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 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/lock.h> 45 #include <sys/rmlock.h> 46 #include <sys/sysctl.h> 47 #include <sys/syslog.h> 48 49 #include <net/if.h> 50 #include <net/if_var.h> 51 #include <net/if_types.h> 52 #include <net/route.h> 53 #include <net/vnet.h> 54 55 #include <netinet/in.h> 56 #include <netinet/in_fib.h> 57 #include <netinet/in_pcb.h> 58 #include <netinet/in_systm.h> 59 #include <netinet/in_var.h> 60 #include <netinet/ip.h> 61 #include <netinet/ip_icmp.h> 62 #include <netinet/ip_var.h> 63 #include <netinet/ip_options.h> 64 #include <netinet/tcp.h> 65 #include <netinet/tcp_var.h> 66 #include <netinet/tcpip.h> 67 #include <netinet/icmp_var.h> 68 69 #ifdef INET 70 71 #include <machine/in_cksum.h> 72 73 #include <security/mac/mac_framework.h> 74 #endif /* INET */ 75 76 /* 77 * ICMP routines: error generation, receive packet processing, and 78 * routines to turnaround packets back to the originator, and 79 * host table maintenance routines. 80 */ 81 static VNET_DEFINE(int, icmplim) = 200; 82 #define V_icmplim VNET(icmplim) 83 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, 84 &VNET_NAME(icmplim), 0, 85 "Maximum number of ICMP responses per second"); 86 87 static VNET_DEFINE(int, icmplim_output) = 1; 88 #define V_icmplim_output VNET(icmplim_output) 89 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW, 90 &VNET_NAME(icmplim_output), 0, 91 "Enable logging of ICMP response rate limiting"); 92 93 #ifdef INET 94 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 95 VNET_PCPUSTAT_SYSINIT(icmpstat); 96 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 97 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 98 99 #ifdef VIMAGE 100 VNET_PCPUSTAT_SYSUNINIT(icmpstat); 101 #endif /* VIMAGE */ 102 103 static VNET_DEFINE(int, icmpmaskrepl) = 0; 104 #define V_icmpmaskrepl VNET(icmpmaskrepl) 105 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 106 &VNET_NAME(icmpmaskrepl), 0, 107 "Reply to ICMP Address Mask Request packets."); 108 109 static VNET_DEFINE(u_int, icmpmaskfake) = 0; 110 #define V_icmpmaskfake VNET(icmpmaskfake) 111 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW, 112 &VNET_NAME(icmpmaskfake), 0, 113 "Fake reply to ICMP Address Mask Request packets."); 114 115 VNET_DEFINE(int, drop_redirect) = 0; 116 #define V_drop_redirect VNET(drop_redirect) 117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 118 &VNET_NAME(drop_redirect), 0, "Ignore ICMP redirects"); 119 120 static VNET_DEFINE(int, log_redirect) = 0; 121 #define V_log_redirect VNET(log_redirect) 122 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW, 123 &VNET_NAME(log_redirect), 0, 124 "Log ICMP redirects to the console"); 125 126 static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 127 #define V_reply_src VNET(reply_src) 128 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW, 129 &VNET_NAME(reply_src), IFNAMSIZ, 130 "icmp reply source for non-local packets."); 131 132 static VNET_DEFINE(int, icmp_rfi) = 0; 133 #define V_icmp_rfi VNET(icmp_rfi) 134 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW, 135 &VNET_NAME(icmp_rfi), 0, 136 "ICMP reply from incoming interface for non-local packets"); 137 138 static VNET_DEFINE(int, icmp_quotelen) = 8; 139 #define V_icmp_quotelen VNET(icmp_quotelen) 140 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW, 141 &VNET_NAME(icmp_quotelen), 0, 142 "Number of bytes from original packet to quote in ICMP reply"); 143 144 /* 145 * ICMP broadcast echo sysctl 146 */ 147 static VNET_DEFINE(int, icmpbmcastecho) = 0; 148 #define V_icmpbmcastecho VNET(icmpbmcastecho) 149 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 150 &VNET_NAME(icmpbmcastecho), 0, 151 ""); 152 153 static VNET_DEFINE(int, icmptstamprepl) = 1; 154 #define V_icmptstamprepl