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 int 362 icmp_input(struct mbuf **mp, int *offp, int proto) 363 { 364 struct icmp *icp; 365 struct in_ifaddr *ia; 366 struct mbuf *m = *mp; 367 struct ip *ip = mtod(m, struct ip *); 368 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 369 int hlen = *offp; 370 int icmplen = ntohs(ip->ip_len) - *offp; 371 int i, code; 372 void (*ctlfunc)(int, struct sockaddr *, void *); 373 int fibnum; 374 375 *mp = NULL; 376 377 /* 378 * Locate icmp structure in mbuf, and check 379 * that not corrupted and of at least minimum length. 380 */ 381 #ifdef ICMPPRINTFS 382 if (icmpprintfs) { 383 char buf[4 * sizeof "123"]; 384 strcpy(buf, inet_ntoa(ip->ip_src)); 385 printf("icmp_input from %s to %s, len %d\n", 386 buf, inet_ntoa(ip->ip_dst), icmplen); 387 } 388 #endif 389 if (icmplen < ICMP_MINLEN) { 390 ICMPSTAT_INC(icps_tooshort); 391 goto freeit; 392 } 393 i = hlen + min(icmplen, ICMP_ADVLENMIN); 394 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 395 ICMPSTAT_INC(icps_tooshort); 396 return (IPPROTO_DONE); 397 } 398 ip = mtod(m, struct ip *); 399 m->m_len -= hlen; 400 m->m_data += hlen; 401 icp = mtod(m, struct icmp *); 402 if (in_cksum(m, icmplen)) { 403 ICMPSTAT_INC(icps_checksum); 404 goto freeit; 405 } 406 m->m_len += hlen; 407 m->m_data -= hlen; 408 409 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 410 /* 411 * Deliver very specific ICMP type only. 412 */ 413 switch (icp->icmp_type) { 414 case ICMP_UNREACH: 415 case ICMP_TIMXCEED: 416 break; 417 default: 418 goto freeit; 419 } 420 } 421 422 #ifdef ICMPPRINTFS 423 if (icmpprintfs) 424 printf("icmp_input, type %d code %d\n", icp->icmp_type, 425 icp->icmp_code); 426 #endif 427 428 /* 429 * Message type specific processing. 430 */ 431 if (icp->icmp_type > ICMP_MAXTYPE) 432 goto raw; 433 434 /* Initialize */ 435 bzero(&icmpsrc, sizeof(icmpsrc)); 436 icmpsrc.sin_len = sizeof(struct sockaddr_in); 437 icmpsrc.sin_family = AF_INET; 438 bzero(&icmpdst, sizeof(icmpdst)); 439 icmpdst.sin_len = sizeof(struct sockaddr_in); 440 icmpdst.sin_family = AF_INET; 441 bzero(&icmpgw, sizeof(icmpgw)); 442 icmpgw.sin_len = sizeof(struct sockaddr_in); 443 icmpgw.sin_family = AF_INET; 444 445 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 446 code = icp->icmp_code; 447 switch (icp->icmp_type) { 448 449 case ICMP_UNREACH: 450 switch (code) { 451 case ICMP_UNREACH_NET: 452 case ICMP_UNREACH_HOST: 453 case ICMP_UNREACH_SRCFAIL: 454 case ICMP_UNREACH_NET_UNKNOWN: 455 case ICMP_UNREACH_HOST_UNKNOWN: 456 case ICMP_UNREACH_ISOLATED: 457 case ICMP_UNREACH_TOSNET: 458 case ICMP_UNREACH_TOSHOST: 459 case ICMP_UNREACH_HOST_PRECEDENCE: 460 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 461 code = PRC_UNREACH_NET; 462 break; 463 464 case ICMP_UNREACH_NEEDFRAG: 465 code = PRC_MSGSIZE; 466 break; 467 468 /* 469 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 470 * Treat subcodes 2,3 as immediate RST 471 */ 472 case ICMP_UNREACH_PROTOCOL: 473 case ICMP_UNREACH_PORT: 474 code = PRC_UNREACH_PORT; 475 break; 476 477 case ICMP_UNREACH_NET_PROHIB: 478 case ICMP_UNREACH_HOST_PROHIB: 479 case ICMP_UNREACH_FILTER_PROHIB: 480 code = PRC_UNREACH_ADMIN_PROHIB; 481 break; 482 483 default: 484 goto badcode; 485 } 486 goto deliver; 487 488 case ICMP_TIMXCEED: 489 if (code > 1) 490 goto badcode; 491 code += PRC_TIMXCEED_INTRANS; 492 goto deliver; 493 494 case ICMP_PARAMPROB: 495 if (code > 1) 496 goto badcode; 497 code = PRC_PARAMPROB; 498 goto deliver; 499 500 case ICMP_SOURCEQUENCH: 501 if (code) 502 goto badcode; 503 code = PRC_QUENCH; 504 deliver: 505 /* 506 * Problem with datagram; advise higher level routines. 