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sys/netinet/ip_icmp.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 30 * $FreeBSD$ 31 */ 32 33 #include "opt_ipsec.h" 34 #include "opt_mac.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/mac.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 51 #include <netinet/in.h> 52 #include <netinet/in_pcb.h> 53 #include <netinet/in_systm.h> 54 #include <netinet/in_var.h> 55 #include <netinet/ip.h> 56 #include <netinet/ip_icmp.h> 57 #include <netinet/ip_var.h> 58 #include <netinet/tcp.h> 59 #include <netinet/tcp_var.h> 60 #include <netinet/tcpip.h> 61 #include <netinet/icmp_var.h> 62 63 #ifdef IPSEC 64 #include <netinet6/ipsec.h> 65 #include <netkey/key.h> 66 #endif 67 68 #ifdef FAST_IPSEC 69 #include <netipsec/ipsec.h> 70 #include <netipsec/key.h> 71 #define IPSEC 72 #endif 73 74 #include <machine/in_cksum.h> 75 76 /* 77 * ICMP routines: error generation, receive packet processing, and 78 * routines to turnaround packets back to the originator, and 79 * host table maintenance routines. 80 */ 81 82 struct icmpstat icmpstat; 83 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 84 &icmpstat, icmpstat, ""); 85 86 static int icmpmaskrepl = 0; 87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 88 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 89 90 static u_int icmpmaskfake = 0; 91 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 92 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 93 94 static int drop_redirect = 0; 95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 96 &drop_redirect, 0, ""); 97 98 static int log_redirect = 0; 99 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 100 &log_redirect, 0, ""); 101 102 static int icmplim = 200; 103 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 104 &icmplim, 0, ""); 105 106 static int icmplim_output = 1; 107 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 108 &icmplim_output, 0, ""); 109 110 static char reply_src[IFNAMSIZ]; 111 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 112 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 113 114 static int icmp_rfi = 0; 115 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 116 &icmp_rfi, 0, "ICMP reply from incoming interface for " 117 "non-local packets"); 118 119 static int icmp_quotelen = 8; 120 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 121 &icmp_quotelen, 0, "Number of bytes from original packet to " 122 "quote in ICMP reply"); 123 124 /* 125 * ICMP broadcast echo sysctl 126 */ 127 128 static int icmpbmcastecho = 0; 129 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 130 &icmpbmcastecho, 0, ""); 131 132 133 #ifdef ICMPPRINTFS 134 int icmpprintfs = 0; 135 #endif 136 137 static void icmp_reflect(struct mbuf *); 138 static void icmp_send(struct mbuf *, struct mbuf *); 139 140 extern struct protosw inetsw[]; 141 142 /* 143 * Generate an error packet of type error 144 * in response to bad packet ip. 145 */ 146 void 147 icmp_error(n, type, code, dest, mtu) 148 struct mbuf *n; 149 int type, code; 150 n_long dest; 151 int mtu; 152 { 153 register struct ip *oip = mtod(n, struct ip *), *nip; 154 register unsigned oiphlen = oip->ip_hl << 2; 155 register struct icmp *icp; 156 register struct mbuf *m; 157 unsigned icmplen, icmpelen, nlen; 158 159 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 160 #ifdef ICMPPRINTFS 161 if (icmpprintfs) 162 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 163 #endif 164 if (type != ICMP_REDIRECT) 165 icmpstat.icps_error++; 166 /* 167 * Don't send error: 168 * if the original packet was encrypted. 169 * if not the first fragment of message. 170 * in response to a multicast or broadcast packet. 171 * if the old packet protocol was an ICMP error message. 172 */ 173 if (n->m_flags & M_DECRYPTED) 174 goto freeit; 175 if (oip->ip_off & ~(IP_MF|IP_DF)) 176 goto freeit; 177 if (n->m_flags & (M_BCAST|M_MCAST)) 178 goto freeit; 179 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 180 n->m_len >= oiphlen + ICMP_MINLEN && 181 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 182 icmpstat.icps_oldicmp++; 183 goto freeit; 184 } 185 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 186 if (oiphlen + 8 > n->m_len) 187 goto freeit; 188 /* 189 * Calculate length to quote from original packet and 190 * prevent the ICMP mbuf from overflowing. 