sys/netinet/ip_options.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.
   4  * Copyright (c) 2005 Andre Oppermann, Internet Business Solutions AG.
   5  * All rights 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
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include "opt_ipstealth.h"
  36 #include "opt_mac.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/mbuf.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, possibly discarding it if bad options
  87  * are encountered, or forwarding it if source-routed.
  88  *
  89  * The pass argument is used when operating in the IPSTEALTH mode to tell
  90  * what options to process: [LS]SRR (pass 0) or the others (pass 1).  The
  91  * reason for as many as two passes is that when doing IPSTEALTH, non-routing
  92  * options should be processed only if the packet is for us.
  93  *
  94  * Returns 1 if packet has been forwarded/freed, 0 if the packet should be
  95  * 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         uint32_t 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.  Find interface with current
 144                  * destination address.  If none on this machine then drop if
 145                  * strictly routed, or do nothing if loosely routed.  Record
 146                  * interface address and bring up next address component.  If
 147                  * strictly routed make sure next address is on directly
 148                  * 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
 200                                          * 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
 213                                          * silently drop.
 214                                          */
 215 #ifdef IPSTEALTH
 216 dropit:
 217 #endif
 218                                         ipstat.ips_cantforward++;
 219                                         m_freem(m);
 220                                         return (1);
 221                                 }
 222                         }
 223
 224                         /*
 225                          * locate outgoing interface
 226                          */
 227                         (void)memcpy(&ipaddr.sin_addr, cp + off,
 228                             sizeof(ipaddr.sin_addr));
 229
 230                         if (opt == IPOPT_SSRR) {
 231 #define INA     struct in_ifaddr *
 232 #define SA      struct sockaddr *
 233                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
 234                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 235                         } else
 236 /* XXX MRT 0 for routing */
 237                                 ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m));
 238                         if (ia == NULL) {
 239                                 type = ICMP_UNREACH;
 240                                 code = ICMP_UNREACH_SRCFAIL;
 241                                 goto bad;
 242                         }
 243                         ip->ip_dst = ipaddr.sin_addr;
 244                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
 245                             sizeof(struct in_addr));
 246                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 247                         /*
 248                          * Let ip_intr's mcast routing check handle mcast pkts
 249                          */
 250                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 251                         break;
 252
 253                 case IPOPT_RR:
 254 #ifdef IPSTEALTH
 255                         if (ipstealth && pass == 0)
 256                                 break;
 257 #endif
 258                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
 259                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 260                                 goto bad;
 261                         }
 262                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 263                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 264                                 goto bad;
 265                         }
 266                         /*
 267                          * If no space remains, ignore.
 268                          */
 269                         off--;                  /* 0 origin */
 270                         if (off > optlen - (int)sizeof(struct in_addr))
 271                                 break;
 272                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
 273                             sizeof(ipaddr.sin_addr));
 274                         /*
 275                          * Locate outgoing interface; if we're the
 276                          * destination, use the incoming interface (should be
 277                          * same).
 278                          */
 279                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
 280                             (ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m))) == NULL) {
 281                                 type = ICMP_UNREACH;
 282                                 code = ICMP_UNREACH_HOST;
 283                                 goto bad;
 284                         }
 285                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
 286                             sizeof(struct in_addr));
 287                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 288                         break;
 289
 290                 case IPOPT_TS:
 291 #ifdef IPSTEALTH
 292                         if (ipstealth && pass == 0)
 293                                 break;
 294 #endif
 295                         code = cp - (u_char *)ip;
 296                         if (optlen < 4 || optlen > 40) {
 297                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 298                                 goto bad;
 299                         }
 300                         if ((off = cp[IPOPT_OFFSET]) < 5) {
 301                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 302                                 goto bad;
 303                         }
 304                         if (off > optlen - (int)sizeof(int32_t)) {
 305                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
 306                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
 307                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 308                                         goto bad;
 309                                 }
 310                                 break;
 311                         }
 312                         off--;                          /* 0 origin */
 313                         sin = (struct in_addr *)(cp + off);
 314                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
 315
 316                         case IPOPT_TS_TSONLY:
 317                                 break;
 318
 319                         case IPOPT_TS_TSANDADDR:
 320                                 if (off + sizeof(uint32_t) +
 321                                     sizeof(struct in_addr) > optlen) {
 322                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 323                                         goto bad;
 324                                 }
 325                                 ipaddr.sin_addr = dst;
 326                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
 327                                                             m->m_pkthdr.rcvif);
 328                                 if (ia == NULL)
 329                                         continue;
 330                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
 331                                     sizeof(struct in_addr));
 332                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 333                                 off += sizeof(struct in_addr);
 334                                 break;
 335
 336                         case IPOPT_TS_PRESPEC:
 337                                 if (off + sizeof(uint32_t) +
 338                                     sizeof(struct in_addr) > optlen) {
 339                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 340                                         goto bad;
 341                                 }
 342                                 (void)memcpy(&ipaddr.sin_addr, sin,
 343                                     sizeof(struct in_addr));
 344                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
 345                                         continue;
 346                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 347                                 off += sizeof(struct in_addr);
 348                                 break;
 349
 350                         default:
 351                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
 352                                 goto bad;
 353                         }
 354                         ntime = iptime();
 355                         (void)memcpy(cp + off, &ntime, sizeof(uint32_t));
 356                         cp[IPOPT_OFFSET] += sizeof(uint32_t);
 357                 }
 358         }
 359         if (forward && ipforwarding) {
 360                 ip_forward(m, 1);
 361                 return (1);
 362         }
 363         return (0);
 364 bad:
 365         icmp_error(m, type, code, 0, 0);
 366         ipstat.ips_badoptions++;
 367         return (1);
 368 }
 369
 370 /*
 371  * Save incoming source route for use in replies, to be picked up later by
 372  * ip_srcroute if the receiver is interested.
