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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: releng/6.2/sys/netinet/ip_icmp.c 155762 2006-02-16 17:50:57Z andre $ 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 46 #include <net/if.h> 47 #include <net/if_types.h> 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_pcb.h> 52 #include <netinet/in_systm.h> 53 #include <netinet/in_var.h> 54 #include <netinet/ip.h> 55 #include <netinet/ip_icmp.h> 56 #include <netinet/ip_var.h> 57 #include <netinet/tcp.h> 58 #include <netinet/tcp_var.h> 59 #include <netinet/tcpip.h> 60 #include <netinet/icmp_var.h> 61 62 #ifdef IPSEC 63 #include <netinet6/ipsec.h> 64 #include <netkey/key.h> 65 #endif 66 67 #ifdef FAST_IPSEC 68 #include <netipsec/ipsec.h> 69 #include <netipsec/key.h> 70 #define IPSEC 71 #endif 72 73 #include <machine/in_cksum.h> 74 75 /* 76 * ICMP routines: error generation, receive packet processing, and 77 * routines to turnaround packets back to the originator, and 78 * host table maintenance routines. 79 */ 80 81 struct icmpstat icmpstat; 82 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 83 &icmpstat, icmpstat, ""); 84 85 static int icmpmaskrepl = 0; 86 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 87 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 88 89 static u_int icmpmaskfake = 0; 90 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 91 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 92 93 static int drop_redirect = 0; 94 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 95 &drop_redirect, 0, ""); 96 97 static int log_redirect = 0; 98 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 99 &log_redirect, 0, ""); 100 101 static int icmplim = 200; 102 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 103 &icmplim, 0, ""); 104 105 static int icmplim_output = 1; 106 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 107 &icmplim_output, 0, ""); 108 109 static char reply_src[IFNAMSIZ]; 110 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 111 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 112 113 static int icmp_rfi = 0; 114 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 115 &icmp_rfi, 0, "ICMP reply from incoming interface for " 116 "non-local packets"); 117 118 static int icmp_quotelen = 8; 119 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 120 &icmp_quotelen, 0, "Number of bytes from original packet to " 121 "quote in ICMP reply"); 122 123 /* 124 * ICMP broadcast echo sysctl 125 */ 126 127 static int icmpbmcastecho = 0; 128 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 129 &icmpbmcastecho, 0, ""); 130 131 132 #ifdef ICMPPRINTFS 133 int icmpprintfs = 0; 134 #endif 135 136 static void icmp_reflect(struct mbuf *); 137 static void icmp_send(struct mbuf *, struct mbuf *); 138 139 extern struct protosw inetsw[]; 140 141 /* 142 * Generate an error packet of type error 143 * in response to bad packet ip. 144 */ 145 void 146 icmp_error(n, type, code, dest, mtu) 147 struct mbuf *n; 148 int type, code; 149 n_long dest; 150 int mtu; 151 { 152 register struct ip *oip = mtod(n, struct ip *), *nip; 153 register unsigned oiphlen = oip->ip_hl << 2; 154 register struct icmp *icp; 155 register struct mbuf *m; 156 unsigned icmplen, icmpelen, nlen; 157 158 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 159 #ifdef ICMPPRINTFS 160 if (icmpprintfs) 161 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 162 #endif 163 if (type != ICMP_REDIRECT) 164 icmpstat.icps_error++; 165 /* 166 * Don't send error: 167 * if the original packet was encrypted. 168 * if not the first fragment of message. 169 * in response to a multicast or broadcast packet. 170 * if the old packet protocol was an ICMP error message. 171 */ 172 if (n->m_flags & M_DECRYPTED) 173 goto freeit; 174 if (oip->ip_off & ~(IP_MF|IP_DF)) 175 goto freeit; 176 if (n->m_flags & (M_BCAST|M_MCAST)) 177 goto freeit; 178 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 179 n->m_len >= oiphlen + ICMP_MINLEN && 180 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 181 icmpstat.icps_oldicmp++; 182 goto freeit; 183 } 184 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 185 if (oiphlen + 8 > n->m_len) 186 goto freeit; 187 /* 188 * Calculate length to quote from original packet and 189 * prevent the ICMP mbuf from overflowing. 