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 #ifdef INET 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 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 81 static 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 static void arpintr(struct mbuf *); 127 static void arptimer(void *); 128 #ifdef INET 129 static void in_arpinput(struct mbuf *); 130 #endif 131 132 static const struct netisr_handler arp_nh = { 133 .nh_name = "arp", 134 .nh_handler = arpintr, 135 .nh_proto = NETISR_ARP, 136 .nh_policy = NETISR_POLICY_SOURCE, 137 }; 138 139 #ifdef AF_INET 140 /* 141 * called by in_ifscrub to remove entry from the table when 142 * the interface goes away 143 */ 144 void 145 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 146 { 147 struct sockaddr_in addr4; 148 149 bzero((void *)&addr4, sizeof(addr4)); 150 addr4.sin_len = sizeof(addr4); 151 addr4.sin_family = AF_INET; 152 addr4.sin_addr.s_addr = addr; 153 IF_AFDATA_LOCK(ifp); 154 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 155 (struct sockaddr *)&addr4); 156 IF_AFDATA_UNLOCK(ifp); 157 } 158 #endif 159 160 /* 161 * Timeout routine. Age arp_tab entries periodically. 162 */ 163 static void 164 arptimer(void *arg) 165 { 166 struct ifnet *ifp; 167 struct llentry *lle; 168 int pkts_dropped; 169 170 KASSERT(arg != NULL, ("%s: arg NULL", __func__)); 171 lle = (struct llentry *)arg; 172 ifp = lle->lle_tbl->llt_ifp; 173 CURVNET_SET(ifp->if_vnet); 174 IF_AFDATA_LOCK(ifp); 175 LLE_WLOCK(lle); 176 if (lle->la_flags & LLE_STATIC) 177 LLE_WUNLOCK(lle); 178 else { 179 if (!callout_pending(&lle->la_timer) && 180 callout_active(&lle->la_timer)) { 181 callout_stop(&lle->la_timer); 182 LLE_REMREF(lle); 183 184 if (lle->la_flags != LLE_DELETED) { 185 int evt; 186 187 if (lle->la_flags & LLE_VALID) 188 evt = LLENTRY_EXPIRED; 189 else 190 evt = LLENTRY_TIMEDOUT; 191 EVENTHANDLER_INVOKE(lle_event, lle, evt); 192 } 193 194 pkts_dropped = llentry_free(lle); 195 ARPSTAT_ADD(dropped, pkts_dropped); 196 ARPSTAT_INC(timeouts); 197 } else { 198 #ifdef DIAGNOSTIC 199 struct sockaddr *l3addr = L3_ADDR(lle); 200 log(LOG_INFO, 201 "arptimer issue: %p, IPv4 address: \"%s\"\n", lle, 202 inet_ntoa( 203 ((const struct sockaddr_in *)l3addr)->sin_addr)); 204 #endif 205 LLE_WUNLOCK(lle); 206 } 207 } 208 IF_AFDATA_UNLOCK(ifp); 209 CURVNET_RESTORE(); 210 } 211 212 /* 213 * Broadcast an ARP request. Caller specifies: 214 * - arp header source ip address 215 * - arp header target ip address 216 * - arp header source ethernet address 217 */ 218 void 219 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 220 u_char *enaddr) 221 { 222 struct mbuf *m; 223 struct arphdr *ah; 224 struct sockaddr sa; 225 u_char *carpaddr = NULL; 226 227 if (sip == NULL) { 228 /* 229 * The caller did not supply a source address, try to find 230 * a compatible one among those assigned to this interface. 231 */ 232 struct ifaddr *ifa; 233 234 IF_ADDR_RLOCK(ifp); 235 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 236 if (ifa->ifa_addr->sa_family != AF_INET) 237 continue; 238 239 if (ifa->ifa_carp) { 240 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 241 continue; 242 sip = &IA_SIN(ifa)->sin_addr; 243 } else { 244 carpaddr = NULL; 245 sip = &IA_SIN(ifa)->sin_addr; 246 } 247 248 if (0 == ((sip->s_addr ^ tip->s_addr) & 249 IA_MASKSIN(ifa)->sin_addr.s_addr)) 250 break; /* found it. */ 251 } 252 IF_ADDR_RUNLOCK(ifp); 253 if (sip == NULL) { 254 printf("%s: cannot find matching address\n", __func__); 255 return; 256 } 257 } 258 if (enaddr == NULL) 259 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 260 261 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 262 return; 263 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 264 2*ifp->if_data.ifi_addrlen; 265 m->m_pkthdr.len = m->m_len; 266 MH_ALIGN(m, m->m_len); 267 ah = mtod(m, struct arphdr *); 268 bzero((caddr_t)ah, m->m_len); 269 #ifdef MAC 270 