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/mbuf.h> 49 #include <sys/malloc.h> 50 #include <sys/socket.h> 51 #include <sys/syslog.h> 52 53 #include <net/if.h> 54 #include <net/if_dl.h> 55 #include <net/if_types.h> 56 #include <net/route.h> 57 #include <net/netisr.h> 58 #include <net/if_llc.h> 59 #include <net/ethernet.h> 60 61 #include <netinet/in.h> 62 #include <netinet/in_var.h> 63 #include <netinet/if_ether.h> 64 65 #include <net/if_arc.h> 66 #include <net/iso88025.h> 67 68 #ifdef DEV_CARP 69 #include <netinet/ip_carp.h> 70 #endif 71 72 #include <security/mac/mac_framework.h> 73 74 #define SIN(s) ((struct sockaddr_in *)s) 75 #define SDL(s) ((struct sockaddr_dl *)s) 76 77 SYSCTL_DECL(_net_link_ether); 78 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 79 80 /* timer values */ 81 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 82 83 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 84 &arpt_keep, 0, "ARP entry lifetime in seconds"); 85 86 #define rt_expire rt_rmx.rmx_expire 87 88 struct llinfo_arp { 89 struct callout la_timer; 90 struct rtentry *la_rt; 91 struct mbuf *la_hold; /* last packet until resolved/timeout */ 92 u_short la_preempt; /* countdown for pre-expiry arps */ 93 u_short la_asked; /* # requests sent */ 94 }; 95 96 static struct ifqueue arpintrq; 97 static int arp_allocated; 98 99 static int arp_maxtries = 5; 100 static int useloopback = 1; /* use loopback interface for local traffic */ 101 static int arp_proxyall = 0; 102 103 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 104 &arp_maxtries, 0, "ARP resolution attempts before returning error"); 105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 106 &useloopback, 0, "Use the loopback interface for local traffic"); 107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 108 &arp_proxyall, 0, "Enable proxy ARP for all suitable requests"); 109 110 static void arp_init(void); 111 static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *); 112 static void arprequest(struct ifnet *, 113 struct in_addr *, struct in_addr *, u_char *); 114 static void arpintr(struct mbuf *); 115 static void arptimer(void *); 116 static struct rtentry 117 *arplookup(u_long, int, int); 118 #ifdef INET 119 static void in_arpinput(struct mbuf *); 120 #endif 121 122 /* 123 * Timeout routine. 124 */ 125 static void 126 arptimer(void *arg) 127 { 128 struct rtentry *rt = (struct rtentry *)arg; 129 130 RT_LOCK_ASSERT(rt); 131 /* 132 * The lock is needed to close a theoretical race 133 * between spontaneous expiry and intentional removal. 134 * We still got an extra reference on rtentry, so can 135 * safely pass pointers to its contents. 136 */ 137 RT_UNLOCK(rt); 138 139 rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL); 140 } 141 142 /* 143 * Parallel to llc_rtrequest. 144 */ 145 static void 146 arp_rtrequest(req, rt, info) 147 int req; 148 struct rtentry *rt; 149 struct rt_addrinfo *info; 150 { 151 struct sockaddr *gate; 152 struct llinfo_arp *la; 153 static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK}; 154 struct in_ifaddr *ia; 155 struct ifaddr *ifa; 156 157 RT_LOCK_ASSERT(rt); 158 159 if (rt->rt_flags & RTF_GATEWAY) 160 return; 161 gate = rt->rt_gateway; 162 la = (struct llinfo_arp *)rt->rt_llinfo; 163 switch (req) { 164 165 case RTM_ADD: 166 /* 167 * XXX: If this is a manually added route to interface 168 * such as older version of routed or gated might provide, 169 * restore cloning bit. 170 */ 171 if ((rt->rt_flags & RTF_HOST) == 0 && 172 rt_mask(rt) != NULL && 173 SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff) 174 rt->rt_flags |= RTF_CLONING; 175 if (rt->rt_flags & RTF_CLONING) { 176 /* 177 * Case 1: This route should come from a route to iface. 