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_carp.h" 43 44 #include <sys/param.h> 45 #include <sys/kernel.h> 46 #include <sys/queue.h> 47 #include <sys/sysctl.h> 48 #include <sys/systm.h> 49 #include <sys/mbuf.h> 50 #include <sys/malloc.h> 51 #include <sys/proc.h> 52 #include <sys/socket.h> 53 #include <sys/syslog.h> 54 #include <sys/vimage.h> 55 56 #include <net/if.h> 57 #include <net/if_dl.h> 58 #include <net/if_types.h> 59 #include <net/netisr.h> 60 #include <net/if_llc.h> 61 #include <net/ethernet.h> 62 #include <net/route.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 #include <netinet/vinet.h> 69 70 #include <net/if_arc.h> 71 #include <net/iso88025.h> 72 73 #ifdef DEV_CARP 74 #include <netinet/ip_carp.h> 75 #endif 76 77 #include <security/mac/mac_framework.h> 78 79 #define SIN(s) ((struct sockaddr_in *)s) 80 #define SDL(s) ((struct sockaddr_dl *)s) 81 82 SYSCTL_DECL(_net_link_ether); 83 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 84 85 /* timer values */ 86 #ifdef VIMAGE_GLOBALS 87 static int arpt_keep; /* once resolved, good for 20 more minutes */ 88 static int arp_maxtries; 89 int useloopback; /* use loopback interface for local traffic */ 90 static int arp_proxyall; 91 #endif 92 93 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, max_age, 94 CTLFLAG_RW, arpt_keep, 0, "ARP entry lifetime in seconds"); 95 96 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, maxtries, 97 CTLFLAG_RW, arp_maxtries, 0, 98 "ARP resolution attempts before returning error"); 99 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, useloopback, 100 CTLFLAG_RW, useloopback, 0, 101 "Use the loopback interface for local traffic"); 102 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, proxyall, 103 CTLFLAG_RW, arp_proxyall, 0, 104 "Enable proxy ARP for all suitable requests"); 105 106 static void arp_init(void); 107 static int arp_iattach(const void *); 108 void arprequest(struct ifnet *, 109 struct in_addr *, struct in_addr *, u_char *); 110 static void arpintr(struct mbuf *); 111 static void arptimer(void *); 112 #ifdef INET 113 static void in_arpinput(struct mbuf *); 114 #endif 115 116 static const struct netisr_handler arp_nh = { 117 .nh_name = "arp", 118 .nh_handler = arpintr, 119 .nh_proto = NETISR_ARP, 120 .nh_policy = NETISR_POLICY_SOURCE, 121 }; 122 123 #ifndef VIMAGE_GLOBALS 124 static const vnet_modinfo_t vnet_arp_modinfo = { 125 .vmi_id = VNET_MOD_ARP, 126 .vmi_name = "arp", 127 .vmi_dependson = VNET_MOD_INET, 128 .vmi_iattach = arp_iattach 129 }; 130 #endif /* !VIMAGE_GLOBALS */ 131 132 #ifdef AF_INET 133 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 134 135 /* 136 * called by in_ifscrub to remove entry from the table when 137 * the interface goes away 138 */ 139 void 140 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 141 { 142 struct sockaddr_in addr4; 143 144 bzero((void *)&addr4, sizeof(addr4)); 145 addr4.sin_len = sizeof(addr4); 146 addr4.sin_family = AF_INET; 147 addr4.sin_addr.s_addr = addr; 148 CURVNET_SET(ifp->if_vnet); 149 IF_AFDATA_LOCK(ifp); 150 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 151 (struct sockaddr *)&addr4); 152 IF_AFDATA_UNLOCK(ifp); 153 CURVNET_RESTORE(); 154 } 155 #endif 156 157 /* 158 * Timeout routine. Age arp_tab entries periodically. 159 */ 160 static void 161 arptimer(void *arg) 162 { 163 struct ifnet *ifp; 164 struct llentry *lle = (struct llentry *)arg; 165 166 if (lle == NULL) { 167 panic("%s: NULL entry!