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 #include "opt_ipsec.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/mbuf.h> 41 #include <sys/protosw.h> 42 #include <sys/socket.h> 43 #include <sys/time.h> 44 #include <sys/kernel.h> 45 #include <sys/sysctl.h> 46 #include <sys/syslog.h> 47 48 #include <net/if.h> 49 #include <net/if_types.h> 50 #include <net/route.h> 51 #include <net/vnet.h> 52 53 #include <netinet/in.h> 54 #include <netinet/in_pcb.h> 55 #include <netinet/in_systm.h> 56 #include <netinet/in_var.h> 57 #include <netinet/ip.h> 58 #include <netinet/ip_icmp.h> 59 #include <netinet/ip_var.h> 60 #include <netinet/ip_options.h> 61 #include <netinet/tcp.h> 62 #include <netinet/tcp_var.h> 63 #include <netinet/tcpip.h> 64 #include <netinet/icmp_var.h> 65 66 #ifdef INET 67 #ifdef IPSEC 68 #include <netipsec/ipsec.h> 69 #include <netipsec/key.h> 70 #endif 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_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, 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_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 91 &VNET_NAME(icmplim_output), 0, 92 "Enable rate limiting of ICMP responses"); 93 94 #ifdef INET 95 VNET_DEFINE(struct icmpstat, icmpstat); 96 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 97 &VNET_NAME(icmpstat), icmpstat, ""); 98 99 static VNET_DEFINE(int, icmpmaskrepl) = 0; 100 #define V_icmpmaskrepl VNET(icmpmaskrepl) 101 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 102 &VNET_NAME(icmpmaskrepl), 0, 103 "Reply to ICMP Address Mask Request packets."); 104 105 static VNET_DEFINE(u_int, icmpmaskfake) = 0; 106 #define V_icmpmaskfake VNET(icmpmaskfake) 107 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 108 &VNET_NAME(icmpmaskfake), 0, 109 "Fake reply to ICMP Address Mask Request packets."); 110 111 VNET_DEFINE(int, drop_redirect) = 0; 112 113 static VNET_DEFINE(int, log_redirect) = 0; 114 #define V_log_redirect VNET(log_redirect) 115 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 116 &VNET_NAME(log_redirect), 0, 117 "Log ICMP redirects to the console"); 118 119 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 120 #define V_reply_src VNET(reply_src) 121 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 122 &VNET_NAME(reply_src), IFNAMSIZ, 123 "icmp reply source for non-local packets."); 124 125 static VNET_DEFINE(int, icmp_rfi) = 0; 126 #define V_icmp_rfi VNET(icmp_rfi) 127 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 128 &VNET_NAME(icmp_rfi), 0, 129 "ICMP reply from incoming interface for non-local packets"); 130 131 static VNET_DEFINE(int, icmp_quotelen) = 8; 132 #define V_icmp_quotelen VNET(icmp_quotelen) 133 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 134 &VNET_NAME(icmp_quotelen), 0, 135 "Number of bytes from original packet to quote in ICMP reply"); 136 137 /* 138 * ICMP broadcast echo sysctl 139 */ 140 static VNET_DEFINE(int, icmpbmcastecho) = 0; 141 #define V_icmpbmcastecho VNET(icmpbmcastecho) 142 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 143 &VNET_NAME(icmpbmcastecho), 0, 144 ""); 145 146 147 #ifdef ICMPPRINTFS 148 int icmpprintfs = 0; 149 #endif 150 151 static void icmp_reflect(struct mbuf *); 152 static void icmp_send(struct mbuf *, struct mbuf *); 153 154 extern struct protosw inetsw[]; 155 156 static int 157 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS) 158 { 159 int error, new; 160 int i; 161 struct radix_node_head *rnh; 162 163 new = V_drop_redirect; 164 error = sysctl_handle_int(oidp, &new, 0, req); 165 if (error == 0 && req->newptr) { 166 new = (new != 0) ? 