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 7.23 (Berkeley) 05/31/93 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 35 int icmpmaskrepl = 0; 36 #ifdef ICMPPRINTFS 37 int icmpprintfs = 0; 38 #endif 39 40 extern struct protosw inetsw[]; 41 42 /* 43 * Generate an error packet of type error 44 * in response to bad packet ip. 45 */ 46 void 47 icmp_error(n, type, code, dest, destifp) 48 struct mbuf *n; 49 int type, code; 50 n_long dest; 51 struct ifnet *destifp; 52 { 53 register struct ip *oip = mtod(n, struct ip *), *nip; 54 register unsigned oiplen = oip->ip_hl << 2; 55 register struct icmp *icp; 56 register struct mbuf *m; 57 unsigned icmplen; 58 59 #ifdef ICMPPRINTFS 60 if (icmpprintfs) 61 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 62 #endif 63 if (type != ICMP_REDIRECT) 64 icmpstat.icps_error++; 65 /* 66 * Don't send error if not the first fragment of message. 67 * Don't error if the old packet protocol was ICMP 68 * error message, only known informational types. 69 */ 70 if (oip->ip_off &~ (IP_MF|IP_DF)) 71 goto freeit; 72 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 73 n->m_len >= oiplen + ICMP_MINLEN && 74 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 75 icmpstat.icps_oldicmp++; 76 goto freeit; 77 } 78 /* Don't send error in response to a multicast or broadcast packet */ 79 if (n->m_flags & (M_BCAST|M_MCAST)) 80 goto freeit; 81 /* 82 * First, formulate icmp message 83 */ 84 m = m_gethdr(M_DONTWAIT, MT_HEADER); 85 if (m == NULL) 86 goto freeit; 87 icmplen = oiplen + min(8, oip->ip_len); 88 m->m_len = icmplen + ICMP_MINLEN; 89 MH_ALIGN(m, m->m_len); 90 icp = mtod(m, struct icmp *); 91 if ((u_int)type > ICMP_MAXTYPE) 92 panic("icmp_error"); 93 icmpstat.icps_outhist[type]++; 94 icp->icmp_type = type; 95 if (type == ICMP_REDIRECT) 96 icp->icmp_gwaddr.s_addr = dest; 97 else { 98 icp->icmp_void = 0; 99 /* 100 * The following assignments assume an overlay with the 101 * zeroed icmp_void field. 102 */ 103 if (type == ICMP_PARAMPROB) { 104 icp->icmp_pptr = code; 105 code = 0; 106 } else if (type == ICMP_UNREACH && 107 code == ICMP_UNREACH_NEEDFRAG && destifp) { 108 icp->icmp_nextmtu = htons(destifp->if_mtu); 109 } 110 } 111 112 icp->icmp_code = code; 113 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 114 nip = &icp->icmp_ip; 115 nip->ip_len = htons((u_short)(nip->ip_len + oiplen)); 116 117 /* 118 * Now, copy old ip header (without options) 119 * in front of icmp message. 120 */ 121 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 122 panic("icmp len"); 123 m->m_data -= sizeof(struct ip); 124 m->m_len += sizeof(struct ip); 125 m->m_pkthdr.len = m->m_len; 126 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 127 nip = mtod(m, struct ip *); 128 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 129 nip->ip_len = m->m_len; 130 nip->ip_hl = sizeof(struct ip) >> 2; 131 nip->ip_p = IPPROTO_ICMP; 132 nip->ip_tos = 0; 133 icmp_reflect(m); 134 135 freeit: 136 m_freem(n); 137 } 138 139 static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP }; 140 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 141 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 142 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 143 struct sockaddr_in icmpmask = { 8, 0 }; 144 struct in_ifaddr *ifptoia(); 145 146 /* 147 * Process a received ICMP message. 