1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 32 */ 33 34 /* 35 * Ethernet address resolution protocol. 36 * TODO: 37 * add "inuse/lock" bit (or ref. count) along with valid bit 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "opt_inet.h" 44 45 #include <sys/param.h> 46 #include <sys/eventhandler.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/queue.h> 50 #include <sys/sysctl.h> 51 #include <sys/systm.h> 52 #include <sys/mbuf.h> 53 #include <sys/malloc.h> 54 #include <sys/proc.h> 55 #include <sys/rmlock.h> 56 #include <sys/socket.h> 57 #include <sys/syslog.h> 58 59 #include <net/if.h> 60 #include <net/if_var.h> 61 #include <net/if_dl.h> 62 #include <net/if_types.h> 63 #include <net/netisr.h> 64 #include <net/ethernet.h> 65 #include <net/route.h> 66 #include <net/route/nhop.h> 67 #include <net/vnet.h> 68 69 #include <netinet/in.h> 70 #include <netinet/in_fib.h> 71 #include <netinet/in_var.h> 72 #include <net/if_llatbl.h> 73 #include <netinet/if_ether.h> 74 #ifdef INET 75 #include <netinet/ip_carp.h> 76 #endif 77 78 #include <security/mac/mac_framework.h> 79 80 #define SIN(s) ((const struct sockaddr_in *)(s)) 81 82 static struct timeval arp_lastlog; 83 static int arp_curpps; 84 static int arp_maxpps = 1; 85 86 /* Simple ARP state machine */ 87 enum arp_llinfo_state { 88 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 89 ARP_LLINFO_REACHABLE, /* LLE is valid */ 90 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 91 ARP_LLINFO_DELETED, /* LLE is deleted */ 92 }; 93 94 SYSCTL_DECL(_net_link_ether); 95 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, 96 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 97 ""); 98 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, 99 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 100 ""); 101 102 /* timer values */ 103 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 104 * minutes */ 105 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 106 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 107 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 108 * 20 seconds */ 109 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 110 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 111 VNET_PCPUSTAT_SYSINIT(arpstat); 112 113 #ifdef VIMAGE 114 VNET_PCPUSTAT_SYSUNINIT(arpstat); 115 #endif /* VIMAGE */ 116 117 VNET_DEFINE_STATIC(int, arp_maxhold) = 16; 118 119 #define V_arpt_keep VNET(arpt_keep) 120 #define V_arpt_down VNET(arpt_down) 121 #define V_arpt_rexmit VNET(arpt_rexmit) 122 #define V_arp_maxtries VNET(arp_maxtries) 123 #define V_arp_proxyall VNET(arp_proxyall) 124 #define V_arp_maxhold VNET(arp_maxhold) 125 126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 127 &VNET_NAME(arpt_keep), 0, 128 "ARP entry lifetime in seconds"); 129 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 130 &VNET_NAME(arp_maxtries), 0, 131 "ARP resolution attempts before returning error"); 132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 133 &VNET_NAME(arp_proxyall), 0, 134 "Enable proxy ARP for all suitable requests"); 135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 136 &VNET_NAME(arpt_down), 0, 137 "Incomplete ARP entry lifetime in seconds"); 138 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 139 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 140 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 141 &VNET_NAME(arp_maxhold), 0, 142 "Number of packets to hold per ARP entry"); 143 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 144 CTLFLAG_RW, &arp_maxpps, 0, 145 "Maximum number of remotely triggered ARP messages that can be " 146 "logged per second"); 147 148 /* 149 * Due to the exponential backoff algorithm used for the interval between GARP 150 * retransmissions, the maximum number of retransmissions is limited for 151 * sanity. This limit corresponds to a maximum interval between retransmissions 152 * of 2^16 seconds ~= 18 hours. 