1 : 0; 167 168 if (new == V_drop_redirect) 169 return (0); 170 171 for (i = 0; i < rt_numfibs; i++) { 172 if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL) 173 continue; 174 RADIX_NODE_HEAD_LOCK(rnh); 175 in_setmatchfunc(rnh, new); 176 RADIX_NODE_HEAD_UNLOCK(rnh); 177 } 178 179 V_drop_redirect = new; 180 } 181 182 return (error); 183 } 184 185 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect, 186 CTLTYPE_INT|CTLFLAG_RW, 0, 0, 187 sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects"); 188 189 /* 190 * Kernel module interface for updating icmpstat. The argument is an index 191 * into icmpstat treated as an array of u_long. While this encodes the 192 * general layout of icmpstat into the caller, it doesn't encode its 193 * location, so that future changes to add, for example, per-CPU stats 194 * support won't cause binary compatibility problems for kernel modules. 195 */ 196 void 197 kmod_icmpstat_inc(int statnum) 198 { 199 200 (*((u_long *)&V_icmpstat + statnum))++; 201 } 202 203 /* 204 * Generate an error packet of type error 205 * in response to bad packet ip. 206 */ 207 void 208 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 209 { 210 register struct ip *oip = mtod(n, struct ip *), *nip; 211 register unsigned oiphlen = oip->ip_hl << 2; 212 register struct icmp *icp; 213 register struct mbuf *m; 214 unsigned icmplen, icmpelen, nlen; 215 216 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 217 #ifdef ICMPPRINTFS 218 if (icmpprintfs) 219 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 220 #endif 221 if (type != ICMP_REDIRECT) 222 ICMPSTAT_INC(icps_error); 223 /* 224 * Don't send error: 225 * if the original packet was encrypted. 226 * if not the first fragment of message. 227 * in response to a multicast or broadcast packet. 228 * if the old packet protocol was an ICMP error message. 229 */ 230 if (n->m_flags & M_DECRYPTED) 231 goto freeit; 232 if (oip->ip_off & ~(IP_MF|IP_DF)) 233 goto freeit; 234 if (n->m_flags & (M_BCAST|M_MCAST)) 235 goto freeit; 236 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 237 n->m_len >= oiphlen + ICMP_MINLEN && 238 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 239 ICMPSTAT_INC(icps_oldicmp); 240 goto freeit; 241 } 242 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 243 if (oiphlen + 8 > n->m_len) 244 goto freeit; 245 /* 246 * Calculate length to quote from original packet and 247 * prevent the ICMP mbuf from overflowing. 248 * Unfortunatly this is non-trivial since ip_forward() 249 * sends us truncated packets. 250 */ 251 nlen = m_length(n, NULL); 252 if (oip->ip_p == IPPROTO_TCP) { 253 struct tcphdr *th; 254 int tcphlen; 255 256 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 257 n->m_next == NULL) 258 goto stdreply; 259 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 260 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 261 goto freeit; 262 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 263 tcphlen = th->th_off << 2; 264 if (tcphlen < sizeof(struct tcphdr)) 265 goto freeit; 266 if (oip->ip_len < oiphlen + tcphlen) 267 goto freeit; 268 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 269 goto stdreply; 270 if (n->m_len < oiphlen + tcphlen && 271 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 272 goto freeit; 273 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 274 } else 275 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 276 277 icmplen = min(oiphlen + icmpelen, nlen); 278 if (icmplen < sizeof(struct ip)) 279 goto freeit; 280 281 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 282 m = m_gethdr(M_DONTWAIT, MT_DATA); 283 else 284 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 285 if (m == NULL) 286 goto freeit; 287 #ifdef MAC 288 mac_netinet_icmp_reply(n, m); 289 #endif 290 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 291 m_align(m, ICMP_MINLEN + icmplen); 292 m->m_len = ICMP_MINLEN + icmplen; 293 294 /* XXX MRT make the outgoing packet use the same FIB 295 * that was associated with the incoming packet 296 */ 297 M_SETFIB(m, M_GETFIB(n)); 298 icp = mtod(m, struct icmp *); 299 ICMPSTAT_INC(icps_outhist[type]); 300 icp->icmp_type = type; 301 if (type == ICMP_REDIRECT) 302 icp->icmp_gwaddr.s_addr = dest; 303 else { 304 icp->icmp_void = 0; 305 /* 306 * The following assignments assume an overlay with the 307 * just zeroed icmp_void field. 