mac_netinet_arp_send(ifp, m); 271 #endif 272 ah->ar_pro = htons(ETHERTYPE_IP); 273 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 274 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 275 ah->ar_op = htons(ARPOP_REQUEST); 276 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 277 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 278 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 279 sa.sa_family = AF_ARP; 280 sa.sa_len = 2; 281 m->m_flags |= M_BCAST; 282 (*ifp->if_output)(ifp, m, &sa, NULL); 283 ARPSTAT_INC(txrequests); 284 } 285 286 /* 287 * Resolve an IP address into an ethernet address. 288 * On input: 289 * ifp is the interface we use 290 * rt0 is the route to the final destination (possibly useless) 291 * m is the mbuf. May be NULL if we don't have a packet. 292 * dst is the next hop, 293 * desten is where we want the address. 294 * 295 * On success, desten is filled in and the function returns 0; 296 * If the packet must be held pending resolution, we return EWOULDBLOCK 297 * On other errors, we return the corresponding error code. 298 * Note that m_freem() handles NULL. 299 */ 300 int 301 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 302 struct sockaddr *dst, u_char *desten, struct llentry **lle) 303 { 304 struct llentry *la = 0; 305 u_int flags = 0; 306 struct mbuf *curr = NULL; 307 struct mbuf *next = NULL; 308 int error, renew; 309 310 *lle = NULL; 311 if (m != NULL) { 312 if (m->m_flags & M_BCAST) { 313 /* broadcast */ 314 (void)memcpy(desten, 315 ifp->if_broadcastaddr, ifp->if_addrlen); 316 return (0); 317 } 318 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 319 /* multicast */ 320 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 321 return (0); 322 } 323 } 324 retry: 325 IF_AFDATA_RLOCK(ifp); 326 la = lla_lookup(LLTABLE(ifp), flags, dst); 327 IF_AFDATA_RUNLOCK(ifp); 328 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 329 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 330 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 331 IF_AFDATA_WLOCK(ifp); 332 la = lla_lookup(LLTABLE(ifp), flags, dst); 333 IF_AFDATA_WUNLOCK(ifp); 334 } 335 if (la == NULL) { 336 if (flags & LLE_CREATE) 337 log(LOG_DEBUG, 338 "arpresolve: can't allocate llinfo for %s\n", 339 inet_ntoa(SIN(dst)->sin_addr)); 340 m_freem(m); 341 return (EINVAL); 342 } 343 344 if ((la->la_flags & LLE_VALID) && 345 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 346 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 347 /* 348 * If entry has an expiry time and it is approaching, 349 * see if we need to send an ARP request within this 350 * arpt_down interval. 351 */ 352 if (!(la->la_flags & LLE_STATIC) && 353 time_uptime + la->la_preempt > la->la_expire) { 354 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 355 la->la_preempt--; 356 } 357 358 *lle = la; 359 error = 0; 360 goto done; 361 } 362 363 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 364 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 365 inet_ntoa(SIN(dst)->sin_addr)); 366 m_freem(m); 367 error = EINVAL; 368 goto done; 369 } 370 371 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 372 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 373 flags |= LLE_EXCLUSIVE; 374 LLE_RUNLOCK(la); 375 goto retry; 376 } 377 /* 378 * There is an arptab entry, but no ethernet address 379 * response yet. Add the mbuf to the list, dropping 380 * the oldest packet if we have exceeded the system 381 * setting. 382 */ 383 if (m != NULL) { 384 if (la->la_numheld >= V_arp_maxhold) { 385 if (la->la_hold != NULL) { 386 next = la->la_hold->m_nextpkt; 387 m_freem(la->la_hold); 388 la->la_hold = next; 389 la->la_numheld--; 390 ARPSTAT_INC(dropped); 391 } 392 } 393 if (la->la_hold != NULL) { 394 curr = la->la_hold; 395 while (curr->m_nextpkt != NULL) 396 curr = curr->m_nextpkt; 397 curr->m_nextpkt = m; 398 } else 399 la->la_hold = m; 400 la->la_numheld++; 401 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 402 flags &= ~LLE_EXCLUSIVE; 403 LLE_DOWNGRADE(la); 404 } 405 406 } 407 /* 408 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 409 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 410 * if we have already sent arp_maxtries ARP requests. Retransmit the 411 * ARP request, but not faster than one request per second. 