if_ether.c revision 229810
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 229810 2012-01-08 13:34:00Z 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#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 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 ifnet *ifp; 167 struct llentry *lle; 168 int pkts_dropped; 169 170 KASSERT(arg != NULL, ("%s: arg NULL", __func__)); 171 lle = (struct llentry *)arg; 172 ifp = lle->lle_tbl->llt_ifp; 173 CURVNET_SET(ifp->if_vnet); 174 IF_AFDATA_LOCK(ifp); 175 LLE_WLOCK(lle); 176 if (lle->la_flags & LLE_STATIC) 177 LLE_WUNLOCK(lle); 178 else { 179 if (!callout_pending(&lle->la_timer) && 180 callout_active(&lle->la_timer)) { 181 callout_stop(&lle->la_timer); 182 LLE_REMREF(lle); 183 pkts_dropped = llentry_free(lle); 184 ARPSTAT_ADD(dropped, pkts_dropped); 185 ARPSTAT_INC(timeouts); 186 } else { 187#ifdef DIAGNOSTIC 188 struct sockaddr *l3addr = L3_ADDR(lle); 189 log(LOG_INFO, 190 "arptimer issue: %p, IPv4 address: \"%s\"\n", lle, 191 inet_ntoa( 192 ((const struct sockaddr_in *)l3addr)->sin_addr)); 193#endif 194 LLE_WUNLOCK(lle); 195 } 196 } 197 IF_AFDATA_UNLOCK(ifp); 198 CURVNET_RESTORE(); 199} 200 201/* 202 * Broadcast an ARP request. Caller specifies: 203 * - arp header source ip address 204 * - arp header target ip address 205 * - arp header source ethernet address 206 */ 207void 208arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 209 u_char *enaddr) 210{ 211 struct mbuf *m; 212 struct arphdr *ah; 213 struct sockaddr sa; 214 215 if (sip == NULL) { 216 /* XXX don't believe this can happen (or explain why) */ 217 /* 218 * The caller did not supply a source address, try to find 219 * a compatible one among those assigned to this interface. 220 */ 221 struct ifaddr *ifa; 222 223 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 224 if (!ifa->ifa_addr || 225 ifa->ifa_addr->sa_family != AF_INET) 226 continue; 227 sip = &SIN(ifa->ifa_addr)->sin_addr; 228 if (0 == ((sip->s_addr ^ tip->s_addr) & 229 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 230 break; /* found it. */ 231 } 232 if (sip == NULL) { 233 printf("%s: cannot find matching address\n", __func__); 234 return; 235 } 236 } 237 238 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 239 return; 240 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 241 2*ifp->if_data.ifi_addrlen; 242 m->m_pkthdr.len = m->m_len; 243 MH_ALIGN(m, m->m_len); 244 ah = mtod(m, struct arphdr *); 245 bzero((caddr_t)ah, m->m_len); 246#ifdef MAC 247 mac_netinet_arp_send(ifp, m); 248#endif 249 ah->ar_pro = htons(ETHERTYPE_IP); 250 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 251 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 252 ah->ar_op = htons(ARPOP_REQUEST); 253 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 254 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 255 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 256 sa.sa_family = AF_ARP; 257 sa.sa_len = 2; 258 m->m_flags |= M_BCAST; 259 (*ifp->if_output)(ifp, m, &sa, NULL); 260 ARPSTAT_INC(txrequests); 261} 262 263/* 264 * Resolve an IP address into an ethernet address. 265 * On input: 266 * ifp is the interface we use 267 * rt0 is the route to the final destination (possibly useless) 268 * m is the mbuf. May be NULL if we don't have a packet. 269 * dst is the next hop, 270 * desten is where we want the address. 271 * 272 * On success, desten is filled in and the function returns 0; 273 * If the packet must be held pending resolution, we return EWOULDBLOCK 274 * On other errors, we return the corresponding error code. 275 * Note that m_freem() handles NULL. 276 */ 277int 278arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 279 struct sockaddr *dst, u_char *desten, struct llentry **lle) 280{ 281 struct llentry *la = 0; 282 u_int flags = 0; 283 struct mbuf *curr = NULL; 284 struct mbuf *next = NULL; 285 int error, renew; 286 287 *lle = NULL; 288 if (m != NULL) { 289 if (m->m_flags & M_BCAST) { 290 /* broadcast */ 291 (void)memcpy(desten, 292 ifp->if_broadcastaddr, ifp->if_addrlen); 293 return (0); 294 } 295 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 296 /* multicast */ 297 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 298 return (0); 299 } 300 } 301retry: 302 IF_AFDATA_RLOCK(ifp); 303 la = lla_lookup(LLTABLE(ifp), flags, dst); 304 IF_AFDATA_RUNLOCK(ifp); 305 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 306 