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 && (!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 = 0; 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 /* XXXXX 272 */ 273 retry: 274 IF_AFDATA_RLOCK(ifp); 275 la = lla_lookup(LLTABLE(ifp), flags, dst); 276 IF_AFDATA_RUNLOCK(ifp); 277 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 278 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 279 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 280 IF_AFDATA_WLOCK(ifp); 281 la = lla_lookup(LLTABLE(ifp), flags, dst); 282 IF_AFDATA_WUNLOCK(ifp); 283 } 284 if (la == NULL) { 285 if (flags & LLE_CREATE) 286 log(LOG_DEBUG, 287 "arpresolve: can't allocate llinfo for %s\n", 288 inet_ntoa(SIN(dst)->sin_addr)); 289 m_freem(m); 290 return (EINVAL); 291 } 292 293 if ((la->la_flags & LLE_VALID) && 294 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 295 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 296 /* 297 * If entry has an expiry time and it is approaching, 298 * see if we need to send an ARP request within this 299 * arpt_down interval. 300 */ 301 if (!(la->la_flags & LLE_STATIC) && 302 time_uptime + la->la_preempt > la->la_expire) { 303 arprequest(ifp, NULL, 304 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 305 306 la->la_preempt--; 307 } 308 309 *lle = la; 310 error = 0; 311 goto done; 312 } 313 314 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 315 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 316 inet_ntoa(SIN(dst)->sin_addr)); 317 m_freem(m); 318 error = EINVAL; 319 goto done; 320 } 321 322 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 323 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 324 flags |= LLE_EXCLUSIVE; 325 LLE_RUNLOCK(la); 326 goto retry; 327 } 328 /* 329 * There is an arptab entry, but no ethernet address 330 * response yet. Replace the held mbuf with this 331 * latest one. 332 */ 333 if (m != NULL) { 334 if (la->la_hold != NULL) 335 m_freem(la->la_hold); 336 la->la_hold = m; 337 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 338 flags &= ~LLE_EXCLUSIVE; 339 LLE_DOWNGRADE(la); 340 } 341 342 } 343 /* 344 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 345 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 346 * if we have already sent arp_maxtries ARP requests. Retransmit the 347 * ARP request, but not faster than one request per second. 348 */ 349 if (la->la_asked < V_arp_maxtries) 350 error = EWOULDBLOCK; /* First request. */ 351 else 352 error = 353 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH; 354 355 if (renew) { 356 LLE_ADDREF(la); 357 la->la_expire = time_uptime; 358 callout_reset(&la->la_timer, hz, arptimer, la); 359 la->la_asked++; 360 LLE_WUNLOCK(la); 361 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 362 IF_LLADDR(ifp)); 363 return (error); 364 } 365 done: 366 if (flags & LLE_EXCLUSIVE) 367 LLE_WUNLOCK(la); 368 else 369 LLE_RUNLOCK(la); 370 return (error); 371 } 372 373 /* 374 * Common length and type checks are done here, 375 * then the protocol-specific routine is called. 376 */ 377 static void 378 arpintr(struct mbuf *m) 379 { 380 struct arphdr *ar; 381 382 if (m->m_len < sizeof(struct arphdr) && 383 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 384 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 385 return; 386 } 387 ar = mtod(m, struct arphdr *); 388 389 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 390 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 391 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 392 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 393 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 394 (unsigned char *)&ar->ar_hrd, ""); 395 m_freem(m); 396 return; 397 } 398 399 if (m->m_len < arphdr_len(ar)) { 400 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 401 log(LOG_ERR, "arp: runt packet\n"); 402 m_freem(m); 403 return; 404 } 405 ar = mtod(m, struct arphdr *); 406 } 407 408 switch (ntohs(ar->ar_pro)) { 409 #ifdef INET 410 case ETHERTYPE_IP: 411 in_arpinput(m); 412 return; 413 #endif 414 } 415 m_freem(m); 416 } 417 418 #ifdef INET 419 /* 420 * ARP for Internet protocols on 10 Mb/s Ethernet. 