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 * $FreeBSD$ 31 */ 32 33 #include "opt_ipsec.h" 34 #include "opt_mac.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/mbuf.h> 39 #include <sys/protosw.h> 40 #include <sys/socket.h> 41 #include <sys/time.h> 42 #include <sys/kernel.h> 43 #include <sys/sysctl.h> 44 45 #include <net/if.h> 46 #include <net/if_types.h> 47 #include <net/route.h> 48 49 #include <netinet/in.h> 50 #include <netinet/in_pcb.h> 51 #include <netinet/in_systm.h> 52 #include <netinet/in_var.h> 53 #include <netinet/ip.h> 54 #include <netinet/ip_icmp.h> 55 #include <netinet/ip_var.h> 56 #include <netinet/ip_options.h> 57 #include <netinet/tcp.h> 58 #include <netinet/tcp_var.h> 59 #include <netinet/tcpip.h> 60 #include <netinet/icmp_var.h> 61 62 #ifdef IPSEC 63 #include <netipsec/ipsec.h> 64 #include <netipsec/key.h> 65 #endif 66 67 #include <machine/in_cksum.h> 68 69 #include <security/mac/mac_framework.h> 70 71 /* 72 * ICMP routines: error generation, receive packet processing, and 73 * routines to turnaround packets back to the originator, and 74 * host table maintenance routines. 75 */ 76 77 struct icmpstat icmpstat; 78 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 79 &icmpstat, icmpstat, ""); 80 81 static int icmpmaskrepl = 0; 82 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 83 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); 84 85 static u_int icmpmaskfake = 0; 86 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 87 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); 88 89 static int drop_redirect = 0; 90 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 91 &drop_redirect, 0, "Ignore ICMP redirects"); 92 93 static int log_redirect = 0; 94 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 95 &log_redirect, 0, "Log ICMP redirects to the console"); 96 97 static int icmplim = 200; 98 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 99 &icmplim, 0, "Maximum number of ICMP responses per second"); 100 101 static int icmplim_output = 1; 102 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 103 &icmplim_output, 0, "Enable rate limiting of ICMP responses"); 104 105 static char reply_src[IFNAMSIZ]; 106 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 107 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 108 109 static int icmp_rfi = 0; 110 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 111 &icmp_rfi, 0, "ICMP reply from incoming interface for " 112 "non-local packets"); 113 114 static int icmp_quotelen = 8; 115 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 116 &icmp_quotelen, 0, "Number of bytes from original packet to " 117 "quote in ICMP reply"); 118 119 /* 120 * ICMP broadcast echo sysctl 121 */ 122 123 static int icmpbmcastecho = 0; 124 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 125 &icmpbmcastecho, 0, ""); 126 127 128 #ifdef ICMPPRINTFS 129 int icmpprintfs = 0; 130 #endif 131 132 static void icmp_reflect(struct mbuf *); 133 static void icmp_send(struct mbuf *, struct mbuf *); 134 135 extern struct protosw inetsw[]; 136 137 /* 138 * Generate an error packet of type error 139 * in response to bad packet ip. 140 */ 141 void 142 icmp_error(struct mbuf *n, int type, int code, n_long dest, int mtu) 143 { 144 register struct ip *oip = mtod(n, struct ip *), *nip; 145 register unsigned oiphlen = oip->ip_hl << 2; 146 register struct icmp *icp; 147 register struct mbuf *m; 148 unsigned icmplen, icmpelen, nlen; 149 150 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 151 #ifdef ICMPPRINTFS 152 if (icmpprintfs) 153 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 154 #endif 155 if (type != ICMP_REDIRECT) 156 icmpstat.icps_error++; 157 /* 158 * Don't send error: 159 * if the original packet was encrypted. 