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 epoch_tracker et; 397 struct icmp *icp; 398 struct in_ifaddr *ia; 399 struct mbuf *m = *mp; 400 struct ip *ip = mtod(m, struct ip *); 401 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 402 int hlen = *offp; 403 int icmplen = ntohs(ip->ip_len) - *offp; 404 int i, code; 405 void (*ctlfunc)(int, struct sockaddr *, void *); 406 int fibnum; 407 408 *mp = NULL; 409 410 /* 411 * Locate icmp structure in mbuf, and check 412 * that not corrupted and of at least minimum length. 413 */ 414 #ifdef ICMPPRINTFS 415 if (icmpprintfs) { 416 char srcbuf[INET_ADDRSTRLEN]; 417 char dstbuf[INET_ADDRSTRLEN]; 418 419 printf("icmp_input from %s to %s, len %d\n", 420 inet_ntoa_r(ip->ip_src, srcbuf), 421 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 422 } 423 #endif 424 NET_EPOCH_ENTER(et); 425 if (icmplen < ICMP_MINLEN) { 426 ICMPSTAT_INC(icps_tooshort); 427 goto freeit; 428 } 429 i = hlen + min(icmplen, ICMP_ADVLENMIN); 430 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 431 ICMPSTAT_INC(icps_tooshort); 432 NET_EPOCH_EXIT(et); 433 return (IPPROTO_DONE); 434 } 435 ip = mtod(m, struct ip *); 436 m->m_len -= hlen; 437 m->m_data += hlen; 438 icp = mtod(m, struct icmp *); 439 if (in_cksum(m, icmplen)) { 440 ICMPSTAT_INC(icps_checksum); 441 goto freeit; 442 } 443 m->m_len += hlen; 444 m->m_data -= hlen; 445 446 #ifdef ICMPPRINTFS 447 if (icmpprintfs) 448 printf("icmp_input, type %d code %d\n", icp->icmp_type, 449 icp->icmp_code); 450 #endif 451 452 /* 453 * Message type specific processing. 454 */ 455 if (icp->icmp_type > ICMP_MAXTYPE) 456 goto raw; 457 458 /* Initialize */ 459 bzero(&icmpsrc, sizeof(icmpsrc)); 460 icmpsrc.sin_len = sizeof(struct sockaddr_in); 461 icmpsrc.sin_family = AF_INET; 462 bzero(&icmpdst, sizeof(icmpdst)); 463 icmpdst.sin_len = sizeof(struct sockaddr_in); 464 icmpdst.sin_family = AF_INET; 465 bzero(&icmpgw, sizeof(icmpgw)); 466 icmpgw.sin_len = sizeof(struct sockaddr_in); 467 icmpgw.sin_family = AF_INET; 468 469 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 470 code = icp->icmp_code; 471 switch (icp->icmp_type) { 472 473 case ICMP_UNREACH: 474 switch (code) { 475 case ICMP_UNREACH_NET: 476 case ICMP_UNREACH_HOST: 477 case ICMP_UNREACH_SRCFAIL: 478 case ICMP_UNREACH_NET_UNKNOWN: 479 case ICMP_UNREACH_HOST_UNKNOWN: 480 case ICMP_UNREACH_ISOLATED: 481 case ICMP_UNREACH_TOSNET: 482 case ICMP_UNREACH_TOSHOST: 483 case ICMP_UNREACH_HOST_PRECEDENCE: 484 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 485 code = PRC_UNREACH_NET; 486 break; 487 488 case ICMP_UNREACH_NEEDFRAG: 489 code = PRC_MSGSIZE; 490 break; 491 492 /* 493 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 494 * Treat subcodes 2,3 as immediate RST 495 */ 496 case ICMP_UNREACH_PROTOCOL: 497 code = PRC_UNREACH_PROTOCOL; 498 break; 499 case ICMP_UNREACH_PORT: 500 code = PRC_UNREACH_PORT; 501 break; 502 503 case ICMP_UNREACH_NET_PROHIB: 504 case ICMP_UNREACH_HOST_PROHIB: 505 case ICMP_UNREACH_FILTER_PROHIB: 506 code = PRC_UNREACH_ADMIN_PROHIB; 507 break; 508 509 default: 510 goto badcode; 511 } 512 goto deliver; 513 514 case ICMP_TIMXCEED: 515 if (code > 1) 516 goto badcode; 517 code += PRC_TIMXCEED_INTRANS; 518 goto deliver; 519 520 case ICMP_PARAMPROB: 521 if (code > 1) 522 goto badcode; 523 code = PRC_PARAMPROB; 524 deliver: 525 /* 526 * Problem with datagram; advise higher level routines. 527 */ 528 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 529 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 530 ICMPSTAT_INC(icps_badlen); 531 goto freeit; 532 } 533 /* Discard ICMP's in response to multicast packets */ 534 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 535 goto badcode; 536 #ifdef ICMPPRINTFS 537 if (icmpprintfs) 538 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 539 #endif 540 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 541 /* 542 * XXX if the packet contains [IPv4 AH TCP], we can't make a 543 * notification to TCP layer. 