153 * 154 * Making this limit more dynamic is more complicated than worthwhile, 155 * especially since sending out GARPs spaced days apart would be of little 156 * use. A maximum dynamic limit would look something like: 157 * 158 * const int max = fls(INT_MAX / hz) - 1; 159 */ 160 #define MAX_GARP_RETRANSMITS 16 161 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 162 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 163 164 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 165 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 166 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 167 "Number of times to retransmit GARP packets;" 168 " 0 to disable, maximum of 16"); 169 170 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 171 #define V_arp_log_level VNET(arp_log_level) 172 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 173 &VNET_NAME(arp_log_level), 0, 174 "Minimum log(9) level for recording rate limited arp log messages. " 175 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 176 #define ARP_LOG(pri, ...) do { \ 177 if ((pri) <= V_arp_log_level && \ 178 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 179 log((pri), "arp: " __VA_ARGS__); \ 180 } while (0) 181 182 static void arpintr(struct mbuf *); 183 static void arptimer(void *); 184 #ifdef INET 185 static void in_arpinput(struct mbuf *); 186 #endif 187 188 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 189 struct ifnet *ifp, int bridged, struct llentry *la); 190 static void arp_mark_lle_reachable(struct llentry *la); 191 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 192 193 static eventhandler_tag iflladdr_tag; 194 195 static const struct netisr_handler arp_nh = { 196 .nh_name = "arp", 197 .nh_handler = arpintr, 198 .nh_proto = NETISR_ARP, 199 .nh_policy = NETISR_POLICY_SOURCE, 200 }; 201 202 /* 203 * Timeout routine. Age arp_tab entries periodically. 204 */ 205 static void 206 arptimer(void *arg) 207 { 208 struct llentry *lle = (struct llentry *)arg; 209 struct ifnet *ifp; 210 211 if (lle->la_flags & LLE_STATIC) { 212 return; 213 } 214 LLE_WLOCK(lle); 215 if (callout_pending(&lle->lle_timer)) { 216 /* 217 * Here we are a bit odd here in the treatment of 218 * active/pending. If the pending bit is set, it got 219 * rescheduled before I ran. The active 220 * bit we ignore, since if it was stopped 221 * in ll_tablefree() and was currently running 222 * it would have return 0 so the code would 223 * not have deleted it since the callout could 224 * not be stopped so we want to go through 225 * with the delete here now. If the callout 226 * was restarted, the pending bit will be back on and 227 * we just want to bail since the callout_reset would 228 * return 1 and our reference would have been removed 229 * by arpresolve() below. 230 */ 231 LLE_WUNLOCK(lle); 232 return; 233 } 234 ifp = lle->lle_tbl->llt_ifp; 235 CURVNET_SET(ifp->if_vnet); 236 237 switch (lle->ln_state) { 238 case ARP_LLINFO_REACHABLE: 239 240 /* 241 * Expiration time is approaching. 242 * Request usage feedback from the datapath. 243 * Change state and re-schedule ourselves. 244 */ 245 llentry_request_feedback(lle); 246 lle->ln_state = ARP_LLINFO_VERIFY; 247 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 248 LLE_WUNLOCK(lle); 249 CURVNET_RESTORE(); 250 return; 251 case ARP_LLINFO_VERIFY: 252 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) { 253 /* Entry was used, issue refresh request */ 254 struct epoch_tracker et; 255 struct in_addr dst; 256 257 dst = lle->r_l3addr.addr4; 258 lle->la_preempt--; 259 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 260 LLE_WUNLOCK(lle); 261 NET_EPOCH_ENTER(et); 262 arprequest(ifp, NULL, &dst, NULL); 263 NET_EPOCH_EXIT(et); 264 CURVNET_RESTORE(); 265 return; 266 } 267 /* Nothing happened. Reschedule if not too late */ 268 if (lle->la_expire > time_uptime) { 269 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 270 LLE_WUNLOCK(lle); 271 CURVNET_RESTORE(); 272 return; 273 } 274 break; 275 case ARP_LLINFO_INCOMPLETE: 276 case ARP_LLINFO_DELETED: 277 break; 278 } 279 280 if ((lle->la_flags & LLE_DELETED) == 0) { 281 int evt; 282 283 if (lle->la_flags & LLE_VALID) 284 evt = LLENTRY_EXPIRED; 285 else 286 evt = LLENTRY_TIMEDOUT; 287 EVENTHANDLER_INVOKE(lle_event, lle, evt); 288 } 289 290 callout_stop(&lle->lle_timer); 291 292 /* XXX: LOR avoidance. We still have ref on lle. */ 293 LLE_WUNLOCK(lle); 294 IF_AFDATA_LOCK(ifp); 295 LLE_WLOCK(lle); 296 297 /* Guard against race with other llentry_free(). */ 298 if (lle->la_flags & LLE_LINKED) { 299 LLE_REMREF(lle); 300 lltable_unlink_entry(lle->lle_tbl, lle); 301 } 302 IF_AFDATA_UNLOCK(ifp); 303 304 size_t pkts_dropped = llentry_free(lle); 305 306 ARPSTAT_ADD(dropped, pkts_dropped); 307 ARPSTAT_INC(timeouts); 308 309 CURVNET_RESTORE(); 310 } 311 312 /* 313 * Stores link-layer header for @ifp in format suitable for if_output() 314 * into buffer @buf. Resulting header length is stored in @bufsize. 