Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/if_ether.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 30 */ 31 32 /* 33 * Ethernet address resolution protocol. 34 * TODO: 35 * add "inuse/lock" bit (or ref. count) along with valid bit 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_inet.h" 42 43 #include <sys/param.h> 44 #include <sys/kernel.h> 45 #include <sys/queue.h> 46 #include <sys/sysctl.h> 47 #include <sys/systm.h> 48 #include <sys/mbuf.h> 49 #include <sys/malloc.h> 50 #include <sys/proc.h> 51 #include <sys/socket.h> 52 #include <sys/syslog.h> 53 54 #include <net/if.h> 55 #include <net/if_dl.h> 56 #include <net/if_types.h> 57 #include <net/netisr.h> 58 #include <net/if_llc.h> 59 #include <net/ethernet.h> 60 #include <net/route.h> 61 #include <net/vnet.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_var.h> 65 #include <net/if_llatbl.h> 66 #include <netinet/if_ether.h> 67 #if defined(INET) 68 #include <netinet/ip_carp.h> 69 #endif 70 71 #include <net/if_arc.h> 72 #include <net/iso88025.h> 73 74 #include <security/mac/mac_framework.h> 75 76 #define SIN(s) ((struct sockaddr_in *)s) 77 #define SDL(s) ((struct sockaddr_dl *)s) 78 79 SYSCTL_DECL(_net_link_ether); 80 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 81 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 82 83 /* timer values */ 84 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 85 * minutes */ 86 static VNET_DEFINE(int, arp_maxtries) = 5; 87 VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for 88 * local traffic */ 89 static VNET_DEFINE(int, arp_proxyall) = 0; 90 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 91 * 20 seconds */ 92 VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 93 94 static VNET_DEFINE(int, arp_maxhold) = 1; 95 96 #define V_arpt_keep VNET(arpt_keep) 97 #define V_arpt_down VNET(arpt_down) 98 #define V_arp_maxtries VNET(arp_maxtries) 99 #define V_arp_proxyall VNET(arp_proxyall) 100 #define V_arpstat VNET(arpstat) 101 #define V_arp_maxhold VNET(arp_maxhold) 102 103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 104 &VNET_NAME(arpt_keep), 0, 105 "ARP entry lifetime in seconds"); 106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 107 &VNET_NAME(arp_maxtries), 0, 108 "ARP resolution attempts before returning error"); 109 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 110 &VNET_NAME(useloopback), 0, 111 "Use the loopback interface for local traffic"); 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_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW, 119 &VNET_NAME(arpstat), arpstat, 120 "ARP statistics (struct arpstat, net/if_arp.h)"); 121 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW, 122 &VNET_NAME(arp_maxhold), 0, 123 "Number of packets to hold per ARP entry"); 124 125 static void arp_init(void); 126 void arprequest(struct ifnet *, 127 struct in_addr *, struct in_addr *, u_char *); 128 static void arpintr(struct mbuf *); 129 static void arptimer(void *); 130 #ifdef INET 131 static void in_arpinput(struct mbuf *); 132 #endif 133 134 static const struct netisr_handler arp_nh = { 135 .nh_name = "arp", 136 .nh_handler = arpintr, 137 .nh_proto = NETISR_ARP, 138 .nh_policy = NETISR_POLICY_SOURCE, 139 }; 140 141 #ifdef AF_INET 142 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 143 144 /* 145 * called by in_ifscrub to remove entry from the table when 146 * the interface goes away 147 */ 148 void 149 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 150 { 151 struct sockaddr_in addr4; 152 153 bzero((void *)&addr4, sizeof(addr4)); 154 addr4.sin_len = sizeof(addr4); 155 addr4.sin_family = AF_INET; 156 addr4.sin_addr.s_addr = addr; 157 IF_AFDATA_WLOCK(ifp); 158 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 159 (struct sockaddr *)&addr4); 160 IF_AFDATA_WUNLOCK(ifp); 161 } 162 #endif 163 164 /* 165 * Timeout routine. Age arp_tab entries periodically. 