1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 32 */ 33 34 /* 35 * Ethernet address resolution protocol. 36 * TODO: 37 * add "inuse/lock" bit (or ref. count) along with valid bit 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "opt_inet.h" 44 45 #include <sys/param.h> 46 #include <sys/eventhandler.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/queue.h> 50 #include <sys/sysctl.h> 51 #include <sys/systm.h> 52 #include <sys/mbuf.h> 53 #include <sys/malloc.h> 54 #include <sys/proc.h> 55 #include <sys/socket.h> 56 #include <sys/syslog.h> 57 58 #include <net/if.h> 59 #include <net/if_var.h> 60 #include <net/if_dl.h> 61 #include <net/if_private.h> 62 #include <net/if_types.h> 63 #include <net/netisr.h> 64 #include <net/ethernet.h> 65 #include <net/route.h> 66 #include <net/route/nhop.h> 67 #include <net/vnet.h> 68 69 #include <netinet/in.h> 70 #include <netinet/in_fib.h> 71 #include <netinet/in_var.h> 72 #include <net/if_llatbl.h> 73 #include <netinet/if_ether.h> 74 #ifdef INET 75 #include <netinet/ip_carp.h> 76 #endif 77 78 #include <security/mac/mac_framework.h> 79 80 #define SIN(s) ((const struct sockaddr_in *)(s)) 81 82 static struct timeval arp_lastlog; 83 static int arp_curpps; 84 static int arp_maxpps = 1; 85 86 /* Simple ARP state machine */ 87 enum arp_llinfo_state { 88 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 89 ARP_LLINFO_REACHABLE, /* LLE is valid */ 90 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 91 ARP_LLINFO_DELETED, /* LLE is deleted */ 92 }; 93 94 SYSCTL_DECL(_net_link_ether); 95 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, 96 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 97 ""); 98 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, 99 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 100 ""); 101 102 /* timer values */ 103 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 104 * minutes */ 105 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 106 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 107 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 108 * 20 seconds */ 109 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 110 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 111 VNET_PCPUSTAT_SYSINIT(arpstat); 112 113 #ifdef VIMAGE 114 VNET_PCPUSTAT_SYSUNINIT(arpstat); 115 #endif /* VIMAGE */ 116 117 VNET_DEFINE_STATIC(int, arp_maxhold) = 16; 118 119 #define V_arpt_keep VNET(arpt_keep) 120 #define V_arpt_down VNET(arpt_down) 121 #define V_arpt_rexmit VNET(arpt_rexmit) 122 #define V_arp_maxtries VNET(arp_maxtries) 123 #define V_arp_proxyall VNET(arp_proxyall) 124 #define V_arp_maxhold VNET(arp_maxhold) 125 126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 127 &VNET_NAME(arpt_keep), 0, 128 "ARP entry lifetime in seconds"); 129 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 130 &VNET_NAME(arp_maxtries), 0, 131 "ARP resolution attempts before returning error"); 132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 133 &VNET_NAME(arp_proxyall), 0, 134 "Enable proxy ARP for all suitable requests"); 135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 136 &VNET_NAME(arpt_down), 0, 137 "Incomplete ARP entry lifetime in seconds"); 138 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 139 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 140 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 141 &VNET_NAME(arp_maxhold), 0, 142 "Number of packets to hold per ARP entry"); 143 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 144 CTLFLAG_RW, &arp_maxpps, 0, 145 "Maximum number of remotely triggered ARP messages that can be " 146 "logged per second"); 147 148 /* 149 * Due to the exponential backoff algorithm used for the interval between GARP 150 * retransmissions, the maximum number of retransmissions is limited for 151 * sanity. This limit corresponds to a maximum interval between retransmissions 152 * of 2^16 seconds ~= 18 hours. 153 * 154 * Making this limit more dynamic is more complicated than worthwhile, 155 * especially since sending out GARPs spaced days apart would be of little 156 * use. A maximum dynamic limit would look something like: 157 * 158 * const int max = fls(INT_MAX / hz) - 1; 159 */ 160 #define MAX_GARP_RETRANSMITS 16 161 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 162 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 163 164 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 165 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 166 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 167 "Number of times to retransmit GARP packets;" 168 " 0 to disable, maximum of 16"); 169 170 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 171 #define V_arp_log_level VNET(arp_log_level) 172 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 173 &VNET_NAME(arp_log_level), 0, 174 "Minimum log(9) level for recording rate limited arp log messages. " 175 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 176 #define ARP_LOG(pri, ...) do { \ 177 if ((pri) <= V_arp_log_level && \ 178 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 179 log((pri), "arp: " __VA_ARGS__); \ 180 } while (0) 181 182 static void arpintr(struct mbuf *); 183 static void arptimer(void *); 184 #ifdef INET 185 static void in_arpinput(struct mbuf *); 186 #endif 187 188 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 189 struct ifnet *ifp, int bridged, struct llentry *la); 190 static void arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp); 191 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 192 193 static eventhandler_tag iflladdr_tag; 194 195 static const struct netisr_handler arp_nh = { 196 .nh_name = "arp", 197 .nh_handler = arpintr, 198 .nh_proto = NETISR_ARP, 199 .nh_policy = NETISR_POLICY_SOURCE, 200 }; 201 202 /* 203 * Timeout routine. Age arp_tab entries periodically. 