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_ipsec.h" 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/mbuf.h> 40 #include <sys/protosw.h> 41 #include <sys/socket.h> 42 #include <sys/time.h> 43 #include <sys/kernel.h> 44 #include <sys/sysctl.h> 45 46 #include <net/if.h> 47 #include <net/if_types.h> 48 #include <net/route.h> 49 #include <net/vnet.h> 50 51 #include <netinet/in.h> 52 #include <netinet/in_pcb.h> 53 #include <netinet/in_systm.h> 54 #include <netinet/in_var.h> 55 #include <netinet/ip.h> 56 #include <netinet/ip_icmp.h> 57 #include <netinet/ip_var.h> 58 #include <netinet/ip_options.h> 59 #include <netinet/tcp.h> 60 #include <netinet/tcp_var.h> 61 #include <netinet/tcpip.h> 62 #include <netinet/icmp_var.h> 63 64 #ifdef IPSEC 65 #include <netipsec/ipsec.h> 66 #include <netipsec/key.h> 67 #endif 68 69 #include <machine/in_cksum.h> 70 71 #include <security/mac/mac_framework.h> 72 73 /* 74 * ICMP routines: error generation, receive packet processing, and 75 * routines to turnaround packets back to the originator, and 76 * host table maintenance routines. 77 */ 78 79 VNET_DEFINE(struct icmpstat, icmpstat); 80 static VNET_DEFINE(int, icmpmaskrepl); 81 static VNET_DEFINE(u_int, icmpmaskfake); 82 static VNET_DEFINE(int, drop_redirect); 83 static VNET_DEFINE(int, log_redirect); 84 static VNET_DEFINE(int, icmplim); 85 static VNET_DEFINE(int, icmplim_output); 86 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 87 static VNET_DEFINE(int, icmp_rfi); 88 static VNET_DEFINE(int, icmp_quotelen); 89 static VNET_DEFINE(int, icmpbmcastecho); 90 91 #define V_icmpmaskrepl VNET(icmpmaskrepl) 92 #define V_icmpmaskfake VNET(icmpmaskfake) 93 #define V_drop_redirect VNET(drop_redirect) 94 #define V_log_redirect VNET(log_redirect) 95 #define V_icmplim VNET(icmplim) 96 #define V_icmplim_output VNET(icmplim_output) 97 #define V_reply_src VNET(reply_src) 98 #define V_icmp_rfi VNET(icmp_rfi) 99 #define V_icmp_quotelen VNET(icmp_quotelen) 100 #define V_icmpbmcastecho VNET(icmpbmcastecho) 101 102 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 103 &VNET_NAME(icmpstat), icmpstat, ""); 104 105 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 106 &VNET_NAME(icmpmaskrepl), 0, 107 "Reply to ICMP Address Mask Request packets."); 108 109 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, 110 &VNET_NAME(icmpmaskfake), 0, 111 "Fake reply to ICMP Address Mask Request packets."); 112 113 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 114 &VNET_NAME(drop_redirect), 0, 115 "Ignore ICMP redirects"); 116 117 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 118 &VNET_NAME(log_redirect), 0, 119 "Log ICMP redirects to the console"); 120 121 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 122 &VNET_NAME(icmplim), 0, 123 "Maximum number of ICMP responses per second"); 124 125 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 126 &VNET_NAME(icmplim_output), 0, 127 "Enable rate limiting of ICMP responses"); 128 129 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 130 &VNET_NAME(reply_src), IFNAMSIZ, 131 "icmp reply source for non-local packets."); 132 133 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 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, 138 &VNET_NAME(icmp_quotelen), 0, 139 "Number of bytes from original packet to quote in ICMP reply"); 140 141 /* 142 * ICMP broadcast echo sysctl 143 */ 144 145 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 146 &VNET_NAME(icmpbmcastecho), 0, 147 ""); 148 149 150 #ifdef ICMPPRINTFS 151 int icmpprintfs = 0; 152 #endif 153 154 static void icmp_reflect(struct