1 /* 2 * Copyright (c) 1982, 1986, 1988 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)ip_icmp.c 7.21 (Berkeley) 04/07/93 8 */ 9 10 #include <sys/param.h> 11 #include <sys/systm.h> 12 #include <sys/malloc.h> 13 #include <sys/mbuf.h> 14 #include <sys/protosw.h> 15 #include <sys/socket.h> 16 #include <sys/time.h> 17 #include <sys/kernel.h> 18 19 #include <net/route.h> 20 #include <net/if.h> 21 22 #include <netinet/in.h> 23 #include <netinet/in_systm.h> 24 #include <netinet/in_var.h> 25 #include <netinet/ip.h> 26 #include <netinet/ip_icmp.h> 27 #include <netinet/icmp_var.h> 28 29 /* 30 * ICMP routines: error generation, receive packet processing, and 31 * routines to turnaround packets back to the originator, and 32 * host table maintenance routines. 33 */ 34 #ifdef ICMPPRINTFS 35 int icmpprintfs = 0; 36 #endif 37 38 extern struct protosw inetsw[]; 39 40 /* 41 * Generate an error packet of type error 42 * in response to bad packet ip. 43 */ 44 /*VARARGS3*/ 45 icmp_error(n, type, code, dest, destifp) 46 struct mbuf *n; 47 int type, code; 48 struct in_addr dest; 49 struct ifnet *destifp; 50 { 51 register struct ip *oip = mtod(n, struct ip *), *nip; 52 register unsigned oiplen = oip->ip_hl << 2; 53 register struct icmp *icp; 54 register struct mbuf *m; 55 unsigned icmplen; 56 57 #ifdef ICMPPRINTFS 58 if (icmpprintfs) 59 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 60 #endif 61 if (type != ICMP_REDIRECT) 62 icmpstat.icps_error++; 63 /* 64 * Don't send error if not the first fragment of message. 65 * Don't error if the old packet protocol was ICMP 66 * error message, only known informational types. 67 */ 68 if (oip->ip_off &~ (IP_MF|IP_DF)) 69 goto freeit; 70 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 71 n->m_len >= oiplen + ICMP_MINLEN && 72 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 73 icmpstat.icps_oldicmp++; 74 goto freeit; 75 } 76 /* Don't send error in response to a multicast or broadcast packet */ 77 if (n->m_flags & (M_BCAST|M_MCAST)) 78 goto freeit; 79 /* 80 * First, formulate icmp message 81 */ 82 m = m_gethdr(M_DONTWAIT, MT_HEADER); 83 if (m == NULL) 84 goto freeit; 85 icmplen = oiplen + min(8, oip->ip_len); 86 m->m_len = icmplen + ICMP_MINLEN; 87 MH_ALIGN(m, m->m_len); 88 icp = mtod(m, struct icmp *); 89 if ((u_int)type > ICMP_MAXTYPE) 90 panic("icmp_error"); 91 icmpstat.icps_outhist[type]++; 92 icp->icmp_type = type; 93 if (type == ICMP_REDIRECT) 94 icp->icmp_gwaddr = dest; 95 else { 96 icp->icmp_void = 0; 97 /* 98 * The following assignments assume an overlay with the 99 * zeroed icmp_void field. 100 */ 101 if (type == ICMP_PARAMPROB) { 102 icp->icmp_pptr = code; 103 code = 0; 104 } else if (type == ICMP_UNREACH && 105 code == ICMP_UNREACH_NEEDFRAG && destifp) { 106 icp->icmp_nextmtu = htons(destifp->if_mtu); 107 } 108 } 109 110 icp->icmp_code = code; 111 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 112 nip = &icp->icmp_ip; 113 nip->ip_len = htons((u_short)(nip->ip_len + oiplen)); 114 115 /* 116 * Now, copy old ip header (without options) 117 * in front of icmp message. 118 */ 119 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 120 panic("icmp len"); 121 m->m_data -= sizeof(struct ip); 122 m->m_len += sizeof(struct ip); 123 m->m_pkthdr.len = m->m_len; 124 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 125 nip = mtod(m, struct ip *); 126 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 127 nip->ip_len = m->m_len; 128 nip->ip_hl = sizeof(struct ip) >> 2; 129 nip->ip_p = IPPROTO_ICMP; 130 nip->ip_tos = 0; 131 icmp_reflect(m); 132 133 freeit: 134 m_freem(n); 135 } 136 137 static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP }; 138 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 139 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 140 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 141 struct sockaddr_in icmpmask = { 8, 0 }; 142 struct in_ifaddr *ifptoia(); 143 144 /* 145 * Process a received ICMP message. 