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 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/mbuf.h> 40 #include <sys/protosw.h> 41 #include <sys/socket.h> 42 #include <sys/time.h> 43 #include <sys/kernel.h> 44 #include <sys/sysctl.h> 45 #include <sys/vimage.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/ip_options.h> 59 #include <netinet/tcp.h> 60 #include <netinet/tcp_var.h> 61 #include <netinet/tcpip.h> 62 #include <netinet/icmp_var.h> 63 #include <netinet/vinet.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 #ifdef VIMAGE_GLOBALS 81 struct icmpstat icmpstat; 82 static int icmpmaskrepl; 83 static u_int icmpmaskfake; 84 static int drop_redirect; 85 static int log_redirect; 86 static int icmplim; 87 static int icmplim_output; 88 static char reply_src[IFNAMSIZ]; 89 static int icmp_rfi; 90 static int icmp_quotelen; 91 static int icmpbmcastecho; 92 #endif 93 94 SYSCTL_V_STRUCT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_STATS, stats, 95 CTLFLAG_RW, icmpstat, icmpstat, ""); 96 97 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, 98 CTLFLAG_RW, icmpmaskrepl, 0, 99 "Reply to ICMP Address Mask Request packets."); 100 101 SYSCTL_V_UINT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 102 icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 103 104 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, drop_redirect, 105 CTLFLAG_RW, drop_redirect, 0, "Ignore ICMP redirects"); 106 107 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, log_redirect, 108 CTLFLAG_RW, log_redirect, 0, "Log ICMP redirects to the console"); 109 110 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, 111 CTLFLAG_RW, icmplim, 0, "Maximum number of ICMP responses per second"); 112 113 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, icmplim_output, 114 CTLFLAG_RW, icmplim_output, 0, 115 "Enable rate limiting of ICMP responses"); 116 117 SYSCTL_V_STRING(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_src, 118 CTLFLAG_RW, reply_src, IFNAMSIZ, 119 "icmp reply source for non-local packets."); 120 121 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_from_interface, 122 CTLFLAG_RW, icmp_rfi, 0, "ICMP reply from incoming interface for " 123 "non-local packets"); 124 125 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 126 icmp_quotelen, 0, "Number of bytes from original packet to " 127 "quote in ICMP reply"); 128 129 /* 130 * ICMP broadcast echo sysctl 131 */ 132 133 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, bmcastecho, 134 CTLFLAG_RW, icmpbmcastecho, 0, ""); 135 136 137 #ifdef ICMPPRINTFS 138 int icmpprintfs = 0; 139 #endif 140 141 static void icmp_reflect(struct mbuf *); 142 static void icmp_send(struct mbuf *, struct mbuf *); 143 144 extern struct protosw inetsw[]; 145 146 void 147 icmp_init(void) 148 { 149 INIT_VNET_INET(curvnet); 150 151 V_icmpmaskrepl = 0; 152 V_icmpmaskfake = 0; 153 V_drop_redirect = 0; 154 V_log_redirect = 0; 155 V_icmplim = 200; 156 V_icmplim_output = 1; 157 V_icmp_rfi = 0; 158 V_icmp_quotelen = 8; 159 V_icmpbmcastecho = 0; 160 } 161 162 /* 163 * Generate an error packet of type error 164 * in response to bad packet ip. 165 */ 166 void 167 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 168 { 169 INIT_VNET_INET(curvnet); 170 register struct ip *oip = mtod(n, struct ip *), *nip; 171 register unsigned oiphlen = oip->ip_hl << 2; 172 register struct icmp *icp; 173 register struct mbuf *m; 174 unsigned icmplen, icmpelen, nlen; 175 176 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 177 #ifdef ICMPPRINTFS 178 if (icmpprintfs) 179 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 180 #endif 181 if (type != ICMP_REDIRECT) 182 ICMPSTAT_INC(icps_error); 183 /* 184 * Don't send error: 185 * if the original packet was encrypted. 