Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/ip_icmp.c
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1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: releng/12.0/sys/netinet/ip_icmp.c 340267 2018-11-08 21:58:23Z gjb $"); 36 37 #include "opt_inet.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/mbuf.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/time.h> 45 #include <sys/kernel.h> 46 #include <sys/lock.h> 47 #include <sys/rmlock.h> 48 #include <sys/sysctl.h> 49 #include <sys/syslog.h> 50 51 #include <net/if.h> 52 #include <net/if_var.h> 53 #include <net/if_types.h> 54 #include <net/route.h> 55 #include <net/vnet.h> 56 57 #include <netinet/in.h> 58 #include <netinet/in_fib.h> 59 #include <netinet/in_pcb.h> 60 #include <netinet/in_systm.h> 61 #include <netinet/in_var.h> 62 #include <netinet/ip.h> 63 #include <netinet/ip_icmp.h> 64 #include <netinet/ip_var.h> 65 #include <netinet/ip_options.h> 66 #include <netinet/sctp.h> 67 #include <netinet/tcp.h> 68 #include <netinet/tcp_var.h> 69 #include <netinet/tcpip.h> 70 #include <netinet/icmp_var.h> 71 72 73 #ifdef INET 74 75 #include <machine/in_cksum.h> 76 77 #include <security/mac/mac_framework.h> 78 #endif /* INET */ 79 80 /* 81 * ICMP routines: error generation, receive packet processing, and 82 * routines to turnaround packets back to the originator, and 83 * host table maintenance routines. 84 */ 85 VNET_DEFINE_STATIC(int, icmplim) = 200; 86 #define V_icmplim VNET(icmplim) 87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, 88 &VNET_NAME(icmplim), 0, 89 "Maximum number of ICMP responses per second"); 90 91 VNET_DEFINE_STATIC(int, icmplim_output) = 1; 92 #define V_icmplim_output VNET(icmplim_output) 93 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW, 94 &VNET_NAME(icmplim_output), 0, 95 "Enable logging of ICMP response rate limiting"); 96 97 #ifdef INET 98 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 99 VNET_PCPUSTAT_SYSINIT(icmpstat); 100 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 101 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 102 103 #ifdef VIMAGE 104 VNET_PCPUSTAT_SYSUNINIT(icmpstat); 105 #endif /* VIMAGE */ 106 107 VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0; 108 #define V_icmpmaskrepl VNET(icmpmaskrepl) 109 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 110 &VNET_NAME(icmpmaskrepl), 0, 111 "Reply to ICMP Address Mask Request packets"); 112 113 VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0; 114 #define V_icmpmaskfake VNET(icmpmaskfake) 115 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW, 116 &VNET_NAME(icmpmaskfake), 0, 117 "Fake reply to ICMP Address Mask Request packets"); 118 119 VNET_DEFINE(int, drop_redirect) = 0; 120 #define V_drop_redirect VNET(drop_redirect) 121 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 122 &VNET_NAME(drop_redirect), 0, 123 "Ignore ICMP redirects"); 124 125 VNET_DEFINE_STATIC(int, log_redirect) = 0; 126 #define V_log_redirect VNET(log_redirect) 127 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW, 128 &VNET_NAME(log_redirect), 0, 129 "Log ICMP redirects to the console"); 130 131 VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]); 132 #define V_reply_src VNET(reply_src) 133 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW, 134 &VNET_NAME(reply_src), IFNAMSIZ, 135 "ICMP reply source for non-local packets"); 136 137 VNET_DEFINE_STATIC(int, icmp_rfi) = 0; 138 #define V_icmp_rfi VNET(icmp_rfi) 139 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW, 140 &VNET_NAME(icmp_rfi), 0, 141 "ICMP reply from incoming interface for non-local packets"); 142 /* Router requirements RFC 1812 section 4.3.2.3 requires 576 - 28. */ 143 VNET_DEFINE_STATIC(int, icmp_quotelen) = 548; 144 #define V_icmp_quotelen