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 #include <netinet/vinet.h> 65 66 #ifdef IPSEC 67 #include <netipsec/ipsec.h> 68 #include <netipsec/key.h> 69 #endif 70 71 #include <machine/in_cksum.h> 72 73 #include <security/mac/mac_framework.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 #ifdef VIMAGE_GLOBALS 82 struct icmpstat icmpstat; 83 static int icmpmaskrepl; 84 static u_int icmpmaskfake; 85 static int drop_redirect; 86 static int log_redirect; 87 static int icmplim; 88 static int icmplim_output; 89 static char reply_src[IFNAMSIZ]; 90 static int icmp_rfi; 91 static int icmp_quotelen; 92 static int icmpbmcastecho; 93 #endif 94 95 SYSCTL_V_STRUCT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_STATS, stats, 96 CTLFLAG_RW, icmpstat, icmpstat, ""); 97 98 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, 99 CTLFLAG_RW, icmpmaskrepl, 0, 100 "Reply to ICMP Address Mask Request packets."); 101 102 SYSCTL_V_UINT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 103 icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 104 105 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, drop_redirect, 106 CTLFLAG_RW, drop_redirect, 0, "Ignore ICMP redirects"); 107 108 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, log_redirect, 109 CTLFLAG_RW, log_redirect, 0, "Log ICMP redirects to the console"); 110 111 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, 112 CTLFLAG_RW, icmplim, 0, "Maximum number of ICMP responses per second"); 113 114 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, icmplim_output, 115 CTLFLAG_RW, icmplim_output, 0, 116 "Enable rate limiting of ICMP responses"); 117 118 SYSCTL_V_STRING(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_src, 119 CTLFLAG_RW, reply_src, IFNAMSIZ, 120 "icmp reply source for non-local packets."); 121 122 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_from_interface, 123 CTLFLAG_RW, icmp_rfi, 0, "ICMP reply from incoming interface for " 124 "non-local packets"); 125 126 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 127 icmp_quotelen, 0, "Number of bytes from original packet to " 128 "quote in ICMP reply"); 129 130 /* 131 * ICMP broadcast echo sysctl 132 */ 133 134 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, bmcastecho, 135 CTLFLAG_RW, icmpbmcastecho, 0, ""); 136 137 138 #ifdef ICMPPRINTFS 139 int icmpprintfs = 0; 140 #endif 141 142 static void icmp_reflect(struct mbuf *); 143 static void icmp_send(struct mbuf *, struct mbuf *); 144 145 extern struct protosw inetsw[]; 146 147 void 148 icmp_init(void) 149 { 150 INIT_VNET_INET(curvnet); 151 152 V_icmpmaskrepl = 0; 153 V_icmpmaskfake = 0; 154 V_drop_redirect = 0; 155 V_log_redirect = 0; 156 V_icmplim = 200; 157 V_icmplim_output = 1; 158 V_icmp_rfi = 0; 159 V_icmp_quotelen = 8; 160 V_icmpbmcastecho = 0; 161 } 162 163 /* 164 * Generate an error packet of type error 165 * in response to bad packet ip. 166 */ 167 void 168 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 169 { 170 INIT_VNET_INET(curvnet); 171 register struct ip *oip = mtod(n, struct ip *), *nip; 172 register unsigned oiphlen = oip->ip_hl << 2; 173 register struct icmp *icp; 174 register struct mbuf *m; 175 unsigned icmplen, icmpelen, nlen; 176 177 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 178 #ifdef ICMPPRINTFS 179 if (icmpprintfs) 180 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 181 #endif 182 if (type != ICMP_REDIRECT) 183 V_icmpstat.icps_error++; 184 /* 185 * Don't send error: 186 * if the original packet was encrypted. 187 * if not the first fragment of message. 