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/rmlock.h> 56 #include <sys/socket.h> 57 #include <sys/syslog.h> 58 59 #include <net/if.h> 60 #include <net/if_var.h> 61 #include <net/if_dl.h> 62 #include <net/if_types.h> 63 #include <net/netisr.h> 64 #include <net/ethernet.h> 65 #include <net/route.h> 66 #include <net/route/nhop.h> 67 #include <net/vnet.h> 68 69 #include <netinet/in.h> 70 #include <netinet/in_fib.h> 71 #include <netinet/in_var.h> 72 #include <net/if_llatbl.h> 73 #include <netinet/if_ether.h> 74 #ifdef INET 75 #include <netinet/ip_carp.h> 76 #endif 77 78 #include <security/mac/mac_framework.h> 79 80 #define SIN(s) ((const struct sockaddr_in *)(s)) 81 82 static struct timeval arp_lastlog; 83 static int arp_curpps; 84 static int arp_maxpps = 1; 85 86 /* Simple ARP state machine */ 87 enum arp_llinfo_state { 88 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 89 ARP_LLINFO_REACHABLE, /* LLE is valid */ 90 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 91 ARP_LLINFO_DELETED, /* LLE is deleted */ 92 }; 93 94 SYSCTL_DECL(_net_link_ether); 95 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, 96 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 97 ""); 98 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, 99 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 100 ""); 101 102 /* timer values */ 103 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 104 * minutes */ 105 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 106 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 107 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 108 * 20 seconds */ 109 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 110 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 111 VNET_PCPUSTAT_SYSINIT(arpstat); 112 113 #ifdef VIMAGE 114 VNET_PCPUSTAT_SYSUNINIT(arpstat); 115 #endif /* VIMAGE */ 116 117 VNET_DEFINE_STATIC(int, arp_maxhold) = 16; 118 119 #define V_arpt_keep VNET(arpt_keep) 120 #define V_arpt_down VNET(arpt_down) 121 #define V_arpt_rexmit VNET(arpt_rexmit) 122 #define V_arp_maxtries VNET(arp_maxtries) 123 #define V_arp_proxyall VNET(arp_proxyall) 124 #define V_arp_maxhold VNET(arp_maxhold) 125 126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 127 &VNET_NAME(arpt_keep), 0, 128 "ARP entry lifetime in seconds"); 129 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 130 &VNET_NAME(arp_maxtries), 0, 131 "ARP resolution attempts before returning error"); 132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 133 &VNET_NAME(arp_proxyall), 0, 134 "Enable proxy ARP for all suitable requests"); 135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 136 &VNET_NAME(arpt_down), 0, 137 "Incomplete ARP entry lifetime in seconds"); 138 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 139 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 140 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 141 &VNET_NAME(arp_maxhold), 0, 142 "Number of packets to hold per ARP entry"); 143 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 144 CTLFLAG_RW, &arp_maxpps, 0, 145 "Maximum number of remotely triggered ARP messages that can be " 146 "logged per second"); 147 148 /* 149 * Due to the exponential backoff algorithm used for the interval between GARP 150 * retransmissions, the maximum number of retransmissions is limited for 151 * sanity. This limit corresponds to a maximum interval between retransmissions 152 * of 2^16 seconds ~= 18 hours. 153 * 154 * Making this limit more dynamic is more complicated than worthwhile, 155 * especially since sending out GARPs spaced days apart would be of little 156 * use. A maximum dynamic limit would look something like: 157 * 158 * const int max = fls(INT_MAX / hz) - 1; 159 */ 160 #define MAX_GARP_RETRANSMITS 16 161 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 162 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 163 164 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 165 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 166 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 167 "Number of times to retransmit GARP packets;" 168 " 0 to disable, maximum of 16"); 169 170 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 171 #define V_arp_log_level VNET(arp_log_level) 172 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 173 &VNET_NAME(arp_log_level), 0, 174 "Minimum log(9) level for recording rate limited arp log messages. " 175 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 176 #define ARP_LOG(pri, ...) do { \ 177 if ((pri) <= V_arp_log_level && \ 178 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 179 log((pri), "arp: " __VA_ARGS__); \ 180 } while (0) 181 182 static void arpintr(struct mbuf *); 183 static void arptimer(void *); 184 #ifdef INET 185 static void in_arpinput(struct mbuf *); 186 #endif 187 188 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 189 struct ifnet *ifp, int bridged, struct llentry *la); 190 static void arp_mark_lle_reachable(struct llentry *la); 191 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 192 193 static eventhandler_tag iflladdr_tag; 194 195 static const struct netisr_handler arp_nh = { 196 .nh_name = "arp", 197 .nh_handler = arpintr, 198 .nh_proto = NETISR_ARP, 199 .nh_policy = NETISR_POLICY_SOURCE, 200 }; 201 202 /* 203 * Timeout routine. Age arp_tab entries periodically. 