ip_icmp.c revision 215701
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: head/sys/netinet/ip_icmp.c 215701 2010-11-22 19:32:54Z dim $"); 34 35#include "opt_ipsec.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 IPSEC 66#include <netipsec/ipsec.h> 67#include <netipsec/key.h> 68#endif 69 70#include <machine/in_cksum.h> 71 72#include <security/mac/mac_framework.h> 73 74/* 75 * ICMP routines: error generation, receive packet processing, and 76 * routines to turnaround packets back to the originator, and 77 * host table maintenance routines. 78 */ 79VNET_DEFINE(struct icmpstat, icmpstat); 80SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 81 &VNET_NAME(icmpstat), icmpstat, ""); 82 83static VNET_DEFINE(int, icmpmaskrepl) = 0; 84#define V_icmpmaskrepl VNET(icmpmaskrepl) 85SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 86 &VNET_NAME(icmpmaskrepl), 0, 87 "Reply to ICMP Address Mask Request packets."); 88 89static VNET_DEFINE(u_int, icmpmaskfake) = 0; 90#define V_icmpmaskfake VNET(icmpmaskfake) 91SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 92 &VNET_NAME(icmpmaskfake), 0, 93 "Fake reply to ICMP Address Mask Request packets."); 94 95static VNET_DEFINE(int, drop_redirect) = 0; 96#define V_drop_redirect VNET(drop_redirect) 97SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 98 &VNET_NAME(drop_redirect), 0, 99 "Ignore ICMP redirects"); 100 101static VNET_DEFINE(int, log_redirect) = 0; 102#define V_log_redirect VNET(log_redirect) 103SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 104 &VNET_NAME(log_redirect), 0, 105 "Log ICMP redirects to the console"); 106 107static VNET_DEFINE(int, icmplim) = 200; 108#define V_icmplim VNET(icmplim) 109SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 110 &VNET_NAME(icmplim), 0, 111 "Maximum number of ICMP responses per second"); 112 113static VNET_DEFINE(int, icmplim_output) = 1; 114#define V_icmplim_output VNET(icmplim_output) 115SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 116 &VNET_NAME(icmplim_output), 0, 117 "Enable rate limiting of ICMP responses"); 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 ""); 145 146 147#ifdef ICMPPRINTFS 148int icmpprintfs = 0; 149#endif 150 151static void icmp_reflect(struct mbuf *); 152static void icmp_send(struct mbuf *, struct mbuf *); 153 154extern struct protosw inetsw[]; 155 156/* 157 * Kernel module interface for updating icmpstat. The argument is an index 158 * into icmpstat treated as an array of u_long. While this encodes the 159 * general layout of icmpstat into the caller, it doesn't encode its 160 * location, so that future changes to add, for example, per-CPU stats 161 * support won't cause binary compatibility problems for kernel modules. 162 */ 163void 164kmod_icmpstat_inc(int statnum) 165{ 166 167 (*((u_long *)&V_icmpstat + statnum))++; 168} 169 170/* 171 * Generate an error packet of type error 172 * in response to bad packet ip. 173 */ 174void 175icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 176{ 177 register struct ip *oip = mtod(n, struct ip *), *nip; 178 register unsigned oiphlen = oip->ip_hl << 2; 179 register struct icmp *icp; 180 register struct mbuf *m; 181 unsigned icmplen, icmpelen, nlen; 182 183 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 184#ifdef ICMPPRINTFS 185 if (icmpprintfs) 186 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 187#endif 188 if (type != ICMP_REDIRECT) 189 ICMPSTAT_INC(icps_error); 190 /* 191 * Don't send error: 192 * if the original packet was encrypted. 193 * if not the first fragment of message. 194 * in response to a multicast or broadcast packet. 