1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 32 */ 33 34 /* 35 * Ethernet address resolution protocol. 36 * TODO: 37 * add "inuse/lock" bit (or ref. count) along with valid bit 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "opt_inet.h" 44 45 #include <sys/param.h> 46 #include <sys/eventhandler.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/queue.h> 50 #include <sys/sysctl.h> 51 #include <sys/systm.h> 52 #include <sys/mbuf.h> 53 #include <sys/malloc.h> 54 #include <sys/proc.h> 55 #include <sys/socket.h> 56 #include <sys/syslog.h> 57 58 #include <net/if.h> 59 #include <net/if_var.h> 60 #include <net/if_dl.h> 61 #include <net/if_types.h> 62 #include <net/netisr.h> 63 #include <net/ethernet.h> 64 #include <net/route.h> 65 #include <net/route/nhop.h> 66 #include <net/vnet.h> 67 68 #include <netinet/in.h> 69 #include <netinet/in_fib.h> 70 #include <netinet/in_var.h> 71 #include <net/if_llatbl.h> 72 #include <netinet/if_ether.h> 73 #ifdef INET 74 #include <netinet/ip_carp.h> 75 #endif 76 77 #include <security/mac/mac_framework.h> 78 79 #define SIN(s) ((const struct sockaddr_in *)(s)) 80 81 static struct timeval arp_lastlog; 82 static int arp_curpps; 83 static int arp_maxpps = 1; 84 85 /* Simple ARP state machine */ 86 enum arp_llinfo_state { 87 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 88 ARP_LLINFO_REACHABLE, /* LLE is valid */ 89 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 90 ARP_LLINFO_DELETED, /* LLE is deleted */ 91 }; 92 93 SYSCTL_DECL(_net_link_ether); 94 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, 95 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 96 ""); 97 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, 98 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 99 ""); 100 101 /* timer values */ 102 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 103 * minutes */ 104 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 105 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 106 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 107 * 20 seconds */ 108 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 109 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 110 VNET_PCPUSTAT_SYSINIT(arpstat); 111 112 #ifdef VIMAGE 113 VNET_PCPUSTAT_SYSUNINIT(arpstat); 114 #endif /* VIMAGE */ 115 116 VNET_DEFINE_STATIC(int, arp_maxhold) = 16; 117 118 #define V_arpt_keep VNET(arpt_keep) 119 #define V_arpt_down VNET(arpt_down) 120 #define V_arpt_rexmit VNET(arpt_rexmit) 121 #define V_arp_maxtries VNET(arp_maxtries) 122 #define V_arp_proxyall VNET(arp_proxyall) 123 #define V_arp_maxhold VNET(arp_maxhold) 124 125 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 126 &VNET_NAME(arpt_keep), 0, 127 "ARP entry lifetime in seconds"); 128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 129 &VNET_NAME(arp_maxtries), 0, 130 "ARP resolution attempts before returning error"); 131 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 132 &VNET_NAME(arp_proxyall), 0, 133 "Enable proxy ARP for all suitable requests"); 134 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 135 &VNET_NAME(arpt_down), 0, 136 "Incomplete ARP entry lifetime in seconds"); 137 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 138 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 139 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 140 &VNET_NAME(arp_maxhold), 0, 141 "Number of packets to hold per ARP entry"); 142 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 143 CTLFLAG_RW, &arp_maxpps, 0, 144 "Maximum number of remotely triggered ARP messages that can be " 145 "logged per second"); 146 147 /* 148 * Due to the exponential backoff algorithm used for the interval between GARP 149 * retransmissions, the maximum number of retransmissions is limited for 150 * sanity. This limit corresponds to a maximum interval between retransmissions 151 * of 2^16 seconds ~= 18 hours. 152 * 153 * Making this limit more dynamic is more complicated than worthwhile, 154 * especially since sending out GARPs spaced days apart would be of little 155 * use. A maximum dynamic limit would look something like: 156 * 157 * const int max = fls(INT_MAX / hz) - 1; 158 */ 159 #define MAX_GARP_RETRANSMITS 16 160 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 161 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 162 163 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 164 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 165 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 166 "Number of times to retransmit GARP packets;" 167 " 0 to disable, maximum of 16"); 168 169 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 170 #define V_arp_log_level VNET(arp_log_level) 171 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 172 &VNET_NAME(arp_log_level), 0, 173 "Minimum log(9) level for recording rate limited arp log messages. " 174 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 175 #define ARP_LOG(pri, ...) do { \ 176 if ((pri) <= V_arp_log_level && \ 177 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 178 log((pri), "arp: " __VA_ARGS__); \ 179 } while (0) 180 181 static void arpintr(struct mbuf *); 182 static void arptimer(void *); 183 #ifdef INET 184 static void in_arpinput(struct mbuf *); 185 #endif 186 187 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 188 struct ifnet *ifp, int bridged, struct llentry *la); 189 static void arp_mark_lle_reachable(struct llentry *la); 190 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 191 192 static eventhandler_tag iflladdr_tag; 193 194 static const struct netisr_handler arp_nh = { 195 .nh_name = "arp", 196 .nh_handler = arpintr, 197 .nh_proto = NETISR_ARP, 198 .nh_policy = NETISR_POLICY_SOURCE, 199 }; 200 201 /* 202 * Timeout routine. Age arp_tab entries periodically. 