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 #include "opt_mac.h" 43 #include "opt_carp.h" 44 45 #include <sys/param.h> 46 #include <sys/kernel.h> 47 #include <sys/queue.h> 48 #include <sys/sysctl.h> 49 #include <sys/systm.h> 50 #include <sys/mbuf.h> 51 #include <sys/malloc.h> 52 #include <sys/proc.h> 53 #include <sys/socket.h> 54 #include <sys/syslog.h> 55 #include <sys/vimage.h> 56 57 #include <net/if.h> 58 #include <net/if_dl.h> 59 #include <net/if_types.h> 60 #include <net/route.h> 61 #include <net/netisr.h> 62 #include <net/if_llc.h> 63 #include <net/ethernet.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 #include <netinet/vinet.h> 71 72 #include <net/if_arc.h> 73 #include <net/iso88025.h> 74 75 #ifdef DEV_CARP 76 #include <netinet/ip_carp.h> 77 #endif 78 79 #include <security/mac/mac_framework.h> 80 81 #define SIN(s) ((struct sockaddr_in *)s) 82 #define SDL(s) ((struct sockaddr_dl *)s) 83 #define LLTABLE(ifp) ((struct lltable *)(ifp)->if_afdata[AF_INET]) 84 85 SYSCTL_DECL(_net_link_ether); 86 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 87 88 /* timer values */ 89 #ifdef VIMAGE_GLOBALS 90 static int arpt_keep; /* once resolved, good for 20 more minutes */ 91 static int arp_maxtries; 92 int useloopback; /* use loopback interface for local traffic */ 93 static int arp_proxyall; 94 #endif 95 96 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, max_age, 97 CTLFLAG_RW, arpt_keep, 0, "ARP entry lifetime in seconds"); 98 99 static struct ifqueue arpintrq; 100 101 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, maxtries, 102 CTLFLAG_RW, arp_maxtries, 0, 103 "ARP resolution attempts before returning error"); 104 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, useloopback, 105 CTLFLAG_RW, useloopback, 0, 106 "Use the loopback interface for local traffic"); 107 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, proxyall, 108 CTLFLAG_RW, arp_proxyall, 0, 109 "Enable proxy ARP for all suitable requests"); 110 111 static void arp_init(void); 112 void arprequest(struct ifnet *, 113 struct in_addr *, struct in_addr *, u_char *); 114 static void arpintr(struct mbuf *); 115 static void arptimer(void *); 116 #ifdef INET 117 static void in_arpinput(struct mbuf *); 118 #endif 119 120 #ifdef AF_INET 121 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 122 123 /* 124 * called by in_ifscrub to remove entry from the table when 125 * the interface goes away 126 */ 127 void 128 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 129 { 130 struct sockaddr_in addr4; 131 132 bzero((void *)&addr4, sizeof(addr4)); 133 addr4.sin_len = sizeof(addr4); 134 addr4.sin_family = AF_INET; 135 addr4.sin_addr.s_addr = addr; 136 IF_AFDATA_LOCK(ifp); 137 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 138 (struct sockaddr *)&addr4); 139 IF_AFDATA_UNLOCK(ifp); 140 } 141 #endif 142 143 /* 144 * Timeout routine. Age arp_tab entries periodically. 145 */ 146 static void 147 arptimer(void *arg) 148 { 149 struct ifnet *ifp; 150 struct llentry *lle = (struct llentry *)arg; 151 152 if (lle == NULL) { 153 panic("%s: NULL entry!\n", __func__); 154 return; 155 } 156 ifp = lle->lle_tbl->llt_ifp; 157 IF_AFDATA_LOCK(ifp); 158 LLE_WLOCK(lle); 159 if ((lle->la_flags & LLE_DELETED) || 160 (time_second >= lle->la_expire)) { 161 if (!callout_pending(&lle->la_timer) && 162 callout_active(&lle->la_timer)) 163 (void) llentry_free(lle); 164 } else { 165 /* 166 * Still valid, just drop our reference 167 */ 168 LLE_FREE_LOCKED(lle); 169 } 170 IF_AFDATA_UNLOCK(ifp); 171 } 172 173 /* 174 * Broadcast an ARP request. Caller specifies: 175 * - arp header source ip address 176 * - arp header target ip address 177 * - arp header source ethernet address 178 */ 179 void 180 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 181 u_char *enaddr) 182 { 183 struct mbuf *m; 184 struct arphdr *ah; 185 struct sockaddr sa; 186 187 if (sip == NULL) { 188 /* XXX don't believe this can happen (or explain why) */ 189 /* 190 * The caller did not supply a source address, try to find 191 * a compatible one among those assigned to this interface. 