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 logging of ICMP response rate limiting"); 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 VNET_DEFINE(int, drop_redirect) = 0; 112 113 static VNET_DEFINE(int, log_redirect) = 0; 114 #define V_log_redirect VNET(log_redirect) 115 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 116 &VNET_NAME(log_redirect), 0, 117 "Log ICMP redirects to the console"); 118 119 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 120 #define V_reply_src VNET(reply_src) 121 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 122 &VNET_NAME(reply_src), IFNAMSIZ, 123 "icmp reply source for non-local packets."); 124 125 static VNET_DEFINE(int, icmp_rfi) = 0; 126 #define V_icmp_rfi VNET(icmp_rfi) 127 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 128 &VNET_NAME(icmp_rfi), 0, 129 "ICMP reply from incoming interface for non-local packets"); 130 131 static VNET_DEFINE(int, icmp_quotelen) = 8; 132 #define V_icmp_quotelen VNET(icmp_quotelen) 133 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 134 &VNET_NAME(icmp_quotelen), 0, 135 "Number of bytes from original packet to quote in ICMP reply"); 136 137 /* 138 * ICMP broadcast echo sysctl 139 */ 140 static VNET_DEFINE(int, icmpbmcastecho) = 0; 141 #define V_icmpbmcastecho VNET(icmpbmcastecho) 142 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 143 &VNET_NAME(icmpbmcastecho), 0, 144 ""); 145 146 147 #ifdef ICMPPRINTFS 148 int icmpprintfs = 0; 149 #endif 150 151 static void icmp_reflect(struct mbuf *); 152 static void icmp_send(struct mbuf *, struct mbuf *); 153 154 extern struct protosw inetsw[]; 155 156 static int 157 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS) 158 { 159 int error, new; 160 int i; 161 struct radix_node_head *rnh; 162 163 new = V_drop_redirect; 164 error = sysctl_handle_int(oidp, &new, 0, req); 165 if (error == 0 && req->newptr) { 166 new = (new != 0) ? 1 : 0; 167 168 if (new == V_drop_redirect) 169 return (0); 170 171 for (i = 0; i < rt_numfibs; i++) { 172 if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL) 173 continue; 174 RADIX_NODE_HEAD_LOCK(rnh); 175 in_setmatchfunc(rnh, new); 176 RADIX_NODE_HEAD_UNLOCK(rnh); 177 } 178 179 V_drop_redirect = new; 180 } 181 182 return (error); 183 } 184 185 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect, 186 CTLTYPE_INT|CTLFLAG_RW, 0, 0, 187 sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects"); 188 189 /* 190 * Kernel module interface for updating icmpstat. The argument is an index 191 * into icmpstat treated as an array of u_long. While this encodes the 192 * general layout of icmpstat into the caller, it doesn't encode its 193 * location, so that future changes to add, for example, per-CPU stats 194 * support won't cause binary compatibility problems for kernel modules. 195 */ 196 void 197 kmod_icmpstat_inc(int statnum) 198 { 199 200 (*((u_long *)&V_icmpstat + statnum))++; 201 } 202 203 /* 204 * Generate an error packet of type error 205 * in response to bad packet ip. 206 */ 207 void 208 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 209 { 210 register struct ip *oip = mtod(n, struct ip *), *nip; 211 register unsigned oiphlen = oip->ip_hl << 2; 212 register struct icmp *icp; 213 register struct mbuf *m; 214 unsigned icmplen, icmpelen, nlen; 215 216 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 217 #ifdef ICMPPRINTFS 218 if (icmpprintfs) 219 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 220 #endif 221 if (type != ICMP_REDIRECT) 222 ICMPSTAT_INC(icps_error); 223 /* 224 * Don't send error: 225 * if the original packet was encrypted. 