186 * if not the first fragment of message. 187 * in response to a multicast or broadcast packet. 188 * if the old packet protocol was an ICMP error message. 189 */ 190 if (n->m_flags & M_DECRYPTED) 191 goto freeit; 192 if (oip->ip_off & ~(IP_MF|IP_DF)) 193 goto freeit; 194 if (n->m_flags & (M_BCAST|M_MCAST)) 195 goto freeit; 196 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 197 n->m_len >= oiphlen + ICMP_MINLEN && 198 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 199 ICMPSTAT_INC(icps_oldicmp); 200 goto freeit; 201 } 202 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 203 if (oiphlen + 8 > n->m_len) 204 goto freeit; 205 /* 206 * Calculate length to quote from original packet and 207 * prevent the ICMP mbuf from overflowing. 208 * Unfortunatly this is non-trivial since ip_forward() 209 * sends us truncated packets. 210 */ 211 nlen = m_length(n, NULL); 212 if (oip->ip_p == IPPROTO_TCP) { 213 struct tcphdr *th; 214 int tcphlen; 215 216 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 217 n->m_next == NULL) 218 goto stdreply; 219 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 220 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 221 goto freeit; 222 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 223 tcphlen = th->th_off << 2; 224 if (tcphlen < sizeof(struct tcphdr)) 225 goto freeit; 226 if (oip->ip_len < oiphlen + tcphlen) 227 goto freeit; 228 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 229 goto stdreply; 230 if (n->m_len < oiphlen + tcphlen && 231 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 232 goto freeit; 233 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 234 } else 235 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 236 237 icmplen = min(oiphlen + icmpelen, nlen); 238 if (icmplen < sizeof(struct ip)) 239 goto freeit; 240 241 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 242 m = m_gethdr(M_DONTWAIT, MT_DATA); 243 else 244 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 245 if (m == NULL) 246 goto freeit; 247 #ifdef MAC 248 mac_netinet_icmp_reply(n, m); 249 #endif 250 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 251 m_align(m, ICMP_MINLEN + icmplen); 252 m->m_len = ICMP_MINLEN + icmplen; 253 254 /* XXX MRT make the outgoing packet use the same FIB 255 * that was associated with the incoming packet 256 */ 257 M_SETFIB(m, M_GETFIB(n)); 258 icp = mtod(m, struct icmp *); 259 ICMPSTAT_INC(icps_outhist[type]); 260 icp->icmp_type = type; 261 if (type == ICMP_REDIRECT) 262 icp->icmp_gwaddr.s_addr = dest; 263 else { 264 icp->icmp_void = 0; 265 /* 266 * The following assignments assume an overlay with the 267 * just zeroed icmp_void field. 268 */ 269 if (type == ICMP_PARAMPROB) { 270 icp->icmp_pptr = code; 271 code = 0; 272 } else if (type == ICMP_UNREACH && 273 code == ICMP_UNREACH_NEEDFRAG && mtu) { 274 icp->icmp_nextmtu = htons(mtu); 275 } 276 } 277 icp->icmp_code = code; 278 279 /* 280 * Copy the quotation into ICMP message and 281 * convert quoted IP header back to network representation. 282 */ 283 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 284 nip = &icp->icmp_ip; 285 nip->ip_len = htons(nip->ip_len); 286 nip->ip_off = htons(nip->ip_off); 287 288 /* 289 * Set up ICMP message mbuf and copy old IP header (without options 290 * in front of ICMP message. 