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_route.h" 43 #include "opt_mac.h" 44 #include "opt_carp.h" 45 46 #include <sys/param.h> 47 #include <sys/kernel.h> 48 #include <sys/queue.h> 49 #include <sys/sysctl.h> 50 #include <sys/systm.h> 51 #include <sys/mbuf.h> 52 #include <sys/malloc.h> 53 #include <sys/proc.h> 54 #include <sys/socket.h> 55 #include <sys/syslog.h> 56 #include <sys/vimage.h> 57 58 #include <net/if.h> 59 #include <net/if_dl.h> 60 #include <net/if_types.h> 61 #include <net/route.h> 62 #include <net/netisr.h> 63 #include <net/if_llc.h> 64 #include <net/ethernet.h> 65 #include <net/vnet.h> 66 67 #include <netinet/in.h> 68 #include <netinet/in_var.h> 69 #include <net/if_llatbl.h> 70 #include <netinet/if_ether.h> 71 #include <netinet/vinet.h> 72 73 #include <net/if_arc.h> 74 #include <net/iso88025.h> 75 76 #ifdef DEV_CARP 77 #include <netinet/ip_carp.h> 78 #endif 79 80 #include <security/mac/mac_framework.h> 81 82 #define SIN(s) ((struct sockaddr_in *)s) 83 #define SDL(s) ((struct sockaddr_dl *)s) 84 #define LLTABLE(ifp) ((struct lltable *)(ifp)->if_afdata[AF_INET]) 85 86 SYSCTL_DECL(_net_link_ether); 87 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 88 89 /* timer values */ 90 #ifdef VIMAGE_GLOBALS 91 static int arpt_keep; /* once resolved, good for 20 more minutes */ 92 static int arp_maxtries; 93 int useloopback; /* use loopback interface for local traffic */ 94 static int arp_proxyall; 95 #endif 96 97 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, max_age, 98 CTLFLAG_RW, arpt_keep, 0, "ARP entry lifetime in seconds"); 99 100 static struct ifqueue arpintrq; 101 102 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, maxtries, 103 CTLFLAG_RW, arp_maxtries, 0, 104 "ARP resolution attempts before returning error"); 105 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, useloopback, 106 CTLFLAG_RW, useloopback, 0, 107 "Use the loopback interface for local traffic"); 108 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, proxyall, 109 CTLFLAG_RW, arp_proxyall, 0, 110 "Enable proxy ARP for all suitable requests"); 111 112 static void arp_init(void); 113 void arprequest(struct ifnet *, 114 struct in_addr *, struct in_addr *, u_char *); 115 static void arpintr(struct mbuf *); 116 static void arptimer(void *); 117 #ifdef INET 118 static void in_arpinput(struct mbuf *); 119 #endif 120 121 #ifdef AF_INET 122 void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 123 124 /* 125 * called by in_ifscrub to remove entry from the table when 126 * the interface goes away 127 */ 128 void 129 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 130 { 131 struct sockaddr_in addr4; 132 133 bzero((void *)&addr4, sizeof(addr4)); 134 addr4.sin_len = sizeof(addr4); 135 addr4.sin_family = AF_INET; 136 addr4.sin_addr.s_addr = addr; 137 IF_AFDATA_LOCK(ifp); 138 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 139 (struct sockaddr *)&addr4); 140 IF_AFDATA_UNLOCK(ifp); 141 } 142 #endif 143 144 /* 145 * Timeout routine. Age arp_tab entries periodically. 146 */ 147 static void 148 arptimer(void *arg) 149 { 150 struct ifnet *ifp; 151 struct llentry *lle = (struct llentry *)arg; 152 153 if (lle == NULL) { 154 panic("%s: NULL entry!\n", __func__); 155 return; 156 } 157 ifp = lle->lle_tbl->llt_ifp; 158 IF_AFDATA_LOCK(ifp); 159 LLE_WLOCK(lle); 160 if (((lle->la_flags & LLE_DELETED) 161 || (time_second >= lle->la_expire)) 162 && (!callout_pending(&lle->la_timer) && 163 callout_active(&lle->la_timer))) 164 (void) llentry_free(lle); 165 else { 166 /* 167 * Still valid, just drop our reference 168 */ 169 LLE_FREE_LOCKED(lle); 170 } 171 IF_AFDATA_UNLOCK(ifp); 172 } 173 174 /* 175 * Broadcast an ARP request. Caller specifies: 176 * - arp header source ip address 177 * - arp header target ip address 178 * - arp header source ethernet address 179 */ 180 void 181 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 182 u_char *enaddr) 183 { 184 struct mbuf *m; 185 struct arphdr *ah; 186 struct sockaddr sa; 187 188 if (sip == NULL) { 189 /* XXX don't believe this can happen (or explain why) */ 190 /* 191 * The caller did not supply a source address, try to find 192 * a compatible one among those assigned to this interface. 