203 */ 204 static void 205 arptimer(void *arg) 206 { 207 struct llentry *lle = (struct llentry *)arg; 208 struct ifnet *ifp; 209 210 if (lle->la_flags & LLE_STATIC) { 211 return; 212 } 213 LLE_WLOCK(lle); 214 if (callout_pending(&lle->lle_timer)) { 215 /* 216 * Here we are a bit odd here in the treatment of 217 * active/pending. If the pending bit is set, it got 218 * rescheduled before I ran. The active 219 * bit we ignore, since if it was stopped 220 * in ll_tablefree() and was currently running 221 * it would have return 0 so the code would 222 * not have deleted it since the callout could 223 * not be stopped so we want to go through 224 * with the delete here now. If the callout 225 * was restarted, the pending bit will be back on and 226 * we just want to bail since the callout_reset would 227 * return 1 and our reference would have been removed 228 * by arpresolve() below. 229 */ 230 LLE_WUNLOCK(lle); 231 return; 232 } 233 ifp = lle->lle_tbl->llt_ifp; 234 CURVNET_SET(ifp->if_vnet); 235 236 switch (lle->ln_state) { 237 case ARP_LLINFO_REACHABLE: 238 239 /* 240 * Expiration time is approaching. 241 * Request usage feedback from the datapath. 242 * Change state and re-schedule ourselves. 243 */ 244 llentry_request_feedback(lle); 245 lle->ln_state = ARP_LLINFO_VERIFY; 246 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 247 LLE_WUNLOCK(lle); 248 CURVNET_RESTORE(); 249 return; 250 case ARP_LLINFO_VERIFY: 251 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) { 252 /* Entry was used, issue refresh request */ 253 struct epoch_tracker et; 254 struct in_addr dst; 255 256 dst = lle->r_l3addr.addr4; 257 lle->la_preempt--; 258 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 259 LLE_WUNLOCK(lle); 260 NET_EPOCH_ENTER(et); 261 arprequest(ifp, NULL, &dst, NULL); 262 NET_EPOCH_EXIT(et); 263 CURVNET_RESTORE(); 264 return; 265 } 266 /* Nothing happened. Reschedule if not too late */ 267 if (lle->la_expire > time_uptime) { 268 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 269 LLE_WUNLOCK(lle); 270 CURVNET_RESTORE(); 271 return; 272 } 273 break; 274 case ARP_LLINFO_INCOMPLETE: 275 case ARP_LLINFO_DELETED: 276 break; 277 } 278 279 if ((lle->la_flags & LLE_DELETED) == 0) { 280 int evt; 281 282 if (lle->la_flags & LLE_VALID) 283 evt = LLENTRY_EXPIRED; 284 else 285 evt = LLENTRY_TIMEDOUT; 286 EVENTHANDLER_INVOKE(lle_event, lle, evt); 287 } 288 289 callout_stop(&lle->lle_timer); 290 291 /* XXX: LOR avoidance. We still have ref on lle. */ 292 LLE_WUNLOCK(lle); 293 IF_AFDATA_LOCK(ifp); 294 LLE_WLOCK(lle); 295 296 /* Guard against race with other llentry_free(). */ 297 if (lle->la_flags & LLE_LINKED) { 298 LLE_REMREF(lle); 299 lltable_unlink_entry(lle->lle_tbl, lle); 300 } 301 IF_AFDATA_UNLOCK(ifp); 302 303 size_t pkts_dropped = llentry_free(lle); 304 305 ARPSTAT_ADD(dropped, pkts_dropped); 306 ARPSTAT_INC(timeouts); 307 308 CURVNET_RESTORE(); 309 } 310 311 /* 312 * Stores link-layer header for @ifp in format suitable for if_output() 313 * into buffer @buf. Resulting header length is stored in @bufsize. 314 * 315 * Returns 0 on success. 316 */ 317 static int 318 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 319 size_t *bufsize) 320 { 321 struct if_encap_req ereq; 322 int error; 323 324 bzero(buf, *bufsize); 325 bzero(&ereq, sizeof(ereq)); 326 ereq.buf = buf; 327 ereq.bufsize = *bufsize; 328 ereq.rtype = IFENCAP_LL; 329 ereq.family = AF_ARP; 330 ereq.lladdr = ar_tha(ah); 331 ereq.hdata = (u_char *)ah; 332 if (bcast) 333 ereq.flags = IFENCAP_FLAG_BROADCAST; 334 error = ifp->if_requestencap(ifp, &ereq); 335 if (error == 0) 336 *bufsize = ereq.bufsize; 337 338 return (error); 339 } 340 341 /* 342 * Broadcast an ARP request. Caller specifies: 343 * - arp header source ip address 344 * - arp header target ip address 345 * - arp header source ethernet address 346 */ 347 static int 348 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 349 const struct in_addr *tip, u_char *enaddr) 350 { 351 struct mbuf *m; 352 struct arphdr *ah; 353 struct sockaddr sa; 354 u_char *carpaddr = NULL; 355 uint8_t linkhdr[LLE_MAX_LINKHDR]; 356 size_t linkhdrsize; 357 struct route ro; 358 int error; 359 360 NET_EPOCH_ASSERT(); 361 362 if (sip == NULL) { 363 /* 364 * The caller did not supply a source address, try to find 365 * a compatible one among those assigned to this interface. 366 */ 367 struct ifaddr *ifa; 368 369 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 370 if (ifa->ifa_addr->sa_family != AF_INET) 371 continue; 372 373 if (ifa->ifa_carp) { 374 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 375 continue; 376 sip = &IA_SIN(ifa)->sin_addr; 377 } else { 378 carpaddr = NULL; 379 sip = &IA_SIN(ifa)->sin_addr; 380 } 381 382 if (0 == ((sip->s_addr ^ tip->s_addr) & 383 IA_MASKSIN(ifa)->sin_addr.s_addr)) 384 break; /* found it. */ 385 } 386 if (sip == NULL) { 387 printf("%s: cannot find matching address\n", __func__); 388 return (EADDRNOTAVAIL); 389 } 390 } 391 if (enaddr == NULL) 392 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 393 394 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 395 return (ENOMEM); 396 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 397 2 * ifp->if_addrlen; 398 m->m_pkthdr.len = m->m_len; 399 