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("$FreeBSD$"); 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 VNET_DEFINE_STATIC(int, error_keeptags) = 0; 162 #define V_error_keeptags VNET(error_keeptags) 163 SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW, 164 &VNET_NAME(error_keeptags), 0, 165 "ICMP error response keeps copy of mbuf_tags of original packet"); 166 167 #ifdef ICMPPRINTFS 168 int icmpprintfs = 0; 169 #endif 170 171 static void icmp_reflect(struct mbuf *); 172 static void icmp_send(struct mbuf *, struct mbuf *); 173 174 extern struct protosw inetsw[]; 175 176 /* 177 * Kernel module interface for updating icmpstat. The argument is an index 178 * into icmpstat treated as an array of u_long. While this encodes the 179 * general layout of icmpstat into the caller, it doesn't encode its 180 * location, so that future changes to add, for example, per-CPU stats 181 * support won't cause binary compatibility problems for kernel modules. 182 */ 183 void 184 kmod_icmpstat_inc(int statnum) 185 { 186 187 counter_u64_add(VNET(icmpstat)[statnum], 1); 188 } 189 190 /* 191 * Generate an error packet of type error 192 * in response to bad packet ip. 193 */ 194 void 195 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 196 { 197 struct ip *oip, *nip; 198 struct icmp *icp; 199 struct mbuf *m; 200 unsigned icmplen, icmpelen, nlen, oiphlen; 201 202 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", 203 __func__)); 204 205 if (type != ICMP_REDIRECT) 206 ICMPSTAT_INC(icps_error); 207 /* 208 * Don't send error: 209 * if the original packet was encrypted. 210 * if not the first fragment of message. 211 * in response to a multicast or broadcast packet. 212 * if the old packet protocol was an ICMP error message. 213 */ 214 if (n->m_flags & M_DECRYPTED) 215 goto freeit; 216 if (n->m_flags & (M_BCAST|M_MCAST)) 217 goto freeit; 218 219 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */ 220 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) 221 goto freeit; 222 oip = mtod(n, struct ip *); 223 oiphlen = oip->ip_hl << 2; 224 if (n->m_len < oiphlen + ICMP_MINLEN) 225 goto freeit; 226 #ifdef ICMPPRINTFS 227 if (icmpprintfs) 228 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 229 #endif 230 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 231 goto freeit; 232 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 233 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + 234 oiphlen))->icmp_type)) { 235 ICMPSTAT_INC(icps_oldicmp); 236 goto freeit; 237 } 238 /* 239 * Calculate length to quote from original packet and 240 * prevent the ICMP mbuf from overflowing. 241 * Unfortunately this is non-trivial since ip_forward() 242 * sends us truncated packets. 243 */ 244 nlen = m_length(n, NULL); 245 if (oip->ip_p == IPPROTO_TCP) { 246 struct tcphdr *th; 247 int tcphlen; 248 249 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 250 n->m_next == NULL) 251 goto stdreply; 252 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 253 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL) 254 goto freeit; 255 oip = mtod(n, struct ip *); 256 th = mtodo(n, oiphlen); 257 tcphlen = th->th_off << 2; 258 if (tcphlen < sizeof(struct tcphdr)) 259 goto freeit; 260 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 261 goto freeit; 262 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 263 goto stdreply; 264 if (n->m_len < oiphlen + tcphlen && 265 (n = m_pullup(n, oiphlen + tcphlen)) == NULL) 266 goto freeit; 267 icmpelen = max(tcphlen, min(V_icmp_quotelen, 268 ntohs(oip->ip_len) - oiphlen)); 269 } else if (oip->ip_p == IPPROTO_SCTP) { 270 struct sctphdr *sh; 271 struct sctp_chunkhdr *ch; 272 273 