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("$FreeBSD$"); 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_VNET | CTLFLAG_RW, 155 &VNET_NAME(icmptstamprepl), 0, 156 "Respond to ICMP Timestamp packets"); 157 158 static VNET_DEFINE(int, error_keeptags) = 0; 159 #define V_error_keeptags VNET(error_keeptags) 160 SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW, 161 &VNET_NAME(error_keeptags), 0, 162 "ICMP error response keeps copy of mbuf_tags of original packet"); 163 164 #ifdef ICMPPRINTFS 165 int icmpprintfs = 0; 166 #endif 167 168 static void icmp_reflect(struct mbuf *); 169 static void icmp_send(struct mbuf *, struct mbuf *); 170 171 extern struct protosw inetsw[]; 172 173 /* 174 * Kernel module interface for updating icmpstat. The argument is an index 175 * into icmpstat treated as an array of u_long. While this encodes the 176 * general layout of icmpstat into the caller, it doesn't encode its 177 * location, so that future changes to add, for example, per-CPU stats 178 * support won't cause binary compatibility problems for kernel modules. 179 */ 180 void 181 kmod_icmpstat_inc(int statnum) 182 { 183 184 counter_u64_add(VNET(icmpstat)[statnum], 1); 185 } 186 187 /* 188 * Generate an error packet of type error 189 * in response to bad packet ip. 190 */ 191 void 192 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 193 { 194 struct ip *oip, *nip; 195 struct icmp *icp; 196 struct mbuf *m; 197 unsigned icmplen, icmpelen, nlen, oiphlen; 198 199 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", 200 __func__)); 201 202 if (type != ICMP_REDIRECT) 203 ICMPSTAT_INC(icps_error); 204 /* 205 * Don't send error: 206 * if the original packet was encrypted. 207 * if not the first fragment of message. 208 * in response to a multicast or broadcast packet. 209 * if the old packet protocol was an ICMP error message. 210 */ 211 if (n->m_flags & M_DECRYPTED) 212 goto freeit; 213 if (n->m_flags & (M_BCAST|M_MCAST)) 214 goto freeit; 215 216 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */ 217 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) 218 goto freeit; 219 oip = mtod(n, struct ip *); 220 oiphlen = oip->ip_hl << 2; 221 if (n->m_len < oiphlen + ICMP_MINLEN) 222 goto freeit; 223 #ifdef ICMPPRINTFS 224 if (icmpprintfs) 225 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 226 #endif 227 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 228 goto freeit; 229 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 230 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + 231 oiphlen))->icmp_type)) { 232 ICMPSTAT_INC(icps_oldicmp); 233 goto freeit; 234 } 235 /* 236 * Calculate length to quote from original packet and 237 * prevent the ICMP mbuf from overflowing. 238 * Unfortunately this is non-trivial since ip_forward() 239 * sends us truncated packets. 240 */ 241 nlen = m_length(n, NULL); 242 if (oip->ip_p == IPPROTO_TCP) { 243 struct tcphdr *th; 244 int tcphlen; 245 246 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 247 n->m_next == NULL) 248 goto stdreply; 249 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 250 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL) 251 goto freeit; 252 oip = mtod(n, struct ip *); 253 th = mtodo(n, oiphlen); 254 tcphlen = th->th_off << 2; 255 if (tcphlen < sizeof(struct tcphdr)) 256 goto freeit; 257 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 258 goto freeit; 259 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 260 goto stdreply; 261 if (n->m_len < oiphlen + tcphlen && 262 (n = m_pullup(n, oiphlen + tcphlen)) == NULL) 263 goto freeit; 264 icmpelen = max(tcphlen, min(V_icmp_quotelen, 265 ntohs(oip->ip_len) - oiphlen)); 266 } else if (oip->ip_p == IPPROTO_SCTP) { 267 struct sctphdr *sh; 268 struct sctp_chunkhdr *ch; 269 270 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr)) 271 goto stdreply; 272 if (oiphlen + sizeof(struct sctphdr) > n->m_len && 273 n->m_next == NULL) 274 goto stdreply; 275 if (n->m_len < oiphlen + sizeof(struct sctphdr) && 276 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL) 277 goto freeit; 278 oip = mtod(n, struct ip *); 279 icmpelen = max(sizeof(struct sctphdr), 280 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 281 sh = mtodo(n, oiphlen); 282 if (ntohl(sh->v_tag) == 0 && 283 ntohs(oip->ip_len) >= oiphlen + 284 sizeof(struct sctphdr) + 8 && 285 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 || 286 n->m_next != NULL)) { 287 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 && 288 (n = m_pullup(n, oiphlen + 289 sizeof(struct sctphdr) + 8)) == NULL) 290 goto freeit; 291 oip = mtod(n, struct ip *); 292 sh = mtodo(n, oiphlen); 293 ch = (struct sctp_chunkhdr *)(sh + 1); 294 if (ch->chunk_type == SCTP_INITIATION) { 295 icmpelen = max(sizeof(struct sctphdr) + 8, 296 min(V_icmp_quotelen, ntohs(oip->ip_len) - 297 oiphlen)); 298 } 299 } 300 } else 301 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - 302 oiphlen)); 303 304 icmplen = min(oiphlen + icmpelen, nlen); 305 if (icmplen < sizeof(struct ip)) 306 goto freeit; 307 308 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 309 m = m_gethdr(M_NOWAIT, MT_DATA); 310 else 311 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 312 if (m == NULL) 313 goto freeit; 314 #ifdef MAC 315 mac_netinet_icmp_reply(n, m); 316 #endif 317 icmplen = min(icmplen, M_TRAILINGSPACE(m) - 318 sizeof(struct ip) - ICMP_MINLEN); 319 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen); 320 m->m_data += sizeof(struct ip); 321 m->m_len = ICMP_MINLEN + icmplen; 322 323 /* XXX MRT make the outgoing packet use the same FIB 324 * that was associated with the incoming packet 325 */ 326 M_SETFIB(m, M_GETFIB(n)); 327 icp = mtod(m, struct icmp *); 328 ICMPSTAT_INC(icps_outhist[type]); 329 icp->icmp_type = type; 330 if (type == ICMP_REDIRECT) 331 icp->icmp_gwaddr.s_addr = dest; 332 else { 333 icp->icmp_void = 0; 334 /* 335 * The following assignments assume an overlay with the 336 * just zeroed icmp_void field. 337 */ 338 if (type == ICMP_PARAMPROB) { 339 icp->icmp_pptr = code; 340 code = 0; 341 } else if (type == ICMP_UNREACH && 342 code == ICMP_UNREACH_NEEDFRAG && mtu) { 343 icp->icmp_nextmtu = htons(mtu); 344 } 345 } 346 icp->icmp_code = code; 347 348 /* 349 * Copy the quotation into ICMP message and 350 * convert quoted IP header back to network representation. 351 */ 352 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 353 nip = &icp->icmp_ip; 354 355 /* 356 * Set up ICMP message mbuf and copy old IP header (without options 357 * in front of ICMP message. 358 * If the original mbuf was meant to bypass the firewall, the error 359 * reply should bypass as well. 360 */ 361 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 362 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip), 363 ("insufficient space for ip header")); 364 m->m_data -= sizeof(struct ip); 365 m->m_len += sizeof(struct ip); 366 m->m_pkthdr.len = m->m_len; 367 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 368 nip = mtod(m, struct ip *); 369 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 370 nip->ip_len = htons(m->m_len); 371 nip->ip_v = IPVERSION; 372 nip->ip_hl = 5; 373 nip->ip_p = IPPROTO_ICMP; 374 nip->ip_tos = 0; 375 nip->ip_off = 0; 376 377 if (V_error_keeptags) 378 m_tag_copy_chain(m, n, M_NOWAIT); 379 380 icmp_reflect(m); 381 382 freeit: 383 m_freem(n); 384 } 385 386 /* 387 * Process a received ICMP message. 