544 */ 545 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 546 ip_stripoptions(m); 547 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 548 /* This should actually not happen */ 549 ICMPSTAT_INC(icps_tooshort); 550 NET_EPOCH_EXIT(et); 551 return (IPPROTO_DONE); 552 } 553 ip = mtod(m, struct ip *); 554 icp = (struct icmp *)(ip + 1); 555 /* 556 * The upper layer handler can rely on: 557 * - The outer IP header has no options. 558 * - The outer IP header, the ICMP header, the inner IP header, 559 * and the first n bytes of the inner payload are contiguous. 560 * n is at least 8, but might be larger based on 561 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 562 */ 563 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 564 if (ctlfunc) 565 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 566 (void *)&icp->icmp_ip); 567 break; 568 569 badcode: 570 ICMPSTAT_INC(icps_badcode); 571 break; 572 573 case ICMP_ECHO: 574 if (!V_icmpbmcastecho 575 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 576 ICMPSTAT_INC(icps_bmcastecho); 577 break; 578 } 579 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 580 goto freeit; 581 icp->icmp_type = ICMP_ECHOREPLY; 582 goto reflect; 583 584 case ICMP_TSTAMP: 585 if (V_icmptstamprepl == 0) 586 break; 587 if (!V_icmpbmcastecho 588 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 589 ICMPSTAT_INC(icps_bmcasttstamp); 590 break; 591 } 592 if (icmplen < ICMP_TSLEN) { 593 ICMPSTAT_INC(icps_badlen); 594 break; 595 } 596 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 597 goto freeit; 598 icp->icmp_type = ICMP_TSTAMPREPLY; 599 icp->icmp_rtime = iptime(); 600 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 601 goto reflect; 602 603 case ICMP_MASKREQ: 604 if (V_icmpmaskrepl == 0) 605 break; 606 /* 607 * We are not able to respond with all ones broadcast 608 * unless we receive it over a point-to-point interface. 609 */ 610 if (icmplen < ICMP_MASKLEN) 611 break; 612 switch (ip->ip_dst.s_addr) { 613 614 case INADDR_BROADCAST: 615 case INADDR_ANY: 616 icmpdst.sin_addr = ip->ip_src; 617 break; 618 619 default: 620 icmpdst.sin_addr = ip->ip_dst; 621 } 622 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 623 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 624 if (ia == NULL) 625 break; 626 if (ia->ia_ifp == NULL) 627 break; 628 icp->icmp_type = ICMP_MASKREPLY; 629 if (V_icmpmaskfake == 0) 630 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 631 else 632 icp->icmp_mask = V_icmpmaskfake; 633 if (ip->ip_src.s_addr == 0) { 634 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 635 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 636 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 637 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 638 } 639 reflect: 640 ICMPSTAT_INC(icps_reflect); 641 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 642 icmp_reflect(m); 643 NET_EPOCH_EXIT(et); 644 return (IPPROTO_DONE); 645 646 case ICMP_REDIRECT: 647 if (V_log_redirect) { 648 u_long src, dst, gw; 649 650 src = ntohl(ip->ip_src.s_addr); 651 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 652 gw = ntohl(icp->icmp_gwaddr.s_addr); 653 printf("icmp redirect from %d.%d.%d.%d: " 654 "%d.%d.%d.%d => %d.%d.%d.%d\n", 655 (int)(src >> 24), (int)((src >> 16) & 0xff), 656 (int)((src >> 8) & 0xff), (int)(src & 0xff), 657 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 658 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 659 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 660 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 661 } 662 /* 663 * RFC1812 says we must ignore ICMP redirects if we 664 * are acting as router. 