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