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_var.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 #ifdef INET 69 #include <netinet/ip_carp.h> 70 #endif 71 72 #include <net/if_arc.h> 73 #include <net/iso88025.h> 74 75 #include <security/mac/mac_framework.h> 76 77 #define SIN(s) ((const struct sockaddr_in *)(s)) 78 #define SDL(s) ((struct sockaddr_dl *)s) 79 80 SYSCTL_DECL(_net_link_ether); 81 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 82 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 83 84 /* timer values */ 85 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 86 * minutes */ 87 static VNET_DEFINE(int, arp_maxtries) = 5; 88 static VNET_DEFINE(int, arp_proxyall) = 0; 89 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 90 * 20 seconds */ 91 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 92 VNET_PCPUSTAT_SYSINIT(arpstat); 93 94 #ifdef VIMAGE 95 VNET_PCPUSTAT_SYSUNINIT(arpstat); 96 #endif /* VIMAGE */ 97 98 static VNET_DEFINE(int, arp_maxhold) = 1; 99 100 #define V_arpt_keep VNET(arpt_keep) 101 #define V_arpt_down VNET(arpt_down) 102 #define V_arp_maxtries VNET(arp_maxtries) 103 #define V_arp_proxyall VNET(arp_proxyall) 104 #define V_arp_maxhold VNET(arp_maxhold) 105 106 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 107 &VNET_NAME(arpt_keep), 0, 108 "ARP entry lifetime in seconds"); 109 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 110 &VNET_NAME(arp_maxtries), 0, 111 "ARP resolution attempts before returning error"); 112 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 113 &VNET_NAME(arp_proxyall), 0, 114 "Enable proxy ARP for all suitable requests"); 115 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 116 &VNET_NAME(arpt_down), 0, 117 "Incomplete ARP entry lifetime in seconds"); 118 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 119 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 120 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 121 &VNET_NAME(arp_maxhold), 0, 122 "Number of packets to hold per ARP entry"); 123 124 static void arp_init(void); 125 static void arpintr(struct mbuf *); 126 static void arptimer(void *); 127 #ifdef INET 128 static void in_arpinput(struct mbuf *); 129 #endif 130 131 static const struct netisr_handler arp_nh = { 132 .nh_name = "arp", 133 .nh_handler = arpintr, 134 .nh_proto = NETISR_ARP, 135 .nh_policy = NETISR_POLICY_SOURCE, 136 }; 137 138 #ifdef AF_INET 139 /* 140 * called by in_scrubprefix() 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 IF_AFDATA_WLOCK(ifp); 153 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 154 (struct sockaddr *)&addr4); 155 IF_AFDATA_WUNLOCK(ifp); 156 } 157 #endif 158 159 /* 160 * Timeout routine. Age arp_tab entries periodically. 161 */ 162 static void 163 arptimer(void *arg) 164 { 165 struct llentry *lle = (struct llentry *)arg; 166 struct ifnet *ifp; 167 168 if (lle->la_flags & LLE_STATIC) { 169 return; 170 } 171 LLE_WLOCK(lle); 172 if (callout_pending(&lle->la_timer)) { 173 /* 174 * Here we are a bit odd here in the treatment of 175 * active/pending. If the pending bit is set, it got 176 * rescheduled before I ran. The active 177 * bit we ignore, since if it was stopped 178 * in ll_tablefree() and was currently running 179 * it would have return 0 so the code would 180 * not have deleted it since the callout could 181 * not be stopped so we want to go through 182 * with the delete here now. If the callout 183 * was restarted, the pending bit will be back on and 184 * we just want to bail since the callout_reset would 185 * return 1 and our reference would have been removed 186 * by arpresolve() below. 