if_ether.c revision 249903
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: head/sys/netinet/if_ether.c 249903 2013-04-25 17:38:04Z glebius $"); 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 79SYSCTL_DECL(_net_link_ether); 80static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 81static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 82 83/* timer values */ 84static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 85 * minutes */ 86static VNET_DEFINE(int, arp_maxtries) = 5; 87VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for 88 * local traffic */ 89static VNET_DEFINE(int, arp_proxyall) = 0; 90static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 91 * 20 seconds */ 92VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 93 94static 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 103SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 104 &VNET_NAME(arpt_keep), 0, 105 "ARP entry lifetime in seconds"); 106SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 107 &VNET_NAME(arp_maxtries), 0, 108 "ARP resolution attempts before returning error"); 109SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 110 &VNET_NAME(useloopback), 0, 111 "Use the loopback interface for local traffic"); 112SYSCTL_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"); 115SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW, 116 &VNET_NAME(arpt_down), 0, 117 "Incomplete ARP entry lifetime in seconds"); 118SYSCTL_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)"); 121SYSCTL_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 125static void arp_init(void); 126static void arpintr(struct mbuf *); 127static void arptimer(void *); 128#ifdef INET 129static void in_arpinput(struct mbuf *); 130#endif 131 132static 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 */ 144void 145arp_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 */ 163static void 164arptimer(void *arg) 165{ 166 struct llentry *lle = (struct llentry *)arg; 167 struct ifnet *ifp; 168 169 if (lle->la_flags & LLE_STATIC) { 170 LLE_WUNLOCK(lle); 171 return; 172 } 173 174 ifp = lle->lle_tbl->llt_ifp; 175 CURVNET_SET(ifp->if_vnet); 176 177 if (lle->la_flags != LLE_DELETED) { 178 int evt; 179 180 if (lle->la_flags & LLE_VALID) 181 evt = LLENTRY_EXPIRED; 182 else 183 evt = LLENTRY_TIMEDOUT; 184 EVENTHANDLER_INVOKE(lle_event, lle, evt); 185 } 186 187 callout_stop(&lle->la_timer); 188 189 /* XXX: LOR avoidance. We still have ref on lle. */ 190 LLE_WUNLOCK(lle); 191 IF_AFDATA_LOCK(ifp); 192 LLE_WLOCK(lle); 193 194 /* Guard against race with other llentry_free(). */ 195 if (lle->la_flags & LLE_LINKED) { 196 size_t pkts_dropped; 197 198 LLE_REMREF(lle); 199 pkts_dropped = llentry_free(lle); 200 ARPSTAT_ADD(dropped, pkts_dropped); 201 } else 202 LLE_FREE_LOCKED(lle); 203 204 IF_AFDATA_UNLOCK(ifp); 205 206 ARPSTAT_INC(timeouts); 207 208 CURVNET_RESTORE(); 209} 210 211/* 212 * Broadcast an ARP request. Caller specifies: 213 * - arp header source ip address 214 * - arp header target ip address 215 * - arp header source ethernet address 216 */ 217void 218arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 219 u_char *enaddr) 220{ 221 struct mbuf *m; 222 struct arphdr *ah; 223 struct sockaddr sa; 224 u_char *carpaddr = NULL; 225 226 if (sip == NULL) { 227 /* 228 * The caller did not supply a source address, try to find 229 * a compatible one among those assigned to this interface. 230 */ 231 struct ifaddr *ifa; 232 233 IF_ADDR_RLOCK(ifp); 234 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 235 if (ifa->ifa_addr->sa_family != AF_INET) 236 continue; 237 238 if (ifa->ifa_carp) { 239 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 240 continue; 241 sip = &IA_SIN(ifa)->sin_addr; 242 } else { 243 carpaddr = NULL; 244 sip = &IA_SIN(ifa)->sin_addr; 245 } 246 247 if (0 == ((sip->s_addr ^ tip->s_addr) & 248 IA_MASKSIN(ifa)->sin_addr.s_addr)) 249 break; /* found it. */ 250 } 251 IF_ADDR_RUNLOCK(ifp); 252 if (sip == NULL) { 253 printf("%s: cannot find matching address\n", __func__); 254 return; 255 } 256 } 257 if (enaddr == NULL) 258 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 259 260 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 261 return; 262 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 263 2*ifp->if_data.ifi_addrlen; 264 m->m_pkthdr.len = m->m_len; 265 MH_ALIGN(m, m->m_len); 266 ah = mtod(m, struct arphdr *); 