if_ether.c revision 229816
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 229816 2012-01-08 17:25:15Z 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 u_char *carpaddr = NULL; 215 216 if (sip == NULL) { 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 IF_ADDR_RLOCK(ifp); 224 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 225 if (ifa->ifa_addr->sa_family != AF_INET) 226 continue; 227 228 if (ifa->ifa_carp) { 229 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 230 continue; 231 sip = &IA_SIN(ifa)->sin_addr; 232 } else { 233 carpaddr = NULL; 234 sip = &IA_SIN(ifa)->sin_addr; 235 } 236 237 if (0 == ((sip->s_addr ^ tip->s_addr) & 238 IA_MASKSIN(ifa)->sin_addr.s_addr)) 239 break; /* found it. */ 240 } 241 IF_ADDR_RUNLOCK(ifp); 242 if (sip == NULL) { 243 printf("%s: cannot find matching address\n", __func__); 244 return; 245 } 246 } 247 if (enaddr == NULL) 248 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 249 250 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 251 return; 252 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 253 2*ifp->if_data.ifi_addrlen; 254 m->m_pkthdr.len = m->m_len; 255 MH_ALIGN(m, m->m_len); 256 ah = mtod(m, struct arphdr *); 257 bzero((caddr_t)ah, m->m_len); 258#ifdef MAC 259 mac_netinet_arp_send(ifp, m); 260#endif 261 ah->ar_pro = htons(ETHERTYPE_IP); 262 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 263 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 264 ah->ar_op = htons(ARPOP_REQUEST); 265 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 266 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 267 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 268 sa.sa_family = AF_ARP; 269 sa.sa_len = 2; 270 m->m_flags |= M_BCAST; 271 (*ifp->if_output)(ifp, m, &sa, NULL); 272 ARPSTAT_INC(txrequests); 273} 274 275/* 276 * Resolve an IP address into an ethernet address. 277 * On input: 278 * ifp is the interface we use 279 * rt0 is the route to the final destination (possibly useless) 280 * m is the mbuf. May be NULL if we don't have a packet. 281 * dst is the next hop, 282 * desten is where we want the address. 283 * 284 * On success, desten is filled in and the function returns 0; 285 * If the packet must be held pending resolution, we return EWOULDBLOCK 286 * On other errors, we return the corresponding error code. 287 * Note that m_freem() handles NULL. 288 */ 289int 290arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 291 struct sockaddr *dst, u_char *desten, struct llentry **lle) 292{ 293 struct llentry *la = 0; 294 u_int flags = 0; 295 struct mbuf *curr = NULL; 296 struct mbuf *next = NULL; 297 int error, renew; 298 299 *lle = NULL; 300 if (m != NULL) { 301 if (m->m_flags & M_BCAST) { 302 /* broadcast */ 303 (void)memcpy(desten, 304 ifp->if_broadcastaddr, ifp->if_addrlen); 305 return (0); 306 } 307 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 308 /* multicast */ 309 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 310 return (0); 311 } 312 } 313retry: 314 IF_AFDATA_RLOCK(ifp); 315 la = lla_lookup(LLTABLE(ifp), flags, dst); 316 IF_AFDATA_RUNLOCK(ifp); 317 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 318 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 319 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 320 IF_AFDATA_WLOCK(ifp); 321 la = lla_lookup(LLTABLE(ifp), flags, dst); 322 IF_AFDATA_WUNLOCK(ifp); 323 } 324 if (la == NULL) { 325 if (flags & LLE_CREATE) 326 log(LOG_DEBUG, 327 "arpresolve: can't allocate llinfo for %s\n", 328 inet_ntoa(SIN(dst)->sin_addr)); 329 m_freem(m); 330 return (EINVAL); 331 } 332 333 if ((la->la_flags & LLE_VALID) && 334 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 335 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 336 /* 337 * If entry has an expiry time and it is approaching, 338 * see if we need to send an ARP request within this 339 * arpt_down interval. 340 */ 341 if (!