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/mbuf.h>
  40 /* #include <sys/malloc.h> */
  41 #include <sys/domain.h>
  42 #include <sys/protosw.h>
  43 #include <sys/socket.h>
  44 #include <sys/time.h>
  45 #include <sys/kernel.h>
  46 #include <sys/syslog.h>
  47 #include <sys/sysctl.h>
  48
  49 #include <net/if.h>
  50 #include <net/if_types.h>
  51 #include <net/if_var.h>
  52 #include <net/if_dl.h>
  53 #include <net/route.h>
  54 #include <net/netisr.h>
  55
  56 #include <netinet/in.h>
  57 #include <netinet/in_systm.h>
  58 #include <netinet/in_var.h>
  59 #include <netinet/ip.h>
  60 #include <netinet/in_pcb.h>
  61 #include <netinet/ip_var.h>
  62 #include <netinet/ip_options.h>
  63 #include <netinet/ip_icmp.h>
  64 #include <machine/in_cksum.h>
  65
  66 #include <sys/socketvar.h>
  67
  68 #include <security/mac/mac_framework.h>
  69
  70 static int      ip_dosourceroute = 0;
  71 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
  72     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
  73
  74 static int      ip_acceptsourceroute = 0;
  75 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
  76     CTLFLAG_RW, &ip_acceptsourceroute, 0,
  77     "Enable accepting source routed IP packets");
  78
  79 int             ip_doopts = 1;  /* 0 = ignore, 1 = process, 2 = reject */
  80 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
  81     &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
  82
  83 static void     save_rte(struct mbuf *m, u_char *, struct in_addr);
  84
  85 /*
  86  * Do option processing on a datagram,
  87  * possibly discarding it if bad options are encountered,
  88  * or forwarding it if source-routed.
  89  * The pass argument is used when operating in the IPSTEALTH
  90  * mode to tell what options to process:
  91  * [LS]SRR (pass 0) or the others (pass 1).
  92  * The reason for as many as two passes is that when doing IPSTEALTH,
  93  * non-routing options should be processed only if the packet is for us.
  94  * Returns 1 if packet has been forwarded/freed,
  95  * 0 if the packet should be processed further.
  96  */
  97 int
  98 ip_dooptions(struct mbuf *m, int pass)
  99 {
 100         struct ip *ip = mtod(m, struct ip *);
 101         u_char *cp;
 102         struct in_ifaddr *ia;
 103         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
 104         struct in_addr *sin, dst;
 105         n_time ntime;
 106         struct  sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
 107
 108         /* ignore or reject packets with IP options */
 109         if (ip_doopts == 0)
 110                 return 0;
 111         else if (ip_doopts == 2) {
 112                 type = ICMP_UNREACH;
 113                 code = ICMP_UNREACH_FILTER_PROHIB;
 114                 goto bad;
 115         }
 116
 117         dst = ip->ip_dst;
 118         cp = (u_char *)(ip + 1);
 119         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 120         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 121                 opt = cp[IPOPT_OPTVAL];
 122                 if (opt == IPOPT_EOL)
 123                         break;
 124                 if (opt == IPOPT_NOP)
 125                         optlen = 1;
 126                 else {
 127                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
 128                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 129                                 goto bad;
 130                         }
 131                         optlen = cp[IPOPT_OLEN];
 132                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
 133                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 134                                 goto bad;
 135                         }
 136                 }
 137                 switch (opt) {
 138
 139                 default:
 140                         break;
 141
 142                 /*
 143                  * Source routing with record.
 144                  * Find interface with current destination address.
 145                  * If none on this machine then drop if strictly routed,
 146                  * or do nothing if loosely routed.
 147                  * Record interface address and bring up next address
 148                  * component.  If strictly routed make sure next
 149                  * address is on directly accessible net.
 150                  */
 151                 case IPOPT_LSRR:
 152                 case IPOPT_SSRR:
 153 #ifdef IPSTEALTH
 154                         if (ipstealth && pass > 0)
 155                                 break;
 156 #endif
 157                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
 158                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 159                                 goto bad;
 160                         }
 161                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 162                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 163                                 goto bad;
 164                         }
 165                         ipaddr.sin_addr = ip->ip_dst;
 166                         ia = (struct in_ifaddr *)
 167                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
 168                         if (ia == NULL) {
 169                                 if (opt == IPOPT_SSRR) {
 170                                         type = ICMP_UNREACH;
 171                                         code = ICMP_UNREACH_SRCFAIL;
 172                                         goto bad;
 173                                 }
 174                                 if (!ip_dosourceroute)
 175                                         goto nosourcerouting;
 176                                 /*
 177                                  * Loose routing, and not at next destination
 178                                  * yet; nothing to do except forward.
