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 */ 31 32 /* 33 * Ethernet address resolution protocol. 34 * TODO: 35 * add "inuse/lock" bit (or ref. count) along with valid bit 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_inet.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/proc.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/netisr.h> 58 #include <net/if_llc.h> 59 #include <net/ethernet.h> 60 #include <net/route.h> 61 #include <net/vnet.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_var.h> 65 #include <net/if_llatbl.h> 66 #include <netinet/if_ether.h> 67 #if defined(INET) || defined(INET6) 68 #include <netinet/ip_carp.h> 69 #endif 70 71 #include <net/if_arc.h> 72 #include <net/iso88025.h> 73 74 #include <security/mac/mac_framework.h> 75 76 #define SIN(s) ((struct sockaddr_in *)s) 77 #define SDL(s) ((struct sockaddr_dl *)s) 78 79 SYSCTL_DECL(_net_link_ether); 80 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 81 SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 82 83 /* timer values */ 84 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 85 * minutes */ 86 static VNET_DEFINE(int, arp_maxtries) = 5; 87 VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for 88 * local traffic */ 89 static VNET_DEFINE(int, arp_proxyall) = 0; 90 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 91 * 20 seconds */ 92 VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 93 94 static VNET_DEFINE(int, arp_maxhold) = 1; 95 96 #define V_arpt_keep VNET(arpt_keep) 97 #define V_arpt_down VNET(arpt_down) 98 #define V_arp_maxtries VNET(arp_maxtries) 99 #define V_arp_proxyall VNET(arp_proxyall) 100 #define V_arpstat VNET(arpstat) 101 #define V_arp_maxhold VNET(arp_maxhold) 102 103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 104 &VNET_NAME(arpt_keep), 0, 105 "ARP entry lifetime in seconds"); 106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 107 &VNET_NAME(arp_maxtries), 0, 108 "ARP resolution attempts before returning error"); 109 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 110 &VNET_NAME(useloopback), 0, 111 "Use the loopback interface for local traffic"); 112 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 113 &VNET_NAME(arp_proxyall), 0, 114 "Enable proxy ARP for all suitable requests"); 115 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW, 116 &VNET_NAME(arpt_down), 0, 117 "Incomplete ARP entry lifetime in seconds"); 118 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW, 119 &VNET_NAME(arpstat), arpstat, 120 "ARP statistics (struct arpstat, net/if_arp.h)"); 121 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW, 122 &VNET_NAME(arp_maxhold), 0, 123 "Number of packets to hold per ARP entry"); 124 125 static void arp_init(void); 126 void arprequest(struct ifnet *, 127 struct in_addr *, struct in_addr *, u_char *); 128 static void arpintr(struct mbuf *); 129 static void arptimer(void *); 130 #ifdef INET 131 static void in_arpinput(struct mbuf *); 132 #endif 133 134 static const struct netisr_handler arp_nh = { 135 .nh_name = "arp", 136 .nh_handler = arpintr, 137 .nh_proto = NETISR_ARP, 138 .nh_policy = NETISR_POLICY_SOURCE, 139 }; 140 141 #ifdef AF_INET 142 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 143 144 /* 145 * called by in_ifscrub to remove entry from the table when 146 * the interface goes away 147 */ 148 void 149 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 150 { 151 struct sockaddr_in addr4; 152 153 bzero((void *)&addr4, sizeof(addr4)); 154 addr4.sin_len = sizeof(addr4); 155 addr4.sin_family = AF_INET; 156 addr4.sin_addr.s_addr = addr; 157 IF_AFDATA_LOCK(ifp); 158 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 159 (struct sockaddr *)&addr4); 160 IF_AFDATA_UNLOCK(ifp); 161 } 162 #endif 163 164 /* 165 * Timeout routine. Age arp_tab entries periodically. 