ip_icmp.c revision 331722
1/*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 30 */ 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: stable/11/sys/netinet/ip_icmp.c 331722 2018-03-29 02:50:57Z eadler $"); 34 35#include "opt_inet.h" 36 37#include <sys/param.h> 38#include <sys/systm.h> 39#include <sys/mbuf.h> 40#include <sys/protosw.h> 41#include <sys/socket.h> 42#include <sys/time.h> 43#include <sys/kernel.h> 44#include <sys/lock.h> 45#include <sys/rmlock.h> 46#include <sys/sysctl.h> 47#include <sys/syslog.h> 48 49#include <net/if.h> 50#include <net/if_var.h> 51#include <net/if_types.h> 52#include <net/route.h> 53#include <net/vnet.h> 54 55#include <netinet/in.h> 56#include <netinet/in_fib.h> 57#include <netinet/in_pcb.h> 58#include <netinet/in_systm.h> 59#include <netinet/in_var.h> 60#include <netinet/ip.h> 61#include <netinet/ip_icmp.h> 62#include <netinet/ip_var.h> 63#include <netinet/ip_options.h> 64#include <netinet/sctp.h> 65#include <netinet/tcp.h> 66#include <netinet/tcp_var.h> 67#include <netinet/tcpip.h> 68#include <netinet/icmp_var.h> 69 70#ifdef INET 71 72#include <machine/in_cksum.h> 73 74#include <security/mac/mac_framework.h> 75#endif /* INET */ 76 77/* 78 * ICMP routines: error generation, receive packet processing, and 79 * routines to turnaround packets back to the originator, and 80 * host table maintenance routines. 81 */ 82static VNET_DEFINE(int, icmplim) = 200; 83#define V_icmplim VNET(icmplim) 84SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, 85 &VNET_NAME(icmplim), 0, 86 "Maximum number of ICMP responses per second"); 87 88static VNET_DEFINE(int, icmplim_output) = 1; 89#define V_icmplim_output VNET(icmplim_output) 90SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW, 91 &VNET_NAME(icmplim_output), 0, 92 "Enable logging of ICMP response rate limiting"); 93 94#ifdef INET 95VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 96VNET_PCPUSTAT_SYSINIT(icmpstat); 97SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 98 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 99 100#ifdef VIMAGE 101VNET_PCPUSTAT_SYSUNINIT(icmpstat); 102#endif /* VIMAGE */ 103 104static VNET_DEFINE(int, icmpmaskrepl) = 0; 105#define V_icmpmaskrepl VNET(icmpmaskrepl) 106SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 107 &VNET_NAME(icmpmaskrepl), 0, 108 "Reply to ICMP Address Mask Request packets"); 109 110static VNET_DEFINE(u_int, icmpmaskfake) = 0; 111#define V_icmpmaskfake VNET(icmpmaskfake) 112SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW, 113 &VNET_NAME(icmpmaskfake), 0, 114 "Fake reply to ICMP Address Mask Request packets"); 115 116VNET_DEFINE(int, drop_redirect) = 0; 117#define V_drop_redirect VNET(drop_redirect) 118SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 119 &VNET_NAME(drop_redirect), 0, 120 "Ignore ICMP redirects"); 121 122static VNET_DEFINE(int, log_redirect) = 0; 123#define V_log_redirect VNET(log_redirect) 124SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW, 125 &VNET_NAME(log_redirect), 0, 126 "Log ICMP redirects to the console"); 127 128static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 129#define V_reply_src VNET(reply_src) 130SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW, 131 &VNET_NAME(reply_src), IFNAMSIZ, 132 "ICMP reply source for non-local packets"); 133 134static VNET_DEFINE(int, icmp_rfi) = 0; 135#define V_icmp_rfi VNET(icmp_rfi) 136SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(icmp_rfi), 0, 138 "ICMP reply from incoming interface for non-local packets"); 139 140static VNET_DEFINE(int, icmp_quotelen) = 8; 141#define V_icmp_quotelen VNET(icmp_quotelen) 142SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW, 