M_ALIGN(m, m->m_len); 400 ah = mtod(m, struct arphdr *); 401 bzero((caddr_t)ah, m->m_len); 402 #ifdef MAC 403 mac_netinet_arp_send(ifp, m); 404 #endif 405 ah->ar_pro = htons(ETHERTYPE_IP); 406 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 407 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 408 ah->ar_op = htons(ARPOP_REQUEST); 409 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 410 bcopy(sip, ar_spa(ah), ah->ar_pln); 411 bcopy(tip, ar_tpa(ah), ah->ar_pln); 412 sa.sa_family = AF_ARP; 413 sa.sa_len = 2; 414 415 /* Calculate link header for sending frame */ 416 bzero(&ro, sizeof(ro)); 417 linkhdrsize = sizeof(linkhdr); 418 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 419 if (error != 0 && error != EAFNOSUPPORT) { 420 m_freem(m); 421 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 422 if_name(ifp), error); 423 return (error); 424 } 425 426 ro.ro_prepend = linkhdr; 427 ro.ro_plen = linkhdrsize; 428 ro.ro_flags = 0; 429 430 m->m_flags |= M_BCAST; 431 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 432 error = (*ifp->if_output)(ifp, m, &sa, &ro); 433 ARPSTAT_INC(txrequests); 434 if (error) { 435 ARPSTAT_INC(txerrors); 436 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 437 if_name(ifp), error); 438 } 439 return (error); 440 } 441 442 void 443 arprequest(struct ifnet *ifp, const struct in_addr *sip, 444 const struct in_addr *tip, u_char *enaddr) 445 { 446 447 (void) arprequest_internal(ifp, sip, tip, enaddr); 448 } 449 450 /* 451 * Resolve an IP address into an ethernet address - heavy version. 452 * Used internally by arpresolve(). 453 * We have already checked that we can't use an existing lle without 454 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 455 * 456 * On success, desten and pflags are filled in and the function returns 0; 457 * If the packet must be held pending resolution, we return EWOULDBLOCK 458 * On other errors, we return the corresponding error code. 459 * Note that m_freem() handles NULL. 460 */ 461 static int 462 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 463 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 464 struct llentry **plle) 465 { 466 struct llentry *la = NULL, *la_tmp; 467 struct mbuf *curr = NULL; 468 struct mbuf *next = NULL; 469 int error, renew; 470 char *lladdr; 471 int ll_len; 472 473 NET_EPOCH_ASSERT(); 474 475 if (pflags != NULL) 476 *pflags = 0; 477 if (plle != NULL) 478 *plle = NULL; 479 480 if ((flags & LLE_CREATE) == 0) 481 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 482 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 483 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 484 if (la == NULL) { 485 char addrbuf[INET_ADDRSTRLEN]; 486 487 log(LOG_DEBUG, 488 "arpresolve: can't allocate llinfo for %s on %s\n", 489 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 490 if_name(ifp)); 491 m_freem(m); 492 return (EINVAL); 493 } 494 495 IF_AFDATA_WLOCK(ifp); 496 LLE_WLOCK(la); 497 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 498 /* Prefer ANY existing lle over newly-created one */ 499 if (la_tmp == NULL) 500 lltable_link_entry(LLTABLE(ifp), la); 501 IF_AFDATA_WUNLOCK(ifp); 502 if (la_tmp != NULL) { 503 lltable_free_entry(LLTABLE(ifp), la); 504 la = la_tmp; 505 } 506 } 507 if (la == NULL) { 508 m_freem(m); 509 return (EINVAL); 510 } 511 512 if ((la->la_flags & LLE_VALID) && 513 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 514 if (flags & LLE_ADDRONLY) { 515 lladdr = la->ll_addr; 516 ll_len = ifp->if_addrlen; 517 } else { 518 lladdr = la->r_linkdata; 519 ll_len = la->r_hdrlen; 520 } 521 bcopy(lladdr, desten, ll_len); 522 523 /* Notify LLE code that the entry was used by datapath */ 524 llentry_provide_feedback(la); 525 if (pflags != NULL) 526 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 527 if (plle) { 528 LLE_ADDREF(la); 529 *plle = la; 530 } 531 LLE_WUNLOCK(la); 532 return (0); 533 } 534 535 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 536 /* 537 * There is an arptab entry, but no ethernet address 538 * response yet. Add the mbuf to the list, dropping 539 * the oldest packet if we have exceeded the system 540 * setting. 541 */ 542 if (m != NULL) { 543 if (la->la_numheld >= V_arp_maxhold) { 544 if (la->la_hold != NULL) { 545 next = la->la_hold->m_nextpkt; 546 m_freem(la->la_hold); 547 la->la_hold = next; 548 la->la_numheld--; 549 ARPSTAT_INC(dropped); 550 } 551 } 552 if (la->la_hold != NULL) { 553 curr = la->la_hold; 554 while (curr->m_nextpkt != NULL) 555 curr = curr->m_nextpkt; 556 curr->m_nextpkt = m; 557 } else 558 la->la_hold = m; 559 la->la_numheld++; 560 } 561 /* 562 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 563 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 564 * if we have already sent arp_maxtries ARP requests. Retransmit the 565 * ARP request, but not faster than one request per second. 566 */ 567 if (la->la_asked < V_arp_maxtries) 568 error = EWOULDBLOCK; /* First request. */ 569 else 570 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 571 572 if (renew) { 573 int canceled, e; 574 575 LLE_ADDREF(la); 576 la->la_expire = time_uptime; 577 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 578 arptimer, la); 579 if (canceled) 580 LLE_REMREF(la); 581 la->la_asked++; 582 LLE_WUNLOCK(la); 583 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL); 584 /* 585 * Only overwrite 'error' in case of error; in case of success 586 * the proper return value was already set above. 