188 * in response to a multicast or broadcast packet. 189 * if the old packet protocol was an ICMP error message. 190 */ 191 if (n->m_flags & M_DECRYPTED) 192 goto freeit; 193 if (oip->ip_off & ~(IP_MF|IP_DF)) 194 goto freeit; 195 if (n->m_flags & (M_BCAST|M_MCAST)) 196 goto freeit; 197 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 198 n->m_len >= oiphlen + ICMP_MINLEN && 199 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 200 V_icmpstat.icps_oldicmp++; 201 goto freeit; 202 } 203 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 204 if (oiphlen + 8 > n->m_len) 205 goto freeit; 206 /* 207 * Calculate length to quote from original packet and 208 * prevent the ICMP mbuf from overflowing. 209 * Unfortunatly this is non-trivial since ip_forward() 210 * sends us truncated packets. 211 */ 212 nlen = m_length(n, NULL); 213 if (oip->ip_p == IPPROTO_TCP) { 214 struct tcphdr *th; 215 int tcphlen; 216 217 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 218 n->m_next == NULL) 219 goto stdreply; 220 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 221 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 222 goto freeit; 223 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 224 tcphlen = th->th_off << 2; 225 if (tcphlen < sizeof(struct tcphdr)) 226 goto freeit; 227 if (oip->ip_len < oiphlen + tcphlen) 228 goto freeit; 229 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 230 goto stdreply; 231 if (n->m_len < oiphlen + tcphlen && 232 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 233 goto freeit; 234 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 235 } else 236 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 237 238 icmplen = min(oiphlen + icmpelen, nlen); 239 if (icmplen < sizeof(struct ip)) 240 goto freeit; 241 242 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 243 m = m_gethdr(M_DONTWAIT, MT_DATA); 244 else 245 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 246 if (m == NULL) 247 goto freeit; 248 #ifdef MAC 249 mac_netinet_icmp_reply(n, m); 250 #endif 251 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 252 m_align(m, ICMP_MINLEN + icmplen); 253 m->m_len = ICMP_MINLEN + icmplen; 254 255 /* XXX MRT make the outgoing packet use the same FIB 256 * that was associated with the incoming packet 257 */ 258 M_SETFIB(m, M_GETFIB(n)); 259 icp = mtod(m, struct icmp *); 260 V_icmpstat.icps_outhist[type]++; 261 icp->icmp_type = type; 262 if (type == ICMP_REDIRECT) 263 icp->icmp_gwaddr.s_addr = dest; 264 else { 265 icp->icmp_void = 0; 266 /* 267 * The following assignments assume an overlay with the 268 * just zeroed icmp_void field. 269 */ 270 if (type == ICMP_PARAMPROB) { 271 icp->icmp_pptr = code; 272 code = 0; 273 } else if (type == ICMP_UNREACH && 274 code == ICMP_UNREACH_NEEDFRAG && mtu) { 275 icp->icmp_nextmtu = htons(mtu); 276 } 277 } 278 icp->icmp_code = code; 279 280 /* 281 * Copy the quotation into ICMP message and 282 * convert quoted IP header back to network representation. 283 */ 284 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 285 nip = &icp->icmp_ip; 286 nip->ip_len = htons(nip->ip_len); 287 nip->ip_off = htons(nip->ip_off); 288 289 /* 290 * Set up ICMP message mbuf and copy old IP header (without options 291 * in front of ICMP message. 292 * If the original mbuf was meant to bypass the firewall, the error 293 * reply should bypass as well. 294 */ 295 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 296 m->m_data -= sizeof(struct ip); 297 m->m_len += sizeof(struct ip); 298 m->m_pkthdr.len = m->m_len; 299 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 300 nip = mtod(m, struct ip *); 301 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 302 nip->ip_len = m->m_len; 303 nip->ip_v = IPVERSION; 304 nip->ip_hl = 5; 305 nip->ip_p = IPPROTO_ICMP; 306 nip->ip_tos = 0; 307 icmp_reflect(m); 308 309 freeit: 310 m_freem(n); 311 } 312 313 /* 314 * Process a received ICMP message. 