204 */ 205 static void 206 arptimer(void *arg) 207 { 208 struct llentry *lle = (struct llentry *)arg; 209 struct ifnet *ifp; 210 211 if (lle->la_flags & LLE_STATIC) { 212 return; 213 } 214 LLE_WLOCK(lle); 215 if (callout_pending(&lle->lle_timer)) { 216 /* 217 * Here we are a bit odd here in the treatment of 218 * active/pending. If the pending bit is set, it got 219 * rescheduled before I ran. The active 220 * bit we ignore, since if it was stopped 221 * in ll_tablefree() and was currently running 222 * it would have return 0 so the code would 223 * not have deleted it since the callout could 224 * not be stopped so we want to go through 225 * with the delete here now. If the callout 226 * was restarted, the pending bit will be back on and 227 * we just want to bail since the callout_reset would 228 * return 1 and our reference would have been removed 229 * by arpresolve() below. 230 */ 231 LLE_WUNLOCK(lle); 232 return; 233 } 234 ifp = lle->lle_tbl->llt_ifp; 235 CURVNET_SET(ifp->if_vnet); 236 237 switch (lle->ln_state) { 238 case ARP_LLINFO_REACHABLE: 239 240 /* 241 * Expiration time is approaching. 242 * Request usage feedback from the datapath. 243 * Change state and re-schedule ourselves. 244 */ 245 llentry_request_feedback(lle); 246 lle->ln_state = ARP_LLINFO_VERIFY; 247 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 248 LLE_WUNLOCK(lle); 249 CURVNET_RESTORE(); 250 return; 251 case ARP_LLINFO_VERIFY: 252 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) { 253 /* Entry was used, issue refresh request */ 254 struct epoch_tracker et; 255 struct in_addr dst; 256 257 dst = lle->r_l3addr.addr4; 258 lle->la_preempt--; 259 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 260 LLE_WUNLOCK(lle); 261 NET_EPOCH_ENTER(et); 262 arprequest(ifp, NULL, &dst, NULL); 263 NET_EPOCH_EXIT(et); 264 CURVNET_RESTORE(); 265 return; 266 } 267 /* Nothing happened. Reschedule if not too late */ 268 if (lle->la_expire > time_uptime) { 269 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 270 LLE_WUNLOCK(lle); 271 CURVNET_RESTORE(); 272 return; 273 } 274 break; 275 case ARP_LLINFO_INCOMPLETE: 276 case ARP_LLINFO_DELETED: 277 break; 278 } 279 280 if ((lle->la_flags & LLE_DELETED) == 0) { 281 int evt; 282 283 if (lle->la_flags & LLE_VALID) 284 evt = LLENTRY_EXPIRED; 285 else 286 evt = LLENTRY_TIMEDOUT; 287 EVENTHANDLER_INVOKE(lle_event, lle, evt); 288 } 289 290 callout_stop(&lle->lle_timer); 291 292 /* XXX: LOR avoidance. We still have ref on lle. */ 293 LLE_WUNLOCK(lle); 294 IF_AFDATA_LOCK(ifp); 295 LLE_WLOCK(lle); 296 297 /* Guard against race with other llentry_free(). */ 298 if (lle->la_flags & LLE_LINKED) { 299 LLE_REMREF(lle); 300 lltable_unlink_entry(lle->lle_tbl, lle); 301 } 302 IF_AFDATA_UNLOCK(ifp); 303 304 size_t pkts_dropped = llentry_free(lle); 305 306 ARPSTAT_ADD(dropped, pkts_dropped); 307 ARPSTAT_INC(timeouts); 308 309 CURVNET_RESTORE(); 310 } 311 312 /* 313 * Stores link-layer header for @ifp in format suitable for if_output() 314 * into buffer @buf. Resulting header length is stored in @bufsize. 315 * 316 * Returns 0 on success. 317 */ 318 static int 319 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 320 size_t *bufsize) 321 { 322 struct if_encap_req ereq; 323 int error; 324 325 bzero(buf, *bufsize); 326 bzero(&ereq, sizeof(ereq)); 327 ereq.buf = buf; 328 ereq.bufsize = *bufsize; 329 ereq.rtype = IFENCAP_LL; 330 ereq.family = AF_ARP; 331 ereq.lladdr = ar_tha(ah); 332 ereq.hdata = (u_char *)ah; 333 if (bcast) 334 ereq.flags = IFENCAP_FLAG_BROADCAST; 335 error = ifp->if_requestencap(ifp, &ereq); 336 if (error == 0) 337 *bufsize = ereq.bufsize; 338 339 return (error); 340 } 341 342 /* 343 * Broadcast an ARP request. Caller specifies: 344 * - arp header source ip address 345 * - arp header target ip address 346 * - arp header source ethernet address 347 */ 348 static int 349 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 350 const struct in_addr *tip, u_char *enaddr) 351 { 352 struct mbuf *m; 353 struct arphdr *ah; 354 struct sockaddr sa; 355 u_char *carpaddr = NULL; 356 uint8_t linkhdr[LLE_MAX_LINKHDR]; 357 size_t linkhdrsize; 358 struct route ro; 359 int error; 360 361 NET_EPOCH_ASSERT(); 362 363 if (sip == NULL) { 364 /* 365 * The caller did not supply a source address, try to find 366 * a compatible one among those assigned to this interface. 