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("$FreeBSD$"); 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 68 #include <net/if_arc.h> 69 #include <net/iso88025.h> 70 71 #include <security/mac/mac_framework.h> 72 73 #define SIN(s) ((struct sockaddr_in *)s) 74 #define SDL(s) ((struct sockaddr_dl *)s) 75 76 SYSCTL_DECL(_net_link_ether); 77 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 78 SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 79 80 /* timer values */ 81 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 82 * minutes */ 83 static VNET_DEFINE(int, arp_maxtries) = 5; 84 VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for 85 * local traffic */ 86 static VNET_DEFINE(int, arp_proxyall) = 0; 87 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 88 * 20 seconds */ 89 static VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 90 91 #define V_arpt_keep VNET(arpt_keep) 92 #define V_arpt_down VNET(arpt_down) 93 #define V_arp_maxtries VNET(arp_maxtries) 94 #define V_arp_proxyall VNET(arp_proxyall) 95 #define V_arpstat VNET(arpstat) 96 97 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 98 &VNET_NAME(arpt_keep), 0, 99 "ARP entry lifetime in seconds"); 100 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 101 &VNET_NAME(arp_maxtries), 0, 102 "ARP resolution attempts before returning error"); 103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 104 &VNET_NAME(useloopback), 0, 105 "Use the loopback interface for local traffic"); 106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 107 &VNET_NAME(arp_proxyall), 0, 108 "Enable proxy ARP for all suitable requests"); 109 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW, 110 &VNET_NAME(arpstat), arpstat, 111 "ARP statistics (struct arpstat, net/if_arp.h)"); 112 113 static void arp_init(void); 114 void arprequest(struct ifnet *, 115 struct in_addr *, struct in_addr *, u_char *); 116 static void arpintr(struct mbuf *); 117 static void arptimer(void *); 118 #ifdef INET 119 static void in_arpinput(struct mbuf *); 120 #endif 121 #if defined(INET) || defined(INET6) 122 int (*carp_iamatch_p)(struct ifnet *, struct in_ifaddr *, struct in_addr *, 123 u_int8_t **); 124 #endif 125 126 static const struct netisr_handler arp_nh = { 127 .nh_name = "arp", 128 .nh_handler = arpintr, 129 .nh_proto = NETISR_ARP, 130 .nh_policy = NETISR_POLICY_SOURCE, 131 }; 132 133 #ifdef AF_INET 134 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 135 136 /* 137 * called by in_ifscrub to remove entry from the table when 138 * the interface goes away 139 */ 140 void 141 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 142 { 143 struct sockaddr_in addr4; 144 145 bzero((void *)&addr4, sizeof(addr4)); 146 addr4.sin_len = sizeof(addr4); 147 addr4.sin_family = AF_INET; 148 addr4.sin_addr.s_addr = addr; 149 CURVNET_SET(ifp->if_vnet); 150 IF_AFDATA_LOCK(ifp); 151 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 152 (struct sockaddr *)&addr4); 153 IF_AFDATA_UNLOCK(ifp); 154 CURVNET_RESTORE(); 155 } 156 #endif 157 158 /* 159 * Timeout routine. Age arp_tab entries periodically. 160 */ 161 static void 162 arptimer(void *arg) 163 { 164 struct ifnet *ifp; 165 struct llentry *lle; 166 167 KASSERT(arg != NULL, ("%s: arg NULL", __func__)); 168 lle = (struct llentry *)arg; 169 ifp = lle->lle_tbl->llt_ifp; 170 CURVNET_SET(ifp->if_vnet); 171 IF_AFDATA_LOCK(ifp); 172 LLE_WLOCK(lle); 173 if (lle->la_flags & LLE_STATIC) 174 LLE_WUNLOCK(lle); 175 else { 176 if (!callout_pending(&lle->la_timer) && 177 callout_active(&lle->la_timer)) { 178 callout_stop(&lle->la_timer); 179 LLE_REMREF(lle); 180 (void) llentry_free(lle); 181 ARPSTAT_INC(timeouts); 182 } 183 #ifdef DIAGNOSTIC 184 else { 185 struct sockaddr *l3addr = L3_ADDR(lle); 186 log(LOG_INFO, 187 "arptimer issue: %p, IPv4 address: \"%s\"\n", lle, 188 inet_ntoa( 189 ((const struct sockaddr_in *)l3addr)->sin_addr)); 190 } 191 #endif 192 } 193 IF_AFDATA_UNLOCK(ifp); 