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 static int icmp_rfi = 0; 114 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 115 &icmp_rfi, 0, "ICMP reply from incoming interface for " 116 "non-local packets"); 117 118 static int icmp_quotelen = 8; 119 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 120 &icmp_quotelen, 0, "Number of bytes from original packet to " 121 "quote in ICMP reply"); 122 123 /* 124 * ICMP broadcast echo sysctl 125 */ 126 127 static int icmpbmcastecho = 0; 128 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 129 &icmpbmcastecho, 0, ""); 130 131 132 #ifdef ICMPPRINTFS 133 int icmpprintfs = 0; 134 #endif 135 136 static void icmp_reflect(struct mbuf *); 137 static void icmp_send(struct mbuf *, struct mbuf *); 138 139 extern struct protosw inetsw[]; 140 141 /* 142 * Generate an error packet of type error 143 * in response to bad packet ip. 144 */ 145 void 146 icmp_error(n, type, code, dest, mtu) 147 struct mbuf *n; 148 int type, code; 149 n_long dest; 150 int mtu; 151 { 152 register struct ip *oip = mtod(n, struct ip *), *nip; 153 register unsigned oiplen = oip->ip_hl << 2; 154 register struct icmp *icp; 155 register struct mbuf *m; 156 unsigned icmplen; 157 158 #ifdef ICMPPRINTFS 159 if (icmpprintfs) 160 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 161 #endif 162 if (type != ICMP_REDIRECT) 163 icmpstat.icps_error++; 164 /* 165 * Don't send error if the original packet was encrypted. 166 * Don't send error if not the first fragment of message. 167 * Don't error if the old packet protocol was ICMP 168 * error message, only known informational types. 169 */ 170 if (n->m_flags & M_DECRYPTED) 171 goto freeit; 172 if (oip->ip_off &~ (IP_MF|IP_DF)) 173 goto freeit; 174 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 175 n->m_len >= oiplen + ICMP_MINLEN && 176 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 177 icmpstat.icps_oldicmp++; 178 goto freeit; 179 } 180 /* Don't send error in response to a multicast or broadcast packet */ 181 if (n->m_flags & (M_BCAST|M_MCAST)) 182 goto freeit; 183 /* 184 * First, formulate icmp message 185 */ 186 MGETHDR(m, M_DONTWAIT, MT_HEADER); 187 if (m == NULL) 188 goto freeit; 189 #ifdef MAC 190 mac_create_mbuf_netlayer(n, m); 191 #endif 192 /* 193 * Calculate length to quote from original packet and 194 * prevent the ICMP mbuf from overflowing. 195 */ 196 if (oip->ip_p == IPPROTO_TCP) { 197 struct tcphdr *th; 198 int tcphlen; 199 200 if (n->m_len < oiplen + sizeof(struct tcphdr) && 201 ((n = m_pullup(n, oiplen + sizeof(struct tcphdr))) == NULL)) 202 goto freeit; 203 th = (struct tcphdr *)((caddr_t)oip + oiplen); 204 tcphlen = th->th_off << 2; 205 if (tcphlen < sizeof(struct tcphdr)) 206 goto freeit; 207 if (oip->ip_len < oiplen + tcphlen) 208 goto freeit; 209 if (n->m_len < oiplen + tcphlen && 210 ((n = m_pullup(n, oiplen + tcphlen)) == NULL)) 211 goto freeit; 212 icmplen = max(oiplen + tcphlen, min(icmp_quotelen, oip->ip_len)); 213 } else 214 icmplen = min(oiplen + max(8, icmp_quotelen), oip->ip_len); 215 if (icmplen < sizeof(struct ip)) 216 goto freeit; 217 if (icmplen + ICMP_MINLEN + sizeof(struct ip) > MHLEN) { 218 MCLGET(m, M_DONTWAIT); 219 if (!(m->m_flags & M_EXT)) 220 goto freeit; 221 } 222 m->m_len = icmplen + ICMP_MINLEN; 223 MH_ALIGN(m, m->m_len); 224 icp = mtod(m, struct icmp *); 225 if ((u_int)type > ICMP_MAXTYPE) 226 panic("icmp_error"); 227 icmpstat.icps_outhist[type]++; 228 icp->icmp_type = type; 229 if (type == ICMP_REDIRECT) 230 icp->icmp_gwaddr.s_addr = dest; 231 else { 232 icp->icmp_void = 0; 233 /* 234 * The following assignments assume an overlay with the 235 * zeroed icmp_void field. 