143 &VNET_NAME(icmp_quotelen), 0, 144 "Number of bytes from original packet to quote in ICMP reply"); 145 146static VNET_DEFINE(int, icmpbmcastecho) = 0; 147#define V_icmpbmcastecho VNET(icmpbmcastecho) 148SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 149 &VNET_NAME(icmpbmcastecho), 0, 150 "Reply to multicast ICMP Echo Request and Timestamp packets"); 151 152static VNET_DEFINE(int, icmptstamprepl) = 1; 153#define V_icmptstamprepl VNET(icmptstamprepl) 154SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 155 &VNET_NAME(icmptstamprepl), 0, 156 "Respond to ICMP Timestamp packets"); 157 158#ifdef ICMPPRINTFS 159int icmpprintfs = 0; 160#endif 161 162static void icmp_reflect(struct mbuf *); 163static void icmp_send(struct mbuf *, struct mbuf *); 164 165extern struct protosw inetsw[]; 166 167/* 168 * Kernel module interface for updating icmpstat. The argument is an index 169 * into icmpstat treated as an array of u_long. While this encodes the 170 * general layout of icmpstat into the caller, it doesn't encode its 171 * location, so that future changes to add, for example, per-CPU stats 172 * support won't cause binary compatibility problems for kernel modules. 173 */ 174void 175kmod_icmpstat_inc(int statnum) 176{ 177 178 counter_u64_add(VNET(icmpstat)[statnum], 1); 179} 180 181/* 182 * Generate an error packet of type error 183 * in response to bad packet ip. 184 */ 185void 186icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 187{ 188 struct ip *oip, *nip; 189 struct icmp *icp; 190 struct mbuf *m; 191 unsigned icmplen, icmpelen, nlen, oiphlen; 192 193 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", 194 __func__)); 195 196 if (type != ICMP_REDIRECT) 197 ICMPSTAT_INC(icps_error); 198 /* 199 * Don't send error: 200 * if the original packet was encrypted. 201 * if not the first fragment of message. 202 * in response to a multicast or broadcast packet. 203 * if the old packet protocol was an ICMP error message. 204 */ 205 if (n->m_flags & M_DECRYPTED) 206 goto freeit; 207 if (n->m_flags & (M_BCAST|M_MCAST)) 208 goto freeit; 209 210 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */ 211 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) 212 goto freeit; 213 oip = mtod(n, struct ip *); 214 oiphlen = oip->ip_hl << 2; 215 if (n->m_len < oiphlen + ICMP_MINLEN) 216 goto freeit; 217#ifdef ICMPPRINTFS 218 if (icmpprintfs) 219 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 220#endif 221 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 222 goto freeit; 223 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 224 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + 225 oiphlen))->icmp_type)) { 226 ICMPSTAT_INC(icps_oldicmp); 227 goto freeit; 228 } 229 /* 230 * Calculate length to quote from original packet and 231 * prevent the ICMP mbuf from overflowing. 232 * Unfortunately this is non-trivial since ip_forward() 233 * sends us truncated packets. 234 */ 235 nlen = m_length(n, NULL); 236 if (oip->ip_p == IPPROTO_TCP) { 237 struct tcphdr *th; 238 int tcphlen; 239 240 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 241 n->m_next == NULL) 242 goto stdreply; 243 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 244 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL) 245 goto freeit; 246 oip = mtod(n, struct ip *); 247 th = mtodo(n, oiphlen); 248 tcphlen = th->th_off << 2; 249 if (tcphlen < sizeof(struct tcphdr)) 250 goto freeit; 251 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 252 goto freeit; 253 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 254 goto stdreply; 255 if (n->m_len < oiphlen + tcphlen && 256 (n = m_pullup(n, oiphlen + tcphlen)) == NULL) 257 goto freeit; 258 icmpelen = max(tcphlen, min(V_icmp_quotelen, 259 ntohs(oip->ip_len) - oiphlen)); 260 } else if (oip->ip_p == IPPROTO_SCTP) { 261 struct sctphdr *sh; 262 struct sctp_chunkhdr *ch; 263 264 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 265 goto stdreply; 266 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 267 n->m_next == NULL) 268 goto stdreply; 269 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 270 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 271 goto freeit; 272 oip = mtod(n, struct ip *); 273 icmpelen = max(sizeof(struct sctphdr), 274 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 275 sh = mtodo(n, oiphlen); 276 if (ntohl(sh->v_tag) == 0 && 277 ntohs(oip->ip_len) >= oiphlen + 278 sizeof(struct sctphdr) + 8 && 279 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 280 n->m_next != NULL)) { 281 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 282 (n = m_pullup(n, oiphlen + 283 sizeof(struct sctphdr) + 8)) == NULL) 284 goto freeit; 285 oip = mtod(n, struct ip *); 286 sh = mtodo(n, oiphlen); 287 ch = (struct sctp_chunkhdr *)(sh + 1); 288 if (ch->chunk_type == SCTP_INITIATION) { 289 icmpelen = max(sizeof(struct sctphdr) + 8, 290 min(V_icmp_quotelen, ntohs(oip->ip_len) - 291 oiphlen)); 292 } 293 } 294 } else 295stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 296 oiphlen)); 297 298 icmplen = min(oiphlen + icmpelen, nlen); 299 if (icmplen < sizeof(struct ip)) 300 goto freeit; 301 302 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 303 m = m_gethdr(M_NOWAIT, MT_DATA); 304 else 305 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 306 if (m == NULL) 307 goto freeit; 308#ifdef MAC 309 mac_netinet_icmp_reply(n, m); 310#endif 311 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 312 sizeof(struct ip) - ICMP_MINLEN); 313 m_align(m, ICMP_MINLEN + icmplen); 314 m->m_len = ICMP_MINLEN + icmplen; 315 316 /* XXX MRT make the outgoing packet use the same FIB 317 * that was associated with the incoming packet 318 */ 319 M_SETFIB(m, M_GETFIB(n)); 320 icp = mtod(m, struct icmp *); 321 ICMPSTAT_INC(icps_outhist[type]); 322 icp->icmp_type = type; 323 if (type == ICMP_REDIRECT) 324 icp->icmp_gwaddr.s_addr = dest; 325 else { 326 icp->icmp_void = 0; 327 /* 328 * The following assignments assume an overlay with the 329 * just zeroed icmp_void field. 330 */ 331 if (type == ICMP_PARAMPROB) { 332 icp->icmp_pptr = code; 333 code = 0; 334 } else if (type == ICMP_UNREACH && 335 code == ICMP_UNREACH_NEEDFRAG && mtu) { 336 icp->icmp_nextmtu = htons(mtu); 337 } 338 } 339 icp->icmp_code = code; 340 341 /* 342 * Copy the quotation into ICMP message and 343 * convert quoted IP header back to network representation. 344 */ 345 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 346 nip = &icp->icmp_ip; 347 348 /* 349 * Set up ICMP message mbuf and copy old IP header (without options 350 * in front of ICMP message. 351 * If the original mbuf was meant to bypass the firewall, the error 352 * reply should bypass as well. 353 */ 354 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 355 m->m_data -= sizeof(struct ip); 356 m->m_len += sizeof(struct ip); 357 m->m_pkthdr.len = m->m_len; 358 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 359 nip = mtod(m, struct ip *); 360 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 361 nip->ip_len = htons(m->m_len); 362 nip->ip_v = IPVERSION; 363 nip->ip_hl = 5; 364 nip->ip_p = IPPROTO_ICMP; 365 nip->ip_tos = 0; 366 nip->ip_off = 0; 367 icmp_reflect(m); 368 369freeit: 370 m_freem(n); 371} 372 373/* 374 * Process a received ICMP message. 