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 32 /* 33 * Ethernet address resolution protocol. 34 * TODO: 35 * add "inuse/lock" bit (or ref. count) along with valid bit 36 */ 37 38 #include <sys/cdefs.h> 39 #include "opt_inet.h" 40 41 #include <sys/param.h> 42 #include <sys/eventhandler.h> 43 #include <sys/kernel.h> 44 #include <sys/lock.h> 45 #include <sys/queue.h> 46 #include <sys/sysctl.h> 47 #include <sys/systm.h> 48 #include <sys/mbuf.h> 49 #include <sys/malloc.h> 50 #include <sys/proc.h> 51 #include <sys/socket.h> 52 #include <sys/syslog.h> 53 54 #include <net/if.h> 55 #include <net/if_var.h> 56 #include <net/if_dl.h> 57 #include <net/if_private.h> 58 #include <net/if_types.h> 59 #include <net/netisr.h> 60 #include <net/ethernet.h> 61 #include <net/route.h> 62 #include <net/route/nhop.h> 63 #include <net/vnet.h> 64 65 #include <netinet/in.h> 66 #include <netinet/in_fib.h> 67 #include <netinet/in_var.h> 68 #include <net/if_llatbl.h> 69 #include <netinet/if_ether.h> 70 #ifdef INET 71 #include <netinet/ip_carp.h> 72 #endif 73 74 #include <security/mac/mac_framework.h> 75 76 #define SIN(s) ((const struct sockaddr_in *)(s)) 77 78 static struct timeval arp_lastlog; 79 static int arp_curpps; 80 static int arp_maxpps = 1; 81 82 /* Simple ARP state machine */ 83 enum arp_llinfo_state { 84 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 85 ARP_LLINFO_REACHABLE, /* LLE is valid */ 86 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 87 ARP_LLINFO_DELETED, /* LLE is deleted */ 88 }; 89 90 SYSCTL_DECL(_net_link_ether); 91 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, 92 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 93 ""); 94 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, 95 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 96 ""); 97 98 /* timer values */ 99 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 100 * minutes */ 101 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 102 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 103 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 104 * 20 seconds */ 105 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 106 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 107 VNET_PCPUSTAT_SYSINIT(arpstat); 108 109 #ifdef VIMAGE 110 VNET_PCPUSTAT_SYSUNINIT(arpstat); 111 #endif /* VIMAGE */ 112 113 VNET_DEFINE_STATIC(int, arp_maxhold) = 16; 114 115 #define V_arpt_keep VNET(arpt_keep) 116 #define V_arpt_down VNET(arpt_down) 117 #define V_arpt_rexmit VNET(arpt_rexmit) 118 #define V_arp_maxtries VNET(arp_maxtries) 119 #define V_arp_proxyall VNET(arp_proxyall) 120 #define V_arp_maxhold VNET(arp_maxhold) 121 122 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 123 &VNET_NAME(arpt_keep), 0, 124 "ARP entry lifetime in seconds"); 125 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 126 &VNET_NAME(arp_maxtries), 0, 127 "ARP resolution attempts before returning error"); 128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 129 &VNET_NAME(arp_proxyall), 0, 130 "Enable proxy ARP for all suitable requests"); 131 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 132 &VNET_NAME(arpt_down), 0, 133 "Incomplete ARP entry lifetime in seconds"); 134 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 135 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 136 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(arp_maxhold), 0, 138 "Number of packets to hold per ARP entry"); 139 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 140 CTLFLAG_RW, &arp_maxpps, 0, 141 "Maximum number of remotely triggered ARP messages that can be " 142 "logged per second"); 143 144 /* 145 * Due to the exponential backoff algorithm used for the interval between GARP 146 * retransmissions, the maximum number of retransmissions is limited for 147 * sanity. This limit corresponds to a maximum interval between retransmissions 148 * of 2^16 seconds ~= 18 hours. 149 * 150 * Making this limit more dynamic is more complicated than worthwhile, 151 * especially since sending out GARPs spaced days apart would be of little 152 * use. A maximum dynamic limit would look something like: 153 * 154 * const int max = fls(INT_MAX / hz) - 1; 155 */ 156 #define MAX_GARP_RETRANSMITS 16 157 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 158 VNET_DEFINE_STATIC(int, garp_rexmit_count) = 0; /* GARP retransmission setting. */ 159 #define V_garp_rexmit_count VNET(garp_rexmit_count) 160 161 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 162 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE|CTLFLAG_VNET, 163 &VNET_NAME(garp_rexmit_count), 0, sysctl_garp_rexmit, "I", 164 "Number of times to retransmit GARP packets;" 165 " 0 to disable, maximum of 16"); 166 167 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 168 #define V_arp_log_level VNET(arp_log_level) 169 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 170 &VNET_NAME(arp_log_level), 0, 171 "Minimum log(9) level for recording rate limited arp log messages. " 172 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 173 #define ARP_LOG(pri, ...) do { \ 174 if ((pri) <= V_arp_log_level && \ 175 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 176 log((pri), "arp: " __VA_ARGS__); \ 177 } while (0) 178 179 static void arpintr(struct mbuf *); 180 static void arptimer(void *); 181 #ifdef INET 182 static void in_arpinput(struct mbuf *); 183 #endif 184 185 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 186 struct ifnet *ifp, int bridged, struct llentry *la); 187 static void arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp); 188 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 189 190 static eventhandler_tag iflladdr_tag; 191 192 static const struct netisr_handler arp_nh = { 193 .nh_name = "arp", 194 .nh_handler = arpintr, 195 .nh_proto = NETISR_ARP, 196 .nh_policy = NETISR_POLICY_SOURCE, 197 }; 198 199 /* 200 * Timeout routine. Age arp_tab entries periodically. 