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_var.h> 50 #include <net/if_types.h> 51 #include <net/route.h> 52 #include <net/vnet.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/ip_options.h> 62 #include <netinet/tcp.h> 63 #include <netinet/tcp_var.h> 64 #include <netinet/tcpip.h> 65 #include <netinet/icmp_var.h> 66 67 #ifdef INET 68 #ifdef IPSEC 69 #include <netipsec/ipsec.h> 70 #include <netipsec/key.h> 71 #endif 72 73 #include <machine/in_cksum.h> 74 75 #include <security/mac/mac_framework.h> 76 #endif /* INET */ 77 78 /* 79 * ICMP routines: error generation, receive packet processing, and 80 * routines to turnaround packets back to the originator, and 81 * host table maintenance routines. 82 */ 83 static VNET_DEFINE(int, icmplim) = 200; 84 #define V_icmplim VNET(icmplim) 85 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 86 &VNET_NAME(icmplim), 0, 87 "Maximum number of ICMP responses per second"); 88 89 static VNET_DEFINE(int, icmplim_output) = 1; 90 #define V_icmplim_output VNET(icmplim_output) 91 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 92 &VNET_NAME(icmplim_output), 0, 93 "Enable logging of ICMP response rate limiting"); 94 95 #ifdef INET 96 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 97 VNET_PCPUSTAT_SYSINIT(icmpstat); 98 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 99 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 100 101 #ifdef VIMAGE 102 VNET_PCPUSTAT_SYSUNINIT(icmpstat); 103 #endif /* VIMAGE */ 104 105 static VNET_DEFINE(int, icmpmaskrepl) = 0; 106 #define V_icmpmaskrepl VNET(icmpmaskrepl) 107 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 108 &VNET_NAME(icmpmaskrepl), 0, 109 "Reply to ICMP Address Mask Request packets."); 110 111 static VNET_DEFINE(u_int, icmpmaskfake) = 0; 112 #define V_icmpmaskfake VNET(icmpmaskfake) 113 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 114 &VNET_NAME(icmpmaskfake), 0, 115 "Fake reply to ICMP Address Mask Request packets."); 116 117 VNET_DEFINE(int, drop_redirect) = 0; 118 119 static VNET_DEFINE(int, log_redirect) = 0; 120 #define V_log_redirect VNET(log_redirect) 121 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 122 &VNET_NAME(log_redirect), 0, 123 "Log ICMP redirects to the console"); 124 125 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 126 #define V_reply_src VNET(reply_src) 127 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 128 &VNET_NAME(reply_src), IFNAMSIZ, 129 "icmp reply source for non-local packets."); 130 131 static VNET_DEFINE(int, icmp_rfi) = 0; 132 #define V_icmp_rfi VNET(icmp_rfi) 133 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 134 &VNET_NAME(icmp_rfi), 0, 135 "ICMP reply from incoming interface for non-local packets"); 136 137 static VNET_DEFINE(int, icmp_quotelen) = 8; 138 #define V_icmp_quotelen VNET(icmp_quotelen) 139 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 140 &VNET_NAME(icmp_quotelen), 0, 141 "Number of bytes from original packet to quote in ICMP reply"); 142 143 /* 144 * ICMP broadcast echo sysctl 145 */ 146 static VNET_DEFINE(int, icmpbmcastecho) = 0; 147 #define V_icmpbmcastecho VNET(icmpbmcastecho) 148 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 149 &VNET_NAME(icmpbmcastecho), 0, 150 ""); 151 152 153 #ifdef ICMPPRINTFS 154 int icmpprintfs = 0; 155 #endif 156 157 static void icmp_reflect(struct mbuf *); 158 static void icmp_send(struct mbuf *, struct mbuf *); 159 160 extern struct protosw inetsw[]; 161 162 static int 163 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS) 164 { 165 int error, new; 166 int i; 167 struct radix_node_head *rnh; 168 169 new = V_drop_redirect; 170 error = sysctl_handle_int(oidp, &new, 0, req); 171 if (error == 0 && req->newptr) { 172 new = (new != 0) ? 