166 */ 167 static void 168 arptimer(void *arg) 169 { 170 struct ifnet *ifp; 171 struct llentry *lle; 172 int pkts_dropped; 173 174 KASSERT(arg != NULL, ("%s: arg NULL", __func__)); 175 lle = (struct llentry *)arg; 176 ifp = lle->lle_tbl->llt_ifp; 177 CURVNET_SET(ifp->if_vnet); 178 IF_AFDATA_LOCK(ifp); 179 LLE_WLOCK(lle); 180 if (lle->la_flags & LLE_STATIC) 181 LLE_WUNLOCK(lle); 182 else { 183 if (!callout_pending(&lle->la_timer) && 184 callout_active(&lle->la_timer)) { 185 callout_stop(&lle->la_timer); 186 LLE_REMREF(lle); 187 pkts_dropped = llentry_free(lle); 188 ARPSTAT_ADD(dropped, pkts_dropped); 189 ARPSTAT_INC(timeouts); 190 } else { 191 #ifdef DIAGNOSTIC 192 struct sockaddr *l3addr = L3_ADDR(lle); 193 log(LOG_INFO, 194 "arptimer issue: %p, IPv4 address: \"%s\"\n", lle, 195 inet_ntoa( 196 ((const struct sockaddr_in *)l3addr)->sin_addr)); 197 #endif 198 LLE_WUNLOCK(lle); 199 } 200 } 201 IF_AFDATA_UNLOCK(ifp); 202 CURVNET_RESTORE(); 203 } 204 205 /* 206 * Broadcast an ARP request. Caller specifies: 207 * - arp header source ip address 208 * - arp header target ip address 209 * - arp header source ethernet address 210 */ 211 void 212 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 213 u_char *enaddr) 214 { 215 struct mbuf *m; 216 struct arphdr *ah; 217 struct sockaddr sa; 218 219 if (sip == NULL) { 220 /* XXX don't believe this can happen (or explain why) */ 221 /* 222 * The caller did not supply a source address, try to find 223 * a compatible one among those assigned to this interface. 224 */ 225 struct ifaddr *ifa; 226 227 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 228 if (!ifa->ifa_addr || 229 ifa->ifa_addr->sa_family != AF_INET) 230 continue; 231 sip = &SIN(ifa->ifa_addr)->sin_addr; 232 if (0 == ((sip->s_addr ^ tip->s_addr) & 233 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 234 break; /* found it. */ 235 } 236 if (sip == NULL) { 237 printf("%s: cannot find matching address\n", __func__); 238 return; 239 } 240 } 241 242 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 243 return; 244 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 245 2*ifp->if_data.ifi_addrlen; 246 m->m_pkthdr.len = m->m_len; 247 MH_ALIGN(m, m->m_len); 248 ah = mtod(m, struct arphdr *); 249 bzero((caddr_t)ah, m->m_len); 250 #ifdef MAC 251 mac_netinet_arp_send(ifp, m); 252 #endif 253 ah->ar_pro = htons(ETHERTYPE_IP); 254 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 255 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 256 ah->ar_op = htons(ARPOP_REQUEST); 257 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 258 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 259 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 260 sa.sa_family = AF_ARP; 261 sa.sa_len = 2; 262 m->m_flags |= M_BCAST; 263 (*ifp->if_output)(ifp, m, &sa, NULL); 264 ARPSTAT_INC(txrequests); 265 } 266 267 /* 268 * Resolve an IP address into an ethernet address. 269 * On input: 270 * ifp is the interface we use 271 * rt0 is the route to the final destination (possibly useless) 272 * m is the mbuf. May be NULL if we don't have a packet. 273 * dst is the next hop, 274 * desten is where we want the address. 275 * 276 * On success, desten is filled in and the function returns 0; 277 * If the packet must be held pending resolution, we return EWOULDBLOCK 278 * On other errors, we return the corresponding error code. 279 * Note that m_freem() handles NULL. 280 */ 281 int 282 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 283 struct sockaddr *dst, u_char *desten, struct llentry **lle) 284 { 285 struct llentry *la = 0; 286 u_int flags = 0; 287 struct mbuf *curr = NULL; 288 struct mbuf *next = NULL; 289 int error, renew; 290 291 *lle = NULL; 292 if (m != NULL) { 293 if (m->m_flags & M_BCAST) { 294 /* broadcast */ 295 (void)memcpy(desten, 296 ifp->if_broadcastaddr, ifp->if_addrlen); 297 return (0); 298 } 299 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 300 /* multicast */ 301 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 302 return (0); 303 } 304 } 305 retry: 306 IF_AFDATA_RLOCK(ifp); 307 la = lla_lookup(LLTABLE(ifp), flags, dst); 308 IF_AFDATA_RUNLOCK(ifp); 309 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 310 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 311 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 312 IF_AFDATA_WLOCK(ifp); 313 la = lla_lookup(LLTABLE(ifp), flags, dst); 314 IF_AFDATA_WUNLOCK(ifp); 315 } 316 if (la == NULL) { 317 if (flags & LLE_CREATE) 318 log(LOG_DEBUG, 319 "arpresolve: can't allocate llinfo for %s\n", 320 inet_ntoa(SIN(dst)->sin_addr)); 321 m_freem(m); 322 return (EINVAL); 323 } 324 325 if ((la->la_flags & LLE_VALID) && 326 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 327 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 328 /* 329 * If entry has an expiry time and it is approaching, 330 * see if we need to send an ARP request within this 331 * arpt_down interval. 