ip_icmp.c revision 341258
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 341258 2018-11-29 20:14:09Z emaste $"); 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 151static VNET_DEFINE(int, error_keeptags) = 0; 152#define V_error_keeptags VNET(error_keeptags) 153SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW, 154 &VNET_NAME(error_keeptags), 0, 155 "ICMP error response keeps copy of mbuf_tags of original packet"); 156 157#ifdef ICMPPRINTFS 158int icmpprintfs = 0; 159#endif 160 161static void icmp_reflect(struct mbuf *); 162static void icmp_send(struct mbuf *, struct mbuf *); 163 164extern struct protosw inetsw[]; 165 166static int 167sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS) 168{ 169 int error, new; 170 int i; 171 struct radix_node_head *rnh; 172 173 new = V_drop_redirect; 174 error = sysctl_handle_int(oidp, &new, 0, req); 175 if (error == 0 && req->newptr) { 176 new = (new != 0) ? 1 : 0; 177 178 if (new == V_drop_redirect) 179 return (0); 180 181 for (i = 0; i < rt_numfibs; i++) { 182 if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL) 183 continue; 184 RADIX_NODE_HEAD_LOCK(rnh); 185 in_setmatchfunc(rnh, new); 186 RADIX_NODE_HEAD_UNLOCK(rnh); 187 } 188 189 V_drop_redirect = new; 190 } 191 192 return (error); 193} 194 195SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect, 196 CTLTYPE_INT|CTLFLAG_RW, 0, 0, 197 sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects"); 198 199/* 200 * Kernel module interface for updating icmpstat. The argument is an index 201 * into icmpstat treated as an array of u_long. While this encodes the 202 * general layout of icmpstat into the caller, it doesn't encode its 203 * location, so that future changes to add, for example, per-CPU stats 204 * support won't cause binary compatibility problems for kernel modules. 205 */ 206void 207kmod_icmpstat_inc(int statnum) 208{ 209 210 counter_u64_add(VNET(icmpstat)[statnum], 1); 211} 212 213/* 214 * Generate an error packet of type error 215 * in response to bad packet ip. 216 */ 217void 218icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 219{ 220 register struct ip *oip = mtod(n, struct ip *), *nip; 221 register unsigned oiphlen = oip->ip_hl << 2; 222 register struct icmp *icp; 223 register struct mbuf *m; 224 unsigned icmplen, icmpelen, nlen; 225 226 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 227#ifdef ICMPPRINTFS 228 if (icmpprintfs) 229 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 230#endif 231 if (type != ICMP_REDIRECT) 232 ICMPSTAT_INC(icps_error); 233 /* 234 * Don't send error: 235 * if the original packet was encrypted. 236 * if not the first fragment of message. 237 * in response to a multicast or broadcast packet. 238 * if the old packet protocol was an ICMP error message. 239 */ 240 if (n->m_flags & M_DECRYPTED) 241 goto freeit; 242 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 243 goto freeit; 244 if (n->m_flags & (M_BCAST|M_MCAST)) 245 goto freeit; 246 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 247 n->m_len >= oiphlen + ICMP_MINLEN && 248 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 249 ICMPSTAT_INC(icps_oldicmp); 250 goto freeit; 251 } 252 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 253 if (oiphlen + 8 > n->m_len) 254 goto freeit; 255 /* 256 * Calculate length to quote from original packet and 257 * prevent the ICMP mbuf from overflowing. 258 * Unfortunatly this is non-trivial since ip_forward() 259 * sends us truncated packets. 