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 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_ipsec.h" 36 #include "opt_mac.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/mbuf.h> 41 #include <sys/protosw.h> 42 #include <sys/socket.h> 43 #include <sys/time.h> 44 #include <sys/kernel.h> 45 #include <sys/sysctl.h> 46 47 #include <net/if.h> 48 #include <net/if_types.h> 49 #include <net/route.h> 50 51 #include <netinet/in.h> 52 #include <netinet/in_pcb.h> 53 #include <netinet/in_systm.h> 54 #include <netinet/in_var.h> 55 #include <netinet/ip.h> 56 #include <netinet/ip_icmp.h> 57 #include <netinet/ip_var.h> 58 #include <netinet/ip_options.h> 59 #include <netinet/tcp.h> 60 #include <netinet/tcp_var.h> 61 #include <netinet/tcpip.h> 62 #include <netinet/icmp_var.h> 63 64 #ifdef IPSEC 65 #include <netipsec/ipsec.h> 66 #include <netipsec/key.h> 67 #endif 68 69 #include <machine/in_cksum.h> 70 71 #include <security/mac/mac_framework.h> 72 73 /* 74 * ICMP routines: error generation, receive packet processing, and 75 * routines to turnaround packets back to the originator, and 76 * host table maintenance routines. 77 */ 78 79 struct icmpstat icmpstat; 80 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 81 &icmpstat, icmpstat, ""); 82 83 static int icmpmaskrepl = 0; 84 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 85 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 86 87 static u_int icmpmaskfake = 0; 88 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 89 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 90 91 static int drop_redirect = 0; 92 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 93 &drop_redirect, 0, "Ignore ICMP redirects"); 94 95 static int log_redirect = 0; 96 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 97 &log_redirect, 0, "Log ICMP redirects to the console"); 98 99 static int icmplim = 200; 100 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 101 &icmplim, 0, "Maximum number of ICMP responses per second"); 102 103 static int icmplim_output = 1; 104 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 105 &icmplim_output, 0, "Enable rate limiting of ICMP responses"); 106 107 static char reply_src[IFNAMSIZ]; 108 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 109 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 110 111 static int icmp_rfi = 0; 112 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 113 &icmp_rfi, 0, "ICMP reply from incoming interface for " 114 "non-local packets"); 115 116 static int icmp_quotelen = 8; 117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 118 &icmp_quotelen, 0, "Number of bytes from original packet to " 119 "quote in ICMP reply"); 120 121 /* 122 * ICMP broadcast echo sysctl 123 */ 124 125 static int icmpbmcastecho = 0; 126 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 127 &icmpbmcastecho, 0, ""); 128 129 130 #ifdef ICMPPRINTFS 131 int icmpprintfs = 0; 132 #endif 133 134 static void icmp_reflect(struct mbuf *); 135 static void icmp_send(struct mbuf *, struct mbuf *); 136 137 extern struct protosw inetsw[]; 138 139 /* 140 * Generate an error packet of type error 141 * in response to bad packet ip. 142 */ 143 void 144 icmp_error(struct mbuf *n, int type, int code, n_long dest, int mtu) 145 { 146 register struct ip *oip = mtod(n, struct ip *), *nip; 147 register unsigned oiphlen = oip->ip_hl << 2; 148 register struct icmp *icp; 149 register struct mbuf *m; 150 unsigned icmplen, icmpelen, nlen; 151 152 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 153 #ifdef ICMPPRINTFS 154 if (icmpprintfs) 155 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 156 #endif 157 if (type != ICMP_REDIRECT) 158 icmpstat.icps_error++; 159 /* 160 * Don't send error: 161 * if the original packet was encrypted. 