267 bzero((caddr_t)ah, m->m_len); 268#ifdef MAC 269 mac_netinet_arp_send(ifp, m); 270#endif 271 ah->ar_pro = htons(ETHERTYPE_IP); 272 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 273 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 274 ah->ar_op = htons(ARPOP_REQUEST); 275 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 276 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 277 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 278 sa.sa_family = AF_ARP; 279 sa.sa_len = 2; 280 m->m_flags |= M_BCAST; 281 (*ifp->if_output)(ifp, m, &sa, NULL); 282 ARPSTAT_INC(txrequests); 283} 284 285/* 286 * Resolve an IP address into an ethernet address. 287 * On input: 288 * ifp is the interface we use 289 * rt0 is the route to the final destination (possibly useless) 290 * m is the mbuf. May be NULL if we don't have a packet. 291 * dst is the next hop, 292 * desten is where we want the address. 293 * 294 * On success, desten is filled in and the function returns 0; 295 * If the packet must be held pending resolution, we return EWOULDBLOCK 296 * On other errors, we return the corresponding error code. 297 * Note that m_freem() handles NULL. 298 */ 299int 300arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 301 struct sockaddr *dst, u_char *desten, struct llentry **lle) 302{ 303 struct llentry *la = 0; 304 u_int flags = 0; 305 struct mbuf *curr = NULL; 306 struct mbuf *next = NULL; 307 int error, renew; 308 309 *lle = NULL; 310 if (m != NULL) { 311 if (m->m_flags & M_BCAST) { 312 /* broadcast */ 313 (void)memcpy(desten, 314 ifp->if_broadcastaddr, ifp->if_addrlen); 315 return (0); 316 } 317 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 318 /* multicast */ 319 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 320 return (0); 321 } 322 } 323retry: 324 IF_AFDATA_RLOCK(ifp); 325 la = lla_lookup(LLTABLE(ifp), flags, dst); 326 IF_AFDATA_RUNLOCK(ifp); 327 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 328 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 329 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 330 IF_AFDATA_WLOCK(ifp); 331 la = lla_lookup(LLTABLE(ifp), flags, dst); 332 IF_AFDATA_WUNLOCK(ifp); 333 } 334 if (la == NULL) { 335 if (flags & LLE_CREATE) 336 log(LOG_DEBUG, 337 "arpresolve: can't allocate llinfo for %s\n", 338 inet_ntoa(SIN(dst)->sin_addr)); 339 m_freem(m); 340 return (EINVAL); 341 } 342 343 if ((la->la_flags & LLE_VALID) && 344 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 345 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 346 /* 347 * If entry has an expiry time and it is approaching, 348 * see if we need to send an ARP request within this 349 * arpt_down interval. 350 */ 351 if (!(la->la_flags & LLE_STATIC) && 352 time_uptime + la->la_preempt > la->la_expire) { 353 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 354 la->la_preempt--; 355 } 356 357 *lle = la; 358 error = 0; 359 goto done; 360 } 361 362 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 363 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 364 inet_ntoa(SIN(dst)->sin_addr)); 365 m_freem(m); 366 error = EINVAL; 367 goto done; 368 } 369 370 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 371 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 372 flags |= LLE_EXCLUSIVE; 373 LLE_RUNLOCK(la); 374 goto retry; 375 } 376 /* 377 * There is an arptab entry, but no ethernet address 378 * response yet. Add the mbuf to the list, dropping 379 * the oldest packet if we have exceeded the system 380 * setting. 381 */ 382 if (m != NULL) { 383 if (la->la_numheld >= V_arp_maxhold) { 384 if (la->la_hold != NULL) { 385 next = la->la_hold->m_nextpkt; 386 m_freem(la->la_hold); 387 la->la_hold = next; 388 la->la_numheld--; 389 ARPSTAT_INC(dropped); 390 } 391 } 392 if (la->la_hold != NULL) { 393 curr = la->la_hold; 394 while (curr->m_nextpkt != NULL) 395 curr = curr->m_nextpkt; 396 curr->m_nextpkt = m; 397 } else 398 la->la_hold = m; 399 la->la_numheld++; 400 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 401 flags &= ~LLE_EXCLUSIVE; 402 LLE_DOWNGRADE(la); 403 } 404 405 } 406 /* 407 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 408 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 409 * if we have already sent arp_maxtries ARP requests. Retransmit the 410 * ARP request, but not faster than one request per second. 