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 1.32 2008/10/27 02:56:30 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/socketops.h> 46 #include <sys/time.h> 47 #include <sys/kernel.h> 48 #include <sys/sysctl.h> 49 #include <sys/in_cksum.h> 50 51 #include <machine/stdarg.h> 52 53 #include <net/if.h> 54 #include <net/if_types.h> 55 #include <net/route.h> 56 57 #define _IP_VHL 58 #include <netinet/in.h> 59 #include <netinet/in_systm.h> 60 #include <netinet/in_var.h> 61 #include <netinet/ip.h> 62 #include <netinet/ip_icmp.h> 63 #include <netinet/ip_var.h> 64 #include <netinet/icmp_var.h> 65 66 #ifdef IPSEC 67 #include <netinet6/ipsec.h> 68 #include <netproto/key/key.h> 69 #endif 70 71 #ifdef FAST_IPSEC 72 #include <netproto/ipsec/ipsec.h> 73 #include <netproto/ipsec/key.h> 74 #define IPSEC 75 #endif 76 77 /* 78 * ICMP routines: error generation, receive packet processing, and 79 * routines to turnaround packets back to the originator, and 80 * host table maintenance routines. 81 */ 82 83 struct icmpstat icmpstat; 84 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 85 &icmpstat, icmpstat, ""); 86 87 static int icmpmaskrepl = 0; 88 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 89 &icmpmaskrepl, 0, ""); 90 91 static int drop_redirect = 0; 92 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 93 &drop_redirect, 0, ""); 94 95 static int log_redirect = 0; 96 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 97 &log_redirect, 0, ""); 98 99 #ifdef ICMP_BANDLIM 100 101 /* 102 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl 103 * variable content is -1 and read-only. 104 */ 105 106 static int icmplim = 200; 107 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 108 &icmplim, 0, ""); 109 #else 110 111 static int icmplim = -1; 112 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD, 113 &icmplim, 0, ""); 114 115 #endif 116 117 static int icmplim_output = 1; 118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 119 &icmplim_output, 0, ""); 120 121 /* 122 * ICMP broadcast echo sysctl 123 */ 124 125 static int icmpbmcastecho = 0; 126 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 127 &icmpbmcastecho, 0, ""); 128 129 static char icmp_reply_src[IFNAMSIZ]; 130 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 131 icmp_reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 132 133 static int icmp_rfi; 134 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 135 &icmp_rfi, 0, "ICMP reply from incoming interface for " 136 "non-local packets"); 137 138 #ifdef ICMPPRINTFS 139 int icmpprintfs = 0; 140 #endif 141 142 static void icmp_reflect (struct mbuf *); 143 static void icmp_send (struct mbuf *, struct mbuf *, struct route *); 144 145 extern struct protosw inetsw[]; 146 147 /* 148 * Generate an error packet of type error 149 * in response to bad packet ip. 150 */ 151 void 152 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu) 153 { 154 struct ip *oip = mtod(n, struct ip *), *nip; 155 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2; 156 struct icmp *icp; 157 struct mbuf *m; 158 unsigned icmplen; 159 160 #ifdef ICMPPRINTFS 161 if (icmpprintfs) 162 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code); 163 #endif 164 if (type != ICMP_REDIRECT) 165 icmpstat.icps_error++; 166 /* 167 * Don't send error if the original packet was encrypted. 168 * Don't send error if not the first fragment of message. 169 * Don't error if the old packet protocol was ICMP 170 * error message, only known informational types. 