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 */ 36 37 #include "opt_ipsec.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/mbuf.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/socketops.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, "ICMP statistics"); 85 86 static int icmpmaskrepl = 0; 87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 88 &icmpmaskrepl, 0, "Allow replies to netmask requests"); 89 90 static int drop_redirect = 0; 91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 92 &drop_redirect, 0, "Ignore ICMP redirects"); 93 94 static int log_redirect = 0; 95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 96 &log_redirect, 0, "Enable output about ICMP redirects"); 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 = 1; 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 int icmpprintfs = 0; 139 #endif 140 141 static void icmp_reflect (struct mbuf *); 142 static void icmp_send (struct mbuf *, struct mbuf *, struct route *); 143 144 extern struct protosw inetsw[]; 145 146 /* 147 * Generate an error packet of type error 148 * in response to bad packet ip. 149 */ 150 void 151 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu) 152 { 153 struct ip *oip = mtod(n, struct ip *), *nip; 154 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2; 155 struct icmp *icp; 156 struct mbuf *m; 157 unsigned icmplen; 158 159 #ifdef ICMPPRINTFS 160 if (icmpprintfs) 161 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code); 162 #endif 163 if (type != ICMP_REDIRECT) 164 icmpstat.icps_error++; 165 /* 166 * Don't send error if the original packet was encrypted. 167 * Don't send error if not the first fragment of message. 168 * Don't error if the old packet protocol was ICMP 169 * error message, only known informational types. 170 */ 171 if (n->m_flags & M_DECRYPTED) 172 goto freeit; 173 if (oip->ip_off &~ (IP_MF|IP_DF)) 174 goto freeit; 175 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 176 n->m_len >= oiplen + ICMP_MINLEN && 177 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 178 icmpstat.icps_oldicmp++; 179 goto freeit; 180 } 181 /* Don't send error in response to a multicast or broadcast packet */ 182 if (n->m_flags & (M_BCAST|M_MCAST)) 183 goto freeit; 184 /* 185 * First, formulate icmp message 186 */ 187 m = m_gethdr(MB_DONTWAIT, MT_HEADER); 188 if (m == NULL) 189 goto freeit; 190 icmplen = min(oiplen + 8, oip->ip_len); 191 if (icmplen < sizeof(struct ip)) 192 panic("icmp_error: bad length"); 193 m->m_len = icmplen + ICMP_MINLEN; 194 MH_ALIGN(m, m->m_len); 195 icp = mtod(m, struct icmp *); 196 if ((u_int)type > ICMP_MAXTYPE) 197 panic("icmp_error"); 198 icmpstat.icps_outhist[type]++; 199 icp->icmp_type = type; 200 if (type == ICMP_REDIRECT) 201 icp->icmp_gwaddr.s_addr = dest; 202 else { 203 icp->icmp_void = 0; 204 /* 205 * The following assignments assume an overlay with the 206 * zeroed icmp_void field. 207 */ 208 if (type == ICMP_PARAMPROB) { 209 icp->icmp_pptr = code; 210 code = 0; 211 } else if (type == ICMP_UNREACH && 212 code == ICMP_UNREACH_NEEDFRAG && destmtu) { 213 icp->icmp_nextmtu = htons(destmtu); 214 } 215 } 216 217 icp->icmp_code = code; 218 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 219 nip = &icp->icmp_ip; 220 221 /* 222 * Convert fields to network representation. 223 */ 224 nip->ip_len = htons(nip->ip_len); 225 nip->ip_off = htons(nip->ip_off); 226 227 /* 228 * Now, copy old ip header (without options) 229 * in front of icmp message. 