411 */ 412 if (la->la_asked < V_arp_maxtries) 413 error = EWOULDBLOCK; /* First request. */ 414 else 415 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 416 EHOSTUNREACH : EHOSTDOWN; 417 418 if (renew) { 419 int canceled; 420 421 LLE_ADDREF(la); 422 la->la_expire = time_uptime; 423 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 424 arptimer, la); 425 if (canceled) 426 LLE_REMREF(la); 427 la->la_asked++; 428 LLE_WUNLOCK(la); 429 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 430 return (error); 431 } 432done: 433 if (flags & LLE_EXCLUSIVE) 434 LLE_WUNLOCK(la); 435 else 436 LLE_RUNLOCK(la); 437 return (error); 438} 439 440/* 441 * Common length and type checks are done here, 442 * then the protocol-specific routine is called. 443 */ 444static void 445arpintr(struct mbuf *m) 446{ 447 struct arphdr *ar; 448 449 if (m->m_len < sizeof(struct arphdr) && 450 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 451 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 452 return; 453 } 454 ar = mtod(m, struct arphdr *); 455 456 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 457 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 458 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 459 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 460 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 461 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 462 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 463 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 464 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 465 m_freem(m); 466 return; 467 } 468 469 if (m->m_len < arphdr_len(ar)) { 470 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 471 log(LOG_NOTICE, "arp: runt packet\n"); 472 m_freem(m); 473 return; 474 } 475 ar = mtod(m, struct arphdr *); 476 } 477 478 ARPSTAT_INC(received); 479 switch (ntohs(ar->ar_pro)) { 480#ifdef INET 481 case ETHERTYPE_IP: 482 in_arpinput(m); 483 return; 484#endif 485 } 486 m_freem(m); 487} 488 489#ifdef INET 490/* 491 * ARP for Internet protocols on 10 Mb/s Ethernet. 492 * Algorithm is that given in RFC 826. 493 * In addition, a sanity check is performed on the sender 494 * protocol address, to catch impersonators. 495 * We no longer handle negotiations for use of trailer protocol: 496 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 497 * along with IP replies if we wanted trailers sent to us, 498 * and also sent them in response to IP replies. 499 * This allowed either end to announce the desire to receive 500 * trailer packets. 501 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 502 * but formerly didn't normally send requests. 503 */ 504static int log_arp_wrong_iface = 1; 505static int log_arp_movements = 1; 506static int log_arp_permanent_modify = 1; 507static int allow_multicast = 0; 508 509SYSCTL_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"); 512SYSCTL_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"); 515SYSCTL_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"); 518SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 519 &allow_multicast, 0, "accept multicast addresses"); 520 521static void 522in_arpinput(struct mbuf *m) 523{ 524 struct arphdr *ah; 525 struct ifnet *ifp = m->m_pkthdr.rcvif; 526 struct llentry *la = NULL; 527 struct rtentry *rt; 528 struct ifaddr *ifa; 529 struct in_ifaddr *ia; 530 struct sockaddr sa; 531 struct in_addr isaddr, itaddr, myaddr; 532 u_int8_t *enaddr = NULL; 533 int op, flags; 534 int req_len; 535 int bridged = 0, is_bridge = 0; 536 int carped; 537 struct sockaddr_in sin; 538 sin.sin_len = sizeof(struct sockaddr_in); 539 sin.sin_family = AF_INET; 540 sin.sin_addr.s_addr = 0; 541 542 if (ifp->if_bridge) 543 bridged = 1; 544 if (ifp->if_type == IFT_BRIDGE) 545 is_bridge = 1; 546 547 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 548 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 549 log(LOG_NOTICE, "in_arp: runt packet -- m_pullup failed\n"); 550 return; 551 } 552 553 ah = mtod(m, struct arphdr *); 554 /* 555 * ARP is only for IPv4 so we can reject packets with 556 * a protocol length not equal to an IPv4 address. 