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 */ 85VNET_DEFINE_STATIC(int, icmplim) = 200; 86#define V_icmplim VNET(icmplim) 87SYSCTL_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 91VNET_DEFINE_STATIC(int, icmplim_output) = 1; 92#define V_icmplim_output VNET(icmplim_output) 93SYSCTL_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 98VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 99VNET_PCPUSTAT_SYSINIT(icmpstat); 100SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 101 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 102 103#ifdef VIMAGE 104VNET_PCPUSTAT_SYSUNINIT(icmpstat); 105#endif /* VIMAGE */ 106 107VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0; 108#define V_icmpmaskrepl VNET(icmpmaskrepl) 109SYSCTL_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 113VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0; 114#define V_icmpmaskfake VNET(icmpmaskfake) 115SYSCTL_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 119VNET_DEFINE(int, drop_redirect) = 0; 120#define V_drop_redirect VNET(drop_redirect) 121SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 122 &VNET_NAME(drop_redirect), 0, 123 "Ignore ICMP redirects"); 124 125VNET_DEFINE_STATIC(int, log_redirect) = 0; 126#define V_log_redirect VNET(log_redirect) 127SYSCTL_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 131VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]); 132#define V_reply_src VNET(reply_src) 133SYSCTL_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 137VNET_DEFINE_STATIC(int, icmp_rfi) = 0; 138#define V_icmp_rfi VNET(icmp_rfi) 139SYSCTL_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. */ 143VNET_DEFINE_STATIC(int, icmp_quotelen) = 548; 144#define V_icmp_quotelen VNET(icmp_quotelen) 145SYSCTL_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 149VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0; 150#define V_icmpbmcastecho VNET(icmpbmcastecho) 151SYSCTL_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 155VNET_DEFINE_STATIC(int, icmptstamprepl) = 1; 156#define V_icmptstamprepl VNET(icmptstamprepl) 157SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_VNET | CTLFLAG_RW, 158 &VNET_NAME(icmptstamprepl), 0, 159 "Respond to ICMP Timestamp packets"); 160 161VNET_DEFINE_STATIC(int, error_keeptags) = 0; 162#define V_error_keeptags VNET(error_keeptags) 163SYSCTL_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 168int icmpprintfs = 0; 169#endif 170 171static void icmp_reflect(struct mbuf *); 172static void icmp_send(struct mbuf *, struct mbuf *); 173 174extern 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 */ 183void 184kmod_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 */ 194void 195icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 196{ 197 struct ip *oip, *nip; 198 struct icmp *icp; 199 struct mbuf *m; 200 unsigned icmplen, icmpelen, nlen, oiphlen; 201 202 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", 203 __func__)); 204 205 if (type != ICMP_REDIRECT) 206 ICMPSTAT_INC(icps_error); 207 /* 208 * Don't send error: 209 * if the original packet was encrypted. 210 * if not the first fragment of message. 211 * in response to a multicast or broadcast packet. 212 * if the old packet protocol was an ICMP error message. 213 */ 214 if (n->m_flags & M_DECRYPTED) 215 goto freeit; 216 if (n->m_flags & (M_BCAST|M_MCAST)) 217 goto freeit; 218 219 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */ 220 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) 221 goto freeit; 222 oip = mtod(n, struct ip *); 223 oiphlen = oip->ip_hl << 2; 224 if (n->m_len < oiphlen + ICMP_MINLEN) 225 goto freeit; 226#ifdef ICMPPRINTFS 227 if (icmpprintfs) 228 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 229#endif 230 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 231 goto freeit; 232 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 233 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + 234 oiphlen))->icmp_type)) { 235 ICMPSTAT_INC(icps_oldicmp); 236 goto freeit; 237 } 238 /* 239 * Calculate length to quote from original packet and 240 * prevent the ICMP mbuf from overflowing. 