195 * if the old packet protocol was an ICMP error message. 196 */ 197 if (n->m_flags & M_DECRYPTED) 198 goto freeit; 199 if (oip->ip_off & ~(IP_MF|IP_DF)) 200 goto freeit; 201 if (n->m_flags & (M_BCAST|M_MCAST)) 202 goto freeit; 203 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 204 n->m_len >= oiphlen + ICMP_MINLEN && 205 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 206 ICMPSTAT_INC(icps_oldicmp); 207 goto freeit; 208 } 209 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 210 if (oiphlen + 8 > n->m_len) 211 goto freeit; 212 /* 213 * Calculate length to quote from original packet and 214 * prevent the ICMP mbuf from overflowing. 215 * Unfortunatly this is non-trivial since ip_forward() 216 * sends us truncated packets. 217 */ 218 nlen = m_length(n, NULL); 219 if (oip->ip_p == IPPROTO_TCP) { 220 struct tcphdr *th; 221 int tcphlen; 222 223 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 224 n->m_next == NULL) 225 goto stdreply; 226 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 227 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 228 goto freeit; 229 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 230 tcphlen = th->th_off << 2; 231 if (tcphlen < sizeof(struct tcphdr)) 232 goto freeit; 233 if (oip->ip_len < oiphlen + tcphlen) 234 goto freeit; 235 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 236 goto stdreply; 237 if (n->m_len < oiphlen + tcphlen && 238 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 239 goto freeit; 240 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 241 } else 242stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 243 244 icmplen = min(oiphlen + icmpelen, nlen); 245 if (icmplen < sizeof(struct ip)) 246 goto freeit; 247 248 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 249 m = m_gethdr(M_DONTWAIT, MT_DATA); 250 else 251 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 252 if (m == NULL) 253 goto freeit; 254#ifdef MAC 255 mac_netinet_icmp_reply(n, m); 256#endif 257 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 258 m_align(m, ICMP_MINLEN + icmplen); 259 m->m_len = ICMP_MINLEN + icmplen; 260 261 /* XXX MRT make the outgoing packet use the same FIB 262 * that was associated with the incoming packet 263 */ 264 M_SETFIB(m, M_GETFIB(n)); 265 icp = mtod(m, struct icmp *); 266 ICMPSTAT_INC(icps_outhist[type]); 267 icp->icmp_type = type; 268 if (type == ICMP_REDIRECT) 269 icp->icmp_gwaddr.s_addr = dest; 270 else { 271 icp->icmp_void = 0; 272 /* 273 * The following assignments assume an overlay with the 274 * just zeroed icmp_void field. 275 */ 276 if (type == ICMP_PARAMPROB) { 277 icp->icmp_pptr = code; 278 code = 0; 279 } else if (type == ICMP_UNREACH && 280 code == ICMP_UNREACH_NEEDFRAG && mtu) { 281 icp->icmp_nextmtu = htons(mtu); 282 } 283 } 284 icp->icmp_code = code; 285 286 /* 287 * Copy the quotation into ICMP message and 288 * convert quoted IP header back to network representation. 289 */ 290 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 291 nip = &icp->icmp_ip; 292 nip->ip_len = htons(nip->ip_len); 293 nip->ip_off = htons(nip->ip_off); 294 295 /* 296 * Set up ICMP message mbuf and copy old IP header (without options 297 * in front of ICMP message. 298 * If the original mbuf was meant to bypass the firewall, the error 299 * reply should bypass as well. 300 */ 301 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 302 m->m_data -= sizeof(struct ip); 303 m->m_len += sizeof(struct ip); 304 m->m_pkthdr.len = m->m_len; 305 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 306 nip = mtod(m, struct ip *); 307 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 308 nip->ip_len = m->m_len; 309 nip->ip_v = IPVERSION; 310 nip->ip_hl = 5; 311 nip->ip_p = IPPROTO_ICMP; 312 nip->ip_tos = 0; 313 icmp_reflect(m); 314 315freeit: 316 m_freem(n); 317} 318 319/* 320 * Process a received ICMP message. 