\n", __func__); 168 return; 169 } 170 ifp = lle->lle_tbl->llt_ifp; 171 IF_AFDATA_LOCK(ifp); 172 LLE_WLOCK(lle); 173 if (((lle->la_flags & LLE_DELETED) 174 || (time_second >= lle->la_expire)) 175 && (!callout_pending(&lle->la_timer) && 176 callout_active(&lle->la_timer))) 177 (void) llentry_free(lle); 178 else { 179 /* 180 * Still valid, just drop our reference 181 */ 182 LLE_FREE_LOCKED(lle); 183 } 184 IF_AFDATA_UNLOCK(ifp); 185 } 186 187 /* 188 * Broadcast an ARP request. Caller specifies: 189 * - arp header source ip address 190 * - arp header target ip address 191 * - arp header source ethernet address 192 */ 193 void 194 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 195 u_char *enaddr) 196 { 197 struct mbuf *m; 198 struct arphdr *ah; 199 struct sockaddr sa; 200 201 if (sip == NULL) { 202 /* XXX don't believe this can happen (or explain why) */ 203 /* 204 * The caller did not supply a source address, try to find 205 * a compatible one among those assigned to this interface. 206 */ 207 struct ifaddr *ifa; 208 209 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 210 if (!ifa->ifa_addr || 211 ifa->ifa_addr->sa_family != AF_INET) 212 continue; 213 sip = &SIN(ifa->ifa_addr)->sin_addr; 214 if (0 == ((sip->s_addr ^ tip->s_addr) & 215 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 216 break; /* found it. */ 217 } 218 if (sip == NULL) { 219 printf("%s: cannot find matching address\n", __func__); 220 return; 221 } 222 } 223 224 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 225 return; 226 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 227 2*ifp->if_data.ifi_addrlen; 228 m->m_pkthdr.len = m->m_len; 229 MH_ALIGN(m, m->m_len); 230 ah = mtod(m, struct arphdr *); 231 bzero((caddr_t)ah, m->m_len); 232 #ifdef MAC 233 mac_netinet_arp_send(ifp, m); 234 #endif 235 ah->ar_pro = htons(ETHERTYPE_IP); 236 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 237 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 238 ah->ar_op = htons(ARPOP_REQUEST); 239 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 240 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 241 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 242 sa.sa_family = AF_ARP; 243 sa.sa_len = 2; 244 m->m_flags |= M_BCAST; 245 (*ifp->if_output)(ifp, m, &sa, NULL); 246 } 247 248 /* 249 * Resolve an IP address into an ethernet address. 250 * On input: 251 * ifp is the interface we use 252 * rt0 is the route to the final destination (possibly useless) 253 * m is the mbuf. May be NULL if we don't have a packet. 254 * dst is the next hop, 255 * desten is where we want the address. 256 * 257 * On success, desten is filled in and the function returns 0; 258 * If the packet must be held pending resolution, we return EWOULDBLOCK 259 * On other errors, we return the corresponding error code. 260 * Note that m_freem() handles NULL. 261 */ 262 int 263 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 264 struct sockaddr *dst, u_char *desten, struct llentry **lle) 265 { 266 INIT_VNET_INET(ifp->if_vnet); 267 struct llentry *la = 0; 268 u_int flags = 0; 269 int error, renew; 270 271 *lle = NULL; 272 if (m != NULL) { 273 if (m->m_flags & M_BCAST) { 274 /* broadcast */ 275 (void)memcpy(desten, 276 ifp->if_broadcastaddr, ifp->if_addrlen); 277 return (0); 278 } 279 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 280 /* multicast */ 281 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 282 return (0); 283 } 284 } 285 /* XXXXX 286 */ 287 retry: 288 IF_AFDATA_RLOCK(ifp); 289 la = lla_lookup(LLTABLE(ifp), flags, dst); 290 IF_AFDATA_RUNLOCK(ifp); 291 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 292 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 293 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 294 IF_AFDATA_WLOCK(ifp); 295 la = lla_lookup(LLTABLE(ifp), flags, dst); 296 IF_AFDATA_WUNLOCK(ifp); 297 } 298 if (la == NULL) { 299 if (flags & LLE_CREATE) 300 log(LOG_DEBUG, 301 "arpresolve: can't allocate llinfo for %s\n", 302 inet_ntoa(SIN(dst)->sin_addr)); 303 m_freem(m); 304 return (EINVAL); 305 } 306 307 if ((la->la_flags & LLE_VALID) && 308 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 309 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 310 /* 311 * If entry has an expiry time and it is approaching, 312 * see if we need to send an ARP request within this 313 * arpt_down interval. 