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_inet.h" 36 #include "opt_ipsec.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/syslog.h> 47 48 #include <net/if.h> 49 #include <net/if_types.h> 50 #include <net/route.h> 51 #include <net/vnet.h> 52 53 #include <netinet/in.h> 54 #include <netinet/in_pcb.h> 55 #include <netinet/in_systm.h> 56 #include <netinet/in_var.h> 57 #include <netinet/ip.h> 58 #include <netinet/ip_icmp.h> 59 #include <netinet/ip_var.h> 60 #include <netinet/ip_options.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 INET 67 #ifdef IPSEC 68 #include <netipsec/ipsec.h> 69 #include <netipsec/key.h> 70 #endif 71 72 #include <machine/in_cksum.h> 73 74 #include <security/mac/mac_framework.h> 75 #endif /* INET */ 76 77 /* 78 * ICMP routines: error generation, receive packet processing, and 79 * routines to turnaround packets back to the originator, and 80 * host table maintenance routines. 81 */ 82 static VNET_DEFINE(int, icmplim) = 200; 83 #define V_icmplim VNET(icmplim) 84 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 85 &VNET_NAME(icmplim), 0, 86 "Maximum number of ICMP responses per second"); 87 88 static VNET_DEFINE(int, icmplim_output) = 1; 89 #define V_icmplim_output VNET(icmplim_output) 90 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 91 &VNET_NAME(icmplim_output), 0, 92 "Enable rate limiting of ICMP responses"); 93 94 #ifdef INET 95 VNET_DEFINE(struct icmpstat, icmpstat); 96 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 97 &VNET_NAME(icmpstat), icmpstat, ""); 98 99 static VNET_DEFINE(int, icmpmaskrepl) = 0; 100 #define V_icmpmaskrepl VNET(icmpmaskrepl) 101 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 102 &VNET_NAME(icmpmaskrepl), 0, 103 "Reply to ICMP Address Mask Request packets."); 104 105 static VNET_DEFINE(u_int, icmpmaskfake) = 0; 106 #define V_icmpmaskfake VNET(icmpmaskfake) 107 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 108 &VNET_NAME(icmpmaskfake), 0, 109 "Fake reply to ICMP Address Mask Request packets."); 110 111 static VNET_DEFINE(int, drop_redirect) = 0; 112 #define V_drop_redirect VNET(drop_redirect) 113 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 114 &VNET_NAME(drop_redirect), 0, 115 "Ignore ICMP redirects"); 116 117 static VNET_DEFINE(int, log_redirect) = 0; 118 #define V_log_redirect VNET(log_redirect) 119 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 120 &VNET_NAME(log_redirect), 0, 121 "Log ICMP redirects to the console"); 122 123 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 124 #define V_reply_src VNET(reply_src) 125 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 126 &VNET_NAME(reply_src), IFNAMSIZ, 127 "icmp reply source for non-local packets."); 128 129 static VNET_DEFINE(int, icmp_rfi) = 0; 130 #define V_icmp_rfi VNET(icmp_rfi) 131 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 132 &VNET_NAME(icmp_rfi), 0, 133 "ICMP reply from incoming interface for non-local packets"); 134 135 static VNET_DEFINE(int, icmp_quotelen) = 8; 136 #define V_icmp_quotelen VNET(icmp_quotelen) 137 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 138 &VNET_NAME(icmp_quotelen), 0, 139 "Number of bytes from original packet to quote in ICMP reply"); 140 141 /* 142 * ICMP broadcast echo sysctl 143 */ 144 static VNET_DEFINE(int, icmpbmcastecho) = 0; 145 #define V_icmpbmcastecho VNET(icmpbmcastecho) 146 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 147 &VNET_NAME(icmpbmcastecho), 0, 148 ""); 149 150 151 #ifdef ICMPPRINTFS 152 int icmpprintfs = 0; 153 #endif 154 155 static void icmp_reflect(struct mbuf *); 156 static void icmp_send(struct mbuf *, struct mbuf *); 157 158 extern struct protosw inetsw[]; 159 160 /* 161 * Kernel module interface for updating icmpstat. The argument is an index 162 * into icmpstat treated as an array of u_long. While this encodes the 163 * general layout of icmpstat into the caller, it doesn't encode its 164 * location, so that future changes to add, for example, per-CPU stats 165 * support won't cause binary compatibility problems for kernel modules. 