160 * if not the first fragment of message. 161 * in response to a multicast or broadcast packet. 162 * if the old packet protocol was an ICMP error message. 163 */ 164 if (n->m_flags & M_DECRYPTED) 165 goto freeit; 166 if (oip->ip_off & ~(IP_MF|IP_DF)) 167 goto freeit; 168 if (n->m_flags & (M_BCAST|M_MCAST)) 169 goto freeit; 170 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 171 n->m_len >= oiphlen + ICMP_MINLEN && 172 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 173 icmpstat.icps_oldicmp++; 174 goto freeit; 175 } 176 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 177 if (oiphlen + 8 > n->m_len) 178 goto freeit; 179 /* 180 * Calculate length to quote from original packet and 181 * prevent the ICMP mbuf from overflowing. 182 * Unfortunatly this is non-trivial since ip_forward() 183 * sends us truncated packets. 184 */ 185 nlen = m_length(n, NULL); 186 if (oip->ip_p == IPPROTO_TCP) { 187 struct tcphdr *th; 188 int tcphlen; 189 190 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 191 n->m_next == NULL) 192 goto stdreply; 193 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 194 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 195 goto freeit; 196 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 197 tcphlen = th->th_off << 2; 198 if (tcphlen < sizeof(struct tcphdr)) 199 goto freeit; 200 if (oip->ip_len < oiphlen + tcphlen) 201 goto freeit; 202 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 203 goto stdreply; 204 if (n->m_len < oiphlen + tcphlen && 205 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 206 goto freeit; 207 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen)); 208 } else 209 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen)); 210 211 icmplen = min(oiphlen + icmpelen, nlen); 212 if (icmplen < sizeof(struct ip)) 213 goto freeit; 214 215 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 216 m = m_gethdr(M_DONTWAIT, MT_DATA); 217 else 218 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 219 if (m == NULL) 220 goto freeit; 221 #ifdef MAC 222 mac_create_mbuf_netlayer(n, m); 223 #endif 224 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 225 m_align(m, ICMP_MINLEN + icmplen); 226 m->m_len = ICMP_MINLEN + icmplen; 227 228 icp = mtod(m, struct icmp *); 229 icmpstat.icps_outhist[type]++; 230 icp->icmp_type = type; 231 if (type == ICMP_REDIRECT) 232 icp->icmp_gwaddr.s_addr = dest; 233 else { 234 icp->icmp_void = 0; 235 /* 236 * The following assignments assume an overlay with the 237 * just zeroed icmp_void field. 238 */ 239 if (type == ICMP_PARAMPROB) { 240 icp->icmp_pptr = code; 241 code = 0; 242 } else if (type == ICMP_UNREACH && 243 code == ICMP_UNREACH_NEEDFRAG && mtu) { 244 icp->icmp_nextmtu = htons(mtu); 245 } 246 } 247 icp->icmp_code = code; 248 249 /* 250 * Copy the quotation into ICMP message and 251 * convert quoted IP header back to network representation. 252 */ 253 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 254 nip = &icp->icmp_ip; 255 nip->ip_len = htons(nip->ip_len); 256 nip->ip_off = htons(nip->ip_off); 257 258 /* 259 * Set up ICMP message mbuf and copy old IP header (without options 260 * in front of ICMP message. 