146 */ 147 icmp_input(m, hlen) 148 register struct mbuf *m; 149 int hlen; 150 { 151 register struct icmp *icp; 152 register struct ip *ip = mtod(m, struct ip *); 153 int icmplen = ip->ip_len; 154 register int i; 155 struct in_ifaddr *ia; 156 int (*ctlfunc)(), code; 157 extern u_char ip_protox[]; 158 159 /* 160 * Locate icmp structure in mbuf, and check 161 * that not corrupted and of at least minimum length. 162 */ 163 #ifdef ICMPPRINTFS 164 if (icmpprintfs) 165 printf("icmp_input from %x to %x, len %d\n", 166 ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), 167 icmplen); 168 #endif 169 if (icmplen < ICMP_MINLEN) { 170 icmpstat.icps_tooshort++; 171 goto freeit; 172 } 173 i = hlen + min(icmplen, ICMP_ADVLENMIN); 174 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 175 icmpstat.icps_tooshort++; 176 return; 177 } 178 ip = mtod(m, struct ip *); 179 m->m_len -= hlen; 180 m->m_data += hlen; 181 icp = mtod(m, struct icmp *); 182 if (in_cksum(m, icmplen)) { 183 icmpstat.icps_checksum++; 184 goto freeit; 185 } 186 m->m_len += hlen; 187 m->m_data -= hlen; 188 189 #ifdef ICMPPRINTFS 190 /* 191 * Message type specific processing. 192 */ 193 if (icmpprintfs) 194 printf("icmp_input, type %d code %d\n", icp->icmp_type, 195 icp->icmp_code); 196 #endif 197 if (icp->icmp_type > ICMP_MAXTYPE) 198 goto raw; 199 icmpstat.icps_inhist[icp->icmp_type]++; 200 code = icp->icmp_code; 201 switch (icp->icmp_type) { 202 203 case ICMP_UNREACH: 204 switch (code) { 205 case ICMP_UNREACH_NET: 206 case ICMP_UNREACH_HOST: 207 case ICMP_UNREACH_PROTOCOL: 208 case ICMP_UNREACH_PORT: 209 case ICMP_UNREACH_SRCFAIL: 210 code += PRC_UNREACH_NET; 211 break; 212 213 case ICMP_UNREACH_NEEDFRAG: 214 code = PRC_MSGSIZE; 215 break; 216 217 case ICMP_UNREACH_NET_UNKNOWN: 218 case ICMP_UNREACH_NET_PROHIB: 219 case ICMP_UNREACH_TOSNET: 220 code = PRC_UNREACH_NET; 221 break; 222 223 case ICMP_UNREACH_HOST_UNKNOWN: 224 case ICMP_UNREACH_ISOLATED: 225 case ICMP_UNREACH_HOST_PROHIB: 226 case ICMP_UNREACH_TOSHOST: 227 code = PRC_UNREACH_HOST; 228 break; 229 230 default: 231 goto badcode; 232 } 233 goto deliver; 234 235 case ICMP_TIMXCEED: 236 if (code > 1) 237 goto badcode; 238 code += PRC_TIMXCEED_INTRANS; 239 goto deliver; 240 241 case ICMP_PARAMPROB: 242 if (code > 1) 243 goto badcode; 244 code = PRC_PARAMPROB; 245 goto deliver; 246 247 case ICMP_SOURCEQUENCH: 248 if (code) 249 goto badcode; 250 code = PRC_QUENCH; 251 deliver: 252 /* 253 * Problem with datagram; advise higher level routines. 254 */ 255 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 256 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 257 icmpstat.icps_badlen++; 258 goto freeit; 259 } 260 NTOHS(icp->icmp_ip.ip_len); 261 #ifdef ICMPPRINTFS 262 if (icmpprintfs) 263 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 264 #endif 265 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 266 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 267 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 268 (caddr_t) &icp->icmp_ip); 269 break; 270 271 badcode: 272 icmpstat.icps_badcode++; 273 break; 274 275 case ICMP_ECHO: 276 icp->icmp_type = ICMP_ECHOREPLY; 277 goto reflect; 278 279 case ICMP_TSTAMP: 280 if (icmplen < ICMP_TSLEN) { 281 icmpstat.icps_badlen++; 282 break; 283 } 284 icp->icmp_type = ICMP_TSTAMPREPLY; 285 icp->icmp_rtime = iptime(); 286 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 287 goto reflect; 288 289 case ICMP_MASKREQ: 290 #define satosin(sa) ((struct sockaddr_in *)(sa)) 291 /* 292 * We are not able to respond with all ones broadcast 293 * unless we receive it over a point-to-point interface. 