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/mbuf.h> 39 #include <sys/protosw.h> 40 #include <sys/socket.h> 41 #include <sys/time.h> 42 #include <sys/kernel.h> 43 #include <sys/sysctl.h> 44 45 #include <net/if.h> 46 #include <net/if_types.h> 47 #include <net/route.h> 48 49 #include <netinet/in.h> 50 #include <netinet/in_pcb.h> 51 #include <netinet/in_systm.h> 52 #include <netinet/in_var.h> 53 #include <netinet/ip.h> 54 #include <netinet/ip_icmp.h> 55 #include <netinet/ip_var.h> 56 #include <netinet/ip_options.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 #include <security/mac/mac_framework.h> 76 77 /* 78 * ICMP routines: error generation, receive packet processing, and 79 * routines to turnaround packets back to the originator, and 80 * host table maintenance routines. 81 */ 82 83 struct icmpstat icmpstat; 84 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 85 &icmpstat, icmpstat, ""); 86 87 static int icmpmaskrepl = 0; 88 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 89 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 90 91 static u_int icmpmaskfake = 0; 92 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 93 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 94 95 static int drop_redirect = 0; 96 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 97 &drop_redirect, 0, "Ignore ICMP redirects"); 98 99 static int log_redirect = 0; 100 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 101 &log_redirect, 0, "Log ICMP redirects to the console"); 102 103 static int icmplim = 200; 104 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 105 &icmplim, 0, "Maximum number of ICMP responses per second"); 106 107 static int icmplim_output = 1; 108 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 109 &icmplim_output, 0, "Enable rate limiting of ICMP responses"); 110 111 static char reply_src[IFNAMSIZ]; 112 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 113 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 114 115 static int icmp_rfi = 0; 116 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 117 &icmp_rfi, 0, "ICMP reply from incoming interface for " 118 "non-local packets"); 119 120 static int icmp_quotelen = 8; 121 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 122 &icmp_quotelen, 0, "Number of bytes from original packet to " 123 "quote in ICMP reply"); 124 125 /* 126 * ICMP broadcast echo sysctl 127 */ 128 129 static int icmpbmcastecho = 0; 130 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 131 &icmpbmcastecho, 0, ""); 132 133 134 #ifdef ICMPPRINTFS 135 int icmpprintfs = 0; 136 #endif 137 138 static void icmp_reflect(struct mbuf *); 139 static void icmp_send(struct mbuf *, struct mbuf *); 140 141 extern struct protosw inetsw[]; 142 143 /* 144 * Generate an error packet of type error 145 * in response to bad packet ip. 146 */ 147 void 148 icmp_error(n, type, code, dest, mtu) 149 struct mbuf *n; 150 int type, code; 151 n_long dest; 152 int mtu; 153 { 154 register struct ip *oip = mtod(n, struct ip *), *nip; 155 register unsigned oiphlen = oip->ip_hl << 2; 156 register struct icmp *icp; 157 register struct mbuf *m; 158 unsigned icmplen, icmpelen, nlen; 159 160 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 161 #ifdef ICMPPRINTFS 162 if (icmpprintfs) 163 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 164 #endif 165 if (type != ICMP_REDIRECT) 166 icmpstat.icps_error++; 167 /* 168 * Don't send error: 169 * if the original packet was encrypted. 170 * if not the first fragment of message. 171 * in response to a multicast or broadcast packet. 172 * if the old packet protocol was an ICMP error message. 173 */ 174 if (n->m_flags & M_DECRYPTED) 175 goto freeit; 176 if (oip->ip_off & ~(IP_MF|IP_DF)) 177 goto freeit; 178 if (n->m_flags & (M_BCAST|M_MCAST)) 179 goto freeit; 180 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 181 n->m_len >= oiphlen + ICMP_MINLEN && 182 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 183 icmpstat.icps_oldicmp++; 184 goto freeit; 185 } 186 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 187 if (oiphlen + 8 > n->m_len) 188 goto freeit; 189 /* 190 * Calculate length to quote from original packet and 191 * prevent the ICMP mbuf from overflowing. 