ip_icmp.c revision 283901
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: stable/10/sys/netinet/ip_icmp.c 283901 2015-06-02 03:14:42Z ae $"); 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/sysctl.h> 45#include <sys/syslog.h> 46 47#include <net/if.h> 48#include <net/if_types.h> 49#include <net/route.h> 50#include <net/vnet.h> 51 52#include <netinet/in.h> 53#include <netinet/in_pcb.h> 54#include <netinet/in_systm.h> 55#include <netinet/in_var.h> 56#include <netinet/ip.h> 57#include <netinet/ip_icmp.h> 58#include <netinet/ip_var.h> 59#include <netinet/ip_options.h> 60#include <netinet/tcp.h> 61#include <netinet/tcp_var.h> 62#include <netinet/tcpip.h> 63#include <netinet/icmp_var.h> 64 65#ifdef INET 66 67#include <machine/in_cksum.h> 68 69#include <security/mac/mac_framework.h> 70#endif /* INET */ 71 72/* 73 * ICMP routines: error generation, receive packet processing, and 74 * routines to turnaround packets back to the originator, and 75 * host table maintenance routines. 76 */ 77static VNET_DEFINE(int, icmplim) = 200; 78#define V_icmplim VNET(icmplim) 79SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 80 &VNET_NAME(icmplim), 0, 81 "Maximum number of ICMP responses per second"); 82 83static VNET_DEFINE(int, icmplim_output) = 1; 84#define V_icmplim_output VNET(icmplim_output) 85SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 86 &VNET_NAME(icmplim_output), 0, 87 "Enable logging of ICMP response rate limiting"); 88 89#ifdef INET 90VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 91VNET_PCPUSTAT_SYSINIT(icmpstat); 92SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 93 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 94 95#ifdef VIMAGE 96VNET_PCPUSTAT_SYSUNINIT(icmpstat); 97#endif /* VIMAGE */ 98 99static VNET_DEFINE(int, icmpmaskrepl) = 0; 100#define V_icmpmaskrepl VNET(icmpmaskrepl) 101SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 102 &VNET_NAME(icmpmaskrepl), 0, 103 "Reply to ICMP Address Mask Request packets."); 104 105static VNET_DEFINE(u_int, icmpmaskfake) = 0; 106#define V_icmpmaskfake VNET(icmpmaskfake) 107SYSCTL_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 111VNET_DEFINE(int, drop_redirect) = 0; 112 113static VNET_DEFINE(int, log_redirect) = 0; 114#define V_log_redirect VNET(log_redirect) 115SYSCTL_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 119static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 120#define V_reply_src VNET(reply_src) 121SYSCTL_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 125static VNET_DEFINE(int, icmp_rfi) = 0; 126#define V_icmp_rfi VNET(icmp_rfi) 127SYSCTL_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 131static VNET_DEFINE(int, icmp_quotelen) = 8; 132#define V_icmp_quotelen VNET(icmp_quotelen) 133SYSCTL_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 */ 140static VNET_DEFINE(int, icmpbmcastecho) = 0; 141#define V_icmpbmcastecho VNET(icmpbmcastecho) 142SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 143 &VNET_NAME(icmpbmcastecho), 0, 144 ""); 145 146static VNET_DEFINE(int, icmptstamprepl) = 1; 147#define V_icmptstamprepl VNET(icmptstamprepl) 148SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 149 &VNET_NAME(icmptstamprepl), 0, "Respond to ICMP Timestamp packets"); 150 151#ifdef ICMPPRINTFS 152int icmpprintfs = 0; 153#endif 154 155static void icmp_reflect(struct mbuf *); 156static void icmp_send(struct mbuf *, struct mbuf *); 157 158extern struct protosw inetsw[]; 159 160static int 161sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS) 162{ 163 int error, new; 164 int i; 165 struct radix_node_head *rnh; 166 167 new = V_drop_redirect; 168 error = sysctl_handle_int(oidp, &new, 0, req); 169 if (error == 0 && req->newptr) { 170 new = (new != 0) ? 