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