1 : 0; 173 174 if (new == V_drop_redirect) 175 return (0); 176 177 for (i = 0; i < rt_numfibs; i++) { 178 if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL) 179 continue; 180 RADIX_NODE_HEAD_LOCK(rnh); 181 in_setmatchfunc(rnh, new); 182 RADIX_NODE_HEAD_UNLOCK(rnh); 183 } 184 185 V_drop_redirect = new; 186 } 187 188 return (error); 189 } 190 191 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect, 192 CTLTYPE_INT|CTLFLAG_RW, 0, 0, 193 sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects"); 194 195 /* 196 * Kernel module interface for updating icmpstat. The argument is an index 197 * into icmpstat treated as an array of u_long. While this encodes the 198 * general layout of icmpstat into the caller, it doesn't encode its 199 * location, so that future changes to add, for example, per-CPU stats 200 * support won't cause binary compatibility problems for kernel modules. 201 */ 202 void 203 kmod_icmpstat_inc(int statnum) 204 { 205 206 counter_u64_add(VNET(icmpstat)[statnum], 1); 207 } 208 209 /* 210 * Generate an error packet of type error 211 * in response to bad packet ip. 212 */ 213 void 214 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 215 { 216 register struct ip *oip = mtod(n, struct ip *), *nip; 217 register unsigned oiphlen = oip->ip_hl << 2; 218 register struct icmp *icp; 219 register struct mbuf *m; 220 unsigned icmplen, icmpelen, nlen; 221 222 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 223 #ifdef ICMPPRINTFS 224 if (icmpprintfs) 225 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 226 #endif 227 if (type != ICMP_REDIRECT) 228 ICMPSTAT_INC(icps_error); 229 /* 230 * Don't send error: 231 * if the original packet was encrypted. 232 * if not the first fragment of message. 233 * in response to a multicast or broadcast packet. 234 * if the old packet protocol was an ICMP error message. 235 */ 236 if (n->m_flags & M_DECRYPTED) 237 goto freeit; 238 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 239 goto freeit; 240 if (n->m_flags & (M_BCAST|M_MCAST)) 241 goto freeit; 242 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 243 n->m_len >= oiphlen + ICMP_MINLEN && 244 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 245 ICMPSTAT_INC(icps_oldicmp); 246 goto freeit; 247 } 248 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 249 if (oiphlen + 8 > n->m_len) 250 goto freeit; 251 /* 252 * Calculate length to quote from original packet and 253 * prevent the ICMP mbuf from overflowing. 254 * Unfortunatly this is non-trivial since ip_forward() 255 * sends us truncated packets. 256 */ 257 nlen = m_length(n, NULL); 258 if (oip->ip_p == IPPROTO_TCP) { 259 struct tcphdr *th; 260 int tcphlen; 261 262 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 263 n->m_next == NULL) 264 goto stdreply; 265 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 266 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 267 goto freeit; 268 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 269 tcphlen = th->th_off << 2; 270 if (tcphlen < sizeof(struct tcphdr)) 271 goto freeit; 272 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 273 goto freeit; 274 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 275 goto stdreply; 276 if (n->m_len < oiphlen + tcphlen && 277 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 278 goto freeit; 279 icmpelen = max(tcphlen, min(V_icmp_quotelen, 280 ntohs(oip->ip_len) - oiphlen)); 281 } else 282 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 283 284 icmplen = min(oiphlen + icmpelen, nlen); 285 if (icmplen < sizeof(struct ip)) 286 goto freeit; 287 288 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 289 m = m_gethdr(M_NOWAIT, MT_DATA); 290 else 291 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 292 if (m == NULL) 293 goto freeit; 294 #ifdef MAC 295 mac_netinet_icmp_reply(n, m); 296 #endif 297 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 298 m_align(m, ICMP_MINLEN + icmplen); 299 m->m_len = ICMP_MINLEN + icmplen; 300 301 /* XXX MRT make the outgoing packet use the same FIB 302 * that was associated with the incoming packet 303 */ 304 M_SETFIB(m, M_GETFIB(n)); 305 icp = mtod(m, struct icmp *); 306 ICMPSTAT_INC(icps_outhist[type]); 307 icp->icmp_type = type; 308 if (type == ICMP_REDIRECT) 309 icp->icmp_gwaddr.s_addr = dest; 310 else { 311 icp->icmp_void = 0; 312 /* 313 * The following assignments assume an overlay with the 314 * just zeroed icmp_void field. 