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_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 buf[4 * sizeof "123"]; 384 strcpy(buf, inet_ntoa(ip->ip_src)); 385 printf("icmp_input from %s to %s, len %d\n", 386 buf, inet_ntoa(ip->ip_dst), icmplen); 387 } 388 #endif 389 if (icmplen < ICMP_MINLEN) { 390 ICMPSTAT_INC(icps_tooshort); 391 goto freeit; 392 } 393 i = hlen + min(icmplen, ICMP_ADVLENMIN); 394 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 395 ICMPSTAT_INC(icps_tooshort); 396 return (IPPROTO_DONE); 397 } 398 ip = mtod(m, struct ip *); 399 m->m_len -= hlen; 400 m->m_data += hlen; 401 icp = mtod(m, struct icmp *); 402 if (in_cksum(m, icmplen)) { 403 ICMPSTAT_INC(icps_checksum); 404 goto freeit; 405 } 406 m->m_len += hlen; 407 m->m_data -= hlen; 408 409 #ifdef ICMPPRINTFS 410 if (icmpprintfs) 411 printf("icmp_input, type %d code %d\n", icp->icmp_type, 412 icp->icmp_code); 413 #endif 414 415 /* 416 * Message type specific processing. 417 */ 418 if (icp->icmp_type > ICMP_MAXTYPE) 419 goto raw; 420 421 /* Initialize */ 422 bzero(&icmpsrc, sizeof(icmpsrc)); 423 icmpsrc.sin_len = sizeof(struct sockaddr_in); 424 icmpsrc.sin_family = AF_INET; 425 bzero(&icmpdst, sizeof(icmpdst)); 426 icmpdst.sin_len = sizeof(struct sockaddr_in); 427 icmpdst.sin_family = AF_INET; 428 bzero(&icmpgw, sizeof(icmpgw)); 429 icmpgw.sin_len = sizeof(struct sockaddr_in); 430 icmpgw.sin_family = AF_INET; 431 432 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 433 code = icp->icmp_code; 434 switch (icp->icmp_type) { 435 436 case ICMP_UNREACH: 437 switch (code) { 438 case ICMP_UNREACH_NET: 439 case ICMP_UNREACH_HOST: 440 case ICMP_UNREACH_SRCFAIL: 441 case ICMP_UNREACH_NET_UNKNOWN: 442 case ICMP_UNREACH_HOST_UNKNOWN: 443 case ICMP_UNREACH_ISOLATED: 444 case ICMP_UNREACH_TOSNET: 445 case ICMP_UNREACH_TOSHOST: 446 case ICMP_UNREACH_HOST_PRECEDENCE: 447 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 448 code = PRC_UNREACH_NET; 449 break; 450 451 case ICMP_UNREACH_NEEDFRAG: 452 code = PRC_MSGSIZE; 453 break; 454 455 /* 456 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 457 * Treat subcodes 2,3 as immediate RST 458 */ 459 case ICMP_UNREACH_PROTOCOL: 460 code = PRC_UNREACH_PROTOCOL; 461 break; 462 case ICMP_UNREACH_PORT: 463 code = PRC_UNREACH_PORT; 464 break; 465 466 case ICMP_UNREACH_NET_PROHIB: 467 case ICMP_UNREACH_HOST_PROHIB: 468 case ICMP_UNREACH_FILTER_PROHIB: 469 code = PRC_UNREACH_ADMIN_PROHIB; 470 break; 471 472 default: 473 goto badcode; 474 } 475 goto deliver; 476 477 case ICMP_TIMXCEED: 478 if (code > 1) 479 goto badcode; 480 code += PRC_TIMXCEED_INTRANS; 481 goto deliver; 482 483 case ICMP_PARAMPROB: 484 if (code > 1) 485 goto badcode; 486 code = PRC_PARAMPROB; 487 deliver: 488 /* 489 * Problem with datagram; advise higher level routines. 490 */ 491 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 492 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 493 ICMPSTAT_INC(icps_badlen); 494 goto freeit; 495 } 496 /* Discard ICMP's in response to multicast packets */ 497 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 498 goto badcode; 499 #ifdef ICMPPRINTFS 500 if (icmpprintfs) 501 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 502 #endif 503 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 504 /* 505 * XXX if the packet contains [IPv4 AH TCP], we can't make a 506 * notification to TCP layer. 507 */ 508 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 509 ip_stripoptions(m); 510 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 511 /* This should actually not happen */ 512 ICMPSTAT_INC(icps_tooshort); 513 return (IPPROTO_DONE); 514 } 515 ip = mtod(m, struct ip *); 516 icp = (struct icmp *)(ip + 1); 517 /* 518 * The upper layer handler can rely on: 519 * - The outer IP header has no options. 