 373  */
 374 static void
 375 save_rte(struct mbuf *m, u_char *option, 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, in the same form used
 398  * by setsockopt.  The first hop is placed before the options, will be
 399  * removed later.
 400  */
 401 struct mbuf *
 402 ip_srcroute(struct mbuf *m0)
 403 {
 404         struct in_addr *p, *q;
 405         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, reversing the path
 442          * (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 level protocol in the kernel.  Second
 457  * argument is buffer to which options will be moved, and return value is
 458  * their length.
 459  *
 460  * XXX should be deleted; last arg currently ignored.
 461  */
 462 void
 463 ip_stripoptions(struct mbuf *m, struct mbuf *mopt)
 464 {
 465         int i;
 466         struct ip *ip = mtod(m, struct ip *);
 467         caddr_t opts;
 468         int olen;
 469
 470         olen = (ip->ip_hl << 2) - sizeof (struct ip);
 471         opts = (caddr_t)(ip + 1);
 472         i = m->m_len - (sizeof (struct ip) + olen);
 473         bcopy(opts + olen, opts, (unsigned)i);
 474         m->m_len -= olen;
 475         if (m->m_flags & M_PKTHDR)
 476                 m->m_pkthdr.len -= olen;
 477         ip->ip_v = IPVERSION;
 478         ip->ip_hl = sizeof(struct ip) >> 2;
 479 }
 480
 481 /*
 482  * Insert IP options into preformed packet.  Adjust IP destination as
 483  * required for IP source routing, as indicated by a non-zero in_addr at the
 484  * start of the options.
 485  *
 486  * XXX This routine assumes that the packet has no options in place.
 487  */
 488 struct mbuf *
 489 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
 490 {
 491         struct ipoption *p = mtod(opt, struct ipoption *);
 492         struct mbuf *n;
 493         struct ip *ip = mtod(m, struct ip *);
 494         unsigned optlen;
 495
 496         optlen = opt->m_len - sizeof(p->ipopt_dst);
 497         if (optlen + ip->ip_len > IP_MAXPACKET) {
 498                 *phlen = 0;
 499                 return (m);             /* XXX should fail */
 500         }
 501         if (p->ipopt_dst.s_addr)
 502                 ip->ip_dst = p->ipopt_dst;
 503         if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
 504                 MGETHDR(n, M_DONTWAIT, MT_DATA);
 505                 if (n == NULL) {
 506                         *phlen = 0;
 507                         return (m);
 508                 }
 509                 M_MOVE_PKTHDR(n, m);
 510                 n->m_pkthdr.rcvif = NULL;
 511                 n->m_pkthdr.len += optlen;
 512                 m->m_len -= sizeof(struct ip);
 513                 m->m_data += sizeof(struct ip);
 514                 n->m_next = m;
 515                 m = n;
 516                 m->m_len = optlen + sizeof(struct ip);
 517                 m->m_data += max_linkhdr;
 518                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 519         } else {
 520                 m->m_data -= optlen;
 521                 m->m_len += optlen;
 522                 m->m_pkthdr.len += optlen;
 523                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 524         }
 525         ip = mtod(m, struct ip *);
 526         bcopy(p->ipopt_list, ip + 1, optlen);
 527         *phlen = sizeof(struct ip) + optlen;
 528         ip->ip_v = IPVERSION;
 529         ip->ip_hl = *phlen >> 2;
 530         ip->ip_len += optlen;
 531         return (m);
 532 }
 533
 534 /*
 535  * Copy options from ip to jp, omitting those not copied during
 536  * fragmentation.
