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/lock.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/rmlock.h> 53 #include <sys/socket.h> 54 #include <sys/syslog.h> 55 56 #include <net/if.h> 57 #include <net/if_var.h> 58 #include <net/if_dl.h> 59 #include <net/if_types.h> 60 #include <net/netisr.h> 61 #include <net/if_llc.h> 62 #include <net/ethernet.h> 63 #include <net/route.h> 64 #include <net/vnet.h> 65 66 #include <netinet/in.h> 67 #include <netinet/in_var.h> 68 #include <net/if_llatbl.h> 69 #include <netinet/if_ether.h> 70 #ifdef INET 71 #include <netinet/ip_carp.h> 72 #endif 73 74 #include <net/if_arc.h> 75 #include <net/iso88025.h> 76 77 #include <security/mac/mac_framework.h> 78 79 #define SIN(s) ((const struct sockaddr_in *)(s)) 80 #define SDL(s) ((struct sockaddr_dl *)s) 81 82 SYSCTL_DECL(_net_link_ether); 83 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 84 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 85 86 /* timer values */ 87 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 88 * minutes */ 89 static VNET_DEFINE(int, arp_maxtries) = 5; 90 static VNET_DEFINE(int, arp_proxyall) = 0; 91 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 92 * 20 seconds */ 93 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 94 VNET_PCPUSTAT_SYSINIT(arpstat); 95 96 #ifdef VIMAGE 97 VNET_PCPUSTAT_SYSUNINIT(arpstat); 98 #endif /* VIMAGE */ 99 100 static VNET_DEFINE(int, arp_maxhold) = 1; 101 102 #define V_arpt_keep VNET(arpt_keep) 103 #define V_arpt_down VNET(arpt_down) 104 #define V_arp_maxtries VNET(arp_maxtries) 105 #define V_arp_proxyall VNET(arp_proxyall) 106 #define V_arp_maxhold VNET(arp_maxhold) 107 108 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 109 &VNET_NAME(arpt_keep), 0, 110 "ARP entry lifetime in seconds"); 111 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 112 &VNET_NAME(arp_maxtries), 0, 113 "ARP resolution attempts before returning error"); 114 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 115 &VNET_NAME(arp_proxyall), 0, 116 "Enable proxy ARP for all suitable requests"); 117 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 118 &VNET_NAME(arpt_down), 0, 119 "Incomplete ARP entry lifetime in seconds"); 120 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 121 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 122 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 123 &VNET_NAME(arp_maxhold), 0, 124 "Number of packets to hold per ARP entry"); 125 126 static void arp_init(void); 127 static void arpintr(struct mbuf *); 128 static void arptimer(void *); 129 #ifdef INET 130 static void in_arpinput(struct mbuf *); 131 #endif 132 133 static const struct netisr_handler arp_nh = { 134 .nh_name = "arp", 135 .nh_handler = arpintr, 136 .nh_proto = NETISR_ARP, 137 .nh_policy = NETISR_POLICY_SOURCE, 138 }; 139 140 #ifdef AF_INET 141 /* 142 * called by in_scrubprefix() to remove entry from the table when 143 * the interface goes away 144 */ 145 void 146 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 147 { 148 struct sockaddr_in addr4; 149 150 bzero((void *)&addr4, sizeof(addr4)); 151 addr4.sin_len = sizeof(addr4); 152 addr4.sin_family = AF_INET; 153 addr4.sin_addr.s_addr = addr; 154 IF_AFDATA_WLOCK(ifp); 155 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 156 (struct sockaddr *)&addr4); 157 IF_AFDATA_WUNLOCK(ifp); 158 } 159 #endif 160 161 /* 162 * Timeout routine. Age arp_tab entries periodically. 163 */ 164 static void 165 arptimer(void *arg) 166 { 167 struct llentry *lle = (struct llentry *)arg; 168 struct ifnet *ifp; 169 170 if (lle->la_flags & LLE_STATIC) { 171 return; 172 } 173 LLE_WLOCK(lle); 174 if (callout_pending(&lle->la_timer)) { 175 /* 176 * Here we are a bit odd here in the treatment of 177 * active/pending. If the pending bit is set, it got 178 * rescheduled before I ran. The active 179 * bit we ignore, since if it was stopped 180 * in ll_tablefree() and was currently running 181 * it would have return 0 so the code would 182 * not have deleted it since the callout could 183 * not be stopped so we want to go through 184 * with the delete here now. If the callout 185 * was restarted, the pending bit will be back on and 186 * we just want to bail since the callout_reset would 187 * return 1 and our reference would have been removed 188 * by arpresolve() below. 