315 */ 316 void 317 icmp_input(struct mbuf *m, int off) 318 { 319 INIT_VNET_INET(curvnet); 320 struct icmp *icp; 321 struct in_ifaddr *ia; 322 struct ip *ip = mtod(m, struct ip *); 323 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 324 int hlen = off; 325 int icmplen = ip->ip_len; 326 int i, code; 327 void (*ctlfunc)(int, struct sockaddr *, void *); 328 int fibnum; 329 330 /* 331 * Locate icmp structure in mbuf, and check 332 * that not corrupted and of at least minimum length. 333 */ 334 #ifdef ICMPPRINTFS 335 if (icmpprintfs) { 336 char buf[4 * sizeof "123"]; 337 strcpy(buf, inet_ntoa(ip->ip_src)); 338 printf("icmp_input from %s to %s, len %d\n", 339 buf, inet_ntoa(ip->ip_dst), icmplen); 340 } 341 #endif 342 if (icmplen < ICMP_MINLEN) { 343 V_icmpstat.icps_tooshort++; 344 goto freeit; 345 } 346 i = hlen + min(icmplen, ICMP_ADVLENMIN); 347 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 348 V_icmpstat.icps_tooshort++; 349 return; 350 } 351 ip = mtod(m, struct ip *); 352 m->m_len -= hlen; 353 m->m_data += hlen; 354 icp = mtod(m, struct icmp *); 355 if (in_cksum(m, icmplen)) { 356 V_icmpstat.icps_checksum++; 357 goto freeit; 358 } 359 m->m_len += hlen; 360 m->m_data -= hlen; 361 362 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 363 /* 364 * Deliver very specific ICMP type only. 365 */ 366 switch (icp->icmp_type) { 367 case ICMP_UNREACH: 368 case ICMP_TIMXCEED: 369 break; 370 default: 371 goto freeit; 372 } 373 } 374 375 #ifdef ICMPPRINTFS 376 if (icmpprintfs) 377 printf("icmp_input, type %d code %d\n", icp->icmp_type, 378 icp->icmp_code); 379 #endif 380 381 /* 382 * Message type specific processing. 383 */ 384 if (icp->icmp_type > ICMP_MAXTYPE) 385 goto raw; 386 387 /* Initialize */ 388 bzero(&icmpsrc, sizeof(icmpsrc)); 389 icmpsrc.sin_len = sizeof(struct sockaddr_in); 390 icmpsrc.sin_family = AF_INET; 391 bzero(&icmpdst, sizeof(icmpdst)); 392 icmpdst.sin_len = sizeof(struct sockaddr_in); 393 icmpdst.sin_family = AF_INET; 394 bzero(&icmpgw, sizeof(icmpgw)); 395 icmpgw.sin_len = sizeof(struct sockaddr_in); 396 icmpgw.sin_family = AF_INET; 397 398 V_icmpstat.icps_inhist[icp->icmp_type]++; 399 code = icp->icmp_code; 400 switch (icp->icmp_type) { 401 402 case ICMP_UNREACH: 403 switch (code) { 404 case ICMP_UNREACH_NET: 405 case ICMP_UNREACH_HOST: 406 case ICMP_UNREACH_SRCFAIL: 407 case ICMP_UNREACH_NET_UNKNOWN: 408 case ICMP_UNREACH_HOST_UNKNOWN: 409 case ICMP_UNREACH_ISOLATED: 410 case ICMP_UNREACH_TOSNET: 411 case ICMP_UNREACH_TOSHOST: 412 case ICMP_UNREACH_HOST_PRECEDENCE: 413 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 414 code = PRC_UNREACH_NET; 415 break; 416 417 case ICMP_UNREACH_NEEDFRAG: 418 code = PRC_MSGSIZE; 419 break; 420 421 /* 422 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 423 * Treat subcodes 2,3 as immediate RST 424 */ 425 case ICMP_UNREACH_PROTOCOL: 426 case ICMP_UNREACH_PORT: 427 code = PRC_UNREACH_PORT; 428 break; 429 430 case ICMP_UNREACH_NET_PROHIB: 431 case ICMP_UNREACH_HOST_PROHIB: 432 case ICMP_UNREACH_FILTER_PROHIB: 433 code = PRC_UNREACH_ADMIN_PROHIB; 434 break; 435 436 default: 437 goto badcode; 438 } 439 goto deliver; 440 441 case ICMP_TIMXCEED: 442 if (code > 1) 443 goto badcode; 444 code += PRC_TIMXCEED_INTRANS; 445 goto deliver; 446 447 case ICMP_PARAMPROB: 448 if (code > 1) 449 goto badcode; 450 code = PRC_PARAMPROB; 451 goto deliver; 452 453 case ICMP_SOURCEQUENCH: 454 if (code) 455 goto badcode; 456 code = PRC_QUENCH; 457 deliver: 458 /* 459 * Problem with datagram; advise higher level routines. 