VNET(icmp_quotelen) 145 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW, 146 &VNET_NAME(icmp_quotelen), 0, 147 "Number of bytes from original packet to quote in ICMP reply"); 148 149 VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0; 150 #define V_icmpbmcastecho VNET(icmpbmcastecho) 151 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 152 &VNET_NAME(icmpbmcastecho), 0, 153 "Reply to multicast ICMP Echo Request and Timestamp packets"); 154 155 VNET_DEFINE_STATIC(int, icmptstamprepl) = 1; 156 #define V_icmptstamprepl VNET(icmptstamprepl) 157 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 158 &VNET_NAME(icmptstamprepl), 0, 159 "Respond to ICMP Timestamp packets"); 160 161 #ifdef ICMPPRINTFS 162 int icmpprintfs = 0; 163 #endif 164 165 static void icmp_reflect(struct mbuf *); 166 static void icmp_send(struct mbuf *, struct mbuf *); 167 168 extern struct protosw inetsw[]; 169 170 /* 171 * Kernel module interface for updating icmpstat. The argument is an index 172 * into icmpstat treated as an array of u_long. While this encodes the 173 * general layout of icmpstat into the caller, it doesn't encode its 174 * location, so that future changes to add, for example, per-CPU stats 175 * support won't cause binary compatibility problems for kernel modules. 176 */ 177 void 178 kmod_icmpstat_inc(int statnum) 179 { 180 181 counter_u64_add(VNET(icmpstat)[statnum], 1); 182 } 183 184 /* 185 * Generate an error packet of type error 186 * in response to bad packet ip. 187 */ 188 void 189 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 190 { 191 struct ip *oip, *nip; 192 struct icmp *icp; 193 struct mbuf *m; 194 unsigned icmplen, icmpelen, nlen, oiphlen; 195 196 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", 197 __func__)); 198 199 if (type != ICMP_REDIRECT) 200 ICMPSTAT_INC(icps_error); 201 /* 202 * Don't send error: 203 * if the original packet was encrypted. 204 * if not the first fragment of message. 205 * in response to a multicast or broadcast packet. 206 * if the old packet protocol was an ICMP error message. 207 */ 208 if (n->m_flags & M_DECRYPTED) 209 goto freeit; 210 if (n->m_flags & (M_BCAST|M_MCAST)) 211 goto freeit; 212 213 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */ 214 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) 215 goto freeit; 216 oip = mtod(n, struct ip *); 217 oiphlen = oip->ip_hl << 2; 218 if (n->m_len < oiphlen + ICMP_MINLEN) 219 goto freeit; 220 #ifdef ICMPPRINTFS 221 if (icmpprintfs) 222 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 223 #endif 224 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 225 goto freeit; 226 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 227 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + 228 oiphlen))->icmp_type)) { 229 ICMPSTAT_INC(icps_oldicmp); 230 goto freeit; 231 } 232 /* 233 * Calculate length to quote from original packet and 234 * prevent the ICMP mbuf from overflowing. 235 * Unfortunately this is non-trivial since ip_forward() 236 * sends us truncated packets. 237 */ 238 nlen = m_length(n, NULL); 239 if (oip->ip_p == IPPROTO_TCP) { 240 struct tcphdr *th; 241 int tcphlen; 242 243 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 244 n->m_next == NULL) 245 goto stdreply; 246 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 247 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL) 248 goto freeit; 249 oip = mtod(n, struct ip *); 250 th = mtodo(n, oiphlen); 251 tcphlen = th->th_off << 2; 252 if (tcphlen < sizeof(struct tcphdr)) 253 goto freeit; 254 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 255 goto freeit; 256 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 257 goto stdreply; 258 if (n->m_len < oiphlen + tcphlen && 259 (n = m_pullup(n, oiphlen + tcphlen)) == NULL) 