193 */ 194 struct ifaddr *ifa; 195 196 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 197 if (!ifa->ifa_addr || 198 ifa->ifa_addr->sa_family != AF_INET) 199 continue; 200 sip = &SIN(ifa->ifa_addr)->sin_addr; 201 if (0 == ((sip->s_addr ^ tip->s_addr) & 202 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 203 break; /* found it. */ 204 } 205 if (sip == NULL) { 206 printf("%s: cannot find matching address\n", __func__); 207 return; 208 } 209 } 210 211 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 212 return; 213 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 214 2*ifp->if_data.ifi_addrlen; 215 m->m_pkthdr.len = m->m_len; 216 MH_ALIGN(m, m->m_len); 217 ah = mtod(m, struct arphdr *); 218 bzero((caddr_t)ah, m->m_len); 219 #ifdef MAC 220 mac_netinet_arp_send(ifp, m); 221 #endif 222 ah->ar_pro = htons(ETHERTYPE_IP); 223 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 224 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 225 ah->ar_op = htons(ARPOP_REQUEST); 226 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 227 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 228 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 229 sa.sa_family = AF_ARP; 230 sa.sa_len = 2; 231 m->m_flags |= M_BCAST; 232 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 233 } 234 235 /* 236 * Resolve an IP address into an ethernet address. 237 * On input: 238 * ifp is the interface we use 239 * rt0 is the route to the final destination (possibly useless) 240 * m is the mbuf. May be NULL if we don't have a packet. 241 * dst is the next hop, 242 * desten is where we want the address. 243 * 244 * On success, desten is filled in and the function returns 0; 245 * If the packet must be held pending resolution, we return EWOULDBLOCK 246 * On other errors, we return the corresponding error code. 247 * Note that m_freem() handles NULL. 248 */ 249 int 250 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 251 struct sockaddr *dst, u_char *desten, struct llentry **lle) 252 { 253 INIT_VNET_INET(ifp->if_vnet); 254 struct llentry *la = 0; 255 u_int flags = 0; 256 int error, renew; 257 258 *lle = NULL; 259 if (m != NULL) { 260 if (m->m_flags & M_BCAST) { 261 /* broadcast */ 262 (void)memcpy(desten, 263 ifp->if_broadcastaddr, ifp->if_addrlen); 264 return (0); 265 } 266 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 267 /* multicast */ 268 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 269 return (0); 270 } 271 } 272 /* XXXXX 273 */ 274 retry: 275 IF_AFDATA_RLOCK(ifp); 276 la = lla_lookup(LLTABLE(ifp), flags, dst); 277 IF_AFDATA_RUNLOCK(ifp); 278 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 279 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 280 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 281 IF_AFDATA_WLOCK(ifp); 282 la = lla_lookup(LLTABLE(ifp), flags, dst); 283 IF_AFDATA_WUNLOCK(ifp); 284 } 285 if (la == NULL) { 286 if (flags & LLE_CREATE) 287 log(LOG_DEBUG, 288 "arpresolve: can't allocate llinfo for %s\n", 289 inet_ntoa(SIN(dst)->sin_addr)); 290 m_freem(m); 291 return (EINVAL); 292 } 293 294 if ((la->la_flags & LLE_VALID) && 295 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 296 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 297 /* 298 * If entry has an expiry time and it is approaching, 299 * see if we need to send an ARP request within this 300 * arpt_down interval. 301 */ 302 if (!(la->la_flags & LLE_STATIC) && 303 time_uptime + la->la_preempt > la->la_expire) { 304 arprequest(ifp, NULL, 305 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 306 307 la->la_preempt--; 308 } 309 310 *lle = la; 311 error = 0; 312 goto done; 313 } 314 315 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 316 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 317 inet_ntoa(SIN(dst)->sin_addr)); 318 m_freem(m); 319 error = EINVAL; 320 goto done; 321 } 322 323 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 324 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 325 flags |= LLE_EXCLUSIVE; 326 LLE_RUNLOCK(la); 327 goto retry; 328 } 329 /* 330 * There is an arptab entry, but no ethernet address 331 * response yet. Replace the held mbuf with this 332 * latest one. 333 */ 334 if (m != NULL) { 335 if (la->la_hold != NULL) 336 m_freem(la->la_hold); 337 la->la_hold = m; 338 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 339 flags &= ~LLE_EXCLUSIVE; 340 LLE_DOWNGRADE(la); 341 } 342 343 } 344 /* 345 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 346 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 347 * if we have already sent arp_maxtries ARP requests. Retransmit the 348 * ARP request, but not faster than one request per second. 