507 */ 508 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 509 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 510 ICMPSTAT_INC(icps_badlen); 511 goto freeit; 512 } 513 /* Discard ICMP's in response to multicast packets */ 514 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 515 goto badcode; 516 #ifdef ICMPPRINTFS 517 if (icmpprintfs) 518 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 519 #endif 520 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 521 /* 522 * XXX if the packet contains [IPv4 AH TCP], we can't make a 523 * notification to TCP layer. 524 */ 525 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 526 if (ctlfunc) 527 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 528 (void *)&icp->icmp_ip); 529 break; 530 531 badcode: 532 ICMPSTAT_INC(icps_badcode); 533 break; 534 535 case ICMP_ECHO: 536 if (!V_icmpbmcastecho 537 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 538 ICMPSTAT_INC(icps_bmcastecho); 539 break; 540 } 541 icp->icmp_type = ICMP_ECHOREPLY; 542 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 543 goto freeit; 544 else 545 goto reflect; 546 547 case ICMP_TSTAMP: 548 if (!V_icmpbmcastecho 549 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 550 ICMPSTAT_INC(icps_bmcasttstamp); 551 break; 552 } 553 if (icmplen < ICMP_TSLEN) { 554 ICMPSTAT_INC(icps_badlen); 555 break; 556 } 557 icp->icmp_type = ICMP_TSTAMPREPLY; 558 icp->icmp_rtime = iptime(); 559 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 560 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 561 goto freeit; 562 else 563 goto reflect; 564 565 case ICMP_MASKREQ: 566 if (V_icmpmaskrepl == 0) 567 break; 568 /* 569 * We are not able to respond with all ones broadcast 570 * unless we receive it over a point-to-point interface. 571 */ 572 if (icmplen < ICMP_MASKLEN) 573 break; 574 switch (ip->ip_dst.s_addr) { 575 576 case INADDR_BROADCAST: 577 case INADDR_ANY: 578 icmpdst.sin_addr = ip->ip_src; 579 break; 580 581 default: 582 icmpdst.sin_addr = ip->ip_dst; 583 } 584 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 585 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 586 if (ia == NULL) 587 break; 588 if (ia->ia_ifp == NULL) { 589 ifa_free(&ia->ia_ifa); 590 break; 591 } 592 icp->icmp_type = ICMP_MASKREPLY; 593 if (V_icmpmaskfake == 0) 594 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 595 else 596 icp->icmp_mask = V_icmpmaskfake; 597 if (ip->ip_src.s_addr == 0) { 598 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 599 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 600 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 601 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 602 } 603 ifa_free(&ia->ia_ifa); 604 reflect: 605 ICMPSTAT_INC(icps_reflect); 606 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 607 icmp_reflect(m); 608 return (IPPROTO_DONE); 609 610 case ICMP_REDIRECT: 611 if (V_log_redirect) { 612 u_long src, dst, gw; 613 614 src = ntohl(ip->ip_src.s_addr); 615 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 616 gw = ntohl(icp->icmp_gwaddr.s_addr); 617 printf("icmp redirect from %d.%d.%d.%d: " 618 "%d.%d.%d.%d => %d.%d.%d.%d\n", 619 (int)(src >> 24), (int)((src >> 16) & 0xff), 620 (int)((src >> 8) & 0xff), (int)(src & 0xff), 621 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 622 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 623 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 624 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 625 } 626 /* 627 * RFC1812 says we must ignore ICMP redirects if we 628 * are acting as router. 