236 */ 237 if (type == ICMP_PARAMPROB) { 238 icp->icmp_pptr = code; 239 code = 0; 240 } else if (type == ICMP_UNREACH && 241 code == ICMP_UNREACH_NEEDFRAG && mtu) { 242 icp->icmp_nextmtu = htons(mtu); 243 } 244 } 245 246 icp->icmp_code = code; 247 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 248 nip = &icp->icmp_ip; 249 250 /* 251 * Convert fields to network representation. 252 */ 253 nip->ip_len = htons(nip->ip_len); 254 nip->ip_off = htons(nip->ip_off); 255 256 /* 257 * Now, copy old ip header (without options) 258 * in front of icmp message. 259 */ 260 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 261 panic("icmp len"); 262 /* 263 * If the original mbuf was meant to bypass the firewall, the error 264 * reply should bypass as well. 265 */ 266 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 267 m->m_data -= sizeof(struct ip); 268 m->m_len += sizeof(struct ip); 269 m->m_pkthdr.len = m->m_len; 270 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 271 nip = mtod(m, struct ip *); 272 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 273 nip->ip_len = m->m_len; 274 nip->ip_v = IPVERSION; 275 nip->ip_hl = 5; 276 nip->ip_p = IPPROTO_ICMP; 277 nip->ip_tos = 0; 278 icmp_reflect(m); 279 280 freeit: 281 m_freem(n); 282 } 283 284 /* 285 * Process a received ICMP message. 286 */ 287 void 288 icmp_input(m, off) 289 struct mbuf *m; 290 int off; 291 { 292 struct icmp *icp; 293 struct in_ifaddr *ia; 294 struct ip *ip = mtod(m, struct ip *); 295 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 296 int hlen = off; 297 int icmplen = ip->ip_len; 298 int i, code; 299 void (*ctlfunc)(int, struct sockaddr *, void *); 300 301 /* 302 * Locate icmp structure in mbuf, and check 303 * that not corrupted and of at least minimum length. 304 */ 305 #ifdef ICMPPRINTFS 306 if (icmpprintfs) { 307 char buf[4 * sizeof "123"]; 308 strcpy(buf, inet_ntoa(ip->ip_src)); 309 printf("icmp_input from %s to %s, len %d\n", 310 buf, inet_ntoa(ip->ip_dst), icmplen); 311 } 312 #endif 313 if (icmplen < ICMP_MINLEN) { 314 icmpstat.icps_tooshort++; 315 goto freeit; 316 } 317 i = hlen + min(icmplen, ICMP_ADVLENMIN); 318 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 319 icmpstat.icps_tooshort++; 320 return; 321 } 322 ip = mtod(m, struct ip *); 323 m->m_len -= hlen; 324 m->m_data += hlen; 325 icp = mtod(m, struct icmp *); 326 if (in_cksum(m, icmplen)) { 327 icmpstat.icps_checksum++; 328 goto freeit; 329 } 330 m->m_len += hlen; 331 m->m_data -= hlen; 332 333 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 334 /* 335 * Deliver very specific ICMP type only. 336 */ 337 switch (icp->icmp_type) { 338 case ICMP_UNREACH: 339 case ICMP_TIMXCEED: 340 break; 341 default: 342 goto freeit; 343 } 344 } 345 346 #ifdef ICMPPRINTFS 347 if (icmpprintfs) 348 printf("icmp_input, type %d code %d\n", icp->icmp_type, 349 icp->icmp_code); 350 #endif 351 352 /* 353 * Message type specific processing. 354 */ 355 if (icp->icmp_type > ICMP_MAXTYPE) 356 goto raw; 357 358 /* Initialize */ 359 bzero(&icmpsrc, sizeof(icmpsrc)); 360 icmpsrc.sin_len = sizeof(struct sockaddr_in); 361 icmpsrc.sin_family = AF_INET; 362 bzero(&icmpdst, sizeof(icmpdst)); 363 icmpdst.sin_len = sizeof(struct sockaddr_in); 364 icmpdst.sin_family = AF_INET; 365 bzero(&icmpgw, sizeof(icmpgw)); 366 icmpgw.sin_len = sizeof(struct sockaddr_in); 367 icmpgw.sin_family = AF_INET; 368 369 icmpstat.icps_inhist[icp->icmp_type]++; 370 code = icp->icmp_code; 371 switch (icp->icmp_type) { 372 373 case ICMP_UNREACH: 374 switch (code) { 375 case ICMP_UNREACH_NET: 376 case ICMP_UNREACH_HOST: 377 case ICMP_UNREACH_SRCFAIL: 378 case ICMP_UNREACH_NET_UNKNOWN: 379 case ICMP_UNREACH_HOST_UNKNOWN: 380 case ICMP_UNREACH_ISOLATED: 381 case ICMP_UNREACH_TOSNET: 382 case ICMP_UNREACH_TOSHOST: 