421 * Algorithm is that given in RFC 826. 422 * In addition, a sanity check is performed on the sender 423 * protocol address, to catch impersonators. 424 * We no longer handle negotiations for use of trailer protocol: 425 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 426 * along with IP replies if we wanted trailers sent to us, 427 * and also sent them in response to IP replies. 428 * This allowed either end to announce the desire to receive 429 * trailer packets. 430 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 431 * but formerly didn't normally send requests. 432 */ 433 static int log_arp_wrong_iface = 1; 434 static int log_arp_movements = 1; 435 static int log_arp_permanent_modify = 1; 436 437 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 438 &log_arp_wrong_iface, 0, 439 "log arp packets arriving on the wrong interface"); 440 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 441 &log_arp_movements, 0, 442 "log arp replies from MACs different than the one in the cache"); 443 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 444 &log_arp_permanent_modify, 0, 445 "log arp replies from MACs different than the one in the permanent arp entry"); 446 447 448 static void 449 in_arpinput(struct mbuf *m) 450 { 451 struct arphdr *ah; 452 struct ifnet *ifp = m->m_pkthdr.rcvif; 453 struct llentry *la = NULL; 454 struct rtentry *rt; 455 struct ifaddr *ifa; 456 struct in_ifaddr *ia; 457 struct sockaddr sa; 458 struct in_addr isaddr, itaddr, myaddr; 459 u_int8_t *enaddr = NULL; 460 int op, flags; 461 struct mbuf *m0; 462 int req_len; 463 int bridged = 0, is_bridge = 0; 464 #ifdef DEV_CARP 465 int carp_match = 0; 466 #endif 467 struct sockaddr_in sin; 468 sin.sin_len = sizeof(struct sockaddr_in); 469 sin.sin_family = AF_INET; 470 sin.sin_addr.s_addr = 0; 471 INIT_VNET_INET(ifp->if_vnet); 472 473 if (ifp->if_bridge) 474 bridged = 1; 475 if (ifp->if_type == IFT_BRIDGE) 476 is_bridge = 1; 477 478 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 479 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 480 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 481 return; 482 } 483 484 ah = mtod(m, struct arphdr *); 485 op = ntohs(ah->ar_op); 486 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 487 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 488 489 /* 490 * For a bridge, we want to check the address irrespective 491 * of the receive interface. (This will change slightly 492 * when we have clusters of interfaces). 493 * If the interface does not match, but the recieving interface 494 * is part of carp, we call carp_iamatch to see if this is a 495 * request for the virtual host ip. 496 * XXX: This is really ugly! 497 */ 498 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 499 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 500 ia->ia_ifp == ifp) && 501 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 502 goto match; 503 #ifdef DEV_CARP 504 if (ifp->if_carp != NULL && 505 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 506 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 507 carp_match = 1; 508 goto match; 509 } 510 #endif 511 } 512 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 513 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 514 ia->ia_ifp == ifp) && 515 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 516 goto match; 517 518 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 519 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 520 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 521 addr == ia->ia_addr.sin_addr.s_addr) 522 /* 523 * Check the case when bridge shares its MAC address with 524 * some of its children, so packets are claimed by bridge 525 * itself (bridge_input() does it first), but they are really 526 * meant to be destined to the bridge member. 