(la->la_flags & LLE_STATIC) && 342 time_uptime + la->la_preempt > la->la_expire) { 343 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 344 la->la_preempt--; 345 } 346 347 *lle = la; 348 error = 0; 349 goto done; 350 } 351 352 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 353 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 354 inet_ntoa(SIN(dst)->sin_addr)); 355 m_freem(m); 356 error = EINVAL; 357 goto done; 358 } 359 360 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 361 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 362 flags |= LLE_EXCLUSIVE; 363 LLE_RUNLOCK(la); 364 goto retry; 365 } 366 /* 367 * There is an arptab entry, but no ethernet address 368 * response yet. Add the mbuf to the list, dropping 369 * the oldest packet if we have exceeded the system 370 * setting. 371 */ 372 if (m != NULL) { 373 if (la->la_numheld >= V_arp_maxhold) { 374 if (la->la_hold != NULL) { 375 next = la->la_hold->m_nextpkt; 376 m_freem(la->la_hold); 377 la->la_hold = next; 378 la->la_numheld--; 379 ARPSTAT_INC(dropped); 380 } 381 } 382 if (la->la_hold != NULL) { 383 curr = la->la_hold; 384 while (curr->m_nextpkt != NULL) 385 curr = curr->m_nextpkt; 386 curr->m_nextpkt = m; 387 } else 388 la->la_hold = m; 389 la->la_numheld++; 390 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 391 flags &= ~LLE_EXCLUSIVE; 392 LLE_DOWNGRADE(la); 393 } 394 395 } 396 /* 397 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 398 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 399 * if we have already sent arp_maxtries ARP requests. Retransmit the 400 * ARP request, but not faster than one request per second. 401 */ 402 if (la->la_asked < V_arp_maxtries) 403 error = EWOULDBLOCK; /* First request. */ 404 else 405 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 406 EHOSTUNREACH : EHOSTDOWN; 407 408 if (renew) { 409 int canceled; 410 411 LLE_ADDREF(la); 412 la->la_expire = time_uptime; 413 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 414 arptimer, la); 415 if (canceled) 416 LLE_REMREF(la); 417 la->la_asked++; 418 LLE_WUNLOCK(la); 419 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 420 return (error); 421 } 422done: 423 if (flags & LLE_EXCLUSIVE) 424 LLE_WUNLOCK(la); 425 else 426 LLE_RUNLOCK(la); 427 return (error); 428} 429 430/* 431 * Common length and type checks are done here, 432 * then the protocol-specific routine is called. 433 */ 434static void 435arpintr(struct mbuf *m) 436{ 437 struct arphdr *ar; 438 439 if (m->m_len < sizeof(struct arphdr) && 440 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 441 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 442 return; 443 } 444 ar = mtod(m, struct arphdr *); 445 446 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 447 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 448 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 449 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 450 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 451 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 452 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 453 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 454 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 455 m_freem(m); 456 return; 457 } 458 459 if (m->m_len < arphdr_len(ar)) { 460 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 461 log(LOG_NOTICE, "arp: runt packet\n"); 462 m_freem(m); 463 return; 464 } 465 ar = mtod(m, struct arphdr *); 466 } 467 468 ARPSTAT_INC(received); 469 switch (ntohs(ar->ar_pro)) { 470#ifdef INET 471 case ETHERTYPE_IP: 472 in_arpinput(m); 473 return; 474#endif 475 } 476 m_freem(m); 477} 478 479#ifdef INET 480/* 481 * ARP for Internet protocols on 10 Mb/s Ethernet. 482 * Algorithm is that given in RFC 826. 483 * In addition, a sanity check is performed on the sender 484 * protocol address, to catch impersonators. 485 * We no longer handle negotiations for use of trailer protocol: 486 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 487 * along with IP replies if we wanted trailers sent to us, 488 * and also sent them in response to IP replies. 489 * This allowed either end to announce the desire to receive 490 * trailer packets. 491 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 492 * but formerly didn't normally send requests. 