162 * if not the first fragment of message. 163 * in response to a multicast or broadcast packet. 164 * if the old packet protocol was an ICMP error message. 165 */ 166 if (n->m_flags & M_DECRYPTED) 167 goto freeit; 168 if (oip->ip_off & ~(IP_MF|IP_DF)) 169 goto freeit; 170 if (n->m_flags & (M_BCAST|M_MCAST)) 171 goto freeit; 172 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 173 n->m_len >= oiphlen + ICMP_MINLEN && 174 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 175 icmpstat.icps_oldicmp++; 176 goto freeit; 177 } 178 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 179 if (oiphlen + 8 > n->m_len) 180 goto freeit; 181 /* 182 * Calculate length to quote from original packet and 183 * prevent the ICMP mbuf from overflowing. 184 * Unfortunatly this is non-trivial since ip_forward() 185 * sends us truncated packets. 186 */ 187 nlen = m_length(n, NULL); 188 if (oip->ip_p == IPPROTO_TCP) { 189 struct tcphdr *th; 190 int tcphlen; 191 192 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 193 n->m_next == NULL) 194 goto stdreply; 195 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 196 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 197 goto freeit; 198 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 199 tcphlen = th->th_off << 2; 200 if (tcphlen < sizeof(struct tcphdr)) 201 goto freeit; 202 if (oip->ip_len < oiphlen + tcphlen) 203 goto freeit; 204 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 205 goto stdreply; 206 if (n->m_len < oiphlen + tcphlen && 207 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 208 goto freeit; 209 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen)); 210 } else 211 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen)); 212 213 icmplen = min(oiphlen + icmpelen, nlen); 214 if (icmplen < sizeof(struct ip)) 215 goto freeit; 216 217 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 218 m = m_gethdr(M_DONTWAIT, MT_DATA); 219 else 220 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 221 if (m == NULL) 222 goto freeit; 223 #ifdef MAC 224 mac_netinet_icmp_reply(n, m); 225 #endif 226 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 227 m_align(m, ICMP_MINLEN + icmplen); 228 m->m_len = ICMP_MINLEN + icmplen; 229 230 /* XXX MRT make the outgoing packet use the same FIB 231 * that was associated with the incoming packet 232 */ 233 M_SETFIB(m, M_GETFIB(n)); 234 icp = mtod(m, struct icmp *); 235 icmpstat.icps_outhist[type]++; 236 icp->icmp_type = type; 237 if (type == ICMP_REDIRECT) 238 icp->icmp_gwaddr.s_addr = dest; 239 else { 240 icp->icmp_void = 0; 241 /* 242 * The following assignments assume an overlay with the 243 * just zeroed icmp_void field. 244 */ 245 if (type == ICMP_PARAMPROB) { 246 icp->icmp_pptr = code; 247 code = 0; 248 } else if (type == ICMP_UNREACH && 249 code == ICMP_UNREACH_NEEDFRAG && mtu) { 250 icp->icmp_nextmtu = htons(mtu); 251 } 252 } 253 icp->icmp_code = code; 254 255 /* 256 * Copy the quotation into ICMP message and 257 * convert quoted IP header back to network representation. 258 */ 259 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 260 nip = &icp->icmp_ip; 261 nip->ip_len = htons(nip->ip_len); 262 nip->ip_off = htons(nip->ip_off); 263 264 /* 265 * Set up ICMP message mbuf and copy old IP header (without options 266 * in front of ICMP message. 