291 * If the original mbuf was meant to bypass the firewall, the error 292 * reply should bypass as well. 293 */ 294 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 295 m->m_data -= sizeof(struct ip); 296 m->m_len += sizeof(struct ip); 297 m->m_pkthdr.len = m->m_len; 298 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 299 nip = mtod(m, struct ip *); 300 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 301 nip->ip_len = m->m_len; 302 nip->ip_v = IPVERSION; 303 nip->ip_hl = 5; 304 nip->ip_p = IPPROTO_ICMP; 305 nip->ip_tos = 0; 306 icmp_reflect(m); 307 308 freeit: 309 m_freem(n); 310 } 311 312 /* 313 * Process a received ICMP message. 314 */ 315 void 316 icmp_input(struct mbuf *m, int off) 317 { 318 INIT_VNET_INET(curvnet); 319 struct icmp *icp; 320 struct in_ifaddr *ia; 321 struct ip *ip = mtod(m, struct ip *); 322 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 323 int hlen = off; 324 int icmplen = ip->ip_len; 325 int i, code; 326 void (*ctlfunc)(int, struct sockaddr *, void *); 327 int fibnum; 328 329 /* 330 * Locate icmp structure in mbuf, and check 331 * that not corrupted and of at least minimum length. 332 */ 333 #ifdef ICMPPRINTFS 334 if (icmpprintfs) { 335 char buf[4 * sizeof "123"]; 336 strcpy(buf, inet_ntoa(ip->ip_src)); 337 printf("icmp_input from %s to %s, len %d\n", 338 buf, inet_ntoa(ip->ip_dst), icmplen); 339 } 340 #endif 341 if (icmplen < ICMP_MINLEN) { 342 ICMPSTAT_INC(icps_tooshort); 343 goto freeit; 344 } 345 i = hlen + min(icmplen, ICMP_ADVLENMIN); 346 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 347 ICMPSTAT_INC(icps_tooshort); 348 return; 349 } 350 ip = mtod(m, struct ip *); 351 m->m_len -= hlen; 352 m->m_data += hlen; 353 icp = mtod(m, struct icmp *); 354 if (in_cksum(m, icmplen)) { 355 ICMPSTAT_INC(icps_checksum); 356 goto freeit; 357 } 358 m->m_len += hlen; 359 m->m_data -= hlen; 360 361 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 362 /* 363 * Deliver very specific ICMP type only. 364 */ 365 switch (icp->icmp_type) { 366 case ICMP_UNREACH: 367 case ICMP_TIMXCEED: 368 break; 369 default: 370 goto freeit; 371 } 372 } 373 374 #ifdef ICMPPRINTFS 375 if (icmpprintfs) 376 printf("icmp_input, type %d code %d\n", icp->icmp_type, 377 icp->icmp_code); 378 #endif 379 380 /* 381 * Message type specific processing. 382 */ 383 if (icp->icmp_type > ICMP_MAXTYPE) 384 goto raw; 385 386 /* Initialize */ 387 bzero(&icmpsrc, sizeof(icmpsrc)); 388 icmpsrc.sin_len = sizeof(struct sockaddr_in); 389 icmpsrc.sin_family = AF_INET; 390 bzero(&icmpdst, sizeof(icmpdst)); 391 icmpdst.sin_len = sizeof(struct sockaddr_in); 392 icmpdst.sin_family = AF_INET; 393 bzero(&icmpgw, sizeof(icmpgw)); 394 icmpgw.sin_len = sizeof(struct sockaddr_in); 395 icmpgw.sin_family = AF_INET; 396 397 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 398 code = icp->icmp_code; 399 switch (icp->icmp_type) { 400 401 case ICMP_UNREACH: 402 switch (code) { 403 case ICMP_UNREACH_NET: 404 case ICMP_UNREACH_HOST: 405 case ICMP_UNREACH_SRCFAIL: 406 case ICMP_UNREACH_NET_UNKNOWN: 407 case ICMP_UNREACH_HOST_UNKNOWN: 408 case ICMP_UNREACH_ISOLATED: 409 case ICMP_UNREACH_TOSNET: 410 case ICMP_UNREACH_TOSHOST: 411 case ICMP_UNREACH_HOST_PRECEDENCE: 412 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 413 code = PRC_UNREACH_NET; 414 break; 415 416 case ICMP_UNREACH_NEEDFRAG: 417 code = PRC_MSGSIZE; 418 break; 419 420 /* 421 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 422 * Treat subcodes 2,3 as immediate RST 423 */ 424 case ICMP_UNREACH_PROTOCOL: 425 case ICMP_UNREACH_PORT: 426 code = PRC_UNREACH_PORT; 427 break; 428 429 case ICMP_UNREACH_NET_PROHIB: 430 case ICMP_UNREACH_HOST_PROHIB: 431 case ICMP_UNREACH_FILTER_PROHIB: 432 code = PRC_UNREACH_ADMIN_PROHIB; 433 break; 434 435 default: 436 goto badcode; 437 } 438 goto deliver; 439 440 case ICMP_TIMXCEED: 441 if (code > 1) 442 goto badcode; 443 code += PRC_TIMXCEED_INTRANS; 444 goto deliver; 445 446 case ICMP_PARAMPROB: 447 if (code > 1) 448 goto badcode; 449 code = PRC_PARAMPROB; 450 goto deliver; 451 452 case ICMP_SOURCEQUENCH: 453 if (code) 454 goto badcode; 455 code = PRC_QUENCH; 456 deliver: 457 /* 458 * Problem with datagram; advise higher level routines. 