226 * if not the first fragment of message. 227 * in response to a multicast or broadcast packet. 228 * if the old packet protocol was an ICMP error message. 229 */ 230 if (n->m_flags & M_DECRYPTED) 231 goto freeit; 232 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 233 goto freeit; 234 if (n->m_flags & (M_BCAST|M_MCAST)) 235 goto freeit; 236 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 237 n->m_len >= oiphlen + ICMP_MINLEN && 238 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 239 ICMPSTAT_INC(icps_oldicmp); 240 goto freeit; 241 } 242 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 243 if (oiphlen + 8 > n->m_len) 244 goto freeit; 245 /* 246 * Calculate length to quote from original packet and 247 * prevent the ICMP mbuf from overflowing. 248 * Unfortunatly this is non-trivial since ip_forward() 249 * sends us truncated packets. 250 */ 251 nlen = m_length(n, NULL); 252 if (oip->ip_p == IPPROTO_TCP) { 253 struct tcphdr *th; 254 int tcphlen; 255 256 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 257 n->m_next == NULL) 258 goto stdreply; 259 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 260 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 261 goto freeit; 262 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 263 tcphlen = th->th_off << 2; 264 if (tcphlen < sizeof(struct tcphdr)) 265 goto freeit; 266 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 267 goto freeit; 268 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 269 goto stdreply; 270 if (n->m_len < oiphlen + tcphlen && 271 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 272 goto freeit; 273 icmpelen = max(tcphlen, min(V_icmp_quotelen, 274 ntohs(oip->ip_len) - oiphlen)); 275 } else 276 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 277 278 icmplen = min(oiphlen + icmpelen, nlen); 279 if (icmplen < sizeof(struct ip)) 280 goto freeit; 281 282 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 283 m = m_gethdr(M_NOWAIT, MT_DATA); 284 else 285 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 286 if (m == NULL) 287 goto freeit; 288 #ifdef MAC 289 mac_netinet_icmp_reply(n, m); 290 #endif 291 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 292 m_align(m, ICMP_MINLEN + icmplen); 293 m->m_len = ICMP_MINLEN + icmplen; 294 295 /* XXX MRT make the outgoing packet use the same FIB 296 * that was associated with the incoming packet 297 */ 298 M_SETFIB(m, M_GETFIB(n)); 299 icp = mtod(m, struct icmp *); 300 ICMPSTAT_INC(icps_outhist[type]); 301 icp->icmp_type = type; 302 if (type == ICMP_REDIRECT) 303 icp->icmp_gwaddr.s_addr = dest; 304 else { 305 icp->icmp_void = 0; 306 /* 307 * The following assignments assume an overlay with the 308 * just zeroed icmp_void field. 309 */ 310 if (type == ICMP_PARAMPROB) { 311 icp->icmp_pptr = code; 312 code = 0; 313 } else if (type == ICMP_UNREACH && 314 code == ICMP_UNREACH_NEEDFRAG && mtu) { 315 icp->icmp_nextmtu = htons(mtu); 316 } 317 } 318 icp->icmp_code = code; 319 320 /* 321 * Copy the quotation into ICMP message and 322 * convert quoted IP header back to network representation. 323 */ 324 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 325 nip = &icp->icmp_ip; 326 327 /* 328 * Set up ICMP message mbuf and copy old IP header (without options 329 * in front of ICMP message. 