191 * Unfortunatly this is non-trivial since ip_forward() 192 * sends us truncated packets. 193 */ 194 nlen = m_length(n, NULL); 195 if (oip->ip_p == IPPROTO_TCP) { 196 struct tcphdr *th; 197 int tcphlen; 198 199 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 200 n->m_next == NULL) 201 goto stdreply; 202 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 203 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 204 goto freeit; 205 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 206 tcphlen = th->th_off << 2; 207 if (tcphlen < sizeof(struct tcphdr)) 208 goto freeit; 209 if (oip->ip_len < oiphlen + tcphlen) 210 goto freeit; 211 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 212 goto stdreply; 213 if (n->m_len < oiphlen + tcphlen && 214 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 215 goto freeit; 216 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen)); 217 } else 218 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen)); 219 220 icmplen = min(oiphlen + icmpelen, nlen); 221 if (icmplen < sizeof(struct ip)) 222 goto freeit; 223 224 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 225 m = m_gethdr(M_DONTWAIT, MT_DATA); 226 else 227 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 228 if (m == NULL) 229 goto freeit; 230 #ifdef MAC 231 mac_create_mbuf_netlayer(n, m); 232 #endif 233 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 234 m_align(m, ICMP_MINLEN + icmplen); 235 m->m_len = ICMP_MINLEN + icmplen; 236 237 icp = mtod(m, struct icmp *); 238 icmpstat.icps_outhist[type]++; 239 icp->icmp_type = type; 240 if (type == ICMP_REDIRECT) 241 icp->icmp_gwaddr.s_addr = dest; 242 else { 243 icp->icmp_void = 0; 244 /* 245 * The following assignments assume an overlay with the 246 * just zeroed icmp_void field. 247 */ 248 if (type == ICMP_PARAMPROB) { 249 icp->icmp_pptr = code; 250 code = 0; 251 } else if (type == ICMP_UNREACH && 252 code == ICMP_UNREACH_NEEDFRAG && mtu) { 253 icp->icmp_nextmtu = htons(mtu); 254 } 255 } 256 icp->icmp_code = code; 257 258 /* 259 * Copy the quotation into ICMP message and 260 * convert quoted IP header back to network representation. 261 */ 262 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 263 nip = &icp->icmp_ip; 264 nip->ip_len = htons(nip->ip_len); 265 nip->ip_off = htons(nip->ip_off); 266 267 /* 268 * Set up ICMP message mbuf and copy old IP header (without options 269 * in front of ICMP message. 270 * If the original mbuf was meant to bypass the firewall, the error 271 * reply should bypass as well. 272 */ 273 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 274 m->m_data -= sizeof(struct ip); 275 m->m_len += sizeof(struct ip); 276 m->m_pkthdr.len = m->m_len; 277 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 278 nip = mtod(m, struct ip *); 279 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 280 nip->ip_len = m->m_len; 281 nip->ip_v = IPVERSION; 282 nip->ip_hl = 5; 283 nip->ip_p = IPPROTO_ICMP; 284 nip->ip_tos = 0; 285 icmp_reflect(m); 286 287 freeit: 288 m_freem(n); 289 } 290 291 /* 292 * Process a received ICMP message. 293 */ 294 void 295 icmp_input(m, off) 296 struct mbuf *m; 297 int off; 298 { 299 struct icmp *icp; 300 struct in_ifaddr *ia; 301 struct ip *ip = mtod(m, struct ip *); 302 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 303 int hlen = off; 304 int icmplen = ip->ip_len; 305 int i, code; 306 void (*ctlfunc)(int, struct sockaddr *, void *); 307 308 /* 309 * Locate icmp structure in mbuf, and check 310 * that not corrupted and of at least minimum length. 