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 #ifdef INET 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) ((const struct sockaddr_in *)(s)) 77 #define SDL(s) ((struct sockaddr_dl *)s) 78 79 SYSCTL_DECL(_net_link_ether); 80 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 81 static 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 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 93 VNET_PCPUSTAT_SYSINIT(arpstat); 94 95 #ifdef VIMAGE 96 VNET_PCPUSTAT_SYSUNINIT(arpstat); 97 #endif /* VIMAGE */ 98 99 static VNET_DEFINE(int, arp_maxhold) = 1; 100 101 #define V_arpt_keep VNET(arpt_keep) 102 #define V_arpt_down VNET(arpt_down) 103 #define V_arp_maxtries VNET(arp_maxtries) 104 #define V_arp_proxyall VNET(arp_proxyall) 105 #define V_arp_maxhold VNET(arp_maxhold) 106 107 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 108 &VNET_NAME(arpt_keep), 0, 109 "ARP entry lifetime in seconds"); 110 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 111 &VNET_NAME(arp_maxtries), 0, 112 "ARP resolution attempts before returning error"); 113 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 114 &VNET_NAME(useloopback), 0, 115 "Use the loopback interface for local traffic"); 116 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 117 &VNET_NAME(arp_proxyall), 0, 118 "Enable proxy ARP for all suitable requests"); 119 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW, 120 &VNET_NAME(arpt_down), 0, 121 "Incomplete ARP entry lifetime in seconds"); 122 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 123 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 124 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW, 125 &VNET_NAME(arp_maxhold), 0, 126 "Number of packets to hold per ARP entry"); 127 128 static void arp_init(void); 129 static void arpintr(struct mbuf *); 130 static void arptimer(void *); 131 #ifdef INET 132 static void in_arpinput(struct mbuf *); 133 #endif 134 135 static const struct netisr_handler arp_nh = { 136 .nh_name = "arp", 137 .nh_handler = arpintr, 138 .nh_proto = NETISR_ARP, 139 .nh_policy = NETISR_POLICY_SOURCE, 140 }; 141 142 #ifdef AF_INET 143 /* 144 * called by in_ifscrub to remove entry from the table when 145 * the interface goes away 146 */ 147 void 148 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 149 { 150 struct sockaddr_in addr4; 151 152 bzero((void *)&addr4, sizeof(addr4)); 153 addr4.sin_len = sizeof(addr4); 154 addr4.sin_family = AF_INET; 155 addr4.sin_addr.s_addr = addr; 156 IF_AFDATA_LOCK(ifp); 157 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 158 (struct sockaddr *)&addr4); 159 IF_AFDATA_UNLOCK(ifp); 160 } 161 #endif 162 163 /* 164 * Timeout routine. Age arp_tab entries periodically. 165 */ 166 static void 167 arptimer(void *arg) 168 { 169 struct llentry *lle = (struct llentry *)arg; 170 struct ifnet *ifp; 171 172 if (lle->la_flags & LLE_STATIC) { 173 LLE_WUNLOCK(lle); 174 return; 175 } 176 177 ifp = lle->lle_tbl->llt_ifp; 178 CURVNET_SET(ifp->if_vnet); 179 180 if ((lle->la_flags & LLE_DELETED) == 0) { 181 int evt; 182 183 if (lle->la_flags & LLE_VALID) 184 evt = LLENTRY_EXPIRED; 185 else 186 evt = LLENTRY_TIMEDOUT; 187 EVENTHANDLER_INVOKE(lle_event, lle, evt); 188 } 189 190 callout_stop(&lle->la_timer); 191 192 /* XXX: LOR avoidance. We still have ref on lle. */ 193 LLE_WUNLOCK(lle); 194 IF_AFDATA_LOCK(ifp); 195 LLE_WLOCK(lle); 196 197 /* Guard against race with other llentry_free(). */ 198 if (lle->la_flags & LLE_LINKED) { 199 size_t pkts_dropped; 200 201 LLE_REMREF(lle); 202 pkts_dropped = llentry_free(lle); 203 ARPSTAT_ADD(dropped, pkts_dropped); 204 } else 205 LLE_FREE_LOCKED(lle); 206 207 IF_AFDATA_UNLOCK(ifp); 208 209 ARPSTAT_INC(timeouts); 210 211 CURVNET_RESTORE(); 212 } 213 214 /* 215 * Broadcast an ARP request. Caller specifies: 216 * - arp header source ip address 217 * - arp header target ip address 218 * - arp header source ethernet address 219 */ 220 void 221 arprequest(struct ifnet *ifp, const struct in_addr *sip, 222 const struct in_addr *tip, u_char *enaddr) 223 { 224 struct mbuf *m; 225 struct arphdr *ah; 226 struct sockaddr sa; 227 u_char *carpaddr = NULL; 228 229 if (sip == NULL) { 230 /* 231 * The caller did not supply a source address, try to find 232 * a compatible one among those assigned to this interface. 