230 */ 231 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 232 panic("icmp len"); 233 m->m_data -= sizeof(struct ip); 234 m->m_len += sizeof(struct ip); 235 m->m_pkthdr.len = m->m_len; 236 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 237 nip = mtod(m, struct ip *); 238 bcopy(oip, nip, sizeof(struct ip)); 239 nip->ip_len = m->m_len; 240 nip->ip_vhl = IP_VHL_BORING; 241 nip->ip_p = IPPROTO_ICMP; 242 nip->ip_tos = 0; 243 m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED; 244 icmp_reflect(m); 245 246 freeit: 247 m_freem(n); 248 } 249 250 /* 251 * Process a received ICMP message. 252 */ 253 int 254 icmp_input(struct mbuf **mp, int *offp, int proto) 255 { 256 struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET }; 257 struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET }; 258 struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET }; 259 struct icmp *icp; 260 struct in_ifaddr *ia; 261 struct mbuf *m = *mp; 262 struct ip *ip = mtod(m, struct ip *); 263 int icmplen = ip->ip_len; 264 int i, hlen; 265 int code; 266 267 *mp = NULL; 268 hlen = *offp; 269 270 /* 271 * Locate icmp structure in mbuf, and check 272 * that not corrupted and of at least minimum length. 273 */ 274 #ifdef ICMPPRINTFS 275 if (icmpprintfs) { 276 char buf[sizeof "aaa.bbb.ccc.ddd"]; 277 278 strcpy(buf, inet_ntoa(ip->ip_src)); 279 kprintf("icmp_input from %s to %s, len %d\n", 280 buf, inet_ntoa(ip->ip_dst), icmplen); 281 } 282 #endif 283 if (icmplen < ICMP_MINLEN) { 284 icmpstat.icps_tooshort++; 285 goto freeit; 286 } 287 i = hlen + min(icmplen, ICMP_ADVLENMIN); 288 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) { 289 icmpstat.icps_tooshort++; 290 return(IPPROTO_DONE); 291 } 292 ip = mtod(m, struct ip *); 293 m->m_len -= hlen; 294 m->m_data += hlen; 295 icp = mtod(m, struct icmp *); 296 if (in_cksum(m, icmplen)) { 297 icmpstat.icps_checksum++; 298 goto freeit; 299 } 300 m->m_len += hlen; 301 m->m_data -= 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 code = PRC_QUENCH; 386 deliver: 387 /* 388 * Problem with datagram; advise higher level routines. 389 */ 390 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 391 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 392 icmpstat.icps_badlen++; 393 goto freeit; 394 } 395 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); 396 /* Discard ICMP's in response to multicast packets */ 397 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 398 goto badcode; 399 #ifdef ICMPPRINTFS 400 if (icmpprintfs) 401 kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 402 #endif 403 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 404 #if 1 405 /* 406 * MTU discovery: 407 * If we got a needfrag and there is a host route to the 408 * original destination, and the MTU is not locked, then 409 * set the MTU in the route to the suggested new value 410 * (if given) and then notify as usual. The ULPs will 411 * notice that the MTU has changed and adapt accordingly. 412 * If no new MTU was suggested, then we guess a new one 413 * less than the current value. If the new MTU is 414 * unreasonably small (arbitrarily set at 296), then 415 * we reset the MTU to the interface value and enable the 416 * lock bit, indicating that we are no longer doing MTU 417 * discovery. 418 */ 419 if (code == PRC_MSGSIZE) { 420 struct rtentry *rt; 421 int mtu; 422 423 rt = rtpurelookup((struct sockaddr *)&icmpsrc); 424 if (rt != NULL && (rt->rt_flags & RTF_HOST) && 425 !