if_ether.c revision 190787
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 190787 2009-04-06 22:29:41Z zec $"); 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) \ 85 ((struct in_ifinfo *)(ifp)->if_afdata[AF_INET])->ii_llt 86 87SYSCTL_DECL(_net_link_ether); 88SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 89 90/* timer values */ 91#ifdef VIMAGE_GLOBALS 92static int arpt_keep; /* once resolved, good for 20 more minutes */ 93static int arp_maxtries; 94int useloopback; /* use loopback interface for local traffic */ 95static int arp_proxyall; 96#endif 97 98SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, max_age, 99 CTLFLAG_RW, arpt_keep, 0, "ARP entry lifetime in seconds"); 100 101static struct ifqueue arpintrq; 102 103SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, maxtries, 104 CTLFLAG_RW, arp_maxtries, 0, 105 "ARP resolution attempts before returning error"); 106SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, useloopback, 107 CTLFLAG_RW, useloopback, 0, 108 "Use the loopback interface for local traffic"); 109SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, proxyall, 110 CTLFLAG_RW, arp_proxyall, 0, 111 "Enable proxy ARP for all suitable requests"); 112 113static void arp_init(void); 114static int arp_iattach(const void *); 115void arprequest(struct ifnet *, 116 struct in_addr *, struct in_addr *, u_char *); 117static void arpintr(struct mbuf *); 118static void arptimer(void *); 119#ifdef INET 120static void in_arpinput(struct mbuf *); 121#endif 122 123#ifdef AF_INET 124void arp_ifscrub(struct ifnet *ifp, uint32_t addr); 125 126/* 127 * called by in_ifscrub to remove entry from the table when 128 * the interface goes away 129 */ 130void 131arp_ifscrub(struct ifnet *ifp, uint32_t addr) 132{ 133 struct sockaddr_in addr4; 134 135 bzero((void *)&addr4, sizeof(addr4)); 136 addr4.sin_len = sizeof(addr4); 137 addr4.sin_family = AF_INET; 138 addr4.sin_addr.s_addr = addr; 139 IF_AFDATA_LOCK(ifp); 140 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR), 141 (struct sockaddr *)&addr4); 142 IF_AFDATA_UNLOCK(ifp); 143} 144#endif 145 146/* 147 * Timeout routine. Age arp_tab entries periodically. 148 */ 149static void 150arptimer(void *arg) 151{ 152 struct ifnet *ifp; 153 struct llentry *lle = (struct llentry *)arg; 154 155 if (lle == NULL) { 156 panic("%s: NULL entry!\n", __func__); 157 return; 158 } 159 ifp = lle->lle_tbl->llt_ifp; 160 IF_AFDATA_LOCK(ifp); 161 LLE_WLOCK(lle); 162 if (((lle->la_flags & LLE_DELETED) 163 || (time_second >= lle->la_expire)) 164 && (!callout_pending(&lle->la_timer) && 165 callout_active(&lle->la_timer))) 166 (void) llentry_free(lle); 167 else { 168 /* 169 * Still valid, just drop our reference 170 */ 171 LLE_FREE_LOCKED(lle); 172 } 173 IF_AFDATA_UNLOCK(ifp); 174} 175 176/* 177 * Broadcast an ARP request. Caller specifies: 178 * - arp header source ip address 179 * - arp header target ip address 180 * - arp header source ethernet address 181 */ 182void 183arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 184 u_char *enaddr) 185{ 186 struct mbuf *m; 187 struct arphdr *ah; 188 struct sockaddr sa; 189 190 if (sip == NULL) { 191 /* XXX don't believe this can happen (or explain why) */ 192 /* 193 * The caller did not supply a source address, try to find 194 * a compatible one among those assigned to this interface. 195 */ 196 struct ifaddr *ifa; 197 198 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 199 if (!ifa->ifa_addr || 200 ifa->ifa_addr->sa_family != AF_INET) 201 continue; 202 sip = &SIN(ifa->ifa_addr)->sin_addr; 203 if (0 == ((sip->s_addr ^ tip->s_addr) & 204 SIN(ifa->ifa_netmask)->sin_addr.s_addr) ) 205 break; /* found it. */ 206 } 207 if (sip == NULL) { 208 printf("%s: cannot find matching address\n", __func__); 209 return; 210 } 211 } 212 213 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 214 return; 215 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 216 2*ifp->if_data.ifi_addrlen; 217 m->m_pkthdr.len = m->m_len; 218 MH_ALIGN(m, m->m_len); 219 ah = mtod(m, struct arphdr *); 220 bzero((caddr_t)ah, m->m_len); 221#ifdef MAC 222 mac_netinet_arp_send(ifp, m); 223#endif 224 ah->ar_pro = htons(ETHERTYPE_IP); 225 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 226 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 227 ah->ar_op = htons(ARPOP_REQUEST); 228 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 229 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 230 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 231 sa.sa_family = AF_ARP; 232 sa.sa_len = 2; 233 m->m_flags |= M_BCAST; 234 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 235} 236 237/* 238 * Resolve an IP address into an ethernet address. 