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 274 goto stdreply; 275 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 276 n->m_next == NULL) 277 goto stdreply; 278 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 279 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 280 goto freeit; 281 oip = mtod(n, struct ip *); 282 icmpelen = max(sizeof(struct sctphdr), 283 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 284 sh = mtodo(n, oiphlen); 285 if (ntohl(sh->v_tag) == 0 && 286 ntohs(oip->ip_len) >= oiphlen + 287 sizeof(struct sctphdr) + 8 && 288 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 289 n->m_next != NULL)) { 290 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 291 (n = m_pullup(n, oiphlen + 292 sizeof(struct sctphdr) + 8)) == NULL) 293 goto freeit; 294 oip = mtod(n, struct ip *); 295 sh = mtodo(n, oiphlen); 296 ch = (struct sctp_chunkhdr *)(sh + 1); 297 if (ch->chunk_type == SCTP_INITIATION) { 298 icmpelen = max(sizeof(struct sctphdr) + 8, 299 min(V_icmp_quotelen, ntohs(oip->ip_len) - 300 oiphlen)); 301 } 302 } 303 } else 304 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 305 oiphlen)); 306 307 icmplen = min(oiphlen + icmpelen, nlen); 308 if (icmplen < sizeof(struct ip)) 309 goto freeit; 310 311 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 312 m = m_gethdr(M_NOWAIT, MT_DATA); 313 else 314 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 315 if (m == NULL) 316 goto freeit; 317 #ifdef MAC 318 mac_netinet_icmp_reply(n, m); 319 #endif 320 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 321 sizeof(struct ip) - ICMP_MINLEN); 322 m_align(m, ICMP_MINLEN + icmplen); 323 m->m_len = ICMP_MINLEN + icmplen; 324 325 /* XXX MRT make the outgoing packet use the same FIB 326 * that was associated with the incoming packet 327 */ 328 M_SETFIB(m, M_GETFIB(n)); 329 icp = mtod(m, struct icmp *); 330 ICMPSTAT_INC(icps_outhist[type]); 331 icp->icmp_type = type; 332 if (type == ICMP_REDIRECT) 333 icp->icmp_gwaddr.s_addr = dest; 334 else { 335 icp->icmp_void = 0; 336 /* 337 * The following assignments assume an overlay with the 338 * just zeroed icmp_void field. 339 */ 340 if (type == ICMP_PARAMPROB) { 341 icp->icmp_pptr = code; 342 code = 0; 343 } else if (type == ICMP_UNREACH && 344 code == ICMP_UNREACH_NEEDFRAG && mtu) { 345 icp->icmp_nextmtu = htons(mtu); 346 } 347 } 348 icp->icmp_code = code; 349 350 /* 351 * Copy the quotation into ICMP message and 352 * convert quoted IP header back to network representation. 353 */ 354 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 355 nip = &icp->icmp_ip; 356 357 /* 358 * Set up ICMP message mbuf and copy old IP header (without options 359 * in front of ICMP message. 360 * If the original mbuf was meant to bypass the firewall, the error 361 * reply should bypass as well. 362 */ 363 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 364 m->m_data -= sizeof(struct ip); 365 m->m_len += sizeof(struct ip); 366 m->m_pkthdr.len = m->m_len; 367 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 368 nip = mtod(m, struct ip *); 369 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 370 nip->ip_len = htons(m->m_len); 371 nip->ip_v = IPVERSION; 372 nip->ip_hl = 5; 373 nip->ip_p = IPPROTO_ICMP; 374 nip->ip_tos = 0; 375 nip->ip_off = 0; 376 377 if (V_error_keeptags) 378 m_tag_copy_chain(m, n, M_NOWAIT); 379 380 icmp_reflect(m); 381 382 freeit: 383 m_freem(n); 384 } 385 386 /* 387 * Process a received ICMP message. 