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_pcb.h> 57 #include <netinet/in_systm.h> 58 #include <netinet/in_var.h> 59 #include <netinet/ip.h> 60 #include <netinet/ip_icmp.h> 61 #include <netinet/ip_var.h> 62 #include <netinet/ip_options.h> 63 #include <netinet/tcp.h> 64 #include <netinet/tcp_var.h> 65 #include <netinet/tcpip.h> 66 #include <netinet/icmp_var.h> 67 68 #ifdef INET 69 70 #include <machine/in_cksum.h> 71 72 #include <security/mac/mac_framework.h> 73 #endif /* INET */ 74 75 /* 76 * ICMP routines: error generation, receive packet processing, and 77 * routines to turnaround packets back to the originator, and 78 * host table maintenance routines. 79 */ 80 static VNET_DEFINE(int, icmplim) = 200; 81 #define V_icmplim VNET(icmplim) 82 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, 83 &VNET_NAME(icmplim), 0, 84 "Maximum number of ICMP responses per second"); 85 86 static VNET_DEFINE(int, icmplim_output) = 1; 87 #define V_icmplim_output VNET(icmplim_output) 88 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW, 89 &VNET_NAME(icmplim_output), 0, 90 "Enable logging of ICMP response rate limiting"); 91 92 #ifdef INET 93 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 94 VNET_PCPUSTAT_SYSINIT(icmpstat); 95 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 96 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 97 98 #ifdef VIMAGE 99 VNET_PCPUSTAT_SYSUNINIT(icmpstat); 100 #endif /* VIMAGE */ 101 102 static VNET_DEFINE(int, icmpmaskrepl) = 0; 103 #define V_icmpmaskrepl VNET(icmpmaskrepl) 104 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 105 &VNET_NAME(icmpmaskrepl), 0, 106 "Reply to ICMP Address Mask Request packets."); 107 108 static VNET_DEFINE(u_int, icmpmaskfake) = 0; 109 #define V_icmpmaskfake VNET(icmpmaskfake) 110 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW, 111 &VNET_NAME(icmpmaskfake), 0, 112 "Fake reply to ICMP Address Mask Request packets."); 113 114 VNET_DEFINE(int, drop_redirect) = 0; 115 #define V_drop_redirect VNET(drop_redirect) 116 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 117 &VNET_NAME(drop_redirect), 0, "Ignore ICMP redirects"); 118 119 static VNET_DEFINE(int, log_redirect) = 0; 120 #define V_log_redirect VNET(log_redirect) 121 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | 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_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | 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_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | 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_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | 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_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 149 &VNET_NAME(icmpbmcastecho), 0, 150 ""); 151 152 static VNET_DEFINE(int, icmptstamprepl) = 1; 153 #define V_icmptstamprepl VNET(icmptstamprepl) 154 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 155 &VNET_NAME(icmptstamprepl), 0, "Respond to ICMP Timestamp packets"); 156 157 #ifdef ICMPPRINTFS 158 int icmpprintfs = 0; 159 #endif 160 161 static void icmp_reflect(struct mbuf *); 162 static void icmp_send(struct mbuf *, struct mbuf *); 163 164 extern struct protosw inetsw[]; 165 166 /* 167 * Kernel module interface for updating icmpstat. The argument is an index 168 * into icmpstat treated as an array of u_long. While this encodes the 169 * general layout of icmpstat into the caller, it doesn't encode its 170 * location, so that future changes to add, for example, per-CPU stats 171 * support won't cause binary compatibility problems for kernel modules. 172 */ 173 void 174 kmod_icmpstat_inc(int statnum) 175 { 176 177 counter_u64_add(VNET(icmpstat)[statnum], 1); 178 } 179 180 /* 181 * Generate an error packet of type error 182 * in response to bad packet ip. 183 */ 184 void 185 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 186 { 187 register struct ip *oip = mtod(n, struct ip *), *nip; 188 register unsigned oiphlen = oip->ip_hl << 2; 189 register struct icmp *icp; 190 register struct mbuf *m; 191 unsigned icmplen, icmpelen, nlen; 192 193 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 194 #ifdef ICMPPRINTFS 195 if (icmpprintfs) 196 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 197 #endif 198 if (type != ICMP_REDIRECT) 199 ICMPSTAT_INC(icps_error); 200 /* 201 * Don't send error: 202 * if the original packet was encrypted. 