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 #include "opt_carp.h" 43 44 #include <sys/param.h> 45 #include <sys/kernel.h> 46 #include <sys/queue.h> 47 #include <sys/sysctl.h> 48 #include <sys/systm.h> 49 #include <sys/mbuf.h> 50 #include <sys/malloc.h> 51 #include <sys/proc.h> 52 #include <sys/socket.h> 53 #include <sys/syslog.h> 54 55 #include <net/if.h> 56 #include <net/if_dl.h> 57 #include <net/if_types.h> 58 #include <net/netisr.h> 59 #include <net/if_llc.h> 60 #include <net/ethernet.h> 61 #include <net/route.h> 62 #include <net/vnet.h> 63 64 #include <netinet/in.h> 65 #include <netinet/in_var.h> 66 #include <net/if_llatbl.h> 67 #include <netinet/if_ether.h> 68 69 #include <net/if_arc.h> 70 #include <net/iso88025.h> 71 72 #ifdef DEV_CARP 73 #include <netinet/ip_carp.h> 74 #endif 75 76 #include <security/mac/mac_framework.h> 77 78 #define SIN(s) ((struct sockaddr_in *)s) 79 #define SDL(s) ((struct sockaddr_dl *)s) 80 81 SYSCTL_DECL(_net_link_ether); 82 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 83 SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 84 85 VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for 86 * local traffic */ 87 88 /* timer values */ 89 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 90 * minutes */ 91 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 92 * 20 seconds */ 93 static VNET_DEFINE(int, arp_maxtries) = 5; 94 static VNET_DEFINE(int, arp_proxyall); 95 static VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 96 97 #define V_arpt_keep VNET(arpt_keep) 98 #define V_arpt_down VNET(arpt_down) 99 #define V_arp_maxtries VNET(arp_maxtries) 100 #define V_arp_proxyall VNET(arp_proxyall) 101 #define V_arpstat VNET(arpstat) 102 103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 104 &VNET_NAME(arpt_keep), 0, 105 "ARP entry lifetime in seconds"); 106 107 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 108 &VNET_NAME(arp_maxtries), 0, 109 "ARP resolution attempts before returning error"); 110 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 111 &VNET_NAME(useloopback), 0, 112 "Use the loopback interface for local traffic"); 113 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 114 &VNET_NAME(arp_proxyall), 0, 115 "Enable proxy ARP for all suitable requests"); 116 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW, 117 &VNET_NAME(arpstat), arpstat, 118 "ARP statistics (struct arpstat, net/if_arp.h)"); 119 120 static void arp_init(void); 121 void arprequest(struct ifnet *, 122 struct in_addr *, struct in_addr *, u_char *); 123 static void arpintr(struct mbuf *); 124 static void arptimer(void *); 125 #ifdef INET 126 static void in_arpinput(struct mbuf *); 127 #endif 128 129 static const struct netisr_handler arp_nh = { 130 .nh_name = "arp", 131 .nh_handler = arpintr, 132 .nh_proto = NETISR_ARP, 133 .nh_policy = NETISR_POLICY_SOURCE, 134 }; 135 136 #ifdef AF_INET 137 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 138 139 /* 140 * called by in_ifscrub to remove entry from the table when 141 * the interface goes away 142 */ 143 void 144 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 145 { 146 struct sockaddr_in addr4; 147 148 bzero((void *)&addr4, sizeof(addr4)); 149 addr4.sin_len = sizeof(addr4); 150 addr4.sin_family = AF_INET; 151 addr4.sin_addr.s_addr = addr; 152 CURVNET_SET(ifp->if_vnet); 153 IF_AFDATA_LOCK(ifp); 154 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 155 (struct sockaddr *)&addr4); 156 IF_AFDATA_UNLOCK(ifp); 157 CURVNET_RESTORE(); 158 } 159 #endif 160 161 /* 162 * Timeout routine. Age arp_tab entries periodically. 163 */ 164 static void 165 arptimer(void *arg) 166 { 167 struct ifnet *ifp; 168 struct llentry *lle = (struct llentry *)arg; 169 170 if (lle == NULL) { 171 panic("%s: NULL entry!