ip_icmp.c revision 275392
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: head/sys/netinet/ip_icmp.c 275392 2014-12-02 04:20:50Z ae $"); 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/sysctl.h> 45#include <sys/syslog.h> 46 47#include <net/if.h> 48#include <net/if_var.h> 49#include <net/if_types.h> 50#include <net/route.h> 51#include <net/vnet.h> 52 53#include <netinet/in.h> 54#include <netinet/in_pcb.h> 55#include <netinet/in_systm.h> 56#include <netinet/in_var.h> 57#include <netinet/ip.h> 58#include <netinet/ip_icmp.h> 59#include <netinet/ip_var.h> 60#include <netinet/ip_options.h> 61#include <netinet/tcp.h> 62#include <netinet/tcp_var.h> 63#include <netinet/tcpip.h> 64#include <netinet/icmp_var.h> 65 66#ifdef INET 67 68#include <machine/in_cksum.h> 69 70#include <security/mac/mac_framework.h> 71#endif /* INET */ 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 */ 78static VNET_DEFINE(int, icmplim) = 200; 79#define V_icmplim VNET(icmplim) 80SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, 81 &VNET_NAME(icmplim), 0, 82 "Maximum number of ICMP responses per second"); 83 84static VNET_DEFINE(int, icmplim_output) = 1; 85#define V_icmplim_output VNET(icmplim_output) 86SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW, 87 &VNET_NAME(icmplim_output), 0, 88 "Enable logging of ICMP response rate limiting"); 89 90#ifdef INET 91VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 92VNET_PCPUSTAT_SYSINIT(icmpstat); 93SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 94 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 95 96#ifdef VIMAGE 97VNET_PCPUSTAT_SYSUNINIT(icmpstat); 98#endif /* VIMAGE */ 99 100static VNET_DEFINE(int, icmpmaskrepl) = 0; 101#define V_icmpmaskrepl VNET(icmpmaskrepl) 102SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW, 103 &VNET_NAME(icmpmaskrepl), 0, 104 "Reply to ICMP Address Mask Request packets."); 105 106static VNET_DEFINE(u_int, icmpmaskfake) = 0; 107#define V_icmpmaskfake VNET(icmpmaskfake) 108SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW, 109 &VNET_NAME(icmpmaskfake), 0, 110 "Fake reply to ICMP Address Mask Request packets."); 111 112VNET_DEFINE(int, drop_redirect) = 0; 113#define V_drop_redirect VNET(drop_redirect) 114SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 115 &VNET_NAME(drop_redirect), 0, "Ignore ICMP redirects"); 116 117static VNET_DEFINE(int, log_redirect) = 0; 118#define V_log_redirect VNET(log_redirect) 119SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW, 120 &VNET_NAME(log_redirect), 0, 121 "Log ICMP redirects to the console"); 122 123static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 124#define V_reply_src VNET(reply_src) 125SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW, 126 &VNET_NAME(reply_src), IFNAMSIZ, 127 "icmp reply source for non-local packets."); 128 129static VNET_DEFINE(int, icmp_rfi) = 0; 130#define V_icmp_rfi VNET(icmp_rfi) 131SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW, 132 &VNET_NAME(icmp_rfi), 0, 133 "ICMP reply from incoming interface for non-local packets"); 134 135static VNET_DEFINE(int, icmp_quotelen) = 8; 136#define V_icmp_quotelen VNET(icmp_quotelen) 137SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | 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 */ 144static VNET_DEFINE(int, icmpbmcastecho) = 0; 145#define V_icmpbmcastecho VNET(icmpbmcastecho) 146SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 147 &VNET_NAME(icmpbmcastecho), 0, 148 ""); 149 150static VNET_DEFINE(int, icmptstamprepl) = 1; 151#define V_icmptstamprepl VNET(icmptstamprepl) 152SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 153 &VNET_NAME(icmptstamprepl), 0, "Respond to ICMP Timestamp packets"); 154 155#ifdef ICMPPRINTFS 156int icmpprintfs = 0; 157#endif 158 159static void icmp_reflect(struct mbuf *); 160static void icmp_send(struct mbuf *, struct mbuf *); 161 162extern struct protosw inetsw[]; 163 164/* 165 * Kernel module interface for updating icmpstat. The argument is an index 166 * into icmpstat treated as an array of u_long. While this encodes the 167 * general layout of icmpstat into the caller, it doesn't encode its 168 * location, so that future changes to add, for example, per-CPU stats 169 * support won't cause binary compatibility problems for kernel modules. 