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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 30 * $FreeBSD$ 31 */ 32 33 /* 34 * Ethernet address resolution protocol. 35 * TODO: 36 * add "inuse/lock" bit (or ref. count) along with valid bit 37 */ 38 39 #include "opt_inet.h" 40 #include "opt_mac.h" 41 #include "opt_carp.h" 42 43 #include <sys/param.h> 44 #include <sys/kernel.h> 45 #include <sys/queue.h> 46 #include <sys/sysctl.h> 47 #include <sys/systm.h> 48 #include <sys/mac.h> 49 #include <sys/mbuf.h> 50 #include <sys/malloc.h> 51 #include <sys/socket.h> 52 #include <sys/syslog.h> 53 54 #include <net/if.h> 55 #include <net/if_dl.h> 56 #include <net/if_types.h> 57 #include <net/route.h> 58 #include <net/netisr.h> 59 #include <net/if_llc.h> 60 #include <net/ethernet.h> 61 62 #include <netinet/in.h> 63 #include <netinet/in_var.h> 64 #include <netinet/if_ether.h> 65 66 #include <net/if_arc.h> 67 #include <net/iso88025.h> 68 69 #ifdef DEV_CARP 70 #include <netinet/ip_carp.h> 71 #endif 72 73 #define SIN(s) ((struct sockaddr_in *)s) 74 #define SDL(s) ((struct sockaddr_dl *)s) 75 76 SYSCTL_DECL(_net_link_ether); 77 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 78 79 /* timer values */ 80 static int arpt_prune = (5*60*1); /* walk list every 5 minutes */ 81 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 82 83 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW, 84 &arpt_prune, 0, "ARP table prune interval in seconds"); 85 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 86 &arpt_keep, 0, "ARP entry lifetime in seconds"); 87 88 #define rt_expire rt_rmx.rmx_expire 89 90 struct llinfo_arp { 91 LIST_ENTRY(llinfo_arp) la_le; 92 struct rtentry *la_rt; 93 struct mbuf *la_hold; /* last packet until resolved/timeout */ 94 u_short la_preempt; /* countdown for pre-expiry arps */ 95 u_short la_asked; /* # requests sent */ 96 }; 97 98 static LIST_HEAD(, llinfo_arp) llinfo_arp; 99 100 static struct ifqueue arpintrq; 101 static int arp_allocated; 102 103 static int arp_maxtries = 5; 104 static int useloopback = 1; /* use loopback interface for local traffic */ 105 static int arp_proxyall = 0; 106 static struct callout arp_callout; 107 108 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 109 &arp_maxtries, 0, "ARP resolution attempts before returning error"); 110 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 111 &useloopback, 0, "Use the loopback interface for local traffic"); 112 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 113 &arp_proxyall, 0, "Enable proxy ARP for all suitable requests"); 114 115 static void arp_init(void); 116 static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *); 117 static void arprequest(struct ifnet *, 118 struct in_addr *, struct in_addr *, u_char *); 119 static void arpintr(struct mbuf *); 120 static void arptimer(void *); 121 static struct rtentry 122 *arplookup(u_long, int, int); 123 #ifdef INET 124 static void in_arpinput(struct mbuf *); 125 #endif 126 127 /* 128 * Timeout routine. Age arp_tab entries periodically. 129 */ 130 /* ARGSUSED */ 131 static void 132 arptimer(void * __unused unused) 133 { 134 struct llinfo_arp *la, *ola; 135 136 RADIX_NODE_HEAD_LOCK(rt_tables[AF_INET]); 137 LIST_FOREACH_SAFE(la, &llinfo_arp, la_le, ola) { 138 struct rtentry *rt = la->la_rt; 139 140 RT_LOCK(rt); 141 if (rt->rt_expire && rt->rt_expire <= time_uptime) { 142 struct sockaddr_dl *sdl = SDL(rt->rt_gateway); 143 144 KASSERT(sdl->sdl_family == AF_LINK, ("sdl_family %d", 145 sdl->sdl_family)); 146 if (rt->rt_refcnt > 1) { 147 sdl->sdl_alen = 0; 148 la->la_preempt = la->la_asked = 0; 149 RT_UNLOCK(rt); 150 continue; 151 } 152 RT_UNLOCK(rt); 153 /* 154 * XXX: LIST_REMOVE() is deep inside rtrequest(). 155 */ 156 rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, 157 NULL); 158 continue; 159 } 160 RT_UNLOCK(rt); 161 } 162 RADIX_NODE_HEAD_UNLOCK(rt_tables[AF_INET]); 163 164 callout_reset(&arp_callout, arpt_prune * hz, arptimer, NULL); 165 } 166 167 /* 168 * Parallel to llc_rtrequest. 