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 * 3. 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_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 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 295 stdreply: 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); 368 369 freeit: 370 m_freem(n); 371 } 372 373 /* 374 * Process a received ICMP message. 375 */ 376 int 377 icmp_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 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 559 goto freeit; 560 icp->icmp_type = ICMP_ECHOREPLY; 561 goto reflect; 562 563 case ICMP_TSTAMP: 564 if (V_icmptstamprepl == 0) 565 break; 566 if (!V_icmpbmcastecho 567 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 568 ICMPSTAT_INC(icps_bmcasttstamp); 569 break; 570 } 571 if (icmplen < ICMP_TSLEN) { 572 ICMPSTAT_INC(icps_badlen); 573 break; 574 } 575 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 576 goto freeit; 577 icp->icmp_type = ICMP_TSTAMPREPLY; 578 icp->icmp_rtime = iptime(); 579 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 580 goto reflect; 581 582 case ICMP_MASKREQ: 583 if (V_icmpmaskrepl == 0) 584 break; 585 /* 586 * We are not able to respond with all ones broadcast 587 * unless we receive it over a point-to-point interface. 588 */ 589 if (icmplen < ICMP_MASKLEN) 590 break; 591 switch (ip->ip_dst.s_addr) { 592 593 case INADDR_BROADCAST: 594 case INADDR_ANY: 595 icmpdst.sin_addr = ip->ip_src; 596 break; 597 598 default: 599 icmpdst.sin_addr = ip->ip_dst; 600 } 601 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 602 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 603 if (ia == NULL) 604 break; 605 if (ia->ia_ifp == NULL) { 606 ifa_free(&ia->ia_ifa); 607 break; 608 } 609 icp->icmp_type = ICMP_MASKREPLY; 610 if (V_icmpmaskfake == 0) 611 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 612 else 613 icp->icmp_mask = V_icmpmaskfake; 614 if (ip->ip_src.s_addr == 0) { 615 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 616 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 617 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 618 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 619 } 620 ifa_free(&ia->ia_ifa); 621 reflect: 622 ICMPSTAT_INC(icps_reflect); 623 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 624 icmp_reflect(m); 625 return (IPPROTO_DONE); 626 627 case ICMP_REDIRECT: 628 if (V_log_redirect) { 629 u_long src, dst, gw; 630 631 src = ntohl(ip->ip_src.s_addr); 632 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 633 gw = ntohl(icp->icmp_gwaddr.s_addr); 634 printf("icmp redirect from %d.%d.%d.%d: " 635 "%d.%d.%d.%d => %d.%d.%d.%d\n", 636 (int)(src >> 24), (int)((src >> 16) & 0xff), 637 (int)((src >> 8) & 0xff), (int)(src & 0xff), 638 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 639 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 640 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 641 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 642 } 643 /* 644 * RFC1812 says we must ignore ICMP redirects if we 645 * are acting as router. 646 */ 647 if (V_drop_redirect || V_ipforwarding) 648 break; 649 if (code > 3) 650 goto badcode; 651 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 652 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 653 ICMPSTAT_INC(icps_badlen); 654 break; 655 } 656 /* 657 * Short circuit routing redirects to force 658 * immediate change in the kernel's routing 659 * tables. The message is also handed to anyone 660 * listening on a raw socket (e.g. the routing 661 * daemon for use in updating its tables). 662 */ 663 icmpgw.sin_addr = ip->ip_src; 664 icmpdst.sin_addr = icp->icmp_gwaddr; 665 #ifdef ICMPPRINTFS 666 if (icmpprintfs) { 667 char dstbuf[INET_ADDRSTRLEN]; 668 char gwbuf[INET_ADDRSTRLEN]; 669 670 printf("redirect dst %s to %s\n", 671 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf), 672 inet_ntoa_r(icp->icmp_gwaddr, gwbuf)); 673 } 674 #endif 675 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 676 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 677 in_rtredirect((struct sockaddr *)&icmpsrc, 678 (struct sockaddr *)&icmpdst, 679 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 680 (struct sockaddr *)&icmpgw, fibnum); 681 } 682 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 683 break; 684 685 /* 686 * No kernel processing for the following; 687 * just fall through to send to raw listener. 