170 */ 171void 172kmod_icmpstat_inc(int statnum) 173{ 174 175 counter_u64_add(VNET(icmpstat)[statnum], 1); 176} 177 178/* 179 * Generate an error packet of type error 180 * in response to bad packet ip. 181 */ 182void 183icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu) 184{ 185 register struct ip *oip = mtod(n, struct ip *), *nip; 186 register unsigned oiphlen = oip->ip_hl << 2; 187 register struct icmp *icp; 188 register struct mbuf *m; 189 unsigned icmplen, icmpelen, nlen; 190 191 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); 192#ifdef ICMPPRINTFS 193 if (icmpprintfs) 194 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 195#endif 196 if (type != ICMP_REDIRECT) 197 ICMPSTAT_INC(icps_error); 198 /* 199 * Don't send error: 200 * if the original packet was encrypted. 201 * if not the first fragment of message. 202 * in response to a multicast or broadcast packet. 203 * if the old packet protocol was an ICMP error message. 204 */ 205 if (n->m_flags & M_DECRYPTED) 206 goto freeit; 207 if (oip->ip_off & htons(~(IP_MF|IP_DF))) 208 goto freeit; 209 if (n->m_flags & (M_BCAST|M_MCAST)) 210 goto freeit; 211 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 212 n->m_len >= oiphlen + ICMP_MINLEN && 213 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { 214 ICMPSTAT_INC(icps_oldicmp); 215 goto freeit; 216 } 217 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ 218 if (oiphlen + 8 > n->m_len) 219 goto freeit; 220 /* 221 * Calculate length to quote from original packet and 222 * prevent the ICMP mbuf from overflowing. 223 * Unfortunatly this is non-trivial since ip_forward() 224 * sends us truncated packets. 225 */ 226 nlen = m_length(n, NULL); 227 if (oip->ip_p == IPPROTO_TCP) { 228 struct tcphdr *th; 229 int tcphlen; 230 231 if (oiphlen + sizeof(struct tcphdr) > n->m_len && 232 n->m_next == NULL) 233 goto stdreply; 234 if (n->m_len < oiphlen + sizeof(struct tcphdr) && 235 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)) 236 goto freeit; 237 th = (struct tcphdr *)((caddr_t)oip + oiphlen); 238 tcphlen = th->th_off << 2; 239 if (tcphlen < sizeof(struct tcphdr)) 240 goto freeit; 241 if (ntohs(oip->ip_len) < oiphlen + tcphlen) 242 goto freeit; 243 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL) 244 goto stdreply; 245 if (n->m_len < oiphlen + tcphlen && 246 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL)) 247 goto freeit; 248 icmpelen = max(tcphlen, min(V_icmp_quotelen, 249 ntohs(oip->ip_len) - oiphlen)); 250 } else 251stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen)); 252 253 icmplen = min(oiphlen + icmpelen, nlen); 254 if (icmplen < sizeof(struct ip)) 255 goto freeit; 256 257 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen) 258 m = m_gethdr(M_NOWAIT, MT_DATA); 259 else 260 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 261 if (m == NULL) 262 goto freeit; 263#ifdef MAC 264 mac_netinet_icmp_reply(n, m); 265#endif 266 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); 267 m_align(m, ICMP_MINLEN + icmplen); 268 m->m_len = ICMP_MINLEN + icmplen; 269 270 /* XXX MRT make the outgoing packet use the same FIB 271 * that was associated with the incoming packet 272 */ 273 M_SETFIB(m, M_GETFIB(n)); 274 icp = mtod(m, struct icmp *); 275 ICMPSTAT_INC(icps_outhist[type]); 276 icp->icmp_type = type; 277 if (type == ICMP_REDIRECT) 278 icp->icmp_gwaddr.s_addr = dest; 279 else { 280 icp->icmp_void = 0; 281 /* 282 * The following assignments assume an overlay with the 283 * just zeroed icmp_void field. 