ip_icmp.c revision 330897
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 * 4. 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: stable/11/sys/netinet/ip_icmp.c 330897 2018-03-14 03:19:51Z eadler $"); 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#ifdef INET 73 74#include <machine/in_cksum.h> 75 76#include <security/mac/mac_framework.h> 77#endif /* INET */ 78 79/* 80 * ICMP routines: error generation, receive packet processing, and 81 * routines to turnaround packets back to the originator, and 82 * host table maintenance routines. 83 */ 84static VNET_DEFINE(int, icmplim) = 200; 85#define V_icmplim VNET(icmplim) 86SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, 87 &VNET_NAME(icmplim), 0, 88 "Maximum number of ICMP responses per second"); 89 90static VNET_DEFINE(int, icmplim_output) = 1; 91#define V_icmplim_output VNET(icmplim_output) 92SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW, 93 &VNET_NAME(icmplim_output), 0, 94 "Enable logging of ICMP response rate limiting"); 95 96#ifdef INET 97VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 98VNET_PCPUSTAT_SYSINIT(icmpstat); 99SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 100 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 101 102#ifdef VIMAGE 103VNET_PCPUSTAT_SYSUNINIT(icmpstat); 104#endif /* VIMAGE */ 105 106static VNET_DEFINE(int, icmpmaskrepl) = 0; 107#define V_icmpmaskrepl VNET(icmpmaskrepl) 108SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 109 &VNET_NAME(icmpmaskrepl), 0, 110 "Reply to ICMP Address Mask Request packets"); 111 112static VNET_DEFINE(u_int, icmpmaskfake) = 0; 113#define V_icmpmaskfake VNET(icmpmaskfake) 114SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW, 115 &VNET_NAME(icmpmaskfake), 0, 116 "Fake reply to ICMP Address Mask Request packets"); 117 118VNET_DEFINE(int, drop_redirect) = 0; 119#define V_drop_redirect VNET(drop_redirect) 120SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 121 &VNET_NAME(drop_redirect), 0, 122 "Ignore ICMP redirects"); 123 124static VNET_DEFINE(int, log_redirect) = 0; 125#define V_log_redirect VNET(log_redirect) 126SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW, 127 &VNET_NAME(log_redirect), 0, 128 "Log ICMP redirects to the console"); 129 130static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 131#define V_reply_src VNET(reply_src) 132SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW, 133 &VNET_NAME(reply_src), IFNAMSIZ, 134 "ICMP reply source for non-local packets"); 135 136static VNET_DEFINE(int, icmp_rfi) = 0; 137#define V_icmp_rfi VNET(icmp_rfi) 138SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW, 139 &VNET_NAME(icmp_rfi), 0, 140 "ICMP reply from incoming interface for non-local packets"); 141 142static VNET_DEFINE(int, icmp_quotelen) = 8; 143#define V_icmp_quotelen VNET(icmp_quotelen) 144SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW, 145 &VNET_NAME(icmp_quotelen), 0, 146 "Number of bytes from original packet to quote in ICMP reply"); 147 148static VNET_DEFINE(int, icmpbmcastecho) = 0; 149#define V_icmpbmcastecho VNET(icmpbmcastecho) 150SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 151 &VNET_NAME(icmpbmcastecho), 0, 152 "Reply to multicast ICMP Echo Request and Timestamp packets"); 153 154static VNET_DEFINE(int, icmptstamprepl) = 1; 155#define V_icmptstamprepl VNET(icmptstamprepl) 156SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 157 &VNET_NAME(icmptstamprepl), 0, 158 "Respond to ICMP Timestamp packets"); 159 160#ifdef ICMPPRINTFS 161int icmpprintfs = 0; 162#endif 163 164static void icmp_reflect(struct mbuf *); 165static void icmp_send(struct mbuf *, struct mbuf *); 166 167extern struct protosw inetsw[]; 168 169/* 170 * Kernel module interface for updating icmpstat. The argument is an index 171 * into icmpstat treated as an array of u_long. While this encodes the 172 * general layout of icmpstat into the caller, it doesn't encode its 173 * location, so that future changes to add, for example, per-CPU stats 174 * support won't cause binary compatibility problems for kernel modules. 