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 43 #include <sys/param.h> 44 #include <sys/kernel.h> 45 #include <sys/lock.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/rmlock.h> 53 #include <sys/socket.h> 54 #include <sys/syslog.h> 55 56 #include <net/if.h> 57 #include <net/if_var.h> 58 #include <net/if_dl.h> 59 #include <net/if_types.h> 60 #include <net/netisr.h> 61 #include <net/if_llc.h> 62 #include <net/ethernet.h> 63 #include <net/route.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 #ifdef INET 71 #include <netinet/ip_carp.h> 72 #endif 73 74 #include <net/if_arc.h> 75 #include <net/iso88025.h> 76 77 #include <security/mac/mac_framework.h> 78 79 #define SIN(s) ((const struct sockaddr_in *)(s)) 80 #define SDL(s) ((struct sockaddr_dl *)s) 81 82 SYSCTL_DECL(_net_link_ether); 83 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 84 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 85 86 /* timer values */ 87 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 88 * minutes */ 89 static VNET_DEFINE(int, arp_maxtries) = 5; 90 static VNET_DEFINE(int, arp_proxyall) = 0; 91 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 92 * 20 seconds */ 93 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 94 VNET_PCPUSTAT_SYSINIT(arpstat); 95 96 #ifdef VIMAGE 97 VNET_PCPUSTAT_SYSUNINIT(arpstat); 98 #endif /* VIMAGE */ 99 100 static VNET_DEFINE(int, arp_maxhold) = 1; 101 102 #define V_arpt_keep VNET(arpt_keep) 103 #define V_arpt_down VNET(arpt_down) 104 #define V_arp_maxtries VNET(arp_maxtries) 105 #define V_arp_proxyall VNET(arp_proxyall) 106 #define V_arp_maxhold VNET(arp_maxhold) 107 108 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 109 &VNET_NAME(arpt_keep), 0, 110 "ARP entry lifetime in seconds"); 111 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 112 &VNET_NAME(arp_maxtries), 0, 113 "ARP resolution attempts before returning error"); 114 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 115 &VNET_NAME(arp_proxyall), 0, 116 "Enable proxy ARP for all suitable requests"); 117 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 118 &VNET_NAME(arpt_down), 0, 119 "Incomplete ARP entry lifetime in seconds"); 120 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 121 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 122 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 123 &VNET_NAME(arp_maxhold), 0, 124 "Number of packets to hold per ARP entry"); 125 126 static void arp_init(void); 127 static void arpintr(struct mbuf *); 128 static void arptimer(void *); 129 #ifdef INET 130 static void in_arpinput(struct mbuf *); 131 #endif 132 133 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 134 struct ifnet *ifp, int bridged, struct llentry *la); 135 static void arp_update_lle(struct arphdr *ah, struct ifnet *ifp, 136 struct llentry *la); 137 static void arp_mark_lle_reachable(struct llentry *la); 138 139 140 static const struct netisr_handler arp_nh = { 141 .nh_name = "arp", 142 .nh_handler = arpintr, 143 .nh_proto = NETISR_ARP, 144 .nh_policy = NETISR_POLICY_SOURCE, 145 }; 146 147 #ifdef AF_INET 148 /* 149 * called by in_scrubprefix() to remove entry from the table when 150 * the interface goes away 151 */ 152 void 153 arp_ifscrub(struct ifnet *ifp, uint32_t addr) 154 { 155 struct sockaddr_in addr4; 156 157 bzero((void *)&addr4, sizeof(addr4)); 158 addr4.sin_len = sizeof(addr4); 159 addr4.sin_family = AF_INET; 160 addr4.sin_addr.s_addr = addr; 161 IF_AFDATA_WLOCK(ifp); 162 lla_delete(LLTABLE(ifp), LLE_IFADDR, (struct sockaddr *)&addr4); 163 IF_AFDATA_WUNLOCK(ifp); 164 } 165 #endif 166 167 /* 168 * Timeout routine. Age arp_tab entries periodically. 