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
 123         /* sanity check */
 124         if (isr == NULL)
 125                 panic("ah_hdrsiz: NULL was passed.\n");
 126
 127         if (isr->saidx.proto != IPPROTO_AH)
 128                 panic("unsupported mode passed to ah_hdrsiz");
 129
 130 #if 0
 131         {
 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                 if (isr->sav->state != SADB_SASTATE_MATURE
 141                  && isr->sav->state != SADB_SASTATE_DYING)
 142                         goto estimate;
 143
 144                 /* we need transport mode AH. */
 145                 algo = ah_algorithm_lookup(isr->sav->alg_auth);
 146                 if (!algo)
 147                         goto estimate;
 148
 149                 /*
 150                  * XXX
 151                  * right now we don't calcurate the padding size.  simply
 152                  * treat the padding size as constant, for simplicity.
 153                  *
 154                  * XXX variable size padding support
 155                  */
 156                 hdrsiz = (((*algo->sumsiz)(isr->sav) + 3) & ~(4 - 1));
 157                 if (isr->sav->flags & SADB_X_EXT_OLD)
 158                         hdrsiz += sizeof(struct ah);
 159                 else
 160                         hdrsiz += sizeof(struct newah);
 161
 162                 lck_mtx_unlock(sadb_mutex);
 163                 return hdrsiz;
 164         }
 165
 166 estimate:
 167 #endif
 168
 169     //lck_mtx_unlock(sadb_mutex);
 170         /* ASSUMING:
 171          *      sizeof(struct newah) > sizeof(struct ah).
 172          *      16 = (16 + 3) & ~(4 - 1).
 173          */
 174         return sizeof(struct newah) + 16;
 175 }
 176
 177 #if INET
 178 /*
 179  * Modify the packet so that it includes the authentication data.
 180  * The mbuf passed must start with IPv4 header.
 181  *
 182  * assumes that the first mbuf contains IPv4 header + option only.
 183  * the function does not modify m.
 184  */
 185 int
 186 ah4_output(struct mbuf *m, struct secasvar *sav)
 187 {
 188         const struct ah_algorithm *algo;
 189         u_int32_t spi;
 190         u_char *ahdrpos;
 191         u_char *ahsumpos = NULL;
 192         size_t hlen = 0;        /*IP header+option in bytes*/
 193         size_t plen = 0;        /*AH payload size in bytes*/
 194         size_t ahlen = 0;       /*plen + sizeof(ah)*/
 195         struct ip *ip;
 196         struct in_addr dst = { 0 };
 197         struct in_addr *finaldst;
 198         int error;
 199
 200         /* sanity checks */
 201         if ((sav->flags & SADB_X_EXT_OLD) == 0 && !sav->replay) {
 202                 ip = mtod(m, struct ip *);
 203                 ipseclog((LOG_DEBUG, "ah4_output: internal error: "
 204                         "sav->replay is null: %x->%x, SPI=%u\n",
 205                         (u_int32_t)ntohl(ip->ip_src.s_addr),
 206                         (u_int32_t)ntohl(ip->ip_dst.s_addr),
 207                         (u_int32_t)ntohl(sav->spi)));
 208                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 209                 m_freem(m);
 210                 return EINVAL;
 211         }
 212
 213         algo = ah_algorithm_lookup(sav->alg_auth);
 214         if (!algo) {
 215                 ipseclog((LOG_ERR, "ah4_output: unsupported algorithm: "
 216                     "SPI=%u\n", (u_int32_t)ntohl(sav->spi)));
 217                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 218                 m_freem(m);
 219                 return EINVAL;
 220         }
 221         spi = sav->spi;
 222
 223         /*
 224          * determine the size to grow.