189 */ 190 LLE_WUNLOCK(lle); 191 return; 192 } 193 ifp = lle->lle_tbl->llt_ifp; 194 CURVNET_SET(ifp->if_vnet); 195 196 if ((lle->la_flags & LLE_DELETED) == 0) { 197 int evt; 198 199 if (lle->la_flags & LLE_VALID) 200 evt = LLENTRY_EXPIRED; 201 else 202 evt = LLENTRY_TIMEDOUT; 203 EVENTHANDLER_INVOKE(lle_event, lle, evt); 204 } 205 206 callout_stop(&lle->la_timer); 207 208 /* XXX: LOR avoidance. We still have ref on lle. */ 209 LLE_WUNLOCK(lle); 210 IF_AFDATA_LOCK(ifp); 211 LLE_WLOCK(lle); 212 213 /* Guard against race with other llentry_free(). */ 214 if (lle->la_flags & LLE_LINKED) { 215 size_t pkts_dropped; 216 217 LLE_REMREF(lle); 218 pkts_dropped = llentry_free(lle); 219 ARPSTAT_ADD(dropped, pkts_dropped); 220 } else 221 LLE_FREE_LOCKED(lle); 222 223 IF_AFDATA_UNLOCK(ifp); 224 225 ARPSTAT_INC(timeouts); 226 227 CURVNET_RESTORE(); 228 } 229 230 /* 231 * Broadcast an ARP request. Caller specifies: 232 * - arp header source ip address 233 * - arp header target ip address 234 * - arp header source ethernet address 235 */ 236 void 237 arprequest(struct ifnet *ifp, const struct in_addr *sip, 238 const struct in_addr *tip, u_char *enaddr) 239 { 240 struct mbuf *m; 241 struct arphdr *ah; 242 struct sockaddr sa; 243 u_char *carpaddr = NULL; 244 245 if (sip == NULL) { 246 /* 247 * The caller did not supply a source address, try to find 248 * a compatible one among those assigned to this interface. 249 */ 250 struct ifaddr *ifa; 251 252 IF_ADDR_RLOCK(ifp); 253 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 254 if (ifa->ifa_addr->sa_family != AF_INET) 255 continue; 256 257 if (ifa->ifa_carp) { 258 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 259 continue; 260 sip = &IA_SIN(ifa)->sin_addr; 261 } else { 262 carpaddr = NULL; 263 sip = &IA_SIN(ifa)->sin_addr; 264 } 265 266 if (0 == ((sip->s_addr ^ tip->s_addr) & 267 IA_MASKSIN(ifa)->sin_addr.s_addr)) 268 break; /* found it. */ 269 } 270 IF_ADDR_RUNLOCK(ifp); 271 if (sip == NULL) { 272 printf("%s: cannot find matching address\n", __func__); 273 return; 274 } 275 } 276 if (enaddr == NULL) 277 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 278 279 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 280 return; 281 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 282 2 * ifp->if_addrlen; 283 m->m_pkthdr.len = m->m_len; 284 M_ALIGN(m, m->m_len); 285 ah = mtod(m, struct arphdr *); 286 bzero((caddr_t)ah, m->m_len); 287 #ifdef MAC 288 mac_netinet_arp_send(ifp, m); 289 #endif 290 ah->ar_pro = htons(ETHERTYPE_IP); 291 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 292 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 293 ah->ar_op = htons(ARPOP_REQUEST); 294 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 295 bcopy(sip, ar_spa(ah), ah->ar_pln); 296 bcopy(tip, ar_tpa(ah), ah->ar_pln); 297 sa.sa_family = AF_ARP; 298 sa.sa_len = 2; 299 m->m_flags |= M_BCAST; 300 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 301 (*ifp->if_output)(ifp, m, &sa, NULL); 302 ARPSTAT_INC(txrequests); 303 } 304 305 /* 306 * Resolve an IP address into an ethernet address. 307 * On input: 308 * ifp is the interface we use 309 * is_gw != if @dst represents gateway to some destination 310 * m is the mbuf. May be NULL if we don't have a packet. 311 * dst is the next hop, 312 * desten is where we want the address. 313 * flags returns lle entry flags. 