375 */ 376int 377icmp_input(struct mbuf **mp, int *offp, int proto) 378{ 379 struct icmp *icp; 380 struct in_ifaddr *ia; 381 struct mbuf *m = *mp; 382 struct ip *ip = mtod(m, struct ip *); 383 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 384 int hlen = *offp; 385 int icmplen = ntohs(ip->ip_len) - *offp; 386 int i, code; 387 void (*ctlfunc)(int, struct sockaddr *, void *); 388 int fibnum; 389 390 *mp = NULL; 391 392 /* 393 * Locate icmp structure in mbuf, and check 394 * that not corrupted and of at least minimum length. 395 */ 396#ifdef ICMPPRINTFS 397 if (icmpprintfs) { 398 char srcbuf[INET_ADDRSTRLEN]; 399 char dstbuf[INET_ADDRSTRLEN]; 400 401 printf("icmp_input from %s to %s, len %d\n", 402 inet_ntoa_r(ip->ip_src, srcbuf), 403 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 404 } 405#endif 406 if (icmplen < ICMP_MINLEN) { 407 ICMPSTAT_INC(icps_tooshort); 408 goto freeit; 409 } 410 i = hlen + min(icmplen, ICMP_ADVLENMIN); 411 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 412 ICMPSTAT_INC(icps_tooshort); 413 return (IPPROTO_DONE); 414 } 415 ip = mtod(m, struct ip *); 416 m->m_len -= hlen; 417 m->m_data += hlen; 418 icp = mtod(m, struct icmp *); 419 if (in_cksum(m, icmplen)) { 420 ICMPSTAT_INC(icps_checksum); 421 goto freeit; 422 } 423 m->m_len += hlen; 424 m->m_data -= hlen; 425 426#ifdef ICMPPRINTFS 427 if (icmpprintfs) 428 printf("icmp_input, type %d code %d\n", icp->icmp_type, 429 icp->icmp_code); 430#endif 431 432 /* 433 * Message type specific processing. 434 */ 435 if (icp->icmp_type > ICMP_MAXTYPE) 436 goto raw; 437 438 /* Initialize */ 439 bzero(&icmpsrc, sizeof(icmpsrc)); 440 icmpsrc.sin_len = sizeof(struct sockaddr_in); 441 icmpsrc.sin_family = AF_INET; 442 bzero(&icmpdst, sizeof(icmpdst)); 443 icmpdst.sin_len = sizeof(struct sockaddr_in); 444 icmpdst.sin_family = AF_INET; 445 bzero(&icmpgw, sizeof(icmpgw)); 446 icmpgw.sin_len = sizeof(struct sockaddr_in); 447 icmpgw.sin_family = AF_INET; 448 449 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 450 code = icp->icmp_code; 451 switch (icp->icmp_type) { 452 453 case ICMP_UNREACH: 454 switch (code) { 455 case ICMP_UNREACH_NET: 456 case ICMP_UNREACH_HOST: 457 case ICMP_UNREACH_SRCFAIL: 458 case ICMP_UNREACH_NET_UNKNOWN: 459 case ICMP_UNREACH_HOST_UNKNOWN: 460 case ICMP_UNREACH_ISOLATED: 461 case ICMP_UNREACH_TOSNET: 462 case ICMP_UNREACH_TOSHOST: 463 case ICMP_UNREACH_HOST_PRECEDENCE: 464 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 465 code = PRC_UNREACH_NET; 466 break; 467 468 case ICMP_UNREACH_NEEDFRAG: 469 code = PRC_MSGSIZE; 470 break; 471 472 /* 473 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 474 * Treat subcodes 2,3 as immediate RST 475 */ 476 case ICMP_UNREACH_PROTOCOL: 477 code = PRC_UNREACH_PROTOCOL; 478 break; 479 case ICMP_UNREACH_PORT: 480 code = PRC_UNREACH_PORT; 481 break; 482 483 case ICMP_UNREACH_NET_PROHIB: 484 case ICMP_UNREACH_HOST_PROHIB: 485 case ICMP_UNREACH_FILTER_PROHIB: 486 code = PRC_UNREACH_ADMIN_PROHIB; 487 break; 488 489 default: 490 goto badcode; 491 } 492 goto deliver; 493 494 case ICMP_TIMXCEED: 495 if (code > 1) 496 goto badcode; 497 code += PRC_TIMXCEED_INTRANS; 498 goto deliver; 499 500 case ICMP_PARAMPROB: 501 if (code > 1) 502 goto badcode; 503 code = PRC_PARAMPROB; 504 deliver: 505 /* 506 * Problem with datagram; advise higher level routines. 507 */ 508 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 509 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 510 ICMPSTAT_INC(icps_badlen); 511 goto freeit; 512 } 513 /* Discard ICMP's in response to multicast packets */ 514 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 515 goto badcode; 516#ifdef ICMPPRINTFS 517 if (icmpprintfs) 518 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 519#endif 520 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 521 /* 522 * XXX if the packet contains [IPv4 AH TCP], we can't make a 523 * notification to TCP layer. 