332 */ 333 if (!(la->la_flags & LLE_STATIC) && 334 time_uptime + la->la_preempt > la->la_expire) { 335 arprequest(ifp, NULL, 336 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 337 338 la->la_preempt--; 339 } 340 341 *lle = la; 342 error = 0; 343 goto done; 344 } 345 346 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 347 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 348 inet_ntoa(SIN(dst)->sin_addr)); 349 m_freem(m); 350 error = EINVAL; 351 goto done; 352 } 353 354 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 355 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 356 flags |= LLE_EXCLUSIVE; 357 LLE_RUNLOCK(la); 358 goto retry; 359 } 360 /* 361 * There is an arptab entry, but no ethernet address 362 * response yet. Add the mbuf to the list, dropping 363 * the oldest packet if we have exceeded the system 364 * setting. 365 */ 366 if (m != NULL) { 367 if (la->la_numheld >= V_arp_maxhold) { 368 if (la->la_hold != NULL) { 369 next = la->la_hold->m_nextpkt; 370 m_freem(la->la_hold); 371 la->la_hold = next; 372 la->la_numheld--; 373 ARPSTAT_INC(dropped); 374 } 375 } 376 if (la->la_hold != NULL) { 377 curr = la->la_hold; 378 while (curr->m_nextpkt != NULL) 379 curr = curr->m_nextpkt; 380 curr->m_nextpkt = m; 381 } else 382 la->la_hold = m; 383 la->la_numheld++; 384 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 385 flags &= ~LLE_EXCLUSIVE; 386 LLE_DOWNGRADE(la); 387 } 388 389 } 390 /* 391 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 392 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 393 * if we have already sent arp_maxtries ARP requests. Retransmit the 394 * ARP request, but not faster than one request per second. 395 */ 396 if (la->la_asked < V_arp_maxtries) 397 error = EWOULDBLOCK; /* First request. */ 398 else 399 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 400 EHOSTUNREACH : EHOSTDOWN; 401 402 if (renew) { 403 int canceled; 404 405 LLE_ADDREF(la); 406 la->la_expire = time_uptime; 407 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 408 arptimer, la); 409 if (canceled) 410 LLE_REMREF(la); 411 la->la_asked++; 412 LLE_WUNLOCK(la); 413 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 414 IF_LLADDR(ifp)); 415 return (error); 416 } 417 done: 418 if (flags & LLE_EXCLUSIVE) 419 LLE_WUNLOCK(la); 420 else 421 LLE_RUNLOCK(la); 422 return (error); 423 } 424 425 /* 426 * Common length and type checks are done here, 427 * then the protocol-specific routine is called. 428 */ 429 static void 430 arpintr(struct mbuf *m) 431 { 432 struct arphdr *ar; 433 434 if (m->m_len < sizeof(struct arphdr) && 435 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 436 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 437 return; 438 } 439 ar = mtod(m, struct arphdr *); 440 441 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 442 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 443 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 444 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 445 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 446 (unsigned char *)&ar->ar_hrd, ""); 447 m_freem(m); 448 return; 449 } 450 451 if (m->m_len < arphdr_len(ar)) { 452 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 453 log(LOG_ERR, "arp: runt packet\n"); 454 m_freem(m); 455 return; 456 } 457 ar = mtod(m, struct arphdr *); 458 } 459 460 ARPSTAT_INC(received); 461 switch (ntohs(ar->ar_pro)) { 462 #ifdef INET 463 case ETHERTYPE_IP: 464 in_arpinput(m); 465 return; 466 #endif 467 } 468 m_freem(m); 469 } 470 471 #ifdef INET 472 /* 473 * ARP for Internet protocols on 10 Mb/s Ethernet. 474 * Algorithm is that given in RFC 826. 475 * In addition, a sanity check is performed on the sender 476 * protocol address, to catch impersonators. 