169 */ 170 static void 171 arptimer(void *arg) 172 { 173 struct llentry *lle = (struct llentry *)arg; 174 struct ifnet *ifp; 175 176 if (lle->la_flags & LLE_STATIC) { 177 return; 178 } 179 LLE_WLOCK(lle); 180 if (callout_pending(&lle->lle_timer)) { 181 /* 182 * Here we are a bit odd here in the treatment of 183 * active/pending. If the pending bit is set, it got 184 * rescheduled before I ran. The active 185 * bit we ignore, since if it was stopped 186 * in ll_tablefree() and was currently running 187 * it would have return 0 so the code would 188 * not have deleted it since the callout could 189 * not be stopped so we want to go through 190 * with the delete here now. If the callout 191 * was restarted, the pending bit will be back on and 192 * we just want to bail since the callout_reset would 193 * return 1 and our reference would have been removed 194 * by arpresolve() below. 195 */ 196 LLE_WUNLOCK(lle); 197 return; 198 } 199 ifp = lle->lle_tbl->llt_ifp; 200 CURVNET_SET(ifp->if_vnet); 201 202 if ((lle->la_flags & LLE_DELETED) == 0) { 203 int evt; 204 205 if (lle->la_flags & LLE_VALID) 206 evt = LLENTRY_EXPIRED; 207 else 208 evt = LLENTRY_TIMEDOUT; 209 EVENTHANDLER_INVOKE(lle_event, lle, evt); 210 } 211 212 callout_stop(&lle->lle_timer); 213 214 /* XXX: LOR avoidance. We still have ref on lle. */ 215 LLE_WUNLOCK(lle); 216 IF_AFDATA_LOCK(ifp); 217 LLE_WLOCK(lle); 218 219 /* Guard against race with other llentry_free(). */ 220 if (lle->la_flags & LLE_LINKED) { 221 size_t pkts_dropped; 222 223 LLE_REMREF(lle); 224 pkts_dropped = llentry_free(lle); 225 ARPSTAT_ADD(dropped, pkts_dropped); 226 } else 227 LLE_FREE_LOCKED(lle); 228 229 IF_AFDATA_UNLOCK(ifp); 230 231 ARPSTAT_INC(timeouts); 232 233 CURVNET_RESTORE(); 234 } 235 236 /* 237 * Broadcast an ARP request. Caller specifies: 238 * - arp header source ip address 239 * - arp header target ip address 240 * - arp header source ethernet address 241 */ 242 void 243 arprequest(struct ifnet *ifp, const struct in_addr *sip, 244 const struct in_addr *tip, u_char *enaddr) 245 { 246 struct mbuf *m; 247 struct arphdr *ah; 248 struct sockaddr sa; 249 u_char *carpaddr = NULL; 250 251 if (sip == NULL) { 252 /* 253 * The caller did not supply a source address, try to find 254 * a compatible one among those assigned to this interface. 255 */ 256 struct ifaddr *ifa; 257 258 IF_ADDR_RLOCK(ifp); 259 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 260 if (ifa->ifa_addr->sa_family != AF_INET) 261 continue; 262 263 if (ifa->ifa_carp) { 264 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 265 continue; 266 sip = &IA_SIN(ifa)->sin_addr; 267 } else { 268 carpaddr = NULL; 269 sip = &IA_SIN(ifa)->sin_addr; 270 } 271 272 if (0 == ((sip->s_addr ^ tip->s_addr) & 273 IA_MASKSIN(ifa)->sin_addr.s_addr)) 274 break; /* found it. */ 275 } 276 IF_ADDR_RUNLOCK(ifp); 277 if (sip == NULL) { 278 printf("%s: cannot find matching address\n", __func__); 279 return; 280 } 281 } 282 if (enaddr == NULL) 283 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 284 285 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 286 return; 287 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 288 2 * ifp->if_addrlen; 289 m->m_pkthdr.len = m->m_len; 290 M_ALIGN(m, m->m_len); 291 ah = mtod(m, struct arphdr *); 292 bzero((caddr_t)ah, m->m_len); 293 #ifdef MAC 294 mac_netinet_arp_send(ifp, m); 295 #endif 296 ah->ar_pro = htons(ETHERTYPE_IP); 297 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 298 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 299 ah->ar_op = htons(ARPOP_REQUEST); 300 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 301 bcopy(sip, ar_spa(ah), ah->ar_pln); 302 bcopy(tip, ar_tpa(ah), ah->ar_pln); 303 sa.sa_family = AF_ARP; 304 sa.sa_len = 2; 305 m->m_flags |= M_BCAST; 306 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 307 (*ifp->if_output)(ifp, m, &sa, NULL); 308 ARPSTAT_INC(txrequests); 309 } 310 311 /* 312 * Resolve an IP address into an ethernet address - heavy version. 