527 */ 528 if (is_bridge) { 529 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 530 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 531 ifp = ia->ia_ifp; 532 goto match; 533 } 534 } 535 } 536 #undef BDG_MEMBER_MATCHES_ARP 537 538 /* 539 * No match, use the first inet address on the receive interface 540 * as a dummy address for the rest of the function. 541 */ 542 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 543 if (ifa->ifa_addr->sa_family == AF_INET) { 544 ia = ifatoia(ifa); 545 goto match; 546 } 547 /* 548 * If bridging, fall back to using any inet address. 549 */ 550 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 551 goto drop; 552 match: 553 if (!enaddr) 554 enaddr = (u_int8_t *)IF_LLADDR(ifp); 555 myaddr = ia->ia_addr.sin_addr; 556 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 557 goto drop; /* it's from me, ignore it. */ 558 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 559 log(LOG_ERR, 560 "arp: link address is broadcast for IP address %s!\n", 561 inet_ntoa(isaddr)); 562 goto drop; 563 } 564 /* 565 * Warn if another host is using the same IP address, but only if the 566 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 567 * case we suppress the warning to avoid false positive complaints of 568 * potential misconfiguration. 569 */ 570 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 571 log(LOG_ERR, 572 "arp: %*D is using my IP address %s on %s!\n", 573 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 574 inet_ntoa(isaddr), ifp->if_xname); 575 itaddr = myaddr; 576 goto reply; 577 } 578 if (ifp->if_flags & IFF_STATICARP) 579 goto reply; 580 581 bzero(&sin, sizeof(sin)); 582 sin.sin_len = sizeof(struct sockaddr_in); 583 sin.sin_family = AF_INET; 584 sin.sin_addr = isaddr; 585 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 586 flags |= LLE_EXCLUSIVE; 587 IF_AFDATA_LOCK(ifp); 588 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 589 IF_AFDATA_UNLOCK(ifp); 590 if (la != NULL) { 591 /* the following is not an error when doing bridging */ 592 if (!bridged && la->lle_tbl->llt_ifp != ifp 593 #ifdef DEV_CARP 594 && (ifp->if_type != IFT_CARP || !carp_match) 595 #endif 596 ) { 597 if (log_arp_wrong_iface) 598 log(LOG_ERR, "arp: %s is on %s " 599 "but got reply from %*D on %s\n", 600 inet_ntoa(isaddr), 601 la->lle_tbl->llt_ifp->if_xname, 602 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 603 ifp->if_xname); 604 goto reply; 605 } 606 if ((la->la_flags & LLE_VALID) && 607 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 608 if (la->la_flags & LLE_STATIC) { 609 log(LOG_ERR, 610 "arp: %*D attempts to modify permanent " 611 "entry for %s on %s\n", 612 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 613 inet_ntoa(isaddr), ifp->if_xname); 614 goto reply; 615 } 616 if (log_arp_movements) { 617 log(LOG_INFO, "arp: %s moved from %*D " 618 "to %*D on %s\n", 619 inet_ntoa(isaddr), 620 ifp->if_addrlen, 621 (u_char *)&la->ll_addr, ":", 622 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 623 ifp->if_xname); 624 } 625 } 626 627 if (ifp->if_addrlen != ah->ar_hln) { 628 log(LOG_WARNING, 629 "arp from %*D: addr len: new %d, i/f %d (ignored)", 630 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 631 ah->ar_hln, ifp->if_addrlen); 632 goto reply; 633 } 634 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 635 la->la_flags |= LLE_VALID; 636 637 if (!(la->la_flags & LLE_STATIC)) { 638 la->la_expire = time_uptime + V_arpt_keep; 639 callout_reset(&la->la_timer, hz * V_arpt_keep, 640 arptimer, la); 641 } 642 la->la_asked = 0; 643 la->la_preempt = V_arp_maxtries; 644 if (la->la_hold != NULL) { 645 m0 = la->la_hold; 646 la->la_hold = 0; 647 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 648 LLE_WUNLOCK(la); 649 650 (*ifp->if_output)(ifp, m0, &sa, NULL); 651 return; 652 } 653 } 654 reply: 655 if (op != ARPOP_REQUEST) 656 goto drop; 657 658 if (itaddr.s_addr == myaddr.s_addr) { 659 /* Shortcut.. the receiving interface is the target. */ 660 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 661 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 662 } else { 663 struct llentry *lle = NULL; 664 665 if (!V_arp_proxyall) 666 goto drop; 667 668 sin.sin_addr = itaddr; 669 /* XXX MRT use table 0 for arp reply */ 670 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 671 if (!rt) 672 goto drop; 673 674 /* 675 * Don't send proxies for nodes on the same interface 676 * as this one came out of, or we'll get into a fight 677 * over who claims what Ether address. 