178 */ 179 rt_setgate(rt, rt_key(rt), 180 (struct sockaddr *)&null_sdl); 181 gate = rt->rt_gateway; 182 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 183 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 184 rt->rt_expire = time_uptime; 185 break; 186 } 187 /* Announce a new entry if requested. */ 188 if (rt->rt_flags & RTF_ANNOUNCE) 189 arprequest(rt->rt_ifp, 190 &SIN(rt_key(rt))->sin_addr, 191 &SIN(rt_key(rt))->sin_addr, 192 (u_char *)LLADDR(SDL(gate))); 193 /*FALLTHROUGH*/ 194 case RTM_RESOLVE: 195 if (gate->sa_family != AF_LINK || 196 gate->sa_len < sizeof(null_sdl)) { 197 log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__, 198 inet_ntoa(SIN(rt_key(rt))->sin_addr), 199 (gate->sa_family != AF_LINK) ? 200 " (!AF_LINK)": ""); 201 break; 202 } 203 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 204 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 205 if (la != 0) 206 break; /* This happens on a route change */ 207 /* 208 * Case 2: This route may come from cloning, or a manual route 209 * add with a LL address. 210 */ 211 R_Zalloc(la, struct llinfo_arp *, sizeof(*la)); 212 rt->rt_llinfo = (caddr_t)la; 213 if (la == 0) { 214 log(LOG_DEBUG, "%s: malloc failed\n", __func__); 215 break; 216 } 217 arp_allocated++; 218 /* 219 * We are storing a route entry outside of radix tree. So, 220 * it can be found and accessed by other means than radix 221 * lookup. The routing code assumes that any rtentry detached 222 * from radix can be destroyed safely. To prevent this, we 223 * add an additional reference. 224 */ 225 RT_ADDREF(rt); 226 la->la_rt = rt; 227 rt->rt_flags |= RTF_LLINFO; 228 callout_init_mtx(&la->la_timer, &rt->rt_mtx, 229 CALLOUT_RETURNUNLOCKED); 230 231 #ifdef INET 232 /* 233 * This keeps the multicast addresses from showing up 234 * in `arp -a' listings as unresolved. It's not actually 235 * functional. Then the same for broadcast. 236 */ 237 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) && 238 rt->rt_ifp->if_type != IFT_ARCNET) { 239 ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr, 240 LLADDR(SDL(gate))); 241 SDL(gate)->sdl_alen = 6; 242 rt->rt_expire = 0; 243 } 244 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) { 245 memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr, 246 rt->rt_ifp->if_addrlen); 247 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen; 248 rt->rt_expire = 0; 249 } 250 #endif 251 252 TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) { 253 if (ia->ia_ifp == rt->rt_ifp && 254 SIN(rt_key(rt))->sin_addr.s_addr == 255 (IA_SIN(ia))->sin_addr.s_addr) 256 break; 257 } 258 if (ia) { 259 /* 260 * This test used to be 261 * if (loif.if_flags & IFF_UP) 262 * It allowed local traffic to be forced 263 * through the hardware by configuring the loopback down. 264 * However, it causes problems during network configuration 265 * for boards that can't receive packets they send. 266 * It is now necessary to clear "useloopback" and remove 267 * the route to force traffic out to the hardware. 268 */ 269 rt->rt_expire = 0; 270 bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)), 271 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen); 272 if (useloopback) { 273 rt->rt_ifp = loif; 274 rt->rt_rmx.rmx_mtu = loif->if_mtu; 275 } 276 277 /* 278 * make sure to set rt->rt_ifa to the interface 279 * address we are using, otherwise we will have trouble 280 * with source address selection. 281 */ 282 ifa = &ia->ia_ifa; 283 if (ifa != rt->rt_ifa) { 284 IFAFREE(rt->rt_ifa); 285 IFAREF(ifa); 286 rt->rt_ifa = ifa; 287 } 288 } 289 break; 290 291 case RTM_DELETE: 292 if (la == NULL) /* XXX: at least CARP does this. */ 293 break; 294 callout_stop(&la->la_timer); 295 rt->rt_llinfo = NULL; 296 rt->rt_flags &= ~RTF_LLINFO; 297 RT_REMREF(rt); 298 if (la->la_hold) 299 m_freem(la->la_hold); 300 Free((caddr_t)la); 301 } 302 } 303 304 /* 305 * Broadcast an ARP request. Caller specifies: 306 * - arp header source ip address 307 * - arp header target ip address 308 * - arp header source ethernet address 309 */ 310 static void 311 arprequest(ifp, sip, tip, enaddr) 312 struct ifnet *ifp; 313 struct