587 */ 588 if (e != 0) 589 return (e); 590 return (error); 591 } 592 593 LLE_WUNLOCK(la); 594 return (error); 595 } 596 597 /* 598 * Lookups link header based on an IP address. 599 * On input: 600 * ifp is the interface we use 601 * is_gw != 0 if @dst represents gateway to some destination 602 * m is the mbuf. May be NULL if we don't have a packet. 603 * dst is the next hop, 604 * desten is the storage to put LL header. 605 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 606 * 607 * On success, full/partial link header and flags are filled in and 608 * the function returns 0. 609 * If the packet must be held pending resolution, we return EWOULDBLOCK 610 * On other errors, we return the corresponding error code. 611 * Note that m_freem() handles NULL. 612 */ 613 int 614 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 615 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 616 struct llentry **plle) 617 { 618 struct llentry *la = NULL; 619 620 NET_EPOCH_ASSERT(); 621 622 if (pflags != NULL) 623 *pflags = 0; 624 if (plle != NULL) 625 *plle = NULL; 626 627 if (m != NULL) { 628 if (m->m_flags & M_BCAST) { 629 /* broadcast */ 630 (void)memcpy(desten, 631 ifp->if_broadcastaddr, ifp->if_addrlen); 632 return (0); 633 } 634 if (m->m_flags & M_MCAST) { 635 /* multicast */ 636 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 637 return (0); 638 } 639 } 640 641 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 642 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 643 /* Entry found, let's copy lle info */ 644 bcopy(la->r_linkdata, desten, la->r_hdrlen); 645 if (pflags != NULL) 646 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 647 /* Notify the LLE handling code that the entry was used. */ 648 llentry_provide_feedback(la); 649 if (plle) { 650 LLE_ADDREF(la); 651 *plle = la; 652 LLE_WUNLOCK(la); 653 } 654 return (0); 655 } 656 if (plle && la) 657 LLE_WUNLOCK(la); 658 659 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 660 desten, pflags, plle)); 661 } 662 663 /* 664 * Common length and type checks are done here, 665 * then the protocol-specific routine is called. 666 */ 667 static void 668 arpintr(struct mbuf *m) 669 { 670 struct arphdr *ar; 671 struct ifnet *ifp; 672 char *layer; 673 int hlen; 674 675 ifp = m->m_pkthdr.rcvif; 676 677 if (m->m_len < sizeof(struct arphdr) && 678 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 679 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 680 if_name(ifp)); 681 return; 682 } 683 ar = mtod(m, struct arphdr *); 684 685 /* Check if length is sufficient */ 686 if (m->m_len < arphdr_len(ar)) { 687 m = m_pullup(m, arphdr_len(ar)); 688 if (m == NULL) { 689 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 690 if_name(ifp)); 691 return; 692 } 693 ar = mtod(m, struct arphdr *); 694 } 695 696 hlen = 0; 697 layer = ""; 698 switch (ntohs(ar->ar_hrd)) { 699 case ARPHRD_ETHER: 700 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 701 layer = "ethernet"; 702 break; 703 case ARPHRD_INFINIBAND: 704 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 705 layer = "infiniband"; 706 break; 707 case ARPHRD_IEEE1394: 708 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 709 layer = "firewire"; 710 711 /* 712 * Restrict too long hardware addresses. 713 * Currently we are capable of handling 20-byte 714 * addresses ( sizeof(lle->ll_addr) ) 715 */ 716 if (ar->ar_hln >= 20) 717 hlen = 16; 718 break; 719 default: 720 ARP_LOG(LOG_NOTICE, 721 "packet with unknown hardware format 0x%02d received on " 722 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 723 m_freem(m); 724 return; 725 } 726 727 if (hlen != 0 && hlen != ar->ar_hln) { 728 ARP_LOG(LOG_NOTICE, 729 "packet with invalid %s address length %d received on %s\n", 730 layer, ar->ar_hln, if_name(ifp)); 731 m_freem(m); 732 return; 733 } 734 735 ARPSTAT_INC(received); 736 switch (ntohs(ar->ar_pro)) { 737 #ifdef INET 738 case ETHERTYPE_IP: 739 in_arpinput(m); 740 return; 741 #endif 742 } 743 m_freem(m); 744 } 745 746 #ifdef INET 747 /* 748 * ARP for Internet protocols on 10 Mb/s Ethernet. 749 * Algorithm is that given in RFC 826. 750 * In addition, a sanity check is performed on the sender 751 * protocol address, to catch impersonators. 752 * We no longer handle negotiations for use of trailer protocol: 753 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 754 * along with IP replies if we wanted trailers sent to us, 755 * and also sent them in response to IP replies. 756 * This allowed either end to announce the desire to receive 757 * trailer packets. 758 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 759 * but formerly didn't normally send requests. 760 */ 761 static int log_arp_wrong_iface = 1; 762 static int log_arp_movements = 1; 763 static int log_arp_permanent_modify = 1; 764 static int allow_multicast = 0; 765 766 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 767 &log_arp_wrong_iface, 0, 768 "log arp packets arriving on the wrong interface"); 769 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 770 &log_arp_movements, 0, 771 "log arp replies from MACs different than the one in the cache"); 772 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 773 &log_arp_permanent_modify, 0, 774 "log arp replies from MACs different than the one in the permanent arp entry"); 775 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 776 &allow_multicast, 0, "accept multicast addresses"); 777 778 static void 779 in_arpinput(struct mbuf *m) 780 { 781 struct arphdr *ah; 782 struct ifnet *ifp = m->m_pkthdr.rcvif; 783 struct llentry *la = NULL, *la_tmp; 