ip_options.c revision 182311
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: head/sys/netinet/ip_options.c 182311 2008-08-27 23:52:03Z csjp $"); 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 71static int ip_dosourceroute = 0; 72SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW, 73 &ip_dosourceroute, 0, "Enable forwarding source routed IP packets"); 74 75static int ip_acceptsourceroute = 0; 76SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, 77 CTLFLAG_RW, &ip_acceptsourceroute, 0, 78 "Enable accepting source routed IP packets"); 79 80int ip_doopts = 1; /* 0 = ignore, 1 = process, 2 = reject */ 81SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW, 82 &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)"); 83 84static 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 */ 98int 99ip_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 */ 203nosourcerouting: 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 217dropit: 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); 365bad: 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 */ 375static void 376save_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 */ 402struct mbuf * 403ip_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 */ 463void 464ip_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 */ 489struct mbuf * 490ip_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 */ 539int 540ip_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 */ 583int 584ip_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 680bad: 681 (void)m_free(m); 682 return (EINVAL); 683} 684