ip_icmp.c revision 299828
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 299828 2016-05-15 03:19:53Z markj $"); 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 */ 81static VNET_DEFINE(int, icmplim) = 200; 82#define V_icmplim VNET(icmplim) 83SYSCTL_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 87static VNET_DEFINE(int, icmplim_output) = 1; 88#define V_icmplim_output VNET(icmplim_output) 89SYSCTL_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 94VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat); 95VNET_PCPUSTAT_SYSINIT(icmpstat); 96SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat, 97 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)"); 98 99#ifdef VIMAGE 100VNET_PCPUSTAT_SYSUNINIT(icmpstat); 101#endif /* VIMAGE */ 102 103static VNET_DEFINE(int, icmpmaskrepl) = 0; 104#define V_icmpmaskrepl VNET(icmpmaskrepl) 105SYSCTL_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 109static VNET_DEFINE(u_int, icmpmaskfake) = 0; 110#define V_icmpmaskfake VNET(icmpmaskfake) 111SYSCTL_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 115VNET_DEFINE(int, drop_redirect) = 0; 116#define V_drop_redirect VNET(drop_redirect) 117SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW, 118 &VNET_NAME(drop_redirect), 0, 119 "Ignore ICMP redirects"); 120 121static VNET_DEFINE(int, log_redirect) = 0; 122#define V_log_redirect VNET(log_redirect) 123SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW, 124 &VNET_NAME(log_redirect), 0, 125 "Log ICMP redirects to the console"); 126 127static VNET_DEFINE(char, reply_src[IFNAMSIZ]); 128#define V_reply_src VNET(reply_src) 129SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW, 130 &VNET_NAME(reply_src), IFNAMSIZ, 131 "ICMP reply source for non-local packets"); 132 133static VNET_DEFINE(int, icmp_rfi) = 0; 134#define V_icmp_rfi VNET(icmp_rfi) 135SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW, 136 &VNET_NAME(icmp_rfi), 0, 137 "ICMP reply from incoming interface for non-local packets"); 138 139static VNET_DEFINE(int, icmp_quotelen) = 8; 140#define V_icmp_quotelen VNET(icmp_quotelen) 141SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW, 142 &VNET_NAME(icmp_quotelen), 0, 143 "Number of bytes from original packet to quote in ICMP reply"); 144 145static VNET_DEFINE(int, icmpbmcastecho) = 0; 146#define V_icmpbmcastecho VNET(icmpbmcastecho) 147SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW, 148 &VNET_NAME(icmpbmcastecho), 0, 149 "Reply to multicast ICMP Echo Request and Timestamp packets"); 150 151static VNET_DEFINE(int, icmptstamprepl) = 1; 152#define V_icmptstamprepl VNET(icmptstamprepl) 153SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW, 154 &VNET_NAME(icmptstamprepl), 0, 155 "Respond to ICMP Timestamp packets"); 156 157#ifdef ICMPPRINTFS 158int icmpprintfs = 0; 159#endif 160 161static void icmp_reflect(struct mbuf *); 162static void icmp_send(struct mbuf *, struct mbuf *); 163 164extern 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 */ 173void 174kmod_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 */ 184void 185icmp_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 * Unfortunately 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 253stdreply: 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 325freeit: 326 m_freem(n); 327} 328 329/* 330 * Process a received ICMP message. 331 */ 332int 333icmp_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 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp)); 478 ip_stripoptions(m); 479 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 480 /* This should actually not happen */ 481 ICMPSTAT_INC(icps_tooshort); 482 return (IPPROTO_DONE); 483 } 484 ip = mtod(m, struct ip *); 485 icp = (struct icmp *)(ip + 1); 486 /* 487 * The upper layer handler can rely on: 488 * - The outer IP header has no options. 489 * - The outer IP header, the ICMP header, the inner IP header, 490 * and the first n bytes of the inner payload are contiguous. 