267 * If the original mbuf was meant to bypass the firewall, the error 268 * reply should bypass as well. 269 */ 270 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 271 m->m_data -= sizeof(struct ip); 272 m->m_len += sizeof(struct ip); 273 m->m_pkthdr.len = m->m_len; 274 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 275 nip = mtod(m, struct ip *); 276 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 277 nip->ip_len = m->m_len; 278 nip->ip_v = IPVERSION; 279 nip->ip_hl = 5; 280 nip->ip_p = IPPROTO_ICMP; 281 nip->ip_tos = 0; 282 icmp_reflect(m); 283 284 freeit: 285 m_freem(n); 286 } 287 288 /* 289 * Process a received ICMP message. 290 */ 291 void 292 icmp_input(struct mbuf *m, int off) 293 { 294 struct icmp *icp; 295 struct in_ifaddr *ia; 296 struct ip *ip = mtod(m, struct ip *); 297 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 298 int hlen = off; 299 int icmplen = ip->ip_len; 300 int i, code; 301 void (*ctlfunc)(int, struct sockaddr *, void *); 302 int fibnum; 303 304 /* 305 * Locate icmp structure in mbuf, and check 306 * that not corrupted and of at least minimum length. 307 */ 308 #ifdef ICMPPRINTFS 309 if (icmpprintfs) { 310 char buf[4 * sizeof "123"]; 311 strcpy(buf, inet_ntoa(ip->ip_src)); 312 printf("icmp_input from %s to %s, len %d\n", 313 buf, inet_ntoa(ip->ip_dst), icmplen); 314 } 315 #endif 316 if (icmplen < ICMP_MINLEN) { 317 icmpstat.icps_tooshort++; 318 goto freeit; 319 } 320 i = hlen + min(icmplen, ICMP_ADVLENMIN); 321 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 322 icmpstat.icps_tooshort++; 323 return; 324 } 325 ip = mtod(m, struct ip *); 326 m->m_len -= hlen; 327 m->m_data += hlen; 328 icp = mtod(m, struct icmp *); 329 if (in_cksum(m, icmplen)) { 330 icmpstat.icps_checksum++; 331 goto freeit; 332 } 333 m->m_len += hlen; 334 m->m_data -= hlen; 335 336 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 337 /* 338 * Deliver very specific ICMP type only. 339 */ 340 switch (icp->icmp_type) { 341 case ICMP_UNREACH: 342 case ICMP_TIMXCEED: 343 break; 344 default: 345 goto freeit; 346 } 347 } 348 349 #ifdef ICMPPRINTFS 350 if (icmpprintfs) 351 printf("icmp_input, type %d code %d\n", icp->icmp_type, 352 icp->icmp_code); 353 #endif 354 355 /* 356 * Message type specific processing. 357 */ 358 if (icp->icmp_type > ICMP_MAXTYPE) 359 goto raw; 360 361 /* Initialize */ 362 bzero(&icmpsrc, sizeof(icmpsrc)); 363 icmpsrc.sin_len = sizeof(struct sockaddr_in); 364 icmpsrc.sin_family = AF_INET; 365 bzero(&icmpdst, sizeof(icmpdst)); 366 icmpdst.sin_len = sizeof(struct sockaddr_in); 367 icmpdst.sin_family = AF_INET; 368 bzero(&icmpgw, sizeof(icmpgw)); 369 icmpgw.sin_len = sizeof(struct sockaddr_in); 370 icmpgw.sin_family = AF_INET; 371 372 icmpstat.icps_inhist[icp->icmp_type]++; 373 code = icp->icmp_code; 374 switch (icp->icmp_type) { 375 376 case ICMP_UNREACH: 377 switch (code) { 378 case ICMP_UNREACH_NET: 379 case ICMP_UNREACH_HOST: 380 case ICMP_UNREACH_SRCFAIL: 381 case ICMP_UNREACH_NET_UNKNOWN: 382 case ICMP_UNREACH_HOST_UNKNOWN: 383 case ICMP_UNREACH_ISOLATED: 384 case ICMP_UNREACH_TOSNET: 385 case ICMP_UNREACH_TOSHOST: 386 case ICMP_UNREACH_HOST_PRECEDENCE: 387 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 388 code = PRC_UNREACH_NET; 389 break; 390 391 case ICMP_UNREACH_NEEDFRAG: 392 code = PRC_MSGSIZE; 393 break; 394 395 /* 396 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 397 * Treat subcodes 2,3 as immediate RST 398 */ 399 case ICMP_UNREACH_PROTOCOL: 400 case ICMP_UNREACH_PORT: 401 code = PRC_UNREACH_PORT; 402 break; 403 404 case ICMP_UNREACH_NET_PROHIB: 405 case ICMP_UNREACH_HOST_PROHIB: 406 case ICMP_UNREACH_FILTER_PROHIB: 407 code = PRC_UNREACH_ADMIN_PROHIB; 408 break; 409 410 default: 411 goto badcode; 412 } 413 goto deliver; 414 415 case ICMP_TIMXCEED: 416 if (code > 1) 417 goto badcode; 418 code += PRC_TIMXCEED_INTRANS; 419 goto deliver; 420 421 case ICMP_PARAMPROB: 422 if (code > 1) 423 goto badcode; 424 code = PRC_PARAMPROB; 425 goto deliver; 426 427 case ICMP_SOURCEQUENCH: 428 if (code) 429 goto badcode; 430 code = PRC_QUENCH; 431 deliver: 432 /* 433 * Problem with datagram; advise higher level routines. 