mbuf *); 155 static void icmp_send(struct mbuf *, struct mbuf *); 156 157 extern struct protosw inetsw[]; 158 159 void 160 icmp_init(void) 161 { 162 163 V_icmpmaskrepl = 0; 164 V_icmpmaskfake = 0; 165 V_drop_redirect = 0; 166 V_log_redirect = 0; 167 V_icmplim = 200; 168 V_icmplim_output = 1; 169 V_icmp_rfi = 0; 170 V_icmp_quotelen = 8; 171 V_icmpbmcastecho = 0; 172 } 173 174 /* 175 * Kernel module interface for updating icmpstat. The argument is an index 176 * into icmpstat treated as an array of u_long. While this encodes the 177 * general layout of icmpstat into the caller, it doesn't encode its 178 * location, so that future changes to add, for example, per-CPU stats 179 * support won't cause binary compatibility problems for kernel modules. 180 */ 181 void 182 kmod_icmpstat_inc(int statnum) 183 { 184 185 (*((u_long *)&V_icmpstat + statnum))++; 186 } 187 188 /* 189 * Generate an error packet of type error 190 * in response to bad packet ip. 191 */ 192 void 193 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 194 { 195 register struct ip *oip = mtod(n, struct ip *), *nip; 196 register unsigned oiphlen = oip->ip_hl << 2; 197 register struct icmp *icp; 198 register struct mbuf *m; 199 unsigned icmplen, icmpelen, nlen; 200 201 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 202 #ifdef ICMPPRINTFS 203 if (icmpprintfs) 204 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 205 #endif 206 if (type != ICMP_REDIRECT) 207 ICMPSTAT_INC(icps_error); 208 /* 209 * Don't send error: 210 * if the original packet was encrypted. 211 * if not the first fragment of message. 212 * in response to a multicast or broadcast packet. 213 * if the old packet protocol was an ICMP error message. 214 */ 215 if (n->m_flags & M_DECRYPTED) 216 goto freeit; 217 if (oip->ip_off & ~(IP_MF|IP_DF)) 218 goto freeit; 219 if (n->m_flags & (M_BCAST|M_MCAST)) 220 goto freeit; 221 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 222 n->m_len >= oiphlen + ICMP_MINLEN && 223 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 224 ICMPSTAT_INC(icps_oldicmp); 225 goto freeit; 226 } 227 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 228 if (oiphlen + 8 > n->m_len) 229 goto freeit; 230 /* 231 * Calculate length to quote from original packet and 232 * prevent the ICMP mbuf from overflowing. 233 * Unfortunatly this is non-trivial since ip_forward() 234 * sends us truncated packets. 235 */ 236 nlen = m_length(n, NULL); 237 if (oip->ip_p == IPPROTO_TCP) { 238 struct tcphdr *th; 239 int tcphlen; 240 241 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 242 n->m_next == NULL) 243 goto stdreply; 244 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 245 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 246 goto freeit; 247 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 248 tcphlen = th->th_off << 2; 249 if (tcphlen < sizeof(struct tcphdr)) 250 goto freeit; 251 if (oip->ip_len < oiphlen + tcphlen) 252 goto freeit; 253 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 254 goto stdreply; 255 if (n->m_len < oiphlen + tcphlen && 256 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 257 goto freeit; 258 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 259 } else 260 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen)); 261 262 icmplen = min(oiphlen + icmpelen, nlen); 263 if (icmplen < sizeof(struct ip)) 264 goto freeit; 265 266 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 267 m = m_gethdr(M_DONTWAIT, MT_DATA); 268 else 269 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 270 if (m == NULL) 271 goto freeit; 272 #ifdef MAC 