233 */ 234 struct ifaddr *ifa; 235 236 IF_ADDR_RLOCK(ifp); 237 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 238 if (ifa->ifa_addr->sa_family != AF_INET) 239 continue; 240 241 if (ifa->ifa_carp) { 242 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 243 continue; 244 sip = &IA_SIN(ifa)->sin_addr; 245 } else { 246 carpaddr = NULL; 247 sip = &IA_SIN(ifa)->sin_addr; 248 } 249 250 if (0 == ((sip->s_addr ^ tip->s_addr) & 251 IA_MASKSIN(ifa)->sin_addr.s_addr)) 252 break; /* found it. */ 253 } 254 IF_ADDR_RUNLOCK(ifp); 255 if (sip == NULL) { 256 printf("%s: cannot find matching address\n", __func__); 257 return; 258 } 259 } 260 if (enaddr == NULL) 261 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 262 263 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 264 return; 265 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 266 2*ifp->if_data.ifi_addrlen; 267 m->m_pkthdr.len = m->m_len; 268 MH_ALIGN(m, m->m_len); 269 ah = mtod(m, struct arphdr *); 270 bzero((caddr_t)ah, m->m_len); 271 #ifdef MAC 272 mac_netinet_arp_send(ifp, m); 273 #endif 274 ah->ar_pro = htons(ETHERTYPE_IP); 275 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 276 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 277 ah->ar_op = htons(ARPOP_REQUEST); 278 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 279 bcopy(sip, ar_spa(ah), ah->ar_pln); 280 bcopy(tip, ar_tpa(ah), ah->ar_pln); 281 sa.sa_family = AF_ARP; 282 sa.sa_len = 2; 283 m->m_flags |= M_BCAST; 284 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 285 (*ifp->if_output)(ifp, m, &sa, NULL); 286 ARPSTAT_INC(txrequests); 287 } 288 289 /* 290 * Resolve an IP address into an ethernet address. 291 * On input: 292 * ifp is the interface we use 293 * rt0 is the route to the final destination (possibly useless) 294 * m is the mbuf. May be NULL if we don't have a packet. 295 * dst is the next hop, 296 * desten is where we want the address. 297 * 298 * On success, desten is filled in and the function returns 0; 299 * If the packet must be held pending resolution, we return EWOULDBLOCK 300 * On other errors, we return the corresponding error code. 301 * Note that m_freem() handles NULL. 302 */ 303 int 304 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 305 const struct sockaddr *dst, u_char *desten, struct llentry **lle) 306 { 307 struct llentry *la = 0; 308 u_int flags = 0; 309 struct mbuf *curr = NULL; 310 struct mbuf *next = NULL; 311 int error, renew; 312 313 *lle = NULL; 314 if (m != NULL) { 315 if (m->m_flags & M_BCAST) { 316 /* broadcast */ 317 (void)memcpy(desten, 318 ifp->if_broadcastaddr, ifp->if_addrlen); 319 return (0); 320 } 321 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 322 /* multicast */ 323 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 324 return (0); 325 } 326 } 327 retry: 328 IF_AFDATA_RLOCK(ifp); 329 la = lla_lookup(LLTABLE(ifp), flags, dst); 330 IF_AFDATA_RUNLOCK(ifp); 331 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 332 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 333 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 334 IF_AFDATA_WLOCK(ifp); 335 la = lla_lookup(LLTABLE(ifp), flags, dst); 336 IF_AFDATA_WUNLOCK(ifp); 337 } 338 if (la == NULL) { 339 if (flags & LLE_CREATE) 340 log(LOG_DEBUG, 341 "arpresolve: can't allocate llinfo for %s\n", 342 inet_ntoa(SIN(dst)->sin_addr)); 343 m_freem(m); 344 return (EINVAL); 345 } 346 347 if ((la->la_flags & LLE_VALID) && 348 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 349 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 350 /* 351 * If entry has an expiry time and it is approaching, 352 * see if we need to send an ARP request within this 353 * arpt_down interval. 354 */ 355 if (!(la->la_flags & LLE_STATIC) && 356 time_uptime + la->la_preempt > la->la_expire) { 357 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 358 la->la_preempt--; 359 } 360 361 *lle = la; 362 error = 0; 363 goto done; 364 } 365 366 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 367 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 368 inet_ntoa(SIN(dst)->sin_addr)); 369 m_freem(m); 370 error = EINVAL; 371 goto done; 372 } 373 374 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 375 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 376 flags |= LLE_EXCLUSIVE; 377 LLE_RUNLOCK(la); 378 goto retry; 379 } 380 /* 381 * There is an arptab entry, but no ethernet address 382 * response yet. Add the mbuf to the list, dropping 383 * the oldest packet if we have exceeded the system 384 * setting. 