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 oip = mtod(n, struct ip *); 268 icmpelen = max(tcphlen, min(V_icmp_quotelen, 269 ntohs(oip->ip_len) - oiphlen)); 270 } else if (oip->ip_p == IPPROTO_SCTP) { 271 struct sctphdr *sh; 272 struct sctp_chunkhdr *ch; 273 274 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 275 goto stdreply; 276 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 277 n->m_next == NULL) 278 goto stdreply; 279 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 280 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 281 goto freeit; 282 oip = mtod(n, struct ip *); 283 icmpelen = max(sizeof(struct sctphdr), 284 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 285 sh = mtodo(n, oiphlen); 286 if (ntohl(sh->v_tag) == 0 && 287 ntohs(oip->ip_len) >= oiphlen + 288 sizeof(struct sctphdr) + 8 && 289 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 290 n->m_next != NULL)) { 291 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 292 (n = m_pullup(n, oiphlen + 293 sizeof(struct sctphdr) + 8)) == NULL) 294 goto freeit; 295 oip = mtod(n, struct ip *); 296 sh = mtodo(n, oiphlen); 297 ch = (struct sctp_chunkhdr *)(sh + 1); 298 if (ch->chunk_type == SCTP_INITIATION) { 299 icmpelen = max(sizeof(struct sctphdr) + 8, 300 min(V_icmp_quotelen, ntohs(oip->ip_len) - 301 oiphlen)); 302 } 303 } 304 } else 305 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 306 oiphlen)); 307 308 icmplen = min(oiphlen + icmpelen, nlen); 309 if (icmplen < sizeof(struct ip)) 310 goto freeit; 311 312 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 313 m = m_gethdr(M_NOWAIT, MT_DATA); 314 else 315 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 316 if (m == NULL) 317 goto freeit; 318 #ifdef MAC 319 mac_netinet_icmp_reply(n, m); 320 #endif 321 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 322 sizeof(struct ip) - ICMP_MINLEN); 323 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen); 324 m->m_data += sizeof(struct ip); 325 m->m_len = ICMP_MINLEN + icmplen; 326 327 /* XXX MRT make the outgoing packet use the same FIB 328 * that was associated with the incoming packet 329 */ 330 M_SETFIB(m, M_GETFIB(n)); 331 icp = mtod(m, struct icmp *); 332 ICMPSTAT_INC(icps_outhist[type]); 333 icp->icmp_type = type; 334 if (type == ICMP_REDIRECT) 335 icp->icmp_gwaddr.s_addr = dest; 336 else { 337 icp->icmp_void = 0; 338 /* 339 * The following assignments assume an overlay with the 340 * just zeroed icmp_void field. 341 */ 342 if (type == ICMP_PARAMPROB) { 343 icp->icmp_pptr = code; 344 code = 0; 345 } else if (type == ICMP_UNREACH && 346 code == ICMP_UNREACH_NEEDFRAG && mtu) { 347 icp->icmp_nextmtu = htons(mtu); 348 } 349 } 350 icp->icmp_code = code; 351 352 /* 353 * Copy the quotation into ICMP message and 354 * convert quoted IP header back to network representation. 355 */ 356 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 357 nip = &icp->icmp_ip; 358 359 /* 360 * Set up ICMP message mbuf and copy old IP header (without options 361 * in front of ICMP message. 362 * If the original mbuf was meant to bypass the firewall, the error 363 * reply should bypass as well. 364 */ 365 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 366 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip), 367 ("insufficient space for ip header")); 368 m->m_data -= sizeof(struct ip); 369 m->m_len += sizeof(struct ip); 370 m->m_pkthdr.len = m->m_len; 371 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 372 nip = mtod(m, struct ip *); 373 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 374 nip->ip_len = htons(m->m_len); 375 nip->ip_v = IPVERSION; 376 nip->ip_hl = 5; 377 nip->ip_p = IPPROTO_ICMP; 378 nip->ip_tos = 0; 379 nip->ip_off = 0; 380 381 if (V_error_keeptags) 382 m_tag_copy_chain(m, n, M_NOWAIT); 383 384 icmp_reflect(m); 385 386 freeit: 387 m_freem(n); 388 } 389 390 /* 391 * Process a received ICMP message. 