383 case ICMP_UNREACH_HOST_PRECEDENCE: 384 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 385 code = PRC_UNREACH_NET; 386 break; 387 388 case ICMP_UNREACH_NEEDFRAG: 389 code = PRC_MSGSIZE; 390 break; 391 392 /* 393 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 394 * Treat subcodes 2,3 as immediate RST 395 */ 396 case ICMP_UNREACH_PROTOCOL: 397 case ICMP_UNREACH_PORT: 398 code = PRC_UNREACH_PORT; 399 break; 400 401 case ICMP_UNREACH_NET_PROHIB: 402 case ICMP_UNREACH_HOST_PROHIB: 403 case ICMP_UNREACH_FILTER_PROHIB: 404 code = PRC_UNREACH_ADMIN_PROHIB; 405 break; 406 407 default: 408 goto badcode; 409 } 410 goto deliver; 411 412 case ICMP_TIMXCEED: 413 if (code > 1) 414 goto badcode; 415 code += PRC_TIMXCEED_INTRANS; 416 goto deliver; 417 418 case ICMP_PARAMPROB: 419 if (code > 1) 420 goto badcode; 421 code = PRC_PARAMPROB; 422 goto deliver; 423 424 case ICMP_SOURCEQUENCH: 425 if (code) 426 goto badcode; 427 code = PRC_QUENCH; 428 deliver: 429 /* 430 * Problem with datagram; advise higher level routines. 431 */ 432 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 433 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 434 icmpstat.icps_badlen++; 435 goto freeit; 436 } 437 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 438 /* Discard ICMP's in response to multicast packets */ 439 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 440 goto badcode; 441 #ifdef ICMPPRINTFS 442 if (icmpprintfs) 443 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 444 #endif 445 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 446 /* 447 * XXX if the packet contains [IPv4 AH TCP], we can't make a 448 * notification to TCP layer. 449 */ 450 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 451 if (ctlfunc) 452 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 453 (void *)&icp->icmp_ip); 454 break; 455 456 badcode: 457 icmpstat.icps_badcode++; 458 break; 459 460 case ICMP_ECHO: 461 if (!icmpbmcastecho 462 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 463 icmpstat.icps_bmcastecho++; 464 break; 465 } 466 icp->icmp_type = ICMP_ECHOREPLY; 467 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 468 goto freeit; 469 else 470 goto reflect; 471 472 case ICMP_TSTAMP: 473 if (!icmpbmcastecho 474 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 475 icmpstat.icps_bmcasttstamp++; 476 break; 477 } 478 if (icmplen < ICMP_TSLEN) { 479 icmpstat.icps_badlen++; 480 break; 481 } 482 icp->icmp_type = ICMP_TSTAMPREPLY; 483 icp->icmp_rtime = iptime(); 484 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 485 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 486 goto freeit; 487 else 488 goto reflect; 489 490 case ICMP_MASKREQ: 491 if (icmpmaskrepl == 0) 492 break; 493 /* 494 * We are not able to respond with all ones broadcast 495 * unless we receive it over a point-to-point interface. 496 */ 497 if (icmplen < ICMP_MASKLEN) 498 break; 499 switch (ip->ip_dst.s_addr) { 500 501 case INADDR_BROADCAST: 502 case INADDR_ANY: 503 icmpdst.sin_addr = ip->ip_src; 504 break; 505 506 default: 507 icmpdst.sin_addr = ip->ip_dst; 508 } 509 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 510 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 511 if (ia == 0) 512 break; 513 if (ia->ia_ifp == 0) 514 break; 515 icp->icmp_type = ICMP_MASKREPLY; 516 if (icmpmaskfake == 0) 517 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 518 else 519 icp->icmp_mask = icmpmaskfake; 520 if (ip->ip_src.s_addr == 0) { 521 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 522 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 523 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 524 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 525 } 526 reflect: 527 ip->ip_len += hlen; /* since ip_input deducts this */ 528 icmpstat.icps_reflect++; 529 icmpstat.icps_outhist[icp->icmp_type]++; 530 icmp_reflect(m); 531 return; 532 533 case ICMP_REDIRECT: 534 if (log_redirect) { 535 u_long src, dst, gw; 536 537 src = ntohl(ip->ip_src.s_addr); 538 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 539 gw = ntohl(icp->icmp_gwaddr.s_addr); 540 printf("icmp redirect from %d.