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. 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 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $ 31 */ 32 33 #include "opt_ipsec.h" 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/mbuf.h> 38 #include <sys/protosw.h> 39 #include <sys/socket.h> 40 #include <sys/socketops.h> 41 #include <sys/time.h> 42 #include <sys/kernel.h> 43 #include <sys/sysctl.h> 44 #include <sys/in_cksum.h> 45 46 #include <machine/stdarg.h> 47 48 #include <net/if.h> 49 #include <net/if_types.h> 50 #include <net/route.h> 51 52 #define _IP_VHL 53 #include <netinet/in.h> 54 #include <netinet/in_systm.h> 55 #include <netinet/in_var.h> 56 #include <netinet/ip.h> 57 #include <netinet/ip_icmp.h> 58 #include <netinet/ip_var.h> 59 #include <netinet/icmp_var.h> 60 61 #ifdef IPSEC 62 #include <netinet6/ipsec.h> 63 #include <netproto/key/key.h> 64 #endif 65 66 #ifdef FAST_IPSEC 67 #include <netproto/ipsec/ipsec.h> 68 #include <netproto/ipsec/key.h> 69 #define IPSEC 70 #endif 71 72 /* 73 * ICMP routines: error generation, receive packet processing, and 74 * routines to turnaround packets back to the originator, and 75 * host table maintenance routines. 76 */ 77 78 struct icmpstat icmpstat; 79 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 80 &icmpstat, icmpstat, "ICMP statistics"); 81 82 static int icmpmaskrepl = 0; 83 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 84 &icmpmaskrepl, 0, "Allow replies to netmask requests"); 85 86 static int drop_redirect = 0; 87 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 88 &drop_redirect, 0, "Ignore ICMP redirects"); 89 90 static int log_redirect = 0; 91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 92 &log_redirect, 0, "Enable output about ICMP redirects"); 93 94 static int discard_sourcequench = 1; 95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, discard_sourcequench, CTLFLAG_RW, 96 &discard_sourcequench, 0, "Discard ICMP Source Quench"); 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, "ICMP bandwidth limit"); 108 #else 109 110 static int icmplim = -1; 111 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD, 112 &icmplim, 0, "ICMP bandwidth limit"); 113 114 #endif 115 116 static int icmplim_output = 0; 117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 118 &icmplim_output, 0, "Enable output about ICMP bandwidth limits"); 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 static char icmp_reply_src[IFNAMSIZ]; 129 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, 130 icmp_reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); 131 132 static int icmp_rfi; 133 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, 134 &icmp_rfi, 0, "ICMP reply from incoming interface for " 135 "non-local packets"); 136 137 #ifdef ICMPPRINTFS 138 static int icmpprintfs = 0; 139 SYSCTL_INT(_net_inet_icmp, OID_AUTO, debug_prints, CTLFLAG_RW, 140 &icmpprintfs, 0, "extra ICMP debug prints"); 141 #endif 142 143 static void icmp_reflect (struct mbuf *); 144 static void icmp_send (struct mbuf *, struct mbuf *, struct route *); 145 146 extern struct protosw inetsw[]; 147 148 /* 149 * Generate an error packet of type error 150 * in response to bad packet ip. 151 */ 152 void 153 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu) 154 { 155 struct ip *oip = mtod(n, struct ip *), *nip; 156 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2; 157 struct icmp *icp; 158 struct mbuf *m; 159 unsigned icmplen; 160 161 #ifdef ICMPPRINTFS 162 if (icmpprintfs) 163 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code); 164 #endif 165 if (type != ICMP_REDIRECT) 166 icmpstat.icps_error++; 167 /* 168 * Don't send error if the original packet was encrypted. 