 537  */
 538 int
 539 ip_optcopy(struct ip *ip, struct ip *jp)
 540 {
 541         u_char *cp, *dp;
 542         int opt, optlen, cnt;
 543
 544         cp = (u_char *)(ip + 1);
 545         dp = (u_char *)(jp + 1);
 546         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 547         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 548                 opt = cp[0];
 549                 if (opt == IPOPT_EOL)
 550                         break;
 551                 if (opt == IPOPT_NOP) {
 552                         /* Preserve for IP mcast tunnel's LSRR alignment. */
 553                         *dp++ = IPOPT_NOP;
 554                         optlen = 1;
 555                         continue;
 556                 }
 557
 558                 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
 559                     ("ip_optcopy: malformed ipv4 option"));
 560                 optlen = cp[IPOPT_OLEN];
 561                 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
 562                     ("ip_optcopy: malformed ipv4 option"));
 563
 564                 /* Bogus lengths should have been caught by ip_dooptions. */
 565                 if (optlen > cnt)
 566                         optlen = cnt;
 567                 if (IPOPT_COPIED(opt)) {
 568                         bcopy(cp, dp, optlen);
 569                         dp += optlen;
 570                 }
 571         }
 572         for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
 573                 *dp++ = IPOPT_EOL;
 574         return (optlen);
 575 }
 576
 577 /*
 578  * Set up IP options in pcb for insertion in output packets.  Store in mbuf
 579  * with pointer in pcbopt, adding pseudo-option with destination address if
 580  * source routed.
 581  */
 582 int
 583 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
 584 {
 585         int cnt, optlen;
 586         u_char *cp;
 587         struct mbuf **pcbopt;
 588         u_char opt;
 589
 590         INP_WLOCK_ASSERT(inp);
 591
 592         pcbopt = &inp->inp_options;
 593
 594         /* turn off any old options */
 595         if (*pcbopt)
 596                 (void)m_free(*pcbopt);
 597         *pcbopt = 0;
 598         if (m == NULL || m->m_len == 0) {
 599                 /*
 600                  * Only turning off any previous options.
 601                  */
 602                 if (m != NULL)
 603                         (void)m_free(m);
 604                 return (0);
 605         }
 606
 607         if (m->m_len % sizeof(int32_t))
 608                 goto bad;
 609         /*
 610          * IP first-hop destination address will be stored before actual
 611          * options; move other options back and clear it when none present.
 612          */
 613         if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
 614                 goto bad;
 615         cnt = m->m_len;
 616         m->m_len += sizeof(struct in_addr);
 617         cp = mtod(m, u_char *) + sizeof(struct in_addr);
 618         bcopy(mtod(m, void *), cp, (unsigned)cnt);
 619         bzero(mtod(m, void *), sizeof(struct in_addr));
 620
 621         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 622                 opt = cp[IPOPT_OPTVAL];
 623                 if (opt == IPOPT_EOL)
 624                         break;
 625                 if (opt == IPOPT_NOP)
 626                         optlen = 1;
 627                 else {
 628                         if (cnt < IPOPT_OLEN + sizeof(*cp))
 629                                 goto bad;
 630                         optlen = cp[IPOPT_OLEN];
 631                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
 632                                 goto bad;
 633                 }
 634                 switch (opt) {
 635
 636                 default:
 637                         break;
 638
 639                 case IPOPT_LSRR:
 640                 case IPOPT_SSRR:
 641                         /*
 642                          * User process specifies route as:
 643                          *
 644                          *      ->A->B->C->D
 645                          *
 646                          * D must be our final destination (but we can't
 647                          * check that since we may not have connected yet).
 648                          * A is first hop destination, which doesn't appear
 649                          * in actual IP option, but is stored before the
 650                          * options.
 651                          */
 652                         /* XXX-BZ PRIV_NETINET_SETHDROPTS? */
 653                         if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
 654                                 goto bad;
 655                         m->m_len -= sizeof(struct in_addr);
 656                         cnt -= sizeof(struct in_addr);
 657                         optlen -= sizeof(struct in_addr);
 658                         cp[IPOPT_OLEN] = optlen;
 659                         /*
 660                          * Move first hop before start of options.
 661                          */
 662                         bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
 663                             sizeof(struct in_addr));
 664                         /*
 665                          * Then copy rest of options back
 666                          * to close up the deleted entry.
 667                          */
 668                         bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
 669                             &cp[IPOPT_OFFSET+1],
 670                             (unsigned)cnt - (IPOPT_MINOFF - 1));
 671                         break;
 672                 }
 673         }
 674         if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
 675                 goto bad;
 676         *pcbopt = m;
 677         return (0);
 678
 679 bad:
 680         (void)m_free(m);
 681         return (EINVAL);
 682 }