166 */ 167 void 168 kmod_icmpstat_inc(int statnum) 169 { 170 171 (*((u_long *)&V_icmpstat + statnum))++; 172 } 173 174 /* 175 * Generate an error packet of type error 176 * in response to bad packet ip. 177 */ 178 void 179 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 180 { 181 register struct ip *oip = mtod(n, struct ip *), *nip; 182 register unsigned oiphlen = oip->ip_hl << 2; 183 register struct icmp *icp; 184 register struct mbuf *m; 185 unsigned icmplen, icmpelen, nlen; 186 187 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 188 #ifdef ICMPPRINTFS 189 if (icmpprintfs) 190 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 191 #endif 192 if (type != ICMP_REDIRECT) 193 ICMPSTAT_INC(icps_error); 194 /* 195 * Don't send error: 196 * if the original packet was encrypted. 197 * if not the first fragment of message. 198 * in response to a multicast or broadcast packet. 199 * if the old packet protocol was an ICMP error message. 200 */ 201 if (n->m_flags & M_DECRYPTED) 202 goto freeit; 203 if (oip->ip_off & ~(IP_MF|IP_DF)) 204 goto freeit; 205 if (n->m_flags & (M_BCAST|M_MCAST)) 206 goto freeit; 207 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 208 n->m_len >= oiphlen + ICMP_MINLEN && 209 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 210 ICMPSTAT_INC(icps_oldicmp); 211 goto freeit; 212 } 213 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 214 if (oiphlen + 8 > n->m_len) 215 goto freeit; 216 /* 217 * Calculate length to quote from original packet and 218 * prevent the ICMP mbuf from overflowing. 219 * Unfortunatly this is non-trivial since ip_forward() 220 * sends us truncated packets. 221 */ 222 nlen = m_length(n, NULL); 223 if (oip->ip_p == IPPROTO_TCP) { 224 struct tcphdr *th; 225 int tcphlen; 226 227 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 228 n->m_next == NULL) 229 goto stdreply; 230 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 231 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 232 goto freeit; 233 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 234 tcphlen = th->th_off << 2; 235 if (tcphlen < sizeof(struct tcphdr)) 236 goto freeit; 237 if (oip->ip_len < oiphlen + tcphlen) 238 goto freeit; 239 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 240 goto stdreply; 241 if (n->m_len < oiphlen + tcphlen && 242 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 243 goto freeit; 244 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 245 } else 246 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 247 248 icmplen = min(oiphlen + icmpelen, nlen); 249 if (icmplen < sizeof(struct ip)) 250 goto freeit; 251 252 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 253 m = m_gethdr(M_DONTWAIT, MT_DATA); 254 else 255 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 256 if (m == NULL) 257 goto freeit; 258 #ifdef MAC 259 mac_netinet_icmp_reply(n, m); 260 #endif 261 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 262 m_align(m, ICMP_MINLEN + icmplen); 263 m->m_len = ICMP_MINLEN + icmplen; 264 265 /* XXX MRT make the outgoing packet use the same FIB 266 * that was associated with the incoming packet 267 */ 268 M_SETFIB(m, M_GETFIB(n)); 269 icp = mtod(m, struct icmp *); 270 ICMPSTAT_INC(icps_outhist[type]); 271 icp->icmp_type = type; 272 if (type == ICMP_REDIRECT) 273 icp->icmp_gwaddr.s_addr = dest; 274 else { 275 icp->icmp_void = 0; 276 /* 277 * The following assignments assume an overlay with the 278 * just zeroed icmp_void field. 