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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 34 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $ 35 * $DragonFly: src/sys/netinet/ip_icmp.c,v 1.27 2007/12/19 12:13:17 sephe Exp $ 36 */ 37 38 #include "opt_ipsec.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/mbuf.h> 43 #include <sys/protosw.h> 44 #include <sys/socket.h> 45 #include <sys/time.h> 46 #include <sys/kernel.h> 47 #include <sys/sysctl.h> 48 #include <sys/in_cksum.h> 49 50 #include <machine/stdarg.h> 51 52 #include <net/if.h> 53 #include <net/if_types.h> 54 #include <net/route.h> 55 56 #define _IP_VHL 57 #include <netinet/in.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/icmp_var.h> 64 65 #ifdef IPSEC 66 #include <netinet6/ipsec.h> 67 #include <netproto/key/key.h> 68 #endif 69 70 #ifdef FAST_IPSEC 71 #include <netproto/ipsec/ipsec.h> 72 #include <netproto/ipsec/key.h> 73 #define IPSEC 74 #endif 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 82 struct icmpstat icmpstat; 83 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 84 &icmpstat, icmpstat, ""); 85 86 static int icmpmaskrepl = 0; 87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 88 &icmpmaskrepl, 0, ""); 89 90 static int drop_redirect = 0; 91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 92 &drop_redirect, 0, ""); 93 94 static int log_redirect = 0; 95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 96 &log_redirect, 0, ""); 97 98 #ifdef ICMP_BANDLIM 99 100 /* 101 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl 102 * variable content is -1 and read-only. 103 */ 104 105 static int icmplim = 200; 106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 107 &icmplim, 0, ""); 108 #else 109 110 static int icmplim = -1; 111 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD, 112 &icmplim, 0, ""); 113 114 #endif 115 116 static int icmplim_output = 1; 117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 118 &icmplim_output, 0, ""); 119 120 /* 121 * ICMP broadcast echo sysctl 122 */ 123 124 static int icmpbmcastecho = 0; 125 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 126 &icmpbmcastecho, 0, ""); 127 128 129 #ifdef ICMPPRINTFS 130 int icmpprintfs = 0; 131 #endif 132 133 static void icmp_reflect (struct mbuf *); 134 static void icmp_send (struct mbuf *, struct mbuf *, struct route *); 135 136 extern struct protosw inetsw[]; 137 138 /* 139 * Generate an error packet of type error 140 * in response to bad packet ip. 141 */ 142 void 143 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu) 144 { 145 struct ip *oip = mtod(n, struct ip *), *nip; 146 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2; 147 struct icmp *icp; 148 struct mbuf *m; 149 unsigned icmplen; 150 151 #ifdef ICMPPRINTFS 152 if (icmpprintfs) 153 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code); 154 #endif 155 if (type != ICMP_REDIRECT) 156 icmpstat.icps_error++; 157 /* 158 * Don't send error if the original packet was encrypted. 159 * Don't send error if not the first fragment of message. 160 * Don't error if the old packet protocol was ICMP 161 * error message, only known informational types. 162 */ 163 if (n->m_flags & M_DECRYPTED) 164 goto freeit; 165 if (oip->ip_off &~ (IP_MF|IP_DF)) 166 goto freeit; 167 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 168 n->m_len >= oiplen + ICMP_MINLEN && 169 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 170 icmpstat.icps_oldicmp++; 171 goto freeit; 172 } 173 /* Don't send error in response to a multicast or broadcast packet */ 174 if (n->m_flags & (M_BCAST|M_MCAST)) 175 goto freeit; 176 /* 177 * First, formulate icmp message 178 */ 179 m = m_gethdr(MB_DONTWAIT, MT_HEADER); 180 if (m == NULL) 181 goto freeit; 182 icmplen = min(oiplen + 8, oip->ip_len); 183 if (icmplen < sizeof(struct ip)) 184 panic("icmp_error: bad length"); 185 m->m_len = icmplen + ICMP_MINLEN; 186 MH_ALIGN(m, m->m_len); 187 icp = mtod(m, struct icmp *); 188 if ((u_int)type > ICMP_MAXTYPE) 189 panic("icmp_error"); 190 icmpstat.icps_outhist[type]++; 191 icp->icmp_type = type; 192 if (type == ICMP_REDIRECT) 193 icp->icmp_gwaddr.s_addr = dest; 194 else { 195 icp->icmp_void = 0; 196 /* 197 * The following assignments assume an overlay with the 198 * zeroed icmp_void field. 