166 */ 167 static void 168 arptimer(void *arg) 169 { 170 struct llentry *lle = (struct llentry *)arg; 171 struct ifnet *ifp; 172 173 if (lle->la_flags & LLE_STATIC) { 174 LLE_WUNLOCK(lle); 175 return; 176 } 177 178 ifp = lle->lle_tbl->llt_ifp; 179 CURVNET_SET(ifp->if_vnet); 180 181 if ((lle->la_flags & LLE_DELETED) == 0) { 182 int evt; 183 184 if (lle->la_flags & LLE_VALID) 185 evt = LLENTRY_EXPIRED; 186 else 187 evt = LLENTRY_TIMEDOUT; 188 EVENTHANDLER_INVOKE(lle_event, lle, evt); 189 } 190 191 callout_stop(&lle->la_timer); 192 193 /* XXX: LOR avoidance. We still have ref on lle. */ 194 LLE_WUNLOCK(lle); 195 IF_AFDATA_LOCK(ifp); 196 LLE_WLOCK(lle); 197 198 /* Guard against race with other llentry_free(). */ 199 if (lle->la_flags & LLE_LINKED) { 200 size_t pkts_dropped; 201 202 LLE_REMREF(lle); 203 pkts_dropped = llentry_free(lle); 204 ARPSTAT_ADD(dropped, pkts_dropped); 205 } else 206 LLE_FREE_LOCKED(lle); 207 208 IF_AFDATA_UNLOCK(ifp); 209 210 ARPSTAT_INC(timeouts); 211 212 CURVNET_RESTORE(); 213 } 214 215 /* 216 * Broadcast an ARP request. Caller specifies: 217 * - arp header source ip address 218 * - arp header target ip address 219 * - arp header source ethernet address 220 */ 221 void 222 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 223 u_char *enaddr) 224 { 225 struct mbuf *m; 226 struct arphdr *ah; 227 struct sockaddr sa; 228 229 if (sip == NULL) { 230 /* XXX don't believe this can happen (or explain why) */ 231 /* 232 * The caller did not supply a source address, try to find 233 * a compatible one among those assigned to this interface. 234 */ 235 struct ifaddr *ifa; 236 237 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 238 if (!ifa->ifa_addr || 239 ifa->ifa_addr->sa_family != AF_INET) 240 continue; 241 sip = &SIN(ifa->ifa_addr)->sin_addr; 242 if (0 == ((sip->s_addr ^ tip->s_addr) & 243 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 244 break; /* found it. */ 245 } 246 if (sip == NULL) { 247 printf("%s: cannot find matching address\n", __func__); 248 return; 249 } 250 } 251 252 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 253 return; 254 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 255 2*ifp->if_data.ifi_addrlen; 256 m->m_pkthdr.len = m->m_len; 257 MH_ALIGN(m, m->m_len); 258 ah = mtod(m, struct arphdr *); 259 bzero((caddr_t)ah, m->m_len); 260 #ifdef MAC 261 mac_netinet_arp_send(ifp, m); 262 #endif 263 ah->ar_pro = htons(ETHERTYPE_IP); 264 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 265 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 266 ah->ar_op = htons(ARPOP_REQUEST); 267 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 268 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 269 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 270 sa.sa_family = AF_ARP; 271 sa.sa_len = 2; 272 m->m_flags |= M_BCAST; 273 (*ifp->if_output)(ifp, m, &sa, NULL); 274 ARPSTAT_INC(txrequests); 275 } 276 277 /* 278 * Resolve an IP address into an ethernet address. 279 * On input: 280 * ifp is the interface we use 281 * rt0 is the route to the final destination (possibly useless) 282 * m is the mbuf. May be NULL if we don't have a packet. 283 * dst is the next hop, 284 * desten is where we want the address. 