260 goto freeit; 261 icmpelen = max(tcphlen, min(V_icmp_quotelen, 262 ntohs(oip->ip_len) - oiphlen)); 263 } else if (oip->ip_p == IPPROTO_SCTP) { 264 struct sctphdr *sh; 265 struct sctp_chunkhdr *ch; 266 267 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 268 goto stdreply; 269 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 270 n->m_next == NULL) 271 goto stdreply; 272 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 273 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 274 goto freeit; 275 oip = mtod(n, struct ip *); 276 icmpelen = max(sizeof(struct sctphdr), 277 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 278 sh = mtodo(n, oiphlen); 279 if (ntohl(sh->v_tag) == 0 && 280 ntohs(oip->ip_len) >= oiphlen + 281 sizeof(struct sctphdr) + 8 && 282 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 283 n->m_next != NULL)) { 284 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 285 (n = m_pullup(n, oiphlen + 286 sizeof(struct sctphdr) + 8)) == NULL) 287 goto freeit; 288 oip = mtod(n, struct ip *); 289 sh = mtodo(n, oiphlen); 290 ch = (struct sctp_chunkhdr *)(sh + 1); 291 if (ch->chunk_type == SCTP_INITIATION) { 292 icmpelen = max(sizeof(struct sctphdr) + 8, 293 min(V_icmp_quotelen, ntohs(oip->ip_len) - 294 oiphlen)); 295 } 296 } 297 } else 298 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 299 oiphlen)); 300 301 icmplen = min(oiphlen + icmpelen, nlen); 302 if (icmplen < sizeof(struct ip)) 303 goto freeit; 304 305 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 306 m = m_gethdr(M_NOWAIT, MT_DATA); 307 else 308 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 309 if (m == NULL) 310 goto freeit; 311 #ifdef MAC 312 mac_netinet_icmp_reply(n, m); 313 #endif 314 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 315 sizeof(struct ip) - ICMP_MINLEN); 316 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen); 317 m->m_data += sizeof(struct ip); 318 m->m_len = ICMP_MINLEN + icmplen; 319 320 /* XXX MRT make the outgoing packet use the same FIB 321 * that was associated with the incoming packet 322 */ 323 M_SETFIB(m, M_GETFIB(n)); 324 icp = mtod(m, struct icmp *); 325 ICMPSTAT_INC(icps_outhist[type]); 326 icp->icmp_type = type; 327 if (type == ICMP_REDIRECT) 328 icp->icmp_gwaddr.s_addr = dest; 329 else { 330 icp->icmp_void = 0; 331 /* 332 * The following assignments assume an overlay with the 333 * just zeroed icmp_void field. 334 */ 335 if (type == ICMP_PARAMPROB) { 336 icp->icmp_pptr = code; 337 code = 0; 338 } else if (type == ICMP_UNREACH && 339 code == ICMP_UNREACH_NEEDFRAG && mtu) { 340 icp->icmp_nextmtu = htons(mtu); 341 } 342 } 343 icp->icmp_code = code; 344 345 /* 346 * Copy the quotation into ICMP message and 347 * convert quoted IP header back to network representation. 348 */ 349 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 350 nip = &icp->icmp_ip; 351 352 /* 353 * Set up ICMP message mbuf and copy old IP header (without options 354 * in front of ICMP message. 355 * If the original mbuf was meant to bypass the firewall, the error 356 * reply should bypass as well. 357 */ 358 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 359 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip), 360 ("insufficient space for ip header")); 361 m->m_data -= sizeof(struct ip); 362 m->m_len += sizeof(struct ip); 363 m->m_pkthdr.len = m->m_len; 364 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 365 nip = mtod(m, struct ip *); 366 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 367 nip->ip_len = htons(m->m_len); 368 nip->ip_v = IPVERSION; 369 nip->ip_hl = 5; 370 nip->ip_p = IPPROTO_ICMP; 371 nip->ip_tos = 0; 372 nip->ip_off = 0; 373 icmp_reflect(m); 374 375 freeit: 376 m_freem(n); 377 } 378 379 /* 380 * Process a received ICMP message. 