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("$FreeBSD$"); 34 35 #include "opt_ipsec.h" 36 #include "opt_mac.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/mbuf.h> 41 #include <sys/protosw.h> 42 #include <sys/socket.h> 43 #include <sys/time.h> 44 #include <sys/kernel.h> 45 #include <sys/sysctl.h> 46 #include <sys/vimage.h> 47 48 #include <net/if.h> 49 #include <net/if_types.h> 50 #include <net/route.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 */ 79 80 struct icmpstat icmpstat; 81 SYSCTL_V_STRUCT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_STATS, stats, 82 CTLFLAG_RW, icmpstat, icmpstat, ""); 83 84 static int icmpmaskrepl = 0; 85 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, 86 CTLFLAG_RW, icmpmaskrepl, 0, 87 "Reply to ICMP Address Mask Request packets."); 88 89 static u_int icmpmaskfake = 0; 90 SYSCTL_V_UINT(V_NET, vnet_inet, _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_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, drop_redirect, 95 CTLFLAG_RW, drop_redirect, 0, "Ignore ICMP redirects"); 96 97 static int log_redirect = 0; 98 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, log_redirect, 99 CTLFLAG_RW, log_redirect, 0, "Log ICMP redirects to the console"); 100 101 static int icmplim = 200; 102 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, 103 CTLFLAG_RW, icmplim, 0, "Maximum number of ICMP responses per second"); 104 105 static int icmplim_output = 1; 106 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, icmplim_output, 107 CTLFLAG_RW, icmplim_output, 0, 108 "Enable rate limiting of ICMP responses"); 109 110 static char reply_src[IFNAMSIZ]; 111 SYSCTL_V_STRING(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_src, 112 CTLFLAG_RW, reply_src, IFNAMSIZ, 113 "icmp reply source for non-local packets."); 114 115 static int icmp_rfi = 0; 116 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_from_interface, 117 CTLFLAG_RW, icmp_rfi, 0, "ICMP reply from incoming interface for " 118 "non-local packets"); 119 120 static int icmp_quotelen = 8; 121 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 122 icmp_quotelen, 0, "Number of bytes from original packet to " 123 "quote in ICMP reply"); 124 125 /* 126 * ICMP broadcast echo sysctl 127 */ 128 129 static int icmpbmcastecho = 0; 130 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, bmcastecho, 131 CTLFLAG_RW, icmpbmcastecho, 0, ""); 132 133 134 #ifdef ICMPPRINTFS 135 int icmpprintfs = 0; 136 #endif 137 138 static void icmp_reflect(struct mbuf *); 139 static void icmp_send(struct mbuf *, struct mbuf *); 140 141 extern struct protosw inetsw[]; 142 143 /* 144 * Generate an error packet of type error 145 * in response to bad packet ip. 146 */ 147 void 148 icmp_error(struct mbuf *n, int type, int code, n_long dest, int mtu) 149 { 150 INIT_VNET_INET(curvnet); 151 register struct ip *oip = mtod(n, struct ip *), *nip; 152 register unsigned oiphlen = oip->ip_hl << 2; 153 register struct icmp *icp; 154 register struct mbuf *m; 155 unsigned icmplen, icmpelen, nlen; 156 157 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 158 #ifdef ICMPPRINTFS 159 if (icmpprintfs) 160 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 161 #endif 162 if (type != ICMP_REDIRECT) 163 V_icmpstat.icps_error++; 164 /* 165 * Don't send error: 166 * if the original packet was encrypted. 167 * if not the first fragment of message. 168 * in response to a multicast or broadcast packet. 169 * if the old packet protocol was an ICMP error message. 170 */ 171 if (n->m_flags & M_DECRYPTED) 172 goto freeit; 173 if (oip->ip_off & ~(IP_MF|IP_DF)) 174 goto freeit; 175 if (n->m_flags & (M_BCAST|M_MCAST)) 176 goto freeit; 177 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 178 n->m_len >= oiphlen + ICMP_MINLEN && 179 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 180 V_icmpstat.icps_oldicmp++; 181 goto freeit; 182 } 183 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 184 if (oiphlen + 8 > n->m_len) 185 goto freeit; 186 /* 187 * Calculate length to quote from original packet and 188 * prevent the ICMP mbuf from overflowing. 