284 */ 285 if (type == ICMP_PARAMPROB) { 286 icp->icmp_pptr = code; 287 code = 0; 288 } else if (type == ICMP_UNREACH && 289 code == ICMP_UNREACH_NEEDFRAG && mtu) { 290 icp->icmp_nextmtu = htons(mtu); 291 } 292 } 293 icp->icmp_code = code; 294 295 /* 296 * Copy the quotation into ICMP message and 297 * convert quoted IP header back to network representation. 298 */ 299 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 300 nip = &icp->icmp_ip; 301 302 /* 303 * Set up ICMP message mbuf and copy old IP header (without options 304 * in front of ICMP message. 305 * If the original mbuf was meant to bypass the firewall, the error 306 * reply should bypass as well. 307 */ 308 m->m_flags |= n->m_flags & M_SKIP_FIREWALL; 309 m->m_data -= sizeof(struct ip); 310 m->m_len += sizeof(struct ip); 311 m->m_pkthdr.len = m->m_len; 312 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 313 nip = mtod(m, struct ip *); 314 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 315 nip->ip_len = htons(m->m_len); 316 nip->ip_v = IPVERSION; 317 nip->ip_hl = 5; 318 nip->ip_p = IPPROTO_ICMP; 319 nip->ip_tos = 0; 320 nip->ip_off = 0; 321 icmp_reflect(m); 322 323freeit: 324 m_freem(n); 325} 326 327/* 328 * Process a received ICMP message. 329 */ 330int 331icmp_input(struct mbuf **mp, int *offp, int proto) 332{ 333 struct icmp *icp; 334 struct in_ifaddr *ia; 335 struct mbuf *m = *mp; 336 struct ip *ip = mtod(m, struct ip *); 337 struct sockaddr_in icmpsrc, icmpdst, icmpgw; 338 int hlen = *offp; 339 int icmplen = ntohs(ip->ip_len) - *offp; 340 int i, code; 341 void (*ctlfunc)(int, struct sockaddr *, void *); 342 int fibnum; 343 344 *mp = NULL; 345 346 /* 347 * Locate icmp structure in mbuf, and check 348 * that not corrupted and of at least minimum length. 349 */ 350#ifdef ICMPPRINTFS 351 if (icmpprintfs) { 352 char buf[4 * sizeof "123"]; 353 strcpy(buf, inet_ntoa(ip->ip_src)); 354 printf("icmp_input from %s to %s, len %d\n", 355 buf, inet_ntoa(ip->ip_dst), icmplen); 356 } 357#endif 358 if (icmplen < ICMP_MINLEN) { 359 ICMPSTAT_INC(icps_tooshort); 360 goto freeit; 361 } 362 i = hlen + min(icmplen, ICMP_ADVLENMIN); 363 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 364 ICMPSTAT_INC(icps_tooshort); 365 return (IPPROTO_DONE); 366 } 367 ip = mtod(m, struct ip *); 368 m->m_len -= hlen; 369 m->m_data += hlen; 370 icp = mtod(m, struct icmp *); 371 if (in_cksum(m, icmplen)) { 372 ICMPSTAT_INC(icps_checksum); 373 goto freeit; 374 } 375 m->m_len += hlen; 376 m->m_data -= hlen; 377 378#ifdef ICMPPRINTFS 379 if (icmpprintfs) 380 printf("icmp_input, type %d code %d\n", icp->icmp_type, 381 icp->icmp_code); 382#endif 383 384 /* 385 * Message type specific processing. 386 */ 387 if (icp->icmp_type > ICMP_MAXTYPE) 388 goto raw; 389 390 /* Initialize */ 391 bzero(&icmpsrc, sizeof(icmpsrc)); 392 icmpsrc.sin_len = sizeof(struct sockaddr_in); 393 icmpsrc.sin_family = AF_INET; 394 bzero(&icmpdst, sizeof(icmpdst)); 395 icmpdst.sin_len = sizeof(struct sockaddr_in); 396 icmpdst.sin_family = AF_INET; 397 bzero(&icmpgw, sizeof(icmpgw)); 398 icmpgw.sin_len = sizeof(struct sockaddr_in); 399 icmpgw.sin_family = AF_INET; 400 401 ICMPSTAT_INC(icps_inhist[icp->icmp_type]); 402 code = icp->icmp_code; 403 switch (icp->icmp_type) { 404 405 case ICMP_UNREACH: 406 switch (code) { 407 case ICMP_UNREACH_NET: 408 case ICMP_UNREACH_HOST: 409 case ICMP_UNREACH_SRCFAIL: 410 case ICMP_UNREACH_NET_UNKNOWN: 411 case ICMP_UNREACH_HOST_UNKNOWN: 412 case ICMP_UNREACH_ISOLATED: 413 case ICMP_UNREACH_TOSNET: 