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 307 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 308 IF_AFDATA_WLOCK(ifp); 309 la = lla_lookup(LLTABLE(ifp), flags, dst); 310 IF_AFDATA_WUNLOCK(ifp); 311 } 312 if (la == NULL) { 313 if (flags & LLE_CREATE) 314 log(LOG_DEBUG, 315 "arpresolve: can't allocate llinfo for %s\n", 316 inet_ntoa(SIN(dst)->sin_addr)); 317 m_freem(m); 318 return (EINVAL); 319 } 320 321 if ((la->la_flags & LLE_VALID) && 322 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 323 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 324 /* 325 * If entry has an expiry time and it is approaching, 326 * see if we need to send an ARP request within this 327 * arpt_down interval. 328 */ 329 if (!(la->la_flags & LLE_STATIC) && 330 time_uptime + la->la_preempt > la->la_expire) { 331 arprequest(ifp, NULL, 332 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 333 334 la->la_preempt--; 335 } 336 337 *lle = la; 338 error = 0; 339 goto done; 340 } 341 342 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 343 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 344 inet_ntoa(SIN(dst)->sin_addr)); 345 m_freem(m); 346 error = EINVAL; 347 goto done; 348 } 349 350 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 351 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 352 flags |= LLE_EXCLUSIVE; 353 LLE_RUNLOCK(la); 354 goto retry; 355 } 356 /* 357 * There is an arptab entry, but no ethernet address 358 * response yet. Add the mbuf to the list, dropping 359 * the oldest packet if we have exceeded the system 360 * setting. 361 */ 362 if (m != NULL) { 363 if (la->la_numheld >= V_arp_maxhold) { 364 if (la->la_hold != NULL) { 365 next = la->la_hold->m_nextpkt; 366 m_freem(la->la_hold); 367 la->la_hold = next; 368 la->la_numheld--; 369 ARPSTAT_INC(dropped); 370 } 371 } 372 if (la->la_hold != NULL) { 373 curr = la->la_hold; 374 while (curr->m_nextpkt != NULL) 375 curr = curr->m_nextpkt; 376 curr->m_nextpkt = m; 377 } else 378 la->la_hold = m; 379 la->la_numheld++; 380 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 381 flags &= ~LLE_EXCLUSIVE; 382 LLE_DOWNGRADE(la); 383 } 384 385 } 386 /* 387 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 388 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 389 * if we have already sent arp_maxtries ARP requests. Retransmit the 390 * ARP request, but not faster than one request per second. 391 */ 392 if (la->la_asked < V_arp_maxtries) 393 error = EWOULDBLOCK; /* First request. */ 394 else 395 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 396 EHOSTUNREACH : EHOSTDOWN; 397 398 if (renew) { 399 int canceled; 400 401 LLE_ADDREF(la); 402 la->la_expire = time_uptime; 403 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 404 arptimer, la); 405 if (canceled) 406 LLE_REMREF(la); 407 la->la_asked++; 408 LLE_WUNLOCK(la); 409 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 410 IF_LLADDR(ifp)); 411 return (error); 412 } 413done: 414 if (flags & LLE_EXCLUSIVE) 415 LLE_WUNLOCK(la); 416 else 417 LLE_RUNLOCK(la); 418 return (error); 419} 420 421/* 422 * Common length and type checks are done here, 423 * then the protocol-specific routine is called. 424 */ 425static void 426arpintr(struct mbuf *m) 427{ 428 struct arphdr *ar; 429 430 if (m->m_len < sizeof(struct arphdr) && 431 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 432 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 433 return; 434 } 435 ar = mtod(m, struct arphdr *); 436 437 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 438 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 439 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 440 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 441 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 442 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 443 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 444 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 445 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 446 m_freem(m); 447 return; 448 } 449 450 if (m->m_len < arphdr_len(ar)) { 451 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 452 log(LOG_NOTICE, "arp: runt packet\n"); 453 m_freem(m); 454 return; 455 } 456 ar = mtod(m, struct arphdr *); 457 } 458 459 ARPSTAT_INC(received); 460 switch (ntohs(ar->ar_pro)) { 461#ifdef INET 462 case ETHERTYPE_IP: 463 in_arpinput(m); 464 return; 465#endif 466 } 467 m_freem(m); 468} 469 470#ifdef INET 471/* 472 * ARP for Internet protocols on 10 Mb/s Ethernet. 