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