388 */ 389 int 390 icmp_input(struct mbuf **mp, int *offp, int proto) 391 { 392 struct icmp *icp; 393 struct in_ifaddr *ia; 394 struct mbuf *m = *mp; 395 struct ip *ip = mtod(m, struct ip *); 396 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 397 int hlen = *offp; 398 int icmplen = ntohs(ip->ip_len) - *offp; 399 int i, code; 400 void (*ctlfunc)(int, struct sockaddr *, void *); 401 int fibnum; 402 403 *mp = NULL; 404 405 /* 406 * Locate icmp structure in mbuf, and check 407 * that not corrupted and of at least minimum length. 408 */ 409 #ifdef ICMPPRINTFS 410 if (icmpprintfs) { 411 char srcbuf[INET_ADDRSTRLEN]; 412 char dstbuf[INET_ADDRSTRLEN]; 413 414 printf("icmp_input from %s to %s, len %d\n", 415 inet_ntoa_r(ip->ip_src, srcbuf), 416 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 417 } 418 #endif 419 NET_EPOCH_ENTER(); 420 if (icmplen < ICMP_MINLEN) { 421 ICMPSTAT_INC(icps_tooshort); 422 goto freeit; 423 } 424 i = hlen + min(icmplen, ICMP_ADVLENMIN); 425 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 426 ICMPSTAT_INC(icps_tooshort); 427 NET_EPOCH_EXIT(); 428 return (IPPROTO_DONE); 429 } 430 ip = mtod(m, struct ip *); 431 m->m_len -= hlen; 432 m->m_data += hlen; 433 icp = mtod(m, struct icmp *); 434 if (in_cksum(m, icmplen)) { 435 ICMPSTAT_INC(icps_checksum); 436 goto freeit; 437 } 438 m->m_len += hlen; 439 m->m_data -= hlen; 440 441 #ifdef ICMPPRINTFS 442 if (icmpprintfs) 443 printf("icmp_input, type %d code %d\n", icp->icmp_type, 444 icp->icmp_code); 445 #endif 446 447 /* 448 * Message type specific processing. 449 */ 450 if (icp->icmp_type > ICMP_MAXTYPE) 451 goto raw; 452 453 /* Initialize */ 454 bzero(&icmpsrc, sizeof(icmpsrc)); 455 icmpsrc.sin_len = sizeof(struct sockaddr_in); 456 icmpsrc.sin_family = AF_INET; 457 bzero(&icmpdst, sizeof(icmpdst)); 458 icmpdst.sin_len = sizeof(struct sockaddr_in); 459 icmpdst.sin_family = AF_INET; 460 bzero(&icmpgw, sizeof(icmpgw)); 461 icmpgw.sin_len = sizeof(struct sockaddr_in); 462 icmpgw.sin_family = AF_INET; 463 464 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 465 code = icp->icmp_code; 466 switch (icp->icmp_type) { 467 468 case ICMP_UNREACH: 469 switch (code) { 470 case ICMP_UNREACH_NET: 471 case ICMP_UNREACH_HOST: 472 case ICMP_UNREACH_SRCFAIL: 473 case ICMP_UNREACH_NET_UNKNOWN: 474 case ICMP_UNREACH_HOST_UNKNOWN: 475 case ICMP_UNREACH_ISOLATED: 476 case ICMP_UNREACH_TOSNET: 477 case ICMP_UNREACH_TOSHOST: 478 case ICMP_UNREACH_HOST_PRECEDENCE: 479 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 480 code = PRC_UNREACH_NET; 481 break; 482 483 case ICMP_UNREACH_NEEDFRAG: 484 code = PRC_MSGSIZE; 485 break; 486 487 /* 488 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 489 * Treat subcodes 2,3 as immediate RST 490 */ 491 case ICMP_UNREACH_PROTOCOL: 492 code = PRC_UNREACH_PROTOCOL; 493 break; 494 case ICMP_UNREACH_PORT: 495 code = PRC_UNREACH_PORT; 496 break; 497 498 case ICMP_UNREACH_NET_PROHIB: 499 case ICMP_UNREACH_HOST_PROHIB: 500 case ICMP_UNREACH_FILTER_PROHIB: 501 code = PRC_UNREACH_ADMIN_PROHIB; 502 break; 503 504 default: 505 goto badcode; 506 } 507 goto deliver; 508 509 case ICMP_TIMXCEED: 510 if (code > 1) 511 goto badcode; 512 code += PRC_TIMXCEED_INTRANS; 513 goto deliver; 514 515 case ICMP_PARAMPROB: 516 if (code > 1) 517 goto badcode; 518 code = PRC_PARAMPROB; 519 deliver: 520 /* 521 * Problem with datagram; advise higher level routines. 522 */ 523 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 524 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 525 ICMPSTAT_INC(icps_badlen); 526 goto freeit; 527 } 528 /* Discard ICMP's in response to multicast packets */ 529 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 530 goto badcode; 531 #ifdef ICMPPRINTFS 532 if (icmpprintfs) 533 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 534 #endif 535 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 536 /* 537 * XXX if the packet contains [IPv4 AH TCP], we can't make a 538 * notification to TCP layer. 