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