241 * Unfortunately this is non-trivial since ip_forward() 242 * sends us truncated packets. 243 */ 244 nlen = m_length(n, NULL); 245 if (oip->ip_p == IPPROTO_TCP) { 246 struct tcphdr *th; 247 int tcphlen; 248 249 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 250 n->m_next == NULL) 251 goto stdreply; 252 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 253 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL) 254 goto freeit; 255 oip = mtod(n, struct ip *); 256 th = mtodo(n, oiphlen); 257 tcphlen = th->th_off << 2; 258 if (tcphlen < sizeof(struct tcphdr)) 259 goto freeit; 260 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 261 goto freeit; 262 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 263 goto stdreply; 264 if (n->m_len < oiphlen + tcphlen && 265 (n = m_pullup(n, oiphlen + tcphlen)) == NULL) 266 goto freeit; 267 icmpelen = max(tcphlen, min(V_icmp_quotelen, 268 ntohs(oip->ip_len) - oiphlen)); 269 } else if (oip->ip_p == IPPROTO_SCTP) { 270 struct sctphdr *sh; 271 struct sctp_chunkhdr *ch; 272 273 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 274 goto stdreply; 275 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 276 n->m_next == NULL) 277 goto stdreply; 278 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 279 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 280 goto freeit; 281 oip = mtod(n, struct ip *); 282 icmpelen = max(sizeof(struct sctphdr), 283 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 284 sh = mtodo(n, oiphlen); 285 if (ntohl(sh->v_tag) == 0 && 286 ntohs(oip->ip_len) >= oiphlen + 287 sizeof(struct sctphdr) + 8 && 288 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 289 n->m_next != NULL)) { 290 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 291 (n = m_pullup(n, oiphlen + 292 sizeof(struct sctphdr) + 8)) == NULL) 293 goto freeit; 294 oip = mtod(n, struct ip *); 295 sh = mtodo(n, oiphlen); 296 ch = (struct sctp_chunkhdr *)(sh + 1); 297 if (ch->chunk_type == SCTP_INITIATION) { 298 icmpelen = max(sizeof(struct sctphdr) + 8, 299 min(V_icmp_quotelen, ntohs(oip->ip_len) - 300 oiphlen)); 301 } 302 } 303 } else 304stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 305 oiphlen)); 306 307 icmplen = min(oiphlen + icmpelen, nlen); 308 if (icmplen < sizeof(struct ip)) 309 goto freeit; 310 311 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 312 m = m_gethdr(M_NOWAIT, MT_DATA); 313 else 314 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 315 if (m == NULL) 316 goto freeit; 317#ifdef MAC 318 mac_netinet_icmp_reply(n, m); 319#endif 320 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 321 sizeof(struct ip) - ICMP_MINLEN); 322 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen); 323 m->m_data += sizeof(struct ip); 324 m->m_len = ICMP_MINLEN + icmplen; 325 326 /* XXX MRT make the outgoing packet use the same FIB 327 * that was associated with the incoming packet 328 */ 329 M_SETFIB(m, M_GETFIB(n)); 330 icp = mtod(m, struct icmp *); 331 ICMPSTAT_INC(icps_outhist[type]); 332 icp->icmp_type = type; 333 if (type == ICMP_REDIRECT) 334 icp->icmp_gwaddr.s_addr = dest; 335 else { 336 icp->icmp_void = 0; 337 /* 338 * The following assignments assume an overlay with the 339 * just zeroed icmp_void field. 340 */ 341 if (type == ICMP_PARAMPROB) { 342 icp->icmp_pptr = code; 343 code = 0; 344 } else if (type == ICMP_UNREACH && 345 code == ICMP_UNREACH_NEEDFRAG && mtu) { 346 icp->icmp_nextmtu = htons(mtu); 347 } 348 } 349 icp->icmp_code = code; 350 351 /* 352 * Copy the quotation into ICMP message and 353 * convert quoted IP header back to network representation. 354 */ 355 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 356 nip = &icp->icmp_ip; 357 358 /* 359 * Set up ICMP message mbuf and copy old IP header (without options 360 * in front of ICMP message. 