Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/ip_icmp.c
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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: releng/11.1/sys/netinet/ip_icmp.c 315456 2017-03-17 14:54:10Z vangyzen $"); 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 */ 82 static VNET_DEFINE(int, icmplim) = 200; 83 #define V_icmplim VNET(icmplim) 84 SYSCTL_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 88 static VNET_DEFINE(int, icmplim_output) = 1; 89 #define V_icmplim_output VNET(icmplim_output) 90 SYSCTL_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 95 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 96 VNET_PCPUSTAT_SYSINIT(icmpstat); 97 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 98 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 99 100 #ifdef VIMAGE 101 VNET_PCPUSTAT_SYSUNINIT(icmpstat); 102 #endif /* VIMAGE */ 103 104 static VNET_DEFINE(int, icmpmaskrepl) = 0; 105 #define V_icmpmaskrepl VNET(icmpmaskrepl) 106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 107 &VNET_NAME(icmpmaskrepl), 0, 108 "Reply to ICMP Address Mask Request packets"); 109 110 static VNET_DEFINE(u_int, icmpmaskfake) = 0; 111 #define V_icmpmaskfake VNET(icmpmaskfake) 112 SYSCTL_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"); 115 116 VNET_DEFINE(int, drop_redirect) = 0; 117 #define V_drop_redirect VNET(drop_redirect) 118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 119 &VNET_NAME(drop_redirect), 0, 120 "Ignore ICMP redirects"); 121 122 static VNET_DEFINE(int, log_redirect) = 0; 123 #define V_log_redirect VNET(log_redirect) 124 SYSCTL_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"); 127 128 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 129 #define V_reply_src VNET(reply_src) 130 SYSCTL_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"); 133 134 static VNET_DEFINE(int, icmp_rfi) = 0; 135 #define V_icmp_rfi VNET(icmp_rfi) 136 SYSCTL_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"); 139 140 static VNET_DEFINE(int, icmp_quotelen) = 8; 141 #define V_icmp_quotelen VNET(icmp_quotelen) 142 SYSCTL_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"); 145 146 static VNET_DEFINE(int, icmpbmcastecho) = 0; 147 #define V_icmpbmcastecho VNET(icmpbmcastecho) 148 SYSCTL_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"); 151 152 static VNET_DEFINE(int, icmptstamprepl) = 1; 153 #define V_icmptstamprepl VNET(icmptstamprepl) 154 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 155 &VNET_NAME(icmptstamprepl), 0, 156 "Respond to ICMP Timestamp packets"); 157 158 #ifdef ICMPPRINTFS 159 int icmpprintfs = 0; 160 #endif 161 162 static void icmp_reflect(struct mbuf *); 163 static void icmp_send(struct mbuf *, struct mbuf *); 164 165 extern 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 */ 174 void 175 kmod_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 */ 185 void 186 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 187 { 188 register struct ip *oip = mtod(n, struct ip *), *nip; 189 register unsigned oiphlen = oip->ip_hl << 2; 190 register struct icmp *icp; 191 register struct mbuf *m; 192 unsigned icmplen, icmpelen, nlen; 193 194 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 195 #ifdef ICMPPRINTFS 196 if (icmpprintfs) 197 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 198 #endif 199 if (type != ICMP_REDIRECT) 200 ICMPSTAT_INC(icps_error); 201 /* 202 * Don't send error: 203 * if the original packet was encrypted. 204 * if not the first fragment of message. 205 * in response to a multicast or broadcast packet. 206 * if the old packet protocol was an ICMP error message. 