321 */ 322void 323icmp_input(struct mbuf *m, int off) 324{ 325 struct icmp *icp; 326 struct in_ifaddr *ia; 327 struct ip *ip = mtod(m, struct ip *); 328 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 329 int hlen = off; 330 int icmplen = ip->ip_len; 331 int i, code; 332 void (*ctlfunc)(int, struct sockaddr *, void *); 333 int fibnum; 334 335 /* 336 * Locate icmp structure in mbuf, and check 337 * that not corrupted and of at least minimum length. 338 */ 339#ifdef ICMPPRINTFS 340 if (icmpprintfs) { 341 char buf[4 * sizeof "123"]; 342 strcpy(buf, inet_ntoa(ip->ip_src)); 343 printf("icmp_input from %s to %s, len %d\n", 344 buf, inet_ntoa(ip->ip_dst), icmplen); 345 } 346#endif 347 if (icmplen < ICMP_MINLEN) { 348 ICMPSTAT_INC(icps_tooshort); 349 goto freeit; 350 } 351 i = hlen + min(icmplen, ICMP_ADVLENMIN); 352 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 353 ICMPSTAT_INC(icps_tooshort); 354 return; 355 } 356 ip = mtod(m, struct ip *); 357 m->m_len -= hlen; 358 m->m_data += hlen; 359 icp = mtod(m, struct icmp *); 360 if (in_cksum(m, icmplen)) { 361 ICMPSTAT_INC(icps_checksum); 362 goto freeit; 363 } 364 m->m_len += hlen; 365 m->m_data -= hlen; 366 367 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 368 /* 369 * Deliver very specific ICMP type only. 370 */ 371 switch (icp->icmp_type) { 372 case ICMP_UNREACH: 373 case ICMP_TIMXCEED: 374 break; 375 default: 376 goto freeit; 377 } 378 } 379 380#ifdef ICMPPRINTFS 381 if (icmpprintfs) 382 printf("icmp_input, type %d code %d\n", icp->icmp_type, 383 icp->icmp_code); 384#endif 385 386 /* 387 * Message type specific processing. 388 */ 389 if (icp->icmp_type > ICMP_MAXTYPE) 390 goto raw; 391 392 /* Initialize */ 393 bzero(&icmpsrc, sizeof(icmpsrc)); 394 icmpsrc.sin_len = sizeof(struct sockaddr_in); 395 icmpsrc.sin_family = AF_INET; 396 bzero(&icmpdst, sizeof(icmpdst)); 397 icmpdst.sin_len = sizeof(struct sockaddr_in); 398 icmpdst.sin_family = AF_INET; 399 bzero(&icmpgw, sizeof(icmpgw)); 400 icmpgw.sin_len = sizeof(struct sockaddr_in); 401 icmpgw.sin_family = AF_INET; 402 403 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 404 code = icp->icmp_code; 405 switch (icp->icmp_type) { 406 407 case ICMP_UNREACH: 408 switch (code) { 409 case ICMP_UNREACH_NET: 410 case ICMP_UNREACH_HOST: 411 case ICMP_UNREACH_SRCFAIL: 412 case ICMP_UNREACH_NET_UNKNOWN: 413 case ICMP_UNREACH_HOST_UNKNOWN: 414 case ICMP_UNREACH_ISOLATED: 415 case ICMP_UNREACH_TOSNET: 416 case ICMP_UNREACH_TOSHOST: 417 case ICMP_UNREACH_HOST_PRECEDENCE: 418 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 419 code = PRC_UNREACH_NET; 420 break; 421 422 case ICMP_UNREACH_NEEDFRAG: 423 code = PRC_MSGSIZE; 424 break; 425 426 /* 427 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 428 * Treat subcodes 2,3 as immediate RST 429 */ 430 case ICMP_UNREACH_PROTOCOL: 431 case ICMP_UNREACH_PORT: 432 code = PRC_UNREACH_PORT; 433 break; 434 435 case ICMP_UNREACH_NET_PROHIB: 436 case ICMP_UNREACH_HOST_PROHIB: 437 case ICMP_UNREACH_FILTER_PROHIB: 438 code = PRC_UNREACH_ADMIN_PROHIB; 439 break; 440 441 default: 442 goto badcode; 443 } 444 goto deliver; 445 446 case ICMP_TIMXCEED: 447 if (code > 1) 448 goto badcode; 449 code += PRC_TIMXCEED_INTRANS; 450 goto deliver; 451 452 case ICMP_PARAMPROB: 453 if (code > 1) 454 goto badcode; 455 code = PRC_PARAMPROB; 456 goto deliver; 457 458 case ICMP_SOURCEQUENCH: 459 if (code) 460 goto badcode; 461 code = PRC_QUENCH; 462 deliver: 463 /* 464 * Problem with datagram; advise higher level routines. 