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sys/netinet/ip_icmp.c
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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_create_mbuf_netlayer(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 icp = mtod(m, struct icmp *); 231 icmpstat.icps_outhist[type]++; 232 icp->icmp_type = type; 233 if (type == ICMP_REDIRECT) 234 icp->icmp_gwaddr.s_addr = dest; 235 else { 236 icp->icmp_void = 0; 237 /* 238 * The following assignments assume an overlay with the 239 * just zeroed icmp_void field. 240 */ 241 if (type == ICMP_PARAMPROB) { 242 icp->icmp_pptr = code; 243 code = 0; 244 } else if (type == ICMP_UNREACH && 245 code == ICMP_UNREACH_NEEDFRAG && mtu) { 246 icp->icmp_nextmtu = htons(mtu); 247 } 248 } 249 icp->icmp_code = code; 250 251 /* 252 * Copy the quotation into ICMP message and 253 * convert quoted IP header back to network representation. 254 */ 255 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 256 nip = &icp->icmp_ip; 257 nip->ip_len = htons(nip->ip_len); 258 nip->ip_off = htons(nip->ip_off); 259 260 /* 261 * Set up ICMP message mbuf and copy old IP header (without options 262 * in front of ICMP message. 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(struct mbuf *m, int off) 289 { 290 struct icmp *icp; 291 struct in_ifaddr *ia; 292 struct ip *ip = mtod(m, struct ip *); 293 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 294 int hlen = off; 295 int icmplen = ip->ip_len; 296 int i, code; 297 void (*ctlfunc)(int, struct sockaddr *, void *); 298 299 /* 300 * Locate icmp structure in mbuf, and check 301 * that not corrupted and of at least minimum length. 302 */ 303 #ifdef ICMPPRINTFS 304 if (icmpprintfs) { 305 char buf[4 * sizeof "123"]; 306 strcpy(buf, inet_ntoa(ip->ip_src)); 307 printf("icmp_input from %s to %s, len %d\n", 308 buf, inet_ntoa(ip->ip_dst), icmplen); 309 } 310 #endif 311 if (icmplen < ICMP_MINLEN) { 312 icmpstat.icps_tooshort++; 313 goto freeit; 314 } 315 i = hlen + min(icmplen, ICMP_ADVLENMIN); 316 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 317 icmpstat.icps_tooshort++; 318 return; 319 } 320 ip = mtod(m, struct ip *); 321 m->m_len -= hlen; 322 m->m_data += hlen; 323 icp = mtod(m, struct icmp *); 324 if (in_cksum(m, icmplen)) { 325 icmpstat.icps_checksum++; 326 goto freeit; 327 } 328 m->m_len += hlen; 329 m->m_data -= hlen; 330 331 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 332 /* 333 * Deliver very specific ICMP type only. 334 */ 335 switch (icp->icmp_type) { 336 case ICMP_UNREACH: 337 case ICMP_TIMXCEED: 338 break; 339 default: 340 goto freeit; 341 } 342 } 343 344 #ifdef ICMPPRINTFS 345 if (icmpprintfs) 346 printf("icmp_input, type %d code %d\n", icp->icmp_type, 347 icp->icmp_code); 348 #endif 349 350 /* 351 * Message type specific processing. 352 */ 353 if (icp->icmp_type > ICMP_MAXTYPE) 354 goto raw; 355 356 /* Initialize */ 357 bzero(&icmpsrc, sizeof(icmpsrc)); 358 icmpsrc.sin_len = sizeof(struct sockaddr_in); 359 icmpsrc.sin_family = AF_INET; 360 bzero(&icmpdst, sizeof(icmpdst)); 361 icmpdst.sin_len = sizeof(struct sockaddr_in); 362 icmpdst.sin_family = AF_INET; 363 bzero(&icmpgw, sizeof(icmpgw)); 364 icmpgw.sin_len = sizeof(struct sockaddr_in); 365 icmpgw.sin_family = AF_INET; 366 367 icmpstat.icps_inhist[icp->icmp_type]++; 368 code = icp->icmp_code; 369 switch (icp->icmp_type) { 370 371 case ICMP_UNREACH: 372 switch (code) { 373 case ICMP_UNREACH_NET: 374 case ICMP_UNREACH_HOST: 375 case ICMP_UNREACH_SRCFAIL: 376 case ICMP_UNREACH_NET_UNKNOWN: 377 case ICMP_UNREACH_HOST_UNKNOWN: 378 case ICMP_UNREACH_ISOLATED: 379 case ICMP_UNREACH_TOSNET: 380 case ICMP_UNREACH_TOSHOST: 381 case ICMP_UNREACH_HOST_PRECEDENCE: 382 