314 * 315 * On success, desten and flags are filled in and the function returns 0; 316 * If the packet must be held pending resolution, we return EWOULDBLOCK 317 * On other errors, we return the corresponding error code. 318 * Note that m_freem() handles NULL. 319 */ 320 int 321 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 322 const struct sockaddr *dst, u_char *desten, uint32_t *pflags) 323 { 324 struct llentry *la = 0; 325 u_int flags = 0; 326 struct mbuf *curr = NULL; 327 struct mbuf *next = NULL; 328 int error, renew; 329 330 if (pflags != NULL) 331 *pflags = 0; 332 333 if (m != NULL) { 334 if (m->m_flags & M_BCAST) { 335 /* broadcast */ 336 (void)memcpy(desten, 337 ifp->if_broadcastaddr, ifp->if_addrlen); 338 return (0); 339 } 340 if (m->m_flags & M_MCAST) { 341 /* multicast */ 342 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 343 return (0); 344 } 345 } 346 retry: 347 IF_AFDATA_RLOCK(ifp); 348 la = lla_lookup(LLTABLE(ifp), flags, dst); 349 IF_AFDATA_RUNLOCK(ifp); 350 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 351 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 352 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 353 IF_AFDATA_WLOCK(ifp); 354 la = lla_lookup(LLTABLE(ifp), flags, dst); 355 IF_AFDATA_WUNLOCK(ifp); 356 } 357 if (la == NULL) { 358 if (flags & LLE_CREATE) 359 log(LOG_DEBUG, 360 "arpresolve: can't allocate llinfo for %s on %s\n", 361 inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname); 362 m_freem(m); 363 return (EINVAL); 364 } 365 366 if ((la->la_flags & LLE_VALID) && 367 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 368 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 369 renew = 0; 370 /* 371 * If entry has an expiry time and it is approaching, 372 * see if we need to send an ARP request within this 373 * arpt_down interval. 374 */ 375 if (!(la->la_flags & LLE_STATIC) && 376 time_uptime + la->la_preempt > la->la_expire) { 377 renew = 1; 378 la->la_preempt--; 379 } 380 381 if (pflags != NULL) 382 *pflags = la->la_flags; 383 384 if (flags & LLE_EXCLUSIVE) 385 LLE_WUNLOCK(la); 386 else 387 LLE_RUNLOCK(la); 388 389 if (renew == 1) 390 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 391 392 return (0); 393 } 394 395 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 396 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 397 inet_ntoa(SIN(dst)->sin_addr)); 398 m_freem(m); 399 error = EINVAL; 400 goto done; 401 } 402 403 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 404 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 405 flags |= LLE_EXCLUSIVE; 406 LLE_RUNLOCK(la); 407 goto retry; 408 } 409 /* 410 * There is an arptab entry, but no ethernet address 411 * response yet. Add the mbuf to the list, dropping 412 * the oldest packet if we have exceeded the system 413 * setting. 414 */ 415 if (m != NULL) { 416 if (la->la_numheld >= V_arp_maxhold) { 417 if (la->la_hold != NULL) { 418 next = la->la_hold->m_nextpkt; 419 m_freem(la->la_hold); 420 la->la_hold = next; 421 la->la_numheld--; 422 ARPSTAT_INC(dropped); 423 } 424 } 425 if (la->la_hold != NULL) { 426 curr = la->la_hold; 427 while (curr->m_nextpkt != NULL) 428 curr = curr->m_nextpkt; 429 curr->m_nextpkt = m; 430 } else 431 la->la_hold = m; 432 la->la_numheld++; 433 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 434 flags &= ~LLE_EXCLUSIVE; 435 LLE_DOWNGRADE(la); 436 } 437 438 } 439 /* 440 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 441 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 442 * if we have already sent arp_maxtries ARP requests. Retransmit the 443 * ARP request, but not faster than one request per second. 444 */ 445 if (la->la_asked < V_arp_maxtries) 446 error = EWOULDBLOCK; /* First request. */ 447 else 448 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 449 450 if (renew) { 451 int canceled; 452 453 LLE_ADDREF(la); 454 la->la_expire = time_uptime; 455 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 456 arptimer, la); 457 if (canceled) 458 LLE_REMREF(la); 459 la->la_asked++; 460 LLE_WUNLOCK(la); 461 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 462 return (error); 463 } 464 done: 465 if (flags & LLE_EXCLUSIVE) 466 LLE_WUNLOCK(la); 467 else 468 LLE_RUNLOCK(la); 469 return (error); 470 } 471 472 /* 473 * Common length and type checks are done here, 474 * then the protocol-specific routine is called. 