784 struct ifaddr *ifa; 785 struct in_ifaddr *ia; 786 struct sockaddr sa; 787 struct in_addr isaddr, itaddr, myaddr; 788 u_int8_t *enaddr = NULL; 789 int op; 790 int bridged = 0, is_bridge = 0; 791 int carped; 792 struct sockaddr_in sin; 793 struct sockaddr *dst; 794 struct nhop_object *nh; 795 uint8_t linkhdr[LLE_MAX_LINKHDR]; 796 struct route ro; 797 size_t linkhdrsize; 798 int lladdr_off; 799 int error; 800 char addrbuf[INET_ADDRSTRLEN]; 801 802 NET_EPOCH_ASSERT(); 803 804 sin.sin_len = sizeof(struct sockaddr_in); 805 sin.sin_family = AF_INET; 806 sin.sin_addr.s_addr = 0; 807 808 if (ifp->if_bridge) 809 bridged = 1; 810 if (ifp->if_type == IFT_BRIDGE) 811 is_bridge = 1; 812 813 /* 814 * We already have checked that mbuf contains enough contiguous data 815 * to hold entire arp message according to the arp header. 816 */ 817 ah = mtod(m, struct arphdr *); 818 819 /* 820 * ARP is only for IPv4 so we can reject packets with 821 * a protocol length not equal to an IPv4 address. 822 */ 823 if (ah->ar_pln != sizeof(struct in_addr)) { 824 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 825 sizeof(struct in_addr)); 826 goto drop; 827 } 828 829 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 830 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 831 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 832 goto drop; 833 } 834 835 op = ntohs(ah->ar_op); 836 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 837 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 838 839 if (op == ARPOP_REPLY) 840 ARPSTAT_INC(rxreplies); 841 842 /* 843 * For a bridge, we want to check the address irrespective 844 * of the receive interface. (This will change slightly 845 * when we have clusters of interfaces). 846 */ 847 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 848 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 849 ia->ia_ifp == ifp) && 850 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 851 (ia->ia_ifa.ifa_carp == NULL || 852 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 853 ifa_ref(&ia->ia_ifa); 854 goto match; 855 } 856 } 857 CK_LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 858 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 859 ia->ia_ifp == ifp) && 860 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 861 ifa_ref(&ia->ia_ifa); 862 goto match; 863 } 864 865 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 866 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 867 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 868 addr == ia->ia_addr.sin_addr.s_addr) 869 /* 870 * Check the case when bridge shares its MAC address with 871 * some of its children, so packets are claimed by bridge 872 * itself (bridge_input() does it first), but they are really 873 * meant to be destined to the bridge member. 874 */ 875 if (is_bridge) { 876 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 877 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 878 ifa_ref(&ia->ia_ifa); 879 ifp = ia->ia_ifp; 880 goto match; 881 } 882 } 883 } 884 #undef BDG_MEMBER_MATCHES_ARP 885 886 /* 887 * No match, use the first inet address on the receive interface 888 * as a dummy address for the rest of the function. 889 */ 890 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 891 if (ifa->ifa_addr->sa_family == AF_INET && 892 (ifa->ifa_carp == NULL || 893 (*carp_iamatch_p)(ifa, &enaddr))) { 894 ia = ifatoia(ifa); 895 ifa_ref(ifa); 896 goto match; 897 } 898 899 /* 900 * If bridging, fall back to using any inet address. 901 */ 902 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) 903 goto drop; 904 ifa_ref(&ia->ia_ifa); 905 match: 906 if (!enaddr) 907 enaddr = (u_int8_t *)IF_LLADDR(ifp); 908 carped = (ia->ia_ifa.ifa_carp != NULL); 909 myaddr = ia->ia_addr.sin_addr; 910 ifa_free(&ia->ia_ifa); 911 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 912 goto drop; /* it's from me, ignore it. */ 913 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 914 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 915 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 916 goto drop; 917 } 918 919 if (ifp->if_addrlen != ah->ar_hln) { 920 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 921 "i/f %d (ignored)\n", ifp->if_addrlen, 922 (u_char *) ar_sha(ah), ":", ah->ar_hln, 923 ifp->if_addrlen); 924 goto drop; 925 } 926 927 /* 928 * Warn if another host is using the same IP address, but only if the 929 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 930 * case we suppress the warning to avoid false positive complaints of 931 * potential misconfiguration. 932 */ 933 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 934 myaddr.s_addr != 0) { 935 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 936 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 937 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 938 itaddr = myaddr; 939 ARPSTAT_INC(dupips); 940 goto reply; 941 } 942 if (ifp->if_flags & IFF_STATICARP) 943 goto reply; 944 945 bzero(&sin, sizeof(sin)); 946 sin.sin_len = sizeof(struct sockaddr_in); 947 sin.sin_family = AF_INET; 948 sin.sin_addr = isaddr; 949 dst = (struct sockaddr *)&sin; 950 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 951 if (la != NULL) 952 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 953 else if (itaddr.s_addr == myaddr.s_addr) { 954 /* 955 * Request/reply to our address, but no lle exists yet. 956 * Calculate full link prepend to use in lle. 957 */ 958 linkhdrsize = sizeof(linkhdr); 959 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 960 &linkhdrsize, &lladdr_off) != 0) 961 goto reply; 962 963 /* Allocate new entry */ 964 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 965 if (la == NULL) { 966 /* 967 * lle creation may fail if source address belongs 968 * to non-directly connected subnet. However, we 969 * will try to answer the request instead of dropping 970 * frame. 