520 * - The outer IP header, the ICMP header, the inner IP header, 521 * and the first n bytes of the inner payload are contiguous. 522 * n is at least 8, but might be larger based on 523 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 524 */ 525 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 526 if (ctlfunc) 527 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 528 (void *)&icp->icmp_ip); 529 break; 530 531 badcode: 532 ICMPSTAT_INC(icps_badcode); 533 break; 534 535 case ICMP_ECHO: 536 if (!V_icmpbmcastecho 537 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 538 ICMPSTAT_INC(icps_bmcastecho); 539 break; 540 } 541 icp->icmp_type = ICMP_ECHOREPLY; 542 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 543 goto freeit; 544 else 545 goto reflect; 546 547 case ICMP_TSTAMP: 548 if (V_icmptstamprepl == 0) 549 break; 550 if (!V_icmpbmcastecho 551 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 552 ICMPSTAT_INC(icps_bmcasttstamp); 553 break; 554 } 555 if (icmplen < ICMP_TSLEN) { 556 ICMPSTAT_INC(icps_badlen); 557 break; 558 } 559 icp->icmp_type = ICMP_TSTAMPREPLY; 560 icp->icmp_rtime = iptime(); 561 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 562 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 563 goto freeit; 564 else 565 goto reflect; 566 567 case ICMP_MASKREQ: 568 if (V_icmpmaskrepl == 0) 569 break; 570 /* 571 * We are not able to respond with all ones broadcast 572 * unless we receive it over a point-to-point interface. 573 */ 574 if (icmplen < ICMP_MASKLEN) 575 break; 576 switch (ip->ip_dst.s_addr) { 577 578 case INADDR_BROADCAST: 579 case INADDR_ANY: 580 icmpdst.sin_addr = ip->ip_src; 581 break; 582 583 default: 584 icmpdst.sin_addr = ip->ip_dst; 585 } 586 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 587 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 588 if (ia == NULL) 589 break; 590 if (ia->ia_ifp == NULL) { 591 ifa_free(&ia->ia_ifa); 592 break; 593 } 594 icp->icmp_type = ICMP_MASKREPLY; 595 if (V_icmpmaskfake == 0) 596 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 597 else 598 icp->icmp_mask = V_icmpmaskfake; 599 if (ip->ip_src.s_addr == 0) { 600 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 601 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 602 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 603 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 604 } 605 ifa_free(&ia->ia_ifa); 606 reflect: 607 ICMPSTAT_INC(icps_reflect); 608 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 609 icmp_reflect(m); 610 return (IPPROTO_DONE); 611 612 case ICMP_REDIRECT: 613 if (V_log_redirect) { 614 u_long src, dst, gw; 615 616 src = ntohl(ip->ip_src.s_addr); 617 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 618 gw = ntohl(icp->icmp_gwaddr.s_addr); 619 printf("icmp redirect from %d.%d.%d.%d: " 620 "%d.%d.%d.%d => %d.%d.%d.%d\n", 621 (int)(src >> 24), (int)((src >> 16) & 0xff), 622 (int)((src >> 8) & 0xff), (int)(src & 0xff), 623 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 624 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 625 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 626 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 627 } 628 /* 629 * RFC1812 says we must ignore ICMP redirects if we 630 * are acting as router. 