in_addr *sip, *tip; 314 u_char *enaddr; 315 { 316 struct mbuf *m; 317 struct arphdr *ah; 318 struct sockaddr sa; 319 320 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 321 return; 322 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 323 2*ifp->if_data.ifi_addrlen; 324 m->m_pkthdr.len = m->m_len; 325 MH_ALIGN(m, m->m_len); 326 ah = mtod(m, struct arphdr *); 327 bzero((caddr_t)ah, m->m_len); 328 #ifdef MAC 329 mac_create_mbuf_linklayer(ifp, m); 330 #endif 331 ah->ar_pro = htons(ETHERTYPE_IP); 332 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 333 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 334 ah->ar_op = htons(ARPOP_REQUEST); 335 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 336 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 337 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 338 sa.sa_family = AF_ARP; 339 sa.sa_len = 2; 340 m->m_flags |= M_BCAST; 341 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 342 343 return; 344 } 345 346 /* 347 * Resolve an IP address into an ethernet address. 348 * On input: 349 * ifp is the interface we use 350 * dst is the next hop, 351 * rt0 is the route to the final destination (possibly useless) 352 * m is the mbuf 353 * desten is where we want the address. 354 * 355 * On success, desten is filled in and the function returns 0; 356 * If the packet must be held pending resolution, we return EWOULDBLOCK 357 * On other errors, we return the corresponding error code. 358 */ 359 int 360 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 361 struct sockaddr *dst, u_char *desten) 362 { 363 struct llinfo_arp *la = NULL; 364 struct rtentry *rt = NULL; 365 struct sockaddr_dl *sdl; 366 int error; 367 368 if (m->m_flags & M_BCAST) { /* broadcast */ 369 (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen); 370 return (0); 371 } 372 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */ 373 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 374 return (0); 375 } 376 377 if (rt0 != NULL) { 378 error = rt_check(&rt, &rt0, dst); 379 if (error) { 380 m_freem(m); 381 return error; 382 } 383 la = (struct llinfo_arp *)rt->rt_llinfo; 384 if (la == NULL) 385 RT_UNLOCK(rt); 386 } 387 if (la == NULL) { 388 /* 389 * We enter this block in case if rt0 was NULL, 390 * or if rt found by rt_check() didn't have llinfo. 391 */ 392 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); 393 if (rt == NULL) { 394 log(LOG_DEBUG, 395 "arpresolve: can't allocate route for %s\n", 396 inet_ntoa(SIN(dst)->sin_addr)); 397 m_freem(m); 398 return (EINVAL); /* XXX */ 399 } 400 la = (struct llinfo_arp *)rt->rt_llinfo; 401 if (la == NULL) { 402 RT_UNLOCK(rt); 403 log(LOG_DEBUG, 404 "arpresolve: can't allocate llinfo for %s\n", 405 inet_ntoa(SIN(dst)->sin_addr)); 406 m_freem(m); 407 return (EINVAL); /* XXX */ 408 } 409 } 410 sdl = SDL(rt->rt_gateway); 411 /* 412 * Check the address family and length is valid, the address 413 * is resolved; otherwise, try to resolve. 414 */ 415 if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) && 416 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { 417 418 bcopy(LLADDR(sdl), desten, sdl->sdl_alen); 419 420 /* 421 * If entry has an expiry time and it is approaching, 422 * send an ARP request. 423 */ 424 if ((rt->rt_expire != 0) && 425 (time_uptime + la->la_preempt > rt->rt_expire)) { 426 struct in_addr sin = 427 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 428 429 la->la_preempt--; 430 RT_UNLOCK(rt); 431 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 432 IF_LLADDR(ifp)); 433 return (0); 434 } 435 436 RT_UNLOCK(rt); 437 return (0); 438 } 439 /* 440 * If ARP is disabled or static on this interface, stop. 441 * XXX 442 * Probably should not allocate empty llinfo struct if we are 443 * not going to be sending out an arp request. 