475 */ 476 static void 477 arpintr(struct mbuf *m) 478 { 479 struct arphdr *ar; 480 481 if (m->m_len < sizeof(struct arphdr) && 482 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 483 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 484 return; 485 } 486 ar = mtod(m, struct arphdr *); 487 488 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 489 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 490 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 491 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 492 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 493 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 494 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 495 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 496 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 497 m_freem(m); 498 return; 499 } 500 501 if (m->m_len < arphdr_len(ar)) { 502 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 503 log(LOG_NOTICE, "arp: runt packet\n"); 504 m_freem(m); 505 return; 506 } 507 ar = mtod(m, struct arphdr *); 508 } 509 510 ARPSTAT_INC(received); 511 switch (ntohs(ar->ar_pro)) { 512 #ifdef INET 513 case ETHERTYPE_IP: 514 in_arpinput(m); 515 return; 516 #endif 517 } 518 m_freem(m); 519 } 520 521 #ifdef INET 522 /* 523 * ARP for Internet protocols on 10 Mb/s Ethernet. 524 * Algorithm is that given in RFC 826. 525 * In addition, a sanity check is performed on the sender 526 * protocol address, to catch impersonators. 527 * We no longer handle negotiations for use of trailer protocol: 528 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 529 * along with IP replies if we wanted trailers sent to us, 530 * and also sent them in response to IP replies. 531 * This allowed either end to announce the desire to receive 532 * trailer packets. 533 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 534 * but formerly didn't normally send requests. 535 */ 536 static int log_arp_wrong_iface = 1; 537 static int log_arp_movements = 1; 538 static int log_arp_permanent_modify = 1; 539 static int allow_multicast = 0; 540 static struct timeval arp_lastlog; 541 static int arp_curpps; 542 static int arp_maxpps = 1; 543 544 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 545 &log_arp_wrong_iface, 0, 546 "log arp packets arriving on the wrong interface"); 547 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 548 &log_arp_movements, 0, 549 "log arp replies from MACs different than the one in the cache"); 550 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 551 &log_arp_permanent_modify, 0, 552 "log arp replies from MACs different than the one in the permanent arp entry"); 553 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 554 &allow_multicast, 0, "accept multicast addresses"); 555 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 556 CTLFLAG_RW, &arp_maxpps, 0, 557 "Maximum number of remotely triggered ARP messages that can be " 558 "logged per second"); 559 560 #define ARP_LOG(pri, ...) do { \ 561 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 562 log((pri), "arp: " __VA_ARGS__); \ 563 } while (0) 564 565 static void 566 in_arpinput(struct mbuf *m) 567 { 568 struct rm_priotracker in_ifa_tracker; 569 struct arphdr *ah; 570 struct ifnet *ifp = m->m_pkthdr.rcvif; 571 struct llentry *la = NULL; 572 struct rtentry *rt; 573 struct ifaddr *ifa; 574 struct in_ifaddr *ia; 575 struct sockaddr sa; 576 struct in_addr isaddr, itaddr, myaddr; 577 u_int8_t *enaddr = NULL; 578 int op, flags; 579 int req_len; 580 int bridged = 0, is_bridge = 0; 581 int carped; 582 struct sockaddr_in sin; 583 sin.sin_len = sizeof(struct sockaddr_in); 584 sin.sin_family = AF_INET; 585 sin.sin_addr.s_addr = 0; 586 587 if (ifp->if_bridge) 588 bridged = 1; 589 if (ifp->if_type == IFT_BRIDGE) 590 is_bridge = 1; 591 592 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 593 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 594 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n"); 595 return; 596 } 597 598 ah = mtod(m, struct arphdr *); 599 /* 600 * ARP is only for IPv4 so we can reject packets with 601 * a protocol length not equal to an IPv4 address. 