190 * Unfortunatly this is non-trivial since ip_forward() 191 * sends us truncated packets. 192 */ 193 nlen = m_length(n, NULL); 194 if (oip->ip_p == IPPROTO_TCP) { 195 struct tcphdr *th; 196 int tcphlen; 197 198 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 199 n->m_next == NULL) 200 goto stdreply; 201 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 202 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 203 goto freeit; 204 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 205 tcphlen = th->th_off << 2; 206 if (tcphlen < sizeof(struct tcphdr)) 207 goto freeit; 208 if (oip->ip_len < oiphlen + tcphlen) 209 goto freeit; 210 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 211 goto stdreply; 212 if (n->m_len < oiphlen + tcphlen && 213 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 214 goto freeit; 215 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen)); 216 } else 217 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen)); 218 219 icmplen = min(oiphlen + icmpelen, nlen); 220 if (icmplen < sizeof(struct ip)) 221 goto freeit; 222 223 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 224 m = m_gethdr(M_DONTWAIT, MT_DATA); 225 else 226 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 227 if (m == NULL) 228 goto freeit; 229 #ifdef MAC 230 mac_create_mbuf_netlayer(n, m); 231 #endif 232 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 233 m_align(m, ICMP_MINLEN + icmplen); 234 m->m_len = ICMP_MINLEN + icmplen; 235 236 icp = mtod(m, struct icmp *); 237 icmpstat.icps_outhist[type]++; 238 icp->icmp_type = type; 239 if (type == ICMP_REDIRECT) 240 icp->icmp_gwaddr.s_addr = dest; 241 else { 242 icp->icmp_void = 0; 243 /* 244 * The following assignments assume an overlay with the 245 * just zeroed icmp_void field. 246 */ 247 if (type == ICMP_PARAMPROB) { 248 icp->icmp_pptr = code; 249 code = 0; 250 } else if (type == ICMP_UNREACH && 251 code == ICMP_UNREACH_NEEDFRAG && mtu) { 252 icp->icmp_nextmtu = htons(mtu); 253 } 254 } 255 icp->icmp_code = code; 256 257 /* 258 * Copy the quotation into ICMP message and 259 * convert quoted IP header back to network representation. 260 */ 261 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 262 nip = &icp->icmp_ip; 263 nip->ip_len = htons(nip->ip_len); 264 nip->ip_off = htons(nip->ip_off); 265 266 /* 267 * Set up ICMP message mbuf and copy old IP header (without options 268 * in front of ICMP message. 269 * If the original mbuf was meant to bypass the firewall, the error 270 * reply should bypass as well. 271 */ 272 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 273 m->m_data -= sizeof(struct ip); 274 m->m_len += sizeof(struct ip); 275 m->m_pkthdr.len = m->m_len; 276 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 277 nip = mtod(m, struct ip *); 278 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 279 nip->ip_len = m->m_len; 280 nip->ip_v = IPVERSION; 281 nip->ip_hl = 5; 282 nip->ip_p = IPPROTO_ICMP; 283 nip->ip_tos = 0; 284 icmp_reflect(m); 285 286 freeit: 287 m_freem(n); 288 } 289 290 /* 291 * Process a received ICMP message. 292 */ 293 void 294 icmp_input(m, off) 295 struct mbuf *m; 296 int off; 297 { 298 struct icmp *icp; 299 struct in_ifaddr *ia; 300 struct ip *ip = mtod(m, struct ip *); 301 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 302 int hlen = off; 303 int icmplen = ip->ip_len; 304 int i, code; 305 void (*ctlfunc)(int, struct sockaddr *, void *); 306 307 /* 308 * Locate icmp structure in mbuf, and check 309 * that not corrupted and of at least minimum length. 