444 */ 445 if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) { 446 RT_UNLOCK(rt); 447 m_freem(m); 448 return (EINVAL); 449 } 450 /* 451 * There is an arptab entry, but no ethernet address 452 * response yet. Replace the held mbuf with this 453 * latest one. 454 */ 455 if (la->la_hold) 456 m_freem(la->la_hold); 457 la->la_hold = m; 458 459 KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry")); 460 461 /* 462 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 463 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 464 * if we have already sent arp_maxtries ARP requests. Retransmit the 465 * ARP request, but not faster than one request per second. 466 */ 467 if (la->la_asked < arp_maxtries) 468 error = EWOULDBLOCK; /* First request. */ 469 else 470 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH; 471 472 if (la->la_asked == 0 || rt->rt_expire != time_uptime) { 473 struct in_addr sin = 474 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 475 476 rt->rt_expire = time_uptime; 477 callout_reset(&la->la_timer, hz, arptimer, rt); 478 la->la_asked++; 479 RT_UNLOCK(rt); 480 481 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 482 IF_LLADDR(ifp)); 483 } else 484 RT_UNLOCK(rt); 485 486 return (error); 487 } 488 489 /* 490 * Common length and type checks are done here, 491 * then the protocol-specific routine is called. 492 */ 493 static void 494 arpintr(struct mbuf *m) 495 { 496 struct arphdr *ar; 497 498 if (m->m_len < sizeof(struct arphdr) && 499 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 500 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 501 return; 502 } 503 ar = mtod(m, struct arphdr *); 504 505 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 506 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 507 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 508 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 509 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 510 (unsigned char *)&ar->ar_hrd, ""); 511 m_freem(m); 512 return; 513 } 514 515 if (m->m_len < arphdr_len(ar)) { 516 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 517 log(LOG_ERR, "arp: runt packet\n"); 518 m_freem(m); 519 return; 520 } 521 ar = mtod(m, struct arphdr *); 522 } 523 524 switch (ntohs(ar->ar_pro)) { 525 #ifdef INET 526 case ETHERTYPE_IP: 527 in_arpinput(m); 528 return; 529 #endif 530 } 531 m_freem(m); 532 } 533 534 #ifdef INET 535 /* 536 * ARP for Internet protocols on 10 Mb/s Ethernet. 537 * Algorithm is that given in RFC 826. 538 * In addition, a sanity check is performed on the sender 539 * protocol address, to catch impersonators. 540 * We no longer handle negotiations for use of trailer protocol: 541 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 542 * along with IP replies if we wanted trailers sent to us, 543 * and also sent them in response to IP replies. 544 * This allowed either end to announce the desire to receive 545 * trailer packets. 546 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 547 * but formerly didn't normally send requests. 548 */ 549 static int log_arp_wrong_iface = 1; 550 static int log_arp_movements = 1; 551 static int log_arp_permanent_modify = 1; 552 553 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 554 &log_arp_wrong_iface, 0, 555 "log arp packets arriving on the wrong interface"); 556 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 557 &log_arp_movements, 0, 558 "log arp replies from MACs different than the one in the cache"); 559 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 560 &log_arp_permanent_modify, 0, 561 "log arp replies from MACs different than the one in the permanent arp entry"); 562 563 564 static void 565 in_arpinput(m) 566 struct mbuf *m; 567 { 568 struct arphdr *ah; 569 struct ifnet *ifp = m->m_pkthdr.rcvif; 570 struct llinfo_arp *la; 571 struct rtentry *rt; 572 struct ifaddr *ifa; 573 struct in_ifaddr *ia; 574 struct sockaddr_dl *sdl; 575 struct sockaddr sa; 576 struct in_addr isaddr, itaddr, myaddr; 577 struct mbuf *hold; 578 u_int8_t *enaddr = NULL; 