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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 34 * $FreeBSD$ 35 */ 36 37 #include "opt_ipsec.h" 38 #include "opt_mac.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/mac.h> 43 #include <sys/mbuf.h> 44 #include <sys/protosw.h> 45 #include <sys/socket.h> 46 #include <sys/time.h> 47 #include <sys/kernel.h> 48 #include <sys/sysctl.h> 49 50 #include <net/if.h> 51 #include <net/if_types.h> 52 #include <net/route.h> 53 54 #include <netinet/in.h> 55 #include <netinet/in_pcb.h> 56 #include <netinet/in_systm.h> 57 #include <netinet/in_var.h> 58 #include <netinet/ip.h> 59 #include <netinet/ip_icmp.h> 60 #include <netinet/ip_var.h> 61 #include <netinet/tcp.h> 62 #include <netinet/tcp_var.h> 63 #include <netinet/tcpip.h> 64 #include <netinet/icmp_var.h> 65 66 #ifdef IPSEC 67 #include <netinet6/ipsec.h> 68 #include <netkey/key.h> 69 #endif 70 71 #ifdef FAST_IPSEC 72 #include <netipsec/ipsec.h> 73 #include <netipsec/key.h> 74 #define IPSEC 75 #endif 76 77 #include <machine/in_cksum.h> 78 79 /* 80 * ICMP routines: error generation, receive packet processing, and 81 * routines to turnaround packets back to the originator, and 82 * host table maintenance routines. 83 */ 84 85 struct icmpstat icmpstat; 86 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 87 &icmpstat, icmpstat, ""); 88 89 static int icmpmaskrepl = 0; 90 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 91 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 92 93 static u_int icmpmaskfake = 0; 94 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 95 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 96 97 static int drop_redirect = 0; 98 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 99 &drop_redirect, 0, ""); 100 101 static int log_redirect = 0; 102 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 103 &log_redirect, 0, ""); 104 105 static int icmplim = 200; 106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 107 &icmplim, 0, ""); 108 109 static int icmplim_output = 1; 110 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 111 &icmplim_output, 0, ""); 112 113 static char reply_src[IFNAMSIZ+1]; 114 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 115 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 116 117 /* 118 * ICMP broadcast echo sysctl 119 */ 120 121 static int icmpbmcastecho = 0; 122 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 123 &icmpbmcastecho, 0, ""); 124 125 126 #ifdef ICMPPRINTFS 127 int icmpprintfs = 0; 128 #endif 129 130 static void icmp_reflect(struct mbuf *); 131 static void icmp_send(struct mbuf *, struct mbuf *); 132 static int ip_next_mtu(int, int); 133 134 extern struct protosw inetsw[]; 135 136 /* 137 * Generate an error packet of type error 138 * in response to bad packet ip. 139 */ 140 void 141 icmp_error(n, type, code, dest, destifp) 142 struct mbuf *n; 143 int type, code; 144 n_long dest; 145 struct ifnet *destifp; 146 { 147 register struct ip *oip = mtod(n, struct ip *), *nip; 148 register unsigned oiplen = oip->ip_hl << 2; 149 register struct icmp *icp; 150 register struct mbuf *m; 151 register struct m_tag *mtag; 152 unsigned icmplen; 153 154 #ifdef ICMPPRINTFS 155 if (icmpprintfs) 156 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 157 #endif 158 if (type != ICMP_REDIRECT) 159 icmpstat.icps_error++; 160 /* 161 * Don't send error if not the first fragment of message. 162 * Don't error if the old packet protocol was ICMP 163 * error message, only known informational types. 