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