460 */ 461 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 462 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 463 V_icmpstat.icps_badlen++; 464 goto freeit; 465 } 466 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 467 /* Discard ICMP's in response to multicast packets */ 468 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 469 goto badcode; 470 #ifdef ICMPPRINTFS 471 if (icmpprintfs) 472 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 473 #endif 474 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 475 /* 476 * XXX if the packet contains [IPv4 AH TCP], we can't make a 477 * notification to TCP layer. 478 */ 479 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 480 if (ctlfunc) 481 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 482 (void *)&icp->icmp_ip); 483 break; 484 485 badcode: 486 V_icmpstat.icps_badcode++; 487 break; 488 489 case ICMP_ECHO: 490 if (!V_icmpbmcastecho 491 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 492 V_icmpstat.icps_bmcastecho++; 493 break; 494 } 495 icp->icmp_type = ICMP_ECHOREPLY; 496 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 497 goto freeit; 498 else 499 goto reflect; 500 501 case ICMP_TSTAMP: 502 if (!V_icmpbmcastecho 503 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 504 V_icmpstat.icps_bmcasttstamp++; 505 break; 506 } 507 if (icmplen < ICMP_TSLEN) { 508 V_icmpstat.icps_badlen++; 509 break; 510 } 511 icp->icmp_type = ICMP_TSTAMPREPLY; 512 icp->icmp_rtime = iptime(); 513 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 514 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 515 goto freeit; 516 else 517 goto reflect; 518 519 case ICMP_MASKREQ: 520 if (V_icmpmaskrepl == 0) 521 break; 522 /* 523 * We are not able to respond with all ones broadcast 524 * unless we receive it over a point-to-point interface. 525 */ 526 if (icmplen < ICMP_MASKLEN) 527 break; 528 switch (ip->ip_dst.s_addr) { 529 530 case INADDR_BROADCAST: 531 case INADDR_ANY: 532 icmpdst.sin_addr = ip->ip_src; 533 break; 534 535 default: 536 icmpdst.sin_addr = ip->ip_dst; 537 } 538 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 539 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 540 if (ia == 0) 541 break; 542 if (ia->ia_ifp == 0) 543 break; 544 icp->icmp_type = ICMP_MASKREPLY; 545 if (V_icmpmaskfake == 0) 546 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 547 else 548 icp->icmp_mask = V_icmpmaskfake; 549 if (ip->ip_src.s_addr == 0) { 550 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 551 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 552 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 553 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 554 } 555 reflect: 556 ip->ip_len += hlen; /* since ip_input deducts this */ 557 V_icmpstat.icps_reflect++; 558 V_icmpstat.icps_outhist[icp->icmp_type]++; 559 icmp_reflect(m); 560 return; 561 562 case ICMP_REDIRECT: 563 if (V_log_redirect) { 564 u_long src, dst, gw; 565 566 src = ntohl(ip->ip_src.s_addr); 567 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 568 gw = ntohl(icp->icmp_gwaddr.s_addr); 569 printf("icmp redirect from %d.%d.%d.%d: " 570 "%d.%d.%d.%d => %d.%d.%d.