311 */ 312 #ifdef ICMPPRINTFS 313 if (icmpprintfs) { 314 char buf[4 * sizeof "123"]; 315 strcpy(buf, inet_ntoa(ip->ip_src)); 316 printf("icmp_input from %s to %s, len %d\n", 317 buf, inet_ntoa(ip->ip_dst), icmplen); 318 } 319 #endif 320 if (icmplen < ICMP_MINLEN) { 321 icmpstat.icps_tooshort++; 322 goto freeit; 323 } 324 i = hlen + min(icmplen, ICMP_ADVLENMIN); 325 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 326 icmpstat.icps_tooshort++; 327 return; 328 } 329 ip = mtod(m, struct ip *); 330 m->m_len -= hlen; 331 m->m_data += hlen; 332 icp = mtod(m, struct icmp *); 333 if (in_cksum(m, icmplen)) { 334 icmpstat.icps_checksum++; 335 goto freeit; 336 } 337 m->m_len += hlen; 338 m->m_data -= hlen; 339 340 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 341 /* 342 * Deliver very specific ICMP type only. 343 */ 344 switch (icp->icmp_type) { 345 case ICMP_UNREACH: 346 case ICMP_TIMXCEED: 347 break; 348 default: 349 goto freeit; 350 } 351 } 352 353 #ifdef ICMPPRINTFS 354 if (icmpprintfs) 355 printf("icmp_input, type %d code %d\n", icp->icmp_type, 356 icp->icmp_code); 357 #endif 358 359 /* 360 * Message type specific processing. 361 */ 362 if (icp->icmp_type > ICMP_MAXTYPE) 363 goto raw; 364 365 /* Initialize */ 366 bzero(&icmpsrc, sizeof(icmpsrc)); 367 icmpsrc.sin_len = sizeof(struct sockaddr_in); 368 icmpsrc.sin_family = AF_INET; 369 bzero(&icmpdst, sizeof(icmpdst)); 370 icmpdst.sin_len = sizeof(struct sockaddr_in); 371 icmpdst.sin_family = AF_INET; 372 bzero(&icmpgw, sizeof(icmpgw)); 373 icmpgw.sin_len = sizeof(struct sockaddr_in); 374 icmpgw.sin_family = AF_INET; 375 376 icmpstat.icps_inhist[icp->icmp_type]++; 377 code = icp->icmp_code; 378 switch (icp->icmp_type) { 379 380 case ICMP_UNREACH: 381 switch (code) { 382 case ICMP_UNREACH_NET: 383 case ICMP_UNREACH_HOST: 384 case ICMP_UNREACH_SRCFAIL: 385 case ICMP_UNREACH_NET_UNKNOWN: 386 case ICMP_UNREACH_HOST_UNKNOWN: 387 case ICMP_UNREACH_ISOLATED: 388 case ICMP_UNREACH_TOSNET: 389 case ICMP_UNREACH_TOSHOST: 390 case ICMP_UNREACH_HOST_PRECEDENCE: 391 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 392 code = PRC_UNREACH_NET; 393 break; 394 395 case ICMP_UNREACH_NEEDFRAG: 396 code = PRC_MSGSIZE; 397 break; 398 399 /* 400 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 401 * Treat subcodes 2,3 as immediate RST 402 */ 403 case ICMP_UNREACH_PROTOCOL: 404 case ICMP_UNREACH_PORT: 405 code = PRC_UNREACH_PORT; 406 break; 407 408 case ICMP_UNREACH_NET_PROHIB: 409 case ICMP_UNREACH_HOST_PROHIB: 410 case ICMP_UNREACH_FILTER_PROHIB: 411 code = PRC_UNREACH_ADMIN_PROHIB; 412 break; 413 414 default: 415 goto badcode; 416 } 417 goto deliver; 418 419 case ICMP_TIMXCEED: 420 if (code > 1) 421 goto badcode; 422 code += PRC_TIMXCEED_INTRANS; 423 goto deliver; 424 425 case ICMP_PARAMPROB: 426 if (code > 1) 427 goto badcode; 428 code = PRC_PARAMPROB; 429 goto deliver; 430 431 case ICMP_SOURCEQUENCH: 432 if (code) 433 goto badcode; 434 code = PRC_QUENCH; 435 deliver: 436 /* 437 * Problem with datagram; advise higher level routines. 438 */ 439 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 440 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 441 icmpstat.icps_badlen++; 442 goto freeit; 443 } 444 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 445 /* Discard ICMP's in response to multicast packets */ 446 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 447 goto badcode; 448 #ifdef ICMPPRINTFS 449 if (icmpprintfs) 450 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 451 #endif 452 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 453 /* 454 * XXX if the packet contains [IPv4 AH TCP], we can't make a 455 * notification to TCP layer. 456 */ 457 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 458 if (ctlfunc) 459 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 460 (void *)&icp->icmp_ip); 461 break; 462 463 badcode: 464 icmpstat.icps_badcode++; 465 break; 466 467 case ICMP_ECHO: 468 if (!icmpbmcastecho 469 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 470 icmpstat.icps_bmcastecho++; 471 break; 472 } 473 icp->icmp_type = ICMP_ECHOREPLY; 474 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 475 goto freeit; 476 else 477 goto reflect; 478 479 case ICMP_TSTAMP: 480 if (!icmpbmcastecho 481 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 482 icmpstat.icps_bmcasttstamp++; 483 break; 484 } 485 if (icmplen < ICMP_TSLEN) { 486 icmpstat.icps_badlen++; 487 break; 488 } 489 icp->icmp_type = ICMP_TSTAMPREPLY; 490 icp->icmp_rtime = iptime(); 491 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 492 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 493 goto freeit; 494 else 495 goto reflect; 496 497 case ICMP_MASKREQ: 498 if (icmpmaskrepl == 0) 499 break; 500 /* 501 * We are not able to respond with all ones broadcast 502 * unless we receive it over a point-to-point interface. 