187 */ 188 LLE_WUNLOCK(lle); 189 return; 190 } 191 ifp = lle->lle_tbl->llt_ifp; 192 CURVNET_SET(ifp->if_vnet); 193 194 if ((lle->la_flags & LLE_DELETED) == 0) { 195 int evt; 196 197 if (lle->la_flags & LLE_VALID) 198 evt = LLENTRY_EXPIRED; 199 else 200 evt = LLENTRY_TIMEDOUT; 201 EVENTHANDLER_INVOKE(lle_event, lle, evt); 202 } 203 204 callout_stop(&lle->la_timer); 205 206 /* XXX: LOR avoidance. We still have ref on lle. */ 207 LLE_WUNLOCK(lle); 208 IF_AFDATA_LOCK(ifp); 209 LLE_WLOCK(lle); 210 211 /* Guard against race with other llentry_free(). */ 212 if (lle->la_flags & LLE_LINKED) { 213 size_t pkts_dropped; 214 215 LLE_REMREF(lle); 216 pkts_dropped = llentry_free(lle); 217 ARPSTAT_ADD(dropped, pkts_dropped); 218 } else 219 LLE_FREE_LOCKED(lle); 220 221 IF_AFDATA_UNLOCK(ifp); 222 223 ARPSTAT_INC(timeouts); 224 225 CURVNET_RESTORE(); 226 } 227 228 /* 229 * Broadcast an ARP request. Caller specifies: 230 * - arp header source ip address 231 * - arp header target ip address 232 * - arp header source ethernet address 233 */ 234 void 235 arprequest(struct ifnet *ifp, const struct in_addr *sip, 236 const struct in_addr *tip, u_char *enaddr) 237 { 238 struct mbuf *m; 239 struct arphdr *ah; 240 struct sockaddr sa; 241 u_char *carpaddr = NULL; 242 243 if (sip == NULL) { 244 /* 245 * The caller did not supply a source address, try to find 246 * a compatible one among those assigned to this interface. 247 */ 248 struct ifaddr *ifa; 249 250 IF_ADDR_RLOCK(ifp); 251 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 252 if (ifa->ifa_addr->sa_family != AF_INET) 253 continue; 254 255 if (ifa->ifa_carp) { 256 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 257 continue; 258 sip = &IA_SIN(ifa)->sin_addr; 259 } else { 260 carpaddr = NULL; 261 sip = &IA_SIN(ifa)->sin_addr; 262 } 263 264 if (0 == ((sip->s_addr ^ tip->s_addr) & 265 IA_MASKSIN(ifa)->sin_addr.s_addr)) 266 break; /* found it. */ 267 } 268 IF_ADDR_RUNLOCK(ifp); 269 if (sip == NULL) { 270 printf("%s: cannot find matching address\n", __func__); 271 return; 272 } 273 } 274 if (enaddr == NULL) 275 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 276 277 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 278 return; 279 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 280 2 * ifp->if_addrlen; 281 m->m_pkthdr.len = m->m_len; 282 M_ALIGN(m, m->m_len); 283 ah = mtod(m, struct arphdr *); 284 bzero((caddr_t)ah, m->m_len); 285 #ifdef MAC 286 mac_netinet_arp_send(ifp, m); 287 #endif 288 ah->ar_pro = htons(ETHERTYPE_IP); 289 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 290 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 291 ah->ar_op = htons(ARPOP_REQUEST); 292 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 293 bcopy(sip, ar_spa(ah), ah->ar_pln); 294 bcopy(tip, ar_tpa(ah), ah->ar_pln); 295 sa.sa_family = AF_ARP; 296 sa.sa_len = 2; 297 m->m_flags |= M_BCAST; 298 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 299 (*ifp->if_output)(ifp, m, &sa, NULL); 300 ARPSTAT_INC(txrequests); 301 } 302 303 /* 304 * Resolve an IP address into an ethernet address. 305 * On input: 306 * ifp is the interface we use 307 * is_gw != if @dst represents gateway to some destination 308 * m is the mbuf. May be NULL if we don't have a packet. 309 * dst is the next hop, 310 * desten is where we want the address. 311 * flags returns lle entry flags. 312 * 313 * On success, desten and flags are filled in and the function returns 0; 314 * If the packet must be held pending resolution, we return EWOULDBLOCK 315 * On other errors, we return the corresponding error code. 316 * Note that m_freem() handles NULL. 317 */ 318 int 319 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 320 const struct sockaddr *dst, u_char *desten, uint32_t *pflags) 321 { 322 struct llentry *la = 0; 323 u_int flags = 0; 324 struct mbuf *curr = NULL; 325 struct mbuf *next = NULL; 326 int error, renew; 327 328 if (pflags != NULL) 329 *pflags = 0; 330 331 if (m != NULL) { 332 if (m->m_flags & M_BCAST) { 333 /* broadcast */ 334 (void)memcpy(desten, 335 ifp->if_broadcastaddr, ifp->if_addrlen); 336 return (0); 337 } 338 if (m->m_flags & M_MCAST) { 339 /* multicast */ 340 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 341 return (0); 342 } 343 } 344 retry: 345 IF_AFDATA_RLOCK(ifp); 346 la = lla_lookup(LLTABLE(ifp), flags, dst); 347 IF_AFDATA_RUNLOCK(ifp); 348 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 349 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 350 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 351 IF_AFDATA_WLOCK(ifp); 352 la = lla_lookup(LLTABLE(ifp), flags, dst); 353 IF_AFDATA_WUNLOCK(ifp); 354 } 355 if (la == NULL) { 356 if (flags & LLE_CREATE) 357 log(LOG_DEBUG, 358 "arpresolve: can't allocate llinfo for %s on %s\n", 359 inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname); 360 m_freem(m); 361 return (EINVAL); 362 } 363 364 if ((la->la_flags & LLE_VALID) && 365 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 366 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 367 renew = 0; 368 /* 369 * If entry has an expiry time and it is approaching, 370 * see if we need to send an ARP request within this 371 * arpt_down interval. 372 */ 373 if (!(la->la_flags & LLE_STATIC) && 374 time_uptime + la->la_preempt > la->la_expire) { 375 renew = 1; 376 la->la_preempt--; 377 } 378 379 if (pflags != NULL) 380 *pflags = la->la_flags; 381 382 if (flags & LLE_EXCLUSIVE) 383 LLE_WUNLOCK(la); 384 else 385 LLE_RUNLOCK(la); 386 387 if (renew == 1) 388 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 389 390 return (0); 391 } 392 393 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 394 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 395 inet_ntoa(SIN(dst)->sin_addr)); 396 m_freem(m); 397 error = EINVAL; 398 goto done; 399 } 400 401 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 402 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 403 flags |= LLE_EXCLUSIVE; 404 LLE_RUNLOCK(la); 405 goto retry; 406 } 407 /* 408 * There is an arptab entry, but no ethernet address 409 * response yet. Add the mbuf to the list, dropping 410 * the oldest packet if we have exceeded the system 411 * setting. 412 */ 413 if (m != NULL) { 414 if (la->la_numheld >= V_arp_maxhold) { 415 if (la->la_hold != NULL) { 416 next = la->la_hold->m_nextpkt; 417 m_freem(la->la_hold); 418 la->la_hold = next; 419 la->la_numheld--; 420 ARPSTAT_INC(dropped); 421 } 422 } 423 if (la->la_hold != NULL) { 424 curr = la->la_hold; 425 while (curr->m_nextpkt != NULL) 426 curr = curr->m_nextpkt; 427 curr->m_nextpkt = m; 428 } else 429 la->la_hold = m; 430 la->la_numheld++; 431 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 432 flags &= ~LLE_EXCLUSIVE; 433 LLE_DOWNGRADE(la); 434 } 435 436 } 437 /* 438 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 439 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 440 * if we have already sent arp_maxtries ARP requests. Retransmit the 441 * ARP request, but not faster than one request per second. 442 */ 443 if (la->la_asked < V_arp_maxtries) 444 error = EWOULDBLOCK; /* First request. */ 445 else 446 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 447 448 if (renew) { 449 int canceled; 450 451 LLE_ADDREF(la); 452 la->la_expire = time_uptime; 453 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 454 arptimer, la); 455 if (canceled) 456 LLE_REMREF(la); 457 la->la_asked++; 458 LLE_WUNLOCK(la); 459 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 460 return (error); 461 } 462 done: 463 if (flags & LLE_EXCLUSIVE) 464 LLE_WUNLOCK(la); 465 else 466 LLE_RUNLOCK(la); 467 return (error); 468 } 469 470 /* 471 * Common length and type checks are done here, 472 * then the protocol-specific routine is called. 