169 * Don't send error if not the first fragment of message. 170 * Don't error if the old packet protocol was ICMP 171 * error message, only known informational types. 172 */ 173 if (n->m_flags & M_DECRYPTED) 174 goto freeit; 175 if (oip->ip_off &~ (IP_MF|IP_DF)) 176 goto freeit; 177 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 178 n->m_len >= oiplen + ICMP_MINLEN && 179 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 180 icmpstat.icps_oldicmp++; 181 goto freeit; 182 } 183 /* Don't send error in response to a multicast or broadcast packet */ 184 if (n->m_flags & (M_BCAST|M_MCAST)) 185 goto freeit; 186 /* 187 * First, formulate icmp message 188 */ 189 m = m_gethdr(MB_DONTWAIT, MT_HEADER); 190 if (m == NULL) 191 goto freeit; 192 icmplen = min(oiplen + 8, oip->ip_len); 193 if (icmplen < sizeof(struct ip)) 194 panic("icmp_error: bad length"); 195 m->m_len = icmplen + ICMP_MINLEN; 196 MH_ALIGN(m, m->m_len); 197 icp = mtod(m, struct icmp *); 198 if ((u_int)type > ICMP_MAXTYPE) 199 panic("icmp_error"); 200 icmpstat.icps_outhist[type]++; 201 icp->icmp_type = type; 202 if (type == ICMP_REDIRECT) 203 icp->icmp_gwaddr.s_addr = dest; 204 else { 205 icp->icmp_void = 0; 206 /* 207 * The following assignments assume an overlay with the 208 * zeroed icmp_void field. 209 */ 210 if (type == ICMP_PARAMPROB) { 211 icp->icmp_pptr = code; 212 code = 0; 213 } else if (type == ICMP_UNREACH && 214 code == ICMP_UNREACH_NEEDFRAG && destmtu) { 215 icp->icmp_nextmtu = htons(destmtu); 216 } 217 } 218 219 icp->icmp_code = code; 220 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 221 nip = &icp->icmp_ip; 222 223 /* 224 * Convert fields to network representation. 225 */ 226 nip->ip_len = htons(nip->ip_len); 227 nip->ip_off = htons(nip->ip_off); 228 229 /* 230 * Now, copy old ip header (without options) 231 * in front of icmp message. 232 */ 233 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 234 panic("icmp len"); 235 m->m_data -= sizeof(struct ip); 236 m->m_len += sizeof(struct ip); 237 m->m_pkthdr.len = m->m_len; 238 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 239 nip = mtod(m, struct ip *); 240 bcopy(oip, nip, sizeof(struct ip)); 241 nip->ip_len = m->m_len; 242 nip->ip_vhl = IP_VHL_BORING; 243 nip->ip_p = IPPROTO_ICMP; 244 nip->ip_tos = 0; 245 m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED; 246 icmp_reflect(m); 247 248 freeit: 249 m_freem(n); 250 } 251 252 /* 253 * Process a received ICMP message. 254 */ 255 int 256 icmp_input(struct mbuf **mp, int *offp, int proto) 257 { 258 struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET }; 259 struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET }; 260 struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET }; 261 struct icmp *icp; 262 struct in_ifaddr *ia; 263 struct mbuf *m = *mp; 264 struct ip *ip = mtod(m, struct ip *); 265 int icmplen = ip->ip_len; 266 int i, hlen; 267 int code; 268 269 *mp = NULL; 270 hlen = *offp; 271 272 /* 273 * Locate icmp structure in mbuf, and check 274 * that not corrupted and of at least minimum length. 