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 * 3. 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_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 static VNET_DEFINE(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 static VNET_DEFINE(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 nhop4_extended nh_ext; 109 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 110 111 /* Ignore or reject packets with IP options. */ 112 if (V_ip_doopts == 0) 113 return 0; 114 else if (V_ip_doopts == 2) { 115 type = ICMP_UNREACH; 116 code = ICMP_UNREACH_FILTER_PROHIB; 117 goto bad; 118 } 119 120 dst = ip->ip_dst; 121 cp = (u_char *)(ip + 1); 122 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 123 for (; cnt > 0; cnt -= optlen, cp += optlen) { 124 opt = cp[IPOPT_OPTVAL]; 125 if (opt == IPOPT_EOL) 126 break; 127 if (opt == IPOPT_NOP) 128 optlen = 1; 129 else { 130 if (cnt < IPOPT_OLEN + sizeof(*cp)) { 131 code = &cp[IPOPT_OLEN] - (u_char *)ip; 132 goto bad; 133 } 134 optlen = cp[IPOPT_OLEN]; 135 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) { 136 code = &cp[IPOPT_OLEN] - (u_char *)ip; 137 goto bad; 138 } 139 } 140 switch (opt) { 141 142 default: 143 break; 144 145 /* 146 * Source routing with record. Find interface with current 147 * destination address. If none on this machine then drop if 148 * strictly routed, or do nothing if loosely routed. Record 149 * interface address and bring up next address component. If 150 * strictly routed make sure next address is on directly 151 * accessible net. 152 */ 153 case IPOPT_LSRR: 154 case IPOPT_SSRR: 155 #ifdef IPSTEALTH 156 if (V_ipstealth && pass > 0) 157 break; 158 #endif 159 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 160 code = &cp[IPOPT_OLEN] - (u_char *)ip; 161 goto bad; 162 } 163 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 164 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 165 goto bad; 166 } 167 ipaddr.sin_addr = ip->ip_dst; 168 if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr) 169 == 0) { 170 if (opt == IPOPT_SSRR) { 171 type = ICMP_UNREACH; 172 code = ICMP_UNREACH_SRCFAIL; 173 goto bad; 174 } 175 if (!V_ip_dosourceroute) 176 goto nosourcerouting; 177 /* 178 * Loose routing, and not at next destination 179 * yet; nothing to do except forward. 180 */ 181 break; 182 } 183 off--; /* 0 origin */ 184 if (off > optlen - (int)sizeof(struct in_addr)) { 185 /* 186 * End of source route. Should be for us. 187 */ 188 if (!V_ip_acceptsourceroute) 189 goto nosourcerouting; 190 save_rte(m, cp, ip->ip_src); 191 break; 192 } 193 #ifdef IPSTEALTH 194 if (V_ipstealth) 195 goto dropit; 196 #endif 197 if (!V_ip_dosourceroute) { 198 if (V_ipforwarding) { 199 char srcbuf[INET_ADDRSTRLEN]; 200 char dstbuf[INET_ADDRSTRLEN]; 201 202 /* 203 * Acting as a router, so generate 204 * ICMP 205 */ 206 nosourcerouting: 207 log(LOG_WARNING, 208 "attempted source route from %s " 209 "to %s\n", 210 inet_ntoa_r(ip->ip_src, srcbuf), 211 inet_ntoa_r(ip->ip_dst, dstbuf)); 212 type = ICMP_UNREACH; 213 code = ICMP_UNREACH_SRCFAIL; 214 goto bad; 215 } else { 216 /* 217 * Not acting as a router, so 218 * silently drop. 219 */ 220 #ifdef IPSTEALTH 221 dropit: 222 #endif 223 IPSTAT_INC(ips_cantforward); 224 m_freem(m); 225 return (1); 226 } 227 } 228 229 /* 230 * locate outgoing interface 231 */ 232 (void)memcpy(&ipaddr.sin_addr, cp + off, 233 sizeof(ipaddr.sin_addr)); 234 235 type = ICMP_UNREACH; 236 code = ICMP_UNREACH_SRCFAIL; 237 238 if (opt == IPOPT_SSRR) { 239 #define INA struct in_ifaddr * 240 #define SA struct sockaddr * 241 ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr, 242 RT_ALL_FIBS); 243 if (ia == NULL) 244 ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0, 245 RT_ALL_FIBS); 246 if (ia == NULL) 247 goto bad; 248 249 memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 250 sizeof(struct in_addr)); 251 ifa_free(&ia->ia_ifa); 252 } else { 253 /* XXX MRT 0 for routing */ 254 if (fib4_lookup_nh_ext(M_GETFIB(m), 255 ipaddr.sin_addr, 0, 0, &nh_ext) != 0) 256 goto bad; 257 258 memcpy(cp + off, &nh_ext.nh_src, 259 sizeof(struct in_addr)); 260 } 261 262 ip->ip_dst = ipaddr.sin_addr; 263 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 264 /* 265 * Let ip_intr's mcast routing check handle mcast pkts 266 */ 267 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 268 break; 269 270 case IPOPT_RR: 271 #ifdef IPSTEALTH 272 if (V_ipstealth && pass == 0) 273 break; 274 #endif 275 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 276 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 277 goto bad; 278 } 279 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 280 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 281 goto bad; 282 } 283 /* 284 * If no space remains, ignore. 