310 */ 311 #ifdef ICMPPRINTFS 312 if (icmpprintfs) { 313 char buf[4 * sizeof "123"]; 314 strcpy(buf, inet_ntoa(ip->ip_src)); 315 printf("icmp_input from %s to %s, len %d\n", 316 buf, inet_ntoa(ip->ip_dst), icmplen); 317 } 318 #endif 319 if (icmplen < ICMP_MINLEN) { 320 icmpstat.icps_tooshort++; 321 goto freeit; 322 } 323 i = hlen + min(icmplen, ICMP_ADVLENMIN); 324 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 325 icmpstat.icps_tooshort++; 326 return; 327 } 328 ip = mtod(m, struct ip *); 329 m->m_len -= hlen; 330 m->m_data += hlen; 331 icp = mtod(m, struct icmp *); 332 if (in_cksum(m, icmplen)) { 333 icmpstat.icps_checksum++; 334 goto freeit; 335 } 336 m->m_len += hlen; 337 m->m_data -= hlen; 338 339 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 340 /* 341 * Deliver very specific ICMP type only. 342 */ 343 switch (icp->icmp_type) { 344 case ICMP_UNREACH: 345 case ICMP_TIMXCEED: 346 break; 347 default: 348 goto freeit; 349 } 350 } 351 352 #ifdef ICMPPRINTFS 353 if (icmpprintfs) 354 printf("icmp_input, type %d code %d\n", icp->icmp_type, 355 icp->icmp_code); 356 #endif 357 358 /* 359 * Message type specific processing. 360 */ 361 if (icp->icmp_type > ICMP_MAXTYPE) 362 goto raw; 363 364 /* Initialize */ 365 bzero(&icmpsrc, sizeof(icmpsrc)); 366 icmpsrc.sin_len = sizeof(struct sockaddr_in); 367 icmpsrc.sin_family = AF_INET; 368 bzero(&icmpdst, sizeof(icmpdst)); 369 icmpdst.sin_len = sizeof(struct sockaddr_in); 370 icmpdst.sin_family = AF_INET; 371 bzero(&icmpgw, sizeof(icmpgw)); 372 icmpgw.sin_len = sizeof(struct sockaddr_in); 373 icmpgw.sin_family = AF_INET; 374 375 icmpstat.icps_inhist[icp->icmp_type]++; 376 code = icp->icmp_code; 377 switch (icp->icmp_type) { 378 379 case ICMP_UNREACH: 380 switch (code) { 381 case ICMP_UNREACH_NET: 382 case ICMP_UNREACH_HOST: 383 case ICMP_UNREACH_SRCFAIL: 384 case ICMP_UNREACH_NET_UNKNOWN: 385 case ICMP_UNREACH_HOST_UNKNOWN: 386 case ICMP_UNREACH_ISOLATED: 387 case ICMP_UNREACH_TOSNET: 388 case ICMP_UNREACH_TOSHOST: 389 case ICMP_UNREACH_HOST_PRECEDENCE: 390 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 391 code = PRC_UNREACH_NET; 392 break; 393 394 case ICMP_UNREACH_NEEDFRAG: 395 code = PRC_MSGSIZE; 396 break; 397 398 /* 399 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 400 * Treat subcodes 2,3 as immediate RST 401 */ 402 case ICMP_UNREACH_PROTOCOL: 403 case ICMP_UNREACH_PORT: 404 code = PRC_UNREACH_PORT; 405 break; 406 407 case ICMP_UNREACH_NET_PROHIB: 408 case ICMP_UNREACH_HOST_PROHIB: 409 case ICMP_UNREACH_FILTER_PROHIB: 410 code = PRC_UNREACH_ADMIN_PROHIB; 411 break; 412 413 default: 414 goto badcode; 415 } 416 goto deliver; 417 418 case ICMP_TIMXCEED: 419 if (code > 1) 420 goto badcode; 421 code += PRC_TIMXCEED_INTRANS; 422 goto deliver; 423 424 case ICMP_PARAMPROB: 425 if (code > 1) 426 goto badcode; 427 code = PRC_PARAMPROB; 428 goto deliver; 429 430 case ICMP_SOURCEQUENCH: 431 if (code) 432 goto badcode; 433 code = PRC_QUENCH; 434 deliver: 435 /* 436 * Problem with datagram; advise higher level routines. 437 */ 438 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 439 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 440 icmpstat.icps_badlen++; 441 goto freeit; 442 } 443 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 444 /* Discard ICMP's in response to multicast packets */ 445 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 446 goto badcode; 447 #ifdef ICMPPRINTFS 448 if (icmpprintfs) 449 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 450 #endif 451 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 452 /* 453 * XXX if the packet contains [IPv4 AH TCP], we can't make a 454 * notification to TCP layer. 455 */ 456 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 457 if (ctlfunc) 458 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 459 (void *)&icp->icmp_ip); 460 break; 461 462 badcode: 463 icmpstat.icps_badcode++; 464 break; 465 466 case ICMP_ECHO: 467 if (!icmpbmcastecho 468 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 469 icmpstat.icps_bmcastecho++; 470 break; 471 } 472 icp->icmp_type = ICMP_ECHOREPLY; 473 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 474 goto freeit; 475 else 476 goto reflect; 477 478 case ICMP_TSTAMP: 479 if (!icmpbmcastecho 480 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 481 icmpstat.icps_bmcasttstamp++; 482 break; 483 } 484 if (icmplen < ICMP_TSLEN) { 485 icmpstat.icps_badlen++; 486 break; 487 } 488 icp->icmp_type = ICMP_TSTAMPREPLY; 489 icp->icmp_rtime = iptime(); 490 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 491 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 492 goto freeit; 493 else 494 goto reflect; 495 496 case ICMP_MASKREQ: 497 if (icmpmaskrepl == 0) 498 break; 499 /* 500 * We are not able to respond with all ones broadcast 501 * unless we receive it over a point-to-point interface. 