385 */ 386 if (m != NULL) { 387 if (la->la_numheld >= V_arp_maxhold) { 388 if (la->la_hold != NULL) { 389 next = la->la_hold->m_nextpkt; 390 m_freem(la->la_hold); 391 la->la_hold = next; 392 la->la_numheld--; 393 ARPSTAT_INC(dropped); 394 } 395 } 396 if (la->la_hold != NULL) { 397 curr = la->la_hold; 398 while (curr->m_nextpkt != NULL) 399 curr = curr->m_nextpkt; 400 curr->m_nextpkt = m; 401 } else 402 la->la_hold = m; 403 la->la_numheld++; 404 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 405 flags &= ~LLE_EXCLUSIVE; 406 LLE_DOWNGRADE(la); 407 } 408 409 } 410 /* 411 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 412 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 413 * if we have already sent arp_maxtries ARP requests. Retransmit the 414 * ARP request, but not faster than one request per second. 415 */ 416 if (la->la_asked < V_arp_maxtries) 417 error = EWOULDBLOCK; /* First request. */ 418 else 419 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 420 EHOSTUNREACH : EHOSTDOWN; 421 422 if (renew) { 423 int canceled; 424 425 LLE_ADDREF(la); 426 la->la_expire = time_uptime; 427 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 428 arptimer, la); 429 if (canceled) 430 LLE_REMREF(la); 431 la->la_asked++; 432 LLE_WUNLOCK(la); 433 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 434 return (error); 435 } 436 done: 437 if (flags & LLE_EXCLUSIVE) 438 LLE_WUNLOCK(la); 439 else 440 LLE_RUNLOCK(la); 441 return (error); 442 } 443 444 /* 445 * Common length and type checks are done here, 446 * then the protocol-specific routine is called. 447 */ 448 static void 449 arpintr(struct mbuf *m) 450 { 451 struct arphdr *ar; 452 453 if (m->m_len < sizeof(struct arphdr) && 454 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 455 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 456 return; 457 } 458 ar = mtod(m, struct arphdr *); 459 460 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 461 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 462 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 463 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 464 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 465 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 466 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 467 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 468 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 469 m_freem(m); 470 return; 471 } 472 473 if (m->m_len < arphdr_len(ar)) { 474 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 475 log(LOG_NOTICE, "arp: runt packet\n"); 476 m_freem(m); 477 return; 478 } 479 ar = mtod(m, struct arphdr *); 480 } 481 482 ARPSTAT_INC(received); 483 switch (ntohs(ar->ar_pro)) { 484 #ifdef INET 485 case ETHERTYPE_IP: 486 in_arpinput(m); 487 return; 488 #endif 489 } 490 m_freem(m); 491 } 492 493 #ifdef INET 494 /* 495 * ARP for Internet protocols on 10 Mb/s Ethernet. 496 * Algorithm is that given in RFC 826. 497 * In addition, a sanity check is performed on the sender 498 * protocol address, to catch impersonators. 499 * We no longer handle negotiations for use of trailer protocol: 500 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 501 * along with IP replies if we wanted trailers sent to us, 502 * and also sent them in response to IP replies. 503 * This allowed either end to announce the desire to receive 504 * trailer packets. 505 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 506 * but formerly didn't normally send requests. 