388 */ 389 int 390 icmp_input(struct mbuf **mp, int *offp, int proto) 391 { 392 struct icmp *icp; 393 struct in_ifaddr *ia; 394 struct mbuf *m = *mp; 395 struct ip *ip = mtod(m, struct ip *); 396 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 397 int hlen = *offp; 398 int icmplen = ntohs(ip->ip_len) - *offp; 399 int i, code; 400 void (*ctlfunc)(int, struct sockaddr *, void *); 401 int fibnum; 402 403 *mp = NULL; 404 405 /* 406 * Locate icmp structure in mbuf, and check 407 * that not corrupted and of at least minimum length. 408 */ 409 #ifdef ICMPPRINTFS 410 if (icmpprintfs) { 411 char srcbuf[INET_ADDRSTRLEN]; 412 char dstbuf[INET_ADDRSTRLEN]; 413 414 printf("icmp_input from %s to %s, len %d\n", 415 inet_ntoa_r(ip->ip_src, srcbuf), 416 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen); 417 } 418 #endif 419 if (icmplen < ICMP_MINLEN) { 420 ICMPSTAT_INC(icps_tooshort); 421 goto freeit; 422 } 423 i = hlen + min(icmplen, ICMP_ADVLENMIN); 424 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 425 ICMPSTAT_INC(icps_tooshort); 426 return (IPPROTO_DONE); 427 } 428 ip = mtod(m, struct ip *); 429 m->m_len -= hlen; 430 m->m_data += hlen; 431 icp = mtod(m, struct icmp *); 432 if (in_cksum(m, icmplen)) { 433 ICMPSTAT_INC(icps_checksum); 434 goto freeit; 435 } 436 m->m_len += hlen; 437 m->m_data -= hlen; 438 439 #ifdef ICMPPRINTFS 440 if (icmpprintfs) 441 printf("icmp_input, type %d code %d\n", icp->icmp_type, 442 icp->icmp_code); 443 #endif 444 445 /* 446 * Message type specific processing. 447 */ 448 if (icp->icmp_type > ICMP_MAXTYPE) 449 goto raw; 450 451 /* Initialize */ 452 bzero(&icmpsrc, sizeof(icmpsrc)); 453 icmpsrc.sin_len = sizeof(struct sockaddr_in); 454 icmpsrc.sin_family = AF_INET; 455 bzero(&icmpdst, sizeof(icmpdst)); 456 icmpdst.sin_len = sizeof(struct sockaddr_in); 457 icmpdst.sin_family = AF_INET; 458 bzero(&icmpgw, sizeof(icmpgw)); 459 icmpgw.sin_len = sizeof(struct sockaddr_in); 460 icmpgw.sin_family = AF_INET; 461 462 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 463 code = icp->icmp_code; 464 switch (icp->icmp_type) { 465 466 case ICMP_UNREACH: 467 switch (code) { 468 case ICMP_UNREACH_NET: 469 case ICMP_UNREACH_HOST: 470 case ICMP_UNREACH_SRCFAIL: 471 case ICMP_UNREACH_NET_UNKNOWN: 472 case ICMP_UNREACH_HOST_UNKNOWN: 473 case ICMP_UNREACH_ISOLATED: 474 case ICMP_UNREACH_TOSNET: 475 case ICMP_UNREACH_TOSHOST: 476 case ICMP_UNREACH_HOST_PRECEDENCE: 477 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 478 code = PRC_UNREACH_NET; 479 break; 480 481 case ICMP_UNREACH_NEEDFRAG: 482 code = PRC_MSGSIZE; 483 break; 484 485 /* 486 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 487 * Treat subcodes 2,3 as immediate RST 488 */ 489 case ICMP_UNREACH_PROTOCOL: 490 code = PRC_UNREACH_PROTOCOL; 491 break; 492 case ICMP_UNREACH_PORT: 493 code = PRC_UNREACH_PORT; 494 break; 495 496 case ICMP_UNREACH_NET_PROHIB: 497 case ICMP_UNREACH_HOST_PROHIB: 498 case ICMP_UNREACH_FILTER_PROHIB: 499 code = PRC_UNREACH_ADMIN_PROHIB; 500 break; 501 502 default: 503 goto badcode; 504 } 505 goto deliver; 506 507 case ICMP_TIMXCEED: 508 if (code > 1) 509 goto badcode; 510 code += PRC_TIMXCEED_INTRANS; 511 goto deliver; 512 513 case ICMP_PARAMPROB: 514 if (code > 1) 515 goto badcode; 516 code = PRC_PARAMPROB; 517 deliver: 518 /* 519 * Problem with datagram; advise higher level routines. 520 */ 521 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 522 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 523 ICMPSTAT_INC(icps_badlen); 524 goto freeit; 525 } 526 /* Discard ICMP's in response to multicast packets */ 527 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 528 goto badcode; 529 #ifdef ICMPPRINTFS 530 if (icmpprintfs) 531 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 532 #endif 533 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 534 /* 535 * XXX if the packet contains [IPv4 AH TCP], we can't make a 536 * notification to TCP layer. 