367 */ 368 struct ifaddr *ifa; 369 370 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 371 if (ifa->ifa_addr->sa_family != AF_INET) 372 continue; 373 374 if (ifa->ifa_carp) { 375 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 376 continue; 377 sip = &IA_SIN(ifa)->sin_addr; 378 } else { 379 carpaddr = NULL; 380 sip = &IA_SIN(ifa)->sin_addr; 381 } 382 383 if (0 == ((sip->s_addr ^ tip->s_addr) & 384 IA_MASKSIN(ifa)->sin_addr.s_addr)) 385 break; /* found it. */ 386 } 387 if (sip == NULL) { 388 printf("%s: cannot find matching address\n", __func__); 389 return (EADDRNOTAVAIL); 390 } 391 } 392 if (enaddr == NULL) 393 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 394 395 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 396 return (ENOMEM); 397 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 398 2 * ifp->if_addrlen; 399 m->m_pkthdr.len = m->m_len; 400 M_ALIGN(m, m->m_len); 401 ah = mtod(m, struct arphdr *); 402 bzero((caddr_t)ah, m->m_len); 403 #ifdef MAC 404 mac_netinet_arp_send(ifp, m); 405 #endif 406 ah->ar_pro = htons(ETHERTYPE_IP); 407 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 408 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 409 ah->ar_op = htons(ARPOP_REQUEST); 410 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 411 bcopy(sip, ar_spa(ah), ah->ar_pln); 412 bcopy(tip, ar_tpa(ah), ah->ar_pln); 413 sa.sa_family = AF_ARP; 414 sa.sa_len = 2; 415 416 /* Calculate link header for sending frame */ 417 bzero(&ro, sizeof(ro)); 418 linkhdrsize = sizeof(linkhdr); 419 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 420 if (error != 0 && error != EAFNOSUPPORT) { 421 m_freem(m); 422 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 423 if_name(ifp), error); 424 return (error); 425 } 426 427 ro.ro_prepend = linkhdr; 428 ro.ro_plen = linkhdrsize; 429 ro.ro_flags = 0; 430 431 m->m_flags |= M_BCAST; 432 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 433 error = (*ifp->if_output)(ifp, m, &sa, &ro); 434 ARPSTAT_INC(txrequests); 435 if (error) { 436 ARPSTAT_INC(txerrors); 437 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 438 if_name(ifp), error); 439 } 440 return (error); 441 } 442 443 void 444 arprequest(struct ifnet *ifp, const struct in_addr *sip, 445 const struct in_addr *tip, u_char *enaddr) 446 { 447 448 (void) arprequest_internal(ifp, sip, tip, enaddr); 449 } 450 451 /* 452 * Resolve an IP address into an ethernet address - heavy version. 453 * Used internally by arpresolve(). 454 * We have already checked that we can't use an existing lle without 455 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 456 * 457 * On success, desten and pflags are filled in and the function returns 0; 458 * If the packet must be held pending resolution, we return EWOULDBLOCK 459 * On other errors, we return the corresponding error code. 460 * Note that m_freem() handles NULL. 461 */ 462 static int 463 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 464 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 465 struct llentry **plle) 466 { 467 struct llentry *la = NULL, *la_tmp; 468 int error, renew; 469 char *lladdr; 470 int ll_len; 471 472 NET_EPOCH_ASSERT(); 473 474 if (pflags != NULL) 475 *pflags = 0; 476 if (plle != NULL) 477 *plle = NULL; 478 479 if ((flags & LLE_CREATE) == 0) 480 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 481 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 482 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 483 if (la == NULL) { 484 char addrbuf[INET_ADDRSTRLEN]; 485 486 log(LOG_DEBUG, 487 "arpresolve: can't allocate llinfo for %s on %s\n", 488 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 489 if_name(ifp)); 490 m_freem(m); 491 return (EINVAL); 492 } 493 494 IF_AFDATA_WLOCK(ifp); 495 LLE_WLOCK(la); 496 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 497 /* Prefer ANY existing lle over newly-created one */ 498 if (la_tmp == NULL) 499 lltable_link_entry(LLTABLE(ifp), la); 500 IF_AFDATA_WUNLOCK(ifp); 501 if (la_tmp != NULL) { 502 lltable_free_entry(LLTABLE(ifp), la); 503 la = la_tmp; 504 } 505 } 506 if (la == NULL) { 507 m_freem(m); 508 return (EINVAL); 509 } 510 511 if ((la->la_flags & LLE_VALID) && 512 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 513 if (flags & LLE_ADDRONLY) { 514 lladdr = la->ll_addr; 515 ll_len = ifp->if_addrlen; 516 } else { 517 lladdr = la->r_linkdata; 518 ll_len = la->r_hdrlen; 519 } 520 bcopy(lladdr, desten, ll_len); 521 522 /* Notify LLE code that the entry was used by datapath */ 523 llentry_provide_feedback(la); 524 if (pflags != NULL) 525 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 526 if (plle) { 527 LLE_ADDREF(la); 528 *plle = la; 529 } 530 LLE_WUNLOCK(la); 531 return (0); 532 } 533 534 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 535 536 /* 537 * There is an arptab entry, but no ethernet address 538 * response yet. Add the mbuf to the list, dropping 539 * the oldest packet if we have exceeded the system 540 * setting. 541 */ 542 if (m != NULL) { 543 size_t dropped = lltable_append_entry_queue(la, m, V_arp_maxhold); 544 ARPSTAT_ADD(dropped, dropped); 545 } 546 547 /* 548 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 549 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 550 * if we have already sent arp_maxtries ARP requests. Retransmit the 551 * ARP request, but not faster than one request per second. 552 */ 553 if (la->la_asked < V_arp_maxtries) 554 error = EWOULDBLOCK; /* First request. */ 555 else 556 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 557 558 if (renew) { 559 int canceled, e; 560 561 LLE_ADDREF(la); 562 la->la_expire = time_uptime; 563 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 564 arptimer, la); 565 if (canceled) 566 LLE_REMREF(la); 567 la->la_asked++; 568 LLE_WUNLOCK(la); 569 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL); 570 /* 571 * Only overwrite 'error' in case of error; in case of success 572 * the proper return value was already set above. 573 */ 574 if (e != 0) 575 return (e); 576 return (error); 577 } 578 579 LLE_WUNLOCK(la); 580 return (error); 581 } 582 583 /* 584 * Lookups link header based on an IP address. 585 * On input: 586 * ifp is the interface we use 587 * is_gw != 0 if @dst represents gateway to some destination 588 * m is the mbuf. May be NULL if we don't have a packet. 