\n", __func__); 172 return; 173 } 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 (void) llentry_free(lle); 186 ARPSTAT_INC(timeouts); 187 } 188 #ifdef DIAGNOSTIC 189 else { 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 } 196 #endif 197 } 198 IF_AFDATA_UNLOCK(ifp); 199 CURVNET_RESTORE(); 200 } 201 202 /* 203 * Broadcast an ARP request. Caller specifies: 204 * - arp header source ip address 205 * - arp header target ip address 206 * - arp header source ethernet address 207 */ 208 void 209 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 210 u_char *enaddr) 211 { 212 struct mbuf *m; 213 struct arphdr *ah; 214 struct sockaddr sa; 215 216 if (sip == NULL) { 217 /* XXX don't believe this can happen (or explain why) */ 218 /* 219 * The caller did not supply a source address, try to find 220 * a compatible one among those assigned to this interface. 221 */ 222 struct ifaddr *ifa; 223 224 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 225 if (!ifa->ifa_addr || 226 ifa->ifa_addr->sa_family != AF_INET) 227 continue; 228 sip = &SIN(ifa->ifa_addr)->sin_addr; 229 if (0 == ((sip->s_addr ^ tip->s_addr) & 230 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 231 break; /* found it. */ 232 } 233 if (sip == NULL) { 234 printf("%s: cannot find matching address\n", __func__); 235 return; 236 } 237 } 238 239 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 240 return; 241 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 242 2*ifp->if_data.ifi_addrlen; 243 m->m_pkthdr.len = m->m_len; 244 MH_ALIGN(m, m->m_len); 245 ah = mtod(m, struct arphdr *); 246 bzero((caddr_t)ah, m->m_len); 247 #ifdef MAC 248 mac_netinet_arp_send(ifp, m); 249 #endif 250 ah->ar_pro = htons(ETHERTYPE_IP); 251 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 252 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 253 ah->ar_op = htons(ARPOP_REQUEST); 254 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 255 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 256 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 257 sa.sa_family = AF_ARP; 258 sa.sa_len = 2; 259 m->m_flags |= M_BCAST; 260 (*ifp->if_output)(ifp, m, &sa, NULL); 261 ARPSTAT_INC(txrequests); 262 } 263 264 /* 265 * Resolve an IP address into an ethernet address. 266 * On input: 267 * ifp is the interface we use 268 * rt0 is the route to the final destination (possibly useless) 269 * m is the mbuf. May be NULL if we don't have a packet. 270 * dst is the next hop, 271 * desten is where we want the address. 272 * 273 * On success, desten is filled in and the function returns 0; 274 * If the packet must be held pending resolution, we return EWOULDBLOCK 275 * On other errors, we return the corresponding error code. 276 * Note that m_freem() handles NULL. 277 */ 278 int 279 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 280 struct sockaddr *dst, u_char *desten, struct llentry **lle) 281 { 282 struct llentry *la = 0; 283 u_int flags = 0; 284 int error, renew; 285 286 *lle = NULL; 287 if (m != NULL) { 288 if (m->m_flags & M_BCAST) { 289 /* broadcast */ 290 (void)memcpy(desten, 291 ifp->if_broadcastaddr, ifp->if_addrlen); 292 return (0); 293 } 294 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 295 /* multicast */ 296 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 297 return (0); 298 } 299 } 300 /* XXXXX 301 */ 302 retry: 303 IF_AFDATA_RLOCK(ifp); 304 la = lla_lookup(LLTABLE(ifp), flags, dst); 305 IF_AFDATA_RUNLOCK(ifp); 306 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 307 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 308 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 309 IF_AFDATA_WLOCK(ifp); 310 la = lla_lookup(LLTABLE(ifp), flags, dst); 311 IF_AFDATA_WUNLOCK(ifp); 312 } 313 if (la == NULL) { 314 if (flags & LLE_CREATE) 315 log(LOG_DEBUG, 316 "arpresolve: can't allocate llinfo for %s\n", 317 inet_ntoa(SIN(dst)->sin_addr)); 318 m_freem(m); 319 return (EINVAL); 320 } 321 322 if ((la->la_flags & LLE_VALID) && 323 ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) { 324 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 325 /* 326 * If entry has an expiry time and it is approaching, 327 * see if we need to send an ARP request within this 328 * arpt_down interval. 