261 * If the original mbuf was meant to bypass the firewall, the error 262 * reply should bypass as well. 263 */ 264 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 265 m->m_data -= sizeof(struct ip); 266 m->m_len += sizeof(struct ip); 267 m->m_pkthdr.len = m->m_len; 268 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 269 nip = mtod(m, struct ip *); 270 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 271 nip->ip_len = m->m_len; 272 nip->ip_v = IPVERSION; 273 nip->ip_hl = 5; 274 nip->ip_p = IPPROTO_ICMP; 275 nip->ip_tos = 0; 276 icmp_reflect(m); 277 278 freeit: 279 m_freem(n); 280 } 281 282 /* 283 * Process a received ICMP message. 284 */ 285 void 286 icmp_input(struct mbuf *m, int off) 287 { 288 struct icmp *icp; 289 struct in_ifaddr *ia; 290 struct ip *ip = mtod(m, struct ip *); 291 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 292 int hlen = off; 293 int icmplen = ip->ip_len; 294 int i, code; 295 void (*ctlfunc)(int, struct sockaddr *, void *); 296 297 /* 298 * Locate icmp structure in mbuf, and check 299 * that not corrupted and of at least minimum length. 300 */ 301 #ifdef ICMPPRINTFS 302 if (icmpprintfs) { 303 char buf[4 * sizeof "123"]; 304 strcpy(buf, inet_ntoa(ip->ip_src)); 305 printf("icmp_input from %s to %s, len %d\n", 306 buf, inet_ntoa(ip->ip_dst), icmplen); 307 } 308 #endif 309 if (icmplen < ICMP_MINLEN) { 310 icmpstat.icps_tooshort++; 311 goto freeit; 312 } 313 i = hlen + min(icmplen, ICMP_ADVLENMIN); 314 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 315 icmpstat.icps_tooshort++; 316 return; 317 } 318 ip = mtod(m, struct ip *); 319 m->m_len -= hlen; 320 m->m_data += hlen; 321 icp = mtod(m, struct icmp *); 322 if (in_cksum(m, icmplen)) { 323 icmpstat.icps_checksum++; 324 goto freeit; 325 } 326 m->m_len += hlen; 327 m->m_data -= hlen; 328 329 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 330 /* 331 * Deliver very specific ICMP type only. 332 */ 333 switch (icp->icmp_type) { 334 case ICMP_UNREACH: 335 case ICMP_TIMXCEED: 336 break; 337 default: 338 goto freeit; 339 } 340 } 341 342 #ifdef ICMPPRINTFS 343 if (icmpprintfs) 344 printf("icmp_input, type %d code %d\n", icp->icmp_type, 345 icp->icmp_code); 346 #endif 347 348 /* 349 * Message type specific processing. 350 */ 351 if (icp->icmp_type > ICMP_MAXTYPE) 352 goto raw; 353 354 /* Initialize */ 355 bzero(&icmpsrc, sizeof(icmpsrc)); 356 icmpsrc.sin_len = sizeof(struct sockaddr_in); 357 icmpsrc.sin_family = AF_INET; 358 bzero(&icmpdst, sizeof(icmpdst)); 359 icmpdst.sin_len = sizeof(struct sockaddr_in); 360 icmpdst.sin_family = AF_INET; 361 bzero(&icmpgw, sizeof(icmpgw)); 362 icmpgw.sin_len = sizeof(struct sockaddr_in); 363 icmpgw.sin_family = AF_INET; 364 365 icmpstat.icps_inhist[icp->icmp_type]++; 366 code = icp->icmp_code; 367 switch (icp->icmp_type) { 368 369 case ICMP_UNREACH: 370 switch (code) { 371 case ICMP_UNREACH_NET: 372 case ICMP_UNREACH_HOST: 373 case ICMP_UNREACH_SRCFAIL: 374 case ICMP_UNREACH_NET_UNKNOWN: 375 case ICMP_UNREACH_HOST_UNKNOWN: 376 case ICMP_UNREACH_ISOLATED: 377 case ICMP_UNREACH_TOSNET: 378 case ICMP_UNREACH_TOSHOST: 379 case ICMP_UNREACH_HOST_PRECEDENCE: 380 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 381 code = PRC_UNREACH_NET; 382 break; 383 384 case ICMP_UNREACH_NEEDFRAG: 385 code = PRC_MSGSIZE; 386 break; 387 388 /* 389 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 390 * Treat subcodes 2,3 as immediate RST 391 */ 392 case ICMP_UNREACH_PROTOCOL: 393 case ICMP_UNREACH_PORT: 394 code = PRC_UNREACH_PORT; 395 break; 396 397 case ICMP_UNREACH_NET_PROHIB: 398 case ICMP_UNREACH_HOST_PROHIB: 399 case ICMP_UNREACH_FILTER_PROHIB: 400 code = PRC_UNREACH_ADMIN_PROHIB; 401 break; 402 403 default: 404 goto badcode; 405 } 406 goto deliver; 407 408 case ICMP_TIMXCEED: 409 if (code > 1) 410 goto badcode; 411 code += PRC_TIMXCEED_INTRANS; 412 goto deliver; 413 414 case ICMP_PARAMPROB: 415 if (code > 1) 416 goto badcode; 417 code = PRC_PARAMPROB; 418 goto deliver; 419 420 case ICMP_SOURCEQUENCH: 421 if (code) 422 goto badcode; 423 code = PRC_QUENCH; 424 deliver: 425 /* 426 * Problem with datagram; advise higher level routines. 