if_ether.c revision 207369
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: head/sys/netinet/if_ether.c 207369 2010-04-29 11:52:42Z bz $"); 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 55#include <net/if.h> 56#include <net/if_dl.h> 57#include <net/if_types.h> 58#include <net/netisr.h> 59#include <net/if_llc.h> 60#include <net/ethernet.h> 61#include <net/route.h> 62#include <net/vnet.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 69#include <net/if_arc.h> 70#include <net/iso88025.h> 71 72#ifdef DEV_CARP 73#include <netinet/ip_carp.h> 74#endif 75 76#include <security/mac/mac_framework.h> 77 78#define SIN(s) ((struct sockaddr_in *)s) 79#define SDL(s) ((struct sockaddr_dl *)s) 80 81SYSCTL_DECL(_net_link_ether); 82SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 83SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 84 85/* timer values */ 86static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 87 * minutes */ 88static VNET_DEFINE(int, arp_maxtries) = 5; 89VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for 90 * local traffic */ 91static VNET_DEFINE(int, arp_proxyall) = 0; 92static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 93 * 20 seconds */ 94static VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 95 96#define V_arpt_keep VNET(arpt_keep) 97#define V_arpt_down VNET(arpt_down) 98#define V_arp_maxtries VNET(arp_maxtries) 99#define V_arp_proxyall VNET(arp_proxyall) 100#define V_arpstat VNET(arpstat) 101 102SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 103 &VNET_NAME(arpt_keep), 0, 104 "ARP entry lifetime in seconds"); 105SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 106 &VNET_NAME(arp_maxtries), 0, 107 "ARP resolution attempts before returning error"); 108SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 109 &VNET_NAME(useloopback), 0, 110 "Use the loopback interface for local traffic"); 111SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 112 &VNET_NAME(arp_proxyall), 0, 113 "Enable proxy ARP for all suitable requests"); 114SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW, 115 &VNET_NAME(arpstat), arpstat, 116 "ARP statistics (struct arpstat, net/if_arp.h)"); 117 118static void arp_init(void); 119void arprequest(struct ifnet *, 120 struct in_addr *, struct in_addr *, u_char *); 121static void arpintr(struct mbuf *); 122static void arptimer(void *); 123#ifdef INET 124static void in_arpinput(struct mbuf *); 125#endif 126 127static const struct netisr_handler arp_nh = { 128 .nh_name = "arp", 129 .nh_handler = arpintr, 130 .nh_proto = NETISR_ARP, 131 .nh_policy = NETISR_POLICY_SOURCE, 132}; 133 134#ifdef AF_INET 135void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 136 137/* 138 * called by in_ifscrub to remove entry from the table when 139 * the interface goes away 140 */ 141void 142arp_ifscrub(struct ifnet *ifp, uint32_t addr) 143{ 144 struct sockaddr_in addr4; 145 146 bzero((void *)&addr4, sizeof(addr4)); 147 addr4.sin_len = sizeof(addr4); 148 addr4.sin_family = AF_INET; 149 addr4.sin_addr.s_addr = addr; 150 CURVNET_SET(ifp->if_vnet); 151 IF_AFDATA_LOCK(ifp); 152 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 153 (struct sockaddr *)&addr4); 154 IF_AFDATA_UNLOCK(ifp); 155 CURVNET_RESTORE(); 156} 157#endif 158 159/* 160 * Timeout routine. Age arp_tab entries periodically. 161 */ 162static void 163arptimer(void *arg) 164{ 165 struct ifnet *ifp; 166 struct llentry *lle = (struct llentry *)arg; 167 168 if (lle == NULL) { 169 panic("%s: NULL entry!