1 /* 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. 6 * Copyright (c) 2005 Andre Oppermann, Internet Business Solutions AG. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include "opt_ipstealth.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/mbuf.h> 39 #include <sys/domain.h> 40 #include <sys/protosw.h> 41 #include <sys/socket.h> 42 #include <sys/time.h> 43 #include <sys/kernel.h> 44 #include <sys/syslog.h> 45 #include <sys/sysctl.h> 46 47 #include <net/if.h> 48 #include <net/if_types.h> 49 #include <net/if_var.h> 50 #include <net/if_dl.h> 51 #include <net/route.h> 52 #include <net/route/nhop.h> 53 #include <net/netisr.h> 54 #include <net/vnet.h> 55 56 #include <netinet/in.h> 57 #include <netinet/in_fib.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 VNET_DEFINE_STATIC(int, ip_dosourceroute); 70 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, 71 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip_dosourceroute), 0, 72 "Enable forwarding source routed IP packets"); 73 #define V_ip_dosourceroute VNET(ip_dosourceroute) 74 75 VNET_DEFINE_STATIC(int, ip_acceptsourceroute); 76 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, 77 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip_acceptsourceroute), 0, 78 "Enable accepting source routed IP packets"); 79 #define V_ip_acceptsourceroute VNET(ip_acceptsourceroute) 80 81 VNET_DEFINE(int, ip_doopts) = 1; /* 0 = ignore, 1 = process, 2 = reject */ 82 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_VNET | CTLFLAG_RW, 83 &VNET_NAME(ip_doopts), 0, "Enable IP options processing ([LS]SRR, RR, TS)"); 84 85 static void save_rte(struct mbuf *m, u_char *, struct in_addr); 86 87 /* 88 * Do option processing on a datagram, possibly discarding it if bad options 89 * are encountered, or forwarding it if source-routed. 90 * 91 * The pass argument is used when operating in the IPSTEALTH mode to tell 92 * what options to process: [LS]SRR (pass 0) or the others (pass 1). The 93 * reason for as many as two passes is that when doing IPSTEALTH, non-routing 94 * options should be processed only if the packet is for us. 95 * 96 * Returns 1 if packet has been forwarded/freed, 0 if the packet should be 97 * processed further. 98 */ 99 int 100 ip_dooptions(struct mbuf *m, int pass) 101 { 102 struct ip *ip = mtod(m, struct ip *); 103 u_char *cp; 104 struct in_ifaddr *ia; 105 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 106 struct in_addr *sin, dst; 107 uint32_t ntime; 108 struct nhop_object *nh; 109 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 110 111 NET_EPOCH_ASSERT(); 112 113 /* Ignore or reject packets with IP options. */ 114 if (V_ip_doopts == 0) 115 return 0; 116 else if (V_ip_doopts == 2) { 117 type = ICMP_UNREACH; 118 code = ICMP_UNREACH_FILTER_PROHIB; 119 goto bad; 120 } 121 122 dst = ip->ip_dst; 123 cp = (u_char *)(ip + 1); 124 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 125 for (; cnt > 0; cnt -= optlen, cp += optlen) { 126 opt = cp[IPOPT_OPTVAL]; 127 if (opt == IPOPT_EOL) 128 break; 129 if (opt == IPOPT_NOP) 130 optlen = 1; 131 else { 132 if (cnt < IPOPT_OLEN + sizeof(*cp)) { 133 code = &cp[IPOPT_OLEN] - (u_char *)ip; 134 goto bad; 135 } 136 optlen = cp[IPOPT_OLEN]; 137 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) { 138 code = &cp[IPOPT_OLEN] - (u_char *)ip; 139 goto bad; 