491 * n is at least 8, but might be larger based on 492 * ICMP_ADVLENPREF. See its definition in ip_icmp.h. 493 */ 494 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 495 if (ctlfunc) 496 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 497 (void *)&icp->icmp_ip); 498 break; 499 500 badcode: 501 ICMPSTAT_INC(icps_badcode); 502 break; 503 504 case ICMP_ECHO: 505 if (!V_icmpbmcastecho 506 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 507 ICMPSTAT_INC(icps_bmcastecho); 508 break; 509 } 510 icp->icmp_type = ICMP_ECHOREPLY; 511 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 512 goto freeit; 513 else 514 goto reflect; 515 516 case ICMP_TSTAMP: 517 if (V_icmptstamprepl == 0) 518 break; 519 if (!V_icmpbmcastecho 520 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 521 ICMPSTAT_INC(icps_bmcasttstamp); 522 break; 523 } 524 if (icmplen < ICMP_TSLEN) { 525 ICMPSTAT_INC(icps_badlen); 526 break; 527 } 528 icp->icmp_type = ICMP_TSTAMPREPLY; 529 icp->icmp_rtime = iptime(); 530 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 531 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 532 goto freeit; 533 else 534 goto reflect; 535 536 case ICMP_MASKREQ: 537 if (V_icmpmaskrepl == 0) 538 break; 539 /* 540 * We are not able to respond with all ones broadcast 541 * unless we receive it over a point-to-point interface. 542 */ 543 if (icmplen < ICMP_MASKLEN) 544 break; 545 switch (ip->ip_dst.s_addr) { 546 547 case INADDR_BROADCAST: 548 case INADDR_ANY: 549 icmpdst.sin_addr = ip->ip_src; 550 break; 551 552 default: 553 icmpdst.sin_addr = ip->ip_dst; 554 } 555 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 556 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 557 if (ia == NULL) 558 break; 559 if (ia->ia_ifp == NULL) { 560 ifa_free(&ia->ia_ifa); 561 break; 562 } 563 icp->icmp_type = ICMP_MASKREPLY; 564 if (V_icmpmaskfake == 0) 565 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 566 else 567 icp->icmp_mask = V_icmpmaskfake; 568 if (ip->ip_src.s_addr == 0) { 569 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 570 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 571 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 572 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 573 } 574 ifa_free(&ia->ia_ifa); 575reflect: 576 ICMPSTAT_INC(icps_reflect); 577 ICMPSTAT_INC(icps_outhist[icp->icmp_type]); 578 icmp_reflect(m); 579 return (IPPROTO_DONE); 580 581 case ICMP_REDIRECT: 582 if (V_log_redirect) { 583 u_long src, dst, gw; 584 585 src = ntohl(ip->ip_src.s_addr); 586 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 587 gw = ntohl(icp->icmp_gwaddr.s_addr); 588 printf("icmp redirect from %d.%d.%d.%d: " 589 "%d.%d.%d.%d => %d.%d.%d.%d\n", 590 (int)(src >> 24), (int)((src >> 16) & 0xff), 591 (int)((src >> 8) & 0xff), (int)(src & 0xff), 592 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 593 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 594 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 595 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 596 } 597 /* 598 * RFC1812 says we must ignore ICMP redirects if we 599 * are acting as router. 600 */ 601 if (V_drop_redirect || V_ipforwarding) 602 break; 603 if (code > 3) 604 goto badcode; 605 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 606 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 607 ICMPSTAT_INC(icps_badlen); 608 break; 609 } 610 /* 611 * Short circuit routing redirects to force 612 * immediate change in the kernel's routing 613 * tables. The message is also handed to anyone 614 * listening on a raw socket (e.g. the routing 615 * daemon for use in updating its tables). 616 */ 617 icmpgw.sin_addr = ip->ip_src; 618 icmpdst.sin_addr = icp->icmp_gwaddr; 619#ifdef ICMPPRINTFS 620 if (icmpprintfs) { 621 char buf[4 * sizeof "123"]; 622 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 623 624 printf("redirect dst %s to %s\n", 625 buf, inet_ntoa(icp->icmp_gwaddr)); 626 } 627#endif 628 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 629 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) { 630 in_rtredirect((struct sockaddr *)&icmpsrc, 631 (struct sockaddr *)&icmpdst, 632 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 633 (struct sockaddr *)&icmpgw, fibnum); 634 } 635 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 636 break; 637 638 /* 639 * No kernel processing for the following; 640 * just fall through to send to raw listener. 