427 */ 428 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 429 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 430 icmpstat.icps_badlen++; 431 goto freeit; 432 } 433 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 434 /* Discard ICMP's in response to multicast packets */ 435 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 436 goto badcode; 437 #ifdef ICMPPRINTFS 438 if (icmpprintfs) 439 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 440 #endif 441 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 442 /* 443 * XXX if the packet contains [IPv4 AH TCP], we can't make a 444 * notification to TCP layer. 445 */ 446 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 447 if (ctlfunc) 448 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 449 (void *)&icp->icmp_ip); 450 break; 451 452 badcode: 453 icmpstat.icps_badcode++; 454 break; 455 456 case ICMP_ECHO: 457 if (!icmpbmcastecho 458 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 459 icmpstat.icps_bmcastecho++; 460 break; 461 } 462 icp->icmp_type = ICMP_ECHOREPLY; 463 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 464 goto freeit; 465 else 466 goto reflect; 467 468 case ICMP_TSTAMP: 469 if (!icmpbmcastecho 470 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 471 icmpstat.icps_bmcasttstamp++; 472 break; 473 } 474 if (icmplen < ICMP_TSLEN) { 475 icmpstat.icps_badlen++; 476 break; 477 } 478 icp->icmp_type = ICMP_TSTAMPREPLY; 479 icp->icmp_rtime = iptime(); 480 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 481 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 482 goto freeit; 483 else 484 goto reflect; 485 486 case ICMP_MASKREQ: 487 if (icmpmaskrepl == 0) 488 break; 489 /* 490 * We are not able to respond with all ones broadcast 491 * unless we receive it over a point-to-point interface. 492 */ 493 if (icmplen < ICMP_MASKLEN) 494 break; 495 switch (ip->ip_dst.s_addr) { 496 497 case INADDR_BROADCAST: 498 case INADDR_ANY: 499 icmpdst.sin_addr = ip->ip_src; 500 break; 501 502 default: 503 icmpdst.sin_addr = ip->ip_dst; 504 } 505 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 506 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 507 if (ia == 0) 508 break; 509 if (ia->ia_ifp == 0) 510 break; 511 icp->icmp_type = ICMP_MASKREPLY; 512 if (icmpmaskfake == 0) 513 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 514 else 515 icp->icmp_mask = icmpmaskfake; 516 if (ip->ip_src.s_addr == 0) { 517 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 518 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 519 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 520 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 521 } 522 reflect: 523 ip->ip_len += hlen; /* since ip_input deducts this */ 524 icmpstat.icps_reflect++; 525 icmpstat.icps_outhist[icp->icmp_type]++; 526 icmp_reflect(m); 527 return; 528 529 case ICMP_REDIRECT: 530 if (log_redirect) { 531 u_long src, dst, gw; 532 533 src = ntohl(ip->ip_src.s_addr); 534 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 535 gw = ntohl(icp->icmp_gwaddr.s_addr); 536 printf("icmp redirect from %d.%d.%d.