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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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 34 * $FreeBSD: releng/5.2/sys/netinet/ip_icmp.c 124286 2004-01-09 12:32:36Z andre $ 35 */ 36 37 #include "opt_ipsec.h" 38 #include "opt_mac.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/mac.h> 43 #include <sys/mbuf.h> 44 #include <sys/protosw.h> 45 #include <sys/socket.h> 46 #include <sys/time.h> 47 #include <sys/kernel.h> 48 #include <sys/sysctl.h> 49 50 #include <net/if.h> 51 #include <net/if_types.h> 52 #include <net/route.h> 53 54 #include <netinet/in.h> 55 #include <netinet/in_pcb.h> 56 #include <netinet/in_systm.h> 57 #include <netinet/in_var.h> 58 #include <netinet/ip.h> 59 #include <netinet/ip_icmp.h> 60 #include <netinet/ip_var.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 IPSEC 67 #include <netinet6/ipsec.h> 68 #include <netkey/key.h> 69 #endif 70 71 #ifdef FAST_IPSEC 72 #include <netipsec/ipsec.h> 73 #include <netipsec/key.h> 74 #define IPSEC 75 #endif 76 77 #include <machine/in_cksum.h> 78 79 /* 80 * ICMP routines: error generation, receive packet processing, and 81 * routines to turnaround packets back to the originator, and 82 * host table maintenance routines. 83 */ 84 85 static struct icmpstat icmpstat; 86 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 87 &icmpstat, icmpstat, ""); 88 89 static int icmpmaskrepl = 0; 90 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 91 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 92 93 static u_int icmpmaskfake = 0; 94 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 95 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 96 97 static int drop_redirect = 0; 98 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 99 &drop_redirect, 0, ""); 100 101 static int log_redirect = 0; 102 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 103 &log_redirect, 0, ""); 104 105 static int icmplim = 200; 106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 107 &icmplim, 0, ""); 108 109 static int icmplim_output = 1; 110 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 111 &icmplim_output, 0, ""); 112 113 /* 114 * ICMP broadcast echo sysctl 115 */ 116 117 static int icmpbmcastecho = 0; 118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 119 &icmpbmcastecho, 0, ""); 120 121 122 #ifdef ICMPPRINTFS 123 int icmpprintfs = 0; 124 #endif 125 126 static void icmp_reflect(struct mbuf *); 127 static void icmp_send(struct mbuf *, struct mbuf *); 128 static int ip_next_mtu(int, int); 129 130 extern struct protosw inetsw[]; 131 132 /* 133 * Generate an error packet of type error 134 * in response to bad packet ip. 135 */ 136 void 137 icmp_error(n, type, code, dest, destifp) 138 struct mbuf *n; 139 int type, code; 140 n_long dest; 141 struct ifnet *destifp; 142 { 143 register struct ip *oip = mtod(n, struct ip *), *nip; 144 register unsigned oiplen = oip->ip_hl << 2; 145 register struct icmp *icp; 146 register struct mbuf *m; 147 unsigned icmplen; 148 149 #ifdef ICMPPRINTFS 150 if (icmpprintfs) 151 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 152 #endif 153 if (type != ICMP_REDIRECT) 154 icmpstat.icps_error++; 155 /* 156 * Don't send error if not the first fragment of message. 157 * Don't error if the old packet protocol was ICMP 158 * error message, only known informational types. 