1 : 0; 171 172 if (new == V_drop_redirect) 173 return (0); 174 175 for (i = 0; i < rt_numfibs; i++) { 176 if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL) 177 continue; 178 RADIX_NODE_HEAD_LOCK(rnh); 179 in_setmatchfunc(rnh, new); 180 RADIX_NODE_HEAD_UNLOCK(rnh); 181 } 182 183 V_drop_redirect = new; 184 } 185 186 return (error); 187} 188 189SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect, 190 CTLTYPE_INT|CTLFLAG_RW, 0, 0, 191 sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects"); 192 193/* 194 * Kernel module interface for updating icmpstat. The argument is an index 195 * into icmpstat treated as an array of u_long. While this encodes the 196 * general layout of icmpstat into the caller, it doesn't encode its 197 * location, so that future changes to add, for example, per-CPU stats 198 * support won't cause binary compatibility problems for kernel modules. 199 */ 200void 201kmod_icmpstat_inc(int statnum) 202{ 203 204 counter_u64_add(VNET(icmpstat)[statnum], 1); 205} 206 207/* 208 * Generate an error packet of type error 209 * in response to bad packet ip. 210 */ 211void 212icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 213{ 214 register struct ip *oip = mtod(n, struct ip *), *nip; 215 register unsigned oiphlen = oip->ip_hl << 2; 216 register struct icmp *icp; 217 register struct mbuf *m; 218 unsigned icmplen, icmpelen, nlen; 219 220 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 221#ifdef ICMPPRINTFS 222 if (icmpprintfs) 223 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 224#endif 225 if (type != ICMP_REDIRECT) 226 ICMPSTAT_INC(icps_error); 227 /* 228 * Don't send error: 229 * if the original packet was encrypted. 230 * if not the first fragment of message. 231 * in response to a multicast or broadcast packet. 232 * if the old packet protocol was an ICMP error message. 233 */ 234 if (n->m_flags & M_DECRYPTED) 235 goto freeit; 236 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 237 goto freeit; 238 if (n->m_flags & (M_BCAST|M_MCAST)) 239 goto freeit; 240 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 241 n->m_len >= oiphlen + ICMP_MINLEN && 242 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 243 ICMPSTAT_INC(icps_oldicmp); 244 goto freeit; 245 } 246 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 247 if (oiphlen + 8 > n->m_len) 248 goto freeit; 249 /* 250 * Calculate length to quote from original packet and 251 * prevent the ICMP mbuf from overflowing. 252 * Unfortunatly this is non-trivial since ip_forward() 253 * sends us truncated packets. 254 */ 255 nlen = m_length(n, NULL); 256 if (oip->ip_p == IPPROTO_TCP) { 257 struct tcphdr *th; 258 int tcphlen; 259 260 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 261 n->m_next == NULL) 262 goto stdreply; 263 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 264 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 265 goto freeit; 266 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 267 tcphlen = th->th_off << 2; 268 if (tcphlen < sizeof(struct tcphdr)) 269 goto freeit; 270 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 271 goto freeit; 272 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 273 goto stdreply; 274 if (n->m_len < oiphlen + tcphlen && 275 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 276 goto freeit; 277 icmpelen = max(tcphlen, min(V_icmp_quotelen, 278 ntohs(oip->ip_len) - oiphlen)); 279 } else 280stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 281 282 icmplen = min(oiphlen + icmpelen, nlen); 283 if (icmplen < sizeof(struct ip)) 284 goto freeit; 285 286 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 287 m = m_gethdr(M_NOWAIT, MT_DATA); 288 else 289 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 