589 * dst is the next hop, 590 * desten is the storage to put LL header. 591 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 592 * 593 * On success, full/partial link header and flags are filled in and 594 * the function returns 0. 595 * If the packet must be held pending resolution, we return EWOULDBLOCK 596 * On other errors, we return the corresponding error code. 597 * Note that m_freem() handles NULL. 598 */ 599 int 600 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 601 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 602 struct llentry **plle) 603 { 604 struct llentry *la = NULL; 605 606 NET_EPOCH_ASSERT(); 607 608 if (pflags != NULL) 609 *pflags = 0; 610 if (plle != NULL) 611 *plle = NULL; 612 613 if (m != NULL) { 614 if (m->m_flags & M_BCAST) { 615 /* broadcast */ 616 (void)memcpy(desten, 617 ifp->if_broadcastaddr, ifp->if_addrlen); 618 return (0); 619 } 620 if (m->m_flags & M_MCAST) { 621 /* multicast */ 622 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 623 return (0); 624 } 625 } 626 627 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 628 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 629 /* Entry found, let's copy lle info */ 630 bcopy(la->r_linkdata, desten, la->r_hdrlen); 631 if (pflags != NULL) 632 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 633 /* Notify the LLE handling code that the entry was used. */ 634 llentry_provide_feedback(la); 635 if (plle) { 636 LLE_ADDREF(la); 637 *plle = la; 638 LLE_WUNLOCK(la); 639 } 640 return (0); 641 } 642 if (plle && la) 643 LLE_WUNLOCK(la); 644 645 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 646 desten, pflags, plle)); 647 } 648 649 /* 650 * Common length and type checks are done here, 651 * then the protocol-specific routine is called. 652 */ 653 static void 654 arpintr(struct mbuf *m) 655 { 656 struct arphdr *ar; 657 struct ifnet *ifp; 658 char *layer; 659 int hlen; 660 661 ifp = m->m_pkthdr.rcvif; 662 663 if (m->m_len < sizeof(struct arphdr) && 664 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 665 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 666 if_name(ifp)); 667 return; 668 } 669 ar = mtod(m, struct arphdr *); 670 671 /* Check if length is sufficient */ 672 if (m->m_len < arphdr_len(ar)) { 673 m = m_pullup(m, arphdr_len(ar)); 674 if (m == NULL) { 675 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 676 if_name(ifp)); 677 return; 678 } 679 ar = mtod(m, struct arphdr *); 680 } 681 682 hlen = 0; 683 layer = ""; 684 switch (ntohs(ar->ar_hrd)) { 685 case ARPHRD_ETHER: 686 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 687 layer = "ethernet"; 688 break; 689 case ARPHRD_INFINIBAND: 690 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 691 layer = "infiniband"; 692 break; 693 case ARPHRD_IEEE1394: 694 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 695 layer = "firewire"; 696 697 /* 698 * Restrict too long hardware addresses. 699 * Currently we are capable of handling 20-byte 700 * addresses ( sizeof(lle->ll_addr) ) 701 */ 702 if (ar->ar_hln >= 20) 703 hlen = 16; 704 break; 705 default: 706 ARP_LOG(LOG_NOTICE, 707 "packet with unknown hardware format 0x%02d received on " 708 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 709 m_freem(m); 710 return; 711 } 712 713 if (hlen != 0 && hlen != ar->ar_hln) { 714 ARP_LOG(LOG_NOTICE, 715 "packet with invalid %s address length %d received on %s\n", 716 layer, ar->ar_hln, if_name(ifp)); 717 m_freem(m); 718 return; 719 } 720 721 ARPSTAT_INC(received); 722 switch (ntohs(ar->ar_pro)) { 723 #ifdef INET 724 case ETHERTYPE_IP: 725 in_arpinput(m); 726 return; 727 #endif 728 } 729 m_freem(m); 730 } 731 732 #ifdef INET 733 /* 734 * ARP for Internet protocols on 10 Mb/s Ethernet. 735 * Algorithm is that given in RFC 826. 736 * In addition, a sanity check is performed on the sender 737 * protocol address, to catch impersonators. 738 * We no longer handle negotiations for use of trailer protocol: 739 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 740 * along with IP replies if we wanted trailers sent to us, 741 * and also sent them in response to IP replies. 742 * This allowed either end to announce the desire to receive 743 * trailer packets. 744 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 745 * but formerly didn't normally send requests. 746 */ 747 static int log_arp_wrong_iface = 1; 748 static int log_arp_movements = 1; 749 static int log_arp_permanent_modify = 1; 750 static int allow_multicast = 0; 751 752 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 753 &log_arp_wrong_iface, 0, 754 "log arp packets arriving on the wrong interface"); 755 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 756 &log_arp_movements, 0, 757 "log arp replies from MACs different than the one in the cache"); 758 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 759 &log_arp_permanent_modify, 0, 760 "log arp replies from MACs different than the one in the permanent arp entry"); 761 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 762 &allow_multicast, 0, "accept multicast addresses"); 763 764 static void 765 in_arpinput(struct mbuf *m) 766 { 767 struct arphdr *ah; 768 struct ifnet *ifp = m->m_pkthdr.rcvif; 769 struct llentry *la = NULL, *la_tmp; 770 struct ifaddr *ifa; 771 struct in_ifaddr *ia; 772 struct sockaddr sa; 773 struct in_addr isaddr, itaddr, myaddr; 774 u_int8_t *enaddr = NULL; 775 int op; 776 int bridged = 0, is_bridge = 0; 777 int carped; 778 struct sockaddr_in sin; 779 struct sockaddr *dst; 780 struct nhop_object *nh; 781 uint8_t linkhdr[LLE_MAX_LINKHDR]; 782 struct route ro; 783 size_t linkhdrsize; 784 int lladdr_off; 785 int error; 786 char addrbuf[INET_ADDRSTRLEN]; 787 788 NET_EPOCH_ASSERT(); 789 790 sin.sin_len = sizeof(struct sockaddr_in); 791 sin.sin_family = AF_INET; 792 sin.sin_addr.s_addr = 0; 793 794 if (ifp->if_bridge) 795 bridged = 1; 796 if (ifp->if_type == IFT_BRIDGE) 797 is_bridge = 1; 798 799 /* 800 * We already have checked that mbuf contains enough contiguous data 801 * to hold entire arp message according to the arp header. 