493 */ 494static int log_arp_wrong_iface = 1; 495static int log_arp_movements = 1; 496static int log_arp_permanent_modify = 1; 497 498SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 499 &log_arp_wrong_iface, 0, 500 "log arp packets arriving on the wrong interface"); 501SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 502 &log_arp_movements, 0, 503 "log arp replies from MACs different than the one in the cache"); 504SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 505 &log_arp_permanent_modify, 0, 506 "log arp replies from MACs different than the one in the permanent arp entry"); 507 508 509static void 510in_arpinput(struct mbuf *m) 511{ 512 struct arphdr *ah; 513 struct ifnet *ifp = m->m_pkthdr.rcvif; 514 struct llentry *la = NULL; 515 struct rtentry *rt; 516 struct ifaddr *ifa; 517 struct in_ifaddr *ia; 518 struct sockaddr sa; 519 struct in_addr isaddr, itaddr, myaddr; 520 u_int8_t *enaddr = NULL; 521 int op, flags; 522 int req_len; 523 int bridged = 0, is_bridge = 0; 524 int carped; 525 struct sockaddr_in sin; 526 sin.sin_len = sizeof(struct sockaddr_in); 527 sin.sin_family = AF_INET; 528 sin.sin_addr.s_addr = 0; 529 530 if (ifp->if_bridge) 531 bridged = 1; 532 if (ifp->if_type == IFT_BRIDGE) 533 is_bridge = 1; 534 535 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 536 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 537 log(LOG_NOTICE, "in_arp: runt packet -- m_pullup failed\n"); 538 return; 539 } 540 541 ah = mtod(m, struct arphdr *); 542 /* 543 * ARP is only for IPv4 so we can reject packets with 544 * a protocol length not equal to an IPv4 address. 545 */ 546 if (ah->ar_pln != sizeof(struct in_addr)) { 547 log(LOG_NOTICE, "in_arp: requested protocol length != %zu\n", 548 sizeof(struct in_addr)); 549 return; 550 } 551 552 if (ETHER_IS_MULTICAST(ar_sha(ah))) { 553 log(LOG_NOTICE, "in_arp: %*D is multicast\n", 554 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 555 return; 556 } 557 558 op = ntohs(ah->ar_op); 559 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 560 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 561 562 if (op == ARPOP_REPLY) 563 ARPSTAT_INC(rxreplies); 564 565 /* 566 * For a bridge, we want to check the address irrespective 567 * of the receive interface. (This will change slightly 568 * when we have clusters of interfaces). 569 */ 570 IN_IFADDR_RLOCK(); 571 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 572 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 573 ia->ia_ifp == ifp) && 574 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 575 (ia->ia_ifa.ifa_carp == NULL || 576 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 577 ifa_ref(&ia->ia_ifa); 578 IN_IFADDR_RUNLOCK(); 579 goto match; 580 } 581 } 582 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 583 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 584 ia->ia_ifp == ifp) && 585 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 586 ifa_ref(&ia->ia_ifa); 587 IN_IFADDR_RUNLOCK(); 588 goto match; 589 } 590 591#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 592 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 593 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 594 addr == ia->ia_addr.sin_addr.s_addr) 595 /* 596 * Check the case when bridge shares its MAC address with 597 * some of its children, so packets are claimed by bridge 598 * itself (bridge_input() does it first), but they are really 599 * meant to be destined to the bridge member. 600 */ 601 if (is_bridge) { 602 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 603 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 604 ifa_ref(&ia->ia_ifa); 605 ifp = ia->ia_ifp; 606 IN_IFADDR_RUNLOCK(); 607 goto match; 608 } 609 } 610 } 611#undef BDG_MEMBER_MATCHES_ARP 612 IN_IFADDR_RUNLOCK(); 613 614 /* 615 * No match, use the first inet address on the receive interface 616 * as a dummy address for the rest of the function. 617 */ 618 IF_ADDR_RLOCK(ifp); 619 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 620 if (ifa->ifa_addr->sa_family == AF_INET && 621 (ifa->ifa_carp == NULL || 622 (*carp_iamatch_p)(ifa, &enaddr))) { 623 ia = ifatoia(ifa); 624 ifa_ref(ifa); 625 IF_ADDR_RUNLOCK(ifp); 626 goto match; 627 } 628 IF_ADDR_RUNLOCK(ifp); 629 630 /* 631 * If bridging, fall back to using any inet address. 