171 */ 172 if (n->m_flags & M_DECRYPTED) 173 goto freeit; 174 if (oip->ip_off &~ (IP_MF|IP_DF)) 175 goto freeit; 176 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 177 n->m_len >= oiplen + ICMP_MINLEN && 178 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 179 icmpstat.icps_oldicmp++; 180 goto freeit; 181 } 182 /* Don't send error in response to a multicast or broadcast packet */ 183 if (n->m_flags & (M_BCAST|M_MCAST)) 184 goto freeit; 185 /* 186 * First, formulate icmp message 187 */ 188 m = m_gethdr(MB_DONTWAIT, MT_HEADER); 189 if (m == NULL) 190 goto freeit; 191 icmplen = min(oiplen + 8, oip->ip_len); 192 if (icmplen < sizeof(struct ip)) 193 panic("icmp_error: bad length"); 194 m->m_len = icmplen + ICMP_MINLEN; 195 MH_ALIGN(m, m->m_len); 196 icp = mtod(m, struct icmp *); 197 if ((u_int)type > ICMP_MAXTYPE) 198 panic("icmp_error"); 199 icmpstat.icps_outhist[type]++; 200 icp->icmp_type = type; 201 if (type == ICMP_REDIRECT) 202 icp->icmp_gwaddr.s_addr = dest; 203 else { 204 icp->icmp_void = 0; 205 /* 206 * The following assignments assume an overlay with the 207 * zeroed icmp_void field. 208 */ 209 if (type == ICMP_PARAMPROB) { 210 icp->icmp_pptr = code; 211 code = 0; 212 } else if (type == ICMP_UNREACH && 213 code == ICMP_UNREACH_NEEDFRAG && destmtu) { 214 icp->icmp_nextmtu = htons(destmtu); 215 } 216 } 217 218 icp->icmp_code = code; 219 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 220 nip = &icp->icmp_ip; 221 222 /* 223 * Convert fields to network representation. 224 */ 225 nip->ip_len = htons(nip->ip_len); 226 nip->ip_off = htons(nip->ip_off); 227 228 /* 229 * Now, copy old ip header (without options) 230 * in front of icmp message. 231 */ 232 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 233 panic("icmp len"); 234 m->m_data -= sizeof(struct ip); 235 m->m_len += sizeof(struct ip); 236 m->m_pkthdr.len = m->m_len; 237 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 238 nip = mtod(m, struct ip *); 239 bcopy(oip, nip, sizeof(struct ip)); 240 nip->ip_len = m->m_len; 241 nip->ip_vhl = IP_VHL_BORING; 242 nip->ip_p = IPPROTO_ICMP; 243 nip->ip_tos = 0; 244 m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED; 245 icmp_reflect(m); 246 247 freeit: 248 m_freem(n); 249 } 250 251 /* 252 * Process a received ICMP message. 253 */ 254 void 255 icmp_input(struct mbuf *m, ...) 256 { 257 struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET }; 258 struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET }; 259 struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET }; 260 struct icmp *icp; 261 struct in_ifaddr *ia; 262 struct ip *ip = mtod(m, struct ip *); 263 int icmplen = ip->ip_len; 264 int i, hlen; 265 int code, off, proto; 266 __va_list ap; 267 268 __va_start(ap, m); 269 off = __va_arg(ap, int); 270 proto = __va_arg(ap, int); 271 __va_end(ap); 272 273 hlen = off; 274 275 /* 276 * Locate icmp structure in mbuf, and check 277 * that not corrupted and of at least minimum length. 