148 */ 149 icmp_input(m, hlen) 150 register struct mbuf *m; 151 int hlen; 152 { 153 register struct icmp *icp; 154 register struct ip *ip = mtod(m, struct ip *); 155 int icmplen = ip->ip_len; 156 register int i; 157 struct in_ifaddr *ia; 158 int (*ctlfunc)(), code; 159 extern u_char ip_protox[]; 160 161 /* 162 * Locate icmp structure in mbuf, and check 163 * that not corrupted and of at least minimum length. 164 */ 165 #ifdef ICMPPRINTFS 166 if (icmpprintfs) 167 printf("icmp_input from %x to %x, len %d\n", 168 ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), 169 icmplen); 170 #endif 171 if (icmplen < ICMP_MINLEN) { 172 icmpstat.icps_tooshort++; 173 goto freeit; 174 } 175 i = hlen + min(icmplen, ICMP_ADVLENMIN); 176 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 177 icmpstat.icps_tooshort++; 178 return; 179 } 180 ip = mtod(m, struct ip *); 181 m->m_len -= hlen; 182 m->m_data += hlen; 183 icp = mtod(m, struct icmp *); 184 if (in_cksum(m, icmplen)) { 185 icmpstat.icps_checksum++; 186 goto freeit; 187 } 188 m->m_len += hlen; 189 m->m_data -= hlen; 190 191 #ifdef ICMPPRINTFS 192 /* 193 * Message type specific processing. 194 */ 195 if (icmpprintfs) 196 printf("icmp_input, type %d code %d\n", icp->icmp_type, 197 icp->icmp_code); 198 #endif 199 if (icp->icmp_type > ICMP_MAXTYPE) 200 goto raw; 201 icmpstat.icps_inhist[icp->icmp_type]++; 202 code = icp->icmp_code; 203 switch (icp->icmp_type) { 204 205 case ICMP_UNREACH: 206 switch (code) { 207 case ICMP_UNREACH_NET: 208 case ICMP_UNREACH_HOST: 209 case ICMP_UNREACH_PROTOCOL: 210 case ICMP_UNREACH_PORT: 211 case ICMP_UNREACH_SRCFAIL: 212 code += PRC_UNREACH_NET; 213 break; 214 215 case ICMP_UNREACH_NEEDFRAG: 216 code = PRC_MSGSIZE; 217 break; 218 219 case ICMP_UNREACH_NET_UNKNOWN: 220 case ICMP_UNREACH_NET_PROHIB: 221 case ICMP_UNREACH_TOSNET: 222 code = PRC_UNREACH_NET; 223 break; 224 225 case ICMP_UNREACH_HOST_UNKNOWN: 226 case ICMP_UNREACH_ISOLATED: 227 case ICMP_UNREACH_HOST_PROHIB: 228 case ICMP_UNREACH_TOSHOST: 229 code = PRC_UNREACH_HOST; 230 break; 231 232 default: 233 goto badcode; 234 } 235 goto deliver; 236 237 case ICMP_TIMXCEED: 238 if (code > 1) 239 goto badcode; 240 code += PRC_TIMXCEED_INTRANS; 241 goto deliver; 242 243 case ICMP_PARAMPROB: 244 if (code > 1) 245 goto badcode; 246 code = PRC_PARAMPROB; 247 goto deliver; 248 249 case ICMP_SOURCEQUENCH: 250 if (code) 251 goto badcode; 252 code = PRC_QUENCH; 253 deliver: 254 /* 255 * Problem with datagram; advise higher level routines. 256 */ 257 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 258 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 259 icmpstat.icps_badlen++; 260 goto freeit; 261 } 262 NTOHS(icp->icmp_ip.ip_len); 263 #ifdef ICMPPRINTFS 264 if (icmpprintfs) 265 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 266 #endif 267 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 268 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 269 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 270 (caddr_t) &icp->icmp_ip); 271 break; 272 273 badcode: 274 icmpstat.icps_badcode++; 275 break; 276 277 case ICMP_ECHO: 278 icp->icmp_type = ICMP_ECHOREPLY; 279 goto reflect; 280 281 case ICMP_TSTAMP: 282 if (icmplen < ICMP_TSLEN) { 283 icmpstat.icps_badlen++; 284 break; 285 } 286 icp->icmp_type = ICMP_TSTAMPREPLY; 287 icp->icmp_rtime = iptime(); 288 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 289 goto reflect; 290 291 case ICMP_MASKREQ: 292 #define satosin(sa) ((struct sockaddr_in *)(sa)) 293 if (icmpmaskrepl == 0) 294 break; 295 /* 296 * We are not able to respond with all ones broadcast 297 * unless we receive it over a point-to-point interface. 