239 * On input: 240 * ifp is the interface we use 241 * rt0 is the route to the final destination (possibly useless) 242 * m is the mbuf. May be NULL if we don't have a packet. 243 * dst is the next hop, 244 * desten is where we want the address. 245 * 246 * On success, desten is filled in and the function returns 0; 247 * If the packet must be held pending resolution, we return EWOULDBLOCK 248 * On other errors, we return the corresponding error code. 249 * Note that m_freem() handles NULL. 250 */ 251int 252arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 253 struct sockaddr *dst, u_char *desten, struct llentry **lle) 254{ 255 INIT_VNET_INET(ifp->if_vnet); 256 struct llentry *la = 0; 257 u_int flags = 0; 258 int error, renew; 259 260 *lle = NULL; 261 if (m != NULL) { 262 if (m->m_flags & M_BCAST) { 263 /* broadcast */ 264 (void)memcpy(desten, 265 ifp->if_broadcastaddr, ifp->if_addrlen); 266 return (0); 267 } 268 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) { 269 /* multicast */ 270 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 271 return (0); 272 } 273 } 274 /* XXXXX 275 */ 276retry: 277 IF_AFDATA_RLOCK(ifp); 278 la = lla_lookup(LLTABLE(ifp), flags, dst); 279 IF_AFDATA_RUNLOCK(ifp); 280 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0) 281 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) { 282 flags |= (LLE_CREATE | LLE_EXCLUSIVE); 283 IF_AFDATA_WLOCK(ifp); 284 la = lla_lookup(LLTABLE(ifp), flags, dst); 285 IF_AFDATA_WUNLOCK(ifp); 286 } 287 if (la == NULL) { 288 if (flags & LLE_CREATE) 289 log(LOG_DEBUG, 290 "arpresolve: can't allocate llinfo for %s\n", 291 inet_ntoa(SIN(dst)->sin_addr)); 292 m_freem(m); 293 return (EINVAL); 294 } 295 296 if ((la->la_flags & LLE_VALID) && 297 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 298 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 299 /* 300 * If entry has an expiry time and it is approaching, 301 * see if we need to send an ARP request within this 302 * arpt_down interval. 303 */ 304 if (!(la->la_flags & LLE_STATIC) && 305 time_uptime + la->la_preempt > la->la_expire) { 306 arprequest(ifp, NULL, 307 &SIN(dst)->sin_addr, IF_LLADDR(ifp)); 308 309 la->la_preempt--; 310 } 311 312 *lle = la; 313 error = 0; 314 goto done; 315 } 316 317 if (la->la_flags & LLE_STATIC) { /* should not happen! */ 318 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n", 319 inet_ntoa(SIN(dst)->sin_addr)); 320 m_freem(m); 321 error = EINVAL; 322 goto done; 323 } 324 325 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 326 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) { 327 flags |= LLE_EXCLUSIVE; 328 LLE_RUNLOCK(la); 329 goto retry; 330 } 331 /* 332 * There is an arptab entry, but no ethernet address 333 * response yet. Replace the held mbuf with this 334 * latest one. 335 */ 336 if (m != NULL) { 337 if (la->la_hold != NULL) 338 m_freem(la->la_hold); 339 la->la_hold = m; 340 if (renew == 0 && (flags & LLE_EXCLUSIVE)) { 341 flags &= ~LLE_EXCLUSIVE; 342 LLE_DOWNGRADE(la); 343 } 344 345 } 346 /* 347 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 348 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 349 * if we have already sent arp_maxtries ARP requests. Retransmit the 350 * ARP request, but not faster than one request per second. 351 */ 352 if (la->la_asked < V_arp_maxtries) 353 error = EWOULDBLOCK; /* First request. */ 354 else 355 error = 356 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH; 357 358 if (renew) { 359 LLE_ADDREF(la); 360 la->la_expire = time_uptime; 361 callout_reset(&la->la_timer, hz, arptimer, la); 362 la->la_asked++; 363 LLE_WUNLOCK(la); 364 arprequest(ifp, NULL, &SIN(dst)->sin_addr, 365 IF_LLADDR(ifp)); 366 return (error); 367 } 368done: 369 if (flags & LLE_EXCLUSIVE) 370 LLE_WUNLOCK(la); 371 else 372 LLE_RUNLOCK(la); 373 return (error); 374} 375 376/* 377 * Common length and type checks are done here, 378 * then the protocol-specific routine is called. 