315 */ 316 if (type == ICMP_PARAMPROB) { 317 icp->icmp_pptr = code; 318 code = 0; 319 } else if (type == ICMP_UNREACH && 320 code == ICMP_UNREACH_NEEDFRAG && mtu) { 321 icp->icmp_nextmtu = htons(mtu); 322 } 323 } 324 icp->icmp_code = code; 325 326 /* 327 * Copy the quotation into ICMP message and 328 * convert quoted IP header back to network representation. 329 */ 330 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 331 nip = &icp->icmp_ip; 332 333 /* 334 * Set up ICMP message mbuf and copy old IP header (without options 335 * in front of ICMP message. 336 * If the original mbuf was meant to bypass the firewall, the error 337 * reply should bypass as well. 338 */ 339 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 340 m->m_data -= sizeof(struct ip); 341 m->m_len += sizeof(struct ip); 342 m->m_pkthdr.len = m->m_len; 343 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 344 nip = mtod(m, struct ip *); 345 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 346 nip->ip_len = htons(m->m_len); 347 nip->ip_v = IPVERSION; 348 nip->ip_hl = 5; 349 nip->ip_p = IPPROTO_ICMP; 350 nip->ip_tos = 0; 351 icmp_reflect(m); 352 353 freeit: 354 m_freem(n); 355 } 356 357 /* 358 * Process a received ICMP message. 359 */ 360 void 361 icmp_input(struct mbuf *m, int off) 362 { 363 struct icmp *icp; 364 struct in_ifaddr *ia; 365 struct ip *ip = mtod(m, struct ip *); 366 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 367 int hlen = off; 368 int icmplen = ntohs(ip->ip_len) - off; 369 int i, code; 370 void (*ctlfunc)(int, struct sockaddr *, void *); 371 int fibnum; 372 373 /* 374 * Locate icmp structure in mbuf, and check 375 * that not corrupted and of at least minimum length. 376 */ 377 #ifdef ICMPPRINTFS 378 if (icmpprintfs) { 379 char buf[4 * sizeof "123"]; 380 strcpy(buf, inet_ntoa(ip->ip_src)); 381 printf("icmp_input from %s to %s, len %d\n", 382 buf, inet_ntoa(ip->ip_dst), icmplen); 383 } 384 #endif 385 if (icmplen < ICMP_MINLEN) { 386 ICMPSTAT_INC(icps_tooshort); 387 goto freeit; 388 } 389 i = hlen + min(icmplen, ICMP_ADVLENMIN); 390 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 391 ICMPSTAT_INC(icps_tooshort); 392 return; 393 } 394 ip = mtod(m, struct ip *); 395 m->m_len -= hlen; 396 m->m_data += hlen; 397 icp = mtod(m, struct icmp *); 398 if (in_cksum(m, icmplen)) { 399 ICMPSTAT_INC(icps_checksum); 400 goto freeit; 401 } 402 m->m_len += hlen; 403 m->m_data -= hlen; 404 405 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 406 /* 407 * Deliver very specific ICMP type only. 408 */ 409 switch (icp->icmp_type) { 410 case ICMP_UNREACH: 411 case ICMP_TIMXCEED: 412 break; 413 default: 414 goto freeit; 415 } 416 } 417 418 #ifdef ICMPPRINTFS 419 if (icmpprintfs) 420 printf("icmp_input, type %d code %d\n", icp->icmp_type, 421 icp->icmp_code); 422 #endif 423 424 /* 425 * Message type specific processing. 