641 */ 642 case ICMP_ECHOREPLY: 643 case ICMP_ROUTERADVERT: 644 case ICMP_ROUTERSOLICIT: 645 case ICMP_TSTAMPREPLY: 646 case ICMP_IREQREPLY: 647 case ICMP_MASKREPLY: 648 case ICMP_SOURCEQUENCH: 649 default: 650 break; 651 } 652 653raw: 654 *mp = m; 655 rip_input(mp, offp, proto); 656 return (IPPROTO_DONE); 657 658freeit: 659 m_freem(m); 660 return (IPPROTO_DONE); 661} 662 663/* 664 * Reflect the ip packet back to the source 665 */ 666static void 667icmp_reflect(struct mbuf *m) 668{ 669 struct rm_priotracker in_ifa_tracker; 670 struct ip *ip = mtod(m, struct ip *); 671 struct ifaddr *ifa; 672 struct ifnet *ifp; 673 struct in_ifaddr *ia; 674 struct in_addr t; 675 struct nhop4_extended nh_ext; 676 struct mbuf *opts = NULL; 677 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 678 679 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 680 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) || 681 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) { 682 m_freem(m); /* Bad return address */ 683 ICMPSTAT_INC(icps_badaddr); 684 goto done; /* Ip_output() will check for broadcast */ 685 } 686 687 t = ip->ip_dst; 688 ip->ip_dst = ip->ip_src; 689 690 /* 691 * Source selection for ICMP replies: 692 * 693 * If the incoming packet was addressed directly to one of our 694 * own addresses, use dst as the src for the reply. 695 */ 696 IN_IFADDR_RLOCK(&in_ifa_tracker); 697 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) { 698 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) { 699 t = IA_SIN(ia)->sin_addr; 700 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 701 goto match; 702 } 703 } 704 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 705 706 /* 707 * If the incoming packet was addressed to one of our broadcast 708 * addresses, use the first non-broadcast address which corresponds 709 * to the incoming interface. 710 */ 711 ifp = m->m_pkthdr.rcvif; 712 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) { 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 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 719 t.s_addr) { 720 t = IA_SIN(ia)->sin_addr; 721 IF_ADDR_RUNLOCK(ifp); 722 goto match; 723 } 724 } 725 IF_ADDR_RUNLOCK(ifp); 726 } 727 /* 728 * If the packet was transiting through us, use the address of 729 * the interface the packet came through in. If that interface 730 * doesn't have a suitable IP address, the normal selection 731 * criteria apply. 732 */ 733 if (V_icmp_rfi && ifp != NULL) { 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 incoming packet was not addressed directly to us, use 747 * designated interface for icmp replies specified by sysctl 748 * net.inet.icmp.reply_src (default not set). Otherwise continue 749 * with normal source selection. 750 */ 751 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) { 752 IF_ADDR_RLOCK(ifp); 753 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 754 if (ifa->ifa_addr->sa_family != AF_INET) 755 continue; 756 ia = ifatoia(ifa); 757 t = IA_SIN(ia)->sin_addr; 758 IF_ADDR_RUNLOCK(ifp); 759 goto match; 760 } 761 IF_ADDR_RUNLOCK(ifp); 762 } 763 /* 764 * If the packet was transiting through us, use the address of 765 * the interface that is the closest to the packet source. 766 * When we don't have a route back to the packet source, stop here 767 * and drop the packet. 768 */ 769 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) { 770 m_freem(m); 771 ICMPSTAT_INC(icps_noroute); 772 goto done; 773 } 774 t = nh_ext.nh_src; 775match: 776#ifdef MAC 777 mac_netinet_icmp_replyinplace(m); 778#endif 779 ip->ip_src = t; 780 ip->ip_ttl = V_ip_defttl; 781 782 if (optlen > 0) { 783 register u_char *cp; 784 int opt, cnt; 785 u_int len; 786 787 /* 788 * Retrieve any source routing from the incoming packet; 789 * add on any record-route or timestamp options. 790 */ 791 cp = (u_char *) (ip + 1); 792 if ((opts = ip_srcroute(m)) == NULL && 793 (opts = m_gethdr(M_NOWAIT, MT_DATA))) { 794 opts->m_len = sizeof(struct in_addr); 795 mtod(opts, struct in_addr *)->s_addr = 0; 796 } 797 if (opts) { 798#ifdef ICMPPRINTFS 799 if (icmpprintfs) 800 printf("icmp_reflect optlen %d rt %d => ", 801 optlen, opts->m_len); 802#endif 803 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 804 opt = cp[IPOPT_OPTVAL]; 805 if (opt == IPOPT_EOL) 806 break; 807 if (opt == IPOPT_NOP) 808 len = 1; 809 else { 810 if (cnt < IPOPT_OLEN + sizeof(*cp)) 811 break; 812 len = cp[IPOPT_OLEN]; 813 if (len < IPOPT_OLEN + sizeof(*cp) || 814 len > cnt) 815 break; 816 } 817 /* 818 * Should check for overflow, but it "can't happen" 819 */ 820 if (opt == IPOPT_RR || opt == IPOPT_TS || 821 