579 int op, rif_len; 580 int req_len; 581 int bridged = 0; 582 #ifdef DEV_CARP 583 int carp_match = 0; 584 #endif 585 586 if (ifp->if_bridge) 587 bridged = 1; 588 589 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 590 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 591 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 592 return; 593 } 594 595 ah = mtod(m, struct arphdr *); 596 op = ntohs(ah->ar_op); 597 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 598 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 599 600 /* 601 * For a bridge, we want to check the address irrespective 602 * of the receive interface. (This will change slightly 603 * when we have clusters of interfaces). 604 * If the interface does not match, but the recieving interface 605 * is part of carp, we call carp_iamatch to see if this is a 606 * request for the virtual host ip. 607 * XXX: This is really ugly! 608 */ 609 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 610 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 611 (ia->ia_ifp == ifp)) && 612 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 613 goto match; 614 #ifdef DEV_CARP 615 if (ifp->if_carp != NULL && 616 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 617 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 618 carp_match = 1; 619 goto match; 620 } 621 #endif 622 } 623 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 624 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 625 (ia->ia_ifp == ifp)) && 626 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 627 goto match; 628 /* 629 * No match, use the first inet address on the receive interface 630 * as a dummy address for the rest of the function. 631 */ 632 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 633 if (ifa->ifa_addr->sa_family == AF_INET) { 634 ia = ifatoia(ifa); 635 goto match; 636 } 637 /* 638 * If bridging, fall back to using any inet address. 639 */ 640 if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL) 641 goto drop; 642 match: 643 if (!enaddr) 644 enaddr = (u_int8_t *)IF_LLADDR(ifp); 645 myaddr = ia->ia_addr.sin_addr; 646 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 647 goto drop; /* it's from me, ignore it. */ 648 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 649 log(LOG_ERR, 650 "arp: link address is broadcast for IP address %s!\n", 651 inet_ntoa(isaddr)); 652 goto drop; 653 } 654 /* 655 * Warn if another host is using the same IP address, but only if the 656 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 657 * case we suppress the warning to avoid false positive complaints of 658 * potential misconfiguration. 659 */ 660 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 661 log(LOG_ERR, 662 "arp: %*D is using my IP address %s!\n", 663 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 664 inet_ntoa(isaddr)); 665 itaddr = myaddr; 666 goto reply; 667 } 668 if (ifp->if_flags & IFF_STATICARP) 669 goto reply; 670 rt = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); 671 if (rt != NULL) { 672 la = (struct llinfo_arp *)rt->rt_llinfo; 673 if (la == NULL) { 674 RT_UNLOCK(rt); 675 goto reply; 676 } 677 } else 678 goto reply; 679 680 /* The following is not an error when doing bridging. */ 681 if (!bridged && rt->rt_ifp != ifp 682 #ifdef DEV_CARP 683 && (ifp->if_type != IFT_CARP || !carp_match) 684 #endif 685 ) { 686 if (log_arp_wrong_iface) 687 log(LOG_ERR, "arp: %s is on %s but got reply from %*D on %s\n", 688 inet_ntoa(isaddr), 689 rt->rt_ifp->if_xname, 690 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 691 ifp->if_xname); 692 RT_UNLOCK(rt); 693 goto reply; 694 } 695 sdl = SDL(rt->rt_gateway); 696 if (sdl->sdl_alen && 697 bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) { 698 if (rt->rt_expire) { 699 if (log_arp_movements) 700 log(LOG_INFO, "arp: %s moved from %*D to %*D on %s\n", 701 inet_ntoa(isaddr), 702 ifp->if_addrlen, (u_char *)LLADDR(sdl), ":", 703 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 704 ifp->if_xname); 705 } else { 706 RT_UNLOCK(rt); 707 if (log_arp_permanent_modify) 708 log(LOG_ERR, "arp: %*D attempts to modify " 709 "permanent entry for %s on %s\n", 710 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 711 inet_ntoa(isaddr), ifp->if_xname); 712 goto reply; 713 } 714 } 715 /* 716 * sanity check for the address length. 