290 if (m == NULL) 291 goto freeit; 292#ifdef MAC 293 mac_netinet_icmp_reply(n, m); 294#endif 295 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 296 m_align(m, ICMP_MINLEN + icmplen); 297 m->m_len = ICMP_MINLEN + icmplen; 298 299 /* XXX MRT make the outgoing packet use the same FIB 300 * that was associated with the incoming packet 301 */ 302 M_SETFIB(m, M_GETFIB(n)); 303 icp = mtod(m, struct icmp *); 304 ICMPSTAT_INC(icps_outhist[type]); 305 icp->icmp_type = type; 306 if (type == ICMP_REDIRECT) 307 icp->icmp_gwaddr.s_addr = dest; 308 else { 309 icp->icmp_void = 0; 310 /* 311 * The following assignments assume an overlay with the 312 * just zeroed icmp_void field. 313 */ 314 if (type == ICMP_PARAMPROB) { 315 icp->icmp_pptr = code; 316 code = 0; 317 } else if (type == ICMP_UNREACH && 318 code == ICMP_UNREACH_NEEDFRAG && mtu) { 319 icp->icmp_nextmtu = htons(mtu); 320 } 321 } 322 icp->icmp_code = code; 323 324 /* 325 * Copy the quotation into ICMP message and 326 * convert quoted IP header back to network representation. 327 */ 328 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 329 nip = &icp->icmp_ip; 330 331 /* 332 * Set up ICMP message mbuf and copy old IP header (without options 333 * in front of ICMP message. 334 * If the original mbuf was meant to bypass the firewall, the error 335 * reply should bypass as well. 336 */ 337 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 338 m->m_data -= sizeof(struct ip); 339 m->m_len += sizeof(struct ip); 340 m->m_pkthdr.len = m->m_len; 341 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 342 nip = mtod(m, struct ip *); 343 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 344 nip->ip_len = htons(m->m_len); 345 nip->ip_v = IPVERSION; 346 nip->ip_hl = 5; 347 nip->ip_p = IPPROTO_ICMP; 348 nip->ip_tos = 0; 349 nip->ip_off = 0; 350 icmp_reflect(m); 351 352freeit: 353 m_freem(n); 354} 355 356/* 357 * Process a received ICMP message. 358 */ 359void 360icmp_input(struct mbuf *m, int off) 361{ 362 struct icmp *icp; 363 struct in_ifaddr *ia; 364 struct ip *ip = mtod(m, struct ip *); 365 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 366 int hlen = off; 367 int icmplen = ntohs(ip->ip_len) - off; 368 int i, code; 369 void (*ctlfunc)(int, struct sockaddr *, void *); 370 int fibnum; 371 372 /* 373 * Locate icmp structure in mbuf, and check 374 * that not corrupted and of at least minimum length. 375 */ 376#ifdef ICMPPRINTFS 377 if (icmpprintfs) { 378 char buf[4 * sizeof "123"]; 379 strcpy(buf, inet_ntoa(ip->ip_src)); 380 printf("icmp_input from %s to %s, len %d\n", 381 buf, inet_ntoa(ip->ip_dst), icmplen); 382 } 383#endif 384 if (icmplen < ICMP_MINLEN) { 385 ICMPSTAT_INC(icps_tooshort); 386 goto freeit; 387 } 388 i = hlen + min(icmplen, ICMP_ADVLENMIN); 389 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 390 ICMPSTAT_INC(icps_tooshort); 391 return; 392 } 393 ip = mtod(m, struct ip *); 394 m->m_len -= hlen; 395 m->m_data += hlen; 396 icp = mtod(m, struct icmp *); 397 if (in_cksum(m, icmplen)) { 398 ICMPSTAT_INC(icps_checksum); 399 goto freeit; 400 } 401 m->m_len += hlen; 402 m->m_data -= hlen; 403 404 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 405 /* 406 * Deliver very specific ICMP type only. 407 */ 408 switch (icp->icmp_type) { 409 case ICMP_UNREACH: 410 case ICMP_TIMXCEED: 411 break; 412 default: 413 goto freeit; 414 } 415 } 416 417#ifdef ICMPPRINTFS 418 if (icmpprintfs) 419 printf("icmp_input, type %d code %d\n", icp->icmp_type, 420 icp->icmp_code); 421#endif 422 423 /* 424 * Message type specific processing. 