314 */ 315 if (!(la->la_flags & LLE_STATIC) && 316 time_uptime + la->la_preempt > la->la_expire) { 317 arprequest(ifp, NULL, 318 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 319 320 la->la_preempt--; 321 } 322 323 *lle = la; 324 error = 0; 325 goto done; 326 } 327 328 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 329 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 330 inet_ntoa(SIN(dst)->sin_addr)); 331 m_freem(m); 332 error = EINVAL; 333 goto done; 334 } 335 336 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 337 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 338 flags |= LLE_EXCLUSIVE; 339 LLE_RUNLOCK(la); 340 goto retry; 341 } 342 /* 343 * There is an arptab entry, but no ethernet address 344 * response yet. Replace the held mbuf with this 345 * latest one. 346 */ 347 if (m != NULL) { 348 if (la->la_hold != NULL) 349 m_freem(la->la_hold); 350 la->la_hold = m; 351 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 352 flags &= ~LLE_EXCLUSIVE; 353 LLE_DOWNGRADE(la); 354 } 355 356 } 357 /* 358 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 359 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 360 * if we have already sent arp_maxtries ARP requests. Retransmit the 361 * ARP request, but not faster than one request per second. 362 */ 363 if (la->la_asked < V_arp_maxtries) 364 error = EWOULDBLOCK; /* First request. */ 365 else 366 error = 367 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH; 368 369 if (renew) { 370 LLE_ADDREF(la); 371 la->la_expire = time_uptime; 372 callout_reset(&la->la_timer, hz, arptimer, la); 373 la->la_asked++; 374 LLE_WUNLOCK(la); 375 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 376 IF_LLADDR(ifp)); 377 return (error); 378 } 379 done: 380 if (flags & LLE_EXCLUSIVE) 381 LLE_WUNLOCK(la); 382 else 383 LLE_RUNLOCK(la); 384 return (error); 385 } 386 387 /* 388 * Common length and type checks are done here, 389 * then the protocol-specific routine is called. 390 */ 391 static void 392 arpintr(struct mbuf *m) 393 { 394 struct arphdr *ar; 395 396 if (m->m_len < sizeof(struct arphdr) && 397 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 398 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 399 return; 400 } 401 ar = mtod(m, struct arphdr *); 402 403 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 404 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 405 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 406 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 407 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 408 (unsigned char *)&ar->ar_hrd, ""); 409 m_freem(m); 410 return; 411 } 412 413 if (m->m_len < arphdr_len(ar)) { 414 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 415 log(LOG_ERR, "arp: runt packet\n"); 416 m_freem(m); 417 return; 418 } 419 ar = mtod(m, struct arphdr *); 420 } 421 422 switch (ntohs(ar->ar_pro)) { 423 #ifdef INET 424 case ETHERTYPE_IP: 425 in_arpinput(m); 426 return; 427 #endif 428 } 429 m_freem(m); 430 } 431 432 #ifdef INET 433 /* 434 * ARP for Internet protocols on 10 Mb/s Ethernet. 435 * Algorithm is that given in RFC 826. 436 * In addition, a sanity check is performed on the sender 437 * protocol address, to catch impersonators. 438 * We no longer handle negotiations for use of trailer protocol: 439 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 440 * along with IP replies if we wanted trailers sent to us, 441 * and also sent them in response to IP replies. 442 * This allowed either end to announce the desire to receive 443 * trailer packets. 444 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 445 * but formerly didn't normally send requests. 