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 == 0) 540 break; 541 if (ia->ia_ifp == 0) 542 break; 543 icp->icmp_type = ICMP_MASKREPLY; 544 if (V_icmpmaskfake == 0) 545 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 546 else 547 icp->icmp_mask = V_icmpmaskfake; 548 if (ip->ip_src.s_addr == 0) { 549 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 550 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 551 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 552 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 553 } 554 reflect: 555 ip->ip_len += hlen; /* since ip_input deducts this */ 556 ICMPSTAT_INC(icps_reflect); 557 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 558 icmp_reflect(m); 559 return; 560 561 case ICMP_REDIRECT: 562 if (V_log_redirect) { 563 u_long src, dst, gw; 564 565 src = ntohl(ip->ip_src.s_addr); 566 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 567 gw = ntohl(icp->icmp_gwaddr.s_addr); 568 printf("icmp redirect from %d.%d.%d.%d: " 569 "%d.%d.%d.%d => %d.%d.%d.%d\n", 570 (int)(src >> 24), (int)((src >> 16) & 0xff), 571 (int)((src >> 8) & 0xff), (int)(src & 0xff), 572 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 573 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 574 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 575 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 576 } 577 /* 578 * RFC1812 says we must ignore ICMP redirects if we 579 * are acting as router. 580 */ 581 if (V_drop_redirect || V_ipforwarding) 582 break; 583 if (code > 3) 584 goto badcode; 585 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 586 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 587 ICMPSTAT_INC(icps_badlen); 588 break; 589 } 590 /* 591 * Short circuit routing redirects to force 592 * immediate change in the kernel's routing 593 * tables. The message is also handed to anyone 594 * listening on a raw socket (e.g. the routing 595 * daemon for use in updating its tables). 596 */ 597 icmpgw.sin_addr = ip->ip_src; 598 icmpdst.sin_addr = icp->icmp_gwaddr; 599 #ifdef ICMPPRINTFS 600 if (icmpprintfs) { 601 char buf[4 * sizeof "123"]; 602 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 603 604 printf("redirect dst %s to %s\n", 605 buf, inet_ntoa(icp->icmp_gwaddr)); 606 } 607 #endif 608 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 609 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 610 in_rtredirect((struct sockaddr *)&icmpsrc, 611 (struct sockaddr *)&icmpdst, 612 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 613 (struct sockaddr *)&icmpgw, fibnum); 614 } 615 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 616 #ifdef IPSEC 617 key_sa_routechange((struct sockaddr *)&icmpsrc); 618 #endif 619 break; 620 621 /* 622 * No kernel processing for the following; 623 * just fall through to send to raw listener. 624 */ 625 case ICMP_ECHOREPLY: 626 case ICMP_ROUTERADVERT: 627 case ICMP_ROUTERSOLICIT: 628 case ICMP_TSTAMPREPLY: 629 case ICMP_IREQREPLY: 630 case ICMP_MASKREPLY: 631 default: 632 break; 633 } 634 635 raw: 636 rip_input(m, off); 637 return; 638 639 freeit: 640 m_freem(m); 641 } 642 643 /* 644 * Reflect the ip packet back to the source 645 */ 646 static void 647 icmp_reflect(struct mbuf *m) 648 { 649 INIT_VNET_INET(curvnet); 650 struct ip *ip = mtod(m, struct ip *); 651 struct ifaddr *ifa; 652 struct ifnet *ifp; 653 struct in_ifaddr *ia; 654 struct in_addr t; 655 struct mbuf *opts = 0; 656 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 657 658 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 659 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 660 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 661 m_freem(m); /* Bad return address */ 662 ICMPSTAT_INC(icps_badaddr); 663 goto done; /* Ip_output() will check for broadcast */ 664 } 665 666 t = ip->ip_dst; 667 ip->ip_dst = ip->ip_src; 668 669 /* 670 * Source selection for ICMP replies: 671 * 672 * If the incoming packet was addressed directly to one of our 673 * own addresses, use dst as the src for the reply. 