VNET(icmptstamprepl) 155 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 156 &VNET_NAME(icmptstamprepl), 0, "Respond to ICMP Timestamp packets"); 157 158 #ifdef ICMPPRINTFS 159 int icmpprintfs = 0; 160 #endif 161 162 static void icmp_reflect(struct mbuf *); 163 static void icmp_send(struct mbuf *, struct mbuf *); 164 165 extern struct protosw inetsw[]; 166 167 /* 168 * Kernel module interface for updating icmpstat. The argument is an index 169 * into icmpstat treated as an array of u_long. While this encodes the 170 * general layout of icmpstat into the caller, it doesn't encode its 171 * location, so that future changes to add, for example, per-CPU stats 172 * support won't cause binary compatibility problems for kernel modules. 173 */ 174 void 175 kmod_icmpstat_inc(int statnum) 176 { 177 178 counter_u64_add(VNET(icmpstat)[statnum], 1); 179 } 180 181 /* 182 * Generate an error packet of type error 183 * in response to bad packet ip. 184 */ 185 void 186 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 187 { 188 register struct ip *oip = mtod(n, struct ip *), *nip; 189 register unsigned oiphlen = oip->ip_hl << 2; 190 register struct icmp *icp; 191 register struct mbuf *m; 192 unsigned icmplen, icmpelen, nlen; 193 194 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 195 #ifdef ICMPPRINTFS 196 if (icmpprintfs) 197 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 198 #endif 199 if (type != ICMP_REDIRECT) 200 ICMPSTAT_INC(icps_error); 201 /* 202 * Don't send error: 203 * if the original packet was encrypted. 204 * if not the first fragment of message. 205 * in response to a multicast or broadcast packet. 206 * if the old packet protocol was an ICMP error message. 207 */ 208 if (n->m_flags & M_DECRYPTED) 209 goto freeit; 210 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 211 goto freeit; 212 if (n->m_flags & (M_BCAST|M_MCAST)) 213 goto freeit; 214 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 215 n->m_len >= oiphlen + ICMP_MINLEN && 216 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 217 ICMPSTAT_INC(icps_oldicmp); 218 goto freeit; 219 } 220 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 221 if (oiphlen + 8 > n->m_len) 222 goto freeit; 223 /* 224 * Calculate length to quote from original packet and 225 * prevent the ICMP mbuf from overflowing. 226 * Unfortunatly this is non-trivial since ip_forward() 227 * sends us truncated packets. 228 */ 229 nlen = m_length(n, NULL); 230 if (oip->ip_p == IPPROTO_TCP) { 231 struct tcphdr *th; 232 int tcphlen; 233 234 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 235 n->m_next == NULL) 236 goto stdreply; 237 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 238 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 239 goto freeit; 240 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 241 tcphlen = th->th_off << 2; 242 if (tcphlen < sizeof(struct tcphdr)) 243 goto freeit; 244 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 245 goto freeit; 246 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 247 goto stdreply; 248 if (n->m_len < oiphlen + tcphlen && 249 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 250 goto freeit; 251 icmpelen = max(tcphlen, min(V_icmp_quotelen, 252 ntohs(oip->ip_len) - oiphlen)); 253 } else 254 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 255 256 icmplen = min(oiphlen + icmpelen, nlen); 257 if (icmplen < sizeof(struct ip)) 258 goto freeit; 259 260 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 261 m = m_gethdr(M_NOWAIT, MT_DATA); 262 else 263 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 264 if (m == NULL) 265 goto freeit; 266 #ifdef MAC 267 mac_netinet_icmp_reply(n, m); 268 #endif 269 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 270 m_align(m, ICMP_MINLEN + icmplen); 271 m->m_len = ICMP_MINLEN + icmplen; 272 273 /* XXX MRT make the outgoing packet use the same FIB 274 * that was associated with the incoming packet 275 */ 276 M_SETFIB(m, M_GETFIB(n)); 277 icp = mtod(m, struct icmp *); 278 ICMPSTAT_INC(icps_outhist[type]); 279 icp->icmp_type = type; 280 if (type == ICMP_REDIRECT) 281 icp->icmp_gwaddr.s_addr = dest; 282 else { 283 icp->icmp_void = 0; 284 /* 285 * The following assignments assume an overlay with the 286 * just zeroed icmp_void field. 