ip_icmp.c revision 1.14
1 /* $NetBSD: ip_icmp.c,v 1.14 1995/06/01 21:36:22 mycroft Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 36 */ 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/malloc.h> 41 #include <sys/mbuf.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/time.h> 45 #include <sys/kernel.h> 46 47 #include <net/if.h> 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_systm.h> 52 #include <netinet/in_var.h> 53 #include <netinet/ip.h> 54 #include <netinet/ip_icmp.h> 55 #include <netinet/icmp_var.h> 56 57 /* 58 * ICMP routines: error generation, receive packet processing, and 59 * routines to turnaround packets back to the originator, and 60 * host table maintenance routines. 61 */ 62 63 int icmpmaskrepl = 0; 64 #ifdef ICMPPRINTFS 65 int icmpprintfs = 0; 66 #endif 67 68 extern struct protosw inetsw[]; 69 70 /* 71 * Generate an error packet of type error 72 * in response to bad packet ip. 73 */ 74 void 75 icmp_error(n, type, code, dest, destifp) 76 struct mbuf *n; 77 int type, code; 78 n_long dest; 79 struct ifnet *destifp; 80 { 81 register struct ip *oip = mtod(n, struct ip *), *nip; 82 register unsigned oiplen = oip->ip_hl << 2; 83 register struct icmp *icp; 84 register struct mbuf *m; 85 unsigned icmplen; 86 87 #ifdef ICMPPRINTFS 88 if (icmpprintfs) 89 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 90 #endif 91 if (type != ICMP_REDIRECT) 92 icmpstat.icps_error++; 93 /* 94 * Don't send error if not the first fragment of message. 95 * Don't error if the old packet protocol was ICMP 96 * error message, only known informational types. 97 */ 98 if (oip->ip_off &~ (IP_MF|IP_DF)) 99 goto freeit; 100 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 101 n->m_len >= oiplen + ICMP_MINLEN && 102 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 103 icmpstat.icps_oldicmp++; 104 goto freeit; 105 } 106 /* Don't send error in response to a multicast or broadcast packet */ 107 if (n->m_flags & (M_BCAST|M_MCAST)) 108 goto freeit; 109 /* 110 * First, formulate icmp message 111 */ 112 m = m_gethdr(M_DONTWAIT, MT_HEADER); 113 if (m == NULL) 114 goto freeit; 115 icmplen = oiplen + min(8, oip->ip_len); 116 m->m_len = icmplen + ICMP_MINLEN; 117 MH_ALIGN(m, m->m_len); 118 icp = mtod(m, struct icmp *); 119 if ((u_int)type > ICMP_MAXTYPE) 120 panic("icmp_error"); 121 icmpstat.icps_outhist[type]++; 122 icp->icmp_type = type; 123 if (type == ICMP_REDIRECT) 124 icp->icmp_gwaddr.s_addr = dest; 125 else { 126 icp->icmp_void = 0; 127 /* 128 * The following assignments assume an overlay with the 129 * zeroed icmp_void field. 130 */ 131 if (type == ICMP_PARAMPROB) { 132 icp->icmp_pptr = code; 133 code = 0; 134 } else if (type == ICMP_UNREACH && 135 code == ICMP_UNREACH_NEEDFRAG && destifp) 136 icp->icmp_nextmtu = htons(destifp->if_mtu); 137 } 138 139 icp->icmp_code = code; 140 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 141 nip = &icp->icmp_ip; 142 nip->ip_len = htons((u_int16_t)(nip->ip_len + oiplen)); 143 144 /* 145 * Now, copy old ip header (without options) 146 * in front of icmp message. 147 */ 148 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 149 panic("icmp len"); 150 m->m_data -= sizeof(struct ip); 151 m->m_len += sizeof(struct ip); 152 m->m_pkthdr.len = m->m_len; 153 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 154 nip = mtod(m, struct ip *); 155 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 156 nip->ip_len = m->m_len; 157 nip->ip_hl = sizeof(struct ip) >> 2; 158 nip->ip_p = IPPROTO_ICMP; 159 nip->ip_tos = 0; 160 icmp_reflect(m); 161 162 freeit: 163 m_freem(n); 164 } 165 166 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 167 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 168 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 169 struct sockaddr_in icmpmask = { 8, 0 }; 170 171 /* 172 * Process a received ICMP message. 