392 */ 393 int 394 icmp_input(struct mbuf **mp, int *offp, int proto) 395 { 396 struct icmp *icp; 397 struct in_ifaddr *ia; 398 struct mbuf *m = *mp; 399 struct ip *ip = mtod(m, struct ip *); 400 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 401 int hlen = *offp; 402 int icmplen = ntohs(ip->ip_len) - *offp; 403 int i, code; 404 void (*ctlfunc)(int, struct sockaddr *, void *); 405 int fibnum; 406 407 *mp = NULL; 408 409 /* 410 * Locate icmp structure in mbuf, and check 411 * that not corrupted and of at least minimum length. 412 */ 413 #ifdef ICMPPRINTFS 414 if (icmpprintfs) { 415 char srcbuf[INET_ADDRSTRLEN]; 416 char dstbuf[INET_ADDRSTRLEN]; 417 418 printf("icmp_input from %s to %s, len %d\n", 419 inet_ntoa_r(ip->ip_src, srcbuf), 420 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 421 } 422 #endif 423 NET_EPOCH_ENTER(); 424 if (icmplen < ICMP_MINLEN) { 425 ICMPSTAT_INC(icps_tooshort); 426 goto freeit; 427 } 428 i = hlen + min(icmplen, ICMP_ADVLENMIN); 429 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 430 ICMPSTAT_INC(icps_tooshort); 431 NET_EPOCH_EXIT(); 432 return (IPPROTO_DONE); 433 } 434 ip = mtod(m, struct ip *); 435 m->m_len -= hlen; 436 m->m_data += hlen; 437 icp = mtod(m, struct icmp *); 438 if (in_cksum(m, icmplen)) { 439 ICMPSTAT_INC(icps_checksum); 440 goto freeit; 441 } 442 m->m_len += hlen; 443 m->m_data -= hlen; 444 445 #ifdef ICMPPRINTFS 446 if (icmpprintfs) 447 printf("icmp_input, type %d code %d\n", icp->icmp_type, 448 icp->icmp_code); 449 #endif 450 451 /* 452 * Message type specific processing. 453 */ 454 if (icp->icmp_type > ICMP_MAXTYPE) 455 goto raw; 456 457 /* Initialize */ 458 bzero(&icmpsrc, sizeof(icmpsrc)); 459 icmpsrc.sin_len = sizeof(struct sockaddr_in); 460 icmpsrc.sin_family = AF_INET; 461 bzero(&icmpdst, sizeof(icmpdst)); 462 icmpdst.sin_len = sizeof(struct sockaddr_in); 463 icmpdst.sin_family = AF_INET; 464 bzero(&icmpgw, sizeof(icmpgw)); 465 icmpgw.sin_len = sizeof(struct sockaddr_in); 466 icmpgw.sin_family = AF_INET; 467 468 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 469 code = icp->icmp_code; 470 switch (icp->icmp_type) { 471 472 case ICMP_UNREACH: 473 switch (code) { 474 case ICMP_UNREACH_NET: 475 case ICMP_UNREACH_HOST: 476 case ICMP_UNREACH_SRCFAIL: 477 case ICMP_UNREACH_NET_UNKNOWN: 478 case ICMP_UNREACH_HOST_UNKNOWN: 479 case ICMP_UNREACH_ISOLATED: 480 case ICMP_UNREACH_TOSNET: 481 case ICMP_UNREACH_TOSHOST: 482 case ICMP_UNREACH_HOST_PRECEDENCE: 483 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 484 code = PRC_UNREACH_NET; 485 break; 486 487 case ICMP_UNREACH_NEEDFRAG: 488 code = PRC_MSGSIZE; 489 break; 490 491 /* 492 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 493 * Treat subcodes 2,3 as immediate RST 494 */ 495 case ICMP_UNREACH_PROTOCOL: 496 code = PRC_UNREACH_PROTOCOL; 497 break; 498 case ICMP_UNREACH_PORT: 499 code = PRC_UNREACH_PORT; 500 break; 501 502 case ICMP_UNREACH_NET_PROHIB: 503 case ICMP_UNREACH_HOST_PROHIB: 504 case ICMP_UNREACH_FILTER_PROHIB: 505 code = PRC_UNREACH_ADMIN_PROHIB; 506 break; 507 508 default: 509 goto badcode; 510 } 511 goto deliver; 512 513 case ICMP_TIMXCEED: 514 if (code > 1) 515 goto badcode; 516 code += PRC_TIMXCEED_INTRANS; 517 goto deliver; 518 519 case ICMP_PARAMPROB: 520 if (code > 1) 521 goto badcode; 522 code = PRC_PARAMPROB; 523 deliver: 524 /* 525 * Problem with datagram; advise higher level routines. 