199 */ 200 if (type == ICMP_PARAMPROB) { 201 icp->icmp_pptr = code; 202 code = 0; 203 } else if (type == ICMP_UNREACH && 204 code == ICMP_UNREACH_NEEDFRAG && destmtu) { 205 icp->icmp_nextmtu = htons(destmtu); 206 } 207 } 208 209 icp->icmp_code = code; 210 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 211 nip = &icp->icmp_ip; 212 213 /* 214 * Convert fields to network representation. 215 */ 216 nip->ip_len = htons(nip->ip_len); 217 nip->ip_off = htons(nip->ip_off); 218 219 /* 220 * Now, copy old ip header (without options) 221 * in front of icmp message. 222 */ 223 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 224 panic("icmp len"); 225 m->m_data -= sizeof(struct ip); 226 m->m_len += sizeof(struct ip); 227 m->m_pkthdr.len = m->m_len; 228 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 229 nip = mtod(m, struct ip *); 230 bcopy(oip, nip, sizeof(struct ip)); 231 nip->ip_len = m->m_len; 232 nip->ip_vhl = IP_VHL_BORING; 233 nip->ip_p = IPPROTO_ICMP; 234 nip->ip_tos = 0; 235 m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED; 236 icmp_reflect(m); 237 238 freeit: 239 m_freem(n); 240 } 241 242 /* 243 * Process a received ICMP message. 244 */ 245 void 246 icmp_input(struct mbuf *m, ...) 247 { 248 struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET }; 249 struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET }; 250 struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET }; 251 struct icmp *icp; 252 struct in_ifaddr *ia; 253 struct ip *ip = mtod(m, struct ip *); 254 void (*ctlfunc) (int, struct sockaddr *, void *); 255 int icmplen = ip->ip_len; 256 int i, hlen; 257 int code, off, proto; 258 __va_list ap; 259 260 __va_start(ap, m); 261 off = __va_arg(ap, int); 262 proto = __va_arg(ap, int); 263 __va_end(ap); 264 265 hlen = off; 266 267 /* 268 * Locate icmp structure in mbuf, and check 269 * that not corrupted and of at least minimum length. 270 */ 271 #ifdef ICMPPRINTFS 272 if (icmpprintfs) { 273 char buf[sizeof "aaa.bbb.ccc.ddd"]; 274 275 strcpy(buf, inet_ntoa(ip->ip_src)); 276 kprintf("icmp_input from %s to %s, len %d\n", 277 buf, inet_ntoa(ip->ip_dst), icmplen); 278 } 279 #endif 280 if (icmplen < ICMP_MINLEN) { 281 icmpstat.icps_tooshort++; 282 goto freeit; 283 } 284 i = hlen + min(icmplen, ICMP_ADVLENMIN); 285 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 286 icmpstat.icps_tooshort++; 287 return; 288 } 289 ip = mtod(m, struct ip *); 290 m->m_len -= hlen; 291 m->m_data += hlen; 292 icp = mtod(m, struct icmp *); 293 if (in_cksum(m, icmplen)) { 294 icmpstat.icps_checksum++; 295 goto freeit; 296 } 297 m->m_len += hlen; 298 m->m_data -= hlen; 299 300 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 301 /* 302 * Deliver very specific ICMP type only. 303 */ 304 switch (icp->icmp_type) { 305 case ICMP_UNREACH: 306 case ICMP_TIMXCEED: 307 break; 308 default: 309 goto freeit; 310 } 311 } 312 313 #ifdef ICMPPRINTFS 314 if (icmpprintfs) 315 kprintf("icmp_input, type %d code %d\n", icp->icmp_type, 316 icp->icmp_code); 317 #endif 318 319 /* 320 * Message type specific processing. 