sys/netinet/ip_options.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2005
   5  *      Andre Oppermann, Internet Business Solutions AG.  All right reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 4. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  * $FreeBSD$
  32  */
  33
  34 #include "opt_ipstealth.h"
  35 #include "opt_mac.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/mac.h>
  40 #include <sys/mbuf.h>
  41 /* #include <sys/malloc.h> */
  42 #include <sys/domain.h>
  43 #include <sys/protosw.h>
  44 #include <sys/socket.h>
  45 #include <sys/time.h>
  46 #include <sys/kernel.h>
  47 #include <sys/syslog.h>
  48 #include <sys/sysctl.h>
  49
  50 #include <net/if.h>
  51 #include <net/if_types.h>
  52 #include <net/if_var.h>
  53 #include <net/if_dl.h>
  54 #include <net/route.h>
  55 #include <net/netisr.h>
  56
  57 #include <netinet/in.h>
  58 #include <netinet/in_systm.h>
  59 #include <netinet/in_var.h>
  60 #include <netinet/ip.h>
  61 #include <netinet/in_pcb.h>
  62 #include <netinet/ip_var.h>
  63 #include <netinet/ip_options.h>
  64 #include <netinet/ip_icmp.h>
  65 #include <machine/in_cksum.h>
  66
  67 #include <sys/socketvar.h>
  68
  69 static int      ip_dosourceroute = 0;
  70 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
  71     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
  72
  73 static int      ip_acceptsourceroute = 0;
  74 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
  75     CTLFLAG_RW, &ip_acceptsourceroute, 0,
  76     "Enable accepting source routed IP packets");
  77
  78 int             ip_doopts = 1;  /* 0 = ignore, 1 = process, 2 = reject */
  79 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
  80     &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
  81
  82 static void     save_rte(struct mbuf *m, u_char *, struct in_addr);
  83
  84 /*
  85  * Do option processing on a datagram,
  86  * possibly discarding it if bad options are encountered,
  87  * or forwarding it if source-routed.
  88  * The pass argument is used when operating in the IPSTEALTH
  89  * mode to tell what options to process:
  90  * [LS]SRR (pass 0) or the others (pass 1).
  91  * The reason for as many as two passes is that when doing IPSTEALTH,
  92  * non-routing options should be processed only if the packet is for us.
  93  * Returns 1 if packet has been forwarded/freed,
  94  * 0 if the packet should be processed further.
  95  */
  96 int
  97 ip_dooptions(struct mbuf *m, int pass)
  98 {
  99         struct ip *ip = mtod(m, struct ip *);
 100         u_char *cp;
 101         struct in_ifaddr *ia;
 102         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
 103         struct in_addr *sin, dst;
 104         n_time ntime;
 105         struct  sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
 106
 107         /* ignore or reject packets with IP options */
 108         if (ip_doopts == 0)
 109                 return 0;
 110         else if (ip_doopts == 2) {
 111                 type = ICMP_UNREACH;
 112                 code = ICMP_UNREACH_FILTER_PROHIB;
 113                 goto bad;
 114         }
 115
 116         dst = ip->ip_dst;
 117         cp = (u_char *)(ip + 1);
 118         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 119         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 120                 opt = cp[IPOPT_OPTVAL];
 121                 if (opt == IPOPT_EOL)
 122                         break;
 123                 if (opt == IPOPT_NOP)
 124                         optlen = 1;
 125                 else {
 126                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
 127                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 128                                 goto bad;
 129                         }
 130                         optlen = cp[IPOPT_OLEN];
 131                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
 132                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 133                                 goto bad;
 134                         }
 135                 }
 136                 switch (opt) {
 137
 138                 default:
 139                         break;
 140
 141                 /*
 142                  * Source routing with record.
 143                  * Find interface with current destination address.
 144                  * If none on this machine then drop if strictly routed,
 145                  * or do nothing if loosely routed.
 146                  * Record interface address and bring up next address
 147                  * component.  If strictly routed make sure next
 148                  * address is on directly accessible net.
