1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 30 * $FreeBSD$ 31 */ 32 33 #include "opt_ipsec.h" 34 #include "opt_mac.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/mac.h> 39 #include <sys/mbuf.h> 40 #include <sys/protosw.h> 41 #include <sys/socket.h> 42 #include <sys/time.h> 43 #include <sys/kernel.h> 44 #include <sys/sysctl.h> 45 46 #include <net/if.h> 47 #include <net/if_types.h> 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_pcb.h> 52 #include <netinet/in_systm.h> 53 #include <netinet/in_var.h> 54 #include <netinet/ip.h> 55 #include <netinet/ip_icmp.h> 56 #include <netinet/ip_var.h> 57 #include <netinet/tcp.h> 58 #include <netinet/tcp_var.h> 59 #include <netinet/tcpip.h> 60 #include <netinet/icmp_var.h> 61 62 #ifdef IPSEC 63 #include <netinet6/ipsec.h> 64 #include <netkey/key.h> 65 #endif 66 67 #ifdef FAST_IPSEC 68 #include <netipsec/ipsec.h> 69 #include <netipsec/key.h> 70 #define IPSEC 71 #endif 72 73 #include <machine/in_cksum.h> 74 75 /* 76 * ICMP routines: error generation, receive packet processing, and 77 * routines to turnaround packets back to the originator, and 78 * host table maintenance routines. 79 */ 80 81 struct icmpstat icmpstat; 82 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 83 &icmpstat, icmpstat, ""); 84 85 static int icmpmaskrepl = 0; 86 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 87 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 88 89 static u_int icmpmaskfake = 0; 90 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 91 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 92 93 static int drop_redirect = 0; 94 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 95 &drop_redirect, 0, ""); 96 97 static int log_redirect = 0; 98 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 99 &log_redirect, 0, ""); 100 101 static int icmplim = 200; 102 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 103 &icmplim, 0, ""); 104 105 static int icmplim_output = 1; 106 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 107 &icmplim_output, 0, ""); 108 109 static char reply_src[IFNAMSIZ]; 110 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 111 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 112 113 /* 114 * ICMP broadcast echo sysctl 115 */ 116 117 static int icmpbmcastecho = 0; 118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 119 &icmpbmcastecho, 0, ""); 120 121 122 #ifdef ICMPPRINTFS 123 int icmpprintfs = 0; 124 #endif 125 126 static void icmp_reflect(struct mbuf *); 127 static void icmp_send(struct mbuf *, struct mbuf *); 128 129 extern struct protosw inetsw[]; 130 131 /* 132 * Generate an error packet of type error 133 * in response to bad packet ip. 134 */ 135 void 136 icmp_error(n, type, code, dest, mtu) 137 struct mbuf *n; 138 int type, code; 139 n_long dest; 140 int mtu; 141 { 142 register struct ip *oip = mtod(n, struct ip *), *nip; 143 register unsigned oiplen = oip->ip_hl << 2; 144 register struct icmp *icp; 145 register struct mbuf *m; 146 unsigned icmplen; 147 148 #ifdef ICMPPRINTFS 149 if (icmpprintfs) 150 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 151 #endif 152 if (type != ICMP_REDIRECT) 153 icmpstat.icps_error++; 154 /* 155 * Don't send error if the original packet was encrypted. 156 * Don't send error if not the first fragment of message. 157 * Don't error if the old packet protocol was ICMP 158 * error message, only known informational types. 