207 */ 208 if (n->m_flags & M_DECRYPTED) 209 goto freeit; 210 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 211 goto freeit; 212 if (n->m_flags & (M_BCAST|M_MCAST)) 213 goto freeit; 214 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 215 n->m_len >= oiphlen + ICMP_MINLEN && 216 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 217 ICMPSTAT_INC(icps_oldicmp); 218 goto freeit; 219 } 220 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 221 if (oiphlen + 8 > n->m_len) 222 goto freeit; 223 /* 224 * Calculate length to quote from original packet and 225 * prevent the ICMP mbuf from overflowing. 226 * Unfortunately this is non-trivial since ip_forward() 227 * sends us truncated packets. 228 */ 229 nlen = m_length(n, NULL); 230 if (oip->ip_p == IPPROTO_TCP) { 231 struct tcphdr *th; 232 int tcphlen; 233 234 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 235 n->m_next == NULL) 236 goto stdreply; 237 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 238 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 239 goto freeit; 240 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 241 tcphlen = th->th_off << 2; 242 if (tcphlen < sizeof(struct tcphdr)) 243 goto freeit; 244 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 245 goto freeit; 246 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 247 goto stdreply; 248 if (n->m_len < oiphlen + tcphlen && 249 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 250 goto freeit; 251 icmpelen = max(tcphlen, min(V_icmp_quotelen, 252 ntohs(oip->ip_len) - oiphlen)); 253 } else if (oip->ip_p == IPPROTO_SCTP) { 254 struct sctphdr *sh; 255 struct sctp_chunkhdr *ch; 256 257 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 258 goto stdreply; 259 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 260 n->m_next == NULL) 261 goto stdreply; 262 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 263 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 264 goto freeit; 265 icmpelen = max(sizeof(struct sctphdr), 266 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 267 sh = (struct sctphdr *)((caddr_t)oip + oiphlen); 268 if (ntohl(sh->v_tag) == 0 && 269 ntohs(oip->ip_len) >= oiphlen + sizeof(struct sctphdr) + 8 && 270 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 271 n->m_next != NULL)) { 272 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 273 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr) + 8)) == NULL) 274 goto freeit; 275 ch = (struct sctp_chunkhdr *)(sh + 1); 276 if (ch->chunk_type == SCTP_INITIATION) { 277 icmpelen = max(sizeof(struct sctphdr) + 8, 278 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 279 } 280 } 281 } else 282 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 283 284 icmplen = min(oiphlen + icmpelen, nlen); 285 if (icmplen < sizeof(struct ip)) 286 goto freeit; 287 288 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 289 m = m_gethdr(M_NOWAIT, MT_DATA); 290 else 291 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 292 if (m == NULL) 293 goto freeit; 294 #ifdef MAC 295 mac_netinet_icmp_reply(n, m); 296 #endif 297 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 298 m_align(m, ICMP_MINLEN + icmplen); 299 m->m_len = ICMP_MINLEN + icmplen; 300 301 /* XXX MRT make the outgoing packet use the same FIB 302 * that was associated with the incoming packet 303 */ 304 M_SETFIB(m, M_GETFIB(n)); 305 icp = mtod(m, struct icmp *); 306 ICMPSTAT_INC(icps_outhist[type]); 307 icp->icmp_type = type; 308 if (type == ICMP_REDIRECT) 309 icp->icmp_gwaddr.s_addr = dest; 310 else { 311 icp->icmp_void = 0; 312 /* 313 * The following assignments assume an overlay with the 314 * just zeroed icmp_void field. 315 */ 316 if (type == ICMP_PARAMPROB) { 317 icp->icmp_pptr = code; 318 code = 0; 319 } else if (type == ICMP_UNREACH && 320 code == ICMP_UNREACH_NEEDFRAG && mtu) { 321 icp->icmp_nextmtu = htons(mtu); 322 } 323 } 324 icp->icmp_code = code; 325 326 /* 327 * Copy the quotation into ICMP message and 328 * convert quoted IP header back to network representation. 