294 */ 295 if (icmplen < ICMP_MASKLEN) 296 break; 297 switch (ip->ip_dst.s_addr) { 298 299 case INADDR_BROADCAST: 300 case INADDR_ANY: 301 icmpdst.sin_addr = ip->ip_src; 302 break; 303 304 default: 305 icmpdst.sin_addr = ip->ip_dst; 306 } 307 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 308 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 309 if (ia == 0) 310 break; 311 icp->icmp_type = ICMP_MASKREPLY; 312 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 313 if (ip->ip_src.s_addr == 0) { 314 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 315 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 316 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 317 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 318 } 319 reflect: 320 ip->ip_len += hlen; /* since ip_input deducts this */ 321 icmpstat.icps_reflect++; 322 icmpstat.icps_outhist[icp->icmp_type]++; 323 icmp_reflect(m); 324 return; 325 326 case ICMP_REDIRECT: 327 if (code > 3) 328 goto badcode; 329 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 330 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 331 icmpstat.icps_badlen++; 332 break; 333 } 334 /* 335 * Short circuit routing redirects to force 336 * immediate change in the kernel's routing 337 * tables. The message is also handed to anyone 338 * listening on a raw socket (e.g. the routing 339 * daemon for use in updating its tables). 340 */ 341 icmpgw.sin_addr = ip->ip_src; 342 icmpdst.sin_addr = icp->icmp_gwaddr; 343 #ifdef ICMPPRINTFS 344 if (icmpprintfs) 345 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 346 icp->icmp_gwaddr); 347 #endif 348 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 349 rtredirect((struct sockaddr *)&icmpsrc, 350 (struct sockaddr *)&icmpdst, 351 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 352 (struct sockaddr *)&icmpgw, (struct rtentry **)0); 353 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 354 break; 355 356 /* 357 * No kernel processing for the following; 358 * just fall through to send to raw listener. 359 */ 360 case ICMP_ECHOREPLY: 361 case ICMP_ROUTERADVERT: 362 case ICMP_ROUTERSOLICIT: 363 case ICMP_TSTAMPREPLY: 364 case ICMP_IREQREPLY: 365 case ICMP_MASKREPLY: 366 default: 367 break; 368 } 369 370 raw: 371 rip_input(m); 372 return; 373 374 freeit: 375 m_freem(m); 376 } 377 378 /* 379 * Reflect the ip packet back to the source 380 */ 381 icmp_reflect(m) 382 struct mbuf *m; 383 { 384 register struct ip *ip = mtod(m, struct ip *); 385 register struct in_ifaddr *ia; 386 struct in_addr t; 387 struct mbuf *opts = 0, *ip_srcroute(); 388 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 389 390 if (!in_canforward(ip->ip_src) && 391 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 392 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 393 m_freem(m); /* Bad return address */ 394 goto done; /* Ip_output() will check for broadcast */ 395 } 396 t = ip->ip_dst; 397 ip->ip_dst = ip->ip_src; 398 /* 399 * If the incoming packet was addressed directly to us, 400 * use dst as the src for the reply. Otherwise (broadcast 401 * or anonymous), use the address which corresponds 402 * to the incoming interface. 