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