539 */ 540 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 541 ip_stripoptions(m); 542 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 543 /* This should actually not happen */ 544 ICMPSTAT_INC(icps_tooshort); 545 NET_EPOCH_EXIT(); 546 return (IPPROTO_DONE); 547 } 548 ip = mtod(m, struct ip *); 549 icp = (struct icmp *)(ip + 1); 550 /* 551 * The upper layer handler can rely on: 552 * - The outer IP header has no options. 553 * - The outer IP header, the ICMP header, the inner IP header, 554 * and the first n bytes of the inner payload are contiguous. 555 * n is at least 8, but might be larger based on 556 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 557 */ 558 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 559 if (ctlfunc) 560 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 561 (void *)&icp->icmp_ip); 562 break; 563 564 badcode: 565 ICMPSTAT_INC(icps_badcode); 566 break; 567 568 case ICMP_ECHO: 569 if (!V_icmpbmcastecho 570 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 571 ICMPSTAT_INC(icps_bmcastecho); 572 break; 573 } 574 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 575 goto freeit; 576 icp->icmp_type = ICMP_ECHOREPLY; 577 goto reflect; 578 579 case ICMP_TSTAMP: 580 if (V_icmptstamprepl == 0) 581 break; 582 if (!V_icmpbmcastecho 583 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 584 ICMPSTAT_INC(icps_bmcasttstamp); 585 break; 586 } 587 if (icmplen < ICMP_TSLEN) { 588 ICMPSTAT_INC(icps_badlen); 589 break; 590 } 591 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 592 goto freeit; 593 icp->icmp_type = ICMP_TSTAMPREPLY; 594 icp->icmp_rtime = iptime(); 595 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 596 goto reflect; 597 598 case ICMP_MASKREQ: 599 if (V_icmpmaskrepl == 0) 600 break; 601 /* 602 * We are not able to respond with all ones broadcast 603 * unless we receive it over a point-to-point interface. 604 */ 605 if (icmplen < ICMP_MASKLEN) 606 break; 607 switch (ip->ip_dst.s_addr) { 608 609 case INADDR_BROADCAST: 610 case INADDR_ANY: 611 icmpdst.sin_addr = ip->ip_src; 612 break; 613 614 default: 615 icmpdst.sin_addr = ip->ip_dst; 616 } 617 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 618 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 619 if (ia == NULL) 620 break; 621 if (ia->ia_ifp == NULL) 622 break; 623 icp->icmp_type = ICMP_MASKREPLY; 624 if (V_icmpmaskfake == 0) 625 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 626 else 627 icp->icmp_mask = V_icmpmaskfake; 628 if (ip->ip_src.s_addr == 0) { 629 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 630 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 631 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 632 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 633 } 634 reflect: 635 ICMPSTAT_INC(icps_reflect); 636 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 637 icmp_reflect(m); 638 NET_EPOCH_EXIT(); 639 return (IPPROTO_DONE); 640 641 case ICMP_REDIRECT: 642 if (V_log_redirect) { 643 u_long src, dst, gw; 644 645 src = ntohl(ip->ip_src.s_addr); 646 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 647 gw = ntohl(icp->icmp_gwaddr.s_addr); 648 printf("icmp redirect from %d.%d.%d.%d: " 649 "%d.%d.%d.%d => %d.%d.%d.%d\n", 650 (int)(src >> 24), (int)((src >> 16) & 0xff), 651 (int)((src >> 8) & 0xff), (int)(src & 0xff), 652 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 653 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 654 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 655 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 656 } 657 /* 658 * RFC1812 says we must ignore ICMP redirects if we 659 * are acting as router. 