446 */ 447 static int log_arp_wrong_iface = 1; 448 static int log_arp_movements = 1; 449 static int log_arp_permanent_modify = 1; 450 451 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 452 &log_arp_wrong_iface, 0, 453 "log arp packets arriving on the wrong interface"); 454 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 455 &log_arp_movements, 0, 456 "log arp replies from MACs different than the one in the cache"); 457 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 458 &log_arp_permanent_modify, 0, 459 "log arp replies from MACs different than the one in the permanent arp entry"); 460 461 462 static void 463 in_arpinput(struct mbuf *m) 464 { 465 struct arphdr *ah; 466 struct ifnet *ifp = m->m_pkthdr.rcvif; 467 struct llentry *la = NULL; 468 struct rtentry *rt; 469 struct ifaddr *ifa; 470 struct in_ifaddr *ia; 471 struct sockaddr sa; 472 struct in_addr isaddr, itaddr, myaddr; 473 u_int8_t *enaddr = NULL; 474 int op, flags; 475 struct mbuf *m0; 476 int req_len; 477 int bridged = 0, is_bridge = 0; 478 #ifdef DEV_CARP 479 int carp_match = 0; 480 #endif 481 struct sockaddr_in sin; 482 sin.sin_len = sizeof(struct sockaddr_in); 483 sin.sin_family = AF_INET; 484 sin.sin_addr.s_addr = 0; 485 INIT_VNET_INET(ifp->if_vnet); 486 487 if (ifp->if_bridge) 488 bridged = 1; 489 if (ifp->if_type == IFT_BRIDGE) 490 is_bridge = 1; 491 492 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 493 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 494 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 495 return; 496 } 497 498 ah = mtod(m, struct arphdr *); 499 op = ntohs(ah->ar_op); 500 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 501 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 502 503 /* 504 * For a bridge, we want to check the address irrespective 505 * of the receive interface. (This will change slightly 506 * when we have clusters of interfaces). 507 * If the interface does not match, but the recieving interface 508 * is part of carp, we call carp_iamatch to see if this is a 509 * request for the virtual host ip. 510 * XXX: This is really ugly! 511 */ 512 IN_IFADDR_RLOCK(); 513 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 514 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 515 ia->ia_ifp == ifp) && 516 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 517 ifa_ref(&ia->ia_ifa); 518 IN_IFADDR_RUNLOCK(); 519 goto match; 520 } 521 #ifdef DEV_CARP 522 if (ifp->if_carp != NULL && 523 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 524 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 525 carp_match = 1; 526 ifa_ref(&ia->ia_ifa); 527 IN_IFADDR_RUNLOCK(); 528 goto match; 529 } 530 #endif 531 } 532 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 533 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 534 ia->ia_ifp == ifp) && 535 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 536 ifa_ref(&ia->ia_ifa); 537 IN_IFADDR_RUNLOCK(); 538 goto match; 539 } 540 541 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 542 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 543 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 544 addr == ia->ia_addr.sin_addr.s_addr) 545 /* 546 * Check the case when bridge shares its MAC address with 547 * some of its children, so packets are claimed by bridge 548 * itself (bridge_input() does it first), but they are really 549 * meant to be destined to the bridge member. 550 */ 551 if (is_bridge) { 552 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 553 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 554 ifa_ref(&ia->ia_ifa); 555 ifp = ia->ia_ifp; 556 IN_IFADDR_RUNLOCK(); 557 goto match; 558 } 559 } 560 } 561 #undef BDG_MEMBER_MATCHES_ARP 562 IN_IFADDR_RUNLOCK(); 563 564 /* 565 * No match, use the first inet address on the receive interface 566 * as a dummy address for the rest of the function. 567 */ 568 IF_ADDR_LOCK(ifp); 569 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 570 if (ifa->ifa_addr->sa_family == AF_INET) { 571 ia = ifatoia(ifa); 572 ifa_ref(ifa); 573 IF_ADDR_UNLOCK(ifp); 574 goto match; 575 } 576 IF_ADDR_UNLOCK(ifp); 577 578 /* 579 * If bridging, fall back to using any inet address. 