537 */ 538 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 539 ip_stripoptions(m); 540 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 541 /* This should actually not happen */ 542 ICMPSTAT_INC(icps_tooshort); 543 return (IPPROTO_DONE); 544 } 545 ip = mtod(m, struct ip *); 546 icp = (struct icmp *)(ip + 1); 547 /* 548 * The upper layer handler can rely on: 549 * - The outer IP header has no options. 550 * - The outer IP header, the ICMP header, the inner IP header, 551 * and the first n bytes of the inner payload are contiguous. 552 * n is at least 8, but might be larger based on 553 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 554 */ 555 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 556 if (ctlfunc) 557 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 558 (void *)&icp->icmp_ip); 559 break; 560 561 badcode: 562 ICMPSTAT_INC(icps_badcode); 563 break; 564 565 case ICMP_ECHO: 566 if (!V_icmpbmcastecho 567 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 568 ICMPSTAT_INC(icps_bmcastecho); 569 break; 570 } 571 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 572 goto freeit; 573 icp->icmp_type = ICMP_ECHOREPLY; 574 goto reflect; 575 576 case ICMP_TSTAMP: 577 if (V_icmptstamprepl == 0) 578 break; 579 if (!V_icmpbmcastecho 580 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 581 ICMPSTAT_INC(icps_bmcasttstamp); 582 break; 583 } 584 if (icmplen < ICMP_TSLEN) { 585 ICMPSTAT_INC(icps_badlen); 586 break; 587 } 588 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 589 goto freeit; 590 icp->icmp_type = ICMP_TSTAMPREPLY; 591 icp->icmp_rtime = iptime(); 592 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 593 goto reflect; 594 595 case ICMP_MASKREQ: 596 if (V_icmpmaskrepl == 0) 597 break; 598 /* 599 * We are not able to respond with all ones broadcast 600 * unless we receive it over a point-to-point interface. 601 */ 602 if (icmplen < ICMP_MASKLEN) 603 break; 604 switch (ip->ip_dst.s_addr) { 605 606 case INADDR_BROADCAST: 607 case INADDR_ANY: 608 icmpdst.sin_addr = ip->ip_src; 609 break; 610 611 default: 612 icmpdst.sin_addr = ip->ip_dst; 613 } 614 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 615 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 616 if (ia == NULL) 617 break; 618 if (ia->ia_ifp == NULL) { 619 ifa_free(&ia->ia_ifa); 620 break; 621 } 622 icp->icmp_type = ICMP_MASKREPLY; 623 if (V_icmpmaskfake == 0) 624 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 625 else 626 icp->icmp_mask = V_icmpmaskfake; 627 if (ip->ip_src.s_addr == 0) { 628 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 629 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 630 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 631 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 632 } 633 ifa_free(&ia->ia_ifa); 634 reflect: 635 ICMPSTAT_INC(icps_reflect); 636 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 637 icmp_reflect(m); 638 return (IPPROTO_DONE); 639 640 case ICMP_REDIRECT: 641 if (V_log_redirect) { 642 u_long src, dst, gw; 643 644 src = ntohl(ip->ip_src.s_addr); 645 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 646 gw = ntohl(icp->icmp_gwaddr.s_addr); 647 printf("icmp redirect from %d.%d.%d.%d: " 648 "%d.%d.%d.%d => %d.%d.%d.