688 */ 689 case ICMP_ECHOREPLY: 690 case ICMP_ROUTERADVERT: 691 case ICMP_ROUTERSOLICIT: 692 case ICMP_TSTAMPREPLY: 693 case ICMP_IREQREPLY: 694 case ICMP_MASKREPLY: 695 case ICMP_SOURCEQUENCH: 696 default: 697 break; 698 } 699 700 raw: 701 *mp = m; 702 rip_input(mp, offp, proto); 703 return (IPPROTO_DONE); 704 705 freeit: 706 m_freem(m); 707 return (IPPROTO_DONE); 708 } 709 710 /* 711 * Reflect the ip packet back to the source 712 */ 713 static void 714 icmp_reflect(struct mbuf *m) 715 { 716 struct rm_priotracker in_ifa_tracker; 717 struct ip *ip = mtod(m, struct ip *); 718 struct ifaddr *ifa; 719 struct ifnet *ifp; 720 struct in_ifaddr *ia; 721 struct in_addr t; 722 struct nhop4_extended nh_ext; 723 struct mbuf *opts = NULL; 724 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 725 726 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 727 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 728 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 729 m_freem(m); /* Bad return address */ 730 ICMPSTAT_INC(icps_badaddr); 731 goto done; /* Ip_output() will check for broadcast */ 732 } 733 734 t = ip->ip_dst; 735 ip->ip_dst = ip->ip_src; 736 737 /* 738 * Source selection for ICMP replies: 739 * 740 * If the incoming packet was addressed directly to one of our 741 * own addresses, use dst as the src for the reply. 742 */ 743 IN_IFADDR_RLOCK(&in_ifa_tracker); 744 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 745 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 746 t = IA_SIN(ia)->sin_addr; 747 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 748 goto match; 749 } 750 } 751 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 752 753 /* 754 * If the incoming packet was addressed to one of our broadcast 755 * addresses, use the first non-broadcast address which corresponds 756 * to the incoming interface. 757 */ 758 ifp = m->m_pkthdr.rcvif; 759 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 760 IF_ADDR_RLOCK(ifp); 761 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 762 if (ifa->ifa_addr->sa_family != AF_INET) 763 continue; 764 ia = ifatoia(ifa); 765 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 766 t.s_addr) { 767 t = IA_SIN(ia)->sin_addr; 768 IF_ADDR_RUNLOCK(ifp); 769 goto match; 770 } 771 } 772 IF_ADDR_RUNLOCK(ifp); 773 } 774 /* 775 * If the packet was transiting through us, use the address of 776 * the interface the packet came through in. If that interface 777 * doesn't have a suitable IP address, the normal selection 778 * criteria apply. 779 */ 780 if (V_icmp_rfi && ifp != NULL) { 781 IF_ADDR_RLOCK(ifp); 782 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 783 if (ifa->ifa_addr->sa_family != AF_INET) 784 continue; 785 ia = ifatoia(ifa); 786 t = IA_SIN(ia)->sin_addr; 787 IF_ADDR_RUNLOCK(ifp); 788 goto match; 789 } 790 IF_ADDR_RUNLOCK(ifp); 791 } 792 /* 793 * If the incoming packet was not addressed directly to us, use 794 * designated interface for icmp replies specified by sysctl 795 * net.inet.icmp.reply_src (default not set). Otherwise continue 796 * with normal source selection. 797 */ 798 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 799 IF_ADDR_RLOCK(ifp); 800 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 801 if (ifa->ifa_addr->sa_family != AF_INET) 802 continue; 803 ia = ifatoia(ifa); 804 t = IA_SIN(ia)->sin_addr; 805 IF_ADDR_RUNLOCK(ifp); 806 goto match; 807 } 808 IF_ADDR_RUNLOCK(ifp); 809 } 810 /* 811 * If the packet was transiting through us, use the address of 812 * the interface that is the closest to the packet source. 813 * When we don't have a route back to the packet source, stop here 814 * and drop the packet. 815 */ 816 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 817 m_freem(m); 818 ICMPSTAT_INC(icps_noroute); 819 goto done; 820 } 821 t = nh_ext.nh_src; 822 match: 823 #ifdef MAC 824 mac_netinet_icmp_replyinplace(m); 825 #endif 826 ip->ip_src = t; 827 ip->ip_ttl = V_ip_defttl; 828 829 if (optlen > 0) { 830 u_char *cp; 831 int opt, cnt; 832 u_int len; 833 834 /* 835 * Retrieve any source routing from the incoming packet; 836 * add on any record-route or timestamp options. 837 */ 838 cp = (u_char *) (ip + 1); 839 if ((opts = ip_srcroute(m)) == NULL && 840 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 841 opts->m_len = sizeof(struct in_addr); 842 mtod(opts, struct in_addr *)->s_addr = 0; 843 } 844 if (opts) { 845 #ifdef ICMPPRINTFS 846 if (icmpprintfs) 847 printf("icmp_reflect optlen %d rt %d => ", 848 optlen, opts->m_len); 849 #endif 850 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 851 opt = cp[IPOPT_OPTVAL]; 852 if (opt == IPOPT_EOL) 853 break; 854 if (opt == IPOPT_NOP) 855 len = 1; 856 else { 857 if (cnt < IPOPT_OLEN + sizeof(*cp)) 858 break; 859 len = cp[IPOPT_OLEN]; 860 if (len < IPOPT_OLEN + sizeof(*cp) || 861 len > cnt) 862 break; 863 } 864 /* 865 * Should check for overflow, but it "can't happen" 866 */ 867 if (opt == IPOPT_RR || opt == IPOPT_TS || 868 opt == IPOPT_SECURITY) { 869 bcopy((caddr_t)cp, 870 mtod(opts, caddr_t) + opts->m_len, len); 871 opts->m_len += len; 872 } 873 } 874 /* Terminate & pad, if necessary */ 875 cnt = opts->m_len % 4; 876 if (cnt) { 877 for (; cnt < 4; cnt++) { 878 *(mtod(opts, caddr_t) + opts->m_len) = 879 IPOPT_EOL; 880 opts->m_len++; 881 } 882 } 883 #ifdef ICMPPRINTFS 884 if (icmpprintfs) 885 printf("%d\n", opts->m_len); 886 #endif 887 } 888 ip_stripoptions(m); 889 } 890 m_tag_delete_nonpersistent(m); 891 m->m_flags &= ~(M_BCAST|M_MCAST); 892 icmp_send(m, opts); 893 done: 894 if (opts) 895 (void)m_free(opts); 896 } 897 898 /* 899 * Send an icmp packet back to the ip level, 900 * after supplying a checksum. 