 225          */
 226         if (sav->flags & SADB_X_EXT_OLD) {
 227                 /* RFC 1826 */
 228                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1); /*XXX pad to 8byte?*/
 229                 ahlen = plen + sizeof(struct ah);
 230         } else {
 231                 /* RFC 2402 */
 232                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1); /*XXX pad to 8byte?*/
 233                 ahlen = plen + sizeof(struct newah);
 234         }
 235
 236         /*
 237          * grow the mbuf to accomodate AH.
 238          */
 239         ip = mtod(m, struct ip *);
 240 #ifdef _IP_VHL
 241         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 242 #else
 243         hlen = ip->ip_hl << 2;
 244 #endif
 245
 246         if (m->m_len != hlen)
 247                 panic("ah4_output: assumption failed (first mbuf length)");
 248         if (M_LEADINGSPACE(m->m_next) < ahlen) {
 249                 struct mbuf *n;
 250                 MGET(n, M_DONTWAIT, MT_DATA);
 251                 if (!n) {
 252                         ipseclog((LOG_DEBUG, "ENOBUFS in ah4_output %d\n",
 253                             __LINE__));
 254                         m_freem(m);
 255                         return ENOBUFS;
 256                 }
 257                 n->m_len = ahlen;
 258                 n->m_next = m->m_next;
 259                 m->m_next = n;
 260                 m->m_pkthdr.len += ahlen;
 261                 ahdrpos = mtod(n, u_char *);
 262         } else {
 263                 m->m_next->m_len += ahlen;
 264                 m->m_next->m_data -= ahlen;
 265                 m->m_pkthdr.len += ahlen;
 266                 ahdrpos = mtod(m->m_next, u_char *);
 267         }
 268
 269         ip = mtod(m, struct ip *);      /*just to be sure*/
 270
 271         /*
 272          * initialize AH.
 273          */
 274         if (sav->flags & SADB_X_EXT_OLD) {
 275                 struct ah *ahdr;
 276
 277                 ahdr = (struct ah *)(void *)ahdrpos;
 278                 ahsumpos = (u_char *)(ahdr + 1);
 279                 ahdr->ah_len = plen >> 2;
 280                 ahdr->ah_nxt = ip->ip_p;
 281                 ahdr->ah_reserve = htons(0);
 282                 ahdr->ah_spi = spi;
 283                 bzero(ahdr + 1, plen);
 284         } else {
 285                 struct newah *ahdr;
 286
 287                 ahdr = (struct newah *)(void *)ahdrpos;
 288                 ahsumpos = (u_char *)(ahdr + 1);
 289                 ahdr->ah_len = (plen >> 2) + 1; /* plus one for seq# */
 290                 ahdr->ah_nxt = ip->ip_p;
 291                 ahdr->ah_reserve = htons(0);
 292                 ahdr->ah_spi = spi;
 293                 if (sav->replay->count == ~0) {
 294                         if ((sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
 295                                 /* XXX Is it noisy ? */
 296                                 ipseclog((LOG_WARNING,
 297                                     "replay counter overflowed. %s\n",
 298                                     ipsec_logsastr(sav)));
 299                                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 300                                 m_freem(m);
 301                                 return EINVAL;
 302                         }
 303                 }
 304                 lck_mtx_lock(sadb_mutex);
 305                 sav->replay->count++;
 306                 lck_mtx_unlock(sadb_mutex);
 307                 /*
 308                  * XXX sequence number must not be cycled, if the SA is
 309                  * installed by IKE daemon.
 310                  */
 311                 ahdr->ah_seq = htonl(sav->replay->count);
 312                 bzero(ahdr + 1, plen);
 313         }
 314
 315         /*
 316          * modify IPv4 header.
 317          */
 318         ip->ip_p = IPPROTO_AH;
 319         if (ahlen < (IP_MAXPACKET - ntohs(ip->ip_len)))
 320                 ip->ip_len = htons(ntohs(ip->ip_len) + ahlen);
 321         else {
 322                 ipseclog((LOG_ERR, "IPv4 AH output: size exceeds limit\n"));
 323                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 324                 m_freem(m);
 325                 return EMSGSIZE;
 326         }
 327
 328         /*
 329          * If there is source routing option, update destination field in
 330          * the IPv4 header to the final destination.