580 */ 581 IN_IFADDR_RLOCK(); 582 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 583 IN_IFADDR_RUNLOCK(); 584 goto drop; 585 } 586 ifa_ref(&ia->ia_ifa); 587 IN_IFADDR_RUNLOCK(); 588 match: 589 if (!enaddr) 590 enaddr = (u_int8_t *)IF_LLADDR(ifp); 591 myaddr = ia->ia_addr.sin_addr; 592 ifa_free(&ia->ia_ifa); 593 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 594 goto drop; /* it's from me, ignore it. */ 595 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 596 log(LOG_ERR, 597 "arp: link address is broadcast for IP address %s!\n", 598 inet_ntoa(isaddr)); 599 goto drop; 600 } 601 /* 602 * Warn if another host is using the same IP address, but only if the 603 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 604 * case we suppress the warning to avoid false positive complaints of 605 * potential misconfiguration. 606 */ 607 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 608 log(LOG_ERR, 609 "arp: %*D is using my IP address %s on %s!\n", 610 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 611 inet_ntoa(isaddr), ifp->if_xname); 612 itaddr = myaddr; 613 goto reply; 614 } 615 if (ifp->if_flags & IFF_STATICARP) 616 goto reply; 617 618 bzero(&sin, sizeof(sin)); 619 sin.sin_len = sizeof(struct sockaddr_in); 620 sin.sin_family = AF_INET; 621 sin.sin_addr = isaddr; 622 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 623 flags |= LLE_EXCLUSIVE; 624 IF_AFDATA_LOCK(ifp); 625 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 626 IF_AFDATA_UNLOCK(ifp); 627 if (la != NULL) { 628 /* the following is not an error when doing bridging */ 629 if (!bridged && la->lle_tbl->llt_ifp != ifp 630 #ifdef DEV_CARP 631 && (ifp->if_type != IFT_CARP || !carp_match) 632 #endif 633 ) { 634 if (log_arp_wrong_iface) 635 log(LOG_ERR, "arp: %s is on %s " 636 "but got reply from %*D on %s\n", 637 inet_ntoa(isaddr), 638 la->lle_tbl->llt_ifp->if_xname, 639 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 640 ifp->if_xname); 641 goto reply; 642 } 643 if ((la->la_flags & LLE_VALID) && 644 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 645 if (la->la_flags & LLE_STATIC) { 646 log(LOG_ERR, 647 "arp: %*D attempts to modify permanent " 648 "entry for %s on %s\n", 649 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 650 inet_ntoa(isaddr), ifp->if_xname); 651 goto reply; 652 } 653 if (log_arp_movements) { 654 log(LOG_INFO, "arp: %s moved from %*D " 655 "to %*D on %s\n", 656 inet_ntoa(isaddr), 657 ifp->if_addrlen, 658 (u_char *)&la->ll_addr, ":", 659 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 660 ifp->if_xname); 661 } 662 } 663 664 if (ifp->if_addrlen != ah->ar_hln) { 665 log(LOG_WARNING, 666 "arp from %*D: addr len: new %d, i/f %d (ignored)", 667 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 668 ah->ar_hln, ifp->if_addrlen); 669 goto reply; 670 } 671 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 672 la->la_flags |= LLE_VALID; 673 674 if (!(la->la_flags & LLE_STATIC)) { 675 la->la_expire = time_uptime + V_arpt_keep; 676 callout_reset(&la->la_timer, hz * V_arpt_keep, 677 arptimer, la); 678 } 679 la->la_asked = 0; 680 la->la_preempt = V_arp_maxtries; 681 if (la->la_hold != NULL) { 682 m0 = la->la_hold; 683 la->la_hold = 0; 684 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 685 LLE_WUNLOCK(la); 686 687 (*ifp->if_output)(ifp, m0, &sa, NULL); 688 return; 689 } 690 } 691 reply: 692 if (op != ARPOP_REQUEST) 693 goto drop; 694 695 if (itaddr.s_addr == myaddr.s_addr) { 696 /* Shortcut.. the receiving interface is the target. */ 697 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 698 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 699 } else { 700 struct llentry *lle = NULL; 701 702 if (!V_arp_proxyall) 703 goto drop; 704 705 sin.sin_addr = itaddr; 706 /* XXX MRT use table 0 for arp reply */ 707 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 708 if (!rt) 709 goto drop; 710 711 /* 712 * Don't send proxies for nodes on the same interface 713 * as this one came out of, or we'll get into a fight 714 * over who claims what Ether address. 