1 /* $NetBSD: ip_icmp.c,v 1.11 1995/04/13 06:31:59 cgd 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 } 139 140 icp->icmp_code = code; 141 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 142 nip = &icp->icmp_ip; 143 nip->ip_len = htons((u_int16_t)(nip->ip_len + oiplen)); 144 145 /* 146 * Now, copy old ip header (without options) 147 * in front of icmp message. 148 */ 149 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 150 panic("icmp len"); 151 m->m_data -= sizeof(struct ip); 152 m->m_len += sizeof(struct ip); 153 m->m_pkthdr.len = m->m_len; 154 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 155 nip = mtod(m, struct ip *); 156 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 157 nip->ip_len = m->m_len; 158 nip->ip_hl = sizeof(struct ip) >> 2; 159 nip->ip_p = IPPROTO_ICMP; 160 nip->ip_tos = 0; 161 icmp_reflect(m); 162 163 freeit: 164 m_freem(n); 165 } 166 167 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 168 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 169 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 170 struct sockaddr_in icmpmask = { 8, 0 }; 171 172 /* 173 * Process a received ICMP message. 174 */ 175 void 176 icmp_input(m, hlen) 177 register struct mbuf *m; 178 int hlen; 179 { 180 register struct icmp *icp; 181 register struct ip *ip = mtod(m, struct ip *); 182 int icmplen = ip->ip_len; 183 register int i; 184 struct in_ifaddr *ia; 185 void (*ctlfunc) __P((int, struct sockaddr *, struct ip *)); 186 int code; 187 extern u_char ip_protox[]; 188 189 /* 190 * Locate icmp structure in mbuf, and check 191 * that not corrupted and of at least minimum length. 192 */ 193 #ifdef ICMPPRINTFS 194 if (icmpprintfs) 195 printf("icmp_input from %x to %x, len %d\n", 196 ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), 197 icmplen); 198 #endif 199 if (icmplen < ICMP_MINLEN) { 200 icmpstat.icps_tooshort++; 201 goto freeit; 202 } 203 i = hlen + min(icmplen, ICMP_ADVLENMIN); 204 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 205 icmpstat.icps_tooshort++; 206 return; 207 } 208 ip = mtod(m, struct ip *); 209 m->m_len -= hlen; 210 m->m_data += hlen; 211 icp = mtod(m, struct icmp *); 212 if (in_cksum(m, icmplen)) { 213 icmpstat.icps_checksum++; 214 goto freeit; 215 } 216 m->m_len += hlen; 217 m->m_data -= hlen; 218 219 #ifdef ICMPPRINTFS 220 /* 221 * Message type specific processing. 222 */ 223 if (icmpprintfs) 224 printf("icmp_input, type %d code %d\n", icp->icmp_type, 225 icp->icmp_code); 226 #endif 227 if (icp->icmp_type > ICMP_MAXTYPE) 228 goto raw; 229 icmpstat.icps_inhist[icp->icmp_type]++; 230 code = icp->icmp_code; 231 switch (icp->icmp_type) { 232 233 case ICMP_UNREACH: 234 switch (code) { 235 case ICMP_UNREACH_NET: 236 case ICMP_UNREACH_HOST: 237 case ICMP_UNREACH_PROTOCOL: 238 case ICMP_UNREACH_PORT: 239 case ICMP_UNREACH_SRCFAIL: 240 code += PRC_UNREACH_NET; 241 break; 242 243 case ICMP_UNREACH_NEEDFRAG: 244 code = PRC_MSGSIZE; 245 break; 246 247 case ICMP_UNREACH_NET_UNKNOWN: 248 case ICMP_UNREACH_NET_PROHIB: 249 case ICMP_UNREACH_TOSNET: 250 code = PRC_UNREACH_NET; 251 break; 252 253 case ICMP_UNREACH_HOST_UNKNOWN: 254 case ICMP_UNREACH_ISOLATED: 255 case ICMP_UNREACH_HOST_PROHIB: 256 case ICMP_UNREACH_TOSHOST: 257 code = PRC_UNREACH_HOST; 258 break; 259 260 default: 261 goto badcode; 262 } 263 goto deliver; 264 265 case ICMP_TIMXCEED: 266 if (code > 1) 267 goto badcode; 268 code += PRC_TIMXCEED_INTRANS; 269 goto deliver; 270 271 case ICMP_PARAMPROB: 272 if (code > 1) 273 goto badcode; 274 code = PRC_PARAMPROB; 275 goto deliver; 276 277 case ICMP_SOURCEQUENCH: 278 if (code) 279 goto badcode; 280 code = PRC_QUENCH; 281 deliver: 282 /* 283 * Problem with datagram; advise higher level routines. 