308 */ 309 if (type == ICMP_PARAMPROB) { 310 icp->icmp_pptr = code; 311 code = 0; 312 } else if (type == ICMP_UNREACH && 313 code == ICMP_UNREACH_NEEDFRAG && mtu) { 314 icp->icmp_nextmtu = htons(mtu); 315 } 316 } 317 icp->icmp_code = code; 318 319 /* 320 * Copy the quotation into ICMP message and 321 * convert quoted IP header back to network representation. 322 */ 323 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 324 nip = &icp->icmp_ip; 325 nip->ip_len = htons(nip->ip_len); 326 nip->ip_off = htons(nip->ip_off); 327 328 /* 329 * Set up ICMP message mbuf and copy old IP header (without options 330 * in front of ICMP message. 331 * If the original mbuf was meant to bypass the firewall, the error 332 * reply should bypass as well. 333 */ 334 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 335 m->m_data -= sizeof(struct ip); 336 m->m_len += sizeof(struct ip); 337 m->m_pkthdr.len = m->m_len; 338 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 339 nip = mtod(m, struct ip *); 340 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 341 nip->ip_len = m->m_len; 342 nip->ip_v = IPVERSION; 343 nip->ip_hl = 5; 344 nip->ip_p = IPPROTO_ICMP; 345 nip->ip_tos = 0; 346 nip->ip_off = 0; 347 icmp_reflect(m); 348 349 freeit: 350 m_freem(n); 351 } 352 353 /* 354 * Process a received ICMP message. 355 */ 356 void 357 icmp_input(struct mbuf *m, int off) 358 { 359 struct icmp *icp; 360 struct in_ifaddr *ia; 361 struct ip *ip = mtod(m, struct ip *); 362 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 363 int hlen = off; 364 int icmplen = ip->ip_len; 365 int i, code; 366 void (*ctlfunc)(int, struct sockaddr *, void *); 367 int fibnum; 368 369 /* 370 * Locate icmp structure in mbuf, and check 371 * that not corrupted and of at least minimum length. 372 */ 373 #ifdef ICMPPRINTFS 374 if (icmpprintfs) { 375 char buf[4 * sizeof "123"]; 376 strcpy(buf, inet_ntoa(ip->ip_src)); 377 printf("icmp_input from %s to %s, len %d\n", 378 buf, inet_ntoa(ip->ip_dst), icmplen); 379 } 380 #endif 381 if (icmplen < ICMP_MINLEN) { 382 ICMPSTAT_INC(icps_tooshort); 383 goto freeit; 384 } 385 i = hlen + min(icmplen, ICMP_ADVLENMIN); 386 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 387 ICMPSTAT_INC(icps_tooshort); 388 return; 389 } 390 ip = mtod(m, struct ip *); 391 m->m_len -= hlen; 392 m->m_data += hlen; 393 icp = mtod(m, struct icmp *); 394 if (in_cksum(m, icmplen)) { 395 ICMPSTAT_INC(icps_checksum); 396 goto freeit; 397 } 398 m->m_len += hlen; 399 m->m_data -= hlen; 400 401 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 402 /* 403 * Deliver very specific ICMP type only. 404 */ 405 switch (icp->icmp_type) { 406 case ICMP_UNREACH: 407 case ICMP_TIMXCEED: 408 break; 409 default: 410 goto freeit; 411 } 412 } 413 414 #ifdef ICMPPRINTFS 415 if (icmpprintfs) 416 printf("icmp_input, type %d code %d\n", icp->icmp_type, 417 icp->icmp_code); 418 #endif 419 420 /* 421 * Message type specific processing. 422 */ 423 if (icp->icmp_type > ICMP_MAXTYPE) 424 goto raw; 425 426 /* Initialize */ 427 bzero(&icmpsrc, sizeof(icmpsrc)); 428 icmpsrc.sin_len = sizeof(struct sockaddr_in); 429 icmpsrc.sin_family = AF_INET; 430 bzero(&icmpdst, sizeof(icmpdst)); 431 icmpdst.sin_len = sizeof(struct sockaddr_in); 432 icmpdst.sin_family = AF_INET; 433 bzero(&icmpgw, sizeof(icmpgw)); 434 icmpgw.sin_len = sizeof(struct sockaddr_in); 435 icmpgw.sin_family = AF_INET; 436 437 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 438 code = icp->icmp_code; 439 switch (icp->icmp_type) { 440 441 case ICMP_UNREACH: 442 switch (code) { 443 case ICMP_UNREACH_NET: 444 case ICMP_UNREACH_HOST: 445 case ICMP_UNREACH_SRCFAIL: 446 case ICMP_UNREACH_NET_UNKNOWN: 447 case ICMP_UNREACH_HOST_UNKNOWN: 448 case ICMP_UNREACH_ISOLATED: 449 case ICMP_UNREACH_TOSNET: 450 case ICMP_UNREACH_TOSHOST: 451 case ICMP_UNREACH_HOST_PRECEDENCE: 452 