717 * XXX this does not work for protocols with variable address 718 * length. -is 719 */ 720 if (sdl->sdl_alen && 721 sdl->sdl_alen != ah->ar_hln) { 722 log(LOG_WARNING, 723 "arp from %*D: new addr len %d, was %d", 724 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 725 ah->ar_hln, sdl->sdl_alen); 726 } 727 if (ifp->if_addrlen != ah->ar_hln) { 728 log(LOG_WARNING, 729 "arp from %*D: addr len: new %d, i/f %d (ignored)", 730 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 731 ah->ar_hln, ifp->if_addrlen); 732 RT_UNLOCK(rt); 733 goto reply; 734 } 735 (void)memcpy(LLADDR(sdl), ar_sha(ah), 736 sdl->sdl_alen = ah->ar_hln); 737 /* 738 * If we receive an arp from a token-ring station over 739 * a token-ring nic then try to save the source 740 * routing info. 741 */ 742 if (ifp->if_type == IFT_ISO88025) { 743 struct iso88025_header *th = NULL; 744 struct iso88025_sockaddr_dl_data *trld; 745 746 th = (struct iso88025_header *)m->m_pkthdr.header; 747 trld = SDL_ISO88025(sdl); 748 rif_len = TR_RCF_RIFLEN(th->rcf); 749 if ((th->iso88025_shost[0] & TR_RII) && 750 (rif_len > 2)) { 751 trld->trld_rcf = th->rcf; 752 trld->trld_rcf ^= htons(TR_RCF_DIR); 753 memcpy(trld->trld_route, th->rd, rif_len - 2); 754 trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK); 755 /* 756 * Set up source routing information for 757 * reply packet (XXX) 758 */ 759 m->m_data -= rif_len; 760 m->m_len += rif_len; 761 m->m_pkthdr.len += rif_len; 762 } else { 763 th->iso88025_shost[0] &= ~TR_RII; 764 trld->trld_rcf = 0; 765 } 766 m->m_data -= 8; 767 m->m_len += 8; 768 m->m_pkthdr.len += 8; 769 th->rcf = trld->trld_rcf; 770 } 771 if (rt->rt_expire) { 772 rt->rt_expire = time_uptime + arpt_keep; 773 callout_reset(&la->la_timer, hz * arpt_keep, arptimer, rt); 774 } 775 la->la_asked = 0; 776 la->la_preempt = arp_maxtries; 777 hold = la->la_hold; 778 la->la_hold = NULL; 779 RT_UNLOCK(rt); 780 if (hold != NULL) 781 (*ifp->if_output)(ifp, hold, rt_key(rt), rt); 782 783 reply: 784 if (op != ARPOP_REQUEST) 785 goto drop; 786 if (itaddr.s_addr == myaddr.s_addr) { 787 /* I am the target */ 788 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 789 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 790 } else { 791 rt = arplookup(itaddr.s_addr, 0, SIN_PROXY); 792 if (rt == NULL) { 793 struct sockaddr_in sin; 794 795 if (!arp_proxyall) 796 goto drop; 797 798 bzero(&sin, sizeof sin); 799 sin.sin_family = AF_INET; 800 sin.sin_len = sizeof sin; 801 sin.sin_addr = itaddr; 802 803 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 804 if (!rt) 805 goto drop; 806 /* 807 * Don't send proxies for nodes on the same interface 808 * as this one came out of, or we'll get into a fight 809 * over who claims what Ether address. 810 */ 811 if (rt->rt_ifp == ifp) { 812 rtfree(rt); 813 goto drop; 814 } 815 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 816 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 817 rtfree(rt); 818 819 /* 820 * Also check that the node which sent the ARP packet 821 * is on the the interface we expect it to be on. This 822 * avoids ARP chaos if an interface is connected to the 823 * wrong network. 824 */ 825 sin.sin_addr = isaddr; 826 827 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 828 if (!rt) 829 goto drop; 830 if (rt->rt_ifp != ifp) { 831 log(LOG_INFO, "arp_proxy: ignoring request" 832 " from %s via %s, expecting %s\n", 833 inet_ntoa(isaddr), ifp->if_xname, 834 rt->rt_ifp->if_xname); 835 rtfree(rt); 836 goto drop; 837 } 838 rtfree(rt); 839 840 #ifdef DEBUG_PROXY 841 printf("arp: proxying for %s\n", 842 inet_ntoa(itaddr)); 843 #endif 844 } else { 845 /* 846 * Return proxied ARP replies only on the interface 847 * or bridge cluster where this network resides. 