189 * Unfortunatly this is non-trivial since ip_forward() 190 * sends us truncated packets. 191 */ 192 nlen = m_length(n, NULL); 193 if (oip->ip_p == IPPROTO_TCP) { 194 struct tcphdr *th; 195 int tcphlen; 196 197 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 198 n->m_next == NULL) 199 goto stdreply; 200 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 201 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 202 goto freeit; 203 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 204 tcphlen = th->th_off << 2; 205 if (tcphlen < sizeof(struct tcphdr)) 206 goto freeit; 207 if (oip->ip_len < oiphlen + tcphlen) 208 goto freeit; 209 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 210 goto stdreply; 211 if (n->m_len < oiphlen + tcphlen && 212 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 213 goto freeit; 214 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 215 } else 216 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 217 218 icmplen = min(oiphlen + icmpelen, nlen); 219 if (icmplen < sizeof(struct ip)) 220 goto freeit; 221 222 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 223 m = m_gethdr(M_DONTWAIT, MT_DATA); 224 else 225 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 226 if (m == NULL) 227 goto freeit; 228 #ifdef MAC 229 mac_netinet_icmp_reply(n, m); 230 #endif 231 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 232 m_align(m, ICMP_MINLEN + icmplen); 233 m->m_len = ICMP_MINLEN + icmplen; 234 235 /* XXX MRT make the outgoing packet use the same FIB 236 * that was associated with the incoming packet 237 */ 238 M_SETFIB(m, M_GETFIB(n)); 239 icp = mtod(m, struct icmp *); 240 V_icmpstat.icps_outhist[type]++; 241 icp->icmp_type = type; 242 if (type == ICMP_REDIRECT) 243 icp->icmp_gwaddr.s_addr = dest; 244 else { 245 icp->icmp_void = 0; 246 /* 247 * The following assignments assume an overlay with the 248 * just zeroed icmp_void field. 249 */ 250 if (type == ICMP_PARAMPROB) { 251 icp->icmp_pptr = code; 252 code = 0; 253 } else if (type == ICMP_UNREACH && 254 code == ICMP_UNREACH_NEEDFRAG && mtu) { 255 icp->icmp_nextmtu = htons(mtu); 256 } 257 } 258 icp->icmp_code = code; 259 260 /* 261 * Copy the quotation into ICMP message and 262 * convert quoted IP header back to network representation. 263 */ 264 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 265 nip = &icp->icmp_ip; 266 nip->ip_len = htons(nip->ip_len); 267 nip->ip_off = htons(nip->ip_off); 268 269 /* 270 * Set up ICMP message mbuf and copy old IP header (without options 271 * in front of ICMP message. 272 * If the original mbuf was meant to bypass the firewall, the error 273 * reply should bypass as well. 274 */ 275 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 276 m->m_data -= sizeof(struct ip); 277 m->m_len += sizeof(struct ip); 278 m->m_pkthdr.len = m->m_len; 279 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 280 nip = mtod(m, struct ip *); 281 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 282 nip->ip_len = m->m_len; 283 nip->ip_v = IPVERSION; 284 nip->ip_hl = 5; 285 nip->ip_p = IPPROTO_ICMP; 286 nip->ip_tos = 0; 287 icmp_reflect(m); 288 289 freeit: 290 m_freem(n); 291 } 292 293 /* 294 * Process a received ICMP message. 295 */ 296 void 297 icmp_input(struct mbuf *m, int off) 298 { 299 INIT_VNET_INET(curvnet); 300 struct icmp *icp; 301 struct in_ifaddr *ia; 302 struct ip *ip = mtod(m, struct ip *); 303 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 304 int hlen = off; 305 int icmplen = ip->ip_len; 306 int i, code; 307 void (*ctlfunc)(int, struct sockaddr *, void *); 308 int fibnum; 309 310 /* 311 * Locate icmp structure in mbuf, and check 312 * that not corrupted and of at least minimum length. 