557 */ 558 if (ah->ar_pln != sizeof(struct in_addr)) { 559 log(LOG_NOTICE, "in_arp: requested protocol length != %zu\n", 560 sizeof(struct in_addr)); 561 goto drop; 562 } 563 564 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 565 log(LOG_NOTICE, "arp: %*D is multicast\n", 566 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 567 goto drop; 568 } 569 570 op = ntohs(ah->ar_op); 571 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 572 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 573 574 if (op == ARPOP_REPLY) 575 ARPSTAT_INC(rxreplies); 576 577 /* 578 * For a bridge, we want to check the address irrespective 579 * of the receive interface. (This will change slightly 580 * when we have clusters of interfaces). 581 */ 582 IN_IFADDR_RLOCK(); 583 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 584 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 585 ia->ia_ifp == ifp) && 586 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 587 (ia->ia_ifa.ifa_carp == NULL || 588 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 589 ifa_ref(&ia->ia_ifa); 590 IN_IFADDR_RUNLOCK(); 591 goto match; 592 } 593 } 594 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 595 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 596 ia->ia_ifp == ifp) && 597 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 598 ifa_ref(&ia->ia_ifa); 599 IN_IFADDR_RUNLOCK(); 600 goto match; 601 } 602 603#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 604 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 605 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 606 addr == ia->ia_addr.sin_addr.s_addr) 607 /* 608 * Check the case when bridge shares its MAC address with 609 * some of its children, so packets are claimed by bridge 610 * itself (bridge_input() does it first), but they are really 611 * meant to be destined to the bridge member. 612 */ 613 if (is_bridge) { 614 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 615 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 616 ifa_ref(&ia->ia_ifa); 617 ifp = ia->ia_ifp; 618 IN_IFADDR_RUNLOCK(); 619 goto match; 620 } 621 } 622 } 623#undef BDG_MEMBER_MATCHES_ARP 624 IN_IFADDR_RUNLOCK(); 625 626 /* 627 * No match, use the first inet address on the receive interface 628 * as a dummy address for the rest of the function. 629 */ 630 IF_ADDR_RLOCK(ifp); 631 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 632 if (ifa->ifa_addr->sa_family == AF_INET && 633 (ifa->ifa_carp == NULL || 634 (*carp_iamatch_p)(ifa, &enaddr))) { 635 ia = ifatoia(ifa); 636 ifa_ref(ifa); 637 IF_ADDR_RUNLOCK(ifp); 638 goto match; 639 } 640 IF_ADDR_RUNLOCK(ifp); 641 642 /* 643 * If bridging, fall back to using any inet address. 644 */ 645 IN_IFADDR_RLOCK(); 646 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 647 IN_IFADDR_RUNLOCK(); 648 goto drop; 649 } 650 ifa_ref(&ia->ia_ifa); 651 IN_IFADDR_RUNLOCK(); 652match: 653 if (!enaddr) 654 enaddr = (u_int8_t *)IF_LLADDR(ifp); 655 carped = (ia->ia_ifa.ifa_carp != NULL); 656 myaddr = ia->ia_addr.sin_addr; 657 ifa_free(&ia->ia_ifa); 658 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 659 goto drop; /* it's from me, ignore it. */ 660 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 661 log(LOG_NOTICE, 662 "arp: link address is broadcast for IP address %s!\n", 663 inet_ntoa(isaddr)); 664 goto drop; 665 } 666 /* 667 * Warn if another host is using the same IP address, but only if the 668 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 669 * case we suppress the warning to avoid false positive complaints of 670 * potential misconfiguration. 671 */ 672 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 673 myaddr.s_addr != 0) { 674 log(LOG_ERR, "arp: %*D is using my IP address %s on %s!\n", 675 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 676 inet_ntoa(isaddr), ifp->if_xname); 677 itaddr = myaddr; 678 ARPSTAT_INC(dupips); 679 goto reply; 680 } 681 if (ifp->if_flags & IFF_STATICARP) 682 goto reply; 683 684 bzero(&sin, sizeof(sin)); 685 sin.sin_len = sizeof(struct sockaddr_in); 686 sin.sin_family = AF_INET; 687 sin.sin_addr = isaddr; 688 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 689 flags |= LLE_EXCLUSIVE; 690 IF_AFDATA_LOCK(ifp); 691 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 692 IF_AFDATA_UNLOCK(ifp); 693 if (la != NULL) { 694 /* the following is not an error when doing bridging */ 695 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 696 if (log_arp_wrong_iface) 697 log(LOG_WARNING, "arp: %s is on %s " 698 "but got reply from %*D on %s\n", 699 inet_ntoa(isaddr), 700 la->lle_tbl->llt_ifp->if_xname, 701 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 702 ifp->if_xname); 703 LLE_WUNLOCK(la); 704 goto reply; 705 } 706 if ((la->la_flags & LLE_VALID) && 707 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 708 if (la->la_flags & LLE_STATIC) { 709 LLE_WUNLOCK(la); 710 if (log_arp_permanent_modify) 711 log(LOG_ERR, 712 "arp: %*D attempts to modify " 713 "permanent entry for %s on %s\n", 714 ifp->if_addrlen, 715 (u_char *)ar_sha(ah), ":", 716 inet_ntoa(isaddr), ifp->if_xname); 717 goto reply; 718 } 719 if (log_arp_movements) { 720 log(LOG_INFO, "arp: %s moved from %*D " 721 "to %*D on %s\n", 722 inet_ntoa(isaddr), 723 ifp->if_addrlen, 724 (u_char *)&la->ll_addr, ":", 725 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 726 ifp->if_xname); 727 } 728 } 729 730 if (ifp->if_addrlen != ah->ar_hln) { 731 LLE_WUNLOCK(la); 732 log(LOG_WARNING, "arp from %*D: addr len: new %d, " 733 "i/f %d (ignored)\n", ifp->if_addrlen, 734 (u_char *) ar_sha(ah), ":", ah->ar_hln, 735 ifp->if_addrlen); 736 goto drop; 737 } 738 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 739 la->la_flags |= LLE_VALID; 740 741 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 742 743 if (!(la->la_flags & LLE_STATIC)) { 744 int canceled; 745 746 LLE_ADDREF(la); 747 la->la_expire = time_uptime + V_arpt_keep; 748 canceled = callout_reset(&la->la_timer, 749 hz * V_arpt_keep, arptimer, la); 750 if (canceled) 751 LLE_REMREF(la); 752 } 753 la->la_asked = 0; 754 la->la_preempt = V_arp_maxtries; 755 /* 756 * The packets are all freed within the call to the output 757 * routine. 758 * 759 * NB: The lock MUST be released before the call to the 760 * output routine. 761 */ 762 if (la->la_hold != NULL) { 763 struct mbuf *m_hold, *m_hold_next; 764 765 m_hold = la->la_hold; 766 la->la_hold = NULL; 767 la->la_numheld = 0; 768 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 769 LLE_WUNLOCK(la); 770 for (; m_hold != NULL; m_hold = m_hold_next) { 771 m_hold_next = m_hold->m_nextpkt; 772 m_hold->m_nextpkt = NULL; 773 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 774 } 775 } else 776 LLE_WUNLOCK(la); 777 } 778reply: 779 if (op != ARPOP_REQUEST) 780 goto drop; 781 ARPSTAT_INC(rxrequests); 782 783 if (itaddr.s_addr == myaddr.s_addr) { 784 /* Shortcut.. the receiving interface is the target. */ 785 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 786 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 787 } else { 788 struct llentry *lle = NULL; 789 790 sin.sin_addr = itaddr; 791 IF_AFDATA_LOCK(ifp); 792 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 793 IF_AFDATA_UNLOCK(ifp); 794 795 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 796 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 797 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 798 LLE_RUNLOCK(lle); 799 } else { 800 801 if (lle != NULL) 802 LLE_RUNLOCK(lle); 803 804 if (!V_arp_proxyall) 805 goto drop; 806 807 sin.sin_addr = itaddr; 808 /* XXX MRT use table 0 for arp reply */ 809 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 810 if (!rt) 811 goto drop; 812 813 /* 814 * Don't send proxies for nodes on the same interface 815 * as this one came out of, or we'll get into a fight 816 * over who claims what Ether address. 817 */ 818 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 819 RTFREE_LOCKED(rt); 820 goto drop; 821 } 822 RTFREE_LOCKED(rt); 823 824 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 825 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 826 827 /* 828 * Also check that the node which sent the ARP packet 829 * is on the interface we expect it to be on. This 830 * avoids ARP chaos if an interface is connected to the 831 * wrong network. 832 */ 833 sin.sin_addr = isaddr; 834 835 /* XXX MRT use table 0 for arp checks */ 836 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 837 if (!rt) 838 goto drop; 839 if (rt->rt_ifp != ifp) { 840 log(LOG_INFO, "arp_proxy: ignoring request" 841 " from %s via %s, expecting %s\n", 842 inet_ntoa(isaddr), ifp->if_xname, 843 rt->rt_ifp->if_xname); 844 RTFREE_LOCKED(rt); 845 goto drop; 846 } 847 RTFREE_LOCKED(rt); 848 849#ifdef DEBUG_PROXY 850 printf("arp: proxying for %s\n", 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 881drop: 882 m_freem(m); 883} 884#endif 885 886void 887arp_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 915void 916arp_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 924static void 925arp_init(void) 926{ 927 928 netisr_register(&arp_nh); 929} 930SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 931