275 */ 276 #ifdef ICMPPRINTFS 277 if (icmpprintfs) { 278 char src_buf[INET_ADDRSTRLEN], dst_buf[INET_ADDRSTRLEN]; 279 280 kprintf("icmp_input from %s to %s, len %d\n", 281 inet_ntop(AF_INET, &ip->ip_src, src_buf, INET_ADDRSTRLEN), 282 inet_ntop(AF_INET, &ip->ip_dst, dst_buf, INET_ADDRSTRLEN), 283 icmplen); 284 } 285 #endif 286 if (icmplen < ICMP_MINLEN) { 287 icmpstat.icps_tooshort++; 288 goto freeit; 289 } 290 i = hlen + min(icmplen, ICMP_ADVLENMIN); 291 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 292 icmpstat.icps_tooshort++; 293 return(IPPROTO_DONE); 294 } 295 ip = mtod(m, struct ip *); 296 297 if (in_cksum_skip(m, hlen + icmplen, hlen)) { 298 icmpstat.icps_checksum++; 299 goto freeit; 300 } 301 icp = (struct icmp *)((caddr_t)ip + hlen); 302 303 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 304 /* 305 * Deliver very specific ICMP type only. 306 */ 307 switch (icp->icmp_type) { 308 case ICMP_UNREACH: 309 case ICMP_TIMXCEED: 310 break; 311 default: 312 goto freeit; 313 } 314 } 315 316 #ifdef ICMPPRINTFS 317 if (icmpprintfs) 318 kprintf("icmp_input, type %d code %d\n", icp->icmp_type, 319 icp->icmp_code); 320 #endif 321 322 /* 323 * Message type specific processing. 324 */ 325 if (icp->icmp_type > ICMP_MAXTYPE) 326 goto raw; 327 icmpstat.icps_inhist[icp->icmp_type]++; 328 code = icp->icmp_code; 329 switch (icp->icmp_type) { 330 331 case ICMP_UNREACH: 332 switch (code) { 333 case ICMP_UNREACH_NET: 334 case ICMP_UNREACH_HOST: 335 case ICMP_UNREACH_SRCFAIL: 336 case ICMP_UNREACH_NET_UNKNOWN: 337 case ICMP_UNREACH_HOST_UNKNOWN: 338 case ICMP_UNREACH_ISOLATED: 339 case ICMP_UNREACH_TOSNET: 340 case ICMP_UNREACH_TOSHOST: 341 case ICMP_UNREACH_HOST_PRECEDENCE: 342 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 343 code = PRC_UNREACH_NET; 344 break; 345 346 case ICMP_UNREACH_NEEDFRAG: 347 code = PRC_MSGSIZE; 348 break; 349 350 /* 351 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 352 * Treat subcodes 2,3 as immediate RST 353 */ 354 case ICMP_UNREACH_PROTOCOL: 355 case ICMP_UNREACH_PORT: 356 code = PRC_UNREACH_PORT; 357 break; 358 359 case ICMP_UNREACH_NET_PROHIB: 360 case ICMP_UNREACH_HOST_PROHIB: 361 case ICMP_UNREACH_FILTER_PROHIB: 362 code = PRC_UNREACH_ADMIN_PROHIB; 363 break; 364 365 default: 366 goto badcode; 367 } 368 goto deliver; 369 370 case ICMP_TIMXCEED: 371 if (code > 1) 372 goto badcode; 373 code += PRC_TIMXCEED_INTRANS; 374 goto deliver; 375 376 case ICMP_PARAMPROB: 377 if (code > 1) 378 goto badcode; 379 code = PRC_PARAMPROB; 380 goto deliver; 381 382 case ICMP_SOURCEQUENCH: 383 if (code) 384 goto badcode; 385 if (discard_sourcequench) 386 break; 387 code = PRC_QUENCH; 388 deliver: 389 /* 390 * Problem with datagram; advise higher level routines. 391 */ 392 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 393 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 394 icmpstat.icps_badlen++; 395 goto freeit; 396 } 397 /* Discard ICMP's in response to multicast packets */ 398 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 399 goto badcode; 400 #ifdef ICMPPRINTFS 401 if (icmpprintfs) 402 kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 403 #endif 404 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 405 #if 1 406 /* 407 * MTU discovery: 408 * If we got a needfrag and there is a host route to the 409 * original destination, and the MTU is not locked, then 410 * set the MTU in the route to the suggested new value 411 * (if given) and then notify as usual. The ULPs will 412 * notice that the MTU has changed and adapt accordingly. 413 * If no new MTU was suggested, then we guess a new one 414 * less than the current value. If the new MTU is 415 * unreasonably small (arbitrarily set at 296), then 416 * we reset the MTU to the interface value and enable the 417 * lock bit, indicating that we are no longer doing MTU 418 * discovery. 419 */ 420 if (code == PRC_MSGSIZE) { 421 struct rtentry *rt; 422 int mtu; 423 424 rt = rtpurelookup((struct sockaddr *)&icmpsrc); 425 if (rt != NULL && (rt->rt_flags & RTF_HOST) && 426 !