715 */ 716 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 717 RTFREE_LOCKED(rt); 718 goto drop; 719 } 720 IF_AFDATA_LOCK(rt->rt_ifp); 721 lle = lla_lookup(LLTABLE(rt->rt_ifp), 0, (struct sockaddr *)&sin); 722 IF_AFDATA_UNLOCK(rt->rt_ifp); 723 RTFREE_LOCKED(rt); 724 725 if (lle != NULL) { 726 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 727 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 728 LLE_RUNLOCK(lle); 729 } else 730 goto drop; 731 732 /* 733 * Also check that the node which sent the ARP packet 734 * is on the the interface we expect it to be on. This 735 * avoids ARP chaos if an interface is connected to the 736 * wrong network. 737 */ 738 sin.sin_addr = isaddr; 739 740 /* XXX MRT use table 0 for arp checks */ 741 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 742 if (!rt) 743 goto drop; 744 if (rt->rt_ifp != ifp) { 745 log(LOG_INFO, "arp_proxy: ignoring request" 746 " from %s via %s, expecting %s\n", 747 inet_ntoa(isaddr), ifp->if_xname, 748 rt->rt_ifp->if_xname); 749 RTFREE_LOCKED(rt); 750 goto drop; 751 } 752 RTFREE_LOCKED(rt); 753 754 #ifdef DEBUG_PROXY 755 printf("arp: proxying for %s\n", 756 inet_ntoa(itaddr)); 757 #endif 758 } 759 760 if (la != NULL) 761 LLE_WUNLOCK(la); 762 if (itaddr.s_addr == myaddr.s_addr && 763 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 764 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 765 #ifdef DEBUG_LINKLOCAL 766 printf("arp: sending reply for link-local addr %s\n", 767 inet_ntoa(itaddr)); 768 #endif 769 m->m_flags |= M_BCAST; 770 m->m_flags &= ~M_MCAST; 771 } else { 772 /* default behaviour; never reply by broadcast. */ 773 m->m_flags &= ~(M_BCAST|M_MCAST); 774 } 775 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 776 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 777 ah->ar_op = htons(ARPOP_REPLY); 778 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 779 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 780 m->m_pkthdr.len = m->m_len; 781 sa.sa_family = AF_ARP; 782 sa.sa_len = 2; 783 (*ifp->if_output)(ifp, m, &sa, NULL); 784 return; 785 786 drop: 787 if (la != NULL) 788 LLE_WUNLOCK(la); 789 m_freem(m); 790 } 791 #endif 792 793 void 794 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 795 { 796 struct llentry *lle; 797 798 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 799 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 800 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 801 /* 802 * interface address is considered static entry 803 * because the output of the arp utility shows 804 * that L2 entry as permanent 805 */ 806 IF_AFDATA_LOCK(ifp); 807 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 808 (struct sockaddr *)IA_SIN(ifa)); 809 IF_AFDATA_UNLOCK(ifp); 810 if (lle == NULL) 811 log(LOG_INFO, "arp_ifinit: cannot create arp " 812 "entry for interface address\n"); 813 else 814 LLE_RUNLOCK(lle); 815 } 816 ifa->ifa_rtrequest = NULL; 817 } 818 819 void 820 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 821 { 822 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 823 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 824 &IA_SIN(ifa)->sin_addr, enaddr); 825 ifa->ifa_rtrequest = NULL; 826 } 827 828 static int 829 arp_iattach(const void *unused __unused) 830 { 831 INIT_VNET_INET(curvnet); 832 833 V_arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 834 V_arp_maxtries = 5; 835 V_useloopback = 1; /* use loopback interface for local traffic */ 836 V_arp_proxyall = 0; 837 838 return (0); 839 } 840 841 static void 842 arp_init(void) 843 { 844 845 #ifndef VIMAGE_GLOBALS 846 vnet_mod_register(&vnet_arp_modinfo); 847 #else 848 arp_iattach(NULL); 849 #endif 850 851 netisr_register(&arp_nh); 852 } 853 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 854