412 */ 413 if (la->la_asked < V_arp_maxtries) 414 error = EWOULDBLOCK; /* First request. */ 415 else 416 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 417 EHOSTUNREACH : EHOSTDOWN; 418 419 if (renew) { 420 int canceled; 421 422 LLE_ADDREF(la); 423 la->la_expire = time_uptime; 424 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 425 arptimer, la); 426 if (canceled) 427 LLE_REMREF(la); 428 la->la_asked++; 429 LLE_WUNLOCK(la); 430 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 431 return (error); 432 } 433 done: 434 if (flags & LLE_EXCLUSIVE) 435 LLE_WUNLOCK(la); 436 else 437 LLE_RUNLOCK(la); 438 return (error); 439 } 440 441 /* 442 * Common length and type checks are done here, 443 * then the protocol-specific routine is called. 444 */ 445 static void 446 arpintr(struct mbuf *m) 447 { 448 struct arphdr *ar; 449 450 if (m->m_len < sizeof(struct arphdr) && 451 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 452 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 453 return; 454 } 455 ar = mtod(m, struct arphdr *); 456 457 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 458 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 459 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 460 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 461 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 462 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 463 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 464 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 465 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 466 m_freem(m); 467 return; 468 } 469 470 if (m->m_len < arphdr_len(ar)) { 471 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 472 log(LOG_NOTICE, "arp: runt packet\n"); 473 m_freem(m); 474 return; 475 } 476 ar = mtod(m, struct arphdr *); 477 } 478 479 ARPSTAT_INC(received); 480 switch (ntohs(ar->ar_pro)) { 481 #ifdef INET 482 case ETHERTYPE_IP: 483 in_arpinput(m); 484 return; 485 #endif 486 } 487 m_freem(m); 488 } 489 490 #ifdef INET 491 /* 492 * ARP for Internet protocols on 10 Mb/s Ethernet. 493 * Algorithm is that given in RFC 826. 494 * In addition, a sanity check is performed on the sender 495 * protocol address, to catch impersonators. 496 * We no longer handle negotiations for use of trailer protocol: 497 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 498 * along with IP replies if we wanted trailers sent to us, 499 * and also sent them in response to IP replies. 500 * This allowed either end to announce the desire to receive 501 * trailer packets. 502 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 503 * but formerly didn't normally send requests. 504 */ 505 static int log_arp_wrong_iface = 1; 506 static int log_arp_movements = 1; 507 static int log_arp_permanent_modify = 1; 508 509 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 510 &log_arp_wrong_iface, 0, 511 "log arp packets arriving on the wrong interface"); 512 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 513 &log_arp_movements, 0, 514 "log arp replies from MACs different than the one in the cache"); 515 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 516 &log_arp_permanent_modify, 0, 517 "log arp replies from MACs different than the one in the permanent arp entry"); 518 519 520 static void 521 in_arpinput(struct mbuf *m) 522 { 523 struct arphdr *ah; 524 struct ifnet *ifp = m->m_pkthdr.rcvif; 525 struct llentry *la = NULL; 526 struct rtentry *rt; 527 struct ifaddr *ifa; 528 struct in_ifaddr *ia; 529 struct sockaddr sa; 530 