279 */ 280 if (type == ICMP_PARAMPROB) { 281 icp->icmp_pptr = code; 282 code = 0; 283 } else if (type == ICMP_UNREACH && 284 code == ICMP_UNREACH_NEEDFRAG && mtu) { 285 icp->icmp_nextmtu = htons(mtu); 286 } 287 } 288 icp->icmp_code = code; 289 290 /* 291 * Copy the quotation into ICMP message and 292 * convert quoted IP header back to network representation. 293 */ 294 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 295 nip = &icp->icmp_ip; 296 nip->ip_len = htons(nip->ip_len); 297 nip->ip_off = htons(nip->ip_off); 298 299 /* 300 * Set up ICMP message mbuf and copy old IP header (without options 301 * in front of ICMP message. 302 * If the original mbuf was meant to bypass the firewall, the error 303 * reply should bypass as well. 304 */ 305 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 306 m->m_data -= sizeof(struct ip); 307 m->m_len += sizeof(struct ip); 308 m->m_pkthdr.len = m->m_len; 309 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 310 nip = mtod(m, struct ip *); 311 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 312 nip->ip_len = m->m_len; 313 nip->ip_v = IPVERSION; 314 nip->ip_hl = 5; 315 nip->ip_p = IPPROTO_ICMP; 316 nip->ip_tos = 0; 317 icmp_reflect(m); 318 319 freeit: 320 m_freem(n); 321 } 322 323 /* 324 * Process a received ICMP message. 325 */ 326 void 327 icmp_input(struct mbuf *m, int off) 328 { 329 struct icmp *icp; 330 struct in_ifaddr *ia; 331 struct ip *ip = mtod(m, struct ip *); 332 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 333 int hlen = off; 334 int icmplen = ip->ip_len; 335 int i, code; 336 void (*ctlfunc)(int, struct sockaddr *, void *); 337 int fibnum; 338 339 /* 340 * Locate icmp structure in mbuf, and check 341 * that not corrupted and of at least minimum length. 342 */ 343 #ifdef ICMPPRINTFS 344 if (icmpprintfs) { 345 char buf[4 * sizeof "123"]; 346 strcpy(buf, inet_ntoa(ip->ip_src)); 347 printf("icmp_input from %s to %s, len %d\n", 348 buf, inet_ntoa(ip->ip_dst), icmplen); 349 } 350 #endif 351 if (icmplen < ICMP_MINLEN) { 352 ICMPSTAT_INC(icps_tooshort); 353 goto freeit; 354 } 355 i = hlen + min(icmplen, ICMP_ADVLENMIN); 356 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 357 ICMPSTAT_INC(icps_tooshort); 358 return; 359 } 360 ip = mtod(m, struct ip *); 361 m->m_len -= hlen; 362 m->m_data += hlen; 363 icp = mtod(m, struct icmp *); 364 if (in_cksum(m, icmplen)) { 365 ICMPSTAT_INC(icps_checksum); 366 goto freeit; 367 } 368 m->m_len += hlen; 369 m->m_data -= hlen; 370 371 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 372 /* 373 * Deliver very specific ICMP type only. 374 */ 375 switch (icp->icmp_type) { 376 case ICMP_UNREACH: 377 case ICMP_TIMXCEED: 378 break; 379 default: 380 goto freeit; 381 } 382 } 383 384 #ifdef ICMPPRINTFS 385 if (icmpprintfs) 386 printf("icmp_input, type %d code %d\n", icp->icmp_type, 387 icp->icmp_code); 388 #endif 389 390 /* 391 * Message type specific processing. 392 */ 393 if (icp->icmp_type > ICMP_MAXTYPE) 394 goto raw; 395 396 /* Initialize */ 397 bzero(&icmpsrc, sizeof(icmpsrc)); 398 icmpsrc.sin_len = sizeof(struct sockaddr_in); 399 icmpsrc.sin_family = AF_INET; 400 bzero(&icmpdst, sizeof(icmpdst)); 401 icmpdst.sin_len = sizeof(struct sockaddr_in); 402 icmpdst.sin_family = AF_INET; 403 bzero(&icmpgw, sizeof(icmpgw)); 404 icmpgw.sin_len = sizeof(struct sockaddr_in); 405 icmpgw.sin_family = AF_INET; 406 407 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 408 code = icp->icmp_code; 409 switch (icp->icmp_type) { 410 411 case ICMP_UNREACH: 412 switch (code) { 413 case ICMP_UNREACH_NET: 414 case ICMP_UNREACH_HOST: 415 case ICMP_UNREACH_SRCFAIL: 416 case ICMP_UNREACH_NET_UNKNOWN: 417 case ICMP_UNREACH_HOST_UNKNOWN: 418 case ICMP_UNREACH_ISOLATED: 419 case ICMP_UNREACH_TOSNET: 420 case ICMP_UNREACH_TOSHOST: 421 case ICMP_UNREACH_HOST_PRECEDENCE: 422 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 423 code = PRC_UNREACH_NET; 