473 * Algorithm is that given in RFC 826. 474 * In addition, a sanity check is performed on the sender 475 * protocol address, to catch impersonators. 476 * We no longer handle negotiations for use of trailer protocol: 477 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 478 * along with IP replies if we wanted trailers sent to us, 479 * and also sent them in response to IP replies. 480 * This allowed either end to announce the desire to receive 481 * trailer packets. 482 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 483 * but formerly didn't normally send requests. 484 */ 485static int log_arp_wrong_iface = 1; 486static int log_arp_movements = 1; 487static int log_arp_permanent_modify = 1; 488 489SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 490 &log_arp_wrong_iface, 0, 491 "log arp packets arriving on the wrong interface"); 492SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 493 &log_arp_movements, 0, 494 "log arp replies from MACs different than the one in the cache"); 495SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 496 &log_arp_permanent_modify, 0, 497 "log arp replies from MACs different than the one in the permanent arp entry"); 498 499 500static void 501in_arpinput(struct mbuf *m) 502{ 503 struct arphdr *ah; 504 struct ifnet *ifp = m->m_pkthdr.rcvif; 505 struct llentry *la = NULL; 506 struct rtentry *rt; 507 struct ifaddr *ifa; 508 struct in_ifaddr *ia; 509 struct sockaddr sa; 510 struct in_addr isaddr, itaddr, myaddr; 511 u_int8_t *enaddr = NULL; 512 int op, flags; 513 int req_len; 514 int bridged = 0, is_bridge = 0; 515 int carped; 516 struct sockaddr_in sin; 517 sin.sin_len = sizeof(struct sockaddr_in); 518 sin.sin_family = AF_INET; 519 sin.sin_addr.s_addr = 0; 520 521 if (ifp->if_bridge) 522 bridged = 1; 523 if (ifp->if_type == IFT_BRIDGE) 524 is_bridge = 1; 525 526 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 527 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 528 log(LOG_NOTICE, "in_arp: runt packet -- m_pullup failed\n"); 529 return; 530 } 531 532 ah = mtod(m, struct arphdr *); 533 /* 534 * ARP is only for IPv4 so we can reject packets with 535 * a protocol length not equal to an IPv4 address. 536 */ 537 if (ah->ar_pln != sizeof(struct in_addr)) { 538 log(LOG_NOTICE, "in_arp: requested protocol length != %zu\n", 539 sizeof(struct in_addr)); 540 return; 541 } 542 543 if (ETHER_IS_MULTICAST(ar_sha(ah))) { 544 log(LOG_NOTICE, "in_arp: %*D is multicast\n", 545 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 546 return; 547 } 548 549 op = ntohs(ah->ar_op); 550 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 551 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 552 553 if (op == ARPOP_REPLY) 554 ARPSTAT_INC(rxreplies); 555 556 /* 557 * For a bridge, we want to check the address irrespective 558 * of the receive interface. (This will change slightly 559 * when we have clusters of interfaces). 560 */ 561 IN_IFADDR_RLOCK(); 562 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 563 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 564 ia->ia_ifp == ifp) && 565 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 566 (ia->ia_ifa.ifa_carp == NULL || 567 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 568 ifa_ref(&ia->ia_ifa); 569 IN_IFADDR_RUNLOCK(); 570 goto match; 571 } 572 } 573 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 574 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 575 ia->ia_ifp == ifp) && 576 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 577 ifa_ref(&ia->ia_ifa); 578 IN_IFADDR_RUNLOCK(); 579 goto match; 580 } 581 582#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 583 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 584 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 585 addr == ia->ia_addr.sin_addr.s_addr) 586 /* 587 * Check the case when bridge shares its MAC address with 588 * some of its children, so packets are claimed by bridge 589 * itself (bridge_input() does it first), but they are really 590 * meant to be destined to the bridge member. 591 */ 592 if (is_bridge) { 593 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 594 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 595 ifa_ref(&ia->ia_ifa); 596 ifp = ia->ia_ifp; 597 IN_IFADDR_RUNLOCK(); 598 goto match; 599 } 600 } 601 } 602#undef BDG_MEMBER_MATCHES_ARP 603 IN_IFADDR_RUNLOCK(); 604 605 /* 606 * No match, use the first inet address on the receive interface 607 * as a dummy address for the rest of the function. 