287 */ 288 if (type == ICMP_PARAMPROB) { 289 icp->icmp_pptr = code; 290 code = 0; 291 } else if (type == ICMP_UNREACH && 292 code == ICMP_UNREACH_NEEDFRAG && mtu) { 293 icp->icmp_nextmtu = htons(mtu); 294 } 295 } 296 icp->icmp_code = code; 297 298 /* 299 * Copy the quotation into ICMP message and 300 * convert quoted IP header back to network representation. 301 */ 302 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 303 nip = &icp->icmp_ip; 304 305 /* 306 * Set up ICMP message mbuf and copy old IP header (without options 307 * in front of ICMP message. 308 * If the original mbuf was meant to bypass the firewall, the error 309 * reply should bypass as well. 310 */ 311 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 312 m->m_data -= sizeof(struct ip); 313 m->m_len += sizeof(struct ip); 314 m->m_pkthdr.len = m->m_len; 315 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 316 nip = mtod(m, struct ip *); 317 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 318 nip->ip_len = htons(m->m_len); 319 nip->ip_v = IPVERSION; 320 nip->ip_hl = 5; 321 nip->ip_p = IPPROTO_ICMP; 322 nip->ip_tos = 0; 323 nip->ip_off = 0; 324 icmp_reflect(m); 325 326 freeit: 327 m_freem(n); 328 } 329 330 /* 331 * Process a received ICMP message. 332 */ 333 int 334 icmp_input(struct mbuf **mp, int *offp, int proto) 335 { 336 struct icmp *icp; 337 struct in_ifaddr *ia; 338 struct mbuf *m = *mp; 339 struct ip *ip = mtod(m, struct ip *); 340 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 341 int hlen = *offp; 342 int icmplen = ntohs(ip->ip_len) - *offp; 343 int i, code; 344 void (*ctlfunc)(int, struct sockaddr *, void *); 345 int fibnum; 346 347 *mp = NULL; 348 349 /* 350 * Locate icmp structure in mbuf, and check 351 * that not corrupted and of at least minimum length. 352 */ 353 #ifdef ICMPPRINTFS 354 if (icmpprintfs) { 355 char buf[4 * sizeof "123"]; 356 strcpy(buf, inet_ntoa(ip->ip_src)); 357 printf("icmp_input from %s to %s, len %d\n", 358 buf, inet_ntoa(ip->ip_dst), icmplen); 359 } 360 #endif 361 if (icmplen < ICMP_MINLEN) { 362 ICMPSTAT_INC(icps_tooshort); 363 goto freeit; 364 } 365 i = hlen + min(icmplen, ICMP_ADVLENMIN); 366 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 367 ICMPSTAT_INC(icps_tooshort); 368 return (IPPROTO_DONE); 369 } 370 ip = mtod(m, struct ip *); 371 m->m_len -= hlen; 372 m->m_data += hlen; 373 icp = mtod(m, struct icmp *); 374 if (in_cksum(m, icmplen)) { 375 ICMPSTAT_INC(icps_checksum); 376 goto freeit; 377 } 378 m->m_len += hlen; 379 m->m_data -= hlen; 380 381 #ifdef ICMPPRINTFS 382 if (icmpprintfs) 383 printf("icmp_input, type %d code %d\n", icp->icmp_type, 384 icp->icmp_code); 385 #endif 386 387 /* 388 * Message type specific processing. 389 */ 390 if (icp->icmp_type > ICMP_MAXTYPE) 391 goto raw; 392 393 /* Initialize */ 394 bzero(&icmpsrc, sizeof(icmpsrc)); 395 icmpsrc.sin_len = sizeof(struct sockaddr_in); 396 icmpsrc.sin_family = AF_INET; 397 bzero(&icmpdst, sizeof(icmpdst)); 398 icmpdst.sin_len = sizeof(struct sockaddr_in); 399 icmpdst.sin_family = AF_INET; 400 bzero(&icmpgw, sizeof(icmpgw)); 401 icmpgw.sin_len = sizeof(struct sockaddr_in); 402 icmpgw.sin_family = AF_INET; 403 404 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 405 code = icp->icmp_code; 406 switch (icp->icmp_type) { 407 408 case ICMP_UNREACH: 409 switch (code) { 410 case ICMP_UNREACH_NET: 411 case