204 */ 205 static void 206 arptimer(void *arg) 207 { 208 struct llentry *lle = (struct llentry *)arg; 209 struct ifnet *ifp; 210 211 if (lle->la_flags & LLE_STATIC) { 212 return; 213 } 214 LLE_WLOCK(lle); 215 if (callout_pending(&lle->lle_timer)) { 216 /* 217 * Here we are a bit odd here in the treatment of 218 * active/pending. If the pending bit is set, it got 219 * rescheduled before I ran. The active 220 * bit we ignore, since if it was stopped 221 * in ll_tablefree() and was currently running 222 * it would have return 0 so the code would 223 * not have deleted it since the callout could 224 * not be stopped so we want to go through 225 * with the delete here now. If the callout 226 * was restarted, the pending bit will be back on and 227 * we just want to bail since the callout_reset would 228 * return 1 and our reference would have been removed 229 * by arpresolve() below. 230 */ 231 LLE_WUNLOCK(lle); 232 return; 233 } 234 ifp = lle->lle_tbl->llt_ifp; 235 CURVNET_SET(ifp->if_vnet); 236 237 switch (lle->ln_state) { 238 case ARP_LLINFO_REACHABLE: 239 240 /* 241 * Expiration time is approaching. 242 * Request usage feedback from the datapath. 243 * Change state and re-schedule ourselves. 244 */ 245 llentry_request_feedback(lle); 246 lle->ln_state = ARP_LLINFO_VERIFY; 247 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 248 LLE_WUNLOCK(lle); 249 CURVNET_RESTORE(); 250 return; 251 case ARP_LLINFO_VERIFY: 252 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) { 253 /* Entry was used, issue refresh request */ 254 struct epoch_tracker et; 255 struct in_addr dst; 256 257 dst = lle->r_l3addr.addr4; 258 lle->la_preempt--; 259 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 260 LLE_WUNLOCK(lle); 261 NET_EPOCH_ENTER(et); 262 arprequest(ifp, NULL, &dst, NULL); 263 NET_EPOCH_EXIT(et); 264 CURVNET_RESTORE(); 265 return; 266 } 267 /* Nothing happened. Reschedule if not too late */ 268 if (lle->la_expire > time_uptime) { 269 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 270 LLE_WUNLOCK(lle); 271 CURVNET_RESTORE(); 272 return; 273 } 274 break; 275 case ARP_LLINFO_INCOMPLETE: 276 case ARP_LLINFO_DELETED: 277 break; 278 } 279 280 if ((lle->la_flags & LLE_DELETED) == 0) { 281 int evt; 282 283 if (lle->la_flags & LLE_VALID) 284 evt = LLENTRY_EXPIRED; 285 else 286 evt = LLENTRY_TIMEDOUT; 287 EVENTHANDLER_INVOKE(lle_event, lle, evt); 288 } 289 290 callout_stop(&lle->lle_timer); 291 292 /* XXX: LOR avoidance. We still have ref on lle. */ 293 LLE_WUNLOCK(lle); 294 IF_AFDATA_LOCK(ifp); 295 LLE_WLOCK(lle); 296 297 /* Guard against race with other llentry_free(). */ 298 if (lle->la_flags & LLE_LINKED) { 299 LLE_REMREF(lle); 300 lltable_unlink_entry(lle->lle_tbl, lle); 301 } 302 IF_AFDATA_UNLOCK(ifp); 303 304 size_t pkts_dropped = llentry_free(lle); 305 306 ARPSTAT_ADD(dropped, pkts_dropped); 307 ARPSTAT_INC(timeouts); 308 309 CURVNET_RESTORE(); 310 } 311 312 /* 313 * Stores link-layer header for @ifp in format suitable for if_output() 314 * into buffer @buf. Resulting header length is stored in @bufsize. 315 * 316 * Returns 0 on success. 317 */ 318 static int 319 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 320 size_t *bufsize) 321 { 322 struct if_encap_req ereq; 323 int error; 324 325 bzero(buf, *bufsize); 326 bzero(&ereq, sizeof(ereq)); 327 ereq.buf = buf; 328 ereq.bufsize = *bufsize; 329 ereq.rtype = IFENCAP_LL; 330 ereq.family = AF_ARP; 331 ereq.lladdr = ar_tha(ah); 332 ereq.hdata = (u_char *)ah; 333 if (bcast) 334 ereq.flags = IFENCAP_FLAG_BROADCAST; 335 error = ifp->if_requestencap(ifp, &ereq); 336 if (error == 0) 337 *bufsize = ereq.bufsize; 338 339 return (error); 340 } 341 342 /* 343 * Broadcast an ARP request. Caller specifies: 344 * - arp header source ip address 345 * - arp header target ip address 346 * - arp header source ethernet address 347 */ 348 static int 349 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 350 const struct in_addr *tip, u_char *enaddr) 351 { 352 struct mbuf *m; 353 struct arphdr *ah; 354 struct sockaddr sa; 355 u_char *carpaddr = NULL; 356 uint8_t linkhdr[LLE_MAX_LINKHDR]; 357 size_t linkhdrsize; 358 struct route ro; 359 int error; 360 361 NET_EPOCH_ASSERT(); 362 363 if (sip == NULL) { 364 /* 365 * The caller did not supply a source address, try to find 366 * a compatible one among those assigned to this interface. 367 */ 368 struct ifaddr *ifa; 369 370 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 371 if (ifa->ifa_addr->sa_family != AF_INET) 372 continue; 373 374 if (ifa->ifa_carp) { 375 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 376 continue; 377 sip = &IA_SIN(ifa)->sin_addr; 378 } else { 379 carpaddr = NULL; 380 sip = &IA_SIN(ifa)->sin_addr; 381 } 382 383 if (0 == ((sip->s_addr ^ tip->s_addr) & 384 IA_MASKSIN(ifa)->sin_addr.s_addr)) 385 break; /* found it. */ 386 } 387 if (sip == NULL) { 388 printf("%s: cannot find matching address\n", __func__); 389 return (EADDRNOTAVAIL); 390 } 391 } 392 if (enaddr == NULL) 393 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 394 395 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 396 return (ENOMEM); 397 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 398 2 * ifp->if_addrlen; 399 m->m_pkthdr.len = m->m_len; 400 M_ALIGN(m, m->m_len); 401 ah = mtod(m, struct arphdr *); 402 bzero((caddr_t)ah, m->m_len); 403 #ifdef MAC 404 mac_netinet_arp_send(ifp, m); 405 #endif 406 ah->ar_pro = htons(ETHERTYPE_IP); 407 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 408 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 409 ah->ar_op = htons(ARPOP_REQUEST); 410 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 411 bcopy(sip, ar_spa(ah), ah->ar_pln); 412 