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 383 code = PRC_UNREACH_NET; 384 break; 385 386 case ICMP_UNREACH_NEEDFRAG: 387 code = PRC_MSGSIZE; 388 break; 389 390 /* 391 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 392 * Treat subcodes 2,3 as immediate RST 393 */ 394 case ICMP_UNREACH_PROTOCOL: 395 case ICMP_UNREACH_PORT: 396 code = PRC_UNREACH_PORT; 397 break; 398 399 case ICMP_UNREACH_NET_PROHIB: 400 case ICMP_UNREACH_HOST_PROHIB: 401 case ICMP_UNREACH_FILTER_PROHIB: 402 code = PRC_UNREACH_ADMIN_PROHIB; 403 break; 404 405 default: 406 goto badcode; 407 } 408 goto deliver; 409 410 case ICMP_TIMXCEED: 411 if (code > 1) 412 goto badcode; 413 code += PRC_TIMXCEED_INTRANS; 414 goto deliver; 415 416 case ICMP_PARAMPROB: 417 if (code > 1) 418 goto badcode; 419 code = PRC_PARAMPROB; 420 goto deliver; 421 422 case ICMP_SOURCEQUENCH: 423 if (code) 424 goto badcode; 425 code = PRC_QUENCH; 426 deliver: 427 /* 428 * Problem with datagram; advise higher level routines. 429 */ 430 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 431 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 432 icmpstat.icps_badlen++; 433 goto freeit; 434 } 435 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 436 /* Discard ICMP's in response to multicast packets */ 437 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 438 goto badcode; 439 #ifdef ICMPPRINTFS 440 if (icmpprintfs) 441 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 442 #endif 443 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 444 /* 445 * XXX if the packet contains [IPv4 AH TCP], we can't make a 446 * notification to TCP layer. 447 */ 448 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 449 if (ctlfunc) 450 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 451 (void *)&icp->icmp_ip); 452 break; 453 454 badcode: 455 icmpstat.icps_badcode++; 456 break; 457 458 case ICMP_ECHO: 459 if (!icmpbmcastecho 460 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 461 icmpstat.icps_bmcastecho++; 462 break; 463 } 464 icp->icmp_type = ICMP_ECHOREPLY; 465 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 466 goto freeit; 467 else 468 goto reflect; 469 470 case ICMP_TSTAMP: 471 if (!icmpbmcastecho 472 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 473 icmpstat.icps_bmcasttstamp++; 474 break; 475 } 476 if (icmplen < ICMP_TSLEN) { 477 icmpstat.icps_badlen++; 478 break; 479 } 480 icp->icmp_type = ICMP_TSTAMPREPLY; 481 icp->icmp_rtime = iptime(); 482 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 483 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 484 goto freeit; 485 else 486 goto reflect; 487 488 case ICMP_MASKREQ: 489 if (icmpmaskrepl == 0) 490 break; 491 /* 492 * We are not able to respond with all ones broadcast 493 * unless we receive it over a point-to-point interface. 494 */ 495 if (icmplen < ICMP_MASKLEN) 496 break; 497 switch (ip->ip_dst.s_addr) { 498 499 case INADDR_BROADCAST: 500 case INADDR_ANY: 501 icmpdst.sin_addr = ip->ip_src; 502 break; 503 504 default: 505 icmpdst.sin_addr = ip->ip_dst; 506 } 507 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 508 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 509 if (ia == 0) 510 break; 511 if (ia->ia_ifp == 0) 512 break; 513 icp->icmp_type = ICMP_MASKREPLY; 514 if (icmpmaskfake == 0) 515 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 516 else 517 icp->icmp_mask = icmpmaskfake; 518 if (ip->ip_src.s_addr == 0) { 519 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 520 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 521 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 522 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 523 } 524 reflect: 525 ip->ip_len += hlen; /* since ip_input deducts this */ 526 icmpstat.icps_reflect++; 527 icmpstat.icps_outhist[icp->icmp_type]++; 528 icmp_reflect(m); 529 return; 530 531 case ICMP_REDIRECT: 532 if (log_redirect) { 533 u_long src, dst, gw; 534 535 src = ntohl(ip->ip_src.s_addr); 536 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 537 gw = ntohl(icp->icmp_gwaddr.s_addr); 538 printf("icmp redirect from %d.