477 * We no longer handle negotiations for use of trailer protocol: 478 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 479 * along with IP replies if we wanted trailers sent to us, 480 * and also sent them in response to IP replies. 481 * This allowed either end to announce the desire to receive 482 * trailer packets. 483 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 484 * but formerly didn't normally send requests. 485 */ 486 static int log_arp_wrong_iface = 1; 487 static int log_arp_movements = 1; 488 static int log_arp_permanent_modify = 1; 489 490 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 491 &log_arp_wrong_iface, 0, 492 "log arp packets arriving on the wrong interface"); 493 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 494 &log_arp_movements, 0, 495 "log arp replies from MACs different than the one in the cache"); 496 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 497 &log_arp_permanent_modify, 0, 498 "log arp replies from MACs different than the one in the permanent arp entry"); 499 500 501 static void 502 in_arpinput(struct mbuf *m) 503 { 504 struct arphdr *ah; 505 struct ifnet *ifp = m->m_pkthdr.rcvif; 506 struct llentry *la = NULL; 507 struct rtentry *rt; 508 struct ifaddr *ifa; 509 struct in_ifaddr *ia; 510 struct sockaddr sa; 511 struct in_addr isaddr, itaddr, myaddr; 512 u_int8_t *enaddr = NULL; 513 int op, flags; 514 int req_len; 515 int bridged = 0, is_bridge = 0; 516 int carp_match = 0; 517 struct sockaddr_in sin; 518 sin.sin_len = sizeof(struct sockaddr_in); 519 sin.sin_family = AF_INET; 520 sin.sin_addr.s_addr = 0; 521 522 if (ifp->if_bridge) 523 bridged = 1; 524 if (ifp->if_type == IFT_BRIDGE) 525 is_bridge = 1; 526 527 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 528 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 529 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 530 return; 531 } 532 533 ah = mtod(m, struct arphdr *); 534 op = ntohs(ah->ar_op); 535 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 536 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 537 538 if (op == ARPOP_REPLY) 539 ARPSTAT_INC(rxreplies); 540 541 /* 542 * For a bridge, we want to check the address irrespective 543 * of the receive interface. (This will change slightly 544 * when we have clusters of interfaces). 545 * If the interface does not match, but the recieving interface 546 * is part of carp, we call carp_iamatch to see if this is a 547 * request for the virtual host ip. 548 * XXX: This is really ugly! 549 */ 550 IN_IFADDR_RLOCK(); 551 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 552 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 553 ia->ia_ifp == ifp) && 554 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 555 ifa_ref(&ia->ia_ifa); 556 IN_IFADDR_RUNLOCK(); 557 goto match; 558 } 559 if (ifp->if_carp != NULL && 560 (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) && 561 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 562 carp_match = 1; 563 ifa_ref(&ia->ia_ifa); 564 IN_IFADDR_RUNLOCK(); 565 goto match; 566 } 567 } 568 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 569 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 570 ia->ia_ifp == ifp) && 571 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 572 ifa_ref(&ia->ia_ifa); 573 IN_IFADDR_RUNLOCK(); 574 goto match; 575 } 576 577 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 578 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 579 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 580 addr == ia->ia_addr.sin_addr.s_addr) 581 /* 582 * Check the case when bridge shares its MAC address with 583 * some of its children, so packets are claimed by bridge 584 * itself (bridge_input() does it first), but they are really 585 * meant to be destined to the bridge member. 586 */ 587 if (is_bridge) { 588 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 589 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 590 ifa_ref(&ia->ia_ifa); 591 ifp = ia->ia_ifp; 592 IN_IFADDR_RUNLOCK(); 593 goto match; 594 } 595 } 596 } 597 #undef BDG_MEMBER_MATCHES_ARP 598 IN_IFADDR_RUNLOCK(); 599 600 /* 601 * No match, use the first inet address on the receive interface 602 * as a dummy address for the rest of the function. 