260 */ 261 nlen = m_length(n, NULL); 262 if (oip->ip_p == IPPROTO_TCP) { 263 struct tcphdr *th; 264 int tcphlen; 265 266 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 267 n->m_next == NULL) 268 goto stdreply; 269 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 270 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 271 goto freeit; 272 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 273 tcphlen = th->th_off << 2; 274 if (tcphlen < sizeof(struct tcphdr)) 275 goto freeit; 276 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 277 goto freeit; 278 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 279 goto stdreply; 280 if (n->m_len < oiphlen + tcphlen && 281 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 282 goto freeit; 283 icmpelen = max(tcphlen, min(V_icmp_quotelen, 284 ntohs(oip->ip_len) - oiphlen)); 285 } else 286stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 287 288 icmplen = min(oiphlen + icmpelen, nlen); 289 if (icmplen < sizeof(struct ip)) 290 goto freeit; 291 292 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 293 m = m_gethdr(M_NOWAIT, MT_DATA); 294 else 295 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 296 if (m == NULL) 297 goto freeit; 298#ifdef MAC 299 mac_netinet_icmp_reply(n, m); 300#endif 301 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 302 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen); 303 m->m_data += sizeof(struct ip); 304 m->m_len = ICMP_MINLEN + icmplen; 305 306 /* XXX MRT make the outgoing packet use the same FIB 307 * that was associated with the incoming packet 308 */ 309 M_SETFIB(m, M_GETFIB(n)); 310 icp = mtod(m, struct icmp *); 311 ICMPSTAT_INC(icps_outhist[type]); 312 icp->icmp_type = type; 313 if (type == ICMP_REDIRECT) 314 icp->icmp_gwaddr.s_addr = dest; 315 else { 316 icp->icmp_void = 0; 317 /* 318 * The following assignments assume an overlay with the 319 * just zeroed icmp_void field. 320 */ 321 if (type == ICMP_PARAMPROB) { 322 icp->icmp_pptr = code; 323 code = 0; 324 } else if (type == ICMP_UNREACH && 325 code == ICMP_UNREACH_NEEDFRAG && mtu) { 326 icp->icmp_nextmtu = htons(mtu); 327 } 328 } 329 icp->icmp_code = code; 330 331 /* 332 * Copy the quotation into ICMP message and 333 * convert quoted IP header back to network representation. 334 */ 335 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 336 nip = &icp->icmp_ip; 337 338 /* 339 * Set up ICMP message mbuf and copy old IP header (without options 340 * in front of ICMP message. 341 * If the original mbuf was meant to bypass the firewall, the error 342 * reply should bypass as well. 343 */ 344 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 345 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip), 346 ("insufficient space for ip header")); 347 m->m_data -= sizeof(struct ip); 348 m->m_len += sizeof(struct ip); 349 m->m_pkthdr.len = m->m_len; 350 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 351 nip = mtod(m, struct ip *); 352 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 353 nip->ip_len = htons(m->m_len); 354 nip->ip_v = IPVERSION; 355 nip->ip_hl = 5; 356 nip->ip_p = IPPROTO_ICMP; 357 nip->ip_tos = 0; 358 nip->ip_off = 0; 359 360 if (V_error_keeptags) 361 m_tag_copy_chain(m, n, M_NOWAIT); 362 363 icmp_reflect(m); 364 365freeit: 366 m_freem(n); 367} 368 369/* 370 * Process a received ICMP message. 371 */ 372void 373icmp_input(struct mbuf *m, int off) 374{ 375 struct icmp *icp; 376 struct in_ifaddr *ia; 377 struct ip *ip = mtod(m, struct ip *); 378 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 379 int hlen = off; 380 int icmplen = ntohs(ip->ip_len) - off; 381 int i, code; 382 void (*ctlfunc)(int, struct sockaddr *, void *); 383 int fibnum; 384 385 /* 386 * Locate icmp structure in mbuf, and check 387 * that not corrupted and of at least minimum length. 388 */ 389#ifdef ICMPPRINTFS 390 if (icmpprintfs) { 391 char buf[4 * sizeof "123"]; 392 strcpy(buf, inet_ntoa(ip->ip_src)); 393 printf("icmp_input from %s to %s, len %d\n", 394 buf, inet_ntoa(ip->ip_dst), icmplen); 395 } 396#endif 397 if (icmplen < ICMP_MINLEN) { 398 ICMPSTAT_INC(icps_tooshort); 399 goto freeit; 400 } 401 i = hlen + min(icmplen, ICMP_ADVLENMIN); 402 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 403 ICMPSTAT_INC(icps_tooshort); 404 return; 405 } 406 ip = mtod(m, struct ip *); 407 m->m_len -= hlen; 408 m->m_data += hlen; 409 icp = mtod(m, struct icmp *); 410 if (in_cksum(m, icmplen)) { 411 ICMPSTAT_INC(icps_checksum); 412 goto freeit; 413 } 414 m->m_len += hlen; 415 m->m_data -= hlen; 416 417 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 418 /* 419 * Deliver very specific ICMP type only. 420 */ 421 switch (icp->icmp_type) { 422 case ICMP_UNREACH: 423 case ICMP_TIMXCEED: 424 break; 425 default: 426 goto freeit; 427 } 428 } 429 430#ifdef ICMPPRINTFS 431 if (icmpprintfs) 432 printf("icmp_input, type %d code %d\n", icp->icmp_type, 433 icp->icmp_code); 434#endif 435 436 /* 437 * Message type specific processing. 