 149                  */
 150                 case IPOPT_LSRR:
 151                 case IPOPT_SSRR:
 152 #ifdef IPSTEALTH
 153                         if (ipstealth && pass > 0)
 154                                 break;
 155 #endif
 156                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
 157                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 158                                 goto bad;
 159                         }
 160                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 161                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 162                                 goto bad;
 163                         }
 164                         ipaddr.sin_addr = ip->ip_dst;
 165                         ia = (struct in_ifaddr *)
 166                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
 167                         if (ia == NULL) {
 168                                 if (opt == IPOPT_SSRR) {
 169                                         type = ICMP_UNREACH;
 170                                         code = ICMP_UNREACH_SRCFAIL;
 171                                         goto bad;
 172                                 }
 173                                 if (!ip_dosourceroute)
 174                                         goto nosourcerouting;
 175                                 /*
 176                                  * Loose routing, and not at next destination
 177                                  * yet; nothing to do except forward.
 178                                  */
 179                                 break;
 180                         }
 181                         off--;                  /* 0 origin */
 182                         if (off > optlen - (int)sizeof(struct in_addr)) {
 183                                 /*
 184                                  * End of source route.  Should be for us.
 185                                  */
 186                                 if (!ip_acceptsourceroute)
 187                                         goto nosourcerouting;
 188                                 save_rte(m, cp, ip->ip_src);
 189                                 break;
 190                         }
 191 #ifdef IPSTEALTH
 192                         if (ipstealth)
 193                                 goto dropit;
 194 #endif
 195                         if (!ip_dosourceroute) {
 196                                 if (ipforwarding) {
 197                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
 198                                         /*
 199                                          * Acting as a router, so generate ICMP
 200                                          */
 201 nosourcerouting:
 202                                         strcpy(buf, inet_ntoa(ip->ip_dst));
 203                                         log(LOG_WARNING,
 204                                             "attempted source route from %s to %s\n",
 205                                             inet_ntoa(ip->ip_src), buf);
 206                                         type = ICMP_UNREACH;
 207                                         code = ICMP_UNREACH_SRCFAIL;
 208                                         goto bad;
 209                                 } else {
 210                                         /*
 211                                          * Not acting as a router, so silently drop.
 212                                          */
 213 #ifdef IPSTEALTH
 214 dropit:
 215 #endif
 216                                         ipstat.ips_cantforward++;
 217                                         m_freem(m);
 218                                         return (1);
 219                                 }
 220                         }
 221
 222                         /*
 223                          * locate outgoing interface
 224                          */
 225                         (void)memcpy(&ipaddr.sin_addr, cp + off,
 226                             sizeof(ipaddr.sin_addr));
 227
 228                         if (opt == IPOPT_SSRR) {
 229 #define INA     struct in_ifaddr *
 230 #define SA      struct sockaddr *
 231                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
 232                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 233                         } else
 234                                 ia = ip_rtaddr(ipaddr.sin_addr);
 235                         if (ia == NULL) {
 236                                 type = ICMP_UNREACH;
 237                                 code = ICMP_UNREACH_SRCFAIL;
 238                                 goto bad;
 239                         }
 240                         ip->ip_dst = ipaddr.sin_addr;
 241                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
 242                             sizeof(struct in_addr));
 243                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 244                         /*
 245                          * Let ip_intr's mcast routing check handle mcast pkts
 246                          */
 247                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 248                         break;
 249
 250                 case IPOPT_RR:
 251 #ifdef IPSTEALTH
 252                         if (ipstealth && pass == 0)
 253                                 break;
 254 #endif
 255                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
 256                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 257                                 goto bad;
 258                         }
 259                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 260                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 261                                 goto bad;
 262                         }
 263                         /*
 264                          * If no space remains, ignore.
 265                          */
 266                         off--;                  /* 0 origin */
 267                         if (off > optlen - (int)sizeof(struct in_addr))
 268                                 break;
 269                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
 270                             sizeof(ipaddr.sin_addr));
 271                         /*
 272                          * locate outgoing interface; if we're the destination,
 273                          * use the incoming interface (should be same).