159 */ 160 if (oip->ip_off &~ (IP_MF|IP_DF)) 161 goto freeit; 162 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 163 n->m_len >= oiplen + ICMP_MINLEN && 164 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 165 icmpstat.icps_oldicmp++; 166 goto freeit; 167 } 168 /* Don't send error in response to a multicast or broadcast packet */ 169 if (n->m_flags & (M_BCAST|M_MCAST)) 170 goto freeit; 171 /* 172 * First, formulate icmp message 173 */ 174 m = m_gethdr(M_DONTWAIT, MT_HEADER); 175 if (m == NULL) 176 goto freeit; 177 #ifdef MAC 178 mac_create_mbuf_netlayer(n, m); 179 #endif 180 icmplen = min(oiplen + 8, oip->ip_len); 181 if (icmplen < sizeof(struct ip)) 182 panic("icmp_error: bad length"); 183 m->m_len = icmplen + ICMP_MINLEN; 184 MH_ALIGN(m, m->m_len); 185 icp = mtod(m, struct icmp *); 186 if ((u_int)type > ICMP_MAXTYPE) 187 panic("icmp_error"); 188 icmpstat.icps_outhist[type]++; 189 icp->icmp_type = type; 190 if (type == ICMP_REDIRECT) 191 icp->icmp_gwaddr.s_addr = dest; 192 else { 193 icp->icmp_void = 0; 194 /* 195 * The following assignments assume an overlay with the 196 * zeroed icmp_void field. 197 */ 198 if (type == ICMP_PARAMPROB) { 199 icp->icmp_pptr = code; 200 code = 0; 201 } else if (type == ICMP_UNREACH && 202 code == ICMP_UNREACH_NEEDFRAG && destifp) { 203 icp->icmp_nextmtu = htons(destifp->if_mtu); 204 } 205 } 206 207 icp->icmp_code = code; 208 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 209 nip = &icp->icmp_ip; 210 211 /* 212 * Convert fields to network representation. 213 */ 214 nip->ip_len = htons(nip->ip_len); 215 nip->ip_off = htons(nip->ip_off); 216 217 /* 218 * Now, copy old ip header (without options) 219 * in front of icmp message. 220 */ 221 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 222 panic("icmp len"); 223 m->m_data -= sizeof(struct ip); 224 m->m_len += sizeof(struct ip); 225 m->m_pkthdr.len = m->m_len; 226 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 227 nip = mtod(m, struct ip *); 228 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 229 nip->ip_len = m->m_len; 230 nip->ip_v = IPVERSION; 231 nip->ip_hl = 5; 232 nip->ip_p = IPPROTO_ICMP; 233 nip->ip_tos = 0; 234 icmp_reflect(m); 235 236 freeit: 237 m_freem(n); 238 } 239 240 /* 241 * Process a received ICMP message. 242 */ 243 void 244 icmp_input(m, off) 245 struct mbuf *m; 246 int off; 247 { 248 struct icmp *icp; 249 struct in_ifaddr *ia; 250 struct ip *ip = mtod(m, struct ip *); 251 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 252 int hlen = off; 253 int icmplen = ip->ip_len; 254 int i, code; 255 void (*ctlfunc)(int, struct sockaddr *, void *); 256 257 /* 258 * Locate icmp structure in mbuf, and check 259 * that not corrupted and of at least minimum length. 260 */ 261 #ifdef ICMPPRINTFS 262 if (icmpprintfs) { 263 char buf[4 * sizeof "123"]; 264 strcpy(buf, inet_ntoa(ip->ip_src)); 265 printf("icmp_input from %s to %s, len %d\n", 266 buf, inet_ntoa(ip->ip_dst), icmplen); 267 } 268 #endif 269 if (icmplen < ICMP_MINLEN) { 270 icmpstat.icps_tooshort++; 271 goto freeit; 272 } 273 i = hlen + min(icmplen, ICMP_ADVLENMIN); 274 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 275 icmpstat.icps_tooshort++; 276 return; 277 } 278 ip = mtod(m, struct ip *); 279 m->m_len -= hlen; 280 m->m_data += hlen; 281 icp = mtod(m, struct icmp *); 282 if (in_cksum(m, icmplen)) { 283 icmpstat.icps_checksum++; 284 goto freeit; 285 } 286 m->m_len += hlen; 287 m->m_data -= hlen; 288 289 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 290 /* 291 * Deliver very specific ICMP type only. 292 */ 293 switch (icp->icmp_type) { 294 case ICMP_UNREACH: 295 case ICMP_TIMXCEED: 296 break; 297 default: 298 goto freeit; 299 } 300 } 301 302 #ifdef ICMPPRINTFS 303 if (icmpprintfs) 304 printf("icmp_input, type %d code %d\n", icp->icmp_type, 305 icp->icmp_code); 306 #endif 307 308 /* 309 * Message type specific processing. 