192 * Unfortunatly this is non-trivial since ip_forward() 193 * sends us truncated packets. 194 */ 195 nlen = m_length(n, NULL); 196 if (oip->ip_p == IPPROTO_TCP) { 197 struct tcphdr *th; 198 int tcphlen; 199 200 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 201 n->m_next == NULL) 202 goto stdreply; 203 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 204 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 205 goto freeit; 206 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 207 tcphlen = th->th_off << 2; 208 if (tcphlen < sizeof(struct tcphdr)) 209 goto freeit; 210 if (oip->ip_len < oiphlen + tcphlen) 211 goto freeit; 212 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 213 goto stdreply; 214 if (n->m_len < oiphlen + tcphlen && 215 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 216 goto freeit; 217 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen)); 218 } else 219 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen)); 220 221 icmplen = min(oiphlen + icmpelen, nlen); 222 if (icmplen < sizeof(struct ip)) 223 goto freeit; 224 225 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 226 m = m_gethdr(M_DONTWAIT, MT_DATA); 227 else 228 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 229 if (m == NULL) 230 goto freeit; 231 #ifdef MAC 232 mac_create_mbuf_netlayer(n, m); 233 #endif 234 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 235 m_align(m, ICMP_MINLEN + icmplen); 236 m->m_len = ICMP_MINLEN + icmplen; 237 238 icp = mtod(m, struct icmp *); 239 icmpstat.icps_outhist[type]++; 240 icp->icmp_type = type; 241 if (type == ICMP_REDIRECT) 242 icp->icmp_gwaddr.s_addr = dest; 243 else { 244 icp->icmp_void = 0; 245 /* 246 * The following assignments assume an overlay with the 247 * just zeroed icmp_void field. 248 */ 249 if (type == ICMP_PARAMPROB) { 250 icp->icmp_pptr = code; 251 code = 0; 252 } else if (type == ICMP_UNREACH && 253 code == ICMP_UNREACH_NEEDFRAG && mtu) { 254 icp->icmp_nextmtu = htons(mtu); 255 } 256 } 257 icp->icmp_code = code; 258 259 /* 260 * Copy the quotation into ICMP message and 261 * convert quoted IP header back to network representation. 262 */ 263 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 264 nip = &icp->icmp_ip; 265 nip->ip_len = htons(nip->ip_len); 266 nip->ip_off = htons(nip->ip_off); 267 268 /* 269 * Set up ICMP message mbuf and copy old IP header (without options 270 * in front of ICMP message. 271 * If the original mbuf was meant to bypass the firewall, the error 272 * reply should bypass as well. 273 */ 274 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 275 m->m_data -= sizeof(struct ip); 276 m->m_len += sizeof(struct ip); 277 m->m_pkthdr.len = m->m_len; 278 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 279 nip = mtod(m, struct ip *); 280 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 281 nip->ip_len = m->m_len; 282 nip->ip_v = IPVERSION; 283 nip->ip_hl = 5; 284 nip->ip_p = IPPROTO_ICMP; 285 nip->ip_tos = 0; 286 icmp_reflect(m); 287 288 freeit: 289 m_freem(n); 290 } 291 292 /* 293 * Process a received ICMP message. 294 */ 295 void 296 icmp_input(m, off) 297 struct mbuf *m; 298 int off; 299 { 300 struct icmp *icp; 301 struct in_ifaddr *ia; 302 struct ip *ip = mtod(m, struct ip *); 303 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 304 int hlen = off; 305 int icmplen = ip->ip_len; 306 int i, code; 307 void (*ctlfunc)(int, struct sockaddr *, void *); 308 309 /* 310 * Locate icmp structure in mbuf, and check 311 * that not corrupted and of at least minimum length. 