Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/if_ether.c
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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: releng/9.0/sys/netinet/if_ether.c 223840 2011-07-07 11:59:51Z ae $"); 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 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 446 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 447 (unsigned char *)&ar->ar_hrd, ""); 448 m_freem(m); 449 return; 450 } 451 452 if (m->m_len < arphdr_len(ar)) { 453 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 454 log(LOG_ERR, "arp: runt packet\n"); 455 m_freem(m); 456 return; 457 } 458 ar = mtod(m, struct arphdr *); 459 } 460 461 ARPSTAT_INC(received); 462 switch (ntohs(ar->ar_pro)) { 463 #ifdef INET 464 case ETHERTYPE_IP: 465 in_arpinput(m); 466 return; 467 #endif 468 } 469 m_freem(m); 470 } 471 472 #ifdef INET 473 /* 474 * ARP for Internet protocols on 10 Mb/s Ethernet. 475 * Algorithm is that given in RFC 826. 476 * In addition, a sanity check is performed on the sender 477 * protocol address, to catch impersonators. 478 * We no longer handle negotiations for use of trailer protocol: 479 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 480 * along with IP replies if we wanted trailers sent to us, 481 * and also sent them in response to IP replies. 482 * This allowed either end to announce the desire to receive 483 * trailer packets. 484 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 485 * but formerly didn't normally send requests. 486 */ 487 static int log_arp_wrong_iface = 1; 488 static int log_arp_movements = 1; 489 static int log_arp_permanent_modify = 1; 490 491 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 492 &log_arp_wrong_iface, 0, 493 "log arp packets arriving on the wrong interface"); 494 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 495 &log_arp_movements, 0, 496 "log arp replies from MACs different than the one in the cache"); 497 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 498 &log_arp_permanent_modify, 0, 499 "log arp replies from MACs different than the one in the permanent arp entry"); 500 501 502 static void 503 in_arpinput(struct mbuf *m) 504 { 505 struct arphdr *ah; 506 struct ifnet *ifp = m->m_pkthdr.rcvif; 507 struct llentry *la = NULL; 508 struct rtentry *rt; 509 struct ifaddr *ifa; 510 struct in_ifaddr *ia; 511 struct sockaddr sa; 512 struct in_addr isaddr, itaddr, myaddr; 513 u_int8_t *enaddr = NULL; 514 int op, flags; 515 int req_len; 516 int bridged = 0, is_bridge = 0; 517 int carp_match = 0; 518 struct sockaddr_in sin; 519 sin.sin_len = sizeof(struct sockaddr_in); 520 sin.sin_family = AF_INET; 521 sin.sin_addr.s_addr = 0; 522 523 if (ifp->if_bridge) 524 bridged = 1; 525 if (ifp->if_type == IFT_BRIDGE) 526 is_bridge = 1; 527 528 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 529 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 530 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 531 return; 532 } 533 534 ah = mtod(m, struct arphdr *); 535 /* 536 * ARP is only for IPv4 so we can reject packets with 537 * a protocol length not equal to an IPv4 address. 538 */ 539 if (ah->ar_pln != sizeof(struct in_addr)) { 540 log(LOG_ERR, "in_arp: requested protocol length != %zu\n", 541 sizeof(struct in_addr)); 542 return; 543 } 544 545 if (ETHER_IS_MULTICAST(ar_sha(ah))) { 546 log(LOG_ERR, "in_arp: source hardware address is multicast."); 547 return; 548 } 549 550 op = ntohs(ah->ar_op); 551 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 552 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 553 554 if (op == ARPOP_REPLY) 555 ARPSTAT_INC(rxreplies); 556 557 /* 558 * For a bridge, we want to check the address irrespective 559 * of the receive interface. (This will change slightly 560 * when we have clusters of interfaces). 561 * If the interface does not match, but the recieving interface 562 * is part of carp, we call carp_iamatch to see if this is a 563 * request for the virtual host ip. 564 * XXX: This is really ugly! 565 */ 566 IN_IFADDR_RLOCK(); 567 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 568 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 569 ia->ia_ifp == ifp) && 570 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 571 ifa_ref(&ia->ia_ifa); 572 IN_IFADDR_RUNLOCK(); 573 goto match; 574 } 575 if (ifp->if_carp != NULL && 576 (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) && 577 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 578 carp_match = 1; 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_LOCK(ifp); 621 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 622 if (ifa->ifa_addr->sa_family == AF_INET) { 623 ia = ifatoia(ifa); 624 ifa_ref(ifa); 625 IF_ADDR_UNLOCK(ifp); 626 goto match; 627 } 628 IF_ADDR_UNLOCK(ifp); 629 630 /* 631 * If bridging, fall back to using any inet address. 