379 */ 380static void 381arpintr(struct mbuf *m) 382{ 383 struct arphdr *ar; 384 385 if (m->m_len < sizeof(struct arphdr) && 386 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 387 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 388 return; 389 } 390 ar = mtod(m, struct arphdr *); 391 392 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 393 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 394 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 395 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 396 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 397 (unsigned char *)&ar->ar_hrd, ""); 398 m_freem(m); 399 return; 400 } 401 402 if (m->m_len < arphdr_len(ar)) { 403 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 404 log(LOG_ERR, "arp: runt packet\n"); 405 m_freem(m); 406 return; 407 } 408 ar = mtod(m, struct arphdr *); 409 } 410 411 switch (ntohs(ar->ar_pro)) { 412#ifdef INET 413 case ETHERTYPE_IP: 414 in_arpinput(m); 415 return; 416#endif 417 } 418 m_freem(m); 419} 420 421#ifdef INET 422/* 423 * ARP for Internet protocols on 10 Mb/s Ethernet. 424 * Algorithm is that given in RFC 826. 425 * In addition, a sanity check is performed on the sender 426 * protocol address, to catch impersonators. 427 * We no longer handle negotiations for use of trailer protocol: 428 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 429 * along with IP replies if we wanted trailers sent to us, 430 * and also sent them in response to IP replies. 431 * This allowed either end to announce the desire to receive 432 * trailer packets. 433 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 434 * but formerly didn't normally send requests. 435 */ 436static int log_arp_wrong_iface = 1; 437static int log_arp_movements = 1; 438static int log_arp_permanent_modify = 1; 439 440SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 441 &log_arp_wrong_iface, 0, 442 "log arp packets arriving on the wrong interface"); 443SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 444 &log_arp_movements, 0, 445 "log arp replies from MACs different than the one in the cache"); 446SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 447 &log_arp_permanent_modify, 0, 448 "log arp replies from MACs different than the one in the permanent arp entry"); 449 450 451static void 452in_arpinput(struct mbuf *m) 453{ 454 struct arphdr *ah; 455 struct ifnet *ifp = m->m_pkthdr.rcvif; 456 struct llentry *la = NULL; 457 struct rtentry *rt; 458 struct ifaddr *ifa; 459 struct in_ifaddr *ia; 460 struct sockaddr sa; 461 struct in_addr isaddr, itaddr, myaddr; 462 u_int8_t *enaddr = NULL; 463 int op, flags; 464 struct mbuf *m0; 465 int req_len; 466 int bridged = 0, is_bridge = 0; 467#ifdef DEV_CARP 468 int carp_match = 0; 469#endif 470 struct sockaddr_in sin; 471 sin.sin_len = sizeof(struct sockaddr_in); 472 sin.sin_family = AF_INET; 473 sin.sin_addr.s_addr = 0; 474 INIT_VNET_INET(ifp->if_vnet); 475 476 if (ifp->if_bridge) 477 bridged = 1; 478 if (ifp->if_type == IFT_BRIDGE) 479 is_bridge = 1; 480 481 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 482 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 483 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 484 return; 485 } 486 487 ah = mtod(m, struct arphdr *); 488 op = ntohs(ah->ar_op); 489 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 490 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 491 492 /* 493 * For a bridge, we want to check the address irrespective 494 * of the receive interface. (This will change slightly 495 * when we have clusters of interfaces). 496 * If the interface does not match, but the recieving interface 497 * is part of carp, we call carp_iamatch to see if this is a 498 * request for the virtual host ip. 499 * XXX: This is really ugly! 500 */ 501 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 502 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 503 ia->ia_ifp == ifp) && 504 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 505 goto match; 506#ifdef DEV_CARP 507 if (ifp->if_carp != NULL && 508 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 509 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 510 carp_match = 1; 511 goto match; 512 } 513#endif 514 } 515 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 516 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 517 ia->ia_ifp == ifp) && 518 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 519 goto match; 520 521#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 522 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 523 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 524 addr == ia->ia_addr.sin_addr.s_addr) 525 /* 526 * Check the case when bridge shares its MAC address with 527 * some of its children, so packets are claimed by bridge 528 * itself (bridge_input() does it first), but they are really 529 * meant to be destined to the bridge member. 