if_ether.c revision 243882
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 243882 2012-12-05 08:04:20Z 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 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 */ 209void 210arprequest(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_NOWAIT, 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 */ 291int 292arpresolve(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 } 315retry: 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 } 424done: 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 */ 436static void 437arpintr(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 */ 496static int log_arp_wrong_iface = 1; 497static int log_arp_movements = 1; 498static int log_arp_permanent_modify = 1; 499static int allow_multicast = 0; 500 501SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 502 &log_arp_wrong_iface, 0, 503 "log arp packets arriving on the wrong interface"); 504SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 505 &log_arp_movements, 0, 506 "log arp replies from MACs different than the one in the cache"); 507SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 508 &log_arp_permanent_modify, 0, 509 "log arp replies from MACs different than the one in the permanent arp entry"); 510SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 511 &allow_multicast, 0, "accept multicast addresses"); 512 513static void 514in_arpinput(struct mbuf *m) 515{ 516 struct arphdr *ah; 517 struct ifnet *ifp = m->m_pkthdr.rcvif; 518 struct llentry *la = NULL; 519 struct rtentry *rt; 520 struct ifaddr *ifa; 521 struct in_ifaddr *ia; 522 struct sockaddr sa; 523 struct in_addr isaddr, itaddr, myaddr; 524 u_int8_t *enaddr = NULL; 525 int op, flags; 526 int req_len; 527 int bridged = 0, is_bridge = 0; 528 int carped; 529 struct sockaddr_in sin; 530 sin.sin_len = sizeof(struct sockaddr_in); 531 sin.sin_family = AF_INET; 532 sin.sin_addr.s_addr = 0; 533 534 if (ifp->if_bridge) 535 bridged = 1; 536 if (ifp->if_type == IFT_BRIDGE) 537 is_bridge = 1; 538 539 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 540 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 541 log(LOG_NOTICE, "in_arp: runt packet -- m_pullup failed\n"); 542 return; 543 } 544 545 ah = mtod(m, struct arphdr *); 546 /* 547 * ARP is only for IPv4 so we can reject packets with 548 * a protocol length not equal to an IPv4 address. 549 */ 550 if (ah->ar_pln != sizeof(struct in_addr)) { 551 log(LOG_NOTICE, "in_arp: requested protocol length != %zu\n", 552 sizeof(struct in_addr)); 553 return; 554 } 555 556 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 557 log(LOG_NOTICE, "arp: %*D is multicast\n", 558 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 559 return; 560 } 561 562 op = ntohs(ah->ar_op); 563 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 564 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 565 566 if (op == ARPOP_REPLY) 567 ARPSTAT_INC(rxreplies); 568 569 /* 570 * For a bridge, we want to check the address irrespective 571 * of the receive interface. (This will change slightly 572 * when we have clusters of interfaces). 573 */ 574 IN_IFADDR_RLOCK(); 575 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 576 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 577 ia->ia_ifp == ifp) && 578 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 579 (ia->ia_ifa.ifa_carp == NULL || 580 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 581 ifa_ref(&ia->ia_ifa); 582 IN_IFADDR_RUNLOCK(); 583 goto match; 584 } 585 } 586 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 587 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 588 ia->ia_ifp == ifp) && 589 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 590 ifa_ref(&ia->ia_ifa); 591 IN_IFADDR_RUNLOCK(); 592 goto match; 593 } 594 595#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 596 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 597 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 598 addr == ia->ia_addr.sin_addr.s_addr) 599 /* 600 * Check the case when bridge shares its MAC address with 601 * some of its children, so packets are claimed by bridge 602 * itself (bridge_input() does it first), but they are really 603 * meant to be destined to the bridge member. 