164 */ 165 if (oip->ip_off &~ (IP_MF|IP_DF)) 166 goto freeit; 167 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 168 n->m_len >= oiplen + ICMP_MINLEN && 169 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 170 icmpstat.icps_oldicmp++; 171 goto freeit; 172 } 173 /* Don't send error in response to a multicast or broadcast packet */ 174 if (n->m_flags & (M_BCAST|M_MCAST)) 175 goto freeit; 176 /* 177 * First, formulate icmp message 178 */ 179 m = m_gethdr(M_DONTWAIT, MT_HEADER); 180 if (m == NULL) 181 goto freeit; 182 #ifdef MAC 183 mac_create_mbuf_netlayer(n, m); 184 #endif 185 icmplen = min(oiplen + 8, oip->ip_len); 186 if (icmplen < sizeof(struct ip)) 187 panic("icmp_error: bad length"); 188 m->m_len = icmplen + ICMP_MINLEN; 189 MH_ALIGN(m, m->m_len); 190 icp = mtod(m, struct icmp *); 191 if ((u_int)type > ICMP_MAXTYPE) 192 panic("icmp_error"); 193 icmpstat.icps_outhist[type]++; 194 icp->icmp_type = type; 195 if (type == ICMP_REDIRECT) 196 icp->icmp_gwaddr.s_addr = dest; 197 else { 198 icp->icmp_void = 0; 199 /* 200 * The following assignments assume an overlay with the 201 * zeroed icmp_void field. 202 */ 203 if (type == ICMP_PARAMPROB) { 204 icp->icmp_pptr = code; 205 code = 0; 206 } else if (type == ICMP_UNREACH && 207 code == ICMP_UNREACH_NEEDFRAG && destifp) { 208 icp->icmp_nextmtu = htons(destifp->if_mtu); 209 } 210 } 211 212 icp->icmp_code = code; 213 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 214 nip = &icp->icmp_ip; 215 216 /* 217 * Convert fields to network representation. 218 */ 219 nip->ip_len = htons(nip->ip_len); 220 nip->ip_off = htons(nip->ip_off); 221 222 /* 223 * Now, copy old ip header (without options) 224 * in front of icmp message. 225 */ 226 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 227 panic("icmp len"); 228 m->m_data -= sizeof(struct ip); 229 m->m_len += sizeof(struct ip); 230 m->m_pkthdr.len = m->m_len; 231 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 232 nip = mtod(m, struct ip *); 233 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 234 nip->ip_len = m->m_len; 235 nip->ip_v = IPVERSION; 236 nip->ip_hl = 5; 237 nip->ip_p = IPPROTO_ICMP; 238 nip->ip_tos = 0; 239 /* 240 * XXX: Move PF_GENERATED m_tag to new packet, if it exists. 241 * This should be replaced by unified flags/tags for 242 * pf/ipfw/ipf and future pfil_hook applications. 243 */ 244 mtag = m_tag_find(n, PACKET_TAG_PF_GENERATED, NULL); 245 if (mtag != NULL) { 246 m_tag_unlink(n, mtag); 247 m_tag_prepend(m, mtag); 248 } 249 icmp_reflect(m); 250 251 freeit: 252 m_freem(n); 253 } 254 255 /* 256 * Process a received ICMP message. 257 */ 258 void 259 icmp_input(m, off) 260 struct mbuf *m; 261 int off; 262 { 263 struct icmp *icp; 264 struct in_ifaddr *ia; 265 struct ip *ip = mtod(m, struct ip *); 266 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 267 int hlen = off; 268 int icmplen = ip->ip_len; 269 int i, code; 270 void (*ctlfunc)(int, struct sockaddr *, void *); 271 272 /* 273 * Locate icmp structure in mbuf, and check 274 * that not corrupted and of at least minimum length. 