665 */ 666 if (V_drop_redirect || V_ipforwarding) 667 break; 668 if (code > 3) 669 goto badcode; 670 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 671 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 672 ICMPSTAT_INC(icps_badlen); 673 break; 674 } 675 /* 676 * Short circuit routing redirects to force 677 * immediate change in the kernel's routing 678 * tables. The message is also handed to anyone 679 * listening on a raw socket (e.g. the routing 680 * daemon for use in updating its tables). 681 */ 682 icmpgw.sin_addr = ip->ip_src; 683 icmpdst.sin_addr = icp->icmp_gwaddr; 684 #ifdef ICMPPRINTFS 685 if (icmpprintfs) { 686 char dstbuf[INET_ADDRSTRLEN]; 687 char gwbuf[INET_ADDRSTRLEN]; 688 689 printf("redirect dst %s to %s\n", 690 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 691 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 692 } 693 #endif 694 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 695 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 696 in_rtredirect((struct sockaddr *)&icmpsrc, 697 (struct sockaddr *)&icmpdst, 698 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 699 (struct sockaddr *)&icmpgw, fibnum); 700 } 701 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 702 break; 703 704 /* 705 * No kernel processing for the following; 706 * just fall through to send to raw listener. 707 */ 708 case ICMP_ECHOREPLY: 709 case ICMP_ROUTERADVERT: 710 case ICMP_ROUTERSOLICIT: 711 case ICMP_TSTAMPREPLY: 712 case ICMP_IREQREPLY: 713 case ICMP_MASKREPLY: 714 case ICMP_SOURCEQUENCH: 715 default: 716 break; 717 } 718 719 raw: 720 NET_EPOCH_EXIT(et); 721 *mp = m; 722 rip_input(mp, offp, proto); 723 return (IPPROTO_DONE); 724 725 freeit: 726 NET_EPOCH_EXIT(et); 727 m_freem(m); 728 return (IPPROTO_DONE); 729 } 730 731 /* 732 * Reflect the ip packet back to the source 733 */ 734 static void 735 icmp_reflect(struct mbuf *m) 736 { 737 struct rm_priotracker in_ifa_tracker; 738 struct epoch_tracker et; 739 struct ip *ip = mtod(m, struct ip *); 740 struct ifaddr *ifa; 741 struct ifnet *ifp; 742 struct in_ifaddr *ia; 743 struct in_addr t; 744 struct nhop4_extended nh_ext; 745 struct mbuf *opts = NULL; 746 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 747 748 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 749 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 750 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 751 m_freem(m); /* Bad return address */ 752 ICMPSTAT_INC(icps_badaddr); 753 goto done; /* Ip_output() will check for broadcast */ 754 } 755 756 t = ip->ip_dst; 757 ip->ip_dst = ip->ip_src; 758 759 /* 760 * Source selection for ICMP replies: 761 * 762 * If the incoming packet was addressed directly to one of our 763 * own addresses, use dst as the src for the reply. 764 */ 765 IN_IFADDR_RLOCK(&in_ifa_tracker); 766 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 767 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 768 t = IA_SIN(ia)->sin_addr; 769 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 770 goto match; 771 } 772 } 773 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 774 775 /* 776 * If the incoming packet was addressed to one of our broadcast 777 * addresses, use the first non-broadcast address which corresponds 778 * to the incoming interface. 779 */ 780 ifp = m->m_pkthdr.rcvif; 781 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 782 NET_EPOCH_ENTER(et); 783 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 784 if (ifa->ifa_addr->sa_family != AF_INET) 785 continue; 786 ia = ifatoia(ifa); 787 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 788 t.s_addr) { 789 t = IA_SIN(ia)->sin_addr; 790 NET_EPOCH_EXIT(et); 791 goto match; 792 } 793 } 794 NET_EPOCH_EXIT(et); 795 } 796 /* 797 * If the packet was transiting through us, use the address of 798 * the interface the packet came through in. If that interface 799 * doesn't have a suitable IP address, the normal selection 800 * criteria apply. 