194 CURVNET_RESTORE(); 195 } 196 197 /* 198 * Broadcast an ARP request. Caller specifies: 199 * - arp header source ip address 200 * - arp header target ip address 201 * - arp header source ethernet address 202 */ 203 void 204 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 205 u_char *enaddr) 206 { 207 struct mbuf *m; 208 struct arphdr *ah; 209 struct sockaddr sa; 210 211 if (sip == NULL) { 212 /* XXX don't believe this can happen (or explain why) */ 213 /* 214 * The caller did not supply a source address, try to find 215 * a compatible one among those assigned to this interface. 216 */ 217 struct ifaddr *ifa; 218 219 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 220 if (!ifa->ifa_addr || 221 ifa->ifa_addr->sa_family != AF_INET) 222 continue; 223 sip = &SIN(ifa->ifa_addr)->sin_addr; 224 if (0 == ((sip->s_addr ^ tip->s_addr) & 225 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 226 break; /* found it. */ 227 } 228 if (sip == NULL) { 229 printf("%s: cannot find matching address\n", __func__); 230 return; 231 } 232 } 233 234 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 235 return; 236 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 237 2*ifp->if_data.ifi_addrlen; 238 m->m_pkthdr.len = m->m_len; 239 MH_ALIGN(m, m->m_len); 240 ah = mtod(m, struct arphdr *); 241 bzero((caddr_t)ah, m->m_len); 242 #ifdef MAC 243 mac_netinet_arp_send(ifp, m); 244 #endif 245 ah->ar_pro = htons(ETHERTYPE_IP); 246 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 247 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 248 ah->ar_op = htons(ARPOP_REQUEST); 249 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 250 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 251 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 252 sa.sa_family = AF_ARP; 253 sa.sa_len = 2; 254 m->m_flags |= M_BCAST; 255 (*ifp->if_output)(ifp, m, &sa, NULL); 256 ARPSTAT_INC(txrequests); 257 } 258 259 /* 260 * Resolve an IP address into an ethernet address. 261 * On input: 262 * ifp is the interface we use 263 * rt0 is the route to the final destination (possibly useless) 264 * m is the mbuf. May be NULL if we don't have a packet. 265 * dst is the next hop, 266 * desten is where we want the address. 267 * 268 * On success, desten is filled in and the function returns 0; 269 * If the packet must be held pending resolution, we return EWOULDBLOCK 270 * On other errors, we return the corresponding error code. 271 * Note that m_freem() handles NULL. 272 */ 273 int 274 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 275 struct sockaddr *dst, u_char *desten, struct llentry **lle) 276 { 277 struct llentry *la = 0; 278 u_int flags = 0; 279 int error, renew; 280 281 *lle = NULL; 282 if (m != NULL) { 283 if (m->m_flags & M_BCAST) { 284 /* broadcast */ 285 (void)memcpy(desten, 286 ifp->if_broadcastaddr, ifp->if_addrlen); 287 return (0); 288 } 289 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 290 /* multicast */ 291 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 292 return (0); 293 } 294 } 295 /* XXXXX 296 */ 297 retry: 298 IF_AFDATA_RLOCK(ifp); 299 la = lla_lookup(LLTABLE(ifp), flags, dst); 300 IF_AFDATA_RUNLOCK(ifp); 301 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 302 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 303 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 304 IF_AFDATA_WLOCK(ifp); 305 la = lla_lookup(LLTABLE(ifp), flags, dst); 306 IF_AFDATA_WUNLOCK(ifp); 307 } 308 if (la == NULL) { 309 if (flags & LLE_CREATE) 310 log(LOG_DEBUG, 311 "arpresolve: can't allocate llinfo for %s\n", 312 inet_ntoa(SIN(dst)->sin_addr)); 313 m_freem(m); 314 return (EINVAL); 315 } 316 317 if ((la->la_flags & LLE_VALID) && 318 ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) { 319 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 320 /* 321 * If entry has an expiry time and it is approaching, 322 * see if we need to send an ARP request within this 323 * arpt_down interval. 