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 static int ip_dosourceroute = 0; 69 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW, 70 &ip_dosourceroute, 0, "Enable forwarding source routed IP packets"); 71 72 static int ip_acceptsourceroute = 0; 73 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, 74 CTLFLAG_RW, &ip_acceptsourceroute, 0, 75 "Enable accepting source routed IP packets"); 76 77 int ip_doopts = 1; /* 0 = ignore, 1 = process, 2 = reject */ 78 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW, 79 &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)"); 80 81 static void save_rte(struct mbuf *m, u_char *, struct in_addr); 82 83 /* 84 * Do option processing on a datagram, possibly discarding it if bad options 85 * are encountered, or forwarding it if source-routed. 86 * 87 * The pass argument is used when operating in the IPSTEALTH mode to tell 88 * what options to process: [LS]SRR (pass 0) or the others (pass 1). The 89 * reason for as many as two passes is that when doing IPSTEALTH, non-routing 90 * options should be processed only if the packet is for us. 91 * 92 * Returns 1 if packet has been forwarded/freed, 0 if the packet should be 93 * processed further. 94 */ 95 int 96 ip_dooptions(struct mbuf *m, int pass) 97 { 98 struct ip *ip = mtod(m, struct ip *); 99 u_char *cp; 100 struct in_ifaddr *ia; 101 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 102 struct in_addr *sin, dst; 103 uint32_t ntime; 104 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 105 106 /* Ignore or reject packets with IP options. */ 107 if (ip_doopts == 0) 108 return 0; 109 else if (ip_doopts == 2) { 110 type = ICMP_UNREACH; 111 code = ICMP_UNREACH_FILTER_PROHIB; 112 goto bad; 113 } 114 115 dst = ip->ip_dst; 116 cp = (u_char *)(ip + 1); 117 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 118 for (; cnt > 0; cnt -= optlen, cp += optlen) { 119 opt = cp[IPOPT_OPTVAL]; 120 if (opt == IPOPT_EOL) 121 break; 122 if (opt == IPOPT_NOP) 123 optlen = 1; 124 else { 125 if (cnt < IPOPT_OLEN + sizeof(*cp)) { 126 code = &cp[IPOPT_OLEN] - (u_char *)ip; 127 goto bad; 128 } 129 optlen = cp[IPOPT_OLEN]; 130 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) { 131 code = &cp[IPOPT_OLEN] - (u_char *)ip; 132 goto bad; 133 } 134 } 135 switch (opt) { 136 137 default: 138 break; 139 140 /* 141 * Source routing with record. Find interface with current 142 * destination address. If none on this machine then drop if 143 * strictly routed, or do nothing if loosely routed. Record 144 * interface address and bring up next address component. If 145 * strictly routed make sure next address is on directly 146 * accessible net. 147 */ 148 case IPOPT_LSRR: 149 case IPOPT_SSRR: 150 #ifdef IPSTEALTH 151 if (V_ipstealth && pass > 0) 152 break; 153 #endif 154 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 155 code = &cp[IPOPT_OLEN] - (u_char *)ip; 156 goto bad; 157 } 158 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 159 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 160 goto bad; 161 } 162 ipaddr.sin_addr = ip->ip_dst; 163 if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr) 164 == 0) { 165 if (opt == IPOPT_SSRR) { 166 type = ICMP_UNREACH; 167 code = ICMP_UNREACH_SRCFAIL; 168 goto bad; 169 } 170 if (!ip_dosourceroute) 171 goto nosourcerouting; 172 /* 173 * Loose routing, and not at next destination 174 * yet; nothing to do except forward. 175 */ 176 break; 177 } 178 off--; /* 0 origin */ 179 if (off > optlen - (int)sizeof(struct in_addr)) { 180 /* 181 * End of source route. Should be for us. 182 */ 183 if (!ip_acceptsourceroute) 184 goto nosourcerouting; 185 save_rte(m, cp, ip->ip_src); 186 break; 187 } 188 #ifdef IPSTEALTH 189 if (V_ipstealth) 190 goto dropit; 191 #endif 192 if (!ip_dosourceroute) { 193 if (V_ipforwarding) { 194 char buf[16]; /* aaa.bbb.ccc.ddd\0 */ 195 /* 196 * Acting as a router, so generate 197 * ICMP 198 */ 199 nosourcerouting: 200 strcpy(buf, inet_ntoa(ip->ip_dst)); 201 log(LOG_WARNING, 202 "attempted source route from %s to %s\n", 203 inet_ntoa(ip->ip_src), buf); 204 type = ICMP_UNREACH; 205 code = ICMP_UNREACH_SRCFAIL; 206 goto bad; 207 } else { 208 /* 209 * Not acting as a router, so 210 * silently drop. 211 */ 212 #ifdef IPSTEALTH 213 dropit: 214 #endif 215 IPSTAT_INC(ips_cantforward); 216 m_freem(m); 217 return (1); 218 } 219 } 220 221 /* 222 * locate outgoing interface 223 */ 224 (void)memcpy(&ipaddr.sin_addr, cp + off, 225 sizeof(ipaddr.sin_addr)); 226 227 if (opt == IPOPT_SSRR) { 228 #define INA struct in_ifaddr * 229 #define SA struct sockaddr * 230 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL) 231 ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0); 232 } else 233 /* XXX