201 */ 202 static void 203 arptimer(void *arg) 204 { 205 struct llentry *lle = (struct llentry *)arg; 206 struct ifnet *ifp; 207 208 if (lle->la_flags & LLE_STATIC) { 209 return; 210 } 211 LLE_WLOCK(lle); 212 if (callout_pending(&lle->lle_timer)) { 213 /* 214 * Here we are a bit odd here in the treatment of 215 * active/pending. If the pending bit is set, it got 216 * rescheduled before I ran. The active 217 * bit we ignore, since if it was stopped 218 * in ll_tablefree() and was currently running 219 * it would have return 0 so the code would 220 * not have deleted it since the callout could 221 * not be stopped so we want to go through 222 * with the delete here now. If the callout 223 * was restarted, the pending bit will be back on and 224 * we just want to bail since the callout_reset would 225 * return 1 and our reference would have been removed 226 * by arpresolve() below. 227 */ 228 LLE_WUNLOCK(lle); 229 return; 230 } 231 ifp = lle->lle_tbl->llt_ifp; 232 CURVNET_SET(ifp->if_vnet); 233 234 switch (lle->ln_state) { 235 case ARP_LLINFO_REACHABLE: 236 237 /* 238 * Expiration time is approaching. 239 * Request usage feedback from the datapath. 240 * Change state and re-schedule ourselves. 241 */ 242 llentry_request_feedback(lle); 243 lle->ln_state = ARP_LLINFO_VERIFY; 244 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 245 LLE_WUNLOCK(lle); 246 CURVNET_RESTORE(); 247 return; 248 case ARP_LLINFO_VERIFY: 249 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) { 250 /* Entry was used, issue refresh request */ 251 struct epoch_tracker et; 252 struct in_addr dst; 253 254 dst = lle->r_l3addr.addr4; 255 lle->la_preempt--; 256 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 257 LLE_WUNLOCK(lle); 258 NET_EPOCH_ENTER(et); 259 arprequest(ifp, NULL, &dst, NULL); 260 NET_EPOCH_EXIT(et); 261 CURVNET_RESTORE(); 262 return; 263 } 264 /* Nothing happened. Reschedule if not too late */ 265 if (lle->la_expire > time_uptime) { 266 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 267 LLE_WUNLOCK(lle); 268 CURVNET_RESTORE(); 269 return; 270 } 271 break; 272 case ARP_LLINFO_INCOMPLETE: 273 case ARP_LLINFO_DELETED: 274 break; 275 } 276 277 if ((lle->la_flags & LLE_DELETED) == 0) { 278 int evt; 279 280 if (lle->la_flags & LLE_VALID) 281 evt = LLENTRY_EXPIRED; 282 else 283 evt = LLENTRY_TIMEDOUT; 284 EVENTHANDLER_INVOKE(lle_event, lle, evt); 285 } 286 287 callout_stop(&lle->lle_timer); 288 289 /* XXX: LOR avoidance. We still have ref on lle. */ 290 LLE_WUNLOCK(lle); 291 IF_AFDATA_LOCK(ifp); 292 LLE_WLOCK(lle); 293 294 /* Guard against race with other llentry_free(). */ 295 if (lle->la_flags & LLE_LINKED) { 296 LLE_REMREF(lle); 297 lltable_unlink_entry(lle->lle_tbl, lle); 298 } 299 IF_AFDATA_UNLOCK(ifp); 300 301 size_t pkts_dropped = llentry_free(lle); 302 303 ARPSTAT_ADD(dropped, pkts_dropped); 304 ARPSTAT_INC(timeouts); 305 306 CURVNET_RESTORE(); 307 } 308 309 /* 310 * Stores link-layer header for @ifp in format suitable for if_output() 311 * into buffer @buf. Resulting header length is stored in @bufsize. 312 * 313 * Returns 0 on success. 314 */ 315 static int 316 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 317 size_t *bufsize) 318 { 319 struct if_encap_req ereq; 320 int error; 321 322 bzero(buf, *bufsize); 323 bzero(&ereq, sizeof(ereq)); 324 ereq.buf = buf; 325 ereq.bufsize = *bufsize; 326 ereq.rtype = IFENCAP_LL; 327 ereq.family = AF_ARP; 328 ereq.lladdr = ar_tha(ah); 329 ereq.hdata = (u_char *)ah; 330 if (bcast) 331 ereq.flags = IFENCAP_FLAG_BROADCAST; 332 error = ifp->if_requestencap(ifp, &ereq); 333 if (error == 0) 334 *bufsize = ereq.bufsize; 335 336 return (error); 337 } 338 339 /* 340 * Broadcast an ARP request. Caller specifies: 341 * - arp header source ip address 342 * - arp header target ip address 343 * - arp header source ethernet address 344 */ 345 static int 346 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 347 const struct in_addr *tip, u_char *enaddr) 348 { 349 struct mbuf *m; 350 struct arphdr *ah; 351 struct sockaddr sa; 352 u_char *carpaddr = NULL; 353 uint8_t linkhdr[LLE_MAX_LINKHDR]; 354 size_t linkhdrsize; 355 struct route ro; 356 int error; 357 358 NET_EPOCH_ASSERT(); 359 360 if (sip == NULL) { 361 /* 362 * The caller did not supply a source address, try to find 363 * a compatible one among those assigned to this interface. 