329 */ 330 if (!(la->la_flags & LLE_STATIC) && 331 time_second + la->la_preempt > la->la_expire) { 332 arprequest(ifp, NULL, 333 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 334 335 la->la_preempt--; 336 } 337 338 *lle = la; 339 error = 0; 340 goto done; 341 } 342 343 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 344 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 345 inet_ntoa(SIN(dst)->sin_addr)); 346 m_freem(m); 347 error = EINVAL; 348 goto done; 349 } 350 351 renew = (la->la_asked == 0 || la->la_expire != time_second); 352 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 353 flags |= LLE_EXCLUSIVE; 354 LLE_RUNLOCK(la); 355 goto retry; 356 } 357 /* 358 * There is an arptab entry, but no ethernet address 359 * response yet. Replace the held mbuf with this 360 * latest one. 361 */ 362 if (m != NULL) { 363 if (la->la_hold != NULL) { 364 m_freem(la->la_hold); 365 ARPSTAT_INC(dropped); 366 } 367 la->la_hold = m; 368 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 369 flags &= ~LLE_EXCLUSIVE; 370 LLE_DOWNGRADE(la); 371 } 372 373 } 374 /* 375 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 376 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 377 * if we have already sent arp_maxtries ARP requests. Retransmit the 378 * ARP request, but not faster than one request per second. 379 */ 380 if (la->la_asked < V_arp_maxtries) 381 error = EWOULDBLOCK; /* First request. */ 382 else 383 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 384 EHOSTUNREACH : EHOSTDOWN; 385 386 if (renew) { 387 int canceled; 388 389 LLE_ADDREF(la); 390 la->la_expire = time_second + V_arpt_down; 391 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 392 arptimer, la); 393 if (canceled) 394 LLE_REMREF(la); 395 la->la_asked++; 396 LLE_WUNLOCK(la); 397 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 398 IF_LLADDR(ifp)); 399 return (error); 400 } 401 done: 402 if (flags & LLE_EXCLUSIVE) 403 LLE_WUNLOCK(la); 404 else 405 LLE_RUNLOCK(la); 406 return (error); 407 } 408 409 /* 410 * Common length and type checks are done here, 411 * then the protocol-specific routine is called. 412 */ 413 static void 414 arpintr(struct mbuf *m) 415 { 416 struct arphdr *ar; 417 418 if (m->m_len < sizeof(struct arphdr) && 419 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 420 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 421 return; 422 } 423 ar = mtod(m, struct arphdr *); 424 425 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 426 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 427 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 428 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 429 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 430 (unsigned char *)&ar->ar_hrd, ""); 431 m_freem(m); 432 return; 433 } 434 435 if (m->m_len < arphdr_len(ar)) { 436 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 437 log(LOG_ERR, "arp: runt packet\n"); 438 m_freem(m); 439 return; 440 } 441 ar = mtod(m, struct arphdr *); 442 } 443 444 ARPSTAT_INC(received); 445 switch (ntohs(ar->ar_pro)) { 446 #ifdef INET 447 case ETHERTYPE_IP: 448 in_arpinput(m); 449 return; 450 #endif 451 } 452 m_freem(m); 453 } 454 455 #ifdef INET 456 /* 457 * ARP for Internet protocols on 10 Mb/s Ethernet. 458 * Algorithm is that given in RFC 826. 459 * In addition, a sanity check is performed on the sender 460 * protocol address, to catch impersonators. 461 * We no longer handle negotiations for use of trailer protocol: 462 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 463 * along with IP replies if we wanted trailers sent to us, 464 * and also sent them in response to IP replies. 465 * This allowed either end to announce the desire to receive 466 * trailer packets. 467 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 468 * but formerly didn't normally send requests. 