632 */ 633 IN_IFADDR_RLOCK(); 634 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 635 IN_IFADDR_RUNLOCK(); 636 goto drop; 637 } 638 ifa_ref(&ia->ia_ifa); 639 IN_IFADDR_RUNLOCK(); 640match: 641 if (!enaddr) 642 enaddr = (u_int8_t *)IF_LLADDR(ifp); 643 carped = (ia->ia_ifa.ifa_carp != NULL); 644 myaddr = ia->ia_addr.sin_addr; 645 ifa_free(&ia->ia_ifa); 646 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 647 goto drop; /* it's from me, ignore it. */ 648 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 649 log(LOG_NOTICE, 650 "arp: link address is broadcast for IP address %s!\n", 651 inet_ntoa(isaddr)); 652 goto drop; 653 } 654 /* 655 * Warn if another host is using the same IP address, but only if the 656 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 657 * case we suppress the warning to avoid false positive complaints of 658 * potential misconfiguration. 659 */ 660 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 661 myaddr.s_addr != 0) { 662 log(LOG_ERR, "arp: %*D is using my IP address %s on %s!\n", 663 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 664 inet_ntoa(isaddr), ifp->if_xname); 665 itaddr = myaddr; 666 ARPSTAT_INC(dupips); 667 goto reply; 668 } 669 if (ifp->if_flags & IFF_STATICARP) 670 goto reply; 671 672 bzero(&sin, sizeof(sin)); 673 sin.sin_len = sizeof(struct sockaddr_in); 674 sin.sin_family = AF_INET; 675 sin.sin_addr = isaddr; 676 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 677 flags |= LLE_EXCLUSIVE; 678 IF_AFDATA_LOCK(ifp); 679 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 680 IF_AFDATA_UNLOCK(ifp); 681 if (la != NULL) { 682 /* the following is not an error when doing bridging */ 683 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 684 if (log_arp_wrong_iface) 685 log(LOG_WARNING, "arp: %s is on %s " 686 "but got reply from %*D on %s\n", 687 inet_ntoa(isaddr), 688 la->lle_tbl->llt_ifp->if_xname, 689 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 690 ifp->if_xname); 691 LLE_WUNLOCK(la); 692 goto reply; 693 } 694 if ((la->la_flags & LLE_VALID) && 695 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 696 if (la->la_flags & LLE_STATIC) { 697 LLE_WUNLOCK(la); 698 if (log_arp_permanent_modify) 699 log(LOG_ERR, 700 "arp: %*D attempts to modify " 701 "permanent entry for %s on %s\n", 702 ifp->if_addrlen, 703 (u_char *)ar_sha(ah), ":", 704 inet_ntoa(isaddr), ifp->if_xname); 705 goto reply; 706 } 707 if (log_arp_movements) { 708 log(LOG_INFO, "arp: %s moved from %*D " 709 "to %*D on %s\n", 710 inet_ntoa(isaddr), 711 ifp->if_addrlen, 712 (u_char *)&la->ll_addr, ":", 713 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 714 ifp->if_xname); 715 } 716 } 717 718 if (ifp->if_addrlen != ah->ar_hln) { 719 LLE_WUNLOCK(la); 720 log(LOG_WARNING, "arp from %*D: addr len: new %d, " 721 "i/f %d (ignored)\n", ifp->if_addrlen, 722 (u_char *) ar_sha(ah), ":", ah->ar_hln, 723 ifp->if_addrlen); 724 goto drop; 725 } 726 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 727 la->la_flags |= LLE_VALID; 728 729 EVENTHANDLER_INVOKE(arp_update_event, la); 730 731 if (!(la->la_flags & LLE_STATIC)) { 732 int canceled; 733 734 LLE_ADDREF(la); 735 la->la_expire = time_uptime + V_arpt_keep; 736 canceled = callout_reset(&la->la_timer, 737 hz * V_arpt_keep, arptimer, la); 738 if (canceled) 739 LLE_REMREF(la); 740 } 741 la->la_asked = 0; 742 la->la_preempt = V_arp_maxtries; 743 /* 744 * The packets are all freed within the call to the output 745 * routine. 746 * 747 * NB: The lock MUST be released before the call to the 748 * output routine. 