465 */ 466 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 467 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 468 ICMPSTAT_INC(icps_badlen); 469 goto freeit; 470 } 471 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 472 /* Discard ICMP's in response to multicast packets */ 473 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 474 goto badcode; 475#ifdef ICMPPRINTFS 476 if (icmpprintfs) 477 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 478#endif 479 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 480 /* 481 * XXX if the packet contains [IPv4 AH TCP], we can't make a 482 * notification to TCP layer. 483 */ 484 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 485 if (ctlfunc) 486 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 487 (void *)&icp->icmp_ip); 488 break; 489 490 badcode: 491 ICMPSTAT_INC(icps_badcode); 492 break; 493 494 case ICMP_ECHO: 495 if (!V_icmpbmcastecho 496 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 497 ICMPSTAT_INC(icps_bmcastecho); 498 break; 499 } 500 icp->icmp_type = ICMP_ECHOREPLY; 501 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 502 goto freeit; 503 else 504 goto reflect; 505 506 case ICMP_TSTAMP: 507 if (!V_icmpbmcastecho 508 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 509 ICMPSTAT_INC(icps_bmcasttstamp); 510 break; 511 } 512 if (icmplen < ICMP_TSLEN) { 513 ICMPSTAT_INC(icps_badlen); 514 break; 515 } 516 icp->icmp_type = ICMP_TSTAMPREPLY; 517 icp->icmp_rtime = iptime(); 518 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 519 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 520 goto freeit; 521 else 522 goto reflect; 523 524 case ICMP_MASKREQ: 525 if (V_icmpmaskrepl == 0) 526 break; 527 /* 528 * We are not able to respond with all ones broadcast 529 * unless we receive it over a point-to-point interface. 530 */ 531 if (icmplen < ICMP_MASKLEN) 532 break; 533 switch (ip->ip_dst.s_addr) { 534 535 case INADDR_BROADCAST: 536 case INADDR_ANY: 537 icmpdst.sin_addr = ip->ip_src; 538 break; 539 540 default: 541 icmpdst.sin_addr = ip->ip_dst; 542 } 543 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 544 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 545 if (ia == NULL) 546 break; 547 if (ia->ia_ifp == NULL) { 548 ifa_free(&ia->ia_ifa); 549 break; 550 } 551 icp->icmp_type = ICMP_MASKREPLY; 552 if (V_icmpmaskfake == 0) 553 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 554 else 555 icp->icmp_mask = V_icmpmaskfake; 556 if (ip->ip_src.s_addr == 0) { 557 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 558 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 559 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 560 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 561 } 562 ifa_free(&ia->ia_ifa); 563reflect: 564 ip->ip_len += hlen; /* since ip_input deducts this */ 565 ICMPSTAT_INC(icps_reflect); 566 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 567 icmp_reflect(m); 568 return; 569 570 case ICMP_REDIRECT: 571 if (V_log_redirect) { 572 u_long src, dst, gw; 573 574 src = ntohl(ip->ip_src.s_addr); 575 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 576 gw = ntohl(icp->icmp_gwaddr.s_addr); 577 printf("icmp redirect from %d.%d.%d.%d: " 578 "%d.%d.%d.%d => %d.%d.%d.%d\n", 579 (int)(src >> 24), (int)((src >> 16) & 0xff), 580 (int)((src >> 8) & 0xff), (int)(src & 0xff), 581 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 582 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 583 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 584 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 585 } 586 /* 587 * RFC1812 says we must ignore ICMP redirects if we 588 * are acting as router. 