349 */ 350 if (la->la_asked < V_arp_maxtries) 351 error = EWOULDBLOCK; /* First request. */ 352 else 353 error = 354 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH; 355 356 if (renew) { 357 LLE_ADDREF(la); 358 la->la_expire = time_uptime; 359 callout_reset(&la->la_timer, hz, arptimer, la); 360 la->la_asked++; 361 LLE_WUNLOCK(la); 362 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 363 IF_LLADDR(ifp)); 364 return (error); 365 } 366 done: 367 if (flags & LLE_EXCLUSIVE) 368 LLE_WUNLOCK(la); 369 else 370 LLE_RUNLOCK(la); 371 return (error); 372 } 373 374 /* 375 * Common length and type checks are done here, 376 * then the protocol-specific routine is called. 377 */ 378 static void 379 arpintr(struct mbuf *m) 380 { 381 struct arphdr *ar; 382 383 if (m->m_len < sizeof(struct arphdr) && 384 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 385 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 386 return; 387 } 388 ar = mtod(m, struct arphdr *); 389 390 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 391 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 392 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 393 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 394 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 395 (unsigned char *)&ar->ar_hrd, ""); 396 m_freem(m); 397 return; 398 } 399 400 if (m->m_len < arphdr_len(ar)) { 401 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 402 log(LOG_ERR, "arp: runt packet\n"); 403 m_freem(m); 404 return; 405 } 406 ar = mtod(m, struct arphdr *); 407 } 408 409 switch (ntohs(ar->ar_pro)) { 410 #ifdef INET 411 case ETHERTYPE_IP: 412 in_arpinput(m); 413 return; 414 #endif 415 } 416 m_freem(m); 417 } 418 419 #ifdef INET 420 /* 421 * ARP for Internet protocols on 10 Mb/s Ethernet. 422 * Algorithm is that given in RFC 826. 423 * In addition, a sanity check is performed on the sender 424 * protocol address, to catch impersonators. 425 * We no longer handle negotiations for use of trailer protocol: 426 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 427 * along with IP replies if we wanted trailers sent to us, 428 * and also sent them in response to IP replies. 429 * This allowed either end to announce the desire to receive 430 * trailer packets. 431 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 432 * but formerly didn't normally send requests. 433 */ 434 static int log_arp_wrong_iface = 1; 435 static int log_arp_movements = 1; 436 static int log_arp_permanent_modify = 1; 437 438 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 439 &log_arp_wrong_iface, 0, 440 "log arp packets arriving on the wrong interface"); 441 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 442 &log_arp_movements, 0, 443 "log arp replies from MACs different than the one in the cache"); 444 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 445 &log_arp_permanent_modify, 0, 446 "log arp replies from MACs different than the one in the permanent arp entry"); 447 448 449 static void 450 in_arpinput(struct mbuf *m) 451 { 452 struct arphdr *ah; 453 struct ifnet *ifp = m->m_pkthdr.rcvif; 454 struct llentry *la = NULL; 455 struct rtentry *rt; 456 struct ifaddr *ifa; 457 struct in_ifaddr *ia; 458 struct sockaddr sa; 459 struct in_addr isaddr, itaddr, myaddr; 460 u_int8_t *enaddr = NULL; 461 int op, flags; 462 struct mbuf *m0; 463 int req_len; 464 int bridged = 0, is_bridge = 0; 465 #ifdef DEV_CARP 466 int carp_match = 0; 467 #endif 468 struct sockaddr_in sin; 469 sin.sin_len = sizeof(struct sockaddr_in); 470 sin.sin_family = AF_INET; 471 sin.sin_addr.s_addr = 0; 472 INIT_VNET_INET(ifp->if_vnet); 473 474 if (ifp->if_bridge) 475 bridged = 1; 476 if (ifp->if_type == IFT_BRIDGE) 477 is_bridge = 1; 478 479 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 480 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 481 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 482 return; 483 } 484 485 ah = mtod(m, struct arphdr *); 486 op = ntohs(ah->ar_op); 487 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 488 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 489 490 /* 491 * For a bridge, we want to check the address irrespective 492 * of the receive interface. (This will change slightly 493 * when we have clusters of interfaces). 