473 */ 474 static void 475 arpintr(struct mbuf *m) 476 { 477 struct arphdr *ar; 478 479 if (m->m_len < sizeof(struct arphdr) && 480 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 481 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 482 return; 483 } 484 ar = mtod(m, struct arphdr *); 485 486 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 487 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 488 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 489 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 490 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 491 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 492 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 493 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 494 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 495 m_freem(m); 496 return; 497 } 498 499 if (m->m_len < arphdr_len(ar)) { 500 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 501 log(LOG_NOTICE, "arp: runt packet\n"); 502 m_freem(m); 503 return; 504 } 505 ar = mtod(m, struct arphdr *); 506 } 507 508 ARPSTAT_INC(received); 509 switch (ntohs(ar->ar_pro)) { 510 #ifdef INET 511 case ETHERTYPE_IP: 512 in_arpinput(m); 513 return; 514 #endif 515 } 516 m_freem(m); 517 } 518 519 #ifdef INET 520 /* 521 * ARP for Internet protocols on 10 Mb/s Ethernet. 522 * Algorithm is that given in RFC 826. 523 * In addition, a sanity check is performed on the sender 524 * protocol address, to catch impersonators. 525 * We no longer handle negotiations for use of trailer protocol: 526 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 527 * along with IP replies if we wanted trailers sent to us, 528 * and also sent them in response to IP replies. 529 * This allowed either end to announce the desire to receive 530 * trailer packets. 531 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 532 * but formerly didn't normally send requests. 533 */ 534 static int log_arp_wrong_iface = 1; 535 static int log_arp_movements = 1; 536 static int log_arp_permanent_modify = 1; 537 static int allow_multicast = 0; 538 static struct timeval arp_lastlog; 539 static int arp_curpps; 540 static int arp_maxpps = 1; 541 542 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 543 &log_arp_wrong_iface, 0, 544 "log arp packets arriving on the wrong interface"); 545 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 546 &log_arp_movements, 0, 547 "log arp replies from MACs different than the one in the cache"); 548 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 549 &log_arp_permanent_modify, 0, 550 "log arp replies from MACs different than the one in the permanent arp entry"); 551 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 552 &allow_multicast, 0, "accept multicast addresses"); 553 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 554 CTLFLAG_RW, &arp_maxpps, 0, 555 "Maximum number of remotely triggered ARP messages that can be " 556 "logged per second"); 557 558 #define ARP_LOG(pri, ...) do { \ 559 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 560 log((pri), "arp: " __VA_ARGS__); \ 561 } while (0) 562 563 static void 564 in_arpinput(struct mbuf *m) 565 { 566 struct arphdr *ah; 567 struct ifnet *ifp = m->m_pkthdr.rcvif; 568 struct llentry *la = NULL; 569 struct rtentry *rt; 570 struct ifaddr *ifa; 571 struct in_ifaddr *ia; 572 struct sockaddr sa; 573 struct in_addr isaddr, itaddr, myaddr; 574 u_int8_t *enaddr = NULL; 575 int op, flags; 576 int req_len; 577 int bridged = 0, is_bridge = 0; 578 int carped; 579 struct sockaddr_in sin; 580 sin.sin_len = sizeof(struct sockaddr_in); 581 sin.sin_family = AF_INET; 582 sin.sin_addr.s_addr = 0; 583 584 if (ifp->if_bridge) 585 bridged = 1; 586 if (ifp->if_type == IFT_BRIDGE) 587 is_bridge = 1; 588 589 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 590 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 591 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n"); 592 return; 593 } 594 595 ah = mtod(m, struct arphdr *); 596 /* 597 * ARP is only for IPv4 so we can reject packets with 598 * a protocol length not equal to an IPv4 address. 