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