%d: " 537 "%d.%d.%d.%d => %d.%d.%d.%d\n", 538 (int)(src >> 24), (int)((src >> 16) & 0xff), 539 (int)((src >> 8) & 0xff), (int)(src & 0xff), 540 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 541 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 542 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 543 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 544 } 545 /* 546 * RFC1812 says we must ignore ICMP redirects if we 547 * are acting as router. 548 */ 549 if (drop_redirect || ipforwarding) 550 break; 551 if (code > 3) 552 goto badcode; 553 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 554 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 555 icmpstat.icps_badlen++; 556 break; 557 } 558 /* 559 * Short circuit routing redirects to force 560 * immediate change in the kernel's routing 561 * tables. The message is also handed to anyone 562 * listening on a raw socket (e.g. the routing 563 * daemon for use in updating its tables). 564 */ 565 icmpgw.sin_addr = ip->ip_src; 566 icmpdst.sin_addr = icp->icmp_gwaddr; 567 #ifdef ICMPPRINTFS 568 if (icmpprintfs) { 569 char buf[4 * sizeof "123"]; 570 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 571 572 printf("redirect dst %s to %s\n", 573 buf, inet_ntoa(icp->icmp_gwaddr)); 574 } 575 #endif 576 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 577 rtredirect((struct sockaddr *)&icmpsrc, 578 (struct sockaddr *)&icmpdst, 579 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 580 (struct sockaddr *)&icmpgw); 581 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 582 #ifdef IPSEC 583 key_sa_routechange((struct sockaddr *)&icmpsrc); 584 #endif 585 break; 586 587 /* 588 * No kernel processing for the following; 589 * just fall through to send to raw listener. 590 */ 591 case ICMP_ECHOREPLY: 592 case ICMP_ROUTERADVERT: 593 case ICMP_ROUTERSOLICIT: 594 case ICMP_TSTAMPREPLY: 595 case ICMP_IREQREPLY: 596 case ICMP_MASKREPLY: 597 default: 598 break; 599 } 600 601 raw: 602 rip_input(m, off); 603 return; 604 605 freeit: 606 m_freem(m); 607 } 608 609 /* 610 * Reflect the ip packet back to the source 611 */ 612 static void 613 icmp_reflect(struct mbuf *m) 614 { 615 struct ip *ip = mtod(m, struct ip *); 616 struct ifaddr *ifa; 617 struct ifnet *ifn; 618 struct in_ifaddr *ia; 619 struct in_addr t; 620 struct mbuf *opts = 0; 621 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 622 623 if (!in_canforward(ip->ip_src) && 624 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 625 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 626 m_freem(m); /* Bad return address */ 627 icmpstat.icps_badaddr++; 628 goto done; /* Ip_output() will check for broadcast */ 629 } 630 t = ip->ip_dst; 631 ip->ip_dst = ip->ip_src; 632 633 /* 634 * Source selection for ICMP replies: 635 * 636 * If the incoming packet was addressed directly to one of our 637 * own addresses, use dst as the src for the reply. 638 */ 639 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 640 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 641 goto match; 642 /* 643 * If the incoming packet was addressed to one of our broadcast 644 * addresses, use the first non-broadcast address which corresponds 645 * to the incoming interface. 646 */ 647 if (m->m_pkthdr.rcvif != NULL && 648 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 649 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 650 if (ifa->ifa_addr->sa_family != AF_INET) 651 continue; 652 ia = ifatoia(ifa); 653 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 654 t.s_addr) 655 goto match; 656 } 657 } 658 /* 659 * If the packet was transiting through us, use the address of 660 * the interface the packet came through in. If that interface 661 * doesn't have a suitable IP address, the normal selection 662 * criteria apply. 