%d\n", 649 (int)(src >> 24), (int)((src >> 16) & 0xff), 650 (int)((src >> 8) & 0xff), (int)(src & 0xff), 651 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 652 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 653 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 654 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 655 } 656 /* 657 * RFC1812 says we must ignore ICMP redirects if we 658 * are acting as router. 659 */ 660 if (V_drop_redirect || V_ipforwarding) 661 break; 662 if (code > 3) 663 goto badcode; 664 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 665 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 666 ICMPSTAT_INC(icps_badlen); 667 break; 668 } 669 /* 670 * Short circuit routing redirects to force 671 * immediate change in the kernel's routing 672 * tables. The message is also handed to anyone 673 * listening on a raw socket (e.g. the routing 674 * daemon for use in updating its tables). 675 */ 676 icmpgw.sin_addr = ip->ip_src; 677 icmpdst.sin_addr = icp->icmp_gwaddr; 678 #ifdef ICMPPRINTFS 679 if (icmpprintfs) { 680 char dstbuf[INET_ADDRSTRLEN]; 681 char gwbuf[INET_ADDRSTRLEN]; 682 683 printf("redirect dst %s to %s\n", 684 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 685 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 686 } 687 #endif 688 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 689 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 690 in_rtredirect((struct sockaddr *)&icmpsrc, 691 (struct sockaddr *)&icmpdst, 692 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 693 (struct sockaddr *)&icmpgw, fibnum); 694 } 695 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 696 break; 697 698 /* 699 * No kernel processing for the following; 700 * just fall through to send to raw listener. 701 */ 702 case ICMP_ECHOREPLY: 703 case ICMP_ROUTERADVERT: 704 case ICMP_ROUTERSOLICIT: 705 case ICMP_TSTAMPREPLY: 706 case ICMP_IREQREPLY: 707 case ICMP_MASKREPLY: 708 case ICMP_SOURCEQUENCH: 709 default: 710 break; 711 } 712 713 raw: 714 *mp = m; 715 rip_input(mp, offp, proto); 716 return (IPPROTO_DONE); 717 718 freeit: 719 m_freem(m); 720 return (IPPROTO_DONE); 721 } 722 723 /* 724 * Reflect the ip packet back to the source 725 */ 726 static void 727 icmp_reflect(struct mbuf *m) 728 { 729 struct rm_priotracker in_ifa_tracker; 730 struct ip *ip = mtod(m, struct ip *); 731 struct ifaddr *ifa; 732 struct ifnet *ifp; 733 struct in_ifaddr *ia; 734 struct in_addr t; 735 struct nhop4_extended nh_ext; 736 struct mbuf *opts = NULL; 737 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 738 739 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 740 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 741 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 742 m_freem(m); /* Bad return address */ 743 ICMPSTAT_INC(icps_badaddr); 744 goto done; /* Ip_output() will check for broadcast */ 745 } 746 747 t = ip->ip_dst; 748 ip->ip_dst = ip->ip_src; 749 750 /* 751 * Source selection for ICMP replies: 752 * 753 * If the incoming packet was addressed directly to one of our 754 * own addresses, use dst as the src for the reply. 755 */ 756 IN_IFADDR_RLOCK(&in_ifa_tracker); 757 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 758 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 759 t = IA_SIN(ia)->sin_addr; 760 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 761 goto match; 762 } 763 } 764 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 765 766 /* 767 * If the incoming packet was addressed to one of our broadcast 768 * addresses, use the first non-broadcast address which corresponds 769 * to the incoming interface. 