(rt->rt_rmx.rmx_locks & RTV_MTU)) { 426 mtu = ntohs(icp->icmp_nextmtu); 427 if (!mtu) 428 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu, 429 1); 430 #ifdef DEBUG_MTUDISC 431 kprintf("MTU for %s reduced to %d\n", 432 inet_ntoa(icmpsrc.sin_addr), mtu); 433 #endif 434 if (mtu < 296) { 435 /* rt->rt_rmx.rmx_mtu = 436 rt->rt_ifp->if_mtu; */ 437 rt->rt_rmx.rmx_locks |= RTV_MTU; 438 } else if (rt->rt_rmx.rmx_mtu > mtu) { 439 rt->rt_rmx.rmx_mtu = mtu; 440 } 441 } 442 if (rt != NULL) 443 --rt->rt_refcnt; 444 } 445 #endif 446 /* 447 * XXX if the packet contains [IPv4 AH TCP], we can't make a 448 * notification to TCP layer. 449 */ 450 so_pru_ctlinput( 451 &inetsw[ip_protox[icp->icmp_ip.ip_p]], 452 code, (struct sockaddr *)&icmpsrc, &icp->icmp_ip); 453 break; 454 455 badcode: 456 icmpstat.icps_badcode++; 457 break; 458 459 case ICMP_ECHO: 460 if (!icmpbmcastecho 461 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 462 icmpstat.icps_bmcastecho++; 463 break; 464 } 465 icp->icmp_type = ICMP_ECHOREPLY; 466 #ifdef ICMP_BANDLIM 467 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 468 goto freeit; 469 else 470 #endif 471 goto reflect; 472 473 case ICMP_TSTAMP: 474 if (!icmpbmcastecho 475 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 476 icmpstat.icps_bmcasttstamp++; 477 break; 478 } 479 if (icmplen < ICMP_TSLEN) { 480 icmpstat.icps_badlen++; 481 break; 482 } 483 icp->icmp_type = ICMP_TSTAMPREPLY; 484 icp->icmp_rtime = iptime(); 485 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 486 #ifdef ICMP_BANDLIM 487 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 488 goto freeit; 489 else 490 #endif 491 goto reflect; 492 493 case ICMP_MASKREQ: 494 if (icmpmaskrepl == 0) 495 break; 496 /* 497 * We are not able to respond with all ones broadcast 498 * unless we receive it over a point-to-point interface. 499 */ 500 if (icmplen < ICMP_MASKLEN) 501 break; 502 switch (ip->ip_dst.s_addr) { 503 504 case INADDR_BROADCAST: 505 case INADDR_ANY: 506 icmpdst.sin_addr = ip->ip_src; 507 break; 508 509 default: 510 icmpdst.sin_addr = ip->ip_dst; 511 } 512 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 513 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 514 if (ia == NULL) 515 break; 516 if (ia->ia_ifp == 0) 517 break; 518 icp->icmp_type = ICMP_MASKREPLY; 519 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 520 if (ip->ip_src.s_addr == 0) { 521 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 522 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 523 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 524 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 525 } 526 reflect: 527 ip->ip_len += hlen; /* since ip_input deducts this */ 528 icmpstat.icps_reflect++; 529 icmpstat.icps_outhist[icp->icmp_type]++; 530 icmp_reflect(m); 531 return(IPPROTO_DONE); 532 533 case ICMP_REDIRECT: 534 if (log_redirect) { 535 u_long src, dst, gw; 536 537 src = ntohl(ip->ip_src.s_addr); 538 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 539 gw = ntohl(icp->icmp_gwaddr.s_addr); 540 kprintf("icmp redirect from %d.%d.%d.%d: " 541 "%d.%d.%d.%d => %d.%d.%d.