313 */ 314 #ifdef ICMPPRINTFS 315 if (icmpprintfs) { 316 char buf[4 * sizeof "123"]; 317 strcpy(buf, inet_ntoa(ip->ip_src)); 318 printf("icmp_input from %s to %s, len %d\n", 319 buf, inet_ntoa(ip->ip_dst), icmplen); 320 } 321 #endif 322 if (icmplen < ICMP_MINLEN) { 323 V_icmpstat.icps_tooshort++; 324 goto freeit; 325 } 326 i = hlen + min(icmplen, ICMP_ADVLENMIN); 327 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 328 V_icmpstat.icps_tooshort++; 329 return; 330 } 331 ip = mtod(m, struct ip *); 332 m->m_len -= hlen; 333 m->m_data += hlen; 334 icp = mtod(m, struct icmp *); 335 if (in_cksum(m, icmplen)) { 336 V_icmpstat.icps_checksum++; 337 goto freeit; 338 } 339 m->m_len += hlen; 340 m->m_data -= hlen; 341 342 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 343 /* 344 * Deliver very specific ICMP type only. 345 */ 346 switch (icp->icmp_type) { 347 case ICMP_UNREACH: 348 case ICMP_TIMXCEED: 349 break; 350 default: 351 goto freeit; 352 } 353 } 354 355 #ifdef ICMPPRINTFS 356 if (icmpprintfs) 357 printf("icmp_input, type %d code %d\n", icp->icmp_type, 358 icp->icmp_code); 359 #endif 360 361 /* 362 * Message type specific processing. 363 */ 364 if (icp->icmp_type > ICMP_MAXTYPE) 365 goto raw; 366 367 /* Initialize */ 368 bzero(&icmpsrc, sizeof(icmpsrc)); 369 icmpsrc.sin_len = sizeof(struct sockaddr_in); 370 icmpsrc.sin_family = AF_INET; 371 bzero(&icmpdst, sizeof(icmpdst)); 372 icmpdst.sin_len = sizeof(struct sockaddr_in); 373 icmpdst.sin_family = AF_INET; 374 bzero(&icmpgw, sizeof(icmpgw)); 375 icmpgw.sin_len = sizeof(struct sockaddr_in); 376 icmpgw.sin_family = AF_INET; 377 378 V_icmpstat.icps_inhist[icp->icmp_type]++; 379 code = icp->icmp_code; 380 switch (icp->icmp_type) { 381 382 case ICMP_UNREACH: 383 switch (code) { 384 case ICMP_UNREACH_NET: 385 case ICMP_UNREACH_HOST: 386 case ICMP_UNREACH_SRCFAIL: 387 case ICMP_UNREACH_NET_UNKNOWN: 388 case ICMP_UNREACH_HOST_UNKNOWN: 389 case ICMP_UNREACH_ISOLATED: 390 case ICMP_UNREACH_TOSNET: 391 case ICMP_UNREACH_TOSHOST: 392 case ICMP_UNREACH_HOST_PRECEDENCE: 393 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 394 code = PRC_UNREACH_NET; 395 break; 396 397 case ICMP_UNREACH_NEEDFRAG: 398 code = PRC_MSGSIZE; 399 break; 400 401 /* 402 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 403 * Treat subcodes 2,3 as immediate RST 404 */ 405 case ICMP_UNREACH_PROTOCOL: 406 case ICMP_UNREACH_PORT: 407 code = PRC_UNREACH_PORT; 408 break; 409 410 case ICMP_UNREACH_NET_PROHIB: 411 case ICMP_UNREACH_HOST_PROHIB: 412 case ICMP_UNREACH_FILTER_PROHIB: 413 code = PRC_UNREACH_ADMIN_PROHIB; 414 break; 415 416 default: 417 goto badcode; 418 } 419 goto deliver; 420 421 case ICMP_TIMXCEED: 422 if (code > 1) 423 goto badcode; 424 code += PRC_TIMXCEED_INTRANS; 425 goto deliver; 426 427 case ICMP_PARAMPROB: 428 if (code > 1) 429 goto badcode; 430 code = PRC_PARAMPROB; 431 goto deliver; 432 433 case ICMP_SOURCEQUENCH: 434 if (code) 435 goto badcode; 436 code = PRC_QUENCH; 437 deliver: 438 /* 439 * Problem with datagram; advise higher level routines. 440 */ 441 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 442 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 443 V_icmpstat.icps_badlen++; 444 goto freeit; 445 } 446 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 447 /* Discard ICMP's in response to multicast packets */ 448 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 449 goto badcode; 450 #ifdef ICMPPRINTFS 451 if (icmpprintfs) 452 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 453 #endif 454 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 455 /* 456 * XXX if the packet contains [IPv4 AH TCP], we can't make a 457 * notification to TCP layer. 