275 */ 276 #ifdef ICMPPRINTFS 277 if (icmpprintfs) { 278 char buf[4 * sizeof "123"]; 279 strcpy(buf, inet_ntoa(ip->ip_src)); 280 printf("icmp_input from %s to %s, len %d\n", 281 buf, inet_ntoa(ip->ip_dst), icmplen); 282 } 283 #endif 284 if (icmplen < ICMP_MINLEN) { 285 icmpstat.icps_tooshort++; 286 goto freeit; 287 } 288 i = hlen + min(icmplen, ICMP_ADVLENMIN); 289 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 290 icmpstat.icps_tooshort++; 291 return; 292 } 293 ip = mtod(m, struct ip *); 294 m->m_len -= hlen; 295 m->m_data += hlen; 296 icp = mtod(m, struct icmp *); 297 if (in_cksum(m, icmplen)) { 298 icmpstat.icps_checksum++; 299 goto freeit; 300 } 301 m->m_len += hlen; 302 m->m_data -= hlen; 303 304 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 305 /* 306 * Deliver very specific ICMP type only. 307 */ 308 switch (icp->icmp_type) { 309 case ICMP_UNREACH: 310 case ICMP_TIMXCEED: 311 break; 312 default: 313 goto freeit; 314 } 315 } 316 317 #ifdef ICMPPRINTFS 318 if (icmpprintfs) 319 printf("icmp_input, type %d code %d\n", icp->icmp_type, 320 icp->icmp_code); 321 #endif 322 323 /* 324 * Message type specific processing. 325 */ 326 if (icp->icmp_type > ICMP_MAXTYPE) 327 goto raw; 328 329 /* Initialize */ 330 bzero(&icmpsrc, sizeof(icmpsrc)); 331 icmpsrc.sin_len = sizeof(struct sockaddr_in); 332 icmpsrc.sin_family = AF_INET; 333 bzero(&icmpdst, sizeof(icmpdst)); 334 icmpdst.sin_len = sizeof(struct sockaddr_in); 335 icmpdst.sin_family = AF_INET; 336 bzero(&icmpgw, sizeof(icmpgw)); 337 icmpgw.sin_len = sizeof(struct sockaddr_in); 338 icmpgw.sin_family = AF_INET; 339 340 icmpstat.icps_inhist[icp->icmp_type]++; 341 code = icp->icmp_code; 342 switch (icp->icmp_type) { 343 344 case ICMP_UNREACH: 345 switch (code) { 346 case ICMP_UNREACH_NET: 347 case ICMP_UNREACH_HOST: 348 case ICMP_UNREACH_SRCFAIL: 349 case ICMP_UNREACH_NET_UNKNOWN: 350 case ICMP_UNREACH_HOST_UNKNOWN: 351 case ICMP_UNREACH_ISOLATED: 352 case ICMP_UNREACH_TOSNET: 353 case ICMP_UNREACH_TOSHOST: 354 case ICMP_UNREACH_HOST_PRECEDENCE: 355 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 356 code = PRC_UNREACH_NET; 357 break; 358 359 case ICMP_UNREACH_NEEDFRAG: 360 code = PRC_MSGSIZE; 361 break; 362 363 /* 364 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 365 * Treat subcodes 2,3 as immediate RST 366 */ 367 case ICMP_UNREACH_PROTOCOL: 368 case ICMP_UNREACH_PORT: 369 code = PRC_UNREACH_PORT; 370 break; 371 372 case ICMP_UNREACH_NET_PROHIB: 373 case ICMP_UNREACH_HOST_PROHIB: 374 case ICMP_UNREACH_FILTER_PROHIB: 375 code = PRC_UNREACH_ADMIN_PROHIB; 376 break; 377 378 default: 379 goto badcode; 380 } 381 goto deliver; 382 383 case ICMP_TIMXCEED: 384 if (code > 1) 385 goto badcode; 386 code += PRC_TIMXCEED_INTRANS; 387 goto deliver; 388 389 case ICMP_PARAMPROB: 390 if (code > 1) 391 goto badcode; 392 code = PRC_PARAMPROB; 393 goto deliver; 394 395 case ICMP_SOURCEQUENCH: 396 if (code) 397 goto badcode; 398 code = PRC_QUENCH; 399 deliver: 400 /* 401 * Problem with datagram; advise higher level routines. 402 */ 403 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 404 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 405 icmpstat.icps_badlen++; 406 goto freeit; 407 } 408 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 409 /* Discard ICMP's in response to multicast packets */ 410 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 411 goto badcode; 412 #ifdef ICMPPRINTFS 413 if (icmpprintfs) 414 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 415 #endif 416 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 417 418 /* 419 * MTU discovery: 420 * If we got a needfrag and there is a host route to the 421 * original destination, and the MTU is not locked, then 422 * set the MTU in the route to the suggested new value 423 * (if given) and then notify as usual. The ULPs will 424 * notice that the MTU has changed and adapt accordingly. 