140 } 141 } 142 switch (opt) { 143 default: 144 break; 145 146 /* 147 * Source routing with record. Find interface with current 148 * destination address. If none on this machine then drop if 149 * strictly routed, or do nothing if loosely routed. Record 150 * interface address and bring up next address component. If 151 * strictly routed make sure next address is on directly 152 * accessible net. 153 */ 154 case IPOPT_LSRR: 155 case IPOPT_SSRR: 156 #ifdef IPSTEALTH 157 if (V_ipstealth && pass > 0) 158 break; 159 #endif 160 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 161 code = &cp[IPOPT_OLEN] - (u_char *)ip; 162 goto bad; 163 } 164 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 165 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 166 goto bad; 167 } 168 ipaddr.sin_addr = ip->ip_dst; 169 if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr) 170 == 0) { 171 if (opt == IPOPT_SSRR) { 172 type = ICMP_UNREACH; 173 code = ICMP_UNREACH_SRCFAIL; 174 goto bad; 175 } 176 if (!V_ip_dosourceroute) 177 goto nosourcerouting; 178 /* 179 * Loose routing, and not at next destination 180 * yet; nothing to do except forward. 181 */ 182 break; 183 } 184 off--; /* 0 origin */ 185 if (off > optlen - (int)sizeof(struct in_addr)) { 186 /* 187 * End of source route. Should be for us. 188 */ 189 if (!V_ip_acceptsourceroute) 190 goto nosourcerouting; 191 save_rte(m, cp, ip->ip_src); 192 break; 193 } 194 #ifdef IPSTEALTH 195 if (V_ipstealth) 196 goto dropit; 197 #endif 198 if (!V_ip_dosourceroute) { 199 if (V_ipforwarding) { 200 char srcbuf[INET_ADDRSTRLEN]; 201 char dstbuf[INET_ADDRSTRLEN]; 202 203 /* 204 * Acting as a router, so generate 205 * ICMP 206 */ 207 nosourcerouting: 208 log(LOG_WARNING, 209 "attempted source route from %s " 210 "to %s\n", 211 inet_ntoa_r(ip->ip_src, srcbuf), 212 inet_ntoa_r(ip->ip_dst, dstbuf)); 213 type = ICMP_UNREACH; 214 code = ICMP_UNREACH_SRCFAIL; 215 goto bad; 216 } else { 217 /* 218 * Not acting as a router, so 219 * silently drop. 220 */ 221 #ifdef IPSTEALTH 222 dropit: 223 #endif 224 IPSTAT_INC(ips_cantforward); 225 m_freem(m); 226 return (1); 227 } 228 } 229 230 /* 231 * locate outgoing interface 232 */ 233 (void)memcpy(&ipaddr.sin_addr, cp + off, 234 sizeof(ipaddr.sin_addr)); 235 236 type = ICMP_UNREACH; 237 code = ICMP_UNREACH_SRCFAIL; 238 239 if (opt == IPOPT_SSRR) { 240 #define INA struct in_ifaddr * 241 #define SA struct sockaddr * 242 ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr, 243 RT_ALL_FIBS); 244 if (ia == NULL) 245 ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0, 246 RT_ALL_FIBS); 247 if (ia == NULL) 248 goto bad; 249 250 memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 251 sizeof(struct in_addr)); 252 } else { 253 /* XXX MRT 0 for routing */ 254 nh = fib4_lookup(M_GETFIB(m), ipaddr.sin_addr, 255 0, NHR_NONE, 0); 256 if (nh == NULL) 257 goto bad; 258 259 memcpy(cp + off, &(IA_SIN(nh->nh_ifa)->sin_addr), 260 sizeof(struct in_addr)); 261 } 262 263 ip->ip_dst = ipaddr.sin_addr; 264 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 265 /* 266 * Let ip_intr's mcast routing check handle mcast pkts 267 */ 268 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 269 break; 270 271 case IPOPT_RR: 272 #ifdef IPSTEALTH 273 if (V_ipstealth && pass == 0) 274 break; 275 #endif 276 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 277 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 278 goto bad; 279 } 280 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 281 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 282 goto bad; 283 } 284 /* 285 * If no space remains, ignore. 