660 */ 661 if (V_drop_redirect || V_ipforwarding) 662 break; 663 if (code > 3) 664 goto badcode; 665 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 666 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 667 ICMPSTAT_INC(icps_badlen); 668 break; 669 } 670 /* 671 * Short circuit routing redirects to force 672 * immediate change in the kernel's routing 673 * tables. The message is also handed to anyone 674 * listening on a raw socket (e.g. the routing 675 * daemon for use in updating its tables). 676 */ 677 icmpgw.sin_addr = ip->ip_src; 678 icmpdst.sin_addr = icp->icmp_gwaddr; 679 #ifdef ICMPPRINTFS 680 if (icmpprintfs) { 681 char dstbuf[INET_ADDRSTRLEN]; 682 char gwbuf[INET_ADDRSTRLEN]; 683 684 printf("redirect dst %s to %s\n", 685 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 686 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 687 } 688 #endif 689 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 690 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 691 in_rtredirect((struct sockaddr *)&icmpsrc, 692 (struct sockaddr *)&icmpdst, 693 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 694 (struct sockaddr *)&icmpgw, fibnum); 695 } 696 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 697 break; 698 699 /* 700 * No kernel processing for the following; 701 * just fall through to send to raw listener. 702 */ 703 case ICMP_ECHOREPLY: 704 case ICMP_ROUTERADVERT: 705 case ICMP_ROUTERSOLICIT: 706 case ICMP_TSTAMPREPLY: 707 case ICMP_IREQREPLY: 708 case ICMP_MASKREPLY: 709 case ICMP_SOURCEQUENCH: 710 default: 711 break; 712 } 713 714 raw: 715 NET_EPOCH_EXIT(); 716 *mp = m; 717 rip_input(mp, offp, proto); 718 return (IPPROTO_DONE); 719 720 freeit: 721 NET_EPOCH_EXIT(); 722 m_freem(m); 723 return (IPPROTO_DONE); 724 } 725 726 /* 727 * Reflect the ip packet back to the source 728 */ 729 static void 730 icmp_reflect(struct mbuf *m) 731 { 732 struct rm_priotracker in_ifa_tracker; 733 struct ip *ip = mtod(m, struct ip *); 734 struct ifaddr *ifa; 735 struct ifnet *ifp; 736 struct in_ifaddr *ia; 737 struct in_addr t; 738 struct nhop4_extended nh_ext; 739 struct mbuf *opts = NULL; 740 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 741 742 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 743 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 744 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 745 m_freem(m); /* Bad return address */ 746 ICMPSTAT_INC(icps_badaddr); 747 goto done; /* Ip_output() will check for broadcast */ 748 } 749 750 t = ip->ip_dst; 751 ip->ip_dst = ip->ip_src; 752 753 /* 754 * Source selection for ICMP replies: 755 * 756 * If the incoming packet was addressed directly to one of our 757 * own addresses, use dst as the src for the reply. 758 */ 759 IN_IFADDR_RLOCK(&in_ifa_tracker); 760 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 761 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 762 t = IA_SIN(ia)->sin_addr; 763 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 764 goto match; 765 } 766 } 767 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 768 769 /* 770 * If the incoming packet was addressed to one of our broadcast 771 * addresses, use the first non-broadcast address which corresponds 772 * to the incoming interface. 773 */ 774 ifp = m->m_pkthdr.rcvif; 775 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 776 IF_ADDR_RLOCK(ifp); 777 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 778 if (ifa->ifa_addr->sa_family != AF_INET) 779 continue; 780 ia = ifatoia(ifa); 781 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 782 t.s_addr) { 783 t = IA_SIN(ia)->sin_addr; 784 IF_ADDR_RUNLOCK(ifp); 785 goto match; 786 } 787 } 788 IF_ADDR_RUNLOCK(ifp); 789 } 790 /* 791 * If the packet was transiting through us, use the address of 792 * the interface the packet came through in. If that interface 793 * doesn't have a suitable IP address, the normal selection 794 * criteria apply. 