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 nip->ip_off = 0; 352 icmp_reflect(m); 353 354 freeit: 355 m_freem(n); 356 } 357 358 /* 359 * Process a received ICMP message. 360 */ 361 void 362 icmp_input(struct mbuf *m, int off) 363 { 364 struct icmp *icp; 365 struct in_ifaddr *ia; 366 struct ip *ip = mtod(m, struct ip *); 367 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 368 int hlen = off; 369 int icmplen = ntohs(ip->ip_len) - off; 370 int i, code; 371 void (*ctlfunc)(int, struct sockaddr *, void *); 372 int fibnum; 373 374 /* 375 * Locate icmp structure in mbuf, and check 376 * that not corrupted and of at least minimum length. 377 */ 378 #ifdef ICMPPRINTFS 379 if (icmpprintfs) { 380 char buf[4 * sizeof "123"]; 381 strcpy(buf, inet_ntoa(ip->ip_src)); 382 printf("icmp_input from %s to %s, len %d\n", 383 buf, inet_ntoa(ip->ip_dst), icmplen); 384 } 385 #endif 386 if (icmplen < ICMP_MINLEN) { 387 ICMPSTAT_INC(icps_tooshort); 388 goto freeit; 389 } 390 i = hlen + min(icmplen, ICMP_ADVLENMIN); 391 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 392 ICMPSTAT_INC(icps_tooshort); 393 return; 394 } 395 ip = mtod(m, struct ip *); 396 m->m_len -= hlen; 397 m->m_data += hlen; 398 icp = mtod(m, struct icmp *); 399 if (in_cksum(m, icmplen)) { 400 ICMPSTAT_INC(icps_checksum); 401 goto freeit; 402 } 403 m->m_len += hlen; 404 m->m_data -= hlen; 405 406 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 407 /* 408 * Deliver very specific ICMP type only. 409 */ 410 switch (icp->icmp_type) { 411 case ICMP_UNREACH: 412 case ICMP_TIMXCEED: 413 break; 414 default: 415 goto freeit; 416 } 417 } 418 419 #ifdef ICMPPRINTFS 420 if (icmpprintfs) 421 printf("icmp_input, type %d code %d\n", icp->icmp_type, 422 icp->icmp_code); 423 #endif 424 425 /* 426 * Message type specific processing. 427 */ 428 if (icp->icmp_type > ICMP_MAXTYPE) 429 goto raw; 430 431 /* Initialize */ 432 bzero(&icmpsrc, sizeof(icmpsrc)); 433 icmpsrc.sin_len = sizeof(struct sockaddr_in); 434 icmpsrc.sin_family = AF_INET; 435 bzero(&icmpdst, sizeof(icmpdst)); 436 icmpdst.sin_len = sizeof(struct sockaddr_in); 437 icmpdst.sin_family = AF_INET; 438 bzero(&icmpgw, sizeof(icmpgw)); 439 icmpgw.sin_len = sizeof(struct sockaddr_in); 440 icmpgw.sin_family = AF_INET; 441 442 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 443 code = icp->icmp_code; 444 switch (icp->icmp_type) { 445 446 case ICMP_UNREACH: 447 switch (code) { 448 case ICMP_UNREACH_NET: 449 case ICMP_UNREACH_HOST: 450 case ICMP_UNREACH_SRCFAIL: 451 case ICMP_UNREACH_NET_UNKNOWN: 452 case ICMP_UNREACH_HOST_UNKNOWN: 453 case ICMP_UNREACH_ISOLATED: 454 case ICMP_UNREACH_TOSNET: 455 case ICMP_UNREACH_TOSHOST: 456 case ICMP_UNREACH_HOST_PRECEDENCE: 457 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 458 code = PRC_UNREACH_NET; 459 break; 460 461 case ICMP_UNREACH_NEEDFRAG: 462 code = PRC_MSGSIZE; 463 break; 464 465 /* 466 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 467 * Treat subcodes 2,3 as immediate RST 468 */ 469 case ICMP_UNREACH_PROTOCOL: 470 case ICMP_UNREACH_PORT: 471 code = PRC_UNREACH_PORT; 472 break; 473 474 case ICMP_UNREACH_NET_PROHIB: 475 case ICMP_UNREACH_HOST_PROHIB: 476 case ICMP_UNREACH_FILTER_PROHIB: 477 code = PRC_UNREACH_ADMIN_PROHIB; 478 break; 479 480 default: 481 goto badcode; 482 } 483 goto deliver; 484 485 case ICMP_TIMXCEED: 486 if (code > 1) 487 goto badcode; 488 code += PRC_TIMXCEED_INTRANS; 489 goto deliver; 490 491 case ICMP_PARAMPROB: 492 if (code > 1) 493 goto badcode; 494 code = PRC_PARAMPROB; 495 goto deliver; 496 497 case ICMP_SOURCEQUENCH: 498 if (code) 499 goto badcode; 500 code = PRC_QUENCH; 501 deliver: 502 /* 503 * Problem with datagram; advise higher level routines. 