426 */ 427 if (icp->icmp_type > ICMP_MAXTYPE) 428 goto raw; 429 430 /* Initialize */ 431 bzero(&icmpsrc, sizeof(icmpsrc)); 432 icmpsrc.sin_len = sizeof(struct sockaddr_in); 433 icmpsrc.sin_family = AF_INET; 434 bzero(&icmpdst, sizeof(icmpdst)); 435 icmpdst.sin_len = sizeof(struct sockaddr_in); 436 icmpdst.sin_family = AF_INET; 437 bzero(&icmpgw, sizeof(icmpgw)); 438 icmpgw.sin_len = sizeof(struct sockaddr_in); 439 icmpgw.sin_family = AF_INET; 440 441 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 442 code = icp->icmp_code; 443 switch (icp->icmp_type) { 444 445 case ICMP_UNREACH: 446 switch (code) { 447 case ICMP_UNREACH_NET: 448 case ICMP_UNREACH_HOST: 449 case ICMP_UNREACH_SRCFAIL: 450 case ICMP_UNREACH_NET_UNKNOWN: 451 case ICMP_UNREACH_HOST_UNKNOWN: 452 case ICMP_UNREACH_ISOLATED: 453 case ICMP_UNREACH_TOSNET: 454 case ICMP_UNREACH_TOSHOST: 455 case ICMP_UNREACH_HOST_PRECEDENCE: 456 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 457 code = PRC_UNREACH_NET; 458 break; 459 460 case ICMP_UNREACH_NEEDFRAG: 461 code = PRC_MSGSIZE; 462 break; 463 464 /* 465 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 466 * Treat subcodes 2,3 as immediate RST 467 */ 468 case ICMP_UNREACH_PROTOCOL: 469 case ICMP_UNREACH_PORT: 470 code = PRC_UNREACH_PORT; 471 break; 472 473 case ICMP_UNREACH_NET_PROHIB: 474 case ICMP_UNREACH_HOST_PROHIB: 475 case ICMP_UNREACH_FILTER_PROHIB: 476 code = PRC_UNREACH_ADMIN_PROHIB; 477 break; 478 479 default: 480 goto badcode; 481 } 482 goto deliver; 483 484 case ICMP_TIMXCEED: 485 if (code > 1) 486 goto badcode; 487 code += PRC_TIMXCEED_INTRANS; 488 goto deliver; 489 490 case ICMP_PARAMPROB: 491 if (code > 1) 492 goto badcode; 493 code = PRC_PARAMPROB; 494 goto deliver; 495 496 case ICMP_SOURCEQUENCH: 497 if (code) 498 goto badcode; 499 code = PRC_QUENCH; 500 deliver: 501 /* 502 * Problem with datagram; advise higher level routines. 503 */ 504 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 505 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 506 ICMPSTAT_INC(icps_badlen); 507 goto freeit; 508 } 509 /* Discard ICMP's in response to multicast packets */ 510 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 511 goto badcode; 512 #ifdef ICMPPRINTFS 513 if (icmpprintfs) 514 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 515 #endif 516 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 517 /* 518 * XXX if the packet contains [IPv4 AH TCP], we can't make a 519 * notification to TCP layer. 520 */ 521 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 522 if (ctlfunc) 523 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 524 (void *)&icp->icmp_ip); 525 break; 526 527 badcode: 528 ICMPSTAT_INC(icps_badcode); 529 break; 530 531 case ICMP_ECHO: 532 if (!V_icmpbmcastecho 533 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 534 ICMPSTAT_INC(icps_bmcastecho); 535 break; 536 } 537 icp->icmp_type = ICMP_ECHOREPLY; 538 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 539 goto freeit; 540 else 541 goto reflect; 542 543 case ICMP_TSTAMP: 544 if (!V_icmpbmcastecho 545 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 546 ICMPSTAT_INC(icps_bmcasttstamp); 547 break; 548 } 549 if (icmplen < ICMP_TSLEN) { 550 ICMPSTAT_INC(icps_badlen); 551 break; 552 } 553 icp->icmp_type = ICMP_TSTAMPREPLY; 554 icp->icmp_rtime = iptime(); 555 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 556 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 557 goto freeit; 558 else 559 goto reflect; 560 561 case ICMP_MASKREQ: 562 if (V_icmpmaskrepl == 0) 563 break; 564 /* 565 * We are not able to respond with all ones broadcast 566 * unless we receive it over a point-to-point interface. 567 */ 568 if (icmplen < ICMP_MASKLEN) 569 break; 570 switch (ip->ip_dst.s_addr) { 571 572 case INADDR_BROADCAST: 573 case INADDR_ANY: 574 icmpdst.sin_addr = ip->ip_src; 575 break; 576 577 default: 578 icmpdst.sin_addr = ip->ip_dst; 579 } 580 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 581 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 582 if (ia == NULL) 583 break; 584 if (ia->ia_ifp == NULL) { 585 ifa_free(&ia->ia_ifa); 586 break; 587 } 588 icp->icmp_type = ICMP_MASKREPLY; 589 if (V_icmpmaskfake == 0) 590 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 591 else 592 icp->icmp_mask = V_icmpmaskfake; 593 if (ip->ip_src.s_addr == 0) { 594 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 595 