bcopy(tip, ar_tpa(ah), ah->ar_pln); 413 sa.sa_family = AF_ARP; 414 sa.sa_len = 2; 415 416 /* Calculate link header for sending frame */ 417 bzero(&ro, sizeof(ro)); 418 linkhdrsize = sizeof(linkhdr); 419 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 420 if (error != 0 && error != EAFNOSUPPORT) { 421 m_freem(m); 422 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 423 if_name(ifp), error); 424 return (error); 425 } 426 427 ro.ro_prepend = linkhdr; 428 ro.ro_plen = linkhdrsize; 429 ro.ro_flags = 0; 430 431 m->m_flags |= M_BCAST; 432 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 433 error = (*ifp->if_output)(ifp, m, &sa, &ro); 434 ARPSTAT_INC(txrequests); 435 if (error) { 436 ARPSTAT_INC(txerrors); 437 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 438 if_name(ifp), error); 439 } 440 return (error); 441 } 442 443 void 444 arprequest(struct ifnet *ifp, const struct in_addr *sip, 445 const struct in_addr *tip, u_char *enaddr) 446 { 447 448 (void) arprequest_internal(ifp, sip, tip, enaddr); 449 } 450 451 /* 452 * Resolve an IP address into an ethernet address - heavy version. 453 * Used internally by arpresolve(). 454 * We have already checked that we can't use an existing lle without 455 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 456 * 457 * On success, desten and pflags are filled in and the function returns 0; 458 * If the packet must be held pending resolution, we return EWOULDBLOCK 459 * On other errors, we return the corresponding error code. 460 * Note that m_freem() handles NULL. 461 */ 462 static int 463 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 464 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 465 struct llentry **plle) 466 { 467 struct llentry *la = NULL, *la_tmp; 468 struct mbuf *curr = NULL; 469 struct mbuf *next = NULL; 470 int error, renew; 471 char *lladdr; 472 int ll_len; 473 474 NET_EPOCH_ASSERT(); 475 476 if (pflags != NULL) 477 *pflags = 0; 478 if (plle != NULL) 479 *plle = NULL; 480 481 if ((flags & LLE_CREATE) == 0) 482 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 483 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 484 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 485 if (la == NULL) { 486 char addrbuf[INET_ADDRSTRLEN]; 487 488 log(LOG_DEBUG, 489 "arpresolve: can't allocate llinfo for %s on %s\n", 490 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 491 if_name(ifp)); 492 m_freem(m); 493 return (EINVAL); 494 } 495 496 IF_AFDATA_WLOCK(ifp); 497 LLE_WLOCK(la); 498 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 499 /* Prefer ANY existing lle over newly-created one */ 500 if (la_tmp == NULL) 501 lltable_link_entry(LLTABLE(ifp), la); 502 IF_AFDATA_WUNLOCK(ifp); 503 if (la_tmp != NULL) { 504 lltable_free_entry(LLTABLE(ifp), la); 505 la = la_tmp; 506 } 507 } 508 if (la == NULL) { 509 m_freem(m); 510 return (EINVAL); 511 } 512 513 if ((la->la_flags & LLE_VALID) && 514 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 515 if (flags & LLE_ADDRONLY) { 516 lladdr = la->ll_addr; 517 ll_len = ifp->if_addrlen; 518 } else { 519 lladdr = la->r_linkdata; 520 ll_len = la->r_hdrlen; 521 } 522 bcopy(lladdr, desten, ll_len); 523 524 /* Notify LLE code that the entry was used by datapath */ 525 llentry_provide_feedback(la); 526 if (pflags != NULL) 527 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 528 if (plle) { 529 LLE_ADDREF(la); 530 *plle = la; 531 } 532 LLE_WUNLOCK(la); 533 return (0); 534 } 535 536 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 537 /* 538 * There is an arptab entry, but no ethernet address 539 * response yet. Add the mbuf to the list, dropping 540 * the oldest packet if we have exceeded the system 541 * setting. 542 */ 543 if (m != NULL) { 544 if (la->la_numheld >= V_arp_maxhold) { 545 if (la->la_hold != NULL) { 546 next = la->la_hold->m_nextpkt; 547 m_freem(la->la_hold); 548 la->la_hold = next; 549 la->la_numheld--; 550 ARPSTAT_INC(dropped); 551 } 552 } 553 if (la->la_hold != NULL) { 554 curr = la->la_hold; 555 while (curr->m_nextpkt != NULL) 556 curr = curr->m_nextpkt; 557 curr->m_nextpkt = m; 558 } else 559 la->la_hold = m; 560 la->la_numheld++; 561 } 562 /* 563 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 564 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 565 * if we have already sent arp_maxtries ARP requests. Retransmit the 566 * ARP request, but not faster than one request per second. 567 */ 568 if (la->la_asked < V_arp_maxtries) 569 error = EWOULDBLOCK; /* First request. */ 570 else 571 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 572 573 if (renew) { 574 int canceled, e; 575 576 LLE_ADDREF(la); 577 la->la_expire = time_uptime; 578 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 579 arptimer, la); 580 if (canceled) 581 LLE_REMREF(la); 582 la->la_asked++; 583 LLE_WUNLOCK(la); 584 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL); 585 /* 586 * Only overwrite 'error' in case of error; in case of success 587 * the proper return value was already set above. 588 */ 589 if (e != 0) 590 return (e); 591 return (error); 592 } 593 594 LLE_WUNLOCK(la); 595 return (error); 596 } 597 598 /* 599 * Lookups link header based on an IP address. 600 * On input: 601 * ifp is the interface we use 602 * is_gw != 0 if @dst represents gateway to some destination 603 * m is the mbuf. May be NULL if we don't have a packet. 604 * dst is the next hop, 605 * desten is the storage to put LL header. 