278 */ 279 #ifdef ICMPPRINTFS 280 if (icmpprintfs) { 281 char buf[sizeof "aaa.bbb.ccc.ddd"]; 282 283 strcpy(buf, inet_ntoa(ip->ip_src)); 284 kprintf("icmp_input from %s to %s, len %d\n", 285 buf, inet_ntoa(ip->ip_dst), icmplen); 286 } 287 #endif 288 if (icmplen < ICMP_MINLEN) { 289 icmpstat.icps_tooshort++; 290 goto freeit; 291 } 292 i = hlen + min(icmplen, ICMP_ADVLENMIN); 293 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 294 icmpstat.icps_tooshort++; 295 return; 296 } 297 ip = mtod(m, struct ip *); 298 m->m_len -= hlen; 299 m->m_data += hlen; 300 icp = mtod(m, struct icmp *); 301 if (in_cksum(m, icmplen)) { 302 icmpstat.icps_checksum++; 303 goto freeit; 304 } 305 m->m_len += hlen; 306 m->m_data -= hlen; 307 308 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 309 /* 310 * Deliver very specific ICMP type only. 311 */ 312 switch (icp->icmp_type) { 313 case ICMP_UNREACH: 314 case ICMP_TIMXCEED: 315 break; 316 default: 317 goto freeit; 318 } 319 } 320 321 #ifdef ICMPPRINTFS 322 if (icmpprintfs) 323 kprintf("icmp_input, type %d code %d\n", icp->icmp_type, 324 icp->icmp_code); 325 #endif 326 327 /* 328 * Message type specific processing. 329 */ 330 if (icp->icmp_type > ICMP_MAXTYPE) 331 goto raw; 332 icmpstat.icps_inhist[icp->icmp_type]++; 333 code = icp->icmp_code; 334 switch (icp->icmp_type) { 335 336 case ICMP_UNREACH: 337 switch (code) { 338 case ICMP_UNREACH_NET: 339 case ICMP_UNREACH_HOST: 340 case ICMP_UNREACH_SRCFAIL: 341 case ICMP_UNREACH_NET_UNKNOWN: 342 case ICMP_UNREACH_HOST_UNKNOWN: 343 case ICMP_UNREACH_ISOLATED: 344 case ICMP_UNREACH_TOSNET: 345 case ICMP_UNREACH_TOSHOST: 346 case ICMP_UNREACH_HOST_PRECEDENCE: 347 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 348 code = PRC_UNREACH_NET; 349 break; 350 351 case ICMP_UNREACH_NEEDFRAG: 352 code = PRC_MSGSIZE; 353 break; 354 355 /* 356 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 357 * Treat subcodes 2,3 as immediate RST 358 */ 359 case ICMP_UNREACH_PROTOCOL: 360 case ICMP_UNREACH_PORT: 361 code = PRC_UNREACH_PORT; 362 break; 363 364 case ICMP_UNREACH_NET_PROHIB: 365 case ICMP_UNREACH_HOST_PROHIB: 366 case ICMP_UNREACH_FILTER_PROHIB: 367 code = PRC_UNREACH_ADMIN_PROHIB; 368 break; 369 370 default: 371 goto badcode; 372 } 373 goto deliver; 374 375 case ICMP_TIMXCEED: 376 if (code > 1) 377 goto badcode; 378 code += PRC_TIMXCEED_INTRANS; 379 goto deliver; 380 381 case ICMP_PARAMPROB: 382 if (code > 1) 383 goto badcode; 384 code = PRC_PARAMPROB; 385 goto deliver; 386 387 case ICMP_SOURCEQUENCH: 388 if (code) 389 goto badcode; 390 code = PRC_QUENCH; 391 deliver: 392 /* 393 * Problem with datagram; advise higher level routines. 394 */ 395 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 396 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 397 icmpstat.icps_badlen++; 398 goto freeit; 399 } 400 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 401 /* Discard ICMP's in response to multicast packets */ 402 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 403 goto badcode; 404 #ifdef ICMPPRINTFS 405 if (icmpprintfs) 406 kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 407 #endif 408 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 409 #if 1 410 /* 411 * MTU discovery: 412 * If we got a needfrag and there is a host route to the 413 * original destination, and the MTU is not locked, then 414 * set the MTU in the route to the suggested new value 415 * (if given) and then notify as usual. The ULPs will 416 * notice that the MTU has changed and adapt accordingly. 417 * If no new MTU was suggested, then we guess a new one 418 * less than the current value. If the new MTU is 419 * unreasonably small (arbitrarily set at 296), then 420 * we reset the MTU to the interface value and enable the 421 * lock bit, indicating that we are no longer doing MTU 422 * discovery. 