425 */ 426 if (icp->icmp_type > ICMP_MAXTYPE) 427 goto raw; 428 429 /* Initialize */ 430 bzero(&icmpsrc, sizeof(icmpsrc)); 431 icmpsrc.sin_len = sizeof(struct sockaddr_in); 432 icmpsrc.sin_family = AF_INET; 433 bzero(&icmpdst, sizeof(icmpdst)); 434 icmpdst.sin_len = sizeof(struct sockaddr_in); 435 icmpdst.sin_family = AF_INET; 436 bzero(&icmpgw, sizeof(icmpgw)); 437 icmpgw.sin_len = sizeof(struct sockaddr_in); 438 icmpgw.sin_family = AF_INET; 439 440 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 441 code = icp->icmp_code; 442 switch (icp->icmp_type) { 443 444 case ICMP_UNREACH: 445 switch (code) { 446 case ICMP_UNREACH_NET: 447 case ICMP_UNREACH_HOST: 448 case ICMP_UNREACH_SRCFAIL: 449 case ICMP_UNREACH_NET_UNKNOWN: 450 case ICMP_UNREACH_HOST_UNKNOWN: 451 case ICMP_UNREACH_ISOLATED: 452 case ICMP_UNREACH_TOSNET: 453 case ICMP_UNREACH_TOSHOST: 454 case ICMP_UNREACH_HOST_PRECEDENCE: 455 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 456 code = PRC_UNREACH_NET; 457 break; 458 459 case ICMP_UNREACH_NEEDFRAG: 460 code = PRC_MSGSIZE; 461 break; 462 463 /* 464 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 465 * Treat subcodes 2,3 as immediate RST 466 */ 467 case ICMP_UNREACH_PROTOCOL: 468 case ICMP_UNREACH_PORT: 469 code = PRC_UNREACH_PORT; 470 break; 471 472 case ICMP_UNREACH_NET_PROHIB: 473 case ICMP_UNREACH_HOST_PROHIB: 474 case ICMP_UNREACH_FILTER_PROHIB: 475 code = PRC_UNREACH_ADMIN_PROHIB; 476 break; 477 478 default: 479 goto badcode; 480 } 481 goto deliver; 482 483 case ICMP_TIMXCEED: 484 if (code > 1) 485 goto badcode; 486 code += PRC_TIMXCEED_INTRANS; 487 goto deliver; 488 489 case ICMP_PARAMPROB: 490 if (code > 1) 491 goto badcode; 492 code = PRC_PARAMPROB; 493 goto deliver; 494 495 case ICMP_SOURCEQUENCH: 496 if (code) 497 goto badcode; 498 code = PRC_QUENCH; 499 deliver: 500 /* 501 * Problem with datagram; advise higher level routines. 502 */ 503 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 504 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 505 ICMPSTAT_INC(icps_badlen); 506 goto freeit; 507 } 508 /* Discard ICMP's in response to multicast packets */ 509 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 510 goto badcode; 511#ifdef ICMPPRINTFS 512 if (icmpprintfs) 513 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 514#endif 515 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 516 /* 517 * XXX if the packet contains [IPv4 AH TCP], we can't make a 518 * notification to TCP layer. 519 */ 520 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 521 if (ctlfunc) 522 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 523 (void *)&icp->icmp_ip); 524 break; 525 526 badcode: 527 ICMPSTAT_INC(icps_badcode); 528 break; 529 530 case ICMP_ECHO: 531 if (!V_icmpbmcastecho 532 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 533 ICMPSTAT_INC(icps_bmcastecho); 534 break; 535 } 536 icp->icmp_type = ICMP_ECHOREPLY; 537 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 538 goto freeit; 539 else 540 goto reflect; 541 542 case ICMP_TSTAMP: 543 if (V_icmptstamprepl == 0) 544 break; 545 if (!V_icmpbmcastecho 546 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 547 ICMPSTAT_INC(icps_bmcasttstamp); 548 break; 549 } 550 if (icmplen < ICMP_TSLEN) { 551 ICMPSTAT_INC(icps_badlen); 552 break; 553 } 554 icp->icmp_type = ICMP_TSTAMPREPLY; 555 icp->icmp_rtime = iptime(); 556 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 557 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 558 goto freeit; 559 else 560 goto reflect; 561 562 case ICMP_MASKREQ: 563 if (V_icmpmaskrepl == 0) 564 break; 565 /* 566 * We are not able to respond with all ones broadcast 567 * unless we receive it over a point-to-point interface. 