603 */ 604 IF_ADDR_LOCK(ifp); 605 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 606 if (ifa->ifa_addr->sa_family == AF_INET) { 607 ia = ifatoia(ifa); 608 ifa_ref(ifa); 609 IF_ADDR_UNLOCK(ifp); 610 goto match; 611 } 612 IF_ADDR_UNLOCK(ifp); 613 614 /* 615 * If bridging, fall back to using any inet address. 616 */ 617 IN_IFADDR_RLOCK(); 618 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 619 IN_IFADDR_RUNLOCK(); 620 goto drop; 621 } 622 ifa_ref(&ia->ia_ifa); 623 IN_IFADDR_RUNLOCK(); 624 match: 625 if (!enaddr) 626 enaddr = (u_int8_t *)IF_LLADDR(ifp); 627 myaddr = ia->ia_addr.sin_addr; 628 ifa_free(&ia->ia_ifa); 629 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 630 goto drop; /* it's from me, ignore it. */ 631 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 632 log(LOG_ERR, 633 "arp: link address is broadcast for IP address %s!\n", 634 inet_ntoa(isaddr)); 635 goto drop; 636 } 637 /* 638 * Warn if another host is using the same IP address, but only if the 639 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 640 * case we suppress the warning to avoid false positive complaints of 641 * potential misconfiguration. 642 */ 643 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 644 log(LOG_ERR, 645 "arp: %*D is using my IP address %s on %s!\n", 646 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 647 inet_ntoa(isaddr), ifp->if_xname); 648 itaddr = myaddr; 649 ARPSTAT_INC(dupips); 650 goto reply; 651 } 652 if (ifp->if_flags & IFF_STATICARP) 653 goto reply; 654 655 bzero(&sin, sizeof(sin)); 656 sin.sin_len = sizeof(struct sockaddr_in); 657 sin.sin_family = AF_INET; 658 sin.sin_addr = isaddr; 659 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 660 flags |= LLE_EXCLUSIVE; 661 IF_AFDATA_LOCK(ifp); 662 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 663 IF_AFDATA_UNLOCK(ifp); 664 if (la != NULL) { 665 /* the following is not an error when doing bridging */ 666 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) { 667 if (log_arp_wrong_iface) 668 log(LOG_ERR, "arp: %s is on %s " 669 "but got reply from %*D on %s\n", 670 inet_ntoa(isaddr), 671 la->lle_tbl->llt_ifp->if_xname, 672 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 673 ifp->if_xname); 674 LLE_WUNLOCK(la); 675 goto reply; 676 } 677 if ((la->la_flags & LLE_VALID) && 678 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 679 if (la->la_flags & LLE_STATIC) { 680 LLE_WUNLOCK(la); 681 log(LOG_ERR, 682 "arp: %*D attempts to modify permanent " 683 "entry for %s on %s\n", 684 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 685 inet_ntoa(isaddr), ifp->if_xname); 686 goto reply; 687 } 688 if (log_arp_movements) { 689 log(LOG_INFO, "arp: %s moved from %*D " 690 "to %*D on %s\n", 691 inet_ntoa(isaddr), 692 ifp->if_addrlen, 693 (u_char *)&la->ll_addr, ":", 694 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 695 ifp->if_xname); 696 } 697 } 698 699 if (ifp->if_addrlen != ah->ar_hln) { 700 LLE_WUNLOCK(la); 701 log(LOG_WARNING, 702 "arp from %*D: addr len: new %d, i/f %d (ignored)", 703 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 704 ah->ar_hln, ifp->if_addrlen); 705 goto reply; 706 } 707 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 708 la->la_flags |= LLE_VALID; 709 710 EVENTHANDLER_INVOKE(arp_update_event, la); 711 712 if (!(la->la_flags & LLE_STATIC)) { 713 int canceled; 714 715 LLE_ADDREF(la); 716 la->la_expire = time_uptime + V_arpt_keep; 717 canceled = callout_reset(&la->la_timer, 718 hz * V_arpt_keep, arptimer, la); 719 if (canceled) 720 LLE_REMREF(la); 721 } 722 la->la_asked = 0; 723 la->la_preempt = V_arp_maxtries; 724 /* 725 * The packets are all freed within the call to the output 726 * routine. 727 * 728 * NB: The lock MUST be released before the call to the 729 * output routine. 