if_ether.c revision 228571
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 228571 2011-12-16 12:16:56Z 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); 126void arprequest(struct ifnet *, 127 struct in_addr *, struct in_addr *, u_char *); 128static void arpintr(struct mbuf *); 129static void arptimer(void *); 130#ifdef INET 131static void in_arpinput(struct mbuf *); 132#endif 133 134static 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/* 143 * called by in_ifscrub to remove entry from the table when 144 * the interface goes away 145 */ 146void 147arp_ifscrub(struct ifnet *ifp, uint32_t addr) 148{ 149 struct sockaddr_in addr4; 150 151 bzero((void *)&addr4, sizeof(addr4)); 152 addr4.sin_len = sizeof(addr4); 153 addr4.sin_family = AF_INET; 154 addr4.sin_addr.s_addr = addr; 155 IF_AFDATA_LOCK(ifp); 156 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 157 (struct sockaddr *)&addr4); 158 IF_AFDATA_UNLOCK(ifp); 159} 160#endif 161 162/* 163 * Timeout routine. Age arp_tab entries periodically. 164 */ 165static void 166arptimer(void *arg) 167{ 168 struct ifnet *ifp; 169 struct llentry *lle; 170 int pkts_dropped; 171 172 KASSERT(arg != NULL, ("%s: arg NULL", __func__)); 173 lle = (struct llentry *)arg; 174 ifp = lle->lle_tbl->llt_ifp; 175 CURVNET_SET(ifp->if_vnet); 176 IF_AFDATA_LOCK(ifp); 177 LLE_WLOCK(lle); 178 if (lle->la_flags & LLE_STATIC) 179 LLE_WUNLOCK(lle); 180 else { 181 if (!callout_pending(&lle->la_timer) && 182 callout_active(&lle->la_timer)) { 183 callout_stop(&lle->la_timer); 184 LLE_REMREF(lle); 185 pkts_dropped = llentry_free(lle); 186 ARPSTAT_ADD(dropped, pkts_dropped); 187 ARPSTAT_INC(timeouts); 188 } else { 189#ifdef DIAGNOSTIC 190 struct sockaddr *l3addr = L3_ADDR(lle); 191 log(LOG_INFO, 192 "arptimer issue: %p, IPv4 address: \"%s\"\n", lle, 193 inet_ntoa( 194 ((const struct sockaddr_in *)l3addr)->sin_addr)); 195#endif 196 LLE_WUNLOCK(lle); 197 } 198 } 199 IF_AFDATA_UNLOCK(ifp); 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; 216 217 if (sip == NULL) { 218 /* XXX don't believe this can happen (or explain why) */ 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 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 226 if (!ifa->ifa_addr || 227 ifa->ifa_addr->sa_family != AF_INET) 228 continue; 229 sip = &SIN(ifa->ifa_addr)->sin_addr; 230 if (0 == ((sip->s_addr ^ tip->s_addr) & 231 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 232 break; /* found it. */ 233 } 234 if (sip == NULL) { 235 printf("%s: cannot find matching address\n", __func__); 236 return; 237 } 238 } 239 240 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 241 return; 242 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 243 2*ifp->if_data.ifi_addrlen; 244 m->m_pkthdr.len = m->m_len; 245 MH_ALIGN(m, m->m_len); 246 ah = mtod(m, struct arphdr *); 247 bzero((caddr_t)ah, m->m_len); 248#ifdef MAC 249 mac_netinet_arp_send(ifp, m); 250#endif 251 ah->ar_pro = htons(ETHERTYPE_IP); 252 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 253 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 254 ah->ar_op = htons(ARPOP_REQUEST); 255 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 256 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 257 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 258 sa.sa_family = AF_ARP; 259 sa.sa_len = 2; 260 m->m_flags |= M_BCAST; 261 (*ifp->if_output)(ifp, m, &sa, NULL); 262 ARPSTAT_INC(txrequests); 263} 264 265/* 266 * Resolve an IP address into an ethernet address. 267 * On input: 268 * ifp is the interface we use 269 * rt0 is the route to the final destination (possibly useless) 270 * m is the mbuf. May be NULL if we don't have a packet. 271 * dst is the next hop, 272 * desten is where we want the address. 273 * 274 * On success, desten is filled in and the function returns 0; 275 * If the packet must be held pending resolution, we return EWOULDBLOCK 276 * On other errors, we return the corresponding error code. 277 * Note that m_freem() handles NULL. 278 */ 279int 280arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 281 struct sockaddr *dst, u_char *desten, struct llentry **lle) 282{ 283 struct llentry *la = 0; 284 u_int flags = 0; 285 struct mbuf *curr = NULL; 286 struct mbuf *next = NULL; 287 int error, renew; 288 289 *lle = NULL; 290 if (m != NULL) { 291 if (m->m_flags & M_BCAST) { 292 /* broadcast */ 293 (void)memcpy(desten, 294 ifp->if_broadcastaddr, ifp->if_addrlen); 295 return (0); 296 } 297 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 298 /* multicast */ 299 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 300 return (0); 301 } 302 } 303retry: 304 IF_AFDATA_RLOCK(ifp); 305 la = lla_lookup(LLTABLE(ifp), flags, dst); 306 IF_AFDATA_RUNLOCK(ifp); 307 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 308 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 309 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 310 IF_AFDATA_WLOCK(ifp); 311 la = lla_lookup(LLTABLE(ifp), flags, dst); 312 IF_AFDATA_WUNLOCK(ifp); 313 } 314 if (la == NULL) { 315 if (flags & LLE_CREATE) 316 log(LOG_DEBUG, 317 "arpresolve: can't allocate llinfo for %s\n", 318 inet_ntoa(SIN(dst)->sin_addr)); 319 m_freem(m); 320 return (EINVAL); 321 } 322 323 if ((la->la_flags & LLE_VALID) && 324 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 325 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 326 /* 327 * If entry has an expiry time and it is approaching, 328 * see if we need to send an ARP request within this 329 * arpt_down interval. 330 */ 331 if (!