286 */ 287 off--; /* 0 origin */ 288 if (off > optlen - (int)sizeof(struct in_addr)) 289 break; 290 (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst, 291 sizeof(ipaddr.sin_addr)); 292 /* 293 * Locate outgoing interface; if we're the 294 * destination, use the incoming interface (should be 295 * same). 296 */ 297 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) != NULL) { 298 memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 299 sizeof(struct in_addr)); 300 } else if ((nh = fib4_lookup(M_GETFIB(m), 301 ipaddr.sin_addr, 0, NHR_NONE, 0)) != NULL) { 302 memcpy(cp + off, &(IA_SIN(nh->nh_ifa)->sin_addr), 303 sizeof(struct in_addr)); 304 } else { 305 type = ICMP_UNREACH; 306 code = ICMP_UNREACH_HOST; 307 goto bad; 308 } 309 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 310 break; 311 312 case IPOPT_TS: 313 #ifdef IPSTEALTH 314 if (V_ipstealth && pass == 0) 315 break; 316 #endif 317 code = cp - (u_char *)ip; 318 if (optlen < 4 || optlen > 40) { 319 code = &cp[IPOPT_OLEN] - (u_char *)ip; 320 goto bad; 321 } 322 if ((off = cp[IPOPT_OFFSET]) < 5) { 323 code = &cp[IPOPT_OLEN] - (u_char *)ip; 324 goto bad; 325 } 326 if (off > optlen - (int)sizeof(int32_t)) { 327 cp[IPOPT_OFFSET + 1] += (1 << 4); 328 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) { 329 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 330 goto bad; 331 } 332 break; 333 } 334 off--; /* 0 origin */ 335 sin = (struct in_addr *)(cp + off); 336 switch (cp[IPOPT_OFFSET + 1] & 0x0f) { 337 case IPOPT_TS_TSONLY: 338 break; 339 340 case IPOPT_TS_TSANDADDR: 341 if (off + sizeof(uint32_t) + 342 sizeof(struct in_addr) > optlen) { 343 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 344 goto bad; 345 } 346 ipaddr.sin_addr = dst; 347 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 348 m->m_pkthdr.rcvif); 349 if (ia == NULL) 350 continue; 351 (void)memcpy(sin, &IA_SIN(ia)->sin_addr, 352 sizeof(struct in_addr)); 353 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 354 off += sizeof(struct in_addr); 355 break; 356 357 case IPOPT_TS_PRESPEC: 358 if (off + sizeof(uint32_t) + 359 sizeof(struct in_addr) > optlen) { 360 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 361 goto bad; 362 } 363 (void)memcpy(&ipaddr.sin_addr, sin, 364 sizeof(struct in_addr)); 365 if (ifa_ifwithaddr_check((SA)&ipaddr) == 0) 366 continue; 367 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 368 off += sizeof(struct in_addr); 369 break; 370 371 default: 372 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip; 373 goto bad; 374 } 375 ntime = iptime(); 376 (void)memcpy(cp + off, &ntime, sizeof(uint32_t)); 377 cp[IPOPT_OFFSET] += sizeof(uint32_t); 378 } 379 } 380 if (forward && V_ipforwarding) { 381 ip_forward(m, 1); 382 return (1); 383 } 384 return (0); 385 bad: 386 icmp_error(m, type, code, 0, 0); 387 IPSTAT_INC(ips_badoptions); 388 return (1); 389 } 390 391 /* 392 * Save incoming source route for use in replies, to be picked up later by 393 * ip_srcroute if the receiver is interested. 