%d.%d.%d: " 539 "%d.%d.%d.%d => %d.%d.%d.%d\n", 540 (int)(src >> 24), (int)((src >> 16) & 0xff), 541 (int)((src >> 8) & 0xff), (int)(src & 0xff), 542 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 543 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 544 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 545 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 546 } 547 /* 548 * RFC1812 says we must ignore ICMP redirects if we 549 * are acting as router. 550 */ 551 if (drop_redirect || ipforwarding) 552 break; 553 if (code > 3) 554 goto badcode; 555 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 556 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 557 icmpstat.icps_badlen++; 558 break; 559 } 560 /* 561 * Short circuit routing redirects to force 562 * immediate change in the kernel's routing 563 * tables. The message is also handed to anyone 564 * listening on a raw socket (e.g. the routing 565 * daemon for use in updating its tables). 566 */ 567 icmpgw.sin_addr = ip->ip_src; 568 icmpdst.sin_addr = icp->icmp_gwaddr; 569 #ifdef ICMPPRINTFS 570 if (icmpprintfs) { 571 char buf[4 * sizeof "123"]; 572 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 573 574 printf("redirect dst %s to %s\n", 575 buf, inet_ntoa(icp->icmp_gwaddr)); 576 } 577 #endif 578 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 579 rtredirect((struct sockaddr *)&icmpsrc, 580 (struct sockaddr *)&icmpdst, 581 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 582 (struct sockaddr *)&icmpgw); 583 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 584 #ifdef IPSEC 585 key_sa_routechange((struct sockaddr *)&icmpsrc); 586 #endif 587 break; 588 589 /* 590 * No kernel processing for the following; 591 * just fall through to send to raw listener. 592 */ 593 case ICMP_ECHOREPLY: 594 case ICMP_ROUTERADVERT: 595 case ICMP_ROUTERSOLICIT: 596 case ICMP_TSTAMPREPLY: 597 case ICMP_IREQREPLY: 598 case ICMP_MASKREPLY: 599 default: 600 break; 601 } 602 603 raw: 604 rip_input(m, off); 605 return; 606 607 freeit: 608 m_freem(m); 609 } 610 611 /* 612 * Reflect the ip packet back to the source 613 */ 614 static void 615 icmp_reflect(struct mbuf *m) 616 { 617 struct ip *ip = mtod(m, struct ip *); 618 struct ifaddr *ifa; 619 struct ifnet *ifn; 620 struct in_ifaddr *ia; 621 struct in_addr t; 622 struct mbuf *opts = 0; 623 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 624 625 if (!in_canforward(ip->ip_src) && 626 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 627 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 628 m_freem(m); /* Bad return address */ 629 icmpstat.icps_badaddr++; 630 goto done; /* Ip_output() will check for broadcast */ 631 } 632 t = ip->ip_dst; 633 ip->ip_dst = ip->ip_src; 634 635 /* 636 * Source selection for ICMP replies: 637 * 638 * If the incoming packet was addressed directly to one of our 639 * own addresses, use dst as the src for the reply. 640 */ 641 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 642 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 643 goto match; 644 /* 645 * If the incoming packet was addressed to one of our broadcast 646 * addresses, use the first non-broadcast address which corresponds 647 * to the incoming interface. 