364 */ 365 struct ifaddr *ifa; 366 367 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 368 if (ifa->ifa_addr->sa_family != AF_INET) 369 continue; 370 371 if (ifa->ifa_carp) { 372 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 373 continue; 374 sip = &IA_SIN(ifa)->sin_addr; 375 } else { 376 carpaddr = NULL; 377 sip = &IA_SIN(ifa)->sin_addr; 378 } 379 380 if (0 == ((sip->s_addr ^ tip->s_addr) & 381 IA_MASKSIN(ifa)->sin_addr.s_addr)) 382 break; /* found it. */ 383 } 384 if (sip == NULL) { 385 printf("%s: cannot find matching address\n", __func__); 386 return (EADDRNOTAVAIL); 387 } 388 } 389 if (enaddr == NULL) 390 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 391 392 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 393 return (ENOMEM); 394 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 395 2 * ifp->if_addrlen; 396 m->m_pkthdr.len = m->m_len; 397 M_ALIGN(m, m->m_len); 398 ah = mtod(m, struct arphdr *); 399 bzero((caddr_t)ah, m->m_len); 400 #ifdef MAC 401 mac_netinet_arp_send(ifp, m); 402 #endif 403 ah->ar_pro = htons(ETHERTYPE_IP); 404 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 405 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 406 ah->ar_op = htons(ARPOP_REQUEST); 407 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 408 bcopy(sip, ar_spa(ah), ah->ar_pln); 409 bcopy(tip, ar_tpa(ah), ah->ar_pln); 410 sa.sa_family = AF_ARP; 411 sa.sa_len = 2; 412 413 /* Calculate link header for sending frame */ 414 bzero(&ro, sizeof(ro)); 415 linkhdrsize = sizeof(linkhdr); 416 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 417 if (error != 0 && error != EAFNOSUPPORT) { 418 m_freem(m); 419 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 420 if_name(ifp), error); 421 return (error); 422 } 423 424 ro.ro_prepend = linkhdr; 425 ro.ro_plen = linkhdrsize; 426 ro.ro_flags = 0; 427 428 m->m_flags |= M_BCAST; 429 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 430 error = (*ifp->if_output)(ifp, m, &sa, &ro); 431 ARPSTAT_INC(txrequests); 432 if (error) { 433 ARPSTAT_INC(txerrors); 434 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 435 if_name(ifp), error); 436 } 437 return (error); 438 } 439 440 void 441 arprequest(struct ifnet *ifp, const struct in_addr *sip, 442 const struct in_addr *tip, u_char *enaddr) 443 { 444 445 (void) arprequest_internal(ifp, sip, tip, enaddr); 446 } 447 448 /* 449 * Resolve an IP address into an ethernet address - heavy version. 450 * Used internally by arpresolve(). 451 * We have already checked that we can't use an existing lle without 452 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 453 * 454 * On success, desten and pflags are filled in and the function returns 0; 455 * If the packet must be held pending resolution, we return EWOULDBLOCK 456 * On other errors, we return the corresponding error code. 457 * Note that m_freem() handles NULL. 458 */ 459 static int 460 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 461 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 462 struct llentry **plle) 463 { 464 struct llentry *la = NULL, *la_tmp; 465 int error, renew; 466 char *lladdr; 467 int ll_len; 468 469 NET_EPOCH_ASSERT(); 470 471 if (pflags != NULL) 472 *pflags = 0; 473 if (plle != NULL) 474 *plle = NULL; 475 476 if ((flags & LLE_CREATE) == 0) 477 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 478 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 479 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 480 if (la == NULL) { 481 char addrbuf[INET_ADDRSTRLEN]; 482 483 log(LOG_DEBUG, 484 "arpresolve: can't allocate llinfo for %s on %s\n", 485 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 486 if_name(ifp)); 487 m_freem(m); 488 return (EINVAL); 489 } 490 491 IF_AFDATA_WLOCK(ifp); 492 LLE_WLOCK(la); 493 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 494 /* Prefer ANY existing lle over newly-created one */ 495 if (la_tmp == NULL) 496 lltable_link_entry(LLTABLE(ifp), la); 497 IF_AFDATA_WUNLOCK(ifp); 498 if (la_tmp != NULL) { 499 lltable_free_entry(LLTABLE(ifp), la); 500 la = la_tmp; 501 } 502 } 503 if (la == NULL) { 504 m_freem(m); 505 return (EINVAL); 506 } 507 508 if ((la->la_flags & LLE_VALID) && 509 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 510 if (flags & LLE_ADDRONLY) { 511 lladdr = la->ll_addr; 512 ll_len = ifp->if_addrlen; 513 } else { 514 lladdr = la->r_linkdata; 515 ll_len = la->r_hdrlen; 516 } 517 bcopy(lladdr, desten, ll_len); 518 519 /* Notify LLE code that the entry was used by datapath */ 520 llentry_provide_feedback(la); 521 if (pflags != NULL) 522 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 523 if (plle) { 524 LLE_ADDREF(la); 525 *plle = la; 526 } 527 LLE_WUNLOCK(la); 528 return (0); 529 } 530 531 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 532 533 /* 534 * There is an arptab entry, but no ethernet address 535 * response yet. Add the mbuf to the list, dropping 536 * the oldest packet if we have exceeded the system 537 * setting. 538 */ 539 if (m != NULL) { 540 size_t dropped = lltable_append_entry_queue(la, m, V_arp_maxhold); 541 ARPSTAT_ADD(dropped, dropped); 542 } 543 544 /* 545 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 546 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 547 * if we have already sent arp_maxtries ARP requests. Retransmit the 548 * ARP request, but not faster than one request per second. 549 */ 550 if (la->la_asked < V_arp_maxtries) 551 error = EWOULDBLOCK; /* First request. */ 552 else 553 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 554 555 if (renew) { 556 int canceled, e; 557 558 LLE_ADDREF(la); 559 la->la_expire = time_uptime; 560 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 561 arptimer, la); 562 if (canceled) 563 LLE_REMREF(la); 564 la->la_asked++; 565 LLE_WUNLOCK(la); 566 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL); 567 /* 568 * Only overwrite 'error' in case of error; in case of success 569 * the proper return value was already set above. 570 */ 571 if (e != 0) 572 return (e); 573 return (error); 574 } 575 576 LLE_WUNLOCK(la); 577 return (error); 578 } 579 580 /* 581 * Lookups link header based on an IP address. 582 * On input: 583 * ifp is the interface we use 584 * is_gw != 0 if @dst represents gateway to some destination 585 * m is the mbuf. May be NULL if we don't have a packet. 