298 */ 299 if (icmplen < ICMP_MASKLEN) 300 break; 301 switch (ip->ip_dst.s_addr) { 302 303 case INADDR_BROADCAST: 304 case INADDR_ANY: 305 icmpdst.sin_addr = ip->ip_src; 306 break; 307 308 default: 309 icmpdst.sin_addr = ip->ip_dst; 310 } 311 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 312 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 313 if (ia == 0) 314 break; 315 icp->icmp_type = ICMP_MASKREPLY; 316 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 317 if (ip->ip_src.s_addr == 0) { 318 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 319 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 320 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 321 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 322 } 323 reflect: 324 ip->ip_len += hlen; /* since ip_input deducts this */ 325 icmpstat.icps_reflect++; 326 icmpstat.icps_outhist[icp->icmp_type]++; 327 icmp_reflect(m); 328 return; 329 330 case ICMP_REDIRECT: 331 if (code > 3) 332 goto badcode; 333 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 334 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 335 icmpstat.icps_badlen++; 336 break; 337 } 338 /* 339 * Short circuit routing redirects to force 340 * immediate change in the kernel's routing 341 * tables. The message is also handed to anyone 342 * listening on a raw socket (e.g. the routing 343 * daemon for use in updating its tables). 344 */ 345 icmpgw.sin_addr = ip->ip_src; 346 icmpdst.sin_addr = icp->icmp_gwaddr; 347 #ifdef ICMPPRINTFS 348 if (icmpprintfs) 349 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 350 icp->icmp_gwaddr); 351 #endif 352 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 353 rtredirect((struct sockaddr *)&icmpsrc, 354 (struct sockaddr *)&icmpdst, 355 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 356 (struct sockaddr *)&icmpgw, (struct rtentry **)0); 357 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 358 break; 359 360 /* 361 * No kernel processing for the following; 362 * just fall through to send to raw listener. 363 */ 364 case ICMP_ECHOREPLY: 365 case ICMP_ROUTERADVERT: 366 case ICMP_ROUTERSOLICIT: 367 case ICMP_TSTAMPREPLY: 368 case ICMP_IREQREPLY: 369 case ICMP_MASKREPLY: 370 default: 371 break; 372 } 373 374 raw: 375 rip_input(m); 376 return; 377 378 freeit: 379 m_freem(m); 380 } 381 382 /* 383 * Reflect the ip packet back to the source 384 */ 385 icmp_reflect(m) 386 struct mbuf *m; 387 { 388 register struct ip *ip = mtod(m, struct ip *); 389 register struct in_ifaddr *ia; 390 struct in_addr t; 391 struct mbuf *opts = 0, *ip_srcroute(); 392 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 393 394 if (!in_canforward(ip->ip_src) && 395 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 396 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 397 m_freem(m); /* Bad return address */ 398 goto done; /* Ip_output() will check for broadcast */ 399 } 400 t = ip->ip_dst; 401 ip->ip_dst = ip->ip_src; 402 /* 403 * If the incoming packet was addressed directly to us, 404 * use dst as the src for the reply. Otherwise (broadcast 405 * or anonymous), use the address which corresponds 406 * to the incoming interface. 407 */ 408 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 409 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 410 break; 411 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 412 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 413 break; 414 } 415 icmpdst.sin_addr = t; 416 if (ia == (struct in_ifaddr *)0) 417 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 418 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 419 /* 420 * The following happens if the packet was not addressed to us, 421 * and was received on an interface with no IP address. 