438 */ 439 if (icp->icmp_type > ICMP_MAXTYPE) 440 goto raw; 441 442 /* Initialize */ 443 bzero(&icmpsrc, sizeof(icmpsrc)); 444 icmpsrc.sin_len = sizeof(struct sockaddr_in); 445 icmpsrc.sin_family = AF_INET; 446 bzero(&icmpdst, sizeof(icmpdst)); 447 icmpdst.sin_len = sizeof(struct sockaddr_in); 448 icmpdst.sin_family = AF_INET; 449 bzero(&icmpgw, sizeof(icmpgw)); 450 icmpgw.sin_len = sizeof(struct sockaddr_in); 451 icmpgw.sin_family = AF_INET; 452 453 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 454 code = icp->icmp_code; 455 switch (icp->icmp_type) { 456 457 case ICMP_UNREACH: 458 switch (code) { 459 case ICMP_UNREACH_NET: 460 case ICMP_UNREACH_HOST: 461 case ICMP_UNREACH_SRCFAIL: 462 case ICMP_UNREACH_NET_UNKNOWN: 463 case ICMP_UNREACH_HOST_UNKNOWN: 464 case ICMP_UNREACH_ISOLATED: 465 case ICMP_UNREACH_TOSNET: 466 case ICMP_UNREACH_TOSHOST: 467 case ICMP_UNREACH_HOST_PRECEDENCE: 468 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 469 code = PRC_UNREACH_NET; 470 break; 471 472 case ICMP_UNREACH_NEEDFRAG: 473 code = PRC_MSGSIZE; 474 break; 475 476 /* 477 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 478 * Treat subcodes 2,3 as immediate RST 479 */ 480 case ICMP_UNREACH_PROTOCOL: 481 case ICMP_UNREACH_PORT: 482 code = PRC_UNREACH_PORT; 483 break; 484 485 case ICMP_UNREACH_NET_PROHIB: 486 case ICMP_UNREACH_HOST_PROHIB: 487 case ICMP_UNREACH_FILTER_PROHIB: 488 code = PRC_UNREACH_ADMIN_PROHIB; 489 break; 490 491 default: 492 goto badcode; 493 } 494 goto deliver; 495 496 case ICMP_TIMXCEED: 497 if (code > 1) 498 goto badcode; 499 code += PRC_TIMXCEED_INTRANS; 500 goto deliver; 501 502 case ICMP_PARAMPROB: 503 if (code > 1) 504 goto badcode; 505 code = PRC_PARAMPROB; 506 goto deliver; 507 508 case ICMP_SOURCEQUENCH: 509 if (code) 510 goto badcode; 511 code = PRC_QUENCH; 512 deliver: 513 /* 514 * Problem with datagram; advise higher level routines. 515 */ 516 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 517 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 518 ICMPSTAT_INC(icps_badlen); 519 goto freeit; 520 } 521 /* Discard ICMP's in response to multicast packets */ 522 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 523 goto badcode; 524#ifdef ICMPPRINTFS 525 if (icmpprintfs) 526 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 527#endif 528 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 529 /* 530 * XXX if the packet contains [IPv4 AH TCP], we can't make a 531 * notification to TCP layer. 532 */ 533 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 534 if (ctlfunc) 535 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 536 (void *)&icp->icmp_ip); 537 break; 538 539 badcode: 540 ICMPSTAT_INC(icps_badcode); 541 break; 542 543 case ICMP_ECHO: 544 if (!V_icmpbmcastecho 545 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 546 ICMPSTAT_INC(icps_bmcastecho); 547 break; 548 } 549 icp->icmp_type = ICMP_ECHOREPLY; 550 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 551 goto freeit; 552 else 553 goto reflect; 554 555 case ICMP_TSTAMP: 556 if (V_icmptstamprepl == 0) 557 break; 558 if (!V_icmpbmcastecho 559 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 560 ICMPSTAT_INC(icps_bmcasttstamp); 561 break; 562 } 563 if (icmplen < ICMP_TSLEN) { 564 ICMPSTAT_INC(icps_badlen); 565 break; 566 } 567 icp->icmp_type = ICMP_TSTAMPREPLY; 568 icp->icmp_rtime = iptime(); 569 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 570 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 571 goto freeit; 572 else 573 goto reflect; 574 575 case ICMP_MASKREQ: 576 if (V_icmpmaskrepl == 0) 577 break; 578 /* 579 * We are not able to respond with all ones broadcast 580 * unless we receive it over a point-to-point interface. 