(rt->rt_rmx.rmx_locks & RTV_MTU)) { 427 #ifdef DEBUG_MTUDISC 428 char src_buf[INET_ADDRSTRLEN]; 429 #endif 430 mtu = ntohs(icp->icmp_nextmtu); 431 if (!mtu) 432 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu, 433 1); 434 #ifdef DEBUG_MTUDISC 435 kprintf("MTU for %s reduced to %d\n", 436 inet_ntop(AF_INET, &icmpsrc.sin_addr, 437 src_buf, INET_ADDRSTRLEN), 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_pr_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 == NULL) 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(IPPROTO_DONE); 537 538 case ICMP_REDIRECT: 539 if (log_redirect) { 540 char src_buf[INET_ADDRSTRLEN]; 541 char dst_buf[INET_ADDRSTRLEN]; 542 char gwy_buf[INET_ADDRSTRLEN]; 543 544 kprintf("icmp redirect from %s: %s => %s\n", 545 inet_ntop(AF_INET, &ip->ip_src, 546 src_buf, INET_ADDRSTRLEN), 547 inet_ntop(AF_INET, &icp->icmp_ip.ip_dst, 548 dst_buf, INET_ADDRSTRLEN), 549 inet_ntop(AF_INET, &icp->icmp_gwaddr, 550 gwy_buf, INET_ADDRSTRLEN)); 551 } 552 if (drop_redirect) 553 break; 554 if (code > 3) 555 goto badcode; 556 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 557 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 558 icmpstat.icps_badlen++; 559 break; 560 } 561 /* 562 * Short circuit routing redirects to force 563 * immediate change in the kernel's routing 564 * tables. The message is also handed to anyone 565 * listening on a raw socket (e.g. the routing 566 * daemon for use in updating its tables). 567 */ 568 icmpgw.sin_addr = ip->ip_src; 569 icmpdst.sin_addr = icp->icmp_gwaddr; 570 #ifdef ICMPPRINTFS 571 if (icmpprintfs) { 572 char dst_buf[INET_ADDRSTRLEN], gw_buf[INET_ADDRSTRLEN]; 573 574 kprintf("redirect dst %s to %s\n", 575 inet_ntop(AF_INET, &icp->icmp_ip.ip_dst, 576 dst_buf, INET_ADDRSTRLEN), 577 inet_ntop(AF_INET, &icp->icmp_gwaddr, 578 gw_buf, INET_ADDRSTRLEN)); 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 *mp = m; 608 rip_input(mp, offp, proto); 609 return(IPPROTO_DONE); 610 611 freeit: 612 m_freem(m); 613 return(IPPROTO_DONE); 614 } 615 616 /* 617 * Reflect the ip packet back to the source 618 */ 619 static void 620 icmp_reflect(struct mbuf *m) 621 { 622 struct ip *ip = mtod(m, struct ip *); 623 struct in_ifaddr *ia; 624 struct in_ifaddr_container *iac; 625 struct ifaddr_container *ifac; 626 struct ifnet *ifp; 627 struct in_addr t; 628 struct mbuf *opts = NULL; 629 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip); 630 struct route *ro = NULL, rt; 631 632 if (!in_canforward(ip->ip_src) && 633 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 634 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 635 m_freem(m); /* Bad return address */ 636 icmpstat.icps_badaddr++; 637 goto done; /* Ip_output() will check for broadcast */ 638 } 639 t = ip->ip_dst; 640 ip->ip_dst = ip->ip_src; 641 642 ro = &rt; 643 bzero(ro, sizeof *ro); 644 645 /* 646 * If the incoming packet was addressed directly to us, 647 * use dst as the src for the reply. Otherwise (broadcast 648 * or anonymous), use the address which corresponds 649 * to the incoming interface. 650 */ 651 ia = NULL; 652 LIST_FOREACH(iac, INADDR_HASH(t.s_addr), ia_hash) { 653 if (t.s_addr == IA_SIN(iac->ia)->sin_addr.s_addr) { 654 ia = iac->ia; 655 goto match; 656 } 657 } 658 ifp = m->m_pkthdr.rcvif; 659 if (ifp != NULL && (ifp->if_flags & IFF_BROADCAST)) { 660 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 661 struct ifaddr *ifa = ifac->ifa; 662 663 if (ifa->ifa_addr->sa_family != AF_INET) 664 continue; 665 ia = ifatoia(ifa); 666 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 667 t.s_addr) 668 goto match; 669 } 670 } 671 /* 672 * If the packet was transiting through us, use the address of 673 * the interface the packet came through in. If that interface 674 * doesn't have a suitable IP address, the normal selection 675 * criteria apply. 