285 */ 286 off--; /* 0 origin */ 287 if (off > optlen - (int)sizeof(struct in_addr)) 288 break; 289 (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst, 290 sizeof(ipaddr.sin_addr)); 291 /* 292 * Locate outgoing interface; if we're the 293 * destination, use the incoming interface (should be 294 * same). 295 */ 296 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) != NULL) { 297 memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 298 sizeof(struct in_addr)); 299 ifa_free(&ia->ia_ifa); 300 } else if (fib4_lookup_nh_ext(M_GETFIB(m), 301 ipaddr.sin_addr, 0, 0, &nh_ext) == 0) { 302 memcpy(cp + off, &nh_ext.nh_src, 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) { 337 338 case IPOPT_TS_TSONLY: 339 break; 340 341 case IPOPT_TS_TSANDADDR: 342 if (off + sizeof(uint32_t) + 343 sizeof(struct in_addr) > optlen) { 344 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 345 goto bad; 346 } 347 ipaddr.sin_addr = dst; 348 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 349 m->m_pkthdr.rcvif); 350 if (ia == NULL) 351 continue; 352 (void)memcpy(sin, &IA_SIN(ia)->sin_addr, 353 sizeof(struct in_addr)); 354 ifa_free(&ia->ia_ifa); 355 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 356 off += sizeof(struct in_addr); 357 break; 358 359 case IPOPT_TS_PRESPEC: 360 if (off + sizeof(uint32_t) + 361 sizeof(struct in_addr) > optlen) { 362 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 363 goto bad; 364 } 365 (void)memcpy(&ipaddr.sin_addr, sin, 366 sizeof(struct in_addr)); 367 if (ifa_ifwithaddr_check((SA)&ipaddr) == 0) 368 continue; 369 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 370 off += sizeof(struct in_addr); 371 break; 372 373 default: 374 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip; 375 goto bad; 376 } 377 ntime = iptime(); 378 (void)memcpy(cp + off, &ntime, sizeof(uint32_t)); 379 cp[IPOPT_OFFSET] += sizeof(uint32_t); 380 } 381 } 382 if (forward && V_ipforwarding) { 383 ip_forward(m, 1); 384 return (1); 385 } 386 return (0); 387 bad: 388 icmp_error(m, type, code, 0, 0); 389 IPSTAT_INC(ips_badoptions); 390 return (1); 391 } 392 393 /* 394 * Save incoming source route for use in replies, to be picked up later by 395 * ip_srcroute if the receiver is interested. 396 */ 397 static void 398 save_rte(struct mbuf *m, u_char *option, struct in_addr dst) 399 { 400 unsigned olen; 401 struct ipopt_tag *opts; 402 403 opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS, 404 sizeof(struct ipopt_tag), M_NOWAIT); 405 if (opts == NULL) 406 return; 407 408 olen = option[IPOPT_OLEN]; 409 if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) { 410 m_tag_free((struct m_tag *)opts); 411 return; 412 } 413 bcopy(option, opts->ip_srcrt.srcopt, olen); 414 opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 415 opts->ip_srcrt.dst = dst; 416 m_tag_prepend(m, (struct m_tag *)opts); 417 } 418 419 /* 420 * Retrieve incoming source route for use in replies, in the same form used 421 * by setsockopt. The first hop is placed before the options, will be 422 * removed later. 423 */ 424 struct mbuf * 425 ip_srcroute(struct mbuf *m0) 426 { 427 struct in_addr *p, *q; 428 struct mbuf *m; 429 struct ipopt_tag *opts; 430 431 opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL); 432 if (opts == NULL) 433 return (NULL); 434 435 if (opts->ip_nhops == 0) 436 return (NULL); 437 m = m_get(M_NOWAIT, MT_DATA); 438 if (m == NULL) 439 return (NULL); 440 441 #define OPTSIZ (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt)) 442 443 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 444 m->m_len = opts->ip_nhops * sizeof(struct in_addr) + 445 sizeof(struct in_addr) + OPTSIZ; 446 447 /* 448 * First, save first hop for return route. 449 */ 450 p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]); 451 *(mtod(m, struct in_addr *)) = *p--; 452 453 /* 454 * Copy option fields and padding (nop) to mbuf. 455 */ 456 opts->ip_srcrt.nop = IPOPT_NOP; 457 opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 458 (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), 459 &(opts->ip_srcrt.nop), OPTSIZ); 460 q = (struct in_addr *)(mtod(m, caddr_t) + 461 sizeof(struct in_addr) + OPTSIZ); 462 #undef OPTSIZ 463 /* 464 * Record return path as an IP source route, reversing the path 465 * (pointers are now aligned). 