663 */ 664 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) { 665 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 666 if (ifa->ifa_addr->sa_family != AF_INET) 667 continue; 668 ia = ifatoia(ifa); 669 goto match; 670 } 671 } 672 /* 673 * If the incoming packet was not addressed directly to us, use 674 * designated interface for icmp replies specified by sysctl 675 * net.inet.icmp.reply_src (default not set). Otherwise continue 676 * with normal source selection. 677 */ 678 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { 679 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { 680 if (ifa->ifa_addr->sa_family != AF_INET) 681 continue; 682 ia = ifatoia(ifa); 683 goto match; 684 } 685 } 686 /* 687 * If the packet was transiting through us, use the address of 688 * the interface that is the closest to the packet source. 689 * When we don't have a route back to the packet source, stop here 690 * and drop the packet. 691 */ 692 ia = ip_rtaddr(ip->ip_dst); 693 if (ia == NULL) { 694 m_freem(m); 695 icmpstat.icps_noroute++; 696 goto done; 697 } 698 match: 699 #ifdef MAC 700 mac_reflect_mbuf_icmp(m); 701 #endif 702 t = IA_SIN(ia)->sin_addr; 703 ip->ip_src = t; 704 ip->ip_ttl = ip_defttl; 705 706 if (optlen > 0) { 707 register u_char *cp; 708 int opt, cnt; 709 u_int len; 710 711 /* 712 * Retrieve any source routing from the incoming packet; 713 * add on any record-route or timestamp options. 714 */ 715 cp = (u_char *) (ip + 1); 716 if ((opts = ip_srcroute(m)) == 0 && 717 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 718 opts->m_len = sizeof(struct in_addr); 719 mtod(opts, struct in_addr *)->s_addr = 0; 720 } 721 if (opts) { 722 #ifdef ICMPPRINTFS 723 if (icmpprintfs) 724 printf("icmp_reflect optlen %d rt %d => ", 725 optlen, opts->m_len); 726 #endif 727 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 728 opt = cp[IPOPT_OPTVAL]; 729 if (opt == IPOPT_EOL) 730 break; 731 if (opt == IPOPT_NOP) 732 len = 1; 733 else { 734 if (cnt < IPOPT_OLEN + sizeof(*cp)) 735 break; 736 len = cp[IPOPT_OLEN]; 737 if (len < IPOPT_OLEN + sizeof(*cp) || 738 len > cnt) 739 break; 740 } 741 /* 742 * Should check for overflow, but it "can't happen" 743 */ 744 if (opt == IPOPT_RR || opt == IPOPT_TS || 745 opt == IPOPT_SECURITY) { 746 bcopy((caddr_t)cp, 747 mtod(opts, caddr_t) + opts->m_len, len); 748 opts->m_len += len; 749 } 750 } 751 /* Terminate & pad, if necessary */ 752 cnt = opts->m_len % 4; 753 if (cnt) { 754 for (; cnt < 4; cnt++) { 755 *(mtod(opts, caddr_t) + opts->m_len) = 756 IPOPT_EOL; 757 opts->m_len++; 758 } 759 } 760 #ifdef ICMPPRINTFS 761 if (icmpprintfs) 762 printf("%d\n", opts->m_len); 763 #endif 764 } 765 /* 766 * Now strip out original options by copying rest of first 767 * mbuf's data back, and adjust the IP length. 768 */ 769 ip->ip_len -= optlen; 770 ip->ip_v = IPVERSION; 771 ip->ip_hl = 5; 772 m->m_len -= optlen; 773 if (m->m_flags & M_PKTHDR) 774 m->m_pkthdr.len -= optlen; 775 optlen += sizeof(struct ip); 776 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 777 (unsigned)(m->m_len - sizeof(struct ip))); 778 } 779 m_tag_delete_nonpersistent(m); 780 m->m_flags &= ~(M_BCAST|M_MCAST); 781 icmp_send(m, opts); 782 done: 783 if (opts) 784 (void)m_free(opts); 785 } 786 787 /* 788 * Send an icmp packet back to the ip level, 789 * after supplying a checksum. 