422 */ 423 if (ia == (struct in_ifaddr *)0) 424 ia = in_ifaddr; 425 t = IA_SIN(ia)->sin_addr; 426 ip->ip_src = t; 427 ip->ip_ttl = MAXTTL; 428 429 if (optlen > 0) { 430 register u_char *cp; 431 int opt, cnt; 432 u_int len; 433 434 /* 435 * Retrieve any source routing from the incoming packet; 436 * add on any record-route or timestamp options. 437 */ 438 cp = (u_char *) (ip + 1); 439 if ((opts = ip_srcroute()) == 0 && 440 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 441 opts->m_len = sizeof(struct in_addr); 442 mtod(opts, struct in_addr *)->s_addr = 0; 443 } 444 if (opts) { 445 #ifdef ICMPPRINTFS 446 if (icmpprintfs) 447 printf("icmp_reflect optlen %d rt %d => ", 448 optlen, opts->m_len); 449 #endif 450 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 451 opt = cp[IPOPT_OPTVAL]; 452 if (opt == IPOPT_EOL) 453 break; 454 if (opt == IPOPT_NOP) 455 len = 1; 456 else { 457 len = cp[IPOPT_OLEN]; 458 if (len <= 0 || len > cnt) 459 break; 460 } 461 /* 462 * Should check for overflow, but it "can't happen" 463 */ 464 if (opt == IPOPT_RR || opt == IPOPT_TS || 465 opt == IPOPT_SECURITY) { 466 bcopy((caddr_t)cp, 467 mtod(opts, caddr_t) + opts->m_len, len); 468 opts->m_len += len; 469 } 470 } 471 /* Terminate & pad, if necessary */ 472 if (cnt = opts->m_len % 4) { 473 for (; cnt < 4; cnt++) { 474 *(mtod(opts, caddr_t) + opts->m_len) = 475 IPOPT_EOL; 476 opts->m_len++; 477 } 478 } 479 #ifdef ICMPPRINTFS 480 if (icmpprintfs) 481 printf("%d\n", opts->m_len); 482 #endif 483 } 484 /* 485 * Now strip out original options by copying rest of first 486 * mbuf's data back, and adjust the IP length. 487 */ 488 ip->ip_len -= optlen; 489 ip->ip_hl = sizeof(struct ip) >> 2; 490 m->m_len -= optlen; 491 if (m->m_flags & M_PKTHDR) 492 m->m_pkthdr.len -= optlen; 493 optlen += sizeof(struct ip); 494 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 495 (unsigned)(m->m_len - sizeof(struct ip))); 496 } 497 m->m_flags &= ~(M_BCAST|M_MCAST); 498 icmp_send(m, opts); 499 done: 500 if (opts) 501 (void)m_free(opts); 502 } 503 504 /* 505 * Send an icmp packet back to the ip level, 506 * after supplying a checksum. 507 */ 508 icmp_send(m, opts) 509 register struct mbuf *m; 510 struct mbuf *opts; 511 { 512 register struct ip *ip = mtod(m, struct ip *); 513 register int hlen; 514 register struct icmp *icp; 515 516 hlen = ip->ip_hl << 2; 517 m->m_data += hlen; 518 m->m_len -= hlen; 519 icp = mtod(m, struct icmp *); 520 icp->icmp_cksum = 0; 521 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 522 m->m_data -= hlen; 523 m->m_len += hlen; 524 #ifdef ICMPPRINTFS 525 if (icmpprintfs) 526 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 527 #endif 528 (void) ip_output(m, opts, (struct route *)0, 0); 529 } 530 531 n_time 532 iptime() 533 { 534 struct timeval atv; 535 u_long t; 536 537 microtime(&atv); 538 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 539 return (htonl(t)); 540 } 541 542 icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 543 int *name; 544 u_int namelen; 545 void *oldp; 546 size_t *oldlenp; 547 void *newp; 548 size_t newlen; 549 { 550 extern int ip_ttl; 551 552 /* all sysctl names at this level are terminal */ 553 if (namelen != 1) 554 return (ENOTDIR); 555 556 switch (name[0]) { 557 case ICMPCTL_MASKREPL: 558 return (sysctl_int(oldp, oldlenp, newp, newlen, &icmpmaskrepl)); 559 default: 560 return (ENOPROTOOPT); 561 } 562 /* NOTREACHED */ 563 } 564