503 */ 504 if (icmplen < ICMP_MASKLEN) 505 break; 506 switch (ip->ip_dst.s_addr) { 507 508 case INADDR_BROADCAST: 509 case INADDR_ANY: 510 icmpdst.sin_addr = ip->ip_src; 511 break; 512 513 default: 514 icmpdst.sin_addr = ip->ip_dst; 515 } 516 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 517 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 518 if (ia == 0) 519 break; 520 if (ia->ia_ifp == 0) 521 break; 522 icp->icmp_type = ICMP_MASKREPLY; 523 if (icmpmaskfake == 0) 524 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 525 else 526 icp->icmp_mask = icmpmaskfake; 527 if (ip->ip_src.s_addr == 0) { 528 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 529 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 530 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 531 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 532 } 533 reflect: 534 ip->ip_len += hlen; /* since ip_input deducts this */ 535 icmpstat.icps_reflect++; 536 icmpstat.icps_outhist[icp->icmp_type]++; 537 icmp_reflect(m); 538 return; 539 540 case ICMP_REDIRECT: 541 if (log_redirect) { 542 u_long src, dst, gw; 543 544 src = ntohl(ip->ip_src.s_addr); 545 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 546 gw = ntohl(icp->icmp_gwaddr.s_addr); 547 printf("icmp redirect from %d.%d.%d.%d: " 548 "%d.%d.%d.%d => %d.%d.%d.%d\n", 549 (int)(src >> 24), (int)((src >> 16) & 0xff), 550 (int)((src >> 8) & 0xff), (int)(src & 0xff), 551 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 552 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 553 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 554 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 555 } 556 /* 557 * RFC1812 says we must ignore ICMP redirects if we 558 * are acting as router. 559 */ 560 if (drop_redirect || ipforwarding) 561 break; 562 if (code > 3) 563 goto badcode; 564 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 565 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 566 icmpstat.icps_badlen++; 567 break; 568 } 569 /* 570 * Short circuit routing redirects to force 571 * immediate change in the kernel's routing 572 * tables. The message is also handed to anyone 573 * listening on a raw socket (e.g. the routing 574 * daemon for use in updating its tables). 575 */ 576 icmpgw.sin_addr = ip->ip_src; 577 icmpdst.sin_addr = icp->icmp_gwaddr; 578 #ifdef ICMPPRINTFS 579 if (icmpprintfs) { 580 char buf[4 * sizeof "123"]; 581 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 582 583 printf("redirect dst %s to %s\n", 584 buf, inet_ntoa(icp->icmp_gwaddr)); 585 } 586 #endif 587 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 588 rtredirect((struct sockaddr *)&icmpsrc, 589 (struct sockaddr *)&icmpdst, 590 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 591 (struct sockaddr *)&icmpgw); 592 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 593 #ifdef IPSEC 594 key_sa_routechange((struct sockaddr *)&icmpsrc); 595 #endif 596 break; 597 598 /* 599 * No kernel processing for the following; 600 * just fall through to send to raw listener. 601 */ 602 case ICMP_ECHOREPLY: 603 case ICMP_ROUTERADVERT: 604 case ICMP_ROUTERSOLICIT: 605 case ICMP_TSTAMPREPLY: 606 case ICMP_IREQREPLY: 607 case ICMP_MASKREPLY: 608 default: 609 break; 610 } 611 612 raw: 613 rip_input(m, off); 614 return; 615 616 freeit: 617 m_freem(m); 618 } 619 620 /* 621 * Reflect the ip packet back to the source 622 */ 623 static void 624 icmp_reflect(m) 625 struct mbuf *m; 626 { 627 struct ip *ip = mtod(m, struct ip *); 628 struct ifaddr *ifa; 629 struct ifnet *ifn; 630 struct in_ifaddr *ia; 631 struct in_addr t; 632 struct mbuf *opts = 0; 633 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 634 635 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 636 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 637 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 638 m_freem(m); /* Bad return address */ 639 icmpstat.icps_badaddr++; 640 goto done; /* Ip_output() will check for broadcast */ 641 } 642 643 t = ip->ip_dst; 644 ip->ip_dst = ip->ip_src; 645 646 /* 647 * Source selection for ICMP replies: 648 * 649 * If the incoming packet was addressed directly to one of our 650 * own addresses, use dst as the src for the reply. 