 179                                  */
 180                                 break;
 181                         }
 182                         off--;                  /* 0 origin */
 183                         if (off > optlen - (int)sizeof(struct in_addr)) {
 184                                 /*
 185                                  * End of source route.  Should be for us.
 186                                  */
 187                                 if (!ip_acceptsourceroute)
 188                                         goto nosourcerouting;
 189                                 save_rte(m, cp, ip->ip_src);
 190                                 break;
 191                         }
 192 #ifdef IPSTEALTH
 193                         if (ipstealth)
 194                                 goto dropit;
 195 #endif
 196                         if (!ip_dosourceroute) {
 197                                 if (ipforwarding) {
 198                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
 199                                         /*
 200                                          * Acting as a router, so generate ICMP
 201                                          */
 202 nosourcerouting:
 203                                         strcpy(buf, inet_ntoa(ip->ip_dst));
 204                                         log(LOG_WARNING,
 205                                             "attempted source route from %s to %s\n",
 206                                             inet_ntoa(ip->ip_src), buf);
 207                                         type = ICMP_UNREACH;
 208                                         code = ICMP_UNREACH_SRCFAIL;
 209                                         goto bad;
 210                                 } else {
 211                                         /*
 212                                          * Not acting as a router, so silently drop.
 213                                          */
 214 #ifdef IPSTEALTH
 215 dropit:
 216 #endif
 217                                         ipstat.ips_cantforward++;
 218                                         m_freem(m);
 219                                         return (1);
 220                                 }
 221                         }
 222
 223                         /*
 224                          * locate outgoing interface
 225                          */
 226                         (void)memcpy(&ipaddr.sin_addr, cp + off,
 227                             sizeof(ipaddr.sin_addr));
 228
 229                         if (opt == IPOPT_SSRR) {
 230 #define INA     struct in_ifaddr *
 231 #define SA      struct sockaddr *
 232                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
 233                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 234                         } else
 235                                 ia = ip_rtaddr(ipaddr.sin_addr);
 236                         if (ia == NULL) {
 237                                 type = ICMP_UNREACH;
 238                                 code = ICMP_UNREACH_SRCFAIL;
 239                                 goto bad;
 240                         }
 241                         ip->ip_dst = ipaddr.sin_addr;
 242                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
 243                             sizeof(struct in_addr));
 244                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 245                         /*
 246                          * Let ip_intr's mcast routing check handle mcast pkts
 247                          */
 248                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 249                         break;
 250
 251                 case IPOPT_RR:
 252 #ifdef IPSTEALTH
 253                         if (ipstealth && pass == 0)
 254                                 break;
 255 #endif
 256                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
 257                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 258                                 goto bad;
 259                         }
 260                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 261                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 262                                 goto bad;
 263                         }
 264                         /*
 265                          * If no space remains, ignore.
 266                          */
 267                         off--;                  /* 0 origin */
 268                         if (off > optlen - (int)sizeof(struct in_addr))
 269                                 break;
 270                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
 271                             sizeof(ipaddr.sin_addr));
 272                         /*
 273                          * locate outgoing interface; if we're the destination,
 274                          * use the incoming interface (should be same).