175 */ 176void 177kmod_icmpstat_inc(int statnum) 178{ 179 180 counter_u64_add(VNET(icmpstat)[statnum], 1); 181} 182 183/* 184 * Generate an error packet of type error 185 * in response to bad packet ip. 186 */ 187void 188icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 189{ 190 struct ip *oip, *nip; 191 struct icmp *icp; 192 struct mbuf *m; 193 unsigned icmplen, icmpelen, nlen, oiphlen; 194 195 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", 196 __func__)); 197 198 if (type != ICMP_REDIRECT) 199 ICMPSTAT_INC(icps_error); 200 /* 201 * Don't send error: 202 * if the original packet was encrypted. 203 * if not the first fragment of message. 204 * in response to a multicast or broadcast packet. 205 * if the old packet protocol was an ICMP error message. 206 */ 207 if (n->m_flags & M_DECRYPTED) 208 goto freeit; 209 if (n->m_flags & (M_BCAST|M_MCAST)) 210 goto freeit; 211 212 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */ 213 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) 214 goto freeit; 215 oip = mtod(n, struct ip *); 216 oiphlen = oip->ip_hl << 2; 217 if (n->m_len < oiphlen + ICMP_MINLEN) 218 goto freeit; 219#ifdef ICMPPRINTFS 220 if (icmpprintfs) 221 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 222#endif 223 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 224 goto freeit; 225 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 226 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + 227 oiphlen))->icmp_type)) { 228 ICMPSTAT_INC(icps_oldicmp); 229 goto freeit; 230 } 231 /* 232 * Calculate length to quote from original packet and 233 * prevent the ICMP mbuf from overflowing. 234 * Unfortunately this is non-trivial since ip_forward() 235 * sends us truncated packets. 236 */ 237 nlen = m_length(n, NULL); 238 if (oip->ip_p == IPPROTO_TCP) { 239 struct tcphdr *th; 240 int tcphlen; 241 242 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 243 n->m_next == NULL) 244 goto stdreply; 245 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 246 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL) 247 goto freeit; 248 oip = mtod(n, struct ip *); 249 th = mtodo(n, oiphlen); 250 tcphlen = th->th_off << 2; 251 if (tcphlen < sizeof(struct tcphdr)) 252 goto freeit; 253 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 254 goto freeit; 255 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 256 goto stdreply; 257 if (n->m_len < oiphlen + tcphlen && 258 (n = m_pullup(n, oiphlen + tcphlen)) == NULL) 259 goto freeit; 260 icmpelen = max(tcphlen, min(V_icmp_quotelen, 261 ntohs(oip->ip_len) - oiphlen)); 262 } else if (oip->ip_p == IPPROTO_SCTP) { 263 struct sctphdr *sh; 264 struct sctp_chunkhdr *ch; 265 266 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 267 goto stdreply; 268 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 269 n->m_next == NULL) 270 goto stdreply; 271 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 272 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 273 goto freeit; 274 oip = mtod(n, struct