901 */ 902 static void 903 icmp_send(struct mbuf *m, struct mbuf *opts) 904 { 905 struct ip *ip = mtod(m, struct ip *); 906 int hlen; 907 struct icmp *icp; 908 909 hlen = ip->ip_hl << 2; 910 m->m_data += hlen; 911 m->m_len -= hlen; 912 icp = mtod(m, struct icmp *); 913 icp->icmp_cksum = 0; 914 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 915 m->m_data -= hlen; 916 m->m_len += hlen; 917 m->m_pkthdr.rcvif = (struct ifnet *)0; 918 #ifdef ICMPPRINTFS 919 if (icmpprintfs) { 920 char dstbuf[INET_ADDRSTRLEN]; 921 char srcbuf[INET_ADDRSTRLEN]; 922 923 printf("icmp_send dst %s src %s\n", 924 inet_ntoa_r(ip->ip_dst, dstbuf), 925 inet_ntoa_r(ip->ip_src, srcbuf)); 926 } 927 #endif 928 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 929 } 930 931 /* 932 * Return milliseconds since 00:00 UTC in network format. 933 */ 934 uint32_t 935 iptime(void) 936 { 937 struct timeval atv; 938 u_long t; 939 940 getmicrotime(&atv); 941 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 942 return (htonl(t)); 943 } 944 945 /* 946 * Return the next larger or smaller MTU plateau (table from RFC 1191) 947 * given current value MTU. If DIR is less than zero, a larger plateau 948 * is returned; otherwise, a smaller value is returned. 949 */ 950 int 951 ip_next_mtu(int mtu, int dir) 952 { 953 static int mtutab[] = { 954 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 955 296, 68, 0 956 }; 957 int i, size; 958 959 size = (sizeof mtutab) / (sizeof mtutab[0]); 960 if (dir >= 0) { 961 for (i = 0; i < size; i++) 962 if (mtu > mtutab[i]) 963 return mtutab[i]; 964 } else { 965 for (i = size - 1; i >= 0; i--) 966 if (mtu < mtutab[i]) 967 return mtutab[i]; 968 if (mtu == mtutab[0]) 969 return mtutab[0]; 970 } 971 return 0; 972 } 973 #endif /* INET */ 974 975 976 /* 977 * badport_bandlim() - check for ICMP bandwidth limit 978 * 979 * Return 0 if it is ok to send an ICMP error response, -1 if we have 980 * hit our bandwidth limit and it is not ok. 981 * 982 * If icmplim is <= 0, the feature is disabled and 0 is returned. 983 * 984 * For now we separate the TCP and UDP subsystems w/ different 'which' 985 * values. We may eventually remove this separation (and simplify the 986 * code further). 987 * 988 * Note that the printing of the error message is delayed so we can 989 * properly print the icmp error rate that the system was trying to do 990 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 991 * the 'final' error, but it doesn't make sense to solve the printing 992 * delay with more complex code. 993 */ 994 struct icmp_rate { 995 const char *descr; 996 struct counter_rate cr; 997 }; 998 static VNET_DEFINE(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 999 { "icmp unreach response" }, 1000 { "icmp ping response" }, 1001 { "icmp tstamp response" }, 1002 { "closed port RST response" }, 1003 { "open port RST response" }, 1004 { "icmp6 unreach response" }, 1005 { "sctp ootb response" } 1006 }; 1007 #define V_icmp_rates VNET(icmp_rates) 1008 1009 static void 1010 icmp_bandlimit_init(void) 1011 { 1012 1013 for (int i = 0; i < BANDLIM_MAX; i++) { 1014 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 1015 V_icmp_rates[i].cr.cr_ticks = ticks; 1016 } 1017 } 1018 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1019 icmp_bandlimit_init, NULL); 1020 1021 static void 1022 icmp_bandlimit_uninit(void) 1023 { 1024 1025 for (int i = 0; i < BANDLIM_MAX; i++) 1026 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1027 } 1028 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1029 icmp_bandlimit_uninit, NULL); 1030 1031 int 1032 badport_bandlim(int which) 1033 { 1034 int64_t pps; 1035 1036 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1037 return (0); 1038 1039 KASSERT(which >= 0 && which < BANDLIM_MAX, 1040 ("%s: which %d", __func__, which)); 1041 1042 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1043 if (pps == -1) 1044 return (-1); 1045 if (pps > 0 && V_icmplim_output) 1046 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1047 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1048 return (0); 1049 } 1050