648 */ 649 if (m->m_pkthdr.rcvif != NULL && 650 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 651 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 652 if (ifa->ifa_addr->sa_family != AF_INET) 653 continue; 654 ia = ifatoia(ifa); 655 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 656 t.s_addr) 657 goto match; 658 } 659 } 660 /* 661 * If the packet was transiting through us, use the address of 662 * the interface the packet came through in. If that interface 663 * doesn't have a suitable IP address, the normal selection 664 * criteria apply. 665 */ 666 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 667 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 668 if (ifa->ifa_addr->sa_family != AF_INET) 669 continue; 670 ia = ifatoia(ifa); 671 goto match; 672 } 673 } 674 /* 675 * If the incoming packet was not addressed directly to us, use 676 * designated interface for icmp replies specified by sysctl 677 * net.inet.icmp.reply_src (default not set). Otherwise continue 678 * with normal source selection. 679 */ 680 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 681 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 682 if (ifa->ifa_addr->sa_family != AF_INET) 683 continue; 684 ia = ifatoia(ifa); 685 goto match; 686 } 687 } 688 /* 689 * If the packet was transiting through us, use the address of 690 * the interface that is the closest to the packet source. 691 * When we don't have a route back to the packet source, stop here 692 * and drop the packet. 693 */ 694 ia = ip_rtaddr(ip->ip_dst); 695 if (ia == NULL) { 696 m_freem(m); 697 icmpstat.icps_noroute++; 698 goto done; 699 } 700 match: 701 #ifdef MAC 702 mac_reflect_mbuf_icmp(m); 703 #endif 704 t = IA_SIN(ia)->sin_addr; 705 ip->ip_src = t; 706 ip->ip_ttl = ip_defttl; 707 708 if (optlen > 0) { 709 register u_char *cp; 710 int opt, cnt; 711 u_int len; 712 713 /* 714 * Retrieve any source routing from the incoming packet; 715 * add on any record-route or timestamp options. 716 */ 717 cp = (u_char *) (ip + 1); 718 if ((opts = ip_srcroute(m)) == 0 && 719 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 720 opts->m_len = sizeof(struct in_addr); 721 mtod(opts, struct in_addr *)->s_addr = 0; 722 } 723 if (opts) { 724 #ifdef ICMPPRINTFS 725 if (icmpprintfs) 726 printf("icmp_reflect optlen %d rt %d => ", 727 optlen, opts->m_len); 728 #endif 729 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 730 opt = cp[IPOPT_OPTVAL]; 731 if (opt == IPOPT_EOL) 732 break; 733 if (opt == IPOPT_NOP) 734 len = 1; 735 else { 736 if (cnt < IPOPT_OLEN + sizeof(*cp)) 737 break; 738 len = cp[IPOPT_OLEN]; 739 if (len < IPOPT_OLEN + sizeof(*cp) || 740 len > cnt) 741 break; 742 } 743 /* 744 * Should check for overflow, but it "can't happen" 745 */ 746 if (opt == IPOPT_RR || opt == IPOPT_TS || 747 opt == IPOPT_SECURITY) { 748 bcopy((caddr_t)cp, 749 mtod(opts, caddr_t) + opts->m_len, len); 750 opts->m_len += len; 751 } 752 } 753 /* Terminate & pad, if necessary */ 754 cnt = opts->m_len % 4; 755 if (cnt) { 756 for (; cnt < 4; cnt++) { 757 *(mtod(opts, caddr_t) + opts->m_len) = 758 IPOPT_EOL; 759 opts->m_len++; 760 } 761 } 762 #ifdef ICMPPRINTFS 763 if (icmpprintfs) 764 printf("%d\n", opts->m_len); 765 #endif 766 } 767 /* 768 * Now strip out original options by copying rest of first 769 * mbuf's data back, and adjust the IP length. 770 */ 771 ip->ip_len -= optlen; 772 ip->ip_v = IPVERSION; 773 ip->ip_hl = 5; 774 m->m_len -= optlen; 775 if (m->m_flags & M_PKTHDR) 776 m->m_pkthdr.len -= optlen; 777 optlen += sizeof(struct ip); 778 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 779 (unsigned)(m->m_len - sizeof(struct ip))); 780 } 781 m_tag_delete_nonpersistent(m); 782 m->m_flags &= ~(M_BCAST|M_MCAST); 783 icmp_send(m, opts); 784 done: 785 if (opts) 786 (void)m_free(opts); 787 } 788 789 /* 790 * Send an icmp packet back to the ip level, 791 * after supplying a checksum. 