530 */ 531 if (is_bridge) { 532 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 533 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 534 ifp = ia->ia_ifp; 535 goto match; 536 } 537 } 538 } 539#undef BDG_MEMBER_MATCHES_ARP 540 541 /* 542 * No match, use the first inet address on the receive interface 543 * as a dummy address for the rest of the function. 544 */ 545 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 546 if (ifa->ifa_addr->sa_family == AF_INET) { 547 ia = ifatoia(ifa); 548 goto match; 549 } 550 /* 551 * If bridging, fall back to using any inet address. 552 */ 553 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 554 goto drop; 555match: 556 if (!enaddr) 557 enaddr = (u_int8_t *)IF_LLADDR(ifp); 558 myaddr = ia->ia_addr.sin_addr; 559 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 560 goto drop; /* it's from me, ignore it. */ 561 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 562 log(LOG_ERR, 563 "arp: link address is broadcast for IP address %s!\n", 564 inet_ntoa(isaddr)); 565 goto drop; 566 } 567 /* 568 * Warn if another host is using the same IP address, but only if the 569 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 570 * case we suppress the warning to avoid false positive complaints of 571 * potential misconfiguration. 572 */ 573 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 574 log(LOG_ERR, 575 "arp: %*D is using my IP address %s on %s!\n", 576 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 577 inet_ntoa(isaddr), ifp->if_xname); 578 itaddr = myaddr; 579 goto reply; 580 } 581 if (ifp->if_flags & IFF_STATICARP) 582 goto reply; 583 584 bzero(&sin, sizeof(sin)); 585 sin.sin_len = sizeof(struct sockaddr_in); 586 sin.sin_family = AF_INET; 587 sin.sin_addr = isaddr; 588 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0; 589 flags |= LLE_EXCLUSIVE; 590 IF_AFDATA_LOCK(ifp); 591 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin); 592 IF_AFDATA_UNLOCK(ifp); 593 if (la != NULL) { 594 /* the following is not an error when doing bridging */ 595 if (!bridged && la->lle_tbl->llt_ifp != ifp 596#ifdef DEV_CARP 597 && (ifp->if_type != IFT_CARP || !carp_match) 598#endif 599 ) { 600 if (log_arp_wrong_iface) 601 log(LOG_ERR, "arp: %s is on %s " 602 "but got reply from %*D on %s\n", 603 inet_ntoa(isaddr), 604 la->lle_tbl->llt_ifp->if_xname, 605 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 606 ifp->if_xname); 607 goto reply; 608 } 609 if ((la->la_flags & LLE_VALID) && 610 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 611 if (la->la_flags & LLE_STATIC) { 612 log(LOG_ERR, 613 "arp: %*D attempts to modify permanent " 614 "entry for %s on %s\n", 615 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 616 inet_ntoa(isaddr), ifp->if_xname); 617 goto reply; 618 } 619 if (log_arp_movements) { 620 log(LOG_INFO, "arp: %s moved from %*D " 621 "to %*D on %s\n", 622 inet_ntoa(isaddr), 623 ifp->if_addrlen, 624 (u_char *)&la->ll_addr, ":", 625 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 626 ifp->if_xname); 627 } 628 } 629 630 if (ifp->if_addrlen != ah->ar_hln) { 631 log(LOG_WARNING, 632 "arp from %*D: addr len: new %d, i/f %d (ignored)", 633 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 634 ah->ar_hln, ifp->if_addrlen); 635 goto reply; 636 } 637 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 638 la->la_flags |= LLE_VALID; 639 640 if (!