ip *); 275 icmpelen = max(sizeof(struct sctphdr), 276 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 277 sh = mtodo(n, oiphlen); 278 if (ntohl(sh->v_tag) == 0 && 279 ntohs(oip->ip_len) >= oiphlen + 280 sizeof(struct sctphdr) + 8 && 281 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 282 n->m_next != NULL)) { 283 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 284 (n = m_pullup(n, oiphlen + 285 sizeof(struct sctphdr) + 8)) == NULL) 286 goto freeit; 287 oip = mtod(n, struct ip *); 288 sh = mtodo(n, oiphlen); 289 ch = (struct sctp_chunkhdr *)(sh + 1); 290 if (ch->chunk_type == SCTP_INITIATION) { 291 icmpelen = max(sizeof(struct sctphdr) + 8, 292 min(V_icmp_quotelen, ntohs(oip->ip_len) - 293 oiphlen)); 294 } 295 } 296 } else 297stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 298 oiphlen)); 299 300 icmplen = min(oiphlen + icmpelen, nlen); 301 if (icmplen < sizeof(struct ip)) 302 goto freeit; 303 304 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 305 m = m_gethdr(M_NOWAIT, MT_DATA); 306 else 307 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 308 if (m == NULL) 309 goto freeit; 310#ifdef MAC 311 mac_netinet_icmp_reply(n, m); 312#endif 313 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 314 sizeof(struct ip) - ICMP_MINLEN); 315 m_align(m, ICMP_MINLEN + icmplen); 316 m->m_len = ICMP_MINLEN + icmplen; 317 318 /* XXX MRT make the outgoing packet use the same FIB 319 * that was associated with the incoming packet 320 */ 321 M_SETFIB(m, M_GETFIB(n)); 322 icp = mtod(m, struct icmp *); 323 ICMPSTAT_INC(icps_outhist[type]); 324 icp->icmp_type = type; 325 if (type == ICMP_REDIRECT) 326 icp->icmp_gwaddr.s_addr = dest; 327 else { 328 icp->icmp_void = 0; 329 /* 330 * The following assignments assume an overlay with the 331 * just zeroed icmp_void field. 332 */ 333 if (type == ICMP_PARAMPROB) { 334 icp->icmp_pptr = code; 335 code = 0; 336 } else if (type == ICMP_UNREACH && 337 code == ICMP_UNREACH_NEEDFRAG && mtu) { 338 icp->icmp_nextmtu = htons(mtu); 339 } 340 } 341 icp->icmp_code = code; 342 343 /* 344 * Copy the quotation into ICMP message and 345 * convert quoted IP header back to network representation. 346 */ 347 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 348 nip = &icp->icmp_ip; 349 350 /* 351 * Set up ICMP message mbuf and copy old IP header (without options 352 * in front of ICMP message. 353 * If the original mbuf was meant to bypass the firewall, the error 354 * reply should bypass as well. 355 */ 356 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 357 m->m_data -= sizeof(struct ip); 358 m->m_len += sizeof(struct ip); 359 m->m_pkthdr.len = m->m_len; 360 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 361 nip = mtod(m, struct ip *); 362 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 363 nip->ip_len = htons(m->m_len); 364 nip->ip_v = IPVERSION; 365 nip->ip_hl = 5; 366 nip->ip_p = IPPROTO_ICMP; 367 nip->ip_tos = 0; 368 nip->ip_off = 0; 369 icmp_reflect(m); 370 371freeit: 372 m_freem(n); 373} 374 375/* 376 * Process a received ICMP message. 377 */ 378int 379icmp_input(struct mbuf **mp, int *offp, int proto) 380{ 381 struct icmp *icp; 382 struct in_ifaddr *ia; 383 struct mbuf *m = *mp; 384 struct ip *ip = mtod(m, struct ip *); 385 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 386 int hlen = *offp; 387 int icmplen = ntohs(ip->ip_len) - *offp; 388 int i, code; 389 void (*ctlfunc)(int, struct sockaddr *, void *); 390 int fibnum; 391 392 *mp = NULL; 393 394 /* 395 * Locate icmp structure in mbuf, and check 396 * that not corrupted and of at least minimum length. 