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 453 code = PRC_UNREACH_NET; 454 break; 455 456 case ICMP_UNREACH_NEEDFRAG: 457 code = PRC_MSGSIZE; 458 break; 459 460 /* 461 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 462 * Treat subcodes 2,3 as immediate RST 463 */ 464 case ICMP_UNREACH_PROTOCOL: 465 case ICMP_UNREACH_PORT: 466 code = PRC_UNREACH_PORT; 467 break; 468 469 case ICMP_UNREACH_NET_PROHIB: 470 case ICMP_UNREACH_HOST_PROHIB: 471 case ICMP_UNREACH_FILTER_PROHIB: 472 code = PRC_UNREACH_ADMIN_PROHIB; 473 break; 474 475 default: 476 goto badcode; 477 } 478 goto deliver; 479 480 case ICMP_TIMXCEED: 481 if (code > 1) 482 goto badcode; 483 code += PRC_TIMXCEED_INTRANS; 484 goto deliver; 485 486 case ICMP_PARAMPROB: 487 if (code > 1) 488 goto badcode; 489 code = PRC_PARAMPROB; 490 goto deliver; 491 492 case ICMP_SOURCEQUENCH: 493 if (code) 494 goto badcode; 495 code = PRC_QUENCH; 496 deliver: 497 /* 498 * Problem with datagram; advise higher level routines. 499 */ 500 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 501 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 502 ICMPSTAT_INC(icps_badlen); 503 goto freeit; 504 } 505 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 506 /* Discard ICMP's in response to multicast packets */ 507 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 508 goto badcode; 509 #ifdef ICMPPRINTFS 510 if (icmpprintfs) 511 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 512 #endif 513 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 514 /* 515 * XXX if the packet contains [IPv4 AH TCP], we can't make a 516 * notification to TCP layer. 517 */ 518 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 519 if (ctlfunc) 520 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 521 (void *)&icp->icmp_ip); 522 break; 523 524 badcode: 525 ICMPSTAT_INC(icps_badcode); 526 break; 527 528 case ICMP_ECHO: 529 if (!V_icmpbmcastecho 530 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 531 ICMPSTAT_INC(icps_bmcastecho); 532 break; 533 } 534 icp->icmp_type = ICMP_ECHOREPLY; 535 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 536 goto freeit; 537 else 538 goto reflect; 539 540 case ICMP_TSTAMP: 541 if (!V_icmpbmcastecho 542 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 543 ICMPSTAT_INC(icps_bmcasttstamp); 544 break; 545 } 546 if (icmplen < ICMP_TSLEN) { 547 ICMPSTAT_INC(icps_badlen); 548 break; 549 } 550 icp->icmp_type = ICMP_TSTAMPREPLY; 551 icp->icmp_rtime = iptime(); 552 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 553 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 554 goto freeit; 555 else 556 goto reflect; 557 558 case ICMP_MASKREQ: 559 if (V_icmpmaskrepl == 0) 560 break; 561 /* 562 * We are not able to respond with all ones broadcast 563 * unless we receive it over a point-to-point interface. 564 */ 565 if (icmplen < ICMP_MASKLEN) 566 break; 567 switch (ip->ip_dst.s_addr) { 568 569 case INADDR_BROADCAST: 570 case INADDR_ANY: 571 icmpdst.sin_addr = ip->ip_src; 572 break; 573 574 default: 575 icmpdst.sin_addr = ip->ip_dst; 576 } 577 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 578 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 579 if (ia == NULL) 580 break; 581 if (ia->ia_ifp == NULL) { 582 ifa_free(&ia->ia_ifa); 583 break; 584 } 585 icp->icmp_type = ICMP_MASKREPLY; 586 if (V_icmpmaskfake == 0) 587 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 588 else 589 icp->icmp_mask = V_icmpmaskfake; 590 if (ip->ip_src.s_addr == 0) { 591 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 592 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 593 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 594 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 595 } 596 ifa_free(&ia->ia_ifa); 597 reflect: 598 ip->ip_len += hlen; /* since ip_input deducts this */ 599 ICMPSTAT_INC(icps_reflect); 600 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 601 icmp_reflect(m); 602 return; 603 604 case ICMP_REDIRECT: 605 if (V_log_redirect) { 606 u_long src, dst, gw; 607 608 src = ntohl(ip->ip_src.s_addr); 609 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 610 gw = ntohl(icp->icmp_gwaddr.s_addr); 611 printf("icmp redirect from %d.