struct in_addr isaddr, itaddr, myaddr; 531 u_int8_t *enaddr = NULL; 532 int op, flags; 533 int req_len; 534 int bridged = 0, is_bridge = 0; 535 int carped; 536 struct sockaddr_in sin; 537 sin.sin_len = sizeof(struct sockaddr_in); 538 sin.sin_family = AF_INET; 539 sin.sin_addr.s_addr = 0; 540 541 if (ifp->if_bridge) 542 bridged = 1; 543 if (ifp->if_type == IFT_BRIDGE) 544 is_bridge = 1; 545 546 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 547 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 548 log(LOG_NOTICE, "in_arp: runt packet -- m_pullup failed\n"); 549 return; 550 } 551 552 ah = mtod(m, struct arphdr *); 553 /* 554 * ARP is only for IPv4 so we can reject packets with 555 * a protocol length not equal to an IPv4 address. 556 */ 557 if (ah->ar_pln != sizeof(struct in_addr)) { 558 log(LOG_NOTICE, "in_arp: requested protocol length != %zu\n", 559 sizeof(struct in_addr)); 560 return; 561 } 562 563 if (ETHER_IS_MULTICAST(ar_sha(ah))) { 564 log(LOG_NOTICE, "in_arp: %*D is multicast\n", 565 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 566 return; 567 } 568 569 op = ntohs(ah->ar_op); 570 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 571 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 572 573 if (op == ARPOP_REPLY) 574 ARPSTAT_INC(rxreplies); 575 576 /* 577 * For a bridge, we want to check the address irrespective 578 * of the receive interface. (This will change slightly 579 * when we have clusters of interfaces). 580 */ 581 IN_IFADDR_RLOCK(); 582 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 583 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 584 ia->ia_ifp == ifp) && 585 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 586 (ia->ia_ifa.ifa_carp == NULL || 587 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 588 ifa_ref(&ia->ia_ifa); 589 IN_IFADDR_RUNLOCK(); 590 goto match; 591 } 592 } 593 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 594 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 595 ia->ia_ifp == ifp) && 596 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 597 ifa_ref(&ia->ia_ifa); 598 IN_IFADDR_RUNLOCK(); 599 goto match; 600 } 601 602 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 603 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 604 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 605 addr == ia->ia_addr.sin_addr.s_addr) 606 /* 607 * Check the case when bridge shares its MAC address with 608 * some of its children, so packets are claimed by bridge 609 * itself (bridge_input() does it first), but they are really 610 * meant to be destined to the bridge member. 611 */ 612 if (is_bridge) { 613 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 614 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 615 ifa_ref(&ia->ia_ifa); 616 ifp = ia->ia_ifp; 617 IN_IFADDR_RUNLOCK(); 618 goto match; 619 } 620 } 621 } 622 #undef BDG_MEMBER_MATCHES_ARP 623 IN_IFADDR_RUNLOCK(); 624 625 /* 626 * No match, use the first inet address on the receive interface 627 * as a dummy address for the rest of the function. 628 */ 629 IF_ADDR_RLOCK(ifp); 630 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 631 if (ifa->ifa_addr->sa_family == AF_INET && 632 (ifa->ifa_carp == NULL || 633 (*carp_iamatch_p)(ifa, &enaddr))) { 634 ia = ifatoia(ifa); 635 ifa_ref(ifa); 636 IF_ADDR_RUNLOCK(ifp); 637 goto match; 638 } 639 IF_ADDR_RUNLOCK(ifp); 640 641 /* 642 * If bridging, fall back to using any inet address. 643 */ 644 IN_IFADDR_RLOCK(); 645 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 646 IN_IFADDR_RUNLOCK(); 647 goto drop; 648 } 649 ifa_ref(&ia->ia_ifa); 650 IN_IFADDR_RUNLOCK(); 651 match: 652 if (!enaddr) 653 enaddr = (u_int8_t *)IF_LLADDR(ifp); 654 carped = (ia->ia_ifa.ifa_carp != NULL); 655 myaddr = ia->ia_addr.sin_addr; 656 ifa_free(&ia->ia_ifa); 657 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 658 goto drop; /* it's from me, ignore it. */ 659 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 660 log(LOG_NOTICE, 661 "arp: link address is broadcast for IP address %s!