599 */ 600 if (ah->ar_pln != sizeof(struct in_addr)) { 601 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 602 sizeof(struct in_addr)); 603 goto drop; 604 } 605 606 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 607 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 608 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 609 goto drop; 610 } 611 612 op = ntohs(ah->ar_op); 613 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 614 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 615 616 if (op == ARPOP_REPLY) 617 ARPSTAT_INC(rxreplies); 618 619 /* 620 * For a bridge, we want to check the address irrespective 621 * of the receive interface. (This will change slightly 622 * when we have clusters of interfaces). 623 */ 624 IN_IFADDR_RLOCK(); 625 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 626 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 627 ia->ia_ifp == ifp) && 628 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 629 (ia->ia_ifa.ifa_carp == NULL || 630 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 631 ifa_ref(&ia->ia_ifa); 632 IN_IFADDR_RUNLOCK(); 633 goto match; 634 } 635 } 636 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 637 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 638 ia->ia_ifp == ifp) && 639 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 640 ifa_ref(&ia->ia_ifa); 641 IN_IFADDR_RUNLOCK(); 642 goto match; 643 } 644 645 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 646 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 647 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 648 addr == ia->ia_addr.sin_addr.s_addr) 649 /* 650 * Check the case when bridge shares its MAC address with 651 * some of its children, so packets are claimed by bridge 652 * itself (bridge_input() does it first), but they are really 653 * meant to be destined to the bridge member. 654 */ 655 if (is_bridge) { 656 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 657 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 658 ifa_ref(&ia->ia_ifa); 659 ifp = ia->ia_ifp; 660 IN_IFADDR_RUNLOCK(); 661 goto match; 662 } 663 } 664 } 665 #undef BDG_MEMBER_MATCHES_ARP 666 IN_IFADDR_RUNLOCK(); 667 668 /* 669 * No match, use the first inet address on the receive interface 670 * as a dummy address for the rest of the function. 671 */ 672 IF_ADDR_RLOCK(ifp); 673 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 674 if (ifa->ifa_addr->sa_family == AF_INET && 675 (ifa->ifa_carp == NULL || 676 (*carp_iamatch_p)(ifa, &enaddr))) { 677 ia = ifatoia(ifa); 678 ifa_ref(ifa); 679 IF_ADDR_RUNLOCK(ifp); 680 goto match; 681 } 682 IF_ADDR_RUNLOCK(ifp); 683 684 /* 685 * If bridging, fall back to using any inet address. 686 */ 687 IN_IFADDR_RLOCK(); 688 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 689 IN_IFADDR_RUNLOCK(); 690 goto drop; 691 } 692 ifa_ref(&ia->ia_ifa); 693 IN_IFADDR_RUNLOCK(); 694 match: 695 if (!enaddr) 696 enaddr = (u_int8_t *)IF_LLADDR(ifp); 697 carped = (ia->ia_ifa.ifa_carp != NULL); 698 myaddr = ia->ia_addr.sin_addr; 699 ifa_free(&ia->ia_ifa); 700 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 701 goto drop; /* it's from me, ignore it. */ 702 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 703 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 704 "%s!\n", inet_ntoa(isaddr)); 705 goto drop; 706 } 707 /* 708 * Warn if another host is using the same IP address, but only if the 709 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 710 * case we suppress the warning to avoid false positive complaints of 711 * potential misconfiguration. 