676 */ 677 if (icmp_rfi && ifp != NULL) { 678 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 679 struct ifaddr *ifa = ifac->ifa; 680 681 if (ifa->ifa_addr->sa_family != AF_INET) 682 continue; 683 ia = ifatoia(ifa); 684 goto match; 685 } 686 } 687 /* 688 * If the incoming packet was not addressed directly to us, use 689 * designated interface for icmp replies specified by sysctl 690 * net.inet.icmp.reply_src (default not set). Otherwise continue 691 * with normal source selection. 692 */ 693 if (icmp_reply_src[0] != '\0' && (ifp = ifunit(icmp_reply_src))) { 694 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 695 struct ifaddr *ifa = ifac->ifa; 696 697 if (ifa->ifa_addr->sa_family != AF_INET) 698 continue; 699 ia = ifatoia(ifa); 700 goto match; 701 } 702 } 703 /* 704 * If the packet was transiting through us, use the address of 705 * the interface that is the closest to the packet source. 706 * When we don't have a route back to the packet source, stop here 707 * and drop the packet. 708 */ 709 ia = ip_rtaddr(ip->ip_dst, ro); 710 if (ia == NULL) { 711 m_freem(m); 712 icmpstat.icps_noroute++; 713 goto done; 714 } 715 match: 716 t = IA_SIN(ia)->sin_addr; 717 ip->ip_src = t; 718 ip->ip_ttl = ip_defttl; 719 720 if (optlen > 0) { 721 u_char *cp; 722 int opt, cnt; 723 u_int len; 724 725 /* 726 * Retrieve any source routing from the incoming packet; 727 * add on any record-route or timestamp options. 728 */ 729 cp = (u_char *) (ip + 1); 730 if ((opts = ip_srcroute(m)) == NULL && 731 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) { 732 opts->m_len = sizeof(struct in_addr); 733 mtod(opts, struct in_addr *)->s_addr = 0; 734 } 735 if (opts) { 736 #ifdef ICMPPRINTFS 737 if (icmpprintfs) 738 kprintf("icmp_reflect optlen %d rt %d => ", 739 optlen, opts->m_len); 740 #endif 741 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 742 opt = cp[IPOPT_OPTVAL]; 743 if (opt == IPOPT_EOL) 744 break; 745 if (opt == IPOPT_NOP) 746 len = 1; 747 else { 748 if (cnt < IPOPT_OLEN + sizeof *cp) 749 break; 750 len = cp[IPOPT_OLEN]; 751 if (len < IPOPT_OLEN + sizeof *cp || 752 len > cnt) 753 break; 754 } 755 /* 756 * Should check for overflow, but it 757 * "can't happen". 758 */ 759 if (opt == IPOPT_RR || opt == IPOPT_TS || 760 opt == IPOPT_SECURITY) { 761 bcopy(cp, 762 mtod(opts, caddr_t) + opts->m_len, 763 len); 764 opts->m_len += len; 765 } 766 } 767 /* Terminate & pad, if necessary */ 768 cnt = opts->m_len % 4; 769 if (cnt) { 770 for (; cnt < 4; cnt++) { 771 *(mtod(opts, caddr_t) + opts->m_len) = 772 IPOPT_EOL; 773 opts->m_len++; 774 } 775 } 776 #ifdef ICMPPRINTFS 777 if (icmpprintfs) 778 kprintf("%d\n", opts->m_len); 779 #endif 780 } 781 /* 782 * Now strip out original options by copying rest of first 783 * mbuf's data back, and adjust the IP length. 784 */ 785 ip->ip_len -= optlen; 786 ip->ip_vhl = IP_VHL_BORING; 787 m->m_len -= optlen; 788 if (m->m_flags & M_PKTHDR) 789 m->m_pkthdr.len -= optlen; 790 optlen += sizeof(struct ip); 791 bcopy((caddr_t)ip + optlen, ip + 1, 792 m->m_len - sizeof(struct ip)); 793 } 794 m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED; 795 m->m_flags &= ~(M_BCAST|M_MCAST); 796 icmp_send(m, opts, ro); 797 done: 798 if (opts) 799 m_free(opts); 800 if (ro && ro->ro_rt) 801 RTFREE(ro->ro_rt); 802 } 803 804 /* 805 * Send an icmp packet back to the ip level, 806 * after supplying a checksum. 