631 */ 632 if (V_drop_redirect || V_ipforwarding) 633 break; 634 if (code > 3) 635 goto badcode; 636 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 637 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 638 ICMPSTAT_INC(icps_badlen); 639 break; 640 } 641 /* 642 * Short circuit routing redirects to force 643 * immediate change in the kernel's routing 644 * tables. The message is also handed to anyone 645 * listening on a raw socket (e.g. the routing 646 * daemon for use in updating its tables). 647 */ 648 icmpgw.sin_addr = ip->ip_src; 649 icmpdst.sin_addr = icp->icmp_gwaddr; 650 #ifdef ICMPPRINTFS 651 if (icmpprintfs) { 652 char buf[4 * sizeof "123"]; 653 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 654 655 printf("redirect dst %s to %s\n", 656 buf, inet_ntoa(icp->icmp_gwaddr)); 657 } 658 #endif 659 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 660 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 661 in_rtredirect((struct sockaddr *)&icmpsrc, 662 (struct sockaddr *)&icmpdst, 663 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 664 (struct sockaddr *)&icmpgw, fibnum); 665 } 666 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 667 break; 668 669 /* 670 * No kernel processing for the following; 671 * just fall through to send to raw listener. 672 */ 673 case ICMP_ECHOREPLY: 674 case ICMP_ROUTERADVERT: 675 case ICMP_ROUTERSOLICIT: 676 case ICMP_TSTAMPREPLY: 677 case ICMP_IREQREPLY: 678 case ICMP_MASKREPLY: 679 case ICMP_SOURCEQUENCH: 680 default: 681 break; 682 } 683 684 raw: 685 *mp = m; 686 rip_input(mp, offp, proto); 687 return (IPPROTO_DONE); 688 689 freeit: 690 m_freem(m); 691 return (IPPROTO_DONE); 692 } 693 694 /* 695 * Reflect the ip packet back to the source 696 */ 697 static void 698 icmp_reflect(struct mbuf *m) 699 { 700 struct rm_priotracker in_ifa_tracker; 701 struct ip *ip = mtod(m, struct ip *); 702 struct ifaddr *ifa; 703 struct ifnet *ifp; 704 struct in_ifaddr *ia; 705 struct in_addr t; 706 struct nhop4_extended nh_ext; 707 struct mbuf *opts = NULL; 708 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 709 710 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 711 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 712 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 713 m_freem(m); /* Bad return address */ 714 ICMPSTAT_INC(icps_badaddr); 715 goto done; /* Ip_output() will check for broadcast */ 716 } 717 718 t = ip->ip_dst; 719 ip->ip_dst = ip->ip_src; 720 721 /* 722 * Source selection for ICMP replies: 723 * 724 * If the incoming packet was addressed directly to one of our 725 * own addresses, use dst as the src for the reply. 726 */ 727 IN_IFADDR_RLOCK(&in_ifa_tracker); 728 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 729 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 730 t = IA_SIN(ia)->sin_addr; 731 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 732 goto match; 733 } 734 } 735 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 736 737 /* 738 * If the incoming packet was addressed to one of our broadcast 739 * addresses, use the first non-broadcast address which corresponds 740 * to the incoming interface. 741 */ 742 ifp = m->m_pkthdr.rcvif; 743 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 744 IF_ADDR_RLOCK(ifp); 745 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 746 if (ifa->ifa_addr->sa_family != AF_INET) 747 continue; 748 ia = ifatoia(ifa); 749 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 750 t.s_addr) { 751 t = IA_SIN(ia)->sin_addr; 752 IF_ADDR_RUNLOCK(ifp); 753 goto match; 754 } 755 } 756 IF_ADDR_RUNLOCK(ifp); 757 } 758 /* 759 * If the packet was transiting through us, use the address of 760 * the interface the packet came through in. If that interface 761 * doesn't have a suitable IP address, the normal selection 762 * criteria apply. 