632 */ 633 IN_IFADDR_RLOCK(); 634 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 635 IN_IFADDR_RUNLOCK(); 636 goto drop; 637 } 638 ifa_ref(&ia->ia_ifa); 639 IN_IFADDR_RUNLOCK(); 640 match: 641 if (!enaddr) 642 enaddr = (u_int8_t *)IF_LLADDR(ifp); 643 myaddr = ia->ia_addr.sin_addr; 644 ifa_free(&ia->ia_ifa); 645 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 646 goto drop; /* it's from me, ignore it. */ 647 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 648 log(LOG_ERR, 649 "arp: link address is broadcast for IP address %s!\n", 650 inet_ntoa(isaddr)); 651 goto drop; 652 } 653 /* 654 * Warn if another host is using the same IP address, but only if the 655 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 656 * case we suppress the warning to avoid false positive complaints of 657 * potential misconfiguration. 658 */ 659 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 660 log(LOG_ERR, 661 "arp: %*D is using my IP address %s on %s!\n", 662 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 663 inet_ntoa(isaddr), ifp->if_xname); 664 itaddr = myaddr; 665 ARPSTAT_INC(dupips); 666 goto reply; 667 } 668 if (ifp->if_flags & IFF_STATICARP) 669 goto reply; 670 671 bzero(&sin, sizeof(sin)); 672 sin.sin_len = sizeof(struct sockaddr_in); 673 sin.sin_family = AF_INET; 674 sin.sin_addr = isaddr; 675 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 676 flags |= LLE_EXCLUSIVE; 677 IF_AFDATA_LOCK(ifp); 678 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 679 IF_AFDATA_UNLOCK(ifp); 680 if (la != NULL) { 681 /* the following is not an error when doing bridging */ 682 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) { 683 if (log_arp_wrong_iface) 684 log(LOG_ERR, "arp: %s is on %s " 685 "but got reply from %*D on %s\n", 686 inet_ntoa(isaddr), 687 la->lle_tbl->llt_ifp->if_xname, 688 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 689 ifp->if_xname); 690 LLE_WUNLOCK(la); 691 goto reply; 692 } 693 if ((la->la_flags & LLE_VALID) && 694 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 695 if (la->la_flags & LLE_STATIC) { 696 LLE_WUNLOCK(la); 697 if (log_arp_permanent_modify) 698 log(LOG_ERR, 699 "arp: %*D attempts to modify " 700 "permanent entry for %s on %s\n", 701 ifp->if_addrlen, 702 (u_char *)ar_sha(ah), ":", 703 inet_ntoa(isaddr), ifp->if_xname); 704 goto reply; 705 } 706 if (log_arp_movements) { 707 log(LOG_INFO, "arp: %s moved from %*D " 708 "to %*D on %s\n", 709 inet_ntoa(isaddr), 710 ifp->if_addrlen, 711 (u_char *)&la->ll_addr, ":", 712 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 713 ifp->if_xname); 714 } 715 } 716 717 if (ifp->if_addrlen != ah->ar_hln) { 718 LLE_WUNLOCK(la); 719 log(LOG_WARNING, 720 "arp from %*D: addr len: new %d, i/f %d (ignored)", 721 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 722 ah->ar_hln, ifp->if_addrlen); 723 goto drop; 724 } 725 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 726 la->la_flags |= LLE_VALID; 727 728 EVENTHANDLER_INVOKE(arp_update_event, la); 729 730 if (!(la->la_flags & LLE_STATIC)) { 731 int canceled; 732 733 LLE_ADDREF(la); 734 la->la_expire = time_uptime + V_arpt_keep; 735 canceled = callout_reset(&la->la_timer, 736 hz * V_arpt_keep, arptimer, la); 737 if (canceled) 738 LLE_REMREF(la); 739 } 740 la->la_asked = 0; 741 la->la_preempt = V_arp_maxtries; 742 /* 743 * The packets are all freed within the call to the output 744 * routine. 745 * 746 * NB: The lock MUST be released before the call to the 747 * output routine. 