\n", __func__); 170 return; 171 } 172 ifp = lle->lle_tbl->llt_ifp; 173 CURVNET_SET(ifp->if_vnet); 174 IF_AFDATA_LOCK(ifp); 175 LLE_WLOCK(lle); 176 if (lle->la_flags & LLE_STATIC) 177 LLE_WUNLOCK(lle); 178 else { 179 if (!callout_pending(&lle->la_timer) && 180 callout_active(&lle->la_timer)) { 181 callout_stop(&lle->la_timer); 182 LLE_REMREF(lle); 183 (void) llentry_free(lle); 184 ARPSTAT_INC(timeouts); 185 } 186#ifdef DIAGNOSTIC 187 else { 188 struct sockaddr *l3addr = L3_ADDR(lle); 189 log(LOG_INFO, 190 "arptimer issue: %p, IPv4 address: \"%s\"\n", lle, 191 inet_ntoa( 192 ((const struct sockaddr_in *)l3addr)->sin_addr)); 193 } 194#endif 195 } 196 IF_AFDATA_UNLOCK(ifp); 197 CURVNET_RESTORE(); 198} 199 200/* 201 * Broadcast an ARP request. Caller specifies: 202 * - arp header source ip address 203 * - arp header target ip address 204 * - arp header source ethernet address 205 */ 206void 207arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 208 u_char *enaddr) 209{ 210 struct mbuf *m; 211 struct arphdr *ah; 212 struct sockaddr sa; 213 214 if (sip == NULL) { 215 /* XXX don't believe this can happen (or explain why) */ 216 /* 217 * The caller did not supply a source address, try to find 218 * a compatible one among those assigned to this interface. 219 */ 220 struct ifaddr *ifa; 221 222 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 223 if (!ifa->ifa_addr || 224 ifa->ifa_addr->sa_family != AF_INET) 225 continue; 226 sip = &SIN(ifa->ifa_addr)->sin_addr; 227 if (0 == ((sip->s_addr ^ tip->s_addr) & 228 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 229 break; /* found it. */ 230 } 231 if (sip == NULL) { 232 printf("%s: cannot find matching address\n", __func__); 233 return; 234 } 235 } 236 237 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 238 return; 239 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 240 2*ifp->if_data.ifi_addrlen; 241 m->m_pkthdr.len = m->m_len; 242 MH_ALIGN(m, m->m_len); 243 ah = mtod(m, struct arphdr *); 244 bzero((caddr_t)ah, m->m_len); 245#ifdef MAC 246 mac_netinet_arp_send(ifp, m); 247#endif 248 ah->ar_pro = htons(ETHERTYPE_IP); 249 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 250 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 251 ah->ar_op = htons(ARPOP_REQUEST); 252 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 253 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 254 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 255 sa.sa_family = AF_ARP; 256 sa.sa_len = 2; 257 m->m_flags |= M_BCAST; 258 (*ifp->if_output)(ifp, m, &sa, NULL); 259 ARPSTAT_INC(txrequests); 260} 261 262/* 263 * Resolve an IP address into an ethernet address. 264 * On input: 265 * ifp is the interface we use 266 * rt0 is the route to the final destination (possibly useless) 267 * m is the mbuf. May be NULL if we don't have a packet. 268 * dst is the next hop, 269 * desten is where we want the address. 270 * 271 * On success, desten is filled in and the function returns 0; 272 * If the packet must be held pending resolution, we return EWOULDBLOCK 273 * On other errors, we return the corresponding error code. 274 * Note that m_freem() handles NULL. 275 */ 276int 277arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 278 struct sockaddr *dst, u_char *desten, struct llentry **lle) 279{ 280 struct llentry *la = 0; 281 u_int flags = 0; 282 int error, renew; 283 284 *lle = NULL; 285 if (m != NULL) { 286 if (m->m_flags & M_BCAST) { 287 /* broadcast */ 288 (void)memcpy(desten, 289 ifp->if_broadcastaddr, ifp->if_addrlen); 290 return (0); 291 } 292 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 293 /* multicast */ 294 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 295 return (0); 296 } 297 } 298 /* XXXXX 299 */ 300retry: 301 IF_AFDATA_RLOCK(ifp); 302 la = lla_lookup(LLTABLE(ifp), flags, dst); 303 IF_AFDATA_RUNLOCK(ifp); 304 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 305 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 306 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 307 IF_AFDATA_WLOCK(ifp); 308 la = lla_lookup(LLTABLE(ifp), flags, dst); 309 IF_AFDATA_WUNLOCK(ifp); 310 } 311 if (la == NULL) { 312 if (flags & LLE_CREATE) 313 log(LOG_DEBUG, 314 "arpresolve: can't allocate llinfo for %s\n", 315 inet_ntoa(SIN(dst)->sin_addr)); 316 m_freem(m); 317 return (EINVAL); 318 } 319 320 if ((la->la_flags & LLE_VALID) && 321 ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) { 322 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 323 /* 324 * If entry has an expiry time and it is approaching, 325 * see if we need to send an ARP request within this 326 * arpt_down interval. 