608 */ 609 IF_ADDR_RLOCK(ifp); 610 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 611 if (ifa->ifa_addr->sa_family == AF_INET && 612 (ifa->ifa_carp == NULL || 613 (*carp_iamatch_p)(ifa, &enaddr))) { 614 ia = ifatoia(ifa); 615 ifa_ref(ifa); 616 IF_ADDR_RUNLOCK(ifp); 617 goto match; 618 } 619 IF_ADDR_RUNLOCK(ifp); 620 621 /* 622 * If bridging, fall back to using any inet address. 623 */ 624 IN_IFADDR_RLOCK(); 625 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 626 IN_IFADDR_RUNLOCK(); 627 goto drop; 628 } 629 ifa_ref(&ia->ia_ifa); 630 IN_IFADDR_RUNLOCK(); 631match: 632 if (!enaddr) 633 enaddr = (u_int8_t *)IF_LLADDR(ifp); 634 carped = (ia->ia_ifa.ifa_carp != NULL); 635 myaddr = ia->ia_addr.sin_addr; 636 ifa_free(&ia->ia_ifa); 637 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 638 goto drop; /* it's from me, ignore it. */ 639 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 640 log(LOG_NOTICE, 641 "arp: link address is broadcast for IP address %s!\n", 642 inet_ntoa(isaddr)); 643 goto drop; 644 } 645 /* 646 * Warn if another host is using the same IP address, but only if the 647 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 648 * case we suppress the warning to avoid false positive complaints of 649 * potential misconfiguration. 650 */ 651 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 652 myaddr.s_addr != 0) { 653 log(LOG_ERR, "arp: %*D is using my IP address %s on %s!\n", 654 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 655 inet_ntoa(isaddr), ifp->if_xname); 656 itaddr = myaddr; 657 ARPSTAT_INC(dupips); 658 goto reply; 659 } 660 if (ifp->if_flags & IFF_STATICARP) 661 goto reply; 662 663 bzero(&sin, sizeof(sin)); 664 sin.sin_len = sizeof(struct sockaddr_in); 665 sin.sin_family = AF_INET; 666 sin.sin_addr = isaddr; 667 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 668 flags |= LLE_EXCLUSIVE; 669 IF_AFDATA_LOCK(ifp); 670 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 671 IF_AFDATA_UNLOCK(ifp); 672 if (la != NULL) { 673 /* the following is not an error when doing bridging */ 674 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 675 if (log_arp_wrong_iface) 676 log(LOG_WARNING, "arp: %s is on %s " 677 "but got reply from %*D on %s\n", 678 inet_ntoa(isaddr), 679 la->lle_tbl->llt_ifp->if_xname, 680 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 681 ifp->if_xname); 682 LLE_WUNLOCK(la); 683 goto reply; 684 } 685 if ((la->la_flags & LLE_VALID) && 686 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 687 if (la->la_flags & LLE_STATIC) { 688 LLE_WUNLOCK(la); 689 if (log_arp_permanent_modify) 690 log(LOG_ERR, 691 "arp: %*D attempts to modify " 692 "permanent entry for %s on %s\n", 693 ifp->if_addrlen, 694 (u_char *)ar_sha(ah), ":", 695 inet_ntoa(isaddr), ifp->if_xname); 696 goto reply; 697 } 698 if (log_arp_movements) { 699 log(LOG_INFO, "arp: %s moved from %*D " 700 "to %*D on %s\n", 701 inet_ntoa(isaddr), 702 ifp->if_addrlen, 703 (u_char *)&la->ll_addr, ":", 704 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 705 ifp->if_xname); 706 } 707 } 708 709 if (ifp->if_addrlen != ah->ar_hln) { 710 LLE_WUNLOCK(la); 711 log(LOG_WARNING, "arp from %*D: addr len: new %d, " 712 "i/f %d (ignored)\n", ifp->if_addrlen, 713 (u_char *) ar_sha(ah), ":", ah->ar_hln, 714 ifp->if_addrlen); 715 goto drop; 716 } 717 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 718 la->la_flags |= LLE_VALID; 719 720 EVENTHANDLER_INVOKE(arp_update_event, la); 721 722 if (!(la->la_flags & LLE_STATIC)) { 723 int canceled; 724 725 LLE_ADDREF(la); 726 la->la_expire = time_uptime + V_arpt_keep; 727 canceled = callout_reset(&la->la_timer, 728 hz * V_arpt_keep, arptimer, la); 729 if (canceled) 730 LLE_REMREF(la); 731 } 732 la->la_asked = 0; 733 la->la_preempt = V_arp_maxtries; 734 /* 735 * The packets are all freed within the call to the output 736 * routine. 737 * 738 * NB: The lock MUST be released before the call to the 739 * output routine. 