273 mac_netinet_icmp_reply(n, m); 274 #endif 275 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 276 m_align(m, ICMP_MINLEN + icmplen); 277 m->m_len = ICMP_MINLEN + icmplen; 278 279 /* XXX MRT make the outgoing packet use the same FIB 280 * that was associated with the incoming packet 281 */ 282 M_SETFIB(m, M_GETFIB(n)); 283 icp = mtod(m, struct icmp *); 284 ICMPSTAT_INC(icps_outhist[type]); 285 icp->icmp_type = type; 286 if (type == ICMP_REDIRECT) 287 icp->icmp_gwaddr.s_addr = dest; 288 else { 289 icp->icmp_void = 0; 290 /* 291 * The following assignments assume an overlay with the 292 * just zeroed icmp_void field. 293 */ 294 if (type == ICMP_PARAMPROB) { 295 icp->icmp_pptr = code; 296 code = 0; 297 } else if (type == ICMP_UNREACH && 298 code == ICMP_UNREACH_NEEDFRAG && mtu) { 299 icp->icmp_nextmtu = htons(mtu); 300 } 301 } 302 icp->icmp_code = code; 303 304 /* 305 * Copy the quotation into ICMP message and 306 * convert quoted IP header back to network representation. 307 */ 308 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 309 nip = &icp->icmp_ip; 310 nip->ip_len = htons(nip->ip_len); 311 nip->ip_off = htons(nip->ip_off); 312 313 /* 314 * Set up ICMP message mbuf and copy old IP header (without options 315 * in front of ICMP message. 316 * If the original mbuf was meant to bypass the firewall, the error 317 * reply should bypass as well. 318 */ 319 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 320 m->m_data -= sizeof(struct ip); 321 m->m_len += sizeof(struct ip); 322 m->m_pkthdr.len = m->m_len; 323 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 324 nip = mtod(m, struct ip *); 325 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 326 nip->ip_len = m->m_len; 327 nip->ip_v = IPVERSION; 328 nip->ip_hl = 5; 329 nip->ip_p = IPPROTO_ICMP; 330 nip->ip_tos = 0; 331 icmp_reflect(m); 332 333 freeit: 334 m_freem(n); 335 } 336 337 /* 338 * Process a received ICMP message. 339 */ 340 void 341 icmp_input(struct mbuf *m, int off) 342 { 343 struct icmp *icp; 344 struct in_ifaddr *ia; 345 struct ip *ip = mtod(m, struct ip *); 346 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 347 int hlen = off; 348 int icmplen = ip->ip_len; 349 int i, code; 350 void (*ctlfunc)(int, struct sockaddr *, void *); 351 int fibnum; 352 353 /* 354 * Locate icmp structure in mbuf, and check 355 * that not corrupted and of at least minimum length. 356 */ 357 #ifdef ICMPPRINTFS 358 if (icmpprintfs) { 359 char buf[4 * sizeof "123"]; 360 strcpy(buf, inet_ntoa(ip->ip_src)); 361 printf("icmp_input from %s to %s, len %d\n", 362 buf, inet_ntoa(ip->ip_dst), icmplen); 363 } 364 #endif 365 if (icmplen < ICMP_MINLEN) { 366 ICMPSTAT_INC(icps_tooshort); 367 goto freeit; 368 } 369 i = hlen + min(icmplen, ICMP_ADVLENMIN); 370 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 371 ICMPSTAT_INC(icps_tooshort); 372 return; 373 } 374 ip = mtod(m, struct ip *); 375 m->m_len -= hlen; 376 m->m_data += hlen; 377 icp = mtod(m, struct icmp *); 378 if (in_cksum(m, icmplen)) { 379 ICMPSTAT_INC(icps_checksum); 380 goto freeit; 381 } 382 m->m_len += hlen; 383 m->m_data -= hlen; 384 385 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 386 /* 387 * Deliver very specific ICMP type only. 388 */ 389 switch (icp->icmp_type) { 390 case ICMP_UNREACH: 391 case ICMP_TIMXCEED: 392 break; 393 default: 394 goto freeit; 395 } 396 } 397 398 #ifdef ICMPPRINTFS 399 if (icmpprintfs) 400 printf("icmp_input, type %d code %d\n", icp->icmp_type, 401 icp->icmp_code); 402 #endif 403 404 /* 405 * Message type specific processing. 