 331          * Note that we do not need to update source routing option itself
 332          * (as done in IPv4 AH processing -- see ip6_output()), since
 333          * source routing option is not part of the ICV computation.
 334          */
 335         finaldst = ah4_finaldst(m);
 336         if (finaldst) {
 337                 dst.s_addr = ip->ip_dst.s_addr;
 338                 ip->ip_dst.s_addr = finaldst->s_addr;
 339         }
 340
 341         /*
 342          * calcurate the checksum, based on security association
 343          * and the algorithm specified.
 344          */
 345         error = ah4_calccksum(m, (caddr_t)ahsumpos, plen, algo, sav);
 346         if (error) {
 347                 ipseclog((LOG_ERR,
 348                     "error after ah4_calccksum, called from ah4_output"));
 349                 m_freem(m);
 350                 m = NULL;
 351                 IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
 352                 return error;
 353         }
 354
 355         if (finaldst) {
 356                 ip = mtod(m, struct ip *);      /*just to make sure*/
 357                 ip->ip_dst.s_addr = dst.s_addr;
 358         }
 359         lck_mtx_lock(sadb_stat_mutex);
 360         ipsecstat.out_success++;
 361         ipsecstat.out_ahhist[sav->alg_auth]++;
 362         lck_mtx_unlock(sadb_stat_mutex);
 363         key_sa_recordxfer(sav, m);
 364
 365         return 0;
 366 }
 367 #endif
 368
 369 /* Calculate AH length */
 370 int
 371 ah_hdrlen(struct secasvar *sav)
 372 {
 373         const struct ah_algorithm *algo;
 374         int plen, ahlen;
 375
 376         algo = ah_algorithm_lookup(sav->alg_auth);
 377         if (!algo)
 378                 return 0;
 379         if (sav->flags & SADB_X_EXT_OLD) {
 380                 /* RFC 1826 */
 381                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1);   /*XXX pad to 8byte?*/
 382                 ahlen = plen + sizeof(struct ah);
 383         } else {
 384                 /* RFC 2402 */
 385                 plen = ((*algo->sumsiz)(sav) + 3) & ~(4 - 1);   /*XXX pad to 8byte?*/
 386                 ahlen = plen + sizeof(struct newah);
 387         }
 388
 389         return(ahlen);
 390 }
 391
 392 #if INET6
 393 /*
 394  * Fill in the Authentication Header and calculate checksum.
 395  */
 396 int
 397 ah6_output(struct mbuf *m, u_char *nexthdrp, struct mbuf *md,
 398            struct secasvar *sav)
 399 {
 400         struct mbuf *mprev;
 401         struct mbuf *mah;
 402         const struct ah_algorithm *algo;
 403         u_int32_t spi;
 404         u_char *ahsumpos = NULL;
 405         size_t plen;    /*AH payload size in bytes*/
 406         int error = 0;
 407         int ahlen;
 408         struct ip6_hdr *ip6;
 409
 410         if (m->m_len < sizeof(struct ip6_hdr)) {
 411                 ipseclog((LOG_DEBUG, "ah6_output: first mbuf too short\n"));
 412                 m_freem(m);
 413                 return EINVAL;
 414         }
 415
 416         ahlen = ah_hdrlen(sav);
 417         if (ahlen == 0)
 418                 return 0;
 419
 420         for (mprev = m; mprev && mprev->m_next != md; mprev = mprev->m_next)
 421                 ;
 422         if (!mprev || mprev->m_next != md) {
 423                 ipseclog((LOG_DEBUG, "ah6_output: md is not in chain\n"));
 424                 m_freem(m);
 425                 return EINVAL;
 426         }
 427
 428         MGET(mah, M_DONTWAIT, MT_DATA);
 429         if (!mah) {
 430                 m_freem(m);
 431                 return ENOBUFS;
 432         }
 433         if (ahlen > MLEN) {
 434                 MCLGET(mah, M_DONTWAIT);
 435                 if ((mah->m_flags & M_EXT) == 0) {
 436                         m_free(mah);
 437                         m_freem(m);