606 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 607 * 608 * On success, full/partial link header and flags are filled in and 609 * the function returns 0. 610 * If the packet must be held pending resolution, we return EWOULDBLOCK 611 * On other errors, we return the corresponding error code. 612 * Note that m_freem() handles NULL. 613 */ 614 int 615 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 616 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 617 struct llentry **plle) 618 { 619 struct llentry *la = NULL; 620 621 NET_EPOCH_ASSERT(); 622 623 if (pflags != NULL) 624 *pflags = 0; 625 if (plle != NULL) 626 *plle = NULL; 627 628 if (m != NULL) { 629 if (m->m_flags & M_BCAST) { 630 /* broadcast */ 631 (void)memcpy(desten, 632 ifp->if_broadcastaddr, ifp->if_addrlen); 633 return (0); 634 } 635 if (m->m_flags & M_MCAST) { 636 /* multicast */ 637 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 638 return (0); 639 } 640 } 641 642 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 643 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 644 /* Entry found, let's copy lle info */ 645 bcopy(la->r_linkdata, desten, la->r_hdrlen); 646 if (pflags != NULL) 647 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 648 /* Notify the LLE handling code that the entry was used. */ 649 llentry_provide_feedback(la); 650 if (plle) { 651 LLE_ADDREF(la); 652 *plle = la; 653 LLE_WUNLOCK(la); 654 } 655 return (0); 656 } 657 if (plle && la) 658 LLE_WUNLOCK(la); 659 660 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 661 desten, pflags, plle)); 662 } 663 664 /* 665 * Common length and type checks are done here, 666 * then the protocol-specific routine is called. 667 */ 668 static void 669 arpintr(struct mbuf *m) 670 { 671 struct arphdr *ar; 672 struct ifnet *ifp; 673 char *layer; 674 int hlen; 675 676 ifp = m->m_pkthdr.rcvif; 677 678 if (m->m_len < sizeof(struct arphdr) && 679 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 680 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 681 if_name(ifp)); 682 return; 683 } 684 ar = mtod(m, struct arphdr *); 685 686 /* Check if length is sufficient */ 687 if (m->m_len < arphdr_len(ar)) { 688 m = m_pullup(m, arphdr_len(ar)); 689 if (m == NULL) { 690 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 691 if_name(ifp)); 692 return; 693 } 694 ar = mtod(m, struct arphdr *); 695 } 696 697 hlen = 0; 698 layer = ""; 699 switch (ntohs(ar->ar_hrd)) { 700 case ARPHRD_ETHER: 701 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 702 layer = "ethernet"; 703 break; 704 case ARPHRD_INFINIBAND: 705 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 706 layer = "infiniband"; 707 break; 708 case ARPHRD_IEEE1394: 709 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 710 layer = "firewire"; 711 712 /* 713 * Restrict too long hardware addresses. 714 * Currently we are capable of handling 20-byte 715 * addresses ( sizeof(lle->ll_addr) ) 716 */ 717 if (ar->ar_hln >= 20) 718 hlen = 16; 719 break; 720 default: 721 ARP_LOG(LOG_NOTICE, 722 "packet with unknown hardware format 0x%02d received on " 723 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 724 m_freem(m); 725 return; 726 } 727 728 if (hlen != 0 && hlen != ar->ar_hln) { 729 ARP_LOG(LOG_NOTICE, 730 "packet with invalid %s address length %d received on %s\n", 731 layer, ar->ar_hln, if_name(ifp)); 732 m_freem(m); 733 return; 734 } 735 736 ARPSTAT_INC(received); 737 switch (ntohs(ar->ar_pro)) { 738 #ifdef INET 739 case ETHERTYPE_IP: 740 in_arpinput(m); 741 return; 742 #endif 743 } 744 m_freem(m); 745 } 746 747 #ifdef INET 748 /* 749 * ARP for Internet protocols on 10 Mb/s Ethernet. 750 * Algorithm is that given in RFC 826. 751 * In addition, a sanity check is performed on the sender 752 * protocol address, to catch impersonators. 753 * We no longer handle negotiations for use of trailer protocol: 754 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 755 * along with IP replies if we wanted trailers sent to us, 756 * and also sent them in response to IP replies. 757 * This allowed either end to announce the desire to receive 758 * trailer packets. 759 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 760 * but formerly didn't normally send requests. 761 */ 762 static int log_arp_wrong_iface = 1; 763 static int log_arp_movements = 1; 764 static int log_arp_permanent_modify = 1; 765 static int allow_multicast = 0; 766 767 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 768 &log_arp_wrong_iface, 0, 769 "log arp packets arriving on the wrong interface"); 770 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 771 &log_arp_movements, 0, 772 "log arp replies from MACs different than the one in the cache"); 773 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 774 &log_arp_permanent_modify, 0, 775 "log arp replies from MACs different than the one in the permanent arp entry"); 776 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 777 &allow_multicast, 0, "accept multicast addresses"); 778 779 static void 780 in_arpinput(struct mbuf *m) 781 { 782 struct rm_priotracker in_ifa_tracker; 783 struct arphdr *ah; 784 struct ifnet *ifp = m->m_pkthdr.rcvif; 785 struct llentry *la = NULL, *la_tmp; 786 struct ifaddr *ifa; 787 struct in_ifaddr *ia; 788 struct sockaddr sa; 789 struct in_addr isaddr, itaddr, myaddr; 790 u_int8_t *enaddr = NULL; 791 int op; 792 int bridged = 0, is_bridge = 0; 793 int carped; 794 struct sockaddr_in sin; 795 struct sockaddr *dst; 796 struct nhop_object *nh; 797 uint8_t linkhdr[LLE_MAX_LINKHDR]; 798 struct route ro; 799 size_t linkhdrsize; 800 int lladdr_off; 801 int error; 802 char addrbuf[INET_ADDRSTRLEN]; 803 804 NET_EPOCH_ASSERT(); 805 806 sin.sin_len = sizeof(struct sockaddr_in); 807 sin.sin_family = AF_INET; 808 sin.sin_addr.s_addr = 0; 809 810 if (ifp->if_bridge) 811 bridged = 1; 812 if (ifp->if_type == IFT_BRIDGE) 813 is_bridge = 1; 814 815 /* 816 * We already have checked that mbuf contains enough contiguous data 817 * to hold entire arp message according to the arp header. 