740 */ 741 if (la->la_hold != NULL) { 742 struct mbuf *m_hold, *m_hold_next; 743 744 m_hold = la->la_hold; 745 la->la_hold = NULL; 746 la->la_numheld = 0; 747 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 748 LLE_WUNLOCK(la); 749 for (; m_hold != NULL; m_hold = m_hold_next) { 750 m_hold_next = m_hold->m_nextpkt; 751 m_hold->m_nextpkt = NULL; 752 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 753 } 754 } else 755 LLE_WUNLOCK(la); 756 } 757reply: 758 if (op != ARPOP_REQUEST) 759 goto drop; 760 ARPSTAT_INC(rxrequests); 761 762 if (itaddr.s_addr == myaddr.s_addr) { 763 /* Shortcut.. the receiving interface is the target. */ 764 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 765 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 766 } else { 767 struct llentry *lle = NULL; 768 769 sin.sin_addr = itaddr; 770 IF_AFDATA_LOCK(ifp); 771 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 772 IF_AFDATA_UNLOCK(ifp); 773 774 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 775 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 776 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 777 LLE_RUNLOCK(lle); 778 } else { 779 780 if (lle != NULL) 781 LLE_RUNLOCK(lle); 782 783 if (!V_arp_proxyall) 784 goto drop; 785 786 sin.sin_addr = itaddr; 787 /* XXX MRT use table 0 for arp reply */ 788 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 789 if (!rt) 790 goto drop; 791 792 /* 793 * Don't send proxies for nodes on the same interface 794 * as this one came out of, or we'll get into a fight 795 * over who claims what Ether address. 796 */ 797 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 798 RTFREE_LOCKED(rt); 799 goto drop; 800 } 801 RTFREE_LOCKED(rt); 802 803 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 804 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 805 806 /* 807 * Also check that the node which sent the ARP packet 808 * is on the interface we expect it to be on. This 809 * avoids ARP chaos if an interface is connected to the 810 * wrong network. 811 */ 812 sin.sin_addr = isaddr; 813 814 /* XXX MRT use table 0 for arp checks */ 815 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 816 if (!rt) 817 goto drop; 818 if (rt->rt_ifp != ifp) { 819 log(LOG_INFO, "arp_proxy: ignoring request" 820 " from %s via %s, expecting %s\n", 821 inet_ntoa(isaddr), ifp->if_xname, 822 rt->rt_ifp->if_xname); 823 RTFREE_LOCKED(rt); 824 goto drop; 825 } 826 RTFREE_LOCKED(rt); 827 828#ifdef DEBUG_PROXY 829 printf("arp: proxying for %s\n", 830 inet_ntoa(itaddr)); 831#endif 832 } 833 } 834 835 if (itaddr.s_addr == myaddr.s_addr && 836 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 837 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 838#ifdef DEBUG_LINKLOCAL 839 printf("arp: sending reply for link-local addr %s\n", 840 inet_ntoa(itaddr)); 841#endif 842 m->m_flags |= M_BCAST; 843 m->m_flags &= ~M_MCAST; 844 } else { 845 /* default behaviour; never reply by broadcast. */ 846 m->m_flags &= ~(M_BCAST|M_MCAST); 847 } 848 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 849 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 850 ah->ar_op = htons(ARPOP_REPLY); 851 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 852 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 853 m->m_pkthdr.len = m->m_len; 854 m->m_pkthdr.rcvif = NULL; 855 sa.sa_family = AF_ARP; 856 sa.sa_len = 2; 857 (*ifp->if_output)(ifp, m, &sa, NULL); 858 ARPSTAT_INC(txreplies); 859 return; 860 861drop: 862 m_freem(m); 863} 864#endif 865 866void 867arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 868{ 869 struct llentry *lle; 870 871 if (ifa->ifa_carp != NULL) 872 return; 873 874 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 875 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 876 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 877 /* 878 * interface address is considered static entry 879 * because the output of the arp utility shows 880 * that L2 entry as permanent 881 */ 882 IF_AFDATA_LOCK(ifp); 883 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 884 (struct sockaddr *)IA_SIN(ifa)); 885 IF_AFDATA_UNLOCK(ifp); 886 if (lle == NULL) 887 log(LOG_INFO, "arp_ifinit: cannot create arp " 888 "entry for interface address\n"); 889 else 890 LLE_RUNLOCK(lle); 891 } 892 ifa->ifa_rtrequest = NULL; 893} 894 895void 896arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 897{ 898 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 899 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 900 &IA_SIN(ifa)->sin_addr, enaddr); 901 ifa->ifa_rtrequest = NULL; 902} 903 904static void 905arp_init(void) 906{ 907 908 netisr_register(&arp_nh); 909} 910SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 911