MRT 0 for routing */ 234 ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m)); 235 if (ia == NULL) { 236 type = ICMP_UNREACH; 237 code = ICMP_UNREACH_SRCFAIL; 238 goto bad; 239 } 240 ip->ip_dst = ipaddr.sin_addr; 241 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 242 sizeof(struct in_addr)); 243 ifa_free(&ia->ia_ifa); 244 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 245 /* 246 * Let ip_intr's mcast routing check handle mcast pkts 247 */ 248 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 249 break; 250 251 case IPOPT_RR: 252 #ifdef IPSTEALTH 253 if (V_ipstealth && pass == 0) 254 break; 255 #endif 256 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 257 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 258 goto bad; 259 } 260 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 261 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 262 goto bad; 263 } 264 /* 265 * If no space remains, ignore. 266 */ 267 off--; /* 0 origin */ 268 if (off > optlen - (int)sizeof(struct in_addr)) 269 break; 270 (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst, 271 sizeof(ipaddr.sin_addr)); 272 /* 273 * Locate outgoing interface; if we're the 274 * destination, use the incoming interface (should be 275 * same). 276 */ 277 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL && 278 (ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m))) == NULL) { 279 type = ICMP_UNREACH; 280 code = ICMP_UNREACH_HOST; 281 goto bad; 282 } 283 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 284 sizeof(struct in_addr)); 285 ifa_free(&ia->ia_ifa); 286 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 287 break; 288 289 case IPOPT_TS: 290 #ifdef IPSTEALTH 291 if (V_ipstealth && pass == 0) 292 break; 293 #endif 294 code = cp - (u_char *)ip; 295 if (optlen < 4 || optlen > 40) { 296 code = &cp[IPOPT_OLEN] - (u_char *)ip; 297 goto bad; 298 } 299 if ((off = cp[IPOPT_OFFSET]) < 5) { 300 code = &cp[IPOPT_OLEN] - (u_char *)ip; 301 goto bad; 302 } 303 if (off > optlen - (int)sizeof(int32_t)) { 304 cp[IPOPT_OFFSET + 1] += (1 << 4); 305 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) { 306 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 307 goto bad; 308 } 309 break; 310 } 311 off--; /* 0 origin */ 312 sin = (struct in_addr *)(cp + off); 313 switch (cp[IPOPT_OFFSET + 1] & 0x0f) { 314 315 case IPOPT_TS_TSONLY: 316 break; 317 318 case IPOPT_TS_TSANDADDR: 319 if (off + sizeof(uint32_t) + 320 sizeof(struct in_addr) > optlen) { 321 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 322 goto bad; 323 } 324 ipaddr.sin_addr = dst; 325 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 326 m->m_pkthdr.rcvif); 327 if (ia == NULL) 328 continue; 329 (void)memcpy(sin, &IA_SIN(ia)->sin_addr, 330 sizeof(struct in_addr)); 331 ifa_free(&ia->ia_ifa); 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 && V_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_INC(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 } 683 684 /* 685 * Check for the presence of the IP Router Alert option [RFC2113] 686 * in the header of an IPv4 datagram. 687 * 688 * This call is not intended for use from the forwarding path; it is here 689 * so that protocol domains may check for the presence of the option. 690 * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert 691 * option does not have much relevance to the implementation, though this 692 * may change in future. 693 * Router alert options SHOULD be passed if running in IPSTEALTH mode and 694 * we are not the endpoint. 695 * Length checks on individual options should already have been peformed 696 * by ip_dooptions() therefore they are folded under INVARIANTS here. 697 * 698 * Return zero if not present or options are invalid, non-zero if present. 699 */ 700 int 701 ip_checkrouteralert(struct mbuf *m) 702 { 703 struct ip *ip = mtod(m, struct ip *); 704 u_char *cp; 705 int opt, optlen, cnt, found_ra; 706 707 found_ra = 0; 708 cp = (u_char *)(ip + 1); 709 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 710 for (; cnt > 0; cnt -= optlen, cp += optlen) { 711 opt = cp[IPOPT_OPTVAL]; 712 if (opt == IPOPT_EOL) 713 break; 714 if (opt == IPOPT_NOP) 715 optlen = 1; 716 else { 717 #ifdef INVARIANTS 718 if (cnt < IPOPT_OLEN + sizeof(*cp)) 719 break; 720 #endif 721 optlen = cp[IPOPT_OLEN]; 722 #ifdef INVARIANTS 723 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) 724 break; 725 #endif 726 } 727 switch (opt) { 728 case IPOPT_RA: 729 #ifdef INVARIANTS 730 if (optlen != IPOPT_OFFSET + sizeof(uint16_t) || 731 (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0)) 732 break; 733 else 734 #endif 735 found_ra = 1; 736 break; 737 default: 738 break; 739 } 740 } 741 742 return (found_ra); 743 } 744