818 */ 819 ah = mtod(m, struct arphdr *); 820 821 /* 822 * ARP is only for IPv4 so we can reject packets with 823 * a protocol length not equal to an IPv4 address. 824 */ 825 if (ah->ar_pln != sizeof(struct in_addr)) { 826 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 827 sizeof(struct in_addr)); 828 goto drop; 829 } 830 831 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 832 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 833 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 834 goto drop; 835 } 836 837 op = ntohs(ah->ar_op); 838 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 839 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 840 841 if (op == ARPOP_REPLY) 842 ARPSTAT_INC(rxreplies); 843 844 /* 845 * For a bridge, we want to check the address irrespective 846 * of the receive interface. (This will change slightly 847 * when we have clusters of interfaces). 848 */ 849 IN_IFADDR_RLOCK(&in_ifa_tracker); 850 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 851 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 852 ia->ia_ifp == ifp) && 853 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 854 (ia->ia_ifa.ifa_carp == NULL || 855 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 856 ifa_ref(&ia->ia_ifa); 857 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 858 goto match; 859 } 860 } 861 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 862 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 863 ia->ia_ifp == ifp) && 864 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 865 ifa_ref(&ia->ia_ifa); 866 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 867 goto match; 868 } 869 870 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 871 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 872 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 873 addr == ia->ia_addr.sin_addr.s_addr) 874 /* 875 * Check the case when bridge shares its MAC address with 876 * some of its children, so packets are claimed by bridge 877 * itself (bridge_input() does it first), but they are really 878 * meant to be destined to the bridge member. 879 */ 880 if (is_bridge) { 881 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 882 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 883 ifa_ref(&ia->ia_ifa); 884 ifp = ia->ia_ifp; 885 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 886 goto match; 887 } 888 } 889 } 890 #undef BDG_MEMBER_MATCHES_ARP 891 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 892 893 /* 894 * No match, use the first inet address on the receive interface 895 * as a dummy address for the rest of the function. 896 */ 897 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 898 if (ifa->ifa_addr->sa_family == AF_INET && 899 (ifa->ifa_carp == NULL || 900 (*carp_iamatch_p)(ifa, &enaddr))) { 901 ia = ifatoia(ifa); 902 ifa_ref(ifa); 903 goto match; 904 } 905 906 /* 907 * If bridging, fall back to using any inet address. 908 */ 909 IN_IFADDR_RLOCK(&in_ifa_tracker); 910 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 911 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 912 goto drop; 913 } 914 ifa_ref(&ia->ia_ifa); 915 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 916 match: 917 if (!enaddr) 918 enaddr = (u_int8_t *)IF_LLADDR(ifp); 919 carped = (ia->ia_ifa.ifa_carp != NULL); 920 myaddr = ia->ia_addr.sin_addr; 921 ifa_free(&ia->ia_ifa); 922 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 923 goto drop; /* it's from me, ignore it. */ 924 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 925 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 926 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 927 goto drop; 928 } 929 930 if (ifp->if_addrlen != ah->ar_hln) { 931 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 932 "i/f %d (ignored)\n", ifp->if_addrlen, 933 (u_char *) ar_sha(ah), ":", ah->ar_hln, 934 ifp->if_addrlen); 935 goto drop; 936 } 937 938 /* 939 * Warn if another host is using the same IP address, but only if the 940 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 941 * case we suppress the warning to avoid false positive complaints of 942 * potential misconfiguration. 943 */ 944 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 945 myaddr.s_addr != 0) { 946 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 947 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 948 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 949 itaddr = myaddr; 950 ARPSTAT_INC(dupips); 951 goto reply; 952 } 953 if (ifp->if_flags & IFF_STATICARP) 954 goto reply; 955 956 bzero(&sin, sizeof(sin)); 957 sin.sin_len = sizeof(struct sockaddr_in); 958 sin.sin_family = AF_INET; 959 sin.sin_addr = isaddr; 960 dst = (struct sockaddr *)&sin; 961 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 962 if (la != NULL) 963 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 964 else if (itaddr.s_addr == myaddr.s_addr) { 965 /* 966 * Request/reply to our address, but no lle exists yet. 967 * Calculate full link prepend to use in lle. 968 */ 969 linkhdrsize = sizeof(linkhdr); 970 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 971 &linkhdrsize, &lladdr_off) != 0) 972 goto reply; 973 974 /* Allocate new entry */ 975 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 976 if (la == NULL) { 977 /* 978 * lle creation may fail if source address belongs 979 * to non-directly connected subnet. However, we 980 * will try to answer the request instead of dropping 981 * frame. 