712 */ 713 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 714 myaddr.s_addr != 0) { 715 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 716 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 717 inet_ntoa(isaddr), ifp->if_xname); 718 itaddr = myaddr; 719 ARPSTAT_INC(dupips); 720 goto reply; 721 } 722 if (ifp->if_flags & IFF_STATICARP) 723 goto reply; 724 725 bzero(&sin, sizeof(sin)); 726 sin.sin_len = sizeof(struct sockaddr_in); 727 sin.sin_family = AF_INET; 728 sin.sin_addr = isaddr; 729 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 730 flags |= LLE_EXCLUSIVE; 731 IF_AFDATA_LOCK(ifp); 732 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 733 IF_AFDATA_UNLOCK(ifp); 734 if (la != NULL) { 735 /* the following is not an error when doing bridging */ 736 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 737 if (log_arp_wrong_iface) 738 ARP_LOG(LOG_WARNING, "%s is on %s " 739 "but got reply from %*D on %s\n", 740 inet_ntoa(isaddr), 741 la->lle_tbl->llt_ifp->if_xname, 742 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 743 ifp->if_xname); 744 LLE_WUNLOCK(la); 745 goto reply; 746 } 747 if ((la->la_flags & LLE_VALID) && 748 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 749 if (la->la_flags & LLE_STATIC) { 750 LLE_WUNLOCK(la); 751 if (log_arp_permanent_modify) 752 ARP_LOG(LOG_ERR, 753 "%*D attempts to modify " 754 "permanent entry for %s on %s\n", 755 ifp->if_addrlen, 756 (u_char *)ar_sha(ah), ":", 757 inet_ntoa(isaddr), ifp->if_xname); 758 goto reply; 759 } 760 if (log_arp_movements) { 761 ARP_LOG(LOG_INFO, "%s moved from %*D " 762 "to %*D on %s\n", 763 inet_ntoa(isaddr), 764 ifp->if_addrlen, 765 (u_char *)&la->ll_addr, ":", 766 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 767 ifp->if_xname); 768 } 769 } 770 771 if (ifp->if_addrlen != ah->ar_hln) { 772 LLE_WUNLOCK(la); 773 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 774 "i/f %d (ignored)\n", ifp->if_addrlen, 775 (u_char *) ar_sha(ah), ":", ah->ar_hln, 776 ifp->if_addrlen); 777 goto drop; 778 } 779 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 780 la->la_flags |= LLE_VALID; 781 782 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 783 784 if (!(la->la_flags & LLE_STATIC)) { 785 int canceled; 786 787 LLE_ADDREF(la); 788 la->la_expire = time_uptime + V_arpt_keep; 789 canceled = callout_reset(&la->la_timer, 790 hz * V_arpt_keep, arptimer, la); 791 if (canceled) 792 LLE_REMREF(la); 793 } 794 la->la_asked = 0; 795 la->la_preempt = V_arp_maxtries; 796 /* 797 * The packets are all freed within the call to the output 798 * routine. 799 * 800 * NB: The lock MUST be released before the call to the 801 * output routine. 802 */ 803 if (la->la_hold != NULL) { 804 struct mbuf *m_hold, *m_hold_next; 805 806 m_hold = la->la_hold; 807 la->la_hold = NULL; 808 la->la_numheld = 0; 809 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 810 LLE_WUNLOCK(la); 811 for (; m_hold != NULL; m_hold = m_hold_next) { 812 m_hold_next = m_hold->m_nextpkt; 813 m_hold->m_nextpkt = NULL; 814 /* Avoid confusing lower layers. */ 815 m_clrprotoflags(m_hold); 816 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 817 } 818 } else 819 LLE_WUNLOCK(la); 820 } 821 reply: 822 if (op != ARPOP_REQUEST) 823 goto drop; 824 ARPSTAT_INC(rxrequests); 825 826 if (itaddr.s_addr == myaddr.s_addr) { 827 /* Shortcut.. the receiving interface is the target. */ 828 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 829 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 830 } else { 831 struct llentry *lle = NULL; 832 833 sin.sin_addr = itaddr; 834 IF_AFDATA_RLOCK(ifp); 835 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 836 IF_AFDATA_RUNLOCK(ifp); 837 838 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 