406 */ 407 if (icp->icmp_type > ICMP_MAXTYPE) 408 goto raw; 409 410 /* Initialize */ 411 bzero(&icmpsrc, sizeof(icmpsrc)); 412 icmpsrc.sin_len = sizeof(struct sockaddr_in); 413 icmpsrc.sin_family = AF_INET; 414 bzero(&icmpdst, sizeof(icmpdst)); 415 icmpdst.sin_len = sizeof(struct sockaddr_in); 416 icmpdst.sin_family = AF_INET; 417 bzero(&icmpgw, sizeof(icmpgw)); 418 icmpgw.sin_len = sizeof(struct sockaddr_in); 419 icmpgw.sin_family = AF_INET; 420 421 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 422 code = icp->icmp_code; 423 switch (icp->icmp_type) { 424 425 case ICMP_UNREACH: 426 switch (code) { 427 case ICMP_UNREACH_NET: 428 case ICMP_UNREACH_HOST: 429 case ICMP_UNREACH_SRCFAIL: 430 case ICMP_UNREACH_NET_UNKNOWN: 431 case ICMP_UNREACH_HOST_UNKNOWN: 432 case ICMP_UNREACH_ISOLATED: 433 case ICMP_UNREACH_TOSNET: 434 case ICMP_UNREACH_TOSHOST: 435 case ICMP_UNREACH_HOST_PRECEDENCE: 436 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 437 code = PRC_UNREACH_NET; 438 break; 439 440 case ICMP_UNREACH_NEEDFRAG: 441 code = PRC_MSGSIZE; 442 break; 443 444 /* 445 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 446 * Treat subcodes 2,3 as immediate RST 447 */ 448 case ICMP_UNREACH_PROTOCOL: 449 case ICMP_UNREACH_PORT: 450 code = PRC_UNREACH_PORT; 451 break; 452 453 case ICMP_UNREACH_NET_PROHIB: 454 case ICMP_UNREACH_HOST_PROHIB: 455 case ICMP_UNREACH_FILTER_PROHIB: 456 code = PRC_UNREACH_ADMIN_PROHIB; 457 break; 458 459 default: 460 goto badcode; 461 } 462 goto deliver; 463 464 case ICMP_TIMXCEED: 465 if (code > 1) 466 goto badcode; 467 code += PRC_TIMXCEED_INTRANS; 468 goto deliver; 469 470 case ICMP_PARAMPROB: 471 if (code > 1) 472 goto badcode; 473 code = PRC_PARAMPROB; 474 goto deliver; 475 476 case ICMP_SOURCEQUENCH: 477 if (code) 478 goto badcode; 479 code = PRC_QUENCH; 480 deliver: 481 /* 482 * Problem with datagram; advise higher level routines. 483 */ 484 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 485 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 486 ICMPSTAT_INC(icps_badlen); 487 goto freeit; 488 } 489 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 490 /* Discard ICMP's in response to multicast packets */ 491 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 492 goto badcode; 493 #ifdef ICMPPRINTFS 494 if (icmpprintfs) 495 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 496 #endif 497 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 498 /* 499 * XXX if the packet contains [IPv4 AH TCP], we can't make a 500 * notification to TCP layer. 501 */ 502 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 503 if (ctlfunc) 504 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 505 (void *)&icp->icmp_ip); 506 break; 507 508 badcode: 509 ICMPSTAT_INC(icps_badcode); 510 break; 511 512 case ICMP_ECHO: 513 if (!V_icmpbmcastecho 514 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 515 ICMPSTAT_INC(icps_bmcastecho); 516 break; 517 } 518 icp->icmp_type = ICMP_ECHOREPLY; 519 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 520 goto freeit; 521 else 522 goto reflect; 523 524 case ICMP_TSTAMP: 525 if (!V_icmpbmcastecho 526 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 527 ICMPSTAT_INC(icps_bmcasttstamp); 528 break; 529 } 530 if (icmplen < ICMP_TSLEN) { 531 ICMPSTAT_INC(icps_badlen); 532 break; 533 } 534 icp->icmp_type = ICMP_TSTAMPREPLY; 535 icp->icmp_rtime = iptime(); 536 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 537 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 538 goto freeit; 539 else 540 goto reflect; 541 542 case ICMP_MASKREQ: 543 if (V_icmpmaskrepl == 0) 544 break; 545 /* 546 * We are not able to respond with all ones broadcast 547 * unless we receive it over a point-to-point interface. 