469 */ 470 static int log_arp_wrong_iface = 1; 471 static int log_arp_movements = 1; 472 static int log_arp_permanent_modify = 1; 473 474 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 475 &log_arp_wrong_iface, 0, 476 "log arp packets arriving on the wrong interface"); 477 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 478 &log_arp_movements, 0, 479 "log arp replies from MACs different than the one in the cache"); 480 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 481 &log_arp_permanent_modify, 0, 482 "log arp replies from MACs different than the one in the permanent arp entry"); 483 484 485 static void 486 in_arpinput(struct mbuf *m) 487 { 488 struct arphdr *ah; 489 struct ifnet *ifp = m->m_pkthdr.rcvif; 490 struct llentry *la = NULL; 491 struct rtentry *rt; 492 struct ifaddr *ifa; 493 struct in_ifaddr *ia; 494 struct mbuf *hold; 495 struct sockaddr sa; 496 struct in_addr isaddr, itaddr, myaddr; 497 u_int8_t *enaddr = NULL; 498 int op, flags; 499 int req_len; 500 int bridged = 0, is_bridge = 0; 501 #ifdef DEV_CARP 502 int carp_match = 0; 503 #endif 504 struct sockaddr_in sin; 505 sin.sin_len = sizeof(struct sockaddr_in); 506 sin.sin_family = AF_INET; 507 sin.sin_addr.s_addr = 0; 508 509 if (ifp->if_bridge) 510 bridged = 1; 511 if (ifp->if_type == IFT_BRIDGE) 512 is_bridge = 1; 513 514 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 515 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 516 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 517 return; 518 } 519 520 ah = mtod(m, struct arphdr *); 521 op = ntohs(ah->ar_op); 522 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 523 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 524 525 if (op == ARPOP_REPLY) 526 ARPSTAT_INC(rxreplies); 527 528 /* 529 * For a bridge, we want to check the address irrespective 530 * of the receive interface. (This will change slightly 531 * when we have clusters of interfaces). 532 * If the interface does not match, but the recieving interface 533 * is part of carp, we call carp_iamatch to see if this is a 534 * request for the virtual host ip. 535 * XXX: This is really ugly! 536 */ 537 IN_IFADDR_RLOCK(); 538 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 539 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 540 ia->ia_ifp == ifp) && 541 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 542 ifa_ref(&ia->ia_ifa); 543 IN_IFADDR_RUNLOCK(); 544 goto match; 545 } 546 #ifdef DEV_CARP 547 if (ifp->if_carp != NULL && 548 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 549 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 550 carp_match = 1; 551 ifa_ref(&ia->ia_ifa); 552 IN_IFADDR_RUNLOCK(); 553 goto match; 554 } 555 #endif 556 } 557 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 558 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 559 ia->ia_ifp == ifp) && 560 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 561 ifa_ref(&ia->ia_ifa); 562 IN_IFADDR_RUNLOCK(); 563 goto match; 564 } 565 566 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 567 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 568 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 569 addr == ia->ia_addr.sin_addr.s_addr) 570 /* 571 * Check the case when bridge shares its MAC address with 572 * some of its children, so packets are claimed by bridge 573 * itself (bridge_input() does it first), but they are really 574 * meant to be destined to the bridge member. 575 */ 576 if (is_bridge) { 577 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 578 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 579 ifa_ref(&ia->ia_ifa); 580 ifp = ia->ia_ifp; 581 IN_IFADDR_RUNLOCK(); 582 goto match; 583 } 584 } 585 } 586 #undef BDG_MEMBER_MATCHES_ARP 587 IN_IFADDR_RUNLOCK(); 588 589 /* 590 * No match, use the first inet address on the receive interface 591 * as a dummy address for the rest of the function. 592 */ 593 IF_ADDR_LOCK(ifp); 594 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 595 if (ifa->ifa_addr->sa_family == AF_INET) { 596 ia = ifatoia(ifa); 597 ifa_ref(ifa); 598 IF_ADDR_UNLOCK(ifp); 599 goto match; 600 } 601 IF_ADDR_UNLOCK(ifp); 602 603 /* 604 * If bridging, fall back to using any inet address. 