502 */ 503 if (icmplen < ICMP_MASKLEN) 504 break; 505 switch (ip->ip_dst.s_addr) { 506 507 case INADDR_BROADCAST: 508 case INADDR_ANY: 509 icmpdst.sin_addr = ip->ip_src; 510 break; 511 512 default: 513 icmpdst.sin_addr = ip->ip_dst; 514 } 515 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 516 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 517 if (ia == 0) 518 break; 519 if (ia->ia_ifp == 0) 520 break; 521 icp->icmp_type = ICMP_MASKREPLY; 522 if (icmpmaskfake == 0) 523 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 524 else 525 icp->icmp_mask = icmpmaskfake; 526 if (ip->ip_src.s_addr == 0) { 527 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 528 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 529 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 530 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 531 } 532 reflect: 533 ip->ip_len += hlen; /* since ip_input deducts this */ 534 icmpstat.icps_reflect++; 535 icmpstat.icps_outhist[icp->icmp_type]++; 536 icmp_reflect(m); 537 return; 538 539 case ICMP_REDIRECT: 540 if (log_redirect) { 541 u_long src, dst, gw; 542 543 src = ntohl(ip->ip_src.s_addr); 544 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 545 gw = ntohl(icp->icmp_gwaddr.s_addr); 546 printf("icmp redirect from %d.%d.%d.%d: " 547 "%d.%d.%d.%d => %d.%d.%d.%d\n", 548 (int)(src >> 24), (int)((src >> 16) & 0xff), 549 (int)((src >> 8) & 0xff), (int)(src & 0xff), 550 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 551 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 552 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 553 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 554 } 555 /* 556 * RFC1812 says we must ignore ICMP redirects if we 557 * are acting as router. 558 */ 559 if (drop_redirect || ipforwarding) 560 break; 561 if (code > 3) 562 goto badcode; 563 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 564 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 565 icmpstat.icps_badlen++; 566 break; 567 } 568 /* 569 * Short circuit routing redirects to force 570 * immediate change in the kernel's routing 571 * tables. The message is also handed to anyone 572 * listening on a raw socket (e.g. the routing 573 * daemon for use in updating its tables). 574 */ 575 icmpgw.sin_addr = ip->ip_src; 576 icmpdst.sin_addr = icp->icmp_gwaddr; 577 #ifdef ICMPPRINTFS 578 if (icmpprintfs) { 579 char buf[4 * sizeof "123"]; 580 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 581 582 printf("redirect dst %s to %s\n", 583 buf, inet_ntoa(icp->icmp_gwaddr)); 584 } 585 #endif 586 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 587 rtredirect((struct sockaddr *)&icmpsrc, 588 (struct sockaddr *)&icmpdst, 589 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 590 (struct sockaddr *)&icmpgw); 591 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 592 #ifdef IPSEC 593 key_sa_routechange((struct sockaddr *)&icmpsrc); 594 #endif 595 break; 596 597 /* 598 * No kernel processing for the following; 599 * just fall through to send to raw listener. 600 */ 601 case ICMP_ECHOREPLY: 602 case ICMP_ROUTERADVERT: 603 case ICMP_ROUTERSOLICIT: 604 case ICMP_TSTAMPREPLY: 605 case ICMP_IREQREPLY: 606 case ICMP_MASKREPLY: 607 default: 608 break; 609 } 610 611 raw: 612 rip_input(m, off); 613 return; 614 615 freeit: 616 m_freem(m); 617 } 618 619 /* 620 * Reflect the ip packet back to the source 621 */ 622 static void 623 icmp_reflect(m) 624 struct mbuf *m; 625 { 626 struct ip *ip = mtod(m, struct ip *); 627 struct ifaddr *ifa; 628 struct ifnet *ifn; 629 struct in_ifaddr *ia; 630 struct in_addr t; 631 struct mbuf *opts = 0; 632 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 633 634 if (!in_canforward(ip->ip_src) && 635 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 636 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 637 m_freem(m); /* Bad return address */ 638 icmpstat.icps_badaddr++; 639 goto done; /* Ip_output() will check for broadcast */ 640 } 641 t = ip->ip_dst; 642 ip->ip_dst = ip->ip_src; 643 644 /* 645 * Source selection for ICMP replies: 646 * 647 * If the incoming packet was addressed directly to one of our 648 * own addresses, use dst as the src for the reply. 