458 */ 459 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 460 if (ctlfunc) 461 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 462 (void *)&icp->icmp_ip); 463 break; 464 465 badcode: 466 V_icmpstat.icps_badcode++; 467 break; 468 469 case ICMP_ECHO: 470 if (!V_icmpbmcastecho 471 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 472 V_icmpstat.icps_bmcastecho++; 473 break; 474 } 475 icp->icmp_type = ICMP_ECHOREPLY; 476 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 477 goto freeit; 478 else 479 goto reflect; 480 481 case ICMP_TSTAMP: 482 if (!V_icmpbmcastecho 483 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 484 V_icmpstat.icps_bmcasttstamp++; 485 break; 486 } 487 if (icmplen < ICMP_TSLEN) { 488 V_icmpstat.icps_badlen++; 489 break; 490 } 491 icp->icmp_type = ICMP_TSTAMPREPLY; 492 icp->icmp_rtime = iptime(); 493 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 494 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 495 goto freeit; 496 else 497 goto reflect; 498 499 case ICMP_MASKREQ: 500 if (V_icmpmaskrepl == 0) 501 break; 502 /* 503 * We are not able to respond with all ones broadcast 504 * unless we receive it over a point-to-point interface. 505 */ 506 if (icmplen < ICMP_MASKLEN) 507 break; 508 switch (ip->ip_dst.s_addr) { 509 510 case INADDR_BROADCAST: 511 case INADDR_ANY: 512 icmpdst.sin_addr = ip->ip_src; 513 break; 514 515 default: 516 icmpdst.sin_addr = ip->ip_dst; 517 } 518 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 519 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 520 if (ia == 0) 521 break; 522 if (ia->ia_ifp == 0) 523 break; 524 icp->icmp_type = ICMP_MASKREPLY; 525 if (V_icmpmaskfake == 0) 526 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 527 else 528 icp->icmp_mask = V_icmpmaskfake; 529 if (ip->ip_src.s_addr == 0) { 530 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 531 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 532 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 533 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 534 } 535 reflect: 536 ip->ip_len += hlen; /* since ip_input deducts this */ 537 V_icmpstat.icps_reflect++; 538 V_icmpstat.icps_outhist[icp->icmp_type]++; 539 icmp_reflect(m); 540 return; 541 542 case ICMP_REDIRECT: 543 if (V_log_redirect) { 544 u_long src, dst, gw; 545 546 src = ntohl(ip->ip_src.s_addr); 547 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 548 gw = ntohl(icp->icmp_gwaddr.s_addr); 549 printf("icmp redirect from %d.%d.%d.%d: " 550 "%d.%d.%d.%d => %d.%d.%d.%d\n", 551 (int)(src >> 24), (int)((src >> 16) & 0xff), 552 (int)((src >> 8) & 0xff), (int)(src & 0xff), 553 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 554 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 555 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 556 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 557 } 558 /* 559 * RFC1812 says we must ignore ICMP redirects if we 560 * are acting as router. 561 */ 562 if (V_drop_redirect || V_ipforwarding) 563 break; 564 if (code > 3) 565 goto badcode; 566 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 567 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 568 V_icmpstat.icps_badlen++; 569 break; 570 } 571 /* 572 * Short circuit routing redirects to force 573 * immediate change in the kernel's routing 574 * tables. The message is also handed to anyone 575 * listening on a raw socket (e.g. the routing 576 * daemon for use in updating its tables). 577 */ 578 icmpgw.sin_addr = ip->ip_src; 579 icmpdst.sin_addr = icp->icmp_gwaddr; 580 #ifdef ICMPPRINTFS 581 if (icmpprintfs) { 582 char buf[4 * sizeof "123"]; 583 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 584 585 printf("redirect dst %s to %s\n", 586 buf, inet_ntoa(icp->icmp_gwaddr)); 587 } 588 #endif 589 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 590 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 591 in_rtredirect((struct sockaddr *)&icmpsrc, 592 (struct sockaddr *)&icmpdst, 593 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 594 (struct sockaddr *)&icmpgw, fibnum); 595 } 596 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 597 #ifdef IPSEC 598 key_sa_routechange((struct sockaddr *)&icmpsrc); 599 #endif 600 break; 601 602 /* 603 * No kernel processing for the following; 604 * just fall through to send to raw listener. 