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 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/mbuf.h> 40 #include <sys/domain.h> 41 #include <sys/protosw.h> 42 #include <sys/socket.h> 43 #include <sys/time.h> 44 #include <sys/kernel.h> 45 #include <sys/syslog.h> 46 #include <sys/sysctl.h> 47 48 #include <net/if.h> 49 #include <net/if_types.h> 50 #include <net/if_var.h> 51 #include <net/if_dl.h> 52 #include <net/route.h> 53 #include <net/netisr.h> 54 #include <net/vnet.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 (V_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 if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr) 166 == 0) { 167 if (opt == IPOPT_SSRR) { 168 type = ICMP_UNREACH; 169 code = ICMP_UNREACH_SRCFAIL; 170 goto bad; 171 } 172 if (!ip_dosourceroute) 173 goto nosourcerouting; 174 /* 175 * Loose routing, and not at next destination 176 * yet; nothing to do except forward. 177 */ 178 break; 179 } 180 off--; /* 0 origin */ 181 if (off > optlen - (int)sizeof(struct in_addr)) { 182 /* 183 * End of source route. Should be for us. 184 */ 185 if (!ip_acceptsourceroute) 186 goto nosourcerouting; 187 save_rte(m, cp, ip->ip_src); 188 break; 189 } 190 #ifdef IPSTEALTH 191 if (V_ipstealth) 192 goto dropit; 193 #endif 194 if (!ip_dosourceroute) { 195 if (V_ipforwarding) { 196 char buf[16]; /* aaa.bbb.ccc.ddd\0 */ 197 /* 198 * Acting as a router, so generate 199 * ICMP 200 */ 201 nosourcerouting: 202 strcpy(buf, inet_ntoa(ip->ip_dst)); 203 log(LOG_WARNING, 204 "attempted source route from %s to %s\n", 205 inet_ntoa(ip->ip_src), buf); 206 type = ICMP_UNREACH; 207 code = ICMP_UNREACH_SRCFAIL; 208 goto bad; 209 } else { 210 /* 211 * Not acting as a router, so 212 * silently drop. 213 */ 214 #ifdef IPSTEALTH 215 dropit: 216 #endif 217 IPSTAT_INC(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 /* XXX MRT 0 for routing */ 236 ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m)); 237 if (ia == NULL) { 238 type = ICMP_UNREACH; 239 code = ICMP_UNREACH_SRCFAIL; 240 goto bad; 241 } 242 ip->ip_dst = ipaddr.sin_addr; 243 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 244 sizeof(struct in_addr)); 245 ifa_free(&ia->ia_ifa); 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 (V_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 ifa_free(&ia->ia_ifa); 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(uint32_t) + 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 ifa_free(&ia->ia_ifa); 334 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 335 off += sizeof(struct in_addr); 336 break; 337 338 case IPOPT_TS_PRESPEC: 339 if (off + sizeof(uint32_t) + 340 sizeof(struct in_addr) > optlen) { 341 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 342 goto bad; 343 } 344 (void)memcpy(&ipaddr.sin_addr, sin, 345 sizeof(struct in_addr)); 346 if (ifa_ifwithaddr((SA)&ipaddr) == NULL) 347 continue; 348 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 349 off += sizeof(struct in_addr); 350 break; 351 352 default: 353 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip; 354 goto bad; 355 } 356 ntime = iptime(); 357 (void)memcpy(cp + off, &ntime, sizeof(uint32_t)); 358 cp[IPOPT_OFFSET] += sizeof(uint32_t); 359 } 360 } 361 if (forward && V_ipforwarding) { 362 ip_forward(m, 1); 363 return (1); 364 } 365 return (0); 366 bad: 367 icmp_error(m, type, code, 0, 0); 368 IPSTAT_INC(ips_badoptions); 369 return (1); 370 } 371 372 /* 373 * Save incoming source route for use in replies, to be picked up later by 374 * ip_srcroute if the receiver is interested. 