602 */ 603 if (ah->ar_pln != sizeof(struct in_addr)) { 604 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 605 sizeof(struct in_addr)); 606 goto drop; 607 } 608 609 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 610 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 611 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 612 goto drop; 613 } 614 615 op = ntohs(ah->ar_op); 616 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 617 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 618 619 if (op == ARPOP_REPLY) 620 ARPSTAT_INC(rxreplies); 621 622 /* 623 * For a bridge, we want to check the address irrespective 624 * of the receive interface. (This will change slightly 625 * when we have clusters of interfaces). 626 */ 627 IN_IFADDR_RLOCK(&in_ifa_tracker); 628 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 629 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 630 ia->ia_ifp == ifp) && 631 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 632 (ia->ia_ifa.ifa_carp == NULL || 633 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 634 ifa_ref(&ia->ia_ifa); 635 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 636 goto match; 637 } 638 } 639 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 640 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 641 ia->ia_ifp == ifp) && 642 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 643 ifa_ref(&ia->ia_ifa); 644 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 645 goto match; 646 } 647 648 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 649 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 650 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 651 addr == ia->ia_addr.sin_addr.s_addr) 652 /* 653 * Check the case when bridge shares its MAC address with 654 * some of its children, so packets are claimed by bridge 655 * itself (bridge_input() does it first), but they are really 656 * meant to be destined to the bridge member. 657 */ 658 if (is_bridge) { 659 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 660 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 661 ifa_ref(&ia->ia_ifa); 662 ifp = ia->ia_ifp; 663 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 664 goto match; 665 } 666 } 667 } 668 #undef BDG_MEMBER_MATCHES_ARP 669 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 670 671 /* 672 * No match, use the first inet address on the receive interface 673 * as a dummy address for the rest of the function. 674 */ 675 IF_ADDR_RLOCK(ifp); 676 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 677 if (ifa->ifa_addr->sa_family == AF_INET && 678 (ifa->ifa_carp == NULL || 679 (*carp_iamatch_p)(ifa, &enaddr))) { 680 ia = ifatoia(ifa); 681 ifa_ref(ifa); 682 IF_ADDR_RUNLOCK(ifp); 683 goto match; 684 } 685 IF_ADDR_RUNLOCK(ifp); 686 687 /* 688 * If bridging, fall back to using any inet address. 689 */ 690 IN_IFADDR_RLOCK(&in_ifa_tracker); 691 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 692 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 693 goto drop; 694 } 695 ifa_ref(&ia->ia_ifa); 696 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 697 match: 698 if (!enaddr) 699 enaddr = (u_int8_t *)IF_LLADDR(ifp); 700 carped = (ia->ia_ifa.ifa_carp != NULL); 701 myaddr = ia->ia_addr.sin_addr; 702 ifa_free(&ia->ia_ifa); 703 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 704 goto drop; /* it's from me, ignore it. */ 705 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 706 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 707 "%s!