203 * if not the first fragment of message. 204 * in response to a multicast or broadcast packet. 205 * if the old packet protocol was an ICMP error message. 206 */ 207 if (n->m_flags & M_DECRYPTED) 208 goto freeit; 209 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 210 goto freeit; 211 if (n->m_flags & (M_BCAST|M_MCAST)) 212 goto freeit; 213 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 214 n->m_len >= oiphlen + ICMP_MINLEN && 215 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 216 ICMPSTAT_INC(icps_oldicmp); 217 goto freeit; 218 } 219 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 220 if (oiphlen + 8 > n->m_len) 221 goto freeit; 222 /* 223 * Calculate length to quote from original packet and 224 * prevent the ICMP mbuf from overflowing. 225 * Unfortunatly this is non-trivial since ip_forward() 226 * sends us truncated packets. 227 */ 228 nlen = m_length(n, NULL); 229 if (oip->ip_p == IPPROTO_TCP) { 230 struct tcphdr *th; 231 int tcphlen; 232 233 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 234 n->m_next == NULL) 235 goto stdreply; 236 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 237 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 238 goto freeit; 239 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 240 tcphlen = th->th_off << 2; 241 if (tcphlen < sizeof(struct tcphdr)) 242 goto freeit; 243 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 244 goto freeit; 245 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 246 goto stdreply; 247 if (n->m_len < oiphlen + tcphlen && 248 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 249 goto freeit; 250 icmpelen = max(tcphlen, min(V_icmp_quotelen, 251 ntohs(oip->ip_len) - oiphlen)); 252 } else 253 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 254 255 icmplen = min(oiphlen + icmpelen, nlen); 256 if (icmplen < sizeof(struct ip)) 257 goto freeit; 258 259 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 260 m = m_gethdr(M_NOWAIT, MT_DATA); 261 else 262 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 263 if (m == NULL) 264 goto freeit; 265 #ifdef MAC 266 mac_netinet_icmp_reply(n, m); 267 #endif 268 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 269 m_align(m, ICMP_MINLEN + icmplen); 270 m->m_len = ICMP_MINLEN + icmplen; 271 272 /* XXX MRT make the outgoing packet use the same FIB 273 * that was associated with the incoming packet 274 */ 275 M_SETFIB(m, M_GETFIB(n)); 276 icp = mtod(m, struct icmp *); 277 ICMPSTAT_INC(icps_outhist[type]); 278 icp->icmp_type = type; 279 if (type == ICMP_REDIRECT) 280 icp->icmp_gwaddr.s_addr = dest; 281 else { 282 icp->icmp_void = 0; 283 /* 284 * The following assignments assume an overlay with the 285 * just zeroed icmp_void field. 286 */ 287 if (type == ICMP_PARAMPROB) { 288 icp->icmp_pptr = code; 289 code = 0; 290 } else if (type == ICMP_UNREACH && 291 code == ICMP_UNREACH_NEEDFRAG && mtu) { 292 icp->icmp_nextmtu = htons(mtu); 293 } 294 } 295 icp->icmp_code = code; 296 297 /* 298 * Copy the quotation into ICMP message and 299 * convert quoted IP header back to network representation. 300 */ 301 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 302 nip = &icp->icmp_ip; 303 304 /* 305 * Set up ICMP message mbuf and copy old IP header (without options 306 * in front of ICMP message. 307 * If the original mbuf was meant to bypass the firewall, the error 308 * reply should bypass as well. 309 */ 310 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 311 m->m_data -= sizeof(struct ip); 312 m->m_len += sizeof(struct ip); 313 m->m_pkthdr.len = m->m_len; 314 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 315 nip = mtod(m, struct ip *); 316 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 317 nip->ip_len = htons(m->m_len); 318 nip->ip_v = IPVERSION; 319 nip->ip_hl = 5; 320 nip->ip_p = IPPROTO_ICMP; 321 nip->ip_tos = 0; 322 nip->ip_off = 0; 323 icmp_reflect(m); 324 325 freeit: 326 m_freem(n); 327 } 328 329 /* 330 * Process a received ICMP message. 