%d\n", 542 (int)(src >> 24), (int)((src >> 16) & 0xff), 543 (int)((src >> 8) & 0xff), (int)(src & 0xff), 544 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 545 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 546 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 547 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 548 } 549 if (drop_redirect) 550 break; 551 if (code > 3) 552 goto badcode; 553 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 554 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 555 icmpstat.icps_badlen++; 556 break; 557 } 558 /* 559 * Short circuit routing redirects to force 560 * immediate change in the kernel's routing 561 * tables. The message is also handed to anyone 562 * listening on a raw socket (e.g. the routing 563 * daemon for use in updating its tables). 564 */ 565 icmpgw.sin_addr = ip->ip_src; 566 icmpdst.sin_addr = icp->icmp_gwaddr; 567 #ifdef ICMPPRINTFS 568 if (icmpprintfs) { 569 char buf[sizeof "aaa.bbb.ccc.ddd"]; 570 571 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 572 kprintf("redirect dst %s to %s\n", 573 buf, inet_ntoa(icp->icmp_gwaddr)); 574 } 575 #endif 576 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 577 rtredirect((struct sockaddr *)&icmpsrc, 578 (struct sockaddr *)&icmpdst, 579 NULL, RTF_GATEWAY | RTF_HOST, 580 (struct sockaddr *)&icmpgw); 581 kpfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 582 #ifdef IPSEC 583 key_sa_routechange((struct sockaddr *)&icmpsrc); 584 #endif 585 break; 586 587 /* 588 * No kernel processing for the following; 589 * just fall through to send to raw listener. 590 */ 591 case ICMP_ECHOREPLY: 592 case ICMP_ROUTERADVERT: 593 case ICMP_ROUTERSOLICIT: 594 case ICMP_TSTAMPREPLY: 595 case ICMP_IREQREPLY: 596 case ICMP_MASKREPLY: 597 default: 598 break; 599 } 600 601 raw: 602 *mp = m; 603 rip_input(mp, offp, proto); 604 return(IPPROTO_DONE); 605 606 freeit: 607 m_freem(m); 608 return(IPPROTO_DONE); 609 } 610 611 /* 612 * Reflect the ip packet back to the source 613 */ 614 static void 615 icmp_reflect(struct mbuf *m) 616 { 617 struct ip *ip = mtod(m, struct ip *); 618 struct in_ifaddr *ia; 619 struct in_ifaddr_container *iac; 620 struct ifaddr_container *ifac; 621 struct ifnet *ifp; 622 struct in_addr t; 623 struct mbuf *opts = NULL; 624 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip); 625 struct route *ro = NULL, rt; 626 627 if (!in_canforward(ip->ip_src) && 628 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 629 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 630 m_freem(m); /* Bad return address */ 631 icmpstat.icps_badaddr++; 632 goto done; /* Ip_output() will check for broadcast */ 633 } 634 t = ip->ip_dst; 635 ip->ip_dst = ip->ip_src; 636 637 ro = &rt; 638 bzero(ro, sizeof *ro); 639 640 /* 641 * If the incoming packet was addressed directly to us, 642 * use dst as the src for the reply. Otherwise (broadcast 643 * or anonymous), use the address which corresponds 644 * to the incoming interface. 645 */ 646 ia = NULL; 647 LIST_FOREACH(iac, INADDR_HASH(t.s_addr), ia_hash) { 648 if (t.s_addr == IA_SIN(iac->ia)->sin_addr.s_addr) { 649 ia = iac->ia; 650 goto match; 651 } 652 } 653 ifp = m->m_pkthdr.rcvif; 654 if (ifp != NULL && (ifp->if_flags & IFF_BROADCAST)) { 655 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 656 struct ifaddr *ifa = ifac->ifa; 657 658 if (ifa->ifa_addr->sa_family != AF_INET) 659 continue; 660 ia = ifatoia(ifa); 661 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 662 t.s_addr) 663 goto match; 664 } 665 } 666 /* 667 * If the packet was transiting through us, use the address of 668 * the interface the packet came through in. If that interface 669 * doesn't have a suitable IP address, the normal selection 670 * criteria apply. 