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