381 */ 382 int 383 icmp_input(struct mbuf **mp, int *offp, int proto) 384 { 385 struct icmp *icp; 386 struct in_ifaddr *ia; 387 struct mbuf *m = *mp; 388 struct ip *ip = mtod(m, struct ip *); 389 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 390 int hlen = *offp; 391 int icmplen = ntohs(ip->ip_len) - *offp; 392 int i, code; 393 void (*ctlfunc)(int, struct sockaddr *, void *); 394 int fibnum; 395 396 *mp = NULL; 397 398 /* 399 * Locate icmp structure in mbuf, and check 400 * that not corrupted and of at least minimum length. 401 */ 402 #ifdef ICMPPRINTFS 403 if (icmpprintfs) { 404 char srcbuf[INET_ADDRSTRLEN]; 405 char dstbuf[INET_ADDRSTRLEN]; 406 407 printf("icmp_input from %s to %s, len %d\n", 408 inet_ntoa_r(ip->ip_src, srcbuf), 409 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 410 } 411 #endif 412 NET_EPOCH_ENTER(); 413 if (icmplen < ICMP_MINLEN) { 414 ICMPSTAT_INC(icps_tooshort); 415 goto freeit; 416 } 417 i = hlen + min(icmplen, ICMP_ADVLENMIN); 418 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 419 ICMPSTAT_INC(icps_tooshort); 420 NET_EPOCH_EXIT(); 421 return (IPPROTO_DONE); 422 } 423 ip = mtod(m, struct ip *); 424 m->m_len -= hlen; 425 m->m_data += hlen; 426 icp = mtod(m, struct icmp *); 427 if (in_cksum(m, icmplen)) { 428 ICMPSTAT_INC(icps_checksum); 429 goto freeit; 430 } 431 m->m_len += hlen; 432 m->m_data -= hlen; 433 434 #ifdef ICMPPRINTFS 435 if (icmpprintfs) 436 printf("icmp_input, type %d code %d\n", icp->icmp_type, 437 icp->icmp_code); 438 #endif 439 440 /* 441 * Message type specific processing. 442 */ 443 if (icp->icmp_type > ICMP_MAXTYPE) 444 goto raw; 445 446 /* Initialize */ 447 bzero(&icmpsrc, sizeof(icmpsrc)); 448 icmpsrc.sin_len = sizeof(struct sockaddr_in); 449 icmpsrc.sin_family = AF_INET; 450 bzero(&icmpdst, sizeof(icmpdst)); 451 icmpdst.sin_len = sizeof(struct sockaddr_in); 452 icmpdst.sin_family = AF_INET; 453 bzero(&icmpgw, sizeof(icmpgw)); 454 icmpgw.sin_len = sizeof(struct sockaddr_in); 455 icmpgw.sin_family = AF_INET; 456 457 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 458 code = icp->icmp_code; 459 switch (icp->icmp_type) { 460 461 case ICMP_UNREACH: 462 switch (code) { 463 case ICMP_UNREACH_NET: 464 case ICMP_UNREACH_HOST: 465 case ICMP_UNREACH_SRCFAIL: 466 case ICMP_UNREACH_NET_UNKNOWN: 467 case ICMP_UNREACH_HOST_UNKNOWN: 468 case ICMP_UNREACH_ISOLATED: 469 case ICMP_UNREACH_TOSNET: 470 case ICMP_UNREACH_TOSHOST: 471 case ICMP_UNREACH_HOST_PRECEDENCE: 472 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 473 code = PRC_UNREACH_NET; 474 break; 475 476 case ICMP_UNREACH_NEEDFRAG: 477 code = PRC_MSGSIZE; 478 break; 479 480 /* 481 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 482 * Treat subcodes 2,3 as immediate RST 483 */ 484 case ICMP_UNREACH_PROTOCOL: 485 code = PRC_UNREACH_PROTOCOL; 486 break; 487 case ICMP_UNREACH_PORT: 488 code = PRC_UNREACH_PORT; 489 break; 490 491 case ICMP_UNREACH_NET_PROHIB: 492 case ICMP_UNREACH_HOST_PROHIB: 493 case ICMP_UNREACH_FILTER_PROHIB: 494 code = PRC_UNREACH_ADMIN_PROHIB; 495 break; 496 497 default: 498 goto badcode; 499 } 500 goto deliver; 501 502 case ICMP_TIMXCEED: 503 if (code > 1) 504 goto badcode; 505 code += PRC_TIMXCEED_INTRANS; 506 goto deliver; 507 508 case ICMP_PARAMPROB: 509 if (code > 1) 510 goto badcode; 511 code = PRC_PARAMPROB; 512 deliver: 513 /* 514 * Problem with datagram; advise higher level routines. 515 */ 516 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 517 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 518 ICMPSTAT_INC(icps_badlen); 519 goto freeit; 520 } 521 /* Discard ICMP's in response to multicast packets */ 522 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 523 goto badcode; 524 #ifdef ICMPPRINTFS 525 if (icmpprintfs) 526 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 527 #endif 528 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 529 /* 530 * XXX if the packet contains [IPv4 AH TCP], we can't make a 531 * notification to TCP layer. 