674 */ 675 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 676 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 677 t = IA_SIN(ia)->sin_addr; 678 goto match; 679 } 680 } 681 /* 682 * If the incoming packet was addressed to one of our broadcast 683 * addresses, use the first non-broadcast address which corresponds 684 * to the incoming interface. 685 */ 686 ifp = m->m_pkthdr.rcvif; 687 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 688 IF_ADDR_LOCK(ifp); 689 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 690 if (ifa->ifa_addr->sa_family != AF_INET) 691 continue; 692 ia = ifatoia(ifa); 693 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 694 t.s_addr) { 695 t = IA_SIN(ia)->sin_addr; 696 IF_ADDR_UNLOCK(ifp); 697 goto match; 698 } 699 } 700 IF_ADDR_UNLOCK(ifp); 701 } 702 /* 703 * If the packet was transiting through us, use the address of 704 * the interface the packet came through in. If that interface 705 * doesn't have a suitable IP address, the normal selection 706 * criteria apply. 707 */ 708 if (V_icmp_rfi && ifp != NULL) { 709 IF_ADDR_LOCK(ifp); 710 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 711 if (ifa->ifa_addr->sa_family != AF_INET) 712 continue; 713 ia = ifatoia(ifa); 714 t = IA_SIN(ia)->sin_addr; 715 IF_ADDR_UNLOCK(ifp); 716 goto match; 717 } 718 IF_ADDR_UNLOCK(ifp); 719 } 720 /* 721 * If the incoming packet was not addressed directly to us, use 722 * designated interface for icmp replies specified by sysctl 723 * net.inet.icmp.reply_src (default not set). Otherwise continue 724 * with normal source selection. 725 */ 726 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 727 IF_ADDR_LOCK(ifp); 728 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 729 if (ifa->ifa_addr->sa_family != AF_INET) 730 continue; 731 ia = ifatoia(ifa); 732 t = IA_SIN(ia)->sin_addr; 733 IF_ADDR_UNLOCK(ifp); 734 goto match; 735 } 736 IF_ADDR_UNLOCK(ifp); 737 } 738 /* 739 * If the packet was transiting through us, use the address of 740 * the interface that is the closest to the packet source. 741 * When we don't have a route back to the packet source, stop here 742 * and drop the packet. 743 */ 744 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 745 if (ia == NULL) { 746 m_freem(m); 747 ICMPSTAT_INC(icps_noroute); 748 goto done; 749 } 750 t = IA_SIN(ia)->sin_addr; 751 match: 752 #ifdef MAC 753 mac_netinet_icmp_replyinplace(m); 754 #endif 755 ip->ip_src = t; 756 ip->ip_ttl = V_ip_defttl; 757 758 if (optlen > 0) { 759 register u_char *cp; 760 int opt, cnt; 761 u_int len; 762 763 /* 764 * Retrieve any source routing from the incoming packet; 765 * add on any record-route or timestamp options. 766 */ 767 cp = (u_char *) (ip + 1); 768 if ((opts = ip_srcroute(m)) == 0 && 769 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 770 opts->m_len = sizeof(struct in_addr); 771 mtod(opts, struct in_addr *)->s_addr = 0; 772 } 773 if (opts) { 774 #ifdef ICMPPRINTFS 775 if (icmpprintfs) 776 printf("icmp_reflect optlen %d rt %d => ", 777 optlen, opts->m_len); 778 #endif 779 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 780 opt = cp[IPOPT_OPTVAL]; 781 if (opt == IPOPT_EOL) 782 break; 783 if (opt == IPOPT_NOP) 784 len = 1; 785 else { 786 if (cnt < IPOPT_OLEN + sizeof(*cp)) 787 break; 788 len = cp[IPOPT_OLEN]; 789 if (len < IPOPT_OLEN + sizeof(*cp) || 790 len > cnt) 791 break; 792 } 793 /* 794 * Should check for overflow, but it "can't happen" 795 */ 796 if (opt == IPOPT_RR || opt == IPOPT_TS || 797 opt == IPOPT_SECURITY) { 798 bcopy((caddr_t)cp, 799 mtod(opts, caddr_t) + opts->m_len, len); 800 opts->m_len += len; 801 } 802 } 803 /* Terminate & pad, if necessary */ 804 cnt = opts->m_len % 4; 805 if (cnt) { 806 for (; cnt < 4; cnt++) { 807 *(mtod(opts, caddr_t) + opts->m_len) = 808 IPOPT_EOL; 809 opts->m_len++; 810 } 811 } 812 #ifdef ICMPPRINTFS 813 if (icmpprintfs) 814 printf("%d\n", opts->m_len); 815 #endif 816 } 817 /* 818 * Now strip out original options by copying rest of first 819 * mbuf's data back, and adjust the IP length. 