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 596 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 597 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 598 } 599 ifa_free(&ia->ia_ifa); 600 reflect: 601 ICMPSTAT_INC(icps_reflect); 602 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 603 icmp_reflect(m); 604 return; 605 606 case ICMP_REDIRECT: 607 if (V_log_redirect) { 608 u_long src, dst, gw; 609 610 src = ntohl(ip->ip_src.s_addr); 611 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 612 gw = ntohl(icp->icmp_gwaddr.s_addr); 613 printf("icmp redirect from %d.%d.%d.%d: " 614 "%d.%d.%d.%d => %d.%d.%d.%d\n", 615 (int)(src >> 24), (int)((src >> 16) & 0xff), 616 (int)((src >> 8) & 0xff), (int)(src & 0xff), 617 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 618 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 619 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 620 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 621 } 622 /* 623 * RFC1812 says we must ignore ICMP redirects if we 624 * are acting as router. 625 */ 626 if (V_drop_redirect || V_ipforwarding) 627 break; 628 if (code > 3) 629 goto badcode; 630 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 631 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 632 ICMPSTAT_INC(icps_badlen); 633 break; 634 } 635 /* 636 * Short circuit routing redirects to force 637 * immediate change in the kernel's routing 638 * tables. The message is also handed to anyone 639 * listening on a raw socket (e.g. the routing 640 * daemon for use in updating its tables). 641 */ 642 icmpgw.sin_addr = ip->ip_src; 643 icmpdst.sin_addr = icp->icmp_gwaddr; 644 #ifdef ICMPPRINTFS 645 if (icmpprintfs) { 646 char buf[4 * sizeof "123"]; 647 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 648 649 printf("redirect dst %s to %s\n", 650 buf, inet_ntoa(icp->icmp_gwaddr)); 651 } 652 #endif 653 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 654 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 655 in_rtredirect((struct sockaddr *)&icmpsrc, 656 (struct sockaddr *)&icmpdst, 657 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 658 (struct sockaddr *)&icmpgw, fibnum); 659 } 660 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 661 #ifdef IPSEC 662 key_sa_routechange((struct sockaddr *)&icmpsrc); 663 #endif 664 break; 665 666 /* 667 * No kernel processing for the following; 668 * just fall through to send to raw listener. 669 */ 670 case ICMP_ECHOREPLY: 671 case ICMP_ROUTERADVERT: 672 case ICMP_ROUTERSOLICIT: 673 case ICMP_TSTAMPREPLY: 674 case ICMP_IREQREPLY: 675 case ICMP_MASKREPLY: 676 default: 677 break; 678 } 679 680 raw: 681 rip_input(m, off); 682 return; 683 684 freeit: 685 m_freem(m); 686 } 687 688 /* 689 * Reflect the ip packet back to the source 690 */ 691 static void 692 icmp_reflect(struct mbuf *m) 693 { 694 struct ip *ip = mtod(m, struct ip *); 695 struct ifaddr *ifa; 696 struct ifnet *ifp; 697 struct in_ifaddr *ia; 698 struct in_addr t; 699 struct mbuf *opts = 0; 700 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 701 702 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 703 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 704 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 705 m_freem(m); /* Bad return address */ 706 ICMPSTAT_INC(icps_badaddr); 707 goto done; /* Ip_output() will check for broadcast */ 708 } 709 710 t = ip->ip_dst; 711 ip->ip_dst = ip->ip_src; 712 713 /* 714 * Source selection for ICMP replies: 715 * 716 * If the incoming packet was addressed directly to one of our 717 * own addresses, use dst as the src for the reply. 718 */ 719 IN_IFADDR_RLOCK(); 720 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 721 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 722 t = IA_SIN(ia)->sin_addr; 723 IN_IFADDR_RUNLOCK(); 724 goto match; 725 } 726 } 727 IN_IFADDR_RUNLOCK(); 728 729 /* 730 * If the incoming packet was addressed to one of our broadcast 731 * addresses, use the first non-broadcast address which corresponds 732 * to the incoming interface. 