285 * 286 * On success, desten is filled in and the function returns 0; 287 * If the packet must be held pending resolution, we return EWOULDBLOCK 288 * On other errors, we return the corresponding error code. 289 * Note that m_freem() handles NULL. 290 */ 291 int 292 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 293 struct sockaddr *dst, u_char *desten, struct llentry **lle) 294 { 295 struct llentry *la = 0; 296 u_int flags = 0; 297 struct mbuf *curr = NULL; 298 struct mbuf *next = NULL; 299 int error, renew; 300 301 *lle = NULL; 302 if (m != NULL) { 303 if (m->m_flags & M_BCAST) { 304 /* broadcast */ 305 (void)memcpy(desten, 306 ifp->if_broadcastaddr, ifp->if_addrlen); 307 return (0); 308 } 309 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 310 /* multicast */ 311 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 312 return (0); 313 } 314 } 315 retry: 316 IF_AFDATA_RLOCK(ifp); 317 la = lla_lookup(LLTABLE(ifp), flags, dst); 318 IF_AFDATA_RUNLOCK(ifp); 319 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 320 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 321 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 322 IF_AFDATA_WLOCK(ifp); 323 la = lla_lookup(LLTABLE(ifp), flags, dst); 324 IF_AFDATA_WUNLOCK(ifp); 325 } 326 if (la == NULL) { 327 if (flags & LLE_CREATE) 328 log(LOG_DEBUG, 329 "arpresolve: can't allocate llinfo for %s on %s\n", 330 inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname); 331 m_freem(m); 332 return (EINVAL); 333 } 334 335 if ((la->la_flags & LLE_VALID) && 336 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 337 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 338 /* 339 * If entry has an expiry time and it is approaching, 340 * see if we need to send an ARP request within this 341 * arpt_down interval. 342 */ 343 if (!(la->la_flags & LLE_STATIC) && 344 time_uptime + la->la_preempt > la->la_expire) { 345 arprequest(ifp, NULL, 346 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 347 348 la->la_preempt--; 349 } 350 351 *lle = la; 352 error = 0; 353 goto done; 354 } 355 356 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 357 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 358 inet_ntoa(SIN(dst)->sin_addr)); 359 m_freem(m); 360 error = EINVAL; 361 goto done; 362 } 363 364 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 365 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 366 flags |= LLE_EXCLUSIVE; 367 LLE_RUNLOCK(la); 368 goto retry; 369 } 370 /* 371 * There is an arptab entry, but no ethernet address 372 * response yet. Add the mbuf to the list, dropping 373 * the oldest packet if we have exceeded the system 374 * setting. 375 */ 376 if (m != NULL) { 377 if (la->la_numheld >= V_arp_maxhold) { 378 if (la->la_hold != NULL) { 379 next = la->la_hold->m_nextpkt; 380 m_freem(la->la_hold); 381 la->la_hold = next; 382 la->la_numheld--; 383 ARPSTAT_INC(dropped); 384 } 385 } 386 if (la->la_hold != NULL) { 387 curr = la->la_hold; 388 while (curr->m_nextpkt != NULL) 389 curr = curr->m_nextpkt; 390 curr->m_nextpkt = m; 391 } else 392 la->la_hold = m; 393 la->la_numheld++; 394 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 395 flags &= ~LLE_EXCLUSIVE; 396 LLE_DOWNGRADE(la); 397 } 398 399 } 400 /* 401 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 402 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 403 * if we have already sent arp_maxtries ARP requests. Retransmit the 404 * ARP request, but not faster than one request per second. 405 */ 406 if (la->la_asked < V_arp_maxtries) 407 error = EWOULDBLOCK; /* First request. */ 408 else 409 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 410 EHOSTUNREACH : EHOSTDOWN; 411 412 if (renew) { 413 int canceled; 414 415 LLE_ADDREF(la); 416 la->la_expire = time_uptime; 417 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 418 arptimer, la); 419 if (canceled) 420 LLE_REMREF(la); 421 la->la_asked++; 422 LLE_WUNLOCK(la); 423 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 424 IF_LLADDR(ifp)); 425 return (error); 426 } 427 done: 428 if (flags & LLE_EXCLUSIVE) 429 LLE_WUNLOCK(la); 430 else 431 LLE_RUNLOCK(la); 432 return (error); 433 } 434 435 /* 436 * Common length and type checks are done here, 437 * then the protocol-specific routine is called. 