839 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 840 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 841 LLE_RUNLOCK(lle); 842 } else { 843 844 if (lle != NULL) 845 LLE_RUNLOCK(lle); 846 847 if (!V_arp_proxyall) 848 goto drop; 849 850 sin.sin_addr = itaddr; 851 /* XXX MRT use table 0 for arp reply */ 852 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 853 if (!rt) 854 goto drop; 855 856 /* 857 * Don't send proxies for nodes on the same interface 858 * as this one came out of, or we'll get into a fight 859 * over who claims what Ether address. 860 */ 861 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 862 RTFREE_LOCKED(rt); 863 goto drop; 864 } 865 RTFREE_LOCKED(rt); 866 867 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 868 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 869 870 /* 871 * Also check that the node which sent the ARP packet 872 * is on the interface we expect it to be on. This 873 * avoids ARP chaos if an interface is connected to the 874 * wrong network. 875 */ 876 sin.sin_addr = isaddr; 877 878 /* XXX MRT use table 0 for arp checks */ 879 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 880 if (!rt) 881 goto drop; 882 if (rt->rt_ifp != ifp) { 883 ARP_LOG(LOG_INFO, "proxy: ignoring request" 884 " from %s via %s, expecting %s\n", 885 inet_ntoa(isaddr), ifp->if_xname, 886 rt->rt_ifp->if_xname); 887 RTFREE_LOCKED(rt); 888 goto drop; 889 } 890 RTFREE_LOCKED(rt); 891 892 #ifdef DEBUG_PROXY 893 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 894 #endif 895 } 896 } 897 898 if (itaddr.s_addr == myaddr.s_addr && 899 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 900 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 901 #ifdef DEBUG_LINKLOCAL 902 printf("arp: sending reply for link-local addr %s\n", 903 inet_ntoa(itaddr)); 904 #endif 905 m->m_flags |= M_BCAST; 906 m->m_flags &= ~M_MCAST; 907 } else { 908 /* default behaviour; never reply by broadcast. */ 909 m->m_flags &= ~(M_BCAST|M_MCAST); 910 } 911 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 912 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 913 ah->ar_op = htons(ARPOP_REPLY); 914 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 915 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 916 m->m_pkthdr.len = m->m_len; 917 m->m_pkthdr.rcvif = NULL; 918 sa.sa_family = AF_ARP; 919 sa.sa_len = 2; 920 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 921 (*ifp->if_output)(ifp, m, &sa, NULL); 922 ARPSTAT_INC(txreplies); 923 return; 924 925 drop: 926 m_freem(m); 927 } 928 #endif 929 930 void 931 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 932 { 933 struct llentry *lle; 934 935 if (ifa->ifa_carp != NULL) 936 return; 937 938 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 939 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 940 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 941 /* 942 * interface address is considered static entry 943 * because the output of the arp utility shows 944 * that L2 entry as permanent 945 */ 946 IF_AFDATA_LOCK(ifp); 947 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 948 (struct sockaddr *)IA_SIN(ifa)); 949 IF_AFDATA_UNLOCK(ifp); 950 if (lle == NULL) 951 log(LOG_INFO, "arp_ifinit: cannot create arp " 952 "entry for interface address\n"); 953 else 954 LLE_RUNLOCK(lle); 955 } 956 ifa->ifa_rtrequest = NULL; 957 } 958 959 void 960 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 961 { 962 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 963 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 964 &IA_SIN(ifa)->sin_addr, enaddr); 965 ifa->ifa_rtrequest = NULL; 966 } 967 968 static void 969 arp_init(void) 970 { 971 972 netisr_register(&arp_nh); 973 } 974 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 975