802 */ 803 ah = mtod(m, struct arphdr *); 804 805 /* 806 * ARP is only for IPv4 so we can reject packets with 807 * a protocol length not equal to an IPv4 address. 808 */ 809 if (ah->ar_pln != sizeof(struct in_addr)) { 810 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 811 sizeof(struct in_addr)); 812 goto drop; 813 } 814 815 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 816 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 817 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 818 goto drop; 819 } 820 821 op = ntohs(ah->ar_op); 822 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 823 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 824 825 if (op == ARPOP_REPLY) 826 ARPSTAT_INC(rxreplies); 827 828 /* 829 * For a bridge, we want to check the address irrespective 830 * of the receive interface. (This will change slightly 831 * when we have clusters of interfaces). 832 */ 833 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 834 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 835 ia->ia_ifp == ifp) && 836 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 837 (ia->ia_ifa.ifa_carp == NULL || 838 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 839 ifa_ref(&ia->ia_ifa); 840 goto match; 841 } 842 } 843 CK_LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 844 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 845 ia->ia_ifp == ifp) && 846 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 847 ifa_ref(&ia->ia_ifa); 848 goto match; 849 } 850 851 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 852 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 853 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 854 addr == ia->ia_addr.sin_addr.s_addr) 855 /* 856 * Check the case when bridge shares its MAC address with 857 * some of its children, so packets are claimed by bridge 858 * itself (bridge_input() does it first), but they are really 859 * meant to be destined to the bridge member. 860 */ 861 if (is_bridge) { 862 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 863 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 864 ifa_ref(&ia->ia_ifa); 865 ifp = ia->ia_ifp; 866 goto match; 867 } 868 } 869 } 870 #undef BDG_MEMBER_MATCHES_ARP 871 872 /* 873 * No match, use the first inet address on the receive interface 874 * as a dummy address for the rest of the function. 875 */ 876 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 877 if (ifa->ifa_addr->sa_family == AF_INET && 878 (ifa->ifa_carp == NULL || 879 (*carp_iamatch_p)(ifa, &enaddr))) { 880 ia = ifatoia(ifa); 881 ifa_ref(ifa); 882 goto match; 883 } 884 885 /* 886 * If bridging, fall back to using any inet address. 887 */ 888 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 889 goto drop; 890 ifa_ref(&ia->ia_ifa); 891 match: 892 if (!enaddr) 893 enaddr = (u_int8_t *)IF_LLADDR(ifp); 894 carped = (ia->ia_ifa.ifa_carp != NULL); 895 myaddr = ia->ia_addr.sin_addr; 896 ifa_free(&ia->ia_ifa); 897 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 898 goto drop; /* it's from me, ignore it. */ 899 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 900 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 901 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 902 goto drop; 903 } 904 905 if (ifp->if_addrlen != ah->ar_hln) { 906 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 907 "i/f %d (ignored)\n", ifp->if_addrlen, 908 (u_char *) ar_sha(ah), ":", ah->ar_hln, 909 ifp->if_addrlen); 910 goto drop; 911 } 912 913 /* 914 * Warn if another host is using the same IP address, but only if the 915 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 916 * case we suppress the warning to avoid false positive complaints of 917 * potential misconfiguration. 918 */ 919 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 920 myaddr.s_addr != 0) { 921 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 922 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 923 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 924 itaddr = myaddr; 925 ARPSTAT_INC(dupips); 926 goto reply; 927 } 928 if (ifp->if_flags & IFF_STATICARP) 929 goto reply; 930 931 bzero(&sin, sizeof(sin)); 932 sin.sin_len = sizeof(struct sockaddr_in); 933 sin.sin_family = AF_INET; 934 sin.sin_addr = isaddr; 935 dst = (struct sockaddr *)&sin; 936 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 937 if (la != NULL) 938 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 939 else if (itaddr.s_addr == myaddr.s_addr) { 940 /* 941 * Request/reply to our address, but no lle exists yet. 942 * Calculate full link prepend to use in lle. 943 */ 944 linkhdrsize = sizeof(linkhdr); 945 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 946 &linkhdrsize, &lladdr_off) != 0) 947 goto reply; 948 949 /* Allocate new entry */ 950 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 951 if (la == NULL) { 952 /* 953 * lle creation may fail if source address belongs 954 * to non-directly connected subnet. However, we 955 * will try to answer the request instead of dropping 956 * frame. 