(la->la_flags & LLE_STATIC) && 332 time_uptime + la->la_preempt > la->la_expire) { 333 arprequest(ifp, NULL, 334 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 335 336 la->la_preempt--; 337 } 338 339 *lle = la; 340 error = 0; 341 goto done; 342 } 343 344 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 345 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 346 inet_ntoa(SIN(dst)->sin_addr)); 347 m_freem(m); 348 error = EINVAL; 349 goto done; 350 } 351 352 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 353 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 354 flags |= LLE_EXCLUSIVE; 355 LLE_RUNLOCK(la); 356 goto retry; 357 } 358 /* 359 * There is an arptab entry, but no ethernet address 360 * response yet. Add the mbuf to the list, dropping 361 * the oldest packet if we have exceeded the system 362 * setting. 363 */ 364 if (m != NULL) { 365 if (la->la_numheld >= V_arp_maxhold) { 366 if (la->la_hold != NULL) { 367 next = la->la_hold->m_nextpkt; 368 m_freem(la->la_hold); 369 la->la_hold = next; 370 la->la_numheld--; 371 ARPSTAT_INC(dropped); 372 } 373 } 374 if (la->la_hold != NULL) { 375 curr = la->la_hold; 376 while (curr->m_nextpkt != NULL) 377 curr = curr->m_nextpkt; 378 curr->m_nextpkt = m; 379 } else 380 la->la_hold = m; 381 la->la_numheld++; 382 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 383 flags &= ~LLE_EXCLUSIVE; 384 LLE_DOWNGRADE(la); 385 } 386 387 } 388 /* 389 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 390 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 391 * if we have already sent arp_maxtries ARP requests. Retransmit the 392 * ARP request, but not faster than one request per second. 393 */ 394 if (la->la_asked < V_arp_maxtries) 395 error = EWOULDBLOCK; /* First request. */ 396 else 397 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 398 EHOSTUNREACH : EHOSTDOWN; 399 400 if (renew) { 401 int canceled; 402 403 LLE_ADDREF(la); 404 la->la_expire = time_uptime; 405 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 406 arptimer, la); 407 if (canceled) 408 LLE_REMREF(la); 409 la->la_asked++; 410 LLE_WUNLOCK(la); 411 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 412 IF_LLADDR(ifp)); 413 return (error); 414 } 415done: 416 if (flags & LLE_EXCLUSIVE) 417 LLE_WUNLOCK(la); 418 else 419 LLE_RUNLOCK(la); 420 return (error); 421} 422 423/* 424 * Common length and type checks are done here, 425 * then the protocol-specific routine is called. 426 */ 427static void 428arpintr(struct mbuf *m) 429{ 430 struct arphdr *ar; 431 432 if (m->m_len < sizeof(struct arphdr) && 433 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 434 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 435 return; 436 } 437 ar = mtod(m, struct arphdr *); 438 439 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 440 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 441 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 442 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 443 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 444 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 445 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 446 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 447 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 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_NOTICE, "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 */ 487static int log_arp_wrong_iface = 1; 488static int log_arp_movements = 1; 489static int log_arp_permanent_modify = 1; 490 491SYSCTL_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"); 494SYSCTL_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"); 497SYSCTL_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 502static void 503in_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 carped; 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_NOTICE, "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_NOTICE, "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_NOTICE, "in_arp: %*D is multicast\n", 547 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 548 return; 549 } 550 551 op = ntohs(ah->ar_op); 552 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 553 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 554 555 if (op == ARPOP_REPLY) 556 ARPSTAT_INC(rxreplies); 557 558 /* 559 * For a bridge, we want to check the address irrespective 560 * of the receive interface. (This will change slightly 561 * when we have clusters of interfaces). 562 */ 563 IN_IFADDR_RLOCK(); 564 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 565 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 566 ia->ia_ifp == ifp) && 567 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 568 (ia->ia_ifa.ifa_carp == NULL || 569 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 570 ifa_ref(&ia->ia_ifa); 571 IN_IFADDR_RUNLOCK(); 572 goto match; 573 } 574 } 575 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 576 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 577 ia->ia_ifp == ifp) && 578 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 579 ifa_ref(&ia->ia_ifa); 580 IN_IFADDR_RUNLOCK(); 581 goto match; 582 } 583 584#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 585 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 586 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 587 addr == ia->ia_addr.sin_addr.s_addr) 588 /* 589 * Check the case when bridge shares its MAC address with 590 * some of its children, so packets are claimed by bridge 591 * itself (bridge_input() does it first), but they are really 592 * meant to be destined to the bridge member. 593 */ 594 if (is_bridge) { 595 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 596 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 597 ifa_ref(&ia->ia_ifa); 598 ifp = ia->ia_ifp; 599 IN_IFADDR_RUNLOCK(); 600 goto match; 601 } 602 } 603 } 604#undef BDG_MEMBER_MATCHES_ARP 605 IN_IFADDR_RUNLOCK(); 606 607 /* 608 * No match, use the first inet address on the receive interface 609 * as a dummy address for the rest of the function. 610 */ 611 IF_ADDR_LOCK(ifp); 612 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 613 if (ifa->ifa_addr->sa_family == AF_INET) { 614 ia = ifatoia(ifa); 615 ifa_ref(ifa); 616 IF_ADDR_UNLOCK(ifp); 617 goto match; 618 } 619 IF_ADDR_UNLOCK(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