424 break; 425 426 case ICMP_UNREACH_NEEDFRAG: 427 code = PRC_MSGSIZE; 428 break; 429 430 /* 431 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 432 * Treat subcodes 2,3 as immediate RST 433 */ 434 case ICMP_UNREACH_PROTOCOL: 435 case ICMP_UNREACH_PORT: 436 code = PRC_UNREACH_PORT; 437 break; 438 439 case ICMP_UNREACH_NET_PROHIB: 440 case ICMP_UNREACH_HOST_PROHIB: 441 case ICMP_UNREACH_FILTER_PROHIB: 442 code = PRC_UNREACH_ADMIN_PROHIB; 443 break; 444 445 default: 446 goto badcode; 447 } 448 goto deliver; 449 450 case ICMP_TIMXCEED: 451 if (code > 1) 452 goto badcode; 453 code += PRC_TIMXCEED_INTRANS; 454 goto deliver; 455 456 case ICMP_PARAMPROB: 457 if (code > 1) 458 goto badcode; 459 code = PRC_PARAMPROB; 460 goto deliver; 461 462 case ICMP_SOURCEQUENCH: 463 if (code) 464 goto badcode; 465 code = PRC_QUENCH; 466 deliver: 467 /* 468 * Problem with datagram; advise higher level routines. 469 */ 470 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 471 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 472 ICMPSTAT_INC(icps_badlen); 473 goto freeit; 474 } 475 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 476 /* Discard ICMP's in response to multicast packets */ 477 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 478 goto badcode; 479 #ifdef ICMPPRINTFS 480 if (icmpprintfs) 481 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 482 #endif 483 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 484 /* 485 * XXX if the packet contains [IPv4 AH TCP], we can't make a 486 * notification to TCP layer. 487 */ 488 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 489 if (ctlfunc) 490 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 491 (void *)&icp->icmp_ip); 492 break; 493 494 badcode: 495 ICMPSTAT_INC(icps_badcode); 496 break; 497 498 case ICMP_ECHO: 499 if (!V_icmpbmcastecho 500 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 501 ICMPSTAT_INC(icps_bmcastecho); 502 break; 503 } 504 icp->icmp_type = ICMP_ECHOREPLY; 505 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 506 goto freeit; 507 else 508 goto reflect; 509 510 case ICMP_TSTAMP: 511 if (!V_icmpbmcastecho 512 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 513 ICMPSTAT_INC(icps_bmcasttstamp); 514 break; 515 } 516 if (icmplen < ICMP_TSLEN) { 517 ICMPSTAT_INC(icps_badlen); 518 break; 519 } 520 icp->icmp_type = ICMP_TSTAMPREPLY; 521 icp->icmp_rtime = iptime(); 522 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 523 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 524 goto freeit; 525 else 526 goto reflect; 527 528 case ICMP_MASKREQ: 529 if (V_icmpmaskrepl == 0) 530 break; 531 /* 532 * We are not able to respond with all ones broadcast 533 * unless we receive it over a point-to-point interface. 534 */ 535 if (icmplen < ICMP_MASKLEN) 536 break; 537 switch (ip->ip_dst.s_addr) { 538 539 case INADDR_BROADCAST: 540 case INADDR_ANY: 541 icmpdst.sin_addr = ip->ip_src; 542 break; 543 544 default: 545 icmpdst.sin_addr = ip->ip_dst; 546 } 547 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 548 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 549 if (ia == NULL) 550 break; 551 if (ia->ia_ifp == NULL) { 552 ifa_free(&ia->ia_ifa); 553 break; 554 } 555 icp->icmp_type = ICMP_MASKREPLY; 556 if (V_icmpmaskfake == 0) 557 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 558 else 559 icp->icmp_mask = V_icmpmaskfake; 560 if (ip->ip_src.s_addr == 0) { 561 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 562 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 563 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 564 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 565 } 566 ifa_free(&ia->ia_ifa); 567 reflect: 568 ip->ip_len += hlen; /* since ip_input deducts this */ 569 ICMPSTAT_INC(icps_reflect); 570 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 571 icmp_reflect(m); 572 return; 573 574 case ICMP_REDIRECT: 575 if (V_log_redirect) { 576 u_long src, dst, gw; 577 578 src = ntohl(ip->ip_src.s_addr); 579 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 580 gw = ntohl(icp->icmp_gwaddr.s_addr); 581 printf("icmp redirect from %d.