532 */ 533 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 534 ip_stripoptions(m); 535 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 536 /* This should actually not happen */ 537 ICMPSTAT_INC(icps_tooshort); 538 NET_EPOCH_EXIT(); 539 return (IPPROTO_DONE); 540 } 541 ip = mtod(m, struct ip *); 542 icp = (struct icmp *)(ip + 1); 543 /* 544 * The upper layer handler can rely on: 545 * - The outer IP header has no options. 546 * - The outer IP header, the ICMP header, the inner IP header, 547 * and the first n bytes of the inner payload are contiguous. 548 * n is at least 8, but might be larger based on 549 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 550 */ 551 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 552 if (ctlfunc) 553 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 554 (void *)&icp->icmp_ip); 555 break; 556 557 badcode: 558 ICMPSTAT_INC(icps_badcode); 559 break; 560 561 case ICMP_ECHO: 562 if (!V_icmpbmcastecho 563 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 564 ICMPSTAT_INC(icps_bmcastecho); 565 break; 566 } 567 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 568 goto freeit; 569 icp->icmp_type = ICMP_ECHOREPLY; 570 goto reflect; 571 572 case ICMP_TSTAMP: 573 if (V_icmptstamprepl == 0) 574 break; 575 if (!V_icmpbmcastecho 576 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 577 ICMPSTAT_INC(icps_bmcasttstamp); 578 break; 579 } 580 if (icmplen < ICMP_TSLEN) { 581 ICMPSTAT_INC(icps_badlen); 582 break; 583 } 584 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 585 goto freeit; 586 icp->icmp_type = ICMP_TSTAMPREPLY; 587 icp->icmp_rtime = iptime(); 588 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 589 goto reflect; 590 591 case ICMP_MASKREQ: 592 if (V_icmpmaskrepl == 0) 593 break; 594 /* 595 * We are not able to respond with all ones broadcast 596 * unless we receive it over a point-to-point interface. 597 */ 598 if (icmplen < ICMP_MASKLEN) 599 break; 600 switch (ip->ip_dst.s_addr) { 601 602 case INADDR_BROADCAST: 603 case INADDR_ANY: 604 icmpdst.sin_addr = ip->ip_src; 605 break; 606 607 default: 608 icmpdst.sin_addr = ip->ip_dst; 609 } 610 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 611 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 612 if (ia == NULL) 613 break; 614 if (ia->ia_ifp == NULL) 615 break; 616 icp->icmp_type = ICMP_MASKREPLY; 617 if (V_icmpmaskfake == 0) 618 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 619 else 620 icp->icmp_mask = V_icmpmaskfake; 621 if (ip->ip_src.s_addr == 0) { 622 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 623 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 624 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 625 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 626 } 627 reflect: 628 ICMPSTAT_INC(icps_reflect); 629 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 630 icmp_reflect(m); 631 NET_EPOCH_EXIT(); 632 return (IPPROTO_DONE); 633 634 case ICMP_REDIRECT: 635 if (V_log_redirect) { 636 u_long src, dst, gw; 637 638 src = ntohl(ip->ip_src.s_addr); 639 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 640 gw = ntohl(icp->icmp_gwaddr.s_addr); 641 printf("icmp redirect from %d.%d.%d.%d: " 642 "%d.%d.%d.%d => %d.%d.%d.%d\n", 643 (int)(src >> 24), (int)((src >> 16) & 0xff), 644 (int)((src >> 8) & 0xff), (int)(src & 0xff), 645 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 646 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 647 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 648 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 649 } 650 /* 651 * RFC1812 says we must ignore ICMP redirects if we 652 * are acting as router. 