629 */ 630 if (V_drop_redirect || V_ipforwarding) 631 break; 632 if (code > 3) 633 goto badcode; 634 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 635 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 636 ICMPSTAT_INC(icps_badlen); 637 break; 638 } 639 /* 640 * Short circuit routing redirects to force 641 * immediate change in the kernel's routing 642 * tables. The message is also handed to anyone 643 * listening on a raw socket (e.g. the routing 644 * daemon for use in updating its tables). 645 */ 646 icmpgw.sin_addr = ip->ip_src; 647 icmpdst.sin_addr = icp->icmp_gwaddr; 648 #ifdef ICMPPRINTFS 649 if (icmpprintfs) { 650 char buf[4 * sizeof "123"]; 651 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 652 653 printf("redirect dst %s to %s\n", 654 buf, inet_ntoa(icp->icmp_gwaddr)); 655 } 656 #endif 657 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 658 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 659 in_rtredirect((struct sockaddr *)&icmpsrc, 660 (struct sockaddr *)&icmpdst, 661 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 662 (struct sockaddr *)&icmpgw, fibnum); 663 } 664 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 665 #ifdef IPSEC 666 key_sa_routechange((struct sockaddr *)&icmpsrc); 667 #endif 668 break; 669 670 /* 671 * No kernel processing for the following; 672 * just fall through to send to raw listener. 673 */ 674 case ICMP_ECHOREPLY: 675 case ICMP_ROUTERADVERT: 676 case ICMP_ROUTERSOLICIT: 677 case ICMP_TSTAMPREPLY: 678 case ICMP_IREQREPLY: 679 case ICMP_MASKREPLY: 680 default: 681 break; 682 } 683 684 raw: 685 *mp = m; 686 rip_input(mp, offp, proto); 687 return (IPPROTO_DONE); 688 689 freeit: 690 m_freem(m); 691 return (IPPROTO_DONE); 692 } 693 694 /* 695 * Reflect the ip packet back to the source 696 */ 697 static void 698 icmp_reflect(struct mbuf *m) 699 { 700 struct ip *ip = mtod(m, struct ip *); 701 struct ifaddr *ifa; 702 struct ifnet *ifp; 703 struct in_ifaddr *ia; 704 struct in_addr t; 705 struct mbuf *opts = 0; 706 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 707 708 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 709 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 710 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 711 m_freem(m); /* Bad return address */ 712 ICMPSTAT_INC(icps_badaddr); 713 goto done; /* Ip_output() will check for broadcast */ 714 } 715 716 t = ip->ip_dst; 717 ip->ip_dst = ip->ip_src; 718 719 /* 720 * Source selection for ICMP replies: 721 * 722 * If the incoming packet was addressed directly to one of our 723 * own addresses, use dst as the src for the reply. 724 */ 725 IN_IFADDR_RLOCK(); 726 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 727 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 728 t = IA_SIN(ia)->sin_addr; 729 IN_IFADDR_RUNLOCK(); 730 goto match; 731 } 732 } 733 IN_IFADDR_RUNLOCK(); 734 735 /* 736 * If the incoming packet was addressed to one of our broadcast 737 * addresses, use the first non-broadcast address which corresponds 738 * to the incoming interface. 739 */ 740 ifp = m->m_pkthdr.rcvif; 741 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 742 IF_ADDR_RLOCK(ifp); 743 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 744 if (ifa->ifa_addr->sa_family != AF_INET) 745 continue; 746 ia = ifatoia(ifa); 747 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 748 t.s_addr) { 749 t = IA_SIN(ia)->sin_addr; 750 IF_ADDR_RUNLOCK(ifp); 751 goto match; 752 } 753 } 754 IF_ADDR_RUNLOCK(ifp); 755 } 756 /* 757 * If the packet was transiting through us, use the address of 758 * the interface the packet came through in. If that interface 759 * doesn't have a suitable IP address, the normal selection 760 * criteria apply. 