 274                          */
 275                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
 276                             (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
 277                                 type = ICMP_UNREACH;
 278                                 code = ICMP_UNREACH_HOST;
 279                                 goto bad;
 280                         }
 281                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
 282                             sizeof(struct in_addr));
 283                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 284                         break;
 285
 286                 case IPOPT_TS:
 287 #ifdef IPSTEALTH
 288                         if (ipstealth && pass == 0)
 289                                 break;
 290 #endif
 291                         code = cp - (u_char *)ip;
 292                         if (optlen < 4 || optlen > 40) {
 293                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 294                                 goto bad;
 295                         }
 296                         if ((off = cp[IPOPT_OFFSET]) < 5) {
 297                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 298                                 goto bad;
 299                         }
 300                         if (off > optlen - (int)sizeof(int32_t)) {
 301                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
 302                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
 303                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 304                                         goto bad;
 305                                 }
 306                                 break;
 307                         }
 308                         off--;                          /* 0 origin */
 309                         sin = (struct in_addr *)(cp + off);
 310                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
 311
 312                         case IPOPT_TS_TSONLY:
 313                                 break;
 314
 315                         case IPOPT_TS_TSANDADDR:
 316                                 if (off + sizeof(n_time) +
 317                                     sizeof(struct in_addr) > optlen) {
 318                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 319                                         goto bad;
 320                                 }
 321                                 ipaddr.sin_addr = dst;
 322                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
 323                                                             m->m_pkthdr.rcvif);
 324                                 if (ia == NULL)
 325                                         continue;
 326                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
 327                                     sizeof(struct in_addr));
 328                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 329                                 off += sizeof(struct in_addr);
 330                                 break;
 331
 332                         case IPOPT_TS_PRESPEC:
 333                                 if (off + sizeof(n_time) +
 334                                     sizeof(struct in_addr) > optlen) {
 335                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 336                                         goto bad;
 337                                 }
 338                                 (void)memcpy(&ipaddr.sin_addr, sin,
 339                                     sizeof(struct in_addr));
 340                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
 341                                         continue;
 342                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 343                                 off += sizeof(struct in_addr);
 344                                 break;
 345
 346                         default:
 347                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
 348                                 goto bad;
 349                         }
 350                         ntime = iptime();
 351                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
 352                         cp[IPOPT_OFFSET] += sizeof(n_time);
 353                 }
 354         }
 355         if (forward && ipforwarding) {
 356                 ip_forward(m, 1);
 357                 return (1);
 358         }
 359         return (0);
 360 bad:
 361         icmp_error(m, type, code, 0, 0);
 362         ipstat.ips_badoptions++;
 363         return (1);
 364 }
 365
 366 /*
 367  * Save incoming source route for use in replies,
 368  * to be picked up later by ip_srcroute if the receiver is interested.
 369  */
 370 static void
 371 save_rte(m, option, dst)
 372         struct mbuf *m;
 373         u_char *option;
 374         struct in_addr dst;
 375 {
 376         unsigned olen;
 377         struct ipopt_tag *opts;
 378
 379         opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
 380                                         sizeof(struct ipopt_tag), M_NOWAIT);
 381         if (opts == NULL)
 382                 return;
 383
 384         olen = option[IPOPT_OLEN];
 385         if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
 386                 m_tag_free((struct m_tag *)opts);
 387                 return;
 388         }
 389         bcopy(option, opts->ip_srcrt.srcopt, olen);
 390         opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
 391         opts->ip_srcrt.dst = dst;
 392         m_tag_prepend(m, (struct m_tag *)opts);
 393 }
 394
 395 /*
 396  * Retrieve incoming source route for use in replies,
 397  * in the same form used by setsockopt.
 398  * The first hop is placed before the options, will be removed later.
 399  */
 400 struct mbuf *
 401 ip_srcroute(m0)
 402         struct mbuf *m0;
 403 {
 404         register struct in_addr *p, *q;
 405         register struct mbuf *m;
 406         struct ipopt_tag *opts;
 407
 408         opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
 409         if (opts == NULL)
 410                 return (NULL);
 411
 412         if (opts->ip_nhops == 0)
 413                 return (NULL);
 414         m = m_get(M_DONTWAIT, MT_DATA);
 415         if (m == NULL)
 416                 return (NULL);
 417
 418 #define OPTSIZ  (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
 419
 420         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
 421         m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
 422             sizeof(struct in_addr) + OPTSIZ;
 423
 424         /*
 425          * First save first hop for return route
 426          */
 427         p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
 428         *(mtod(m, struct in_addr *)) = *p--;
 429
 430         /*
 431          * Copy option fields and padding (nop) to mbuf.
 432          */
 433         opts->ip_srcrt.nop = IPOPT_NOP;
 434         opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
 435         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
 436             &(opts->ip_srcrt.nop), OPTSIZ);
 437         q = (struct in_addr *)(mtod(m, caddr_t) +
 438             sizeof(struct in_addr) + OPTSIZ);
 439 #undef OPTSIZ
 440         /*
 441          * Record return path as an IP source route,
 442          * reversing the path (pointers are now aligned).