586 * dst is the next hop, 587 * desten is the storage to put LL header. 588 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 589 * 590 * On success, full/partial link header and flags are filled in and 591 * the function returns 0. 592 * If the packet must be held pending resolution, we return EWOULDBLOCK 593 * On other errors, we return the corresponding error code. 594 * Note that m_freem() handles NULL. 595 */ 596 int 597 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 598 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 599 struct llentry **plle) 600 { 601 struct llentry *la = NULL; 602 603 NET_EPOCH_ASSERT(); 604 605 if (pflags != NULL) 606 *pflags = 0; 607 if (plle != NULL) 608 *plle = NULL; 609 610 if (m != NULL) { 611 if (m->m_flags & M_BCAST) { 612 /* broadcast */ 613 (void)memcpy(desten, 614 ifp->if_broadcastaddr, ifp->if_addrlen); 615 return (0); 616 } 617 if (m->m_flags & M_MCAST) { 618 /* multicast */ 619 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 620 return (0); 621 } 622 } 623 624 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 625 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 626 /* Entry found, let's copy lle info */ 627 bcopy(la->r_linkdata, desten, la->r_hdrlen); 628 if (pflags != NULL) 629 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 630 /* Notify the LLE handling code that the entry was used. */ 631 llentry_provide_feedback(la); 632 if (plle) { 633 LLE_ADDREF(la); 634 *plle = la; 635 LLE_WUNLOCK(la); 636 } 637 return (0); 638 } 639 if (plle && la) 640 LLE_WUNLOCK(la); 641 642 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 643 desten, pflags, plle)); 644 } 645 646 /* 647 * Common length and type checks are done here, 648 * then the protocol-specific routine is called. 649 */ 650 static void 651 arpintr(struct mbuf *m) 652 { 653 struct arphdr *ar; 654 struct ifnet *ifp; 655 char *layer; 656 int hlen; 657 658 ifp = m->m_pkthdr.rcvif; 659 660 if (m->m_len < sizeof(struct arphdr) && 661 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 662 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 663 if_name(ifp)); 664 return; 665 } 666 ar = mtod(m, struct arphdr *); 667 668 /* Check if length is sufficient */ 669 if (m->m_len < arphdr_len(ar)) { 670 m = m_pullup(m, arphdr_len(ar)); 671 if (m == NULL) { 672 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 673 if_name(ifp)); 674 return; 675 } 676 ar = mtod(m, struct arphdr *); 677 } 678 679 hlen = 0; 680 layer = ""; 681 switch (ntohs(ar->ar_hrd)) { 682 case ARPHRD_ETHER: 683 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 684 layer = "ethernet"; 685 break; 686 case ARPHRD_IEEE802: 687 hlen = ETHER_ADDR_LEN; 688 layer = "ieee802"; 689 break; 690 case ARPHRD_INFINIBAND: 691 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 692 layer = "infiniband"; 693 break; 694 case ARPHRD_IEEE1394: 695 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 696 layer = "firewire"; 697 698 /* 699 * Restrict too long hardware addresses. 700 * Currently we are capable of handling 20-byte 701 * addresses ( sizeof(lle->ll_addr) ) 702 */ 703 if (ar->ar_hln >= 20) 704 hlen = 16; 705 break; 706 default: 707 ARP_LOG(LOG_NOTICE, 708 "packet with unknown hardware format 0x%02d received on " 709 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 710 m_freem(m); 711 return; 712 } 713 714 if (hlen != 0 && hlen != ar->ar_hln) { 715 ARP_LOG(LOG_NOTICE, 716 "packet with invalid %s address length %d received on %s\n", 717 layer, ar->ar_hln, if_name(ifp)); 718 m_freem(m); 719 return; 720 } 721 722 ARPSTAT_INC(received); 723 switch (ntohs(ar->ar_pro)) { 724 #ifdef INET 725 case ETHERTYPE_IP: 726 in_arpinput(m); 727 return; 728 #endif 729 } 730 m_freem(m); 731 } 732 733 #ifdef INET 734 /* 735 * ARP for Internet protocols on 10 Mb/s Ethernet. 736 * Algorithm is that given in RFC 826. 737 * In addition, a sanity check is performed on the sender 738 * protocol address, to catch impersonators. 739 * We no longer handle negotiations for use of trailer protocol: 740 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 741 * along with IP replies if we wanted trailers sent to us, 742 * and also sent them in response to IP replies. 743 * This allowed either end to announce the desire to receive 744 * trailer packets. 745 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 746 * but formerly didn't normally send requests. 747 */ 748 static int log_arp_wrong_iface = 1; 749 static int log_arp_movements = 1; 750 static int log_arp_permanent_modify = 1; 751 static int allow_multicast = 0; 752 753 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 754 &log_arp_wrong_iface, 0, 755 "log arp packets arriving on the wrong interface"); 756 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 757 &log_arp_movements, 0, 758 "log arp replies from MACs different than the one in the cache"); 759 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 760 &log_arp_permanent_modify, 0, 761 "log arp replies from MACs different than the one in the permanent arp entry"); 762 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 763 &allow_multicast, 0, "accept multicast addresses"); 764 765 static void 766 in_arpinput(struct mbuf *m) 767 { 768 struct arphdr *ah; 769 struct ifnet *ifp = m->m_pkthdr.rcvif; 770 struct llentry *la = NULL, *la_tmp; 771 struct ifaddr *ifa; 772 struct in_ifaddr *ia; 773 struct sockaddr sa; 774 struct in_addr isaddr, itaddr, myaddr; 775 u_int8_t *enaddr = NULL; 776 int op; 777 int bridged = 0, is_bridge = 0; 778 int carped; 779 struct sockaddr_in sin; 780 struct sockaddr *dst; 781 struct nhop_object *nh; 782 uint8_t linkhdr[LLE_MAX_LINKHDR]; 783 struct route ro; 784 size_t linkhdrsize; 785 int lladdr_off; 786 int error; 787 char addrbuf[INET_ADDRSTRLEN]; 788 789 NET_EPOCH_ASSERT(); 790 791 sin.sin_len = sizeof(struct sockaddr_in); 792 sin.sin_family = AF_INET; 793 sin.sin_addr.s_addr = 0; 794 795 if (ifp->if_bridge) 796 bridged = 1; 797 if (ifp->if_type == IFT_BRIDGE) 798 is_bridge = 1; 799 800 /* 801 * We already have checked that mbuf contains enough contiguous data 802 * to hold entire arp message according to the arp header. 