605 */ 606 IN_IFADDR_RLOCK(); 607 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 608 IN_IFADDR_RUNLOCK(); 609 goto drop; 610 } 611 ifa_ref(&ia->ia_ifa); 612 IN_IFADDR_RUNLOCK(); 613 match: 614 if (!enaddr) 615 enaddr = (u_int8_t *)IF_LLADDR(ifp); 616 myaddr = ia->ia_addr.sin_addr; 617 ifa_free(&ia->ia_ifa); 618 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 619 goto drop; /* it's from me, ignore it. */ 620 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 621 log(LOG_ERR, 622 "arp: link address is broadcast for IP address %s!\n", 623 inet_ntoa(isaddr)); 624 goto drop; 625 } 626 /* 627 * Warn if another host is using the same IP address, but only if the 628 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 629 * case we suppress the warning to avoid false positive complaints of 630 * potential misconfiguration. 631 */ 632 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 633 log(LOG_ERR, 634 "arp: %*D is using my IP address %s on %s!\n", 635 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 636 inet_ntoa(isaddr), ifp->if_xname); 637 itaddr = myaddr; 638 ARPSTAT_INC(dupips); 639 goto reply; 640 } 641 if (ifp->if_flags & IFF_STATICARP) 642 goto reply; 643 644 bzero(&sin, sizeof(sin)); 645 sin.sin_len = sizeof(struct sockaddr_in); 646 sin.sin_family = AF_INET; 647 sin.sin_addr = isaddr; 648 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 649 flags |= LLE_EXCLUSIVE; 650 IF_AFDATA_LOCK(ifp); 651 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 652 IF_AFDATA_UNLOCK(ifp); 653 if (la != NULL) { 654 /* the following is not an error when doing bridging */ 655 if (!bridged && la->lle_tbl->llt_ifp != ifp 656 #ifdef DEV_CARP 657 && (ifp->if_type != IFT_CARP || !carp_match) 658 #endif 659 ) { 660 if (log_arp_wrong_iface) 661 log(LOG_ERR, "arp: %s is on %s " 662 "but got reply from %*D on %s\n", 663 inet_ntoa(isaddr), 664 la->lle_tbl->llt_ifp->if_xname, 665 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 666 ifp->if_xname); 667 LLE_WUNLOCK(la); 668 goto reply; 669 } 670 if ((la->la_flags & LLE_VALID) && 671 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 672 if (la->la_flags & LLE_STATIC) { 673 LLE_WUNLOCK(la); 674 log(LOG_ERR, 675 "arp: %*D attempts to modify permanent " 676 "entry for %s on %s\n", 677 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 678 inet_ntoa(isaddr), ifp->if_xname); 679 goto reply; 680 } 681 if (log_arp_movements) { 682 log(LOG_INFO, "arp: %s moved from %*D " 683 "to %*D on %s\n", 684 inet_ntoa(isaddr), 685 ifp->if_addrlen, 686 (u_char *)&la->ll_addr, ":", 687 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 688 ifp->if_xname); 689 } 690 } 691 692 if (ifp->if_addrlen != ah->ar_hln) { 693 LLE_WUNLOCK(la); 694 log(LOG_WARNING, 695 "arp from %*D: addr len: new %d, i/f %d (ignored)", 696 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 697 ah->ar_hln, ifp->if_addrlen); 698 goto reply; 699 } 700 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 701 la->la_flags |= LLE_VALID; 702 703 EVENTHANDLER_INVOKE(arp_update_event, la); 704 705 if (!(la->la_flags & LLE_STATIC)) { 706 int canceled; 707 708 LLE_ADDREF(la); 709 la->la_expire = time_second + V_arpt_keep; 710 canceled = callout_reset(&la->la_timer, 711 hz * V_arpt_keep, arptimer, la); 712 if (canceled) 713 LLE_REMREF(la); 714 } 715 la->la_asked = 0; 716 la->la_preempt = V_arp_maxtries; 717 hold = la->la_hold; 718 if (hold != NULL) { 719 la->la_hold = NULL; 720 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 721 } 722 LLE_WUNLOCK(la); 723 if (hold != NULL) 724 (*ifp->if_output)(ifp, hold, &sa, NULL); 725 } 726 reply: 727 if (op != ARPOP_REQUEST) 728 goto drop; 729 ARPSTAT_INC(rxrequests); 730 731 if (itaddr.s_addr == myaddr.s_addr) { 732 /* Shortcut.. the receiving interface is the target. */ 733 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 