524 */ 525 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 526 ip_stripoptions(m); 527 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 528 /* This should actually not happen */ 529 ICMPSTAT_INC(icps_tooshort); 530 return (IPPROTO_DONE); 531 } 532 ip = mtod(m, struct ip *); 533 icp = (struct icmp *)(ip + 1); 534 /* 535 * The upper layer handler can rely on: 536 * - The outer IP header has no options. 537 * - The outer IP header, the ICMP header, the inner IP header, 538 * and the first n bytes of the inner payload are contiguous. 539 * n is at least 8, but might be larger based on 540 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 541 */ 542 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 543 if (ctlfunc) 544 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 545 (void *)&icp->icmp_ip); 546 break; 547 548 badcode: 549 ICMPSTAT_INC(icps_badcode); 550 break; 551 552 case ICMP_ECHO: 553 if (!V_icmpbmcastecho 554 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 555 ICMPSTAT_INC(icps_bmcastecho); 556 break; 557 } 558 icp->icmp_type = ICMP_ECHOREPLY; 559 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 560 goto freeit; 561 else 562 goto reflect; 563 564 case ICMP_TSTAMP: 565 if (V_icmptstamprepl == 0) 566 break; 567 if (!V_icmpbmcastecho 568 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 569 ICMPSTAT_INC(icps_bmcasttstamp); 570 break; 571 } 572 if (icmplen < ICMP_TSLEN) { 573 ICMPSTAT_INC(icps_badlen); 574 break; 575 } 576 icp->icmp_type = ICMP_TSTAMPREPLY; 577 icp->icmp_rtime = iptime(); 578 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 579 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 580 goto freeit; 581 else 582 goto reflect; 583 584 case ICMP_MASKREQ: 585 if (V_icmpmaskrepl == 0) 586 break; 587 /* 588 * We are not able to respond with all ones broadcast 589 * unless we receive it over a point-to-point interface. 590 */ 591 if (icmplen < ICMP_MASKLEN) 592 break; 593 switch (ip->ip_dst.s_addr) { 594 595 case INADDR_BROADCAST: 596 case INADDR_ANY: 597 icmpdst.sin_addr = ip->ip_src; 598 break; 599 600 default: 601 icmpdst.sin_addr = ip->ip_dst; 602 } 603 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 604 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 605 if (ia == NULL) 606 break; 607 if (ia->ia_ifp == NULL) { 608 ifa_free(&ia->ia_ifa); 609 break; 610 } 611 icp->icmp_type = ICMP_MASKREPLY; 612 if (V_icmpmaskfake == 0) 613 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 614 else 615 icp->icmp_mask = V_icmpmaskfake; 616 if (ip->ip_src.s_addr == 0) { 617 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 618 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 619 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 620 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 621 } 622 ifa_free(&ia->ia_ifa); 623reflect: 624 ICMPSTAT_INC(icps_reflect); 625 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 626 icmp_reflect(m); 627 return (IPPROTO_DONE); 628 629 case ICMP_REDIRECT: 630 if (V_log_redirect) { 631 u_long src, dst, gw; 632 633 src = ntohl(ip->ip_src.s_addr); 634 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 635 gw = ntohl(icp->icmp_gwaddr.s_addr); 636 printf("icmp redirect from %d.%d.%d.%d: " 637 "%d.%d.%d.%d => %d.%d.%d.