414 case ICMP_UNREACH_TOSHOST: 415 case ICMP_UNREACH_HOST_PRECEDENCE: 416 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 417 code = PRC_UNREACH_NET; 418 break; 419 420 case ICMP_UNREACH_NEEDFRAG: 421 code = PRC_MSGSIZE; 422 break; 423 424 /* 425 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 426 * Treat subcodes 2,3 as immediate RST 427 */ 428 case ICMP_UNREACH_PROTOCOL: 429 case ICMP_UNREACH_PORT: 430 code = PRC_UNREACH_PORT; 431 break; 432 433 case ICMP_UNREACH_NET_PROHIB: 434 case ICMP_UNREACH_HOST_PROHIB: 435 case ICMP_UNREACH_FILTER_PROHIB: 436 code = PRC_UNREACH_ADMIN_PROHIB; 437 break; 438 439 default: 440 goto badcode; 441 } 442 goto deliver; 443 444 case ICMP_TIMXCEED: 445 if (code > 1) 446 goto badcode; 447 code += PRC_TIMXCEED_INTRANS; 448 goto deliver; 449 450 case ICMP_PARAMPROB: 451 if (code > 1) 452 goto badcode; 453 code = PRC_PARAMPROB; 454 deliver: 455 /* 456 * Problem with datagram; advise higher level routines. 457 */ 458 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 459 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 460 ICMPSTAT_INC(icps_badlen); 461 goto freeit; 462 } 463 /* Discard ICMP's in response to multicast packets */ 464 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 465 goto badcode; 466#ifdef ICMPPRINTFS 467 if (icmpprintfs) 468 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 469#endif 470 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 471 /* 472 * XXX if the packet contains [IPv4 AH TCP], we can't make a 473 * notification to TCP layer. 474 */ 475 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 476 if (ctlfunc) 477 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 478 (void *)&icp->icmp_ip); 479 break; 480 481 badcode: 482 ICMPSTAT_INC(icps_badcode); 483 break; 484 485 case ICMP_ECHO: 486 if (!V_icmpbmcastecho 487 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 488 ICMPSTAT_INC(icps_bmcastecho); 489 break; 490 } 491 icp->icmp_type = ICMP_ECHOREPLY; 492 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 493 goto freeit; 494 else 495 goto reflect; 496 497 case ICMP_TSTAMP: 498 if (V_icmptstamprepl == 0) 499 break; 500 if (!V_icmpbmcastecho 501 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 502 ICMPSTAT_INC(icps_bmcasttstamp); 503 break; 504 } 505 if (icmplen < ICMP_TSLEN) { 506 ICMPSTAT_INC(icps_badlen); 507 break; 508 } 509 icp->icmp_type = ICMP_TSTAMPREPLY; 510 icp->icmp_rtime = iptime(); 511 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 512 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 513 goto freeit; 514 else 515 goto reflect; 516 517 case ICMP_MASKREQ: 518 if (V_icmpmaskrepl == 0) 519 break; 520 /* 521 * We are not able to respond with all ones broadcast 522 * unless we receive it over a point-to-point interface. 523 */ 524 if (icmplen < ICMP_MASKLEN) 525 break; 526 switch (ip->ip_dst.s_addr) { 527 528 case INADDR_BROADCAST: 529 case INADDR_ANY: 530 icmpdst.sin_addr = ip->ip_src; 531 break; 532 533 default: 534 icmpdst.sin_addr = ip->ip_dst; 535 } 536 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 537 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 538 if (ia == NULL) 539 break; 540 if (ia->ia_ifp == NULL) { 541 ifa_free(&ia->ia_ifa); 542 break; 543 } 544 icp->icmp_type = ICMP_MASKREPLY; 545 if (V_icmpmaskfake == 0) 546 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 547 else 548 icp->icmp_mask = V_icmpmaskfake; 549 if (ip->ip_src.s_addr == 0) { 550 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 551 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 552 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 553 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 554 } 555 ifa_free(&ia->ia_ifa); 556reflect: 557 ICMPSTAT_INC(icps_reflect); 558 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 559 icmp_reflect(m); 560 return (IPPROTO_DONE); 561 562 case ICMP_REDIRECT: 563 if (V_log_redirect) { 564 u_long src, dst, gw; 565 566 src = ntohl(ip->ip_src.s_addr); 567 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 568 gw = ntohl(icp->icmp_gwaddr.s_addr); 569 printf("icmp redirect from %d.