526 */ 527 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 528 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 529 ICMPSTAT_INC(icps_badlen); 530 goto freeit; 531 } 532 /* Discard ICMP's in response to multicast packets */ 533 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 534 goto badcode; 535 #ifdef ICMPPRINTFS 536 if (icmpprintfs) 537 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 538 #endif 539 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 540 /* 541 * XXX if the packet contains [IPv4 AH TCP], we can't make a 542 * notification to TCP layer. 543 */ 544 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 545 ip_stripoptions(m); 546 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 547 /* This should actually not happen */ 548 ICMPSTAT_INC(icps_tooshort); 549 NET_EPOCH_EXIT(); 550 return (IPPROTO_DONE); 551 } 552 ip = mtod(m, struct ip *); 553 icp = (struct icmp *)(ip + 1); 554 /* 555 * The upper layer handler can rely on: 556 * - The outer IP header has no options. 557 * - The outer IP header, the ICMP header, the inner IP header, 558 * and the first n bytes of the inner payload are contiguous. 559 * n is at least 8, but might be larger based on 560 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 561 */ 562 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 563 if (ctlfunc) 564 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 565 (void *)&icp->icmp_ip); 566 break; 567 568 badcode: 569 ICMPSTAT_INC(icps_badcode); 570 break; 571 572 case ICMP_ECHO: 573 if (!V_icmpbmcastecho 574 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 575 ICMPSTAT_INC(icps_bmcastecho); 576 break; 577 } 578 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 579 goto freeit; 580 icp->icmp_type = ICMP_ECHOREPLY; 581 goto reflect; 582 583 case ICMP_TSTAMP: 584 if (V_icmptstamprepl == 0) 585 break; 586 if (!V_icmpbmcastecho 587 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 588 ICMPSTAT_INC(icps_bmcasttstamp); 589 break; 590 } 591 if (icmplen < ICMP_TSLEN) { 592 ICMPSTAT_INC(icps_badlen); 593 break; 594 } 595 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 596 goto freeit; 597 icp->icmp_type = ICMP_TSTAMPREPLY; 598 icp->icmp_rtime = iptime(); 599 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 600 goto reflect; 601 602 case ICMP_MASKREQ: 603 if (V_icmpmaskrepl == 0) 604 break; 605 /* 606 * We are not able to respond with all ones broadcast 607 * unless we receive it over a point-to-point interface. 608 */ 609 if (icmplen < ICMP_MASKLEN) 610 break; 611 switch (ip->ip_dst.s_addr) { 612 613 case INADDR_BROADCAST: 614 case INADDR_ANY: 615 icmpdst.sin_addr = ip->ip_src; 616 break; 617 618 default: 619 icmpdst.sin_addr = ip->ip_dst; 620 } 621 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 622 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 623 if (ia == NULL) 624 break; 625 if (ia->ia_ifp == NULL) 626 break; 627 icp->icmp_type = ICMP_MASKREPLY; 628 if (V_icmpmaskfake == 0) 629 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 630 else 631 icp->icmp_mask = V_icmpmaskfake; 632 if (ip->ip_src.s_addr == 0) { 633 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 634 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 635 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 636 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 637 } 638 reflect: 639 ICMPSTAT_INC(icps_reflect); 640 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 641 icmp_reflect(m); 642 NET_EPOCH_EXIT(); 643 return (IPPROTO_DONE); 644 645 case ICMP_REDIRECT: 646 if (V_log_redirect) { 647 u_long src, dst, gw; 648 649 src = ntohl(ip->ip_src.s_addr); 650 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 651 gw = ntohl(icp->icmp_gwaddr.s_addr); 652 printf("icmp redirect from %d.%d.%d.%d: " 653 "%d.%d.%d.%d => %d.%d.%d.%d\n", 654 (int)(src >> 24), (int)((src >> 16) & 0xff), 655 (int)((src >> 8) & 0xff), (int)(src & 0xff), 656 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 657 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 658 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 659 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 660 } 661 /* 662 * RFC1812 says we must ignore ICMP redirects if we 663 * are acting as router. 