315 * 316 * Returns 0 on success. 317 */ 318 static int 319 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 320 size_t *bufsize) 321 { 322 struct if_encap_req ereq; 323 int error; 324 325 bzero(buf, *bufsize); 326 bzero(&ereq, sizeof(ereq)); 327 ereq.buf = buf; 328 ereq.bufsize = *bufsize; 329 ereq.rtype = IFENCAP_LL; 330 ereq.family = AF_ARP; 331 ereq.lladdr = ar_tha(ah); 332 ereq.hdata = (u_char *)ah; 333 if (bcast) 334 ereq.flags = IFENCAP_FLAG_BROADCAST; 335 error = ifp->if_requestencap(ifp, &ereq); 336 if (error == 0) 337 *bufsize = ereq.bufsize; 338 339 return (error); 340 } 341 342 /* 343 * Broadcast an ARP request. Caller specifies: 344 * - arp header source ip address 345 * - arp header target ip address 346 * - arp header source ethernet address 347 */ 348 static int 349 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 350 const struct in_addr *tip, u_char *enaddr) 351 { 352 struct mbuf *m; 353 struct arphdr *ah; 354 struct sockaddr sa; 355 u_char *carpaddr = NULL; 356 uint8_t linkhdr[LLE_MAX_LINKHDR]; 357 size_t linkhdrsize; 358 struct route ro; 359 int error; 360 361 NET_EPOCH_ASSERT(); 362 363 if (sip == NULL) { 364 /* 365 * The caller did not supply a source address, try to find 366 * a compatible one among those assigned to this interface. 367 */ 368 struct ifaddr *ifa; 369 370 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 371 if (ifa->ifa_addr->sa_family != AF_INET) 372 continue; 373 374 if (ifa->ifa_carp) { 375 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 376 continue; 377 sip = &IA_SIN(ifa)->sin_addr; 378 } else { 379 carpaddr = NULL; 380 sip = &IA_SIN(ifa)->sin_addr; 381 } 382 383 if (0 == ((sip->s_addr ^ tip->s_addr) & 384 IA_MASKSIN(ifa)->sin_addr.s_addr)) 385 break; /* found it. */ 386 } 387 if (sip == NULL) { 388 printf("%s: cannot find matching address\n", __func__); 389 return (EADDRNOTAVAIL); 390 } 391 } 392 if (enaddr == NULL) 393 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 394 395 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 396 return (ENOMEM); 397 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 398 2 * ifp->if_addrlen; 399 m->m_pkthdr.len = m->m_len; 400 M_ALIGN(m, m->m_len); 401 ah = mtod(m, struct arphdr *); 402 bzero((caddr_t)ah, m->m_len); 403 #ifdef MAC 404 mac_netinet_arp_send(ifp, m); 405 #endif 406 ah->ar_pro = htons(ETHERTYPE_IP); 407 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 408 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 409 ah->ar_op = htons(ARPOP_REQUEST); 410 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 411 bcopy(sip, ar_spa(ah), ah->ar_pln); 412 bcopy(tip, ar_tpa(ah), ah->ar_pln); 413 sa.sa_family = AF_ARP; 414 sa.sa_len = 2; 415 416 /* Calculate link header for sending frame */ 417 bzero(&ro, sizeof(ro)); 418 linkhdrsize = sizeof(linkhdr); 419 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 420 if (error != 0 && error != EAFNOSUPPORT) { 421 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 rm_priotracker in_ifa_tracker; 782 struct arphdr *ah; 783 struct ifnet *ifp = m->m_pkthdr.rcvif; 784 struct llentry *la = NULL, *la_tmp; 785 struct ifaddr *ifa; 786 struct in_ifaddr *ia; 787 struct sockaddr sa; 788 struct in_addr isaddr, itaddr, myaddr; 789 u_int8_t *enaddr = NULL; 790 int op; 791 int bridged = 0, is_bridge = 0; 792 int carped; 793 struct sockaddr_in sin; 794 struct sockaddr *dst; 795 struct nhop_object *nh; 796 uint8_t linkhdr[LLE_MAX_LINKHDR]; 797 struct route ro; 798 size_t linkhdrsize; 799 int lladdr_off; 800 int error; 801 char addrbuf[INET_ADDRSTRLEN]; 802 803 NET_EPOCH_ASSERT(); 804 805 sin.sin_len = sizeof(struct sockaddr_in); 806 sin.sin_family = AF_INET; 807 sin.sin_addr.s_addr = 0; 808 809 if (ifp->if_bridge) 810 bridged = 1; 811 if (ifp->if_type == IFT_BRIDGE) 812 is_bridge = 1; 813 814 /* 815 * We already have checked that mbuf contains enough contiguous data 816 * to hold entire arp message according to the arp header. 