%d.%d.%d: " 612 "%d.%d.%d.%d => %d.%d.%d.%d\n", 613 (int)(src >> 24), (int)((src >> 16) & 0xff), 614 (int)((src >> 8) & 0xff), (int)(src & 0xff), 615 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 616 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 617 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 618 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 619 } 620 /* 621 * RFC1812 says we must ignore ICMP redirects if we 622 * are acting as router. 623 */ 624 if (V_drop_redirect || V_ipforwarding) 625 break; 626 if (code > 3) 627 goto badcode; 628 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 629 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 630 ICMPSTAT_INC(icps_badlen); 631 break; 632 } 633 /* 634 * Short circuit routing redirects to force 635 * immediate change in the kernel's routing 636 * tables. The message is also handed to anyone 637 * listening on a raw socket (e.g. the routing 638 * daemon for use in updating its tables). 639 */ 640 icmpgw.sin_addr = ip->ip_src; 641 icmpdst.sin_addr = icp->icmp_gwaddr; 642 #ifdef ICMPPRINTFS 643 if (icmpprintfs) { 644 char buf[4 * sizeof "123"]; 645 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 646 647 printf("redirect dst %s to %s\n", 648 buf, inet_ntoa(icp->icmp_gwaddr)); 649 } 650 #endif 651 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 652 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 653 in_rtredirect((struct sockaddr *)&icmpsrc, 654 (struct sockaddr *)&icmpdst, 655 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 656 (struct sockaddr *)&icmpgw, fibnum); 657 } 658 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 659 #ifdef IPSEC 660 key_sa_routechange((struct sockaddr *)&icmpsrc); 661 #endif 662 break; 663 664 /* 665 * No kernel processing for the following; 666 * just fall through to send to raw listener. 667 */ 668 case ICMP_ECHOREPLY: 669 case ICMP_ROUTERADVERT: 670 case ICMP_ROUTERSOLICIT: 671 case ICMP_TSTAMPREPLY: 672 case ICMP_IREQREPLY: 673 case ICMP_MASKREPLY: 674 default: 675 break; 676 } 677 678 raw: 679 rip_input(m, off); 680 return; 681 682 freeit: 683 m_freem(m); 684 } 685 686 /* 687 * Reflect the ip packet back to the source 688 */ 689 static void 690 icmp_reflect(struct mbuf *m) 691 { 692 struct ip *ip = mtod(m, struct ip *); 693 struct ifaddr *ifa; 694 struct ifnet *ifp; 695 struct in_ifaddr *ia; 696 struct in_addr t; 697 struct mbuf *opts = 0; 698 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 699 700 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 701 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 702 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 703 m_freem(m); /* Bad return address */ 704 ICMPSTAT_INC(icps_badaddr); 705 goto done; /* Ip_output() will check for broadcast */ 706 } 707 708 m_addr_changed(m); 709 710 t = ip->ip_dst; 711 ip->ip_dst = ip->ip_src; 712 713 /* 714 * Source selection for ICMP replies: 715 * 716 * If the incoming packet was addressed directly to one of our 717 * own addresses, use dst as the src for the reply. 718 */ 719 IN_IFADDR_RLOCK(); 720 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 721 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 722 t = IA_SIN(ia)->sin_addr; 723 IN_IFADDR_RUNLOCK(); 724 goto match; 725 } 726 } 727 IN_IFADDR_RUNLOCK(); 728 729 /* 730 * If the incoming packet was addressed to one of our broadcast 731 * addresses, use the first non-broadcast address which corresponds 732 * to the incoming interface. 