748 */ 749 if (la->la_hold != NULL) { 750 struct mbuf *m_hold, *m_hold_next; 751 752 m_hold = la->la_hold; 753 la->la_hold = NULL; 754 la->la_numheld = 0; 755 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 756 LLE_WUNLOCK(la); 757 for (; m_hold != NULL; m_hold = m_hold_next) { 758 m_hold_next = m_hold->m_nextpkt; 759 m_hold->m_nextpkt = NULL; 760 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 761 } 762 } else 763 LLE_WUNLOCK(la); 764 } 765 reply: 766 if (op != ARPOP_REQUEST) 767 goto drop; 768 ARPSTAT_INC(rxrequests); 769 770 if (itaddr.s_addr == myaddr.s_addr) { 771 /* Shortcut.. the receiving interface is the target. */ 772 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 773 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 774 } else { 775 struct llentry *lle = NULL; 776 777 sin.sin_addr = itaddr; 778 IF_AFDATA_LOCK(ifp); 779 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 780 IF_AFDATA_UNLOCK(ifp); 781 782 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 783 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 784 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 785 LLE_RUNLOCK(lle); 786 } else { 787 788 if (lle != NULL) 789 LLE_RUNLOCK(lle); 790 791 if (!V_arp_proxyall) 792 goto drop; 793 794 sin.sin_addr = itaddr; 795 /* XXX MRT use table 0 for arp reply */ 796 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 797 if (!rt) 798 goto drop; 799 800 /* 801 * Don't send proxies for nodes on the same interface 802 * as this one came out of, or we'll get into a fight 803 * over who claims what Ether address. 804 */ 805 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 806 RTFREE_LOCKED(rt); 807 goto drop; 808 } 809 RTFREE_LOCKED(rt); 810 811 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 812 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 813 814 /* 815 * Also check that the node which sent the ARP packet 816 * is on the interface we expect it to be on. This 817 * avoids ARP chaos if an interface is connected to the 818 * wrong network. 819 */ 820 sin.sin_addr = isaddr; 821 822 /* XXX MRT use table 0 for arp checks */ 823 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 824 if (!rt) 825 goto drop; 826 if (rt->rt_ifp != ifp) { 827 log(LOG_INFO, "arp_proxy: ignoring request" 828 " from %s via %s, expecting %s\n", 829 inet_ntoa(isaddr), ifp->if_xname, 830 rt->rt_ifp->if_xname); 831 RTFREE_LOCKED(rt); 832 goto drop; 833 } 834 RTFREE_LOCKED(rt); 835 836 #ifdef DEBUG_PROXY 837 printf("arp: proxying for %s\n", 838 inet_ntoa(itaddr)); 839 #endif 840 } 841 } 842 843 if (itaddr.s_addr == myaddr.s_addr && 844 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 845 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 846 #ifdef DEBUG_LINKLOCAL 847 printf("arp: sending reply for link-local addr %s\n", 848 inet_ntoa(itaddr)); 849 #endif 850 m->m_flags |= M_BCAST; 851 m->m_flags &= ~M_MCAST; 852 } else { 853 /* default behaviour; never reply by broadcast. */ 854 m->m_flags &= ~(M_BCAST|M_MCAST); 855 } 856 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 857 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 858 ah->ar_op = htons(ARPOP_REPLY); 859 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 860 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 861 m->m_pkthdr.len = m->m_len; 862 m->m_pkthdr.rcvif = NULL; 863 sa.sa_family = AF_ARP; 864 sa.sa_len = 2; 865 (*ifp->if_output)(ifp, m, &sa, NULL); 866 ARPSTAT_INC(txreplies); 867 return; 868 869 drop: 870 m_freem(m); 871 } 872 #endif 873 874 void 875 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 876 { 877 struct llentry *lle; 878 879 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 880 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 881 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 882 /* 883 * interface address is considered static entry 884 * because the output of the arp utility shows 885 * that L2 entry as permanent 886 */ 887 IF_AFDATA_LOCK(ifp); 888 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 889 (struct sockaddr *)IA_SIN(ifa)); 890 IF_AFDATA_UNLOCK(ifp); 891 if (lle == NULL) 892 log(LOG_INFO, "arp_ifinit: cannot create arp " 893 "entry for interface address\n"); 894 else 895 LLE_RUNLOCK(lle); 896 } 897 ifa->ifa_rtrequest = NULL; 898 } 899 900 void 901 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 902 { 903 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 904 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 905 &IA_SIN(ifa)->sin_addr, enaddr); 906 ifa->ifa_rtrequest = NULL; 907 } 908 909 static void 910 arp_init(void) 911 { 912 913 netisr_register(&arp_nh); 914 } 915 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
Cache object: ec8e85b2ba5f366207a41b70b9720301
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