459 */ 460 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 461 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 462 ICMPSTAT_INC(icps_badlen); 463 goto freeit; 464 } 465 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 466 /* Discard ICMP's in response to multicast packets */ 467 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 468 goto badcode; 469 #ifdef ICMPPRINTFS 470 if (icmpprintfs) 471 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 472 #endif 473 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 474 /* 475 * XXX if the packet contains [IPv4 AH TCP], we can't make a 476 * notification to TCP layer. 477 */ 478 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 479 if (ctlfunc) 480 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 481 (void *)&icp->icmp_ip); 482 break; 483 484 badcode: 485 ICMPSTAT_INC(icps_badcode); 486 break; 487 488 case ICMP_ECHO: 489 if (!V_icmpbmcastecho 490 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 491 ICMPSTAT_INC(icps_bmcastecho); 492 break; 493 } 494 icp->icmp_type = ICMP_ECHOREPLY; 495 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 496 goto freeit; 497 else 498 goto reflect; 499 500 case ICMP_TSTAMP: 501 if (!V_icmpbmcastecho 502 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 503 ICMPSTAT_INC(icps_bmcasttstamp); 504 break; 505 } 506 if (icmplen < ICMP_TSLEN) { 507 ICMPSTAT_INC(icps_badlen); 508 break; 509 } 510 icp->icmp_type = ICMP_TSTAMPREPLY; 511 icp->icmp_rtime = iptime(); 512 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 513 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 514 goto freeit; 515 else 516 goto reflect; 517 518 case ICMP_MASKREQ: 519 if (V_icmpmaskrepl == 0) 520 break; 521 /* 522 * We are not able to respond with all ones broadcast 523 * unless we receive it over a point-to-point interface. 524 */ 525 if (icmplen < ICMP_MASKLEN) 526 break; 527 switch (ip->ip_dst.s_addr) { 528 529 case INADDR_BROADCAST: 530 case INADDR_ANY: 531 icmpdst.sin_addr = ip->ip_src; 532 break; 533 534 default: 535 icmpdst.sin_addr = ip->ip_dst; 536 } 537 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 538 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 539 if (ia == NULL) 540 break; 541 if (ia->ia_ifp == NULL) { 542 ifa_free(&ia->ia_ifa); 543 break; 544 } 545 icp->icmp_type = ICMP_MASKREPLY; 546 if (V_icmpmaskfake == 0) 547 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 548 else 549 icp->icmp_mask = V_icmpmaskfake; 550 if (ip->ip_src.s_addr == 0) { 551 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 552 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 553 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 554 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 555 } 556 ifa_free(&ia->ia_ifa); 557 reflect: 558 ip->ip_len += hlen; /* since ip_input deducts this */ 559 ICMPSTAT_INC(icps_reflect); 560 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 561 icmp_reflect(m); 562 return; 563 564 case ICMP_REDIRECT: 565 if (V_log_redirect) { 566 u_long src, dst, gw; 567 568 src = ntohl(ip->ip_src.s_addr); 569 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 570 gw = ntohl(icp->icmp_gwaddr.s_addr); 571 printf("icmp redirect from %d.%d.%d.%d: " 572 "%d.%d.%d.%d => %d.%d.%d.%d\n", 573 (int)(src >> 24), (int)((src >> 16) & 0xff), 574 (int)((src >> 8) & 0xff), (int)(src & 0xff), 575 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 576 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 577 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 578 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 579 } 580 /* 581 * RFC1812 says we must ignore ICMP redirects if we 582 * are acting as router. 