504 */ 505 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 506 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 507 ICMPSTAT_INC(icps_badlen); 508 goto freeit; 509 } 510 /* Discard ICMP's in response to multicast packets */ 511 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 512 goto badcode; 513 #ifdef ICMPPRINTFS 514 if (icmpprintfs) 515 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 516 #endif 517 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 518 /* 519 * XXX if the packet contains [IPv4 AH TCP], we can't make a 520 * notification to TCP layer. 521 */ 522 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 523 if (ctlfunc) 524 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 525 (void *)&icp->icmp_ip); 526 break; 527 528 badcode: 529 ICMPSTAT_INC(icps_badcode); 530 break; 531 532 case ICMP_ECHO: 533 if (!V_icmpbmcastecho 534 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 535 ICMPSTAT_INC(icps_bmcastecho); 536 break; 537 } 538 icp->icmp_type = ICMP_ECHOREPLY; 539 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 540 goto freeit; 541 else 542 goto reflect; 543 544 case ICMP_TSTAMP: 545 if (!V_icmpbmcastecho 546 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 547 ICMPSTAT_INC(icps_bmcasttstamp); 548 break; 549 } 550 if (icmplen < ICMP_TSLEN) { 551 ICMPSTAT_INC(icps_badlen); 552 break; 553 } 554 icp->icmp_type = ICMP_TSTAMPREPLY; 555 icp->icmp_rtime = iptime(); 556 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 557 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 558 goto freeit; 559 else 560 goto reflect; 561 562 case ICMP_MASKREQ: 563 if (V_icmpmaskrepl == 0) 564 break; 565 /* 566 * We are not able to respond with all ones broadcast 567 * unless we receive it over a point-to-point interface. 568 */ 569 if (icmplen < ICMP_MASKLEN) 570 break; 571 switch (ip->ip_dst.s_addr) { 572 573 case INADDR_BROADCAST: 574 case INADDR_ANY: 575 icmpdst.sin_addr = ip->ip_src; 576 break; 577 578 default: 579 icmpdst.sin_addr = ip->ip_dst; 580 } 581 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 582 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 583 if (ia == NULL) 584 break; 585 if (ia->ia_ifp == NULL) { 586 ifa_free(&ia->ia_ifa); 587 break; 588 } 589 icp->icmp_type = ICMP_MASKREPLY; 590 if (V_icmpmaskfake == 0) 591 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 592 else 593 icp->icmp_mask = V_icmpmaskfake; 594 if (ip->ip_src.s_addr == 0) { 595 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 596 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 597 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 598 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 599 } 600 ifa_free(&ia->ia_ifa); 601 reflect: 602 ICMPSTAT_INC(icps_reflect); 603 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 604 icmp_reflect(m); 605 return; 606 607 case ICMP_REDIRECT: 608 if (V_log_redirect) { 609 u_long src, dst, gw; 610 611 src = ntohl(ip->ip_src.s_addr); 612 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 613 gw = ntohl(icp->icmp_gwaddr.s_addr); 614 printf("icmp redirect from %d.%d.%d.%d: " 615 "%d.%d.%d.%d => %d.%d.%d.%d\n", 616 (int)(src >> 24), (int)((src >> 16) & 0xff), 617 (int)((src >> 8) & 0xff), (int)(src & 0xff), 618 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 619 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 620 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 621 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 622 } 623 /* 624 * RFC1812 says we must ignore ICMP redirects if we 625 * are acting as router. 