982 */ 983 goto reply; 984 } 985 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 986 lladdr_off); 987 988 IF_AFDATA_WLOCK(ifp); 989 LLE_WLOCK(la); 990 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 991 992 /* 993 * Check if lle still does not exists. 994 * If it does, that means that we either 995 * 1) have configured it explicitly, via 996 * 1a) 'arp -s' static entry or 997 * 1b) interface address static record 998 * or 999 * 2) it was the result of sending first packet to-host 1000 * or 1001 * 3) it was another arp reply packet we handled in 1002 * different thread. 1003 * 1004 * In all cases except 3) we definitely need to prefer 1005 * existing lle. For the sake of simplicity, prefer any 1006 * existing lle over newly-create one. 1007 */ 1008 if (la_tmp == NULL) 1009 lltable_link_entry(LLTABLE(ifp), la); 1010 IF_AFDATA_WUNLOCK(ifp); 1011 1012 if (la_tmp == NULL) { 1013 arp_mark_lle_reachable(la); 1014 LLE_WUNLOCK(la); 1015 } else { 1016 /* Free newly-create entry and handle packet */ 1017 lltable_free_entry(LLTABLE(ifp), la); 1018 la = la_tmp; 1019 la_tmp = NULL; 1020 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1021 /* arp_check_update_lle() returns @la unlocked */ 1022 } 1023 la = NULL; 1024 } 1025 reply: 1026 if (op != ARPOP_REQUEST) 1027 goto drop; 1028 ARPSTAT_INC(rxrequests); 1029 1030 if (itaddr.s_addr == myaddr.s_addr) { 1031 /* Shortcut.. the receiving interface is the target. */ 1032 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1033 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1034 } else { 1035 /* 1036 * Destination address is not ours. Check if 1037 * proxyarp entry exists or proxyarp is turned on globally. 1038 */ 1039 struct llentry *lle; 1040 1041 sin.sin_addr = itaddr; 1042 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1043 1044 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1045 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1046 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1047 LLE_RUNLOCK(lle); 1048 } else { 1049 if (lle != NULL) 1050 LLE_RUNLOCK(lle); 1051 1052 if (!V_arp_proxyall) 1053 goto drop; 1054 1055 NET_EPOCH_ASSERT(); 1056 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0); 1057 if (nh == NULL) 1058 goto drop; 1059 1060 /* 1061 * Don't send proxies for nodes on the same interface 1062 * as this one came out of, or we'll get into a fight 1063 * over who claims what Ether address. 1064 */ 1065 if (nh->nh_ifp == ifp) 1066 goto drop; 1067 1068 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1069 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1070 1071 /* 1072 * Also check that the node which sent the ARP packet 1073 * is on the interface we expect it to be on. This 1074 * avoids ARP chaos if an interface is connected to the 1075 * wrong network. 1076 */ 1077 1078 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0); 1079 if (nh == NULL) 1080 goto drop; 1081 if (nh->nh_ifp != ifp) { 1082 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1083 " from %s via %s\n", 1084 inet_ntoa_r(isaddr, addrbuf), 1085 ifp->if_xname); 1086 goto drop; 1087 } 1088 1089 #ifdef DEBUG_PROXY 1090 printf("arp: proxying for %s\n", 1091 inet_ntoa_r(itaddr, addrbuf)); 1092 #endif 1093 } 1094 } 1095 1096 if (itaddr.s_addr == myaddr.s_addr && 1097 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1098 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1099 #ifdef DEBUG_LINKLOCAL 1100 printf("arp: sending reply for link-local addr %s\n", 1101 inet_ntoa_r(itaddr, addrbuf)); 1102 #endif 1103 m->m_flags |= M_BCAST; 1104 m->m_flags &= ~M_MCAST; 1105 } else { 1106 /* default behaviour; never reply by broadcast. */ 1107 m->m_flags &= ~(M_BCAST|M_MCAST); 1108 } 1109 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1110 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1111 ah->ar_op = htons(ARPOP_REPLY); 1112 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1113 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1114 m->m_pkthdr.len = m->m_len; 1115 m->m_pkthdr.rcvif = NULL; 1116 sa.sa_family = AF_ARP; 1117 sa.sa_len = 2; 1118 1119 /* Calculate link header for sending frame */ 1120 bzero(&ro, sizeof(ro)); 1121 linkhdrsize = sizeof(linkhdr); 1122 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1123 1124 /* 1125 * arp_fillheader() may fail due to lack of support inside encap request 1126 * routing. This is not necessary an error, AF_ARP can/should be handled 1127 * by if_output(). 