397 */ 398#ifdef ICMPPRINTFS 399 if (icmpprintfs) { 400 char srcbuf[INET_ADDRSTRLEN]; 401 char dstbuf[INET_ADDRSTRLEN]; 402 403 printf("icmp_input from %s to %s, len %d\n", 404 inet_ntoa_r(ip->ip_src, srcbuf), 405 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 406 } 407#endif 408 if (icmplen < ICMP_MINLEN) { 409 ICMPSTAT_INC(icps_tooshort); 410 goto freeit; 411 } 412 i = hlen + min(icmplen, ICMP_ADVLENMIN); 413 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 414 ICMPSTAT_INC(icps_tooshort); 415 return (IPPROTO_DONE); 416 } 417 ip = mtod(m, struct ip *); 418 m->m_len -= hlen; 419 m->m_data += hlen; 420 icp = mtod(m, struct icmp *); 421 if (in_cksum(m, icmplen)) { 422 ICMPSTAT_INC(icps_checksum); 423 goto freeit; 424 } 425 m->m_len += hlen; 426 m->m_data -= hlen; 427 428#ifdef ICMPPRINTFS 429 if (icmpprintfs) 430 printf("icmp_input, type %d code %d\n", icp->icmp_type, 431 icp->icmp_code); 432#endif 433 434 /* 435 * Message type specific processing. 436 */ 437 if (icp->icmp_type > ICMP_MAXTYPE) 438 goto raw; 439 440 /* Initialize */ 441 bzero(&icmpsrc, sizeof(icmpsrc)); 442 icmpsrc.sin_len = sizeof(struct sockaddr_in); 443 icmpsrc.sin_family = AF_INET; 444 bzero(&icmpdst, sizeof(icmpdst)); 445 icmpdst.sin_len = sizeof(struct sockaddr_in); 446 icmpdst.sin_family = AF_INET; 447 bzero(&icmpgw, sizeof(icmpgw)); 448 icmpgw.sin_len = sizeof(struct sockaddr_in); 449 icmpgw.sin_family = AF_INET; 450 451 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 452 code = icp->icmp_code; 453 switch (icp->icmp_type) { 454 455 case ICMP_UNREACH: 456 switch (code) { 457 case ICMP_UNREACH_NET: 458 case ICMP_UNREACH_HOST: 459 case ICMP_UNREACH_SRCFAIL: 460 case ICMP_UNREACH_NET_UNKNOWN: 461 case ICMP_UNREACH_HOST_UNKNOWN: 462 case ICMP_UNREACH_ISOLATED: 463 case ICMP_UNREACH_TOSNET: 464 case ICMP_UNREACH_TOSHOST: 465 case ICMP_UNREACH_HOST_PRECEDENCE: 466 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 467 code = PRC_UNREACH_NET; 468 break; 469 470 case ICMP_UNREACH_NEEDFRAG: 471 code = PRC_MSGSIZE; 472 break; 473 474 /* 475 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 476 * Treat subcodes 2,3 as immediate RST 477 */ 478 case ICMP_UNREACH_PROTOCOL: 479 code = PRC_UNREACH_PROTOCOL; 480 break; 481 case ICMP_UNREACH_PORT: 482 code = PRC_UNREACH_PORT; 483 break; 484 485 case ICMP_UNREACH_NET_PROHIB: 486 case ICMP_UNREACH_HOST_PROHIB: 487 case ICMP_UNREACH_FILTER_PROHIB: 488 code = PRC_UNREACH_ADMIN_PROHIB; 489 break; 490 491 default: 492 goto badcode; 493 } 494 goto deliver; 495 496 case ICMP_TIMXCEED: 497 if (code > 1) 498 goto badcode; 499 code += PRC_TIMXCEED_INTRANS; 500 goto deliver; 501 502 case ICMP_PARAMPROB: 503 if (code > 1) 504 goto badcode; 505 code = PRC_PARAMPROB; 506 deliver: 507 /* 508 * Problem with datagram; advise higher level routines. 509 */ 510 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 511 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 512 ICMPSTAT_INC(icps_badlen); 513 goto freeit; 514 } 515 /* Discard ICMP's in response to multicast packets */ 516 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 517 goto badcode; 518#ifdef ICMPPRINTFS 519 if (icmpprintfs) 520 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 521#endif 522 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 523 /* 524 * XXX if the packet contains [IPv4 AH TCP], we can't make a 525 * notification to TCP layer. 