313 * Used internally by arpresolve(). 314 * We have already checked than we can't use existing lle without 315 * modification so we have to acquire LLE_EXCLUSIVE lle lock. 316 * 317 * On success, desten and flags are filled in and the function returns 0; 318 * If the packet must be held pending resolution, we return EWOULDBLOCK 319 * On other errors, we return the corresponding error code. 320 * Note that m_freem() handles NULL. 321 */ 322 static int 323 arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf *m, 324 const struct sockaddr *dst, u_char *desten, uint32_t *pflags) 325 { 326 struct llentry *la = NULL; 327 struct mbuf *curr = NULL; 328 struct mbuf *next = NULL; 329 int error, renew; 330 331 if (pflags != NULL) 332 *pflags = 0; 333 334 if (create == 0) { 335 IF_AFDATA_RLOCK(ifp); 336 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 337 IF_AFDATA_RUNLOCK(ifp); 338 } 339 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 340 create = 1; 341 IF_AFDATA_WLOCK(ifp); 342 la = lla_create(LLTABLE(ifp), 0, dst); 343 IF_AFDATA_WUNLOCK(ifp); 344 } 345 if (la == NULL) { 346 if (create != 0) 347 log(LOG_DEBUG, 348 "arpresolve: can't allocate llinfo for %s on %s\n", 349 inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname); 350 m_freem(m); 351 return (EINVAL); 352 } 353 354 if ((la->la_flags & LLE_VALID) && 355 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 356 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 357 renew = 0; 358 /* 359 * If entry has an expiry time and it is approaching, 360 * see if we need to send an ARP request within this 361 * arpt_down interval. 362 */ 363 if (!(la->la_flags & LLE_STATIC) && 364 time_uptime + la->la_preempt > la->la_expire) { 365 renew = 1; 366 la->la_preempt--; 367 } 368 369 if (pflags != NULL) 370 *pflags = la->la_flags; 371 372 LLE_WUNLOCK(la); 373 374 if (renew == 1) 375 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 376 377 return (0); 378 } 379 380 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 381 /* 382 * There is an arptab entry, but no ethernet address 383 * response yet. Add the mbuf to the list, dropping 384 * the oldest packet if we have exceeded the system 385 * setting. 386 */ 387 if (m != NULL) { 388 if (la->la_numheld >= V_arp_maxhold) { 389 if (la->la_hold != NULL) { 390 next = la->la_hold->m_nextpkt; 391 m_freem(la->la_hold); 392 la->la_hold = next; 393 la->la_numheld--; 394 ARPSTAT_INC(dropped); 395 } 396 } 397 if (la->la_hold != NULL) { 398 curr = la->la_hold; 399 while (curr->m_nextpkt != NULL) 400 curr = curr->m_nextpkt; 401 curr->m_nextpkt = m; 402 } else 403 la->la_hold = m; 404 la->la_numheld++; 405 } 406 /* 407 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 408 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 409 * if we have already sent arp_maxtries ARP requests. Retransmit the 410 * ARP request, but not faster than one request per second. 411 */ 412 if (la->la_asked < V_arp_maxtries) 413 error = EWOULDBLOCK; /* First request. */ 414 else 415 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 416 417 if (renew) { 418 int canceled; 419 420 LLE_ADDREF(la); 421 la->la_expire = time_uptime; 422 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 423 arptimer, la); 424 if (canceled) 425 LLE_REMREF(la); 426 la->la_asked++; 427 LLE_WUNLOCK(la); 428 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 429 return (error); 430 } 431 432 LLE_WUNLOCK(la); 433 return (error); 434 } 435 436 /* 437 * Resolve an IP address into an ethernet address. 438 * On input: 439 * ifp is the interface we use 440 * is_gw != 0 if @dst represents gateway to some destination 441 * m is the mbuf. May be NULL if we don't have a packet. 442 * dst is the next hop, 443 * desten is the storage to put LL address. 444 * flags returns lle entry flags. 