 438                         return ENOBUFS;
 439                 }
 440         }
 441         mah->m_len = ahlen;
 442         mah->m_next = md;
 443         mprev->m_next = mah;
 444         m->m_pkthdr.len += ahlen;
 445
 446         /* fix plen */
 447         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) > IPV6_MAXPACKET) {
 448                 ipseclog((LOG_ERR,
 449                     "ip6_output: AH with IPv6 jumbogram is not supported\n"));
 450                 m_freem(m);
 451                 return EINVAL;
 452         }
 453         ip6 = mtod(m, struct ip6_hdr *);
 454         ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
 455
 456         if ((sav->flags & SADB_X_EXT_OLD) == 0 && !sav->replay) {
 457                 ipseclog((LOG_DEBUG, "ah6_output: internal error: "
 458                           "sav->replay is null: SPI=%u\n",
 459                           (u_int32_t)ntohl(sav->spi)));
 460                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 461                 m_freem(m);
 462                 return EINVAL;
 463         }
 464
 465         algo = ah_algorithm_lookup(sav->alg_auth);
 466         if (!algo) {
 467                 ipseclog((LOG_ERR, "ah6_output: unsupported algorithm: "
 468                     "SPI=%u\n", (u_int32_t)ntohl(sav->spi)));
 469                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 470                 m_freem(m);
 471                 return EINVAL;
 472         }
 473         spi = sav->spi;
 474
 475         /*
 476          * initialize AH.
 477          */
 478         if (sav->flags & SADB_X_EXT_OLD) {
 479                 struct ah *ahdr = mtod(mah, struct ah *);
 480
 481                 plen = mah->m_len - sizeof(struct ah);
 482                 ahsumpos = (u_char *)(ahdr + 1);
 483                 ahdr->ah_nxt = *nexthdrp;
 484                 *nexthdrp = IPPROTO_AH;
 485                 ahdr->ah_len = plen >> 2;
 486                 ahdr->ah_reserve = htons(0);
 487                 ahdr->ah_spi = spi;
 488                 bzero(ahdr + 1, plen);
 489         } else {
 490                 struct newah *ahdr = mtod(mah, struct newah *);
 491
 492                 plen = mah->m_len - sizeof(struct newah);
 493                 ahsumpos = (u_char *)(ahdr + 1);
 494                 ahdr->ah_nxt = *nexthdrp;
 495                 *nexthdrp = IPPROTO_AH;
 496                 ahdr->ah_len = (plen >> 2) + 1; /* plus one for seq# */
 497                 ahdr->ah_reserve = htons(0);
 498                 ahdr->ah_spi = spi;
 499                 if (sav->replay->count == ~0) {
 500                         if ((sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
 501                                 /* XXX Is it noisy ? */
 502                                 ipseclog((LOG_WARNING,
 503                                      "replay counter overflowed. %s\n",
 504                                     ipsec_logsastr(sav)));
 505                                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 506                                 m_freem(m);
 507                                 return EINVAL;
 508                         }
 509                 }
 510                 lck_mtx_lock(sadb_mutex);
 511                 sav->replay->count++;
 512                 lck_mtx_unlock(sadb_mutex);
 513                 /*
 514                  * XXX sequence number must not be cycled, if the SA is
 515                  * installed by IKE daemon.
 516                  */
 517                 ahdr->ah_seq = htonl(sav->replay->count);
 518                 bzero(ahdr + 1, plen);
 519         }
 520
 521         /*
 522          * calcurate the checksum, based on security association
 523          * and the algorithm specified.