671 */ 672 if (icmp_rfi && ifp != NULL) { 673 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 674 struct ifaddr *ifa = ifac->ifa; 675 676 if (ifa->ifa_addr->sa_family != AF_INET) 677 continue; 678 ia = ifatoia(ifa); 679 goto match; 680 } 681 } 682 /* 683 * If the incoming packet was not addressed directly to us, use 684 * designated interface for icmp replies specified by sysctl 685 * net.inet.icmp.reply_src (default not set). Otherwise continue 686 * with normal source selection. 687 */ 688 if (icmp_reply_src[0] != '\0' && (ifp = ifunit(icmp_reply_src))) { 689 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { 690 struct ifaddr *ifa = ifac->ifa; 691 692 if (ifa->ifa_addr->sa_family != AF_INET) 693 continue; 694 ia = ifatoia(ifa); 695 goto match; 696 } 697 } 698 /* 699 * If the packet was transiting through us, use the address of 700 * the interface that is the closest to the packet source. 701 * When we don't have a route back to the packet source, stop here 702 * and drop the packet. 703 */ 704 ia = ip_rtaddr(ip->ip_dst, ro); 705 if (ia == NULL) { 706 m_freem(m); 707 icmpstat.icps_noroute++; 708 goto done; 709 } 710 match: 711 t = IA_SIN(ia)->sin_addr; 712 ip->ip_src = t; 713 ip->ip_ttl = ip_defttl; 714 715 if (optlen > 0) { 716 u_char *cp; 717 int opt, cnt; 718 u_int len; 719 720 /* 721 * Retrieve any source routing from the incoming packet; 722 * add on any record-route or timestamp options. 723 */ 724 cp = (u_char *) (ip + 1); 725 if ((opts = ip_srcroute(m)) == NULL && 726 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) { 727 opts->m_len = sizeof(struct in_addr); 728 mtod(opts, struct in_addr *)->s_addr = 0; 729 } 730 if (opts) { 731 #ifdef ICMPPRINTFS 732 if (icmpprintfs) 733 kprintf("icmp_reflect optlen %d rt %d => ", 734 optlen, opts->m_len); 735 #endif 736 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 737 opt = cp[IPOPT_OPTVAL]; 738 if (opt == IPOPT_EOL) 739 break; 740 if (opt == IPOPT_NOP) 741 len = 1; 742 else { 743 if (cnt < IPOPT_OLEN + sizeof *cp) 744 break; 745 len = cp[IPOPT_OLEN]; 746 if (len < IPOPT_OLEN + sizeof *cp || 747 len > cnt) 748 break; 749 } 750 /* 751 * Should check for overflow, but it 752 * "can't happen". 753 */ 754 if (opt == IPOPT_RR || opt == IPOPT_TS || 755 opt == IPOPT_SECURITY) { 756 bcopy(cp, 757 mtod(opts, caddr_t) + opts->m_len, 758 len); 759 opts->m_len += len; 760 } 761 } 762 /* Terminate & pad, if necessary */ 763 cnt = opts->m_len % 4; 764 if (cnt) { 765 for (; cnt < 4; cnt++) { 766 *(mtod(opts, caddr_t) + opts->m_len) = 767 IPOPT_EOL; 768 opts->m_len++; 769 } 770 } 771 #ifdef ICMPPRINTFS 772 if (icmpprintfs) 773 kprintf("%d\n", opts->m_len); 774 #endif 775 } 776 /* 777 * Now strip out original options by copying rest of first 778 * mbuf's data back, and adjust the IP length. 779 */ 780 ip->ip_len -= optlen; 781 ip->ip_vhl = IP_VHL_BORING; 782 m->m_len -= optlen; 783 if (m->m_flags & M_PKTHDR) 784 m->m_pkthdr.len -= optlen; 785 optlen += sizeof(struct ip); 786 bcopy((caddr_t)ip + optlen, ip + 1, 787 m->m_len - sizeof(struct ip)); 788 } 789 m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED; 790 m->m_flags &= ~(M_BCAST|M_MCAST); 791 icmp_send(m, opts, ro); 792 done: 793 if (opts) 794 m_free(opts); 795 if (ro && ro->ro_rt) 796 RTFREE(ro->ro_rt); 797 } 798 799 /* 800 * Send an icmp packet back to the ip level, 801 * after supplying a checksum. 