664 */ 665 if (V_drop_redirect || V_ipforwarding) 666 break; 667 if (code > 3) 668 goto badcode; 669 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 670 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 671 ICMPSTAT_INC(icps_badlen); 672 break; 673 } 674 /* 675 * Short circuit routing redirects to force 676 * immediate change in the kernel's routing 677 * tables. The message is also handed to anyone 678 * listening on a raw socket (e.g. the routing 679 * daemon for use in updating its tables). 680 */ 681 icmpgw.sin_addr = ip->ip_src; 682 icmpdst.sin_addr = icp->icmp_gwaddr; 683 #ifdef ICMPPRINTFS 684 if (icmpprintfs) { 685 char dstbuf[INET_ADDRSTRLEN]; 686 char gwbuf[INET_ADDRSTRLEN]; 687 688 printf("redirect dst %s to %s\n", 689 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 690 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 691 } 692 #endif 693 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 694 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 695 in_rtredirect((struct sockaddr *)&icmpsrc, 696 (struct sockaddr *)&icmpdst, 697 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 698 (struct sockaddr *)&icmpgw, fibnum); 699 } 700 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 701 break; 702 703 /* 704 * No kernel processing for the following; 705 * just fall through to send to raw listener. 706 */ 707 case ICMP_ECHOREPLY: 708 case ICMP_ROUTERADVERT: 709 case ICMP_ROUTERSOLICIT: 710 case ICMP_TSTAMPREPLY: 711 case ICMP_IREQREPLY: 712 case ICMP_MASKREPLY: 713 case ICMP_SOURCEQUENCH: 714 default: 715 break; 716 } 717 718 raw: 719 NET_EPOCH_EXIT(); 720 *mp = m; 721 rip_input(mp, offp, proto); 722 return (IPPROTO_DONE); 723 724 freeit: 725 NET_EPOCH_EXIT(); 726 m_freem(m); 727 return (IPPROTO_DONE); 728 } 729 730 /* 731 * Reflect the ip packet back to the source 732 */ 733 static void 734 icmp_reflect(struct mbuf *m) 735 { 736 struct rm_priotracker in_ifa_tracker; 737 struct ip *ip = mtod(m, struct ip *); 738 struct ifaddr *ifa; 739 struct ifnet *ifp; 740 struct in_ifaddr *ia; 741 struct in_addr t; 742 struct nhop4_extended nh_ext; 743 struct mbuf *opts = NULL; 744 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 745 746 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 747 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 748 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 749 m_freem(m); /* Bad return address */ 750 ICMPSTAT_INC(icps_badaddr); 751 goto done; /* Ip_output() will check for broadcast */ 752 } 753 754 t = ip->ip_dst; 755 ip->ip_dst = ip->ip_src; 756 757 /* 758 * Source selection for ICMP replies: 759 * 760 * If the incoming packet was addressed directly to one of our 761 * own addresses, use dst as the src for the reply. 762 */ 763 IN_IFADDR_RLOCK(&in_ifa_tracker); 764 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 765 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 766 t = IA_SIN(ia)->sin_addr; 767 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 768 goto match; 769 } 770 } 771 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 772 773 /* 774 * If the incoming packet was addressed to one of our broadcast 775 * addresses, use the first non-broadcast address which corresponds 776 * to the incoming interface. 