361 * If the original mbuf was meant to bypass the firewall, the error 362 * reply should bypass as well. 363 */ 364 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 365 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip), 366 ("insufficient space for ip header")); 367 m->m_data -= sizeof(struct ip); 368 m->m_len += sizeof(struct ip); 369 m->m_pkthdr.len = m->m_len; 370 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 371 nip = mtod(m, struct ip *); 372 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 373 nip->ip_len = htons(m->m_len); 374 nip->ip_v = IPVERSION; 375 nip->ip_hl = 5; 376 nip->ip_p = IPPROTO_ICMP; 377 nip->ip_tos = 0; 378 nip->ip_off = 0; 379 380 if (V_error_keeptags) 381 m_tag_copy_chain(m, n, M_NOWAIT); 382 383 icmp_reflect(m); 384 385freeit: 386 m_freem(n); 387} 388 389/* 390 * Process a received ICMP message. 391 */ 392int 393icmp_input(struct mbuf **mp, int *offp, int proto) 394{ 395 struct icmp *icp; 396 struct in_ifaddr *ia; 397 struct mbuf *m = *mp; 398 struct ip *ip = mtod(m, struct ip *); 399 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 400 int hlen = *offp; 401 int icmplen = ntohs(ip->ip_len) - *offp; 402 int i, code; 403 void (*ctlfunc)(int, struct sockaddr *, void *); 404 int fibnum; 405 406 *mp = NULL; 407 408 /* 409 * Locate icmp structure in mbuf, and check 410 * that not corrupted and of at least minimum length. 411 */ 412#ifdef ICMPPRINTFS 413 if (icmpprintfs) { 414 char srcbuf[INET_ADDRSTRLEN]; 415 char dstbuf[INET_ADDRSTRLEN]; 416 417 printf("icmp_input from %s to %s, len %d\n", 418 inet_ntoa_r(ip->ip_src, srcbuf), 419 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 420 } 421#endif 422 NET_EPOCH_ENTER(); 423 if (icmplen < ICMP_MINLEN) { 424 ICMPSTAT_INC(icps_tooshort); 425 goto freeit; 426 } 427 i = hlen + min(icmplen, ICMP_ADVLENMIN); 428 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 429 ICMPSTAT_INC(icps_tooshort); 430 NET_EPOCH_EXIT(); 431 return (IPPROTO_DONE); 432 } 433 ip = mtod(m, struct ip *); 434 m->m_len -= hlen; 435 m->m_data += hlen; 436 icp = mtod(m, struct icmp *); 437 if (in_cksum(m, icmplen)) { 438 ICMPSTAT_INC(icps_checksum); 439 goto freeit; 440 } 441 m->m_len += hlen; 442 m->m_data -= hlen; 443 444#ifdef ICMPPRINTFS 445 if (icmpprintfs) 446 printf("icmp_input, type %d code %d\n", icp->icmp_type, 447 icp->icmp_code); 448#endif 449 450 /* 451 * Message type specific processing. 452 */ 453 if (icp->icmp_type > ICMP_MAXTYPE) 454 goto raw; 455 456 /* Initialize */ 457 bzero(&icmpsrc, sizeof(icmpsrc)); 458 icmpsrc.sin_len = sizeof(struct sockaddr_in); 459 icmpsrc.sin_family = AF_INET; 460 bzero(&icmpdst, sizeof(icmpdst)); 461 icmpdst.sin_len = sizeof(struct sockaddr_in); 462 icmpdst.sin_family = AF_INET; 463 bzero(&icmpgw, sizeof(icmpgw)); 464 icmpgw.sin_len = sizeof(struct sockaddr_in); 465 icmpgw.sin_family = AF_INET; 466 467 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 468 code = icp->icmp_code; 469 switch (icp->icmp_type) { 470 471 case ICMP_UNREACH: 472 switch (code) { 473 case ICMP_UNREACH_NET: 474 case ICMP_UNREACH_HOST: 475 case ICMP_UNREACH_SRCFAIL: 476 case ICMP_UNREACH_NET_UNKNOWN: 477 case ICMP_UNREACH_HOST_UNKNOWN: 478 case ICMP_UNREACH_ISOLATED: 479 case ICMP_UNREACH_TOSNET: 480 case ICMP_UNREACH_TOSHOST: 481 case ICMP_UNREACH_HOST_PRECEDENCE: 482 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 483 code = PRC_UNREACH_NET; 484 break; 485 486 case ICMP_UNREACH_NEEDFRAG: 487 code = PRC_MSGSIZE; 488 break; 489 490 /* 491 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 492 * Treat subcodes 2,3 as immediate RST 493 */ 494 case ICMP_UNREACH_PROTOCOL: 495 code = PRC_UNREACH_PROTOCOL; 496 break; 497 case ICMP_UNREACH_PORT: 498 code = PRC_UNREACH_PORT; 499 break; 500 501 case ICMP_UNREACH_NET_PROHIB: 502 case ICMP_UNREACH_HOST_PROHIB: 503 case ICMP_UNREACH_FILTER_PROHIB: 504 code = PRC_UNREACH_ADMIN_PROHIB; 505 break; 506 507 default: 508 goto badcode; 509 } 510 goto deliver; 511 512 case ICMP_TIMXCEED: 513 if (code > 1) 514 goto badcode; 515 code += PRC_TIMXCEED_INTRANS; 516 goto deliver; 517 518 case ICMP_PARAMPROB: 519 if (code > 1) 520 goto badcode; 521 code = PRC_PARAMPROB; 522 deliver: 523 /* 524 * Problem with datagram; advise higher level routines. 