425 * If no new MTU was suggested, then we guess a new one 426 * less than the current value. If the new MTU is 427 * unreasonably small (defined by sysctl tcp_minmss), then 428 * we don't update the MTU value. 429 * 430 * XXX: All this should be done in tcp_mtudisc() because 431 * the way we do it now, everyone can send us bogus ICMP 432 * MSGSIZE packets for any destination. By doing this far 433 * higher in the chain we have a matching tcp connection. 434 * Thus spoofing is much harder. However there is no easy 435 * non-hackish way to pass the new MTU up to tcp_mtudisc(). 436 * Also see next XXX regarding IPv4 AH TCP. 437 */ 438 if (code == PRC_MSGSIZE) { 439 int mtu; 440 struct in_conninfo inc; 441 442 bzero(&inc, sizeof(inc)); 443 inc.inc_flags = 0; /* IPv4 */ 444 inc.inc_faddr = icmpsrc.sin_addr; 445 446 mtu = ntohs(icp->icmp_nextmtu); 447 if (!mtu) 448 mtu = ip_next_mtu(mtu, 1); 449 450 if (mtu >= max(296, (tcp_minmss + 451 sizeof(struct tcpiphdr)))) 452 tcp_hc_updatemtu(&inc, mtu); 453 454 #ifdef DEBUG_MTUDISC 455 printf("MTU for %s reduced to %d\n", 456 inet_ntoa(icmpsrc.sin_addr), mtu); 457 #endif 458 } 459 460 /* 461 * XXX if the packet contains [IPv4 AH TCP], we can't make a 462 * notification to TCP layer. 463 */ 464 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 465 if (ctlfunc) 466 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 467 (void *)&icp->icmp_ip); 468 break; 469 470 badcode: 471 icmpstat.icps_badcode++; 472 break; 473 474 case ICMP_ECHO: 475 if (!icmpbmcastecho 476 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 477 icmpstat.icps_bmcastecho++; 478 break; 479 } 480 icp->icmp_type = ICMP_ECHOREPLY; 481 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 482 goto freeit; 483 else 484 goto reflect; 485 486 case ICMP_TSTAMP: 487 if (!icmpbmcastecho 488 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 489 icmpstat.icps_bmcasttstamp++; 490 break; 491 } 492 if (icmplen < ICMP_TSLEN) { 493 icmpstat.icps_badlen++; 494 break; 495 } 496 icp->icmp_type = ICMP_TSTAMPREPLY; 497 icp->icmp_rtime = iptime(); 498 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 499 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 500 goto freeit; 501 else 502 goto reflect; 503 504 case ICMP_MASKREQ: 505 if (icmpmaskrepl == 0) 506 break; 507 /* 508 * We are not able to respond with all ones broadcast 509 * unless we receive it over a point-to-point interface. 510 */ 511 if (icmplen < ICMP_MASKLEN) 512 break; 513 switch (ip->ip_dst.s_addr) { 514 515 case INADDR_BROADCAST: 516 case INADDR_ANY: 517 icmpdst.sin_addr = ip->ip_src; 518 break; 519 520 default: 521 icmpdst.sin_addr = ip->ip_dst; 522 } 523 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 524 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 525 if (ia == 0) 526 break; 527 if (ia->ia_ifp == 0) 528 break; 529 icp->icmp_type = ICMP_MASKREPLY; 530 if (icmpmaskfake == 0) 531 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 532 else 533 icp->icmp_mask = icmpmaskfake; 534 if (ip->ip_src.s_addr == 0) { 535 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 536 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 537 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 538 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 539 } 540 reflect: 541 ip->ip_len += hlen; /* since ip_input deducts this */ 542 icmpstat.icps_reflect++; 543 icmpstat.icps_outhist[icp->icmp_type]++; 544 icmp_reflect(m); 545 return; 546 547 case ICMP_REDIRECT: 548 if (log_redirect) { 549 u_long src, dst, gw; 550 551 src = ntohl(ip->ip_src.s_addr); 552 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 553 gw = ntohl(icp->icmp_gwaddr.s_addr); 554 printf("icmp redirect from %d.