192 */ 193 struct ifaddr *ifa; 194 195 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 196 if (!ifa->ifa_addr || 197 ifa->ifa_addr->sa_family != AF_INET) 198 continue; 199 sip = &SIN(ifa->ifa_addr)->sin_addr; 200 if (0 == ((sip->s_addr ^ tip->s_addr) & 201 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 202 break; /* found it. */ 203 } 204 if (sip == NULL) { 205 printf("%s: cannot find matching address\n", __func__); 206 return; 207 } 208 } 209 210 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 211 return; 212 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 213 2*ifp->if_data.ifi_addrlen; 214 m->m_pkthdr.len = m->m_len; 215 MH_ALIGN(m, m->m_len); 216 ah = mtod(m, struct arphdr *); 217 bzero((caddr_t)ah, m->m_len); 218 #ifdef MAC 219 mac_netinet_arp_send(ifp, m); 220 #endif 221 ah->ar_pro = htons(ETHERTYPE_IP); 222 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 223 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 224 ah->ar_op = htons(ARPOP_REQUEST); 225 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 226 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 227 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 228 sa.sa_family = AF_ARP; 229 sa.sa_len = 2; 230 m->m_flags |= M_BCAST; 231 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 232 } 233 234 /* 235 * Resolve an IP address into an ethernet address. 236 * On input: 237 * ifp is the interface we use 238 * rt0 is the route to the final destination (possibly useless) 239 * m is the mbuf. May be NULL if we don't have a packet. 240 * dst is the next hop, 241 * desten is where we want the address. 242 * 243 * On success, desten is filled in and the function returns 0; 244 * If the packet must be held pending resolution, we return EWOULDBLOCK 245 * On other errors, we return the corresponding error code. 246 * Note that m_freem() handles NULL. 247 */ 248 int 249 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 250 struct sockaddr *dst, u_char *desten, struct llentry **lle) 251 { 252 INIT_VNET_INET(ifp->if_vnet); 253 struct llentry *la = 0; 254 u_int flags; 255 int error, renew; 256 257 *lle = NULL; 258 if (m != NULL) { 259 if (m->m_flags & M_BCAST) { 260 /* broadcast */ 261 (void)memcpy(desten, 262 ifp->if_broadcastaddr, ifp->if_addrlen); 263 return (0); 264 } 265 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 266 /* multicast */ 267 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 268 return (0); 269 } 270 } 271 272 flags = (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) ? 0 : LLE_CREATE; 273 274 /* XXXXX 275 * Since this function returns an llentry, the 276 * lock is held by the caller. 277 * XXX if caller is required to hold lock, assert it 278 */ 279 retry: 280 IF_AFDATA_LOCK(ifp); 281 la = lla_lookup(LLTABLE(ifp), flags, dst); 282 IF_AFDATA_UNLOCK(ifp); 283 if (la == NULL) { 284 if (flags & LLE_CREATE) 285 log(LOG_DEBUG, 286 "arpresolve: can't allocate llinfo for %s\n", 287 inet_ntoa(SIN(dst)->sin_addr)); 288 m_freem(m); 289 return (EINVAL); 290 } 291 292 if ((la->la_flags & LLE_VALID) && 293 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 294 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 295 /* 296 * If entry has an expiry time and it is approaching, 297 * see if we need to send an ARP request within this 298 * arpt_down interval. 299 */ 300 if (!(la->la_flags & LLE_STATIC) && 301 time_uptime + la->la_preempt > la->la_expire) { 302 arprequest(ifp, NULL, 303 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 304 305 la->la_preempt--; 306 } 307 308 *lle = la; 309 error = 0; 310 goto done; 311 } 312 313 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 314 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 315 inet_ntoa(SIN(dst)->sin_addr)); 316 m_freem(m); 317 error = EINVAL; 318 goto done; 319 } 320 321 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 322 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 323 flags |= LLE_EXCLUSIVE; 324 LLE_RUNLOCK(la); 325 goto retry; 326 } 327 /* 328 * There is an arptab entry, but no ethernet address 329 * response yet. Replace the held mbuf with this 330 * latest one. 331 */ 332 if (m != NULL) { 333 if (la->la_hold != NULL) 334 m_freem(la->la_hold); 335 la->la_hold = m; 336 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 337 flags &= ~LLE_EXCLUSIVE; 338 LLE_DOWNGRADE(la); 339 } 340 341 } 342 /* 343 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 344 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 345 * if we have already sent arp_maxtries ARP requests. Retransmit the 346 * ARP request, but not faster than one request per second. 347 */ 348 if (la->la_asked < V_arp_maxtries) 349 error = EWOULDBLOCK; /* First request. */ 350 else 351 error = 352 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH; 353 354 if (renew) { 355 LLE_ADDREF(la); 356 la->la_expire = time_uptime; 357 callout_reset(&la->la_timer, hz, arptimer, la); 358 la->la_asked++; 359 LLE_WUNLOCK(la); 360 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 361 IF_LLADDR(ifp)); 362 return (error); 363 } 364 done: 365 if (flags & LLE_EXCLUSIVE) 366 LLE_WUNLOCK(la); 367 else 368 LLE_RUNLOCK(la); 369 return (error); 370 } 371 372 /* 373 * Common length and type checks are done here, 374 * then the protocol-specific routine is called. 