327 */ 328 if (!(la->la_flags & LLE_STATIC) && 329 time_second + la->la_preempt > la->la_expire) { 330 arprequest(ifp, NULL, 331 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 332 333 la->la_preempt--; 334 } 335 336 *lle = la; 337 error = 0; 338 goto done; 339 } 340 341 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 342 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 343 inet_ntoa(SIN(dst)->sin_addr)); 344 m_freem(m); 345 error = EINVAL; 346 goto done; 347 } 348 349 renew = (la->la_asked == 0 || la->la_expire != time_second); 350 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 351 flags |= LLE_EXCLUSIVE; 352 LLE_RUNLOCK(la); 353 goto retry; 354 } 355 /* 356 * There is an arptab entry, but no ethernet address 357 * response yet. Replace the held mbuf with this 358 * latest one. 359 */ 360 if (m != NULL) { 361 if (la->la_hold != NULL) { 362 m_freem(la->la_hold); 363 ARPSTAT_INC(dropped); 364 } 365 la->la_hold = m; 366 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 367 flags &= ~LLE_EXCLUSIVE; 368 LLE_DOWNGRADE(la); 369 } 370 371 } 372 /* 373 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 374 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 375 * if we have already sent arp_maxtries ARP requests. Retransmit the 376 * ARP request, but not faster than one request per second. 377 */ 378 if (la->la_asked < V_arp_maxtries) 379 error = EWOULDBLOCK; /* First request. */ 380 else 381 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ? 382 EHOSTUNREACH : EHOSTDOWN; 383 384 if (renew) { 385 int canceled; 386 387 LLE_ADDREF(la); 388 la->la_expire = time_second + V_arpt_down; 389 canceled = callout_reset(&la->la_timer, hz * V_arpt_down, 390 arptimer, la); 391 if (canceled) 392 LLE_REMREF(la); 393 la->la_asked++; 394 LLE_WUNLOCK(la); 395 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 396 IF_LLADDR(ifp)); 397 return (error); 398 } 399done: 400 if (flags & LLE_EXCLUSIVE) 401 LLE_WUNLOCK(la); 402 else 403 LLE_RUNLOCK(la); 404 return (error); 405} 406 407/* 408 * Common length and type checks are done here, 409 * then the protocol-specific routine is called. 410 */ 411static void 412arpintr(struct mbuf *m) 413{ 414 struct arphdr *ar; 415 416 if (m->m_len < sizeof(struct arphdr) && 417 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 418 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 419 return; 420 } 421 ar = mtod(m, struct arphdr *); 422 423 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 424 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 425 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 426 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 427 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 428 (unsigned char *)&ar->ar_hrd, ""); 429 m_freem(m); 430 return; 431 } 432 433 if (m->m_len < arphdr_len(ar)) { 434 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 435 log(LOG_ERR, "arp: runt packet\n"); 436 m_freem(m); 437 return; 438 } 439 ar = mtod(m, struct arphdr *); 440 } 441 442 ARPSTAT_INC(received); 443 switch (ntohs(ar->ar_pro)) { 444#ifdef INET 445 case ETHERTYPE_IP: 446 in_arpinput(m); 447 return; 448#endif 449 } 450 m_freem(m); 451} 452 453#ifdef INET 454/* 455 * ARP for Internet protocols on 10 Mb/s Ethernet. 456 * Algorithm is that given in RFC 826. 457 * In addition, a sanity check is performed on the sender 458 * protocol address, to catch impersonators. 459 * We no longer handle negotiations for use of trailer protocol: 460 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 461 * along with IP replies if we wanted trailers sent to us, 462 * and also sent them in response to IP replies. 463 * This allowed either end to announce the desire to receive 464 * trailer packets. 465 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 466 * but formerly didn't normally send requests. 