\n", 662 inet_ntoa(isaddr)); 663 goto drop; 664 } 665 /* 666 * Warn if another host is using the same IP address, but only if the 667 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 668 * case we suppress the warning to avoid false positive complaints of 669 * potential misconfiguration. 670 */ 671 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 672 myaddr.s_addr != 0) { 673 log(LOG_ERR, "arp: %*D is using my IP address %s on %s!\n", 674 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 675 inet_ntoa(isaddr), ifp->if_xname); 676 itaddr = myaddr; 677 ARPSTAT_INC(dupips); 678 goto reply; 679 } 680 if (ifp->if_flags & IFF_STATICARP) 681 goto reply; 682 683 bzero(&sin, sizeof(sin)); 684 sin.sin_len = sizeof(struct sockaddr_in); 685 sin.sin_family = AF_INET; 686 sin.sin_addr = isaddr; 687 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 688 flags |= LLE_EXCLUSIVE; 689 IF_AFDATA_LOCK(ifp); 690 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 691 IF_AFDATA_UNLOCK(ifp); 692 if (la != NULL) { 693 /* the following is not an error when doing bridging */ 694 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 695 if (log_arp_wrong_iface) 696 log(LOG_WARNING, "arp: %s is on %s " 697 "but got reply from %*D on %s\n", 698 inet_ntoa(isaddr), 699 la->lle_tbl->llt_ifp->if_xname, 700 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 701 ifp->if_xname); 702 LLE_WUNLOCK(la); 703 goto reply; 704 } 705 if ((la->la_flags & LLE_VALID) && 706 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 707 if (la->la_flags & LLE_STATIC) { 708 LLE_WUNLOCK(la); 709 if (log_arp_permanent_modify) 710 log(LOG_ERR, 711 "arp: %*D attempts to modify " 712 "permanent entry for %s on %s\n", 713 ifp->if_addrlen, 714 (u_char *)ar_sha(ah), ":", 715 inet_ntoa(isaddr), ifp->if_xname); 716 goto reply; 717 } 718 if (log_arp_movements) { 719 log(LOG_INFO, "arp: %s moved from %*D " 720 "to %*D on %s\n", 721 inet_ntoa(isaddr), 722 ifp->if_addrlen, 723 (u_char *)&la->ll_addr, ":", 724 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 725 ifp->if_xname); 726 } 727 } 728 729 if (ifp->if_addrlen != ah->ar_hln) { 730 LLE_WUNLOCK(la); 731 log(LOG_WARNING, "arp from %*D: addr len: new %d, " 732 "i/f %d (ignored)\n", ifp->if_addrlen, 733 (u_char *) ar_sha(ah), ":", ah->ar_hln, 734 ifp->if_addrlen); 735 goto drop; 736 } 737 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 738 la->la_flags |= LLE_VALID; 739 740 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 741 742 if (!(la->la_flags & LLE_STATIC)) { 743 int canceled; 744 745 LLE_ADDREF(la); 746 la->la_expire = time_uptime + V_arpt_keep; 747 canceled = callout_reset(&la->la_timer, 748 hz * V_arpt_keep, arptimer, la); 749 if (canceled) 750 LLE_REMREF(la); 751 } 752 la->la_asked = 0; 753 la->la_preempt = V_arp_maxtries; 754 /* 755 * The packets are all freed within the call to the output 756 * routine. 757 * 758 * NB: The lock MUST be released before the call to the 759 * output routine. 760 */ 761 if (la->la_hold != NULL) { 762 struct mbuf *m_hold, *m_hold_next; 763 764 m_hold = la->la_hold; 765 la->la_hold = NULL; 766 la->la_numheld = 0; 767 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 768 LLE_WUNLOCK(la); 769 for (; m_hold != NULL; m_hold = m_hold_next) { 770 m_hold_next = m_hold->m_nextpkt; 771 m_hold->m_nextpkt = NULL; 772 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 773 } 774 } else 775 LLE_WUNLOCK(la); 776 } 777 reply: 778 if (op != ARPOP_REQUEST) 779 goto drop; 780 ARPSTAT_INC(rxrequests); 781 782 if (itaddr.s_addr == myaddr.s_addr) { 783 /* Shortcut.. the receiving interface is the target. */ 784 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 785 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 786 } else { 787 struct llentry *lle = NULL; 788 789 