761 */ 762 if (V_icmp_rfi && ifp != NULL) { 763 IF_ADDR_RLOCK(ifp); 764 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 765 if (ifa->ifa_addr->sa_family != AF_INET) 766 continue; 767 ia = ifatoia(ifa); 768 t = IA_SIN(ia)->sin_addr; 769 IF_ADDR_RUNLOCK(ifp); 770 goto match; 771 } 772 IF_ADDR_RUNLOCK(ifp); 773 } 774 /* 775 * If the incoming packet was not addressed directly to us, use 776 * designated interface for icmp replies specified by sysctl 777 * net.inet.icmp.reply_src (default not set). Otherwise continue 778 * with normal source selection. 779 */ 780 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 781 IF_ADDR_RLOCK(ifp); 782 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 783 if (ifa->ifa_addr->sa_family != AF_INET) 784 continue; 785 ia = ifatoia(ifa); 786 t = IA_SIN(ia)->sin_addr; 787 IF_ADDR_RUNLOCK(ifp); 788 goto match; 789 } 790 IF_ADDR_RUNLOCK(ifp); 791 } 792 /* 793 * If the packet was transiting through us, use the address of 794 * the interface that is the closest to the packet source. 795 * When we don't have a route back to the packet source, stop here 796 * and drop the packet. 797 */ 798 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 799 if (ia == NULL) { 800 m_freem(m); 801 ICMPSTAT_INC(icps_noroute); 802 goto done; 803 } 804 t = IA_SIN(ia)->sin_addr; 805 ifa_free(&ia->ia_ifa); 806 match: 807 #ifdef MAC 808 mac_netinet_icmp_replyinplace(m); 809 #endif 810 ip->ip_src = t; 811 ip->ip_ttl = V_ip_defttl; 812 813 if (optlen > 0) { 814 register u_char *cp; 815 int opt, cnt; 816 u_int len; 817 818 /* 819 * Retrieve any source routing from the incoming packet; 820 * add on any record-route or timestamp options. 821 */ 822 cp = (u_char *) (ip + 1); 823 if ((opts = ip_srcroute(m)) == 0 && 824 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 825 opts->m_len = sizeof(struct in_addr); 826 mtod(opts, struct in_addr *)->s_addr = 0; 827 } 828 if (opts) { 829 #ifdef ICMPPRINTFS 830 if (icmpprintfs) 831 printf("icmp_reflect optlen %d rt %d => ", 832 optlen, opts->m_len); 833 #endif 834 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 835 opt = cp[IPOPT_OPTVAL]; 836 if (opt == IPOPT_EOL) 837 break; 838 if (opt == IPOPT_NOP) 839 len = 1; 840 else { 841 if (cnt < IPOPT_OLEN + sizeof(*cp)) 842 break; 843 len = cp[IPOPT_OLEN]; 844 if (len < IPOPT_OLEN + sizeof(*cp) || 845 len > cnt) 846 break; 847 } 848 /* 849 * Should check for overflow, but it "can't happen" 850 */ 851 if (opt == IPOPT_RR || opt == IPOPT_TS || 852 opt == IPOPT_SECURITY) { 853 bcopy((caddr_t)cp, 854 mtod(opts, caddr_t) + opts->m_len, len); 855 opts->m_len += len; 856 } 857 } 858 /* Terminate & pad, if necessary */ 859 cnt = opts->m_len % 4; 860 if (cnt) { 861 for (; cnt < 4; cnt++) { 862 *(mtod(opts, caddr_t) + opts->m_len) = 863 IPOPT_EOL; 864 opts->m_len++; 865 } 866 } 867 #ifdef ICMPPRINTFS 868 if (icmpprintfs) 869 printf("%d\n", opts->m_len); 870 #endif 871 } 872 ip_stripoptions(m); 873 } 874 m_tag_delete_nonpersistent(m); 875 m->m_flags &= ~(M_BCAST|M_MCAST); 876 icmp_send(m, opts); 877 done: 878 if (opts) 879 (void)m_free(opts); 880 } 881 882 /* 883 * Send an icmp packet back to the ip level, 884 * after supplying a checksum. 