284 */ 285 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 286 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 287 icmpstat.icps_badlen++; 288 goto freeit; 289 } 290 NTOHS(icp->icmp_ip.ip_len); 291 #ifdef ICMPPRINTFS 292 if (icmpprintfs) 293 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 294 #endif 295 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 296 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 297 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 298 &icp->icmp_ip); 299 break; 300 301 badcode: 302 icmpstat.icps_badcode++; 303 break; 304 305 case ICMP_ECHO: 306 icp->icmp_type = ICMP_ECHOREPLY; 307 goto reflect; 308 309 case ICMP_TSTAMP: 310 if (icmplen < ICMP_TSLEN) { 311 icmpstat.icps_badlen++; 312 break; 313 } 314 icp->icmp_type = ICMP_TSTAMPREPLY; 315 icp->icmp_rtime = iptime(); 316 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 317 goto reflect; 318 319 case ICMP_MASKREQ: 320 #define satosin(sa) ((struct sockaddr_in *)(sa)) 321 if (icmpmaskrepl == 0) 322 break; 323 /* 324 * We are not able to respond with all ones broadcast 325 * unless we receive it over a point-to-point interface. 326 */ 327 if (icmplen < ICMP_MASKLEN) 328 break; 329 switch (ip->ip_dst.s_addr) { 330 331 case INADDR_BROADCAST: 332 case INADDR_ANY: 333 icmpdst.sin_addr = ip->ip_src; 334 break; 335 336 default: 337 icmpdst.sin_addr = ip->ip_dst; 338 } 339 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 340 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 341 if (ia == 0) 342 break; 343 icp->icmp_type = ICMP_MASKREPLY; 344 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 345 if (ip->ip_src.s_addr == 0) { 346 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 347 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 348 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 349 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 350 } 351 reflect: 352 ip->ip_len += hlen; /* since ip_input deducts this */ 353 icmpstat.icps_reflect++; 354 icmpstat.icps_outhist[icp->icmp_type]++; 355 icmp_reflect(m); 356 return; 357 358 case ICMP_REDIRECT: 359 if (code > 3) 360 goto badcode; 361 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 362 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 363 icmpstat.icps_badlen++; 364 break; 365 } 366 /* 367 * Short circuit routing redirects to force 368 * immediate change in the kernel's routing 369 * tables. The message is also handed to anyone 370 * listening on a raw socket (e.g. the routing 371 * daemon for use in updating its tables). 372 */ 373 icmpgw.sin_addr = ip->ip_src; 374 icmpdst.sin_addr = icp->icmp_gwaddr; 375 #ifdef ICMPPRINTFS 376 if (icmpprintfs) 377 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 378 icp->icmp_gwaddr); 379 #endif 380 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 381 rtredirect((struct sockaddr *)&icmpsrc, 382 (struct sockaddr *)&icmpdst, 383 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 384 (struct sockaddr *)&icmpgw, (struct rtentry **)0); 385 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 386 break; 387 388 /* 389 * No kernel processing for the following; 390 * just fall through to send to raw listener. 391 */ 392 case ICMP_ECHOREPLY: 393 case ICMP_ROUTERADVERT: 394 case ICMP_ROUTERSOLICIT: 395 case ICMP_TSTAMPREPLY: 396 case ICMP_IREQREPLY: 397 case ICMP_MASKREPLY: 398 default: 399 break; 400 } 401 402 raw: 403 rip_input(m); 404 return; 405 406 freeit: 407 m_freem(m); 408 } 409 410 /* 411 * Reflect the ip packet back to the source 412 */ 413 void 414 icmp_reflect(m) 415 struct mbuf *m; 416 { 417 register struct ip *ip = mtod(m, struct ip *); 418 register struct in_ifaddr *ia; 419 struct in_addr t; 420 struct mbuf *opts = 0, *ip_srcroute(); 421 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 422 423 if (!in_canforward(ip->ip_src) && 424 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 425 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 426 m_freem(m); /* Bad return address */ 427 goto done; /* Ip_output() will check for broadcast */ 428 } 429 t = ip->ip_dst; 430 ip->ip_dst = ip->ip_src; 431 /* 432 * If the incoming packet was addressed directly to us, 433 * use dst as the src for the reply. Otherwise (broadcast 434 * or anonymous), use the address which corresponds 435 * to the incoming interface. 