312 */ 313 #ifdef ICMPPRINTFS 314 if (icmpprintfs) { 315 char buf[4 * sizeof "123"]; 316 strcpy(buf, inet_ntoa(ip->ip_src)); 317 printf("icmp_input from %s to %s, len %d\n", 318 buf, inet_ntoa(ip->ip_dst), icmplen); 319 } 320 #endif 321 if (icmplen < ICMP_MINLEN) { 322 icmpstat.icps_tooshort++; 323 goto freeit; 324 } 325 i = hlen + min(icmplen, ICMP_ADVLENMIN); 326 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 327 icmpstat.icps_tooshort++; 328 return; 329 } 330 ip = mtod(m, struct ip *); 331 m->m_len -= hlen; 332 m->m_data += hlen; 333 icp = mtod(m, struct icmp *); 334 if (in_cksum(m, icmplen)) { 335 icmpstat.icps_checksum++; 336 goto freeit; 337 } 338 m->m_len += hlen; 339 m->m_data -= hlen; 340 341 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 342 /* 343 * Deliver very specific ICMP type only. 344 */ 345 switch (icp->icmp_type) { 346 case ICMP_UNREACH: 347 case ICMP_TIMXCEED: 348 break; 349 default: 350 goto freeit; 351 } 352 } 353 354 #ifdef ICMPPRINTFS 355 if (icmpprintfs) 356 printf("icmp_input, type %d code %d\n", icp->icmp_type, 357 icp->icmp_code); 358 #endif 359 360 /* 361 * Message type specific processing. 362 */ 363 if (icp->icmp_type > ICMP_MAXTYPE) 364 goto raw; 365 366 /* Initialize */ 367 bzero(&icmpsrc, sizeof(icmpsrc)); 368 icmpsrc.sin_len = sizeof(struct sockaddr_in); 369 icmpsrc.sin_family = AF_INET; 370 bzero(&icmpdst, sizeof(icmpdst)); 371 icmpdst.sin_len = sizeof(struct sockaddr_in); 372 icmpdst.sin_family = AF_INET; 373 bzero(&icmpgw, sizeof(icmpgw)); 374 icmpgw.sin_len = sizeof(struct sockaddr_in); 375 icmpgw.sin_family = AF_INET; 376 377 icmpstat.icps_inhist[icp->icmp_type]++; 378 code = icp->icmp_code; 379 switch (icp->icmp_type) { 380 381 case ICMP_UNREACH: 382 switch (code) { 383 case ICMP_UNREACH_NET: 384 case ICMP_UNREACH_HOST: 385 case ICMP_UNREACH_SRCFAIL: 386 case ICMP_UNREACH_NET_UNKNOWN: 387 case ICMP_UNREACH_HOST_UNKNOWN: 388 case ICMP_UNREACH_ISOLATED: 389 case ICMP_UNREACH_TOSNET: 390 case ICMP_UNREACH_TOSHOST: 391 case ICMP_UNREACH_HOST_PRECEDENCE: 392 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 393 code = PRC_UNREACH_NET; 394 break; 395 396 case ICMP_UNREACH_NEEDFRAG: 397 code = PRC_MSGSIZE; 398 break; 399 400 /* 401 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 402 * Treat subcodes 2,3 as immediate RST 403 */ 404 case ICMP_UNREACH_PROTOCOL: 405 case ICMP_UNREACH_PORT: 406 code = PRC_UNREACH_PORT; 407 break; 408 409 case ICMP_UNREACH_NET_PROHIB: 410 case ICMP_UNREACH_HOST_PROHIB: 411 case ICMP_UNREACH_FILTER_PROHIB: 412 code = PRC_UNREACH_ADMIN_PROHIB; 413 break; 414 415 default: 416 goto badcode; 417 } 418 goto deliver; 419 420 case ICMP_TIMXCEED: 421 if (code > 1) 422 goto badcode; 423 code += PRC_TIMXCEED_INTRANS; 424 goto deliver; 425 426 case ICMP_PARAMPROB: 427 if (code > 1) 428 goto badcode; 429 code = PRC_PARAMPROB; 430 goto deliver; 431 432 case ICMP_SOURCEQUENCH: 433 if (code) 434 goto badcode; 435 code = PRC_QUENCH; 436 deliver: 437 /* 438 * Problem with datagram; advise higher level routines. 439 */ 440 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 441 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 442 icmpstat.icps_badlen++; 443 goto freeit; 444 } 445 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 446 /* Discard ICMP's in response to multicast packets */ 447 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 448 goto badcode; 449 #ifdef ICMPPRINTFS 450 if (icmpprintfs) 451 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 452 #endif 453 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 454 /* 455 * XXX if the packet contains [IPv4 AH TCP], we can't make a 456 * notification to TCP layer. 457 */ 458 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 459 if (ctlfunc) 460 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 461 (void *)&icp->icmp_ip); 462 break; 463 464 badcode: 465 icmpstat.icps_badcode++; 466 break; 467 468 case ICMP_ECHO: 469 if (!icmpbmcastecho 470 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 471 icmpstat.icps_bmcastecho++; 472 break; 473 } 474 icp->icmp_type = ICMP_ECHOREPLY; 475 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 476 goto freeit; 477 else 478 goto reflect; 479 480 case ICMP_TSTAMP: 481 if (!icmpbmcastecho 482 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 483 icmpstat.icps_bmcasttstamp++; 484 break; 485 } 486 if (icmplen < ICMP_TSLEN) { 487 icmpstat.icps_badlen++; 488 break; 489 } 490 icp->icmp_type = ICMP_TSTAMPREPLY; 491 icp->icmp_rtime = iptime(); 492 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 493 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 494 goto freeit; 495 else 496 goto reflect; 497 498 case ICMP_MASKREQ: 499 if (icmpmaskrepl == 0) 500 break; 501 /* 502 * We are not able to respond with all ones broadcast 503 * unless we receive it over a point-to-point interface. 