803 */ 804 ah = mtod(m, struct arphdr *); 805 806 /* 807 * ARP is only for IPv4 so we can reject packets with 808 * a protocol length not equal to an IPv4 address. 809 */ 810 if (ah->ar_pln != sizeof(struct in_addr)) { 811 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 812 sizeof(struct in_addr)); 813 goto drop; 814 } 815 816 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 817 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 818 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 819 goto drop; 820 } 821 822 op = ntohs(ah->ar_op); 823 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 824 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 825 826 if (op == ARPOP_REPLY) 827 ARPSTAT_INC(rxreplies); 828 829 /* 830 * For a bridge, we want to check the address irrespective 831 * of the receive interface. (This will change slightly 832 * when we have clusters of interfaces). 833 */ 834 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 835 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 836 ia->ia_ifp == ifp) && 837 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 838 (ia->ia_ifa.ifa_carp == NULL || 839 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 840 ifa_ref(&ia->ia_ifa); 841 goto match; 842 } 843 } 844 CK_LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 845 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 846 ia->ia_ifp == ifp) && 847 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 848 ifa_ref(&ia->ia_ifa); 849 goto match; 850 } 851 852 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 853 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 854 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 855 addr == ia->ia_addr.sin_addr.s_addr) 856 /* 857 * Check the case when bridge shares its MAC address with 858 * some of its children, so packets are claimed by bridge 859 * itself (bridge_input() does it first), but they are really 860 * meant to be destined to the bridge member. 861 */ 862 if (is_bridge) { 863 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 864 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 865 ifa_ref(&ia->ia_ifa); 866 ifp = ia->ia_ifp; 867 goto match; 868 } 869 } 870 } 871 #undef BDG_MEMBER_MATCHES_ARP 872 873 /* 874 * No match, use the first inet address on the receive interface 875 * as a dummy address for the rest of the function. 876 */ 877 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 878 if (ifa->ifa_addr->sa_family == AF_INET && 879 (ifa->ifa_carp == NULL || 880 (*carp_iamatch_p)(ifa, &enaddr))) { 881 ia = ifatoia(ifa); 882 ifa_ref(ifa); 883 goto match; 884 } 885 886 /* 887 * If bridging, fall back to using any inet address. 888 */ 889 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 890 goto drop; 891 ifa_ref(&ia->ia_ifa); 892 match: 893 if (!enaddr) 894 enaddr = (u_int8_t *)IF_LLADDR(ifp); 895 carped = (ia->ia_ifa.ifa_carp != NULL); 896 myaddr = ia->ia_addr.sin_addr; 897 ifa_free(&ia->ia_ifa); 898 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 899 goto drop; /* it's from me, ignore it. */ 900 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 901 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 902 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 903 goto drop; 904 } 905 906 if (ifp->if_addrlen != ah->ar_hln) { 907 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 908 "i/f %d (ignored)\n", ifp->if_addrlen, 909 (u_char *) ar_sha(ah), ":", ah->ar_hln, 910 ifp->if_addrlen); 911 goto drop; 912 } 913 914 /* 915 * Warn if another host is using the same IP address, but only if the 916 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 917 * case we suppress the warning to avoid false positive complaints of 918 * potential misconfiguration. 919 */ 920 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 921 myaddr.s_addr != 0) { 922 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 923 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 924 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 925 itaddr = myaddr; 926 ARPSTAT_INC(dupips); 927 goto reply; 928 } 929 if (ifp->if_flags & IFF_STATICARP) 930 goto reply; 931 932 bzero(&sin, sizeof(sin)); 933 sin.sin_len = sizeof(struct sockaddr_in); 934 sin.sin_family = AF_INET; 935 sin.sin_addr = isaddr; 936 dst = (struct sockaddr *)&sin; 937 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 938 if (la != NULL) 939 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 940 else if (itaddr.s_addr == myaddr.s_addr) { 941 /* 942 * Request/reply to our address, but no lle exists yet. 943 * Calculate full link prepend to use in lle. 944 */ 945 linkhdrsize = sizeof(linkhdr); 946 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 947 &linkhdrsize, &lladdr_off) != 0) 948 goto reply; 949 950 /* Allocate new entry */ 951 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 952 if (la == NULL) { 953 /* 954 * lle creation may fail if source address belongs 955 * to non-directly connected subnet. However, we 956 * will try to answer the request instead of dropping 957 * frame. 