434 */ 435 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 436 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 437 icmpstat.icps_badlen++; 438 goto freeit; 439 } 440 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 441 /* Discard ICMP's in response to multicast packets */ 442 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 443 goto badcode; 444 #ifdef ICMPPRINTFS 445 if (icmpprintfs) 446 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 447 #endif 448 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 449 /* 450 * XXX if the packet contains [IPv4 AH TCP], we can't make a 451 * notification to TCP layer. 452 */ 453 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 454 if (ctlfunc) 455 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 456 (void *)&icp->icmp_ip); 457 break; 458 459 badcode: 460 icmpstat.icps_badcode++; 461 break; 462 463 case ICMP_ECHO: 464 if (!icmpbmcastecho 465 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 466 icmpstat.icps_bmcastecho++; 467 break; 468 } 469 icp->icmp_type = ICMP_ECHOREPLY; 470 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 471 goto freeit; 472 else 473 goto reflect; 474 475 case ICMP_TSTAMP: 476 if (!icmpbmcastecho 477 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 478 icmpstat.icps_bmcasttstamp++; 479 break; 480 } 481 if (icmplen < ICMP_TSLEN) { 482 icmpstat.icps_badlen++; 483 break; 484 } 485 icp->icmp_type = ICMP_TSTAMPREPLY; 486 icp->icmp_rtime = iptime(); 487 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 488 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 489 goto freeit; 490 else 491 goto reflect; 492 493 case ICMP_MASKREQ: 494 if (icmpmaskrepl == 0) 495 break; 496 /* 497 * We are not able to respond with all ones broadcast 498 * unless we receive it over a point-to-point interface. 499 */ 500 if (icmplen < ICMP_MASKLEN) 501 break; 502 switch (ip->ip_dst.s_addr) { 503 504 case INADDR_BROADCAST: 505 case INADDR_ANY: 506 icmpdst.sin_addr = ip->ip_src; 507 break; 508 509 default: 510 icmpdst.sin_addr = ip->ip_dst; 511 } 512 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 513 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 514 if (ia == 0) 515 break; 516 if (ia->ia_ifp == 0) 517 break; 518 icp->icmp_type = ICMP_MASKREPLY; 519 if (icmpmaskfake == 0) 520 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 521 else 522 icp->icmp_mask = icmpmaskfake; 523 if (ip->ip_src.s_addr == 0) { 524 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 525 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 526 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 527 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 528 } 529 reflect: 530 ip->ip_len += hlen; /* since ip_input deducts this */ 531 icmpstat.icps_reflect++; 532 icmpstat.icps_outhist[icp->icmp_type]++; 533 icmp_reflect(m); 534 return; 535 536 case ICMP_REDIRECT: 537 if (log_redirect) { 538 u_long src, dst, gw; 539 540 src = ntohl(ip->ip_src.s_addr); 541 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 542 gw = ntohl(icp->icmp_gwaddr.s_addr); 543 printf("icmp redirect from %d.%d.%d.