583 */ 584 if (V_drop_redirect || V_ipforwarding) 585 break; 586 if (code > 3) 587 goto badcode; 588 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 589 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 590 ICMPSTAT_INC(icps_badlen); 591 break; 592 } 593 /* 594 * Short circuit routing redirects to force 595 * immediate change in the kernel's routing 596 * tables. The message is also handed to anyone 597 * listening on a raw socket (e.g. the routing 598 * daemon for use in updating its tables). 599 */ 600 icmpgw.sin_addr = ip->ip_src; 601 icmpdst.sin_addr = icp->icmp_gwaddr; 602 #ifdef ICMPPRINTFS 603 if (icmpprintfs) { 604 char buf[4 * sizeof "123"]; 605 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 606 607 printf("redirect dst %s to %s\n", 608 buf, inet_ntoa(icp->icmp_gwaddr)); 609 } 610 #endif 611 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 612 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 613 in_rtredirect((struct sockaddr *)&icmpsrc, 614 (struct sockaddr *)&icmpdst, 615 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 616 (struct sockaddr *)&icmpgw, fibnum); 617 } 618 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 619 #ifdef IPSEC 620 key_sa_routechange((struct sockaddr *)&icmpsrc); 621 #endif 622 break; 623 624 /* 625 * No kernel processing for the following; 626 * just fall through to send to raw listener. 627 */ 628 case ICMP_ECHOREPLY: 629 case ICMP_ROUTERADVERT: 630 case ICMP_ROUTERSOLICIT: 631 case ICMP_TSTAMPREPLY: 632 case ICMP_IREQREPLY: 633 case ICMP_MASKREPLY: 634 default: 635 break; 636 } 637 638 raw: 639 rip_input(m, off); 640 return; 641 642 freeit: 643 m_freem(m); 644 } 645 646 /* 647 * Reflect the ip packet back to the source 648 */ 649 static void 650 icmp_reflect(struct mbuf *m) 651 { 652 INIT_VNET_INET(curvnet); 653 struct ip *ip = mtod(m, struct ip *); 654 struct ifaddr *ifa; 655 struct ifnet *ifp; 656 struct in_ifaddr *ia; 657 struct in_addr t; 658 struct mbuf *opts = 0; 659 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 660 661 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 662 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 663 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 664 m_freem(m); /* Bad return address */ 665 ICMPSTAT_INC(icps_badaddr); 666 goto done; /* Ip_output() will check for broadcast */ 667 } 668 669 t = ip->ip_dst; 670 ip->ip_dst = ip->ip_src; 671 672 /* 673 * Source selection for ICMP replies: 674 * 675 * If the incoming packet was addressed directly to one of our 676 * own addresses, use dst as the src for the reply. 677 */ 678 IN_IFADDR_RLOCK(); 679 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 680 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 681 t = IA_SIN(ia)->sin_addr; 682 IN_IFADDR_RUNLOCK(); 683 goto match; 684 } 685 } 686 IN_IFADDR_RUNLOCK(); 687 688 /* 689 * If the incoming packet was addressed to one of our broadcast 690 * addresses, use the first non-broadcast address which corresponds 691 * to the incoming interface. 692 */ 693 ifp = m->m_pkthdr.rcvif; 694 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 695 IF_ADDR_LOCK(ifp); 696 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 697 if (ifa->ifa_addr->sa_family != AF_INET) 698 continue; 699 ia = ifatoia(ifa); 700 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 701 t.s_addr) { 702 t = IA_SIN(ia)->sin_addr; 703 IF_ADDR_UNLOCK(ifp); 704 goto match; 705 } 706 } 707 IF_ADDR_UNLOCK(ifp); 708 } 709 /* 710 * If the packet was transiting through us, use the address of 711 * the interface the packet came through in. If that interface 712 * doesn't have a suitable IP address, the normal selection 713 * criteria apply. 