526 */ 527 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 528 ip_stripoptions(m); 529 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 530 /* This should actually not happen */ 531 ICMPSTAT_INC(icps_tooshort); 532 return (IPPROTO_DONE); 533 } 534 ip = mtod(m, struct ip *); 535 icp = (struct icmp *)(ip + 1); 536 /* 537 * The upper layer handler can rely on: 538 * - The outer IP header has no options. 539 * - The outer IP header, the ICMP header, the inner IP header, 540 * and the first n bytes of the inner payload are contiguous. 541 * n is at least 8, but might be larger based on 542 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 543 */ 544 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 545 if (ctlfunc) 546 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 547 (void *)&icp->icmp_ip); 548 break; 549 550 badcode: 551 ICMPSTAT_INC(icps_badcode); 552 break; 553 554 case ICMP_ECHO: 555 if (!V_icmpbmcastecho 556 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 557 ICMPSTAT_INC(icps_bmcastecho); 558 break; 559 } 560 icp->icmp_type = ICMP_ECHOREPLY; 561 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 562 goto freeit; 563 else 564 goto reflect; 565 566 case ICMP_TSTAMP: 567 if (V_icmptstamprepl == 0) 568 break; 569 if (!V_icmpbmcastecho 570 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 571 ICMPSTAT_INC(icps_bmcasttstamp); 572 break; 573 } 574 if (icmplen < ICMP_TSLEN) { 575 ICMPSTAT_INC(icps_badlen); 576 break; 577 } 578 icp->icmp_type = ICMP_TSTAMPREPLY; 579 icp->icmp_rtime = iptime(); 580 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 581 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 582 goto freeit; 583 else 584 goto reflect; 585 586 case ICMP_MASKREQ: 587 if (V_icmpmaskrepl == 0) 588 break; 589 /* 590 * We are not able to respond with all ones broadcast 591 * unless we receive it over a point-to-point interface. 592 */ 593 if (icmplen < ICMP_MASKLEN) 594 break; 595 switch (ip->ip_dst.s_addr) { 596 597 case INADDR_BROADCAST: 598 case INADDR_ANY: 599 icmpdst.sin_addr = ip->ip_src; 600 break; 601 602 default: 603 icmpdst.sin_addr = ip->ip_dst; 604 } 605 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 606 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 607 if (ia == NULL) 608 break; 609 if (ia->ia_ifp == NULL) { 610 ifa_free(&ia->ia_ifa); 611 break; 612 } 613 icp->icmp_type = ICMP_MASKREPLY; 614 if (V_icmpmaskfake == 0) 615 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 616 else 617 icp->icmp_mask = V_icmpmaskfake; 618 if (ip->ip_src.s_addr == 0) { 619 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 620 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 621 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 622 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 623 } 624 ifa_free(&ia->ia_ifa); 625reflect: 626 ICMPSTAT_INC(icps_reflect); 627 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 628 icmp_reflect(m); 629 return (IPPROTO_DONE); 630 631 case ICMP_REDIRECT: 632 if (V_log_redirect) { 633 u_long src, dst, gw; 634 635 src = ntohl(ip->ip_src.s_addr); 636 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 637 gw = ntohl(icp->icmp_gwaddr.s_addr); 638 printf("icmp redirect from %d.%d.%d.%d: " 639 "%d.%d.%d.%d => %d.%d.%d.%d\n", 640 (int)(src >> 24), (int)((src >> 16) & 0xff), 641 (int)((src >> 8) & 0xff), (int)(src & 0xff), 642 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 643 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 644 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 645 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 646 } 647 /* 648 * RFC1812 says we must ignore ICMP redirects if we 649 * are acting as router. 