\n", inet_ntoa(isaddr)); 708 goto drop; 709 } 710 /* 711 * Warn if another host is using the same IP address, but only if the 712 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 713 * case we suppress the warning to avoid false positive complaints of 714 * potential misconfiguration. 715 */ 716 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 717 myaddr.s_addr != 0) { 718 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 719 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 720 inet_ntoa(isaddr), ifp->if_xname); 721 itaddr = myaddr; 722 ARPSTAT_INC(dupips); 723 goto reply; 724 } 725 if (ifp->if_flags & IFF_STATICARP) 726 goto reply; 727 728 bzero(&sin, sizeof(sin)); 729 sin.sin_len = sizeof(struct sockaddr_in); 730 sin.sin_family = AF_INET; 731 sin.sin_addr = isaddr; 732 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 733 flags |= LLE_EXCLUSIVE; 734 IF_AFDATA_LOCK(ifp); 735 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 736 IF_AFDATA_UNLOCK(ifp); 737 if (la != NULL) { 738 /* the following is not an error when doing bridging */ 739 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 740 if (log_arp_wrong_iface) 741 ARP_LOG(LOG_WARNING, "%s is on %s " 742 "but got reply from %*D on %s\n", 743 inet_ntoa(isaddr), 744 la->lle_tbl->llt_ifp->if_xname, 745 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 746 ifp->if_xname); 747 LLE_WUNLOCK(la); 748 goto reply; 749 } 750 if ((la->la_flags & LLE_VALID) && 751 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 752 if (la->la_flags & LLE_STATIC) { 753 LLE_WUNLOCK(la); 754 if (log_arp_permanent_modify) 755 ARP_LOG(LOG_ERR, 756 "%*D attempts to modify " 757 "permanent entry for %s on %s\n", 758 ifp->if_addrlen, 759 (u_char *)ar_sha(ah), ":", 760 inet_ntoa(isaddr), ifp->if_xname); 761 goto reply; 762 } 763 if (log_arp_movements) { 764 ARP_LOG(LOG_INFO, "%s moved from %*D " 765 "to %*D on %s\n", 766 inet_ntoa(isaddr), 767 ifp->if_addrlen, 768 (u_char *)&la->ll_addr, ":", 769 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 770 ifp->if_xname); 771 } 772 } 773 774 if (ifp->if_addrlen != ah->ar_hln) { 775 LLE_WUNLOCK(la); 776 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 777 "i/f %d (ignored)\n", ifp->if_addrlen, 778 (u_char *) ar_sha(ah), ":", ah->ar_hln, 779 ifp->if_addrlen); 780 goto drop; 781 } 782 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 783 la->la_flags |= LLE_VALID; 784 785 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 786 787 if (!(la->la_flags & LLE_STATIC)) { 788 int canceled; 789 790 LLE_ADDREF(la); 791 la->la_expire = time_uptime + V_arpt_keep; 792 canceled = callout_reset(&la->la_timer, 793 hz * V_arpt_keep, arptimer, la); 794 if (canceled) 795 LLE_REMREF(la); 796 } 797 la->la_asked = 0; 798 la->la_preempt = V_arp_maxtries; 799 /* 800 * The packets are all freed within the call to the output 801 * routine. 802 * 803 * NB: The lock MUST be released before the call to the 804 * output routine. 805 */ 806 if (la->la_hold != NULL) { 807 struct mbuf *m_hold, *m_hold_next; 808 809 m_hold = la->la_hold; 810 la->la_hold = NULL; 811 la->la_numheld = 0; 812 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 813 LLE_WUNLOCK(la); 814 for (; m_hold != NULL; m_hold = m_hold_next) { 815 m_hold_next = m_hold->m_nextpkt; 816 m_hold->m_nextpkt = NULL; 817 /* Avoid confusing lower layers. */ 818 m_clrprotoflags(m_hold); 819 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 820 } 821 } else 822 LLE_WUNLOCK(la); 823 } 824 reply: 825 if (op != ARPOP_REQUEST) 826 goto drop; 827 ARPSTAT_INC(rxrequests); 828 829 if (itaddr.s_addr == myaddr.s_addr) { 830 /* Shortcut.. the receiving interface is the target. */ 831 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 832 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 833 } else { 834 struct llentry *lle = NULL; 835 836 sin.sin_addr = itaddr; 837 