817 */ 818 ah = mtod(m, struct arphdr *); 819 820 /* 821 * ARP is only for IPv4 so we can reject packets with 822 * a protocol length not equal to an IPv4 address. 823 */ 824 if (ah->ar_pln != sizeof(struct in_addr)) { 825 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 826 sizeof(struct in_addr)); 827 goto drop; 828 } 829 830 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 831 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 832 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 833 goto drop; 834 } 835 836 op = ntohs(ah->ar_op); 837 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 838 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 839 840 if (op == ARPOP_REPLY) 841 ARPSTAT_INC(rxreplies); 842 843 /* 844 * For a bridge, we want to check the address irrespective 845 * of the receive interface. (This will change slightly 846 * when we have clusters of interfaces). 847 */ 848 IN_IFADDR_RLOCK(&in_ifa_tracker); 849 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 850 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 851 ia->ia_ifp == ifp) && 852 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 853 (ia->ia_ifa.ifa_carp == NULL || 854 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 855 ifa_ref(&ia->ia_ifa); 856 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 857 goto match; 858 } 859 } 860 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 861 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 862 ia->ia_ifp == ifp) && 863 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 864 ifa_ref(&ia->ia_ifa); 865 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 866 goto match; 867 } 868 869 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 870 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 871 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 872 addr == ia->ia_addr.sin_addr.s_addr) 873 /* 874 * Check the case when bridge shares its MAC address with 875 * some of its children, so packets are claimed by bridge 876 * itself (bridge_input() does it first), but they are really 877 * meant to be destined to the bridge member. 878 */ 879 if (is_bridge) { 880 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 881 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 882 ifa_ref(&ia->ia_ifa); 883 ifp = ia->ia_ifp; 884 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 885 goto match; 886 } 887 } 888 } 889 #undef BDG_MEMBER_MATCHES_ARP 890 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 891 892 /* 893 * No match, use the first inet address on the receive interface 894 * as a dummy address for the rest of the function. 895 */ 896 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 897 if (ifa->ifa_addr->sa_family == AF_INET && 898 (ifa->ifa_carp == NULL || 899 (*carp_iamatch_p)(ifa, &enaddr))) { 900 ia = ifatoia(ifa); 901 ifa_ref(ifa); 902 goto match; 903 } 904 905 /* 906 * If bridging, fall back to using any inet address. 907 */ 908 IN_IFADDR_RLOCK(&in_ifa_tracker); 909 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 910 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 911 goto drop; 912 } 913 ifa_ref(&ia->ia_ifa); 914 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 915 match: 916 if (!enaddr) 917 enaddr = (u_int8_t *)IF_LLADDR(ifp); 918 carped = (ia->ia_ifa.ifa_carp != NULL); 919 myaddr = ia->ia_addr.sin_addr; 920 ifa_free(&ia->ia_ifa); 921 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 922 goto drop; /* it's from me, ignore it. */ 923 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 924 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 925 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 926 goto drop; 927 } 928 929 if (ifp->if_addrlen != ah->ar_hln) { 930 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 931 "i/f %d (ignored)\n", ifp->if_addrlen, 932 (u_char *) ar_sha(ah), ":", ah->ar_hln, 933 ifp->if_addrlen); 934 goto drop; 935 } 936 937 /* 938 * Warn if another host is using the same IP address, but only if the 939 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 940 * case we suppress the warning to avoid false positive complaints of 941 * potential misconfiguration. 