807 */ 808 static void 809 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt) 810 { 811 struct ip *ip = mtod(m, struct ip *); 812 struct icmp *icp; 813 int hlen; 814 815 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 816 m->m_data += hlen; 817 m->m_len -= hlen; 818 icp = mtod(m, struct icmp *); 819 icp->icmp_cksum = 0; 820 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 821 m->m_data -= hlen; 822 m->m_len += hlen; 823 m->m_pkthdr.rcvif = NULL; 824 #ifdef ICMPPRINTFS 825 if (icmpprintfs) { 826 char dst_buf[INET_ADDRSTRLEN], src_buf[INET_ADDRSTRLEN]; 827 828 kprintf("icmp_send dst %s src %s\n", 829 inet_ntop(AF_INET, &ip->ip_dst, dst_buf, INET_ADDRSTRLEN), 830 inet_ntop(AF_INET, &ip->ip_src, src_buf, INET_ADDRSTRLEN)); 831 } 832 #endif 833 ip_output(m, opts, rt, 0, NULL, NULL); 834 } 835 836 n_time 837 iptime(void) 838 { 839 struct timeval atv; 840 u_long t; 841 842 getmicrotime(&atv); 843 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 844 return (htonl(t)); 845 } 846 847 #if 1 848 /* 849 * Return the next larger or smaller MTU plateau (table from RFC 1191) 850 * given current value MTU. If DIR is less than zero, a larger plateau 851 * is returned; otherwise, a smaller value is returned. 852 */ 853 int 854 ip_next_mtu(int mtu, int dir) 855 { 856 static int mtutab[] = { 857 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 858 68, 0 859 }; 860 int i; 861 862 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 863 if (mtu >= mtutab[i]) 864 break; 865 } 866 867 if (dir < 0) { 868 if (i == 0) { 869 return 0; 870 } else { 871 return mtutab[i - 1]; 872 } 873 } else { 874 if (mtutab[i] == 0) { 875 return 0; 876 } else if(mtu > mtutab[i]) { 877 return mtutab[i]; 878 } else { 879 return mtutab[i + 1]; 880 } 881 } 882 } 883 #endif 884 885 #ifdef ICMP_BANDLIM 886 /* 887 * badport_bandlim() - check for ICMP bandwidth limit 888 * 889 * Return 0 if it is ok to send an ICMP error response, -1 if we have 890 * hit our bandwidth limit and it is not ok. 891 * 892 * If icmplim is <= 0, the feature is disabled and 0 is returned. 893 * 894 * For now we separate the TCP and UDP subsystems w/ different 'which' 895 * values. We may eventually remove this separation (and simplify the 896 * code further). 897 * 898 * Note that the printing of the error message is delayed so we can 899 * properly print the icmp error rate that the system was trying to do 900 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 901 * the 'final' error, but it doesn't make sense to solve the printing 902 * delay with more complex code. 903 */ 904 int 905 badport_bandlim(int which) 906 { 907 static int lticks[BANDLIM_MAX + 1]; 908 static int lpackets[BANDLIM_MAX + 1]; 909 int dticks; 910 const char *bandlimittype[] = { 911 "Limiting icmp unreach response", 912 "Limiting icmp ping response", 913 "Limiting icmp tstamp response", 914 "Limiting closed port RST response", 915 "Limiting open port RST response" 916 }; 917 918 /* 919 * Return ok status if feature disabled or argument out of 920 * ranage. 921 */ 922 923 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0) 924 return(0); 925 dticks = ticks - lticks[which]; 926 927 /* 928 * reset stats when cumulative dt exceeds one second. 929 */ 930 931 if ((unsigned int)dticks > hz) { 932 if (lpackets[which] > icmplim && icmplim_output) { 933 kprintf("%s from %d to %d packets per second\n", 934 bandlimittype[which], 935 lpackets[which], 936 icmplim 937 ); 938 } 939 lticks[which] = ticks; 940 lpackets[which] = 0; 941 } 942 943 /* 944 * bump packet count 945 */ 946 947 if (++lpackets[which] > icmplim) { 948 return(-1); 949 } 950 return(0); 951 } 952 #endif 953