XXX pad to 8byte?*/
 388                 ahlen = plen + sizeof(struct ah);
 389         } else {
 390                 /* RFC 2402 */
 391                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1);   /*XXX pad to 8byte?*/
 392                 ahlen = plen + sizeof(struct newah);
 393         }
 394
 395         return ahlen;
 396 }
 397
 398 #if INET6
 399 /*
 400  * Fill in the Authentication Header and calculate checksum.
 401  */
 402 int
 403 ah6_output(struct mbuf *m, u_char *nexthdrp, struct mbuf *md,
 404     struct secasvar *sav)
 405 {
 406         struct mbuf *mprev;
 407         struct mbuf *mah;
 408         const struct ah_algorithm *algo;
 409         u_int32_t spi;
 410         u_char *ahsumpos = NULL;
 411         size_t plen;    /*AH payload size in bytes*/
 412         int error = 0;
 413         int ahlen;
 414         struct ip6_hdr *ip6;
 415
 416         if (m->m_len < sizeof(struct ip6_hdr)) {
 417                 ipseclog((LOG_DEBUG, "ah6_output: first mbuf too short\n"));
 418                 m_freem(m);
 419                 return EINVAL;
 420         }
 421
 422         ahlen = ah_hdrlen(sav);
 423         if (ahlen == 0) {
 424                 return 0;
 425         }
 426
 427         for (mprev = m; mprev && mprev->m_next != md; mprev = mprev->m_next) {
 428                 ;
 429         }
 430         if (!mprev || mprev->m_next != md) {
 431                 ipseclog((LOG_DEBUG, "ah6_output: md is not in chain\n"));
 432                 m_freem(m);
 433                 return EINVAL;
 434         }
 435
 436         MGET(mah, M_DONTWAIT, MT_DATA);
 437         if (!mah) {
 438                 m_freem(m);
 439                 return ENOBUFS;
 440         }
 441         if (ahlen > MLEN) {
 442                 MCLGET(mah, M_DONTWAIT);
 443                 if ((mah->m_flags & M_EXT) == 0) {
 444                         m_free(mah);
 445                         m_freem(m);
 446                         return ENOBUFS;
 447                 }
 448         }
 449         mah->m_len = ahlen;
 450         mah->m_next = md;
 451         mprev->m_next = mah;
 452         m->m_pkthdr.len += ahlen;
 453
 454         /* fix plen */
 455         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) > IPV6_MAXPACKET) {
 456                 ipseclog((LOG_ERR,
 457                     "ip6_output: AH with IPv6 jumbogram is not supported\n"));
 458                 m_freem(m);
 459                 return EINVAL;
 460         }
 461         ip6 = mtod(m, struct ip6_hdr *);
 462         ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
 463
 464         if ((sav->flags & SADB_X_EXT_OLD) == 0 && !sav->replay) {
 465                 ipseclog((LOG_DEBUG, "ah6_output: internal error: "
 466                     "sav->replay is null: SPI=%u\n",
 467                     (u_int32_t)ntohl(sav->spi)));
 468                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 469                 m_freem(m);
 470                 return EINVAL;
 471         }
 472
 473         algo = ah_algorithm_lookup(sav->alg_auth);
 474         if (!algo) {
 475                 ipseclog((LOG_ERR, "ah6_output: unsupported algorithm: "
 476                     "SPI=%u\n", (u_int32_t)ntohl(sav->spi)));
 477                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 478                 m_freem(m);
 479                 return EINVAL;
 480         }
 481         spi = sav->spi;
 482
 483         /*
 484          * initialize AH.
 485          */
 486         if (sav->flags & SADB_X_EXT_OLD) {
 487                 struct ah *ahdr = mtod(mah, struct ah *);
 488
 489                 plen = mah->m_len - sizeof(struct ah);
 490                 ahsumpos = (u_char *)(ahdr + 1);
 491                 ahdr->ah_nxt = *nexthdrp;
 492                 *nexthdrp = IPPROTO_AH;
 493                 ahdr->ah_len = plen >> 2;
 494                 ahdr->ah_reserve = htons(0);
 495                 ahdr->ah_spi = spi;
 496                 bzero(ahdr + 1, plen);
 497         } else {
 498                 struct newah *ahdr = mtod(mah, struct newah *);
 499
 500                 plen = mah->m_len - sizeof(struct newah);
 501                 ahsumpos = (u_char *)(ahdr + 1);
 502                 ahdr->ah_nxt = *nexthdrp;
 503                 *nexthdrp = IPPROTO_AH;
 504                 ahdr->ah_len = (plen >> 2) + 1; /* plus one for seq# */
 505                 ahdr->ah_reserve = htons(0);
 506                 ahdr->ah_spi = spi;
 507                 if (sav->replay->count == ~0) {
 508                         if ((sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
 509                                 /* XXX Is it noisy ? */
 510                                 ipseclog((LOG_WARNING,
 511                                     "replay counter overflowed. %s\n",
 512                                     ipsec_logsastr(sav)));
 513                                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 514                                 m_freem(m);
 515                                 return EINVAL;
 516                         }
 517                 }
 518                 lck_mtx_lock(sadb_mutex);
 519                 sav->replay->count++;
 520                 lck_mtx_unlock(sadb_mutex);
 521                 /*
 522                  * XXX sequence number must not be cycled, if the SA is
 523                  * installed by IKE daemon.