770 */ 771 ifp = m->m_pkthdr.rcvif; 772 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 773 IF_ADDR_RLOCK(ifp); 774 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 775 if (ifa->ifa_addr->sa_family != AF_INET) 776 continue; 777 ia = ifatoia(ifa); 778 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 779 t.s_addr) { 780 t = IA_SIN(ia)->sin_addr; 781 IF_ADDR_RUNLOCK(ifp); 782 goto match; 783 } 784 } 785 IF_ADDR_RUNLOCK(ifp); 786 } 787 /* 788 * If the packet was transiting through us, use the address of 789 * the interface the packet came through in. If that interface 790 * doesn't have a suitable IP address, the normal selection 791 * criteria apply. 792 */ 793 if (V_icmp_rfi && ifp != NULL) { 794 IF_ADDR_RLOCK(ifp); 795 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 796 if (ifa->ifa_addr->sa_family != AF_INET) 797 continue; 798 ia = ifatoia(ifa); 799 t = IA_SIN(ia)->sin_addr; 800 IF_ADDR_RUNLOCK(ifp); 801 goto match; 802 } 803 IF_ADDR_RUNLOCK(ifp); 804 } 805 /* 806 * If the incoming packet was not addressed directly to us, use 807 * designated interface for icmp replies specified by sysctl 808 * net.inet.icmp.reply_src (default not set). Otherwise continue 809 * with normal source selection. 810 */ 811 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 812 IF_ADDR_RLOCK(ifp); 813 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 814 if (ifa->ifa_addr->sa_family != AF_INET) 815 continue; 816 ia = ifatoia(ifa); 817 t = IA_SIN(ia)->sin_addr; 818 IF_ADDR_RUNLOCK(ifp); 819 goto match; 820 } 821 IF_ADDR_RUNLOCK(ifp); 822 } 823 /* 824 * If the packet was transiting through us, use the address of 825 * the interface that is the closest to the packet source. 826 * When we don't have a route back to the packet source, stop here 827 * and drop the packet. 828 */ 829 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 830 m_freem(m); 831 ICMPSTAT_INC(icps_noroute); 832 goto done; 833 } 834 t = nh_ext.nh_src; 835 match: 836 #ifdef MAC 837 mac_netinet_icmp_replyinplace(m); 838 #endif 839 ip->ip_src = t; 840 ip->ip_ttl = V_ip_defttl; 841 842 if (optlen > 0) { 843 u_char *cp; 844 int opt, cnt; 845 u_int len; 846 847 /* 848 * Retrieve any source routing from the incoming packet; 849 * add on any record-route or timestamp options. 850 */ 851 cp = (u_char *) (ip + 1); 852 if ((opts = ip_srcroute(m)) == NULL && 853 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 854 opts->m_len = sizeof(struct in_addr); 855 mtod(opts, struct in_addr *)->s_addr = 0; 856 } 857 if (opts) { 858 #ifdef ICMPPRINTFS 859 if (icmpprintfs) 860 printf("icmp_reflect optlen %d rt %d => ", 861 optlen, opts->m_len); 862 #endif 863 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 864 opt = cp[IPOPT_OPTVAL]; 865 if (opt == IPOPT_EOL) 866 break; 867 if (opt == IPOPT_NOP) 868 len = 1; 869 else { 870 if (cnt < IPOPT_OLEN + sizeof(*cp)) 871 break; 872 len = cp[IPOPT_OLEN]; 873 if (len < IPOPT_OLEN + sizeof(*cp) || 874 len > cnt) 875 break; 876 } 877 /* 878 * Should check for overflow, but it "can't happen" 879 */ 880 if (opt == IPOPT_RR || opt == IPOPT_TS || 881 opt == IPOPT_SECURITY) { 882 bcopy((caddr_t)cp, 883 mtod(opts, caddr_t) + opts->m_len, len); 884 opts->m_len += len; 885 } 886 } 887 /* Terminate & pad, if necessary */ 888 cnt = opts->m_len % 4; 889 if (cnt) { 890 for (; cnt < 4; cnt++) { 891 *(mtod(opts, caddr_t) + opts->m_len) = 892 IPOPT_EOL; 893 opts->m_len++; 894 } 895 } 896 #ifdef ICMPPRINTFS 897 if (icmpprintfs) 898 printf("%d\n", opts->m_len); 899 #endif 900 } 901 ip_stripoptions(m); 902 } 903 m_tag_delete_nonpersistent(m); 904 m->m_flags &= ~(M_BCAST|M_MCAST); 905 icmp_send(m, opts); 906 done: 907 if (opts) 908 (void)m_free(opts); 909 } 910 911 /* 912 * Send an icmp packet back to the ip level, 913 * after supplying a checksum. 