525 */ 526 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 527 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 528 ICMPSTAT_INC(icps_badlen); 529 goto freeit; 530 } 531 /* Discard ICMP's in response to multicast packets */ 532 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 533 goto badcode; 534#ifdef ICMPPRINTFS 535 if (icmpprintfs) 536 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 537#endif 538 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 539 /* 540 * XXX if the packet contains [IPv4 AH TCP], we can't make a 541 * notification to TCP layer. 542 */ 543 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 544 ip_stripoptions(m); 545 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 546 /* This should actually not happen */ 547 ICMPSTAT_INC(icps_tooshort); 548 NET_EPOCH_EXIT(); 549 return (IPPROTO_DONE); 550 } 551 ip = mtod(m, struct ip *); 552 icp = (struct icmp *)(ip + 1); 553 /* 554 * The upper layer handler can rely on: 555 * - The outer IP header has no options. 556 * - The outer IP header, the ICMP header, the inner IP header, 557 * and the first n bytes of the inner payload are contiguous. 558 * n is at least 8, but might be larger based on 559 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 560 */ 561 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 562 if (ctlfunc) 563 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 564 (void *)&icp->icmp_ip); 565 break; 566 567 badcode: 568 ICMPSTAT_INC(icps_badcode); 569 break; 570 571 case ICMP_ECHO: 572 if (!V_icmpbmcastecho 573 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 574 ICMPSTAT_INC(icps_bmcastecho); 575 break; 576 } 577 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 578 goto freeit; 579 icp->icmp_type = ICMP_ECHOREPLY; 580 goto reflect; 581 582 case ICMP_TSTAMP: 583 if (V_icmptstamprepl == 0) 584 break; 585 if (!V_icmpbmcastecho 586 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 587 ICMPSTAT_INC(icps_bmcasttstamp); 588 break; 589 } 590 if (icmplen < ICMP_TSLEN) { 591 ICMPSTAT_INC(icps_badlen); 592 break; 593 } 594 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 595 goto freeit; 596 icp->icmp_type = ICMP_TSTAMPREPLY; 597 icp->icmp_rtime = iptime(); 598 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 599 goto reflect; 600 601 case ICMP_MASKREQ: 602 if (V_icmpmaskrepl == 0) 603 break; 604 /* 605 * We are not able to respond with all ones broadcast 606 * unless we receive it over a point-to-point interface. 607 */ 608 if (icmplen < ICMP_MASKLEN) 609 break; 610 switch (ip->ip_dst.s_addr) { 611 612 case INADDR_BROADCAST: 613 case INADDR_ANY: 614 icmpdst.sin_addr = ip->ip_src; 615 break; 616 617 default: 618 icmpdst.sin_addr = ip->ip_dst; 619 } 620 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 621 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 622 if (ia == NULL) 623 break; 624 if (ia->ia_ifp == NULL) 625 break; 626 icp->icmp_type = ICMP_MASKREPLY; 627 if (V_icmpmaskfake == 0) 628 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 629 else 630 icp->icmp_mask = V_icmpmaskfake; 631 if (ip->ip_src.s_addr == 0) { 632 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 633 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 634 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 635 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 636 } 637reflect: 638 ICMPSTAT_INC(icps_reflect); 639 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 640 icmp_reflect(m); 641 NET_EPOCH_EXIT(); 642 return (IPPROTO_DONE); 643 644 case ICMP_REDIRECT: 645 if (V_log_redirect) { 646 u_long src, dst, gw; 647 648 src = ntohl(ip->ip_src.s_addr); 649 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 650 gw = ntohl(icp->icmp_gwaddr.s_addr); 651 printf("icmp redirect from %d.