ICMP_UNREACH_HOST: 412 case ICMP_UNREACH_SRCFAIL: 413 case ICMP_UNREACH_NET_UNKNOWN: 414 case ICMP_UNREACH_HOST_UNKNOWN: 415 case ICMP_UNREACH_ISOLATED: 416 case ICMP_UNREACH_TOSNET: 417 case ICMP_UNREACH_TOSHOST: 418 case ICMP_UNREACH_HOST_PRECEDENCE: 419 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 420 code = PRC_UNREACH_NET; 421 break; 422 423 case ICMP_UNREACH_NEEDFRAG: 424 code = PRC_MSGSIZE; 425 break; 426 427 /* 428 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 429 * Treat subcodes 2,3 as immediate RST 430 */ 431 case ICMP_UNREACH_PROTOCOL: 432 case ICMP_UNREACH_PORT: 433 code = PRC_UNREACH_PORT; 434 break; 435 436 case ICMP_UNREACH_NET_PROHIB: 437 case ICMP_UNREACH_HOST_PROHIB: 438 case ICMP_UNREACH_FILTER_PROHIB: 439 code = PRC_UNREACH_ADMIN_PROHIB; 440 break; 441 442 default: 443 goto badcode; 444 } 445 goto deliver; 446 447 case ICMP_TIMXCEED: 448 if (code > 1) 449 goto badcode; 450 code += PRC_TIMXCEED_INTRANS; 451 goto deliver; 452 453 case ICMP_PARAMPROB: 454 if (code > 1) 455 goto badcode; 456 code = PRC_PARAMPROB; 457 deliver: 458 /* 459 * Problem with datagram; advise higher level routines. 460 */ 461 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 462 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 463 ICMPSTAT_INC(icps_badlen); 464 goto freeit; 465 } 466 /* Discard ICMP's in response to multicast packets */ 467 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 468 goto badcode; 469 #ifdef ICMPPRINTFS 470 if (icmpprintfs) 471 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 472 #endif 473 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 474 /* 475 * XXX if the packet contains [IPv4 AH TCP], we can't make a 476 * notification to TCP layer. 477 */ 478 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 479 if (ctlfunc) 480 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 481 (void *)&icp->icmp_ip); 482 break; 483 484 badcode: 485 ICMPSTAT_INC(icps_badcode); 486 break; 487 488 case ICMP_ECHO: 489 if (!V_icmpbmcastecho 490 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 491 ICMPSTAT_INC(icps_bmcastecho); 492 break; 493 } 494 icp->icmp_type = ICMP_ECHOREPLY; 495 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 496 goto freeit; 497 else 498 goto reflect; 499 500 case ICMP_TSTAMP: 501 if (V_icmptstamprepl == 0) 502 break; 503 if (!V_icmpbmcastecho 504 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 505 ICMPSTAT_INC(icps_bmcasttstamp); 506 break; 507 } 508 if (icmplen < ICMP_TSLEN) { 509 ICMPSTAT_INC(icps_badlen); 510 break; 511 } 512 icp->icmp_type = ICMP_TSTAMPREPLY; 513 icp->icmp_rtime = iptime(); 514 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 515 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 516 goto freeit; 517 else 518 goto reflect; 519 520 case ICMP_MASKREQ: 521 if (V_icmpmaskrepl == 0) 522 break; 523 /* 524 * We are not able to respond with all ones broadcast 525 * unless we receive it over a point-to-point interface. 526 */ 527 if (icmplen < ICMP_MASKLEN) 528 break; 529 switch (ip->ip_dst.s_addr) { 530 531 case INADDR_BROADCAST: 532 case INADDR_ANY: 533 icmpdst.sin_addr = ip->ip_src; 534 break; 535 536 default: 537 icmpdst.sin_addr = ip->ip_dst; 538 } 539 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 540 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 541 if (ia == NULL) 542 break; 543 if (ia->ia_ifp == NULL) { 544 ifa_free(&ia->ia_ifa); 545 break; 546 } 547 icp->icmp_type = ICMP_MASKREPLY; 548 if (V_icmpmaskfake == 0) 549 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 550 else 551 icp->icmp_mask = V_icmpmaskfake; 552 if (ip->ip_src.s_addr == 0) { 553 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 554 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 555 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 556 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 557 } 558 ifa_free(&ia->ia_ifa); 559 reflect: 560 ICMPSTAT_INC(icps_reflect); 561 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 562 icmp_reflect(m); 563 return (IPPROTO_DONE); 564 565 case ICMP_REDIRECT: 566 if (V_log_redirect) { 567 u_long src, dst, gw; 568 569 src = ntohl(ip->ip_src.s_addr); 570 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 571 gw = ntohl(icp->icmp_gwaddr.s_addr); 572 printf("icmp redirect from %d.