 443          */
 444         while (p >= opts->ip_srcrt.route) {
 445                 *q++ = *p--;
 446         }
 447         /*
 448          * Last hop goes to final destination.
 449          */
 450         *q = opts->ip_srcrt.dst;
 451         m_tag_delete(m0, (struct m_tag *)opts);
 452         return (m);
 453 }
 454
 455 /*
 456  * Strip out IP options, at higher
 457  * level protocol in the kernel.
 458  * Second argument is buffer to which options
 459  * will be moved, and return value is their length.
 460  * XXX should be deleted; last arg currently ignored.
 461  */
 462 void
 463 ip_stripoptions(m, mopt)
 464         register struct mbuf *m;
 465         struct mbuf *mopt;
 466 {
 467         register int i;
 468         struct ip *ip = mtod(m, struct ip *);
 469         register caddr_t opts;
 470         int olen;
 471
 472         olen = (ip->ip_hl << 2) - sizeof (struct ip);
 473         opts = (caddr_t)(ip + 1);
 474         i = m->m_len - (sizeof (struct ip) + olen);
 475         bcopy(opts + olen, opts, (unsigned)i);
 476         m->m_len -= olen;
 477         if (m->m_flags & M_PKTHDR)
 478                 m->m_pkthdr.len -= olen;
 479         ip->ip_v = IPVERSION;
 480         ip->ip_hl = sizeof(struct ip) >> 2;
 481 }
 482
 483 /*
 484  * Insert IP options into preformed packet.
 485  * Adjust IP destination as required for IP source routing,
 486  * as indicated by a non-zero in_addr at the start of the options.
 487  *
 488  * XXX This routine assumes that the packet has no options in place.
 489  */
 490 struct mbuf *
 491 ip_insertoptions(m, opt, phlen)
 492         register struct mbuf *m;
 493         struct mbuf *opt;
 494         int *phlen;
 495 {
 496         register struct ipoption *p = mtod(opt, struct ipoption *);
 497         struct mbuf *n;
 498         register struct ip *ip = mtod(m, struct ip *);
 499         unsigned optlen;
 500
 501         optlen = opt->m_len - sizeof(p->ipopt_dst);
 502         if (optlen + ip->ip_len > IP_MAXPACKET) {
 503                 *phlen = 0;
 504                 return (m);             /* XXX should fail */
 505         }
 506         if (p->ipopt_dst.s_addr)
 507                 ip->ip_dst = p->ipopt_dst;
 508         if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
 509                 MGETHDR(n, M_DONTWAIT, MT_DATA);
 510                 if (n == NULL) {
 511                         *phlen = 0;
 512                         return (m);
 513                 }
 514                 M_MOVE_PKTHDR(n, m);
 515                 n->m_pkthdr.rcvif = NULL;
 516 #ifdef MAC
 517                 mac_copy_mbuf(m, n);
 518 #endif
 519                 n->m_pkthdr.len += optlen;
 520                 m->m_len -= sizeof(struct ip);
 521                 m->m_data += sizeof(struct ip);
 522                 n->m_next = m;
 523                 m = n;
 524                 m->m_len = optlen + sizeof(struct ip);
 525                 m->m_data += max_linkhdr;
 526                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 527         } else {
 528                 m->m_data -= optlen;
 529                 m->m_len += optlen;
 530                 m->m_pkthdr.len += optlen;
 531                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 532         }
 533         ip = mtod(m, struct ip *);
 534         bcopy(p->ipopt_list, ip + 1, optlen);
 535         *phlen = sizeof(struct ip) + optlen;
 536         ip->ip_v = IPVERSION;
 537         ip->ip_hl = *phlen >> 2;
 538         ip->ip_len += optlen;
 539         return (m);
 540 }
 541
 542 /*
 543  * Copy options from ip to jp,
 544  * omitting those not copied during fragmentation.