375 */ 376 static void 377 arpintr(struct mbuf *m) 378 { 379 struct arphdr *ar; 380 381 if (m->m_len < sizeof(struct arphdr) && 382 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 383 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 384 return; 385 } 386 ar = mtod(m, struct arphdr *); 387 388 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 389 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 390 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 391 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 392 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 393 (unsigned char *)&ar->ar_hrd, ""); 394 m_freem(m); 395 return; 396 } 397 398 if (m->m_len < arphdr_len(ar)) { 399 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 400 log(LOG_ERR, "arp: runt packet\n"); 401 m_freem(m); 402 return; 403 } 404 ar = mtod(m, struct arphdr *); 405 } 406 407 switch (ntohs(ar->ar_pro)) { 408 #ifdef INET 409 case ETHERTYPE_IP: 410 in_arpinput(m); 411 return; 412 #endif 413 } 414 m_freem(m); 415 } 416 417 #ifdef INET 418 /* 419 * ARP for Internet protocols on 10 Mb/s Ethernet. 420 * Algorithm is that given in RFC 826. 421 * In addition, a sanity check is performed on the sender 422 * protocol address, to catch impersonators. 423 * We no longer handle negotiations for use of trailer protocol: 424 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 425 * along with IP replies if we wanted trailers sent to us, 426 * and also sent them in response to IP replies. 427 * This allowed either end to announce the desire to receive 428 * trailer packets. 429 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 430 * but formerly didn't normally send requests. 431 */ 432 static int log_arp_wrong_iface = 1; 433 static int log_arp_movements = 1; 434 static int log_arp_permanent_modify = 1; 435 436 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 437 &log_arp_wrong_iface, 0, 438 "log arp packets arriving on the wrong interface"); 439 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 440 &log_arp_movements, 0, 441 "log arp replies from MACs different than the one in the cache"); 442 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 443 &log_arp_permanent_modify, 0, 444 "log arp replies from MACs different than the one in the permanent arp entry"); 445 446 447 static void 448 in_arpinput(struct mbuf *m) 449 { 450 struct arphdr *ah; 451 struct ifnet *ifp = m->m_pkthdr.rcvif; 452 struct llentry *la = NULL; 453 struct rtentry *rt; 454 struct ifaddr *ifa; 455 struct in_ifaddr *ia; 456 struct sockaddr sa; 457 struct in_addr isaddr, itaddr, myaddr; 458 u_int8_t *enaddr = NULL; 459 int op, flags; 460 struct mbuf *m0; 461 int req_len; 462 int bridged = 0, is_bridge = 0; 463 #ifdef DEV_CARP 464 int carp_match = 0; 465 #endif 466 struct sockaddr_in sin; 467 sin.sin_len = sizeof(struct sockaddr_in); 468 sin.sin_family = AF_INET; 469 sin.sin_addr.s_addr = 0; 470 INIT_VNET_INET(ifp->if_vnet); 471 472 if (ifp->if_bridge) 473 bridged = 1; 474 if (ifp->if_type == IFT_BRIDGE) 475 is_bridge = 1; 476 477 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 478 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 479 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 480 return; 481 } 482 483 ah = mtod(m, struct arphdr *); 484 op = ntohs(ah->ar_op); 485 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 486 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 487 488 /* 489 * For a bridge, we want to check the address irrespective 490 * of the receive interface. (This will change slightly 491 * when we have clusters of interfaces). 