1128 */ 1129 if (error != 0 && error != EAFNOSUPPORT) { 1130 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1131 if_name(ifp), error); 1132 goto drop; 1133 } 1134 1135 ro.ro_prepend = linkhdr; 1136 ro.ro_plen = linkhdrsize; 1137 ro.ro_flags = 0; 1138 1139 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1140 (*ifp->if_output)(ifp, m, &sa, &ro); 1141 ARPSTAT_INC(txreplies); 1142 return; 1143 1144 drop: 1145 m_freem(m); 1146 } 1147 #endif 1148 1149 static struct mbuf * 1150 arp_grab_holdchain(struct llentry *la) 1151 { 1152 struct mbuf *chain; 1153 1154 LLE_WLOCK_ASSERT(la); 1155 1156 chain = la->la_hold; 1157 la->la_hold = NULL; 1158 la->la_numheld = 0; 1159 1160 return (chain); 1161 } 1162 1163 static void 1164 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain) 1165 { 1166 struct mbuf *m_hold, *m_hold_next; 1167 struct sockaddr_in sin; 1168 1169 NET_EPOCH_ASSERT(); 1170 1171 struct route ro = { 1172 .ro_prepend = la->r_linkdata, 1173 .ro_plen = la->r_hdrlen, 1174 }; 1175 1176 lltable_fill_sa_entry(la, (struct sockaddr *)&sin); 1177 1178 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) { 1179 m_hold_next = m_hold->m_nextpkt; 1180 m_hold->m_nextpkt = NULL; 1181 /* Avoid confusing lower layers. */ 1182 m_clrprotoflags(m_hold); 1183 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro); 1184 } 1185 } 1186 1187 /* 1188 * Checks received arp data against existing @la. 1189 * Updates lle state/performs notification if necessary. 1190 */ 1191 static void 1192 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1193 int bridged, struct llentry *la) 1194 { 1195 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1196 size_t linkhdrsize; 1197 int lladdr_off; 1198 char addrbuf[INET_ADDRSTRLEN]; 1199 1200 LLE_WLOCK_ASSERT(la); 1201 1202 /* the following is not an error when doing bridging */ 1203 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1204 if (log_arp_wrong_iface) 1205 ARP_LOG(LOG_WARNING, "%s is on %s " 1206 "but got reply from %*D on %s\n", 1207 inet_ntoa_r(isaddr, addrbuf), 1208 la->lle_tbl->llt_ifp->if_xname, 1209 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1210 ifp->if_xname); 1211 LLE_WUNLOCK(la); 1212 return; 1213 } 1214 if ((la->la_flags & LLE_VALID) && 1215 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1216 if (la->la_flags & LLE_STATIC) { 1217 LLE_WUNLOCK(la); 1218 if (log_arp_permanent_modify) 1219 ARP_LOG(LOG_ERR, 1220 "%*D attempts to modify " 1221 "permanent entry for %s on %s\n", 1222 ifp->if_addrlen, 1223 (u_char *)ar_sha(ah), ":", 1224 inet_ntoa_r(isaddr, addrbuf), 1225 ifp->if_xname); 1226 return; 1227 } 1228 if (log_arp_movements) { 1229 ARP_LOG(LOG_INFO, "%s moved from %*D " 1230 "to %*D on %s\n", 1231 inet_ntoa_r(isaddr, addrbuf), 1232 ifp->if_addrlen, 1233 (u_char *)la->ll_addr, ":", 1234 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1235 ifp->if_xname); 1236 } 1237 } 1238 1239 /* Calculate full link prepend to use in lle */ 1240 linkhdrsize = sizeof(linkhdr); 1241 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1242 &linkhdrsize, &lladdr_off) != 0) 1243 return; 1244 1245 /* Check if something has changed */ 1246 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1247 (la->la_flags & LLE_VALID) == 0) { 1248 /* Try to perform LLE update */ 1249 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1250 lladdr_off) == 0) 1251 return; 1252 1253 /* Clear fast path feedback request if set */ 1254 llentry_mark_used(la); 1255 } 1256 1257 arp_mark_lle_reachable(la); 1258 1259 /* 1260 * The packets are all freed within the call to the output 1261 * routine. 1262 * 1263 * NB: The lock MUST be released before the call to the 1264 * output routine. 1265 */ 1266 if (la->la_hold != NULL) { 1267 struct mbuf *chain; 1268 1269 chain = arp_grab_holdchain(la); 1270 LLE_WUNLOCK(la); 1271 arp_flush_holdchain(ifp, la, chain); 1272 } else 1273 LLE_WUNLOCK(la); 1274 } 1275 1276 static void 1277 arp_mark_lle_reachable(struct llentry *la) 1278 { 1279 int canceled, wtime; 1280 1281 LLE_WLOCK_ASSERT(la); 1282 1283 la->ln_state = ARP_LLINFO_REACHABLE; 1284 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1285 1286 if (!(la->la_flags & LLE_STATIC)) { 1287 LLE_ADDREF(la); 1288 la->la_expire = time_uptime + V_arpt_keep; 1289 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1290 if (wtime < 0) 1291 wtime = V_arpt_keep; 1292 canceled = callout_reset(&la->lle_timer, 1293 hz * wtime, arptimer, la); 1294 if (canceled) 1295 LLE_REMREF(la); 1296 } 1297 la->la_asked = 0; 1298 la->la_preempt = V_arp_maxtries; 1299 } 1300 1301 /* 1302 * Add permanent link-layer record for given interface address. 1303 */ 1304 static __noinline void 1305 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1306 { 1307 struct llentry *lle, *lle_tmp; 1308 1309 /* 1310 * Interface address LLE record is considered static 1311 * because kernel code relies on LLE_STATIC flag to check 1312 * if these entries can be rewriten by arp updates. 1313 */ 1314 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1315 if (lle == NULL) { 1316 log(LOG_INFO, "arp_ifinit: cannot create arp " 1317 "entry for interface address\n"); 1318 return; 1319 } 1320 1321 IF_AFDATA_WLOCK(ifp); 1322 LLE_WLOCK(lle); 1323 /* Unlink any entry if exists */ 1324 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1325 if (lle_tmp != NULL) 1326 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1327 1328 lltable_link_entry(LLTABLE(ifp), lle); 1329 IF_AFDATA_WUNLOCK(ifp); 1330 1331 if (lle_tmp != NULL) 1332 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1333 1334 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1335 LLE_WUNLOCK(lle); 1336 if (lle_tmp != NULL) 1337 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1338 } 1339 1340 /* 1341 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1342 * of valid values. 