%d.%d.%d: " 573 "%d.%d.%d.%d => %d.%d.%d.%d\n", 574 (int)(src >> 24), (int)((src >> 16) & 0xff), 575 (int)((src >> 8) & 0xff), (int)(src & 0xff), 576 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 577 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 578 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 579 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 580 } 581 /* 582 * RFC1812 says we must ignore ICMP redirects if we 583 * are acting as router. 584 */ 585 if (V_drop_redirect || V_ipforwarding) 586 break; 587 if (code > 3) 588 goto badcode; 589 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 590 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 591 ICMPSTAT_INC(icps_badlen); 592 break; 593 } 594 /* 595 * Short circuit routing redirects to force 596 * immediate change in the kernel's routing 597 * tables. The message is also handed to anyone 598 * listening on a raw socket (e.g. the routing 599 * daemon for use in updating its tables). 600 */ 601 icmpgw.sin_addr = ip->ip_src; 602 icmpdst.sin_addr = icp->icmp_gwaddr; 603 #ifdef ICMPPRINTFS 604 if (icmpprintfs) { 605 char buf[4 * sizeof "123"]; 606 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 607 608 printf("redirect dst %s to %s\n", 609 buf, inet_ntoa(icp->icmp_gwaddr)); 610 } 611 #endif 612 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 613 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 614 in_rtredirect((struct sockaddr *)&icmpsrc, 615 (struct sockaddr *)&icmpdst, 616 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 617 (struct sockaddr *)&icmpgw, fibnum); 618 } 619 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 620 break; 621 622 /* 623 * No kernel processing for the following; 624 * just fall through to send to raw listener. 625 */ 626 case ICMP_ECHOREPLY: 627 case ICMP_ROUTERADVERT: 628 case ICMP_ROUTERSOLICIT: 629 case ICMP_TSTAMPREPLY: 630 case ICMP_IREQREPLY: 631 case ICMP_MASKREPLY: 632 case ICMP_SOURCEQUENCH: 633 default: 634 break; 635 } 636 637 raw: 638 *mp = m; 639 rip_input(mp, offp, proto); 640 return (IPPROTO_DONE); 641 642 freeit: 643 m_freem(m); 644 return (IPPROTO_DONE); 645 } 646 647 /* 648 * Reflect the ip packet back to the source 649 */ 650 static void 651 icmp_reflect(struct mbuf *m) 652 { 653 struct rm_priotracker in_ifa_tracker; 654 struct ip *ip = mtod(m, struct ip *); 655 struct ifaddr *ifa; 656 struct ifnet *ifp; 657 struct in_ifaddr *ia; 658 struct in_addr t; 659 struct nhop4_extended nh_ext; 660 struct mbuf *opts = 0; 661 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 662 663 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 664 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 665 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 666 m_freem(m); /* Bad return address */ 667 ICMPSTAT_INC(icps_badaddr); 668 goto done; /* Ip_output() will check for broadcast */ 669 } 670 671 t = ip->ip_dst; 672 ip->ip_dst = ip->ip_src; 673 674 /* 675 * Source selection for ICMP replies: 676 * 677 * If the incoming packet was addressed directly to one of our 678 * own addresses, use dst as the src for the reply. 