492 * If the interface does not match, but the recieving interface 493 * is part of carp, we call carp_iamatch to see if this is a 494 * request for the virtual host ip. 495 * XXX: This is really ugly! 496 */ 497 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 498 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 499 ia->ia_ifp == ifp) && 500 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 501 goto match; 502 #ifdef DEV_CARP 503 if (ifp->if_carp != NULL && 504 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 505 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 506 carp_match = 1; 507 goto match; 508 } 509 #endif 510 } 511 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 512 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 513 ia->ia_ifp == ifp) && 514 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 515 goto match; 516 517 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 518 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 519 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 520 addr == ia->ia_addr.sin_addr.s_addr) 521 /* 522 * Check the case when bridge shares its MAC address with 523 * some of its children, so packets are claimed by bridge 524 * itself (bridge_input() does it first), but they are really 525 * meant to be destined to the bridge member. 526 */ 527 if (is_bridge) { 528 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 529 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 530 ifp = ia->ia_ifp; 531 goto match; 532 } 533 } 534 } 535 #undef BDG_MEMBER_MATCHES_ARP 536 537 /* 538 * No match, use the first inet address on the receive interface 539 * as a dummy address for the rest of the function. 540 */ 541 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 542 if (ifa->ifa_addr->sa_family == AF_INET) { 543 ia = ifatoia(ifa); 544 goto match; 545 } 546 /* 547 * If bridging, fall back to using any inet address. 548 */ 549 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 550 goto drop; 551 match: 552 if (!enaddr) 553 enaddr = (u_int8_t *)IF_LLADDR(ifp); 554 myaddr = ia->ia_addr.sin_addr; 555 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 556 goto drop; /* it's from me, ignore it. */ 557 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 558 log(LOG_ERR, 559 "arp: link address is broadcast for IP address %s!\n", 560 inet_ntoa(isaddr)); 561 goto drop; 562 } 563 /* 564 * Warn if another host is using the same IP address, but only if the 565 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 566 * case we suppress the warning to avoid false positive complaints of 567 * potential misconfiguration. 568 */ 569 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 570 log(LOG_ERR, 571 "arp: %*D is using my IP address %s on %s!\n", 572 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 573 inet_ntoa(isaddr), ifp->if_xname); 574 itaddr = myaddr; 575 goto reply; 576 } 577 if (ifp->if_flags & IFF_STATICARP) 578 goto reply; 579 580 bzero(&sin, sizeof(sin)); 581 sin.sin_len = sizeof(struct sockaddr_in); 582 sin.sin_family = AF_INET; 583 sin.sin_addr = isaddr; 584 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 585 flags |= LLE_EXCLUSIVE; 586 IF_AFDATA_LOCK(ifp); 587 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 588 IF_AFDATA_UNLOCK(ifp); 589 if (la != NULL) { 590 /* the following is not an error when doing bridging */ 591 if (!bridged && la->lle_tbl->llt_ifp != ifp 592 #ifdef DEV_CARP 593 && (ifp->if_type != IFT_CARP || !carp_match) 594 #endif 595 ) { 596 if (log_arp_wrong_iface) 597 log(LOG_ERR, "arp: %s is on %s " 598 "but got reply from %*D on %s\n", 599 inet_ntoa(isaddr), 600 la->lle_tbl->llt_ifp->if_xname, 601 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 602 ifp->if_xname); 603 goto reply; 604 } 605 if ((la->la_flags & LLE_VALID) && 606 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 607 if (la->la_flags & LLE_STATIC) { 608 log(LOG_ERR, 609 "arp: %*D attempts to modify permanent " 610 "entry for %s on %s\n", 611 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 612 inet_ntoa(isaddr), ifp->if_xname); 613 goto reply; 614 } 615 if (log_arp_movements) { 616 log(LOG_INFO, "arp: %s moved from %*D " 617 "to %*D on %s\n", 618 inet_ntoa(isaddr), 619 ifp->if_addrlen, 620 (u_char *)&la->ll_addr, ":", 621 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 622 ifp->if_xname); 623 } 624 } 625 626 if (ifp->if_addrlen != ah->ar_hln) { 627 log(LOG_WARNING, 628 "arp from %*D: addr len: new %d, i/f %d (ignored)", 629 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 630 ah->ar_hln, ifp->if_addrlen); 631 goto reply; 632 } 633 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 634 la->la_flags |= LLE_VALID; 635 636 if (!