467 */ 468static int log_arp_wrong_iface = 1; 469static int log_arp_movements = 1; 470static int log_arp_permanent_modify = 1; 471 472SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 473 &log_arp_wrong_iface, 0, 474 "log arp packets arriving on the wrong interface"); 475SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 476 &log_arp_movements, 0, 477 "log arp replies from MACs different than the one in the cache"); 478SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 479 &log_arp_permanent_modify, 0, 480 "log arp replies from MACs different than the one in the permanent arp entry"); 481 482 483static void 484in_arpinput(struct mbuf *m) 485{ 486 struct arphdr *ah; 487 struct ifnet *ifp = m->m_pkthdr.rcvif; 488 struct llentry *la = NULL; 489 struct rtentry *rt; 490 struct ifaddr *ifa; 491 struct in_ifaddr *ia; 492 struct mbuf *hold; 493 struct sockaddr sa; 494 struct in_addr isaddr, itaddr, myaddr; 495 u_int8_t *enaddr = NULL; 496 int op, flags; 497 int req_len; 498 int bridged = 0, is_bridge = 0; 499#ifdef DEV_CARP 500 int carp_match = 0; 501#endif 502 struct sockaddr_in sin; 503 sin.sin_len = sizeof(struct sockaddr_in); 504 sin.sin_family = AF_INET; 505 sin.sin_addr.s_addr = 0; 506 507 if (ifp->if_bridge) 508 bridged = 1; 509 if (ifp->if_type == IFT_BRIDGE) 510 is_bridge = 1; 511 512 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 513 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 514 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 515 return; 516 } 517 518 ah = mtod(m, struct arphdr *); 519 op = ntohs(ah->ar_op); 520 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 521 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 522 523 if (op == ARPOP_REPLY) 524 ARPSTAT_INC(rxreplies); 525 526 /* 527 * For a bridge, we want to check the address irrespective 528 * of the receive interface. (This will change slightly 529 * when we have clusters of interfaces). 530 * If the interface does not match, but the recieving interface 531 * is part of carp, we call carp_iamatch to see if this is a 532 * request for the virtual host ip. 533 * XXX: This is really ugly! 534 */ 535 IN_IFADDR_RLOCK(); 536 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 537 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 538 ia->ia_ifp == ifp) && 539 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 540 ifa_ref(&ia->ia_ifa); 541 IN_IFADDR_RUNLOCK(); 542 goto match; 543 } 544#ifdef DEV_CARP 545 if (ifp->if_carp != NULL && 546 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 547 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 548 carp_match = 1; 549 ifa_ref(&ia->ia_ifa); 550 IN_IFADDR_RUNLOCK(); 551 goto match; 552 } 553#endif 554 } 555 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 556 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 557 ia->ia_ifp == ifp) && 558 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 559 ifa_ref(&ia->ia_ifa); 560 IN_IFADDR_RUNLOCK(); 561 goto match; 562 } 563 564#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 565 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 566 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 567 addr == ia->ia_addr.sin_addr.s_addr) 568 /* 569 * Check the case when bridge shares its MAC address with 570 * some of its children, so packets are claimed by bridge 571 * itself (bridge_input() does it first), but they are really 572 * meant to be destined to the bridge member. 573 */ 574 if (is_bridge) { 575 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 576 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 577 ifa_ref(&ia->ia_ifa); 578 ifp = ia->ia_ifp; 579 IN_IFADDR_RUNLOCK(); 580 goto match; 581 } 582 } 583 } 584#undef BDG_MEMBER_MATCHES_ARP 585 IN_IFADDR_RUNLOCK(); 586 587 /* 588 * No match, use the first inet address on the receive interface 589 * as a dummy address for the rest of the function. 