%d.%d.%d: " 582 "%d.%d.%d.%d => %d.%d.%d.%d\n", 583 (int)(src >> 24), (int)((src >> 16) & 0xff), 584 (int)((src >> 8) & 0xff), (int)(src & 0xff), 585 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 586 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 587 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 588 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 589 } 590 /* 591 * RFC1812 says we must ignore ICMP redirects if we 592 * are acting as router. 593 */ 594 if (V_drop_redirect || V_ipforwarding) 595 break; 596 if (code > 3) 597 goto badcode; 598 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 599 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 600 ICMPSTAT_INC(icps_badlen); 601 break; 602 } 603 /* 604 * Short circuit routing redirects to force 605 * immediate change in the kernel's routing 606 * tables. The message is also handed to anyone 607 * listening on a raw socket (e.g. the routing 608 * daemon for use in updating its tables). 609 */ 610 icmpgw.sin_addr = ip->ip_src; 611 icmpdst.sin_addr = icp->icmp_gwaddr; 612 #ifdef ICMPPRINTFS 613 if (icmpprintfs) { 614 char buf[4 * sizeof "123"]; 615 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 616 617 printf("redirect dst %s to %s\n", 618 buf, inet_ntoa(icp->icmp_gwaddr)); 619 } 620 #endif 621 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 622 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 623 in_rtredirect((struct sockaddr *)&icmpsrc, 624 (struct sockaddr *)&icmpdst, 625 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 626 (struct sockaddr *)&icmpgw, fibnum); 627 } 628 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 629 #ifdef IPSEC 630 key_sa_routechange((struct sockaddr *)&icmpsrc); 631 #endif 632 break; 633 634 /* 635 * No kernel processing for the following; 636 * just fall through to send to raw listener. 637 */ 638 case ICMP_ECHOREPLY: 639 case ICMP_ROUTERADVERT: 640 case ICMP_ROUTERSOLICIT: 641 case ICMP_TSTAMPREPLY: 642 case ICMP_IREQREPLY: 643 case ICMP_MASKREPLY: 644 default: 645 break; 646 } 647 648 raw: 649 rip_input(m, off); 650 return; 651 652 freeit: 653 m_freem(m); 654 } 655 656 /* 657 * Reflect the ip packet back to the source 658 */ 659 static void 660 icmp_reflect(struct mbuf *m) 661 { 662 struct ip *ip = mtod(m, struct ip *); 663 struct ifaddr *ifa; 664 struct ifnet *ifp; 665 struct in_ifaddr *ia; 666 struct in_addr t; 667 struct mbuf *opts = 0; 668 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 669 670 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 671 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 672 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 673 m_freem(m); /* Bad return address */ 674 ICMPSTAT_INC(icps_badaddr); 675 goto done; /* Ip_output() will check for broadcast */ 676 } 677 678 m_addr_changed(m); 679 680 t = ip->ip_dst; 681 ip->ip_dst = ip->ip_src; 682 683 /* 684 * Source selection for ICMP replies: 685 * 686 * If the incoming packet was addressed directly to one of our 687 * own addresses, use dst as the src for the reply. 688 */ 689 IN_IFADDR_RLOCK(); 690 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 691 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 692 t = IA_SIN(ia)->sin_addr; 693 IN_IFADDR_RUNLOCK(); 694 goto match; 695 } 696 } 697 IN_IFADDR_RUNLOCK(); 698 699 /* 700 * If the incoming packet was addressed to one of our broadcast 701 * addresses, use the first non-broadcast address which corresponds 702 * to the incoming interface. 