 524                  */
 525                 ahdr->ah_seq = htonl(sav->replay->count);
 526                 bzero(ahdr + 1, plen);
 527         }
 528
 529         /*
 530          * calcurate the checksum, based on security association
 531          * and the algorithm specified.
 532          */
 533         error = ah6_calccksum(m, (caddr_t)ahsumpos, plen, algo, sav);
 534         if (error) {
 535                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 536                 m_freem(m);
 537         } else {
 538                 IPSEC_STAT_INCREMENT(ipsec6stat.out_success);
 539                 key_sa_recordxfer(sav, m);
 540         }
 541         IPSEC_STAT_INCREMENT(ipsec6stat.out_ahhist[sav->alg_auth]);
 542
 543         return error;
 544 }
 545 #endif
 546
 547 #if INET
 548 /*
 549  * Find the final destination if there is loose/strict source routing option.
 550  * Returns NULL if there's no source routing options.
 551  * Returns NULL on errors too.
 552  * Note that this function will return a pointer INTO the given parameter,
 553  * struct mbuf *m.
 554  * The mbuf must be pulled up toward, at least, ip option part.
 555  */
 556 static struct in_addr *
 557 ah4_finaldst(struct mbuf *m)
 558 {
 559         struct ip *ip;
 560         int optlen;
 561         u_char *q;
 562         int i;
 563         int hlen;
 564
 565         if (!m) {
 566                 panic("ah4_finaldst: m == NULL");
 567         }
 568         ip = mtod(m, struct ip *);
 569 #ifdef _IP_VHL
 570         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 571 #else
 572         hlen = ip->ip_hl << 2;
 573 #endif
 574
 575         if (m->m_len < hlen) {
 576                 ipseclog((LOG_DEBUG,
 577                     "ah4_finaldst: parameter mbuf wrong (not pulled up)\n"));
 578                 return NULL;
 579         }
 580
 581         if (hlen == sizeof(struct ip)) {
 582                 return NULL;
 583         }
 584
 585         optlen = hlen - sizeof(struct ip);
 586         if (optlen < 0) {
 587                 ipseclog((LOG_DEBUG, "ah4_finaldst: wrong optlen %d\n",
 588                     optlen));
 589                 return NULL;
 590         }
 591
 592         q = (u_char *)(ip + 1);
 593         i = 0;
 594         while (i < optlen) {
 595                 if (i + IPOPT_OPTVAL >= optlen) {
 596                         return NULL;
 597                 }
 598                 if (q[i + IPOPT_OPTVAL] == IPOPT_EOL ||
 599                     q[i + IPOPT_OPTVAL] == IPOPT_NOP ||
 600                     i + IPOPT_OLEN < optlen) {
 601                         ;
 602                 } else {
 603                         return NULL;
 604                 }
 605
 606                 switch (q[i + IPOPT_OPTVAL]) {
 607                 case IPOPT_EOL:
 608                         i = optlen;     /* bye */
 609                         break;
 610                 case IPOPT_NOP:
 611                         i++;
 612                         break;
 613                 case IPOPT_LSRR:
 614                 case IPOPT_SSRR:
 615                         if (q[i + IPOPT_OLEN] < 2 + sizeof(struct in_addr) ||
 616                             optlen - i < q[i + IPOPT_OLEN]) {
 617                                 ipseclog((LOG_ERR,
 618                                     "ip_finaldst: invalid IP option "
 619                                     "(code=%02x len=%02x)\n",
 620                                     q[i + IPOPT_OPTVAL], q[i + IPOPT_OLEN]));
 621                                 return NULL;
 622                         }
 623                         i += q[i + IPOPT_OLEN] - sizeof(struct in_addr);
 624                         return (struct in_addr *)(void *)(q + i);
 625                 default:
 626                         if (q[i + IPOPT_OLEN] < 2 ||
 627                             optlen - i < q[i + IPOPT_OLEN]) {
 628                                 ipseclog((LOG_ERR,
 629                                     "ip_finaldst: invalid IP option "
 630                                     "(code=%02x len=%02x)\n",
 631                                     q[i + IPOPT_OPTVAL], q[i + IPOPT_OLEN]));
 632                                 return NULL;
 633                         }
 634                         i += q[i + IPOPT_OLEN];
 635                         break;
 636                 }
 637         }
 638         return NULL;
 639 }
 640 #endif