626 */ 627 if (V_drop_redirect || V_ipforwarding) 628 break; 629 if (code > 3) 630 goto badcode; 631 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 632 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 633 ICMPSTAT_INC(icps_badlen); 634 break; 635 } 636 /* 637 * Short circuit routing redirects to force 638 * immediate change in the kernel's routing 639 * tables. The message is also handed to anyone 640 * listening on a raw socket (e.g. the routing 641 * daemon for use in updating its tables). 642 */ 643 icmpgw.sin_addr = ip->ip_src; 644 icmpdst.sin_addr = icp->icmp_gwaddr; 645 #ifdef ICMPPRINTFS 646 if (icmpprintfs) { 647 char buf[4 * sizeof "123"]; 648 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 649 650 printf("redirect dst %s to %s\n", 651 buf, inet_ntoa(icp->icmp_gwaddr)); 652 } 653 #endif 654 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 655 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 656 in_rtredirect((struct sockaddr *)&icmpsrc, 657 (struct sockaddr *)&icmpdst, 658 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 659 (struct sockaddr *)&icmpgw, fibnum); 660 } 661 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 662 #ifdef IPSEC 663 key_sa_routechange((struct sockaddr *)&icmpsrc); 664 #endif 665 break; 666 667 /* 668 * No kernel processing for the following; 669 * just fall through to send to raw listener. 670 */ 671 case ICMP_ECHOREPLY: 672 case ICMP_ROUTERADVERT: 673 case ICMP_ROUTERSOLICIT: 674 case ICMP_TSTAMPREPLY: 675 case ICMP_IREQREPLY: 676 case ICMP_MASKREPLY: 677 default: 678 break; 679 } 680 681 raw: 682 rip_input(m, off); 683 return; 684 685 freeit: 686 m_freem(m); 687 } 688 689 /* 690 * Reflect the ip packet back to the source 691 */ 692 static void 693 icmp_reflect(struct mbuf *m) 694 { 695 struct ip *ip = mtod(m, struct ip *); 696 struct ifaddr *ifa; 697 struct ifnet *ifp; 698 struct in_ifaddr *ia; 699 struct in_addr t; 700 struct mbuf *opts = 0; 701 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 702 703 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 704 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 705 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 706 m_freem(m); /* Bad return address */ 707 ICMPSTAT_INC(icps_badaddr); 708 goto done; /* Ip_output() will check for broadcast */ 709 } 710 711 t = ip->ip_dst; 712 ip->ip_dst = ip->ip_src; 713 714 /* 715 * Source selection for ICMP replies: 716 * 717 * If the incoming packet was addressed directly to one of our 718 * own addresses, use dst as the src for the reply. 719 */ 720 IN_IFADDR_RLOCK(); 721 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 722 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 723 t = IA_SIN(ia)->sin_addr; 724 IN_IFADDR_RUNLOCK(); 725 goto match; 726 } 727 } 728 IN_IFADDR_RUNLOCK(); 729 730 /* 731 * If the incoming packet was addressed to one of our broadcast 732 * addresses, use the first non-broadcast address which corresponds 733 * to the incoming interface. 734 */ 735 ifp = m->m_pkthdr.rcvif; 736 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 737 IF_ADDR_RLOCK(ifp); 738 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 739 if (ifa->ifa_addr->sa_family != AF_INET) 740 continue; 741 ia = ifatoia(ifa); 742 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 743 t.s_addr) { 744 t = IA_SIN(ia)->sin_addr; 745 IF_ADDR_RUNLOCK(ifp); 746 goto match; 747 } 748 } 749 IF_ADDR_RUNLOCK(ifp); 750 } 751 /* 752 * If the packet was transiting through us, use the address of 753 * the interface the packet came through in. If that interface 754 * doesn't have a suitable IP address, the normal selection 755 * criteria apply. 