310 */ 311 if (icp->icmp_type > ICMP_MAXTYPE) 312 goto raw; 313 314 /* Initialize */ 315 bzero(&icmpsrc, sizeof(icmpsrc)); 316 icmpsrc.sin_len = sizeof(struct sockaddr_in); 317 icmpsrc.sin_family = AF_INET; 318 bzero(&icmpdst, sizeof(icmpdst)); 319 icmpdst.sin_len = sizeof(struct sockaddr_in); 320 icmpdst.sin_family = AF_INET; 321 bzero(&icmpgw, sizeof(icmpgw)); 322 icmpgw.sin_len = sizeof(struct sockaddr_in); 323 icmpgw.sin_family = AF_INET; 324 325 icmpstat.icps_inhist[icp->icmp_type]++; 326 code = icp->icmp_code; 327 switch (icp->icmp_type) { 328 329 case ICMP_UNREACH: 330 switch (code) { 331 case ICMP_UNREACH_NET: 332 case ICMP_UNREACH_HOST: 333 case ICMP_UNREACH_SRCFAIL: 334 case ICMP_UNREACH_NET_UNKNOWN: 335 case ICMP_UNREACH_HOST_UNKNOWN: 336 case ICMP_UNREACH_ISOLATED: 337 case ICMP_UNREACH_TOSNET: 338 case ICMP_UNREACH_TOSHOST: 339 case ICMP_UNREACH_HOST_PRECEDENCE: 340 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 341 code = PRC_UNREACH_NET; 342 break; 343 344 case ICMP_UNREACH_NEEDFRAG: 345 code = PRC_MSGSIZE; 346 break; 347 348 /* 349 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 350 * Treat subcodes 2,3 as immediate RST 351 */ 352 case ICMP_UNREACH_PROTOCOL: 353 case ICMP_UNREACH_PORT: 354 code = PRC_UNREACH_PORT; 355 break; 356 357 case ICMP_UNREACH_NET_PROHIB: 358 case ICMP_UNREACH_HOST_PROHIB: 359 case ICMP_UNREACH_FILTER_PROHIB: 360 code = PRC_UNREACH_ADMIN_PROHIB; 361 break; 362 363 default: 364 goto badcode; 365 } 366 goto deliver; 367 368 case ICMP_TIMXCEED: 369 if (code > 1) 370 goto badcode; 371 code += PRC_TIMXCEED_INTRANS; 372 goto deliver; 373 374 case ICMP_PARAMPROB: 375 if (code > 1) 376 goto badcode; 377 code = PRC_PARAMPROB; 378 goto deliver; 379 380 case ICMP_SOURCEQUENCH: 381 if (code) 382 goto badcode; 383 code = PRC_QUENCH; 384 deliver: 385 /* 386 * Problem with datagram; advise higher level routines. 387 */ 388 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 389 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 390 icmpstat.icps_badlen++; 391 goto freeit; 392 } 393 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 394 /* Discard ICMP's in response to multicast packets */ 395 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 396 goto badcode; 397 #ifdef ICMPPRINTFS 398 if (icmpprintfs) 399 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 400 #endif 401 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 402 403 /* 404 * MTU discovery: 405 * If we got a needfrag and there is a host route to the 406 * original destination, and the MTU is not locked, then 407 * set the MTU in the route to the suggested new value 408 * (if given) and then notify as usual. The ULPs will 409 * notice that the MTU has changed and adapt accordingly. 410 * If no new MTU was suggested, then we guess a new one 411 * less than the current value. If the new MTU is 412 * unreasonably small (defined by sysctl tcp_minmss), then 413 * we don't update the MTU value. 414 * 415 * XXX: All this should be done in tcp_mtudisc() because 416 * the way we do it now, everyone can send us bogus ICMP 417 * MSGSIZE packets for any destination. By doing this far 418 * higher in the chain we have a matching tcp connection. 419 * Thus spoofing is much harder. However there is no easy 420 * non-hackish way to pass the new MTU up to tcp_mtudisc(). 421 * Also see next XXX regarding IPv4 AH TCP. 422 */ 423 if (code == PRC_MSGSIZE) { 424 int mtu; 425 struct in_conninfo inc; 426 427 bzero(&inc, sizeof(inc)); 428 inc.inc_flags = 0; /* IPv4 */ 429 inc.inc_faddr = icmpsrc.sin_addr; 430 431 mtu = ntohs(icp->icmp_nextmtu); 432 if (!mtu) 433 mtu = ip_next_mtu(mtu, 1); 434 435 if (mtu >= max(296, (tcp_minmss + 436 sizeof(struct tcpiphdr)))) 437 tcp_hc_updatemtu(&inc, mtu); 438 439 #ifdef DEBUG_MTUDISC 440 printf("MTU for %s reduced to %d\n", 441 inet_ntoa(icmpsrc.sin_addr), mtu); 442 #endif 443 } 444 445 /* 446 * XXX if the packet contains [IPv4 AH TCP], we can't make a 447 * notification to TCP layer. 