%d.%d.%d: " 570 "%d.%d.%d.%d => %d.%d.%d.%d\n", 571 (int)(src >> 24), (int)((src >> 16) & 0xff), 572 (int)((src >> 8) & 0xff), (int)(src & 0xff), 573 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 574 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 575 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 576 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 577 } 578 /* 579 * RFC1812 says we must ignore ICMP redirects if we 580 * are acting as router. 581 */ 582 if (V_drop_redirect || V_ipforwarding) 583 break; 584 if (code > 3) 585 goto badcode; 586 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 587 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 588 ICMPSTAT_INC(icps_badlen); 589 break; 590 } 591 /* 592 * Short circuit routing redirects to force 593 * immediate change in the kernel's routing 594 * tables. The message is also handed to anyone 595 * listening on a raw socket (e.g. the routing 596 * daemon for use in updating its tables). 597 */ 598 icmpgw.sin_addr = ip->ip_src; 599 icmpdst.sin_addr = icp->icmp_gwaddr; 600#ifdef ICMPPRINTFS 601 if (icmpprintfs) { 602 char buf[4 * sizeof "123"]; 603 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 604 605 printf("redirect dst %s to %s\n", 606 buf, inet_ntoa(icp->icmp_gwaddr)); 607 } 608#endif 609 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 610 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 611 in_rtredirect((struct sockaddr *)&icmpsrc, 612 (struct sockaddr *)&icmpdst, 613 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 614 (struct sockaddr *)&icmpgw, fibnum); 615 } 616 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 617 break; 618 619 /* 620 * No kernel processing for the following; 621 * just fall through to send to raw listener. 622 */ 623 case ICMP_ECHOREPLY: 624 case ICMP_ROUTERADVERT: 625 case ICMP_ROUTERSOLICIT: 626 case ICMP_TSTAMPREPLY: 627 case ICMP_IREQREPLY: 628 case ICMP_MASKREPLY: 629 case ICMP_SOURCEQUENCH: 630 default: 631 break; 632 } 633 634raw: 635 *mp = m; 636 rip_input(mp, offp, proto); 637 return (IPPROTO_DONE); 638 639freeit: 640 m_freem(m); 641 return (IPPROTO_DONE); 642} 643 644/* 645 * Reflect the ip packet back to the source 646 */ 647static void 648icmp_reflect(struct mbuf *m) 649{ 650 struct ip *ip = mtod(m, struct ip *); 651 struct ifaddr *ifa; 652 struct ifnet *ifp; 653 struct in_ifaddr *ia; 654 struct in_addr t; 655 struct mbuf *opts = 0; 656 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 657 658 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 659 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 660 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 661 m_freem(m); /* Bad return address */ 662 ICMPSTAT_INC(icps_badaddr); 663 goto done; /* Ip_output() will check for broadcast */ 664 } 665 666 t = ip->ip_dst; 667 ip->ip_dst = ip->ip_src; 668 669 /* 670 * Source selection for ICMP replies: 671 * 672 * If the incoming packet was addressed directly to one of our 673 * own addresses, use dst as the src for the reply. 674 */ 675 IN_IFADDR_RLOCK(); 676 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 677 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 678 t = IA_SIN(ia)->sin_addr; 679 IN_IFADDR_RUNLOCK(); 680 goto match; 681 } 682 } 683 IN_IFADDR_RUNLOCK(); 684 685 /* 686 * If the incoming packet was addressed to one of our broadcast 687 * addresses, use the first non-broadcast address which corresponds 688 * to the incoming interface. 