opt == IPOPT_SECURITY) { 822 bcopy((caddr_t)cp, 823 mtod(opts, caddr_t) + opts->m_len, len); 824 opts->m_len += len; 825 } 826 } 827 /* Terminate & pad, if necessary */ 828 cnt = opts->m_len % 4; 829 if (cnt) { 830 for (; cnt < 4; cnt++) { 831 *(mtod(opts, caddr_t) + opts->m_len) = 832 IPOPT_EOL; 833 opts->m_len++; 834 } 835 } 836#ifdef ICMPPRINTFS 837 if (icmpprintfs) 838 printf("%d\n", opts->m_len); 839#endif 840 } 841 ip_stripoptions(m); 842 } 843 m_tag_delete_nonpersistent(m); 844 m->m_flags &= ~(M_BCAST|M_MCAST); 845 icmp_send(m, opts); 846done: 847 if (opts) 848 (void)m_free(opts); 849} 850 851/* 852 * Send an icmp packet back to the ip level, 853 * after supplying a checksum. 854 */ 855static void 856icmp_send(struct mbuf *m, struct mbuf *opts) 857{ 858 register struct ip *ip = mtod(m, struct ip *); 859 register int hlen; 860 register struct icmp *icp; 861 862 hlen = ip->ip_hl << 2; 863 m->m_data += hlen; 864 m->m_len -= hlen; 865 icp = mtod(m, struct icmp *); 866 icp->icmp_cksum = 0; 867 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); 868 m->m_data -= hlen; 869 m->m_len += hlen; 870 m->m_pkthdr.rcvif = (struct ifnet *)0; 871#ifdef ICMPPRINTFS 872 if (icmpprintfs) { 873 char buf[4 * sizeof "123"]; 874 strcpy(buf, inet_ntoa(ip->ip_dst)); 875 printf("icmp_send dst %s src %s\n", 876 buf, inet_ntoa(ip->ip_src)); 877 } 878#endif 879 (void) ip_output(m, opts, NULL, 0, NULL, NULL); 880} 881 882/* 883 * Return milliseconds since 00:00 UTC in network format. 884 */ 885uint32_t 886iptime(void) 887{ 888 struct timeval atv; 889 u_long t; 890 891 getmicrotime(&atv); 892 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 893 return (htonl(t)); 894} 895 896/* 897 * Return the next larger or smaller MTU plateau (table from RFC 1191) 898 * given current value MTU. If DIR is less than zero, a larger plateau 899 * is returned; otherwise, a smaller value is returned. 900 */ 901int 902ip_next_mtu(int mtu, int dir) 903{ 904 static int mtutab[] = { 905 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 906 296, 68, 0 907 }; 908 int i, size; 909 910 size = (sizeof mtutab) / (sizeof mtutab[0]); 911 if (dir >= 0) { 912 for (i = 0; i < size; i++) 913 if (mtu > mtutab[i]) 914 return mtutab[i]; 915 } else { 916 for (i = size - 1; i >= 0; i--) 917 if (mtu < mtutab[i]) 918 return mtutab[i]; 919 if (mtu == mtutab[0]) 920 return mtutab[0]; 921 } 922 return 0; 923} 924#endif /* INET */ 925 926 927/* 928 * badport_bandlim() - check for ICMP bandwidth limit 929 * 930 * Return 0 if it is ok to send an ICMP error response, -1 if we have 931 * hit our bandwidth limit and it is not ok. 932 * 933 * If icmplim is <= 0, the feature is disabled and 0 is returned. 934 * 935 * For now we separate the TCP and UDP subsystems w/ different 'which' 936 * values. We may eventually remove this separation (and simplify the 937 * code further). 938 * 939 * Note that the printing of the error message is delayed so we can 940 * properly print the icmp error rate that the system was trying to do 941 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 942 * the 'final' error, but it doesn't make sense to solve the printing 943 * delay with more complex code. 944 */ 945 946int 947badport_bandlim(int which) 948{ 949 950#define N(a) (sizeof (a) / sizeof (a[0])) 951 static struct rate { 952 const char *type; 953 struct timeval lasttime; 954 int curpps; 955 } rates[BANDLIM_MAX+1] = { 956 { "icmp unreach response" }, 957 { "icmp ping response" }, 958 { "icmp tstamp response" }, 959 { "closed port RST response" }, 960 { "open port RST response" }, 961 { "icmp6 unreach response" }, 962 { "sctp ootb response" } 963 }; 964 965 /* 966 * Return ok status if feature disabled or argument out of range. 967 */ 968 if (V_icmplim > 0 && (u_int) which < N(rates)) { 969 struct rate *r = &rates[which]; 970 int opps = r->curpps; 971 972 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim)) 973 return -1; /* discard packet */ 974 /* 975 * If we've dropped below the threshold after having 976 * rate-limited traffic print the message. This preserves 977 * the previous behaviour at the expense of added complexity. 978 */ 979 if (V_icmplim_output && opps > V_icmplim) 980 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n", 981 r->type, opps, V_icmplim); 982 } 983 return 0; /* okay to send packet */ 984#undef N 985} 986