679 */ 680 IN_IFADDR_RLOCK(&in_ifa_tracker); 681 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 682 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 683 t = IA_SIN(ia)->sin_addr; 684 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 685 goto match; 686 } 687 } 688 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 689 690 /* 691 * If the incoming packet was addressed to one of our broadcast 692 * addresses, use the first non-broadcast address which corresponds 693 * to the incoming interface. 694 */ 695 ifp = m->m_pkthdr.rcvif; 696 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 697 IF_ADDR_RLOCK(ifp); 698 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 699 if (ifa->ifa_addr->sa_family != AF_INET) 700 continue; 701 ia = ifatoia(ifa); 702 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 703 t.s_addr) { 704 t = IA_SIN(ia)->sin_addr; 705 IF_ADDR_RUNLOCK(ifp); 706 goto match; 707 } 708 } 709 IF_ADDR_RUNLOCK(ifp); 710 } 711 /* 712 * If the packet was transiting through us, use the address of 713 * the interface the packet came through in. If that interface 714 * doesn't have a suitable IP address, the normal selection 715 * criteria apply. 716 */ 717 if (V_icmp_rfi && ifp != NULL) { 718 IF_ADDR_RLOCK(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 t = IA_SIN(ia)->sin_addr; 724 IF_ADDR_RUNLOCK(ifp); 725 goto match; 726 } 727 IF_ADDR_RUNLOCK(ifp); 728 } 729 /* 730 * If the incoming packet was not addressed directly to us, use 731 * designated interface for icmp replies specified by sysctl 732 * net.inet.icmp.reply_src (default not set). Otherwise continue 733 * with normal source selection. 734 */ 735 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 736 IF_ADDR_RLOCK(ifp); 737 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 738 if (ifa->ifa_addr->sa_family != AF_INET) 739 continue; 740 ia = ifatoia(ifa); 741 t = IA_SIN(ia)->sin_addr; 742 IF_ADDR_RUNLOCK(ifp); 743 goto match; 744 } 745 IF_ADDR_RUNLOCK(ifp); 746 } 747 /* 748 * If the packet was transiting through us, use the address of 749 * the interface that is the closest to the packet source. 750 * When we don't have a route back to the packet source, stop here 751 * and drop the packet. 752 */ 753 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 754 m_freem(m); 755 ICMPSTAT_INC(icps_noroute); 756 goto done; 757 } 758 t = nh_ext.nh_src; 759 match: 760 #ifdef MAC 761 mac_netinet_icmp_replyinplace(m); 762 #endif 763 ip->ip_src = t; 764 ip->ip_ttl = V_ip_defttl; 765 766 if (optlen > 0) { 767 register u_char *cp; 768 int opt, cnt; 769 u_int len; 770 771 /* 772 * Retrieve any source routing from the incoming packet; 773 * add on any record-route or timestamp options. 774 */ 775 cp = (u_char *) (ip + 1); 776 if ((opts = ip_srcroute(m)) == 0 && 777 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 778 opts->m_len = sizeof(struct in_addr); 779 mtod(opts, struct in_addr *)->s_addr = 0; 780 } 781 if (opts) { 782 #ifdef ICMPPRINTFS 783 if (icmpprintfs) 784 printf("icmp_reflect optlen %d rt %d => ", 785 optlen, opts->m_len); 786 #endif 787 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 788 opt = cp[IPOPT_OPTVAL]; 789 if (opt == IPOPT_EOL) 790 break; 791 if (opt == IPOPT_NOP) 792 len = 1; 793 else { 794 if (cnt < IPOPT_OLEN + sizeof(*cp)) 795 break; 796 len = cp[IPOPT_OLEN]; 797 if (len < IPOPT_OLEN + sizeof(*cp) || 798 len > cnt) 799 break; 800 } 801 /* 802 * Should check for overflow, but it "can't happen" 803 */ 804 if (opt == IPOPT_RR || opt == IPOPT_TS || 805 opt == IPOPT_SECURITY) { 806 bcopy((caddr_t)cp, 807 mtod(opts, caddr_t) + opts->m_len, len); 808 opts->m_len += len; 809 } 810 } 811 /* Terminate & pad, if necessary */ 812 cnt = opts->m_len % 4; 813 if (cnt) { 814 for (; cnt < 4; cnt++) { 815 *(mtod(opts, caddr_t) + opts->m_len) = 816 IPOPT_EOL; 817 opts->m_len++; 818 } 819 } 820 #ifdef ICMPPRINTFS 821 if (icmpprintfs) 822 printf("%d\n", opts->m_len); 823 #endif 824 } 825 ip_stripoptions(m); 826 } 827 m_tag_delete_nonpersistent(m); 828 m->m_flags &= ~(M_BCAST|M_MCAST); 829 icmp_send(m, opts); 830 done: 831 if (opts) 832 (void)m_free(opts); 833 } 834 835 /* 836 * Send an icmp packet back to the ip level, 837 * after supplying a checksum. 