971 */ 972 goto reply; 973 } 974 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 975 lladdr_off); 976 977 IF_AFDATA_WLOCK(ifp); 978 LLE_WLOCK(la); 979 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 980 981 /* 982 * Check if lle still does not exists. 983 * If it does, that means that we either 984 * 1) have configured it explicitly, via 985 * 1a) 'arp -s' static entry or 986 * 1b) interface address static record 987 * or 988 * 2) it was the result of sending first packet to-host 989 * or 990 * 3) it was another arp reply packet we handled in 991 * different thread. 992 * 993 * In all cases except 3) we definitely need to prefer 994 * existing lle. For the sake of simplicity, prefer any 995 * existing lle over newly-create one. 996 */ 997 if (la_tmp == NULL) 998 lltable_link_entry(LLTABLE(ifp), la); 999 IF_AFDATA_WUNLOCK(ifp); 1000 1001 if (la_tmp == NULL) { 1002 arp_mark_lle_reachable(la); 1003 LLE_WUNLOCK(la); 1004 } else { 1005 /* Free newly-create entry and handle packet */ 1006 lltable_free_entry(LLTABLE(ifp), la); 1007 la = la_tmp; 1008 la_tmp = NULL; 1009 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1010 /* arp_check_update_lle() returns @la unlocked */ 1011 } 1012 la = NULL; 1013 } 1014 reply: 1015 if (op != ARPOP_REQUEST) 1016 goto drop; 1017 ARPSTAT_INC(rxrequests); 1018 1019 if (itaddr.s_addr == myaddr.s_addr) { 1020 /* Shortcut.. the receiving interface is the target. */ 1021 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1022 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1023 } else { 1024 /* 1025 * Destination address is not ours. Check if 1026 * proxyarp entry exists or proxyarp is turned on globally. 1027 */ 1028 struct llentry *lle; 1029 1030 sin.sin_addr = itaddr; 1031 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1032 1033 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1034 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1035 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1036 LLE_RUNLOCK(lle); 1037 } else { 1038 if (lle != NULL) 1039 LLE_RUNLOCK(lle); 1040 1041 if (!V_arp_proxyall) 1042 goto drop; 1043 1044 NET_EPOCH_ASSERT(); 1045 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0); 1046 if (nh == NULL) 1047 goto drop; 1048 1049 /* 1050 * Don't send proxies for nodes on the same interface 1051 * as this one came out of, or we'll get into a fight 1052 * over who claims what Ether address. 1053 */ 1054 if (nh->nh_ifp == ifp) 1055 goto drop; 1056 1057 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1058 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1059 1060 /* 1061 * Also check that the node which sent the ARP packet 1062 * is on the interface we expect it to be on. This 1063 * avoids ARP chaos if an interface is connected to the 1064 * wrong network. 1065 */ 1066 1067 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0); 1068 if (nh == NULL) 1069 goto drop; 1070 if (nh->nh_ifp != ifp) { 1071 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1072 " from %s via %s\n", 1073 inet_ntoa_r(isaddr, addrbuf), 1074 ifp->if_xname); 1075 goto drop; 1076 } 1077 1078 #ifdef DEBUG_PROXY 1079 printf("arp: proxying for %s\n", 1080 inet_ntoa_r(itaddr, addrbuf)); 1081 #endif 1082 } 1083 } 1084 1085 if (itaddr.s_addr == myaddr.s_addr && 1086 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1087 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1088 #ifdef DEBUG_LINKLOCAL 1089 printf("arp: sending reply for link-local addr %s\n", 1090 inet_ntoa_r(itaddr, addrbuf)); 1091 #endif 1092 m->m_flags |= M_BCAST; 1093 m->m_flags &= ~M_MCAST; 1094 } else { 1095 /* default behaviour; never reply by broadcast. */ 1096 m->m_flags &= ~(M_BCAST|M_MCAST); 1097 } 1098 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1099 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1100 ah->ar_op = htons(ARPOP_REPLY); 1101 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1102 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1103 m->m_pkthdr.len = m->m_len; 1104 m->m_pkthdr.rcvif = NULL; 1105 sa.sa_family = AF_ARP; 1106 sa.sa_len = 2; 1107 1108 /* Calculate link header for sending frame */ 1109 bzero(&ro, sizeof(ro)); 1110 linkhdrsize = sizeof(linkhdr); 1111 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1112 1113 /* 1114 * arp_fillheader() may fail due to lack of support inside encap request 1115 * routing. This is not necessary an error, AF_ARP can/should be handled 1116 * by if_output(). 