(la->la_flags & LLE_STATIC)) { 637 la->la_expire = time_uptime + V_arpt_keep; 638 callout_reset(&la->la_timer, hz * V_arpt_keep, 639 arptimer, la); 640 } 641 la->la_asked = 0; 642 la->la_preempt = V_arp_maxtries; 643 if (la->la_hold != NULL) { 644 m0 = la->la_hold; 645 la->la_hold = 0; 646 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 647 LLE_WUNLOCK(la); 648 649 (*ifp->if_output)(ifp, m0, &sa, NULL); 650 return; 651 } 652 } 653 reply: 654 if (op != ARPOP_REQUEST) 655 goto drop; 656 657 if (itaddr.s_addr == myaddr.s_addr) { 658 /* Shortcut.. the receiving interface is the target. */ 659 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 660 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 661 } else { 662 if (la == NULL) { 663 if (!V_arp_proxyall) 664 goto drop; 665 666 sin.sin_addr = itaddr; 667 /* XXX MRT use table 0 for arp reply */ 668 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 669 if (!rt) 670 goto drop; 671 /* 672 * Don't send proxies for nodes on the same interface 673 * as this one came out of, or we'll get into a fight 674 * over who claims what Ether address. 675 */ 676 if (rt->rt_ifp == ifp) { 677 RTFREE_LOCKED(rt); 678 goto drop; 679 } 680 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 681 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 682 RTFREE_LOCKED(rt); 683 684 /* 685 * Also check that the node which sent the ARP packet 686 * is on the the interface we expect it to be on. This 687 * avoids ARP chaos if an interface is connected to the 688 * wrong network. 689 */ 690 sin.sin_addr = isaddr; 691 692 /* XXX MRT use table 0 for arp checks */ 693 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 694 if (!rt) 695 goto drop; 696 if (rt->rt_ifp != ifp) { 697 log(LOG_INFO, "arp_proxy: ignoring request" 698 " from %s via %s, expecting %s\n", 699 inet_ntoa(isaddr), ifp->if_xname, 700 rt->rt_ifp->if_xname); 701 RTFREE_LOCKED(rt); 702 goto drop; 703 } 704 RTFREE_LOCKED(rt); 705 706 #ifdef DEBUG_PROXY 707 printf("arp: proxying for %s\n", 708 inet_ntoa(itaddr)); 709 #endif 710 } else { 711 /* 712 * Return proxied ARP replies only on the interface 713 * or bridge cluster where this network resides. 714 * Otherwise we may conflict with the host we are 715 * proxying for. 716 */ 717 if (la->lle_tbl->llt_ifp != ifp && 718 (la->lle_tbl->llt_ifp->if_bridge != ifp->if_bridge || 719 ifp->if_bridge == NULL)) { 720 goto drop; 721 } 722 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 723 (void)memcpy(ar_sha(ah), &la->ll_addr, ah->ar_hln); 724 } 725 } 726 727 if (la != NULL) 728 LLE_WUNLOCK(la); 729 if (itaddr.s_addr == myaddr.s_addr && 730 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 731 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 732 #ifdef DEBUG_LINKLOCAL 733 printf("arp: sending reply for link-local addr %s\n", 734 inet_ntoa(itaddr)); 735 #endif 736 m->m_flags |= M_BCAST; 737 m->m_flags &= ~M_MCAST; 738 } else { 739 /* default behaviour; never reply by broadcast. */ 740 m->m_flags &= ~(M_BCAST|M_MCAST); 741 } 742 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 743 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 744 ah->ar_op = htons(ARPOP_REPLY); 745 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 746 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 747 m->m_pkthdr.len = m->m_len; 748 sa.sa_family = AF_ARP; 749 sa.sa_len = 2; 750 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 751 return; 752 753 drop: 754 if (la != NULL) 755 LLE_WUNLOCK(la); 756 m_freem(m); 757 } 758 #endif 759 760 void 761 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 762 { 763 struct llentry *lle; 764 765 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 766 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 767 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 768 /* 769 * interface address is considered static entry 770 * because the output of the arp utility shows 771 * that L2 entry as permanent 772 */ 773 IF_AFDATA_LOCK(ifp); 774 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 775 (struct sockaddr *)IA_SIN(ifa)); 776 IF_AFDATA_UNLOCK(ifp); 777 if (lle == NULL) 778 log(LOG_INFO, "arp_ifinit: cannot create arp " 779 "entry for interface address\n"); 780 LLE_RUNLOCK(lle); 781 ifa->ifa_rtrequest = NULL; 782 } 783 784 void 785 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 786 { 787 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 788 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 789 &IA_SIN(ifa)->sin_addr, enaddr); 790 ifa->ifa_rtrequest = NULL; 791 } 792 793 static void 794 arp_init(void) 795 { 796 INIT_VNET_INET(curvnet); 797 798 V_arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 799 V_arp_maxtries = 5; 800 V_useloopback = 1; /* use loopback interface for local traffic */ 801 V_arp_proxyall = 0; 802 803 arpintrq.ifq_maxlen = 50; 804 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 805 netisr_register(NETISR_ARP, arpintr, &arpintrq, 0); 806 } 807 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 808