 275                          */
 276                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
 277                             (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
 278                                 type = ICMP_UNREACH;
 279                                 code = ICMP_UNREACH_HOST;
 280                                 goto bad;
 281                         }
 282                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
 283                             sizeof(struct in_addr));
 284                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 285                         break;
 286
 287                 case IPOPT_TS:
 288 #ifdef IPSTEALTH
 289                         if (ipstealth && pass == 0)
 290                                 break;
 291 #endif
 292                         code = cp - (u_char *)ip;
 293                         if (optlen < 4 || optlen > 40) {
 294                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 295                                 goto bad;
 296                         }
 297                         if ((off = cp[IPOPT_OFFSET]) < 5) {
 298                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 299                                 goto bad;
 300                         }
 301                         if (off > optlen - (int)sizeof(int32_t)) {
 302                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
 303                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
 304                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 305                                         goto bad;
 306                                 }
 307                                 break;
 308                         }
 309                         off--;                          /* 0 origin */
 310                         sin = (struct in_addr *)(cp + off);
 311                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
 312
 313                         case IPOPT_TS_TSONLY:
 314                                 break;
 315
 316                         case IPOPT_TS_TSANDADDR:
 317                                 if (off + sizeof(n_time) +
 318                                     sizeof(struct in_addr) > optlen) {
 319                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 320                                         goto bad;
 321                                 }
 322                                 ipaddr.sin_addr = dst;
 323                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
 324                                                             m->m_pkthdr.rcvif);
 325                                 if (ia == NULL)
 326                                         continue;
 327                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
 328                                     sizeof(struct in_addr));
 329                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 330                                 off += sizeof(struct in_addr);
 331                                 break;
 332
 333                         case IPOPT_TS_PRESPEC:
 334                                 if (off + sizeof(n_time) +
 335                                     sizeof(struct in_addr) > optlen) {
 336                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 337                                         goto bad;
 338                                 }
 339                                 (void)memcpy(&ipaddr.sin_addr, sin,
 340                                     sizeof(struct in_addr));
 341                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
 342                                         continue;
 343                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 344                                 off += sizeof(struct in_addr);
 345                                 break;
 346
 347                         default:
 348                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
 349                                 goto bad;
 350                         }
 351                         ntime = iptime();
 352                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
 353                         cp[IPOPT_OFFSET] += sizeof(n_time);
 354                 }
 355         }
 356         if (forward && ipforwarding) {
 357                 ip_forward(m, 1);
 358                 return (1);
 359         }
 360         return (0);
 361 bad:
 362         icmp_error(m, type, code, 0, 0);
 363         ipstat.ips_badoptions++;
 364         return (1);
 365 }
 366
 367 /*
 368  * Save incoming source route for use in replies,
 369  * to be picked up later by ip_srcroute if the receiver is interested.
 370  */
 371 static void
 372 save_rte(m, option, dst)
 373         struct mbuf *m;
 374         u_char *option;
 375         struct in_addr dst;
 376 {
 377         unsigned olen;
 378         struct ipopt_tag *opts;
 379
 380         opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
 381                                         sizeof(struct ipopt_tag), M_NOWAIT);
 382         if (opts == NULL)
 383                 return;
 384
 385         olen = option[IPOPT_OLEN];
 386         if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
 387                 m_tag_free((struct m_tag *)opts);
 388                 return;
 389         }
 390         bcopy(option, opts->ip_srcrt.srcopt, olen);
 391         opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
 392         opts->ip_srcrt.dst = dst;
 393         m_tag_prepend(m, (struct m_tag *)opts);
 394 }
 395
 396 /*
 397  * Retrieve incoming source route for use in replies,
 398  * in the same form used by setsockopt.
 399  * The first hop is placed before the options, will be removed later.
 400  */
 401 struct mbuf *
 402 ip_srcroute(m0)
 403         struct mbuf *m0;
 404 {
 405         register struct in_addr *p, *q;
 406         register struct mbuf *m;
 407         struct ipopt_tag *opts;
 408
 409         opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
 410         if (opts == NULL)
 411                 return (NULL);
 412
 413         if (opts->ip_nhops == 0)
 414                 return (NULL);
 415         m = m_get(M_DONTWAIT, MT_DATA);
 416         if (m == NULL)
 417                 return (NULL);
 418
 419 #define OPTSIZ  (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
 420
 421         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
 422         m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
 423             sizeof(struct in_addr) + OPTSIZ;
 424
 425         /*
 426          * First save first hop for return route
 427          */
 428         p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
 429         *(mtod(m, struct in_addr *)) = *p--;
 430
 431         /*
 432          * Copy option fields and padding (nop) to mbuf.
 433          */
 434         opts->ip_srcrt.nop = IPOPT_NOP;
 435         opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
 436         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
 437             &(opts->ip_srcrt.nop), OPTSIZ);
 438         q = (struct in_addr *)(mtod(m, caddr_t) +
 439             sizeof(struct in_addr) + OPTSIZ);
 440 #undef OPTSIZ
 441         /*
 442          * Record return path as an IP source route,
 443          * reversing the path (pointers are now aligned).