%d.%d.%d: " 652 "%d.%d.%d.%d => %d.%d.%d.%d\n", 653 (int)(src >> 24), (int)((src >> 16) & 0xff), 654 (int)((src >> 8) & 0xff), (int)(src & 0xff), 655 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 656 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 657 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 658 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 659 } 660 /* 661 * RFC1812 says we must ignore ICMP redirects if we 662 * are acting as router. 663 */ 664 if (V_drop_redirect || V_ipforwarding) 665 break; 666 if (code > 3) 667 goto badcode; 668 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 669 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 670 ICMPSTAT_INC(icps_badlen); 671 break; 672 } 673 /* 674 * Short circuit routing redirects to force 675 * immediate change in the kernel's routing 676 * tables. The message is also handed to anyone 677 * listening on a raw socket (e.g. the routing 678 * daemon for use in updating its tables). 679 */ 680 icmpgw.sin_addr = ip->ip_src; 681 icmpdst.sin_addr = icp->icmp_gwaddr; 682#ifdef ICMPPRINTFS 683 if (icmpprintfs) { 684 char dstbuf[INET_ADDRSTRLEN]; 685 char gwbuf[INET_ADDRSTRLEN]; 686 687 printf("redirect dst %s to %s\n", 688 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 689 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 690 } 691#endif 692 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 693 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 694 in_rtredirect((struct sockaddr *)&icmpsrc, 695 (struct sockaddr *)&icmpdst, 696 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 697 (struct sockaddr *)&icmpgw, fibnum); 698 } 699 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 700 break; 701 702 /* 703 * No kernel processing for the following; 704 * just fall through to send to raw listener. 705 */ 706 case ICMP_ECHOREPLY: 707 case ICMP_ROUTERADVERT: 708 case ICMP_ROUTERSOLICIT: 709 case ICMP_TSTAMPREPLY: 710 case ICMP_IREQREPLY: 711 case ICMP_MASKREPLY: 712 case ICMP_SOURCEQUENCH: 713 default: 714 break; 715 } 716 717raw: 718 NET_EPOCH_EXIT(); 719 *mp = m; 720 rip_input(mp, offp, proto); 721 return (IPPROTO_DONE); 722 723freeit: 724 NET_EPOCH_EXIT(); 725 m_freem(m); 726 return (IPPROTO_DONE); 727} 728 729/* 730 * Reflect the ip packet back to the source 731 */ 732static void 733icmp_reflect(struct mbuf *m) 734{ 735 struct rm_priotracker in_ifa_tracker; 736 struct ip *ip = mtod(m, struct ip *); 737 struct ifaddr *ifa; 738 struct ifnet *ifp; 739 struct in_ifaddr *ia; 740 struct in_addr t; 741 struct nhop4_extended nh_ext; 742 struct mbuf *opts = NULL; 743 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 744 745 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 746 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 747 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 748 m_freem(m); /* Bad return address */ 749 ICMPSTAT_INC(icps_badaddr); 750 goto done; /* Ip_output() will check for broadcast */ 751 } 752 753 t = ip->ip_dst; 754 ip->ip_dst = ip->ip_src; 755 756 /* 757 * Source selection for ICMP replies: 758 * 759 * If the incoming packet was addressed directly to one of our 760 * own addresses, use dst as the src for the reply. 761 */ 762 IN_IFADDR_RLOCK(&in_ifa_tracker); 763 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 764 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 765 t = IA_SIN(ia)->sin_addr; 766 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 767 goto match; 768 } 769 } 770 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 771 772 /* 773 * If the incoming packet was addressed to one of our broadcast 774 * addresses, use the first non-broadcast address which corresponds 775 * to the incoming interface. 