445 * 446 * On success, desten and flags are filled in and the function returns 0; 447 * If the packet must be held pending resolution, we return EWOULDBLOCK 448 * On other errors, we return the corresponding error code. 449 * Note that m_freem() handles NULL. 450 */ 451 int 452 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 453 const struct sockaddr *dst, u_char *desten, uint32_t *pflags) 454 { 455 struct llentry *la = 0; 456 int renew; 457 458 if (pflags != NULL) 459 *pflags = 0; 460 461 if (m != NULL) { 462 if (m->m_flags & M_BCAST) { 463 /* broadcast */ 464 (void)memcpy(desten, 465 ifp->if_broadcastaddr, ifp->if_addrlen); 466 return (0); 467 } 468 if (m->m_flags & M_MCAST) { 469 /* multicast */ 470 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 471 return (0); 472 } 473 } 474 475 IF_AFDATA_RLOCK(ifp); 476 la = lla_lookup(LLTABLE(ifp), 0, dst); 477 IF_AFDATA_RUNLOCK(ifp); 478 479 if (la == NULL) 480 return (arpresolve_full(ifp, is_gw, 1, m, dst, desten, pflags)); 481 482 if ((la->la_flags & LLE_VALID) && 483 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 484 bcopy(&la->ll_addr, desten, ifp->if_addrlen); 485 renew = 0; 486 /* 487 * If entry has an expiry time and it is approaching, 488 * see if we need to send an ARP request within this 489 * arpt_down interval. 490 */ 491 if (!(la->la_flags & LLE_STATIC) && 492 time_uptime + la->la_preempt > la->la_expire) { 493 renew = 1; 494 la->la_preempt--; 495 } 496 497 if (pflags != NULL) 498 *pflags = la->la_flags; 499 500 LLE_RUNLOCK(la); 501 502 if (renew == 1) 503 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 504 505 return (0); 506 } 507 LLE_RUNLOCK(la); 508 509 return (arpresolve_full(ifp, is_gw, 0, m, dst, desten, pflags)); 510 } 511 512 /* 513 * Common length and type checks are done here, 514 * then the protocol-specific routine is called. 515 */ 516 static void 517 arpintr(struct mbuf *m) 518 { 519 struct arphdr *ar; 520 521 if (m->m_len < sizeof(struct arphdr) && 522 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 523 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n"); 524 return; 525 } 526 ar = mtod(m, struct arphdr *); 527 528 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 529 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 530 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 531 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 && 532 ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) { 533 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)" 534 " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "", 535 ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":", 536 ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":"); 537 m_freem(m); 538 return; 539 } 540 541 if (m->m_len < arphdr_len(ar)) { 542 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 543 log(LOG_NOTICE, "arp: runt packet\n"); 544 m_freem(m); 545 return; 546 } 547 ar = mtod(m, struct arphdr *); 548 } 549 550 ARPSTAT_INC(received); 551 switch (ntohs(ar->ar_pro)) { 552 #ifdef INET 553 case ETHERTYPE_IP: 554 in_arpinput(m); 555 return; 556 #endif 557 } 558 m_freem(m); 559 } 560 561 #ifdef INET 562 /* 563 * ARP for Internet protocols on 10 Mb/s Ethernet. 564 * Algorithm is that given in RFC 826. 565 * In addition, a sanity check is performed on the sender 566 * protocol address, to catch impersonators. 567 * We no longer handle negotiations for use of trailer protocol: 568 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 569 * along with IP replies if we wanted trailers sent to us, 570 * and also sent them in response to IP replies. 571 * This allowed either end to announce the desire to receive 572 * trailer packets. 573 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 574 * but formerly didn't normally send requests. 