942 */ 943 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 944 myaddr.s_addr != 0) { 945 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 946 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 947 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 948 itaddr = myaddr; 949 ARPSTAT_INC(dupips); 950 goto reply; 951 } 952 if (ifp->if_flags & IFF_STATICARP) 953 goto reply; 954 955 bzero(&sin, sizeof(sin)); 956 sin.sin_len = sizeof(struct sockaddr_in); 957 sin.sin_family = AF_INET; 958 sin.sin_addr = isaddr; 959 dst = (struct sockaddr *)&sin; 960 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 961 if (la != NULL) 962 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 963 else if (itaddr.s_addr == myaddr.s_addr) { 964 /* 965 * Request/reply to our address, but no lle exists yet. 966 * Calculate full link prepend to use in lle. 967 */ 968 linkhdrsize = sizeof(linkhdr); 969 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 970 &linkhdrsize, &lladdr_off) != 0) 971 goto reply; 972 973 /* Allocate new entry */ 974 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 975 if (la == NULL) { 976 /* 977 * lle creation may fail if source address belongs 978 * to non-directly connected subnet. However, we 979 * will try to answer the request instead of dropping 980 * frame. 981 */ 982 goto reply; 983 } 984 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 985 lladdr_off); 986 987 IF_AFDATA_WLOCK(ifp); 988 LLE_WLOCK(la); 989 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 990 991 /* 992 * Check if lle still does not exists. 993 * If it does, that means that we either 994 * 1) have configured it explicitly, via 995 * 1a) 'arp -s' static entry or 996 * 1b) interface address static record 997 * or 998 * 2) it was the result of sending first packet to-host 999 * or 1000 * 3) it was another arp reply packet we handled in 1001 * different thread. 1002 * 1003 * In all cases except 3) we definitely need to prefer 1004 * existing lle. For the sake of simplicity, prefer any 1005 * existing lle over newly-create one. 1006 */ 1007 if (la_tmp == NULL) 1008 lltable_link_entry(LLTABLE(ifp), la); 1009 IF_AFDATA_WUNLOCK(ifp); 1010 1011 if (la_tmp == NULL) { 1012 arp_mark_lle_reachable(la); 1013 LLE_WUNLOCK(la); 1014 } else { 1015 /* Free newly-create entry and handle packet */ 1016 lltable_free_entry(LLTABLE(ifp), la); 1017 la = la_tmp; 1018 la_tmp = NULL; 1019 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1020 /* arp_check_update_lle() returns @la unlocked */ 1021 } 1022 la = NULL; 1023 } 1024 reply: 1025 if (op != ARPOP_REQUEST) 1026 goto drop; 1027 ARPSTAT_INC(rxrequests); 1028 1029 if (itaddr.s_addr == myaddr.s_addr) { 1030 /* Shortcut.. the receiving interface is the target. */ 1031 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1032 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1033 } else { 1034 /* 1035 * Destination address is not ours. Check if 1036 * proxyarp entry exists or proxyarp is turned on globally. 1037 */ 1038 struct llentry *lle; 1039 1040 sin.sin_addr = itaddr; 1041 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1042 1043 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1044 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1045 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1046 LLE_RUNLOCK(lle); 1047 } else { 1048 if (lle != NULL) 1049 LLE_RUNLOCK(lle); 1050 1051 if (!V_arp_proxyall) 1052 goto drop; 1053 1054 NET_EPOCH_ASSERT(); 1055 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0); 1056 if (nh == NULL) 1057 goto drop; 1058 1059 /* 1060 * Don't send proxies for nodes on the same interface 1061 * as this one came out of, or we'll get into a fight 1062 * over who claims what Ether address. 