649 */ 650 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 651 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 652 goto match; 653 /* 654 * If the incoming packet was addressed to one of our broadcast 655 * addresses, use the first non-broadcast address which corresponds 656 * to the incoming interface. 657 */ 658 if (m->m_pkthdr.rcvif != NULL && 659 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 660 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 661 if (ifa->ifa_addr->sa_family != AF_INET) 662 continue; 663 ia = ifatoia(ifa); 664 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 665 t.s_addr) 666 goto match; 667 } 668 } 669 /* 670 * If the packet was transiting through us, use the address of 671 * the interface the packet came through in. If that interface 672 * doesn't have a suitable IP address, the normal selection 673 * criteria apply. 674 */ 675 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 676 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 677 if (ifa->ifa_addr->sa_family != AF_INET) 678 continue; 679 ia = ifatoia(ifa); 680 goto match; 681 } 682 } 683 /* 684 * If the incoming packet was not addressed directly to us, use 685 * designated interface for icmp replies specified by sysctl 686 * net.inet.icmp.reply_src (default not set). Otherwise continue 687 * with normal source selection. 688 */ 689 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 690 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 691 if (ifa->ifa_addr->sa_family != AF_INET) 692 continue; 693 ia = ifatoia(ifa); 694 goto match; 695 } 696 } 697 /* 698 * If the packet was transiting through us, use the address of 699 * the interface that is the closest to the packet source. 700 * When we don't have a route back to the packet source, stop here 701 * and drop the packet. 702 */ 703 ia = ip_rtaddr(ip->ip_dst); 704 if (ia == NULL) { 705 m_freem(m); 706 icmpstat.icps_noroute++; 707 goto done; 708 } 709 match: 710 #ifdef MAC 711 mac_reflect_mbuf_icmp(m); 712 #endif 713 t = IA_SIN(ia)->sin_addr; 714 ip->ip_src = t; 715 ip->ip_ttl = ip_defttl; 716 717 if (optlen > 0) { 718 register u_char *cp; 719 int opt, cnt; 720 u_int len; 721 722 /* 723 * Retrieve any source routing from the incoming packet; 724 * add on any record-route or timestamp options. 725 */ 726 cp = (u_char *) (ip + 1); 727 if ((opts = ip_srcroute(m)) == 0 && 728 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 729 opts->m_len = sizeof(struct in_addr); 730 mtod(opts, struct in_addr *)->s_addr = 0; 731 } 732 if (opts) { 733 #ifdef ICMPPRINTFS 734 if (icmpprintfs) 735 printf("icmp_reflect optlen %d rt %d => ", 736 optlen, opts->m_len); 737 #endif 738 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 739 opt = cp[IPOPT_OPTVAL]; 740 if (opt == IPOPT_EOL) 741 break; 742 if (opt == IPOPT_NOP) 743 len = 1; 744 else { 745 if (cnt < IPOPT_OLEN + sizeof(*cp)) 746 break; 747 len = cp[IPOPT_OLEN]; 748 if (len < IPOPT_OLEN + sizeof(*cp) || 749 len > cnt) 750 break; 751 } 752 /* 753 * Should check for overflow, but it "can't happen" 754 */ 755 if (opt == IPOPT_RR || opt == IPOPT_TS || 756 opt == IPOPT_SECURITY) { 757 bcopy((caddr_t)cp, 758 mtod(opts, caddr_t) + opts->m_len, len); 759 opts->m_len += len; 760 } 761 } 762 /* Terminate & pad, if necessary */ 763 cnt = opts->m_len % 4; 764 if (cnt) { 765 for (; cnt < 4; cnt++) { 766 *(mtod(opts, caddr_t) + opts->m_len) = 767 IPOPT_EOL; 768 opts->m_len++; 769 } 770 } 771 #ifdef ICMPPRINTFS 772 if (icmpprintfs) 773 printf("%d\n", opts->m_len); 774 #endif 775 } 776 /* 777 * Now strip out original options by copying rest of first 778 * mbuf's data back, and adjust the IP length. 