%d.%d.%d: " 541 "%d.%d.%d.%d => %d.%d.%d.%d\n", 542 (int)(src >> 24), (int)((src >> 16) & 0xff), 543 (int)((src >> 8) & 0xff), (int)(src & 0xff), 544 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 545 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 546 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 547 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 548 } 549 /* 550 * RFC1812 says we must ignore ICMP redirects if we 551 * are acting as router. 552 */ 553 if (drop_redirect || ipforwarding) 554 break; 555 if (code > 3) 556 goto badcode; 557 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 558 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 559 icmpstat.icps_badlen++; 560 break; 561 } 562 /* 563 * Short circuit routing redirects to force 564 * immediate change in the kernel's routing 565 * tables. The message is also handed to anyone 566 * listening on a raw socket (e.g. the routing 567 * daemon for use in updating its tables). 568 */ 569 icmpgw.sin_addr = ip->ip_src; 570 icmpdst.sin_addr = icp->icmp_gwaddr; 571 #ifdef ICMPPRINTFS 572 if (icmpprintfs) { 573 char buf[4 * sizeof "123"]; 574 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 575 576 printf("redirect dst %s to %s\n", 577 buf, inet_ntoa(icp->icmp_gwaddr)); 578 } 579 #endif 580 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 581 rtredirect((struct sockaddr *)&icmpsrc, 582 (struct sockaddr *)&icmpdst, 583 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 584 (struct sockaddr *)&icmpgw); 585 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 586 #ifdef IPSEC 587 key_sa_routechange((struct sockaddr *)&icmpsrc); 588 #endif 589 break; 590 591 /* 592 * No kernel processing for the following; 593 * just fall through to send to raw listener. 594 */ 595 case ICMP_ECHOREPLY: 596 case ICMP_ROUTERADVERT: 597 case ICMP_ROUTERSOLICIT: 598 case ICMP_TSTAMPREPLY: 599 case ICMP_IREQREPLY: 600 case ICMP_MASKREPLY: 601 default: 602 break; 603 } 604 605 raw: 606 rip_input(m, off); 607 return; 608 609 freeit: 610 m_freem(m); 611 } 612 613 /* 614 * Reflect the ip packet back to the source 615 */ 616 static void 617 icmp_reflect(m) 618 struct mbuf *m; 619 { 620 struct ip *ip = mtod(m, struct ip *); 621 struct ifaddr *ifa; 622 struct ifnet *ifn; 623 struct in_ifaddr *ia; 624 struct in_addr t; 625 struct mbuf *opts = 0; 626 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 627 628 if (!in_canforward(ip->ip_src) && 629 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 630 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 631 m_freem(m); /* Bad return address */ 632 icmpstat.icps_badaddr++; 633 goto done; /* Ip_output() will check for broadcast */ 634 } 635 t = ip->ip_dst; 636 ip->ip_dst = ip->ip_src; 637 638 /* 639 * Source selection for ICMP replies: 640 * 641 * If the incoming packet was addressed directly to one of our 642 * own addresses, use dst as the src for the reply. 643 */ 644 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 645 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 646 goto match; 647 /* 648 * If the incoming packet was addressed to one of our broadcast 649 * addresses, use the first non-broadcast address which corresponds 650 * to the incoming interface. 