321 */ 322 if (icp->icmp_type > ICMP_MAXTYPE) 323 goto raw; 324 icmpstat.icps_inhist[icp->icmp_type]++; 325 code = icp->icmp_code; 326 switch (icp->icmp_type) { 327 328 case ICMP_UNREACH: 329 switch (code) { 330 case ICMP_UNREACH_NET: 331 case ICMP_UNREACH_HOST: 332 case ICMP_UNREACH_SRCFAIL: 333 case ICMP_UNREACH_NET_UNKNOWN: 334 case ICMP_UNREACH_HOST_UNKNOWN: 335 case ICMP_UNREACH_ISOLATED: 336 case ICMP_UNREACH_TOSNET: 337 case ICMP_UNREACH_TOSHOST: 338 case ICMP_UNREACH_HOST_PRECEDENCE: 339 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 340 code = PRC_UNREACH_NET; 341 break; 342 343 case ICMP_UNREACH_NEEDFRAG: 344 code = PRC_MSGSIZE; 345 break; 346 347 /* 348 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 349 * Treat subcodes 2,3 as immediate RST 350 */ 351 case ICMP_UNREACH_PROTOCOL: 352 case ICMP_UNREACH_PORT: 353 code = PRC_UNREACH_PORT; 354 break; 355 356 case ICMP_UNREACH_NET_PROHIB: 357 case ICMP_UNREACH_HOST_PROHIB: 358 case ICMP_UNREACH_FILTER_PROHIB: 359 code = PRC_UNREACH_ADMIN_PROHIB; 360 break; 361 362 default: 363 goto badcode; 364 } 365 goto deliver; 366 367 case ICMP_TIMXCEED: 368 if (code > 1) 369 goto badcode; 370 code += PRC_TIMXCEED_INTRANS; 371 goto deliver; 372 373 case ICMP_PARAMPROB: 374 if (code > 1) 375 goto badcode; 376 code = PRC_PARAMPROB; 377 goto deliver; 378 379 case ICMP_SOURCEQUENCH: 380 if (code) 381 goto badcode; 382 code = PRC_QUENCH; 383 deliver: 384 /* 385 * Problem with datagram; advise higher level routines. 386 */ 387 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 388 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 389 icmpstat.icps_badlen++; 390 goto freeit; 391 } 392 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 393 /* Discard ICMP's in response to multicast packets */ 394 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 395 goto badcode; 396 #ifdef ICMPPRINTFS 397 if (icmpprintfs) 398 kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 399 #endif 400 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 401 #if 1 402 /* 403 * MTU discovery: 404 * If we got a needfrag and there is a host route to the 405 * original destination, and the MTU is not locked, then 406 * set the MTU in the route to the suggested new value 407 * (if given) and then notify as usual. The ULPs will 408 * notice that the MTU has changed and adapt accordingly. 409 * If no new MTU was suggested, then we guess a new one 410 * less than the current value. If the new MTU is 411 * unreasonably small (arbitrarily set at 296), then 412 * we reset the MTU to the interface value and enable the 413 * lock bit, indicating that we are no longer doing MTU 414 * discovery. 415 */ 416 if (code == PRC_MSGSIZE) { 417 struct rtentry *rt; 418 int mtu; 419 420 rt = rtpurelookup((struct sockaddr *)&icmpsrc); 421 if (rt != NULL && (rt->rt_flags & RTF_HOST) && 422 !(rt->rt_rmx.rmx_locks & RTV_MTU)) { 423 mtu = ntohs(icp->icmp_nextmtu); 424 if (!mtu) 425 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu, 426 1); 427 #ifdef DEBUG_MTUDISC 428 kprintf("MTU for %s reduced to %d\n", 429 inet_ntoa(icmpsrc.sin_addr), mtu); 430 #endif 431 if (mtu < 296) { 432 /* rt->rt_rmx.rmx_mtu = 433 rt->rt_ifp->if_mtu; */ 434 rt->rt_rmx.rmx_locks |= RTV_MTU; 435 } else if (rt->rt_rmx.rmx_mtu > mtu) { 436 rt->rt_rmx.rmx_mtu = mtu; 437 } 438 } 439 if (rt != NULL) 440 --rt->rt_refcnt; 441 } 442 #endif 443 /* 444 * XXX if the packet contains [IPv4 AH TCP], we can't make a 445 * notification to TCP layer. 