159 */ 160 if (n->m_flags & M_DECRYPTED) 161 goto freeit; 162 if (oip->ip_off &~ (IP_MF|IP_DF)) 163 goto freeit; 164 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 165 n->m_len >= oiplen + ICMP_MINLEN && 166 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 167 icmpstat.icps_oldicmp++; 168 goto freeit; 169 } 170 /* Don't send error in response to a multicast or broadcast packet */ 171 if (n->m_flags & (M_BCAST|M_MCAST)) 172 goto freeit; 173 /* 174 * First, formulate icmp message 175 */ 176 m = m_gethdr(M_DONTWAIT, MT_HEADER); 177 if (m == NULL) 178 goto freeit; 179 #ifdef MAC 180 mac_create_mbuf_netlayer(n, m); 181 #endif 182 icmplen = min(oiplen + 8, oip->ip_len); 183 if (icmplen < sizeof(struct ip)) 184 panic("icmp_error: bad length"); 185 m->m_len = icmplen + ICMP_MINLEN; 186 MH_ALIGN(m, m->m_len); 187 icp = mtod(m, struct icmp *); 188 if ((u_int)type > ICMP_MAXTYPE) 189 panic("icmp_error"); 190 icmpstat.icps_outhist[type]++; 191 icp->icmp_type = type; 192 if (type == ICMP_REDIRECT) 193 icp->icmp_gwaddr.s_addr = dest; 194 else { 195 icp->icmp_void = 0; 196 /* 197 * The following assignments assume an overlay with the 198 * zeroed icmp_void field. 199 */ 200 if (type == ICMP_PARAMPROB) { 201 icp->icmp_pptr = code; 202 code = 0; 203 } else if (type == ICMP_UNREACH && 204 code == ICMP_UNREACH_NEEDFRAG && mtu) { 205 icp->icmp_nextmtu = htons(mtu); 206 } 207 } 208 209 icp->icmp_code = code; 210 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 211 nip = &icp->icmp_ip; 212 213 /* 214 * Convert fields to network representation. 215 */ 216 nip->ip_len = htons(nip->ip_len); 217 nip->ip_off = htons(nip->ip_off); 218 219 /* 220 * Now, copy old ip header (without options) 221 * in front of icmp message. 222 */ 223 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 224 panic("icmp len"); 225 /* 226 * If the original mbuf was meant to bypass the firewall, the error 227 * reply should bypass as well. 228 */ 229 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 230 m->m_data -= sizeof(struct ip); 231 m->m_len += sizeof(struct ip); 232 m->m_pkthdr.len = m->m_len; 233 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 234 nip = mtod(m, struct ip *); 235 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 236 nip->ip_len = m->m_len; 237 nip->ip_v = IPVERSION; 238 nip->ip_hl = 5; 239 nip->ip_p = IPPROTO_ICMP; 240 nip->ip_tos = 0; 241 icmp_reflect(m); 242 243 freeit: 244 m_freem(n); 245 } 246 247 /* 248 * Process a received ICMP message. 249 */ 250 void 251 icmp_input(m, off) 252 struct mbuf *m; 253 int off; 254 { 255 struct icmp *icp; 256 struct in_ifaddr *ia; 257 struct ip *ip = mtod(m, struct ip *); 258 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 259 int hlen = off; 260 int icmplen = ip->ip_len; 261 int i, code; 262 void (*ctlfunc)(int, struct sockaddr *, void *); 263 264 /* 265 * Locate icmp structure in mbuf, and check 266 * that not corrupted and of at least minimum length. 267 */ 268 #ifdef ICMPPRINTFS 269 if (icmpprintfs) { 270 char buf[4 * sizeof "123"]; 271 strcpy(buf, inet_ntoa(ip->ip_src)); 272 printf("icmp_input from %s to %s, len %d\n", 273 buf, inet_ntoa(ip->ip_dst), icmplen); 274 } 275 #endif 276 if (icmplen < ICMP_MINLEN) { 277 icmpstat.icps_tooshort++; 278 goto freeit; 279 } 280 i = hlen + min(icmplen, ICMP_ADVLENMIN); 281 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 282 icmpstat.icps_tooshort++; 283 return; 284 } 285 ip = mtod(m, struct ip *); 286 m->m_len -= hlen; 287 m->m_data += hlen; 288 icp = mtod(m, struct icmp *); 289 if (in_cksum(m, icmplen)) { 290 icmpstat.icps_checksum++; 291 goto freeit; 292 } 293 m->m_len += hlen; 294 m->m_data -= hlen; 295 296 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 297 /* 298 * Deliver very specific ICMP type only. 299 */ 300 switch (icp->icmp_type) { 301 case ICMP_UNREACH: 302 case ICMP_TIMXCEED: 303 break; 304 default: 305 goto freeit; 306 } 307 } 308 309 #ifdef ICMPPRINTFS 310 if (icmpprintfs) 311 printf("icmp_input, type %d code %d\n", icp->icmp_type, 312 icp->icmp_code); 313 #endif 314 315 /* 316 * Message type specific processing. 