436 */ 437 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 438 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 439 break; 440 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 441 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 442 break; 443 } 444 icmpdst.sin_addr = t; 445 if (ia == (struct in_ifaddr *)0) 446 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 447 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 448 /* 449 * The following happens if the packet was not addressed to us, 450 * and was received on an interface with no IP address. 451 */ 452 if (ia == (struct in_ifaddr *)0) 453 ia = in_ifaddr; 454 t = IA_SIN(ia)->sin_addr; 455 ip->ip_src = t; 456 ip->ip_ttl = MAXTTL; 457 458 if (optlen > 0) { 459 register u_char *cp; 460 int opt, cnt; 461 u_int len; 462 463 /* 464 * Retrieve any source routing from the incoming packet; 465 * add on any record-route or timestamp options. 466 */ 467 cp = (u_char *) (ip + 1); 468 if ((opts = ip_srcroute()) == 0 && 469 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 470 opts->m_len = sizeof(struct in_addr); 471 mtod(opts, struct in_addr *)->s_addr = 0; 472 } 473 if (opts) { 474 #ifdef ICMPPRINTFS 475 if (icmpprintfs) 476 printf("icmp_reflect optlen %d rt %d => ", 477 optlen, opts->m_len); 478 #endif 479 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 480 opt = cp[IPOPT_OPTVAL]; 481 if (opt == IPOPT_EOL) 482 break; 483 if (opt == IPOPT_NOP) 484 len = 1; 485 else { 486 len = cp[IPOPT_OLEN]; 487 if (len <= 0 || len > cnt) 488 break; 489 } 490 /* 491 * Should check for overflow, but it "can't happen" 492 */ 493 if (opt == IPOPT_RR || opt == IPOPT_TS || 494 opt == IPOPT_SECURITY) { 495 bcopy((caddr_t)cp, 496 mtod(opts, caddr_t) + opts->m_len, len); 497 opts->m_len += len; 498 } 499 } 500 /* Terminate & pad, if necessary */ 501 if (cnt = opts->m_len % 4) { 502 for (; cnt < 4; cnt++) { 503 *(mtod(opts, caddr_t) + opts->m_len) = 504 IPOPT_EOL; 505 opts->m_len++; 506 } 507 } 508 #ifdef ICMPPRINTFS 509 if (icmpprintfs) 510 printf("%d\n", opts->m_len); 511 #endif 512 } 513 /* 514 * Now strip out original options by copying rest of first 515 * mbuf's data back, and adjust the IP length. 516 */ 517 ip->ip_len -= optlen; 518 ip->ip_hl = sizeof(struct ip) >> 2; 519 m->m_len -= optlen; 520 if (m->m_flags & M_PKTHDR) 521 m->m_pkthdr.len -= optlen; 522 optlen += sizeof(struct ip); 523 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 524 (unsigned)(m->m_len - sizeof(struct ip))); 525 } 526 m->m_flags &= ~(M_BCAST|M_MCAST); 527 icmp_send(m, opts); 528 done: 529 if (opts) 530 (void)m_free(opts); 531 } 532 533 /* 534 * Send an icmp packet back to the ip level, 535 * after supplying a checksum. 536 */ 537 void 538 icmp_send(m, opts) 539 register struct mbuf *m; 540 struct mbuf *opts; 541 { 542 register struct ip *ip = mtod(m, struct ip *); 543 register int hlen; 544 register struct icmp *icp; 545 546 hlen = ip->ip_hl << 2; 547 m->m_data += hlen; 548 m->m_len -= hlen; 549 icp = mtod(m, struct icmp *); 550 icp->icmp_cksum = 0; 551 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 552 m->m_data -= hlen; 553 m->m_len += hlen; 554 #ifdef ICMPPRINTFS 555 if (icmpprintfs) 556 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 557 #endif 558 (void) ip_output(m, opts, NULL, 0, NULL); 559 } 560 561 n_time 562 iptime() 563 { 564 struct timeval atv; 565 u_long t; 566 567 microtime(&atv); 568 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 569 return (htonl(t)); 570 } 571 572 int 573 icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 574 int *name; 575 u_int namelen; 576 void *oldp; 577 size_t *oldlenp; 578 void *newp; 579 size_t newlen; 580 { 581 582 /* All sysctl names at this level are terminal. */ 583 if (namelen != 1) 584 return (ENOTDIR); 585 586 switch (name[0]) { 587 case ICMPCTL_MASKREPL: 588 return (sysctl_int(oldp, oldlenp, newp, newlen, &icmpmaskrepl)); 589 default: 590 return (ENOPROTOOPT); 591 } 592 /* NOTREACHED */ 593 } 594