1117 */ 1118 if (error != 0 && error != EAFNOSUPPORT) { 1119 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1120 if_name(ifp), error); 1121 goto drop; 1122 } 1123 1124 ro.ro_prepend = linkhdr; 1125 ro.ro_plen = linkhdrsize; 1126 ro.ro_flags = 0; 1127 1128 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1129 (*ifp->if_output)(ifp, m, &sa, &ro); 1130 ARPSTAT_INC(txreplies); 1131 return; 1132 1133 drop: 1134 m_freem(m); 1135 } 1136 #endif 1137 1138 static struct mbuf * 1139 arp_grab_holdchain(struct llentry *la) 1140 { 1141 struct mbuf *chain; 1142 1143 LLE_WLOCK_ASSERT(la); 1144 1145 chain = la->la_hold; 1146 la->la_hold = NULL; 1147 la->la_numheld = 0; 1148 1149 return (chain); 1150 } 1151 1152 static void 1153 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain) 1154 { 1155 struct mbuf *m_hold, *m_hold_next; 1156 struct sockaddr_in sin; 1157 1158 NET_EPOCH_ASSERT(); 1159 1160 struct route ro = { 1161 .ro_prepend = la->r_linkdata, 1162 .ro_plen = la->r_hdrlen, 1163 }; 1164 1165 lltable_fill_sa_entry(la, (struct sockaddr *)&sin); 1166 1167 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) { 1168 m_hold_next = m_hold->m_nextpkt; 1169 m_hold->m_nextpkt = NULL; 1170 /* Avoid confusing lower layers. */ 1171 m_clrprotoflags(m_hold); 1172 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro); 1173 } 1174 } 1175 1176 /* 1177 * Checks received arp data against existing @la. 1178 * Updates lle state/performs notification if necessary. 1179 */ 1180 static void 1181 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1182 int bridged, struct llentry *la) 1183 { 1184 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1185 size_t linkhdrsize; 1186 int lladdr_off; 1187 char addrbuf[INET_ADDRSTRLEN]; 1188 1189 LLE_WLOCK_ASSERT(la); 1190 1191 /* the following is not an error when doing bridging */ 1192 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1193 if (log_arp_wrong_iface) 1194 ARP_LOG(LOG_WARNING, "%s is on %s " 1195 "but got reply from %*D on %s\n", 1196 inet_ntoa_r(isaddr, addrbuf), 1197 la->lle_tbl->llt_ifp->if_xname, 1198 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1199 ifp->if_xname); 1200 LLE_WUNLOCK(la); 1201 return; 1202 } 1203 if ((la->la_flags & LLE_VALID) && 1204 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1205 if (la->la_flags & LLE_STATIC) { 1206 LLE_WUNLOCK(la); 1207 if (log_arp_permanent_modify) 1208 ARP_LOG(LOG_ERR, 1209 "%*D attempts to modify " 1210 "permanent entry for %s on %s\n", 1211 ifp->if_addrlen, 1212 (u_char *)ar_sha(ah), ":", 1213 inet_ntoa_r(isaddr, addrbuf), 1214 ifp->if_xname); 1215 return; 1216 } 1217 if (log_arp_movements) { 1218 ARP_LOG(LOG_INFO, "%s moved from %*D " 1219 "to %*D on %s\n", 1220 inet_ntoa_r(isaddr, addrbuf), 1221 ifp->if_addrlen, 1222 (u_char *)la->ll_addr, ":", 1223 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1224 ifp->if_xname); 1225 } 1226 } 1227 1228 /* Calculate full link prepend to use in lle */ 1229 linkhdrsize = sizeof(linkhdr); 1230 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1231 &linkhdrsize, &lladdr_off) != 0) { 1232 LLE_WUNLOCK(la); 1233 return; 1234 } 1235 1236 /* Check if something has changed */ 1237 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1238 (la->la_flags & LLE_VALID) == 0) { 1239 /* Try to perform LLE update */ 1240 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1241 lladdr_off) == 0) { 1242 LLE_WUNLOCK(la); 1243 return; 1244 } 1245 1246 /* Clear fast path feedback request if set */ 1247 llentry_mark_used(la); 1248 } 1249 1250 arp_mark_lle_reachable(la); 1251 1252 /* 1253 * The packets are all freed within the call to the output 1254 * routine. 1255 * 1256 * NB: The lock MUST be released before the call to the 1257 * output routine. 1258 */ 1259 if (la->la_hold != NULL) { 1260 struct mbuf *chain; 1261 1262 chain = arp_grab_holdchain(la); 1263 LLE_WUNLOCK(la); 1264 arp_flush_holdchain(ifp, la, chain); 1265 } else 1266 LLE_WUNLOCK(la); 1267 } 1268 1269 static void 1270 arp_mark_lle_reachable(struct llentry *la) 1271 { 1272 int canceled, wtime; 1273 1274 LLE_WLOCK_ASSERT(la); 1275 1276 la->ln_state = ARP_LLINFO_REACHABLE; 1277 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1278 1279 if (!(la->la_flags & LLE_STATIC)) { 1280 LLE_ADDREF(la); 1281 la->la_expire = time_uptime + V_arpt_keep; 1282 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1283 if (wtime < 0) 1284 wtime = V_arpt_keep; 1285 canceled = callout_reset(&la->lle_timer, 1286 hz * wtime, arptimer, la); 1287 if (canceled) 1288 LLE_REMREF(la); 1289 } 1290 la->la_asked = 0; 1291 la->la_preempt = V_arp_maxtries; 1292 } 1293 1294 /* 1295 * Add permanent link-layer record for given interface address. 1296 */ 1297 static __noinline void 1298 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1299 { 1300 struct llentry *lle, *lle_tmp; 1301 1302 /* 1303 * Interface address LLE record is considered static 1304 * because kernel code relies on LLE_STATIC flag to check 1305 * if these entries can be rewriten by arp updates. 1306 */ 1307 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1308 if (lle == NULL) { 1309 log(LOG_INFO, "arp_ifinit: cannot create arp " 1310 "entry for interface address\n"); 1311 return; 1312 } 1313 1314 IF_AFDATA_WLOCK(ifp); 1315 LLE_WLOCK(lle); 1316 /* Unlink any entry if exists */ 1317 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1318 if (lle_tmp != NULL) 1319 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1320 1321 lltable_link_entry(LLTABLE(ifp), lle); 1322 IF_AFDATA_WUNLOCK(ifp); 1323 1324 if (lle_tmp != NULL) 1325 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1326 1327 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1328 LLE_WUNLOCK(lle); 1329 if (lle_tmp != NULL) 1330 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1331 } 1332 1333 /* 1334 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1335 * of valid values. 