%d\n", 571 (int)(src >> 24), (int)((src >> 16) & 0xff), 572 (int)((src >> 8) & 0xff), (int)(src & 0xff), 573 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 574 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 575 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 576 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 577 } 578 /* 579 * RFC1812 says we must ignore ICMP redirects if we 580 * are acting as router. 581 */ 582 if (V_drop_redirect || V_ipforwarding) 583 break; 584 if (code > 3) 585 goto badcode; 586 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 587 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 588 V_icmpstat.icps_badlen++; 589 break; 590 } 591 /* 592 * Short circuit routing redirects to force 593 * immediate change in the kernel's routing 594 * tables. The message is also handed to anyone 595 * listening on a raw socket (e.g. the routing 596 * daemon for use in updating its tables). 597 */ 598 icmpgw.sin_addr = ip->ip_src; 599 icmpdst.sin_addr = icp->icmp_gwaddr; 600 #ifdef ICMPPRINTFS 601 if (icmpprintfs) { 602 char buf[4 * sizeof "123"]; 603 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 604 605 printf("redirect dst %s to %s\n", 606 buf, inet_ntoa(icp->icmp_gwaddr)); 607 } 608 #endif 609 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 610 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 611 in_rtredirect((struct sockaddr *)&icmpsrc, 612 (struct sockaddr *)&icmpdst, 613 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 614 (struct sockaddr *)&icmpgw, fibnum); 615 } 616 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 617 #ifdef IPSEC 618 key_sa_routechange((struct sockaddr *)&icmpsrc); 619 #endif 620 break; 621 622 /* 623 * No kernel processing for the following; 624 * just fall through to send to raw listener. 625 */ 626 case ICMP_ECHOREPLY: 627 case ICMP_ROUTERADVERT: 628 case ICMP_ROUTERSOLICIT: 629 case ICMP_TSTAMPREPLY: 630 case ICMP_IREQREPLY: 631 case ICMP_MASKREPLY: 632 default: 633 break; 634 } 635 636 raw: 637 rip_input(m, off); 638 return; 639 640 freeit: 641 m_freem(m); 642 } 643 644 /* 645 * Reflect the ip packet back to the source 646 */ 647 static void 648 icmp_reflect(struct mbuf *m) 649 { 650 INIT_VNET_INET(curvnet); 651 struct ip *ip = mtod(m, struct ip *); 652 struct ifaddr *ifa; 653 struct ifnet *ifn; 654 struct in_ifaddr *ia; 655 struct in_addr t; 656 struct mbuf *opts = 0; 657 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 658 659 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 660 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 661 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 662 m_freem(m); /* Bad return address */ 663 V_icmpstat.icps_badaddr++; 664 goto done; /* Ip_output() will check for broadcast */ 665 } 666 667 t = ip->ip_dst; 668 ip->ip_dst = ip->ip_src; 669 670 /* 671 * Source selection for ICMP replies: 672 * 673 * If the incoming packet was addressed directly to one of our 674 * own addresses, use dst as the src for the reply. 675 */ 676 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 677 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 678 goto match; 679 /* 680 * If the incoming packet was addressed to one of our broadcast 681 * addresses, use the first non-broadcast address which corresponds 682 * to the incoming interface. 683 */ 684 if (m->m_pkthdr.rcvif != NULL && 685 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 686 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 687 if (ifa->ifa_addr->sa_family != AF_INET) 688 continue; 689 ia = ifatoia(ifa); 690 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 691 t.s_addr) 692 goto match; 693 } 694 } 695 /* 696 * If the packet was transiting through us, use the address of 697 * the interface the packet came through in. If that interface 698 * doesn't have a suitable IP address, the normal selection 699 * criteria apply. 