734 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 735 } else { 736 struct llentry *lle = NULL; 737 738 sin.sin_addr = itaddr; 739 IF_AFDATA_LOCK(ifp); 740 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 741 IF_AFDATA_UNLOCK(ifp); 742 743 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 744 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 745 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 746 LLE_RUNLOCK(lle); 747 } else { 748 749 if (lle != NULL) 750 LLE_RUNLOCK(lle); 751 752 if (!V_arp_proxyall) 753 goto drop; 754 755 sin.sin_addr = itaddr; 756 /* XXX MRT use table 0 for arp reply */ 757 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 758 if (!rt) 759 goto drop; 760 761 /* 762 * Don't send proxies for nodes on the same interface 763 * as this one came out of, or we'll get into a fight 764 * over who claims what Ether address. 765 */ 766 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 767 RTFREE_LOCKED(rt); 768 goto drop; 769 } 770 RTFREE_LOCKED(rt); 771 772 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 773 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 774 775 /* 776 * Also check that the node which sent the ARP packet 777 * is on the the interface we expect it to be on. This 778 * avoids ARP chaos if an interface is connected to the 779 * wrong network. 780 */ 781 sin.sin_addr = isaddr; 782 783 /* XXX MRT use table 0 for arp checks */ 784 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 785 if (!rt) 786 goto drop; 787 if (rt->rt_ifp != ifp) { 788 log(LOG_INFO, "arp_proxy: ignoring request" 789 " from %s via %s, expecting %s\n", 790 inet_ntoa(isaddr), ifp->if_xname, 791 rt->rt_ifp->if_xname); 792 RTFREE_LOCKED(rt); 793 goto drop; 794 } 795 RTFREE_LOCKED(rt); 796 797 #ifdef DEBUG_PROXY 798 printf("arp: proxying for %s\n", 799 inet_ntoa(itaddr)); 800 #endif 801 } 802 } 803 804 if (itaddr.s_addr == myaddr.s_addr && 805 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 806 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 807 #ifdef DEBUG_LINKLOCAL 808 printf("arp: sending reply for link-local addr %s\n", 809 inet_ntoa(itaddr)); 810 #endif 811 m->m_flags |= M_BCAST; 812 m->m_flags &= ~M_MCAST; 813 } else { 814 /* default behaviour; never reply by broadcast. */ 815 m->m_flags &= ~(M_BCAST|M_MCAST); 816 } 817 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 818 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 819 ah->ar_op = htons(ARPOP_REPLY); 820 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 821 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 822 m->m_pkthdr.len = m->m_len; 823 sa.sa_family = AF_ARP; 824 sa.sa_len = 2; 825 (*ifp->if_output)(ifp, m, &sa, NULL); 826 ARPSTAT_INC(txreplies); 827 return; 828 829 drop: 830 m_freem(m); 831 } 832 #endif 833 834 void 835 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 836 { 837 struct llentry *lle; 838 839 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 840 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 841 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 842 /* 843 * interface address is considered static entry 844 * because the output of the arp utility shows 845 * that L2 entry as permanent 846 */ 847 IF_AFDATA_LOCK(ifp); 848 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 849 (struct sockaddr *)IA_SIN(ifa)); 850 IF_AFDATA_UNLOCK(ifp); 851 if (lle == NULL) 852 log(LOG_INFO, "arp_ifinit: cannot create arp " 853 "entry for interface address\n"); 854 else 855 LLE_RUNLOCK(lle); 856 } 857 ifa->ifa_rtrequest = NULL; 858 } 859 860 void 861 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 862 { 863 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 864 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 865 &IA_SIN(ifa)->sin_addr, enaddr); 866 ifa->ifa_rtrequest = NULL; 867 } 868 869 static void 870 arp_init(void) 871 { 872 873 netisr_register(&arp_nh); 874 } 875 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 876