494 * If the interface does not match, but the recieving interface 495 * is part of carp, we call carp_iamatch to see if this is a 496 * request for the virtual host ip. 497 * XXX: This is really ugly! 498 */ 499 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 500 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 501 ia->ia_ifp == ifp) && 502 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 503 goto match; 504 #ifdef DEV_CARP 505 if (ifp->if_carp != NULL && 506 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 507 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 508 carp_match = 1; 509 goto match; 510 } 511 #endif 512 } 513 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 514 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 515 ia->ia_ifp == ifp) && 516 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 517 goto match; 518 519 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 520 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 521 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 522 addr == ia->ia_addr.sin_addr.s_addr) 523 /* 524 * Check the case when bridge shares its MAC address with 525 * some of its children, so packets are claimed by bridge 526 * itself (bridge_input() does it first), but they are really 527 * meant to be destined to the bridge member. 528 */ 529 if (is_bridge) { 530 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 531 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 532 ifp = ia->ia_ifp; 533 goto match; 534 } 535 } 536 } 537 #undef BDG_MEMBER_MATCHES_ARP 538 539 /* 540 * No match, use the first inet address on the receive interface 541 * as a dummy address for the rest of the function. 542 */ 543 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 544 if (ifa->ifa_addr->sa_family == AF_INET) { 545 ia = ifatoia(ifa); 546 goto match; 547 } 548 /* 549 * If bridging, fall back to using any inet address. 550 */ 551 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 552 goto drop; 553 match: 554 if (!enaddr) 555 enaddr = (u_int8_t *)IF_LLADDR(ifp); 556 myaddr = ia->ia_addr.sin_addr; 557 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 558 goto drop; /* it's from me, ignore it. */ 559 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 560 log(LOG_ERR, 561 "arp: link address is broadcast for IP address %s!\n", 562 inet_ntoa(isaddr)); 563 goto drop; 564 } 565 /* 566 * Warn if another host is using the same IP address, but only if the 567 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 568 * case we suppress the warning to avoid false positive complaints of 569 * potential misconfiguration. 570 */ 571 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 572 log(LOG_ERR, 573 "arp: %*D is using my IP address %s on %s!\n", 574 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 575 inet_ntoa(isaddr), ifp->if_xname); 576 itaddr = myaddr; 577 goto reply; 578 } 579 if (ifp->if_flags & IFF_STATICARP) 580 goto reply; 581 582 bzero(&sin, sizeof(sin)); 583 sin.sin_len = sizeof(struct sockaddr_in); 584 sin.sin_family = AF_INET; 585 sin.sin_addr = isaddr; 586 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 587 flags |= LLE_EXCLUSIVE; 588 IF_AFDATA_LOCK(ifp); 589 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 590 IF_AFDATA_UNLOCK(ifp); 591 if (la != NULL) { 592 /* the following is not an error when doing bridging */ 593 if (!bridged && la->lle_tbl->llt_ifp != ifp 594 #ifdef DEV_CARP 595 && (ifp->if_type != IFT_CARP || !carp_match) 596 #endif 597 ) { 598 if (log_arp_wrong_iface) 599 log(LOG_ERR, "arp: %s is on %s " 600 "but got reply from %*D on %s\n", 601 inet_ntoa(isaddr), 602 la->lle_tbl->llt_ifp->if_xname, 603 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 604 ifp->if_xname); 605 goto reply; 606 } 607 if ((la->la_flags & LLE_VALID) && 608 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 609 if (la->la_flags & LLE_STATIC) { 610 log(LOG_ERR, 611 "arp: %*D attempts to modify permanent " 612 "entry for %s on %s\n", 613 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 614 inet_ntoa(isaddr), ifp->if_xname); 615 goto reply; 616 } 617 if (log_arp_movements) { 618 log(LOG_INFO, "arp: %s moved from %*D " 619 "to %*D on %s\n", 620 inet_ntoa(isaddr), 621 ifp->if_addrlen, 622 (u_char *)&la->ll_addr, ":", 623 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 624 ifp->if_xname); 625 } 626 } 627 628 if (ifp->if_addrlen != ah->ar_hln) { 629 log(LOG_WARNING, 630 "arp from %*D: addr len: new %d, i/f %d (ignored)", 631 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 632 ah->ar_hln, ifp->if_addrlen); 633 goto reply; 634 } 635 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 636 la->la_flags |= LLE_VALID; 637 638 if (!