575 */ 576 static int log_arp_wrong_iface = 1; 577 static int log_arp_movements = 1; 578 static int log_arp_permanent_modify = 1; 579 static int allow_multicast = 0; 580 static struct timeval arp_lastlog; 581 static int arp_curpps; 582 static int arp_maxpps = 1; 583 584 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 585 &log_arp_wrong_iface, 0, 586 "log arp packets arriving on the wrong interface"); 587 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 588 &log_arp_movements, 0, 589 "log arp replies from MACs different than the one in the cache"); 590 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 591 &log_arp_permanent_modify, 0, 592 "log arp replies from MACs different than the one in the permanent arp entry"); 593 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 594 &allow_multicast, 0, "accept multicast addresses"); 595 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 596 CTLFLAG_RW, &arp_maxpps, 0, 597 "Maximum number of remotely triggered ARP messages that can be " 598 "logged per second"); 599 600 #define ARP_LOG(pri, ...) do { \ 601 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 602 log((pri), "arp: " __VA_ARGS__); \ 603 } while (0) 604 605 static void 606 in_arpinput(struct mbuf *m) 607 { 608 struct rm_priotracker in_ifa_tracker; 609 struct arphdr *ah; 610 struct ifnet *ifp = m->m_pkthdr.rcvif; 611 struct llentry *la = NULL; 612 struct rtentry *rt; 613 struct ifaddr *ifa; 614 struct in_ifaddr *ia; 615 struct sockaddr sa; 616 struct in_addr isaddr, itaddr, myaddr; 617 u_int8_t *enaddr = NULL; 618 int op; 619 int req_len; 620 int bridged = 0, is_bridge = 0; 621 int carped; 622 struct sockaddr_in sin; 623 sin.sin_len = sizeof(struct sockaddr_in); 624 sin.sin_family = AF_INET; 625 sin.sin_addr.s_addr = 0; 626 627 if (ifp->if_bridge) 628 bridged = 1; 629 if (ifp->if_type == IFT_BRIDGE) 630 is_bridge = 1; 631 632 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 633 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 634 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n"); 635 return; 636 } 637 638 ah = mtod(m, struct arphdr *); 639 /* 640 * ARP is only for IPv4 so we can reject packets with 641 * a protocol length not equal to an IPv4 address. 642 */ 643 if (ah->ar_pln != sizeof(struct in_addr)) { 644 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 645 sizeof(struct in_addr)); 646 goto drop; 647 } 648 649 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 650 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 651 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 652 goto drop; 653 } 654 655 op = ntohs(ah->ar_op); 656 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 657 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 658 659 if (op == ARPOP_REPLY) 660 ARPSTAT_INC(rxreplies); 661 662 /* 663 * For a bridge, we want to check the address irrespective 664 * of the receive interface. (This will change slightly 665 * when we have clusters of interfaces). 666 */ 667 IN_IFADDR_RLOCK(&in_ifa_tracker); 668 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 669 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 670 ia->ia_ifp == ifp) && 671 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 672 (ia->ia_ifa.ifa_carp == NULL || 673 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 674 ifa_ref(&ia->ia_ifa); 675 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 676 goto match; 677 } 678 } 679 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 680 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 681 ia->ia_ifp == ifp) && 682 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 683 ifa_ref(&ia->ia_ifa); 684 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 685 goto match; 686 } 687 688 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 689 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 690 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 691 addr == ia->ia_addr.sin_addr.s_addr) 692 /* 693 * Check the case when bridge shares its MAC address with 694 * some of its children, so packets are claimed by bridge 695 * itself (bridge_input() does it first), but they are really 696 * meant to be destined to the bridge member. 