317 */ 318 if (icp->icmp_type > ICMP_MAXTYPE) 319 goto raw; 320 321 /* Initialize */ 322 bzero(&icmpsrc, sizeof(icmpsrc)); 323 icmpsrc.sin_len = sizeof(struct sockaddr_in); 324 icmpsrc.sin_family = AF_INET; 325 bzero(&icmpdst, sizeof(icmpdst)); 326 icmpdst.sin_len = sizeof(struct sockaddr_in); 327 icmpdst.sin_family = AF_INET; 328 bzero(&icmpgw, sizeof(icmpgw)); 329 icmpgw.sin_len = sizeof(struct sockaddr_in); 330 icmpgw.sin_family = AF_INET; 331 332 icmpstat.icps_inhist[icp->icmp_type]++; 333 code = icp->icmp_code; 334 switch (icp->icmp_type) { 335 336 case ICMP_UNREACH: 337 switch (code) { 338 case ICMP_UNREACH_NET: 339 case ICMP_UNREACH_HOST: 340 case ICMP_UNREACH_SRCFAIL: 341 case ICMP_UNREACH_NET_UNKNOWN: 342 case ICMP_UNREACH_HOST_UNKNOWN: 343 case ICMP_UNREACH_ISOLATED: 344 case ICMP_UNREACH_TOSNET: 345 case ICMP_UNREACH_TOSHOST: 346 case ICMP_UNREACH_HOST_PRECEDENCE: 347 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 348 code = PRC_UNREACH_NET; 349 break; 350 351 case ICMP_UNREACH_NEEDFRAG: 352 code = PRC_MSGSIZE; 353 break; 354 355 /* 356 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 357 * Treat subcodes 2,3 as immediate RST 358 */ 359 case ICMP_UNREACH_PROTOCOL: 360 case ICMP_UNREACH_PORT: 361 code = PRC_UNREACH_PORT; 362 break; 363 364 case ICMP_UNREACH_NET_PROHIB: 365 case ICMP_UNREACH_HOST_PROHIB: 366 case ICMP_UNREACH_FILTER_PROHIB: 367 code = PRC_UNREACH_ADMIN_PROHIB; 368 break; 369 370 default: 371 goto badcode; 372 } 373 goto deliver; 374 375 case ICMP_TIMXCEED: 376 if (code > 1) 377 goto badcode; 378 code += PRC_TIMXCEED_INTRANS; 379 goto deliver; 380 381 case ICMP_PARAMPROB: 382 if (code > 1) 383 goto badcode; 384 code = PRC_PARAMPROB; 385 goto deliver; 386 387 case ICMP_SOURCEQUENCH: 388 if (code) 389 goto badcode; 390 code = PRC_QUENCH; 391 deliver: 392 /* 393 * Problem with datagram; advise higher level routines. 394 */ 395 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 396 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 397 icmpstat.icps_badlen++; 398 goto freeit; 399 } 400 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 401 /* Discard ICMP's in response to multicast packets */ 402 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 403 goto badcode; 404 #ifdef ICMPPRINTFS 405 if (icmpprintfs) 406 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 407 #endif 408 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 409 /* 410 * XXX if the packet contains [IPv4 AH TCP], we can't make a 411 * notification to TCP layer. 412 */ 413 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 414 if (ctlfunc) 415 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 416 (void *)&icp->icmp_ip); 417 break; 418 419 badcode: 420 icmpstat.icps_badcode++; 421 break; 422 423 case ICMP_ECHO: 424 if (!icmpbmcastecho 425 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 426 icmpstat.icps_bmcastecho++; 427 break; 428 } 429 icp->icmp_type = ICMP_ECHOREPLY; 430 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 431 goto freeit; 432 else 433 goto reflect; 434 435 case ICMP_TSTAMP: 436 if (!icmpbmcastecho 437 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 438 icmpstat.icps_bmcasttstamp++; 439 break; 440 } 441 if (icmplen < ICMP_TSLEN) { 442 icmpstat.icps_badlen++; 443 break; 444 } 445 icp->icmp_type = ICMP_TSTAMPREPLY; 446 icp->icmp_rtime = iptime(); 447 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 448 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 449 goto freeit; 450 else 451 goto reflect; 452 453 case ICMP_MASKREQ: 454 if (icmpmaskrepl == 0) 455 break; 456 /* 457 * We are not able to respond with all ones broadcast 458 * unless we receive it over a point-to-point interface. 