581 */ 582 if (icmplen < ICMP_MASKLEN) 583 break; 584 switch (ip->ip_dst.s_addr) { 585 586 case INADDR_BROADCAST: 587 case INADDR_ANY: 588 icmpdst.sin_addr = ip->ip_src; 589 break; 590 591 default: 592 icmpdst.sin_addr = ip->ip_dst; 593 } 594 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 595 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 596 if (ia == NULL) 597 break; 598 if (ia->ia_ifp == NULL) { 599 ifa_free(&ia->ia_ifa); 600 break; 601 } 602 icp->icmp_type = ICMP_MASKREPLY; 603 if (V_icmpmaskfake == 0) 604 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 605 else 606 icp->icmp_mask = V_icmpmaskfake; 607 if (ip->ip_src.s_addr == 0) { 608 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 609 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 610 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 611 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 612 } 613 ifa_free(&ia->ia_ifa); 614reflect: 615 ICMPSTAT_INC(icps_reflect); 616 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 617 icmp_reflect(m); 618 return; 619 620 case ICMP_REDIRECT: 621 if (V_log_redirect) { 622 u_long src, dst, gw; 623 624 src = ntohl(ip->ip_src.s_addr); 625 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 626 gw = ntohl(icp->icmp_gwaddr.s_addr); 627 printf("icmp redirect from %d.%d.%d.%d: " 628 "%d.%d.%d.%d => %d.%d.%d.%d\n", 629 (int)(src >> 24), (int)((src >> 16) & 0xff), 630 (int)((src >> 8) & 0xff), (int)(src & 0xff), 631 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 632 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 633 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 634 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 635 } 636 /* 637 * RFC1812 says we must ignore ICMP redirects if we 638 * are acting as router. 639 */ 640 if (V_drop_redirect || V_ipforwarding) 641 break; 642 if (code > 3) 643 goto badcode; 644 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 645 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 646 ICMPSTAT_INC(icps_badlen); 647 break; 648 } 649 /* 650 * Short circuit routing redirects to force 651 * immediate change in the kernel's routing 652 * tables. The message is also handed to anyone 653 * listening on a raw socket (e.g. the routing 654 * daemon for use in updating its tables). 655 */ 656 icmpgw.sin_addr = ip->ip_src; 657 icmpdst.sin_addr = icp->icmp_gwaddr; 658#ifdef ICMPPRINTFS 659 if (icmpprintfs) { 660 char buf[4 * sizeof "123"]; 661 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 662 663 printf("redirect dst %s to %s\n", 664 buf, inet_ntoa(icp->icmp_gwaddr)); 665 } 666#endif 667 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 668 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 669 in_rtredirect((struct sockaddr *)&icmpsrc, 670 (struct sockaddr *)&icmpdst, 671 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 672 (struct sockaddr *)&icmpgw, fibnum); 673 } 674 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 675 break; 676 677 /* 678 * No kernel processing for the following; 679 * just fall through to send to raw listener. 680 */ 681 case ICMP_ECHOREPLY: 682 case ICMP_ROUTERADVERT: 683 case ICMP_ROUTERSOLICIT: 684 case ICMP_TSTAMPREPLY: 685 case ICMP_IREQREPLY: 686 case ICMP_MASKREPLY: 687 default: 688 break; 689 } 690 691raw: 692 rip_input(m, off); 693 return; 694 695freeit: 696 m_freem(m); 697} 698 699/* 700 * Reflect the ip packet back to the source 701 */ 702static void 703icmp_reflect(struct mbuf *m) 704{ 705 struct ip *ip = mtod(m, struct ip *); 706 struct ifaddr *ifa; 707 struct ifnet *ifp; 708 struct in_ifaddr *ia; 709 struct in_addr t; 710 struct mbuf *opts = 0; 711 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 712 713 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 714 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 715 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 716 m_freem(m); /* Bad return address */ 717 ICMPSTAT_INC(icps_badaddr); 718 goto done; /* Ip_output() will check for broadcast */ 719 } 720 721 t = ip->ip_dst; 722 ip->ip_dst = ip->ip_src; 723 724 /* 725 * Source selection for ICMP replies: 726 * 727 * If the incoming packet was addressed directly to one of our 728 * own addresses, use dst as the src for the reply. 