589 */ 590 if (V_drop_redirect || V_ipforwarding) 591 break; 592 if (code > 3) 593 goto badcode; 594 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 595 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 596 ICMPSTAT_INC(icps_badlen); 597 break; 598 } 599 /* 600 * Short circuit routing redirects to force 601 * immediate change in the kernel's routing 602 * tables. The message is also handed to anyone 603 * listening on a raw socket (e.g. the routing 604 * daemon for use in updating its tables). 605 */ 606 icmpgw.sin_addr = ip->ip_src; 607 icmpdst.sin_addr = icp->icmp_gwaddr; 608#ifdef ICMPPRINTFS 609 if (icmpprintfs) { 610 char buf[4 * sizeof "123"]; 611 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 612 613 printf("redirect dst %s to %s\n", 614 buf, inet_ntoa(icp->icmp_gwaddr)); 615 } 616#endif 617 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 618 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 619 in_rtredirect((struct sockaddr *)&icmpsrc, 620 (struct sockaddr *)&icmpdst, 621 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 622 (struct sockaddr *)&icmpgw, fibnum); 623 } 624 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 625#ifdef IPSEC 626 key_sa_routechange((struct sockaddr *)&icmpsrc); 627#endif 628 break; 629 630 /* 631 * No kernel processing for the following; 632 * just fall through to send to raw listener. 633 */ 634 case ICMP_ECHOREPLY: 635 case ICMP_ROUTERADVERT: 636 case ICMP_ROUTERSOLICIT: 637 case ICMP_TSTAMPREPLY: 638 case ICMP_IREQREPLY: 639 case ICMP_MASKREPLY: 640 default: 641 break; 642 } 643 644raw: 645 rip_input(m, off); 646 return; 647 648freeit: 649 m_freem(m); 650} 651 652/* 653 * Reflect the ip packet back to the source 654 */ 655static void 656icmp_reflect(struct mbuf *m) 657{ 658 struct ip *ip = mtod(m, struct ip *); 659 struct ifaddr *ifa; 660 struct ifnet *ifp; 661 struct in_ifaddr *ia; 662 struct in_addr t; 663 struct mbuf *opts = 0; 664 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 665 666 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 667 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 668 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 669 m_freem(m); /* Bad return address */ 670 ICMPSTAT_INC(icps_badaddr); 671 goto done; /* Ip_output() will check for broadcast */ 672 } 673 674 t = ip->ip_dst; 675 ip->ip_dst = ip->ip_src; 676 677 /* 678 * Source selection for ICMP replies: 679 * 680 * If the incoming packet was addressed directly to one of our 681 * own addresses, use dst as the src for the reply. 682 */ 683 IN_IFADDR_RLOCK(); 684 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 685 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 686 t = IA_SIN(ia)->sin_addr; 687 IN_IFADDR_RUNLOCK(); 688 goto match; 689 } 690 } 691 IN_IFADDR_RUNLOCK(); 692 693 /* 694 * If the incoming packet was addressed to one of our broadcast 695 * addresses, use the first non-broadcast address which corresponds 696 * to the incoming interface. 697 */ 698 ifp = m->m_pkthdr.rcvif; 699 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 700 IF_ADDR_LOCK(ifp); 701 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 702 if (ifa->ifa_addr->sa_family != AF_INET) 703 continue; 704 ia = ifatoia(ifa); 705 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 706 t.s_addr) { 707 t = IA_SIN(ia)->sin_addr; 708 IF_ADDR_UNLOCK(ifp); 709 goto match; 710 } 711 } 712 IF_ADDR_UNLOCK(ifp); 713 } 714 /* 715 * If the packet was transiting through us, use the address of 716 * the interface the packet came through in. If that interface 717 * doesn't have a suitable IP address, the normal selection 718 * criteria apply. 