957 */ 958 goto reply; 959 } 960 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 961 lladdr_off); 962 963 IF_AFDATA_WLOCK(ifp); 964 LLE_WLOCK(la); 965 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 966 967 /* 968 * Check if lle still does not exists. 969 * If it does, that means that we either 970 * 1) have configured it explicitly, via 971 * 1a) 'arp -s' static entry or 972 * 1b) interface address static record 973 * or 974 * 2) it was the result of sending first packet to-host 975 * or 976 * 3) it was another arp reply packet we handled in 977 * different thread. 978 * 979 * In all cases except 3) we definitely need to prefer 980 * existing lle. For the sake of simplicity, prefer any 981 * existing lle over newly-create one. 982 */ 983 if (la_tmp == NULL) 984 lltable_link_entry(LLTABLE(ifp), la); 985 IF_AFDATA_WUNLOCK(ifp); 986 987 if (la_tmp == NULL) { 988 arp_mark_lle_reachable(la, ifp); 989 LLE_WUNLOCK(la); 990 } else { 991 /* Free newly-create entry and handle packet */ 992 lltable_free_entry(LLTABLE(ifp), la); 993 la = la_tmp; 994 la_tmp = NULL; 995 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 996 /* arp_check_update_lle() returns @la unlocked */ 997 } 998 la = NULL; 999 } 1000 reply: 1001 if (op != ARPOP_REQUEST) 1002 goto drop; 1003 ARPSTAT_INC(rxrequests); 1004 1005 if (itaddr.s_addr == myaddr.s_addr) { 1006 /* Shortcut.. the receiving interface is the target. */ 1007 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1008 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1009 } else { 1010 /* 1011 * Destination address is not ours. Check if 1012 * proxyarp entry exists or proxyarp is turned on globally. 1013 */ 1014 struct llentry *lle; 1015 1016 sin.sin_addr = itaddr; 1017 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1018 1019 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1020 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1021 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1022 LLE_RUNLOCK(lle); 1023 } else { 1024 if (lle != NULL) 1025 LLE_RUNLOCK(lle); 1026 1027 if (!V_arp_proxyall) 1028 goto drop; 1029 1030 NET_EPOCH_ASSERT(); 1031 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0); 1032 if (nh == NULL) 1033 goto drop; 1034 1035 /* 1036 * Don't send proxies for nodes on the same interface 1037 * as this one came out of, or we'll get into a fight 1038 * over who claims what Ether address. 1039 */ 1040 if (nh->nh_ifp == ifp) 1041 goto drop; 1042 1043 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1044 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1045 1046 /* 1047 * Also check that the node which sent the ARP packet 1048 * is on the interface we expect it to be on. This 1049 * avoids ARP chaos if an interface is connected to the 1050 * wrong network. 1051 */ 1052 1053 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0); 1054 if (nh == NULL) 1055 goto drop; 1056 if (nh->nh_ifp != ifp) { 1057 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1058 " from %s via %s\n", 1059 inet_ntoa_r(isaddr, addrbuf), 1060 ifp->if_xname); 1061 goto drop; 1062 } 1063 1064 #ifdef DEBUG_PROXY 1065 printf("arp: proxying for %s\n", 1066 inet_ntoa_r(itaddr, addrbuf)); 1067 #endif 1068 } 1069 } 1070 1071 if (itaddr.s_addr == myaddr.s_addr && 1072 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1073 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1074 #ifdef DEBUG_LINKLOCAL 1075 printf("arp: sending reply for link-local addr %s\n", 1076 inet_ntoa_r(itaddr, addrbuf)); 1077 #endif 1078 m->m_flags |= M_BCAST; 1079 m->m_flags &= ~M_MCAST; 1080 } else { 1081 /* default behaviour; never reply by broadcast. */ 1082 m->m_flags &= ~(M_BCAST|M_MCAST); 1083 } 1084 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1085 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1086 ah->ar_op = htons(ARPOP_REPLY); 1087 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1088 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1089 m->m_pkthdr.len = m->m_len; 1090 m->m_pkthdr.rcvif = NULL; 1091 sa.sa_family = AF_ARP; 1092 sa.sa_len = 2; 1093 1094 /* Calculate link header for sending frame */ 1095 bzero(&ro, sizeof(ro)); 1096 linkhdrsize = sizeof(linkhdr); 1097 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1098 1099 /* 1100 * arp_fillheader() may fail due to lack of support inside encap request 1101 * routing. This is not necessary an error, AF_ARP can/should be handled 1102 * by if_output(). 1103 */ 1104 if (error != 0 && error != EAFNOSUPPORT) { 1105 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1106 if_name(ifp), error); 1107 goto drop; 1108 } 1109 1110 ro.ro_prepend = linkhdr; 1111 ro.ro_plen = linkhdrsize; 1112 ro.ro_flags = 0; 1113 1114 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1115 (*ifp->if_output)(ifp, m, &sa, &ro); 1116 ARPSTAT_INC(txreplies); 1117 return; 1118 1119 drop: 1120 m_freem(m); 1121 } 1122 #endif 1123 1124 static struct mbuf * 1125 arp_grab_holdchain(struct llentry *la) 1126 { 1127 struct mbuf *chain; 1128 1129 LLE_WLOCK_ASSERT(la); 1130 1131 chain = la->la_hold; 1132 la->la_hold = NULL; 1133 la->la_numheld = 0; 1134 1135 return (chain); 1136 } 1137 1138 static void 1139 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain) 1140 { 1141 struct mbuf *m_hold, *m_hold_next; 1142 struct sockaddr_in sin; 1143 1144 NET_EPOCH_ASSERT(); 1145 1146 struct route ro = { 1147 .ro_prepend = la->r_linkdata, 1148 .ro_plen = la->r_hdrlen, 1149 }; 1150 1151 lltable_fill_sa_entry(la, (struct sockaddr *)&sin); 1152 1153 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) { 1154 m_hold_next = m_hold->m_nextpkt; 1155 m_hold->m_nextpkt = NULL; 1156 /* Avoid confusing lower layers. */ 1157 m_clrprotoflags(m_hold); 1158 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro); 1159 } 1160 } 1161 1162 /* 1163 * Checks received arp data against existing @la. 1164 * Updates lle state/performs notification if necessary. 