651 */ 652 if (m->m_pkthdr.rcvif != NULL && 653 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 654 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 655 if (ifa->ifa_addr->sa_family != AF_INET) 656 continue; 657 ia = ifatoia(ifa); 658 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 659 t.s_addr) 660 goto match; 661 } 662 } 663 /* 664 * If the packet was transiting through us, use the address of 665 * the interface the packet came through in. If that interface 666 * doesn't have a suitable IP address, the normal selection 667 * criteria apply. 668 */ 669 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 670 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 671 if (ifa->ifa_addr->sa_family != AF_INET) 672 continue; 673 ia = ifatoia(ifa); 674 goto match; 675 } 676 } 677 /* 678 * If the incoming packet was not addressed directly to us, use 679 * designated interface for icmp replies specified by sysctl 680 * net.inet.icmp.reply_src (default not set). Otherwise continue 681 * with normal source selection. 682 */ 683 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 684 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 685 if (ifa->ifa_addr->sa_family != AF_INET) 686 continue; 687 ia = ifatoia(ifa); 688 goto match; 689 } 690 } 691 /* 692 * If the packet was transiting through us, use the address of 693 * the interface that is the closest to the packet source. 694 * When we don't have a route back to the packet source, stop here 695 * and drop the packet. 696 */ 697 ia = ip_rtaddr(ip->ip_dst); 698 if (ia == NULL) { 699 m_freem(m); 700 icmpstat.icps_noroute++; 701 goto done; 702 } 703 match: 704 #ifdef MAC 705 mac_reflect_mbuf_icmp(m); 706 #endif 707 t = IA_SIN(ia)->sin_addr; 708 ip->ip_src = t; 709 ip->ip_ttl = ip_defttl; 710 711 if (optlen > 0) { 712 register u_char *cp; 713 int opt, cnt; 714 u_int len; 715 716 /* 717 * Retrieve any source routing from the incoming packet; 718 * add on any record-route or timestamp options. 719 */ 720 cp = (u_char *) (ip + 1); 721 if ((opts = ip_srcroute(m)) == 0 && 722 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 723 opts->m_len = sizeof(struct in_addr); 724 mtod(opts, struct in_addr *)->s_addr = 0; 725 } 726 if (opts) { 727 #ifdef ICMPPRINTFS 728 if (icmpprintfs) 729 printf("icmp_reflect optlen %d rt %d => ", 730 optlen, opts->m_len); 731 #endif 732 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 733 opt = cp[IPOPT_OPTVAL]; 734 if (opt == IPOPT_EOL) 735 break; 736 if (opt == IPOPT_NOP) 737 len = 1; 738 else { 739 if (cnt < IPOPT_OLEN + sizeof(*cp)) 740 break; 741 len = cp[IPOPT_OLEN]; 742 if (len < IPOPT_OLEN + sizeof(*cp) || 743 len > cnt) 744 break; 745 } 746 /* 747 * Should check for overflow, but it "can't happen" 748 */ 749 if (opt == IPOPT_RR || opt == IPOPT_TS || 750 opt == IPOPT_SECURITY) { 751 bcopy((caddr_t)cp, 752 mtod(opts, caddr_t) + opts->m_len, len); 753 opts->m_len += len; 754 } 755 } 756 /* Terminate & pad, if necessary */ 757 cnt = opts->m_len % 4; 758 if (cnt) { 759 for (; cnt < 4; cnt++) { 760 *(mtod(opts, caddr_t) + opts->m_len) = 761 IPOPT_EOL; 762 opts->m_len++; 763 } 764 } 765 #ifdef ICMPPRINTFS 766 if (icmpprintfs) 767 printf("%d\n", opts->m_len); 768 #endif 769 } 770 /* 771 * Now strip out original options by copying rest of first 772 * mbuf's data back, and adjust the IP length. 773 */ 774 ip->ip_len -= optlen; 775 ip->ip_v = IPVERSION; 776 ip->ip_hl = 5; 777 m->m_len -= optlen; 778 if (m->m_flags & M_PKTHDR) 779 m->m_pkthdr.len -= optlen; 780 optlen += sizeof(struct ip); 781 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 782 (unsigned)(m->m_len - sizeof(struct ip))); 783 } 784 m_tag_delete_nonpersistent(m); 785 m->m_flags &= ~(M_BCAST|M_MCAST); 786 icmp_send(m, opts); 787 done: 788 if (opts) 789 (void)m_free(opts); 790 } 791 792 /* 793 * Send an icmp packet back to the ip level, 794 * after supplying a checksum. 