446 */ 447 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 448 if (ctlfunc) 449 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 450 &icp->icmp_ip); 451 break; 452 453 badcode: 454 icmpstat.icps_badcode++; 455 break; 456 457 case ICMP_ECHO: 458 if (!icmpbmcastecho 459 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 460 icmpstat.icps_bmcastecho++; 461 break; 462 } 463 icp->icmp_type = ICMP_ECHOREPLY; 464 #ifdef ICMP_BANDLIM 465 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 466 goto freeit; 467 else 468 #endif 469 goto reflect; 470 471 case ICMP_TSTAMP: 472 if (!icmpbmcastecho 473 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 474 icmpstat.icps_bmcasttstamp++; 475 break; 476 } 477 if (icmplen < ICMP_TSLEN) { 478 icmpstat.icps_badlen++; 479 break; 480 } 481 icp->icmp_type = ICMP_TSTAMPREPLY; 482 icp->icmp_rtime = iptime(); 483 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 484 #ifdef ICMP_BANDLIM 485 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 486 goto freeit; 487 else 488 #endif 489 goto reflect; 490 491 case ICMP_MASKREQ: 492 if (icmpmaskrepl == 0) 493 break; 494 /* 495 * We are not able to respond with all ones broadcast 496 * unless we receive it over a point-to-point interface. 497 */ 498 if (icmplen < ICMP_MASKLEN) 499 break; 500 switch (ip->ip_dst.s_addr) { 501 502 case INADDR_BROADCAST: 503 case INADDR_ANY: 504 icmpdst.sin_addr = ip->ip_src; 505 break; 506 507 default: 508 icmpdst.sin_addr = ip->ip_dst; 509 } 510 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 511 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 512 if (ia == 0) 513 break; 514 if (ia->ia_ifp == 0) 515 break; 516 icp->icmp_type = ICMP_MASKREPLY; 517 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 518 if (ip->ip_src.s_addr == 0) { 519 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 520 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 521 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 522 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 523 } 524 reflect: 525 ip->ip_len += hlen; /* since ip_input deducts this */ 526 icmpstat.icps_reflect++; 527 icmpstat.icps_outhist[icp->icmp_type]++; 528 icmp_reflect(m); 529 return; 530 531 case ICMP_REDIRECT: 532 if (log_redirect) { 533 u_long src, dst, gw; 534 535 src = ntohl(ip->ip_src.s_addr); 536 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 537 gw = ntohl(icp->icmp_gwaddr.s_addr); 538 kprintf("icmp redirect from %d.%d.%d.%d: " 539 "%d.%d.%d.%d => %d.%d.%d.%d\n", 540 (int)(src >> 24), (int)((src >> 16) & 0xff), 541 (int)((src >> 8) & 0xff), (int)(src & 0xff), 542 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 543 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 544 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 545 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 546 } 547 if (drop_redirect) 548 break; 549 if (code > 3) 550 goto badcode; 551 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 552 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 553 icmpstat.icps_badlen++; 554 break; 555 } 556 /* 557 * Short circuit routing redirects to force 558 * immediate change in the kernel's routing 559 * tables. The message is also handed to anyone 560 * listening on a raw socket (e.g. the routing 561 * daemon for use in updating its tables). 562 */ 563 icmpgw.sin_addr = ip->ip_src; 564 icmpdst.sin_addr = icp->icmp_gwaddr; 565 #ifdef ICMPPRINTFS 566 if (icmpprintfs) { 567 char buf[sizeof "aaa.bbb.ccc.ddd"]; 568 569 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 570 kprintf("redirect dst %s to %s\n", 571 buf, inet_ntoa(icp->icmp_gwaddr)); 572 } 573 #endif 574 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 575 rtredirect((struct sockaddr *)&icmpsrc, 576 (struct sockaddr *)&icmpdst, 577 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 578 (struct sockaddr *)&icmpgw); 579 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 580 #ifdef IPSEC 581 key_sa_routechange((struct sockaddr *)&icmpsrc); 582 #endif 583 break; 584 585 /* 586 * No kernel processing for the following; 587 * just fall through to send to raw listener. 