1165 */ 1166 static void 1167 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1168 int bridged, struct llentry *la) 1169 { 1170 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1171 size_t linkhdrsize; 1172 int lladdr_off; 1173 char addrbuf[INET_ADDRSTRLEN]; 1174 1175 LLE_WLOCK_ASSERT(la); 1176 1177 /* the following is not an error when doing bridging */ 1178 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1179 if (log_arp_wrong_iface) 1180 ARP_LOG(LOG_WARNING, "%s is on %s " 1181 "but got reply from %*D on %s\n", 1182 inet_ntoa_r(isaddr, addrbuf), 1183 la->lle_tbl->llt_ifp->if_xname, 1184 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1185 ifp->if_xname); 1186 LLE_WUNLOCK(la); 1187 return; 1188 } 1189 if ((la->la_flags & LLE_VALID) && 1190 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1191 if (la->la_flags & LLE_STATIC) { 1192 LLE_WUNLOCK(la); 1193 if (log_arp_permanent_modify) 1194 ARP_LOG(LOG_ERR, 1195 "%*D attempts to modify " 1196 "permanent entry for %s on %s\n", 1197 ifp->if_addrlen, 1198 (u_char *)ar_sha(ah), ":", 1199 inet_ntoa_r(isaddr, addrbuf), 1200 ifp->if_xname); 1201 return; 1202 } 1203 if (log_arp_movements) { 1204 ARP_LOG(LOG_INFO, "%s moved from %*D " 1205 "to %*D on %s\n", 1206 inet_ntoa_r(isaddr, addrbuf), 1207 ifp->if_addrlen, 1208 (u_char *)la->ll_addr, ":", 1209 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1210 ifp->if_xname); 1211 } 1212 } 1213 1214 /* Calculate full link prepend to use in lle */ 1215 linkhdrsize = sizeof(linkhdr); 1216 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1217 &linkhdrsize, &lladdr_off) != 0) { 1218 LLE_WUNLOCK(la); 1219 return; 1220 } 1221 1222 /* Check if something has changed */ 1223 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1224 (la->la_flags & LLE_VALID) == 0) { 1225 /* Try to perform LLE update */ 1226 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1227 lladdr_off) == 0) { 1228 LLE_WUNLOCK(la); 1229 return; 1230 } 1231 1232 /* Clear fast path feedback request if set */ 1233 llentry_mark_used(la); 1234 } 1235 1236 arp_mark_lle_reachable(la, ifp); 1237 1238 /* 1239 * The packets are all freed within the call to the output 1240 * routine. 1241 * 1242 * NB: The lock MUST be released before the call to the 1243 * output routine. 1244 */ 1245 if (la->la_hold != NULL) { 1246 struct mbuf *chain; 1247 1248 chain = arp_grab_holdchain(la); 1249 LLE_WUNLOCK(la); 1250 arp_flush_holdchain(ifp, la, chain); 1251 } else 1252 LLE_WUNLOCK(la); 1253 } 1254 1255 static void 1256 arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp) 1257 { 1258 int canceled, wtime; 1259 1260 LLE_WLOCK_ASSERT(la); 1261 1262 la->ln_state = ARP_LLINFO_REACHABLE; 1263 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1264 1265 if ((ifp->if_flags & IFF_STICKYARP) != 0) 1266 la->la_flags |= LLE_STATIC; 1267 1268 if (!(la->la_flags & LLE_STATIC)) { 1269 LLE_ADDREF(la); 1270 la->la_expire = time_uptime + V_arpt_keep; 1271 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1272 if (wtime < 0) 1273 wtime = V_arpt_keep; 1274 canceled = callout_reset(&la->lle_timer, 1275 hz * wtime, arptimer, la); 1276 if (canceled) 1277 LLE_REMREF(la); 1278 } 1279 la->la_asked = 0; 1280 la->la_preempt = V_arp_maxtries; 1281 } 1282 1283 /* 1284 * Add permanent link-layer record for given interface address. 1285 */ 1286 static __noinline void 1287 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1288 { 1289 struct llentry *lle, *lle_tmp; 1290 1291 /* 1292 * Interface address LLE record is considered static 1293 * because kernel code relies on LLE_STATIC flag to check 1294 * if these entries can be rewriten by arp updates. 1295 */ 1296 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1297 if (lle == NULL) { 1298 log(LOG_INFO, "arp_ifinit: cannot create arp " 1299 "entry for interface address\n"); 1300 return; 1301 } 1302 1303 IF_AFDATA_WLOCK(ifp); 1304 LLE_WLOCK(lle); 1305 /* Unlink any entry if exists */ 1306 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1307 if (lle_tmp != NULL) 1308 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1309 1310 lltable_link_entry(LLTABLE(ifp), lle); 1311 IF_AFDATA_WUNLOCK(ifp); 1312 1313 if (lle_tmp != NULL) 1314 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1315 1316 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1317 LLE_WUNLOCK(lle); 1318 if (lle_tmp != NULL) 1319 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1320 } 1321 1322 /* 1323 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1324 * of valid values. 