329 */ 330 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 331 nip = &icp->icmp_ip; 332 333 /* 334 * Set up ICMP message mbuf and copy old IP header (without options 335 * in front of ICMP message. 336 * If the original mbuf was meant to bypass the firewall, the error 337 * reply should bypass as well. 338 */ 339 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 340 m->m_data -= sizeof(struct ip); 341 m->m_len += sizeof(struct ip); 342 m->m_pkthdr.len = m->m_len; 343 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 344 nip = mtod(m, struct ip *); 345 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 346 nip->ip_len = htons(m->m_len); 347 nip->ip_v = IPVERSION; 348 nip->ip_hl = 5; 349 nip->ip_p = IPPROTO_ICMP; 350 nip->ip_tos = 0; 351 nip->ip_off = 0; 352 icmp_reflect(m); 353 354 freeit: 355 m_freem(n); 356 } 357 358 /* 359 * Process a received ICMP message. 360 */ 361 int 362 icmp_input(struct mbuf **mp, int *offp, int proto) 363 { 364 struct icmp *icp; 365 struct in_ifaddr *ia; 366 struct mbuf *m = *mp; 367 struct ip *ip = mtod(m, struct ip *); 368 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 369 int hlen = *offp; 370 int icmplen = ntohs(ip->ip_len) - *offp; 371 int i, code; 372 void (*ctlfunc)(int, struct sockaddr *, void *); 373 int fibnum; 374 375 *mp = NULL; 376 377 /* 378 * Locate icmp structure in mbuf, and check 379 * that not corrupted and of at least minimum length. 380 */ 381 #ifdef ICMPPRINTFS 382 if (icmpprintfs) { 383 char srcbuf[INET_ADDRSTRLEN]; 384 char dstbuf[INET_ADDRSTRLEN]; 385 386 printf("icmp_input from %s to %s, len %d\n", 387 inet_ntoa_r(ip->ip_src, srcbuf), 388 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 389 } 390 #endif 391 if (icmplen < ICMP_MINLEN) { 392 ICMPSTAT_INC(icps_tooshort); 393 goto freeit; 394 } 395 i = hlen + min(icmplen, ICMP_ADVLENMIN); 396 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 397 ICMPSTAT_INC(icps_tooshort); 398 return (IPPROTO_DONE); 399 } 400 ip = mtod(m, struct ip *); 401 m->m_len -= hlen; 402 m->m_data += hlen; 403 icp = mtod(m, struct icmp *); 404 if (in_cksum(m, icmplen)) { 405 ICMPSTAT_INC(icps_checksum); 406 goto freeit; 407 } 408 m->m_len += hlen; 409 m->m_data -= hlen; 410 411 #ifdef ICMPPRINTFS 412 if (icmpprintfs) 413 printf("icmp_input, type %d code %d\n", icp->icmp_type, 414 icp->icmp_code); 415 #endif 416 417 /* 418 * Message type specific processing. 419 */ 420 if (icp->icmp_type > ICMP_MAXTYPE) 421 goto raw; 422 423 /* Initialize */ 424 bzero(&icmpsrc, sizeof(icmpsrc)); 425 icmpsrc.sin_len = sizeof(struct sockaddr_in); 426 icmpsrc.sin_family = AF_INET; 427 bzero(&icmpdst, sizeof(icmpdst)); 428 icmpdst.sin_len = sizeof(struct sockaddr_in); 429 icmpdst.sin_family = AF_INET; 430 bzero(&icmpgw, sizeof(icmpgw)); 431 icmpgw.sin_len = sizeof(struct sockaddr_in); 432 icmpgw.sin_family = AF_INET; 433 434 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 435 code = icp->icmp_code; 436 switch (icp->icmp_type) { 437 438 case ICMP_UNREACH: 439 switch (code) { 440 case ICMP_UNREACH_NET: 441 case ICMP_UNREACH_HOST: 442 case ICMP_UNREACH_SRCFAIL: 443 case ICMP_UNREACH_NET_UNKNOWN: 444 case ICMP_UNREACH_HOST_UNKNOWN: 445 case ICMP_UNREACH_ISOLATED: 446 case ICMP_UNREACH_TOSNET: 447 case ICMP_UNREACH_TOSHOST: 448 case ICMP_UNREACH_HOST_PRECEDENCE: 449 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 450 code = PRC_UNREACH_NET; 451 break; 452 453 case ICMP_UNREACH_NEEDFRAG: 454 code = PRC_MSGSIZE; 455 break; 456 457 /* 458 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 459 * Treat subcodes 2,3 as immediate RST 460 */ 461 case ICMP_UNREACH_PROTOCOL: 462 code = PRC_UNREACH_PROTOCOL; 463 break; 464 case ICMP_UNREACH_PORT: 465 code = PRC_UNREACH_PORT; 466 break; 467 468 case ICMP_UNREACH_NET_PROHIB: 469 case ICMP_UNREACH_HOST_PROHIB: 470 case ICMP_UNREACH_FILTER_PROHIB: 471 code = PRC_UNREACH_ADMIN_PROHIB; 472 break; 473 474 default: 475 goto badcode; 476 } 477 goto deliver; 478 479 case ICMP_TIMXCEED: 480 if (code > 1) 481 goto badcode; 482 code += PRC_TIMXCEED_INTRANS; 483 goto deliver; 484 485 case ICMP_PARAMPROB: 486 if (code > 1) 487 goto badcode; 488 code = PRC_PARAMPROB; 489 deliver: 490 /* 491 * Problem with datagram; advise higher level routines. 