504 */ 505 if (icmplen < ICMP_MASKLEN) 506 break; 507 switch (ip->ip_dst.s_addr) { 508 509 case INADDR_BROADCAST: 510 case INADDR_ANY: 511 icmpdst.sin_addr = ip->ip_src; 512 break; 513 514 default: 515 icmpdst.sin_addr = ip->ip_dst; 516 } 517 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 518 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 519 if (ia == 0) 520 break; 521 if (ia->ia_ifp == 0) 522 break; 523 icp->icmp_type = ICMP_MASKREPLY; 524 if (icmpmaskfake == 0) 525 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 526 else 527 icp->icmp_mask = icmpmaskfake; 528 if (ip->ip_src.s_addr == 0) { 529 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 530 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 531 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 532 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 533 } 534 reflect: 535 ip->ip_len += hlen; /* since ip_input deducts this */ 536 icmpstat.icps_reflect++; 537 icmpstat.icps_outhist[icp->icmp_type]++; 538 icmp_reflect(m); 539 return; 540 541 case ICMP_REDIRECT: 542 if (log_redirect) { 543 u_long src, dst, gw; 544 545 src = ntohl(ip->ip_src.s_addr); 546 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 547 gw = ntohl(icp->icmp_gwaddr.s_addr); 548 printf("icmp redirect from %d.%d.%d.%d: " 549 "%d.%d.%d.%d => %d.%d.%d.%d\n", 550 (int)(src >> 24), (int)((src >> 16) & 0xff), 551 (int)((src >> 8) & 0xff), (int)(src & 0xff), 552 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 553 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 554 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 555 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 556 } 557 /* 558 * RFC1812 says we must ignore ICMP redirects if we 559 * are acting as router. 560 */ 561 if (drop_redirect || ipforwarding) 562 break; 563 if (code > 3) 564 goto badcode; 565 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 566 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 567 icmpstat.icps_badlen++; 568 break; 569 } 570 /* 571 * Short circuit routing redirects to force 572 * immediate change in the kernel's routing 573 * tables. The message is also handed to anyone 574 * listening on a raw socket (e.g. the routing 575 * daemon for use in updating its tables). 576 */ 577 icmpgw.sin_addr = ip->ip_src; 578 icmpdst.sin_addr = icp->icmp_gwaddr; 579 #ifdef ICMPPRINTFS 580 if (icmpprintfs) { 581 char buf[4 * sizeof "123"]; 582 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 583 584 printf("redirect dst %s to %s\n", 585 buf, inet_ntoa(icp->icmp_gwaddr)); 586 } 587 #endif 588 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 589 rtredirect((struct sockaddr *)&icmpsrc, 590 (struct sockaddr *)&icmpdst, 591 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 592 (struct sockaddr *)&icmpgw); 593 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 594 #ifdef IPSEC 595 key_sa_routechange((struct sockaddr *)&icmpsrc); 596 #endif 597 break; 598 599 /* 600 * No kernel processing for the following; 601 * just fall through to send to raw listener. 602 */ 603 case ICMP_ECHOREPLY: 604 case ICMP_ROUTERADVERT: 605 case ICMP_ROUTERSOLICIT: 606 case ICMP_TSTAMPREPLY: 607 case ICMP_IREQREPLY: 608 case ICMP_MASKREPLY: 609 default: 610 break; 611 } 612 613 raw: 614 rip_input(m, off); 615 return; 616 617 freeit: 618 m_freem(m); 619 } 620 621 /* 622 * Reflect the ip packet back to the source 623 */ 624 static void 625 icmp_reflect(m) 626 struct mbuf *m; 627 { 628 struct ip *ip = mtod(m, struct ip *); 629 struct ifaddr *ifa; 630 struct ifnet *ifn; 631 struct in_ifaddr *ia; 632 struct in_addr t; 633 struct mbuf *opts = 0; 634 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 635 636 if (!in_canforward(ip->ip_src) && 637 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 638 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 639 m_freem(m); /* Bad return address */ 640 icmpstat.icps_badaddr++; 641 goto done; /* Ip_output() will check for broadcast */ 642 } 643 t = ip->ip_dst; 644 ip->ip_dst = ip->ip_src; 645 646 /* 647 * Source selection for ICMP replies: 648 * 649 * If the incoming packet was addressed directly to one of our 650 * own addresses, use dst as the src for the reply. 