507 */ 508 static int log_arp_wrong_iface = 1; 509 static int log_arp_movements = 1; 510 static int log_arp_permanent_modify = 1; 511 static int allow_multicast = 0; 512 static struct timeval arp_lastlog; 513 static int arp_curpps; 514 static int arp_maxpps = 1; 515 516 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 517 &log_arp_wrong_iface, 0, 518 "log arp packets arriving on the wrong interface"); 519 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 520 &log_arp_movements, 0, 521 "log arp replies from MACs different than the one in the cache"); 522 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 523 &log_arp_permanent_modify, 0, 524 "log arp replies from MACs different than the one in the permanent arp entry"); 525 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 526 &allow_multicast, 0, "accept multicast addresses"); 527 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 528 CTLFLAG_RW, &arp_maxpps, 0, 529 "Maximum number of remotely triggered ARP messages that can be " 530 "logged per second"); 531 532 #define ARP_LOG(pri, ...) do { \ 533 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 534 log((pri), "arp: " __VA_ARGS__); \ 535 } while (0) 536 537 static void 538 in_arpinput(struct mbuf *m) 539 { 540 struct arphdr *ah; 541 struct ifnet *ifp = m->m_pkthdr.rcvif; 542 struct llentry *la = NULL; 543 struct rtentry *rt; 544 struct ifaddr *ifa; 545 struct in_ifaddr *ia; 546 struct sockaddr sa; 547 struct in_addr isaddr, itaddr, myaddr; 548 u_int8_t *enaddr = NULL; 549 int op, flags; 550 int req_len; 551 int bridged = 0, is_bridge = 0; 552 int carped; 553 struct sockaddr_in sin; 554 sin.sin_len = sizeof(struct sockaddr_in); 555 sin.sin_family = AF_INET; 556 sin.sin_addr.s_addr = 0; 557 558 if (ifp->if_bridge) 559 bridged = 1; 560 if (ifp->if_type == IFT_BRIDGE) 561 is_bridge = 1; 562 563 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 564 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 565 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n"); 566 return; 567 } 568 569 ah = mtod(m, struct arphdr *); 570 /* 571 * ARP is only for IPv4 so we can reject packets with 572 * a protocol length not equal to an IPv4 address. 573 */ 574 if (ah->ar_pln != sizeof(struct in_addr)) { 575 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 576 sizeof(struct in_addr)); 577 goto drop; 578 } 579 580 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 581 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 582 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 583 goto drop; 584 } 585 586 op = ntohs(ah->ar_op); 587 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 588 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 589 590 if (op == ARPOP_REPLY) 591 ARPSTAT_INC(rxreplies); 592 593 /* 594 * For a bridge, we want to check the address irrespective 595 * of the receive interface. (This will change slightly 596 * when we have clusters of interfaces). 597 */ 598 IN_IFADDR_RLOCK(); 599 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 600 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 601 ia->ia_ifp == ifp) && 602 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 603 (ia->ia_ifa.ifa_carp == NULL || 604 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 605 ifa_ref(&ia->ia_ifa); 606 IN_IFADDR_RUNLOCK(); 607 goto match; 608 } 609 } 610 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 611 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 612 ia->ia_ifp == ifp) && 613 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 614 ifa_ref(&ia->ia_ifa); 615 IN_IFADDR_RUNLOCK(); 616 goto match; 617 } 618 619 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 620 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 621 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 622 addr == ia->ia_addr.sin_addr.s_addr) 623 /* 624 * Check the case when bridge shares its MAC address with 625 * some of its children, so packets are claimed by bridge 626 * itself (bridge_input() does it first), but they are really 627 * meant to be destined to the bridge member. 628 */ 629 if (is_bridge) { 630 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 631 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 632 ifa_ref(&ia->ia_ifa); 633 ifp = ia->ia_ifp; 634 IN_IFADDR_RUNLOCK(); 635 goto match; 636 } 637 } 638 } 639 #undef BDG_MEMBER_MATCHES_ARP 640 IN_IFADDR_RUNLOCK(); 641 642 /* 643 * No match, use the first inet address on the receive interface 644 * as a dummy address for the rest of the function. 645 */ 646 IF_ADDR_RLOCK(ifp); 647 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 648 if (ifa->ifa_addr->sa_family == AF_INET && 649 (ifa->ifa_carp == NULL || 650 (*carp_iamatch_p)(ifa, &enaddr))) { 651 ia = ifatoia(ifa); 652 ifa_ref(ifa); 653 IF_ADDR_RUNLOCK(ifp); 654 goto match; 655 } 656 IF_ADDR_RUNLOCK(ifp); 657 658 /* 659 * If bridging, fall back to using any inet address. 