779 */ 780 ip->ip_len -= optlen; 781 ip->ip_v = IPVERSION; 782 ip->ip_hl = 5; 783 m->m_len -= optlen; 784 if (m->m_flags & M_PKTHDR) 785 m->m_pkthdr.len -= optlen; 786 optlen += sizeof(struct ip); 787 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 788 (unsigned)(m->m_len - sizeof(struct ip))); 789 } 790 m_tag_delete_nonpersistent(m); 791 m->m_flags &= ~(M_BCAST|M_MCAST); 792 icmp_send(m, opts); 793 done: 794 if (opts) 795 (void)m_free(opts); 796 } 797 798 /* 799 * Send an icmp packet back to the ip level, 800 * after supplying a checksum. 801 */ 802 static void 803 icmp_send(m, opts) 804 register struct mbuf *m; 805 struct mbuf *opts; 806 { 807 register struct ip *ip = mtod(m, struct ip *); 808 register int hlen; 809 register struct icmp *icp; 810 811 hlen = ip->ip_hl << 2; 812 m->m_data += hlen; 813 m->m_len -= hlen; 814 icp = mtod(m, struct icmp *); 815 icp->icmp_cksum = 0; 816 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 817 m->m_data -= hlen; 818 m->m_len += hlen; 819 m->m_pkthdr.rcvif = (struct ifnet *)0; 820 #ifdef ICMPPRINTFS 821 if (icmpprintfs) { 822 char buf[4 * sizeof "123"]; 823 strcpy(buf, inet_ntoa(ip->ip_dst)); 824 printf("icmp_send dst %s src %s\n", 825 buf, inet_ntoa(ip->ip_src)); 826 } 827 #endif 828 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 829 } 830 831 n_time 832 iptime() 833 { 834 struct timeval atv; 835 u_long t; 836 837 getmicrotime(&atv); 838 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 839 return (htonl(t)); 840 } 841 842 /* 843 * Return the next larger or smaller MTU plateau (table from RFC 1191) 844 * given current value MTU. If DIR is less than zero, a larger plateau 845 * is returned; otherwise, a smaller value is returned. 846 */ 847 int 848 ip_next_mtu(mtu, dir) 849 int mtu; 850 int dir; 851 { 852 static int mtutab[] = { 853 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 854 296, 68, 0 855 }; 856 int i, size; 857 858 size = (sizeof mtutab) / (sizeof mtutab[0]); 859 if (dir >= 0) { 860 for (i = 0; i < size; i++) 861 if (mtu > mtutab[i]) 862 return mtutab[i]; 863 } else { 864 for (i = size - 1; i >= 0; i--) 865 if (mtu < mtutab[i]) 866 return mtutab[i]; 867 if (mtu == mtutab[0]) 868 return mtutab[0]; 869 } 870 return 0; 871 } 872 873 874 /* 875 * badport_bandlim() - check for ICMP bandwidth limit 876 * 877 * Return 0 if it is ok to send an ICMP error response, -1 if we have 878 * hit our bandwidth limit and it is not ok. 879 * 880 * If icmplim is <= 0, the feature is disabled and 0 is returned. 881 * 882 * For now we separate the TCP and UDP subsystems w/ different 'which' 883 * values. We may eventually remove this separation (and simplify the 884 * code further). 885 * 886 * Note that the printing of the error message is delayed so we can 887 * properly print the icmp error rate that the system was trying to do 888 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 889 * the 'final' error, but it doesn't make sense to solve the printing 890 * delay with more complex code. 891 */ 892 893 int 894 badport_bandlim(int which) 895 { 896 #define N(a) (sizeof (a) / sizeof (a[0])) 897 static struct rate { 898 const char *type; 899 struct timeval lasttime; 900 int curpps; 901 } rates[BANDLIM_MAX+1] = { 902 { "icmp unreach response" }, 903 { "icmp ping response" }, 904 { "icmp tstamp response" }, 905 { "closed port RST response" }, 906 { "open port RST response" } 907 }; 908 909 /* 910 * Return ok status if feature disabled or argument out of range. 911 */ 912 if (icmplim > 0 && (u_int) which < N(rates)) { 913 struct rate *r = &rates[which]; 914 int opps = r->curpps; 915 916 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 917 return -1; /* discard packet */ 918 /* 919 * If we've dropped below the threshold after having 920 * rate-limited traffic print the message. This preserves 921 * the previous behaviour at the expense of added complexity. 922 */ 923 if (icmplim_output && opps > icmplim) 924 printf("Limiting %s from %d to %d packets/sec\n", 925 r->type, opps, icmplim); 926 } 927 return 0; /* okay to send packet */ 928 #undef N 929 }
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