776 */ 777 ifp = m->m_pkthdr.rcvif; 778 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 779 IF_ADDR_RLOCK(ifp); 780 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 781 if (ifa->ifa_addr->sa_family != AF_INET) 782 continue; 783 ia = ifatoia(ifa); 784 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 785 t.s_addr) { 786 t = IA_SIN(ia)->sin_addr; 787 IF_ADDR_RUNLOCK(ifp); 788 goto match; 789 } 790 } 791 IF_ADDR_RUNLOCK(ifp); 792 } 793 /* 794 * If the packet was transiting through us, use the address of 795 * the interface the packet came through in. If that interface 796 * doesn't have a suitable IP address, the normal selection 797 * criteria apply. 798 */ 799 if (V_icmp_rfi && ifp != NULL) { 800 IF_ADDR_RLOCK(ifp); 801 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 802 if (ifa->ifa_addr->sa_family != AF_INET) 803 continue; 804 ia = ifatoia(ifa); 805 t = IA_SIN(ia)->sin_addr; 806 IF_ADDR_RUNLOCK(ifp); 807 goto match; 808 } 809 IF_ADDR_RUNLOCK(ifp); 810 } 811 /* 812 * If the incoming packet was not addressed directly to us, use 813 * designated interface for icmp replies specified by sysctl 814 * net.inet.icmp.reply_src (default not set). Otherwise continue 815 * with normal source selection. 816 */ 817 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 818 IF_ADDR_RLOCK(ifp); 819 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 820 if (ifa->ifa_addr->sa_family != AF_INET) 821 continue; 822 ia = ifatoia(ifa); 823 t = IA_SIN(ia)->sin_addr; 824 IF_ADDR_RUNLOCK(ifp); 825 goto match; 826 } 827 IF_ADDR_RUNLOCK(ifp); 828 } 829 /* 830 * If the packet was transiting through us, use the address of 831 * the interface that is the closest to the packet source. 832 * When we don't have a route back to the packet source, stop here 833 * and drop the packet. 834 */ 835 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 836 m_freem(m); 837 ICMPSTAT_INC(icps_noroute); 838 goto done; 839 } 840 t = nh_ext.nh_src; 841match: 842#ifdef MAC 843 mac_netinet_icmp_replyinplace(m); 844#endif 845 ip->ip_src = t; 846 ip->ip_ttl = V_ip_defttl; 847 848 if (optlen > 0) { 849 u_char *cp; 850 int opt, cnt; 851 u_int len; 852 853 /* 854 * Retrieve any source routing from the incoming packet; 855 * add on any record-route or timestamp options. 856 */ 857 cp = (u_char *) (ip + 1); 858 if ((opts = ip_srcroute(m)) == NULL && 859 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 860 opts->m_len = sizeof(struct in_addr); 861 mtod(opts, struct in_addr *)->s_addr = 0; 862 } 863 if (opts) { 864#ifdef ICMPPRINTFS 865 if (icmpprintfs) 866 printf("icmp_reflect optlen %d rt %d => ", 867 optlen, opts->m_len); 868#endif 869 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 870 opt = cp[IPOPT_OPTVAL]; 871 if (opt == IPOPT_EOL) 872 break; 873 if (opt == IPOPT_NOP) 874 len = 1; 875 else { 876 if (cnt < IPOPT_OLEN + sizeof(*cp)) 877 break; 878 len = cp[IPOPT_OLEN]; 879 if (len < IPOPT_OLEN + sizeof(*cp) || 880 len > cnt) 881 break; 882 } 883 /* 884 * Should check for overflow, but it "can't happen" 885 */ 886 if (opt == IPOPT_RR || opt == IPOPT_TS || 887 opt == IPOPT_SECURITY) { 888 bcopy((caddr_t)cp, 889 mtod(opts, caddr_t) + opts->m_len, len); 890 opts->m_len += len; 891 } 892 } 893 /* Terminate & pad, if necessary */ 894 cnt = opts->m_len % 4; 895 if (cnt) { 896 for (; cnt < 4; cnt++) { 897 *(mtod(opts, caddr_t) + opts->m_len) = 898 IPOPT_EOL; 899 opts->m_len++; 900 } 901 } 902#ifdef ICMPPRINTFS 903 if (icmpprintfs) 904 printf("%d\n", opts->m_len); 905#endif 906 } 907 ip_stripoptions(m); 908 } 909 m_tag_delete_nonpersistent(m); 910 m->m_flags &= ~(M_BCAST|M_MCAST); 911 icmp_send(m, opts); 912done: 913 if (opts) 914 (void)m_free(opts); 915} 916 917/* 918 * Send an icmp packet back to the ip level, 919 * after supplying a checksum. 