653 */ 654 if (V_drop_redirect || V_ipforwarding) 655 break; 656 if (code > 3) 657 goto badcode; 658 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 659 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 660 ICMPSTAT_INC(icps_badlen); 661 break; 662 } 663 /* 664 * Short circuit routing redirects to force 665 * immediate change in the kernel's routing 666 * tables. The message is also handed to anyone 667 * listening on a raw socket (e.g. the routing 668 * daemon for use in updating its tables). 669 */ 670 icmpgw.sin_addr = ip->ip_src; 671 icmpdst.sin_addr = icp->icmp_gwaddr; 672 #ifdef ICMPPRINTFS 673 if (icmpprintfs) { 674 char dstbuf[INET_ADDRSTRLEN]; 675 char gwbuf[INET_ADDRSTRLEN]; 676 677 printf("redirect dst %s to %s\n", 678 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 679 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 680 } 681 #endif 682 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 683 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 684 in_rtredirect((struct sockaddr *)&icmpsrc, 685 (struct sockaddr *)&icmpdst, 686 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 687 (struct sockaddr *)&icmpgw, fibnum); 688 } 689 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 690 break; 691 692 /* 693 * No kernel processing for the following; 694 * just fall through to send to raw listener. 695 */ 696 case ICMP_ECHOREPLY: 697 case ICMP_ROUTERADVERT: 698 case ICMP_ROUTERSOLICIT: 699 case ICMP_TSTAMPREPLY: 700 case ICMP_IREQREPLY: 701 case ICMP_MASKREPLY: 702 case ICMP_SOURCEQUENCH: 703 default: 704 break; 705 } 706 707 raw: 708 NET_EPOCH_EXIT(); 709 *mp = m; 710 rip_input(mp, offp, proto); 711 return (IPPROTO_DONE); 712 713 freeit: 714 NET_EPOCH_EXIT(); 715 m_freem(m); 716 return (IPPROTO_DONE); 717 } 718 719 /* 720 * Reflect the ip packet back to the source 721 */ 722 static void 723 icmp_reflect(struct mbuf *m) 724 { 725 struct rm_priotracker in_ifa_tracker; 726 struct ip *ip = mtod(m, struct ip *); 727 struct ifaddr *ifa; 728 struct ifnet *ifp; 729 struct in_ifaddr *ia; 730 struct in_addr t; 731 struct nhop4_extended nh_ext; 732 struct mbuf *opts = NULL; 733 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 734 735 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 736 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 737 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 738 m_freem(m); /* Bad return address */ 739 ICMPSTAT_INC(icps_badaddr); 740 goto done; /* Ip_output() will check for broadcast */ 741 } 742 743 t = ip->ip_dst; 744 ip->ip_dst = ip->ip_src; 745 746 /* 747 * Source selection for ICMP replies: 748 * 749 * If the incoming packet was addressed directly to one of our 750 * own addresses, use dst as the src for the reply. 751 */ 752 IN_IFADDR_RLOCK(&in_ifa_tracker); 753 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 754 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 755 t = IA_SIN(ia)->sin_addr; 756 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 757 goto match; 758 } 759 } 760 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 761 762 /* 763 * If the incoming packet was addressed to one of our broadcast 764 * addresses, use the first non-broadcast address which corresponds 765 * to the incoming interface. 766 */ 767 ifp = m->m_pkthdr.rcvif; 768 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 769 IF_ADDR_RLOCK(ifp); 770 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 771 if (ifa->ifa_addr->sa_family != AF_INET) 772 continue; 773 ia = ifatoia(ifa); 774 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 775 t.s_addr) { 776 t = IA_SIN(ia)->sin_addr; 777 IF_ADDR_RUNLOCK(ifp); 778 goto match; 779 } 780 } 781 IF_ADDR_RUNLOCK(ifp); 782 } 783 /* 784 * If the packet was transiting through us, use the address of 785 * the interface the packet came through in. If that interface 786 * doesn't have a suitable IP address, the normal selection 787 * criteria apply. 