169 */ 170 static void 171 arp_rtrequest(req, rt, info) 172 int req; 173 struct rtentry *rt; 174 struct rt_addrinfo *info; 175 { 176 struct sockaddr *gate; 177 struct llinfo_arp *la; 178 static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK}; 179 struct in_ifaddr *ia; 180 struct ifaddr *ifa; 181 182 RT_LOCK_ASSERT(rt); 183 184 if (rt->rt_flags & RTF_GATEWAY) 185 return; 186 gate = rt->rt_gateway; 187 la = (struct llinfo_arp *)rt->rt_llinfo; 188 switch (req) { 189 190 case RTM_ADD: 191 /* 192 * XXX: If this is a manually added route to interface 193 * such as older version of routed or gated might provide, 194 * restore cloning bit. 195 */ 196 if ((rt->rt_flags & RTF_HOST) == 0 && 197 rt_mask(rt) != NULL && 198 SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff) 199 rt->rt_flags |= RTF_CLONING; 200 if (rt->rt_flags & RTF_CLONING) { 201 /* 202 * Case 1: This route should come from a route to iface. 203 */ 204 rt_setgate(rt, rt_key(rt), 205 (struct sockaddr *)&null_sdl); 206 gate = rt->rt_gateway; 207 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 208 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 209 rt->rt_expire = time_uptime; 210 break; 211 } 212 /* Announce a new entry if requested. */ 213 if (rt->rt_flags & RTF_ANNOUNCE) 214 arprequest(rt->rt_ifp, 215 &SIN(rt_key(rt))->sin_addr, 216 &SIN(rt_key(rt))->sin_addr, 217 (u_char *)LLADDR(SDL(gate))); 218 /*FALLTHROUGH*/ 219 case RTM_RESOLVE: 220 if (gate->sa_family != AF_LINK || 221 gate->sa_len < sizeof(null_sdl)) { 222 log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__, 223 inet_ntoa(SIN(rt_key(rt))->sin_addr), 224 (gate->sa_family != AF_LINK) ? 225 " (!AF_LINK)": ""); 226 break; 227 } 228 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 229 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 230 if (la != 0) 231 break; /* This happens on a route change */ 232 /* 233 * Case 2: This route may come from cloning, or a manual route 234 * add with a LL address. 235 */ 236 R_Zalloc(la, struct llinfo_arp *, sizeof(*la)); 237 rt->rt_llinfo = (caddr_t)la; 238 if (la == 0) { 239 log(LOG_DEBUG, "%s: malloc failed\n", __func__); 240 break; 241 } 242 arp_allocated++; 243 /* 244 * We are storing a route entry outside of radix tree. So, 245 * it can be found and accessed by other means than radix 246 * lookup. The routing code assumes that any rtentry detached 247 * from radix can be destroyed safely. To prevent this, we 248 * add an additional reference. 249 */ 250 RT_ADDREF(rt); 251 la->la_rt = rt; 252 rt->rt_flags |= RTF_LLINFO; 253 RADIX_NODE_HEAD_LOCK_ASSERT(rt_tables[AF_INET]); 254 LIST_INSERT_HEAD(&llinfo_arp, la, la_le); 255 256 #ifdef INET 257 /* 258 * This keeps the multicast addresses from showing up 259 * in `arp -a' listings as unresolved. It's not actually 260 * functional. Then the same for broadcast. 261 */ 262 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) && 263 rt->rt_ifp->if_type != IFT_ARCNET) { 264 ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr, 265 LLADDR(SDL(gate))); 266 SDL(gate)->sdl_alen = 6; 267 rt->rt_expire = 0; 268 } 269 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) { 270 memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr, 271 rt->rt_ifp->if_addrlen); 272 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen; 273 rt->rt_expire = 0; 274 } 275 #endif 276 277 TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) { 278 if (ia->ia_ifp == rt->rt_ifp && 279 SIN(rt_key(rt))->sin_addr.s_addr == 280 (IA_SIN(ia))->sin_addr.s_addr) 281 break; 282 } 283 if (ia) { 284 /* 285 * This test used to be 286 * if (loif.if_flags & IFF_UP) 287 * It allowed local traffic to be forced 288 * through the hardware by configuring the loopback down. 289 * However, it causes problems during network configuration 290 * for boards that can't receive packets they send. 291 * It is now necessary to clear "useloopback" and remove 292 * the route to force traffic out to the hardware. 