719 */ 720 if (V_icmp_rfi && ifp != NULL) { 721 IF_ADDR_LOCK(ifp); 722 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 723 if (ifa->ifa_addr->sa_family != AF_INET) 724 continue; 725 ia = ifatoia(ifa); 726 t = IA_SIN(ia)->sin_addr; 727 IF_ADDR_UNLOCK(ifp); 728 goto match; 729 } 730 IF_ADDR_UNLOCK(ifp); 731 } 732 /* 733 * If the incoming packet was not addressed directly to us, use 734 * designated interface for icmp replies specified by sysctl 735 * net.inet.icmp.reply_src (default not set). Otherwise continue 736 * with normal source selection. 737 */ 738 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 739 IF_ADDR_LOCK(ifp); 740 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 741 if (ifa->ifa_addr->sa_family != AF_INET) 742 continue; 743 ia = ifatoia(ifa); 744 t = IA_SIN(ia)->sin_addr; 745 IF_ADDR_UNLOCK(ifp); 746 goto match; 747 } 748 IF_ADDR_UNLOCK(ifp); 749 } 750 /* 751 * If the packet was transiting through us, use the address of 752 * the interface that is the closest to the packet source. 753 * When we don't have a route back to the packet source, stop here 754 * and drop the packet. 755 */ 756 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 757 if (ia == NULL) { 758 m_freem(m); 759 ICMPSTAT_INC(icps_noroute); 760 goto done; 761 } 762 t = IA_SIN(ia)->sin_addr; 763 ifa_free(&ia->ia_ifa); 764match: 765#ifdef MAC 766 mac_netinet_icmp_replyinplace(m); 767#endif 768 ip->ip_src = t; 769 ip->ip_ttl = V_ip_defttl; 770 771 if (optlen > 0) { 772 register u_char *cp; 773 int opt, cnt; 774 u_int len; 775 776 /* 777 * Retrieve any source routing from the incoming packet; 778 * add on any record-route or timestamp options. 779 */ 780 cp = (u_char *) (ip + 1); 781 if ((opts = ip_srcroute(m)) == 0 && 782 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 783 opts->m_len = sizeof(struct in_addr); 784 mtod(opts, struct in_addr *)->s_addr = 0; 785 } 786 if (opts) { 787#ifdef ICMPPRINTFS 788 if (icmpprintfs) 789 printf("icmp_reflect optlen %d rt %d => ", 790 optlen, opts->m_len); 791#endif 792 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 793 opt = cp[IPOPT_OPTVAL]; 794 if (opt == IPOPT_EOL) 795 break; 796 if (opt == IPOPT_NOP) 797 len = 1; 798 else { 799 if (cnt < IPOPT_OLEN + sizeof(*cp)) 800 break; 801 len = cp[IPOPT_OLEN]; 802 if (len < IPOPT_OLEN + sizeof(*cp) || 803 len > cnt) 804 break; 805 } 806 /* 807 * Should check for overflow, but it "can't happen" 808 */ 809 if (opt == IPOPT_RR || opt == IPOPT_TS || 810 opt == IPOPT_SECURITY) { 811 bcopy((caddr_t)cp, 812 mtod(opts, caddr_t) + opts->m_len, len); 813 opts->m_len += len; 814 } 815 } 816 /* Terminate & pad, if necessary */ 817 cnt = opts->m_len % 4; 818 if (cnt) { 819 for (; cnt < 4; cnt++) { 820 *(mtod(opts, caddr_t) + opts->m_len) = 821 IPOPT_EOL; 822 opts->m_len++; 823 } 824 } 825#ifdef ICMPPRINTFS 826 if (icmpprintfs) 827 printf("%d\n", opts->m_len); 828#endif 829 } 830 /* 831 * Now strip out original options by copying rest of first 832 * mbuf's data back, and adjust the IP length. 833 */ 834 ip->ip_len -= optlen; 835 ip->ip_v = IPVERSION; 836 ip->ip_hl = 5; 837 m->m_len -= optlen; 838 if (m->m_flags & M_PKTHDR) 839 m->m_pkthdr.len -= optlen; 840 optlen += sizeof(struct ip); 841 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 842 (unsigned)(m->m_len - sizeof(struct ip))); 843 } 844 m_tag_delete_nonpersistent(m); 845 m->m_flags &= ~(M_BCAST|M_MCAST); 846 icmp_send(m, opts); 847done: 848 if (opts) 849 (void)m_free(opts); 850} 851 852/* 853 * Send an icmp packet back to the ip level, 854 * after supplying a checksum. 