651 */ 652 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 653 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 654 goto match; 655 /* 656 * If the incoming packet was addressed to one of our broadcast 657 * addresses, use the first non-broadcast address which corresponds 658 * to the incoming interface. 659 */ 660 if (m->m_pkthdr.rcvif != NULL && 661 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 662 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 663 if (ifa->ifa_addr->sa_family != AF_INET) 664 continue; 665 ia = ifatoia(ifa); 666 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 667 t.s_addr) 668 goto match; 669 } 670 } 671 /* 672 * If the packet was transiting through us, use the address of 673 * the interface the packet came through in. If that interface 674 * doesn't have a suitable IP address, the normal selection 675 * criteria apply. 676 */ 677 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 678 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 679 if (ifa->ifa_addr->sa_family != AF_INET) 680 continue; 681 ia = ifatoia(ifa); 682 goto match; 683 } 684 } 685 /* 686 * If the incoming packet was not addressed directly to us, use 687 * designated interface for icmp replies specified by sysctl 688 * net.inet.icmp.reply_src (default not set). Otherwise continue 689 * with normal source selection. 690 */ 691 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 692 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 693 if (ifa->ifa_addr->sa_family != AF_INET) 694 continue; 695 ia = ifatoia(ifa); 696 goto match; 697 } 698 } 699 /* 700 * If the packet was transiting through us, use the address of 701 * the interface that is the closest to the packet source. 702 * When we don't have a route back to the packet source, stop here 703 * and drop the packet. 704 */ 705 ia = ip_rtaddr(ip->ip_dst); 706 if (ia == NULL) { 707 m_freem(m); 708 icmpstat.icps_noroute++; 709 goto done; 710 } 711 match: 712 #ifdef MAC 713 mac_reflect_mbuf_icmp(m); 714 #endif 715 t = IA_SIN(ia)->sin_addr; 716 ip->ip_src = t; 717 ip->ip_ttl = ip_defttl; 718 719 if (optlen > 0) { 720 register u_char *cp; 721 int opt, cnt; 722 u_int len; 723 724 /* 725 * Retrieve any source routing from the incoming packet; 726 * add on any record-route or timestamp options. 727 */ 728 cp = (u_char *) (ip + 1); 729 if ((opts = ip_srcroute(m)) == 0 && 730 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 731 opts->m_len = sizeof(struct in_addr); 732 mtod(opts, struct in_addr *)->s_addr = 0; 733 } 734 if (opts) { 735 #ifdef ICMPPRINTFS 736 if (icmpprintfs) 737 printf("icmp_reflect optlen %d rt %d => ", 738 optlen, opts->m_len); 739 #endif 740 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 741 opt = cp[IPOPT_OPTVAL]; 742 if (opt == IPOPT_EOL) 743 break; 744 if (opt == IPOPT_NOP) 745 len = 1; 746 else { 747 if (cnt < IPOPT_OLEN + sizeof(*cp)) 748 break; 749 len = cp[IPOPT_OLEN]; 750 if (len < IPOPT_OLEN + sizeof(*cp) || 751 len > cnt) 752 break; 753 } 754 /* 755 * Should check for overflow, but it "can't happen" 756 */ 757 if (opt == IPOPT_RR || opt == IPOPT_TS || 758 opt == IPOPT_SECURITY) { 759 bcopy((caddr_t)cp, 760 mtod(opts, caddr_t) + opts->m_len, len); 761 opts->m_len += len; 762 } 763 } 764 /* Terminate & pad, if necessary */ 765 cnt = opts->m_len % 4; 766 if (cnt) { 767 for (; cnt < 4; cnt++) { 768 *(mtod(opts, caddr_t) + opts->m_len) = 769 IPOPT_EOL; 770 opts->m_len++; 771 } 772 } 773 #ifdef ICMPPRINTFS 774 if (icmpprintfs) 775 printf("%d\n", opts->m_len); 776 #endif 777 } 778 /* 779 * Now strip out original options by copying rest of first 780 * mbuf's data back, and adjust the IP length. 