293 */ 294 rt->rt_expire = 0; 295 bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)), 296 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen); 297 if (useloopback) 298 rt->rt_ifp = loif; 299 300 /* 301 * make sure to set rt->rt_ifa to the interface 302 * address we are using, otherwise we will have trouble 303 * with source address selection. 304 */ 305 ifa = &ia->ia_ifa; 306 if (ifa != rt->rt_ifa) { 307 IFAFREE(rt->rt_ifa); 308 IFAREF(ifa); 309 rt->rt_ifa = ifa; 310 } 311 } 312 break; 313 314 case RTM_DELETE: 315 if (la == 0) 316 break; 317 RADIX_NODE_HEAD_LOCK_ASSERT(rt_tables[AF_INET]); 318 LIST_REMOVE(la, la_le); 319 RT_REMREF(rt); 320 rt->rt_llinfo = 0; 321 rt->rt_flags &= ~RTF_LLINFO; 322 if (la->la_hold) 323 m_freem(la->la_hold); 324 Free((caddr_t)la); 325 } 326 } 327 328 /* 329 * Broadcast an ARP request. Caller specifies: 330 * - arp header source ip address 331 * - arp header target ip address 332 * - arp header source ethernet address 333 */ 334 static void 335 arprequest(ifp, sip, tip, enaddr) 336 struct ifnet *ifp; 337 struct in_addr *sip, *tip; 338 u_char *enaddr; 339 { 340 struct mbuf *m; 341 struct arphdr *ah; 342 struct sockaddr sa; 343 344 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 345 return; 346 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 347 2*ifp->if_data.ifi_addrlen; 348 m->m_pkthdr.len = m->m_len; 349 MH_ALIGN(m, m->m_len); 350 ah = mtod(m, struct arphdr *); 351 bzero((caddr_t)ah, m->m_len); 352 #ifdef MAC 353 mac_create_mbuf_linklayer(ifp, m); 354 #endif 355 ah->ar_pro = htons(ETHERTYPE_IP); 356 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 357 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 358 ah->ar_op = htons(ARPOP_REQUEST); 359 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 360 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 361 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 362 sa.sa_family = AF_ARP; 363 sa.sa_len = 2; 364 m->m_flags |= M_BCAST; 365 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 366 367 return; 368 } 369 370 /* 371 * Resolve an IP address into an ethernet address. 372 * On input: 373 * ifp is the interface we use 374 * dst is the next hop, 375 * rt0 is the route to the final destination (possibly useless) 376 * m is the mbuf 377 * desten is where we want the address. 378 * 379 * On success, desten is filled in and the function returns 0; 380 * If the packet must be held pending resolution, we return EWOULDBLOCK 381 * On other errors, we return the corresponding error code. 382 */ 383 int 384 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 385 struct sockaddr *dst, u_char *desten) 386 { 387 struct llinfo_arp *la = NULL; 388 struct rtentry *rt = NULL; 389 struct sockaddr_dl *sdl; 390 int error; 391 392 if (m->m_flags & M_BCAST) { /* broadcast */ 393 (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen); 394 return (0); 395 } 396 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */ 397 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 398 return (0); 399 } 400 401 if (rt0 != NULL) { 402 error = rt_check(&rt, &rt0, dst); 403 if (error) { 404 m_freem(m); 405 return error; 406 } 407 la = (struct llinfo_arp *)rt->rt_llinfo; 408 if (la == NULL) 409 RT_UNLOCK(rt); 410 } 411 if (la == NULL) { 412 /* 413 * We enter this block in case if rt0 was NULL, 414 * or if rt found by rt_check() didn't have llinfo. 415 */ 416 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); 417 if (rt == NULL) { 418 log(LOG_DEBUG, 419 "arpresolve: can't allocate route for %s\n", 420 inet_ntoa(SIN(dst)->sin_addr)); 421 m_freem(m); 422 return (EINVAL); /* XXX */ 423 } 424 la = (struct llinfo_arp *)rt->rt_llinfo; 425 if (la == NULL) { 426 RT_UNLOCK(rt); 427 log(LOG_DEBUG, 428 "arpresolve: can't allocate llinfo for %s\n", 429 inet_ntoa(SIN(dst)->sin_addr)); 430 m_freem(m); 431 return (EINVAL); /* XXX */ 432 } 433 } 434 sdl = SDL(rt->rt_gateway); 435 /* 436 * Check the address family and length is valid, the address 437 * is resolved; otherwise, try to resolve. 