403 */ 404 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 405 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 406 break; 407 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 408 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 409 break; 410 } 411 icmpdst.sin_addr = t; 412 if (ia == (struct in_ifaddr *)0) 413 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 414 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 415 /* 416 * The following happens if the packet was not addressed to us, 417 * and was received on an interface with no IP address. 418 */ 419 if (ia == (struct in_ifaddr *)0) 420 ia = in_ifaddr; 421 t = IA_SIN(ia)->sin_addr; 422 ip->ip_src = t; 423 ip->ip_ttl = MAXTTL; 424 425 if (optlen > 0) { 426 register u_char *cp; 427 int opt, cnt; 428 u_int len; 429 430 /* 431 * Retrieve any source routing from the incoming packet; 432 * add on any record-route or timestamp options. 433 */ 434 cp = (u_char *) (ip + 1); 435 if ((opts = ip_srcroute()) == 0 && 436 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 437 opts->m_len = sizeof(struct in_addr); 438 mtod(opts, struct in_addr *)->s_addr = 0; 439 } 440 if (opts) { 441 #ifdef ICMPPRINTFS 442 if (icmpprintfs) 443 printf("icmp_reflect optlen %d rt %d => ", 444 optlen, opts->m_len); 445 #endif 446 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 447 opt = cp[IPOPT_OPTVAL]; 448 if (opt == IPOPT_EOL) 449 break; 450 if (opt == IPOPT_NOP) 451 len = 1; 452 else { 453 len = cp[IPOPT_OLEN]; 454 if (len <= 0 || len > cnt) 455 break; 456 } 457 /* 458 * Should check for overflow, but it "can't happen" 459 */ 460 if (opt == IPOPT_RR || opt == IPOPT_TS || 461 opt == IPOPT_SECURITY) { 462 bcopy((caddr_t)cp, 463 mtod(opts, caddr_t) + opts->m_len, len); 464 opts->m_len += len; 465 } 466 } 467 /* Terminate & pad, if necessary */ 468 if (cnt = opts->m_len % 4) { 469 for (; cnt < 4; cnt++) { 470 *(mtod(opts, caddr_t) + opts->m_len) = 471 IPOPT_EOL; 472 opts->m_len++; 473 } 474 } 475 #ifdef ICMPPRINTFS 476 if (icmpprintfs) 477 printf("%d\n", opts->m_len); 478 #endif 479 } 480 /* 481 * Now strip out original options by copying rest of first 482 * mbuf's data back, and adjust the IP length. 483 */ 484 ip->ip_len -= optlen; 485 ip->ip_hl = sizeof(struct ip) >> 2; 486 m->m_len -= optlen; 487 if (m->m_flags & M_PKTHDR) 488 m->m_pkthdr.len -= optlen; 489 optlen += sizeof(struct ip); 490 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 491 (unsigned)(m->m_len - sizeof(struct ip))); 492 } 493 m->m_flags &= ~(M_BCAST|M_MCAST); 494 icmp_send(m, opts); 495 done: 496 if (opts) 497 (void)m_free(opts); 498 } 499 500 /* 501 * Send an icmp packet back to the ip level, 502 * after supplying a checksum. 503 */ 504 icmp_send(m, opts) 505 register struct mbuf *m; 506 struct mbuf *opts; 507 { 508 register struct ip *ip = mtod(m, struct ip *); 509 register int hlen; 510 register struct icmp *icp; 511 512 hlen = ip->ip_hl << 2; 513 m->m_data += hlen; 514 m->m_len -= hlen; 515 icp = mtod(m, struct icmp *); 516 icp->icmp_cksum = 0; 517 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 518 m->m_data -= hlen; 519 m->m_len += hlen; 520 #ifdef ICMPPRINTFS 521 if (icmpprintfs) 522 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 523 #endif 524 (void) ip_output(m, opts, (struct route *)0, 0); 525 } 526 527 n_time 528 iptime() 529 { 530 struct timeval atv; 531 u_long t; 532 533 microtime(&atv); 534 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 535 return (htonl(t)); 536 } 537