781 */ 782 ip->ip_len -= optlen; 783 ip->ip_v = IPVERSION; 784 ip->ip_hl = 5; 785 m->m_len -= optlen; 786 if (m->m_flags & M_PKTHDR) 787 m->m_pkthdr.len -= optlen; 788 optlen += sizeof(struct ip); 789 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 790 (unsigned)(m->m_len - sizeof(struct ip))); 791 } 792 m_tag_delete_nonpersistent(m); 793 m->m_flags &= ~(M_BCAST|M_MCAST); 794 icmp_send(m, opts); 795 done: 796 if (opts) 797 (void)m_free(opts); 798 } 799 800 /* 801 * Send an icmp packet back to the ip level, 802 * after supplying a checksum. 803 */ 804 static void 805 icmp_send(m, opts) 806 register struct mbuf *m; 807 struct mbuf *opts; 808 { 809 register struct ip *ip = mtod(m, struct ip *); 810 register int hlen; 811 register struct icmp *icp; 812 813 hlen = ip->ip_hl << 2; 814 m->m_data += hlen; 815 m->m_len -= hlen; 816 icp = mtod(m, struct icmp *); 817 icp->icmp_cksum = 0; 818 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 819 m->m_data -= hlen; 820 m->m_len += hlen; 821 m->m_pkthdr.rcvif = (struct ifnet *)0; 822 #ifdef ICMPPRINTFS 823 if (icmpprintfs) { 824 char buf[4 * sizeof "123"]; 825 strcpy(buf, inet_ntoa(ip->ip_dst)); 826 printf("icmp_send dst %s src %s\n", 827 buf, inet_ntoa(ip->ip_src)); 828 } 829 #endif 830 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 831 } 832 833 n_time 834 iptime() 835 { 836 struct timeval atv; 837 u_long t; 838 839 getmicrotime(&atv); 840 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 841 return (htonl(t)); 842 } 843 844 /* 845 * Return the next larger or smaller MTU plateau (table from RFC 1191) 846 * given current value MTU. If DIR is less than zero, a larger plateau 847 * is returned; otherwise, a smaller value is returned. 848 */ 849 int 850 ip_next_mtu(mtu, dir) 851 int mtu; 852 int dir; 853 { 854 static int mtutab[] = { 855 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 856 296, 68, 0 857 }; 858 int i, size; 859 860 size = (sizeof mtutab) / (sizeof mtutab[0]); 861 if (dir >= 0) { 862 for (i = 0; i < size; i++) 863 if (mtu > mtutab[i]) 864 return mtutab[i]; 865 } else { 866 for (i = size - 1; i >= 0; i--) 867 if (mtu < mtutab[i]) 868 return mtutab[i]; 869 if (mtu == mtutab[0]) 870 return mtutab[0]; 871 } 872 return 0; 873 } 874 875 876 /* 877 * badport_bandlim() - check for ICMP bandwidth limit 878 * 879 * Return 0 if it is ok to send an ICMP error response, -1 if we have 880 * hit our bandwidth limit and it is not ok. 881 * 882 * If icmplim is <= 0, the feature is disabled and 0 is returned. 883 * 884 * For now we separate the TCP and UDP subsystems w/ different 'which' 885 * values. We may eventually remove this separation (and simplify the 886 * code further). 887 * 888 * Note that the printing of the error message is delayed so we can 889 * properly print the icmp error rate that the system was trying to do 890 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 891 * the 'final' error, but it doesn't make sense to solve the printing 892 * delay with more complex code. 893 */ 894 895 int 896 badport_bandlim(int which) 897 { 898 #define N(a) (sizeof (a) / sizeof (a[0])) 899 static struct rate { 900 const char *type; 901 struct timeval lasttime; 902 int curpps; 903 } rates[BANDLIM_MAX+1] = { 904 { "icmp unreach response" }, 905 { "icmp ping response" }, 906 { "icmp tstamp response" }, 907 { "closed port RST response" }, 908 { "open port RST response" } 909 }; 910 911 /* 912 * Return ok status if feature disabled or argument out of range. 913 */ 914 if (icmplim > 0 && (u_int) which < N(rates)) { 915 struct rate *r = &rates[which]; 916 int opps = r->curpps; 917 918 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 919 return -1; /* discard packet */ 920 /* 921 * If we've dropped below the threshold after having 922 * rate-limited traffic print the message. This preserves 923 * the previous behaviour at the expense of added complexity. 924 */ 925 if (icmplim_output && opps > icmplim) 926 printf("Limiting %s from %d to %d packets/sec\n", 927 r->type, opps, icmplim); 928 } 929 return 0; /* okay to send packet */ 930 #undef N 931 } 932