375 */ 376 static void 377 save_rte(struct mbuf *m, u_char *option, struct in_addr dst) 378 { 379 unsigned olen; 380 struct ipopt_tag *opts; 381 382 opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS, 383 sizeof(struct ipopt_tag), M_NOWAIT); 384 if (opts == NULL) 385 return; 386 387 olen = option[IPOPT_OLEN]; 388 if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) { 389 m_tag_free((struct m_tag *)opts); 390 return; 391 } 392 bcopy(option, opts->ip_srcrt.srcopt, olen); 393 opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 394 opts->ip_srcrt.dst = dst; 395 m_tag_prepend(m, (struct m_tag *)opts); 396 } 397 398 /* 399 * Retrieve incoming source route for use in replies, in the same form used 400 * by setsockopt. The first hop is placed before the options, will be 401 * removed later. 402 */ 403 struct mbuf * 404 ip_srcroute(struct mbuf *m0) 405 { 406 struct in_addr *p, *q; 407 struct mbuf *m; 408 struct ipopt_tag *opts; 409 410 opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL); 411 if (opts == NULL) 412 return (NULL); 413 414 if (opts->ip_nhops == 0) 415 return (NULL); 416 m = m_get(M_DONTWAIT, MT_DATA); 417 if (m == NULL) 418 return (NULL); 419 420 #define OPTSIZ (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt)) 421 422 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 423 m->m_len = opts->ip_nhops * sizeof(struct in_addr) + 424 sizeof(struct in_addr) + OPTSIZ; 425 426 /* 427 * First, save first hop for return route. 428 */ 429 p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]); 430 *(mtod(m, struct in_addr *)) = *p--; 431 432 /* 433 * Copy option fields and padding (nop) to mbuf. 434 */ 435 opts->ip_srcrt.nop = IPOPT_NOP; 436 opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 437 (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), 438 &(opts->ip_srcrt.nop), OPTSIZ); 439 q = (struct in_addr *)(mtod(m, caddr_t) + 440 sizeof(struct in_addr) + OPTSIZ); 441 #undef OPTSIZ 442 /* 443 * Record return path as an IP source route, reversing the path 444 * (pointers are now aligned). 445 */ 446 while (p >= opts->ip_srcrt.route) { 447 *q++ = *p--; 448 } 449 /* 450 * Last hop goes to final destination. 451 */ 452 *q = opts->ip_srcrt.dst; 453 m_tag_delete(m0, (struct m_tag *)opts); 454 return (m); 455 } 456 457 /* 458 * Strip out IP options, at higher level protocol in the kernel. Second 459 * argument is buffer to which options will be moved, and return value is 460 * their length. 461 * 462 * XXX should be deleted; last arg currently ignored. 463 */ 464 void 465 ip_stripoptions(struct mbuf *m, struct mbuf *mopt) 466 { 467 int i; 468 struct ip *ip = mtod(m, struct ip *); 469 caddr_t opts; 470 int olen; 471 472 olen = (ip->ip_hl << 2) - sizeof (struct ip); 473 opts = (caddr_t)(ip + 1); 474 i = m->m_len - (sizeof (struct ip) + olen); 475 bcopy(opts + olen, opts, (unsigned)i); 476 m->m_len -= olen; 477 if (m->m_flags & M_PKTHDR) 478 m->m_pkthdr.len -= olen; 479 ip->ip_v = IPVERSION; 480 ip->ip_hl = sizeof(struct ip) >> 2; 481 } 482 483 /* 484 * Insert IP options into preformed packet. Adjust IP destination as 485 * required for IP source routing, as indicated by a non-zero in_addr at the 486 * start of the options. 487 * 488 * XXX This routine assumes that the packet has no options in place. 