1063 */ 1064 if (nh->nh_ifp == ifp) 1065 goto drop; 1066 1067 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1068 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1069 1070 /* 1071 * Also check that the node which sent the ARP packet 1072 * is on the interface we expect it to be on. This 1073 * avoids ARP chaos if an interface is connected to the 1074 * wrong network. 1075 */ 1076 1077 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0); 1078 if (nh == NULL) 1079 goto drop; 1080 if (nh->nh_ifp != ifp) { 1081 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1082 " from %s via %s\n", 1083 inet_ntoa_r(isaddr, addrbuf), 1084 ifp->if_xname); 1085 goto drop; 1086 } 1087 1088 #ifdef DEBUG_PROXY 1089 printf("arp: proxying for %s\n", 1090 inet_ntoa_r(itaddr, addrbuf)); 1091 #endif 1092 } 1093 } 1094 1095 if (itaddr.s_addr == myaddr.s_addr && 1096 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1097 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1098 #ifdef DEBUG_LINKLOCAL 1099 printf("arp: sending reply for link-local addr %s\n", 1100 inet_ntoa_r(itaddr, addrbuf)); 1101 #endif 1102 m->m_flags |= M_BCAST; 1103 m->m_flags &= ~M_MCAST; 1104 } else { 1105 /* default behaviour; never reply by broadcast. */ 1106 m->m_flags &= ~(M_BCAST|M_MCAST); 1107 } 1108 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1109 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1110 ah->ar_op = htons(ARPOP_REPLY); 1111 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1112 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1113 m->m_pkthdr.len = m->m_len; 1114 m->m_pkthdr.rcvif = NULL; 1115 sa.sa_family = AF_ARP; 1116 sa.sa_len = 2; 1117 1118 /* Calculate link header for sending frame */ 1119 bzero(&ro, sizeof(ro)); 1120 linkhdrsize = sizeof(linkhdr); 1121 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1122 1123 /* 1124 * arp_fillheader() may fail due to lack of support inside encap request 1125 * routing. This is not necessary an error, AF_ARP can/should be handled 1126 * by if_output(). 1127 */ 1128 if (error != 0 && error != EAFNOSUPPORT) { 1129 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1130 if_name(ifp), error); 1131 return; 1132 } 1133 1134 ro.ro_prepend = linkhdr; 1135 ro.ro_plen = linkhdrsize; 1136 ro.ro_flags = 0; 1137 1138 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1139 (*ifp->if_output)(ifp, m, &sa, &ro); 1140 ARPSTAT_INC(txreplies); 1141 return; 1142 1143 drop: 1144 m_freem(m); 1145 } 1146 #endif 1147 1148 static struct mbuf * 1149 arp_grab_holdchain(struct llentry *la) 1150 { 1151 struct mbuf *chain; 1152 1153 LLE_WLOCK_ASSERT(la); 1154 1155 chain = la->la_hold; 1156 la->la_hold = NULL; 1157 la->la_numheld = 0; 1158 1159 return (chain); 1160 } 1161 1162 static void 1163 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain) 1164 { 1165 struct mbuf *m_hold, *m_hold_next; 1166 struct sockaddr_in sin; 1167 1168 NET_EPOCH_ASSERT(); 1169 1170 struct route ro = { 1171 .ro_prepend = la->r_linkdata, 1172 .ro_plen = la->r_hdrlen, 1173 }; 1174 1175 lltable_fill_sa_entry(la, (struct sockaddr *)&sin); 1176 1177 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) { 1178 m_hold_next = m_hold->m_nextpkt; 1179 m_hold->m_nextpkt = NULL; 1180 /* Avoid confusing lower layers. */ 1181 m_clrprotoflags(m_hold); 1182 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro); 1183 } 1184 } 1185 1186 /* 1187 * Checks received arp data against existing @la. 1188 * Updates lle state/performs notification if necessary. 