423 */ 424 if (code == PRC_MSGSIZE) { 425 struct rtentry *rt; 426 int mtu; 427 428 rt = rtpurelookup((struct sockaddr *)&icmpsrc); 429 if (rt != NULL && (rt->rt_flags & RTF_HOST) && 430 !(rt->rt_rmx.rmx_locks & RTV_MTU)) { 431 mtu = ntohs(icp->icmp_nextmtu); 432 if (!mtu) 433 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu, 434 1); 435 #ifdef DEBUG_MTUDISC 436 kprintf("MTU for %s reduced to %d\n", 437 inet_ntoa(icmpsrc.sin_addr), mtu); 438 #endif 439 if (mtu < 296) { 440 /* rt->rt_rmx.rmx_mtu = 441 rt->rt_ifp->if_mtu; */ 442 rt->rt_rmx.rmx_locks |= RTV_MTU; 443 } else if (rt->rt_rmx.rmx_mtu > mtu) { 444 rt->rt_rmx.rmx_mtu = mtu; 445 } 446 } 447 if (rt != NULL) 448 --rt->rt_refcnt; 449 } 450 #endif 451 /* 452 * XXX if the packet contains [IPv4 AH TCP], we can't make a 453 * notification to TCP layer. 454 */ 455 so_pru_ctlinput( 456 &inetsw[ip_protox[icp->icmp_ip.ip_p]], 457 code, (struct sockaddr *)&icmpsrc, &icp->icmp_ip); 458 break; 459 460 badcode: 461 icmpstat.icps_badcode++; 462 break; 463 464 case ICMP_ECHO: 465 if (!icmpbmcastecho 466 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 467 icmpstat.icps_bmcastecho++; 468 break; 469 } 470 icp->icmp_type = ICMP_ECHOREPLY; 471 #ifdef ICMP_BANDLIM 472 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 473 goto freeit; 474 else 475 #endif 476 goto reflect; 477 478 case ICMP_TSTAMP: 479 if (!icmpbmcastecho 480 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 481 icmpstat.icps_bmcasttstamp++; 482 break; 483 } 484 if (icmplen < ICMP_TSLEN) { 485 icmpstat.icps_badlen++; 486 break; 487 } 488 icp->icmp_type = ICMP_TSTAMPREPLY; 489 icp->icmp_rtime = iptime(); 490 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 491 #ifdef ICMP_BANDLIM 492 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 493 goto freeit; 494 else 495 #endif 496 goto reflect; 497 498 case ICMP_MASKREQ: 499 if (icmpmaskrepl == 0) 500 break; 501 /* 502 * We are not able to respond with all ones broadcast 503 * unless we receive it over a point-to-point interface. 504 */ 505 if (icmplen < ICMP_MASKLEN) 506 break; 507 switch (ip->ip_dst.s_addr) { 508 509 case INADDR_BROADCAST: 510 case INADDR_ANY: 511 icmpdst.sin_addr = ip->ip_src; 512 break; 513 514 default: 515 icmpdst.sin_addr = ip->ip_dst; 516 } 517 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 518 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 519 if (ia == 0) 520 break; 521 if (ia->ia_ifp == 0) 522 break; 523 icp->icmp_type = ICMP_MASKREPLY; 524 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 525 if (ip->ip_src.s_addr == 0) { 526 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 527 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 528 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 529 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 530 } 531 reflect: 532 ip->ip_len += hlen; /* since ip_input deducts this */ 533 icmpstat.icps_reflect++; 534 icmpstat.icps_outhist[icp->icmp_type]++; 535 icmp_reflect(m); 536 return; 537 538 case ICMP_REDIRECT: 539 if (log_redirect) { 540 u_long src, dst, gw; 541 542 src = ntohl(ip->ip_src.s_addr); 543 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 544 gw = ntohl(icp->icmp_gwaddr.s_addr); 545 kprintf("icmp redirect from %d.%d.%d.%d: " 546 "%d.%d.%d.%d => %d.%d.%d.