733 */ 734 ifp = m->m_pkthdr.rcvif; 735 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 736 IF_ADDR_RLOCK(ifp); 737 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 738 if (ifa->ifa_addr->sa_family != AF_INET) 739 continue; 740 ia = ifatoia(ifa); 741 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 742 t.s_addr) { 743 t = IA_SIN(ia)->sin_addr; 744 IF_ADDR_RUNLOCK(ifp); 745 goto match; 746 } 747 } 748 IF_ADDR_RUNLOCK(ifp); 749 } 750 /* 751 * If the packet was transiting through us, use the address of 752 * the interface the packet came through in. If that interface 753 * doesn't have a suitable IP address, the normal selection 754 * criteria apply. 755 */ 756 if (V_icmp_rfi && ifp != NULL) { 757 IF_ADDR_RLOCK(ifp); 758 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 759 if (ifa->ifa_addr->sa_family != AF_INET) 760 continue; 761 ia = ifatoia(ifa); 762 t = IA_SIN(ia)->sin_addr; 763 IF_ADDR_RUNLOCK(ifp); 764 goto match; 765 } 766 IF_ADDR_RUNLOCK(ifp); 767 } 768 /* 769 * If the incoming packet was not addressed directly to us, use 770 * designated interface for icmp replies specified by sysctl 771 * net.inet.icmp.reply_src (default not set). Otherwise continue 772 * with normal source selection. 773 */ 774 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 775 IF_ADDR_RLOCK(ifp); 776 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 777 if (ifa->ifa_addr->sa_family != AF_INET) 778 continue; 779 ia = ifatoia(ifa); 780 t = IA_SIN(ia)->sin_addr; 781 IF_ADDR_RUNLOCK(ifp); 782 goto match; 783 } 784 IF_ADDR_RUNLOCK(ifp); 785 } 786 /* 787 * If the packet was transiting through us, use the address of 788 * the interface that is the closest to the packet source. 789 * When we don't have a route back to the packet source, stop here 790 * and drop the packet. 791 */ 792 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 793 if (ia == NULL) { 794 m_freem(m); 795 ICMPSTAT_INC(icps_noroute); 796 goto done; 797 } 798 t = IA_SIN(ia)->sin_addr; 799 ifa_free(&ia->ia_ifa); 800 match: 801 #ifdef MAC 802 mac_netinet_icmp_replyinplace(m); 803 #endif 804 ip->ip_src = t; 805 ip->ip_ttl = V_ip_defttl; 806 807 if (optlen > 0) { 808 register u_char *cp; 809 int opt, cnt; 810 u_int len; 811 812 /* 813 * Retrieve any source routing from the incoming packet; 814 * add on any record-route or timestamp options. 815 */ 816 cp = (u_char *) (ip + 1); 817 if ((opts = ip_srcroute(m)) == 0 && 818 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 819 opts->m_len = sizeof(struct in_addr); 820 mtod(opts, struct in_addr *)->s_addr = 0; 821 } 822 if (opts) { 823 #ifdef ICMPPRINTFS 824 if (icmpprintfs) 825 printf("icmp_reflect optlen %d rt %d => ", 826 optlen, opts->m_len); 827 #endif 828 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 829 opt = cp[IPOPT_OPTVAL]; 830 if (opt == IPOPT_EOL) 831 break; 832 if (opt == IPOPT_NOP) 833 len = 1; 834 else { 835 if (cnt < IPOPT_OLEN + sizeof(*cp)) 836 break; 837 len = cp[IPOPT_OLEN]; 838 if (len < IPOPT_OLEN + sizeof(*cp) || 839 len > cnt) 840 break; 841 } 842 /* 843 * Should check for overflow, but it "can't happen" 844 */ 845 if (opt == IPOPT_RR || opt == IPOPT_TS || 846 opt == IPOPT_SECURITY) { 847 bcopy((caddr_t)cp, 848 mtod(opts, caddr_t) + opts->m_len, len); 849 opts->m_len += len; 850 } 851 } 852 /* Terminate & pad, if necessary */ 853 cnt = opts->m_len % 4; 854 if (cnt) { 855 for (; cnt < 4; cnt++) { 856 *(mtod(opts, caddr_t) + opts->m_len) = 857 IPOPT_EOL; 858 opts->m_len++; 859 } 860 } 861 #ifdef ICMPPRINTFS 862 if (icmpprintfs) 863 printf("%d\n", opts->m_len); 864 #endif 865 } 866 ip_stripoptions(m); 867 } 868 m_tag_delete_nonpersistent(m); 869 m->m_flags &= ~(M_BCAST|M_MCAST); 870 icmp_send(m, opts); 871 done: 872 if (opts) 873 (void)m_free(opts); 874 } 875 876 /* 877 * Send an icmp packet back to the ip level, 878 * after supplying a checksum. 