590 */ 591 IF_ADDR_LOCK(ifp); 592 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 593 if (ifa->ifa_addr->sa_family == AF_INET) { 594 ia = ifatoia(ifa); 595 ifa_ref(ifa); 596 IF_ADDR_UNLOCK(ifp); 597 goto match; 598 } 599 IF_ADDR_UNLOCK(ifp); 600 601 /* 602 * If bridging, fall back to using any inet address. 603 */ 604 IN_IFADDR_RLOCK(); 605 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 606 IN_IFADDR_RUNLOCK(); 607 goto drop; 608 } 609 ifa_ref(&ia->ia_ifa); 610 IN_IFADDR_RUNLOCK(); 611match: 612 if (!enaddr) 613 enaddr = (u_int8_t *)IF_LLADDR(ifp); 614 myaddr = ia->ia_addr.sin_addr; 615 ifa_free(&ia->ia_ifa); 616 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 617 goto drop; /* it's from me, ignore it. */ 618 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 619 log(LOG_ERR, 620 "arp: link address is broadcast for IP address %s!\n", 621 inet_ntoa(isaddr)); 622 goto drop; 623 } 624 /* 625 * Warn if another host is using the same IP address, but only if the 626 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 627 * case we suppress the warning to avoid false positive complaints of 628 * potential misconfiguration. 629 */ 630 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 631 log(LOG_ERR, 632 "arp: %*D is using my IP address %s on %s!\n", 633 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 634 inet_ntoa(isaddr), ifp->if_xname); 635 itaddr = myaddr; 636 ARPSTAT_INC(dupips); 637 goto reply; 638 } 639 if (ifp->if_flags & IFF_STATICARP) 640 goto reply; 641 642 bzero(&sin, sizeof(sin)); 643 sin.sin_len = sizeof(struct sockaddr_in); 644 sin.sin_family = AF_INET; 645 sin.sin_addr = isaddr; 646 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 647 flags |= LLE_EXCLUSIVE; 648 IF_AFDATA_LOCK(ifp); 649 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 650 IF_AFDATA_UNLOCK(ifp); 651 if (la != NULL) { 652 /* the following is not an error when doing bridging */ 653 if (!bridged && la->lle_tbl->llt_ifp != ifp 654#ifdef DEV_CARP 655 && (ifp->if_type != IFT_CARP || !carp_match) 656#endif 657 ) { 658 if (log_arp_wrong_iface) 659 log(LOG_ERR, "arp: %s is on %s " 660 "but got reply from %*D on %s\n", 661 inet_ntoa(isaddr), 662 la->lle_tbl->llt_ifp->if_xname, 663 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 664 ifp->if_xname); 665 LLE_WUNLOCK(la); 666 goto reply; 667 } 668 if ((la->la_flags & LLE_VALID) && 669 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 670 if (la->la_flags & LLE_STATIC) { 671 LLE_WUNLOCK(la); 672 log(LOG_ERR, 673 "arp: %*D attempts to modify permanent " 674 "entry for %s on %s\n", 675 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 676 inet_ntoa(isaddr), ifp->if_xname); 677 goto reply; 678 } 679 if (log_arp_movements) { 680 log(LOG_INFO, "arp: %s moved from %*D " 681 "to %*D on %s\n", 682 inet_ntoa(isaddr), 683 ifp->if_addrlen, 684 (u_char *)&la->ll_addr, ":", 685 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 686 ifp->if_xname); 687 } 688 } 689 690 if (ifp->if_addrlen != ah->ar_hln) { 691 LLE_WUNLOCK(la); 692 log(LOG_WARNING, 693 "arp from %*D: addr len: new %d, i/f %d (ignored)", 694 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 695 ah->ar_hln, ifp->if_addrlen); 696 goto reply; 697 } 698 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 699 la->la_flags |= LLE_VALID; 700 701 EVENTHANDLER_INVOKE(arp_update_event, la); 702 703 if (!(la->la_flags & LLE_STATIC)) { 704 int canceled; 705 706 LLE_ADDREF(la); 707 la->la_expire = time_second + V_arpt_keep; 708 canceled = callout_reset(&la->la_timer, 709 hz * V_arpt_keep, arptimer, la); 710 if (canceled) 711 LLE_REMREF(la); 712 } 713 la->la_asked = 0; 714 la->la_preempt = V_arp_maxtries; 715 hold = la->la_hold; 716 if (hold != NULL) { 717 la->la_hold = NULL; 718 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 719 } 720 LLE_WUNLOCK(la); 721 if (hold != NULL) 722 (*ifp->if_output)(ifp, hold, &sa, NULL); 723 } 724reply: 725 if (op != ARPOP_REQUEST) 726 goto drop; 727 ARPSTAT_INC(rxrequests); 728 729 if (itaddr.s_addr == myaddr.s_addr) { 730 /* Shortcut.. the receiving interface is the target. */ 731 