650 */ 651 if (V_drop_redirect || V_ipforwarding) 652 break; 653 if (code > 3) 654 goto badcode; 655 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 656 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 657 ICMPSTAT_INC(icps_badlen); 658 break; 659 } 660 /* 661 * Short circuit routing redirects to force 662 * immediate change in the kernel's routing 663 * tables. The message is also handed to anyone 664 * listening on a raw socket (e.g. the routing 665 * daemon for use in updating its tables). 666 */ 667 icmpgw.sin_addr = ip->ip_src; 668 icmpdst.sin_addr = icp->icmp_gwaddr; 669#ifdef ICMPPRINTFS 670 if (icmpprintfs) { 671 char dstbuf[INET_ADDRSTRLEN]; 672 char gwbuf[INET_ADDRSTRLEN]; 673 674 printf("redirect dst %s to %s\n", 675 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 676 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 677 } 678#endif 679 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 680 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 681 in_rtredirect((struct sockaddr *)&icmpsrc, 682 (struct sockaddr *)&icmpdst, 683 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 684 (struct sockaddr *)&icmpgw, fibnum); 685 } 686 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 687 break; 688 689 /* 690 * No kernel processing for the following; 691 * just fall through to send to raw listener. 692 */ 693 case ICMP_ECHOREPLY: 694 case ICMP_ROUTERADVERT: 695 case ICMP_ROUTERSOLICIT: 696 case ICMP_TSTAMPREPLY: 697 case ICMP_IREQREPLY: 698 case ICMP_MASKREPLY: 699 case ICMP_SOURCEQUENCH: 700 default: 701 break; 702 } 703 704raw: 705 *mp = m; 706 rip_input(mp, offp, proto); 707 return (IPPROTO_DONE); 708 709freeit: 710 m_freem(m); 711 return (IPPROTO_DONE); 712} 713 714/* 715 * Reflect the ip packet back to the source 716 */ 717static void 718icmp_reflect(struct mbuf *m) 719{ 720 struct rm_priotracker in_ifa_tracker; 721 struct ip *ip = mtod(m, struct ip *); 722 struct ifaddr *ifa; 723 struct ifnet *ifp; 724 struct in_ifaddr *ia; 725 struct in_addr t; 726 struct nhop4_extended nh_ext; 727 struct mbuf *opts = NULL; 728 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 729 730 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 731 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 732 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 733 m_freem(m); /* Bad return address */ 734 ICMPSTAT_INC(icps_badaddr); 735 goto done; /* Ip_output() will check for broadcast */ 736 } 737 738 t = ip->ip_dst; 739 ip->ip_dst = ip->ip_src; 740 741 /* 742 * Source selection for ICMP replies: 743 * 744 * If the incoming packet was addressed directly to one of our 745 * own addresses, use dst as the src for the reply. 746 */ 747 IN_IFADDR_RLOCK(&in_ifa_tracker); 748 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 749 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 750 t = IA_SIN(ia)->sin_addr; 751 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 752 goto match; 753 } 754 } 755 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 756 757 /* 758 * If the incoming packet was addressed to one of our broadcast 759 * addresses, use the first non-broadcast address which corresponds 760 * to the incoming interface. 