801 */ 802 if (V_icmp_rfi && ifp != NULL) { 803 NET_EPOCH_ENTER(et); 804 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 805 if (ifa->ifa_addr->sa_family != AF_INET) 806 continue; 807 ia = ifatoia(ifa); 808 t = IA_SIN(ia)->sin_addr; 809 NET_EPOCH_EXIT(et); 810 goto match; 811 } 812 NET_EPOCH_EXIT(et); 813 } 814 /* 815 * If the incoming packet was not addressed directly to us, use 816 * designated interface for icmp replies specified by sysctl 817 * net.inet.icmp.reply_src (default not set). Otherwise continue 818 * with normal source selection. 819 */ 820 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 821 NET_EPOCH_ENTER(et); 822 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 823 if (ifa->ifa_addr->sa_family != AF_INET) 824 continue; 825 ia = ifatoia(ifa); 826 t = IA_SIN(ia)->sin_addr; 827 NET_EPOCH_EXIT(et); 828 goto match; 829 } 830 NET_EPOCH_EXIT(et); 831 } 832 /* 833 * If the packet was transiting through us, use the address of 834 * the interface that is the closest to the packet source. 835 * When we don't have a route back to the packet source, stop here 836 * and drop the packet. 837 */ 838 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 839 m_freem(m); 840 ICMPSTAT_INC(icps_noroute); 841 goto done; 842 } 843 t = nh_ext.nh_src; 844 match: 845 #ifdef MAC 846 mac_netinet_icmp_replyinplace(m); 847 #endif 848 ip->ip_src = t; 849 ip->ip_ttl = V_ip_defttl; 850 851 if (optlen > 0) { 852 u_char *cp; 853 int opt, cnt; 854 u_int len; 855 856 /* 857 * Retrieve any source routing from the incoming packet; 858 * add on any record-route or timestamp options. 859 */ 860 cp = (u_char *) (ip + 1); 861 if ((opts = ip_srcroute(m)) == NULL && 862 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 863 opts->m_len = sizeof(struct in_addr); 864 mtod(opts, struct in_addr *)->s_addr = 0; 865 } 866 if (opts) { 867 #ifdef ICMPPRINTFS 868 if (icmpprintfs) 869 printf("icmp_reflect optlen %d rt %d => ", 870 optlen, opts->m_len); 871 #endif 872 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 873 opt = cp[IPOPT_OPTVAL]; 874 if (opt == IPOPT_EOL) 875 break; 876 if (opt == IPOPT_NOP) 877 len = 1; 878 else { 879 if (cnt < IPOPT_OLEN + sizeof(*cp)) 880 break; 881 len = cp[IPOPT_OLEN]; 882 if (len < IPOPT_OLEN + sizeof(*cp) || 883 len > cnt) 884 break; 885 } 886 /* 887 * Should check for overflow, but it "can't happen" 888 */ 889 if (opt == IPOPT_RR || opt == IPOPT_TS || 890 opt == IPOPT_SECURITY) { 891 bcopy((caddr_t)cp, 892 mtod(opts, caddr_t) + opts->m_len, len); 893 opts->m_len += len; 894 } 895 } 896 /* Terminate & pad, if necessary */ 897 cnt = opts->m_len % 4; 898 if (cnt) { 899 for (; cnt < 4; cnt++) { 900 *(mtod(opts, caddr_t) + opts->m_len) = 901 IPOPT_EOL; 902 opts->m_len++; 903 } 904 } 905 #ifdef ICMPPRINTFS 906 if (icmpprintfs) 907 printf("%d\n", opts->m_len); 908 #endif 909 } 910 ip_stripoptions(m); 911 } 912 m_tag_delete_nonpersistent(m); 913 m->m_flags &= ~(M_BCAST|M_MCAST); 914 icmp_send(m, opts); 915 done: 916 if (opts) 917 (void)m_free(opts); 918 } 919 920 /* 921 * Send an icmp packet back to the ip level, 922 * after supplying a checksum. 