492 */ 493 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 494 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 495 ICMPSTAT_INC(icps_badlen); 496 goto freeit; 497 } 498 /* Discard ICMP's in response to multicast packets */ 499 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 500 goto badcode; 501 #ifdef ICMPPRINTFS 502 if (icmpprintfs) 503 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 504 #endif 505 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 506 /* 507 * XXX if the packet contains [IPv4 AH TCP], we can't make a 508 * notification to TCP layer. 509 */ 510 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 511 ip_stripoptions(m); 512 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 513 /* This should actually not happen */ 514 ICMPSTAT_INC(icps_tooshort); 515 return (IPPROTO_DONE); 516 } 517 ip = mtod(m, struct ip *); 518 icp = (struct icmp *)(ip + 1); 519 /* 520 * The upper layer handler can rely on: 521 * - The outer IP header has no options. 522 * - The outer IP header, the ICMP header, the inner IP header, 523 * and the first n bytes of the inner payload are contiguous. 524 * n is at least 8, but might be larger based on 525 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 526 */ 527 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 528 if (ctlfunc) 529 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 530 (void *)&icp->icmp_ip); 531 break; 532 533 badcode: 534 ICMPSTAT_INC(icps_badcode); 535 break; 536 537 case ICMP_ECHO: 538 if (!V_icmpbmcastecho 539 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 540 ICMPSTAT_INC(icps_bmcastecho); 541 break; 542 } 543 icp->icmp_type = ICMP_ECHOREPLY; 544 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 545 goto freeit; 546 else 547 goto reflect; 548 549 case ICMP_TSTAMP: 550 if (V_icmptstamprepl == 0) 551 break; 552 if (!V_icmpbmcastecho 553 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 554 ICMPSTAT_INC(icps_bmcasttstamp); 555 break; 556 } 557 if (icmplen < ICMP_TSLEN) { 558 ICMPSTAT_INC(icps_badlen); 559 break; 560 } 561 icp->icmp_type = ICMP_TSTAMPREPLY; 562 icp->icmp_rtime = iptime(); 563 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 564 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 565 goto freeit; 566 else 567 goto reflect; 568 569 case ICMP_MASKREQ: 570 if (V_icmpmaskrepl == 0) 571 break; 572 /* 573 * We are not able to respond with all ones broadcast 574 * unless we receive it over a point-to-point interface. 575 */ 576 if (icmplen < ICMP_MASKLEN) 577 break; 578 switch (ip->ip_dst.s_addr) { 579 580 case INADDR_BROADCAST: 581 case INADDR_ANY: 582 icmpdst.sin_addr = ip->ip_src; 583 break; 584 585 default: 586 icmpdst.sin_addr = ip->ip_dst; 587 } 588 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 589 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 590 if (ia == NULL) 591 break; 592 if (ia->ia_ifp == NULL) { 593 ifa_free(&ia->ia_ifa); 594 break; 595 } 596 icp->icmp_type = ICMP_MASKREPLY; 597 if (V_icmpmaskfake == 0) 598 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 599 else 600 icp->icmp_mask = V_icmpmaskfake; 601 if (ip->ip_src.s_addr == 0) { 602 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 603 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 604 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 605 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 606 } 607 ifa_free(&ia->ia_ifa); 608 reflect: 609 ICMPSTAT_INC(icps_reflect); 610 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 611 icmp_reflect(m); 612 return (IPPROTO_DONE); 613 614 case ICMP_REDIRECT: 615 if (V_log_redirect) { 616 u_long src, dst, gw; 617 618 src = ntohl(ip->ip_src.s_addr); 619 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 620 gw = ntohl(icp->icmp_gwaddr.s_addr); 621 printf("icmp redirect from %d.