IF_AFDATA_RLOCK(ifp); 838 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 839 IF_AFDATA_RUNLOCK(ifp); 840 841 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 842 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 843 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 844 LLE_RUNLOCK(lle); 845 } else { 846 847 if (lle != NULL) 848 LLE_RUNLOCK(lle); 849 850 if (!V_arp_proxyall) 851 goto drop; 852 853 sin.sin_addr = itaddr; 854 /* XXX MRT use table 0 for arp reply */ 855 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 856 if (!rt) 857 goto drop; 858 859 /* 860 * Don't send proxies for nodes on the same interface 861 * as this one came out of, or we'll get into a fight 862 * over who claims what Ether address. 863 */ 864 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 865 RTFREE_LOCKED(rt); 866 goto drop; 867 } 868 RTFREE_LOCKED(rt); 869 870 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 871 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 872 873 /* 874 * Also check that the node which sent the ARP packet 875 * is on the interface we expect it to be on. This 876 * avoids ARP chaos if an interface is connected to the 877 * wrong network. 878 */ 879 sin.sin_addr = isaddr; 880 881 /* XXX MRT use table 0 for arp checks */ 882 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 883 if (!rt) 884 goto drop; 885 if (rt->rt_ifp != ifp) { 886 ARP_LOG(LOG_INFO, "proxy: ignoring request" 887 " from %s via %s, expecting %s\n", 888 inet_ntoa(isaddr), ifp->if_xname, 889 rt->rt_ifp->if_xname); 890 RTFREE_LOCKED(rt); 891 goto drop; 892 } 893 RTFREE_LOCKED(rt); 894 895 #ifdef DEBUG_PROXY 896 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 897 #endif 898 } 899 } 900 901 if (itaddr.s_addr == myaddr.s_addr && 902 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 903 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 904 #ifdef DEBUG_LINKLOCAL 905 printf("arp: sending reply for link-local addr %s\n", 906 inet_ntoa(itaddr)); 907 #endif 908 m->m_flags |= M_BCAST; 909 m->m_flags &= ~M_MCAST; 910 } else { 911 /* default behaviour; never reply by broadcast. */ 912 m->m_flags &= ~(M_BCAST|M_MCAST); 913 } 914 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 915 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 916 ah->ar_op = htons(ARPOP_REPLY); 917 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 918 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 919 m->m_pkthdr.len = m->m_len; 920 m->m_pkthdr.rcvif = NULL; 921 sa.sa_family = AF_ARP; 922 sa.sa_len = 2; 923 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 924 (*ifp->if_output)(ifp, m, &sa, NULL); 925 ARPSTAT_INC(txreplies); 926 return; 927 928 drop: 929 m_freem(m); 930 } 931 #endif 932 933 void 934 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 935 { 936 struct llentry *lle; 937 938 if (ifa->ifa_carp != NULL) 939 return; 940 941 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 942 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 943 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 944 /* 945 * interface address is considered static entry 946 * because the output of the arp utility shows 947 * that L2 entry as permanent 948 */ 949 IF_AFDATA_LOCK(ifp); 950 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 951 (struct sockaddr *)IA_SIN(ifa)); 952 IF_AFDATA_UNLOCK(ifp); 953 if (lle == NULL) 954 log(LOG_INFO, "arp_ifinit: cannot create arp " 955 "entry for interface address\n"); 956 else 957 LLE_RUNLOCK(lle); 958 } 959 ifa->ifa_rtrequest = NULL; 960 } 961 962 void 963 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 964 { 965 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 966 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 967 &IA_SIN(ifa)->sin_addr, enaddr); 968 ifa->ifa_rtrequest = NULL; 969 } 970 971 static void 972 arp_init(void) 973 { 974 975 netisr_register(&arp_nh); 976 } 977 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 978