605 */ 606 case ICMP_ECHOREPLY: 607 case ICMP_ROUTERADVERT: 608 case ICMP_ROUTERSOLICIT: 609 case ICMP_TSTAMPREPLY: 610 case ICMP_IREQREPLY: 611 case ICMP_MASKREPLY: 612 default: 613 break; 614 } 615 616 raw: 617 rip_input(m, off); 618 return; 619 620 freeit: 621 m_freem(m); 622 } 623 624 /* 625 * Reflect the ip packet back to the source 626 */ 627 static void 628 icmp_reflect(struct mbuf *m) 629 { 630 INIT_VNET_INET(curvnet); 631 struct ip *ip = mtod(m, struct ip *); 632 struct ifaddr *ifa; 633 struct ifnet *ifn; 634 struct in_ifaddr *ia; 635 struct in_addr t; 636 struct mbuf *opts = 0; 637 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 638 639 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 640 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 641 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 642 m_freem(m); /* Bad return address */ 643 V_icmpstat.icps_badaddr++; 644 goto done; /* Ip_output() will check for broadcast */ 645 } 646 647 t = ip->ip_dst; 648 ip->ip_dst = ip->ip_src; 649 650 /* 651 * Source selection for ICMP replies: 652 * 653 * If the incoming packet was addressed directly to one of our 654 * own addresses, use dst as the src for the reply. 655 */ 656 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 657 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 658 goto match; 659 /* 660 * If the incoming packet was addressed to one of our broadcast 661 * addresses, use the first non-broadcast address which corresponds 662 * to the incoming interface. 663 */ 664 if (m->m_pkthdr.rcvif != NULL && 665 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 666 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 667 if (ifa->ifa_addr->sa_family != AF_INET) 668 continue; 669 ia = ifatoia(ifa); 670 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 671 t.s_addr) 672 goto match; 673 } 674 } 675 /* 676 * If the packet was transiting through us, use the address of 677 * the interface the packet came through in. If that interface 678 * doesn't have a suitable IP address, the normal selection 679 * criteria apply. 680 */ 681 if (V_icmp_rfi && m->m_pkthdr.rcvif != NULL) { 682 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 683 if (ifa->ifa_addr->sa_family != AF_INET) 684 continue; 685 ia = ifatoia(ifa); 686 goto match; 687 } 688 } 689 /* 690 * If the incoming packet was not addressed directly to us, use 691 * designated interface for icmp replies specified by sysctl 692 * net.inet.icmp.reply_src (default not set). Otherwise continue 693 * with normal source selection. 694 */ 695 if (V_reply_src[0] != '\0' && (ifn = ifunit(V_reply_src))) { 696 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 697 if (ifa->ifa_addr->sa_family != AF_INET) 698 continue; 699 ia = ifatoia(ifa); 700 goto match; 701 } 702 } 703 /* 704 * If the packet was transiting through us, use the address of 705 * the interface that is the closest to the packet source. 706 * When we don't have a route back to the packet source, stop here 707 * and drop the packet. 708 */ 709 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 710 if (ia == NULL) { 711 m_freem(m); 712 V_icmpstat.icps_noroute++; 713 goto done; 714 } 715 match: 716 #ifdef MAC 717 mac_netinet_icmp_replyinplace(m); 718 #endif 719 t = IA_SIN(ia)->sin_addr; 720 ip->ip_src = t; 721 ip->ip_ttl = V_ip_defttl; 722 723 if (optlen > 0) { 724 register u_char *cp; 725 int opt, cnt; 726 u_int len; 727 728 /* 729 * Retrieve any source routing from the incoming packet; 730 * add on any record-route or timestamp options. 