714 */ 715 if (V_icmp_rfi && ifp != NULL) { 716 IF_ADDR_LOCK(ifp); 717 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 718 if (ifa->ifa_addr->sa_family != AF_INET) 719 continue; 720 ia = ifatoia(ifa); 721 t = IA_SIN(ia)->sin_addr; 722 IF_ADDR_UNLOCK(ifp); 723 goto match; 724 } 725 IF_ADDR_UNLOCK(ifp); 726 } 727 /* 728 * If the incoming packet was not addressed directly to us, use 729 * designated interface for icmp replies specified by sysctl 730 * net.inet.icmp.reply_src (default not set). Otherwise continue 731 * with normal source selection. 732 */ 733 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 734 IF_ADDR_LOCK(ifp); 735 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 736 if (ifa->ifa_addr->sa_family != AF_INET) 737 continue; 738 ia = ifatoia(ifa); 739 t = IA_SIN(ia)->sin_addr; 740 IF_ADDR_UNLOCK(ifp); 741 goto match; 742 } 743 IF_ADDR_UNLOCK(ifp); 744 } 745 /* 746 * If the packet was transiting through us, use the address of 747 * the interface that is the closest to the packet source. 748 * When we don't have a route back to the packet source, stop here 749 * and drop the packet. 750 */ 751 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 752 if (ia == NULL) { 753 m_freem(m); 754 ICMPSTAT_INC(icps_noroute); 755 goto done; 756 } 757 t = IA_SIN(ia)->sin_addr; 758 ifa_free(&ia->ia_ifa); 759 match: 760 #ifdef MAC 761 mac_netinet_icmp_replyinplace(m); 762 #endif 763 ip->ip_src = t; 764 ip->ip_ttl = V_ip_defttl; 765 766 if (optlen > 0) { 767 register u_char *cp; 768 int opt, cnt; 769 u_int len; 770 771 /* 772 * Retrieve any source routing from the incoming packet; 773 * add on any record-route or timestamp options. 774 */ 775 cp = (u_char *) (ip + 1); 776 if ((opts = ip_srcroute(m)) == 0 && 777 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 778 opts->m_len = sizeof(struct in_addr); 779 mtod(opts, struct in_addr *)->s_addr = 0; 780 } 781 if (opts) { 782 #ifdef ICMPPRINTFS 783 if (icmpprintfs) 784 printf("icmp_reflect optlen %d rt %d => ", 785 optlen, opts->m_len); 786 #endif 787 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 788 opt = cp[IPOPT_OPTVAL]; 789 if (opt == IPOPT_EOL) 790 break; 791 if (opt == IPOPT_NOP) 792 len = 1; 793 else { 794 if (cnt < IPOPT_OLEN + sizeof(*cp)) 795 break; 796 len = cp[IPOPT_OLEN]; 797 if (len < IPOPT_OLEN + sizeof(*cp) || 798 len > cnt) 799 break; 800 } 801 /* 802 * Should check for overflow, but it "can't happen" 803 */ 804 if (opt == IPOPT_RR || opt == IPOPT_TS || 805 opt == IPOPT_SECURITY) { 806 bcopy((caddr_t)cp, 807 mtod(opts, caddr_t) + opts->m_len, len); 808 opts->m_len += len; 809 } 810 } 811 /* Terminate & pad, if necessary */ 812 cnt = opts->m_len % 4; 813 if (cnt) { 814 for (; cnt < 4; cnt++) { 815 *(mtod(opts, caddr_t) + opts->m_len) = 816 IPOPT_EOL; 817 opts->m_len++; 818 } 819 } 820 #ifdef ICMPPRINTFS 821 if (icmpprintfs) 822 printf("%d\n", opts->m_len); 823 #endif 824 } 825 /* 826 * Now strip out original options by copying rest of first 827 * mbuf's data back, and adjust the IP length. 828 */ 829 ip->ip_len -= optlen; 830 ip->ip_v = IPVERSION; 831 ip->ip_hl = 5; 832 m->m_len -= optlen; 833 if (m->m_flags & M_PKTHDR) 834 m->m_pkthdr.len -= optlen; 835 optlen += sizeof(struct ip); 836 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 837 (unsigned)(m->m_len - sizeof(struct ip))); 838 } 839 m_tag_delete_nonpersistent(m); 840 m->m_flags &= ~(M_BCAST|M_MCAST); 841 icmp_send(m, opts); 842 done: 843 if (opts) 844 (void)m_free(opts); 845 } 846 847 /* 848 * Send an icmp packet back to the ip level, 849 * after supplying a checksum. 