733 */ 734 ifp = m->m_pkthdr.rcvif; 735 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 736 IF_ADDR_RLOCK(ifp); 737 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 738 if (ifa->ifa_addr->sa_family != AF_INET) 739 continue; 740 ia = ifatoia(ifa); 741 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 742 t.s_addr) { 743 t = IA_SIN(ia)->sin_addr; 744 IF_ADDR_RUNLOCK(ifp); 745 goto match; 746 } 747 } 748 IF_ADDR_RUNLOCK(ifp); 749 } 750 /* 751 * If the packet was transiting through us, use the address of 752 * the interface the packet came through in. If that interface 753 * doesn't have a suitable IP address, the normal selection 754 * criteria apply. 755 */ 756 if (V_icmp_rfi && ifp != NULL) { 757 IF_ADDR_RLOCK(ifp); 758 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 759 if (ifa->ifa_addr->sa_family != AF_INET) 760 continue; 761 ia = ifatoia(ifa); 762 t = IA_SIN(ia)->sin_addr; 763 IF_ADDR_RUNLOCK(ifp); 764 goto match; 765 } 766 IF_ADDR_RUNLOCK(ifp); 767 } 768 /* 769 * If the incoming packet was not addressed directly to us, use 770 * designated interface for icmp replies specified by sysctl 771 * net.inet.icmp.reply_src (default not set). Otherwise continue 772 * with normal source selection. 773 */ 774 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 775 IF_ADDR_RLOCK(ifp); 776 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 777 if (ifa->ifa_addr->sa_family != AF_INET) 778 continue; 779 ia = ifatoia(ifa); 780 t = IA_SIN(ia)->sin_addr; 781 IF_ADDR_RUNLOCK(ifp); 782 goto match; 783 } 784 IF_ADDR_RUNLOCK(ifp); 785 } 786 /* 787 * If the packet was transiting through us, use the address of 788 * the interface that is the closest to the packet source. 789 * When we don't have a route back to the packet source, stop here 790 * and drop the packet. 791 */ 792 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 793 if (ia == NULL) { 794 m_freem(m); 795 ICMPSTAT_INC(icps_noroute); 796 goto done; 797 } 798 t = IA_SIN(ia)->sin_addr; 799 ifa_free(&ia->ia_ifa); 800 match: 801 #ifdef MAC 802 mac_netinet_icmp_replyinplace(m); 803 #endif 804 ip->ip_src = t; 805 ip->ip_ttl = V_ip_defttl; 806 807 if (optlen > 0) { 808 register u_char *cp; 809 int opt, cnt; 810 u_int len; 811 812 /* 813 * Retrieve any source routing from the incoming packet; 814 * add on any record-route or timestamp options. 815 */ 816 cp = (u_char *) (ip + 1); 817 if ((opts = ip_srcroute(m)) == 0 && 818 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 819 opts->m_len = sizeof(struct in_addr); 820 mtod(opts, struct in_addr *)->s_addr = 0; 821 } 822 if (opts) { 823 #ifdef ICMPPRINTFS 824 if (icmpprintfs) 825 printf("icmp_reflect optlen %d rt %d => ", 826 optlen, opts->m_len); 827 #endif 828 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 829 opt = cp[IPOPT_OPTVAL]; 830 if (opt == IPOPT_EOL) 831 break; 832 if (opt == IPOPT_NOP) 833 len = 1; 834 else { 835 if (cnt < IPOPT_OLEN + sizeof(*cp)) 836 break; 837 len = cp[IPOPT_OLEN]; 838 if (len < IPOPT_OLEN + sizeof(*cp) || 839 len > cnt) 840 break; 841 } 842 /* 843 * Should check for overflow, but it "can't happen" 844 */ 845 if (opt == IPOPT_RR || opt == IPOPT_TS || 846 opt == IPOPT_SECURITY) { 847 bcopy((caddr_t)cp, 848 mtod(opts, caddr_t) + opts->m_len, len); 849 opts->m_len += len; 850 } 851 } 852 /* Terminate & pad, if necessary */ 853 cnt = opts->m_len % 4; 854 if (cnt) { 855 for (; cnt < 4; cnt++) { 856 *(mtod(opts, caddr_t) + opts->m_len) = 857 IPOPT_EOL; 858 opts->m_len++; 859 } 860 } 861 #ifdef ICMPPRINTFS 862 if (icmpprintfs) 863 printf("%d\n", opts->m_len); 864 #endif 865 } 866 /* 867 * Now strip out original options by copying rest of first 868 * mbuf's data back, and adjust the IP length. 869 */ 870 ip->ip_len -= optlen; 871 ip->ip_v = IPVERSION; 872 ip->ip_hl = 5; 873 m->m_len -= optlen; 874 if (m->m_flags & M_PKTHDR) 875 m->m_pkthdr.len -= optlen; 876 optlen += sizeof(struct ip); 877 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 878 (unsigned)(m->m_len - sizeof(struct ip))); 879 } 880 m_tag_delete_nonpersistent(m); 881 m->m_flags &= ~(M_BCAST|M_MCAST); 882 icmp_send(m, opts); 883 done: 884 if (opts) 885 (void)m_free(opts); 886 } 887 888 /* 889 * Send an icmp packet back to the ip level, 890 * after supplying a checksum. 