700 */ 701 if (V_icmp_rfi && m->m_pkthdr.rcvif != NULL) { 702 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 703 if (ifa->ifa_addr->sa_family != AF_INET) 704 continue; 705 ia = ifatoia(ifa); 706 goto match; 707 } 708 } 709 /* 710 * If the incoming packet was not addressed directly to us, use 711 * designated interface for icmp replies specified by sysctl 712 * net.inet.icmp.reply_src (default not set). Otherwise continue 713 * with normal source selection. 714 */ 715 if (V_reply_src[0] != '\0' && (ifn = ifunit(V_reply_src))) { 716 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 717 if (ifa->ifa_addr->sa_family != AF_INET) 718 continue; 719 ia = ifatoia(ifa); 720 goto match; 721 } 722 } 723 /* 724 * If the packet was transiting through us, use the address of 725 * the interface that is the closest to the packet source. 726 * When we don't have a route back to the packet source, stop here 727 * and drop the packet. 728 */ 729 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 730 if (ia == NULL) { 731 m_freem(m); 732 V_icmpstat.icps_noroute++; 733 goto done; 734 } 735 match: 736 #ifdef MAC 737 mac_netinet_icmp_replyinplace(m); 738 #endif 739 t = IA_SIN(ia)->sin_addr; 740 ip->ip_src = t; 741 ip->ip_ttl = V_ip_defttl; 742 743 if (optlen > 0) { 744 register u_char *cp; 745 int opt, cnt; 746 u_int len; 747 748 /* 749 * Retrieve any source routing from the incoming packet; 750 * add on any record-route or timestamp options. 751 */ 752 cp = (u_char *) (ip + 1); 753 if ((opts = ip_srcroute(m)) == 0 && 754 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 755 opts->m_len = sizeof(struct in_addr); 756 mtod(opts, struct in_addr *)->s_addr = 0; 757 } 758 if (opts) { 759 #ifdef ICMPPRINTFS 760 if (icmpprintfs) 761 printf("icmp_reflect optlen %d rt %d => ", 762 optlen, opts->m_len); 763 #endif 764 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 765 opt = cp[IPOPT_OPTVAL]; 766 if (opt == IPOPT_EOL) 767 break; 768 if (opt == IPOPT_NOP) 769 len = 1; 770 else { 771 if (cnt < IPOPT_OLEN + sizeof(*cp)) 772 break; 773 len = cp[IPOPT_OLEN]; 774 if (len < IPOPT_OLEN + sizeof(*cp) || 775 len > cnt) 776 break; 777 } 778 /* 779 * Should check for overflow, but it "can't happen" 780 */ 781 if (opt == IPOPT_RR || opt == IPOPT_TS || 782 opt == IPOPT_SECURITY) { 783 bcopy((caddr_t)cp, 784 mtod(opts, caddr_t) + opts->m_len, len); 785 opts->m_len += len; 786 } 787 } 788 /* Terminate & pad, if necessary */ 789 cnt = opts->m_len % 4; 790 if (cnt) { 791 for (; cnt < 4; cnt++) { 792 *(mtod(opts, caddr_t) + opts->m_len) = 793 IPOPT_EOL; 794 opts->m_len++; 795 } 796 } 797 #ifdef ICMPPRINTFS 798 if (icmpprintfs) 799 printf("%d\n", opts->m_len); 800 #endif 801 } 802 /* 803 * Now strip out original options by copying rest of first 804 * mbuf's data back, and adjust the IP length. 805 */ 806 ip->ip_len -= optlen; 807 ip->ip_v = IPVERSION; 808 ip->ip_hl = 5; 809 m->m_len -= optlen; 810 if (m->m_flags & M_PKTHDR) 811 m->m_pkthdr.len -= optlen; 812 optlen += sizeof(struct ip); 813 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 814 (unsigned)(m->m_len - sizeof(struct ip))); 815 } 816 m_tag_delete_nonpersistent(m); 817 m->m_flags &= ~(M_BCAST|M_MCAST); 818 icmp_send(m, opts); 819 done: 820 if (opts) 821 (void)m_free(opts); 822 } 823 824 /* 825 * Send an icmp packet back to the ip level, 826 * after supplying a checksum. 