604 */ 605 if (is_bridge) { 606 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 607 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 608 ifa_ref(&ia->ia_ifa); 609 ifp = ia->ia_ifp; 610 IN_IFADDR_RUNLOCK(); 611 goto match; 612 } 613 } 614 } 615#undef BDG_MEMBER_MATCHES_ARP 616 IN_IFADDR_RUNLOCK(); 617 618 /* 619 * No match, use the first inet address on the receive interface 620 * as a dummy address for the rest of the function. 621 */ 622 IF_ADDR_RLOCK(ifp); 623 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 624 if (ifa->ifa_addr->sa_family == AF_INET && 625 (ifa->ifa_carp == NULL || 626 (*carp_iamatch_p)(ifa, &enaddr))) { 627 ia = ifatoia(ifa); 628 ifa_ref(ifa); 629 IF_ADDR_RUNLOCK(ifp); 630 goto match; 631 } 632 IF_ADDR_RUNLOCK(ifp); 633 634 /* 635 * If bridging, fall back to using any inet address. 636 */ 637 IN_IFADDR_RLOCK(); 638 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 639 IN_IFADDR_RUNLOCK(); 640 goto drop; 641 } 642 ifa_ref(&ia->ia_ifa); 643 IN_IFADDR_RUNLOCK(); 644match: 645 if (!enaddr) 646 enaddr = (u_int8_t *)IF_LLADDR(ifp); 647 carped = (ia->ia_ifa.ifa_carp != NULL); 648 myaddr = ia->ia_addr.sin_addr; 649 ifa_free(&ia->ia_ifa); 650 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 651 goto drop; /* it's from me, ignore it. */ 652 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 653 log(LOG_NOTICE, 654 "arp: link address is broadcast for IP address %s!\n", 655 inet_ntoa(isaddr)); 656 goto drop; 657 } 658 /* 659 * Warn if another host is using the same IP address, but only if the 660 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 661 * case we suppress the warning to avoid false positive complaints of 662 * potential misconfiguration. 663 */ 664 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 665 myaddr.s_addr != 0) { 666 log(LOG_ERR, "arp: %*D is using my IP address %s on %s!\n", 667 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 668 inet_ntoa(isaddr), ifp->if_xname); 669 itaddr = myaddr; 670 ARPSTAT_INC(dupips); 671 goto reply; 672 } 673 if (ifp->if_flags & IFF_STATICARP) 674 goto reply; 675 676 bzero(&sin, sizeof(sin)); 677 sin.sin_len = sizeof(struct sockaddr_in); 678 sin.sin_family = AF_INET; 679 sin.sin_addr = isaddr; 680 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 681 flags |= LLE_EXCLUSIVE; 682 IF_AFDATA_LOCK(ifp); 683 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 684 IF_AFDATA_UNLOCK(ifp); 685 if (la != NULL) { 686 /* the following is not an error when doing bridging */ 687 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 688 if (log_arp_wrong_iface) 689 log(LOG_WARNING, "arp: %s is on %s " 690 "but got reply from %*D on %s\n", 691 inet_ntoa(isaddr), 692 la->lle_tbl->llt_ifp->if_xname, 693 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 694 ifp->if_xname); 695 LLE_WUNLOCK(la); 696 goto reply; 697 } 698 if ((la->la_flags & LLE_VALID) && 699 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 700 if (la->la_flags & LLE_STATIC) { 701 LLE_WUNLOCK(la); 702 if (log_arp_permanent_modify) 703 log(LOG_ERR, 704 "arp: %*D attempts to modify " 705 "permanent entry for %s on %s\n", 706 ifp->if_addrlen, 707 (u_char *)ar_sha(ah), ":", 708 inet_ntoa(isaddr), ifp->if_xname); 709 goto reply; 710 } 711 if (log_arp_movements) { 712 log(LOG_INFO, "arp: %s moved from %*D " 713 "to %*D on %s\n", 714 inet_ntoa(isaddr), 715 ifp->if_addrlen, 716 (u_char *)&la->ll_addr, ":", 717 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 718 ifp->if_xname); 719 } 720 } 721 722 if (ifp->if_addrlen != ah->ar_hln) { 723 LLE_WUNLOCK(la); 724 log(LOG_WARNING, "arp from %*D: addr len: new %d, " 725 "i/f %d (ignored)\n", ifp->if_addrlen, 726 (u_char *) ar_sha(ah), ":", ah->ar_hln, 727 ifp->if_addrlen); 728 goto drop; 729 } 730 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 731 la->la_flags |= LLE_VALID; 732 733 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 734 735 if (!(la->la_flags & LLE_STATIC)) { 736 int canceled; 737 738 LLE_ADDREF(la); 739 la->la_expire = time_uptime + V_arpt_keep; 740 canceled = callout_reset(&la->la_timer, 741 hz * V_arpt_keep, arptimer, la); 742 if (canceled) 743 LLE_REMREF(la); 744 } 745 la->la_asked = 0; 746 la->la_preempt = V_arp_maxtries; 747 /* 748 * The packets are all freed within the call to the output 749 * routine. 750 * 751 * NB: The lock MUST be released before the call to the 752 * output routine. 