466 */ 467 while (p >= opts->ip_srcrt.route) { 468 *q++ = *p--; 469 } 470 /* 471 * Last hop goes to final destination. 472 */ 473 *q = opts->ip_srcrt.dst; 474 m_tag_delete(m0, (struct m_tag *)opts); 475 return (m); 476 } 477 478 /* 479 * Strip out IP options, at higher level protocol in the kernel. 480 */ 481 void 482 ip_stripoptions(struct mbuf *m) 483 { 484 struct ip *ip = mtod(m, struct ip *); 485 int olen; 486 487 olen = (ip->ip_hl << 2) - sizeof(struct ip); 488 m->m_len -= olen; 489 if (m->m_flags & M_PKTHDR) 490 m->m_pkthdr.len -= olen; 491 ip->ip_len = htons(ntohs(ip->ip_len) - olen); 492 ip->ip_hl = sizeof(struct ip) >> 2; 493 494 bcopy((char *)ip + sizeof(struct ip) + olen, (ip + 1), 495 (size_t )(m->m_len - sizeof(struct ip))); 496 } 497 498 /* 499 * Insert IP options into preformed packet. Adjust IP destination as 500 * required for IP source routing, as indicated by a non-zero in_addr at the 501 * start of the options. 502 * 503 * XXX This routine assumes that the packet has no options in place. 504 */ 505 struct mbuf * 506 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen) 507 { 508 struct ipoption *p = mtod(opt, struct ipoption *); 509 struct mbuf *n; 510 struct ip *ip = mtod(m, struct ip *); 511 unsigned optlen; 512 513 optlen = opt->m_len - sizeof(p->ipopt_dst); 514 if (optlen + ntohs(ip->ip_len) > IP_MAXPACKET) { 515 *phlen = 0; 516 return (m); /* XXX should fail */ 517 } 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) { 652 653 default: 654 break; 655 656 case IPOPT_LSRR: 657 case IPOPT_SSRR: 658 /* 659 * User process specifies route as: 660 * 661 * ->A->B->C->D 662 * 663 * D must be our final destination (but we can't 664 * check that since we may not have connected yet). 665 * A is first hop destination, which doesn't appear 666 * in actual IP option, but is stored before the 667 * options. 668 */ 669 /* XXX-BZ PRIV_NETINET_SETHDROPTS? */ 670 if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr)) 671 goto bad; 672 m->m_len -= sizeof(struct in_addr); 673 cnt -= sizeof(struct in_addr); 674 optlen -= sizeof(struct in_addr); 675 cp[IPOPT_OLEN] = optlen; 676 /* 677 * Move first hop before start of options. 678 */ 679 bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t), 680 sizeof(struct in_addr)); 681 /* 682 * Then copy rest of options back 683 * to close up the deleted entry. 684 */ 685 bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)), 686 &cp[IPOPT_OFFSET+1], 687 (unsigned)cnt - (IPOPT_MINOFF - 1)); 688 break; 689 } 690 } 691 if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr)) 692 goto bad; 693 *pcbopt = m; 694 return (0); 695 696 bad: 697 (void)m_free(m); 698 return (EINVAL); 699 } 700 701 /* 702 * Check for the presence of the IP Router Alert option [RFC2113] 703 * in the header of an IPv4 datagram. 704 * 705 * This call is not intended for use from the forwarding path; it is here 706 * so that protocol domains may check for the presence of the option. 707 * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert 708 * option does not have much relevance to the implementation, though this 709 * may change in future. 710 * Router alert options SHOULD be passed if running in IPSTEALTH mode and 711 * we are not the endpoint. 712 * Length checks on individual options should already have been performed 713 * by ip_dooptions() therefore they are folded under INVARIANTS here. 714 * 715 * Return zero if not present or options are invalid, non-zero if present. 716 */ 717 int 718 ip_checkrouteralert(struct mbuf *m) 719 { 720 struct ip *ip = mtod(m, struct ip *); 721 u_char *cp; 722 int opt, optlen, cnt, found_ra; 723 724 found_ra = 0; 725 cp = (u_char *)(ip + 1); 726 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 727 for (; cnt > 0; cnt -= optlen, cp += optlen) { 728 opt = cp[IPOPT_OPTVAL]; 729 if (opt == IPOPT_EOL) 730 break; 731 if (opt == IPOPT_NOP) 732 optlen = 1; 733 else { 734 #ifdef INVARIANTS 735 if (cnt < IPOPT_OLEN + sizeof(*cp)) 736 break; 737 #endif 738 optlen = cp[IPOPT_OLEN]; 739 #ifdef INVARIANTS 740 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) 741 break; 742 #endif 743 } 744 switch (opt) { 745 case IPOPT_RA: 746 #ifdef INVARIANTS 747 if (optlen != IPOPT_OFFSET + sizeof(uint16_t) || 748 (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0)) 749 break; 750 else 751 #endif 752 found_ra = 1; 753 break; 754 default: 755 break; 756 } 757 } 758 759 return (found_ra); 760 } 761