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