448 */ 449 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 450 if (ctlfunc) 451 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 452 (void *)&icp->icmp_ip); 453 break; 454 455 badcode: 456 icmpstat.icps_badcode++; 457 break; 458 459 case ICMP_ECHO: 460 if (!icmpbmcastecho 461 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 462 icmpstat.icps_bmcastecho++; 463 break; 464 } 465 icp->icmp_type = ICMP_ECHOREPLY; 466 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 467 goto freeit; 468 else 469 goto reflect; 470 471 case ICMP_TSTAMP: 472 if (!icmpbmcastecho 473 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 474 icmpstat.icps_bmcasttstamp++; 475 break; 476 } 477 if (icmplen < ICMP_TSLEN) { 478 icmpstat.icps_badlen++; 479 break; 480 } 481 icp->icmp_type = ICMP_TSTAMPREPLY; 482 icp->icmp_rtime = iptime(); 483 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 484 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 485 goto freeit; 486 else 487 goto reflect; 488 489 case ICMP_MASKREQ: 490 if (icmpmaskrepl == 0) 491 break; 492 /* 493 * We are not able to respond with all ones broadcast 494 * unless we receive it over a point-to-point interface. 495 */ 496 if (icmplen < ICMP_MASKLEN) 497 break; 498 switch (ip->ip_dst.s_addr) { 499 500 case INADDR_BROADCAST: 501 case INADDR_ANY: 502 icmpdst.sin_addr = ip->ip_src; 503 break; 504 505 default: 506 icmpdst.sin_addr = ip->ip_dst; 507 } 508 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 509 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 510 if (ia == 0) 511 break; 512 if (ia->ia_ifp == 0) 513 break; 514 icp->icmp_type = ICMP_MASKREPLY; 515 if (icmpmaskfake == 0) 516 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 517 else 518 icp->icmp_mask = icmpmaskfake; 519 if (ip->ip_src.s_addr == 0) { 520 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 521 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 522 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 523 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 524 } 525 reflect: 526 ip->ip_len += hlen; /* since ip_input deducts this */ 527 icmpstat.icps_reflect++; 528 icmpstat.icps_outhist[icp->icmp_type]++; 529 icmp_reflect(m); 530 return; 531 532 case ICMP_REDIRECT: 533 if (log_redirect) { 534 u_long src, dst, gw; 535 536 src = ntohl(ip->ip_src.s_addr); 537 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 538 gw = ntohl(icp->icmp_gwaddr.s_addr); 539 printf("icmp redirect from %d.%d.%d.%d: " 540 "%d.%d.%d.%d => %d.%d.%d.%d\n", 541 (int)(src >> 24), (int)((src >> 16) & 0xff), 542 (int)((src >> 8) & 0xff), (int)(src & 0xff), 543 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 544 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 545 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 546 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 547 } 548 if (drop_redirect) 549 break; 550 if (code > 3) 551 goto badcode; 552 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 553 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 554 icmpstat.icps_badlen++; 555 break; 556 } 557 /* 558 * Short circuit routing redirects to force 559 * immediate change in the kernel's routing 560 * tables. The message is also handed to anyone 561 * listening on a raw socket (e.g. the routing 562 * daemon for use in updating its tables). 563 */ 564 icmpgw.sin_addr = ip->ip_src; 565 icmpdst.sin_addr = icp->icmp_gwaddr; 566 #ifdef ICMPPRINTFS 567 if (icmpprintfs) { 568 char buf[4 * sizeof "123"]; 569 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 570 571 printf("redirect dst %s to %s\n", 572 buf, inet_ntoa(icp->icmp_gwaddr)); 573 } 574 #endif 575 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 576 rtredirect((struct sockaddr *)&icmpsrc, 577 (struct sockaddr *)&icmpdst, 578 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 579 (struct sockaddr *)&icmpgw); 580 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 581 #ifdef IPSEC 582 key_sa_routechange((struct sockaddr *)&icmpsrc); 583 #endif 584 break; 585 586 /* 587 * No kernel processing for the following; 588 * just fall through to send to raw listener. 