%d: " 544 "%d.%d.%d.%d => %d.%d.%d.%d\n", 545 (int)(src >> 24), (int)((src >> 16) & 0xff), 546 (int)((src >> 8) & 0xff), (int)(src & 0xff), 547 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 548 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 549 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 550 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 551 } 552 /* 553 * RFC1812 says we must ignore ICMP redirects if we 554 * are acting as router. 555 */ 556 if (drop_redirect || ipforwarding) 557 break; 558 if (code > 3) 559 goto badcode; 560 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 561 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 562 icmpstat.icps_badlen++; 563 break; 564 } 565 /* 566 * Short circuit routing redirects to force 567 * immediate change in the kernel's routing 568 * tables. The message is also handed to anyone 569 * listening on a raw socket (e.g. the routing 570 * daemon for use in updating its tables). 571 */ 572 icmpgw.sin_addr = ip->ip_src; 573 icmpdst.sin_addr = icp->icmp_gwaddr; 574 #ifdef ICMPPRINTFS 575 if (icmpprintfs) { 576 char buf[4 * sizeof "123"]; 577 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 578 579 printf("redirect dst %s to %s\n", 580 buf, inet_ntoa(icp->icmp_gwaddr)); 581 } 582 #endif 583 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 584 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 585 in_rtredirect((struct sockaddr *)&icmpsrc, 586 (struct sockaddr *)&icmpdst, 587 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 588 (struct sockaddr *)&icmpgw, fibnum); 589 } 590 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 591 #ifdef IPSEC 592 key_sa_routechange((struct sockaddr *)&icmpsrc); 593 #endif 594 break; 595 596 /* 597 * No kernel processing for the following; 598 * just fall through to send to raw listener. 599 */ 600 case ICMP_ECHOREPLY: 601 case ICMP_ROUTERADVERT: 602 case ICMP_ROUTERSOLICIT: 603 case ICMP_TSTAMPREPLY: 604 case ICMP_IREQREPLY: 605 case ICMP_MASKREPLY: 606 default: 607 break; 608 } 609 610 raw: 611 rip_input(m, off); 612 return; 613 614 freeit: 615 m_freem(m); 616 } 617 618 /* 619 * Reflect the ip packet back to the source 620 */ 621 static void 622 icmp_reflect(struct mbuf *m) 623 { 624 struct ip *ip = mtod(m, struct ip *); 625 struct ifaddr *ifa; 626 struct ifnet *ifn; 627 struct in_ifaddr *ia; 628 struct in_addr t; 629 struct mbuf *opts = 0; 630 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 631 632 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 633 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 634 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 635 m_freem(m); /* Bad return address */ 636 icmpstat.icps_badaddr++; 637 goto done; /* Ip_output() will check for broadcast */ 638 } 639 640 t = ip->ip_dst; 641 ip->ip_dst = ip->ip_src; 642 643 /* 644 * Source selection for ICMP replies: 645 * 646 * If the incoming packet was addressed directly to one of our 647 * own addresses, use dst as the src for the reply. 648 */ 649 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 650 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 651 goto match; 652 /* 653 * If the incoming packet was addressed to one of our broadcast 654 * addresses, use the first non-broadcast address which corresponds 655 * to the incoming interface. 