855 */ 856static void 857icmp_send(struct mbuf *m, struct mbuf *opts) 858{ 859 register struct ip *ip = mtod(m, struct ip *); 860 register int hlen; 861 register struct icmp *icp; 862 863 hlen = ip->ip_hl << 2; 864 m->m_data += hlen; 865 m->m_len -= hlen; 866 icp = mtod(m, struct icmp *); 867 icp->icmp_cksum = 0; 868 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 869 m->m_data -= hlen; 870 m->m_len += hlen; 871 m->m_pkthdr.rcvif = (struct ifnet *)0; 872#ifdef ICMPPRINTFS 873 if (icmpprintfs) { 874 char buf[4 * sizeof "123"]; 875 strcpy(buf, inet_ntoa(ip->ip_dst)); 876 printf("icmp_send dst %s src %s\n", 877 buf, inet_ntoa(ip->ip_src)); 878 } 879#endif 880 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 881} 882 883/* 884 * Return milliseconds since 00:00 GMT in network format. 885 */ 886uint32_t 887iptime(void) 888{ 889 struct timeval atv; 890 u_long t; 891 892 getmicrotime(&atv); 893 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 894 return (htonl(t)); 895} 896 897/* 898 * Return the next larger or smaller MTU plateau (table from RFC 1191) 899 * given current value MTU. If DIR is less than zero, a larger plateau 900 * is returned; otherwise, a smaller value is returned. 901 */ 902int 903ip_next_mtu(int mtu, int dir) 904{ 905 static int mtutab[] = { 906 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 907 296, 68, 0 908 }; 909 int i, size; 910 911 size = (sizeof mtutab) / (sizeof mtutab[0]); 912 if (dir >= 0) { 913 for (i = 0; i < size; i++) 914 if (mtu > mtutab[i]) 915 return mtutab[i]; 916 } else { 917 for (i = size - 1; i >= 0; i--) 918 if (mtu < mtutab[i]) 919 return mtutab[i]; 920 if (mtu == mtutab[0]) 921 return mtutab[0]; 922 } 923 return 0; 924} 925 926 927/* 928 * badport_bandlim() - check for ICMP bandwidth limit 929 * 930 * Return 0 if it is ok to send an ICMP error response, -1 if we have 931 * hit our bandwidth limit and it is not ok. 932 * 933 * If icmplim is <= 0, the feature is disabled and 0 is returned. 934 * 935 * For now we separate the TCP and UDP subsystems w/ different 'which' 936 * values. We may eventually remove this separation (and simplify the 937 * code further). 938 * 939 * Note that the printing of the error message is delayed so we can 940 * properly print the icmp error rate that the system was trying to do 941 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 942 * the 'final' error, but it doesn't make sense to solve the printing 943 * delay with more complex code. 944 */ 945 946int 947badport_bandlim(int which) 948{ 949 950#define N(a) (sizeof (a) / sizeof (a[0])) 951 static struct rate { 952 const char *type; 953 struct timeval lasttime; 954 int curpps; 955 } rates[BANDLIM_MAX+1] = { 956 { "icmp unreach response" }, 957 { "icmp ping response" }, 958 { "icmp tstamp response" }, 959 { "closed port RST response" }, 960 { "open port RST response" }, 961 { "icmp6 unreach response" } 962 }; 963 964 /* 965 * Return ok status if feature disabled or argument out of range. 966 */ 967 if (V_icmplim > 0 && (u_int) which < N(rates)) { 968 struct rate *r = &rates[which]; 969 int opps = r->curpps; 970 971 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 972 return -1; /* discard packet */ 973 /* 974 * If we've dropped below the threshold after having 975 * rate-limited traffic print the message. This preserves 976 * the previous behaviour at the expense of added complexity. 977 */ 978 if (V_icmplim_output && opps > V_icmplim) 979 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 980 r->type, opps, V_icmplim); 981 } 982 return 0; /* okay to send packet */ 983#undef N 984} 985