1336 */ 1337 static int 1338 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1339 { 1340 int error; 1341 int rexmit_count = *(int *)arg1; 1342 1343 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1344 1345 /* Enforce limits on any new value that may have been set. */ 1346 if (!error && req->newptr) { 1347 /* A new value was set. */ 1348 if (rexmit_count < 0) { 1349 rexmit_count = 0; 1350 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1351 rexmit_count = MAX_GARP_RETRANSMITS; 1352 } 1353 *(int *)arg1 = rexmit_count; 1354 } 1355 1356 return (error); 1357 } 1358 1359 /* 1360 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1361 * retransmit it again. A pending callout owns a reference to the ifa. 1362 */ 1363 static void 1364 garp_rexmit(void *arg) 1365 { 1366 struct in_ifaddr *ia = arg; 1367 1368 if (callout_pending(&ia->ia_garp_timer) || 1369 !callout_active(&ia->ia_garp_timer)) { 1370 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1371 ifa_free(&ia->ia_ifa); 1372 return; 1373 } 1374 1375 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1376 1377 /* 1378 * Drop lock while the ARP request is generated. 1379 */ 1380 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1381 1382 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1383 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1384 1385 /* 1386 * Increment the count of retransmissions. If the count has reached the 1387 * maximum value, stop sending the GARP packets. Otherwise, schedule 1388 * the callout to retransmit another GARP packet. 1389 */ 1390 ++ia->ia_garp_count; 1391 if (ia->ia_garp_count >= garp_rexmit_count) { 1392 ifa_free(&ia->ia_ifa); 1393 } else { 1394 int rescheduled; 1395 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1396 rescheduled = callout_reset(&ia->ia_garp_timer, 1397 (1 << ia->ia_garp_count) * hz, 1398 garp_rexmit, ia); 1399 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1400 if (rescheduled) { 1401 ifa_free(&ia->ia_ifa); 1402 } 1403 } 1404 1405 CURVNET_RESTORE(); 1406 } 1407 1408 /* 1409 * Start the GARP retransmit timer. 1410 * 1411 * A single GARP is always transmitted when an IPv4 address is added 1412 * to an interface and that is usually sufficient. However, in some 1413 * circumstances, such as when a shared address is passed between 1414 * cluster nodes, this single GARP may occasionally be dropped or 1415 * lost. This can lead to neighbors on the network link working with a 1416 * stale ARP cache and sending packets destined for that address to 1417 * the node that previously owned the address, which may not respond. 1418 * 1419 * To avoid this situation, GARP retransmits can be enabled by setting 1420 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1421 * than zero. The setting represents the maximum number of 1422 * retransmissions. The interval between retransmissions is calculated 1423 * using an exponential backoff algorithm, doubling each time, so the 1424 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1425 */ 1426 static void 1427 garp_timer_start(struct ifaddr *ifa) 1428 { 1429 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1430 1431 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1432 ia->ia_garp_count = 0; 1433 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1434 garp_rexmit, ia) == 0) { 1435 ifa_ref(ifa); 1436 } 1437 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1438 } 1439 1440 void 1441 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1442 { 1443 struct epoch_tracker et; 1444 const struct sockaddr_in *dst_in; 1445 const struct sockaddr *dst; 1446 1447 if (ifa->ifa_carp != NULL) 1448 return; 1449 1450 dst = ifa->ifa_addr; 1451 dst_in = (const struct sockaddr_in *)dst; 1452 1453 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1454 return; 1455 NET_EPOCH_ENTER(et); 1456 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1457 NET_EPOCH_EXIT(et); 1458 if (garp_rexmit_count > 0) { 1459 garp_timer_start(ifa); 1460 } 1461 1462 arp_add_ifa_lle(ifp, dst); 1463 } 1464 1465 void 1466 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1467 { 1468 1469 if (ntohl(addr.s_addr) != INADDR_ANY) 1470 arprequest(ifp, &addr, &addr, enaddr); 1471 } 1472 1473 /* 1474 * Sends gratuitous ARPs for each ifaddr to notify other 1475 * nodes about the address change. 1476 */ 1477 static __noinline void 1478 arp_handle_ifllchange(struct ifnet *ifp) 1479 { 1480 struct ifaddr *ifa; 1481 1482 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1483 if (ifa->ifa_addr->sa_family == AF_INET) 1484 arp_ifinit(ifp, ifa); 1485 } 1486 } 1487 1488 /* 1489 * A handler for interface link layer address change event. 1490 */ 1491 static void 1492 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1493 { 1494 /* if_bridge can update its lladdr during if_vmove(), after we've done 1495 * if_detach_internal()/dom_ifdetach(). */ 1496 if (ifp->if_afdata[AF_INET] == NULL) 1497 return; 1498 1499 lltable_update_ifaddr(LLTABLE(ifp)); 1500 1501 if ((ifp->if_flags & IFF_UP) != 0) 1502 arp_handle_ifllchange(ifp); 1503 } 1504 1505 static void 1506 vnet_arp_init(void) 1507 { 1508 1509 if (IS_DEFAULT_VNET(curvnet)) { 1510 netisr_register(&arp_nh); 1511 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1512 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1513 } 1514 #ifdef VIMAGE 1515 else 1516 netisr_register_vnet(&arp_nh); 1517 #endif 1518 } 1519 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1520 vnet_arp_init, 0); 1521 1522 #ifdef VIMAGE 1523 /* 1524 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1525 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1526 */ 1527 static void 1528 vnet_arp_destroy(__unused void *arg) 1529 { 1530 1531 netisr_unregister_vnet(&arp_nh); 1532 } 1533 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1534 vnet_arp_destroy, NULL); 1535 #endif 1536