827 */ 828 static void 829 icmp_send(struct mbuf *m, struct mbuf *opts) 830 { 831 register struct ip *ip = mtod(m, struct ip *); 832 register int hlen; 833 register struct icmp *icp; 834 835 hlen = ip->ip_hl << 2; 836 m->m_data += hlen; 837 m->m_len -= hlen; 838 icp = mtod(m, struct icmp *); 839 icp->icmp_cksum = 0; 840 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 841 m->m_data -= hlen; 842 m->m_len += hlen; 843 m->m_pkthdr.rcvif = (struct ifnet *)0; 844 #ifdef ICMPPRINTFS 845 if (icmpprintfs) { 846 char buf[4 * sizeof "123"]; 847 strcpy(buf, inet_ntoa(ip->ip_dst)); 848 printf("icmp_send dst %s src %s\n", 849 buf, inet_ntoa(ip->ip_src)); 850 } 851 #endif 852 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 853 } 854 855 /* 856 * Return milliseconds since 00:00 GMT in network format. 857 */ 858 uint32_t 859 iptime(void) 860 { 861 struct timeval atv; 862 u_long t; 863 864 getmicrotime(&atv); 865 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 866 return (htonl(t)); 867 } 868 869 /* 870 * Return the next larger or smaller MTU plateau (table from RFC 1191) 871 * given current value MTU. If DIR is less than zero, a larger plateau 872 * is returned; otherwise, a smaller value is returned. 873 */ 874 int 875 ip_next_mtu(int mtu, int dir) 876 { 877 static int mtutab[] = { 878 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 879 296, 68, 0 880 }; 881 int i, size; 882 883 size = (sizeof mtutab) / (sizeof mtutab[0]); 884 if (dir >= 0) { 885 for (i = 0; i < size; i++) 886 if (mtu > mtutab[i]) 887 return mtutab[i]; 888 } else { 889 for (i = size - 1; i >= 0; i--) 890 if (mtu < mtutab[i]) 891 return mtutab[i]; 892 if (mtu == mtutab[0]) 893 return mtutab[0]; 894 } 895 return 0; 896 } 897 898 899 /* 900 * badport_bandlim() - check for ICMP bandwidth limit 901 * 902 * Return 0 if it is ok to send an ICMP error response, -1 if we have 903 * hit our bandwidth limit and it is not ok. 904 * 905 * If icmplim is <= 0, the feature is disabled and 0 is returned. 906 * 907 * For now we separate the TCP and UDP subsystems w/ different 'which' 908 * values. We may eventually remove this separation (and simplify the 909 * code further). 910 * 911 * Note that the printing of the error message is delayed so we can 912 * properly print the icmp error rate that the system was trying to do 913 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 914 * the 'final' error, but it doesn't make sense to solve the printing 915 * delay with more complex code. 916 */ 917 918 int 919 badport_bandlim(int which) 920 { 921 INIT_VNET_INET(curvnet); 922 923 #define N(a) (sizeof (a) / sizeof (a[0])) 924 static struct rate { 925 const char *type; 926 struct timeval lasttime; 927 int curpps; 928 } rates[BANDLIM_MAX+1] = { 929 { "icmp unreach response" }, 930 { "icmp ping response" }, 931 { "icmp tstamp response" }, 932 { "closed port RST response" }, 933 { "open port RST response" }, 934 { "icmp6 unreach response" } 935 }; 936 937 /* 938 * Return ok status if feature disabled or argument out of range. 939 */ 940 if (V_icmplim > 0 && (u_int) which < N(rates)) { 941 struct rate *r = &rates[which]; 942 int opps = r->curpps; 943 944 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 945 return -1; /* discard packet */ 946 /* 947 * If we've dropped below the threshold after having 948 * rate-limited traffic print the message. This preserves 949 * the previous behaviour at the expense of added complexity. 950 */ 951 if (V_icmplim_output && opps > V_icmplim) 952 printf("Limiting %s from %d to %d packets/sec\n", 953 r->type, opps, V_icmplim); 954 } 955 return 0; /* okay to send packet */ 956 #undef N 957 } 958