330 * If the original mbuf was meant to bypass the firewall, the error 331 * reply should bypass as well. 332 */ 333 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 334 m->m_data -= sizeof(struct ip); 335 m->m_len += sizeof(struct ip); 336 m->m_pkthdr.len = m->m_len; 337 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 338 nip = mtod(m, struct ip *); 339 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 340 nip->ip_len = htons(m->m_len); 341 nip->ip_v = IPVERSION; 342 nip->ip_hl = 5; 343 nip->ip_p = IPPROTO_ICMP; 344 nip->ip_tos = 0; 345 icmp_reflect(m); 346 347 freeit: 348 m_freem(n); 349 } 350 351 /* 352 * Process a received ICMP message. 353 */ 354 void 355 icmp_input(struct mbuf *m, int off) 356 { 357 struct icmp *icp; 358 struct in_ifaddr *ia; 359 struct ip *ip = mtod(m, struct ip *); 360 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 361 int hlen = off; 362 int icmplen = ntohs(ip->ip_len) - off; 363 int i, code; 364 void (*ctlfunc)(int, struct sockaddr *, void *); 365 int fibnum; 366 367 /* 368 * Locate icmp structure in mbuf, and check 369 * that not corrupted and of at least minimum length. 370 */ 371 #ifdef ICMPPRINTFS 372 if (icmpprintfs) { 373 char buf[4 * sizeof "123"]; 374 strcpy(buf, inet_ntoa(ip->ip_src)); 375 printf("icmp_input from %s to %s, len %d\n", 376 buf, inet_ntoa(ip->ip_dst), icmplen); 377 } 378 #endif 379 if (icmplen < ICMP_MINLEN) { 380 ICMPSTAT_INC(icps_tooshort); 381 goto freeit; 382 } 383 i = hlen + min(icmplen, ICMP_ADVLENMIN); 384 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 385 ICMPSTAT_INC(icps_tooshort); 386 return; 387 } 388 ip = mtod(m, struct ip *); 389 m->m_len -= hlen; 390 m->m_data += hlen; 391 icp = mtod(m, struct icmp *); 392 if (in_cksum(m, icmplen)) { 393 ICMPSTAT_INC(icps_checksum); 394 goto freeit; 395 } 396 m->m_len += hlen; 397 m->m_data -= hlen; 398 399 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 400 /* 401 * Deliver very specific ICMP type only. 402 */ 403 switch (icp->icmp_type) { 404 case ICMP_UNREACH: 405 case ICMP_TIMXCEED: 406 break; 407 default: 408 goto freeit; 409 } 410 } 411 412 #ifdef ICMPPRINTFS 413 if (icmpprintfs) 414 printf("icmp_input, type %d code %d\n", icp->icmp_type, 415 icp->icmp_code); 416 #endif 417 418 /* 419 * Message type specific processing. 420 */ 421 if (icp->icmp_type > ICMP_MAXTYPE) 422 goto raw; 423 424 /* Initialize */ 425 bzero(&icmpsrc, sizeof(icmpsrc)); 426 icmpsrc.sin_len = sizeof(struct sockaddr_in); 427 icmpsrc.sin_family = AF_INET; 428 bzero(&icmpdst, sizeof(icmpdst)); 429 icmpdst.sin_len = sizeof(struct sockaddr_in); 430 icmpdst.sin_family = AF_INET; 431 bzero(&icmpgw, sizeof(icmpgw)); 432 icmpgw.sin_len = sizeof(struct sockaddr_in); 433 icmpgw.sin_family = AF_INET; 434 435 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 436 code = icp->icmp_code; 437 switch (icp->icmp_type) { 438 439 case ICMP_UNREACH: 440 switch (code) { 441 case ICMP_UNREACH_NET: 442 case ICMP_UNREACH_HOST: 443 case ICMP_UNREACH_SRCFAIL: 444 case ICMP_UNREACH_NET_UNKNOWN: 445 case ICMP_UNREACH_HOST_UNKNOWN: 446 case ICMP_UNREACH_ISOLATED: 447 case ICMP_UNREACH_TOSNET: 448 case ICMP_UNREACH_TOSHOST: 449 case ICMP_UNREACH_HOST_PRECEDENCE: 450 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 451 code = PRC_UNREACH_NET; 452 break; 453 454 case ICMP_UNREACH_NEEDFRAG: 455 code = PRC_MSGSIZE; 456 break; 457 458 /* 459 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 460 * Treat subcodes 2,3 as immediate RST 461 */ 462 case ICMP_UNREACH_PROTOCOL: 463 case ICMP_UNREACH_PORT: 464 code = PRC_UNREACH_PORT; 465 break; 466 467 case ICMP_UNREACH_NET_PROHIB: 468 case ICMP_UNREACH_HOST_PROHIB: 469 case ICMP_UNREACH_FILTER_PROHIB: 470 code = PRC_UNREACH_ADMIN_PROHIB; 471 break; 472 473 default: 474 goto badcode; 475 } 476 goto deliver; 477 478 case ICMP_TIMXCEED: 479 if (code > 1) 480 goto badcode; 481 code += PRC_TIMXCEED_INTRANS; 482 goto deliver; 483 484 case ICMP_PARAMPROB: 485 if (code > 1) 486 goto badcode; 487 code = PRC_PARAMPROB; 488 goto deliver; 489 490 case ICMP_SOURCEQUENCH: 491 if (code) 492 goto badcode; 493 code = PRC_QUENCH; 494 deliver: 495 /* 496 * Problem with datagram; advise higher level routines. 