795 */ 796 static void 797 icmp_send(m, opts) 798 register struct mbuf *m; 799 struct mbuf *opts; 800 { 801 register struct ip *ip = mtod(m, struct ip *); 802 register int hlen; 803 register struct icmp *icp; 804 805 hlen = ip->ip_hl << 2; 806 m->m_data += hlen; 807 m->m_len -= hlen; 808 icp = mtod(m, struct icmp *); 809 icp->icmp_cksum = 0; 810 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 811 m->m_data -= hlen; 812 m->m_len += hlen; 813 m->m_pkthdr.rcvif = (struct ifnet *)0; 814 #ifdef ICMPPRINTFS 815 if (icmpprintfs) { 816 char buf[4 * sizeof "123"]; 817 strcpy(buf, inet_ntoa(ip->ip_dst)); 818 printf("icmp_send dst %s src %s\n", 819 buf, inet_ntoa(ip->ip_src)); 820 } 821 #endif 822 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 823 } 824 825 n_time 826 iptime() 827 { 828 struct timeval atv; 829 u_long t; 830 831 getmicrotime(&atv); 832 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 833 return (htonl(t)); 834 } 835 836 /* 837 * Return the next larger or smaller MTU plateau (table from RFC 1191) 838 * given current value MTU. If DIR is less than zero, a larger plateau 839 * is returned; otherwise, a smaller value is returned. 840 */ 841 int 842 ip_next_mtu(mtu, dir) 843 int mtu; 844 int dir; 845 { 846 static int mtutab[] = { 847 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 848 296, 68, 0 849 }; 850 int i; 851 852 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 853 if (mtu >= mtutab[i]) 854 break; 855 } 856 857 if (dir < 0) { 858 if (i == 0) { 859 return 0; 860 } else { 861 return mtutab[i - 1]; 862 } 863 } else { 864 if (mtutab[i] == 0) { 865 return 0; 866 } else if(mtu > mtutab[i]) { 867 return mtutab[i]; 868 } else { 869 return mtutab[i + 1]; 870 } 871 } 872 } 873 874 875 /* 876 * badport_bandlim() - check for ICMP bandwidth limit 877 * 878 * Return 0 if it is ok to send an ICMP error response, -1 if we have 879 * hit our bandwidth limit and it is not ok. 880 * 881 * If icmplim is <= 0, the feature is disabled and 0 is returned. 882 * 883 * For now we separate the TCP and UDP subsystems w/ different 'which' 884 * values. We may eventually remove this separation (and simplify the 885 * code further). 886 * 887 * Note that the printing of the error message is delayed so we can 888 * properly print the icmp error rate that the system was trying to do 889 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 890 * the 'final' error, but it doesn't make sense to solve the printing 891 * delay with more complex code. 892 */ 893 894 int 895 badport_bandlim(int which) 896 { 897 #define N(a) (sizeof (a) / sizeof (a[0])) 898 static struct rate { 899 const char *type; 900 struct timeval lasttime; 901 int curpps; 902 } rates[BANDLIM_MAX+1] = { 903 { "icmp unreach response" }, 904 { "icmp ping response" }, 905 { "icmp tstamp response" }, 906 { "closed port RST response" }, 907 { "open port RST response" } 908 }; 909 910 /* 911 * Return ok status if feature disabled or argument out of range. 912 */ 913 if (icmplim > 0 && (u_int) which < N(rates)) { 914 struct rate *r = &rates[which]; 915 int opps = r->curpps; 916 917 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 918 return -1; /* discard packet */ 919 /* 920 * If we've dropped below the threshold after having 921 * rate-limited traffic print the message. This preserves 922 * the previous behaviour at the expense of added complexity. 923 */ 924 if (icmplim_output && opps > icmplim) 925 printf("Limiting %s from %d to %d packets/sec\n", 926 r->type, opps, icmplim); 927 } 928 return 0; /* okay to send packet */ 929 #undef N 930 } 931