%d\n", 638 (int)(src >> 24), (int)((src >> 16) & 0xff), 639 (int)((src >> 8) & 0xff), (int)(src & 0xff), 640 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 641 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 642 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 643 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 644 } 645 /* 646 * RFC1812 says we must ignore ICMP redirects if we 647 * are acting as router. 648 */ 649 if (V_drop_redirect || V_ipforwarding) 650 break; 651 if (code > 3) 652 goto badcode; 653 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 654 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 655 ICMPSTAT_INC(icps_badlen); 656 break; 657 } 658 /* 659 * Short circuit routing redirects to force 660 * immediate change in the kernel's routing 661 * tables. The message is also handed to anyone 662 * listening on a raw socket (e.g. the routing 663 * daemon for use in updating its tables). 664 */ 665 icmpgw.sin_addr = ip->ip_src; 666 icmpdst.sin_addr = icp->icmp_gwaddr; 667#ifdef ICMPPRINTFS 668 if (icmpprintfs) { 669 char dstbuf[INET_ADDRSTRLEN]; 670 char gwbuf[INET_ADDRSTRLEN]; 671 672 printf("redirect dst %s to %s\n", 673 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 674 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 675 } 676#endif 677 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 678 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 679 in_rtredirect((struct sockaddr *)&icmpsrc, 680 (struct sockaddr *)&icmpdst, 681 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 682 (struct sockaddr *)&icmpgw, fibnum); 683 } 684 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 685 break; 686 687 /* 688 * No kernel processing for the following; 689 * just fall through to send to raw listener. 690 */ 691 case ICMP_ECHOREPLY: 692 case ICMP_ROUTERADVERT: 693 case ICMP_ROUTERSOLICIT: 694 case ICMP_TSTAMPREPLY: 695 case ICMP_IREQREPLY: 696 case ICMP_MASKREPLY: 697 case ICMP_SOURCEQUENCH: 698 default: 699 break; 700 } 701 702raw: 703 *mp = m; 704 rip_input(mp, offp, proto); 705 return (IPPROTO_DONE); 706 707freeit: 708 m_freem(m); 709 return (IPPROTO_DONE); 710} 711 712/* 713 * Reflect the ip packet back to the source 714 */ 715static void 716icmp_reflect(struct mbuf *m) 717{ 718 struct rm_priotracker in_ifa_tracker; 719 struct ip *ip = mtod(m, struct ip *); 720 struct ifaddr *ifa; 721 struct ifnet *ifp; 722 struct in_ifaddr *ia; 723 struct in_addr t; 724 struct nhop4_extended nh_ext; 725 struct mbuf *opts = NULL; 726 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 727 728 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 729 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 730 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 731 m_freem(m); /* Bad return address */ 732 ICMPSTAT_INC(icps_badaddr); 733 goto done; /* Ip_output() will check for broadcast */ 734 } 735 736 t = ip->ip_dst; 737 ip->ip_dst = ip->ip_src; 738 739 /* 740 * Source selection for ICMP replies: 741 * 742 * If the incoming packet was addressed directly to one of our 743 * own addresses, use dst as the src for the reply. 744 */ 745 IN_IFADDR_RLOCK(&in_ifa_tracker); 746 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 747 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 748 t = IA_SIN(ia)->sin_addr; 749 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 750 goto match; 751 } 752 } 753 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 754 755 /* 756 * If the incoming packet was addressed to one of our broadcast 757 * addresses, use the first non-broadcast address which corresponds 758 * to the incoming interface. 