756 */ 757 if (V_icmp_rfi && ifp != NULL) { 758 IF_ADDR_RLOCK(ifp); 759 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 760 if (ifa->ifa_addr->sa_family != AF_INET) 761 continue; 762 ia = ifatoia(ifa); 763 t = IA_SIN(ia)->sin_addr; 764 IF_ADDR_RUNLOCK(ifp); 765 goto match; 766 } 767 IF_ADDR_RUNLOCK(ifp); 768 } 769 /* 770 * If the incoming packet was not addressed directly to us, use 771 * designated interface for icmp replies specified by sysctl 772 * net.inet.icmp.reply_src (default not set). Otherwise continue 773 * with normal source selection. 774 */ 775 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 776 IF_ADDR_RLOCK(ifp); 777 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 778 if (ifa->ifa_addr->sa_family != AF_INET) 779 continue; 780 ia = ifatoia(ifa); 781 t = IA_SIN(ia)->sin_addr; 782 IF_ADDR_RUNLOCK(ifp); 783 goto match; 784 } 785 IF_ADDR_RUNLOCK(ifp); 786 } 787 /* 788 * If the packet was transiting through us, use the address of 789 * the interface that is the closest to the packet source. 790 * When we don't have a route back to the packet source, stop here 791 * and drop the packet. 792 */ 793 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 794 if (ia == NULL) { 795 m_freem(m); 796 ICMPSTAT_INC(icps_noroute); 797 goto done; 798 } 799 t = IA_SIN(ia)->sin_addr; 800 ifa_free(&ia->ia_ifa); 801 match: 802 #ifdef MAC 803 mac_netinet_icmp_replyinplace(m); 804 #endif 805 ip->ip_src = t; 806 ip->ip_ttl = V_ip_defttl; 807 808 if (optlen > 0) { 809 register u_char *cp; 810 int opt, cnt; 811 u_int len; 812 813 /* 814 * Retrieve any source routing from the incoming packet; 815 * add on any record-route or timestamp options. 816 */ 817 cp = (u_char *) (ip + 1); 818 if ((opts = ip_srcroute(m)) == 0 && 819 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 820 opts->m_len = sizeof(struct in_addr); 821 mtod(opts, struct in_addr *)->s_addr = 0; 822 } 823 if (opts) { 824 #ifdef ICMPPRINTFS 825 if (icmpprintfs) 826 printf("icmp_reflect optlen %d rt %d => ", 827 optlen, opts->m_len); 828 #endif 829 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 830 opt = cp[IPOPT_OPTVAL]; 831 if (opt == IPOPT_EOL) 832 break; 833 if (opt == IPOPT_NOP) 834 len = 1; 835 else { 836 if (cnt < IPOPT_OLEN + sizeof(*cp)) 837 break; 838 len = cp[IPOPT_OLEN]; 839 if (len < IPOPT_OLEN + sizeof(*cp) || 840 len > cnt) 841 break; 842 } 843 /* 844 * Should check for overflow, but it "can't happen" 845 */ 846 if (opt == IPOPT_RR || opt == IPOPT_TS || 847 opt == IPOPT_SECURITY) { 848 bcopy((caddr_t)cp, 849 mtod(opts, caddr_t) + opts->m_len, len); 850 opts->m_len += len; 851 } 852 } 853 /* Terminate & pad, if necessary */ 854 cnt = opts->m_len % 4; 855 if (cnt) { 856 for (; cnt < 4; cnt++) { 857 *(mtod(opts, caddr_t) + opts->m_len) = 858 IPOPT_EOL; 859 opts->m_len++; 860 } 861 } 862 #ifdef ICMPPRINTFS 863 if (icmpprintfs) 864 printf("%d\n", opts->m_len); 865 #endif 866 } 867 ip_stripoptions(m); 868 } 869 m_tag_delete_nonpersistent(m); 870 m->m_flags &= ~(M_BCAST|M_MCAST); 871 icmp_send(m, opts); 872 done: 873 if (opts) 874 (void)m_free(opts); 875 } 876 877 /* 878 * Send an icmp packet back to the ip level, 879 * after supplying a checksum. 