sin.sin_addr = itaddr; 790 IF_AFDATA_LOCK(ifp); 791 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 792 IF_AFDATA_UNLOCK(ifp); 793 794 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 795 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 796 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 797 LLE_RUNLOCK(lle); 798 } else { 799 800 if (lle != NULL) 801 LLE_RUNLOCK(lle); 802 803 if (!V_arp_proxyall) 804 goto drop; 805 806 sin.sin_addr = itaddr; 807 /* XXX MRT use table 0 for arp reply */ 808 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 809 if (!rt) 810 goto drop; 811 812 /* 813 * Don't send proxies for nodes on the same interface 814 * as this one came out of, or we'll get into a fight 815 * over who claims what Ether address. 816 */ 817 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 818 RTFREE_LOCKED(rt); 819 goto drop; 820 } 821 RTFREE_LOCKED(rt); 822 823 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 824 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 825 826 /* 827 * Also check that the node which sent the ARP packet 828 * is on the interface we expect it to be on. This 829 * avoids ARP chaos if an interface is connected to the 830 * wrong network. 831 */ 832 sin.sin_addr = isaddr; 833 834 /* XXX MRT use table 0 for arp checks */ 835 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 836 if (!rt) 837 goto drop; 838 if (rt->rt_ifp != ifp) { 839 log(LOG_INFO, "arp_proxy: ignoring request" 840 " from %s via %s, expecting %s\n", 841 inet_ntoa(isaddr), ifp->if_xname, 842 rt->rt_ifp->if_xname); 843 RTFREE_LOCKED(rt); 844 goto drop; 845 } 846 RTFREE_LOCKED(rt); 847 848 #ifdef DEBUG_PROXY 849 printf("arp: proxying for %s\n", 850 inet_ntoa(itaddr)); 851 #endif 852 } 853 } 854 855 if (itaddr.s_addr == myaddr.s_addr && 856 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 857 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 858 #ifdef DEBUG_LINKLOCAL 859 printf("arp: sending reply for link-local addr %s\n", 860 inet_ntoa(itaddr)); 861 #endif 862 m->m_flags |= M_BCAST; 863 m->m_flags &= ~M_MCAST; 864 } else { 865 /* default behaviour; never reply by broadcast. */ 866 m->m_flags &= ~(M_BCAST|M_MCAST); 867 } 868 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 869 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 870 ah->ar_op = htons(ARPOP_REPLY); 871 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 872 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 873 m->m_pkthdr.len = m->m_len; 874 m->m_pkthdr.rcvif = NULL; 875 sa.sa_family = AF_ARP; 876 sa.sa_len = 2; 877 (*ifp->if_output)(ifp, m, &sa, NULL); 878 ARPSTAT_INC(txreplies); 879 return; 880 881 drop: 882 m_freem(m); 883 } 884 #endif 885 886 void 887 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 888 { 889 struct llentry *lle; 890 891 if (ifa->ifa_carp != NULL) 892 return; 893 894 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 895 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 896 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 897 /* 898 * interface address is considered static entry 899 * because the output of the arp utility shows 900 * that L2 entry as permanent 901 */ 902 IF_AFDATA_LOCK(ifp); 903 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 904 (struct sockaddr *)IA_SIN(ifa)); 905 IF_AFDATA_UNLOCK(ifp); 906 if (lle == NULL) 907 log(LOG_INFO, "arp_ifinit: cannot create arp " 908 "entry for interface address\n"); 909 else 910 LLE_RUNLOCK(lle); 911 } 912 ifa->ifa_rtrequest = NULL; 913 } 914 915 void 916 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 917 { 918 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 919 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 920 &IA_SIN(ifa)->sin_addr, enaddr); 921 ifa->ifa_rtrequest = NULL; 922 } 923 924 static void 925 arp_init(void) 926 { 927 928 netisr_register(&arp_nh); 929 } 930 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 931