173 */ 174 void 175 icmp_input(m, hlen) 176 register struct mbuf *m; 177 int hlen; 178 { 179 register struct icmp *icp; 180 register struct ip *ip = mtod(m, struct ip *); 181 int icmplen = ip->ip_len; 182 register int i; 183 struct in_ifaddr *ia; 184 void (*ctlfunc) __P((int, struct sockaddr *, struct ip *)); 185 int code; 186 extern u_char ip_protox[]; 187 188 /* 189 * Locate icmp structure in mbuf, and check 190 * that not corrupted and of at least minimum length. 191 */ 192 #ifdef ICMPPRINTFS 193 if (icmpprintfs) 194 printf("icmp_input from %x to %x, len %d\n", 195 ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), 196 icmplen); 197 #endif 198 if (icmplen < ICMP_MINLEN) { 199 icmpstat.icps_tooshort++; 200 goto freeit; 201 } 202 i = hlen + min(icmplen, ICMP_ADVLENMIN); 203 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 204 icmpstat.icps_tooshort++; 205 return; 206 } 207 ip = mtod(m, struct ip *); 208 m->m_len -= hlen; 209 m->m_data += hlen; 210 icp = mtod(m, struct icmp *); 211 if (in_cksum(m, icmplen)) { 212 icmpstat.icps_checksum++; 213 goto freeit; 214 } 215 m->m_len += hlen; 216 m->m_data -= hlen; 217 218 #ifdef ICMPPRINTFS 219 /* 220 * Message type specific processing. 221 */ 222 if (icmpprintfs) 223 printf("icmp_input, type %d code %d\n", icp->icmp_type, 224 icp->icmp_code); 225 #endif 226 if (icp->icmp_type > ICMP_MAXTYPE) 227 goto raw; 228 icmpstat.icps_inhist[icp->icmp_type]++; 229 code = icp->icmp_code; 230 switch (icp->icmp_type) { 231 232 case ICMP_UNREACH: 233 switch (code) { 234 case ICMP_UNREACH_NET: 235 case ICMP_UNREACH_HOST: 236 case ICMP_UNREACH_PROTOCOL: 237 case ICMP_UNREACH_PORT: 238 case ICMP_UNREACH_SRCFAIL: 239 code += PRC_UNREACH_NET; 240 break; 241 242 case ICMP_UNREACH_NEEDFRAG: 243 code = PRC_MSGSIZE; 244 break; 245 246 case ICMP_UNREACH_NET_UNKNOWN: 247 case ICMP_UNREACH_NET_PROHIB: 248 case ICMP_UNREACH_TOSNET: 249 code = PRC_UNREACH_NET; 250 break; 251 252 case ICMP_UNREACH_HOST_UNKNOWN: 253 case ICMP_UNREACH_ISOLATED: 254 case ICMP_UNREACH_HOST_PROHIB: 255 case ICMP_UNREACH_TOSHOST: 256 code = PRC_UNREACH_HOST; 257 break; 258 259 default: 260 goto badcode; 261 } 262 goto deliver; 263 264 case ICMP_TIMXCEED: 265 if (code > 1) 266 goto badcode; 267 code += PRC_TIMXCEED_INTRANS; 268 goto deliver; 269 270 case ICMP_PARAMPROB: 271 if (code > 1) 272 goto badcode; 273 code = PRC_PARAMPROB; 274 goto deliver; 275 276 case ICMP_SOURCEQUENCH: 277 if (code) 278 goto badcode; 279 code = PRC_QUENCH; 280 deliver: 281 /* 282 * Problem with datagram; advise higher level routines. 283 */ 284 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 285 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 286 icmpstat.icps_badlen++; 287 goto freeit; 288 } 289 if (IN_MULTICAST(icp->icmp_ip.ip_dst.s_addr)) 290 goto badcode; 291 NTOHS(icp->icmp_ip.ip_len); 292 #ifdef ICMPPRINTFS 293 if (icmpprintfs) 294 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 295 #endif 296 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 297 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 298 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 299 &icp->icmp_ip); 300 break; 301 302 badcode: 303 icmpstat.icps_badcode++; 304 break; 305 306 case ICMP_ECHO: 307 icp->icmp_type = ICMP_ECHOREPLY; 308 goto reflect; 309 310 case ICMP_TSTAMP: 311 if (icmplen < ICMP_TSLEN) { 312 icmpstat.icps_badlen++; 313 break; 314 } 315 icp->icmp_type = ICMP_TSTAMPREPLY; 316 icp->icmp_rtime = iptime(); 317 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 318 goto reflect; 319 320 case ICMP_MASKREQ: 321 #define satosin(sa) ((struct sockaddr_in *)(sa)) 322 if (icmpmaskrepl == 0) 323 break; 324 /* 325 * We are not able to respond with all ones broadcast 326 * unless we receive it over a point-to-point interface. 