%d.%d.%d: " 622 "%d.%d.%d.%d => %d.%d.%d.%d\n", 623 (int)(src >> 24), (int)((src >> 16) & 0xff), 624 (int)((src >> 8) & 0xff), (int)(src & 0xff), 625 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 626 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 627 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 628 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 629 } 630 /* 631 * RFC1812 says we must ignore ICMP redirects if we 632 * are acting as router. 633 */ 634 if (V_drop_redirect || V_ipforwarding) 635 break; 636 if (code > 3) 637 goto badcode; 638 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 639 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 640 ICMPSTAT_INC(icps_badlen); 641 break; 642 } 643 /* 644 * Short circuit routing redirects to force 645 * immediate change in the kernel's routing 646 * tables. The message is also handed to anyone 647 * listening on a raw socket (e.g. the routing 648 * daemon for use in updating its tables). 649 */ 650 icmpgw.sin_addr = ip->ip_src; 651 icmpdst.sin_addr = icp->icmp_gwaddr; 652 #ifdef ICMPPRINTFS 653 if (icmpprintfs) { 654 char dstbuf[INET_ADDRSTRLEN]; 655 char gwbuf[INET_ADDRSTRLEN]; 656 657 printf("redirect dst %s to %s\n", 658 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 659 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 660 } 661 #endif 662 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 663 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 664 in_rtredirect((struct sockaddr *)&icmpsrc, 665 (struct sockaddr *)&icmpdst, 666 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 667 (struct sockaddr *)&icmpgw, fibnum); 668 } 669 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 670 break; 671 672 /* 673 * No kernel processing for the following; 674 * just fall through to send to raw listener. 675 */ 676 case ICMP_ECHOREPLY: 677 case ICMP_ROUTERADVERT: 678 case ICMP_ROUTERSOLICIT: 679 case ICMP_TSTAMPREPLY: 680 case ICMP_IREQREPLY: 681 case ICMP_MASKREPLY: 682 case ICMP_SOURCEQUENCH: 683 default: 684 break; 685 } 686 687 raw: 688 *mp = m; 689 rip_input(mp, offp, proto); 690 return (IPPROTO_DONE); 691 692 freeit: 693 m_freem(m); 694 return (IPPROTO_DONE); 695 } 696 697 /* 698 * Reflect the ip packet back to the source 699 */ 700 static void 701 icmp_reflect(struct mbuf *m) 702 { 703 struct rm_priotracker in_ifa_tracker; 704 struct ip *ip = mtod(m, struct ip *); 705 struct ifaddr *ifa; 706 struct ifnet *ifp; 707 struct in_ifaddr *ia; 708 struct in_addr t; 709 struct nhop4_extended nh_ext; 710 struct mbuf *opts = NULL; 711 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 712 713 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 714 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 715 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 716 m_freem(m); /* Bad return address */ 717 ICMPSTAT_INC(icps_badaddr); 718 goto done; /* Ip_output() will check for broadcast */ 719 } 720 721 t = ip->ip_dst; 722 ip->ip_dst = ip->ip_src; 723 724 /* 725 * Source selection for ICMP replies: 726 * 727 * If the incoming packet was addressed directly to one of our 728 * own addresses, use dst as the src for the reply. 729 */ 730 IN_IFADDR_RLOCK(&in_ifa_tracker); 731 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 732 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 733 t = IA_SIN(ia)->sin_addr; 734 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 735 goto match; 736 } 737 } 738 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 739 740 /* 741 * If the incoming packet was addressed to one of our broadcast 742 * addresses, use the first non-broadcast address which corresponds 743 * to the incoming interface. 