1325 */ 1326 static int 1327 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1328 { 1329 int error; 1330 int rexmit_count = *(int *)arg1; 1331 1332 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1333 1334 /* Enforce limits on any new value that may have been set. */ 1335 if (!error && req->newptr) { 1336 /* A new value was set. */ 1337 if (rexmit_count < 0) { 1338 rexmit_count = 0; 1339 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1340 rexmit_count = MAX_GARP_RETRANSMITS; 1341 } 1342 *(int *)arg1 = rexmit_count; 1343 } 1344 1345 return (error); 1346 } 1347 1348 /* 1349 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1350 * retransmit it again. A pending callout owns a reference to the ifa. 1351 */ 1352 static void 1353 garp_rexmit(void *arg) 1354 { 1355 struct in_ifaddr *ia = arg; 1356 1357 if (callout_pending(&ia->ia_garp_timer) || 1358 !callout_active(&ia->ia_garp_timer)) { 1359 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1360 ifa_free(&ia->ia_ifa); 1361 return; 1362 } 1363 1364 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1365 1366 /* 1367 * Drop lock while the ARP request is generated. 1368 */ 1369 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1370 1371 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1372 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1373 1374 /* 1375 * Increment the count of retransmissions. If the count has reached the 1376 * maximum value, stop sending the GARP packets. Otherwise, schedule 1377 * the callout to retransmit another GARP packet. 1378 */ 1379 ++ia->ia_garp_count; 1380 if (ia->ia_garp_count >= garp_rexmit_count) { 1381 ifa_free(&ia->ia_ifa); 1382 } else { 1383 int rescheduled; 1384 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1385 rescheduled = callout_reset(&ia->ia_garp_timer, 1386 (1 << ia->ia_garp_count) * hz, 1387 garp_rexmit, ia); 1388 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1389 if (rescheduled) { 1390 ifa_free(&ia->ia_ifa); 1391 } 1392 } 1393 1394 CURVNET_RESTORE(); 1395 } 1396 1397 /* 1398 * Start the GARP retransmit timer. 1399 * 1400 * A single GARP is always transmitted when an IPv4 address is added 1401 * to an interface and that is usually sufficient. However, in some 1402 * circumstances, such as when a shared address is passed between 1403 * cluster nodes, this single GARP may occasionally be dropped or 1404 * lost. This can lead to neighbors on the network link working with a 1405 * stale ARP cache and sending packets destined for that address to 1406 * the node that previously owned the address, which may not respond. 1407 * 1408 * To avoid this situation, GARP retransmits can be enabled by setting 1409 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1410 * than zero. The setting represents the maximum number of 1411 * retransmissions. The interval between retransmissions is calculated 1412 * using an exponential backoff algorithm, doubling each time, so the 1413 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1414 */ 1415 static void 1416 garp_timer_start(struct ifaddr *ifa) 1417 { 1418 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1419 1420 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1421 ia->ia_garp_count = 0; 1422 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1423 garp_rexmit, ia) == 0) { 1424 ifa_ref(ifa); 1425 } 1426 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1427 } 1428 1429 void 1430 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1431 { 1432 struct epoch_tracker et; 1433 const struct sockaddr_in *dst_in; 1434 const struct sockaddr *dst; 1435 1436 if (ifa->ifa_carp != NULL) 1437 return; 1438 1439 dst = ifa->ifa_addr; 1440 dst_in = (const struct sockaddr_in *)dst; 1441 1442 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1443 return; 1444 NET_EPOCH_ENTER(et); 1445 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1446 NET_EPOCH_EXIT(et); 1447 if (garp_rexmit_count > 0) { 1448 garp_timer_start(ifa); 1449 } 1450 1451 arp_add_ifa_lle(ifp, dst); 1452 } 1453 1454 void 1455 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1456 { 1457 1458 if (ntohl(addr.s_addr) != INADDR_ANY) 1459 arprequest(ifp, &addr, &addr, enaddr); 1460 } 1461 1462 /* 1463 * Sends gratuitous ARPs for each ifaddr to notify other 1464 * nodes about the address change. 1465 */ 1466 static __noinline void 1467 arp_handle_ifllchange(struct ifnet *ifp) 1468 { 1469 struct ifaddr *ifa; 1470 1471 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1472 if (ifa->ifa_addr->sa_family == AF_INET) 1473 arp_ifinit(ifp, ifa); 1474 } 1475 } 1476 1477 /* 1478 * A handler for interface link layer address change event. 1479 */ 1480 static void 1481 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1482 { 1483 /* if_bridge can update its lladdr during if_vmove(), after we've done 1484 * if_detach_internal()/dom_ifdetach(). */ 1485 if (ifp->if_afdata[AF_INET] == NULL) 1486 return; 1487 1488 lltable_update_ifaddr(LLTABLE(ifp)); 1489 1490 if ((ifp->if_flags & IFF_UP) != 0) 1491 arp_handle_ifllchange(ifp); 1492 } 1493 1494 static void 1495 vnet_arp_init(void) 1496 { 1497 1498 if (IS_DEFAULT_VNET(curvnet)) { 1499 netisr_register(&arp_nh); 1500 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1501 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1502 } 1503 #ifdef VIMAGE 1504 else 1505 netisr_register_vnet(&arp_nh); 1506 #endif 1507 } 1508 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1509 vnet_arp_init, 0); 1510 1511 #ifdef VIMAGE 1512 /* 1513 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1514 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1515 */ 1516 static void 1517 vnet_arp_destroy(__unused void *arg) 1518 { 1519 1520 netisr_unregister_vnet(&arp_nh); 1521 } 1522 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1523 vnet_arp_destroy, NULL); 1524 #endif 1525