497 */ 498 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 499 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 500 ICMPSTAT_INC(icps_badlen); 501 goto freeit; 502 } 503 /* Discard ICMP's in response to multicast packets */ 504 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 505 goto badcode; 506 #ifdef ICMPPRINTFS 507 if (icmpprintfs) 508 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 509 #endif 510 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 511 /* 512 * XXX if the packet contains [IPv4 AH TCP], we can't make a 513 * notification to TCP layer. 514 */ 515 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 516 if (ctlfunc) 517 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 518 (void *)&icp->icmp_ip); 519 break; 520 521 badcode: 522 ICMPSTAT_INC(icps_badcode); 523 break; 524 525 case ICMP_ECHO: 526 if (!V_icmpbmcastecho 527 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 528 ICMPSTAT_INC(icps_bmcastecho); 529 break; 530 } 531 icp->icmp_type = ICMP_ECHOREPLY; 532 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 533 goto freeit; 534 else 535 goto reflect; 536 537 case ICMP_TSTAMP: 538 if (!V_icmpbmcastecho 539 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 540 ICMPSTAT_INC(icps_bmcasttstamp); 541 break; 542 } 543 if (icmplen < ICMP_TSLEN) { 544 ICMPSTAT_INC(icps_badlen); 545 break; 546 } 547 icp->icmp_type = ICMP_TSTAMPREPLY; 548 icp->icmp_rtime = iptime(); 549 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 550 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 551 goto freeit; 552 else 553 goto reflect; 554 555 case ICMP_MASKREQ: 556 if (V_icmpmaskrepl == 0) 557 break; 558 /* 559 * We are not able to respond with all ones broadcast 560 * unless we receive it over a point-to-point interface. 561 */ 562 if (icmplen < ICMP_MASKLEN) 563 break; 564 switch (ip->ip_dst.s_addr) { 565 566 case INADDR_BROADCAST: 567 case INADDR_ANY: 568 icmpdst.sin_addr = ip->ip_src; 569 break; 570 571 default: 572 icmpdst.sin_addr = ip->ip_dst; 573 } 574 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 575 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 576 if (ia == NULL) 577 break; 578 if (ia->ia_ifp == NULL) { 579 ifa_free(&ia->ia_ifa); 580 break; 581 } 582 icp->icmp_type = ICMP_MASKREPLY; 583 if (V_icmpmaskfake == 0) 584 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 585 else 586 icp->icmp_mask = V_icmpmaskfake; 587 if (ip->ip_src.s_addr == 0) { 588 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 589 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 590 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 591 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 592 } 593 ifa_free(&ia->ia_ifa); 594 reflect: 595 ICMPSTAT_INC(icps_reflect); 596 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 597 icmp_reflect(m); 598 return; 599 600 case ICMP_REDIRECT: 601 if (V_log_redirect) { 602 u_long src, dst, gw; 603 604 src = ntohl(ip->ip_src.s_addr); 605 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 606 gw = ntohl(icp->icmp_gwaddr.s_addr); 607 printf("icmp redirect from %d.%d.%d.%d: " 608 "%d.%d.%d.%d => %d.%d.%d.