795 */ 796 if (V_icmp_rfi && ifp != NULL) { 797 IF_ADDR_RLOCK(ifp); 798 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 799 if (ifa->ifa_addr->sa_family != AF_INET) 800 continue; 801 ia = ifatoia(ifa); 802 t = IA_SIN(ia)->sin_addr; 803 IF_ADDR_RUNLOCK(ifp); 804 goto match; 805 } 806 IF_ADDR_RUNLOCK(ifp); 807 } 808 /* 809 * If the incoming packet was not addressed directly to us, use 810 * designated interface for icmp replies specified by sysctl 811 * net.inet.icmp.reply_src (default not set). Otherwise continue 812 * with normal source selection. 813 */ 814 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 815 IF_ADDR_RLOCK(ifp); 816 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 817 if (ifa->ifa_addr->sa_family != AF_INET) 818 continue; 819 ia = ifatoia(ifa); 820 t = IA_SIN(ia)->sin_addr; 821 IF_ADDR_RUNLOCK(ifp); 822 goto match; 823 } 824 IF_ADDR_RUNLOCK(ifp); 825 } 826 /* 827 * If the packet was transiting through us, use the address of 828 * the interface that is the closest to the packet source. 829 * When we don't have a route back to the packet source, stop here 830 * and drop the packet. 831 */ 832 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 833 m_freem(m); 834 ICMPSTAT_INC(icps_noroute); 835 goto done; 836 } 837 t = nh_ext.nh_src; 838 match: 839 #ifdef MAC 840 mac_netinet_icmp_replyinplace(m); 841 #endif 842 ip->ip_src = t; 843 ip->ip_ttl = V_ip_defttl; 844 845 if (optlen > 0) { 846 u_char *cp; 847 int opt, cnt; 848 u_int len; 849 850 /* 851 * Retrieve any source routing from the incoming packet; 852 * add on any record-route or timestamp options. 853 */ 854 cp = (u_char *) (ip + 1); 855 if ((opts = ip_srcroute(m)) == NULL && 856 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 857 opts->m_len = sizeof(struct in_addr); 858 mtod(opts, struct in_addr *)->s_addr = 0; 859 } 860 if (opts) { 861 #ifdef ICMPPRINTFS 862 if (icmpprintfs) 863 printf("icmp_reflect optlen %d rt %d => ", 864 optlen, opts->m_len); 865 #endif 866 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 867 opt = cp[IPOPT_OPTVAL]; 868 if (opt == IPOPT_EOL) 869 break; 870 if (opt == IPOPT_NOP) 871 len = 1; 872 else { 873 if (cnt < IPOPT_OLEN + sizeof(*cp)) 874 break; 875 len = cp[IPOPT_OLEN]; 876 if (len < IPOPT_OLEN + sizeof(*cp) || 877 len > cnt) 878 break; 879 } 880 /* 881 * Should check for overflow, but it "can't happen" 882 */ 883 if (opt == IPOPT_RR || opt == IPOPT_TS || 884 opt == IPOPT_SECURITY) { 885 bcopy((caddr_t)cp, 886 mtod(opts, caddr_t) + opts->m_len, len); 887 opts->m_len += len; 888 } 889 } 890 /* Terminate & pad, if necessary */ 891 cnt = opts->m_len % 4; 892 if (cnt) { 893 for (; cnt < 4; cnt++) { 894 *(mtod(opts, caddr_t) + opts->m_len) = 895 IPOPT_EOL; 896 opts->m_len++; 897 } 898 } 899 #ifdef ICMPPRINTFS 900 if (icmpprintfs) 901 printf("%d\n", opts->m_len); 902 #endif 903 } 904 ip_stripoptions(m); 905 } 906 m_tag_delete_nonpersistent(m); 907 m->m_flags &= ~(M_BCAST|M_MCAST); 908 icmp_send(m, opts); 909 done: 910 if (opts) 911 (void)m_free(opts); 912 } 913 914 /* 915 * Send an icmp packet back to the ip level, 916 * after supplying a checksum. 