459 */ 460 if (icmplen < ICMP_MASKLEN) 461 break; 462 switch (ip->ip_dst.s_addr) { 463 464 case INADDR_BROADCAST: 465 case INADDR_ANY: 466 icmpdst.sin_addr = ip->ip_src; 467 break; 468 469 default: 470 icmpdst.sin_addr = ip->ip_dst; 471 } 472 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 473 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 474 if (ia == 0) 475 break; 476 if (ia->ia_ifp == 0) 477 break; 478 icp->icmp_type = ICMP_MASKREPLY; 479 if (icmpmaskfake == 0) 480 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 481 else 482 icp->icmp_mask = icmpmaskfake; 483 if (ip->ip_src.s_addr == 0) { 484 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 485 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 486 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 487 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 488 } 489 reflect: 490 ip->ip_len += hlen; /* since ip_input deducts this */ 491 icmpstat.icps_reflect++; 492 icmpstat.icps_outhist[icp->icmp_type]++; 493 icmp_reflect(m); 494 return; 495 496 case ICMP_REDIRECT: 497 if (log_redirect) { 498 u_long src, dst, gw; 499 500 src = ntohl(ip->ip_src.s_addr); 501 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 502 gw = ntohl(icp->icmp_gwaddr.s_addr); 503 printf("icmp redirect from %d.%d.%d.%d: " 504 "%d.%d.%d.%d => %d.%d.%d.%d\n", 505 (int)(src >> 24), (int)((src >> 16) & 0xff), 506 (int)((src >> 8) & 0xff), (int)(src & 0xff), 507 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 508 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 509 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 510 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 511 } 512 /* 513 * RFC1812 says we must ignore ICMP redirects if we 514 * are acting as router. 515 */ 516 if (drop_redirect || ipforwarding) 517 break; 518 if (code > 3) 519 goto badcode; 520 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 521 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 522 icmpstat.icps_badlen++; 523 break; 524 } 525 /* 526 * Short circuit routing redirects to force 527 * immediate change in the kernel's routing 528 * tables. The message is also handed to anyone 529 * listening on a raw socket (e.g. the routing 530 * daemon for use in updating its tables). 531 */ 532 icmpgw.sin_addr = ip->ip_src; 533 icmpdst.sin_addr = icp->icmp_gwaddr; 534 #ifdef ICMPPRINTFS 535 if (icmpprintfs) { 536 char buf[4 * sizeof "123"]; 537 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 538 539 printf("redirect dst %s to %s\n", 540 buf, inet_ntoa(icp->icmp_gwaddr)); 541 } 542 #endif 543 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 544 rtredirect((struct sockaddr *)&icmpsrc, 545 (struct sockaddr *)&icmpdst, 546 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 547 (struct sockaddr *)&icmpgw); 548 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 549 #ifdef IPSEC 550 key_sa_routechange((struct sockaddr *)&icmpsrc); 551 #endif 552 break; 553 554 /* 555 * No kernel processing for the following; 556 * just fall through to send to raw listener. 557 */ 558 case ICMP_ECHOREPLY: 559 case ICMP_ROUTERADVERT: 560 case ICMP_ROUTERSOLICIT: 561 case ICMP_TSTAMPREPLY: 562 case ICMP_IREQREPLY: 563 case ICMP_MASKREPLY: 564 default: 565 break; 566 } 567 568 raw: 569 rip_input(m, off); 570 return; 571 572 freeit: 573 m_freem(m); 574 } 575 576 /* 577 * Reflect the ip packet back to the source 578 */ 579 static void 580 icmp_reflect(m) 581 struct mbuf *m; 582 { 583 struct ip *ip = mtod(m, struct ip *); 584 struct ifaddr *ifa; 585 struct ifnet *ifn; 586 struct in_ifaddr *ia; 587 struct in_addr t; 588 struct mbuf *opts = 0; 589 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 590 591 if (!in_canforward(ip->ip_src) && 592 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 593 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 594 m_freem(m); /* Bad return address */ 595 icmpstat.icps_badaddr++; 596 goto done; /* Ip_output() will check for broadcast */ 597 } 598 t = ip->ip_dst; 599 ip->ip_dst = ip->ip_src; 600 601 /* 602 * Source selection for ICMP replies: 603 * 604 * If the incoming packet was addressed directly to one of our 605 * own addresses, use dst as the src for the reply. 