777 */ 778 ifp = m->m_pkthdr.rcvif; 779 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 780 IF_ADDR_RLOCK(ifp); 781 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 782 if (ifa->ifa_addr->sa_family != AF_INET) 783 continue; 784 ia = ifatoia(ifa); 785 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 786 t.s_addr) { 787 t = IA_SIN(ia)->sin_addr; 788 IF_ADDR_RUNLOCK(ifp); 789 goto match; 790 } 791 } 792 IF_ADDR_RUNLOCK(ifp); 793 } 794 /* 795 * If the packet was transiting through us, use the address of 796 * the interface the packet came through in. If that interface 797 * doesn't have a suitable IP address, the normal selection 798 * criteria apply. 799 */ 800 if (V_icmp_rfi && ifp != NULL) { 801 IF_ADDR_RLOCK(ifp); 802 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 803 if (ifa->ifa_addr->sa_family != AF_INET) 804 continue; 805 ia = ifatoia(ifa); 806 t = IA_SIN(ia)->sin_addr; 807 IF_ADDR_RUNLOCK(ifp); 808 goto match; 809 } 810 IF_ADDR_RUNLOCK(ifp); 811 } 812 /* 813 * If the incoming packet was not addressed directly to us, use 814 * designated interface for icmp replies specified by sysctl 815 * net.inet.icmp.reply_src (default not set). Otherwise continue 816 * with normal source selection. 817 */ 818 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 819 IF_ADDR_RLOCK(ifp); 820 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 821 if (ifa->ifa_addr->sa_family != AF_INET) 822 continue; 823 ia = ifatoia(ifa); 824 t = IA_SIN(ia)->sin_addr; 825 IF_ADDR_RUNLOCK(ifp); 826 goto match; 827 } 828 IF_ADDR_RUNLOCK(ifp); 829 } 830 /* 831 * If the packet was transiting through us, use the address of 832 * the interface that is the closest to the packet source. 833 * When we don't have a route back to the packet source, stop here 834 * and drop the packet. 835 */ 836 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 837 m_freem(m); 838 ICMPSTAT_INC(icps_noroute); 839 goto done; 840 } 841 t = nh_ext.nh_src; 842 match: 843 #ifdef MAC 844 mac_netinet_icmp_replyinplace(m); 845 #endif 846 ip->ip_src = t; 847 ip->ip_ttl = V_ip_defttl; 848 849 if (optlen > 0) { 850 u_char *cp; 851 int opt, cnt; 852 u_int len; 853 854 /* 855 * Retrieve any source routing from the incoming packet; 856 * add on any record-route or timestamp options. 857 */ 858 cp = (u_char *) (ip + 1); 859 if ((opts = ip_srcroute(m)) == NULL && 860 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 861 opts->m_len = sizeof(struct in_addr); 862 mtod(opts, struct in_addr *)->s_addr = 0; 863 } 864 if (opts) { 865 #ifdef ICMPPRINTFS 866 if (icmpprintfs) 867 printf("icmp_reflect optlen %d rt %d => ", 868 optlen, opts->m_len); 869 #endif 870 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 871 opt = cp[IPOPT_OPTVAL]; 872 if (opt == IPOPT_EOL) 873 break; 874 if (opt == IPOPT_NOP) 875 len = 1; 876 else { 877 if (cnt < IPOPT_OLEN + sizeof(*cp)) 878 break; 879 len = cp[IPOPT_OLEN]; 880 if (len < IPOPT_OLEN + sizeof(*cp) || 881 len > cnt) 882 break; 883 } 884 /* 885 * Should check for overflow, but it "can't happen" 886 */ 887 if (opt == IPOPT_RR || opt == IPOPT_TS || 888 opt == IPOPT_SECURITY) { 889 bcopy((caddr_t)cp, 890 mtod(opts, caddr_t) + opts->m_len, len); 891 opts->m_len += len; 892 } 893 } 894 /* Terminate & pad, if necessary */ 895 cnt = opts->m_len % 4; 896 if (cnt) { 897 for (; cnt < 4; cnt++) { 898 *(mtod(opts, caddr_t) + opts->m_len) = 899 IPOPT_EOL; 900 opts->m_len++; 901 } 902 } 903 #ifdef ICMPPRINTFS 904 if (icmpprintfs) 905 printf("%d\n", opts->m_len); 906 #endif 907 } 908 ip_stripoptions(m); 909 } 910 m_tag_delete_nonpersistent(m); 911 m->m_flags &= ~(M_BCAST|M_MCAST); 912 icmp_send(m, opts); 913 done: 914 if (opts) 915 (void)m_free(opts); 916 } 917 918 /* 919 * Send an icmp packet back to the ip level, 920 * after supplying a checksum. 