850 */ 851 static void 852 icmp_send(struct mbuf *m, struct mbuf *opts) 853 { 854 register struct ip *ip = mtod(m, struct ip *); 855 register int hlen; 856 register struct icmp *icp; 857 858 hlen = ip->ip_hl << 2; 859 m->m_data += hlen; 860 m->m_len -= hlen; 861 icp = mtod(m, struct icmp *); 862 icp->icmp_cksum = 0; 863 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 864 m->m_data -= hlen; 865 m->m_len += hlen; 866 m->m_pkthdr.rcvif = (struct ifnet *)0; 867 #ifdef ICMPPRINTFS 868 if (icmpprintfs) { 869 char buf[4 * sizeof "123"]; 870 strcpy(buf, inet_ntoa(ip->ip_dst)); 871 printf("icmp_send dst %s src %s\n", 872 buf, inet_ntoa(ip->ip_src)); 873 } 874 #endif 875 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 876 } 877 878 /* 879 * Return milliseconds since 00:00 GMT in network format. 880 */ 881 uint32_t 882 iptime(void) 883 { 884 struct timeval atv; 885 u_long t; 886 887 getmicrotime(&atv); 888 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 889 return (htonl(t)); 890 } 891 892 /* 893 * Return the next larger or smaller MTU plateau (table from RFC 1191) 894 * given current value MTU. If DIR is less than zero, a larger plateau 895 * is returned; otherwise, a smaller value is returned. 896 */ 897 int 898 ip_next_mtu(int mtu, int dir) 899 { 900 static int mtutab[] = { 901 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 902 296, 68, 0 903 }; 904 int i, size; 905 906 size = (sizeof mtutab) / (sizeof mtutab[0]); 907 if (dir >= 0) { 908 for (i = 0; i < size; i++) 909 if (mtu > mtutab[i]) 910 return mtutab[i]; 911 } else { 912 for (i = size - 1; i >= 0; i--) 913 if (mtu < mtutab[i]) 914 return mtutab[i]; 915 if (mtu == mtutab[0]) 916 return mtutab[0]; 917 } 918 return 0; 919 } 920 921 922 /* 923 * badport_bandlim() - check for ICMP bandwidth limit 924 * 925 * Return 0 if it is ok to send an ICMP error response, -1 if we have 926 * hit our bandwidth limit and it is not ok. 927 * 928 * If icmplim is <= 0, the feature is disabled and 0 is returned. 929 * 930 * For now we separate the TCP and UDP subsystems w/ different 'which' 931 * values. We may eventually remove this separation (and simplify the 932 * code further). 933 * 934 * Note that the printing of the error message is delayed so we can 935 * properly print the icmp error rate that the system was trying to do 936 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 937 * the 'final' error, but it doesn't make sense to solve the printing 938 * delay with more complex code. 939 */ 940 941 int 942 badport_bandlim(int which) 943 { 944 INIT_VNET_INET(curvnet); 945 946 #define N(a) (sizeof (a) / sizeof (a[0])) 947 static struct rate { 948 const char *type; 949 struct timeval lasttime; 950 int curpps; 951 } rates[BANDLIM_MAX+1] = { 952 { "icmp unreach response" }, 953 { "icmp ping response" }, 954 { "icmp tstamp response" }, 955 { "closed port RST response" }, 956 { "open port RST response" }, 957 { "icmp6 unreach response" } 958 }; 959 960 /* 961 * Return ok status if feature disabled or argument out of range. 962 */ 963 if (V_icmplim > 0 && (u_int) which < N(rates)) { 964 struct rate *r = &rates[which]; 965 int opps = r->curpps; 966 967 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 968 return -1; /* discard packet */ 969 /* 970 * If we've dropped below the threshold after having 971 * rate-limited traffic print the message. This preserves 972 * the previous behaviour at the expense of added complexity. 973 */ 974 if (V_icmplim_output && opps > V_icmplim) 975 printf("Limiting %s from %d to %d packets/sec\n", 976 r->type, opps, V_icmplim); 977 } 978 return 0; /* okay to send packet */ 979 #undef N 980 } 981