744 */ 745 ifp = m->m_pkthdr.rcvif; 746 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 747 IF_ADDR_RLOCK(ifp); 748 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 749 if (ifa->ifa_addr->sa_family != AF_INET) 750 continue; 751 ia = ifatoia(ifa); 752 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 753 t.s_addr) { 754 t = IA_SIN(ia)->sin_addr; 755 IF_ADDR_RUNLOCK(ifp); 756 goto match; 757 } 758 } 759 IF_ADDR_RUNLOCK(ifp); 760 } 761 /* 762 * If the packet was transiting through us, use the address of 763 * the interface the packet came through in. If that interface 764 * doesn't have a suitable IP address, the normal selection 765 * criteria apply. 766 */ 767 if (V_icmp_rfi && ifp != NULL) { 768 IF_ADDR_RLOCK(ifp); 769 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 770 if (ifa->ifa_addr->sa_family != AF_INET) 771 continue; 772 ia = ifatoia(ifa); 773 t = IA_SIN(ia)->sin_addr; 774 IF_ADDR_RUNLOCK(ifp); 775 goto match; 776 } 777 IF_ADDR_RUNLOCK(ifp); 778 } 779 /* 780 * If the incoming packet was not addressed directly to us, use 781 * designated interface for icmp replies specified by sysctl 782 * net.inet.icmp.reply_src (default not set). Otherwise continue 783 * with normal source selection. 784 */ 785 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 786 IF_ADDR_RLOCK(ifp); 787 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 788 if (ifa->ifa_addr->sa_family != AF_INET) 789 continue; 790 ia = ifatoia(ifa); 791 t = IA_SIN(ia)->sin_addr; 792 IF_ADDR_RUNLOCK(ifp); 793 goto match; 794 } 795 IF_ADDR_RUNLOCK(ifp); 796 } 797 /* 798 * If the packet was transiting through us, use the address of 799 * the interface that is the closest to the packet source. 800 * When we don't have a route back to the packet source, stop here 801 * and drop the packet. 802 */ 803 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 804 m_freem(m); 805 ICMPSTAT_INC(icps_noroute); 806 goto done; 807 } 808 t = nh_ext.nh_src; 809 match: 810 #ifdef MAC 811 mac_netinet_icmp_replyinplace(m); 812 #endif 813 ip->ip_src = t; 814 ip->ip_ttl = V_ip_defttl; 815 816 if (optlen > 0) { 817 register u_char *cp; 818 int opt, cnt; 819 u_int len; 820 821 /* 822 * Retrieve any source routing from the incoming packet; 823 * add on any record-route or timestamp options. 824 */ 825 cp = (u_char *) (ip + 1); 826 if ((opts = ip_srcroute(m)) == NULL && 827 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 828 opts->m_len = sizeof(struct in_addr); 829 mtod(opts, struct in_addr *)->s_addr = 0; 830 } 831 if (opts) { 832 #ifdef ICMPPRINTFS 833 if (icmpprintfs) 834 printf("icmp_reflect optlen %d rt %d => ", 835 optlen, opts->m_len); 836 #endif 837 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 838 opt = cp[IPOPT_OPTVAL]; 839 if (opt == IPOPT_EOL) 840 break; 841 if (opt == IPOPT_NOP) 842 len = 1; 843 else { 844 if (cnt < IPOPT_OLEN + sizeof(*cp)) 845 break; 846 len = cp[IPOPT_OLEN]; 847 if (len < IPOPT_OLEN + sizeof(*cp) || 848 len > cnt) 849 break; 850 } 851 /* 852 * Should check for overflow, but it "can't happen" 853 */ 854 if (opt == IPOPT_RR || opt == IPOPT_TS || 855 opt == IPOPT_SECURITY) { 856 bcopy((caddr_t)cp, 857 mtod(opts, caddr_t) + opts->m_len, len); 858 opts->m_len += len; 859 } 860 } 861 /* Terminate & pad, if necessary */ 862 cnt = opts->m_len % 4; 863 if (cnt) { 864 for (; cnt < 4; cnt++) { 865 *(mtod(opts, caddr_t) + opts->m_len) = 866 IPOPT_EOL; 867 opts->m_len++; 868 } 869 } 870 #ifdef ICMPPRINTFS 871 if (icmpprintfs) 872 printf("%d\n", opts->m_len); 873 #endif 874 } 875 ip_stripoptions(m); 876 } 877 m_tag_delete_nonpersistent(m); 878 m->m_flags &= ~(M_BCAST|M_MCAST); 879 icmp_send(m, opts); 880 done: 881 if (opts) 882 (void)m_free(opts); 883 } 884 885 /* 886 * Send an icmp packet back to the ip level, 887 * after supplying a checksum. 