589 */ 590 case ICMP_ECHOREPLY: 591 case ICMP_ROUTERADVERT: 592 case ICMP_ROUTERSOLICIT: 593 case ICMP_TSTAMPREPLY: 594 case ICMP_IREQREPLY: 595 case ICMP_MASKREPLY: 596 default: 597 break; 598 } 599 600 raw: 601 rip_input(m, off); 602 return; 603 604 freeit: 605 m_freem(m); 606 } 607 608 /* 609 * Reflect the ip packet back to the source 610 */ 611 static void 612 icmp_reflect(m) 613 struct mbuf *m; 614 { 615 struct ip *ip = mtod(m, struct ip *); 616 struct ifaddr *ifa; 617 struct in_ifaddr *ia; 618 struct in_addr t; 619 struct mbuf *opts = 0; 620 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 621 622 if (!in_canforward(ip->ip_src) && 623 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 624 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 625 m_freem(m); /* Bad return address */ 626 icmpstat.icps_badaddr++; 627 goto done; /* Ip_output() will check for broadcast */ 628 } 629 t = ip->ip_dst; 630 ip->ip_dst = ip->ip_src; 631 /* 632 * If the incoming packet was addressed directly to us, 633 * use dst as the src for the reply. Otherwise (broadcast 634 * or anonymous), use the address which corresponds 635 * to the incoming interface. 636 */ 637 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 638 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 639 goto match; 640 if (m->m_pkthdr.rcvif != NULL && 641 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 642 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 643 if (ifa->ifa_addr->sa_family != AF_INET) 644 continue; 645 ia = ifatoia(ifa); 646 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 647 t.s_addr) 648 goto match; 649 } 650 } 651 ia = ip_rtaddr(ip->ip_dst); 652 /* We need a route to do anything useful. */ 653 if (ia == NULL) { 654 m_freem(m); 655 icmpstat.icps_noroute++; 656 goto done; 657 } 658 match: 659 #ifdef MAC 660 mac_reflect_mbuf_icmp(m); 661 #endif 662 t = IA_SIN(ia)->sin_addr; 663 ip->ip_src = t; 664 ip->ip_ttl = ip_defttl; 665 666 if (optlen > 0) { 667 register u_char *cp; 668 int opt, cnt; 669 u_int len; 670 671 /* 672 * Retrieve any source routing from the incoming packet; 673 * add on any record-route or timestamp options. 674 */ 675 cp = (u_char *) (ip + 1); 676 if ((opts = ip_srcroute()) == 0 && 677 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 678 opts->m_len = sizeof(struct in_addr); 679 mtod(opts, struct in_addr *)->s_addr = 0; 680 } 681 if (opts) { 682 #ifdef ICMPPRINTFS 683 if (icmpprintfs) 684 printf("icmp_reflect optlen %d rt %d => ", 685 optlen, opts->m_len); 686 #endif 687 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 688 opt = cp[IPOPT_OPTVAL]; 689 if (opt == IPOPT_EOL) 690 break; 691 if (opt == IPOPT_NOP) 692 len = 1; 693 else { 694 if (cnt < IPOPT_OLEN + sizeof(*cp)) 695 break; 696 len = cp[IPOPT_OLEN]; 697 if (len < IPOPT_OLEN + sizeof(*cp) || 698 len > cnt) 699 break; 700 } 701 /* 702 * Should check for overflow, but it "can't happen" 703 */ 704 if (opt == IPOPT_RR || opt == IPOPT_TS || 705 opt == IPOPT_SECURITY) { 706 bcopy((caddr_t)cp, 707 mtod(opts, caddr_t) + opts->m_len, len); 708 opts->m_len += len; 709 } 710 } 711 /* Terminate & pad, if necessary */ 712 cnt = opts->m_len % 4; 713 if (cnt) { 714 for (; cnt < 4; cnt++) { 715 *(mtod(opts, caddr_t) + opts->m_len) = 716 IPOPT_EOL; 717 opts->m_len++; 718 } 719 } 720 #ifdef ICMPPRINTFS 721 if (icmpprintfs) 722 printf("%d\n", opts->m_len); 723 #endif 724 } 725 /* 726 * Now strip out original options by copying rest of first 727 * mbuf's data back, and adjust the IP length. 728 */ 729 ip->ip_len -= optlen; 730 ip->ip_v = IPVERSION; 731 ip->ip_hl = 5; 732 m->m_len -= optlen; 733 if (m->m_flags & M_PKTHDR) 734 m->m_pkthdr.len -= optlen; 735 optlen += sizeof(struct ip); 736 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 737 (unsigned)(m->m_len - sizeof(struct ip))); 738 } 739 m_tag_delete_nonpersistent(m); 740 m->m_flags &= ~(M_BCAST|M_MCAST); 741 icmp_send(m, opts); 742 done: 743 if (opts) 744 (void)m_free(opts); 745 } 746 747 /* 748 * Send an icmp packet back to the ip level, 749 * after supplying a checksum. 