588 */ 589 case ICMP_ECHOREPLY: 590 case ICMP_ROUTERADVERT: 591 case ICMP_ROUTERSOLICIT: 592 case ICMP_TSTAMPREPLY: 593 case ICMP_IREQREPLY: 594 case ICMP_MASKREPLY: 595 default: 596 break; 597 } 598 599 raw: 600 rip_input(m, off, proto); 601 return; 602 603 freeit: 604 m_freem(m); 605 } 606 607 /* 608 * Reflect the ip packet back to the source 609 */ 610 static void 611 icmp_reflect(struct mbuf *m) 612 { 613 struct ip *ip = mtod(m, struct ip *); 614 struct ifaddr *ifa; 615 struct in_ifaddr *ia; 616 struct in_addr t; 617 struct mbuf *opts = 0; 618 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip); 619 struct route *ro = NULL, rt; 620 621 if (!in_canforward(ip->ip_src) && 622 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 623 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 624 m_freem(m); /* Bad return address */ 625 icmpstat.icps_badaddr++; 626 goto done; /* Ip_output() will check for broadcast */ 627 } 628 t = ip->ip_dst; 629 ip->ip_dst = ip->ip_src; 630 ro = &rt; 631 bzero(ro, sizeof *ro); 632 /* 633 * If the incoming packet was addressed directly to us, 634 * use dst as the src for the reply. Otherwise (broadcast 635 * or anonymous), use the address which corresponds 636 * to the incoming interface. 637 */ 638 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 639 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 640 goto match; 641 if (m->m_pkthdr.rcvif != NULL && 642 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 643 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 644 if (ifa->ifa_addr->sa_family != AF_INET) 645 continue; 646 ia = ifatoia(ifa); 647 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 648 t.s_addr) 649 goto match; 650 } 651 } 652 ia = ip_rtaddr(ip->ip_dst, ro); 653 /* We need a route to do anything useful. */ 654 if (ia == NULL) { 655 m_freem(m); 656 icmpstat.icps_noroute++; 657 goto done; 658 } 659 match: 660 t = IA_SIN(ia)->sin_addr; 661 ip->ip_src = t; 662 ip->ip_ttl = ip_defttl; 663 664 if (optlen > 0) { 665 u_char *cp; 666 int opt, cnt; 667 u_int len; 668 669 /* 670 * Retrieve any source routing from the incoming packet; 671 * add on any record-route or timestamp options. 672 */ 673 cp = (u_char *) (ip + 1); 674 if ((opts = ip_srcroute()) == 0 && 675 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) { 676 opts->m_len = sizeof(struct in_addr); 677 mtod(opts, struct in_addr *)->s_addr = 0; 678 } 679 if (opts) { 680 #ifdef ICMPPRINTFS 681 if (icmpprintfs) 682 kprintf("icmp_reflect optlen %d rt %d => ", 683 optlen, opts->m_len); 684 #endif 685 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 686 opt = cp[IPOPT_OPTVAL]; 687 if (opt == IPOPT_EOL) 688 break; 689 if (opt == IPOPT_NOP) 690 len = 1; 691 else { 692 if (cnt < IPOPT_OLEN + sizeof *cp) 693 break; 694 len = cp[IPOPT_OLEN]; 695 if (len < IPOPT_OLEN + sizeof *cp || 696 len > cnt) 697 break; 698 } 699 /* 700 * Should check for overflow, but it 701 * "can't happen". 702 */ 703 if (opt == IPOPT_RR || opt == IPOPT_TS || 704 opt == IPOPT_SECURITY) { 705 bcopy(cp, 706 mtod(opts, caddr_t) + opts->m_len, 707 len); 708 opts->m_len += len; 709 } 710 } 711 /* Terminate & pad, if necessary */ 712 cnt = opts->m_len % 4; 713 if (cnt) { 714 for (; cnt < 4; cnt++) { 715 *(mtod(opts, caddr_t) + opts->m_len) = 716 IPOPT_EOL; 717 opts->m_len++; 718 } 719 } 720 #ifdef ICMPPRINTFS 721 if (icmpprintfs) 722 kprintf("%d\n", opts->m_len); 723 #endif 724 } 725 /* 726 * Now strip out original options by copying rest of first 727 * mbuf's data back, and adjust the IP length. 728 */ 729 ip->ip_len -= optlen; 730 ip->ip_vhl = IP_VHL_BORING; 731 m->m_len -= optlen; 732 if (m->m_flags & M_PKTHDR) 733 m->m_pkthdr.len -= optlen; 734 optlen += sizeof(struct ip); 735 bcopy((caddr_t)ip + optlen, ip + 1, 736 m->m_len - sizeof(struct ip)); 737 } 738 m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED; 739 m->m_flags &= ~(M_BCAST|M_MCAST); 740 icmp_send(m, opts, ro); 741 done: 742 if (opts) 743 m_free(opts); 744 if (ro && ro->ro_rt) 745 RTFREE(ro->ro_rt); 746 } 747 748 /* 749 * Send an icmp packet back to the ip level, 750 * after supplying a checksum. 