761 */ 762 ifp = m->m_pkthdr.rcvif; 763 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 764 IF_ADDR_RLOCK(ifp); 765 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 766 if (ifa->ifa_addr->sa_family != AF_INET) 767 continue; 768 ia = ifatoia(ifa); 769 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 770 t.s_addr) { 771 t = IA_SIN(ia)->sin_addr; 772 IF_ADDR_RUNLOCK(ifp); 773 goto match; 774 } 775 } 776 IF_ADDR_RUNLOCK(ifp); 777 } 778 /* 779 * If the packet was transiting through us, use the address of 780 * the interface the packet came through in. If that interface 781 * doesn't have a suitable IP address, the normal selection 782 * criteria apply. 783 */ 784 if (V_icmp_rfi && ifp != NULL) { 785 IF_ADDR_RLOCK(ifp); 786 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 787 if (ifa->ifa_addr->sa_family != AF_INET) 788 continue; 789 ia = ifatoia(ifa); 790 t = IA_SIN(ia)->sin_addr; 791 IF_ADDR_RUNLOCK(ifp); 792 goto match; 793 } 794 IF_ADDR_RUNLOCK(ifp); 795 } 796 /* 797 * If the incoming packet was not addressed directly to us, use 798 * designated interface for icmp replies specified by sysctl 799 * net.inet.icmp.reply_src (default not set). Otherwise continue 800 * with normal source selection. 801 */ 802 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 803 IF_ADDR_RLOCK(ifp); 804 TAILQ_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 IF_ADDR_RUNLOCK(ifp); 810 goto match; 811 } 812 IF_ADDR_RUNLOCK(ifp); 813 } 814 /* 815 * If the packet was transiting through us, use the address of 816 * the interface that is the closest to the packet source. 817 * When we don't have a route back to the packet source, stop here 818 * and drop the packet. 819 */ 820 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 821 m_freem(m); 822 ICMPSTAT_INC(icps_noroute); 823 goto done; 824 } 825 t = nh_ext.nh_src; 826match: 827#ifdef MAC 828 mac_netinet_icmp_replyinplace(m); 829#endif 830 ip->ip_src = t; 831 ip->ip_ttl = V_ip_defttl; 832 833 if (optlen > 0) { 834 register u_char *cp; 835 int opt, cnt; 836 u_int len; 837 838 /* 839 * Retrieve any source routing from the incoming packet; 840 * add on any record-route or timestamp options. 841 */ 842 cp = (u_char *) (ip + 1); 843 if ((opts = ip_srcroute(m)) == NULL && 844 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 845 opts->m_len = sizeof(struct in_addr); 846 mtod(opts, struct in_addr *)->s_addr = 0; 847 } 848 if (opts) { 849#ifdef ICMPPRINTFS 850 if (icmpprintfs) 851 printf("icmp_reflect optlen %d rt %d => ", 852 optlen, opts->m_len); 853#endif 854 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 855 opt = cp[IPOPT_OPTVAL]; 856 if (opt == IPOPT_EOL) 857 break; 858 if (opt == IPOPT_NOP) 859 len = 1; 860 else { 861 if (cnt < IPOPT_OLEN + sizeof(*cp)) 862 break; 863 len = cp[IPOPT_OLEN]; 864 if (len < IPOPT_OLEN + sizeof(*cp) || 865 len > cnt) 866 break; 867 } 868 /* 869 * Should check for overflow, but it "can't happen" 870 */ 871 if (opt == IPOPT_RR || opt == IPOPT_TS || 872 opt == IPOPT_SECURITY) { 873 bcopy((caddr_t)cp, 874 mtod(opts, caddr_t) + opts->m_len, len); 875 opts->m_len += len; 876 } 877 } 878 /* Terminate & pad, if necessary */ 879 cnt = opts->m_len % 4; 880 if (cnt) { 881 for (; cnt < 4; cnt++) { 882 *(mtod(opts, caddr_t) + opts->m_len) = 883 IPOPT_EOL; 884 opts->m_len++; 885 } 886 } 887#ifdef ICMPPRINTFS 888 if (icmpprintfs) 889 printf("%d\n", opts->m_len); 890#endif 891 } 892 ip_stripoptions(m); 893 } 894 m_tag_delete_nonpersistent(m); 895 m->m_flags &= ~(M_BCAST|M_MCAST); 896 icmp_send(m, opts); 897done: 898 if (opts) 899 (void)m_free(opts); 900} 901 902/* 903 * Send an icmp packet back to the ip level, 904 * after supplying a checksum. 