438 */ 439 if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) && 440 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { 441 442 bcopy(LLADDR(sdl), desten, sdl->sdl_alen); 443 444 /* 445 * If entry has an expiry time and it is approaching, 446 * send an ARP request. 447 */ 448 if ((rt->rt_expire != 0) && 449 (time_uptime + la->la_preempt > rt->rt_expire)) { 450 struct in_addr sin = 451 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 452 453 la->la_preempt--; 454 RT_UNLOCK(rt); 455 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 456 IF_LLADDR(ifp)); 457 return (0); 458 } 459 460 RT_UNLOCK(rt); 461 return (0); 462 } 463 /* 464 * If ARP is disabled or static on this interface, stop. 465 * XXX 466 * Probably should not allocate empty llinfo struct if we are 467 * not going to be sending out an arp request. 468 */ 469 if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) { 470 RT_UNLOCK(rt); 471 m_freem(m); 472 return (EINVAL); 473 } 474 /* 475 * There is an arptab entry, but no ethernet address 476 * response yet. Replace the held mbuf with this 477 * latest one. 478 */ 479 if (la->la_hold) 480 m_freem(la->la_hold); 481 la->la_hold = m; 482 483 KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry")); 484 485 /* 486 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 487 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 488 * if we have already sent arp_maxtries ARP requests. Retransmit the 489 * ARP request, but not faster than one request per second. 490 */ 491 if (la->la_asked < arp_maxtries) 492 error = EWOULDBLOCK; /* First request. */ 493 else 494 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH; 495 496 if (la->la_asked++ == 0 || rt->rt_expire != time_uptime) { 497 struct in_addr sin = 498 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 499 500 rt->rt_expire = time_uptime; 501 RT_UNLOCK(rt); 502 503 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 504 IF_LLADDR(ifp)); 505 } else 506 RT_UNLOCK(rt); 507 508 return (error); 509 } 510 511 /* 512 * Common length and type checks are done here, 513 * then the protocol-specific routine is called. 514 */ 515 static void 516 arpintr(struct mbuf *m) 517 { 518 struct arphdr *ar; 519 520 if (m->m_len < sizeof(struct arphdr) && 521 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 522 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 523 return; 524 } 525 ar = mtod(m, struct arphdr *); 526 527 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 528 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 529 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 530 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 531 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 532 (unsigned char *)&ar->ar_hrd, ""); 533 m_freem(m); 534 return; 535 } 536 537 if (m->m_len < arphdr_len(ar)) { 538 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 539 log(LOG_ERR, "arp: runt packet\n"); 540 m_freem(m); 541 return; 542 } 543 ar = mtod(m, struct arphdr *); 544 } 545 546 switch (ntohs(ar->ar_pro)) { 547 #ifdef INET 548 case ETHERTYPE_IP: 549 in_arpinput(m); 550 return; 551 #endif 552 } 553 m_freem(m); 554 } 555 556 #ifdef INET 557 /* 558 * ARP for Internet protocols on 10 Mb/s Ethernet. 559 * Algorithm is that given in RFC 826. 560 * In addition, a sanity check is performed on the sender 561 * protocol address, to catch impersonators. 562 * We no longer handle negotiations for use of trailer protocol: 563 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 564 * along with IP replies if we wanted trailers sent to us, 565 * and also sent them in response to IP replies. 566 * This allowed either end to announce the desire to receive 567 * trailer packets. 568 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 569 * but formerly didn't normally send requests. 