958 */ 959 goto reply; 960 } 961 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 962 lladdr_off); 963 964 IF_AFDATA_WLOCK(ifp); 965 LLE_WLOCK(la); 966 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 967 968 /* 969 * Check if lle still does not exists. 970 * If it does, that means that we either 971 * 1) have configured it explicitly, via 972 * 1a) 'arp -s' static entry or 973 * 1b) interface address static record 974 * or 975 * 2) it was the result of sending first packet to-host 976 * or 977 * 3) it was another arp reply packet we handled in 978 * different thread. 979 * 980 * In all cases except 3) we definitely need to prefer 981 * existing lle. For the sake of simplicity, prefer any 982 * existing lle over newly-create one. 983 */ 984 if (la_tmp == NULL) 985 lltable_link_entry(LLTABLE(ifp), la); 986 IF_AFDATA_WUNLOCK(ifp); 987 988 if (la_tmp == NULL) { 989 arp_mark_lle_reachable(la, ifp); 990 LLE_WUNLOCK(la); 991 } else { 992 /* Free newly-create entry and handle packet */ 993 lltable_free_entry(LLTABLE(ifp), la); 994 la = la_tmp; 995 la_tmp = NULL; 996 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 997 /* arp_check_update_lle() returns @la unlocked */ 998 } 999 la = NULL; 1000 } 1001 reply: 1002 if (op != ARPOP_REQUEST) 1003 goto drop; 1004 ARPSTAT_INC(rxrequests); 1005 1006 if (itaddr.s_addr == myaddr.s_addr) { 1007 /* Shortcut.. the receiving interface is the target. */ 1008 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1009 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1010 } else { 1011 /* 1012 * Destination address is not ours. Check if 1013 * proxyarp entry exists or proxyarp is turned on globally. 1014 */ 1015 struct llentry *lle; 1016 1017 sin.sin_addr = itaddr; 1018 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1019 1020 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1021 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1022 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1023 LLE_RUNLOCK(lle); 1024 } else { 1025 if (lle != NULL) 1026 LLE_RUNLOCK(lle); 1027 1028 if (!V_arp_proxyall) 1029 goto drop; 1030 1031 NET_EPOCH_ASSERT(); 1032 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0); 1033 if (nh == NULL) 1034 goto drop; 1035 1036 /* 1037 * Don't send proxies for nodes on the same interface 1038 * as this one came out of, or we'll get into a fight 1039 * over who claims what Ether address. 1040 */ 1041 if (nh->nh_ifp == ifp) 1042 goto drop; 1043 1044 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1045 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1046 1047 /* 1048 * Also check that the node which sent the ARP packet 1049 * is on the interface we expect it to be on. This 1050 * avoids ARP chaos if an interface is connected to the 1051 * wrong network. 1052 */ 1053 1054 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0); 1055 if (nh == NULL) 1056 goto drop; 1057 if (nh->nh_ifp != ifp) { 1058 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1059 " from %s via %s\n", 1060 inet_ntoa_r(isaddr, addrbuf), 1061 ifp->if_xname); 1062 goto drop; 1063 } 1064 1065 #ifdef DEBUG_PROXY 1066 printf("arp: proxying for %s\n", 1067 inet_ntoa_r(itaddr, addrbuf)); 1068 #endif 1069 } 1070 } 1071 1072 if (itaddr.s_addr == myaddr.s_addr && 1073 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1074 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1075 #ifdef DEBUG_LINKLOCAL 1076 printf("arp: sending reply for link-local addr %s\n", 1077 inet_ntoa_r(itaddr, addrbuf)); 1078 #endif 1079 m->m_flags |= M_BCAST; 1080 m->m_flags &= ~M_MCAST; 1081 } else { 1082 /* default behaviour; never reply by broadcast. */ 1083 m->m_flags &= ~(M_BCAST|M_MCAST); 1084 } 1085 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1086 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1087 ah->ar_op = htons(ARPOP_REPLY); 1088 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1089 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1090 m->m_pkthdr.len = m->m_len; 1091 m->m_pkthdr.rcvif = NULL; 1092 sa.sa_family = AF_ARP; 1093 sa.sa_len = 2; 1094 1095 /* Calculate link header for sending frame */ 1096 bzero(&ro, sizeof(ro)); 1097 linkhdrsize = sizeof(linkhdr); 1098 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1099 1100 /* 1101 * arp_fillheader() may fail due to lack of support inside encap request 1102 * routing. This is not necessary an error, AF_ARP can/should be handled 1103 * by if_output(). 1104 */ 1105 if (error != 0 && error != EAFNOSUPPORT) { 1106 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1107 if_name(ifp), error); 1108 goto drop; 1109 } 1110 1111 ro.ro_prepend = linkhdr; 1112 ro.ro_plen = linkhdrsize; 1113 ro.ro_flags = 0; 1114 1115 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1116 (*ifp->if_output)(ifp, m, &sa, &ro); 1117 ARPSTAT_INC(txreplies); 1118 return; 1119 1120 drop: 1121 m_freem(m); 1122 } 1123 #endif 1124 1125 static struct mbuf * 1126 arp_grab_holdchain(struct llentry *la) 1127 { 1128 struct mbuf *chain; 1129 1130 LLE_WLOCK_ASSERT(la); 1131 1132 chain = la->la_hold; 1133 la->la_hold = NULL; 1134 la->la_numheld = 0; 1135 1136 return (chain); 1137 } 1138 1139 static void 1140 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain) 1141 { 1142 struct mbuf *m_hold, *m_hold_next; 1143 struct sockaddr_in sin; 1144 1145 NET_EPOCH_ASSERT(); 1146 1147 struct route ro = { 1148 .ro_prepend = la->r_linkdata, 1149 .ro_plen = la->r_hdrlen, 1150 }; 1151 1152 lltable_fill_sa_entry(la, (struct sockaddr *)&sin); 1153 1154 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) { 1155 m_hold_next = m_hold->m_nextpkt; 1156 m_hold->m_nextpkt = NULL; 1157 /* Avoid confusing lower layers. */ 1158 m_clrprotoflags(m_hold); 1159 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro); 1160 } 1161 } 1162 1163 /* 1164 * Checks received arp data against existing @la. 1165 * Updates lle state/performs notification if necessary. 