568 */ 569 if (icmplen < ICMP_MASKLEN) 570 break; 571 switch (ip->ip_dst.s_addr) { 572 573 case INADDR_BROADCAST: 574 case INADDR_ANY: 575 icmpdst.sin_addr = ip->ip_src; 576 break; 577 578 default: 579 icmpdst.sin_addr = ip->ip_dst; 580 } 581 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 582 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 583 if (ia == NULL) 584 break; 585 if (ia->ia_ifp == NULL) { 586 ifa_free(&ia->ia_ifa); 587 break; 588 } 589 icp->icmp_type = ICMP_MASKREPLY; 590 if (V_icmpmaskfake == 0) 591 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 592 else 593 icp->icmp_mask = V_icmpmaskfake; 594 if (ip->ip_src.s_addr == 0) { 595 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 596 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 597 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 598 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 599 } 600 ifa_free(&ia->ia_ifa); 601reflect: 602 ICMPSTAT_INC(icps_reflect); 603 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 604 icmp_reflect(m); 605 return; 606 607 case ICMP_REDIRECT: 608 if (V_log_redirect) { 609 u_long src, dst, gw; 610 611 src = ntohl(ip->ip_src.s_addr); 612 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 613 gw = ntohl(icp->icmp_gwaddr.s_addr); 614 printf("icmp redirect from %d.%d.%d.%d: " 615 "%d.%d.%d.%d => %d.%d.%d.%d\n", 616 (int)(src >> 24), (int)((src >> 16) & 0xff), 617 (int)((src >> 8) & 0xff), (int)(src & 0xff), 618 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 619 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 620 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 621 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 622 } 623 /* 624 * RFC1812 says we must ignore ICMP redirects if we 625 * are acting as router. 626 */ 627 if (V_drop_redirect || V_ipforwarding) 628 break; 629 if (code > 3) 630 goto badcode; 631 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 632 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 633 ICMPSTAT_INC(icps_badlen); 634 break; 635 } 636 /* 637 * Short circuit routing redirects to force 638 * immediate change in the kernel's routing 639 * tables. The message is also handed to anyone 640 * listening on a raw socket (e.g. the routing 641 * daemon for use in updating its tables). 642 */ 643 icmpgw.sin_addr = ip->ip_src; 644 icmpdst.sin_addr = icp->icmp_gwaddr; 645#ifdef ICMPPRINTFS 646 if (icmpprintfs) { 647 char buf[4 * sizeof "123"]; 648 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 649 650 printf("redirect dst %s to %s\n", 651 buf, inet_ntoa(icp->icmp_gwaddr)); 652 } 653#endif 654 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 655 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 656 in_rtredirect((struct sockaddr *)&icmpsrc, 657 (struct sockaddr *)&icmpdst, 658 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 659 (struct sockaddr *)&icmpgw, fibnum); 660 } 661 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 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 678raw: 679 rip_input(m, off); 680 return; 681 682freeit: 683 m_freem(m); 684} 685 686/* 687 * Reflect the ip packet back to the source 688 */ 689static void 690icmp_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 t = ip->ip_dst; 709 ip->ip_dst = ip->ip_src; 710 711 /* 712 * Source selection for ICMP replies: 713 * 714 * If the incoming packet was addressed directly to one of our 715 * own addresses, use dst as the src for the reply. 716 */ 717 IN_IFADDR_RLOCK(); 718 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 719 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 720 t = IA_SIN(ia)->sin_addr; 721 IN_IFADDR_RUNLOCK(); 722 goto match; 723 } 724 } 725 IN_IFADDR_RUNLOCK(); 726 727 /* 728 * If the incoming packet was addressed to one of our broadcast 729 * addresses, use the first non-broadcast address which corresponds 730 * to the incoming interface. 