324 */ 325 if (!(la->la_flags & LLE_STATIC) && 326 time_second + la->la_preempt > la->la_expire) { 327 arprequest(ifp, NULL, 328 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 329 330 la->la_preempt--; 331 } 332 333 *lle = la; 334 error = 0; 335 goto done; 336 } 337 338 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 339 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 340 inet_ntoa(SIN(dst)->sin_addr)); 341 m_freem(m); 342 error = EINVAL; 343 goto done; 344 } 345 346 renew = (la->la_asked == 0 || la->la_expire != time_second); 347 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 348 flags |= LLE_EXCLUSIVE; 349 LLE_RUNLOCK(la); 350 goto retry; 351 } 352 /* 353 * There is an arptab entry, but no ethernet address 354 * response yet. Replace the held mbuf with this 355 * latest one. 356 */ 357 if (m != NULL) { 358 if (la->la_hold != NULL) { 359 m_freem(la->la_hold); 360 ARPSTAT_INC(dropped); 361 } 362 la->la_hold = m; 363 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 364 flags &= ~LLE_EXCLUSIVE; 365 LLE_DOWNGRADE(la); 366 } 367 368 } 369 /* 370 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 371 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 372 * if we have already sent arp_maxtries ARP requests. Retransmit the 373 * ARP request, but not faster than one request per second. 374 */ 375 if (la->la_asked < V_arp_maxtries) 376 error = EWOULDBLOCK; /* First request. */ 377 else 378 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 379 EHOSTUNREACH : EHOSTDOWN; 380 381 if (renew) { 382 int canceled; 383 384 LLE_ADDREF(la); 385 la->la_expire = time_second + V_arpt_down; 386 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 387 arptimer, la); 388 if (canceled) 389 LLE_REMREF(la); 390 la->la_asked++; 391 LLE_WUNLOCK(la); 392 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 393 IF_LLADDR(ifp)); 394 return (error); 395 } 396 done: 397 if (flags & LLE_EXCLUSIVE) 398 LLE_WUNLOCK(la); 399 else 400 LLE_RUNLOCK(la); 401 return (error); 402 } 403 404 /* 405 * Common length and type checks are done here, 406 * then the protocol-specific routine is called. 407 */ 408 static void 409 arpintr(struct mbuf *m) 410 { 411 struct arphdr *ar; 412 413 if (m->m_len < sizeof(struct arphdr) && 414 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 415 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 416 return; 417 } 418 ar = mtod(m, struct arphdr *); 419 420 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 421 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 422 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 423 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 424 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 425 (unsigned char *)&ar->ar_hrd, ""); 426 m_freem(m); 427 return; 428 } 429 430 if (m->m_len < arphdr_len(ar)) { 431 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 432 log(LOG_ERR, "arp: runt packet\n"); 433 m_freem(m); 434 return; 435 } 436 ar = mtod(m, struct arphdr *); 437 } 438 439 ARPSTAT_INC(received); 440 switch (ntohs(ar->ar_pro)) { 441 #ifdef INET 442 case ETHERTYPE_IP: 443 in_arpinput(m); 444 return; 445 #endif 446 } 447 m_freem(m); 448 } 449 450 #ifdef INET 451 /* 452 * ARP for Internet protocols on 10 Mb/s Ethernet. 453 * Algorithm is that given in RFC 826. 454 * In addition, a sanity check is performed on the sender 455 * protocol address, to catch impersonators. 456 * We no longer handle negotiations for use of trailer protocol: 457 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 458 * along with IP replies if we wanted trailers sent to us, 459 * and also sent them in response to IP replies. 460 * This allowed either end to announce the desire to receive 461 * trailer packets. 462 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 463 * but formerly didn't normally send requests. 