790 */ 791 static void 792 icmp_send(struct mbuf *m, struct mbuf *opts) 793 { 794 register struct ip *ip = mtod(m, struct ip *); 795 register int hlen; 796 register struct icmp *icp; 797 798 hlen = ip->ip_hl << 2; 799 m->m_data += hlen; 800 m->m_len -= hlen; 801 icp = mtod(m, struct icmp *); 802 icp->icmp_cksum = 0; 803 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 804 m->m_data -= hlen; 805 m->m_len += hlen; 806 m->m_pkthdr.rcvif = (struct ifnet *)0; 807 #ifdef ICMPPRINTFS 808 if (icmpprintfs) { 809 char buf[4 * sizeof "123"]; 810 strcpy(buf, inet_ntoa(ip->ip_dst)); 811 printf("icmp_send dst %s src %s\n", 812 buf, inet_ntoa(ip->ip_src)); 813 } 814 #endif 815 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 816 } 817 818 n_time 819 iptime(void) 820 { 821 struct timeval atv; 822 u_long t; 823 824 getmicrotime(&atv); 825 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 826 return (htonl(t)); 827 } 828 829 /* 830 * Return the next larger or smaller MTU plateau (table from RFC 1191) 831 * given current value MTU. If DIR is less than zero, a larger plateau 832 * is returned; otherwise, a smaller value is returned. 833 */ 834 int 835 ip_next_mtu(int mtu, int dir) 836 { 837 static int mtutab[] = { 838 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 839 296, 68, 0 840 }; 841 int i, size; 842 843 size = (sizeof mtutab) / (sizeof mtutab[0]); 844 if (dir >= 0) { 845 for (i = 0; i < size; i++) 846 if (mtu > mtutab[i]) 847 return mtutab[i]; 848 } else { 849 for (i = size - 1; i >= 0; i--) 850 if (mtu < mtutab[i]) 851 return mtutab[i]; 852 if (mtu == mtutab[0]) 853 return mtutab[0]; 854 } 855 return 0; 856 } 857 858 859 /* 860 * badport_bandlim() - check for ICMP bandwidth limit 861 * 862 * Return 0 if it is ok to send an ICMP error response, -1 if we have 863 * hit our bandwidth limit and it is not ok. 864 * 865 * If icmplim is <= 0, the feature is disabled and 0 is returned. 866 * 867 * For now we separate the TCP and UDP subsystems w/ different 'which' 868 * values. We may eventually remove this separation (and simplify the 869 * code further). 870 * 871 * Note that the printing of the error message is delayed so we can 872 * properly print the icmp error rate that the system was trying to do 873 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 874 * the 'final' error, but it doesn't make sense to solve the printing 875 * delay with more complex code. 876 */ 877 878 int 879 badport_bandlim(int which) 880 { 881 #define N(a) (sizeof (a) / sizeof (a[0])) 882 static struct rate { 883 const char *type; 884 struct timeval lasttime; 885 int curpps; 886 } rates[BANDLIM_MAX+1] = { 887 { "icmp unreach response" }, 888 { "icmp ping response" }, 889 { "icmp tstamp response" }, 890 { "closed port RST response" }, 891 { "open port RST response" }, 892 { "icmp6 unreach response" } 893 }; 894 895 /* 896 * Return ok status if feature disabled or argument out of range. 897 */ 898 if (icmplim > 0 && (u_int) which < N(rates)) { 899 struct rate *r = &rates[which]; 900 int opps = r->curpps; 901 902 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) 903 return -1; /* discard packet */ 904 /* 905 * If we've dropped below the threshold after having 906 * rate-limited traffic print the message. This preserves 907 * the previous behaviour at the expense of added complexity. 908 */ 909 if (icmplim_output && opps > icmplim) 910 printf("Limiting %s from %d to %d packets/sec\n", 911 r->type, opps, icmplim); 912 } 913 return 0; /* okay to send packet */ 914 #undef N 915 } 916