749 */ 750 if (la->la_hold != NULL) { 751 struct mbuf *m_hold, *m_hold_next; 752 753 m_hold = la->la_hold; 754 la->la_hold = NULL; 755 la->la_numheld = 0; 756 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 757 LLE_WUNLOCK(la); 758 for (; m_hold != NULL; m_hold = m_hold_next) { 759 m_hold_next = m_hold->m_nextpkt; 760 m_hold->m_nextpkt = NULL; 761 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 762 } 763 } else 764 LLE_WUNLOCK(la); 765 } 766reply: 767 if (op != ARPOP_REQUEST) 768 goto drop; 769 ARPSTAT_INC(rxrequests); 770 771 if (itaddr.s_addr == myaddr.s_addr) { 772 /* Shortcut.. the receiving interface is the target. */ 773 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 774 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 775 } else { 776 struct llentry *lle = NULL; 777 778 sin.sin_addr = itaddr; 779 IF_AFDATA_LOCK(ifp); 780 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 781 IF_AFDATA_UNLOCK(ifp); 782 783 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 784 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 785 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 786 LLE_RUNLOCK(lle); 787 } else { 788 789 if (lle != NULL) 790 LLE_RUNLOCK(lle); 791 792 if (!V_arp_proxyall) 793 goto drop; 794 795 sin.sin_addr = itaddr; 796 /* XXX MRT use table 0 for arp reply */ 797 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 798 if (!rt) 799 goto drop; 800 801 /* 802 * Don't send proxies for nodes on the same interface 803 * as this one came out of, or we'll get into a fight 804 * over who claims what Ether address. 805 */ 806 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 807 RTFREE_LOCKED(rt); 808 goto drop; 809 } 810 RTFREE_LOCKED(rt); 811 812 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 813 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 814 815 /* 816 * Also check that the node which sent the ARP packet 817 * is on the interface we expect it to be on. This 818 * avoids ARP chaos if an interface is connected to the 819 * wrong network. 820 */ 821 sin.sin_addr = isaddr; 822 823 /* XXX MRT use table 0 for arp checks */ 824 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 825 if (!rt) 826 goto drop; 827 if (rt->rt_ifp != ifp) { 828 log(LOG_INFO, "arp_proxy: ignoring request" 829 " from %s via %s, expecting %s\n", 830 inet_ntoa(isaddr), ifp->if_xname, 831 rt->rt_ifp->if_xname); 832 RTFREE_LOCKED(rt); 833 goto drop; 834 } 835 RTFREE_LOCKED(rt); 836 837#ifdef DEBUG_PROXY 838 printf("arp: proxying for %s\n", 839 inet_ntoa(itaddr)); 840#endif 841 } 842 } 843 844 if (itaddr.s_addr == myaddr.s_addr && 845 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 846 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 847#ifdef DEBUG_LINKLOCAL 848 printf("arp: sending reply for link-local addr %s\n", 849 inet_ntoa(itaddr)); 850#endif 851 m->m_flags |= M_BCAST; 852 m->m_flags &= ~M_MCAST; 853 } else { 854 /* default behaviour; never reply by broadcast. */ 855 m->m_flags &= ~(M_BCAST|M_MCAST); 856 } 857 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 858 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 859 ah->ar_op = htons(ARPOP_REPLY); 860 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 861 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 862 m->m_pkthdr.len = m->m_len; 863 m->m_pkthdr.rcvif = NULL; 864 sa.sa_family = AF_ARP; 865 sa.sa_len = 2; 866 (*ifp->if_output)(ifp, m, &sa, NULL); 867 ARPSTAT_INC(txreplies); 868 return; 869 870drop: 871 m_freem(m); 872} 873#endif 874 875void 876arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 877{ 878 struct llentry *lle; 879 880 if (ifa->ifa_carp != NULL) 881 return; 882 883 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 884 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 885 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 886 /* 887 * interface address is considered static entry 888 * because the output of the arp utility shows 889 * that L2 entry as permanent 890 */ 891 IF_AFDATA_LOCK(ifp); 892 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 893 (struct sockaddr *)IA_SIN(ifa)); 894 IF_AFDATA_UNLOCK(ifp); 895 if (lle == NULL) 896 log(LOG_INFO, "arp_ifinit: cannot create arp " 897 "entry for interface address\n"); 898 else 899 LLE_RUNLOCK(lle); 900 } 901 ifa->ifa_rtrequest = NULL; 902} 903 904void 905arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 906{ 907 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 908 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 909 &IA_SIN(ifa)->sin_addr, enaddr); 910 ifa->ifa_rtrequest = NULL; 911} 912 913static void 914arp_init(void) 915{ 916 917 netisr_register(&arp_nh); 918} 919SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 920