489 */ 490 struct mbuf * 491 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen) 492 { 493 struct ipoption *p = mtod(opt, struct ipoption *); 494 struct mbuf *n; 495 struct ip *ip = mtod(m, struct ip *); 496 unsigned optlen; 497 498 optlen = opt->m_len - sizeof(p->ipopt_dst); 499 if (optlen + ip->ip_len > IP_MAXPACKET) { 500 *phlen = 0; 501 return (m); /* XXX should fail */ 502 } 503 if (p->ipopt_dst.s_addr) 504 ip->ip_dst = p->ipopt_dst; 505 if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) { 506 MGETHDR(n, M_DONTWAIT, MT_DATA); 507 if (n == NULL) { 508 *phlen = 0; 509 return (m); 510 } 511 M_MOVE_PKTHDR(n, m); 512 n->m_pkthdr.rcvif = NULL; 513 n->m_pkthdr.len += optlen; 514 m->m_len -= sizeof(struct ip); 515 m->m_data += sizeof(struct ip); 516 n->m_next = m; 517 m = n; 518 m->m_len = optlen + sizeof(struct ip); 519 m->m_data += max_linkhdr; 520 bcopy(ip, mtod(m, void *), sizeof(struct ip)); 521 } else { 522 m->m_data -= optlen; 523 m->m_len += optlen; 524 m->m_pkthdr.len += optlen; 525 bcopy(ip, mtod(m, void *), sizeof(struct ip)); 526 } 527 ip = mtod(m, struct ip *); 528 bcopy(p->ipopt_list, ip + 1, optlen); 529 *phlen = sizeof(struct ip) + optlen; 530 ip->ip_v = IPVERSION; 531 ip->ip_hl = *phlen >> 2; 532 ip->ip_len += optlen; 533 return (m); 534 } 535 536 /* 537 * Copy options from ip to jp, omitting those not copied during 538 * fragmentation. 539 */ 540 int 541 ip_optcopy(struct ip *ip, struct ip *jp) 542 { 543 u_char *cp, *dp; 544 int opt, optlen, cnt; 545 546 cp = (u_char *)(ip + 1); 547 dp = (u_char *)(jp + 1); 548 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 549 for (; cnt > 0; cnt -= optlen, cp += optlen) { 550 opt = cp[0]; 551 if (opt == IPOPT_EOL) 552 break; 553 if (opt == IPOPT_NOP) { 554 /* Preserve for IP mcast tunnel's LSRR alignment. */ 555 *dp++ = IPOPT_NOP; 556 optlen = 1; 557 continue; 558 } 559 560 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp), 561 ("ip_optcopy: malformed ipv4 option")); 562 optlen = cp[IPOPT_OLEN]; 563 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt, 564 ("ip_optcopy: malformed ipv4 option")); 565 566 /* Bogus lengths should have been caught by ip_dooptions. */ 567 if (optlen > cnt) 568 optlen = cnt; 569 if (IPOPT_COPIED(opt)) { 570 bcopy(cp, dp, optlen); 571 dp += optlen; 572 } 573 } 574 for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++) 575 *dp++ = IPOPT_EOL; 576 return (optlen); 577 } 578 579 /* 580 * Set up IP options in pcb for insertion in output packets. Store in mbuf 581 * with pointer in pcbopt, adding pseudo-option with destination address if 582 * source routed. 583 */ 584 int 585 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m) 586 { 587 int cnt, optlen; 588 u_char *cp; 589 struct mbuf **pcbopt; 590 u_char opt; 591 592 INP_WLOCK_ASSERT(inp); 593 594 pcbopt = &inp->inp_options; 595 596 /* turn off any old options */ 597 if (*pcbopt) 598 (void)m_free(*pcbopt); 599 *pcbopt = 0; 600 if (m == NULL || m->m_len == 0) { 601 /* 602 * Only turning off any previous options. 603 */ 604 if (m != NULL) 605 (void)m_free(m); 606 return (0); 607 } 608 609 if (m->m_len % sizeof(int32_t)) 610 goto bad; 611 /* 612 * IP first-hop destination address will be stored before actual 613 * options; move other options back and clear it when none present. 