%d\n", 609 (int)(src >> 24), (int)((src >> 16) & 0xff), 610 (int)((src >> 8) & 0xff), (int)(src & 0xff), 611 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 612 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 613 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 614 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 615 } 616 /* 617 * RFC1812 says we must ignore ICMP redirects if we 618 * are acting as router. 619 */ 620 if (V_drop_redirect || V_ipforwarding) 621 break; 622 if (code > 3) 623 goto badcode; 624 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 625 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 626 ICMPSTAT_INC(icps_badlen); 627 break; 628 } 629 /* 630 * Short circuit routing redirects to force 631 * immediate change in the kernel's routing 632 * tables. The message is also handed to anyone 633 * listening on a raw socket (e.g. the routing 634 * daemon for use in updating its tables). 635 */ 636 icmpgw.sin_addr = ip->ip_src; 637 icmpdst.sin_addr = icp->icmp_gwaddr; 638 #ifdef ICMPPRINTFS 639 if (icmpprintfs) { 640 char buf[4 * sizeof "123"]; 641 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 642 643 printf("redirect dst %s to %s\n", 644 buf, inet_ntoa(icp->icmp_gwaddr)); 645 } 646 #endif 647 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 648 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 649 in_rtredirect((struct sockaddr *)&icmpsrc, 650 (struct sockaddr *)&icmpdst, 651 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 652 (struct sockaddr *)&icmpgw, fibnum); 653 } 654 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 655 #ifdef IPSEC 656 key_sa_routechange((struct sockaddr *)&icmpsrc); 657 #endif 658 break; 659 660 /* 661 * No kernel processing for the following; 662 * just fall through to send to raw listener. 663 */ 664 case ICMP_ECHOREPLY: 665 case ICMP_ROUTERADVERT: 666 case ICMP_ROUTERSOLICIT: 667 case ICMP_TSTAMPREPLY: 668 case ICMP_IREQREPLY: 669 case ICMP_MASKREPLY: 670 default: 671 break; 672 } 673 674 raw: 675 rip_input(m, off); 676 return; 677 678 freeit: 679 m_freem(m); 680 } 681 682 /* 683 * Reflect the ip packet back to the source 684 */ 685 static void 686 icmp_reflect(struct mbuf *m) 687 { 688 struct ip *ip = mtod(m, struct ip *); 689 struct ifaddr *ifa; 690 struct ifnet *ifp; 691 struct in_ifaddr *ia; 692 struct in_addr t; 693 struct mbuf *opts = 0; 694 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 695 696 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 697 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 698 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 699 m_freem(m); /* Bad return address */ 700 ICMPSTAT_INC(icps_badaddr); 701 goto done; /* Ip_output() will check for broadcast */ 702 } 703 704 t = ip->ip_dst; 705 ip->ip_dst = ip->ip_src; 706 707 /* 708 * Source selection for ICMP replies: 709 * 710 * If the incoming packet was addressed directly to one of our 711 * own addresses, use dst as the src for the reply. 712 */ 713 IN_IFADDR_RLOCK(); 714 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 715 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 716 t = IA_SIN(ia)->sin_addr; 717 IN_IFADDR_RUNLOCK(); 718 goto match; 719 } 720 } 721 IN_IFADDR_RUNLOCK(); 722 723 /* 724 * If the incoming packet was addressed to one of our broadcast 725 * addresses, use the first non-broadcast address which corresponds 726 * to the incoming interface. 