729 */ 730 IN_IFADDR_RLOCK(); 731 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 732 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 733 t = IA_SIN(ia)->sin_addr; 734 IN_IFADDR_RUNLOCK(); 735 goto match; 736 } 737 } 738 IN_IFADDR_RUNLOCK(); 739 740 /* 741 * If the incoming packet was addressed to one of our broadcast 742 * addresses, use the first non-broadcast address which corresponds 743 * to the incoming interface. 744 */ 745 ifp = m->m_pkthdr.rcvif; 746 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 747 IF_ADDR_RLOCK(ifp); 748 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 749 if (ifa->ifa_addr->sa_family != AF_INET) 750 continue; 751 ia = ifatoia(ifa); 752 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 753 t.s_addr) { 754 t = IA_SIN(ia)->sin_addr; 755 IF_ADDR_RUNLOCK(ifp); 756 goto match; 757 } 758 } 759 IF_ADDR_RUNLOCK(ifp); 760 } 761 /* 762 * If the packet was transiting through us, use the address of 763 * the interface the packet came through in. If that interface 764 * doesn't have a suitable IP address, the normal selection 765 * criteria apply. 766 */ 767 if (V_icmp_rfi && ifp != NULL) { 768 IF_ADDR_RLOCK(ifp); 769 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 770 if (ifa->ifa_addr->sa_family != AF_INET) 771 continue; 772 ia = ifatoia(ifa); 773 t = IA_SIN(ia)->sin_addr; 774 IF_ADDR_RUNLOCK(ifp); 775 goto match; 776 } 777 IF_ADDR_RUNLOCK(ifp); 778 } 779 /* 780 * If the incoming packet was not addressed directly to us, use 781 * designated interface for icmp replies specified by sysctl 782 * net.inet.icmp.reply_src (default not set). Otherwise continue 783 * with normal source selection. 784 */ 785 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 786 IF_ADDR_RLOCK(ifp); 787 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 788 if (ifa->ifa_addr->sa_family != AF_INET) 789 continue; 790 ia = ifatoia(ifa); 791 t = IA_SIN(ia)->sin_addr; 792 IF_ADDR_RUNLOCK(ifp); 793 goto match; 794 } 795 IF_ADDR_RUNLOCK(ifp); 796 } 797 /* 798 * If the packet was transiting through us, use the address of 799 * the interface that is the closest to the packet source. 800 * When we don't have a route back to the packet source, stop here 801 * and drop the packet. 802 */ 803 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 804 if (ia == NULL) { 805 m_freem(m); 806 ICMPSTAT_INC(icps_noroute); 807 goto done; 808 } 809 t = IA_SIN(ia)->sin_addr; 810 ifa_free(&ia->ia_ifa); 811match: 812#ifdef MAC 813 mac_netinet_icmp_replyinplace(m); 814#endif 815 ip->ip_src = t; 816 ip->ip_ttl = V_ip_defttl; 817 818 if (optlen > 0) { 819 register u_char *cp; 820 int opt, cnt; 821 u_int len; 822 823 /* 824 * Retrieve any source routing from the incoming packet; 825 * add on any record-route or timestamp options. 826 */ 827 cp = (u_char *) (ip + 1); 828 if ((opts = ip_srcroute(m)) == 0 && 829 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 830 opts->m_len = sizeof(struct in_addr); 831 mtod(opts, struct in_addr *)->s_addr = 0; 832 } 833 if (opts) { 834#ifdef ICMPPRINTFS 835 if (icmpprintfs) 836 printf("icmp_reflect optlen %d rt %d => ", 837 optlen, opts->m_len); 838#endif 839 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 840 opt = cp[IPOPT_OPTVAL]; 841 if (opt == IPOPT_EOL) 842 break; 843 if (opt == IPOPT_NOP) 844 len = 1; 845 else { 846 if (cnt < IPOPT_OLEN + sizeof(*cp)) 847 break; 848 len = cp[IPOPT_OLEN]; 849 if (len < IPOPT_OLEN + sizeof(*cp) || 850 len > cnt) 851 break; 852 } 853 /* 854 * Should check for overflow, but it "can't happen" 855 */ 856 if (opt == IPOPT_RR || opt == IPOPT_TS || 857 opt == IPOPT_SECURITY) { 858 bcopy((caddr_t)cp, 859 mtod(opts, caddr_t) + opts->m_len, len); 860 opts->m_len += len; 861 } 862 } 863 /* Terminate & pad, if necessary */ 864 cnt = opts->m_len % 4; 865 if (cnt) { 866 for (; cnt < 4; cnt++) { 867 *(mtod(opts, caddr_t) + opts->m_len) = 868 IPOPT_EOL; 869 opts->m_len++; 870 } 871 } 872#ifdef ICMPPRINTFS 873 if (icmpprintfs) 874 printf("%d\n", opts->m_len); 875#endif 876 } 877 ip_stripoptions(m); 878 } 879 m_tag_delete_nonpersistent(m); 880 m->m_flags &= ~(M_BCAST|M_MCAST); 881 icmp_send(m, opts); 882done: 883 if (opts) 884 (void)m_free(opts); 885} 886 887/* 888 * Send an icmp packet back to the ip level, 889 * after supplying a checksum. 