763 */ 764 if (V_icmp_rfi && ifp != NULL) { 765 IF_ADDR_RLOCK(ifp); 766 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 767 if (ifa->ifa_addr->sa_family != AF_INET) 768 continue; 769 ia = ifatoia(ifa); 770 t = IA_SIN(ia)->sin_addr; 771 IF_ADDR_RUNLOCK(ifp); 772 goto match; 773 } 774 IF_ADDR_RUNLOCK(ifp); 775 } 776 /* 777 * If the incoming packet was not addressed directly to us, use 778 * designated interface for icmp replies specified by sysctl 779 * net.inet.icmp.reply_src (default not set). Otherwise continue 780 * with normal source selection. 781 */ 782 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 783 IF_ADDR_RLOCK(ifp); 784 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 785 if (ifa->ifa_addr->sa_family != AF_INET) 786 continue; 787 ia = ifatoia(ifa); 788 t = IA_SIN(ia)->sin_addr; 789 IF_ADDR_RUNLOCK(ifp); 790 goto match; 791 } 792 IF_ADDR_RUNLOCK(ifp); 793 } 794 /* 795 * If the packet was transiting through us, use the address of 796 * the interface that is the closest to the packet source. 797 * When we don't have a route back to the packet source, stop here 798 * and drop the packet. 799 */ 800 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 801 m_freem(m); 802 ICMPSTAT_INC(icps_noroute); 803 goto done; 804 } 805 t = nh_ext.nh_src; 806 match: 807 #ifdef MAC 808 mac_netinet_icmp_replyinplace(m); 809 #endif 810 ip->ip_src = t; 811 ip->ip_ttl = V_ip_defttl; 812 813 if (optlen > 0) { 814 register u_char *cp; 815 int opt, cnt; 816 u_int len; 817 818 /* 819 * Retrieve any source routing from the incoming packet; 820 * add on any record-route or timestamp options. 821 */ 822 cp = (u_char *) (ip + 1); 823 if ((opts = ip_srcroute(m)) == NULL && 824 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 825 opts->m_len = sizeof(struct in_addr); 826 mtod(opts, struct in_addr *)->s_addr = 0; 827 } 828 if (opts) { 829 #ifdef ICMPPRINTFS 830 if (icmpprintfs) 831 printf("icmp_reflect optlen %d rt %d => ", 832 optlen, opts->m_len); 833 #endif 834 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 835 opt = cp[IPOPT_OPTVAL]; 836 if (opt == IPOPT_EOL) 837 break; 838 if (opt == IPOPT_NOP) 839 len = 1; 840 else { 841 if (cnt < IPOPT_OLEN + sizeof(*cp)) 842 break; 843 len = cp[IPOPT_OLEN]; 844 if (len < IPOPT_OLEN + sizeof(*cp) || 845 len > cnt) 846 break; 847 } 848 /* 849 * Should check for overflow, but it "can't happen" 850 */ 851 if (opt == IPOPT_RR || opt == IPOPT_TS || 852 opt == IPOPT_SECURITY) { 853 bcopy((caddr_t)cp, 854 mtod(opts, caddr_t) + opts->m_len, len); 855 opts->m_len += len; 856 } 857 } 858 /* Terminate & pad, if necessary */ 859 cnt = opts->m_len % 4; 860 if (cnt) { 861 for (; cnt < 4; cnt++) { 862 *(mtod(opts, caddr_t) + opts->m_len) = 863 IPOPT_EOL; 864 opts->m_len++; 865 } 866 } 867 #ifdef ICMPPRINTFS 868 if (icmpprintfs) 869 printf("%d\n", opts->m_len); 870 #endif 871 } 872 ip_stripoptions(m); 873 } 874 m_tag_delete_nonpersistent(m); 875 m->m_flags &= ~(M_BCAST|M_MCAST); 876 icmp_send(m, opts); 877 done: 878 if (opts) 879 (void)m_free(opts); 880 } 881 882 /* 883 * Send an icmp packet back to the ip level, 884 * after supplying a checksum. 885 */ 886 static void 887 icmp_send(struct mbuf *m, struct mbuf *opts) 888 { 889 register struct ip *ip = mtod(m, struct ip *); 890 register int hlen; 891 register struct icmp *icp; 892 893 hlen = ip->ip_hl << 2; 894 m->m_data += hlen; 895 m->m_len -= hlen; 896 icp = mtod(m, struct icmp *); 897 icp->icmp_cksum = 0; 898 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 899 m->m_data -= hlen; 900 m->m_len += hlen; 901 m->m_pkthdr.rcvif = (struct ifnet *)0; 902 #ifdef ICMPPRINTFS 903 if (icmpprintfs) { 904 char buf[4 * sizeof "123"]; 905 strcpy(buf, inet_ntoa(ip->ip_dst)); 906 printf("icmp_send dst %s src %s\n", 907 buf, inet_ntoa(ip->ip_src)); 908 } 909 #endif 910 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 911 } 912 913 /* 914 * Return milliseconds since 00:00 UTC in network format. 