879 */ 880 static void 881 icmp_send(struct mbuf *m, struct mbuf *opts) 882 { 883 register struct ip *ip = mtod(m, struct ip *); 884 register int hlen; 885 register struct icmp *icp; 886 887 hlen = ip->ip_hl << 2; 888 m->m_data += hlen; 889 m->m_len -= hlen; 890 icp = mtod(m, struct icmp *); 891 icp->icmp_cksum = 0; 892 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 893 m->m_data -= hlen; 894 m->m_len += hlen; 895 m->m_pkthdr.rcvif = (struct ifnet *)0; 896 #ifdef ICMPPRINTFS 897 if (icmpprintfs) { 898 char buf[4 * sizeof "123"]; 899 strcpy(buf, inet_ntoa(ip->ip_dst)); 900 printf("icmp_send dst %s src %s\n", 901 buf, inet_ntoa(ip->ip_src)); 902 } 903 #endif 904 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 905 } 906 907 /* 908 * Return milliseconds since 00:00 GMT in network format. 909 */ 910 uint32_t 911 iptime(void) 912 { 913 struct timeval atv; 914 u_long t; 915 916 getmicrotime(&atv); 917 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 918 return (htonl(t)); 919 } 920 921 /* 922 * Return the next larger or smaller MTU plateau (table from RFC 1191) 923 * given current value MTU. If DIR is less than zero, a larger plateau 924 * is returned; otherwise, a smaller value is returned. 925 */ 926 int 927 ip_next_mtu(int mtu, int dir) 928 { 929 static int mtutab[] = { 930 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 931 296, 68, 0 932 }; 933 int i, size; 934 935 size = (sizeof mtutab) / (sizeof mtutab[0]); 936 if (dir >= 0) { 937 for (i = 0; i < size; i++) 938 if (mtu > mtutab[i]) 939 return mtutab[i]; 940 } else { 941 for (i = size - 1; i >= 0; i--) 942 if (mtu < mtutab[i]) 943 return mtutab[i]; 944 if (mtu == mtutab[0]) 945 return mtutab[0]; 946 } 947 return 0; 948 } 949 #endif /* INET */ 950 951 952 /* 953 * badport_bandlim() - check for ICMP bandwidth limit 954 * 955 * Return 0 if it is ok to send an ICMP error response, -1 if we have 956 * hit our bandwidth limit and it is not ok. 957 * 958 * If icmplim is <= 0, the feature is disabled and 0 is returned. 959 * 960 * For now we separate the TCP and UDP subsystems w/ different 'which' 961 * values. We may eventually remove this separation (and simplify the 962 * code further). 963 * 964 * Note that the printing of the error message is delayed so we can 965 * properly print the icmp error rate that the system was trying to do 966 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 967 * the 'final' error, but it doesn't make sense to solve the printing 968 * delay with more complex code. 969 */ 970 971 int 972 badport_bandlim(int which) 973 { 974 975 #define N(a) (sizeof (a) / sizeof (a[0])) 976 static struct rate { 977 const char *type; 978 struct timeval lasttime; 979 int curpps; 980 } rates[BANDLIM_MAX+1] = { 981 { "icmp unreach response" }, 982 { "icmp ping response" }, 983 { "icmp tstamp response" }, 984 { "closed port RST response" }, 985 { "open port RST response" }, 986 { "icmp6 unreach response" }, 987 { "sctp ootb response" } 988 }; 989 990 /* 991 * Return ok status if feature disabled or argument out of range. 992 */ 993 if (V_icmplim > 0 && (u_int) which < N(rates)) { 994 struct rate *r = &rates[which]; 995 int opps = r->curpps; 996 997 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 998 return -1; /* discard packet */ 999 /* 1000 * If we've dropped below the threshold after having 1001 * rate-limited traffic print the message. This preserves 1002 * the previous behaviour at the expense of added complexity. 1003 */ 1004 if (V_icmplim_output && opps > V_icmplim) 1005 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1006 r->type, opps, V_icmplim); 1007 } 1008 return 0; /* okay to send packet */ 1009 #undef N 1010 } 1011