920 */ 921static void 922icmp_send(struct mbuf *m, struct mbuf *opts) 923{ 924 struct ip *ip = mtod(m, struct ip *); 925 int hlen; 926 struct icmp *icp; 927 928 hlen = ip->ip_hl << 2; 929 m->m_data += hlen; 930 m->m_len -= hlen; 931 icp = mtod(m, struct icmp *); 932 icp->icmp_cksum = 0; 933 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 934 m->m_data -= hlen; 935 m->m_len += hlen; 936 m->m_pkthdr.rcvif = (struct ifnet *)0; 937#ifdef ICMPPRINTFS 938 if (icmpprintfs) { 939 char dstbuf[INET_ADDRSTRLEN]; 940 char srcbuf[INET_ADDRSTRLEN]; 941 942 printf("icmp_send dst %s src %s\n", 943 inet_ntoa_r(ip->ip_dst, dstbuf), 944 inet_ntoa_r(ip->ip_src, srcbuf)); 945 } 946#endif 947 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 948} 949 950/* 951 * Return milliseconds since 00:00 UTC in network format. 952 */ 953uint32_t 954iptime(void) 955{ 956 struct timeval atv; 957 u_long t; 958 959 getmicrotime(&atv); 960 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 961 return (htonl(t)); 962} 963 964/* 965 * Return the next larger or smaller MTU plateau (table from RFC 1191) 966 * given current value MTU. If DIR is less than zero, a larger plateau 967 * is returned; otherwise, a smaller value is returned. 968 */ 969int 970ip_next_mtu(int mtu, int dir) 971{ 972 static int mtutab[] = { 973 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 974 296, 68, 0 975 }; 976 int i, size; 977 978 size = (sizeof mtutab) / (sizeof mtutab[0]); 979 if (dir >= 0) { 980 for (i = 0; i < size; i++) 981 if (mtu > mtutab[i]) 982 return mtutab[i]; 983 } else { 984 for (i = size - 1; i >= 0; i--) 985 if (mtu < mtutab[i]) 986 return mtutab[i]; 987 if (mtu == mtutab[0]) 988 return mtutab[0]; 989 } 990 return 0; 991} 992#endif /* INET */ 993 994 995/* 996 * badport_bandlim() - check for ICMP bandwidth limit 997 * 998 * Return 0 if it is ok to send an ICMP error response, -1 if we have 999 * hit our bandwidth limit and it is not ok. 1000 * 1001 * If icmplim is <= 0, the feature is disabled and 0 is returned. 1002 * 1003 * For now we separate the TCP and UDP subsystems w/ different 'which' 1004 * values. We may eventually remove this separation (and simplify the 1005 * code further). 1006 * 1007 * Note that the printing of the error message is delayed so we can 1008 * properly print the icmp error rate that the system was trying to do 1009 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 1010 * the 'final' error, but it doesn't make sense to solve the printing 1011 * delay with more complex code. 1012 */ 1013struct icmp_rate { 1014 const char *descr; 1015 struct counter_rate cr; 1016}; 1017VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 1018 { "icmp unreach response" }, 1019 { "icmp ping response" }, 1020 { "icmp tstamp response" }, 1021 { "closed port RST response" }, 1022 { "open port RST response" }, 1023 { "icmp6 unreach response" }, 1024 { "sctp ootb response" } 1025}; 1026#define V_icmp_rates VNET(icmp_rates) 1027 1028static void 1029icmp_bandlimit_init(void) 1030{ 1031 1032 for (int i = 0; i < BANDLIM_MAX; i++) { 1033 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 1034 V_icmp_rates[i].cr.cr_ticks = ticks; 1035 } 1036} 1037VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1038 icmp_bandlimit_init, NULL); 1039 1040static void 1041icmp_bandlimit_uninit(void) 1042{ 1043 1044 for (int i = 0; i < BANDLIM_MAX; i++) 1045 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1046} 1047VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1048 icmp_bandlimit_uninit, NULL); 1049 1050int 1051badport_bandlim(int which) 1052{ 1053 int64_t pps; 1054 1055 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1056 return (0); 1057 1058 KASSERT(which >= 0 && which < BANDLIM_MAX, 1059 ("%s: which %d", __func__, which)); 1060 1061 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1062 if (pps == -1) 1063 return (-1); 1064 if (pps > 0 && V_icmplim_output) 1065 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1066 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1067 return (0); 1068} 1069