888 */ 889 static void 890 icmp_send(struct mbuf *m, struct mbuf *opts) 891 { 892 register struct ip *ip = mtod(m, struct ip *); 893 register int hlen; 894 register struct icmp *icp; 895 896 hlen = ip->ip_hl << 2; 897 m->m_data += hlen; 898 m->m_len -= hlen; 899 icp = mtod(m, struct icmp *); 900 icp->icmp_cksum = 0; 901 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 902 m->m_data -= hlen; 903 m->m_len += hlen; 904 m->m_pkthdr.rcvif = (struct ifnet *)0; 905 #ifdef ICMPPRINTFS 906 if (icmpprintfs) { 907 char dstbuf[INET_ADDRSTRLEN]; 908 char srcbuf[INET_ADDRSTRLEN]; 909 910 printf("icmp_send dst %s src %s\n", 911 inet_ntoa_r(ip->ip_dst, dstbuf), 912 inet_ntoa_r(ip->ip_src, srcbuf)); 913 } 914 #endif 915 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 916 } 917 918 /* 919 * Return milliseconds since 00:00 UTC in network format. 920 */ 921 uint32_t 922 iptime(void) 923 { 924 struct timeval atv; 925 u_long t; 926 927 getmicrotime(&atv); 928 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 929 return (htonl(t)); 930 } 931 932 /* 933 * Return the next larger or smaller MTU plateau (table from RFC 1191) 934 * given current value MTU. If DIR is less than zero, a larger plateau 935 * is returned; otherwise, a smaller value is returned. 936 */ 937 int 938 ip_next_mtu(int mtu, int dir) 939 { 940 static int mtutab[] = { 941 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 942 296, 68, 0 943 }; 944 int i, size; 945 946 size = (sizeof mtutab) / (sizeof mtutab[0]); 947 if (dir >= 0) { 948 for (i = 0; i < size; i++) 949 if (mtu > mtutab[i]) 950 return mtutab[i]; 951 } else { 952 for (i = size - 1; i >= 0; i--) 953 if (mtu < mtutab[i]) 954 return mtutab[i]; 955 if (mtu == mtutab[0]) 956 return mtutab[0]; 957 } 958 return 0; 959 } 960 #endif /* INET */ 961 962 963 /* 964 * badport_bandlim() - check for ICMP bandwidth limit 965 * 966 * Return 0 if it is ok to send an ICMP error response, -1 if we have 967 * hit our bandwidth limit and it is not ok. 968 * 969 * If icmplim is <= 0, the feature is disabled and 0 is returned. 970 * 971 * For now we separate the TCP and UDP subsystems w/ different 'which' 972 * values. We may eventually remove this separation (and simplify the 973 * code further). 974 * 975 * Note that the printing of the error message is delayed so we can 976 * properly print the icmp error rate that the system was trying to do 977 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 978 * the 'final' error, but it doesn't make sense to solve the printing 979 * delay with more complex code. 980 */ 981 982 int 983 badport_bandlim(int which) 984 { 985 986 #define N(a) (sizeof (a) / sizeof (a[0])) 987 static struct rate { 988 const char *type; 989 struct timeval lasttime; 990 int curpps; 991 } rates[BANDLIM_MAX+1] = { 992 { "icmp unreach response" }, 993 { "icmp ping response" }, 994 { "icmp tstamp response" }, 995 { "closed port RST response" }, 996 { "open port RST response" }, 997 { "icmp6 unreach response" }, 998 { "sctp ootb response" } 999 }; 1000 1001 /* 1002 * Return ok status if feature disabled or argument out of range. 1003 */ 1004 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1005 struct rate *r = &rates[which]; 1006 int opps = r->curpps; 1007 1008 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1009 return -1; /* discard packet */ 1010 /* 1011 * If we've dropped below the threshold after having 1012 * rate-limited traffic print the message. This preserves 1013 * the previous behaviour at the expense of added complexity. 1014 */ 1015 if (V_icmplim_output && opps > V_icmplim) 1016 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1017 r->type, opps, V_icmplim); 1018 } 1019 return 0; /* okay to send packet */ 1020 #undef N 1021 }
Cache object: 2a3109b3e4246dbff9530e6711d65c04
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