548 */ 549 if (icmplen < ICMP_MASKLEN) 550 break; 551 switch (ip->ip_dst.s_addr) { 552 553 case INADDR_BROADCAST: 554 case INADDR_ANY: 555 icmpdst.sin_addr = ip->ip_src; 556 break; 557 558 default: 559 icmpdst.sin_addr = ip->ip_dst; 560 } 561 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 562 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 563 if (ia == NULL) 564 break; 565 if (ia->ia_ifp == NULL) { 566 ifa_free(&ia->ia_ifa); 567 break; 568 } 569 icp->icmp_type = ICMP_MASKREPLY; 570 if (V_icmpmaskfake == 0) 571 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 572 else 573 icp->icmp_mask = V_icmpmaskfake; 574 if (ip->ip_src.s_addr == 0) { 575 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 576 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 577 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 578 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 579 } 580 ifa_free(&ia->ia_ifa); 581 reflect: 582 ip->ip_len += hlen; /* since ip_input deducts this */ 583 ICMPSTAT_INC(icps_reflect); 584 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 585 icmp_reflect(m); 586 return; 587 588 case ICMP_REDIRECT: 589 if (V_log_redirect) { 590 u_long src, dst, gw; 591 592 src = ntohl(ip->ip_src.s_addr); 593 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 594 gw = ntohl(icp->icmp_gwaddr.s_addr); 595 printf("icmp redirect from %d.%d.%d.%d: " 596 "%d.%d.%d.%d => %d.%d.%d.%d\n", 597 (int)(src >> 24), (int)((src >> 16) & 0xff), 598 (int)((src >> 8) & 0xff), (int)(src & 0xff), 599 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 600 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 601 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 602 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 603 } 604 /* 605 * RFC1812 says we must ignore ICMP redirects if we 606 * are acting as router. 607 */ 608 if (V_drop_redirect || V_ipforwarding) 609 break; 610 if (code > 3) 611 goto badcode; 612 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 613 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 614 ICMPSTAT_INC(icps_badlen); 615 break; 616 } 617 /* 618 * Short circuit routing redirects to force 619 * immediate change in the kernel's routing 620 * tables. The message is also handed to anyone 621 * listening on a raw socket (e.g. the routing 622 * daemon for use in updating its tables). 623 */ 624 icmpgw.sin_addr = ip->ip_src; 625 icmpdst.sin_addr = icp->icmp_gwaddr; 626 #ifdef ICMPPRINTFS 627 if (icmpprintfs) { 628 char buf[4 * sizeof "123"]; 629 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 630 631 printf("redirect dst %s to %s\n", 632 buf, inet_ntoa(icp->icmp_gwaddr)); 633 } 634 #endif 635 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 636 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 637 in_rtredirect((struct sockaddr *)&icmpsrc, 638 (struct sockaddr *)&icmpdst, 639 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 640 (struct sockaddr *)&icmpgw, fibnum); 641 } 642 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 643 #ifdef IPSEC 644 key_sa_routechange((struct sockaddr *)&icmpsrc); 645 #endif 646 break; 647 648 /* 649 * No kernel processing for the following; 650 * just fall through to send to raw listener. 