838 */ 839 static void 840 icmp_send(struct mbuf *m, struct mbuf *opts) 841 { 842 register struct ip *ip = mtod(m, struct ip *); 843 register int hlen; 844 register struct icmp *icp; 845 846 hlen = ip->ip_hl << 2; 847 m->m_data += hlen; 848 m->m_len -= hlen; 849 icp = mtod(m, struct icmp *); 850 icp->icmp_cksum = 0; 851 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 852 m->m_data -= hlen; 853 m->m_len += hlen; 854 m->m_pkthdr.rcvif = (struct ifnet *)0; 855 #ifdef ICMPPRINTFS 856 if (icmpprintfs) { 857 char buf[4 * sizeof "123"]; 858 strcpy(buf, inet_ntoa(ip->ip_dst)); 859 printf("icmp_send dst %s src %s\n", 860 buf, inet_ntoa(ip->ip_src)); 861 } 862 #endif 863 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 864 } 865 866 /* 867 * Return milliseconds since 00:00 UTC in network format. 868 */ 869 uint32_t 870 iptime(void) 871 { 872 struct timeval atv; 873 u_long t; 874 875 getmicrotime(&atv); 876 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 877 return (htonl(t)); 878 } 879 880 /* 881 * Return the next larger or smaller MTU plateau (table from RFC 1191) 882 * given current value MTU. If DIR is less than zero, a larger plateau 883 * is returned; otherwise, a smaller value is returned. 884 */ 885 int 886 ip_next_mtu(int mtu, int dir) 887 { 888 static int mtutab[] = { 889 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 890 296, 68, 0 891 }; 892 int i, size; 893 894 size = (sizeof mtutab) / (sizeof mtutab[0]); 895 if (dir >= 0) { 896 for (i = 0; i < size; i++) 897 if (mtu > mtutab[i]) 898 return mtutab[i]; 899 } else { 900 for (i = size - 1; i >= 0; i--) 901 if (mtu < mtutab[i]) 902 return mtutab[i]; 903 if (mtu == mtutab[0]) 904 return mtutab[0]; 905 } 906 return 0; 907 } 908 #endif /* INET */ 909 910 911 /* 912 * badport_bandlim() - check for ICMP bandwidth limit 913 * 914 * Return 0 if it is ok to send an ICMP error response, -1 if we have 915 * hit our bandwidth limit and it is not ok. 916 * 917 * If icmplim is <= 0, the feature is disabled and 0 is returned. 918 * 919 * For now we separate the TCP and UDP subsystems w/ different 'which' 920 * values. We may eventually remove this separation (and simplify the 921 * code further). 922 * 923 * Note that the printing of the error message is delayed so we can 924 * properly print the icmp error rate that the system was trying to do 925 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 926 * the 'final' error, but it doesn't make sense to solve the printing 927 * delay with more complex code. 928 */ 929 930 int 931 badport_bandlim(int which) 932 { 933 934 #define N(a) (sizeof (a) / sizeof (a[0])) 935 static struct rate { 936 const char *type; 937 struct timeval lasttime; 938 int curpps; 939 } rates[BANDLIM_MAX+1] = { 940 { "icmp unreach response" }, 941 { "icmp ping response" }, 942 { "icmp tstamp response" }, 943 { "closed port RST response" }, 944 { "open port RST response" }, 945 { "icmp6 unreach response" }, 946 { "sctp ootb response" } 947 }; 948 949 /* 950 * Return ok status if feature disabled or argument out of range. 951 */ 952 if (V_icmplim > 0 && (u_int) which < N(rates)) { 953 struct rate *r = &rates[which]; 954 int opps = r->curpps; 955 956 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 957 return -1; /* discard packet */ 958 /* 959 * If we've dropped below the threshold after having 960 * rate-limited traffic print the message. This preserves 961 * the previous behaviour at the expense of added complexity. 962 */ 963 if (V_icmplim_output && opps > V_icmplim) 964 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 965 r->type, opps, V_icmplim); 966 } 967 return 0; /* okay to send packet */ 968 #undef N 969 } 970