570 */ 571 static int log_arp_wrong_iface = 1; 572 static int log_arp_movements = 1; 573 574 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 575 &log_arp_wrong_iface, 0, 576 "log arp packets arriving on the wrong interface"); 577 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 578 &log_arp_movements, 0, 579 "log arp replies from MACs different than the one in the cache"); 580 581 582 static void 583 in_arpinput(m) 584 struct mbuf *m; 585 { 586 struct arphdr *ah; 587 struct ifnet *ifp = m->m_pkthdr.rcvif; 588 struct iso88025_header *th = (struct iso88025_header *)0; 589 struct iso88025_sockaddr_dl_data *trld; 590 struct llinfo_arp *la; 591 struct rtentry *rt; 592 struct ifaddr *ifa; 593 struct in_ifaddr *ia; 594 struct sockaddr_dl *sdl; 595 struct sockaddr sa; 596 struct in_addr isaddr, itaddr, myaddr; 597 struct mbuf *hold; 598 u_int8_t *enaddr = NULL; 599 int op, rif_len; 600 int req_len; 601 int bridged = 0; 602 #ifdef DEV_CARP 603 int carp_match = 0; 604 #endif 605 606 if (ifp->if_bridge) 607 bridged = 1; 608 609 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 610 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 611 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 612 return; 613 } 614 615 ah = mtod(m, struct arphdr *); 616 op = ntohs(ah->ar_op); 617 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 618 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 619 620 /* 621 * For a bridge, we want to check the address irrespective 622 * of the receive interface. (This will change slightly 623 * when we have clusters of interfaces). 624 * If the interface does not match, but the recieving interface 625 * is part of carp, we call carp_iamatch to see if this is a 626 * request for the virtual host ip. 627 * XXX: This is really ugly! 628 */ 629 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 630 if ((bridged || (ia->ia_ifp == ifp)) && 631 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 632 goto match; 633 #ifdef DEV_CARP 634 if (ifp->if_carp != NULL && 635 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 636 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 637 carp_match = 1; 638 goto match; 639 } 640 #endif 641 } 642 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 643 if ((bridged || (ia->ia_ifp == ifp)) && 644 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 645 goto match; 646 /* 647 * No match, use the first inet address on the receive interface 648 * as a dummy address for the rest of the function. 649 */ 650 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 651 if (ifa->ifa_addr && ifa->ifa_addr->sa_family == AF_INET) { 652 ia = ifatoia(ifa); 653 goto match; 654 } 655 /* 656 * If bridging, fall back to using any inet address. 657 */ 658 if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL) 659 goto drop; 660 match: 661 if (!enaddr) 662 enaddr = (u_int8_t *)IF_LLADDR(ifp); 663 myaddr = ia->ia_addr.sin_addr; 664 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 665 goto drop; /* it's from me, ignore it. */ 666 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 667 log(LOG_ERR, 668 "arp: link address is broadcast for IP address %s!\n", 669 inet_ntoa(isaddr)); 670 goto drop; 671 } 672 /* 673 * Warn if another host is using the same IP address, but only if the 674 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 675 * case we suppress the warning to avoid false positive complaints of 676 * potential misconfiguration. 677 */ 678 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 679 log(LOG_ERR, 680 "arp: %*D is using my IP address %s!