703 */ 704 ifp = m->m_pkthdr.rcvif; 705 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 706 IF_ADDR_LOCK(ifp); 707 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 708 if (ifa->ifa_addr->sa_family != AF_INET) 709 continue; 710 ia = ifatoia(ifa); 711 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 712 t.s_addr) { 713 t = IA_SIN(ia)->sin_addr; 714 IF_ADDR_UNLOCK(ifp); 715 goto match; 716 } 717 } 718 IF_ADDR_UNLOCK(ifp); 719 } 720 /* 721 * If the packet was transiting through us, use the address of 722 * the interface the packet came through in. If that interface 723 * doesn't have a suitable IP address, the normal selection 724 * criteria apply. 725 */ 726 if (V_icmp_rfi && ifp != NULL) { 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 incoming packet was not addressed directly to us, use 740 * designated interface for icmp replies specified by sysctl 741 * net.inet.icmp.reply_src (default not set). Otherwise continue 742 * with normal source selection. 743 */ 744 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 745 IF_ADDR_LOCK(ifp); 746 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 747 if (ifa->ifa_addr->sa_family != AF_INET) 748 continue; 749 ia = ifatoia(ifa); 750 t = IA_SIN(ia)->sin_addr; 751 IF_ADDR_UNLOCK(ifp); 752 goto match; 753 } 754 IF_ADDR_UNLOCK(ifp); 755 } 756 /* 757 * If the packet was transiting through us, use the address of 758 * the interface that is the closest to the packet source. 759 * When we don't have a route back to the packet source, stop here 760 * and drop the packet. 761 */ 762 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 763 if (ia == NULL) { 764 m_freem(m); 765 ICMPSTAT_INC(icps_noroute); 766 goto done; 767 } 768 t = IA_SIN(ia)->sin_addr; 769 ifa_free(&ia->ia_ifa); 770 match: 771 #ifdef MAC 772 mac_netinet_icmp_replyinplace(m); 773 #endif 774 ip->ip_src = t; 775 ip->ip_ttl = V_ip_defttl; 776 777 if (optlen > 0) { 778 register u_char *cp; 779 int opt, cnt; 780 u_int len; 781 782 /* 783 * Retrieve any source routing from the incoming packet; 784 * add on any record-route or timestamp options. 785 */ 786 cp = (u_char *) (ip + 1); 787 if ((opts = ip_srcroute(m)) == 0 && 788 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 789 opts->m_len = sizeof(struct in_addr); 790 mtod(opts, struct in_addr *)->s_addr = 0; 791 } 792 if (opts) { 793 #ifdef ICMPPRINTFS 794 if (icmpprintfs) 795 printf("icmp_reflect optlen %d rt %d => ", 796 optlen, opts->m_len); 797 #endif 798 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 799 opt = cp[IPOPT_OPTVAL]; 800 if (opt == IPOPT_EOL) 801 break; 802 if (opt == IPOPT_NOP) 803 len = 1; 804 else { 805 if (cnt < IPOPT_OLEN + sizeof(*cp)) 806 break; 807 len = cp[IPOPT_OLEN]; 808 if (len < IPOPT_OLEN + sizeof(*cp) || 809 len > cnt) 810 break; 811 } 812 /* 813 * Should check for overflow, but it "can't happen" 814 */ 815 if (opt == IPOPT_RR || opt == IPOPT_TS || 816 opt == IPOPT_SECURITY) { 817 bcopy((caddr_t)cp, 818 mtod(opts, caddr_t) + opts->m_len, len); 819 opts->m_len += len; 820 } 821 } 822 /* Terminate & pad, if necessary */ 823 cnt = opts->m_len % 4; 824 if (cnt) { 825 for (; cnt < 4; cnt++) { 826 *(mtod(opts, caddr_t) + opts->m_len) = 827 IPOPT_EOL; 828 opts->m_len++; 829 } 830 } 831 #ifdef ICMPPRINTFS 832 if (icmpprintfs) 833 printf("%d\n", opts->m_len); 834 #endif 835 } 836 /* 837 * Now strip out original options by copying rest of first 838 * mbuf's data back, and adjust the IP length. 839 */ 840 ip->ip_len -= optlen; 841 ip->ip_v = IPVERSION; 842 ip->ip_hl = 5; 843 m->m_len -= optlen; 844 if (m->m_flags & M_PKTHDR) 845 m->m_pkthdr.len -= optlen; 846 optlen += sizeof(struct ip); 847 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 848 (unsigned)(m->m_len - sizeof(struct ip))); 849 } 850 m_tag_delete_nonpersistent(m); 851 m->m_flags &= ~(M_BCAST|M_MCAST); 852 icmp_send(m, opts); 853 done: 854 if (opts) 855 (void)m_free(opts); 856 } 857 858 /* 859 * Send an icmp packet back to the ip level, 860 * after supplying a checksum. 