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