331 */ 332 int 333 icmp_input(struct mbuf **mp, int *offp, int proto) 334 { 335 struct icmp *icp; 336 struct in_ifaddr *ia; 337 struct mbuf *m = *mp; 338 struct ip *ip = mtod(m, struct ip *); 339 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 340 int hlen = *offp; 341 int icmplen = ntohs(ip->ip_len) - *offp; 342 int i, code; 343 void (*ctlfunc)(int, struct sockaddr *, void *); 344 int fibnum; 345 346 *mp = NULL; 347 348 /* 349 * Locate icmp structure in mbuf, and check 350 * that not corrupted and of at least minimum length. 351 */ 352 #ifdef ICMPPRINTFS 353 if (icmpprintfs) { 354 char buf[4 * sizeof "123"]; 355 strcpy(buf, inet_ntoa(ip->ip_src)); 356 printf("icmp_input from %s to %s, len %d\n", 357 buf, inet_ntoa(ip->ip_dst), icmplen); 358 } 359 #endif 360 if (icmplen < ICMP_MINLEN) { 361 ICMPSTAT_INC(icps_tooshort); 362 goto freeit; 363 } 364 i = hlen + min(icmplen, ICMP_ADVLENMIN); 365 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 366 ICMPSTAT_INC(icps_tooshort); 367 return (IPPROTO_DONE); 368 } 369 ip = mtod(m, struct ip *); 370 m->m_len -= hlen; 371 m->m_data += hlen; 372 icp = mtod(m, struct icmp *); 373 if (in_cksum(m, icmplen)) { 374 ICMPSTAT_INC(icps_checksum); 375 goto freeit; 376 } 377 m->m_len += hlen; 378 m->m_data -= hlen; 379 380 #ifdef ICMPPRINTFS 381 if (icmpprintfs) 382 printf("icmp_input, type %d code %d\n", icp->icmp_type, 383 icp->icmp_code); 384 #endif 385 386 /* 387 * Message type specific processing. 388 */ 389 if (icp->icmp_type > ICMP_MAXTYPE) 390 goto raw; 391 392 /* Initialize */ 393 bzero(&icmpsrc, sizeof(icmpsrc)); 394 icmpsrc.sin_len = sizeof(struct sockaddr_in); 395 icmpsrc.sin_family = AF_INET; 396 bzero(&icmpdst, sizeof(icmpdst)); 397 icmpdst.sin_len = sizeof(struct sockaddr_in); 398 icmpdst.sin_family = AF_INET; 399 bzero(&icmpgw, sizeof(icmpgw)); 400 icmpgw.sin_len = sizeof(struct sockaddr_in); 401 icmpgw.sin_family = AF_INET; 402 403 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 404 code = icp->icmp_code; 405 switch (icp->icmp_type) { 406 407 case ICMP_UNREACH: 408 switch (code) { 409 case ICMP_UNREACH_NET: 410 case ICMP_UNREACH_HOST: 411 case ICMP_UNREACH_SRCFAIL: 412 case ICMP_UNREACH_NET_UNKNOWN: 413 case ICMP_UNREACH_HOST_UNKNOWN: 414 case ICMP_UNREACH_ISOLATED: 415 case ICMP_UNREACH_TOSNET: 416 case ICMP_UNREACH_TOSHOST: 417 case ICMP_UNREACH_HOST_PRECEDENCE: 418 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 419 code = PRC_UNREACH_NET; 420 break; 421 422 case ICMP_UNREACH_NEEDFRAG: 423 code = PRC_MSGSIZE; 424 break; 425 426 /* 427 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 428 * Treat subcodes 2,3 as immediate RST 429 */ 430 case ICMP_UNREACH_PROTOCOL: 431 case ICMP_UNREACH_PORT: 432 code = PRC_UNREACH_PORT; 433 break; 434 435 case ICMP_UNREACH_NET_PROHIB: 436 case ICMP_UNREACH_HOST_PROHIB: 437 case ICMP_UNREACH_FILTER_PROHIB: 438 code = PRC_UNREACH_ADMIN_PROHIB; 439 break; 440 441 default: 442 goto badcode; 443 } 444 goto deliver; 445 446 case ICMP_TIMXCEED: 447 if (code > 1) 448 goto badcode; 449 code += PRC_TIMXCEED_INTRANS; 450 goto deliver; 451 452 case ICMP_PARAMPROB: 453 if (code > 1) 454 goto badcode; 455 code = PRC_PARAMPROB; 456 deliver: 457 /* 458 * Problem with datagram; advise higher level routines. 459 */ 460 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 461 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 462 ICMPSTAT_INC(icps_badlen); 463 goto freeit; 464 } 465 /* Discard ICMP's in response to multicast packets */ 466 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 467 goto badcode; 468 #ifdef ICMPPRINTFS 469 if (icmpprintfs) 470 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 471 #endif 472 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 473 /* 474 * XXX if the packet contains [IPv4 AH TCP], we can't make a 475 * notification to TCP layer. 