1166 */ 1167 static void 1168 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1169 int bridged, struct llentry *la) 1170 { 1171 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1172 size_t linkhdrsize; 1173 int lladdr_off; 1174 char addrbuf[INET_ADDRSTRLEN]; 1175 1176 LLE_WLOCK_ASSERT(la); 1177 1178 /* the following is not an error when doing bridging */ 1179 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1180 if (log_arp_wrong_iface) 1181 ARP_LOG(LOG_WARNING, "%s is on %s " 1182 "but got reply from %*D on %s\n", 1183 inet_ntoa_r(isaddr, addrbuf), 1184 la->lle_tbl->llt_ifp->if_xname, 1185 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1186 ifp->if_xname); 1187 LLE_WUNLOCK(la); 1188 return; 1189 } 1190 if ((la->la_flags & LLE_VALID) && 1191 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1192 if (la->la_flags & LLE_STATIC) { 1193 LLE_WUNLOCK(la); 1194 if (log_arp_permanent_modify) 1195 ARP_LOG(LOG_ERR, 1196 "%*D attempts to modify " 1197 "permanent entry for %s on %s\n", 1198 ifp->if_addrlen, 1199 (u_char *)ar_sha(ah), ":", 1200 inet_ntoa_r(isaddr, addrbuf), 1201 ifp->if_xname); 1202 return; 1203 } 1204 if (log_arp_movements) { 1205 ARP_LOG(LOG_INFO, "%s moved from %*D " 1206 "to %*D on %s\n", 1207 inet_ntoa_r(isaddr, addrbuf), 1208 ifp->if_addrlen, 1209 (u_char *)la->ll_addr, ":", 1210 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1211 ifp->if_xname); 1212 } 1213 } 1214 1215 /* Calculate full link prepend to use in lle */ 1216 linkhdrsize = sizeof(linkhdr); 1217 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1218 &linkhdrsize, &lladdr_off) != 0) { 1219 LLE_WUNLOCK(la); 1220 return; 1221 } 1222 1223 /* Check if something has changed */ 1224 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1225 (la->la_flags & LLE_VALID) == 0) { 1226 /* Try to perform LLE update */ 1227 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1228 lladdr_off) == 0) { 1229 LLE_WUNLOCK(la); 1230 return; 1231 } 1232 1233 /* Clear fast path feedback request if set */ 1234 llentry_mark_used(la); 1235 } 1236 1237 arp_mark_lle_reachable(la, ifp); 1238 1239 /* 1240 * The packets are all freed within the call to the output 1241 * routine. 1242 * 1243 * NB: The lock MUST be released before the call to the 1244 * output routine. 1245 */ 1246 if (la->la_hold != NULL) { 1247 struct mbuf *chain; 1248 1249 chain = arp_grab_holdchain(la); 1250 LLE_WUNLOCK(la); 1251 arp_flush_holdchain(ifp, la, chain); 1252 } else 1253 LLE_WUNLOCK(la); 1254 } 1255 1256 static void 1257 arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp) 1258 { 1259 int canceled, wtime; 1260 1261 LLE_WLOCK_ASSERT(la); 1262 1263 la->ln_state = ARP_LLINFO_REACHABLE; 1264 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1265 1266 if ((ifp->if_flags & IFF_STICKYARP) != 0) 1267 la->la_flags |= LLE_STATIC; 1268 1269 if (!(la->la_flags & LLE_STATIC)) { 1270 LLE_ADDREF(la); 1271 la->la_expire = time_uptime + V_arpt_keep; 1272 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1273 if (wtime < 0) 1274 wtime = V_arpt_keep; 1275 canceled = callout_reset(&la->lle_timer, 1276 hz * wtime, arptimer, la); 1277 if (canceled) 1278 LLE_REMREF(la); 1279 } 1280 la->la_asked = 0; 1281 la->la_preempt = V_arp_maxtries; 1282 } 1283 1284 /* 1285 * Add permanent link-layer record for given interface address. 1286 */ 1287 static __noinline void 1288 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1289 { 1290 struct llentry *lle, *lle_tmp; 1291 1292 /* 1293 * Interface address LLE record is considered static 1294 * because kernel code relies on LLE_STATIC flag to check 1295 * if these entries can be rewriten by arp updates. 1296 */ 1297 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1298 if (lle == NULL) { 1299 log(LOG_INFO, "arp_ifinit: cannot create arp " 1300 "entry for interface address\n"); 1301 return; 1302 } 1303 1304 IF_AFDATA_WLOCK(ifp); 1305 LLE_WLOCK(lle); 1306 /* Unlink any entry if exists */ 1307 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1308 if (lle_tmp != NULL) 1309 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1310 1311 lltable_link_entry(LLTABLE(ifp), lle); 1312 IF_AFDATA_WUNLOCK(ifp); 1313 1314 if (lle_tmp != NULL) 1315 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1316 1317 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1318 LLE_WUNLOCK(lle); 1319 if (lle_tmp != NULL) 1320 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1321 } 1322 1323 /* 1324 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1325 * of valid values. 