 444          */
 445         while (p >= opts->ip_srcrt.route) {
 446                 *q++ = *p--;
 447         }
 448         /*
 449          * Last hop goes to final destination.
 450          */
 451         *q = opts->ip_srcrt.dst;
 452         m_tag_delete(m0, (struct m_tag *)opts);
 453         return (m);
 454 }
 455
 456 /*
 457  * Strip out IP options, at higher
 458  * level protocol in the kernel.
 459  * Second argument is buffer to which options
 460  * will be moved, and return value is their length.
 461  * XXX should be deleted; last arg currently ignored.
 462  */
 463 void
 464 ip_stripoptions(m, mopt)
 465         register struct mbuf *m;
 466         struct mbuf *mopt;
 467 {
 468         register int i;
 469         struct ip *ip = mtod(m, struct ip *);
 470         register caddr_t opts;
 471         int olen;
 472
 473         olen = (ip->ip_hl << 2) - sizeof (struct ip);
 474         opts = (caddr_t)(ip + 1);
 475         i = m->m_len - (sizeof (struct ip) + olen);
 476         bcopy(opts + olen, opts, (unsigned)i);
 477         m->m_len -= olen;
 478         if (m->m_flags & M_PKTHDR)
 479                 m->m_pkthdr.len -= olen;
 480         ip->ip_v = IPVERSION;
 481         ip->ip_hl = sizeof(struct ip) >> 2;
 482 }
 483
 484 /*
 485  * Insert IP options into preformed packet.
 486  * Adjust IP destination as required for IP source routing,
 487  * as indicated by a non-zero in_addr at the start of the options.
 488  *
 489  * XXX This routine assumes that the packet has no options in place.
 490  */
 491 struct mbuf *
 492 ip_insertoptions(m, opt, phlen)
 493         register struct mbuf *m;
 494         struct mbuf *opt;
 495         int *phlen;
 496 {
 497         register struct ipoption *p = mtod(opt, struct ipoption *);
 498         struct mbuf *n;
 499         register struct ip *ip = mtod(m, struct ip *);
 500         unsigned optlen;
 501
 502         optlen = opt->m_len - sizeof(p->ipopt_dst);
 503         if (optlen + ip->ip_len > IP_MAXPACKET) {
 504                 *phlen = 0;
 505                 return (m);             /* XXX should fail */
 506         }
 507         if (p->ipopt_dst.s_addr)
 508                 ip->ip_dst = p->ipopt_dst;
 509         if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
 510                 MGETHDR(n, M_DONTWAIT, MT_DATA);
 511                 if (n == NULL) {
 512                         *phlen = 0;
 513                         return (m);
 514                 }
 515                 M_MOVE_PKTHDR(n, m);
 516                 n->m_pkthdr.rcvif = NULL;
 517 #ifdef MAC
 518                 mac_copy_mbuf(m, n);
 519 #endif
 520                 n->m_pkthdr.len += optlen;
 521                 m->m_len -= sizeof(struct ip);
 522                 m->m_data += sizeof(struct ip);
 523                 n->m_next = m;
 524                 m = n;
 525                 m->m_len = optlen + sizeof(struct ip);
 526                 m->m_data += max_linkhdr;
 527                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 528         } else {
 529                 m->m_data -= optlen;
 530                 m->m_len += optlen;
 531                 m->m_pkthdr.len += optlen;
 532                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 533         }
 534         ip = mtod(m, struct ip *);
 535         bcopy(p->ipopt_list, ip + 1, optlen);
 536         *phlen = sizeof(struct ip) + optlen;
 537         ip->ip_v = IPVERSION;
 538         ip->ip_hl = *phlen >> 2;
 539         ip->ip_len += optlen;
 540         return (m);
 541 }
 542
 543 /*
 544  * Copy options from ip to jp,
 545  * omitting those not copied during fragmentation.