1343 */ 1344 static int 1345 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1346 { 1347 int error; 1348 int rexmit_count = *(int *)arg1; 1349 1350 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1351 1352 /* Enforce limits on any new value that may have been set. */ 1353 if (!error && req->newptr) { 1354 /* A new value was set. */ 1355 if (rexmit_count < 0) { 1356 rexmit_count = 0; 1357 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1358 rexmit_count = MAX_GARP_RETRANSMITS; 1359 } 1360 *(int *)arg1 = rexmit_count; 1361 } 1362 1363 return (error); 1364 } 1365 1366 /* 1367 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1368 * retransmit it again. A pending callout owns a reference to the ifa. 1369 */ 1370 static void 1371 garp_rexmit(void *arg) 1372 { 1373 struct in_ifaddr *ia = arg; 1374 1375 if (callout_pending(&ia->ia_garp_timer) || 1376 !callout_active(&ia->ia_garp_timer)) { 1377 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1378 ifa_free(&ia->ia_ifa); 1379 return; 1380 } 1381 1382 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1383 1384 /* 1385 * Drop lock while the ARP request is generated. 1386 */ 1387 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1388 1389 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1390 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1391 1392 /* 1393 * Increment the count of retransmissions. If the count has reached the 1394 * maximum value, stop sending the GARP packets. Otherwise, schedule 1395 * the callout to retransmit another GARP packet. 1396 */ 1397 ++ia->ia_garp_count; 1398 if (ia->ia_garp_count >= garp_rexmit_count) { 1399 ifa_free(&ia->ia_ifa); 1400 } else { 1401 int rescheduled; 1402 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1403 rescheduled = callout_reset(&ia->ia_garp_timer, 1404 (1 << ia->ia_garp_count) * hz, 1405 garp_rexmit, ia); 1406 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1407 if (rescheduled) { 1408 ifa_free(&ia->ia_ifa); 1409 } 1410 } 1411 1412 CURVNET_RESTORE(); 1413 } 1414 1415 /* 1416 * Start the GARP retransmit timer. 1417 * 1418 * A single GARP is always transmitted when an IPv4 address is added 1419 * to an interface and that is usually sufficient. However, in some 1420 * circumstances, such as when a shared address is passed between 1421 * cluster nodes, this single GARP may occasionally be dropped or 1422 * lost. This can lead to neighbors on the network link working with a 1423 * stale ARP cache and sending packets destined for that address to 1424 * the node that previously owned the address, which may not respond. 1425 * 1426 * To avoid this situation, GARP retransmits can be enabled by setting 1427 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1428 * than zero. The setting represents the maximum number of 1429 * retransmissions. The interval between retransmissions is calculated 1430 * using an exponential backoff algorithm, doubling each time, so the 1431 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1432 */ 1433 static void 1434 garp_timer_start(struct ifaddr *ifa) 1435 { 1436 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1437 1438 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1439 ia->ia_garp_count = 0; 1440 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1441 garp_rexmit, ia) == 0) { 1442 ifa_ref(ifa); 1443 } 1444 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1445 } 1446 1447 void 1448 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1449 { 1450 struct epoch_tracker et; 1451 const struct sockaddr_in *dst_in; 1452 const struct sockaddr *dst; 1453 1454 if (ifa->ifa_carp != NULL) 1455 return; 1456 1457 dst = ifa->ifa_addr; 1458 dst_in = (const struct sockaddr_in *)dst; 1459 1460 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1461 return; 1462 NET_EPOCH_ENTER(et); 1463 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1464 NET_EPOCH_EXIT(et); 1465 if (garp_rexmit_count > 0) { 1466 garp_timer_start(ifa); 1467 } 1468 1469 arp_add_ifa_lle(ifp, dst); 1470 } 1471 1472 void 1473 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1474 { 1475 1476 if (ntohl(addr.s_addr) != INADDR_ANY) 1477 arprequest(ifp, &addr, &addr, enaddr); 1478 } 1479 1480 /* 1481 * Sends gratuitous ARPs for each ifaddr to notify other 1482 * nodes about the address change. 1483 */ 1484 static __noinline void 1485 arp_handle_ifllchange(struct ifnet *ifp) 1486 { 1487 struct ifaddr *ifa; 1488 1489 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1490 if (ifa->ifa_addr->sa_family == AF_INET) 1491 arp_ifinit(ifp, ifa); 1492 } 1493 } 1494 1495 /* 1496 * A handler for interface link layer address change event. 1497 */ 1498 static void 1499 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1500 { 1501 /* if_bridge can update its lladdr during if_vmove(), after we've done 1502 * if_detach_internal()/dom_ifdetach(). */ 1503 if (ifp->if_afdata[AF_INET] == NULL) 1504 return; 1505 1506 lltable_update_ifaddr(LLTABLE(ifp)); 1507 1508 if ((ifp->if_flags & IFF_UP) != 0) 1509 arp_handle_ifllchange(ifp); 1510 } 1511 1512 static void 1513 vnet_arp_init(void) 1514 { 1515 1516 if (IS_DEFAULT_VNET(curvnet)) { 1517 netisr_register(&arp_nh); 1518 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1519 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1520 } 1521 #ifdef VIMAGE 1522 else 1523 netisr_register_vnet(&arp_nh); 1524 #endif 1525 } 1526 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1527 vnet_arp_init, 0); 1528 1529 #ifdef VIMAGE 1530 /* 1531 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1532 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1533 */ 1534 static void 1535 vnet_arp_destroy(__unused void *arg) 1536 { 1537 1538 netisr_unregister_vnet(&arp_nh); 1539 } 1540 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1541 vnet_arp_destroy, NULL); 1542 #endif 1543