697 */ 698 if (is_bridge) { 699 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 700 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 701 ifa_ref(&ia->ia_ifa); 702 ifp = ia->ia_ifp; 703 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 704 goto match; 705 } 706 } 707 } 708 #undef BDG_MEMBER_MATCHES_ARP 709 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 710 711 /* 712 * No match, use the first inet address on the receive interface 713 * as a dummy address for the rest of the function. 714 */ 715 IF_ADDR_RLOCK(ifp); 716 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 717 if (ifa->ifa_addr->sa_family == AF_INET && 718 (ifa->ifa_carp == NULL || 719 (*carp_iamatch_p)(ifa, &enaddr))) { 720 ia = ifatoia(ifa); 721 ifa_ref(ifa); 722 IF_ADDR_RUNLOCK(ifp); 723 goto match; 724 } 725 IF_ADDR_RUNLOCK(ifp); 726 727 /* 728 * If bridging, fall back to using any inet address. 729 */ 730 IN_IFADDR_RLOCK(&in_ifa_tracker); 731 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 732 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 733 goto drop; 734 } 735 ifa_ref(&ia->ia_ifa); 736 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 737 match: 738 if (!enaddr) 739 enaddr = (u_int8_t *)IF_LLADDR(ifp); 740 carped = (ia->ia_ifa.ifa_carp != NULL); 741 myaddr = ia->ia_addr.sin_addr; 742 ifa_free(&ia->ia_ifa); 743 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 744 goto drop; /* it's from me, ignore it. */ 745 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 746 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 747 "%s!\n", inet_ntoa(isaddr)); 748 goto drop; 749 } 750 751 if (ifp->if_addrlen != ah->ar_hln) { 752 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 753 "i/f %d (ignored)\n", ifp->if_addrlen, 754 (u_char *) ar_sha(ah), ":", ah->ar_hln, 755 ifp->if_addrlen); 756 goto drop; 757 } 758 759 /* 760 * Warn if another host is using the same IP address, but only if the 761 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 762 * case we suppress the warning to avoid false positive complaints of 763 * potential misconfiguration. 764 */ 765 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 766 myaddr.s_addr != 0) { 767 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 768 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 769 inet_ntoa(isaddr), ifp->if_xname); 770 itaddr = myaddr; 771 ARPSTAT_INC(dupips); 772 goto reply; 773 } 774 if (ifp->if_flags & IFF_STATICARP) 775 goto reply; 776 777 bzero(&sin, sizeof(sin)); 778 sin.sin_len = sizeof(struct sockaddr_in); 779 sin.sin_family = AF_INET; 780 sin.sin_addr = isaddr; 781 IF_AFDATA_RLOCK(ifp); 782 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, (struct sockaddr *)&sin); 783 IF_AFDATA_RUNLOCK(ifp); 784 if (la != NULL) 785 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 786 else if (itaddr.s_addr == myaddr.s_addr) { 787 /* 788 * Reply to our address, but no lle exists yet. 789 * do we really have to create an entry? 