656 */ 657 if (m->m_pkthdr.rcvif != NULL && 658 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 659 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 660 if (ifa->ifa_addr->sa_family != AF_INET) 661 continue; 662 ia = ifatoia(ifa); 663 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 664 t.s_addr) 665 goto match; 666 } 667 } 668 /* 669 * If the packet was transiting through us, use the address of 670 * the interface the packet came through in. If that interface 671 * doesn't have a suitable IP address, the normal selection 672 * criteria apply. 673 */ 674 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 675 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 676 if (ifa->ifa_addr->sa_family != AF_INET) 677 continue; 678 ia = ifatoia(ifa); 679 goto match; 680 } 681 } 682 /* 683 * If the incoming packet was not addressed directly to us, use 684 * designated interface for icmp replies specified by sysctl 685 * net.inet.icmp.reply_src (default not set). Otherwise continue 686 * with normal source selection. 687 */ 688 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 689 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 690 if (ifa->ifa_addr->sa_family != AF_INET) 691 continue; 692 ia = ifatoia(ifa); 693 goto match; 694 } 695 } 696 /* 697 * If the packet was transiting through us, use the address of 698 * the interface that is the closest to the packet source. 699 * When we don't have a route back to the packet source, stop here 700 * and drop the packet. 701 */ 702 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 703 if (ia == NULL) { 704 m_freem(m); 705 icmpstat.icps_noroute++; 706 goto done; 707 } 708 match: 709 #ifdef MAC 710 mac_netinet_icmp_replyinplace(m); 711 #endif 712 t = IA_SIN(ia)->sin_addr; 713 ip->ip_src = t; 714 ip->ip_ttl = ip_defttl; 715 716 if (optlen > 0) { 717 register u_char *cp; 718 int opt, cnt; 719 u_int len; 720 721 /* 722 * Retrieve any source routing from the incoming packet; 723 * add on any record-route or timestamp options. 724 */ 725 cp = (u_char *) (ip + 1); 726 if ((opts = ip_srcroute(m)) == 0 && 727 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 728 opts->m_len = sizeof(struct in_addr); 729 mtod(opts, struct in_addr *)->s_addr = 0; 730 } 731 if (opts) { 732 #ifdef ICMPPRINTFS 733 if (icmpprintfs) 734 printf("icmp_reflect optlen %d rt %d => ", 735 optlen, opts->m_len); 736 #endif 737 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 738 opt = cp[IPOPT_OPTVAL]; 739 if (opt == IPOPT_EOL) 740 break; 741 if (opt == IPOPT_NOP) 742 len = 1; 743 else { 744 if (cnt < IPOPT_OLEN + sizeof(*cp)) 745 break; 746 len = cp[IPOPT_OLEN]; 747 if (len < IPOPT_OLEN + sizeof(*cp) || 748 len > cnt) 749 break; 750 } 751 /* 752 * Should check for overflow, but it "can't happen" 753 */ 754 if (opt == IPOPT_RR || opt == IPOPT_TS || 755 opt == IPOPT_SECURITY) { 756 bcopy((caddr_t)cp, 757 mtod(opts, caddr_t) + opts->m_len, len); 758 opts->m_len += len; 759 } 760 } 761 /* Terminate & pad, if necessary */ 762 cnt = opts->m_len % 4; 763 if (cnt) { 764 for (; cnt < 4; cnt++) { 765 *(mtod(opts, caddr_t) + opts->m_len) = 766 IPOPT_EOL; 767 opts->m_len++; 768 } 769 } 770 #ifdef ICMPPRINTFS 771 if (icmpprintfs) 772 printf("%d\n", opts->m_len); 773 #endif 774 } 775 /* 776 * Now strip out original options by copying rest of first 777 * mbuf's data back, and adjust the IP length. 778 */ 779 ip->ip_len -= optlen; 780 ip->ip_v = IPVERSION; 781 ip->ip_hl = 5; 782 m->m_len -= optlen; 783 if (m->m_flags & M_PKTHDR) 784 m->m_pkthdr.len -= optlen; 785 optlen += sizeof(struct ip); 786 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 787 (unsigned)(m->m_len - sizeof(struct ip))); 788 } 789 m_tag_delete_nonpersistent(m); 790 m->m_flags &= ~(M_BCAST|M_MCAST); 791 icmp_send(m, opts); 792 done: 793 if (opts) 794 (void)m_free(opts); 795 } 796 797 /* 798 * Send an icmp packet back to the ip level, 799 * after supplying a checksum. 