438 */ 439 static void 440 arpintr(struct mbuf *m) 441 { 442 struct arphdr *ar; 443 444 if (m->m_len < sizeof(struct arphdr) && 445 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 446 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 447 return; 448 } 449 ar = mtod(m, struct arphdr *); 450 451 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 452 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 453 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 454 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 455 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 456 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 457 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 458 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 459 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 460 m_freem(m); 461 return; 462 } 463 464 if (m->m_len < arphdr_len(ar)) { 465 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 466 log(LOG_NOTICE, "arp: runt packet\n"); 467 m_freem(m); 468 return; 469 } 470 ar = mtod(m, struct arphdr *); 471 } 472 473 ARPSTAT_INC(received); 474 switch (ntohs(ar->ar_pro)) { 475 #ifdef INET 476 case ETHERTYPE_IP: 477 in_arpinput(m); 478 return; 479 #endif 480 } 481 m_freem(m); 482 } 483 484 #ifdef INET 485 /* 486 * ARP for Internet protocols on 10 Mb/s Ethernet. 487 * Algorithm is that given in RFC 826. 488 * In addition, a sanity check is performed on the sender 489 * protocol address, to catch impersonators. 490 * We no longer handle negotiations for use of trailer protocol: 491 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 492 * along with IP replies if we wanted trailers sent to us, 493 * and also sent them in response to IP replies. 494 * This allowed either end to announce the desire to receive 495 * trailer packets. 496 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 497 * but formerly didn't normally send requests. 498 */ 499 static int log_arp_wrong_iface = 1; 500 static int log_arp_movements = 1; 501 static int log_arp_permanent_modify = 1; 502 static int allow_multicast = 0; 503 504 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 505 &log_arp_wrong_iface, 0, 506 "log arp packets arriving on the wrong interface"); 507 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 508 &log_arp_movements, 0, 509 "log arp replies from MACs different than the one in the cache"); 510 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 511 &log_arp_permanent_modify, 0, 512 "log arp replies from MACs different than the one in the permanent arp entry"); 513 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 514 &allow_multicast, 0, "accept multicast addresses"); 515 516 static void 517 in_arpinput(struct mbuf *m) 518 { 519 struct arphdr *ah; 520 struct ifnet *ifp = m->m_pkthdr.rcvif; 521 struct llentry *la = NULL; 522 struct rtentry *rt; 523 struct ifaddr *ifa; 524 struct in_ifaddr *ia; 525 struct sockaddr sa; 526 struct in_addr isaddr, itaddr, myaddr; 527 u_int8_t *enaddr = NULL; 528 int op, flags; 529 int req_len; 530 int bridged = 0, is_bridge = 0; 531 int carp_match = 0; 532 struct sockaddr_in sin; 533 sin.sin_len = sizeof(struct sockaddr_in); 534 sin.sin_family = AF_INET; 535 sin.sin_addr.s_addr = 0; 536 537 if (ifp->if_bridge) 538 bridged = 1; 539 if (ifp->if_type == IFT_BRIDGE) 540 is_bridge = 1; 541 542 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 543 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 544 log(LOG_NOTICE, "in_arp: runt packet -- m_pullup failed\n"); 545 return; 546 } 547 548 ah = mtod(m, struct arphdr *); 549 /* 550 * ARP is only for IPv4 so we can reject packets with 551 * a protocol length not equal to an IPv4 address. 