464 */ 465 static int log_arp_wrong_iface = 1; 466 static int log_arp_movements = 1; 467 static int log_arp_permanent_modify = 1; 468 469 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 470 &log_arp_wrong_iface, 0, 471 "log arp packets arriving on the wrong interface"); 472 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 473 &log_arp_movements, 0, 474 "log arp replies from MACs different than the one in the cache"); 475 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 476 &log_arp_permanent_modify, 0, 477 "log arp replies from MACs different than the one in the permanent arp entry"); 478 479 480 static void 481 in_arpinput(struct mbuf *m) 482 { 483 struct arphdr *ah; 484 struct ifnet *ifp = m->m_pkthdr.rcvif; 485 struct llentry *la = NULL; 486 struct rtentry *rt; 487 struct ifaddr *ifa; 488 struct in_ifaddr *ia; 489 struct mbuf *hold; 490 struct sockaddr sa; 491 struct in_addr isaddr, itaddr, myaddr; 492 u_int8_t *enaddr = NULL; 493 int op, flags; 494 int req_len; 495 int bridged = 0, is_bridge = 0; 496 int carp_match = 0; 497 struct sockaddr_in sin; 498 sin.sin_len = sizeof(struct sockaddr_in); 499 sin.sin_family = AF_INET; 500 sin.sin_addr.s_addr = 0; 501 502 if (ifp->if_bridge) 503 bridged = 1; 504 if (ifp->if_type == IFT_BRIDGE) 505 is_bridge = 1; 506 507 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 508 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 509 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 510 return; 511 } 512 513 ah = mtod(m, struct arphdr *); 514 op = ntohs(ah->ar_op); 515 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 516 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 517 518 if (op == ARPOP_REPLY) 519 ARPSTAT_INC(rxreplies); 520 521 /* 522 * For a bridge, we want to check the address irrespective 523 * of the receive interface. (This will change slightly 524 * when we have clusters of interfaces). 525 * If the interface does not match, but the recieving interface 526 * is part of carp, we call carp_iamatch to see if this is a 527 * request for the virtual host ip. 528 * XXX: This is really ugly! 529 */ 530 IN_IFADDR_RLOCK(); 531 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 532 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 533 ia->ia_ifp == ifp) && 534 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 535 ifa_ref(&ia->ia_ifa); 536 IN_IFADDR_RUNLOCK(); 537 goto match; 538 } 539 if (ifp->if_carp != NULL && 540 (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) && 541 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 542 carp_match = 1; 543 ifa_ref(&ia->ia_ifa); 544 IN_IFADDR_RUNLOCK(); 545 goto match; 546 } 547 } 548 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 549 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 550 ia->ia_ifp == ifp) && 551 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 552 ifa_ref(&ia->ia_ifa); 553 IN_IFADDR_RUNLOCK(); 554 goto match; 555 } 556 557 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 558 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 559 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 560 addr == ia->ia_addr.sin_addr.s_addr) 561 /* 562 * Check the case when bridge shares its MAC address with 563 * some of its children, so packets are claimed by bridge 564 * itself (bridge_input() does it first), but they are really 565 * meant to be destined to the bridge member. 566 */ 567 if (is_bridge) { 568 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 569 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 570 ifa_ref(&ia->ia_ifa); 571 ifp = ia->ia_ifp; 572 IN_IFADDR_RUNLOCK(); 573 goto match; 574 } 575 } 576 } 577 #undef BDG_MEMBER_MATCHES_ARP 578 IN_IFADDR_RUNLOCK(); 579 580 /* 581 * No match, use the first inet address on the receive interface 582 * as a dummy address for the rest of the function. 583 */ 584 IF_ADDR_LOCK(ifp); 585 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 586 if (ifa->ifa_addr->sa_family == AF_INET) { 587 ia = ifatoia(ifa); 588 ifa_ref(ifa); 589 IF_ADDR_UNLOCK(ifp); 590 goto match; 591 } 592 IF_ADDR_UNLOCK(ifp); 593 594 /* 595 * If bridging, fall back to using any inet address. 