 546  */
 547 int
 548 ip_optcopy(ip, jp)
 549         struct ip *ip, *jp;
 550 {
 551         register u_char *cp, *dp;
 552         int opt, optlen, cnt;
 553
 554         cp = (u_char *)(ip + 1);
 555         dp = (u_char *)(jp + 1);
 556         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 557         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 558                 opt = cp[0];
 559                 if (opt == IPOPT_EOL)
 560                         break;
 561                 if (opt == IPOPT_NOP) {
 562                         /* Preserve for IP mcast tunnel's LSRR alignment. */
 563                         *dp++ = IPOPT_NOP;
 564                         optlen = 1;
 565                         continue;
 566                 }
 567
 568                 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
 569                     ("ip_optcopy: malformed ipv4 option"));
 570                 optlen = cp[IPOPT_OLEN];
 571                 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
 572                     ("ip_optcopy: malformed ipv4 option"));
 573
 574                 /* bogus lengths should have been caught by ip_dooptions */
 575                 if (optlen > cnt)
 576                         optlen = cnt;
 577                 if (IPOPT_COPIED(opt)) {
 578                         bcopy(cp, dp, optlen);
 579                         dp += optlen;
 580                 }
 581         }
 582         for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
 583                 *dp++ = IPOPT_EOL;
 584         return (optlen);
 585 }
 586
 587 /*
 588  * Set up IP options in pcb for insertion in output packets.
 589  * Store in mbuf with pointer in pcbopt, adding pseudo-option
 590  * with destination address if source routed.
 591  */
 592 int
 593 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
 594 {
 595         register int cnt, optlen;
 596         register u_char *cp;
 597         struct mbuf **pcbopt;
 598         u_char opt;
 599
 600         INP_LOCK_ASSERT(inp);
 601
 602         pcbopt = &inp->inp_options;
 603
 604         /* turn off any old options */
 605         if (*pcbopt)
 606                 (void)m_free(*pcbopt);
 607         *pcbopt = 0;
 608         if (m == NULL || m->m_len == 0) {
 609                 /*
 610                  * Only turning off any previous options.
 611                  */
 612                 if (m != NULL)
 613                         (void)m_free(m);
 614                 return (0);
 615         }
 616
 617         if (m->m_len % sizeof(int32_t))
 618                 goto bad;
 619         /*
 620          * IP first-hop destination address will be stored before
 621          * actual options; move other options back
 622          * and clear it when none present.
 623          */
 624         if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
 625                 goto bad;
 626         cnt = m->m_len;
 627         m->m_len += sizeof(struct in_addr);
 628         cp = mtod(m, u_char *) + sizeof(struct in_addr);
 629         bcopy(mtod(m, void *), cp, (unsigned)cnt);
 630         bzero(mtod(m, void *), sizeof(struct in_addr));
 631
 632         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 633                 opt = cp[IPOPT_OPTVAL];
 634                 if (opt == IPOPT_EOL)
 635                         break;
 636                 if (opt == IPOPT_NOP)
 637                         optlen = 1;
 638                 else {
 639                         if (cnt < IPOPT_OLEN + sizeof(*cp))
 640                                 goto bad;
 641                         optlen = cp[IPOPT_OLEN];
 642                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
 643                                 goto bad;
 644                 }
 645                 switch (opt) {
 646
 647                 default:
 648                         break;
 649
 650                 case IPOPT_LSRR:
 651                 case IPOPT_SSRR:
 652                         /*
 653                          * user process specifies route as:
 654                          *      ->A->B->C->D
 655                          * D must be our final destination (but we can't
 656                          * check that since we may not have connected yet).
 657                          * A is first hop destination, which doesn't appear in
 658                          * actual IP option, but is stored before the options.
 659                          */
 660                         if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
 661                                 goto bad;
 662                         m->m_len -= sizeof(struct in_addr);
 663                         cnt -= sizeof(struct in_addr);
 664                         optlen -= sizeof(struct in_addr);
 665                         cp[IPOPT_OLEN] = optlen;
 666                         /*
 667                          * Move first hop before start of options.
 668                          */
 669                         bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
 670                             sizeof(struct in_addr));
 671                         /*
 672                          * Then copy rest of options back
 673                          * to close up the deleted entry.
 674                          */
 675                         bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
 676                             &cp[IPOPT_OFFSET+1],
 677                             (unsigned)cnt - (IPOPT_MINOFF - 1));
 678                         break;
 679                 }
 680         }
 681         if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
 682                 goto bad;
 683         *pcbopt = m;
 684         return (0);
 685
 686 bad:
 687         (void)m_free(m);
 688         return (EINVAL);
 689 }