890 */ 891static void 892icmp_send(struct mbuf *m, struct mbuf *opts) 893{ 894 register struct ip *ip = mtod(m, struct ip *); 895 register int hlen; 896 register struct icmp *icp; 897 898 hlen = ip->ip_hl << 2; 899 m->m_data += hlen; 900 m->m_len -= hlen; 901 icp = mtod(m, struct icmp *); 902 icp->icmp_cksum = 0; 903 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 904 m->m_data -= hlen; 905 m->m_len += hlen; 906 m->m_pkthdr.rcvif = (struct ifnet *)0; 907#ifdef ICMPPRINTFS 908 if (icmpprintfs) { 909 char buf[4 * sizeof "123"]; 910 strcpy(buf, inet_ntoa(ip->ip_dst)); 911 printf("icmp_send dst %s src %s\n", 912 buf, inet_ntoa(ip->ip_src)); 913 } 914#endif 915 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 916} 917 918/* 919 * Return milliseconds since 00:00 GMT in network format. 920 */ 921uint32_t 922iptime(void) 923{ 924 struct timeval atv; 925 u_long t; 926 927 getmicrotime(&atv); 928 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 929 return (htonl(t)); 930} 931 932/* 933 * Return the next larger or smaller MTU plateau (table from RFC 1191) 934 * given current value MTU. If DIR is less than zero, a larger plateau 935 * is returned; otherwise, a smaller value is returned. 936 */ 937int 938ip_next_mtu(int mtu, int dir) 939{ 940 static int mtutab[] = { 941 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 942 296, 68, 0 943 }; 944 int i, size; 945 946 size = (sizeof mtutab) / (sizeof mtutab[0]); 947 if (dir >= 0) { 948 for (i = 0; i < size; i++) 949 if (mtu > mtutab[i]) 950 return mtutab[i]; 951 } else { 952 for (i = size - 1; i >= 0; i--) 953 if (mtu < mtutab[i]) 954 return mtutab[i]; 955 if (mtu == mtutab[0]) 956 return mtutab[0]; 957 } 958 return 0; 959} 960#endif /* INET */ 961 962 963/* 964 * badport_bandlim() - check for ICMP bandwidth limit 965 * 966 * Return 0 if it is ok to send an ICMP error response, -1 if we have 967 * hit our bandwidth limit and it is not ok. 968 * 969 * If icmplim is <= 0, the feature is disabled and 0 is returned. 970 * 971 * For now we separate the TCP and UDP subsystems w/ different 'which' 972 * values. We may eventually remove this separation (and simplify the 973 * code further). 974 * 975 * Note that the printing of the error message is delayed so we can 976 * properly print the icmp error rate that the system was trying to do 977 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 978 * the 'final' error, but it doesn't make sense to solve the printing 979 * delay with more complex code. 980 */ 981 982int 983badport_bandlim(int which) 984{ 985 986#define N(a) (sizeof (a) / sizeof (a[0])) 987 static struct rate { 988 const char *type; 989 struct timeval lasttime; 990 int curpps; 991 } rates[BANDLIM_MAX+1] = { 992 { "icmp unreach response" }, 993 { "icmp ping response" }, 994 { "icmp tstamp response" }, 995 { "closed port RST response" }, 996 { "open port RST response" }, 997 { "icmp6 unreach response" }, 998 { "sctp ootb response" } 999 }; 1000 1001 /* 1002 * Return ok status if feature disabled or argument out of range. 1003 */ 1004 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1005 struct rate *r = &rates[which]; 1006 int opps = r->curpps; 1007 1008 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1009 return -1; /* discard packet */ 1010 /* 1011 * If we've dropped below the threshold after having 1012 * rate-limited traffic print the message. This preserves 1013 * the previous behaviour at the expense of added complexity. 1014 */ 1015 if (V_icmplim_output && opps > V_icmplim) 1016 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1017 r->type, opps, V_icmplim); 1018 } 1019 return 0; /* okay to send packet */ 1020#undef N 1021} 1022