753 */ 754 if (la->la_hold != NULL) { 755 struct mbuf *m_hold, *m_hold_next; 756 757 m_hold = la->la_hold; 758 la->la_hold = NULL; 759 la->la_numheld = 0; 760 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 761 LLE_WUNLOCK(la); 762 for (; m_hold != NULL; m_hold = m_hold_next) { 763 m_hold_next = m_hold->m_nextpkt; 764 m_hold->m_nextpkt = NULL; 765 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 766 } 767 } else 768 LLE_WUNLOCK(la); 769 } 770reply: 771 if (op != ARPOP_REQUEST) 772 goto drop; 773 ARPSTAT_INC(rxrequests); 774 775 if (itaddr.s_addr == myaddr.s_addr) { 776 /* Shortcut.. the receiving interface is the target. */ 777 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 778 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 779 } else { 780 struct llentry *lle = NULL; 781 782 sin.sin_addr = itaddr; 783 IF_AFDATA_LOCK(ifp); 784 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 785 IF_AFDATA_UNLOCK(ifp); 786 787 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 788 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 789 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 790 LLE_RUNLOCK(lle); 791 } else { 792 793 if (lle != NULL) 794 LLE_RUNLOCK(lle); 795 796 if (!V_arp_proxyall) 797 goto drop; 798 799 sin.sin_addr = itaddr; 800 /* XXX MRT use table 0 for arp reply */ 801 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 802 if (!rt) 803 goto drop; 804 805 /* 806 * Don't send proxies for nodes on the same interface 807 * as this one came out of, or we'll get into a fight 808 * over who claims what Ether address. 809 */ 810 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 811 RTFREE_LOCKED(rt); 812 goto drop; 813 } 814 RTFREE_LOCKED(rt); 815 816 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 817 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 818 819 /* 820 * Also check that the node which sent the ARP packet 821 * is on the interface we expect it to be on. This 822 * avoids ARP chaos if an interface is connected to the 823 * wrong network. 824 */ 825 sin.sin_addr = isaddr; 826 827 /* XXX MRT use table 0 for arp checks */ 828 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 829 if (!rt) 830 goto drop; 831 if (rt->rt_ifp != ifp) { 832 log(LOG_INFO, "arp_proxy: ignoring request" 833 " from %s via %s, expecting %s\n", 834 inet_ntoa(isaddr), ifp->if_xname, 835 rt->rt_ifp->if_xname); 836 RTFREE_LOCKED(rt); 837 goto drop; 838 } 839 RTFREE_LOCKED(rt); 840 841#ifdef DEBUG_PROXY 842 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 843#endif 844 } 845 } 846 847 if (itaddr.s_addr == myaddr.s_addr && 848 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 849 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 850#ifdef DEBUG_LINKLOCAL 851 printf("arp: sending reply for link-local addr %s\n", 852 inet_ntoa(itaddr)); 853#endif 854 m->m_flags |= M_BCAST; 855 m->m_flags &= ~M_MCAST; 856 } else { 857 /* default behaviour; never reply by broadcast. */ 858 m->m_flags &= ~(M_BCAST|M_MCAST); 859 } 860 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 861 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 862 ah->ar_op = htons(ARPOP_REPLY); 863 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 864 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 865 m->m_pkthdr.len = m->m_len; 866 m->m_pkthdr.rcvif = NULL; 867 sa.sa_family = AF_ARP; 868 sa.sa_len = 2; 869 (*ifp->if_output)(ifp, m, &sa, NULL); 870 ARPSTAT_INC(txreplies); 871 return; 872 873drop: 874 m_freem(m); 875} 876#endif 877 878void 879arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 880{ 881 struct llentry *lle; 882 883 if (ifa->ifa_carp != NULL) 884 return; 885 886 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 887 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 888 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 889 /* 890 * interface address is considered static entry 891 * because the output of the arp utility shows 892 * that L2 entry as permanent 893 */ 894 IF_AFDATA_LOCK(ifp); 895 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 896 (struct sockaddr *)IA_SIN(ifa)); 897 IF_AFDATA_UNLOCK(ifp); 898 if (lle == NULL) 899 log(LOG_INFO, "arp_ifinit: cannot create arp " 900 "entry for interface address\n"); 901 else 902 LLE_RUNLOCK(lle); 903 } 904 ifa->ifa_rtrequest = NULL; 905} 906 907void 908arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 909{ 910 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 911 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 912 &IA_SIN(ifa)->sin_addr, enaddr); 913 ifa->ifa_rtrequest = NULL; 914} 915 916static void 917arp_init(void) 918{ 919 920 netisr_register(&arp_nh); 921} 922SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 923