327 */ 328 if (icmplen < ICMP_MASKLEN) 329 break; 330 switch (ip->ip_dst.s_addr) { 331 332 case INADDR_BROADCAST: 333 case INADDR_ANY: 334 icmpdst.sin_addr = ip->ip_src; 335 break; 336 337 default: 338 icmpdst.sin_addr = ip->ip_dst; 339 } 340 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 341 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 342 if (ia == 0) 343 break; 344 icp->icmp_type = ICMP_MASKREPLY; 345 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 346 if (ip->ip_src.s_addr == 0) { 347 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 348 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 349 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 350 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 351 } 352 reflect: 353 ip->ip_len += hlen; /* since ip_input deducts this */ 354 icmpstat.icps_reflect++; 355 icmpstat.icps_outhist[icp->icmp_type]++; 356 icmp_reflect(m); 357 return; 358 359 case ICMP_REDIRECT: 360 if (code > 3) 361 goto badcode; 362 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 363 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 364 icmpstat.icps_badlen++; 365 break; 366 } 367 /* 368 * Short circuit routing redirects to force 369 * immediate change in the kernel's routing 370 * tables. The message is also handed to anyone 371 * listening on a raw socket (e.g. the routing 372 * daemon for use in updating its tables). 373 */ 374 icmpgw.sin_addr = ip->ip_src; 375 icmpdst.sin_addr = icp->icmp_gwaddr; 376 #ifdef ICMPPRINTFS 377 if (icmpprintfs) 378 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 379 icp->icmp_gwaddr); 380 #endif 381 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 382 rtredirect((struct sockaddr *)&icmpsrc, 383 (struct sockaddr *)&icmpdst, 384 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 385 (struct sockaddr *)&icmpgw, (struct rtentry **)0); 386 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 387 break; 388 389 /* 390 * No kernel processing for the following; 391 * just fall through to send to raw listener. 392 */ 393 case ICMP_ECHOREPLY: 394 case ICMP_ROUTERADVERT: 395 case ICMP_ROUTERSOLICIT: 396 case ICMP_TSTAMPREPLY: 397 case ICMP_IREQREPLY: 398 case ICMP_MASKREPLY: 399 default: 400 break; 401 } 402 403 raw: 404 rip_input(m); 405 return; 406 407 freeit: 408 m_freem(m); 409 } 410 411 /* 412 * Reflect the ip packet back to the source 413 */ 414 void 415 icmp_reflect(m) 416 struct mbuf *m; 417 { 418 register struct ip *ip = mtod(m, struct ip *); 419 register struct in_ifaddr *ia; 420 struct in_addr t; 421 struct mbuf *opts = 0, *ip_srcroute(); 422 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 423 424 if (!in_canforward(ip->ip_src) && 425 ((ip->ip_src.s_addr & IN_CLASSA_NET) != 426 htonl(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 427 m_freem(m); /* Bad return address */ 428 goto done; /* ip_output() will check for broadcast */ 429 } 430 t = ip->ip_dst; 431 ip->ip_dst = ip->ip_src; 432 /* 433 * If the incoming packet was addressed directly to us, 434 * use dst as the src for the reply. Otherwise (broadcast 435 * or anonymous), use the address which corresponds 436 * to the incoming interface. 437 */ 438 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 439 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 440 break; 441 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 442 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 443 break; 444 } 445 icmpdst.sin_addr = t; 446 if (ia == (struct in_ifaddr *)0) 447 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 448 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 449 /* 450 * The following happens if the packet was not addressed to us, 451 * and was received on an interface with no IP address. 