476 */ 477 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 478 if (ctlfunc) 479 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 480 (void *)&icp->icmp_ip); 481 break; 482 483 badcode: 484 ICMPSTAT_INC(icps_badcode); 485 break; 486 487 case ICMP_ECHO: 488 if (!V_icmpbmcastecho 489 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 490 ICMPSTAT_INC(icps_bmcastecho); 491 break; 492 } 493 icp->icmp_type = ICMP_ECHOREPLY; 494 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 495 goto freeit; 496 else 497 goto reflect; 498 499 case ICMP_TSTAMP: 500 if (V_icmptstamprepl == 0) 501 break; 502 if (!V_icmpbmcastecho 503 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 504 ICMPSTAT_INC(icps_bmcasttstamp); 505 break; 506 } 507 if (icmplen < ICMP_TSLEN) { 508 ICMPSTAT_INC(icps_badlen); 509 break; 510 } 511 icp->icmp_type = ICMP_TSTAMPREPLY; 512 icp->icmp_rtime = iptime(); 513 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 514 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 515 goto freeit; 516 else 517 goto reflect; 518 519 case ICMP_MASKREQ: 520 if (V_icmpmaskrepl == 0) 521 break; 522 /* 523 * We are not able to respond with all ones broadcast 524 * unless we receive it over a point-to-point interface. 525 */ 526 if (icmplen < ICMP_MASKLEN) 527 break; 528 switch (ip->ip_dst.s_addr) { 529 530 case INADDR_BROADCAST: 531 case INADDR_ANY: 532 icmpdst.sin_addr = ip->ip_src; 533 break; 534 535 default: 536 icmpdst.sin_addr = ip->ip_dst; 537 } 538 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 539 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 540 if (ia == NULL) 541 break; 542 if (ia->ia_ifp == NULL) { 543 ifa_free(&ia->ia_ifa); 544 break; 545 } 546 icp->icmp_type = ICMP_MASKREPLY; 547 if (V_icmpmaskfake == 0) 548 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 549 else 550 icp->icmp_mask = V_icmpmaskfake; 551 if (ip->ip_src.s_addr == 0) { 552 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 553 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 554 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 555 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 556 } 557 ifa_free(&ia->ia_ifa); 558 reflect: 559 ICMPSTAT_INC(icps_reflect); 560 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 561 icmp_reflect(m); 562 return (IPPROTO_DONE); 563 564 case ICMP_REDIRECT: 565 if (V_log_redirect) { 566 u_long src, dst, gw; 567 568 src = ntohl(ip->ip_src.s_addr); 569 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 570 gw = ntohl(icp->icmp_gwaddr.s_addr); 571 printf("icmp redirect from %d.%d.%d.%d: " 572 "%d.%d.%d.%d => %d.%d.%d.%d\n", 573 (int)(src >> 24), (int)((src >> 16) & 0xff), 574 (int)((src >> 8) & 0xff), (int)(src & 0xff), 575 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 576 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 577 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 578 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 579 } 580 /* 581 * RFC1812 says we must ignore ICMP redirects if we 582 * are acting as router. 583 */ 584 if (V_drop_redirect || V_ipforwarding) 585 break; 586 if (code > 3) 587 goto badcode; 588 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 589 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 590 ICMPSTAT_INC(icps_badlen); 591 break; 592 } 593 /* 594 * Short circuit routing redirects to force 595 * immediate change in the kernel's routing 596 * tables. The message is also handed to anyone 597 * listening on a raw socket (e.g. the routing 598 * daemon for use in updating its tables). 599 */ 600 icmpgw.sin_addr = ip->ip_src; 601 icmpdst.sin_addr = icp->icmp_gwaddr; 602 #ifdef ICMPPRINTFS 603 if (icmpprintfs) { 604 char buf[4 * sizeof "123"]; 605 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 606 607 printf("redirect dst %s to %s\n", 608 buf, inet_ntoa(icp->icmp_gwaddr)); 609 } 610 #endif 611 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 612 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 613 in_rtredirect((struct sockaddr *)&icmpsrc, 614 (struct sockaddr *)&icmpdst, 615 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 616 (struct sockaddr *)&icmpgw, fibnum); 617 } 618 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 619 break; 620 621 /* 622 * No kernel processing for the following; 623 * just fall through to send to raw listener. 