731 */ 732 ifp = m->m_pkthdr.rcvif; 733 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 734 IF_ADDR_RLOCK(ifp); 735 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 736 if (ifa->ifa_addr->sa_family != AF_INET) 737 continue; 738 ia = ifatoia(ifa); 739 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 740 t.s_addr) { 741 t = IA_SIN(ia)->sin_addr; 742 IF_ADDR_RUNLOCK(ifp); 743 goto match; 744 } 745 } 746 IF_ADDR_RUNLOCK(ifp); 747 } 748 /* 749 * If the packet was transiting through us, use the address of 750 * the interface the packet came through in. If that interface 751 * doesn't have a suitable IP address, the normal selection 752 * criteria apply. 753 */ 754 if (V_icmp_rfi && ifp != NULL) { 755 IF_ADDR_RLOCK(ifp); 756 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 757 if (ifa->ifa_addr->sa_family != AF_INET) 758 continue; 759 ia = ifatoia(ifa); 760 t = IA_SIN(ia)->sin_addr; 761 IF_ADDR_RUNLOCK(ifp); 762 goto match; 763 } 764 IF_ADDR_RUNLOCK(ifp); 765 } 766 /* 767 * If the incoming packet was not addressed directly to us, use 768 * designated interface for icmp replies specified by sysctl 769 * net.inet.icmp.reply_src (default not set). Otherwise continue 770 * with normal source selection. 771 */ 772 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 773 IF_ADDR_RLOCK(ifp); 774 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 775 if (ifa->ifa_addr->sa_family != AF_INET) 776 continue; 777 ia = ifatoia(ifa); 778 t = IA_SIN(ia)->sin_addr; 779 IF_ADDR_RUNLOCK(ifp); 780 goto match; 781 } 782 IF_ADDR_RUNLOCK(ifp); 783 } 784 /* 785 * If the packet was transiting through us, use the address of 786 * the interface that is the closest to the packet source. 787 * When we don't have a route back to the packet source, stop here 788 * and drop the packet. 789 */ 790 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 791 if (ia == NULL) { 792 m_freem(m); 793 ICMPSTAT_INC(icps_noroute); 794 goto done; 795 } 796 t = IA_SIN(ia)->sin_addr; 797 ifa_free(&ia->ia_ifa); 798match: 799#ifdef MAC 800 mac_netinet_icmp_replyinplace(m); 801#endif 802 ip->ip_src = t; 803 ip->ip_ttl = V_ip_defttl; 804 805 if (optlen > 0) { 806 register u_char *cp; 807 int opt, cnt; 808 u_int len; 809 810 /* 811 * Retrieve any source routing from the incoming packet; 812 * add on any record-route or timestamp options. 813 */ 814 cp = (u_char *) (ip + 1); 815 if ((opts = ip_srcroute(m)) == 0 && 816 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 817 opts->m_len = sizeof(struct in_addr); 818 mtod(opts, struct in_addr *)->s_addr = 0; 819 } 820 if (opts) { 821#ifdef ICMPPRINTFS 822 if (icmpprintfs) 823 printf("icmp_reflect optlen %d rt %d => ", 824 optlen, opts->m_len); 825#endif 826 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 827 opt = cp[IPOPT_OPTVAL]; 828 if (opt == IPOPT_EOL) 829 break; 830 if (opt == IPOPT_NOP) 831 len = 1; 832 else { 833 if (cnt < IPOPT_OLEN + sizeof(*cp)) 834 break; 835 len = cp[IPOPT_OLEN]; 836 if (len < IPOPT_OLEN + sizeof(*cp) || 837 len > cnt) 838 break; 839 } 840 /* 841 * Should check for overflow, but it "can't happen" 842 */ 843 if (opt == IPOPT_RR || opt == IPOPT_TS || 844 opt == IPOPT_SECURITY) { 845 bcopy((caddr_t)cp, 846 mtod(opts, caddr_t) + opts->m_len, len); 847 opts->m_len += len; 848 } 849 } 850 /* Terminate & pad, if necessary */ 851 cnt = opts->m_len % 4; 852 if (cnt) { 853 for (; cnt < 4; cnt++) { 854 *(mtod(opts, caddr_t) + opts->m_len) = 855 IPOPT_EOL; 856 opts->m_len++; 857 } 858 } 859#ifdef ICMPPRINTFS 860 if (icmpprintfs) 861 printf("%d\n", opts->m_len); 862#endif 863 } 864 ip_stripoptions(m); 865 } 866 m_tag_delete_nonpersistent(m); 867 m->m_flags &= ~(M_BCAST|M_MCAST); 868 icmp_send(m, opts); 869done: 870 if (opts) 871 (void)m_free(opts); 872} 873 874/* 875 * Send an icmp packet back to the ip level, 876 * after supplying a checksum. 