790 */ 791 IF_AFDATA_WLOCK(ifp); 792 la = lla_create(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 793 arp_update_lle(ah, ifp, la); 794 IF_AFDATA_WUNLOCK(ifp); 795 arp_mark_lle_reachable(la); 796 LLE_WUNLOCK(la); 797 } 798 reply: 799 if (op != ARPOP_REQUEST) 800 goto drop; 801 ARPSTAT_INC(rxrequests); 802 803 if (itaddr.s_addr == myaddr.s_addr) { 804 /* Shortcut.. the receiving interface is the target. */ 805 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 806 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 807 } else { 808 struct llentry *lle = NULL; 809 810 sin.sin_addr = itaddr; 811 IF_AFDATA_RLOCK(ifp); 812 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 813 IF_AFDATA_RUNLOCK(ifp); 814 815 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 816 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 817 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln); 818 LLE_RUNLOCK(lle); 819 } else { 820 821 if (lle != NULL) 822 LLE_RUNLOCK(lle); 823 824 if (!V_arp_proxyall) 825 goto drop; 826 827 sin.sin_addr = itaddr; 828 /* XXX MRT use table 0 for arp reply */ 829 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 830 if (!rt) 831 goto drop; 832 833 /* 834 * Don't send proxies for nodes on the same interface 835 * as this one came out of, or we'll get into a fight 836 * over who claims what Ether address. 837 */ 838 if (!rt->rt_ifp || rt->rt_ifp == ifp) { 839 RTFREE_LOCKED(rt); 840 goto drop; 841 } 842 RTFREE_LOCKED(rt); 843 844 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 845 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 846 847 /* 848 * Also check that the node which sent the ARP packet 849 * is on the interface we expect it to be on. This 850 * avoids ARP chaos if an interface is connected to the 851 * wrong network. 852 */ 853 sin.sin_addr = isaddr; 854 855 /* XXX MRT use table 0 for arp checks */ 856 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0); 857 if (!rt) 858 goto drop; 859 if (rt->rt_ifp != ifp) { 860 ARP_LOG(LOG_INFO, "proxy: ignoring request" 861 " from %s via %s, expecting %s\n", 862 inet_ntoa(isaddr), ifp->if_xname, 863 rt->rt_ifp->if_xname); 864 RTFREE_LOCKED(rt); 865 goto drop; 866 } 867 RTFREE_LOCKED(rt); 868 869 #ifdef DEBUG_PROXY 870 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 871 #endif 872 } 873 } 874 875 if (itaddr.s_addr == myaddr.s_addr && 876 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 877 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 878 #ifdef DEBUG_LINKLOCAL 879 printf("arp: sending reply for link-local addr %s\n", 880 inet_ntoa(itaddr)); 881 #endif 882 m->m_flags |= M_BCAST; 883 m->m_flags &= ~M_MCAST; 884 } else { 885 /* default behaviour; never reply by broadcast. */ 886 m->m_flags &= ~(M_BCAST|M_MCAST); 887 } 888 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 889 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 890 ah->ar_op = htons(ARPOP_REPLY); 891 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 892 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 893 m->m_pkthdr.len = m->m_len; 894 m->m_pkthdr.rcvif = NULL; 895 sa.sa_family = AF_ARP; 896 sa.sa_len = 2; 897 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 898 (*ifp->if_output)(ifp, m, &sa, NULL); 899 ARPSTAT_INC(txreplies); 900 return; 901 902 drop: 903 m_freem(m); 904 } 905 #endif 906 907 /* 908 * Checks received arp data against existing @la. 909 * Updates lle state/performs notification if necessary. 910 */ 911 static void 912 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 913 int bridged, struct llentry *la) 914 { 915 struct sockaddr sa; 916 struct mbuf *m_hold, *m_hold_next; 917 918 LLE_WLOCK_ASSERT(la); 919 920 /* the following is not an error when doing bridging */ 921 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 922 if (log_arp_wrong_iface) 923 ARP_LOG(LOG_WARNING, "%s is on %s " 924 "but got reply from %*D on %s\n", 925 inet_ntoa(isaddr), 926 la->lle_tbl->llt_ifp->if_xname, 927 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 928 ifp->if_xname); 929 LLE_WUNLOCK(la); 930 return; 931 } 932 if ((la->la_flags & LLE_VALID) && 933 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) { 934 if (la->la_flags & LLE_STATIC) { 935 LLE_WUNLOCK(la); 936 if (log_arp_permanent_modify) 937 ARP_LOG(LOG_ERR, 938 "%*D attempts to modify " 939 "permanent entry for %s on %s\n", 940 ifp->if_addrlen, 941 (u_char *)ar_sha(ah), ":", 942 inet_ntoa(isaddr), ifp->if_xname); 943 return; 944 } 945 if (log_arp_movements) { 946 ARP_LOG(LOG_INFO, "%s moved from %*D " 947 "to %*D on %s\n", 948 inet_ntoa(isaddr), 949 ifp->if_addrlen, 950 (u_char *)&la->ll_addr, ":", 951 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 952 ifp->if_xname); 953 } 954 } 955 956 /* Check if something has changed */ 957 if (memcmp(&la->ll_addr, ar_sha(ah), ifp->if_addrlen) != 0 || 958 (la->la_flags & LLE_VALID) == 0) { 959 /* Perform real LLE update */ 960 /* use afdata WLOCK to update fields */ 961 LLE_ADDREF(la); 962 LLE_WUNLOCK(la); 963 IF_AFDATA_WLOCK(ifp); 964 LLE_WLOCK(la); 965 966 /* 967 * Since we droppped LLE lock, other thread might have deleted 968 * this lle. Check and return 969 */ 970 if ((la->la_flags & LLE_DELETED) != 0) { 971 IF_AFDATA_WUNLOCK(ifp); 972 LLE_FREE_LOCKED(la); 973 return; 974 } 975 976 /* Update data */ 977 arp_update_lle(ah, ifp, la); 978 979 IF_AFDATA_WUNLOCK(ifp); 980 LLE_REMREF(la); 981 } 982 983 arp_mark_lle_reachable(la); 984 985 /* 986 * The packets are all freed within the call to the output 987 * routine. 988 * 989 * NB: The lock MUST be released before the call to the 990 * output routine. 991 */ 992 if (la->la_hold != NULL) { 993 m_hold = la->la_hold; 994 la->la_hold = NULL; 995 la->la_numheld = 0; 996 lltable_fill_sa_entry(la, &sa); 997 LLE_WUNLOCK(la); 998 for (; m_hold != NULL; m_hold = m_hold_next) { 999 m_hold_next = m_hold->m_nextpkt; 1000 m_hold->m_nextpkt = NULL; 1001 /* Avoid confusing lower layers. */ 1002 m_clrprotoflags(m_hold); 1003 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1004 } 1005 } else 1006 LLE_WUNLOCK(la); 1007 } 1008 1009 /* 1010 * Updates @la fields used by fast path code. 1011 */ 1012 static void 1013 arp_update_lle(struct arphdr *ah, struct ifnet *ifp, struct llentry *la) 1014 { 1015 1016 memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen); 1017 la->la_flags |= LLE_VALID; 1018 } 1019 1020 static void 1021 arp_mark_lle_reachable(struct llentry *la) 1022 { 1023 int canceled; 1024 1025 LLE_WLOCK_ASSERT(la); 1026 1027 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1028 1029 if (!(la->la_flags & LLE_STATIC)) { 1030 LLE_ADDREF(la); 1031 la->la_expire = time_uptime + V_arpt_keep; 1032 canceled = callout_reset(&la->lle_timer, 1033 hz * V_arpt_keep, arptimer, la); 1034 if (canceled) 1035 LLE_REMREF(la); 1036 } 1037 la->la_asked = 0; 1038 la->la_preempt = V_arp_maxtries; 1039 } 1040 1041 void 1042 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1043 { 1044 struct llentry *lle; 1045 1046 if (ifa->ifa_carp != NULL) 1047 return; 1048 1049 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) { 1050 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 1051 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 1052 /* 1053 * interface address is considered static entry 1054 * because the output of the arp utility shows 1055 * that L2 entry as permanent 1056 */ 1057 IF_AFDATA_LOCK(ifp); 1058 lle = lla_create(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, 1059 (struct sockaddr *)IA_SIN(ifa)); 1060 IF_AFDATA_UNLOCK(ifp); 1061 if (lle == NULL) 1062 log(LOG_INFO, "arp_ifinit: cannot create arp " 1063 "entry for interface address\n"); 1064 else 1065 LLE_WUNLOCK(lle); 1066 } 1067 ifa->ifa_rtrequest = NULL; 1068 } 1069 1070 void 1071 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 1072 { 1073 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 1074 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 1075 &IA_SIN(ifa)->sin_addr, enaddr); 1076 ifa->ifa_rtrequest = NULL; 1077 } 1078 1079 static void 1080 arp_init(void) 1081 { 1082 1083 netisr_register(&arp_nh); 1084 } 1085 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 1086