759 */ 760 ifp = m->m_pkthdr.rcvif; 761 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 762 IF_ADDR_RLOCK(ifp); 763 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 764 if (ifa->ifa_addr->sa_family != AF_INET) 765 continue; 766 ia = ifatoia(ifa); 767 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 768 t.s_addr) { 769 t = IA_SIN(ia)->sin_addr; 770 IF_ADDR_RUNLOCK(ifp); 771 goto match; 772 } 773 } 774 IF_ADDR_RUNLOCK(ifp); 775 } 776 /* 777 * If the packet was transiting through us, use the address of 778 * the interface the packet came through in. If that interface 779 * doesn't have a suitable IP address, the normal selection 780 * criteria apply. 781 */ 782 if (V_icmp_rfi && ifp != NULL) { 783 IF_ADDR_RLOCK(ifp); 784 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 785 if (ifa->ifa_addr->sa_family != AF_INET) 786 continue; 787 ia = ifatoia(ifa); 788 t = IA_SIN(ia)->sin_addr; 789 IF_ADDR_RUNLOCK(ifp); 790 goto match; 791 } 792 IF_ADDR_RUNLOCK(ifp); 793 } 794 /* 795 * If the incoming packet was not addressed directly to us, use 796 * designated interface for icmp replies specified by sysctl 797 * net.inet.icmp.reply_src (default not set). Otherwise continue 798 * with normal source selection. 799 */ 800 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 801 IF_ADDR_RLOCK(ifp); 802 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 803 if (ifa->ifa_addr->sa_family != AF_INET) 804 continue; 805 ia = ifatoia(ifa); 806 t = IA_SIN(ia)->sin_addr; 807 IF_ADDR_RUNLOCK(ifp); 808 goto match; 809 } 810 IF_ADDR_RUNLOCK(ifp); 811 } 812 /* 813 * If the packet was transiting through us, use the address of 814 * the interface that is the closest to the packet source. 815 * When we don't have a route back to the packet source, stop here 816 * and drop the packet. 817 */ 818 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 819 m_freem(m); 820 ICMPSTAT_INC(icps_noroute); 821 goto done; 822 } 823 t = nh_ext.nh_src; 824match: 825#ifdef MAC 826 mac_netinet_icmp_replyinplace(m); 827#endif 828 ip->ip_src = t; 829 ip->ip_ttl = V_ip_defttl; 830 831 if (optlen > 0) { 832 u_char *cp; 833 int opt, cnt; 834 u_int len; 835 836 /* 837 * Retrieve any source routing from the incoming packet; 838 * add on any record-route or timestamp options. 839 */ 840 cp = (u_char *) (ip + 1); 841 if ((opts = ip_srcroute(m)) == NULL && 842 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 843 opts->m_len = sizeof(struct in_addr); 844 mtod(opts, struct in_addr *)->s_addr = 0; 845 } 846 if (opts) { 847#ifdef ICMPPRINTFS 848 if (icmpprintfs) 849 printf("icmp_reflect optlen %d rt %d => ", 850 optlen, opts->m_len); 851#endif 852 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 853 opt = cp[IPOPT_OPTVAL]; 854 if (opt == IPOPT_EOL) 855 break; 856 if (opt == IPOPT_NOP) 857 len = 1; 858 else { 859 if (cnt < IPOPT_OLEN + sizeof(*cp)) 860 break; 861 len = cp[IPOPT_OLEN]; 862 if (len < IPOPT_OLEN + sizeof(*cp) || 863 len > cnt) 864 break; 865 } 866 /* 867 * Should check for overflow, but it "can't happen" 868 */ 869 if (opt == IPOPT_RR || opt == IPOPT_TS || 870 opt == IPOPT_SECURITY) { 871 bcopy((caddr_t)cp, 872 mtod(opts, caddr_t) + opts->m_len, len); 873 opts->m_len += len; 874 } 875 } 876 /* Terminate & pad, if necessary */ 877 cnt = opts->m_len % 4; 878 if (cnt) { 879 for (; cnt < 4; cnt++) { 880 *(mtod(opts, caddr_t) + opts->m_len) = 881 IPOPT_EOL; 882 opts->m_len++; 883 } 884 } 885#ifdef ICMPPRINTFS 886 if (icmpprintfs) 887 printf("%d\n", opts->m_len); 888#endif 889 } 890 ip_stripoptions(m); 891 } 892 m_tag_delete_nonpersistent(m); 893 m->m_flags &= ~(M_BCAST|M_MCAST); 894 icmp_send(m, opts); 895done: 896 if (opts) 897 (void)m_free(opts); 898} 899 900/* 901 * Send an icmp packet back to the ip level, 902 * after supplying a checksum. 