%d.%d.%d: " 555 "%d.%d.%d.%d => %d.%d.%d.%d\n", 556 (int)(src >> 24), (int)((src >> 16) & 0xff), 557 (int)((src >> 8) & 0xff), (int)(src & 0xff), 558 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 559 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 560 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 561 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 562 } 563 /* 564 * RFC1812 says we must ignore ICMP redirects if we 565 * are acting as router. 566 */ 567 if (drop_redirect || ipforwarding) 568 break; 569 if (code > 3) 570 goto badcode; 571 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 572 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 573 icmpstat.icps_badlen++; 574 break; 575 } 576 /* 577 * Short circuit routing redirects to force 578 * immediate change in the kernel's routing 579 * tables. The message is also handed to anyone 580 * listening on a raw socket (e.g. the routing 581 * daemon for use in updating its tables). 582 */ 583 icmpgw.sin_addr = ip->ip_src; 584 icmpdst.sin_addr = icp->icmp_gwaddr; 585 #ifdef ICMPPRINTFS 586 if (icmpprintfs) { 587 char buf[4 * sizeof "123"]; 588 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 589 590 printf("redirect dst %s to %s\n", 591 buf, inet_ntoa(icp->icmp_gwaddr)); 592 } 593 #endif 594 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 595 rtredirect((struct sockaddr *)&icmpsrc, 596 (struct sockaddr *)&icmpdst, 597 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 598 (struct sockaddr *)&icmpgw); 599 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 600 #ifdef IPSEC 601 key_sa_routechange((struct sockaddr *)&icmpsrc); 602 #endif 603 break; 604 605 /* 606 * No kernel processing for the following; 607 * just fall through to send to raw listener. 608 */ 609 case ICMP_ECHOREPLY: 610 case ICMP_ROUTERADVERT: 611 case ICMP_ROUTERSOLICIT: 612 case ICMP_TSTAMPREPLY: 613 case ICMP_IREQREPLY: 614 case ICMP_MASKREPLY: 615 default: 616 break; 617 } 618 619 raw: 620 rip_input(m, off); 621 return; 622 623 freeit: 624 m_freem(m); 625 } 626 627 /* 628 * Reflect the ip packet back to the source 629 */ 630 static void 631 icmp_reflect(m) 632 struct mbuf *m; 633 { 634 struct ip *ip = mtod(m, struct ip *); 635 struct ifaddr *ifa; 636 struct ifnet *ifn; 637 struct in_ifaddr *ia; 638 struct in_addr t; 639 struct mbuf *opts = 0; 640 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 641 642 if (!in_canforward(ip->ip_src) && 643 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 644 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 645 m_freem(m); /* Bad return address */ 646 icmpstat.icps_badaddr++; 647 goto done; /* Ip_output() will check for broadcast */ 648 } 649 t = ip->ip_dst; 650 ip->ip_dst = ip->ip_src; 651 652 /* 653 * Source selection for ICMP replies: 654 * 655 * If the incoming packet was addressed directly to one of our 656 * own addresses, use dst as the src for the reply. 657 */ 658 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 659 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 660 goto match; 661 /* 662 * If the incoming packet was addressed to one of our broadcast 663 * addresses, use the first non-broadcast address which corresponds 664 * to the incoming interface. 