802 */ 803 static void 804 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt) 805 { 806 struct ip *ip = mtod(m, struct ip *); 807 struct icmp *icp; 808 int hlen; 809 810 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 811 m->m_data += hlen; 812 m->m_len -= hlen; 813 icp = mtod(m, struct icmp *); 814 icp->icmp_cksum = 0; 815 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 816 m->m_data -= hlen; 817 m->m_len += hlen; 818 m->m_pkthdr.rcvif = NULL; 819 #ifdef ICMPPRINTFS 820 if (icmpprintfs) { 821 char buf[sizeof "aaa.bbb.ccc.ddd"]; 822 823 strcpy(buf, inet_ntoa(ip->ip_dst)); 824 kprintf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src)); 825 } 826 #endif 827 ip_output(m, opts, rt, 0, NULL, NULL); 828 } 829 830 n_time 831 iptime(void) 832 { 833 struct timeval atv; 834 u_long t; 835 836 getmicrotime(&atv); 837 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 838 return (htonl(t)); 839 } 840 841 #if 1 842 /* 843 * Return the next larger or smaller MTU plateau (table from RFC 1191) 844 * given current value MTU. If DIR is less than zero, a larger plateau 845 * is returned; otherwise, a smaller value is returned. 846 */ 847 int 848 ip_next_mtu(int mtu, int dir) 849 { 850 static int mtutab[] = { 851 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 852 68, 0 853 }; 854 int i; 855 856 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 857 if (mtu >= mtutab[i]) 858 break; 859 } 860 861 if (dir < 0) { 862 if (i == 0) { 863 return 0; 864 } else { 865 return mtutab[i - 1]; 866 } 867 } else { 868 if (mtutab[i] == 0) { 869 return 0; 870 } else if(mtu > mtutab[i]) { 871 return mtutab[i]; 872 } else { 873 return mtutab[i + 1]; 874 } 875 } 876 } 877 #endif 878 879 #ifdef ICMP_BANDLIM 880 /* 881 * badport_bandlim() - check for ICMP bandwidth limit 882 * 883 * Return 0 if it is ok to send an ICMP error response, -1 if we have 884 * hit our bandwidth limit and it is not ok. 885 * 886 * If icmplim is <= 0, the feature is disabled and 0 is returned. 887 * 888 * For now we separate the TCP and UDP subsystems w/ different 'which' 889 * values. We may eventually remove this separation (and simplify the 890 * code further). 891 * 892 * Note that the printing of the error message is delayed so we can 893 * properly print the icmp error rate that the system was trying to do 894 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 895 * the 'final' error, but it doesn't make sense to solve the printing 896 * delay with more complex code. 897 */ 898 int 899 badport_bandlim(int which) 900 { 901 static int lticks[BANDLIM_MAX + 1]; 902 static int lpackets[BANDLIM_MAX + 1]; 903 int dticks; 904 const char *bandlimittype[] = { 905 "Limiting icmp unreach response", 906 "Limiting icmp ping response", 907 "Limiting icmp tstamp response", 908 "Limiting closed port RST response", 909 "Limiting open port RST response" 910 }; 911 912 /* 913 * Return ok status if feature disabled or argument out of 914 * ranage. 915 */ 916 917 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0) 918 return(0); 919 dticks = ticks - lticks[which]; 920 921 /* 922 * reset stats when cumulative dt exceeds one second. 923 */ 924 925 if ((unsigned int)dticks > hz) { 926 if (lpackets[which] > icmplim && icmplim_output) { 927 kprintf("%s from %d to %d packets per second\n", 928 bandlimittype[which], 929 lpackets[which], 930 icmplim 931 ); 932 } 933 lticks[which] = ticks; 934 lpackets[which] = 0; 935 } 936 937 /* 938 * bump packet count 939 */ 940 941 if (++lpackets[which] > icmplim) { 942 return(-1); 943 } 944 return(0); 945 } 946 #endif 947