914 */ 915 static void 916 icmp_send(struct mbuf *m, struct mbuf *opts) 917 { 918 struct ip *ip = mtod(m, struct ip *); 919 int hlen; 920 struct icmp *icp; 921 922 hlen = ip->ip_hl << 2; 923 m->m_data += hlen; 924 m->m_len -= hlen; 925 icp = mtod(m, struct icmp *); 926 icp->icmp_cksum = 0; 927 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 928 m->m_data -= hlen; 929 m->m_len += hlen; 930 m->m_pkthdr.rcvif = (struct ifnet *)0; 931 #ifdef ICMPPRINTFS 932 if (icmpprintfs) { 933 char dstbuf[INET_ADDRSTRLEN]; 934 char srcbuf[INET_ADDRSTRLEN]; 935 936 printf("icmp_send dst %s src %s\n", 937 inet_ntoa_r(ip->ip_dst, dstbuf), 938 inet_ntoa_r(ip->ip_src, srcbuf)); 939 } 940 #endif 941 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 942 } 943 944 /* 945 * Return milliseconds since 00:00 UTC in network format. 946 */ 947 uint32_t 948 iptime(void) 949 { 950 struct timeval atv; 951 u_long t; 952 953 getmicrotime(&atv); 954 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 955 return (htonl(t)); 956 } 957 958 /* 959 * Return the next larger or smaller MTU plateau (table from RFC 1191) 960 * given current value MTU. If DIR is less than zero, a larger plateau 961 * is returned; otherwise, a smaller value is returned. 962 */ 963 int 964 ip_next_mtu(int mtu, int dir) 965 { 966 static int mtutab[] = { 967 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 968 296, 68, 0 969 }; 970 int i, size; 971 972 size = (sizeof mtutab) / (sizeof mtutab[0]); 973 if (dir >= 0) { 974 for (i = 0; i < size; i++) 975 if (mtu > mtutab[i]) 976 return mtutab[i]; 977 } else { 978 for (i = size - 1; i >= 0; i--) 979 if (mtu < mtutab[i]) 980 return mtutab[i]; 981 if (mtu == mtutab[0]) 982 return mtutab[0]; 983 } 984 return 0; 985 } 986 #endif /* INET */ 987 988 989 /* 990 * badport_bandlim() - check for ICMP bandwidth limit 991 * 992 * Return 0 if it is ok to send an ICMP error response, -1 if we have 993 * hit our bandwidth limit and it is not ok. 994 * 995 * If icmplim is <= 0, the feature is disabled and 0 is returned. 996 * 997 * For now we separate the TCP and UDP subsystems w/ different 'which' 998 * values. We may eventually remove this separation (and simplify the 999 * code further). 1000 * 1001 * Note that the printing of the error message is delayed so we can 1002 * properly print the icmp error rate that the system was trying to do 1003 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 1004 * the 'final' error, but it doesn't make sense to solve the printing 1005 * delay with more complex code. 1006 */ 1007 1008 int 1009 badport_bandlim(int which) 1010 { 1011 1012 #define N(a) (sizeof (a) / sizeof (a[0])) 1013 static struct rate { 1014 const char *type; 1015 struct timeval lasttime; 1016 int curpps; 1017 } rates[BANDLIM_MAX+1] = { 1018 { "icmp unreach response" }, 1019 { "icmp ping response" }, 1020 { "icmp tstamp response" }, 1021 { "closed port RST response" }, 1022 { "open port RST response" }, 1023 { "icmp6 unreach response" }, 1024 { "sctp ootb response" } 1025 }; 1026 1027 /* 1028 * Return ok status if feature disabled or argument out of range. 1029 */ 1030 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1031 struct rate *r = &rates[which]; 1032 int opps = r->curpps; 1033 1034 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1035 return -1; /* discard packet */ 1036 /* 1037 * If we've dropped below the threshold after having 1038 * rate-limited traffic print the message. This preserves 1039 * the previous behaviour at the expense of added complexity. 1040 */ 1041 if (V_icmplim_output && opps > V_icmplim) 1042 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1043 r->type, opps, V_icmplim); 1044 } 1045 return 0; /* okay to send packet */ 1046 #undef N 1047 }
Cache object: 0636eddffe3acd7ed796158055aa2508
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