731 */ 732 cp = (u_char *) (ip + 1); 733 if ((opts = ip_srcroute(m)) == 0 && 734 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 735 opts->m_len = sizeof(struct in_addr); 736 mtod(opts, struct in_addr *)->s_addr = 0; 737 } 738 if (opts) { 739 #ifdef ICMPPRINTFS 740 if (icmpprintfs) 741 printf("icmp_reflect optlen %d rt %d => ", 742 optlen, opts->m_len); 743 #endif 744 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 745 opt = cp[IPOPT_OPTVAL]; 746 if (opt == IPOPT_EOL) 747 break; 748 if (opt == IPOPT_NOP) 749 len = 1; 750 else { 751 if (cnt < IPOPT_OLEN + sizeof(*cp)) 752 break; 753 len = cp[IPOPT_OLEN]; 754 if (len < IPOPT_OLEN + sizeof(*cp) || 755 len > cnt) 756 break; 757 } 758 /* 759 * Should check for overflow, but it "can't happen" 760 */ 761 if (opt == IPOPT_RR || opt == IPOPT_TS || 762 opt == IPOPT_SECURITY) { 763 bcopy((caddr_t)cp, 764 mtod(opts, caddr_t) + opts->m_len, len); 765 opts->m_len += len; 766 } 767 } 768 /* Terminate & pad, if necessary */ 769 cnt = opts->m_len % 4; 770 if (cnt) { 771 for (; cnt < 4; cnt++) { 772 *(mtod(opts, caddr_t) + opts->m_len) = 773 IPOPT_EOL; 774 opts->m_len++; 775 } 776 } 777 #ifdef ICMPPRINTFS 778 if (icmpprintfs) 779 printf("%d\n", opts->m_len); 780 #endif 781 } 782 /* 783 * Now strip out original options by copying rest of first 784 * mbuf's data back, and adjust the IP length. 785 */ 786 ip->ip_len -= optlen; 787 ip->ip_v = IPVERSION; 788 ip->ip_hl = 5; 789 m->m_len -= optlen; 790 if (m->m_flags & M_PKTHDR) 791 m->m_pkthdr.len -= optlen; 792 optlen += sizeof(struct ip); 793 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 794 (unsigned)(m->m_len - sizeof(struct ip))); 795 } 796 m_tag_delete_nonpersistent(m); 797 m->m_flags &= ~(M_BCAST|M_MCAST); 798 icmp_send(m, opts); 799 done: 800 if (opts) 801 (void)m_free(opts); 802 } 803 804 /* 805 * Send an icmp packet back to the ip level, 806 * after supplying a checksum. 807 */ 808 static void 809 icmp_send(struct mbuf *m, struct mbuf *opts) 810 { 811 register struct ip *ip = mtod(m, struct ip *); 812 register int hlen; 813 register struct icmp *icp; 814 815 hlen = ip->ip_hl << 2; 816 m->m_data += hlen; 817 m->m_len -= hlen; 818 icp = mtod(m, struct icmp *); 819 icp->icmp_cksum = 0; 820 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 821 m->m_data -= hlen; 822 m->m_len += hlen; 823 m->m_pkthdr.rcvif = (struct ifnet *)0; 824 #ifdef ICMPPRINTFS 825 if (icmpprintfs) { 826 char buf[4 * sizeof "123"]; 827 strcpy(buf, inet_ntoa(ip->ip_dst)); 828 printf("icmp_send dst %s src %s\n", 829 buf, inet_ntoa(ip->ip_src)); 830 } 831 #endif 832 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 833 } 834 835 n_time 836 iptime(void) 837 { 838 struct timeval atv; 839 u_long t; 840 841 getmicrotime(&atv); 842 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 843 return (htonl(t)); 844 } 845 846 /* 847 * Return the next larger or smaller MTU plateau (table from RFC 1191) 848 * given current value MTU. If DIR is less than zero, a larger plateau 849 * is returned; otherwise, a smaller value is returned. 850 */ 851 int 852 ip_next_mtu(int mtu, 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 INIT_VNET_INET(curvnet); 899 900 #define N(a) (sizeof (a) / sizeof (a[0])) 901 static struct rate { 902 const char *type; 903 struct timeval lasttime; 904 int curpps; 905 } rates[BANDLIM_MAX+1] = { 906 { "icmp unreach response" }, 907 { "icmp ping response" }, 908 { "icmp tstamp response" }, 909 { "closed port RST response" }, 910 { "open port RST response" }, 911 { "icmp6 unreach response" } 912 }; 913 914 /* 915 * Return ok status if feature disabled or argument out of range. 916 */ 917 if (V_icmplim > 0 && (u_int) which < N(rates)) { 918 struct rate *r = &rates[which]; 919 int opps = r->curpps; 920 921 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 922 return -1; /* discard packet */ 923 /* 924 * If we've dropped below the threshold after having 925 * rate-limited traffic print the message. This preserves 926 * the previous behaviour at the expense of added complexity. 927 */ 928 if (V_icmplim_output && opps > V_icmplim) 929 printf("Limiting %s from %d to %d packets/sec\n", 930 r->type, opps, V_icmplim); 931 } 932 return 0; /* okay to send packet */ 933 #undef N 934 } 935