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