800 */ 801 static void 802 icmp_send(struct mbuf *m, struct mbuf *opts) 803 { 804 register struct ip *ip = mtod(m, struct ip *); 805 register int hlen; 806 register struct icmp *icp; 807 808 hlen = ip->ip_hl << 2; 809 m->m_data += hlen; 810 m->m_len -= hlen; 811 icp = mtod(m, struct icmp *); 812 icp->icmp_cksum = 0; 813 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 814 m->m_data -= hlen; 815 m->m_len += hlen; 816 m->m_pkthdr.rcvif = (struct ifnet *)0; 817 #ifdef ICMPPRINTFS 818 if (icmpprintfs) { 819 char buf[4 * sizeof "123"]; 820 strcpy(buf, inet_ntoa(ip->ip_dst)); 821 printf("icmp_send dst %s src %s\n", 822 buf, inet_ntoa(ip->ip_src)); 823 } 824 #endif 825 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 826 } 827 828 n_time 829 iptime(void) 830 { 831 struct timeval atv; 832 u_long t; 833 834 getmicrotime(&atv); 835 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 836 return (htonl(t)); 837 } 838 839 /* 840 * Return the next larger or smaller MTU plateau (table from RFC 1191) 841 * given current value MTU. If DIR is less than zero, a larger plateau 842 * is returned; otherwise, a smaller value is returned. 843 */ 844 int 845 ip_next_mtu(int mtu, int dir) 846 { 847 static int mtutab[] = { 848 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 849 296, 68, 0 850 }; 851 int i, size; 852 853 size = (sizeof mtutab) / (sizeof mtutab[0]); 854 if (dir >= 0) { 855 for (i = 0; i < size; i++) 856 if (mtu > mtutab[i]) 857 return mtutab[i]; 858 } else { 859 for (i = size - 1; i >= 0; i--) 860 if (mtu < mtutab[i]) 861 return mtutab[i]; 862 if (mtu == mtutab[0]) 863 return mtutab[0]; 864 } 865 return 0; 866 } 867 868 869 /* 870 * badport_bandlim() - check for ICMP bandwidth limit 871 * 872 * Return 0 if it is ok to send an ICMP error response, -1 if we have 873 * hit our bandwidth limit and it is not ok. 874 * 875 * If icmplim is <= 0, the feature is disabled and 0 is returned. 876 * 877 * For now we separate the TCP and UDP subsystems w/ different 'which' 878 * values. We may eventually remove this separation (and simplify the 879 * code further). 880 * 881 * Note that the printing of the error message is delayed so we can 882 * properly print the icmp error rate that the system was trying to do 883 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 884 * the 'final' error, but it doesn't make sense to solve the printing 885 * delay with more complex code. 886 */ 887 888 int 889 badport_bandlim(int which) 890 { 891 #define N(a) (sizeof (a) / sizeof (a[0])) 892 static struct rate { 893 const char *type; 894 struct timeval lasttime; 895 int curpps; 896 } rates[BANDLIM_MAX+1] = { 897 { "icmp unreach response" }, 898 { "icmp ping response" }, 899 { "icmp tstamp response" }, 900 { "closed port RST response" }, 901 { "open port RST response" }, 902 { "icmp6 unreach response" } 903 }; 904 905 /* 906 * Return ok status if feature disabled or argument out of range. 907 */ 908 if (icmplim > 0 && (u_int) which < N(rates)) { 909 struct rate *r = &rates[which]; 910 int opps = r->curpps; 911 912 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 913 return -1; /* discard packet */ 914 /* 915 * If we've dropped below the threshold after having 916 * rate-limited traffic print the message. This preserves 917 * the previous behaviour at the expense of added complexity. 918 */ 919 if (icmplim_output && opps > icmplim) 920 printf("Limiting %s from %d to %d packets/sec\n", 921 r->type, opps, icmplim); 922 } 923 return 0; /* okay to send packet */ 924 #undef N 925 } 926