727 */ 728 ifp = m->m_pkthdr.rcvif; 729 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 730 IF_ADDR_RLOCK(ifp); 731 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 732 if (ifa->ifa_addr->sa_family != AF_INET) 733 continue; 734 ia = ifatoia(ifa); 735 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 736 t.s_addr) { 737 t = IA_SIN(ia)->sin_addr; 738 IF_ADDR_RUNLOCK(ifp); 739 goto match; 740 } 741 } 742 IF_ADDR_RUNLOCK(ifp); 743 } 744 /* 745 * If the packet was transiting through us, use the address of 746 * the interface the packet came through in. If that interface 747 * doesn't have a suitable IP address, the normal selection 748 * criteria apply. 749 */ 750 if (V_icmp_rfi && ifp != NULL) { 751 IF_ADDR_RLOCK(ifp); 752 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 753 if (ifa->ifa_addr->sa_family != AF_INET) 754 continue; 755 ia = ifatoia(ifa); 756 t = IA_SIN(ia)->sin_addr; 757 IF_ADDR_RUNLOCK(ifp); 758 goto match; 759 } 760 IF_ADDR_RUNLOCK(ifp); 761 } 762 /* 763 * If the incoming packet was not addressed directly to us, use 764 * designated interface for icmp replies specified by sysctl 765 * net.inet.icmp.reply_src (default not set). Otherwise continue 766 * with normal source selection. 767 */ 768 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 769 IF_ADDR_RLOCK(ifp); 770 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 771 if (ifa->ifa_addr->sa_family != AF_INET) 772 continue; 773 ia = ifatoia(ifa); 774 t = IA_SIN(ia)->sin_addr; 775 IF_ADDR_RUNLOCK(ifp); 776 goto match; 777 } 778 IF_ADDR_RUNLOCK(ifp); 779 } 780 /* 781 * If the packet was transiting through us, use the address of 782 * the interface that is the closest to the packet source. 783 * When we don't have a route back to the packet source, stop here 784 * and drop the packet. 785 */ 786 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 787 if (ia == NULL) { 788 m_freem(m); 789 ICMPSTAT_INC(icps_noroute); 790 goto done; 791 } 792 t = IA_SIN(ia)->sin_addr; 793 ifa_free(&ia->ia_ifa); 794 match: 795 #ifdef MAC 796 mac_netinet_icmp_replyinplace(m); 797 #endif 798 ip->ip_src = t; 799 ip->ip_ttl = V_ip_defttl; 800 801 if (optlen > 0) { 802 register u_char *cp; 803 int opt, cnt; 804 u_int len; 805 806 /* 807 * Retrieve any source routing from the incoming packet; 808 * add on any record-route or timestamp options. 809 */ 810 cp = (u_char *) (ip + 1); 811 if ((opts = ip_srcroute(m)) == 0 && 812 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 813 opts->m_len = sizeof(struct in_addr); 814 mtod(opts, struct in_addr *)->s_addr = 0; 815 } 816 if (opts) { 817 #ifdef ICMPPRINTFS 818 if (icmpprintfs) 819 printf("icmp_reflect optlen %d rt %d => ", 820 optlen, opts->m_len); 821 #endif 822 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 823 opt = cp[IPOPT_OPTVAL]; 824 if (opt == IPOPT_EOL) 825 break; 826 if (opt == IPOPT_NOP) 827 len = 1; 828 else { 829 if (cnt < IPOPT_OLEN + sizeof(*cp)) 830 break; 831 len = cp[IPOPT_OLEN]; 832 if (len < IPOPT_OLEN + sizeof(*cp) || 833 len > cnt) 834 break; 835 } 836 /* 837 * Should check for overflow, but it "can't happen" 838 */ 839 if (opt == IPOPT_RR || opt == IPOPT_TS || 840 opt == IPOPT_SECURITY) { 841 bcopy((caddr_t)cp, 842 mtod(opts, caddr_t) + opts->m_len, len); 843 opts->m_len += len; 844 } 845 } 846 /* Terminate & pad, if necessary */ 847 cnt = opts->m_len % 4; 848 if (cnt) { 849 for (; cnt < 4; cnt++) { 850 *(mtod(opts, caddr_t) + opts->m_len) = 851 IPOPT_EOL; 852 opts->m_len++; 853 } 854 } 855 #ifdef ICMPPRINTFS 856 if (icmpprintfs) 857 printf("%d\n", opts->m_len); 858 #endif 859 } 860 ip_stripoptions(m); 861 } 862 m_tag_delete_nonpersistent(m); 863 m->m_flags &= ~(M_BCAST|M_MCAST); 864 icmp_send(m, opts); 865 done: 866 if (opts) 867 (void)m_free(opts); 868 } 869 870 /* 871 * Send an icmp packet back to the ip level, 872 * after supplying a checksum. 