(la->la_flags & LLE_STATIC)) { 641 la->la_expire = time_uptime + V_arpt_keep; 642 callout_reset(&la->la_timer, hz * V_arpt_keep, 643 arptimer, la); 644 } 645 la->la_asked = 0; 646 la->la_preempt = V_arp_maxtries; 647 if (la->la_hold != NULL) { 648 m0 = la->la_hold; 649 la->la_hold = 0; 650 memcpy(&sa, L3_ADDR(la), sizeof(sa)); 651 LLE_WUNLOCK(la); 652 653 (*ifp->if_output)(ifp, m0, &sa, NULL); 654 return; 655 } 656 } 657reply: 658 if (op != ARPOP_REQUEST) 659 goto drop; 660 661 if (itaddr.s_addr == myaddr.s_addr) { 662 /* Shortcut.. the receiving interface is the target. */ 663 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 664 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 665 } else { 666 struct llentry *lle = NULL; 667 668 if (!V_arp_proxyall) 669 goto drop; 670 671 sin.sin_addr = itaddr; 672 /* XXX MRT use table 0 for arp reply */ 673 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 674 if (!rt) 675 goto drop; 676 677 /* 678 * Don't send proxies for nodes on the same interface 679 * as this one came out of, or we'll get into a fight 680 * over who claims what Ether address. 681 */ 682 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 683 RTFREE_LOCKED(rt); 684 goto drop; 685 } 686 IF_AFDATA_LOCK(rt->rt_ifp); 687 lle = lla_lookup(LLTABLE(rt->rt_ifp), 0, (struct sockaddr *)&sin); 688 IF_AFDATA_UNLOCK(rt->rt_ifp); 689 RTFREE_LOCKED(rt); 690 691 if (lle != NULL) { 692 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 693 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 694 LLE_RUNLOCK(lle); 695 } else 696 goto drop; 697 698 /* 699 * Also check that the node which sent the ARP packet 700 * is on the the interface we expect it to be on. This 701 * avoids ARP chaos if an interface is connected to the 702 * wrong network. 703 */ 704 sin.sin_addr = isaddr; 705 706 /* XXX MRT use table 0 for arp checks */ 707 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 708 if (!rt) 709 goto drop; 710 if (rt->rt_ifp != ifp) { 711 log(LOG_INFO, "arp_proxy: ignoring request" 712 " from %s via %s, expecting %s\n", 713 inet_ntoa(isaddr), ifp->if_xname, 714 rt->rt_ifp->if_xname); 715 RTFREE_LOCKED(rt); 716 goto drop; 717 } 718 RTFREE_LOCKED(rt); 719 720#ifdef DEBUG_PROXY 721 printf("arp: proxying for %s\n", 722 inet_ntoa(itaddr)); 723#endif 724 } 725 726 if (la != NULL) 727 LLE_WUNLOCK(la); 728 if (itaddr.s_addr == myaddr.s_addr && 729 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 730 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 731#ifdef DEBUG_LINKLOCAL 732 printf("arp: sending reply for link-local addr %s\n", 733 inet_ntoa(itaddr)); 734#endif 735 m->m_flags |= M_BCAST; 736 m->m_flags &= ~M_MCAST; 737 } else { 738 /* default behaviour; never reply by broadcast. */ 739 m->m_flags &= ~(M_BCAST|M_MCAST); 740 } 741 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 742 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 743 ah->ar_op = htons(ARPOP_REPLY); 744 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 745 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 746 m->m_pkthdr.len = m->m_len; 747 sa.sa_family = AF_ARP; 748 sa.sa_len = 2; 749 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 750 return; 751 752drop: 753 if (la != NULL) 754 LLE_WUNLOCK(la); 755 m_freem(m); 756} 757#endif 758 759void 760arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 761{ 762 struct llentry *lle; 763 764 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 765 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 766 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 767 /* 768 * interface address is considered static entry 769 * because the output of the arp utility shows 770 * that L2 entry as permanent 771 */ 772 IF_AFDATA_LOCK(ifp); 773 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC), 774 (struct sockaddr *)IA_SIN(ifa)); 775 IF_AFDATA_UNLOCK(ifp); 776 if (lle == NULL) 777 log(LOG_INFO, "arp_ifinit: cannot create arp " 778 "entry for interface address\n"); 779 else 780 LLE_RUNLOCK(lle); 781 } 782 ifa->ifa_rtrequest = NULL; 783} 784 785void 786arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 787{ 788 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 789 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 790 &IA_SIN(ifa)->sin_addr, enaddr); 791 ifa->ifa_rtrequest = NULL; 792} 793 794static int 795arp_iattach(const void *unused __unused) 796{ 797 INIT_VNET_INET(curvnet); 798 799 V_arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 800 V_arp_maxtries = 5; 801 V_useloopback = 1; /* use loopback interface for local traffic */ 802 V_arp_proxyall = 0; 803 804 return (0); 805} 806 807static void 808arp_init(void) 809{ 810 811 arp_iattach(NULL); 812 813 arpintrq.ifq_maxlen = 50; 814 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 815 netisr_register(NETISR_ARP, arpintr, &arpintrq, 0); 816} 817SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 818