788 */ 789 if (V_icmp_rfi && ifp != NULL) { 790 IF_ADDR_RLOCK(ifp); 791 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 792 if (ifa->ifa_addr->sa_family != AF_INET) 793 continue; 794 ia = ifatoia(ifa); 795 t = IA_SIN(ia)->sin_addr; 796 IF_ADDR_RUNLOCK(ifp); 797 goto match; 798 } 799 IF_ADDR_RUNLOCK(ifp); 800 } 801 /* 802 * If the incoming packet was not addressed directly to us, use 803 * designated interface for icmp replies specified by sysctl 804 * net.inet.icmp.reply_src (default not set). Otherwise continue 805 * with normal source selection. 806 */ 807 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 808 IF_ADDR_RLOCK(ifp); 809 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 810 if (ifa->ifa_addr->sa_family != AF_INET) 811 continue; 812 ia = ifatoia(ifa); 813 t = IA_SIN(ia)->sin_addr; 814 IF_ADDR_RUNLOCK(ifp); 815 goto match; 816 } 817 IF_ADDR_RUNLOCK(ifp); 818 } 819 /* 820 * If the packet was transiting through us, use the address of 821 * the interface that is the closest to the packet source. 822 * When we don't have a route back to the packet source, stop here 823 * and drop the packet. 824 */ 825 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 826 m_freem(m); 827 ICMPSTAT_INC(icps_noroute); 828 goto done; 829 } 830 t = nh_ext.nh_src; 831 match: 832 #ifdef MAC 833 mac_netinet_icmp_replyinplace(m); 834 #endif 835 ip->ip_src = t; 836 ip->ip_ttl = V_ip_defttl; 837 838 if (optlen > 0) { 839 u_char *cp; 840 int opt, cnt; 841 u_int len; 842 843 /* 844 * Retrieve any source routing from the incoming packet; 845 * add on any record-route or timestamp options. 846 */ 847 cp = (u_char *) (ip + 1); 848 if ((opts = ip_srcroute(m)) == NULL && 849 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 850 opts->m_len = sizeof(struct in_addr); 851 mtod(opts, struct in_addr *)->s_addr = 0; 852 } 853 if (opts) { 854 #ifdef ICMPPRINTFS 855 if (icmpprintfs) 856 printf("icmp_reflect optlen %d rt %d => ", 857 optlen, opts->m_len); 858 #endif 859 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 860 opt = cp[IPOPT_OPTVAL]; 861 if (opt == IPOPT_EOL) 862 break; 863 if (opt == IPOPT_NOP) 864 len = 1; 865 else { 866 if (cnt < IPOPT_OLEN + sizeof(*cp)) 867 break; 868 len = cp[IPOPT_OLEN]; 869 if (len < IPOPT_OLEN + sizeof(*cp) || 870 len > cnt) 871 break; 872 } 873 /* 874 * Should check for overflow, but it "can't happen" 875 */ 876 if (opt == IPOPT_RR || opt == IPOPT_TS || 877 opt == IPOPT_SECURITY) { 878 bcopy((caddr_t)cp, 879 mtod(opts, caddr_t) + opts->m_len, len); 880 opts->m_len += len; 881 } 882 } 883 /* Terminate & pad, if necessary */ 884 cnt = opts->m_len % 4; 885 if (cnt) { 886 for (; cnt < 4; cnt++) { 887 *(mtod(opts, caddr_t) + opts->m_len) = 888 IPOPT_EOL; 889 opts->m_len++; 890 } 891 } 892 #ifdef ICMPPRINTFS 893 if (icmpprintfs) 894 printf("%d\n", opts->m_len); 895 #endif 896 } 897 ip_stripoptions(m); 898 } 899 m_tag_delete_nonpersistent(m); 900 m->m_flags &= ~(M_BCAST|M_MCAST); 901 icmp_send(m, opts); 902 done: 903 if (opts) 904 (void)m_free(opts); 905 } 906 907 /* 908 * Send an icmp packet back to the ip level, 909 * after supplying a checksum. 