861 */ 862 static void 863 icmp_send(struct mbuf *m, struct mbuf *opts) 864 { 865 register struct ip *ip = mtod(m, struct ip *); 866 register int hlen; 867 register struct icmp *icp; 868 869 hlen = ip->ip_hl << 2; 870 m->m_data += hlen; 871 m->m_len -= hlen; 872 icp = mtod(m, struct icmp *); 873 icp->icmp_cksum = 0; 874 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 875 m->m_data -= hlen; 876 m->m_len += hlen; 877 m->m_pkthdr.rcvif = (struct ifnet *)0; 878 #ifdef ICMPPRINTFS 879 if (icmpprintfs) { 880 char buf[4 * sizeof "123"]; 881 strcpy(buf, inet_ntoa(ip->ip_dst)); 882 printf("icmp_send dst %s src %s\n", 883 buf, inet_ntoa(ip->ip_src)); 884 } 885 #endif 886 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 887 } 888 889 /* 890 * Return milliseconds since 00:00 GMT in network format. 891 */ 892 uint32_t 893 iptime(void) 894 { 895 struct timeval atv; 896 u_long t; 897 898 getmicrotime(&atv); 899 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 900 return (htonl(t)); 901 } 902 903 /* 904 * Return the next larger or smaller MTU plateau (table from RFC 1191) 905 * given current value MTU. If DIR is less than zero, a larger plateau 906 * is returned; otherwise, a smaller value is returned. 907 */ 908 int 909 ip_next_mtu(int mtu, int dir) 910 { 911 static int mtutab[] = { 912 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 913 296, 68, 0 914 }; 915 int i, size; 916 917 size = (sizeof mtutab) / (sizeof mtutab[0]); 918 if (dir >= 0) { 919 for (i = 0; i < size; i++) 920 if (mtu > mtutab[i]) 921 return mtutab[i]; 922 } else { 923 for (i = size - 1; i >= 0; i--) 924 if (mtu < mtutab[i]) 925 return mtutab[i]; 926 if (mtu == mtutab[0]) 927 return mtutab[0]; 928 } 929 return 0; 930 } 931 #endif /* INET */ 932 933 934 /* 935 * badport_bandlim() - check for ICMP bandwidth limit 936 * 937 * Return 0 if it is ok to send an ICMP error response, -1 if we have 938 * hit our bandwidth limit and it is not ok. 939 * 940 * If icmplim is <= 0, the feature is disabled and 0 is returned. 941 * 942 * For now we separate the TCP and UDP subsystems w/ different 'which' 943 * values. We may eventually remove this separation (and simplify the 944 * code further). 945 * 946 * Note that the printing of the error message is delayed so we can 947 * properly print the icmp error rate that the system was trying to do 948 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 949 * the 'final' error, but it doesn't make sense to solve the printing 950 * delay with more complex code. 951 */ 952 953 int 954 badport_bandlim(int which) 955 { 956 957 #define N(a) (sizeof (a) / sizeof (a[0])) 958 static struct rate { 959 const char *type; 960 struct timeval lasttime; 961 int curpps; 962 } rates[BANDLIM_MAX+1] = { 963 { "icmp unreach response" }, 964 { "icmp ping response" }, 965 { "icmp tstamp response" }, 966 { "closed port RST response" }, 967 { "open port RST response" }, 968 { "icmp6 unreach response" } 969 }; 970 971 /* 972 * Return ok status if feature disabled or argument out of range. 973 */ 974 if (V_icmplim > 0 && (u_int) which < N(rates)) { 975 struct rate *r = &rates[which]; 976 int opps = r->curpps; 977 978 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 979 return -1; /* discard packet */ 980 /* 981 * If we've dropped below the threshold after having 982 * rate-limited traffic print the message. This preserves 983 * the previous behaviour at the expense of added complexity. 984 */ 985 if (V_icmplim_output && opps > V_icmplim) 986 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 987 r->type, opps, V_icmplim); 988 } 989 return 0; /* okay to send packet */ 990 #undef N 991 } 992