\n", 681 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 682 inet_ntoa(isaddr)); 683 itaddr = myaddr; 684 goto reply; 685 } 686 if (ifp->if_flags & IFF_STATICARP) 687 goto reply; 688 rt = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); 689 if (rt != NULL) { 690 la = (struct llinfo_arp *)rt->rt_llinfo; 691 if (la == NULL) { 692 RT_UNLOCK(rt); 693 goto reply; 694 } 695 } else 696 goto reply; 697 698 /* The following is not an error when doing bridging. */ 699 if (!bridged && rt->rt_ifp != ifp 700 #ifdef DEV_CARP 701 && (ifp->if_type != IFT_CARP || !carp_match) 702 #endif 703 ) { 704 if (log_arp_wrong_iface) 705 log(LOG_ERR, "arp: %s is on %s but got reply from %*D on %s\n", 706 inet_ntoa(isaddr), 707 rt->rt_ifp->if_xname, 708 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 709 ifp->if_xname); 710 RT_UNLOCK(rt); 711 goto reply; 712 } 713 sdl = SDL(rt->rt_gateway); 714 if (sdl->sdl_alen && 715 bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) { 716 if (rt->rt_expire) { 717 if (log_arp_movements) 718 log(LOG_INFO, "arp: %s moved from %*D to %*D on %s\n", 719 inet_ntoa(isaddr), 720 ifp->if_addrlen, (u_char *)LLADDR(sdl), ":", 721 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 722 ifp->if_xname); 723 } else { 724 log(LOG_ERR, 725 "arp: %*D attempts to modify permanent entry for %s on %s\n", 726 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 727 inet_ntoa(isaddr), ifp->if_xname); 728 RT_UNLOCK(rt); 729 goto reply; 730 } 731 } 732 /* 733 * sanity check for the address length. 734 * XXX this does not work for protocols with variable address 735 * length. -is 736 */ 737 if (sdl->sdl_alen && 738 sdl->sdl_alen != ah->ar_hln) { 739 log(LOG_WARNING, 740 "arp from %*D: new addr len %d, was %d", 741 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 742 ah->ar_hln, sdl->sdl_alen); 743 } 744 if (ifp->if_addrlen != ah->ar_hln) { 745 log(LOG_WARNING, 746 "arp from %*D: addr len: new %d, i/f %d (ignored)", 747 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 748 ah->ar_hln, ifp->if_addrlen); 749 RT_UNLOCK(rt); 750 goto reply; 751 } 752 (void)memcpy(LLADDR(sdl), ar_sha(ah), 753 sdl->sdl_alen = ah->ar_hln); 754 /* 755 * If we receive an arp from a token-ring station over 756 * a token-ring nic then try to save the source 757 * routing info. 758 */ 759 if (ifp->if_type == IFT_ISO88025) { 760 th = (struct iso88025_header *)m->m_pkthdr.header; 761 trld = SDL_ISO88025(sdl); 762 rif_len = TR_RCF_RIFLEN(th->rcf); 763 if ((th->iso88025_shost[0] & TR_RII) && 764 (rif_len > 2)) { 765 trld->trld_rcf = th->rcf; 766 trld->trld_rcf ^= htons(TR_RCF_DIR); 767 memcpy(trld->trld_route, th->rd, rif_len - 2); 768 trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK); 769 /* 770 * Set up source routing information for 771 * reply packet (XXX) 772 */ 773 m->m_data -= rif_len; 774 m->m_len += rif_len; 775 m->m_pkthdr.len += rif_len; 776 } else { 777 th->iso88025_shost[0] &= ~TR_RII; 778 trld->trld_rcf = 0; 779 } 780 m->m_data -= 8; 781 m->m_len += 8; 782 m->m_pkthdr.len += 8; 783 th->rcf = trld->trld_rcf; 784 } 785 if (rt->rt_expire) 786 rt->rt_expire = time_uptime + arpt_keep; 787 la->la_asked = 0; 788 la->la_preempt = arp_maxtries; 789 hold = la->la_hold; 790 la->la_hold = NULL; 791 RT_UNLOCK(rt); 792 if (hold != NULL) 793 (*ifp->if_output)(ifp, hold, rt_key(rt), rt); 794 795 reply: 796 if (op != ARPOP_REQUEST) 797 goto drop; 798 if (itaddr.s_addr == myaddr.s_addr) { 799 /* I am the target */ 800 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 801 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 802 } else { 803 rt = arplookup(itaddr.s_addr, 0, SIN_PROXY); 804 if (rt == NULL) { 805 struct sockaddr_in sin; 806 807 if (!arp_proxyall) 808 goto drop; 809 810 bzero(&sin, sizeof sin); 811 sin.sin_family = AF_INET; 812 sin.sin_len = sizeof sin; 813 sin.sin_addr = itaddr; 814 815 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 816 if (!rt) 817 goto drop; 818 /* 819 * Don't send proxies for nodes on the same interface 820 * as this one came out of, or we'll get into a fight 821 * over who claims what Ether address. 822 */ 823 if (rt->rt_ifp == ifp) { 824 rtfree(rt); 825 goto drop; 826 } 827 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 828 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 829 rtfree(rt); 830 831 /* 832 * Also check that the node which sent the ARP packet 833 * is on the the interface we expect it to be on. This 834 * avoids ARP chaos if an interface is connected to the 835 * wrong network. 