885 */ 886 static void 887 icmp_send(struct mbuf *m, struct mbuf *opts) 888 { 889 register struct ip *ip = mtod(m, struct ip *); 890 register int hlen; 891 register struct icmp *icp; 892 893 hlen = ip->ip_hl << 2; 894 m->m_data += hlen; 895 m->m_len -= hlen; 896 icp = mtod(m, struct icmp *); 897 icp->icmp_cksum = 0; 898 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 899 m->m_data -= hlen; 900 m->m_len += hlen; 901 m->m_pkthdr.rcvif = (struct ifnet *)0; 902 #ifdef ICMPPRINTFS 903 if (icmpprintfs) { 904 char buf[4 * sizeof "123"]; 905 strcpy(buf, inet_ntoa(ip->ip_dst)); 906 printf("icmp_send dst %s src %s\n", 907 buf, inet_ntoa(ip->ip_src)); 908 } 909 #endif 910 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 911 } 912 913 /* 914 * Return milliseconds since 00:00 GMT in network format. 915 */ 916 uint32_t 917 iptime(void) 918 { 919 struct timeval atv; 920 u_long t; 921 922 getmicrotime(&atv); 923 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 924 return (htonl(t)); 925 } 926 927 /* 928 * Return the next larger or smaller MTU plateau (table from RFC 1191) 929 * given current value MTU. If DIR is less than zero, a larger plateau 930 * is returned; otherwise, a smaller value is returned. 931 */ 932 int 933 ip_next_mtu(int mtu, int dir) 934 { 935 static int mtutab[] = { 936 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 937 296, 68, 0 938 }; 939 int i, size; 940 941 size = (sizeof mtutab) / (sizeof mtutab[0]); 942 if (dir >= 0) { 943 for (i = 0; i < size; i++) 944 if (mtu > mtutab[i]) 945 return mtutab[i]; 946 } else { 947 for (i = size - 1; i >= 0; i--) 948 if (mtu < mtutab[i]) 949 return mtutab[i]; 950 if (mtu == mtutab[0]) 951 return mtutab[0]; 952 } 953 return 0; 954 } 955 #endif /* INET */ 956 957 958 /* 959 * badport_bandlim() - check for ICMP bandwidth limit 960 * 961 * Return 0 if it is ok to send an ICMP error response, -1 if we have 962 * hit our bandwidth limit and it is not ok. 963 * 964 * If icmplim is <= 0, the feature is disabled and 0 is returned. 965 * 966 * For now we separate the TCP and UDP subsystems w/ different 'which' 967 * values. We may eventually remove this separation (and simplify the 968 * code further). 969 * 970 * Note that the printing of the error message is delayed so we can 971 * properly print the icmp error rate that the system was trying to do 972 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 973 * the 'final' error, but it doesn't make sense to solve the printing 974 * delay with more complex code. 975 */ 976 977 int 978 badport_bandlim(int which) 979 { 980 981 #define N(a) (sizeof (a) / sizeof (a[0])) 982 static struct rate { 983 const char *type; 984 struct timeval lasttime; 985 int curpps; 986 } rates[BANDLIM_MAX+1] = { 987 { "icmp unreach response" }, 988 { "icmp ping response" }, 989 { "icmp tstamp response" }, 990 { "closed port RST response" }, 991 { "open port RST response" }, 992 { "icmp6 unreach response" }, 993 { "sctp ootb response" } 994 }; 995 996 /* 997 * Return ok status if feature disabled or argument out of range. 998 */ 999 if (V_icmplim > 0 && (u_int) which < N(rates)) { 1000 struct rate *r = &rates[which]; 1001 int opps = r->curpps; 1002 1003 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 1004 return -1; /* discard packet */ 1005 /* 1006 * If we've dropped below the threshold after having 1007 * rate-limited traffic print the message. This preserves 1008 * the previous behaviour at the expense of added complexity. 1009 */ 1010 if (V_icmplim_output && opps > V_icmplim) 1011 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 1012 r->type, opps, V_icmplim); 1013 } 1014 return 0; /* okay to send packet */ 1015 #undef N 1016 } 1017