678 */ 679 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 680 RTFREE_LOCKED(rt); 681 goto drop; 682 } 683 IF_AFDATA_LOCK(rt->rt_ifp); 684 lle = lla_lookup(LLTABLE(rt->rt_ifp), 0, (struct sockaddr *)&sin); 685 IF_AFDATA_UNLOCK(rt->rt_ifp); 686 RTFREE_LOCKED(rt); 687 688 if (lle != NULL) { 689 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 690 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 691 LLE_RUNLOCK(lle); 692 } else 693 goto drop; 694 695 /* 696 * Also check that the node which sent the ARP packet 697 * is on the the interface we expect it to be on. This 698 * avoids ARP chaos if an interface is connected to the 699 * wrong network. 700 */ 701 sin.sin_addr = isaddr; 702 703 /* XXX MRT use table 0 for arp checks */ 704 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 705 if (!rt) 706 goto drop; 707 if (rt->rt_ifp != ifp) { 708 log(LOG_INFO, "arp_proxy: ignoring request" 709 " from %s via %s, expecting %s\n", 710 inet_ntoa(isaddr), ifp->if_xname, 711 rt->rt_ifp->if_xname); 712 RTFREE_LOCKED(rt); 713 goto drop; 714 } 715 RTFREE_LOCKED(rt); 716 717 #ifdef DEBUG_PROXY 718 printf("arp: proxying for %s\n", 719 inet_ntoa(itaddr)); 720 #endif 721 } 722 723 if (la != NULL) 724 LLE_WUNLOCK(la); 725 if (itaddr.s_addr == myaddr.s_addr && 726 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 727 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 728 #ifdef DEBUG_LINKLOCAL 729 printf("arp: sending reply for link-local addr %s\n", 730 inet_ntoa(itaddr)); 731 #endif 732 m->m_flags |= M_BCAST; 733 m->m_flags &= ~M_MCAST; 734 } else { 735 /* default behaviour; never reply by broadcast. */ 736 m->m_flags &= ~(M_BCAST|M_MCAST); 737 } 738 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 739 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 740 ah->ar_op = htons(ARPOP_REPLY); 741 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 742 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 743 m->m_pkthdr.len = m->m_len; 744 sa.sa_family = AF_ARP; 745 sa.sa_len = 2; 746 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 747 return; 748 749 drop: 750 if (la != NULL) 751 LLE_WUNLOCK(la); 752 m_freem(m); 753 } 754 #endif 755 756 void 757 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 758 { 759 struct llentry *lle; 760 761 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 762 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 763 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 764 /* 765 * interface address is considered static entry 766 * because the output of the arp utility shows 767 * that L2 entry as permanent 768 */ 769 IF_AFDATA_LOCK(ifp); 770 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 771 (struct sockaddr *)IA_SIN(ifa)); 772 IF_AFDATA_UNLOCK(ifp); 773 if (lle == NULL) 774 log(LOG_INFO, "arp_ifinit: cannot create arp " 775 "entry for interface address\n"); 776 else 777 LLE_RUNLOCK(lle); 778 } 779 ifa->ifa_rtrequest = NULL; 780 } 781 782 void 783 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 784 { 785 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 786 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 787 &IA_SIN(ifa)->sin_addr, enaddr); 788 ifa->ifa_rtrequest = NULL; 789 } 790 791 static void 792 arp_init(void) 793 { 794 INIT_VNET_INET(curvnet); 795 796 V_arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 797 V_arp_maxtries = 5; 798 V_useloopback = 1; /* use loopback interface for local traffic */ 799 V_arp_proxyall = 0; 800 801 arpintrq.ifq_maxlen = 50; 802 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 803 netisr_register(NETISR_ARP, arpintr, &arpintrq, 0); 804 } 805 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 806