915 */ 916 uint32_t 917 iptime(void) 918 { 919 struct timeval atv; 920 u_long t; 921 922 getmicrotime(&atv); 923 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 924 return (htonl(t)); 925 } 926 927 /* 928 * Return the next larger or smaller MTU plateau (table from RFC 1191) 929 * given current value MTU. If DIR is less than zero, a larger plateau 930 * is returned; otherwise, a smaller value is returned. 931 */ 932 int 933 ip_next_mtu(int mtu, int dir) 934 { 935 static int mtutab[] = { 936 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 937 296, 68, 0 938 }; 939 int i, size; 940 941 size = (sizeof mtutab) / (sizeof mtutab[0]); 942 if (dir >= 0) { 943 for (i = 0; i < size; i++) 944 if (mtu > mtutab[i]) 945 return mtutab[i]; 946 } else { 947 for (i = size - 1; i >= 0; i--) 948 if (mtu < mtutab[i]) 949 return mtutab[i]; 950 if (mtu == mtutab[0]) 951 return mtutab[0]; 952 } 953 return 0; 954 } 955 #endif /* INET */ 956 957 958 /* 959 * badport_bandlim() - check for ICMP bandwidth limit 960 * 961 * Return 0 if it is ok to send an ICMP error response, -1 if we have 962 * hit our bandwidth limit and it is not ok. 963 * 964 * If icmplim is <= 0, the feature is disabled and 0 is returned. 965 * 966 * For now we separate the TCP and UDP subsystems w/ different 'which' 967 * values. We may eventually remove this separation (and simplify the 968 * code further). 969 * 970 * Note that the printing of the error message is delayed so we can 971 * properly print the icmp error rate that the system was trying to do 972 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 973 * the 'final' error, but it doesn't make sense to solve the printing 974 * delay with more complex code. 975 */ 976 struct icmp_rate { 977 const char *descr; 978 struct counter_rate cr; 979 }; 980 static VNET_DEFINE(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { 981 { "icmp unreach response" }, 982 { "icmp ping response" }, 983 { "icmp tstamp response" }, 984 { "closed port RST response" }, 985 { "open port RST response" }, 986 { "icmp6 unreach response" }, 987 { "sctp ootb response" } 988 }; 989 #define V_icmp_rates VNET(icmp_rates) 990 991 static void 992 icmp_bandlimit_init(void) 993 { 994 995 for (int i = 0; i < BANDLIM_MAX; i++) { 996 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); 997 V_icmp_rates[i].cr.cr_ticks = ticks; 998 } 999 } 1000 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, 1001 icmp_bandlimit_init, NULL); 1002 1003 static void 1004 icmp_bandlimit_uninit(void) 1005 { 1006 1007 for (int i = 0; i < BANDLIM_MAX; i++) 1008 counter_u64_free(V_icmp_rates[i].cr.cr_rate); 1009 } 1010 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1011 icmp_bandlimit_uninit, NULL); 1012 1013 int 1014 badport_bandlim(int which) 1015 { 1016 int64_t pps; 1017 1018 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) 1019 return (0); 1020 1021 KASSERT(which >= 0 && which < BANDLIM_MAX, 1022 ("%s: which %d", __func__, which)); 1023 1024 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim); 1025 if (pps == -1) 1026 return (-1); 1027 if (pps > 0 && V_icmplim_output) 1028 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", 1029 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim); 1030 return (0); 1031 } 1032