880 */ 881 static void 882 icmp_send(struct mbuf *m, struct mbuf *opts) 883 { 884 register struct ip *ip = mtod(m, struct ip *); 885 register int hlen; 886 register struct icmp *icp; 887 888 hlen = ip->ip_hl << 2; 889 m->m_data += hlen; 890 m->m_len -= hlen; 891 icp = mtod(m, struct icmp *); 892 icp->icmp_cksum = 0; 893 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 894 m->m_data -= hlen; 895 m->m_len += hlen; 896 m->m_pkthdr.rcvif = (struct ifnet *)0; 897 #ifdef ICMPPRINTFS 898 if (icmpprintfs) { 899 char buf[4 * sizeof "123"]; 900 strcpy(buf, inet_ntoa(ip->ip_dst)); 901 printf("icmp_send dst %s src %s\n", 902 buf, inet_ntoa(ip->ip_src)); 903 } 904 #endif 905 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 906 } 907 908 /* 909 * Return milliseconds since 00:00 GMT in network format. 910 */ 911 uint32_t 912 iptime(void) 913 { 914 struct timeval atv; 915 u_long t; 916 917 getmicrotime(&atv); 918 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 919 return (htonl(t)); 920 } 921 922 /* 923 * Return the next larger or smaller MTU plateau (table from RFC 1191) 924 * given current value MTU. If DIR is less than zero, a larger plateau 925 * is returned; otherwise, a smaller value is returned. 926 */ 927 int 928 ip_next_mtu(int mtu, int dir) 929 { 930 static int mtutab[] = { 931 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 932 296, 68, 0 933 }; 934 int i, size; 935 936 size = (sizeof mtutab) / (sizeof mtutab[0]); 937 if (dir >= 0) { 938 for (i = 0; i < size; i++) 939 if (mtu > mtutab[i]) 940 return mtutab[i]; 941 } else { 942 for (i = size - 1; i >= 0; i--) 943 if (mtu < mtutab[i]) 944 return mtutab[i]; 945 if (mtu == mtutab[0]) 946 return mtutab[0]; 947 } 948 return 0; 949 } 950 #endif /* INET */ 951 952 953 /* 954 * badport_bandlim() - check for ICMP bandwidth limit 955 * 956 * Return 0 if it is ok to send an ICMP error response, -1 if we have 957 * hit our bandwidth limit and it is not ok. 958 * 959 * If icmplim is <= 0, the feature is disabled and 0 is returned. 960 * 961 * For now we separate the TCP and UDP subsystems w/ different 'which' 962 * values. We may eventually remove this separation (and simplify the 963 * code further). 964 * 965 * Note that the printing of the error message is delayed so we can 966 * properly print the icmp error rate that the system was trying to do 967 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 968 * the 'final' error, but it doesn't make sense to solve the printing 969 * delay with more complex code. 970 */ 971 972 int 973 badport_bandlim(int which) 974 { 975 976 #define N(a) (sizeof (a) / sizeof (a[0])) 977 static struct rate { 978 const char *type; 979 struct timeval lasttime; 980 int curpps; 981 } rates[BANDLIM_MAX+1] = { 982 { "icmp unreach response" }, 983 { "icmp ping response" }, 984 { "icmp tstamp response" }, 985 { "closed port RST response" }, 986 { "open port RST response" }, 987 { "icmp6 unreach response" }, 988 { "sctp ootb response" } 989 }; 990 991 /* 992 * Return ok status if feature disabled or argument out of range. 993 */ 994 if (V_icmplim > 0 && (u_int) which < N(rates)) { 995 struct rate *r = &rates[which]; 996 int opps = r->curpps; 997 998 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 999 return -1; /* discard packet */ 1000 /* 1001 * If we've dropped below the threshold after having 1002 * rate-limited traffic print the message. This preserves 1003 * the previous behaviour at the expense of added complexity. 1004 */ 1005 if (V_icmplim_output && opps > V_icmplim) 1006 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1007 r->type, opps, V_icmplim); 1008 } 1009 return 0; /* okay to send packet */ 1010 #undef N 1011 } 1012