651 */ 652 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 653 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 654 goto match; 655 /* 656 * If the incoming packet was addressed to one of our broadcast 657 * addresses, use the first non-broadcast address which corresponds 658 * to the incoming interface. 659 */ 660 if (m->m_pkthdr.rcvif != NULL && 661 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 662 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 663 if (ifa->ifa_addr->sa_family != AF_INET) 664 continue; 665 ia = ifatoia(ifa); 666 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 667 t.s_addr) 668 goto match; 669 } 670 } 671 /* 672 * If the packet was transiting through us, use the address of 673 * the interface the packet came through in. If that interface 674 * doesn't have a suitable IP address, the normal selection 675 * criteria apply. 676 */ 677 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 678 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 679 if (ifa->ifa_addr->sa_family != AF_INET) 680 continue; 681 ia = ifatoia(ifa); 682 goto match; 683 } 684 } 685 /* 686 * If the incoming packet was not addressed directly to us, use 687 * designated interface for icmp replies specified by sysctl 688 * net.inet.icmp.reply_src (default not set). Otherwise continue 689 * with normal source selection. 690 */ 691 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 692 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 693 if (ifa->ifa_addr->sa_family != AF_INET) 694 continue; 695 ia = ifatoia(ifa); 696 goto match; 697 } 698 } 699 /* 700 * If the packet was transiting through us, use the address of 701 * the interface that is the closest to the packet source. 702 * When we don't have a route back to the packet source, stop here 703 * and drop the packet. 704 */ 705 ia = ip_rtaddr(ip->ip_dst); 706 if (ia == NULL) { 707 m_freem(m); 708 icmpstat.icps_noroute++; 709 goto done; 710 } 711 match: 712 #ifdef MAC 713 mac_reflect_mbuf_icmp(m); 714 #endif 715 t = IA_SIN(ia)->sin_addr; 716 ip->ip_src = t; 717 ip->ip_ttl = ip_defttl; 718 719 if (optlen > 0) { 720 register u_char *cp; 721 int opt, cnt; 722 u_int len; 723 724 /* 725 * Retrieve any source routing from the incoming packet; 726 * add on any record-route or timestamp options. 727 */ 728 cp = (u_char *) (ip + 1); 729 if ((opts = ip_srcroute(m)) == 0 && 730 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 731 opts->m_len = sizeof(struct in_addr); 732 mtod(opts, struct in_addr *)->s_addr = 0; 733 } 734 if (opts) { 735 #ifdef ICMPPRINTFS 736 if (icmpprintfs) 737 printf("icmp_reflect optlen %d rt %d => ", 738 optlen, opts->m_len); 739 #endif 740 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 741 opt = cp[IPOPT_OPTVAL]; 742 if (opt == IPOPT_EOL) 743 break; 744 if (opt == IPOPT_NOP) 745 len = 1; 746 else { 747 if (cnt < IPOPT_OLEN + sizeof(*cp)) 748 break; 749 len = cp[IPOPT_OLEN]; 750 if (len < IPOPT_OLEN + sizeof(*cp) || 751 len > cnt) 752 break; 753 } 754 /* 755 * Should check for overflow, but it "can't happen" 756 */ 757 if (opt == IPOPT_RR || opt == IPOPT_TS || 758 opt == IPOPT_SECURITY) { 759 bcopy((caddr_t)cp, 760 mtod(opts, caddr_t) + opts->m_len, len); 761 opts->m_len += len; 762 } 763 } 764 /* Terminate & pad, if necessary */ 765 cnt = opts->m_len % 4; 766 if (cnt) { 767 for (; cnt < 4; cnt++) { 768 *(mtod(opts, caddr_t) + opts->m_len) = 769 IPOPT_EOL; 770 opts->m_len++; 771 } 772 } 773 #ifdef ICMPPRINTFS 774 if (icmpprintfs) 775 printf("%d\n", opts->m_len); 776 #endif 777 } 778 /* 779 * Now strip out original options by copying rest of first 780 * mbuf's data back, and adjust the IP length. 