891 */ 892 static void 893 icmp_send(struct mbuf *m, struct mbuf *opts) 894 { 895 register struct ip *ip = mtod(m, struct ip *); 896 register int hlen; 897 register struct icmp *icp; 898 899 hlen = ip->ip_hl << 2; 900 m->m_data += hlen; 901 m->m_len -= hlen; 902 icp = mtod(m, struct icmp *); 903 icp->icmp_cksum = 0; 904 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 905 m->m_data -= hlen; 906 m->m_len += hlen; 907 m->m_pkthdr.rcvif = (struct ifnet *)0; 908 #ifdef ICMPPRINTFS 909 if (icmpprintfs) { 910 char buf[4 * sizeof "123"]; 911 strcpy(buf, inet_ntoa(ip->ip_dst)); 912 printf("icmp_send dst %s src %s\n", 913 buf, inet_ntoa(ip->ip_src)); 914 } 915 #endif 916 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 917 } 918 919 /* 920 * Return milliseconds since 00:00 GMT in network format. 921 */ 922 uint32_t 923 iptime(void) 924 { 925 struct timeval atv; 926 u_long t; 927 928 getmicrotime(&atv); 929 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 930 return (htonl(t)); 931 } 932 933 /* 934 * Return the next larger or smaller MTU plateau (table from RFC 1191) 935 * given current value MTU. If DIR is less than zero, a larger plateau 936 * is returned; otherwise, a smaller value is returned. 937 */ 938 int 939 ip_next_mtu(int mtu, int dir) 940 { 941 static int mtutab[] = { 942 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 943 296, 68, 0 944 }; 945 int i, size; 946 947 size = (sizeof mtutab) / (sizeof mtutab[0]); 948 if (dir >= 0) { 949 for (i = 0; i < size; i++) 950 if (mtu > mtutab[i]) 951 return mtutab[i]; 952 } else { 953 for (i = size - 1; i >= 0; i--) 954 if (mtu < mtutab[i]) 955 return mtutab[i]; 956 if (mtu == mtutab[0]) 957 return mtutab[0]; 958 } 959 return 0; 960 } 961 #endif /* INET */ 962 963 964 /* 965 * badport_bandlim() - check for ICMP bandwidth limit 966 * 967 * Return 0 if it is ok to send an ICMP error response, -1 if we have 968 * hit our bandwidth limit and it is not ok. 969 * 970 * If icmplim is <= 0, the feature is disabled and 0 is returned. 971 * 972 * For now we separate the TCP and UDP subsystems w/ different 'which' 973 * values. We may eventually remove this separation (and simplify the 974 * code further). 975 * 976 * Note that the printing of the error message is delayed so we can 977 * properly print the icmp error rate that the system was trying to do 978 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 979 * the 'final' error, but it doesn't make sense to solve the printing 980 * delay with more complex code. 981 */ 982 983 int 984 badport_bandlim(int which) 985 { 986 987 #define N(a) (sizeof (a) / sizeof (a[0])) 988 static struct rate { 989 const char *type; 990 struct timeval lasttime; 991 int curpps; 992 } rates[BANDLIM_MAX+1] = { 993 { "icmp unreach response" }, 994 { "icmp ping response" }, 995 { "icmp tstamp response" }, 996 { "closed port RST response" }, 997 { "open port RST response" }, 998 { "icmp6 unreach response" }, 999 { "sctp ootb response" } 1000 }; 1001 1002 /* 1003 * Return ok status if feature disabled or argument out of range. 1004 */ 1005 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1006 struct rate *r = &rates[which]; 1007 int opps = r->curpps; 1008 1009 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1010 return -1; /* discard packet */ 1011 /* 1012 * If we've dropped below the threshold after having 1013 * rate-limited traffic print the message. This preserves 1014 * the previous behaviour at the expense of added complexity. 1015 */ 1016 if (V_icmplim_output && opps > V_icmplim) 1017 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1018 r->type, opps, V_icmplim); 1019 } 1020 return 0; /* okay to send packet */ 1021 #undef N 1022 }
Cache object: a327faef39da6120219e6d73928c48cc
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