552 */ 553 if (ah->ar_pln != sizeof(struct in_addr)) { 554 log(LOG_NOTICE, "in_arp: requested protocol length != %zu\n", 555 sizeof(struct in_addr)); 556 goto drop; 557 } 558 559 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 560 log(LOG_NOTICE, "arp: %*D is multicast\n", 561 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 562 goto drop; 563 } 564 565 op = ntohs(ah->ar_op); 566 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 567 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 568 569 if (op == ARPOP_REPLY) 570 ARPSTAT_INC(rxreplies); 571 572 /* 573 * For a bridge, we want to check the address irrespective 574 * of the receive interface. (This will change slightly 575 * when we have clusters of interfaces). 576 * If the interface does not match, but the recieving interface 577 * is part of carp, we call carp_iamatch to see if this is a 578 * request for the virtual host ip. 579 * XXX: This is really ugly! 580 */ 581 IN_IFADDR_RLOCK(); 582 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 583 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 584 ia->ia_ifp == ifp) && 585 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 586 ifa_ref(&ia->ia_ifa); 587 IN_IFADDR_RUNLOCK(); 588 goto match; 589 } 590 if (ifp->if_carp != NULL && 591 (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) && 592 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 593 carp_match = 1; 594 ifa_ref(&ia->ia_ifa); 595 IN_IFADDR_RUNLOCK(); 596 goto match; 597 } 598 } 599 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 600 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 601 ia->ia_ifp == ifp) && 602 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 603 ifa_ref(&ia->ia_ifa); 604 IN_IFADDR_RUNLOCK(); 605 goto match; 606 } 607 608 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 609 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 610 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 611 addr == ia->ia_addr.sin_addr.s_addr) 612 /* 613 * Check the case when bridge shares its MAC address with 614 * some of its children, so packets are claimed by bridge 615 * itself (bridge_input() does it first), but they are really 616 * meant to be destined to the bridge member. 617 */ 618 if (is_bridge) { 619 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 620 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 621 ifa_ref(&ia->ia_ifa); 622 ifp = ia->ia_ifp; 623 IN_IFADDR_RUNLOCK(); 624 goto match; 625 } 626 } 627 } 628 #undef BDG_MEMBER_MATCHES_ARP 629 IN_IFADDR_RUNLOCK(); 630 631 /* 632 * No match, use the first inet address on the receive interface 633 * as a dummy address for the rest of the function. 634 */ 635 IF_ADDR_RLOCK(ifp); 636 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 637 if (ifa->ifa_addr->sa_family == AF_INET) { 638 ia = ifatoia(ifa); 639 ifa_ref(ifa); 640 IF_ADDR_RUNLOCK(ifp); 641 goto match; 642 } 643 IF_ADDR_RUNLOCK(ifp); 644 645 /* 646 * If bridging, fall back to using any inet address. 647 */ 648 IN_IFADDR_RLOCK(); 649 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 650 IN_IFADDR_RUNLOCK(); 651 goto drop; 652 } 653 ifa_ref(&ia->ia_ifa); 654 IN_IFADDR_RUNLOCK(); 655 match: 656 if (!enaddr) 657 enaddr = (u_int8_t *)IF_LLADDR(ifp); 658 myaddr = ia->ia_addr.sin_addr; 659 ifa_free(&ia->ia_ifa); 660 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 661 goto drop; /* it's from me, ignore it. */ 662 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 663 log(LOG_NOTICE, 664 "arp: link address is broadcast for IP address %s!\n", 665 inet_ntoa(isaddr)); 666 goto drop; 667 } 668 /* 669 * Warn if another host is using the same IP address, but only if the 670 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 671 * case we suppress the warning to avoid false positive complaints of 672 * potential misconfiguration. 