651 */ 652 case ICMP_ECHOREPLY: 653 case ICMP_ROUTERADVERT: 654 case ICMP_ROUTERSOLICIT: 655 case ICMP_TSTAMPREPLY: 656 case ICMP_IREQREPLY: 657 case ICMP_MASKREPLY: 658 default: 659 break; 660 } 661 662 raw: 663 rip_input(m, off); 664 return; 665 666 freeit: 667 m_freem(m); 668 } 669 670 /* 671 * Reflect the ip packet back to the source 672 */ 673 static void 674 icmp_reflect(struct mbuf *m) 675 { 676 struct ip *ip = mtod(m, struct ip *); 677 struct ifaddr *ifa; 678 struct ifnet *ifp; 679 struct in_ifaddr *ia; 680 struct in_addr t; 681 struct mbuf *opts = 0; 682 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 683 684 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 685 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 686 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 687 m_freem(m); /* Bad return address */ 688 ICMPSTAT_INC(icps_badaddr); 689 goto done; /* Ip_output() will check for broadcast */ 690 } 691 692 t = ip->ip_dst; 693 ip->ip_dst = ip->ip_src; 694 695 /* 696 * Source selection for ICMP replies: 697 * 698 * If the incoming packet was addressed directly to one of our 699 * own addresses, use dst as the src for the reply. 700 */ 701 IN_IFADDR_RLOCK(); 702 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 703 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 704 t = IA_SIN(ia)->sin_addr; 705 IN_IFADDR_RUNLOCK(); 706 goto match; 707 } 708 } 709 IN_IFADDR_RUNLOCK(); 710 711 /* 712 * If the incoming packet was addressed to one of our broadcast 713 * addresses, use the first non-broadcast address which corresponds 714 * to the incoming interface. 715 */ 716 ifp = m->m_pkthdr.rcvif; 717 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 718 IF_ADDR_LOCK(ifp); 719 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 720 if (ifa->ifa_addr->sa_family != AF_INET) 721 continue; 722 ia = ifatoia(ifa); 723 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 724 t.s_addr) { 725 t = IA_SIN(ia)->sin_addr; 726 IF_ADDR_UNLOCK(ifp); 727 goto match; 728 } 729 } 730 IF_ADDR_UNLOCK(ifp); 731 } 732 /* 733 * If the packet was transiting through us, use the address of 734 * the interface the packet came through in. If that interface 735 * doesn't have a suitable IP address, the normal selection 736 * criteria apply. 737 */ 738 if (V_icmp_rfi && ifp != NULL) { 739 IF_ADDR_LOCK(ifp); 740 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 741 if (ifa->ifa_addr->sa_family != AF_INET) 742 continue; 743 ia = ifatoia(ifa); 744 t = IA_SIN(ia)->sin_addr; 745 IF_ADDR_UNLOCK(ifp); 746 goto match; 747 } 748 IF_ADDR_UNLOCK(ifp); 749 } 750 /* 751 * If the incoming packet was not addressed directly to us, use 752 * designated interface for icmp replies specified by sysctl 753 * net.inet.icmp.reply_src (default not set). Otherwise continue 754 * with normal source selection. 755 */ 756 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 757 IF_ADDR_LOCK(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_UNLOCK(ifp); 764 goto match; 765 } 766 IF_ADDR_UNLOCK(ifp); 767 } 768 /* 769 * If the packet was transiting through us, use the address of 770 * the interface that is the closest to the packet source. 771 * When we don't have a route back to the packet source, stop here 772 * and drop the packet. 773 */ 774 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 775 if (ia == NULL) { 776 m_freem(m); 777 ICMPSTAT_INC(icps_noroute); 778 goto done; 779 } 780 t = IA_SIN(ia)->sin_addr; 781 ifa_free(&ia->ia_ifa); 782 match: 783 #ifdef MAC 784 mac_netinet_icmp_replyinplace(m); 785 #endif 786 ip->ip_src = t; 787 ip->ip_ttl = V_ip_defttl; 788 789 if (optlen > 0) { 790 register u_char *cp; 791 int opt, cnt; 792 u_int len; 793 794 /* 795 * Retrieve any source routing from the incoming packet; 796 * add on any record-route or timestamp options. 