848 * Otherwise we may conflict with the host we are 849 * proxying for. 850 */ 851 if (rt->rt_ifp != ifp && 852 (rt->rt_ifp->if_bridge != ifp->if_bridge || 853 ifp->if_bridge == NULL)) { 854 RT_UNLOCK(rt); 855 goto drop; 856 } 857 sdl = SDL(rt->rt_gateway); 858 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 859 (void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln); 860 RT_UNLOCK(rt); 861 } 862 } 863 864 if (itaddr.s_addr == myaddr.s_addr && 865 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 866 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 867 #ifdef DEBUG_LINKLOCAL 868 printf("arp: sending reply for link-local addr %s\n", 869 inet_ntoa(itaddr)); 870 #endif 871 m->m_flags |= M_BCAST; 872 m->m_flags &= ~M_MCAST; 873 } else { 874 /* default behaviour; never reply by broadcast. */ 875 m->m_flags &= ~(M_BCAST|M_MCAST); 876 } 877 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 878 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 879 ah->ar_op = htons(ARPOP_REPLY); 880 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 881 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 882 m->m_pkthdr.len = m->m_len; 883 sa.sa_family = AF_ARP; 884 sa.sa_len = 2; 885 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 886 return; 887 888 drop: 889 m_freem(m); 890 } 891 #endif 892 893 /* 894 * Lookup or enter a new address in arptab. 895 */ 896 static struct rtentry * 897 arplookup(addr, create, proxy) 898 u_long addr; 899 int create, proxy; 900 { 901 struct rtentry *rt; 902 struct sockaddr_inarp sin; 903 const char *why = 0; 904 905 bzero(&sin, sizeof(sin)); 906 sin.sin_len = sizeof(sin); 907 sin.sin_family = AF_INET; 908 sin.sin_addr.s_addr = addr; 909 if (proxy) 910 sin.sin_other = SIN_PROXY; 911 rt = rtalloc1((struct sockaddr *)&sin, create, 0UL); 912 if (rt == 0) 913 return (0); 914 915 if (rt->rt_flags & RTF_GATEWAY) 916 why = "host is not on local network"; 917 else if ((rt->rt_flags & RTF_LLINFO) == 0) 918 why = "could not allocate llinfo"; 919 else if (rt->rt_gateway->sa_family != AF_LINK) 920 why = "gateway route is not ours"; 921 922 if (why) { 923 #define ISDYNCLONE(_rt) \ 924 (((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED) 925 if (create) 926 log(LOG_DEBUG, "arplookup %s failed: %s\n", 927 inet_ntoa(sin.sin_addr), why); 928 /* 929 * If there are no references to this Layer 2 route, 930 * and it is a cloned route, and not static, and 931 * arplookup() is creating the route, then purge 932 * it from the routing table as it is probably bogus. 933 */ 934 if (rt->rt_refcnt == 1 && ISDYNCLONE(rt)) 935 rtexpunge(rt); 936 RTFREE_LOCKED(rt); 937 return (0); 938 #undef ISDYNCLONE 939 } else { 940 RT_REMREF(rt); 941 return (rt); 942 } 943 } 944 945 void 946 arp_ifinit(ifp, ifa) 947 struct ifnet *ifp; 948 struct ifaddr *ifa; 949 { 950 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 951 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 952 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 953 ifa->ifa_rtrequest = arp_rtrequest; 954 ifa->ifa_flags |= RTF_CLONING; 955 } 956 957 void 958 arp_ifinit2(ifp, ifa, enaddr) 959 struct ifnet *ifp; 960 struct ifaddr *ifa; 961 u_char *enaddr; 962 { 963 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 964 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 965 &IA_SIN(ifa)->sin_addr, enaddr); 966 ifa->ifa_rtrequest = arp_rtrequest; 967 ifa->ifa_flags |= RTF_CLONING; 968 } 969 970 static void 971 arp_init(void) 972 { 973 974 arpintrq.ifq_maxlen = 50; 975 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 976 netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE); 977 } 978 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 979