%d\n", 547 (int)(src >> 24), (int)((src >> 16) & 0xff), 548 (int)((src >> 8) & 0xff), (int)(src & 0xff), 549 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 550 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 551 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 552 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 553 } 554 if (drop_redirect) 555 break; 556 if (code > 3) 557 goto badcode; 558 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 559 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 560 icmpstat.icps_badlen++; 561 break; 562 } 563 /* 564 * Short circuit routing redirects to force 565 * immediate change in the kernel's routing 566 * tables. The message is also handed to anyone 567 * listening on a raw socket (e.g. the routing 568 * daemon for use in updating its tables). 569 */ 570 icmpgw.sin_addr = ip->ip_src; 571 icmpdst.sin_addr = icp->icmp_gwaddr; 572 #ifdef ICMPPRINTFS 573 if (icmpprintfs) { 574 char buf[sizeof "aaa.bbb.ccc.ddd"]; 575 576 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 577 kprintf("redirect dst %s to %s\n", 578 buf, inet_ntoa(icp->icmp_gwaddr)); 579 } 580 #endif 581 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 582 rtredirect((struct sockaddr *)&icmpsrc, 583 (struct sockaddr *)&icmpdst, 584 NULL, RTF_GATEWAY | RTF_HOST, 585 (struct sockaddr *)&icmpgw); 586 kpfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 587 #ifdef IPSEC 588 key_sa_routechange((struct sockaddr *)&icmpsrc); 589 #endif 590 break; 591 592 /* 593 * No kernel processing for the following; 594 * just fall through to send to raw listener. 595 */ 596 case ICMP_ECHOREPLY: 597 case ICMP_ROUTERADVERT: 598 case ICMP_ROUTERSOLICIT: 599 case ICMP_TSTAMPREPLY: 600 case ICMP_IREQREPLY: 601 case ICMP_MASKREPLY: 602 default: 603 break; 604 } 605 606 raw: 607 rip_input(m, off, proto); 608 return; 609 610 freeit: 611 m_freem(m); 612 } 613 614 /* 615 * Reflect the ip packet back to the source 616 */ 617 static void 618 icmp_reflect(struct mbuf *m) 619 { 620 struct ip *ip = mtod(m, struct ip *); 621 struct in_ifaddr *ia; 622 struct in_ifaddr_container *iac; 623 struct ifaddr_container *ifac; 624 struct ifnet *ifp; 625 struct in_addr t; 626 struct mbuf *opts = 0; 627 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip); 628 struct route *ro = NULL, rt; 629 630 if (!in_canforward(ip->ip_src) && 631 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 632 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 633 m_freem(m); /* Bad return address */ 634 icmpstat.icps_badaddr++; 635 goto done; /* Ip_output() will check for broadcast */ 636 } 637 t = ip->ip_dst; 638 ip->ip_dst = ip->ip_src; 639 640 ro = &rt; 641 bzero(ro, sizeof *ro); 642 643 /* 644 * If the incoming packet was addressed directly to us, 645 * use dst as the src for the reply. Otherwise (broadcast 646 * or anonymous), use the address which corresponds 647 * to the incoming interface. 648 */ 649 ia = NULL; 650 LIST_FOREACH(iac, INADDR_HASH(t.s_addr), ia_hash) { 651 if (t.s_addr == IA_SIN(iac->ia)->sin_addr.s_addr) { 652 ia = iac->ia; 653 goto match; 654 } 655 } 656 ifp = m->m_pkthdr.rcvif; 657 if (ifp != NULL && (ifp->if_flags & IFF_BROADCAST)) { 658 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 659 struct ifaddr *ifa = ifac->ifa; 660 661 if (ifa->ifa_addr->sa_family != AF_INET) 662 continue; 663 ia = ifatoia(ifa); 664 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 665 t.s_addr) 666 goto match; 667 } 668 } 669 /* 670 * If the packet was transiting through us, use the address of 671 * the interface the packet came through in. If that interface 672 * doesn't have a suitable IP address, the normal selection 673 * criteria apply. 