751 */ 752 static void 753 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt) 754 { 755 struct ip *ip = mtod(m, struct ip *); 756 int hlen; 757 struct icmp *icp; 758 759 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 760 m->m_data += hlen; 761 m->m_len -= hlen; 762 icp = mtod(m, struct icmp *); 763 icp->icmp_cksum = 0; 764 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 765 m->m_data -= hlen; 766 m->m_len += hlen; 767 m->m_pkthdr.rcvif = (struct ifnet *)0; 768 #ifdef ICMPPRINTFS 769 if (icmpprintfs) { 770 char buf[sizeof "aaa.bbb.ccc.ddd"]; 771 772 strcpy(buf, inet_ntoa(ip->ip_dst)); 773 kprintf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src)); 774 } 775 #endif 776 ip_output(m, opts, rt, 0, NULL, NULL); 777 } 778 779 n_time 780 iptime(void) 781 { 782 struct timeval atv; 783 u_long t; 784 785 getmicrotime(&atv); 786 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 787 return (htonl(t)); 788 } 789 790 #if 1 791 /* 792 * Return the next larger or smaller MTU plateau (table from RFC 1191) 793 * given current value MTU. If DIR is less than zero, a larger plateau 794 * is returned; otherwise, a smaller value is returned. 795 */ 796 int 797 ip_next_mtu(int mtu, int dir) 798 { 799 static int mtutab[] = { 800 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 801 68, 0 802 }; 803 int i; 804 805 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 806 if (mtu >= mtutab[i]) 807 break; 808 } 809 810 if (dir < 0) { 811 if (i == 0) { 812 return 0; 813 } else { 814 return mtutab[i - 1]; 815 } 816 } else { 817 if (mtutab[i] == 0) { 818 return 0; 819 } else if(mtu > mtutab[i]) { 820 return mtutab[i]; 821 } else { 822 return mtutab[i + 1]; 823 } 824 } 825 } 826 #endif 827 828 #ifdef ICMP_BANDLIM 829 /* 830 * badport_bandlim() - check for ICMP bandwidth limit 831 * 832 * Return 0 if it is ok to send an ICMP error response, -1 if we have 833 * hit our bandwidth limit and it is not ok. 834 * 835 * If icmplim is <= 0, the feature is disabled and 0 is returned. 836 * 837 * For now we separate the TCP and UDP subsystems w/ different 'which' 838 * values. We may eventually remove this separation (and simplify the 839 * code further). 840 * 841 * Note that the printing of the error message is delayed so we can 842 * properly print the icmp error rate that the system was trying to do 843 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 844 * the 'final' error, but it doesn't make sense to solve the printing 845 * delay with more complex code. 846 */ 847 int 848 badport_bandlim(int which) 849 { 850 static int lticks[BANDLIM_MAX + 1]; 851 static int lpackets[BANDLIM_MAX + 1]; 852 int dticks; 853 const char *bandlimittype[] = { 854 "Limiting icmp unreach response", 855 "Limiting icmp ping response", 856 "Limiting icmp tstamp response", 857 "Limiting closed port RST response", 858 "Limiting open port RST response" 859 }; 860 861 /* 862 * Return ok status if feature disabled or argument out of 863 * ranage. 864 */ 865 866 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0) 867 return(0); 868 dticks = ticks - lticks[which]; 869 870 /* 871 * reset stats when cumulative dt exceeds one second. 872 */ 873 874 if ((unsigned int)dticks > hz) { 875 if (lpackets[which] > icmplim && icmplim_output) { 876 kprintf("%s from %d to %d packets per second\n", 877 bandlimittype[which], 878 lpackets[which], 879 icmplim 880 ); 881 } 882 lticks[which] = ticks; 883 lpackets[which] = 0; 884 } 885 886 /* 887 * bump packet count 888 */ 889 890 if (++lpackets[which] > icmplim) { 891 return(-1); 892 } 893 return(0); 894 } 895 #endif 896