596 */ 597 IN_IFADDR_RLOCK(); 598 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 599 IN_IFADDR_RUNLOCK(); 600 goto drop; 601 } 602 ifa_ref(&ia->ia_ifa); 603 IN_IFADDR_RUNLOCK(); 604 match: 605 if (!enaddr) 606 enaddr = (u_int8_t *)IF_LLADDR(ifp); 607 myaddr = ia->ia_addr.sin_addr; 608 ifa_free(&ia->ia_ifa); 609 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 610 goto drop; /* it's from me, ignore it. */ 611 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 612 log(LOG_ERR, 613 "arp: link address is broadcast for IP address %s!\n", 614 inet_ntoa(isaddr)); 615 goto drop; 616 } 617 /* 618 * Warn if another host is using the same IP address, but only if the 619 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 620 * case we suppress the warning to avoid false positive complaints of 621 * potential misconfiguration. 622 */ 623 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 624 log(LOG_ERR, 625 "arp: %*D is using my IP address %s on %s!\n", 626 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 627 inet_ntoa(isaddr), ifp->if_xname); 628 itaddr = myaddr; 629 ARPSTAT_INC(dupips); 630 goto reply; 631 } 632 if (ifp->if_flags & IFF_STATICARP) 633 goto reply; 634 635 bzero(&sin, sizeof(sin)); 636 sin.sin_len = sizeof(struct sockaddr_in); 637 sin.sin_family = AF_INET; 638 sin.sin_addr = isaddr; 639 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 640 flags |= LLE_EXCLUSIVE; 641 IF_AFDATA_LOCK(ifp); 642 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 643 IF_AFDATA_UNLOCK(ifp); 644 if (la != NULL) { 645 /* the following is not an error when doing bridging */ 646 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) { 647 if (log_arp_wrong_iface) 648 log(LOG_ERR, "arp: %s is on %s " 649 "but got reply from %*D on %s\n", 650 inet_ntoa(isaddr), 651 la->lle_tbl->llt_ifp->if_xname, 652 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 653 ifp->if_xname); 654 LLE_WUNLOCK(la); 655 goto reply; 656 } 657 if ((la->la_flags & LLE_VALID) && 658 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 659 if (la->la_flags & LLE_STATIC) { 660 LLE_WUNLOCK(la); 661 log(LOG_ERR, 662 "arp: %*D attempts to modify permanent " 663 "entry for %s on %s\n", 664 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 665 inet_ntoa(isaddr), ifp->if_xname); 666 goto reply; 667 } 668 if (log_arp_movements) { 669 log(LOG_INFO, "arp: %s moved from %*D " 670 "to %*D on %s\n", 671 inet_ntoa(isaddr), 672 ifp->if_addrlen, 673 (u_char *)&la->ll_addr, ":", 674 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 675 ifp->if_xname); 676 } 677 } 678 679 if (ifp->if_addrlen != ah->ar_hln) { 680 LLE_WUNLOCK(la); 681 log(LOG_WARNING, 682 "arp from %*D: addr len: new %d, i/f %d (ignored)", 683 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 684 ah->ar_hln, ifp->if_addrlen); 685 goto reply; 686 } 687 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 688 la->la_flags |= LLE_VALID; 689 690 EVENTHANDLER_INVOKE(arp_update_event, la); 691 692 if (!(la->la_flags & LLE_STATIC)) { 693 int canceled; 694 695 LLE_ADDREF(la); 696 la->la_expire = time_second + V_arpt_keep; 697 canceled = callout_reset(&la->la_timer, 698 hz * V_arpt_keep, arptimer, la); 699 if (canceled) 700 LLE_REMREF(la); 701 } 702 la->la_asked = 0; 703 la->la_preempt = V_arp_maxtries; 704 hold = la->la_hold; 705 if (hold != NULL) { 706 la->la_hold = NULL; 707 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 708 } 709 LLE_WUNLOCK(la); 710 if (hold != NULL) 711 (*ifp->if_output)(ifp, hold, &sa, NULL); 712 } 713 reply: 714 if (op != ARPOP_REQUEST) 715 goto drop; 716 ARPSTAT_INC(rxrequests); 717 718 if (itaddr.s_addr == myaddr.s_addr) { 719 /* Shortcut.. the receiving interface is the target. */ 720 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 721 