674 */ 675 if (icmp_rfi && ifp != NULL) { 676 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 677 struct ifaddr *ifa = ifac->ifa; 678 679 if (ifa->ifa_addr->sa_family != AF_INET) 680 continue; 681 ia = ifatoia(ifa); 682 goto match; 683 } 684 } 685 /* 686 * If the incoming packet was not addressed directly to us, use 687 * designated interface for icmp replies specified by sysctl 688 * net.inet.icmp.reply_src (default not set). Otherwise continue 689 * with normal source selection. 690 */ 691 if (icmp_reply_src[0] != '\0' && (ifp = ifunit(icmp_reply_src))) { 692 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 693 struct ifaddr *ifa = ifac->ifa; 694 695 if (ifa->ifa_addr->sa_family != AF_INET) 696 continue; 697 ia = ifatoia(ifa); 698 goto match; 699 } 700 } 701 /* 702 * If the packet was transiting through us, use the address of 703 * the interface that is the closest to the packet source. 704 * When we don't have a route back to the packet source, stop here 705 * and drop the packet. 706 */ 707 ia = ip_rtaddr(ip->ip_dst, ro); 708 if (ia == NULL) { 709 m_freem(m); 710 icmpstat.icps_noroute++; 711 goto done; 712 } 713 match: 714 t = IA_SIN(ia)->sin_addr; 715 ip->ip_src = t; 716 ip->ip_ttl = ip_defttl; 717 718 if (optlen > 0) { 719 u_char *cp; 720 int opt, cnt; 721 u_int len; 722 723 /* 724 * Retrieve any source routing from the incoming packet; 725 * add on any record-route or timestamp options. 726 */ 727 cp = (u_char *) (ip + 1); 728 if ((opts = ip_srcroute(m)) == 0 && 729 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) { 730 opts->m_len = sizeof(struct in_addr); 731 mtod(opts, struct in_addr *)->s_addr = 0; 732 } 733 if (opts) { 734 #ifdef ICMPPRINTFS 735 if (icmpprintfs) 736 kprintf("icmp_reflect optlen %d rt %d => ", 737 optlen, opts->m_len); 738 #endif 739 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 740 opt = cp[IPOPT_OPTVAL]; 741 if (opt == IPOPT_EOL) 742 break; 743 if (opt == IPOPT_NOP) 744 len = 1; 745 else { 746 if (cnt < IPOPT_OLEN + sizeof *cp) 747 break; 748 len = cp[IPOPT_OLEN]; 749 if (len < IPOPT_OLEN + sizeof *cp || 750 len > cnt) 751 break; 752 } 753 /* 754 * Should check for overflow, but it 755 * "can't happen". 756 */ 757 if (opt == IPOPT_RR || opt == IPOPT_TS || 758 opt == IPOPT_SECURITY) { 759 bcopy(cp, 760 mtod(opts, caddr_t) + opts->m_len, 761 len); 762 opts->m_len += len; 763 } 764 } 765 /* Terminate & pad, if necessary */ 766 cnt = opts->m_len % 4; 767 if (cnt) { 768 for (; cnt < 4; cnt++) { 769 *(mtod(opts, caddr_t) + opts->m_len) = 770 IPOPT_EOL; 771 opts->m_len++; 772 } 773 } 774 #ifdef ICMPPRINTFS 775 if (icmpprintfs) 776 kprintf("%d\n", opts->m_len); 777 #endif 778 } 779 /* 780 * Now strip out original options by copying rest of first 781 * mbuf's data back, and adjust the IP length. 782 */ 783 ip->ip_len -= optlen; 784 ip->ip_vhl = IP_VHL_BORING; 785 m->m_len -= optlen; 786 if (m->m_flags & M_PKTHDR) 787 m->m_pkthdr.len -= optlen; 788 optlen += sizeof(struct ip); 789 bcopy((caddr_t)ip + optlen, ip + 1, 790 m->m_len - sizeof(struct ip)); 791 } 792 m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED; 793 m->m_flags &= ~(M_BCAST|M_MCAST); 794 icmp_send(m, opts, ro); 795 done: 796 if (opts) 797 m_free(opts); 798 if (ro && ro->ro_rt) 799 RTFREE(ro->ro_rt); 800 } 801 802 /* 803 * Send an icmp packet back to the ip level, 804 * after supplying a checksum. 