730 */ 731 if (la->la_hold != NULL) { 732 struct mbuf *m_hold, *m_hold_next; 733 734 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 735 LLE_WUNLOCK(la); 736 for (m_hold = la->la_hold, la->la_hold = NULL; 737 m_hold != NULL; m_hold = m_hold_next) { 738 m_hold_next = m_hold->m_nextpkt; 739 m_hold->m_nextpkt = NULL; 740 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 741 } 742 } else 743 LLE_WUNLOCK(la); 744 la->la_hold = NULL; 745 la->la_numheld = 0; 746 } /* end of FIB loop */ 747 reply: 748 if (op != ARPOP_REQUEST) 749 goto drop; 750 ARPSTAT_INC(rxrequests); 751 752 if (itaddr.s_addr == myaddr.s_addr) { 753 /* Shortcut.. the receiving interface is the target. */ 754 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 755 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 756 } else { 757 struct llentry *lle = NULL; 758 759 sin.sin_addr = itaddr; 760 IF_AFDATA_LOCK(ifp); 761 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 762 IF_AFDATA_UNLOCK(ifp); 763 764 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 765 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 766 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 767 LLE_RUNLOCK(lle); 768 } else { 769 770 if (lle != NULL) 771 LLE_RUNLOCK(lle); 772 773 if (!V_arp_proxyall) 774 goto drop; 775 776 sin.sin_addr = itaddr; 777 /* XXX MRT use table 0 for arp reply */ 778 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 779 if (!rt) 780 goto drop; 781 782 /* 783 * Don't send proxies for nodes on the same interface 784 * as this one came out of, or we'll get into a fight 785 * over who claims what Ether address. 786 */ 787 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 788 RTFREE_LOCKED(rt); 789 goto drop; 790 } 791 RTFREE_LOCKED(rt); 792 793 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 794 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 795 796 /* 797 * Also check that the node which sent the ARP packet 798 * is on the the interface we expect it to be on. This 799 * avoids ARP chaos if an interface is connected to the 800 * wrong network. 801 */ 802 sin.sin_addr = isaddr; 803 804 /* XXX MRT use table 0 for arp checks */ 805 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 806 if (!rt) 807 goto drop; 808 if (rt->rt_ifp != ifp) { 809 log(LOG_INFO, "arp_proxy: ignoring request" 810 " from %s via %s, expecting %s\n", 811 inet_ntoa(isaddr), ifp->if_xname, 812 rt->rt_ifp->if_xname); 813 RTFREE_LOCKED(rt); 814 goto drop; 815 } 816 RTFREE_LOCKED(rt); 817 818 #ifdef DEBUG_PROXY 819 printf("arp: proxying for %s\n", 820 inet_ntoa(itaddr)); 821 #endif 822 } 823 } 824 825 if (itaddr.s_addr == myaddr.s_addr && 826 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 827 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 828 #ifdef DEBUG_LINKLOCAL 829 printf("arp: sending reply for link-local addr %s\n", 830 inet_ntoa(itaddr)); 831 #endif 832 m->m_flags |= M_BCAST; 833 m->m_flags &= ~M_MCAST; 834 } else { 835 /* default behaviour; never reply by broadcast. */ 836 m->m_flags &= ~(M_BCAST|M_MCAST); 837 } 838 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 839 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 840 ah->ar_op = htons(ARPOP_REPLY); 841 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 842 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 843 m->m_pkthdr.len = m->m_len; 844 sa.sa_family = AF_ARP; 845 sa.sa_len = 2; 846 (*ifp->if_output)(ifp, m, &sa, NULL); 847 ARPSTAT_INC(txreplies); 848 return; 849 850 drop: 851 m_freem(m); 852 } 853 #endif 854 855 void 856 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 857 { 858 struct llentry *lle; 859 860 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 861 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 862 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 863 /* 864 * interface address is considered static entry 865 * because the output of the arp utility shows 866 * that L2 entry as permanent 867 */ 868 IF_AFDATA_LOCK(ifp); 869 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 870 (struct sockaddr *)IA_SIN(ifa)); 871 IF_AFDATA_UNLOCK(ifp); 872 if (lle == NULL) 873 log(LOG_INFO, "arp_ifinit: cannot create arp " 874 "entry for interface address\n"); 875 else 876 LLE_RUNLOCK(lle); 877 } 878 ifa->ifa_rtrequest = NULL; 879 } 880 881 void 882 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 883 { 884 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 885 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 886 &IA_SIN(ifa)->sin_addr, enaddr); 887 ifa->ifa_rtrequest = NULL; 888 } 889 890 static void 891 arp_init(void) 892 { 893 894 netisr_register(&arp_nh); 895 } 896 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 897