905 */ 906static void 907icmp_send(struct mbuf *m, struct mbuf *opts) 908{ 909 register struct ip *ip = mtod(m, struct ip *); 910 register int hlen; 911 register struct icmp *icp; 912 913 hlen = ip->ip_hl << 2; 914 m->m_data += hlen; 915 m->m_len -= hlen; 916 icp = mtod(m, struct icmp *); 917 icp->icmp_cksum = 0; 918 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 919 m->m_data -= hlen; 920 m->m_len += hlen; 921 m->m_pkthdr.rcvif = (struct ifnet *)0; 922#ifdef ICMPPRINTFS 923 if (icmpprintfs) { 924 char dstbuf[INET_ADDRSTRLEN]; 925 char srcbuf[INET_ADDRSTRLEN]; 926 927 printf("icmp_send dst %s src %s\n", 928 inet_ntoa_r(ip->ip_dst, dstbuf), 929 inet_ntoa_r(ip->ip_src, srcbuf)); 930 } 931#endif 932 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 933} 934 935/* 936 * Return milliseconds since 00:00 UTC in network format. 937 */ 938uint32_t 939iptime(void) 940{ 941 struct timeval atv; 942 u_long t; 943 944 getmicrotime(&atv); 945 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 946 return (htonl(t)); 947} 948 949/* 950 * Return the next larger or smaller MTU plateau (table from RFC 1191) 951 * given current value MTU. If DIR is less than zero, a larger plateau 952 * is returned; otherwise, a smaller value is returned. 953 */ 954int 955ip_next_mtu(int mtu, int dir) 956{ 957 static int mtutab[] = { 958 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 959 296, 68, 0 960 }; 961 int i, size; 962 963 size = (sizeof mtutab) / (sizeof mtutab[0]); 964 if (dir >= 0) { 965 for (i = 0; i < size; i++) 966 if (mtu > mtutab[i]) 967 return mtutab[i]; 968 } else { 969 for (i = size - 1; i >= 0; i--) 970 if (mtu < mtutab[i]) 971 return mtutab[i]; 972 if (mtu == mtutab[0]) 973 return mtutab[0]; 974 } 975 return 0; 976} 977#endif /* INET */ 978 979 980/* 981 * badport_bandlim() - check for ICMP bandwidth limit 982 * 983 * Return 0 if it is ok to send an ICMP error response, -1 if we have 984 * hit our bandwidth limit and it is not ok. 985 * 986 * If icmplim is <= 0, the feature is disabled and 0 is returned. 987 * 988 * For now we separate the TCP and UDP subsystems w/ different 'which' 989 * values. We may eventually remove this separation (and simplify the 990 * code further). 991 * 992 * Note that the printing of the error message is delayed so we can 993 * properly print the icmp error rate that the system was trying to do 994 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 995 * the 'final' error, but it doesn't make sense to solve the printing 996 * delay with more complex code. 997 */ 998 999int 1000badport_bandlim(int which) 1001{ 1002 1003#define N(a) (sizeof (a) / sizeof (a[0])) 1004 static struct rate { 1005 const char *type; 1006 struct timeval lasttime; 1007 int curpps; 1008 } rates[BANDLIM_MAX+1] = { 1009 { "icmp unreach response" }, 1010 { "icmp ping response" }, 1011 { "icmp tstamp response" }, 1012 { "closed port RST response" }, 1013 { "open port RST response" }, 1014 { "icmp6 unreach response" }, 1015 { "sctp ootb response" } 1016 }; 1017 1018 /* 1019 * Return ok status if feature disabled or argument out of range. 1020 */ 1021 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1022 struct rate *r = &rates[which]; 1023 int opps = r->curpps; 1024 1025 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1026 return -1; /* discard packet */ 1027 /* 1028 * If we've dropped below the threshold after having 1029 * rate-limited traffic print the message. This preserves 1030 * the previous behaviour at the expense of added complexity. 1031 */ 1032 if (V_icmplim_output && opps > V_icmplim) 1033 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1034 r->type, opps, V_icmplim); 1035 } 1036 return 0; /* okay to send packet */ 1037#undef N 1038} 1039