873 */ 874 static void 875 icmp_send(struct mbuf *m, struct mbuf *opts) 876 { 877 register struct ip *ip = mtod(m, struct ip *); 878 register int hlen; 879 register struct icmp *icp; 880 881 hlen = ip->ip_hl << 2; 882 m->m_data += hlen; 883 m->m_len -= hlen; 884 icp = mtod(m, struct icmp *); 885 icp->icmp_cksum = 0; 886 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 887 m->m_data -= hlen; 888 m->m_len += hlen; 889 m->m_pkthdr.rcvif = (struct ifnet *)0; 890 #ifdef ICMPPRINTFS 891 if (icmpprintfs) { 892 char buf[4 * sizeof "123"]; 893 strcpy(buf, inet_ntoa(ip->ip_dst)); 894 printf("icmp_send dst %s src %s\n", 895 buf, inet_ntoa(ip->ip_src)); 896 } 897 #endif 898 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 899 } 900 901 /* 902 * Return milliseconds since 00:00 GMT in network format. 903 */ 904 uint32_t 905 iptime(void) 906 { 907 struct timeval atv; 908 u_long t; 909 910 getmicrotime(&atv); 911 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 912 return (htonl(t)); 913 } 914 915 /* 916 * Return the next larger or smaller MTU plateau (table from RFC 1191) 917 * given current value MTU. If DIR is less than zero, a larger plateau 918 * is returned; otherwise, a smaller value is returned. 919 */ 920 int 921 ip_next_mtu(int mtu, int dir) 922 { 923 static int mtutab[] = { 924 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 925 296, 68, 0 926 }; 927 int i, size; 928 929 size = (sizeof mtutab) / (sizeof mtutab[0]); 930 if (dir >= 0) { 931 for (i = 0; i < size; i++) 932 if (mtu > mtutab[i]) 933 return mtutab[i]; 934 } else { 935 for (i = size - 1; i >= 0; i--) 936 if (mtu < mtutab[i]) 937 return mtutab[i]; 938 if (mtu == mtutab[0]) 939 return mtutab[0]; 940 } 941 return 0; 942 } 943 #endif /* INET */ 944 945 946 /* 947 * badport_bandlim() - check for ICMP bandwidth limit 948 * 949 * Return 0 if it is ok to send an ICMP error response, -1 if we have 950 * hit our bandwidth limit and it is not ok. 951 * 952 * If icmplim is <= 0, the feature is disabled and 0 is returned. 953 * 954 * For now we separate the TCP and UDP subsystems w/ different 'which' 955 * values. We may eventually remove this separation (and simplify the 956 * code further). 957 * 958 * Note that the printing of the error message is delayed so we can 959 * properly print the icmp error rate that the system was trying to do 960 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 961 * the 'final' error, but it doesn't make sense to solve the printing 962 * delay with more complex code. 963 */ 964 965 int 966 badport_bandlim(int which) 967 { 968 969 #define N(a) (sizeof (a) / sizeof (a[0])) 970 static struct rate { 971 const char *type; 972 struct timeval lasttime; 973 int curpps; 974 } rates[BANDLIM_MAX+1] = { 975 { "icmp unreach response" }, 976 { "icmp ping response" }, 977 { "icmp tstamp response" }, 978 { "closed port RST response" }, 979 { "open port RST response" }, 980 { "icmp6 unreach response" }, 981 { "sctp ootb response" } 982 }; 983 984 /* 985 * Return ok status if feature disabled or argument out of range. 986 */ 987 if (V_icmplim > 0 && (u_int) which < N(rates)) { 988 struct rate *r = &rates[which]; 989 int opps = r->curpps; 990 991 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 992 return -1; /* discard packet */ 993 /* 994 * If we've dropped below the threshold after having 995 * rate-limited traffic print the message. This preserves 996 * the previous behaviour at the expense of added complexity. 997 */ 998 if (V_icmplim_output && opps > V_icmplim) 999 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1000 r->type, opps, V_icmplim); 1001 } 1002 return 0; /* okay to send packet */ 1003 #undef N 1004 } 1005