673 */ 674 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 675 log(LOG_ERR, 676 "arp: %*D is using my IP address %s on %s!\n", 677 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 678 inet_ntoa(isaddr), ifp->if_xname); 679 itaddr = myaddr; 680 ARPSTAT_INC(dupips); 681 goto reply; 682 } 683 if (ifp->if_flags & IFF_STATICARP) 684 goto reply; 685 686 bzero(&sin, sizeof(sin)); 687 sin.sin_len = sizeof(struct sockaddr_in); 688 sin.sin_family = AF_INET; 689 sin.sin_addr = isaddr; 690 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 691 flags |= LLE_EXCLUSIVE; 692 IF_AFDATA_LOCK(ifp); 693 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 694 IF_AFDATA_UNLOCK(ifp); 695 if (la != NULL) { 696 /* the following is not an error when doing bridging */ 697 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) { 698 if (log_arp_wrong_iface) 699 log(LOG_WARNING, "arp: %s is on %s " 700 "but got reply from %*D on %s\n", 701 inet_ntoa(isaddr), 702 la->lle_tbl->llt_ifp->if_xname, 703 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 704 ifp->if_xname); 705 LLE_WUNLOCK(la); 706 goto reply; 707 } 708 if ((la->la_flags & LLE_VALID) && 709 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 710 if (la->la_flags & LLE_STATIC) { 711 LLE_WUNLOCK(la); 712 if (log_arp_permanent_modify) 713 log(LOG_ERR, 714 "arp: %*D attempts to modify " 715 "permanent entry for %s on %s\n", 716 ifp->if_addrlen, 717 (u_char *)ar_sha(ah), ":", 718 inet_ntoa(isaddr), ifp->if_xname); 719 goto reply; 720 } 721 if (log_arp_movements) { 722 log(LOG_INFO, "arp: %s moved from %*D " 723 "to %*D on %s\n", 724 inet_ntoa(isaddr), 725 ifp->if_addrlen, 726 (u_char *)&la->ll_addr, ":", 727 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 728 ifp->if_xname); 729 } 730 } 731 732 if (ifp->if_addrlen != ah->ar_hln) { 733 LLE_WUNLOCK(la); 734 log(LOG_WARNING, "arp from %*D: addr len: new %d, " 735 "i/f %d (ignored)\n", ifp->if_addrlen, 736 (u_char *) ar_sha(ah), ":", ah->ar_hln, 737 ifp->if_addrlen); 738 goto drop; 739 } 740 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 741 la->la_flags |= LLE_VALID; 742 743 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 744 745 if (!(la->la_flags & LLE_STATIC)) { 746 int canceled; 747 748 LLE_ADDREF(la); 749 la->la_expire = time_uptime + V_arpt_keep; 750 canceled = callout_reset(&la->la_timer, 751 hz * V_arpt_keep, arptimer, la); 752 if (canceled) 753 LLE_REMREF(la); 754 } 755 la->la_asked = 0; 756 la->la_preempt = V_arp_maxtries; 757 /* 758 * The packets are all freed within the call to the output 759 * routine. 760 * 761 * NB: The lock MUST be released before the call to the 762 * output routine. 763 */ 764 if (la->la_hold != NULL) { 765 struct mbuf *m_hold, *m_hold_next; 766 767 m_hold = la->la_hold; 768 la->la_hold = NULL; 769 la->la_numheld = 0; 770 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 771 LLE_WUNLOCK(la); 772 for (; m_hold != NULL; m_hold = m_hold_next) { 773 m_hold_next = m_hold->m_nextpkt; 774 m_hold->m_nextpkt = NULL; 775 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 776 } 777 } else 778 LLE_WUNLOCK(la); 779 } 780 reply: 781 if (op != ARPOP_REQUEST) 782 goto drop; 783 ARPSTAT_INC(rxrequests); 784 785 if (itaddr.s_addr == myaddr.s_addr) { 786 /* Shortcut.. the receiving interface is the target. */ 787 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 788 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 789 } else { 790 struct llentry *lle = NULL; 791 792 sin.sin_addr = itaddr; 793 IF_AFDATA_RLOCK(ifp); 794 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 795 IF_AFDATA_RUNLOCK(ifp); 796 797 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 798 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 799 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 800 LLE_RUNLOCK(lle); 801 } else { 802 803 if (lle != NULL) 804 LLE_RUNLOCK(lle); 805 806 if (!V_arp_proxyall) 807 goto drop; 808 809 sin.sin_addr = itaddr; 810 /* XXX MRT use table 0 for arp reply */ 811 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 812 if (!rt) 813 goto drop; 814 815 /* 816 * Don't send proxies for nodes on the same interface 817 * as this one came out of, or we'll get into a fight 818 * over who claims what Ether address. 