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 732 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 733 } else { 734 struct llentry *lle = NULL; 735 736 sin.sin_addr = itaddr; 737 IF_AFDATA_LOCK(ifp); 738 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 739 IF_AFDATA_UNLOCK(ifp); 740 741 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 742 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 743 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 744 LLE_RUNLOCK(lle); 745 } else { 746 747 if (lle != NULL) 748 LLE_RUNLOCK(lle); 749 750 if (!V_arp_proxyall) 751 goto drop; 752 753 sin.sin_addr = itaddr; 754 /* XXX MRT use table 0 for arp reply */ 755 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 756 if (!rt) 757 goto drop; 758 759 /* 760 * Don't send proxies for nodes on the same interface 761 * as this one came out of, or we'll get into a fight 762 * over who claims what Ether address. 763 */ 764 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 765 RTFREE_LOCKED(rt); 766 goto drop; 767 } 768 RTFREE_LOCKED(rt); 769 770 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 771 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 772 773 /* 774 * Also check that the node which sent the ARP packet 775 * is on the the interface we expect it to be on. This 776 * avoids ARP chaos if an interface is connected to the 777 * wrong network. 778 */ 779 sin.sin_addr = isaddr; 780 781 /* XXX MRT use table 0 for arp checks */ 782 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 783 if (!rt) 784 goto drop; 785 if (rt->rt_ifp != ifp) { 786 log(LOG_INFO, "arp_proxy: ignoring request" 787 " from %s via %s, expecting %s\n", 788 inet_ntoa(isaddr), ifp->if_xname, 789 rt->rt_ifp->if_xname); 790 RTFREE_LOCKED(rt); 791 goto drop; 792 } 793 RTFREE_LOCKED(rt); 794 795#ifdef DEBUG_PROXY 796 printf("arp: proxying for %s\n", 797 inet_ntoa(itaddr)); 798#endif 799 } 800 } 801 802 if (itaddr.s_addr == myaddr.s_addr && 803 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 804 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 805#ifdef DEBUG_LINKLOCAL 806 printf("arp: sending reply for link-local addr %s\n", 807 inet_ntoa(itaddr)); 808#endif 809 m->m_flags |= M_BCAST; 810 m->m_flags &= ~M_MCAST; 811 } else { 812 /* default behaviour; never reply by broadcast. */ 813 m->m_flags &= ~(M_BCAST|M_MCAST); 814 } 815 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 816 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 817 ah->ar_op = htons(ARPOP_REPLY); 818 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 819 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 820 m->m_pkthdr.len = m->m_len; 821 sa.sa_family = AF_ARP; 822 sa.sa_len = 2; 823 (*ifp->if_output)(ifp, m, &sa, NULL); 824 ARPSTAT_INC(txreplies); 825 return; 826 827drop: 828 m_freem(m); 829} 830#endif 831 832void 833arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 834{ 835 struct llentry *lle; 836 837 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 838 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 839 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 840 /* 841 * interface address is considered static entry 842 * because the output of the arp utility shows 843 * that L2 entry as permanent 844 */ 845 IF_AFDATA_LOCK(ifp); 846 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 847 (struct sockaddr *)IA_SIN(ifa)); 848 IF_AFDATA_UNLOCK(ifp); 849 if (lle == NULL) 850 log(LOG_INFO, "arp_ifinit: cannot create arp " 851 "entry for interface address\n"); 852 else 853 LLE_RUNLOCK(lle); 854 } 855 ifa->ifa_rtrequest = NULL; 856} 857 858void 859arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 860{ 861 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 862 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 863 &IA_SIN(ifa)->sin_addr, enaddr); 864 ifa->ifa_rtrequest = NULL; 865} 866 867static void 868arp_init(void) 869{ 870 871 netisr_register(&arp_nh); 872} 873SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 874