452 */ 453 if (ia == (struct in_ifaddr *)0) 454 ia = in_ifaddr; 455 t = IA_SIN(ia)->sin_addr; 456 ip->ip_src = t; 457 ip->ip_ttl = MAXTTL; 458 459 if (optlen > 0) { 460 register u_char *cp; 461 int opt, cnt; 462 u_int len; 463 464 /* 465 * Retrieve any source routing from the incoming packet; 466 * add on any record-route or timestamp options. 467 */ 468 cp = (u_char *) (ip + 1); 469 if ((opts = ip_srcroute()) == 0 && 470 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 471 opts->m_len = sizeof(struct in_addr); 472 mtod(opts, struct in_addr *)->s_addr = 0; 473 } 474 if (opts) { 475 #ifdef ICMPPRINTFS 476 if (icmpprintfs) 477 printf("icmp_reflect optlen %d rt %d => ", 478 optlen, opts->m_len); 479 #endif 480 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 481 opt = cp[IPOPT_OPTVAL]; 482 if (opt == IPOPT_EOL) 483 break; 484 if (opt == IPOPT_NOP) 485 len = 1; 486 else { 487 len = cp[IPOPT_OLEN]; 488 if (len <= 0 || len > cnt) 489 break; 490 } 491 /* 492 * Should check for overflow, but it "can't happen" 493 */ 494 if (opt == IPOPT_RR || opt == IPOPT_TS || 495 opt == IPOPT_SECURITY) { 496 bcopy((caddr_t)cp, 497 mtod(opts, caddr_t) + opts->m_len, len); 498 opts->m_len += len; 499 } 500 } 501 /* Terminate & pad, if necessary */ 502 if (cnt = opts->m_len % 4) { 503 for (; cnt < 4; cnt++) { 504 *(mtod(opts, caddr_t) + opts->m_len) = 505 IPOPT_EOL; 506 opts->m_len++; 507 } 508 } 509 #ifdef ICMPPRINTFS 510 if (icmpprintfs) 511 printf("%d\n", opts->m_len); 512 #endif 513 } 514 /* 515 * Now strip out original options by copying rest of first 516 * mbuf's data back, and adjust the IP length. 517 */ 518 ip->ip_len -= optlen; 519 ip->ip_hl = sizeof(struct ip) >> 2; 520 m->m_len -= optlen; 521 if (m->m_flags & M_PKTHDR) 522 m->m_pkthdr.len -= optlen; 523 optlen += sizeof(struct ip); 524 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 525 (unsigned)(m->m_len - sizeof(struct ip))); 526 } 527 m->m_flags &= ~(M_BCAST|M_MCAST); 528 icmp_send(m, opts); 529 done: 530 if (opts) 531 (void)m_free(opts); 532 } 533 534 /* 535 * Send an icmp packet back to the ip level, 536 * after supplying a checksum. 537 */ 538 void 539 icmp_send(m, opts) 540 register struct mbuf *m; 541 struct mbuf *opts; 542 { 543 register struct ip *ip = mtod(m, struct ip *); 544 register int hlen; 545 register struct icmp *icp; 546 547 hlen = ip->ip_hl << 2; 548 m->m_data += hlen; 549 m->m_len -= hlen; 550 icp = mtod(m, struct icmp *); 551 icp->icmp_cksum = 0; 552 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 553 m->m_data -= hlen; 554 m->m_len += hlen; 555 #ifdef ICMPPRINTFS 556 if (icmpprintfs) 557 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 558 #endif 559 (void) ip_output(m, opts, NULL, 0, NULL); 560 } 561 562 n_time 563 iptime() 564 { 565 struct timeval atv; 566 u_long t; 567 568 microtime(&atv); 569 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 570 return (htonl(t)); 571 } 572 573 int 574 icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 575 int *name; 576 u_int namelen; 577 void *oldp; 578 size_t *oldlenp; 579 void *newp; 580 size_t newlen; 581 { 582 583 /* All sysctl names at this level are terminal. */ 584 if (namelen != 1) 585 return (ENOTDIR); 586 587 switch (name[0]) { 588 case ICMPCTL_MASKREPL: 589 return (sysctl_int(oldp, oldlenp, newp, newlen, &icmpmaskrepl)); 590 default: 591 return (ENOPROTOOPT); 592 } 593 /* NOTREACHED */ 594 } 595
Indexes created Tue Sep 23 07:09:52 GMT 2025