923 */ 924 static void 925 icmp_send(struct mbuf *m, struct mbuf *opts) 926 { 927 struct ip *ip = mtod(m, struct ip *); 928 int hlen; 929 struct icmp *icp; 930 931 hlen = ip->ip_hl << 2; 932 m->m_data += hlen; 933 m->m_len -= hlen; 934 icp = mtod(m, struct icmp *); 935 icp->icmp_cksum = 0; 936 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 937 m->m_data -= hlen; 938 m->m_len += hlen; 939 m->m_pkthdr.rcvif = (struct ifnet *)0; 940 #ifdef ICMPPRINTFS 941 if (icmpprintfs) { 942 char dstbuf[INET_ADDRSTRLEN]; 943 char srcbuf[INET_ADDRSTRLEN]; 944 945 printf("icmp_send dst %s src %s\n", 946 inet_ntoa_r(ip->ip_dst, dstbuf), 947 inet_ntoa_r(ip->ip_src, srcbuf)); 948 } 949 #endif 950 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 951 } 952 953 /* 954 * Return milliseconds since 00:00 UTC in network format. 955 */ 956 uint32_t 957 iptime(void) 958 { 959 struct timeval atv; 960 u_long t; 961 962 getmicrotime(&atv); 963 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 964 return (htonl(t)); 965 } 966 967 /* 968 * Return the next larger or smaller MTU plateau (table from RFC 1191) 969 * given current value MTU. If DIR is less than zero, a larger plateau 970 * is returned; otherwise, a smaller value is returned. 971 */ 972 int 973 ip_next_mtu(int mtu, int dir) 974 { 975 static int mtutab[] = { 976 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 977 296, 68, 0 978 }; 979 int i, size; 980 981 size = (sizeof mtutab) / (sizeof mtutab[0]); 982 if (dir >= 0) { 983 for (i = 0; i < size; i++) 984 if (mtu > mtutab[i]) 985 return mtutab[i]; 986 } else { 987 for (i = size - 1; i >= 0; i--) 988 if (mtu < mtutab[i]) 989 return mtutab[i]; 990 if (mtu == mtutab[0]) 991 return mtutab[0]; 992 } 993 return 0; 994 } 995 #endif /* INET */ 996 997 998 /* 999 * badport_bandlim() - check for ICMP bandwidth limit 1000 * 1001 * Return 0 if it is ok to send an ICMP error response, -1 if we have 1002 * hit our bandwidth limit and it is not ok. 1003 * 1004 * If icmplim is <= 0, the feature is disabled and 0 is returned. 1005 * 1006 * For now we separate the TCP and UDP subsystems w/ different 'which' 1007 * values. We may eventually remove this separation (and simplify the 1008 * code further). 1009 * 1010 * Note that the printing of the error message is delayed so we can 1011 * properly print the icmp error rate that the system was trying to do 1012 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 1013 * the 'final' error, but it doesn't make sense to solve the printing 1014 * delay with more complex code. 1015 */ 1016 struct icmp_rate { 1017 const char *descr; 1018 struct counter_rate cr; 1019 }; 1020 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 1021 { "icmp unreach response" }, 1022 { "icmp ping response" }, 1023 { "icmp tstamp response" }, 1024 { "closed port RST response" }, 1025 { "open port RST response" }, 1026 { "icmp6 unreach response" }, 1027 { "sctp ootb response" } 1028 }; 1029 #define V_icmp_rates VNET(icmp_rates) 1030 1031 static void 1032 icmp_bandlimit_init(void) 1033 { 1034 1035 for (int i = 0; i < BANDLIM_MAX; i++) { 1036 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 1037 V_icmp_rates[i].cr.cr_ticks = ticks; 1038 } 1039 } 1040 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1041 icmp_bandlimit_init, NULL); 1042 1043 static void 1044 icmp_bandlimit_uninit(void) 1045 { 1046 1047 for (int i = 0; i < BANDLIM_MAX; i++) 1048 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1049 } 1050 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1051 icmp_bandlimit_uninit, NULL); 1052 1053 int 1054 badport_bandlim(int which) 1055 { 1056 int64_t pps; 1057 1058 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1059 return (0); 1060 1061 KASSERT(which >= 0 && which < BANDLIM_MAX, 1062 ("%s: which %d", __func__, which)); 1063 1064 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1065 if (pps == -1) 1066 return (-1); 1067 if (pps > 0 && V_icmplim_output) 1068 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1069 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1070 return (0); 1071 } 1072