820 */ 821 ip->ip_len -= optlen; 822 ip->ip_v = IPVERSION; 823 ip->ip_hl = 5; 824 m->m_len -= optlen; 825 if (m->m_flags & M_PKTHDR) 826 m->m_pkthdr.len -= optlen; 827 optlen += sizeof(struct ip); 828 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 829 (unsigned)(m->m_len - sizeof(struct ip))); 830 } 831 m_tag_delete_nonpersistent(m); 832 m->m_flags &= ~(M_BCAST|M_MCAST); 833 icmp_send(m, opts); 834 done: 835 if (opts) 836 (void)m_free(opts); 837 } 838 839 /* 840 * Send an icmp packet back to the ip level, 841 * after supplying a checksum. 842 */ 843 static void 844 icmp_send(struct mbuf *m, struct mbuf *opts) 845 { 846 register struct ip *ip = mtod(m, struct ip *); 847 register int hlen; 848 register struct icmp *icp; 849 850 hlen = ip->ip_hl << 2; 851 m->m_data += hlen; 852 m->m_len -= hlen; 853 icp = mtod(m, struct icmp *); 854 icp->icmp_cksum = 0; 855 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 856 m->m_data -= hlen; 857 m->m_len += hlen; 858 m->m_pkthdr.rcvif = (struct ifnet *)0; 859 #ifdef ICMPPRINTFS 860 if (icmpprintfs) { 861 char buf[4 * sizeof "123"]; 862 strcpy(buf, inet_ntoa(ip->ip_dst)); 863 printf("icmp_send dst %s src %s\n", 864 buf, inet_ntoa(ip->ip_src)); 865 } 866 #endif 867 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 868 } 869 870 /* 871 * Return milliseconds since 00:00 GMT in network format. 872 */ 873 uint32_t 874 iptime(void) 875 { 876 struct timeval atv; 877 u_long t; 878 879 getmicrotime(&atv); 880 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 881 return (htonl(t)); 882 } 883 884 /* 885 * Return the next larger or smaller MTU plateau (table from RFC 1191) 886 * given current value MTU. If DIR is less than zero, a larger plateau 887 * is returned; otherwise, a smaller value is returned. 888 */ 889 int 890 ip_next_mtu(int mtu, int dir) 891 { 892 static int mtutab[] = { 893 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 894 296, 68, 0 895 }; 896 int i, size; 897 898 size = (sizeof mtutab) / (sizeof mtutab[0]); 899 if (dir >= 0) { 900 for (i = 0; i < size; i++) 901 if (mtu > mtutab[i]) 902 return mtutab[i]; 903 } else { 904 for (i = size - 1; i >= 0; i--) 905 if (mtu < mtutab[i]) 906 return mtutab[i]; 907 if (mtu == mtutab[0]) 908 return mtutab[0]; 909 } 910 return 0; 911 } 912 913 914 /* 915 * badport_bandlim() - check for ICMP bandwidth limit 916 * 917 * Return 0 if it is ok to send an ICMP error response, -1 if we have 918 * hit our bandwidth limit and it is not ok. 919 * 920 * If icmplim is <= 0, the feature is disabled and 0 is returned. 921 * 922 * For now we separate the TCP and UDP subsystems w/ different 'which' 923 * values. We may eventually remove this separation (and simplify the 924 * code further). 925 * 926 * Note that the printing of the error message is delayed so we can 927 * properly print the icmp error rate that the system was trying to do 928 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 929 * the 'final' error, but it doesn't make sense to solve the printing 930 * delay with more complex code. 931 */ 932 933 int 934 badport_bandlim(int which) 935 { 936 INIT_VNET_INET(curvnet); 937 938 #define N(a) (sizeof (a) / sizeof (a[0])) 939 static struct rate { 940 const char *type; 941 struct timeval lasttime; 942 int curpps; 943 } rates[BANDLIM_MAX+1] = { 944 { "icmp unreach response" }, 945 { "icmp ping response" }, 946 { "icmp tstamp response" }, 947 { "closed port RST response" }, 948 { "open port RST response" }, 949 { "icmp6 unreach response" } 950 }; 951 952 /* 953 * Return ok status if feature disabled or argument out of range. 954 */ 955 if (V_icmplim > 0 && (u_int) which < N(rates)) { 956 struct rate *r = &rates[which]; 957 int opps = r->curpps; 958 959 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 960 return -1; /* discard packet */ 961 /* 962 * If we've dropped below the threshold after having 963 * rate-limited traffic print the message. This preserves 964 * the previous behaviour at the expense of added complexity. 965 */ 966 if (V_icmplim_output && opps > V_icmplim) 967 printf("Limiting %s from %d to %d packets/sec\n", 968 r->type, opps, V_icmplim); 969 } 970 return 0; /* okay to send packet */ 971 #undef N 972 } 973