624 */ 625 case ICMP_ECHOREPLY: 626 case ICMP_ROUTERADVERT: 627 case ICMP_ROUTERSOLICIT: 628 case ICMP_TSTAMPREPLY: 629 case ICMP_IREQREPLY: 630 case ICMP_MASKREPLY: 631 case ICMP_SOURCEQUENCH: 632 default: 633 break; 634 } 635 636 raw: 637 *mp = m; 638 rip_input(mp, offp, proto); 639 return (IPPROTO_DONE); 640 641 freeit: 642 m_freem(m); 643 return (IPPROTO_DONE); 644 } 645 646 /* 647 * Reflect the ip packet back to the source 648 */ 649 static void 650 icmp_reflect(struct mbuf *m) 651 { 652 struct rm_priotracker in_ifa_tracker; 653 struct ip *ip = mtod(m, struct ip *); 654 struct ifaddr *ifa; 655 struct ifnet *ifp; 656 struct in_ifaddr *ia; 657 struct in_addr t; 658 struct mbuf *opts = 0; 659 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 660 661 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 662 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 663 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 664 m_freem(m); /* Bad return address */ 665 ICMPSTAT_INC(icps_badaddr); 666 goto done; /* Ip_output() will check for broadcast */ 667 } 668 669 t = ip->ip_dst; 670 ip->ip_dst = ip->ip_src; 671 672 /* 673 * Source selection for ICMP replies: 674 * 675 * If the incoming packet was addressed directly to one of our 676 * own addresses, use dst as the src for the reply. 677 */ 678 IN_IFADDR_RLOCK(&in_ifa_tracker); 679 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 680 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 681 t = IA_SIN(ia)->sin_addr; 682 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 683 goto match; 684 } 685 } 686 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 687 688 /* 689 * If the incoming packet was addressed to one of our broadcast 690 * addresses, use the first non-broadcast address which corresponds 691 * to the incoming interface. 692 */ 693 ifp = m->m_pkthdr.rcvif; 694 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 695 IF_ADDR_RLOCK(ifp); 696 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 697 if (ifa->ifa_addr->sa_family != AF_INET) 698 continue; 699 ia = ifatoia(ifa); 700 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 701 t.s_addr) { 702 t = IA_SIN(ia)->sin_addr; 703 IF_ADDR_RUNLOCK(ifp); 704 goto match; 705 } 706 } 707 IF_ADDR_RUNLOCK(ifp); 708 } 709 /* 710 * If the packet was transiting through us, use the address of 711 * the interface the packet came through in. If that interface 712 * doesn't have a suitable IP address, the normal selection 713 * criteria apply. 714 */ 715 if (V_icmp_rfi && ifp != NULL) { 716 IF_ADDR_RLOCK(ifp); 717 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 718 if (ifa->ifa_addr->sa_family != AF_INET) 719 continue; 720 ia = ifatoia(ifa); 721 t = IA_SIN(ia)->sin_addr; 722 IF_ADDR_RUNLOCK(ifp); 723 goto match; 724 } 725 IF_ADDR_RUNLOCK(ifp); 726 } 727 /* 728 * If the incoming packet was not addressed directly to us, use 729 * designated interface for icmp replies specified by sysctl 730 * net.inet.icmp.reply_src (default not set). Otherwise continue 731 * with normal source selection. 732 */ 733 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 734 IF_ADDR_RLOCK(ifp); 735 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 736 if (ifa->ifa_addr->sa_family != AF_INET) 737 continue; 738 ia = ifatoia(ifa); 739 t = IA_SIN(ia)->sin_addr; 740 IF_ADDR_RUNLOCK(ifp); 741 goto match; 742 } 743 IF_ADDR_RUNLOCK(ifp); 744 } 745 /* 746 * If the packet was transiting through us, use the address of 747 * the interface that is the closest to the packet source. 748 * When we don't have a route back to the packet source, stop here 749 * and drop the packet. 750 */ 751 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 752 if (ia == NULL) { 753 m_freem(m); 754 ICMPSTAT_INC(icps_noroute); 755 goto done; 756 } 757 t = IA_SIN(ia)->sin_addr; 758 ifa_free(&ia->ia_ifa); 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