689 */ 690 ifp = m->m_pkthdr.rcvif; 691 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 692 IF_ADDR_RLOCK(ifp); 693 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 694 if (ifa->ifa_addr->sa_family != AF_INET) 695 continue; 696 ia = ifatoia(ifa); 697 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 698 t.s_addr) { 699 t = IA_SIN(ia)->sin_addr; 700 IF_ADDR_RUNLOCK(ifp); 701 goto match; 702 } 703 } 704 IF_ADDR_RUNLOCK(ifp); 705 } 706 /* 707 * If the packet was transiting through us, use the address of 708 * the interface the packet came through in. If that interface 709 * doesn't have a suitable IP address, the normal selection 710 * criteria apply. 711 */ 712 if (V_icmp_rfi && ifp != NULL) { 713 IF_ADDR_RLOCK(ifp); 714 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 715 if (ifa->ifa_addr->sa_family != AF_INET) 716 continue; 717 ia = ifatoia(ifa); 718 t = IA_SIN(ia)->sin_addr; 719 IF_ADDR_RUNLOCK(ifp); 720 goto match; 721 } 722 IF_ADDR_RUNLOCK(ifp); 723 } 724 /* 725 * If the incoming packet was not addressed directly to us, use 726 * designated interface for icmp replies specified by sysctl 727 * net.inet.icmp.reply_src (default not set). Otherwise continue 728 * with normal source selection. 729 */ 730 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 731 IF_ADDR_RLOCK(ifp); 732 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 733 if (ifa->ifa_addr->sa_family != AF_INET) 734 continue; 735 ia = ifatoia(ifa); 736 t = IA_SIN(ia)->sin_addr; 737 IF_ADDR_RUNLOCK(ifp); 738 goto match; 739 } 740 IF_ADDR_RUNLOCK(ifp); 741 } 742 /* 743 * If the packet was transiting through us, use the address of 744 * the interface that is the closest to the packet source. 745 * When we don't have a route back to the packet source, stop here 746 * and drop the packet. 747 */ 748 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m)); 749 if (ia == NULL) { 750 m_freem(m); 751 ICMPSTAT_INC(icps_noroute); 752 goto done; 753 } 754 t = IA_SIN(ia)->sin_addr; 755 ifa_free(&ia->ia_ifa); 756match: 757#ifdef MAC 758 mac_netinet_icmp_replyinplace(m); 759#endif 760 ip->ip_src = t; 761 ip->ip_ttl = V_ip_defttl; 762 763 if (optlen > 0) { 764 register u_char *cp; 765 int opt, cnt; 766 u_int len; 767 768 /* 769 * Retrieve any source routing from the incoming packet; 770 * add on any record-route or timestamp options. 771 */ 772 cp = (u_char *) (ip + 1); 773 if ((opts = ip_srcroute(m)) == 0 && 774 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 775 opts->m_len = sizeof(struct in_addr); 776 mtod(opts, struct in_addr *)->s_addr = 0; 777 } 778 if (opts) { 779#ifdef ICMPPRINTFS 780 if (icmpprintfs) 781 printf("icmp_reflect optlen %d rt %d => ", 782 optlen, opts->m_len); 783#endif 784 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 785 opt = cp[IPOPT_OPTVAL]; 786 if (opt == IPOPT_EOL) 787 break; 788 if (opt == IPOPT_NOP) 789 len = 1; 790 else { 791 if (cnt < IPOPT_OLEN + sizeof(*cp)) 792 break; 793 len = cp[IPOPT_OLEN]; 794 if (len < IPOPT_OLEN + sizeof(*cp) || 795 len > cnt) 796 break; 797 } 798 /* 799 * Should check for overflow, but it "can't happen" 800 */ 801 if (opt == IPOPT_RR || opt == IPOPT_TS || 802 opt == IPOPT_SECURITY) { 803 bcopy((caddr_t)cp, 804 mtod(opts, caddr_t) + opts->m_len, len); 805 opts->m_len += len; 806 } 807 } 808 /* Terminate & pad, if necessary */ 809 cnt = opts->m_len % 4; 810 if (cnt) { 811 for (; cnt < 4; cnt++) { 812 *(mtod(opts, caddr_t) + opts->m_len) = 813 IPOPT_EOL; 814 opts->m_len++; 815 } 816 } 817#ifdef ICMPPRINTFS 818 if (icmpprintfs) 819 printf("%d\n", opts->m_len); 820#endif 821 } 822 ip_stripoptions(m); 823 } 824 m_tag_delete_nonpersistent(m); 825 m->m_flags &= ~(M_BCAST|M_MCAST); 826 icmp_send(m, opts); 827done: 828 if (opts) 829 (void)m_free(opts); 830} 831 832/* 833 * Send an icmp packet back to the ip level, 834 * after supplying a checksum. 