805 */ 806 static void 807 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt) 808 { 809 struct ip *ip = mtod(m, struct ip *); 810 int hlen; 811 struct icmp *icp; 812 813 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 814 m->m_data += hlen; 815 m->m_len -= hlen; 816 icp = mtod(m, struct icmp *); 817 icp->icmp_cksum = 0; 818 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 819 m->m_data -= hlen; 820 m->m_len += hlen; 821 m->m_pkthdr.rcvif = NULL; 822 #ifdef ICMPPRINTFS 823 if (icmpprintfs) { 824 char buf[sizeof "aaa.bbb.ccc.ddd"]; 825 826 strcpy(buf, inet_ntoa(ip->ip_dst)); 827 kprintf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src)); 828 } 829 #endif 830 ip_output(m, opts, rt, 0, NULL, NULL); 831 } 832 833 n_time 834 iptime(void) 835 { 836 struct timeval atv; 837 u_long t; 838 839 getmicrotime(&atv); 840 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 841 return (htonl(t)); 842 } 843 844 #if 1 845 /* 846 * Return the next larger or smaller MTU plateau (table from RFC 1191) 847 * given current value MTU. If DIR is less than zero, a larger plateau 848 * is returned; otherwise, a smaller value is returned. 849 */ 850 int 851 ip_next_mtu(int mtu, int dir) 852 { 853 static int mtutab[] = { 854 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 855 68, 0 856 }; 857 int i; 858 859 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 860 if (mtu >= mtutab[i]) 861 break; 862 } 863 864 if (dir < 0) { 865 if (i == 0) { 866 return 0; 867 } else { 868 return mtutab[i - 1]; 869 } 870 } else { 871 if (mtutab[i] == 0) { 872 return 0; 873 } else if(mtu > mtutab[i]) { 874 return mtutab[i]; 875 } else { 876 return mtutab[i + 1]; 877 } 878 } 879 } 880 #endif 881 882 #ifdef ICMP_BANDLIM 883 /* 884 * badport_bandlim() - check for ICMP bandwidth limit 885 * 886 * Return 0 if it is ok to send an ICMP error response, -1 if we have 887 * hit our bandwidth limit and it is not ok. 888 * 889 * If icmplim is <= 0, the feature is disabled and 0 is returned. 890 * 891 * For now we separate the TCP and UDP subsystems w/ different 'which' 892 * values. We may eventually remove this separation (and simplify the 893 * code further). 894 * 895 * Note that the printing of the error message is delayed so we can 896 * properly print the icmp error rate that the system was trying to do 897 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 898 * the 'final' error, but it doesn't make sense to solve the printing 899 * delay with more complex code. 900 */ 901 int 902 badport_bandlim(int which) 903 { 904 static int lticks[BANDLIM_MAX + 1]; 905 static int lpackets[BANDLIM_MAX + 1]; 906 int dticks; 907 const char *bandlimittype[] = { 908 "Limiting icmp unreach response", 909 "Limiting icmp ping response", 910 "Limiting icmp tstamp response", 911 "Limiting closed port RST response", 912 "Limiting open port RST response" 913 }; 914 915 /* 916 * Return ok status if feature disabled or argument out of 917 * ranage. 918 */ 919 920 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0) 921 return(0); 922 dticks = ticks - lticks[which]; 923 924 /* 925 * reset stats when cumulative dt exceeds one second. 926 */ 927 928 if ((unsigned int)dticks > hz) { 929 if (lpackets[which] > icmplim && icmplim_output) { 930 kprintf("%s from %d to %d packets per second\n", 931 bandlimittype[which], 932 lpackets[which], 933 icmplim 934 ); 935 } 936 lticks[which] = ticks; 937 lpackets[which] = 0; 938 } 939 940 /* 941 * bump packet count 942 */ 943 944 if (++lpackets[which] > icmplim) { 945 return(-1); 946 } 947 return(0); 948 } 949 #endif 950