836 */ 837 sin.sin_addr = isaddr; 838 839 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 840 if (!rt) 841 goto drop; 842 if (rt->rt_ifp != ifp) { 843 log(LOG_INFO, "arp_proxy: ignoring request" 844 " from %s via %s, expecting %s\n", 845 inet_ntoa(isaddr), ifp->if_xname, 846 rt->rt_ifp->if_xname); 847 rtfree(rt); 848 goto drop; 849 } 850 rtfree(rt); 851 852 #ifdef DEBUG_PROXY 853 printf("arp: proxying for %s\n", 854 inet_ntoa(itaddr)); 855 #endif 856 } else { 857 /* 858 * Return proxied ARP replies only on the interface 859 * where this network resides. Otherwise we may 860 * conflict with the host we are proxying for. 861 */ 862 if (rt->rt_ifp != ifp) { 863 RT_UNLOCK(rt); 864 goto drop; 865 } 866 sdl = SDL(rt->rt_gateway); 867 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 868 (void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln); 869 RT_UNLOCK(rt); 870 } 871 } 872 873 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 874 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 875 ah->ar_op = htons(ARPOP_REPLY); 876 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 877 m->m_flags &= ~(M_BCAST|M_MCAST); /* never reply by broadcast */ 878 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 879 m->m_pkthdr.len = m->m_len; 880 sa.sa_family = AF_ARP; 881 sa.sa_len = 2; 882 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 883 return; 884 885 drop: 886 m_freem(m); 887 } 888 #endif 889 890 /* 891 * Lookup or enter a new address in arptab. 892 */ 893 static struct rtentry * 894 arplookup(addr, create, proxy) 895 u_long addr; 896 int create, proxy; 897 { 898 struct rtentry *rt; 899 struct sockaddr_inarp sin; 900 const char *why = 0; 901 902 bzero(&sin, sizeof(sin)); 903 sin.sin_len = sizeof(sin); 904 sin.sin_family = AF_INET; 905 sin.sin_addr.s_addr = addr; 906 if (proxy) 907 sin.sin_other = SIN_PROXY; 908 rt = rtalloc1((struct sockaddr *)&sin, create, 0UL); 909 if (rt == 0) 910 return (0); 911 912 if (rt->rt_flags & RTF_GATEWAY) 913 why = "host is not on local network"; 914 else if ((rt->rt_flags & RTF_LLINFO) == 0) 915 why = "could not allocate llinfo"; 916 else if (rt->rt_gateway->sa_family != AF_LINK) 917 why = "gateway route is not ours"; 918 919 if (why) { 920 #define ISDYNCLONE(_rt) \ 921 (((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED) 922 if (create) 923 log(LOG_DEBUG, "arplookup %s failed: %s\n", 924 inet_ntoa(sin.sin_addr), why); 925 /* 926 * If there are no references to this Layer 2 route, 927 * and it is a cloned route, and not static, and 928 * arplookup() is creating the route, then purge 929 * it from the routing table as it is probably bogus. 930 */ 931 if (rt->rt_refcnt == 1 && ISDYNCLONE(rt)) 932 rtexpunge(rt); 933 RTFREE_LOCKED(rt); 934 return (0); 935 #undef ISDYNCLONE 936 } else { 937 RT_REMREF(rt); 938 return (rt); 939 } 940 } 941 942 void 943 arp_ifinit(ifp, ifa) 944 struct ifnet *ifp; 945 struct ifaddr *ifa; 946 { 947 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 948 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 949 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 950 ifa->ifa_rtrequest = arp_rtrequest; 951 ifa->ifa_flags |= RTF_CLONING; 952 } 953 954 void 955 arp_ifinit2(ifp, ifa, enaddr) 956 struct ifnet *ifp; 957 struct ifaddr *ifa; 958 u_char *enaddr; 959 { 960 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 961 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 962 &IA_SIN(ifa)->sin_addr, enaddr); 963 ifa->ifa_rtrequest = arp_rtrequest; 964 ifa->ifa_flags |= RTF_CLONING; 965 } 966 967 static void 968 arp_init(void) 969 { 970 971 arpintrq.ifq_maxlen = 50; 972 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 973 LIST_INIT(&llinfo_arp); 974 callout_init(&arp_callout, CALLOUT_MPSAFE); 975 netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE); 976 callout_reset(&arp_callout, hz, arptimer, NULL); 977 } 978 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 979