394 */ 395 static void 396 save_rte(struct mbuf *m, u_char *option, struct in_addr dst) 397 { 398 unsigned olen; 399 struct ipopt_tag *opts; 400 401 opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS, 402 sizeof(struct ipopt_tag), M_NOWAIT); 403 if (opts == NULL) 404 return; 405 406 olen = option[IPOPT_OLEN]; 407 if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) { 408 m_tag_free((struct m_tag *)opts); 409 return; 410 } 411 bcopy(option, opts->ip_srcrt.srcopt, olen); 412 opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 413 opts->ip_srcrt.dst = dst; 414 m_tag_prepend(m, (struct m_tag *)opts); 415 } 416 417 /* 418 * Retrieve incoming source route for use in replies, in the same form used 419 * by setsockopt. The first hop is placed before the options, will be 420 * removed later. 421 */ 422 struct mbuf * 423 ip_srcroute(struct mbuf *m0) 424 { 425 struct in_addr *p, *q; 426 struct mbuf *m; 427 struct ipopt_tag *opts; 428 429 opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL); 430 if (opts == NULL) 431 return (NULL); 432 433 if (opts->ip_nhops == 0) 434 return (NULL); 435 m = m_get(M_NOWAIT, MT_DATA); 436 if (m == NULL) 437 return (NULL); 438 439 #define OPTSIZ (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt)) 440 441 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 442 m->m_len = opts->ip_nhops * sizeof(struct in_addr) + 443 sizeof(struct in_addr) + OPTSIZ; 444 445 /* 446 * First, save first hop for return route. 447 */ 448 p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]); 449 *(mtod(m, struct in_addr *)) = *p--; 450 451 /* 452 * Copy option fields and padding (nop) to mbuf. 453 */ 454 opts->ip_srcrt.nop = IPOPT_NOP; 455 opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 456 (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), 457 &(opts->ip_srcrt.nop), OPTSIZ); 458 q = (struct in_addr *)(mtod(m, caddr_t) + 459 sizeof(struct in_addr) + OPTSIZ); 460 #undef OPTSIZ 461 /* 462 * Record return path as an IP source route, reversing the path 463 * (pointers are now aligned). 464 */ 465 while (p >= opts->ip_srcrt.route) { 466 *q++ = *p--; 467 } 468 /* 469 * Last hop goes to final destination. 470 */ 471 *q = opts->ip_srcrt.dst; 472 m_tag_delete(m0, (struct m_tag *)opts); 473 return (m); 474 } 475 476 /* 477 * Strip out IP options, at higher level protocol in the kernel. 478 */ 479 void 480 ip_stripoptions(struct mbuf *m) 481 { 482 struct ip *ip = mtod(m, struct ip *); 483 int olen; 484 485 olen = (ip->ip_hl << 2) - sizeof(struct ip); 486 m->m_len -= olen; 487 if (m->m_flags & M_PKTHDR) 488 m->m_pkthdr.len -= olen; 489 ip->ip_len = htons(ntohs(ip->ip_len) - olen); 490 ip->ip_hl = sizeof(struct ip) >> 2; 491 492 bcopy((char *)ip + sizeof(struct ip) + olen, (ip + 1), 493 (size_t )(m->m_len - sizeof(struct ip))); 494 } 495 496 /* 497 * Insert IP options into preformed packet. Adjust IP destination as 498 * required for IP source routing, as indicated by a non-zero in_addr at the 499 * start of the options. 500 * 501 * XXX This routine assumes that the packet has no options in place. 