 524          */
 525         error = ah6_calccksum(m, (caddr_t)ahsumpos, plen, algo, sav);
 526         if (error) {
 527                 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
 528                 m_freem(m);
 529         } else {
 530                 IPSEC_STAT_INCREMENT(ipsec6stat.out_success);
 531                 key_sa_recordxfer(sav, m);
 532         }
 533         IPSEC_STAT_INCREMENT(ipsec6stat.out_ahhist[sav->alg_auth]);
 534
 535         return(error);
 536 }
 537 #endif
 538
 539 #if INET
 540 /*
 541  * Find the final destination if there is loose/strict source routing option.
 542  * Returns NULL if there's no source routing options.
 543  * Returns NULL on errors too.
 544  * Note that this function will return a pointer INTO the given parameter,
 545  * struct mbuf *m.
 546  * The mbuf must be pulled up toward, at least, ip option part.
 547  */
 548 static struct in_addr *
 549 ah4_finaldst(struct mbuf *m)
 550 {
 551         struct ip *ip;
 552         int optlen;
 553         u_char *q;
 554         int i;
 555         int hlen;
 556
 557         if (!m)
 558                 panic("ah4_finaldst: m == NULL");
 559         ip = mtod(m, struct ip *);
 560 #ifdef _IP_VHL
 561         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 562 #else
 563         hlen = ip->ip_hl << 2;
 564 #endif
 565
 566         if (m->m_len < hlen) {
 567                 ipseclog((LOG_DEBUG,
 568                     "ah4_finaldst: parameter mbuf wrong (not pulled up)\n"));
 569                 return NULL;
 570         }
 571
 572         if (hlen == sizeof(struct ip))
 573                 return NULL;
 574
 575         optlen = hlen - sizeof(struct ip);
 576         if (optlen < 0) {
 577                 ipseclog((LOG_DEBUG, "ah4_finaldst: wrong optlen %d\n",
 578                     optlen));
 579                 return NULL;
 580         }
 581
 582         q = (u_char *)(ip + 1);
 583         i = 0;
 584         while (i < optlen) {
 585                 if (i + IPOPT_OPTVAL >= optlen)
 586                         return NULL;
 587                 if (q[i + IPOPT_OPTVAL] == IPOPT_EOL ||
 588                     q[i + IPOPT_OPTVAL] == IPOPT_NOP ||
 589                     i + IPOPT_OLEN < optlen)
 590                         ;
 591                 else
 592                         return NULL;
 593
 594                 switch (q[i + IPOPT_OPTVAL]) {
 595                 case IPOPT_EOL:
 596                         i = optlen;     /* bye */
 597                         break;
 598                 case IPOPT_NOP:
 599                         i++;
 600                         break;
 601                 case IPOPT_LSRR:
 602                 case IPOPT_SSRR:
 603                         if (q[i + IPOPT_OLEN] < 2 + sizeof(struct in_addr) ||
 604                             optlen - i < q[i + IPOPT_OLEN]) {
 605                                 ipseclog((LOG_ERR,
 606                                     "ip_finaldst: invalid IP option "
 607                                     "(code=%02x len=%02x)\n",
 608                                     q[i + IPOPT_OPTVAL], q[i + IPOPT_OLEN]));
 609                                 return NULL;
 610                         }
 611                         i += q[i + IPOPT_OLEN] - sizeof(struct in_addr);
 612                         return (struct in_addr *)(void *)(q + i);
 613                 default:
 614                         if (q[i + IPOPT_OLEN] < 2 ||
 615                             optlen - i < q[i + IPOPT_OLEN]) {
 616                                 ipseclog((LOG_ERR,
 617                                     "ip_finaldst: invalid IP option "
 618                                     "(code=%02x len=%02x)\n",
 619                                     q[i + IPOPT_OPTVAL], q[i + IPOPT_OLEN]));
 620                                 return NULL;
 621                         }
 622                         i += q[i + IPOPT_OLEN];
 623                         break;
 624                 }
 625         }
 626         return NULL;
 627 }
 628 #endif