792 */ 793 static void 794 icmp_send(struct mbuf *m, struct mbuf *opts) 795 { 796 register struct ip *ip = mtod(m, struct ip *); 797 register int hlen; 798 register struct icmp *icp; 799 800 hlen = ip->ip_hl << 2; 801 m->m_data += hlen; 802 m->m_len -= hlen; 803 icp = mtod(m, struct icmp *); 804 icp->icmp_cksum = 0; 805 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 806 m->m_data -= hlen; 807 m->m_len += hlen; 808 m->m_pkthdr.rcvif = (struct ifnet *)0; 809 #ifdef ICMPPRINTFS 810 if (icmpprintfs) { 811 char buf[4 * sizeof "123"]; 812 strcpy(buf, inet_ntoa(ip->ip_dst)); 813 printf("icmp_send dst %s src %s\n", 814 buf, inet_ntoa(ip->ip_src)); 815 } 816 #endif 817 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 818 } 819 820 n_time 821 iptime(void) 822 { 823 struct timeval atv; 824 u_long t; 825 826 getmicrotime(&atv); 827 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 828 return (htonl(t)); 829 } 830 831 /* 832 * Return the next larger or smaller MTU plateau (table from RFC 1191) 833 * given current value MTU. If DIR is less than zero, a larger plateau 834 * is returned; otherwise, a smaller value is returned. 835 */ 836 int 837 ip_next_mtu(int mtu, int dir) 838 { 839 static int mtutab[] = { 840 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 841 296, 68, 0 842 }; 843 int i, size; 844 845 size = (sizeof mtutab) / (sizeof mtutab[0]); 846 if (dir >= 0) { 847 for (i = 0; i < size; i++) 848 if (mtu > mtutab[i]) 849 return mtutab[i]; 850 } else { 851 for (i = size - 1; i >= 0; i--) 852 if (mtu < mtutab[i]) 853 return mtutab[i]; 854 if (mtu == mtutab[0]) 855 return mtutab[0]; 856 } 857 return 0; 858 } 859 860 861 /* 862 * badport_bandlim() - check for ICMP bandwidth limit 863 * 864 * Return 0 if it is ok to send an ICMP error response, -1 if we have 865 * hit our bandwidth limit and it is not ok. 866 * 867 * If icmplim is <= 0, the feature is disabled and 0 is returned. 868 * 869 * For now we separate the TCP and UDP subsystems w/ different 'which' 870 * values. We may eventually remove this separation (and simplify the 871 * code further). 872 * 873 * Note that the printing of the error message is delayed so we can 874 * properly print the icmp error rate that the system was trying to do 875 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 876 * the 'final' error, but it doesn't make sense to solve the printing 877 * delay with more complex code. 878 */ 879 880 int 881 badport_bandlim(int which) 882 { 883 #define N(a) (sizeof (a) / sizeof (a[0])) 884 static struct rate { 885 const char *type; 886 struct timeval lasttime; 887 int curpps; 888 } rates[BANDLIM_MAX+1] = { 889 { "icmp unreach response" }, 890 { "icmp ping response" }, 891 { "icmp tstamp response" }, 892 { "closed port RST response" }, 893 { "open port RST response" }, 894 { "icmp6 unreach response" } 895 }; 896 897 /* 898 * Return ok status if feature disabled or argument out of range. 899 */ 900 if (icmplim > 0 && (u_int) which < N(rates)) { 901 struct rate *r = &rates[which]; 902 int opps = r->curpps; 903 904 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 905 return -1; /* discard packet */ 906 /* 907 * If we've dropped below the threshold after having 908 * rate-limited traffic print the message. This preserves 909 * the previous behaviour at the expense of added complexity. 910 */ 911 if (icmplim_output && opps > icmplim) 912 printf("Limiting %s from %d to %d packets/sec\n", 913 r->type, opps, icmplim); 914 } 915 return 0; /* okay to send packet */ 916 #undef N 917 }
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