665 */ 666 if (m->m_pkthdr.rcvif != NULL && 667 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 668 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 669 if (ifa->ifa_addr->sa_family != AF_INET) 670 continue; 671 ia = ifatoia(ifa); 672 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 673 t.s_addr) 674 goto match; 675 } 676 } 677 /* 678 * If the incoming packet was not addressed directly to us, use 679 * designated interface for icmp replies specified by sysctl 680 * net.inet.icmp.reply_src (default not set). Otherwise continue 681 * with normal source selection. 682 */ 683 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 684 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 685 if (ifa->ifa_addr->sa_family != AF_INET) 686 continue; 687 ia = ifatoia(ifa); 688 goto match; 689 } 690 } 691 /* 692 * If the packet was transiting through us, use the address of 693 * the interface that is the closest to the packet source. 694 * When we don't have a route back to the packet source, stop here 695 * and drop the packet. 696 */ 697 ia = ip_rtaddr(ip->ip_dst); 698 if (ia == NULL) { 699 m_freem(m); 700 icmpstat.icps_noroute++; 701 goto done; 702 } 703 match: 704 #ifdef MAC 705 mac_reflect_mbuf_icmp(m); 706 #endif 707 t = IA_SIN(ia)->sin_addr; 708 ip->ip_src = t; 709 ip->ip_ttl = ip_defttl; 710 711 if (optlen > 0) { 712 register u_char *cp; 713 int opt, cnt; 714 u_int len; 715 716 /* 717 * Retrieve any source routing from the incoming packet; 718 * add on any record-route or timestamp options. 719 */ 720 cp = (u_char *) (ip + 1); 721 if ((opts = ip_srcroute()) == 0 && 722 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 723 opts->m_len = sizeof(struct in_addr); 724 mtod(opts, struct in_addr *)->s_addr = 0; 725 } 726 if (opts) { 727 #ifdef ICMPPRINTFS 728 if (icmpprintfs) 729 printf("icmp_reflect optlen %d rt %d => ", 730 optlen, opts->m_len); 731 #endif 732 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 733 opt = cp[IPOPT_OPTVAL]; 734 if (opt == IPOPT_EOL) 735 break; 736 if (opt == IPOPT_NOP) 737 len = 1; 738 else { 739 if (cnt < IPOPT_OLEN + sizeof(*cp)) 740 break; 741 len = cp[IPOPT_OLEN]; 742 if (len < IPOPT_OLEN + sizeof(*cp) || 743 len > cnt) 744 break; 745 } 746 /* 747 * Should check for overflow, but it "can't happen" 748 */ 749 if (opt == IPOPT_RR || opt == IPOPT_TS || 750 opt == IPOPT_SECURITY) { 751 bcopy((caddr_t)cp, 752 mtod(opts, caddr_t) + opts->m_len, len); 753 opts->m_len += len; 754 } 755 } 756 /* Terminate & pad, if necessary */ 757 cnt = opts->m_len % 4; 758 if (cnt) { 759 for (; cnt < 4; cnt++) { 760 *(mtod(opts, caddr_t) + opts->m_len) = 761 IPOPT_EOL; 762 opts->m_len++; 763 } 764 } 765 #ifdef ICMPPRINTFS 766 if (icmpprintfs) 767 printf("%d\n", opts->m_len); 768 #endif 769 } 770 /* 771 * Now strip out original options by copying rest of first 772 * mbuf's data back, and adjust the IP length. 773 */ 774 ip->ip_len -= optlen; 775 ip->ip_v = IPVERSION; 776 ip->ip_hl = 5; 777 m->m_len -= optlen; 778 if (m->m_flags & M_PKTHDR) 779 m->m_pkthdr.len -= optlen; 780 optlen += sizeof(struct ip); 781 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 782 (unsigned)(m->m_len - sizeof(struct ip))); 783 } 784 m_tag_delete_nonpersistent(m); 785 m->m_flags &= ~(M_BCAST|M_MCAST); 786 icmp_send(m, opts); 787 done: 788 if (opts) 789 (void)m_free(opts); 790 } 791 792 /* 793 * Send an icmp packet back to the ip level, 794 * after supplying a checksum. 