660 */ 661 IN_IFADDR_RLOCK(); 662 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 663 IN_IFADDR_RUNLOCK(); 664 goto drop; 665 } 666 ifa_ref(&ia->ia_ifa); 667 IN_IFADDR_RUNLOCK(); 668 match: 669 if (!enaddr) 670 enaddr = (u_int8_t *)IF_LLADDR(ifp); 671 carped = (ia->ia_ifa.ifa_carp != NULL); 672 myaddr = ia->ia_addr.sin_addr; 673 ifa_free(&ia->ia_ifa); 674 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 675 goto drop; /* it's from me, ignore it. */ 676 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 677 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 678 "%s!\n", inet_ntoa(isaddr)); 679 goto drop; 680 } 681 /* 682 * Warn if another host is using the same IP address, but only if the 683 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 684 * case we suppress the warning to avoid false positive complaints of 685 * potential misconfiguration. 686 */ 687 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 688 myaddr.s_addr != 0) { 689 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 690 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 691 inet_ntoa(isaddr), ifp->if_xname); 692 itaddr = myaddr; 693 ARPSTAT_INC(dupips); 694 goto reply; 695 } 696 if (ifp->if_flags & IFF_STATICARP) 697 goto reply; 698 699 bzero(&sin, sizeof(sin)); 700 sin.sin_len = sizeof(struct sockaddr_in); 701 sin.sin_family = AF_INET; 702 sin.sin_addr = isaddr; 703 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 704 flags |= LLE_EXCLUSIVE; 705 IF_AFDATA_LOCK(ifp); 706 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 707 IF_AFDATA_UNLOCK(ifp); 708 if (la != NULL) { 709 /* the following is not an error when doing bridging */ 710 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 711 if (log_arp_wrong_iface) 712 ARP_LOG(LOG_WARNING, "%s is on %s " 713 "but got reply from %*D on %s\n", 714 inet_ntoa(isaddr), 715 la->lle_tbl->llt_ifp->if_xname, 716 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 717 ifp->if_xname); 718 LLE_WUNLOCK(la); 719 goto reply; 720 } 721 if ((la->la_flags & LLE_VALID) && 722 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 723 if (la->la_flags & LLE_STATIC) { 724 LLE_WUNLOCK(la); 725 if (log_arp_permanent_modify) 726 ARP_LOG(LOG_ERR, 727 "%*D attempts to modify " 728 "permanent entry for %s on %s\n", 729 ifp->if_addrlen, 730 (u_char *)ar_sha(ah), ":", 731 inet_ntoa(isaddr), ifp->if_xname); 732 goto reply; 733 } 734 if (log_arp_movements) { 735 ARP_LOG(LOG_INFO, "%s moved from %*D " 736 "to %*D on %s\n", 737 inet_ntoa(isaddr), 738 ifp->if_addrlen, 739 (u_char *)&la->ll_addr, ":", 740 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 741 ifp->if_xname); 742 } 743 } 744 745 if (ifp->if_addrlen != ah->ar_hln) { 746 LLE_WUNLOCK(la); 747 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 748 "i/f %d (ignored)\n", ifp->if_addrlen, 749 (u_char *) ar_sha(ah), ":", ah->ar_hln, 750 ifp->if_addrlen); 751 goto drop; 752 } 753 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 754 la->la_flags |= LLE_VALID; 755 756 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 757 758 if (!(la->la_flags & LLE_STATIC)) { 759 int canceled; 760 761 LLE_ADDREF(la); 762 la->la_expire = time_uptime + V_arpt_keep; 763 canceled = callout_reset(&la->la_timer, 764 hz * V_arpt_keep, arptimer, la); 765 if (canceled) 766 LLE_REMREF(la); 767 } 768 la->la_asked = 0; 769 la->la_preempt = V_arp_maxtries; 770 /* 771 * The packets are all freed within the call to the output 772 * routine. 773 * 774 * NB: The lock MUST be released before the call to the 775 * output routine. 