910 */ 911 static void 912 icmp_send(struct mbuf *m, struct mbuf *opts) 913 { 914 struct ip *ip = mtod(m, struct ip *); 915 int hlen; 916 struct icmp *icp; 917 918 hlen = ip->ip_hl << 2; 919 m->m_data += hlen; 920 m->m_len -= hlen; 921 icp = mtod(m, struct icmp *); 922 icp->icmp_cksum = 0; 923 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 924 m->m_data -= hlen; 925 m->m_len += hlen; 926 m->m_pkthdr.rcvif = (struct ifnet *)0; 927 #ifdef ICMPPRINTFS 928 if (icmpprintfs) { 929 char dstbuf[INET_ADDRSTRLEN]; 930 char srcbuf[INET_ADDRSTRLEN]; 931 932 printf("icmp_send dst %s src %s\n", 933 inet_ntoa_r(ip->ip_dst, dstbuf), 934 inet_ntoa_r(ip->ip_src, srcbuf)); 935 } 936 #endif 937 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 938 } 939 940 /* 941 * Return milliseconds since 00:00 UTC in network format. 942 */ 943 uint32_t 944 iptime(void) 945 { 946 struct timeval atv; 947 u_long t; 948 949 getmicrotime(&atv); 950 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 951 return (htonl(t)); 952 } 953 954 /* 955 * Return the next larger or smaller MTU plateau (table from RFC 1191) 956 * given current value MTU. If DIR is less than zero, a larger plateau 957 * is returned; otherwise, a smaller value is returned. 958 */ 959 int 960 ip_next_mtu(int mtu, int dir) 961 { 962 static int mtutab[] = { 963 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 964 296, 68, 0 965 }; 966 int i, size; 967 968 size = (sizeof mtutab) / (sizeof mtutab[0]); 969 if (dir >= 0) { 970 for (i = 0; i < size; i++) 971 if (mtu > mtutab[i]) 972 return mtutab[i]; 973 } else { 974 for (i = size - 1; i >= 0; i--) 975 if (mtu < mtutab[i]) 976 return mtutab[i]; 977 if (mtu == mtutab[0]) 978 return mtutab[0]; 979 } 980 return 0; 981 } 982 #endif /* INET */ 983 984 985 /* 986 * badport_bandlim() - check for ICMP bandwidth limit 987 * 988 * Return 0 if it is ok to send an ICMP error response, -1 if we have 989 * hit our bandwidth limit and it is not ok. 990 * 991 * If icmplim is <= 0, the feature is disabled and 0 is returned. 992 * 993 * For now we separate the TCP and UDP subsystems w/ different 'which' 994 * values. We may eventually remove this separation (and simplify the 995 * code further). 996 * 997 * Note that the printing of the error message is delayed so we can 998 * properly print the icmp error rate that the system was trying to do 999 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 1000 * the 'final' error, but it doesn't make sense to solve the printing 1001 * delay with more complex code. 1002 */ 1003 struct icmp_rate { 1004 const char *descr; 1005 struct counter_rate cr; 1006 }; 1007 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 1008 { "icmp unreach response" }, 1009 { "icmp ping response" }, 1010 { "icmp tstamp response" }, 1011 { "closed port RST response" }, 1012 { "open port RST response" }, 1013 { "icmp6 unreach response" }, 1014 { "sctp ootb response" } 1015 }; 1016 #define V_icmp_rates VNET(icmp_rates) 1017 1018 static void 1019 icmp_bandlimit_init(void) 1020 { 1021 1022 for (int i = 0; i < BANDLIM_MAX; i++) { 1023 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 1024 V_icmp_rates[i].cr.cr_ticks = ticks; 1025 } 1026 } 1027 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1028 icmp_bandlimit_init, NULL); 1029 1030 static void 1031 icmp_bandlimit_uninit(void) 1032 { 1033 1034 for (int i = 0; i < BANDLIM_MAX; i++) 1035 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1036 } 1037 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1038 icmp_bandlimit_uninit, NULL); 1039 1040 int 1041 badport_bandlim(int which) 1042 { 1043 int64_t pps; 1044 1045 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1046 return (0); 1047 1048 KASSERT(which >= 0 && which < BANDLIM_MAX, 1049 ("%s: which %d", __func__, which)); 1050 1051 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1052 if (pps == -1) 1053 return (-1); 1054 if (pps > 0 && V_icmplim_output) 1055 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1056 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1057 return (0); 1058 }
Cache object: 89cd6453fb945b74f9f85f54435dfc15
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