797 */ 798 cp = (u_char *) (ip + 1); 799 if ((opts = ip_srcroute(m)) == 0 && 800 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) { 801 opts->m_len = sizeof(struct in_addr); 802 mtod(opts, struct in_addr *)->s_addr = 0; 803 } 804 if (opts) { 805 #ifdef ICMPPRINTFS 806 if (icmpprintfs) 807 printf("icmp_reflect optlen %d rt %d => ", 808 optlen, opts->m_len); 809 #endif 810 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 811 opt = cp[IPOPT_OPTVAL]; 812 if (opt == IPOPT_EOL) 813 break; 814 if (opt == IPOPT_NOP) 815 len = 1; 816 else { 817 if (cnt < IPOPT_OLEN + sizeof(*cp)) 818 break; 819 len = cp[IPOPT_OLEN]; 820 if (len < IPOPT_OLEN + sizeof(*cp) || 821 len > cnt) 822 break; 823 } 824 /* 825 * Should check for overflow, but it "can't happen" 826 */ 827 if (opt == IPOPT_RR || opt == IPOPT_TS || 828 opt == IPOPT_SECURITY) { 829 bcopy((caddr_t)cp, 830 mtod(opts, caddr_t) + opts->m_len, len); 831 opts->m_len += len; 832 } 833 } 834 /* Terminate & pad, if necessary */ 835 cnt = opts->m_len % 4; 836 if (cnt) { 837 for (; cnt < 4; cnt++) { 838 *(mtod(opts, caddr_t) + opts->m_len) = 839 IPOPT_EOL; 840 opts->m_len++; 841 } 842 } 843 #ifdef ICMPPRINTFS 844 if (icmpprintfs) 845 printf("%d\n", opts->m_len); 846 #endif 847 } 848 /* 849 * Now strip out original options by copying rest of first 850 * mbuf's data back, and adjust the IP length. 851 */ 852 ip->ip_len -= optlen; 853 ip->ip_v = IPVERSION; 854 ip->ip_hl = 5; 855 m->m_len -= optlen; 856 if (m->m_flags & M_PKTHDR) 857 m->m_pkthdr.len -= optlen; 858 optlen += sizeof(struct ip); 859 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 860 (unsigned)(m->m_len - sizeof(struct ip))); 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, 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 } 943 944 945 /* 946 * badport_bandlim() - check for ICMP bandwidth limit 947 * 948 * Return 0 if it is ok to send an ICMP error response, -1 if we have 949 * hit our bandwidth limit and it is not ok. 950 * 951 * If icmplim is <= 0, the feature is disabled and 0 is returned. 952 * 953 * For now we separate the TCP and UDP subsystems w/ different 'which' 954 * values. We may eventually remove this separation (and simplify the 955 * code further). 956 * 957 * Note that the printing of the error message is delayed so we can 958 * properly print the icmp error rate that the system was trying to do 959 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 960 * the 'final' error, but it doesn't make sense to solve the printing 961 * delay with more complex code. 962 */ 963 964 int 965 badport_bandlim(int which) 966 { 967 968 #define N(a) (sizeof (a) / sizeof (a[0])) 969 static struct rate { 970 const char *type; 971 struct timeval lasttime; 972 int curpps; 973 } rates[BANDLIM_MAX+1] = { 974 { "icmp unreach response" }, 975 { "icmp ping response" }, 976 { "icmp tstamp response" }, 977 { "closed port RST response" }, 978 { "open port RST response" }, 979 { "icmp6 unreach response" } 980 }; 981 982 /* 983 * Return ok status if feature disabled or argument out of range. 984 */ 985 if (V_icmplim > 0 && (u_int) which < N(rates)) { 986 struct rate *r = &rates[which]; 987 int opps = r->curpps; 988 989 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 990 return -1; /* discard packet */ 991 /* 992 * If we've dropped below the threshold after having 993 * rate-limited traffic print the message. This preserves 994 * the previous behaviour at the expense of added complexity. 995 */ 996 if (V_icmplim_output && opps > V_icmplim) 997 printf("Limiting %s from %d to %d packets/sec\n", 998 r->type, opps, V_icmplim); 999 } 1000 return 0; /* okay to send packet */ 1001 #undef N 1002 } 1003