776 */ 777 if (la->la_hold != NULL) { 778 struct mbuf *m_hold, *m_hold_next; 779 780 m_hold = la->la_hold; 781 la->la_hold = NULL; 782 la->la_numheld = 0; 783 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 784 LLE_WUNLOCK(la); 785 for (; m_hold != NULL; m_hold = m_hold_next) { 786 m_hold_next = m_hold->m_nextpkt; 787 m_hold->m_nextpkt = NULL; 788 /* Avoid confusing lower layers. */ 789 m_clrprotoflags(m_hold); 790 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 791 } 792 } else 793 LLE_WUNLOCK(la); 794 } 795 reply: 796 if (op != ARPOP_REQUEST) 797 goto drop; 798 ARPSTAT_INC(rxrequests); 799 800 if (itaddr.s_addr == myaddr.s_addr) { 801 /* Shortcut.. the receiving interface is the target. */ 802 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 803 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 804 } else { 805 struct llentry *lle = NULL; 806 807 sin.sin_addr = itaddr; 808 IF_AFDATA_LOCK(ifp); 809 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 810 IF_AFDATA_UNLOCK(ifp); 811 812 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 813 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 814 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 815 LLE_RUNLOCK(lle); 816 } else { 817 818 if (lle != NULL) 819 LLE_RUNLOCK(lle); 820 821 if (!V_arp_proxyall) 822 goto drop; 823 824 sin.sin_addr = itaddr; 825 /* XXX MRT use table 0 for arp reply */ 826 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 827 if (!rt) 828 goto drop; 829 830 /* 831 * Don't send proxies for nodes on the same interface 832 * as this one came out of, or we'll get into a fight 833 * over who claims what Ether address. 834 */ 835 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 836 RTFREE_LOCKED(rt); 837 goto drop; 838 } 839 RTFREE_LOCKED(rt); 840 841 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 842 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 843 844 /* 845 * Also check that the node which sent the ARP packet 846 * is on the interface we expect it to be on. This 847 * avoids ARP chaos if an interface is connected to the 848 * wrong network. 849 */ 850 sin.sin_addr = isaddr; 851 852 /* XXX MRT use table 0 for arp checks */ 853 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 854 if (!rt) 855 goto drop; 856 if (rt->rt_ifp != ifp) { 857 ARP_LOG(LOG_INFO, "proxy: ignoring request" 858 " from %s via %s, expecting %s\n", 859 inet_ntoa(isaddr), ifp->if_xname, 860 rt->rt_ifp->if_xname); 861 RTFREE_LOCKED(rt); 862 goto drop; 863 } 864 RTFREE_LOCKED(rt); 865 866 #ifdef DEBUG_PROXY 867 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 868 #endif 869 } 870 } 871 872 if (itaddr.s_addr == myaddr.s_addr && 873 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 874 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 875 #ifdef DEBUG_LINKLOCAL 876 printf("arp: sending reply for link-local addr %s\n", 877 inet_ntoa(itaddr)); 878 #endif 879 m->m_flags |= M_BCAST; 880 m->m_flags &= ~M_MCAST; 881 } else { 882 /* default behaviour; never reply by broadcast. */ 883 m->m_flags &= ~(M_BCAST|M_MCAST); 884 } 885 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 886 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 887 ah->ar_op = htons(ARPOP_REPLY); 888 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 889 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 890 m->m_pkthdr.len = m->m_len; 891 m->m_pkthdr.rcvif = NULL; 892 sa.sa_family = AF_ARP; 893 sa.sa_len = 2; 894 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 895 (*ifp->if_output)(ifp, m, &sa, NULL); 896 ARPSTAT_INC(txreplies); 897 return; 898 899 drop: 900 m_freem(m); 901 } 902 #endif 903 904 void 905 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 906 { 907 struct llentry *lle; 908 909 if (ifa->ifa_carp != NULL) 910 return; 911 912 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 913 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 914 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 915 /* 916 * interface address is considered static entry 917 * because the output of the arp utility shows 918 * that L2 entry as permanent 919 */ 920 IF_AFDATA_LOCK(ifp); 921 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 922 (struct sockaddr *)IA_SIN(ifa)); 923 IF_AFDATA_UNLOCK(ifp); 924 if (lle == NULL) 925 log(LOG_INFO, "arp_ifinit: cannot create arp " 926 "entry for interface address\n"); 927 else 928 LLE_RUNLOCK(lle); 929 } 930 ifa->ifa_rtrequest = NULL; 931 } 932 933 void 934 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 935 { 936 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 937 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 938 &IA_SIN(ifa)->sin_addr, enaddr); 939 ifa->ifa_rtrequest = NULL; 940 } 941 942 static void 943 arp_init(void) 944 { 945 946 netisr_register(&arp_nh); 947 } 948 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 949