835 */ 836static void 837icmp_send(struct mbuf *m, struct mbuf *opts) 838{ 839 register struct ip *ip = mtod(m, struct ip *); 840 register int hlen; 841 register struct icmp *icp; 842 843 hlen = ip->ip_hl << 2; 844 m->m_data += hlen; 845 m->m_len -= hlen; 846 icp = mtod(m, struct icmp *); 847 icp->icmp_cksum = 0; 848 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 849 m->m_data -= hlen; 850 m->m_len += hlen; 851 m->m_pkthdr.rcvif = (struct ifnet *)0; 852#ifdef ICMPPRINTFS 853 if (icmpprintfs) { 854 char buf[4 * sizeof "123"]; 855 strcpy(buf, inet_ntoa(ip->ip_dst)); 856 printf("icmp_send dst %s src %s\n", 857 buf, inet_ntoa(ip->ip_src)); 858 } 859#endif 860 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 861} 862 863/* 864 * Return milliseconds since 00:00 GMT in network format. 865 */ 866uint32_t 867iptime(void) 868{ 869 struct timeval atv; 870 u_long t; 871 872 getmicrotime(&atv); 873 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 874 return (htonl(t)); 875} 876 877/* 878 * Return the next larger or smaller MTU plateau (table from RFC 1191) 879 * given current value MTU. If DIR is less than zero, a larger plateau 880 * is returned; otherwise, a smaller value is returned. 881 */ 882int 883ip_next_mtu(int mtu, int dir) 884{ 885 static int mtutab[] = { 886 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 887 296, 68, 0 888 }; 889 int i, size; 890 891 size = (sizeof mtutab) / (sizeof mtutab[0]); 892 if (dir >= 0) { 893 for (i = 0; i < size; i++) 894 if (mtu > mtutab[i]) 895 return mtutab[i]; 896 } else { 897 for (i = size - 1; i >= 0; i--) 898 if (mtu < mtutab[i]) 899 return mtutab[i]; 900 if (mtu == mtutab[0]) 901 return mtutab[0]; 902 } 903 return 0; 904} 905#endif /* INET */ 906 907 908/* 909 * badport_bandlim() - check for ICMP bandwidth limit 910 * 911 * Return 0 if it is ok to send an ICMP error response, -1 if we have 912 * hit our bandwidth limit and it is not ok. 913 * 914 * If icmplim is <= 0, the feature is disabled and 0 is returned. 915 * 916 * For now we separate the TCP and UDP subsystems w/ different 'which' 917 * values. We may eventually remove this separation (and simplify the 918 * code further). 919 * 920 * Note that the printing of the error message is delayed so we can 921 * properly print the icmp error rate that the system was trying to do 922 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 923 * the 'final' error, but it doesn't make sense to solve the printing 924 * delay with more complex code. 925 */ 926 927int 928badport_bandlim(int which) 929{ 930 931#define N(a) (sizeof (a) / sizeof (a[0])) 932 static struct rate { 933 const char *type; 934 struct timeval lasttime; 935 int curpps; 936 } rates[BANDLIM_MAX+1] = { 937 { "icmp unreach response" }, 938 { "icmp ping response" }, 939 { "icmp tstamp response" }, 940 { "closed port RST response" }, 941 { "open port RST response" }, 942 { "icmp6 unreach response" }, 943 { "sctp ootb response" } 944 }; 945 946 /* 947 * Return ok status if feature disabled or argument out of range. 948 */ 949 if (V_icmplim > 0 && (u_int) which < N(rates)) { 950 struct rate *r = &rates[which]; 951 int opps = r->curpps; 952 953 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 954 return -1; /* discard packet */ 955 /* 956 * If we've dropped below the threshold after having 957 * rate-limited traffic print the message. This preserves 958 * the previous behaviour at the expense of added complexity. 959 */ 960 if (V_icmplim_output && opps > V_icmplim) 961 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 962 r->type, opps, V_icmplim); 963 } 964 return 0; /* okay to send packet */ 965#undef N 966} 967