502 */ 503 struct mbuf * 504 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen) 505 { 506 struct ipoption *p = mtod(opt, struct ipoption *); 507 struct mbuf *n; 508 struct ip *ip = mtod(m, struct ip *); 509 unsigned optlen; 510 511 optlen = opt->m_len - sizeof(p->ipopt_dst); 512 if (optlen + ntohs(ip->ip_len) > IP_MAXPACKET) { 513 *phlen = 0; 514 return (m); /* XXX should fail */ 515 } 516 KASSERT((m->m_flags & M_EXTPG) == 0, ("%s: mbuf %p is unmapped", 517 __func__, m)); 518 if (p->ipopt_dst.s_addr) 519 ip->ip_dst = p->ipopt_dst; 520 if (!M_WRITABLE(m) || M_LEADINGSPACE(m) < optlen) { 521 n = m_gethdr(M_NOWAIT, MT_DATA); 522 if (n == NULL) { 523 *phlen = 0; 524 return (m); 525 } 526 m_move_pkthdr(n, m); 527 n->m_pkthdr.rcvif = NULL; 528 n->m_pkthdr.len += optlen; 529 m->m_len -= sizeof(struct ip); 530 m->m_data += sizeof(struct ip); 531 n->m_next = m; 532 m = n; 533 m->m_len = optlen + sizeof(struct ip); 534 m->m_data += max_linkhdr; 535 bcopy(ip, mtod(m, void *), sizeof(struct ip)); 536 } else { 537 m->m_data -= optlen; 538 m->m_len += optlen; 539 m->m_pkthdr.len += optlen; 540 bcopy(ip, mtod(m, void *), sizeof(struct ip)); 541 } 542 ip = mtod(m, struct ip *); 543 bcopy(p->ipopt_list, ip + 1, optlen); 544 *phlen = sizeof(struct ip) + optlen; 545 ip->ip_v = IPVERSION; 546 ip->ip_hl = *phlen >> 2; 547 ip->ip_len = htons(ntohs(ip->ip_len) + optlen); 548 return (m); 549 } 550 551 /* 552 * Copy options from ip to jp, omitting those not copied during 553 * fragmentation. 554 */ 555 int 556 ip_optcopy(struct ip *ip, struct ip *jp) 557 { 558 u_char *cp, *dp; 559 int opt, optlen, cnt; 560 561 cp = (u_char *)(ip + 1); 562 dp = (u_char *)(jp + 1); 563 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 564 for (; cnt > 0; cnt -= optlen, cp += optlen) { 565 opt = cp[0]; 566 if (opt == IPOPT_EOL) 567 break; 568 if (opt == IPOPT_NOP) { 569 /* Preserve for IP mcast tunnel's LSRR alignment. */ 570 *dp++ = IPOPT_NOP; 571 optlen = 1; 572 continue; 573 } 574 575 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp), 576 ("ip_optcopy: malformed ipv4 option")); 577 optlen = cp[IPOPT_OLEN]; 578 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt, 579 ("ip_optcopy: malformed ipv4 option")); 580 581 /* Bogus lengths should have been caught by ip_dooptions. */ 582 if (optlen > cnt) 583 optlen = cnt; 584 if (IPOPT_COPIED(opt)) { 585 bcopy(cp, dp, optlen); 586 dp += optlen; 587 } 588 } 589 for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++) 590 *dp++ = IPOPT_EOL; 591 return (optlen); 592 } 593 594 /* 595 * Set up IP options in pcb for insertion in output packets. Store in mbuf 596 * with pointer in pcbopt, adding pseudo-option with destination address if 597 * source routed. 598 */ 599 int 600 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m) 601 { 602 int cnt, optlen; 603 u_char *cp; 604 struct mbuf **pcbopt; 605 u_char opt; 606 607 INP_WLOCK_ASSERT(inp); 608 609 pcbopt = &inp->inp_options; 610 611 /* turn off any old options */ 612 if (*pcbopt) 613 (void)m_free(*pcbopt); 614 *pcbopt = NULL; 615 if (m == NULL || m->m_len == 0) { 616 /* 617 * Only turning off any previous options. 618 */ 619 if (m != NULL) 620 (void)m_free(m); 621 return (0); 622 } 623 624 if (m->m_len % sizeof(int32_t)) 625 goto bad; 626 /* 627 * IP first-hop destination address will be stored before actual 628 * options; move other options back and clear it when none present. 