877 */ 878static void 879icmp_send(struct mbuf *m, struct mbuf *opts) 880{ 881 register struct ip *ip = mtod(m, struct ip *); 882 register int hlen; 883 register struct icmp *icp; 884 885 hlen = ip->ip_hl << 2; 886 m->m_data += hlen; 887 m->m_len -= hlen; 888 icp = mtod(m, struct icmp *); 889 icp->icmp_cksum = 0; 890 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 891 m->m_data -= hlen; 892 m->m_len += hlen; 893 m->m_pkthdr.rcvif = (struct ifnet *)0; 894#ifdef ICMPPRINTFS 895 if (icmpprintfs) { 896 char buf[4 * sizeof "123"]; 897 strcpy(buf, inet_ntoa(ip->ip_dst)); 898 printf("icmp_send dst %s src %s\n", 899 buf, inet_ntoa(ip->ip_src)); 900 } 901#endif 902 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 903} 904 905/* 906 * Return milliseconds since 00:00 GMT in network format. 907 */ 908uint32_t 909iptime(void) 910{ 911 struct timeval atv; 912 u_long t; 913 914 getmicrotime(&atv); 915 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 916 return (htonl(t)); 917} 918 919/* 920 * Return the next larger or smaller MTU plateau (table from RFC 1191) 921 * given current value MTU. If DIR is less than zero, a larger plateau 922 * is returned; otherwise, a smaller value is returned. 923 */ 924int 925ip_next_mtu(int mtu, int dir) 926{ 927 static int mtutab[] = { 928 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 929 296, 68, 0 930 }; 931 int i, size; 932 933 size = (sizeof mtutab) / (sizeof mtutab[0]); 934 if (dir >= 0) { 935 for (i = 0; i < size; i++) 936 if (mtu > mtutab[i]) 937 return mtutab[i]; 938 } else { 939 for (i = size - 1; i >= 0; i--) 940 if (mtu < mtutab[i]) 941 return mtutab[i]; 942 if (mtu == mtutab[0]) 943 return mtutab[0]; 944 } 945 return 0; 946} 947#endif /* INET */ 948 949 950/* 951 * badport_bandlim() - check for ICMP bandwidth limit 952 * 953 * Return 0 if it is ok to send an ICMP error response, -1 if we have 954 * hit our bandwidth limit and it is not ok. 955 * 956 * If icmplim is <= 0, the feature is disabled and 0 is returned. 957 * 958 * For now we separate the TCP and UDP subsystems w/ different 'which' 959 * values. We may eventually remove this separation (and simplify the 960 * code further). 961 * 962 * Note that the printing of the error message is delayed so we can 963 * properly print the icmp error rate that the system was trying to do 964 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 965 * the 'final' error, but it doesn't make sense to solve the printing 966 * delay with more complex code. 967 */ 968 969int 970badport_bandlim(int which) 971{ 972 973#define N(a) (sizeof (a) / sizeof (a[0])) 974 static struct rate { 975 const char *type; 976 struct timeval lasttime; 977 int curpps; 978 } rates[BANDLIM_MAX+1] = { 979 { "icmp unreach response" }, 980 { "icmp ping response" }, 981 { "icmp tstamp response" }, 982 { "closed port RST response" }, 983 { "open port RST response" }, 984 { "icmp6 unreach response" }, 985 { "sctp ootb response" } 986 }; 987 988 /* 989 * Return ok status if feature disabled or argument out of range. 990 */ 991 if (V_icmplim > 0 && (u_int) which < N(rates)) { 992 struct rate *r = &rates[which]; 993 int opps = r->curpps; 994 995 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 996 return -1; /* discard packet */ 997 /* 998 * If we've dropped below the threshold after having 999 * rate-limited traffic print the message. This preserves 1000 * the previous behaviour at the expense of added complexity. 1001 */ 1002 if (V_icmplim_output && opps > V_icmplim) 1003 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1004 r->type, opps, V_icmplim); 1005 } 1006 return 0; /* okay to send packet */ 1007#undef N 1008} 1009