917 */ 918 static void 919 icmp_send(struct mbuf *m, struct mbuf *opts) 920 { 921 struct ip *ip = mtod(m, struct ip *); 922 int hlen; 923 struct icmp *icp; 924 925 hlen = ip->ip_hl << 2; 926 m->m_data += hlen; 927 m->m_len -= hlen; 928 icp = mtod(m, struct icmp *); 929 icp->icmp_cksum = 0; 930 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 931 m->m_data -= hlen; 932 m->m_len += hlen; 933 m->m_pkthdr.rcvif = (struct ifnet *)0; 934 #ifdef ICMPPRINTFS 935 if (icmpprintfs) { 936 char dstbuf[INET_ADDRSTRLEN]; 937 char srcbuf[INET_ADDRSTRLEN]; 938 939 printf("icmp_send dst %s src %s\n", 940 inet_ntoa_r(ip->ip_dst, dstbuf), 941 inet_ntoa_r(ip->ip_src, srcbuf)); 942 } 943 #endif 944 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 945 } 946 947 /* 948 * Return milliseconds since 00:00 UTC in network format. 949 */ 950 uint32_t 951 iptime(void) 952 { 953 struct timeval atv; 954 u_long t; 955 956 getmicrotime(&atv); 957 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 958 return (htonl(t)); 959 } 960 961 /* 962 * Return the next larger or smaller MTU plateau (table from RFC 1191) 963 * given current value MTU. If DIR is less than zero, a larger plateau 964 * is returned; otherwise, a smaller value is returned. 965 */ 966 int 967 ip_next_mtu(int mtu, int dir) 968 { 969 static int mtutab[] = { 970 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 971 296, 68, 0 972 }; 973 int i, size; 974 975 size = (sizeof mtutab) / (sizeof mtutab[0]); 976 if (dir >= 0) { 977 for (i = 0; i < size; i++) 978 if (mtu > mtutab[i]) 979 return mtutab[i]; 980 } else { 981 for (i = size - 1; i >= 0; i--) 982 if (mtu < mtutab[i]) 983 return mtutab[i]; 984 if (mtu == mtutab[0]) 985 return mtutab[0]; 986 } 987 return 0; 988 } 989 #endif /* INET */ 990 991 992 /* 993 * badport_bandlim() - check for ICMP bandwidth limit 994 * 995 * Return 0 if it is ok to send an ICMP error response, -1 if we have 996 * hit our bandwidth limit and it is not ok. 997 * 998 * If icmplim is <= 0, the feature is disabled and 0 is returned. 999 * 1000 * For now we separate the TCP and UDP subsystems w/ different 'which' 1001 * values. We may eventually remove this separation (and simplify the 1002 * code further). 1003 * 1004 * Note that the printing of the error message is delayed so we can 1005 * properly print the icmp error rate that the system was trying to do 1006 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 1007 * the 'final' error, but it doesn't make sense to solve the printing 1008 * delay with more complex code. 1009 */ 1010 struct icmp_rate { 1011 const char *descr; 1012 struct counter_rate cr; 1013 }; 1014 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 1015 { "icmp unreach response" }, 1016 { "icmp ping response" }, 1017 { "icmp tstamp response" }, 1018 { "closed port RST response" }, 1019 { "open port RST response" }, 1020 { "icmp6 unreach response" }, 1021 { "sctp ootb response" } 1022 }; 1023 #define V_icmp_rates VNET(icmp_rates) 1024 1025 static void 1026 icmp_bandlimit_init(void) 1027 { 1028 1029 for (int i = 0; i < BANDLIM_MAX; i++) { 1030 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 1031 V_icmp_rates[i].cr.cr_ticks = ticks; 1032 } 1033 } 1034 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1035 icmp_bandlimit_init, NULL); 1036 1037 static void 1038 icmp_bandlimit_uninit(void) 1039 { 1040 1041 for (int i = 0; i < BANDLIM_MAX; i++) 1042 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1043 } 1044 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1045 icmp_bandlimit_uninit, NULL); 1046 1047 int 1048 badport_bandlim(int which) 1049 { 1050 int64_t pps; 1051 1052 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1053 return (0); 1054 1055 KASSERT(which >= 0 && which < BANDLIM_MAX, 1056 ("%s: which %d", __func__, which)); 1057 1058 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1059 if (pps == -1) 1060 return (-1); 1061 if (pps > 0 && V_icmplim_output) 1062 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1063 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1064 return (0); 1065 } 1066