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 722 } else { 723 struct llentry *lle = NULL; 724 725 sin.sin_addr = itaddr; 726 IF_AFDATA_LOCK(ifp); 727 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 728 IF_AFDATA_UNLOCK(ifp); 729 730 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 731 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 732 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 733 LLE_RUNLOCK(lle); 734 } else { 735 736 if (lle != NULL) 737 LLE_RUNLOCK(lle); 738 739 if (!V_arp_proxyall) 740 goto drop; 741 742 sin.sin_addr = itaddr; 743 /* XXX MRT use table 0 for arp reply */ 744 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 745 if (!rt) 746 goto drop; 747 748 /* 749 * Don't send proxies for nodes on the same interface 750 * as this one came out of, or we'll get into a fight 751 * over who claims what Ether address. 752 */ 753 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 754 RTFREE_LOCKED(rt); 755 goto drop; 756 } 757 RTFREE_LOCKED(rt); 758 759 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 760 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 761 762 /* 763 * Also check that the node which sent the ARP packet 764 * is on the the interface we expect it to be on. This 765 * avoids ARP chaos if an interface is connected to the 766 * wrong network. 767 */ 768 sin.sin_addr = isaddr; 769 770 /* XXX MRT use table 0 for arp checks */ 771 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 772 if (!rt) 773 goto drop; 774 if (rt->rt_ifp != ifp) { 775 log(LOG_INFO, "arp_proxy: ignoring request" 776 " from %s via %s, expecting %s\n", 777 inet_ntoa(isaddr), ifp->if_xname, 778 rt->rt_ifp->if_xname); 779 RTFREE_LOCKED(rt); 780 goto drop; 781 } 782 RTFREE_LOCKED(rt); 783 784 #ifdef DEBUG_PROXY 785 printf("arp: proxying for %s\n", 786 inet_ntoa(itaddr)); 787 #endif 788 } 789 } 790 791 if (itaddr.s_addr == myaddr.s_addr && 792 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 793 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 794 #ifdef DEBUG_LINKLOCAL 795 printf("arp: sending reply for link-local addr %s\n", 796 inet_ntoa(itaddr)); 797 #endif 798 m->m_flags |= M_BCAST; 799 m->m_flags &= ~M_MCAST; 800 } else { 801 /* default behaviour; never reply by broadcast. */ 802 m->m_flags &= ~(M_BCAST|M_MCAST); 803 } 804 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 805 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 806 ah->ar_op = htons(ARPOP_REPLY); 807 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 808 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 809 m->m_pkthdr.len = m->m_len; 810 sa.sa_family = AF_ARP; 811 sa.sa_len = 2; 812 (*ifp->if_output)(ifp, m, &sa, NULL); 813 ARPSTAT_INC(txreplies); 814 return; 815 816 drop: 817 m_freem(m); 818 } 819 #endif 820 821 void 822 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 823 { 824 struct llentry *lle; 825 826 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 827 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 828 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 829 /* 830 * interface address is considered static entry 831 * because the output of the arp utility shows 832 * that L2 entry as permanent 833 */ 834 IF_AFDATA_LOCK(ifp); 835 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 836 (struct sockaddr *)IA_SIN(ifa)); 837 IF_AFDATA_UNLOCK(ifp); 838 if (lle == NULL) 839 log(LOG_INFO, "arp_ifinit: cannot create arp " 840 "entry for interface address\n"); 841 else 842 LLE_RUNLOCK(lle); 843 } 844 ifa->ifa_rtrequest = NULL; 845 } 846 847 void 848 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 849 { 850 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 851 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 852 &IA_SIN(ifa)->sin_addr, enaddr); 853 ifa->ifa_rtrequest = NULL; 854 } 855 856 static void 857 arp_init(void) 858 { 859 860 netisr_register(&arp_nh); 861 } 862 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 863