750 */ 751 static void 752 icmp_send(m, opts) 753 register struct mbuf *m; 754 struct mbuf *opts; 755 { 756 register struct ip *ip = mtod(m, struct ip *); 757 register int hlen; 758 register struct icmp *icp; 759 760 hlen = ip->ip_hl << 2; 761 m->m_data += hlen; 762 m->m_len -= hlen; 763 icp = mtod(m, struct icmp *); 764 icp->icmp_cksum = 0; 765 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 766 m->m_data -= hlen; 767 m->m_len += hlen; 768 m->m_pkthdr.rcvif = (struct ifnet *)0; 769 #ifdef ICMPPRINTFS 770 if (icmpprintfs) { 771 char buf[4 * sizeof "123"]; 772 strcpy(buf, inet_ntoa(ip->ip_dst)); 773 printf("icmp_send dst %s src %s\n", 774 buf, inet_ntoa(ip->ip_src)); 775 } 776 #endif 777 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 778 } 779 780 n_time 781 iptime() 782 { 783 struct timeval atv; 784 u_long t; 785 786 getmicrotime(&atv); 787 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 788 return (htonl(t)); 789 } 790 791 /* 792 * Return the next larger or smaller MTU plateau (table from RFC 1191) 793 * given current value MTU. If DIR is less than zero, a larger plateau 794 * is returned; otherwise, a smaller value is returned. 795 */ 796 static int 797 ip_next_mtu(mtu, dir) 798 int mtu; 799 int dir; 800 { 801 static int mtutab[] = { 802 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 803 68, 0 804 }; 805 int i; 806 807 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 808 if (mtu >= mtutab[i]) 809 break; 810 } 811 812 if (dir < 0) { 813 if (i == 0) { 814 return 0; 815 } else { 816 return mtutab[i - 1]; 817 } 818 } else { 819 if (mtutab[i] == 0) { 820 return 0; 821 } else if(mtu > mtutab[i]) { 822 return mtutab[i]; 823 } else { 824 return mtutab[i + 1]; 825 } 826 } 827 } 828 829 830 /* 831 * badport_bandlim() - check for ICMP bandwidth limit 832 * 833 * Return 0 if it is ok to send an ICMP error response, -1 if we have 834 * hit our bandwidth limit and it is not ok. 835 * 836 * If icmplim is <= 0, the feature is disabled and 0 is returned. 837 * 838 * For now we separate the TCP and UDP subsystems w/ different 'which' 839 * values. We may eventually remove this separation (and simplify the 840 * code further). 841 * 842 * Note that the printing of the error message is delayed so we can 843 * properly print the icmp error rate that the system was trying to do 844 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 845 * the 'final' error, but it doesn't make sense to solve the printing 846 * delay with more complex code. 847 */ 848 849 int 850 badport_bandlim(int which) 851 { 852 #define N(a) (sizeof (a) / sizeof (a[0])) 853 static struct rate { 854 const char *type; 855 struct timeval lasttime; 856 int curpps;; 857 } rates[BANDLIM_MAX+1] = { 858 { "icmp unreach response" }, 859 { "icmp ping response" }, 860 { "icmp tstamp response" }, 861 { "closed port RST response" }, 862 { "open port RST response" } 863 }; 864 865 /* 866 * Return ok status if feature disabled or argument out of range. 867 */ 868 if (icmplim > 0 && (u_int) which < N(rates)) { 869 struct rate *r = &rates[which]; 870 int opps = r->curpps; 871 872 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 873 return -1; /* discard packet */ 874 /* 875 * If we've dropped below the threshold after having 876 * rate-limited traffic print the message. This preserves 877 * the previous behaviour at the expense of added complexity. 878 */ 879 if (icmplim_output && opps > icmplim) 880 printf("Limiting %s from %d to %d packets/sec\n", 881 r->type, opps, icmplim); 882 } 883 return 0; /* okay to send packet */ 884 #undef N 885 }
Cache object: dcc3c0b6549052c7afdbf84cd768eadb
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