(la->la_flags & LLE_STATIC)) { 639 la->la_expire = time_uptime + V_arpt_keep; 640 callout_reset(&la->la_timer, hz * V_arpt_keep, 641 arptimer, la); 642 } 643 la->la_asked = 0; 644 la->la_preempt = V_arp_maxtries; 645 if (la->la_hold != NULL) { 646 m0 = la->la_hold; 647 la->la_hold = 0; 648 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 649 LLE_WUNLOCK(la); 650 651 (*ifp->if_output)(ifp, m0, &sa, NULL); 652 return; 653 } 654 } 655 reply: 656 if (op != ARPOP_REQUEST) 657 goto drop; 658 659 if (itaddr.s_addr == myaddr.s_addr) { 660 /* Shortcut.. the receiving interface is the target. */ 661 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 662 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 663 } else { 664 struct llentry *lle = NULL; 665 666 if (!V_arp_proxyall) 667 goto drop; 668 669 sin.sin_addr = itaddr; 670 /* XXX MRT use table 0 for arp reply */ 671 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 672 if (!rt) 673 goto drop; 674 675 /* 676 * Don't send proxies for nodes on the same interface 677 * as this one came out of, or we'll get into a fight 678 * over who claims what Ether address. 679 */ 680 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 681 RTFREE_LOCKED(rt); 682 goto drop; 683 } 684 IF_AFDATA_LOCK(rt->rt_ifp); 685 lle = lla_lookup(LLTABLE(rt->rt_ifp), 0, (struct sockaddr *)&sin); 686 IF_AFDATA_UNLOCK(rt->rt_ifp); 687 RTFREE_LOCKED(rt); 688 689 if (lle != NULL) { 690 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 691 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 692 LLE_RUNLOCK(lle); 693 } else 694 goto drop; 695 696 /* 697 * Also check that the node which sent the ARP packet 698 * is on the the interface we expect it to be on. This 699 * avoids ARP chaos if an interface is connected to the 700 * wrong network. 701 */ 702 sin.sin_addr = isaddr; 703 704 /* XXX MRT use table 0 for arp checks */ 705 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 706 if (!rt) 707 goto drop; 708 if (rt->rt_ifp != ifp) { 709 log(LOG_INFO, "arp_proxy: ignoring request" 710 " from %s via %s, expecting %s\n", 711 inet_ntoa(isaddr), ifp->if_xname, 712 rt->rt_ifp->if_xname); 713 RTFREE_LOCKED(rt); 714 goto drop; 715 } 716 RTFREE_LOCKED(rt); 717 718 #ifdef DEBUG_PROXY 719 printf("arp: proxying for %s\n", 720 inet_ntoa(itaddr)); 721 #endif 722 } 723 724 if (la != NULL) 725 LLE_WUNLOCK(la); 726 if (itaddr.s_addr == myaddr.s_addr && 727 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 728 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 729 #ifdef DEBUG_LINKLOCAL 730 printf("arp: sending reply for link-local addr %s\n", 731 inet_ntoa(itaddr)); 732 #endif 733 m->m_flags |= M_BCAST; 734 m->m_flags &= ~M_MCAST; 735 } else { 736 /* default behaviour; never reply by broadcast. */ 737 m->m_flags &= ~(M_BCAST|M_MCAST); 738 } 739 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 740 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 741 ah->ar_op = htons(ARPOP_REPLY); 742 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 743 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 744 m->m_pkthdr.len = m->m_len; 745 sa.sa_family = AF_ARP; 746 sa.sa_len = 2; 747 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 748 return; 749 750 drop: 751 if (la != NULL) 752 LLE_WUNLOCK(la); 753 m_freem(m); 754 } 755 #endif 756 757 void 758 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 759 { 760 struct llentry *lle; 761 762 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 763 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 764 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 765 /* 766 * interface address is considered static entry 767 * because the output of the arp utility shows 768 * that L2 entry as permanent 769 */ 770 IF_AFDATA_LOCK(ifp); 771 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 772 (struct sockaddr *)IA_SIN(ifa)); 773 IF_AFDATA_UNLOCK(ifp); 774 if (lle == NULL) 775 log(LOG_INFO, "arp_ifinit: cannot create arp " 776 "entry for interface address\n"); 777 else 778 LLE_RUNLOCK(lle); 779 } 780 ifa->ifa_rtrequest = NULL; 781 } 782 783 void 784 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 785 { 786 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 787 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 788 &IA_SIN(ifa)->sin_addr, enaddr); 789 ifa->ifa_rtrequest = NULL; 790 } 791 792 static void 793 arp_init(void) 794 { 795 INIT_VNET_INET(curvnet); 796 797 V_arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 798 V_arp_maxtries = 5; 799 V_useloopback = 1; /* use loopback interface for local traffic */ 800 V_arp_proxyall = 0; 801 802 arpintrq.ifq_maxlen = 50; 803 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 804 netisr_register(NETISR_ARP, arpintr, &arpintrq, 0); 805 } 806 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 807