903 */ 904static void 905icmp_send(struct mbuf *m, struct mbuf *opts) 906{ 907 struct ip *ip = mtod(m, struct ip *); 908 int hlen; 909 struct icmp *icp; 910 911 hlen = ip->ip_hl << 2; 912 m->m_data += hlen; 913 m->m_len -= hlen; 914 icp = mtod(m, struct icmp *); 915 icp->icmp_cksum = 0; 916 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 917 m->m_data -= hlen; 918 m->m_len += hlen; 919 m->m_pkthdr.rcvif = (struct ifnet *)0; 920#ifdef ICMPPRINTFS 921 if (icmpprintfs) { 922 char dstbuf[INET_ADDRSTRLEN]; 923 char srcbuf[INET_ADDRSTRLEN]; 924 925 printf("icmp_send dst %s src %s\n", 926 inet_ntoa_r(ip->ip_dst, dstbuf), 927 inet_ntoa_r(ip->ip_src, srcbuf)); 928 } 929#endif 930 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 931} 932 933/* 934 * Return milliseconds since 00:00 UTC in network format. 935 */ 936uint32_t 937iptime(void) 938{ 939 struct timeval atv; 940 u_long t; 941 942 getmicrotime(&atv); 943 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 944 return (htonl(t)); 945} 946 947/* 948 * Return the next larger or smaller MTU plateau (table from RFC 1191) 949 * given current value MTU. If DIR is less than zero, a larger plateau 950 * is returned; otherwise, a smaller value is returned. 951 */ 952int 953ip_next_mtu(int mtu, int dir) 954{ 955 static int mtutab[] = { 956 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 957 296, 68, 0 958 }; 959 int i, size; 960 961 size = (sizeof mtutab) / (sizeof mtutab[0]); 962 if (dir >= 0) { 963 for (i = 0; i < size; i++) 964 if (mtu > mtutab[i]) 965 return mtutab[i]; 966 } else { 967 for (i = size - 1; i >= 0; i--) 968 if (mtu < mtutab[i]) 969 return mtutab[i]; 970 if (mtu == mtutab[0]) 971 return mtutab[0]; 972 } 973 return 0; 974} 975#endif /* INET */ 976 977 978/* 979 * badport_bandlim() - check for ICMP bandwidth limit 980 * 981 * Return 0 if it is ok to send an ICMP error response, -1 if we have 982 * hit our bandwidth limit and it is not ok. 983 * 984 * If icmplim is <= 0, the feature is disabled and 0 is returned. 985 * 986 * For now we separate the TCP and UDP subsystems w/ different 'which' 987 * values. We may eventually remove this separation (and simplify the 988 * code further). 989 * 990 * Note that the printing of the error message is delayed so we can 991 * properly print the icmp error rate that the system was trying to do 992 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 993 * the 'final' error, but it doesn't make sense to solve the printing 994 * delay with more complex code. 995 */ 996 997int 998badport_bandlim(int which) 999{ 1000 1001#define N(a) (sizeof (a) / sizeof (a[0])) 1002 static struct rate { 1003 const char *type; 1004 struct timeval lasttime; 1005 int curpps; 1006 } rates[BANDLIM_MAX+1] = { 1007 { "icmp unreach response" }, 1008 { "icmp ping response" }, 1009 { "icmp tstamp response" }, 1010 { "closed port RST response" }, 1011 { "open port RST response" }, 1012 { "icmp6 unreach response" }, 1013 { "sctp ootb response" } 1014 }; 1015 1016 /* 1017 * Return ok status if feature disabled or argument out of range. 1018 */ 1019 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1020 struct rate *r = &rates[which]; 1021 int opps = r->curpps; 1022 1023 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1024 return -1; /* discard packet */ 1025 /* 1026 * If we've dropped below the threshold after having 1027 * rate-limited traffic print the message. This preserves 1028 * the previous behaviour at the expense of added complexity. 1029 */ 1030 if (V_icmplim_output && opps > V_icmplim) 1031 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1032 r->type, opps, V_icmplim); 1033 } 1034 return 0; /* okay to send packet */ 1035#undef N 1036} 1037