606 */ 607 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 608 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 609 goto match; 610 /* 611 * If the incoming packet was addressed to one of our broadcast 612 * addresses, use the first non-broadcast address which corresponds 613 * to the incoming interface. 614 */ 615 if (m->m_pkthdr.rcvif != NULL && 616 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 617 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 618 if (ifa->ifa_addr->sa_family != AF_INET) 619 continue; 620 ia = ifatoia(ifa); 621 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 622 t.s_addr) 623 goto match; 624 } 625 } 626 /* 627 * If the incoming packet was not addressed directly to us, use 628 * designated interface for icmp replies specified by sysctl 629 * net.inet.icmp.reply_src (default not set). Otherwise continue 630 * with normal source selection. 631 */ 632 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 633 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 634 if (ifa->ifa_addr->sa_family != AF_INET) 635 continue; 636 ia = ifatoia(ifa); 637 goto match; 638 } 639 } 640 /* 641 * If the packet was transiting through us, use the address of 642 * the interface that is the closest to the packet source. 643 * When we don't have a route back to the packet source, stop here 644 * and drop the packet. 645 */ 646 ia = ip_rtaddr(ip->ip_dst); 647 if (ia == NULL) { 648 m_freem(m); 649 icmpstat.icps_noroute++; 650 goto done; 651 } 652 match: 653 #ifdef MAC 654 mac_reflect_mbuf_icmp(m); 655 #endif 656 t = IA_SIN(ia)->sin_addr; 657 ip->ip_src = t; 658 ip->ip_ttl = ip_defttl; 659 660 if (optlen > 0) { 661 register u_char *cp; 662 int opt, cnt; 663 u_int len; 664 665 /* 666 * Retrieve any source routing from the incoming packet; 667 * add on any record-route or timestamp options. 668 */ 669 cp = (u_char *) (ip + 1); 670 if ((opts = ip_srcroute(m)) == 0 && 671 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 672 opts->m_len = sizeof(struct in_addr); 673 mtod(opts, struct in_addr *)->s_addr = 0; 674 } 675 if (opts) { 676 #ifdef ICMPPRINTFS 677 if (icmpprintfs) 678 printf("icmp_reflect optlen %d rt %d => ", 679 optlen, opts->m_len); 680 #endif 681 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 682 opt = cp[IPOPT_OPTVAL]; 683 if (opt == IPOPT_EOL) 684 break; 685 if (opt == IPOPT_NOP) 686 len = 1; 687 else { 688 if (cnt < IPOPT_OLEN + sizeof(*cp)) 689 break; 690 len = cp[IPOPT_OLEN]; 691 if (len < IPOPT_OLEN + sizeof(*cp) || 692 len > cnt) 693 break; 694 } 695 /* 696 * Should check for overflow, but it "can't happen" 697 */ 698 if (opt == IPOPT_RR || opt == IPOPT_TS || 699 opt == IPOPT_SECURITY) { 700 bcopy((caddr_t)cp, 701 mtod(opts, caddr_t) + opts->m_len, len); 702 opts->m_len += len; 703 } 704 } 705 /* Terminate & pad, if necessary */ 706 cnt = opts->m_len % 4; 707 if (cnt) { 708 for (; cnt < 4; cnt++) { 709 *(mtod(opts, caddr_t) + opts->m_len) = 710 IPOPT_EOL; 711 opts->m_len++; 712 } 713 } 714 #ifdef ICMPPRINTFS 715 if (icmpprintfs) 716 printf("%d\n", opts->m_len); 717 #endif 718 } 719 /* 720 * Now strip out original options by copying rest of first 721 * mbuf's data back, and adjust the IP length. 722 */ 723 ip->ip_len -= optlen; 724 ip->ip_v = IPVERSION; 725 ip->ip_hl = 5; 726 m->m_len -= optlen; 727 if (m->m_flags & M_PKTHDR) 728 m->m_pkthdr.len -= optlen; 729 optlen += sizeof(struct ip); 730 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 731 (unsigned)(m->m_len - sizeof(struct ip))); 732 } 733 m_tag_delete_nonpersistent(m); 734 m->m_flags &= ~(M_BCAST|M_MCAST); 735 icmp_send(m, opts); 736 done: 737 if (opts) 738 (void)m_free(opts); 739 } 740 741 /* 742 * Send an icmp packet back to the ip level, 743 * after supplying a checksum. 