795 */ 796 static void 797 icmp_send(m, opts) 798 register struct mbuf *m; 799 struct mbuf *opts; 800 { 801 register struct ip *ip = mtod(m, struct ip *); 802 register int hlen; 803 register struct icmp *icp; 804 805 hlen = ip->ip_hl << 2; 806 m->m_data += hlen; 807 m->m_len -= hlen; 808 icp = mtod(m, struct icmp *); 809 icp->icmp_cksum = 0; 810 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 811 m->m_data -= hlen; 812 m->m_len += hlen; 813 m->m_pkthdr.rcvif = (struct ifnet *)0; 814 #ifdef ICMPPRINTFS 815 if (icmpprintfs) { 816 char buf[4 * sizeof "123"]; 817 strcpy(buf, inet_ntoa(ip->ip_dst)); 818 printf("icmp_send dst %s src %s\n", 819 buf, inet_ntoa(ip->ip_src)); 820 } 821 #endif 822 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 823 } 824 825 n_time 826 iptime() 827 { 828 struct timeval atv; 829 u_long t; 830 831 getmicrotime(&atv); 832 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 833 return (htonl(t)); 834 } 835 836 /* 837 * Return the next larger or smaller MTU plateau (table from RFC 1191) 838 * given current value MTU. If DIR is less than zero, a larger plateau 839 * is returned; otherwise, a smaller value is returned. 840 */ 841 static int 842 ip_next_mtu(mtu, dir) 843 int mtu; 844 int dir; 845 { 846 static int mtutab[] = { 847 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 848 68, 0 849 }; 850 int i; 851 852 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 853 if (mtu >= mtutab[i]) 854 break; 855 } 856 857 if (dir < 0) { 858 if (i == 0) { 859 return 0; 860 } else { 861 return mtutab[i - 1]; 862 } 863 } else { 864 if (mtutab[i] == 0) { 865 return 0; 866 } else if(mtu > mtutab[i]) { 867 return mtutab[i]; 868 } else { 869 return mtutab[i + 1]; 870 } 871 } 872 } 873 874 875 /* 876 * badport_bandlim() - check for ICMP bandwidth limit 877 * 878 * Return 0 if it is ok to send an ICMP error response, -1 if we have 879 * hit our bandwidth limit and it is not ok. 880 * 881 * If icmplim is <= 0, the feature is disabled and 0 is returned. 882 * 883 * For now we separate the TCP and UDP subsystems w/ different 'which' 884 * values. We may eventually remove this separation (and simplify the 885 * code further). 886 * 887 * Note that the printing of the error message is delayed so we can 888 * properly print the icmp error rate that the system was trying to do 889 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 890 * the 'final' error, but it doesn't make sense to solve the printing 891 * delay with more complex code. 892 */ 893 894 int 895 badport_bandlim(int which) 896 { 897 #define N(a) (sizeof (a) / sizeof (a[0])) 898 static struct rate { 899 const char *type; 900 struct timeval lasttime; 901 int curpps;; 902 } rates[BANDLIM_MAX+1] = { 903 { "icmp unreach response" }, 904 { "icmp ping response" }, 905 { "icmp tstamp response" }, 906 { "closed port RST response" }, 907 { "open port RST response" } 908 }; 909 910 /* 911 * Return ok status if feature disabled or argument out of range. 912 */ 913 if (icmplim > 0 && (u_int) which < N(rates)) { 914 struct rate *r = &rates[which]; 915 int opps = r->curpps; 916 917 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 918 return -1; /* discard packet */ 919 /* 920 * If we've dropped below the threshold after having 921 * rate-limited traffic print the message. This preserves 922 * the previous behaviour at the expense of added complexity. 923 */ 924 if (icmplim_output && opps > icmplim) 925 printf("Limiting %s from %d to %d packets/sec\n", 926 r->type, opps, icmplim); 927 } 928 return 0; /* okay to send packet */ 929 #undef N 930 } 931