781 */ 782 ip->ip_len -= optlen; 783 ip->ip_v = IPVERSION; 784 ip->ip_hl = 5; 785 m->m_len -= optlen; 786 if (m->m_flags & M_PKTHDR) 787 m->m_pkthdr.len -= optlen; 788 optlen += sizeof(struct ip); 789 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 790 (unsigned)(m->m_len - sizeof(struct ip))); 791 } 792 m_tag_delete_nonpersistent(m); 793 m->m_flags &= ~(M_BCAST|M_MCAST); 794 icmp_send(m, opts); 795 done: 796 if (opts) 797 (void)m_free(opts); 798 } 799 800 /* 801 * Send an icmp packet back to the ip level, 802 * after supplying a checksum. 803 */ 804 static void 805 icmp_send(m, opts) 806 register struct mbuf *m; 807 struct mbuf *opts; 808 { 809 register struct ip *ip = mtod(m, struct ip *); 810 register int hlen; 811 register struct icmp *icp; 812 813 hlen = ip->ip_hl << 2; 814 m->m_data += hlen; 815 m->m_len -= hlen; 816 icp = mtod(m, struct icmp *); 817 icp->icmp_cksum = 0; 818 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 819 m->m_data -= hlen; 820 m->m_len += hlen; 821 m->m_pkthdr.rcvif = (struct ifnet *)0; 822 #ifdef ICMPPRINTFS 823 if (icmpprintfs) { 824 char buf[4 * sizeof "123"]; 825 strcpy(buf, inet_ntoa(ip->ip_dst)); 826 printf("icmp_send dst %s src %s\n", 827 buf, inet_ntoa(ip->ip_src)); 828 } 829 #endif 830 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 831 } 832 833 n_time 834 iptime() 835 { 836 struct timeval atv; 837 u_long t; 838 839 getmicrotime(&atv); 840 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 841 return (htonl(t)); 842 } 843 844 /* 845 * Return the next larger or smaller MTU plateau (table from RFC 1191) 846 * given current value MTU. If DIR is less than zero, a larger plateau 847 * is returned; otherwise, a smaller value is returned. 848 */ 849 int 850 ip_next_mtu(mtu, dir) 851 int mtu; 852 int dir; 853 { 854 static int mtutab[] = { 855 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 856 296, 68, 0 857 }; 858 int i, size; 859 860 size = (sizeof mtutab) / (sizeof mtutab[0]); 861 if (dir >= 0) { 862 for (i = 0; i < size; i++) 863 if (mtu > mtutab[i]) 864 return mtutab[i]; 865 } else { 866 for (i = size - 1; i >= 0; i--) 867 if (mtu < mtutab[i]) 868 return mtutab[i]; 869 if (mtu == mtutab[0]) 870 return mtutab[0]; 871 } 872 return 0; 873 } 874 875 876 /* 877 * badport_bandlim() - check for ICMP bandwidth limit 878 * 879 * Return 0 if it is ok to send an ICMP error response, -1 if we have 880 * hit our bandwidth limit and it is not ok. 881 * 882 * If icmplim is <= 0, the feature is disabled and 0 is returned. 883 * 884 * For now we separate the TCP and UDP subsystems w/ different 'which' 885 * values. We may eventually remove this separation (and simplify the 886 * code further). 887 * 888 * Note that the printing of the error message is delayed so we can 889 * properly print the icmp error rate that the system was trying to do 890 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 891 * the 'final' error, but it doesn't make sense to solve the printing 892 * delay with more complex code. 893 */ 894 895 int 896 badport_bandlim(int which) 897 { 898 #define N(a) (sizeof (a) / sizeof (a[0])) 899 static struct rate { 900 const char *type; 901 struct timeval lasttime; 902 int curpps; 903 } rates[BANDLIM_MAX+1] = { 904 { "icmp unreach response" }, 905 { "icmp ping response" }, 906 { "icmp tstamp response" }, 907 { "closed port RST response" }, 908 { "open port RST response" } 909 }; 910 911 /* 912 * Return ok status if feature disabled or argument out of range. 913 */ 914 if (icmplim > 0 && (u_int) which < N(rates)) { 915 struct rate *r = &rates[which]; 916 int opps = r->curpps; 917 918 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 919 return -1; /* discard packet */ 920 /* 921 * If we've dropped below the threshold after having 922 * rate-limited traffic print the message. This preserves 923 * the previous behaviour at the expense of added complexity. 924 */ 925 if (icmplim_output && opps > icmplim) 926 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 927 r->type, opps, icmplim); 928 } 929 return 0; /* okay to send packet */ 930 #undef N 931 }
Cache object: d2da9d90197c42face9ed683f5878792
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