819 */ 820 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 821 RTFREE_LOCKED(rt); 822 goto drop; 823 } 824 RTFREE_LOCKED(rt); 825 826 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 827 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 828 829 /* 830 * Also check that the node which sent the ARP packet 831 * is on the interface we expect it to be on. This 832 * avoids ARP chaos if an interface is connected to the 833 * wrong network. 834 */ 835 sin.sin_addr = isaddr; 836 837 /* XXX MRT use table 0 for arp checks */ 838 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 839 if (!rt) 840 goto drop; 841 if (rt->rt_ifp != ifp) { 842 log(LOG_INFO, "arp_proxy: ignoring request" 843 " from %s via %s, expecting %s\n", 844 inet_ntoa(isaddr), ifp->if_xname, 845 rt->rt_ifp->if_xname); 846 RTFREE_LOCKED(rt); 847 goto drop; 848 } 849 RTFREE_LOCKED(rt); 850 851 #ifdef DEBUG_PROXY 852 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 853 #endif 854 } 855 } 856 857 if (itaddr.s_addr == myaddr.s_addr && 858 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 859 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 860 #ifdef DEBUG_LINKLOCAL 861 printf("arp: sending reply for link-local addr %s\n", 862 inet_ntoa(itaddr)); 863 #endif 864 m->m_flags |= M_BCAST; 865 m->m_flags &= ~M_MCAST; 866 } else { 867 /* default behaviour; never reply by broadcast. */ 868 m->m_flags &= ~(M_BCAST|M_MCAST); 869 } 870 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 871 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 872 ah->ar_op = htons(ARPOP_REPLY); 873 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 874 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 875 m->m_pkthdr.len = m->m_len; 876 m->m_pkthdr.rcvif = NULL; 877 sa.sa_family = AF_ARP; 878 sa.sa_len = 2; 879 (*ifp->if_output)(ifp, m, &sa, NULL); 880 ARPSTAT_INC(txreplies); 881 return; 882 883 drop: 884 m_freem(m); 885 } 886 #endif 887 888 void 889 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 890 { 891 struct llentry *lle; 892 893 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 894 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 895 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 896 /* 897 * interface address is considered static entry 898 * because the output of the arp utility shows 899 * that L2 entry as permanent 900 */ 901 IF_AFDATA_LOCK(ifp); 902 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 903 (struct sockaddr *)IA_SIN(ifa)); 904 IF_AFDATA_UNLOCK(ifp); 905 if (lle == NULL) 906 log(LOG_INFO, "arp_ifinit: cannot create arp " 907 "entry for interface address\n"); 908 else 909 LLE_RUNLOCK(lle); 910 } 911 ifa->ifa_rtrequest = NULL; 912 } 913 914 void 915 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 916 { 917 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 918 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 919 &IA_SIN(ifa)->sin_addr, enaddr); 920 ifa->ifa_rtrequest = NULL; 921 } 922 923 static void 924 arp_init(void) 925 { 926 927 netisr_register(&arp_nh); 928 } 929 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
Cache object: 5c1e4a66238604e8434e5cf87c35f97b
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