744 */ 745 static void 746 icmp_send(m, opts) 747 register struct mbuf *m; 748 struct mbuf *opts; 749 { 750 register struct ip *ip = mtod(m, struct ip *); 751 register int hlen; 752 register struct icmp *icp; 753 754 hlen = ip->ip_hl << 2; 755 m->m_data += hlen; 756 m->m_len -= hlen; 757 icp = mtod(m, struct icmp *); 758 icp->icmp_cksum = 0; 759 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 760 m->m_data -= hlen; 761 m->m_len += hlen; 762 m->m_pkthdr.rcvif = (struct ifnet *)0; 763 #ifdef ICMPPRINTFS 764 if (icmpprintfs) { 765 char buf[4 * sizeof "123"]; 766 strcpy(buf, inet_ntoa(ip->ip_dst)); 767 printf("icmp_send dst %s src %s\n", 768 buf, inet_ntoa(ip->ip_src)); 769 } 770 #endif 771 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 772 } 773 774 n_time 775 iptime() 776 { 777 struct timeval atv; 778 u_long t; 779 780 getmicrotime(&atv); 781 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 782 return (htonl(t)); 783 } 784 785 /* 786 * Return the next larger or smaller MTU plateau (table from RFC 1191) 787 * given current value MTU. If DIR is less than zero, a larger plateau 788 * is returned; otherwise, a smaller value is returned. 789 */ 790 int 791 ip_next_mtu(mtu, dir) 792 int mtu; 793 int dir; 794 { 795 static int mtutab[] = { 796 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 797 296, 68, 0 798 }; 799 int i; 800 801 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 802 if (mtu >= mtutab[i]) 803 break; 804 } 805 806 if (dir < 0) { 807 if (i == 0) { 808 return 0; 809 } else { 810 return mtutab[i - 1]; 811 } 812 } else { 813 if (mtutab[i] == 0) { 814 return 0; 815 } else if(mtu > mtutab[i]) { 816 return mtutab[i]; 817 } else { 818 return mtutab[i + 1]; 819 } 820 } 821 } 822 823 824 /* 825 * badport_bandlim() - check for ICMP bandwidth limit 826 * 827 * Return 0 if it is ok to send an ICMP error response, -1 if we have 828 * hit our bandwidth limit and it is not ok. 829 * 830 * If icmplim is <= 0, the feature is disabled and 0 is returned. 831 * 832 * For now we separate the TCP and UDP subsystems w/ different 'which' 833 * values. We may eventually remove this separation (and simplify the 834 * code further). 835 * 836 * Note that the printing of the error message is delayed so we can 837 * properly print the icmp error rate that the system was trying to do 838 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 839 * the 'final' error, but it doesn't make sense to solve the printing 840 * delay with more complex code. 841 */ 842 843 int 844 badport_bandlim(int which) 845 { 846 #define N(a) (sizeof (a) / sizeof (a[0])) 847 static struct rate { 848 const char *type; 849 struct timeval lasttime; 850 int curpps; 851 } rates[BANDLIM_MAX+1] = { 852 { "icmp unreach response" }, 853 { "icmp ping response" }, 854 { "icmp tstamp response" }, 855 { "closed port RST response" }, 856 { "open port RST response" } 857 }; 858 859 /* 860 * Return ok status if feature disabled or argument out of range. 861 */ 862 if (icmplim > 0 && (u_int) which < N(rates)) { 863 struct rate *r = &rates[which]; 864 int opps = r->curpps; 865 866 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 867 return -1; /* discard packet */ 868 /* 869 * If we've dropped below the threshold after having 870 * rate-limited traffic print the message. This preserves 871 * the previous behaviour at the expense of added complexity. 872 */ 873 if (icmplim_output && opps > icmplim) 874 printf("Limiting %s from %d to %d packets/sec\n", 875 r->type, opps, icmplim); 876 } 877 return 0; /* okay to send packet */ 878 #undef N 879 } 880