614 */ 615 if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN]) 616 goto bad; 617 cnt = m->m_len; 618 m->m_len += sizeof(struct in_addr); 619 cp = mtod(m, u_char *) + sizeof(struct in_addr); 620 bcopy(mtod(m, void *), cp, (unsigned)cnt); 621 bzero(mtod(m, void *), sizeof(struct in_addr)); 622 623 for (; cnt > 0; cnt -= optlen, cp += optlen) { 624 opt = cp[IPOPT_OPTVAL]; 625 if (opt == IPOPT_EOL) 626 break; 627 if (opt == IPOPT_NOP) 628 optlen = 1; 629 else { 630 if (cnt < IPOPT_OLEN + sizeof(*cp)) 631 goto bad; 632 optlen = cp[IPOPT_OLEN]; 633 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) 634 goto bad; 635 } 636 switch (opt) { 637 638 default: 639 break; 640 641 case IPOPT_LSRR: 642 case IPOPT_SSRR: 643 /* 644 * User process specifies route as: 645 * 646 * ->A->B->C->D 647 * 648 * D must be our final destination (but we can't 649 * check that since we may not have connected yet). 650 * A is first hop destination, which doesn't appear 651 * in actual IP option, but is stored before the 652 * options. 653 */ 654 /* XXX-BZ PRIV_NETINET_SETHDROPTS? */ 655 if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr)) 656 goto bad; 657 m->m_len -= sizeof(struct in_addr); 658 cnt -= sizeof(struct in_addr); 659 optlen -= sizeof(struct in_addr); 660 cp[IPOPT_OLEN] = optlen; 661 /* 662 * Move first hop before start of options. 663 */ 664 bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t), 665 sizeof(struct in_addr)); 666 /* 667 * Then copy rest of options back 668 * to close up the deleted entry. 669 */ 670 bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)), 671 &cp[IPOPT_OFFSET+1], 672 (unsigned)cnt - (IPOPT_MINOFF - 1)); 673 break; 674 } 675 } 676 if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr)) 677 goto bad; 678 *pcbopt = m; 679 return (0); 680 681 bad: 682 (void)m_free(m); 683 return (EINVAL); 684 } 685 686 /* 687 * Check for the presence of the IP Router Alert option [RFC2113] 688 * in the header of an IPv4 datagram. 689 * 690 * This call is not intended for use from the forwarding path; it is here 691 * so that protocol domains may check for the presence of the option. 692 * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert 693 * option does not have much relevance to the implementation, though this 694 * may change in future. 695 * Router alert options SHOULD be passed if running in IPSTEALTH mode and 696 * we are not the endpoint. 697 * Length checks on individual options should already have been peformed 698 * by ip_dooptions() therefore they are folded under INVARIANTS here. 699 * 700 * Return zero if not present or options are invalid, non-zero if present. 701 */ 702 int 703 ip_checkrouteralert(struct mbuf *m) 704 { 705 struct ip *ip = mtod(m, struct ip *); 706 u_char *cp; 707 int opt, optlen, cnt, found_ra; 708 709 found_ra = 0; 710 cp = (u_char *)(ip + 1); 711 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 712 for (; cnt > 0; cnt -= optlen, cp += optlen) { 713 opt = cp[IPOPT_OPTVAL]; 714 if (opt == IPOPT_EOL) 715 break; 716 if (opt == IPOPT_NOP) 717 optlen = 1; 718 else { 719 #ifdef INVARIANTS 720 if (cnt < IPOPT_OLEN + sizeof(*cp)) 721 break; 722 #endif 723 optlen = cp[IPOPT_OLEN]; 724 #ifdef INVARIANTS 725 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) 726 break; 727 #endif 728 } 729 switch (opt) { 730 case IPOPT_RA: 731 #ifdef INVARIANTS 732 if (optlen != IPOPT_OFFSET + sizeof(uint16_t) || 733 (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0)) 734 break; 735 else 736 #endif 737 found_ra = 1; 738 break; 739 default: 740 break; 741 } 742 } 743 744 return (found_ra); 745 } 746