1326 */ 1327 static int 1328 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1329 { 1330 int error; 1331 int rexmit_count = *(int *)arg1; 1332 1333 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1334 1335 /* Enforce limits on any new value that may have been set. */ 1336 if (!error && req->newptr) { 1337 /* A new value was set. */ 1338 if (rexmit_count < 0) { 1339 rexmit_count = 0; 1340 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1341 rexmit_count = MAX_GARP_RETRANSMITS; 1342 } 1343 *(int *)arg1 = rexmit_count; 1344 } 1345 1346 return (error); 1347 } 1348 1349 /* 1350 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1351 * retransmit it again. A pending callout owns a reference to the ifa. 1352 */ 1353 static void 1354 garp_rexmit(void *arg) 1355 { 1356 struct epoch_tracker et; 1357 struct in_ifaddr *ia = arg; 1358 1359 if (callout_pending(&ia->ia_garp_timer) || 1360 !callout_active(&ia->ia_garp_timer)) { 1361 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1362 ifa_free(&ia->ia_ifa); 1363 return; 1364 } 1365 1366 NET_EPOCH_ENTER(et); 1367 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1368 1369 /* 1370 * Drop lock while the ARP request is generated. 1371 */ 1372 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1373 1374 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1375 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1376 1377 /* 1378 * Increment the count of retransmissions. If the count has reached the 1379 * maximum value, stop sending the GARP packets. Otherwise, schedule 1380 * the callout to retransmit another GARP packet. 1381 */ 1382 ++ia->ia_garp_count; 1383 if (ia->ia_garp_count >= V_garp_rexmit_count) { 1384 ifa_free(&ia->ia_ifa); 1385 } else { 1386 int rescheduled; 1387 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1388 rescheduled = callout_reset(&ia->ia_garp_timer, 1389 (1 << ia->ia_garp_count) * hz, 1390 garp_rexmit, ia); 1391 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1392 if (rescheduled) { 1393 ifa_free(&ia->ia_ifa); 1394 } 1395 } 1396 1397 CURVNET_RESTORE(); 1398 NET_EPOCH_EXIT(et); 1399 } 1400 1401 /* 1402 * Start the GARP retransmit timer. 1403 * 1404 * A single GARP is always transmitted when an IPv4 address is added 1405 * to an interface and that is usually sufficient. However, in some 1406 * circumstances, such as when a shared address is passed between 1407 * cluster nodes, this single GARP may occasionally be dropped or 1408 * lost. This can lead to neighbors on the network link working with a 1409 * stale ARP cache and sending packets destined for that address to 1410 * the node that previously owned the address, which may not respond. 1411 * 1412 * To avoid this situation, GARP retransmits can be enabled by setting 1413 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1414 * than zero. The setting represents the maximum number of 1415 * retransmissions. The interval between retransmissions is calculated 1416 * using an exponential backoff algorithm, doubling each time, so the 1417 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1418 */ 1419 static void 1420 garp_timer_start(struct ifaddr *ifa) 1421 { 1422 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1423 1424 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1425 ia->ia_garp_count = 0; 1426 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1427 garp_rexmit, ia) == 0) { 1428 ifa_ref(ifa); 1429 } 1430 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1431 } 1432 1433 void 1434 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1435 { 1436 struct epoch_tracker et; 1437 const struct sockaddr_in *dst_in; 1438 const struct sockaddr *dst; 1439 1440 if (ifa->ifa_carp != NULL) 1441 return; 1442 1443 dst = ifa->ifa_addr; 1444 dst_in = (const struct sockaddr_in *)dst; 1445 1446 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1447 return; 1448 NET_EPOCH_ENTER(et); 1449 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1450 NET_EPOCH_EXIT(et); 1451 if (V_garp_rexmit_count > 0) { 1452 garp_timer_start(ifa); 1453 } 1454 1455 arp_add_ifa_lle(ifp, dst); 1456 } 1457 1458 void 1459 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1460 { 1461 1462 if (ntohl(addr.s_addr) != INADDR_ANY) 1463 arprequest(ifp, &addr, &addr, enaddr); 1464 } 1465 1466 /* 1467 * Sends gratuitous ARPs for each ifaddr to notify other 1468 * nodes about the address change. 1469 */ 1470 static __noinline void 1471 arp_handle_ifllchange(struct ifnet *ifp) 1472 { 1473 struct ifaddr *ifa; 1474 1475 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1476 if (ifa->ifa_addr->sa_family == AF_INET) 1477 arp_ifinit(ifp, ifa); 1478 } 1479 } 1480 1481 /* 1482 * A handler for interface link layer address change event. 1483 */ 1484 static void 1485 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1486 { 1487 /* if_bridge can update its lladdr during if_vmove(), after we've done 1488 * if_detach_internal()/dom_ifdetach(). */ 1489 if (ifp->if_afdata[AF_INET] == NULL) 1490 return; 1491 1492 lltable_update_ifaddr(LLTABLE(ifp)); 1493 1494 if ((ifp->if_flags & IFF_UP) != 0) 1495 arp_handle_ifllchange(ifp); 1496 } 1497 1498 static void 1499 vnet_arp_init(void) 1500 { 1501 1502 if (IS_DEFAULT_VNET(curvnet)) { 1503 netisr_register(&arp_nh); 1504 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1505 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1506 } 1507 #ifdef VIMAGE 1508 else 1509 netisr_register_vnet(&arp_nh); 1510 #endif 1511 } 1512 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1513 vnet_arp_init, NULL); 1514 1515 #ifdef VIMAGE 1516 /* 1517 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1518 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1519 */ 1520 static void 1521 vnet_arp_destroy(__unused void *arg) 1522 { 1523 1524 netisr_unregister_vnet(&arp_nh); 1525 } 1526 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1527 vnet_arp_destroy, NULL); 1528 #endif 1529