 545  */
 546 int
 547 ip_optcopy(ip, jp)
 548         struct ip *ip, *jp;
 549 {
 550         register u_char *cp, *dp;
 551         int opt, optlen, cnt;
 552
 553         cp = (u_char *)(ip + 1);
 554         dp = (u_char *)(jp + 1);
 555         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 556         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 557                 opt = cp[0];
 558                 if (opt == IPOPT_EOL)
 559                         break;
 560                 if (opt == IPOPT_NOP) {
 561                         /* Preserve for IP mcast tunnel's LSRR alignment. */
 562                         *dp++ = IPOPT_NOP;
 563                         optlen = 1;
 564                         continue;
 565                 }
 566
 567                 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
 568                     ("ip_optcopy: malformed ipv4 option"));
 569                 optlen = cp[IPOPT_OLEN];
 570                 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
 571                     ("ip_optcopy: malformed ipv4 option"));
 572
 573                 /* bogus lengths should have been caught by ip_dooptions */
 574                 if (optlen > cnt)
 575                         optlen = cnt;
 576                 if (IPOPT_COPIED(opt)) {
 577                         bcopy(cp, dp, optlen);
 578                         dp += optlen;
 579                 }
 580         }
 581         for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
 582                 *dp++ = IPOPT_EOL;
 583         return (optlen);
 584 }
 585
 586 /*
 587  * Set up IP options in pcb for insertion in output packets.
 588  * Store in mbuf with pointer in pcbopt, adding pseudo-option
 589  * with destination address if source routed.
 590  */
 591 int
 592 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
 593 {
 594         register int cnt, optlen;
 595         register u_char *cp;
 596         struct mbuf **pcbopt;
 597         u_char opt;
 598
 599         INP_LOCK_ASSERT(inp);
 600
 601         pcbopt = &inp->inp_options;
 602
 603         /* turn off any old options */
 604         if (*pcbopt)
 605                 (void)m_free(*pcbopt);
 606         *pcbopt = 0;
 607         if (m == NULL || m->m_len == 0) {
 608                 /*
 609                  * Only turning off any previous options.
 610                  */
 611                 if (m != NULL)
 612                         (void)m_free(m);
 613                 return (0);
 614         }
 615
 616         if (m->m_len % sizeof(int32_t))
 617                 goto bad;
 618         /*
 619          * IP first-hop destination address will be stored before
 620          * actual options; move other options back
 621          * and clear it when none present.
 622          */
 623         if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
 624                 goto bad;
 625         cnt = m->m_len;
 626         m->m_len += sizeof(struct in_addr);
 627         cp = mtod(m, u_char *) + sizeof(struct in_addr);
 628         bcopy(mtod(m, void *), cp, (unsigned)cnt);
 629         bzero(mtod(m, void *), sizeof(struct in_addr));
 630
 631         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 632                 opt = cp[IPOPT_OPTVAL];
 633                 if (opt == IPOPT_EOL)
 634                         break;
 635                 if (opt == IPOPT_NOP)
 636                         optlen = 1;
 637                 else {
 638                         if (cnt < IPOPT_OLEN + sizeof(*cp))
 639                                 goto bad;
 640                         optlen = cp[IPOPT_OLEN];
 641                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
 642                                 goto bad;
 643                 }
 644                 switch (opt) {
 645
 646                 default:
 647                         break;
 648
 649                 case IPOPT_LSRR:
 650                 case IPOPT_SSRR:
 651                         /*
 652                          * user process specifies route as:
 653                          *      ->A->B->C->D
 654                          * D must be our final destination (but we can't
 655                          * check that since we may not have connected yet).
 656                          * A is first hop destination, which doesn't appear in
 657                          * actual IP option, but is stored before the options.
 658                          */
 659                         if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
 660                                 goto bad;
 661                         m->m_len -= sizeof(struct in_addr);
 662                         cnt -= sizeof(struct in_addr);
 663                         optlen -= sizeof(struct in_addr);
 664                         cp[IPOPT_OLEN] = optlen;
 665                         /*
 666                          * Move first hop before start of options.
 667                          */
 668                         bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
 669                             sizeof(struct in_addr));
 670                         /*
 671                          * Then copy rest of options back
 672                          * to close up the deleted entry.
 673                          */
 674                         bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
 675                             &cp[IPOPT_OFFSET+1],
 676                             (unsigned)cnt - (IPOPT_MINOFF - 1));
 677                         break;
 678                 }
 679         }
 680         if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
 681                 goto bad;
 682         *pcbopt = m;
 683         return (0);
 684
 685 bad:
 686         (void)m_free(m);
 687         return (EINVAL);
 688 }