629 */ 630 if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN]) 631 goto bad; 632 cnt = m->m_len; 633 m->m_len += sizeof(struct in_addr); 634 cp = mtod(m, u_char *) + sizeof(struct in_addr); 635 bcopy(mtod(m, void *), cp, (unsigned)cnt); 636 bzero(mtod(m, void *), sizeof(struct in_addr)); 637 638 for (; cnt > 0; cnt -= optlen, cp += optlen) { 639 opt = cp[IPOPT_OPTVAL]; 640 if (opt == IPOPT_EOL) 641 break; 642 if (opt == IPOPT_NOP) 643 optlen = 1; 644 else { 645 if (cnt < IPOPT_OLEN + sizeof(*cp)) 646 goto bad; 647 optlen = cp[IPOPT_OLEN]; 648 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) 649 goto bad; 650 } 651 switch (opt) { 652 default: 653 break; 654 655 case IPOPT_LSRR: 656 case IPOPT_SSRR: 657 /* 658 * User process specifies route as: 659 * 660 * ->A->B->C->D 661 * 662 * D must be our final destination (but we can't 663 * check that since we may not have connected yet). 664 * A is first hop destination, which doesn't appear 665 * in actual IP option, but is stored before the 666 * options. 667 */ 668 /* XXX-BZ PRIV_NETINET_SETHDROPTS? */ 669 if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr)) 670 goto bad; 671 m->m_len -= sizeof(struct in_addr); 672 cnt -= sizeof(struct in_addr); 673 optlen -= sizeof(struct in_addr); 674 cp[IPOPT_OLEN] = optlen; 675 /* 676 * Move first hop before start of options. 677 */ 678 bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t), 679 sizeof(struct in_addr)); 680 /* 681 * Then copy rest of options back 682 * to close up the deleted entry. 683 */ 684 bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)), 685 &cp[IPOPT_OFFSET+1], 686 (unsigned)cnt - (IPOPT_MINOFF - 1)); 687 break; 688 } 689 } 690 if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr)) 691 goto bad; 692 *pcbopt = m; 693 return (0); 694 695 bad: 696 (void)m_free(m); 697 return (EINVAL); 698 } 699 700 /* 701 * Check for the presence of the IP Router Alert option [RFC2113] 702 * in the header of an IPv4 datagram. 703 * 704 * This call is not intended for use from the forwarding path; it is here 705 * so that protocol domains may check for the presence of the option. 706 * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert 707 * option does not have much relevance to the implementation, though this 708 * may change in future. 709 * Router alert options SHOULD be passed if running in IPSTEALTH mode and 710 * we are not the endpoint. 711 * Length checks on individual options should already have been performed 712 * by ip_dooptions() therefore they are folded under INVARIANTS here. 713 * 714 * Return zero if not present or options are invalid, non-zero if present. 715 */ 716 int 717 ip_checkrouteralert(struct mbuf *m) 718 { 719 struct ip *ip = mtod(m, struct ip *); 720 u_char *cp; 721 int opt, optlen, cnt, found_ra; 722 723 found_ra = 0; 724 cp = (u_char *)(ip + 1); 725 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 726 for (; cnt > 0; cnt -= optlen, cp += optlen) { 727 opt = cp[IPOPT_OPTVAL]; 728 if (opt == IPOPT_EOL) 729 break; 730 if (opt == IPOPT_NOP) 731 optlen = 1; 732 else { 733 #ifdef INVARIANTS 734 if (cnt < IPOPT_OLEN + sizeof(*cp)) 735 break; 736 #endif 737 optlen = cp[IPOPT_OLEN]; 738 #ifdef INVARIANTS 739 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) 740 break; 741 #endif 742 } 743 switch (opt) { 744 case IPOPT_RA: 745 #ifdef INVARIANTS 746 if (optlen != IPOPT_OFFSET + sizeof(uint16_t) || 747 (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0)) 748 break; 749 else 750 #endif 751 found_ra = 1; 752 break; 753 default: 754 break; 755 } 756 } 757 758 return (found_ra); 759 } 760