921 */ 922 static void 923 icmp_send(struct mbuf *m, struct mbuf *opts) 924 { 925 struct ip *ip = mtod(m, struct ip *); 926 int hlen; 927 struct icmp *icp; 928 929 hlen = ip->ip_hl << 2; 930 m->m_data += hlen; 931 m->m_len -= hlen; 932 icp = mtod(m, struct icmp *); 933 icp->icmp_cksum = 0; 934 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 935 m->m_data -= hlen; 936 m->m_len += hlen; 937 m->m_pkthdr.rcvif = (struct ifnet *)0; 938 #ifdef ICMPPRINTFS 939 if (icmpprintfs) { 940 char dstbuf[INET_ADDRSTRLEN]; 941 char srcbuf[INET_ADDRSTRLEN]; 942 943 printf("icmp_send dst %s src %s\n", 944 inet_ntoa_r(ip->ip_dst, dstbuf), 945 inet_ntoa_r(ip->ip_src, srcbuf)); 946 } 947 #endif 948 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 949 } 950 951 /* 952 * Return milliseconds since 00:00 UTC in network format. 953 */ 954 uint32_t 955 iptime(void) 956 { 957 struct timeval atv; 958 u_long t; 959 960 getmicrotime(&atv); 961 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 962 return (htonl(t)); 963 } 964 965 /* 966 * Return the next larger or smaller MTU plateau (table from RFC 1191) 967 * given current value MTU. If DIR is less than zero, a larger plateau 968 * is returned; otherwise, a smaller value is returned. 969 */ 970 int 971 ip_next_mtu(int mtu, int dir) 972 { 973 static int mtutab[] = { 974 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 975 296, 68, 0 976 }; 977 int i, size; 978 979 size = (sizeof mtutab) / (sizeof mtutab[0]); 980 if (dir >= 0) { 981 for (i = 0; i < size; i++) 982 if (mtu > mtutab[i]) 983 return mtutab[i]; 984 } else { 985 for (i = size - 1; i >= 0; i--) 986 if (mtu < mtutab[i]) 987 return mtutab[i]; 988 if (mtu == mtutab[0]) 989 return mtutab[0]; 990 } 991 return 0; 992 } 993 #endif /* INET */ 994 995 996 /* 997 * badport_bandlim() - check for ICMP bandwidth limit 998 * 999 * Return 0 if it is ok to send an ICMP error response, -1 if we have 1000 * hit our bandwidth limit and it is not ok. 1001 * 1002 * If icmplim is <= 0, the feature is disabled and 0 is returned. 1003 * 1004 * For now we separate the TCP and UDP subsystems w/ different 'which' 1005 * values. We may eventually remove this separation (and simplify the 1006 * code further). 1007 * 1008 * Note that the printing of the error message is delayed so we can 1009 * properly print the icmp error rate that the system was trying to do 1010 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 1011 * the 'final' error, but it doesn't make sense to solve the printing 1012 * delay with more complex code. 1013 */ 1014 struct icmp_rate { 1015 const char *descr; 1016 struct counter_rate cr; 1017 }; 1018 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 1019 { "icmp unreach response" }, 1020 { "icmp ping response" }, 1021 { "icmp tstamp response" }, 1022 { "closed port RST response" }, 1023 { "open port RST response" }, 1024 { "icmp6 unreach response" }, 1025 { "sctp ootb response" } 1026 }; 1027 #define V_icmp_rates VNET(icmp_rates) 1028 1029 static void 1030 icmp_bandlimit_init(void) 1031 { 1032 1033 for (int i = 0; i < BANDLIM_MAX; i++) { 1034 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 1035 V_icmp_rates[i].cr.cr_ticks = ticks; 1036 } 1037 } 1038 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1039 icmp_bandlimit_init, NULL); 1040 1041 static void 1042 icmp_bandlimit_uninit(void) 1043 { 1044 1045 for (int i = 0; i < BANDLIM_MAX; i++) 1046 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1047 } 1048 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1049 icmp_bandlimit_uninit, NULL); 1050 1051 int 1052 badport_bandlim(int which) 1053 { 1054 int64_t pps; 1055 1056 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1057 return (0); 1058 1059 KASSERT(which >= 0 && which < BANDLIM_MAX, 1060 ("%s: which %d", __func__, which)); 1061 1062 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1063 if (pps == -1) 1064 return (-1); 1065 if (pps > 0 && V_icmplim_output) 1066 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1067 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1068 return (0); 1069 } 1070