1189 */ 1190 static void 1191 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1192 int bridged, struct llentry *la) 1193 { 1194 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1195 size_t linkhdrsize; 1196 int lladdr_off; 1197 char addrbuf[INET_ADDRSTRLEN]; 1198 1199 LLE_WLOCK_ASSERT(la); 1200 1201 /* the following is not an error when doing bridging */ 1202 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1203 if (log_arp_wrong_iface) 1204 ARP_LOG(LOG_WARNING, "%s is on %s " 1205 "but got reply from %*D on %s\n", 1206 inet_ntoa_r(isaddr, addrbuf), 1207 la->lle_tbl->llt_ifp->if_xname, 1208 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1209 ifp->if_xname); 1210 LLE_WUNLOCK(la); 1211 return; 1212 } 1213 if ((la->la_flags & LLE_VALID) && 1214 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1215 if (la->la_flags & LLE_STATIC) { 1216 LLE_WUNLOCK(la); 1217 if (log_arp_permanent_modify) 1218 ARP_LOG(LOG_ERR, 1219 "%*D attempts to modify " 1220 "permanent entry for %s on %s\n", 1221 ifp->if_addrlen, 1222 (u_char *)ar_sha(ah), ":", 1223 inet_ntoa_r(isaddr, addrbuf), 1224 ifp->if_xname); 1225 return; 1226 } 1227 if (log_arp_movements) { 1228 ARP_LOG(LOG_INFO, "%s moved from %*D " 1229 "to %*D on %s\n", 1230 inet_ntoa_r(isaddr, addrbuf), 1231 ifp->if_addrlen, 1232 (u_char *)la->ll_addr, ":", 1233 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1234 ifp->if_xname); 1235 } 1236 } 1237 1238 /* Calculate full link prepend to use in lle */ 1239 linkhdrsize = sizeof(linkhdr); 1240 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1241 &linkhdrsize, &lladdr_off) != 0) 1242 return; 1243 1244 /* Check if something has changed */ 1245 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1246 (la->la_flags & LLE_VALID) == 0) { 1247 /* Try to perform LLE update */ 1248 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1249 lladdr_off) == 0) 1250 return; 1251 1252 /* Clear fast path feedback request if set */ 1253 llentry_mark_used(la); 1254 } 1255 1256 arp_mark_lle_reachable(la); 1257 1258 /* 1259 * The packets are all freed within the call to the output 1260 * routine. 1261 * 1262 * NB: The lock MUST be released before the call to the 1263 * output routine. 1264 */ 1265 if (la->la_hold != NULL) { 1266 struct mbuf *chain; 1267 1268 chain = arp_grab_holdchain(la); 1269 LLE_WUNLOCK(la); 1270 arp_flush_holdchain(ifp, la, chain); 1271 } else 1272 LLE_WUNLOCK(la); 1273 } 1274 1275 static void 1276 arp_mark_lle_reachable(struct llentry *la) 1277 { 1278 int canceled, wtime; 1279 1280 LLE_WLOCK_ASSERT(la); 1281 1282 la->ln_state = ARP_LLINFO_REACHABLE; 1283 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1284 1285 if (!(la->la_flags & LLE_STATIC)) { 1286 LLE_ADDREF(la); 1287 la->la_expire = time_uptime + V_arpt_keep; 1288 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1289 if (wtime < 0) 1290 wtime = V_arpt_keep; 1291 canceled = callout_reset(&la->lle_timer, 1292 hz * wtime, arptimer, la); 1293 if (canceled) 1294 LLE_REMREF(la); 1295 } 1296 la->la_asked = 0; 1297 la->la_preempt = V_arp_maxtries; 1298 } 1299 1300 /* 1301 * Add permanent link-layer record for given interface address. 1302 */ 1303 static __noinline void 1304 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1305 { 1306 struct llentry *lle, *lle_tmp; 1307 1308 /* 1309 * Interface address LLE record is considered static 1310 * because kernel code relies on LLE_STATIC flag to check 1311 * if these entries can be rewriten by arp updates. 1312 */ 1313 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1314 if (lle == NULL) { 1315 log(LOG_INFO, "arp_ifinit: cannot create arp " 1316 "entry for interface address\n"); 1317 return; 1318 } 1319 1320 IF_AFDATA_WLOCK(ifp); 1321 LLE_WLOCK(lle); 1322 /* Unlink any entry if exists */ 1323 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1324 if (lle_tmp != NULL) 1325 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1326 1327 lltable_link_entry(LLTABLE(ifp), lle); 1328 IF_AFDATA_WUNLOCK(ifp); 1329 1330 if (lle_tmp != NULL) 1331 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1332 1333 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1334 LLE_WUNLOCK(lle); 1335 if (lle_tmp != NULL) 1336 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1337 } 1338 1339 /* 1340 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1341 * of valid values. 1342 */ 1343 static int 1344 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1345 { 1346 int error; 1347 int rexmit_count = *(int *)arg1; 1348 1349 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1350 1351 /* Enforce limits on any new value that may have been set. */ 1352 if (!error && req->newptr) { 1353 /* A new value was set. */ 1354 if (rexmit_count < 0) { 1355 rexmit_count = 0; 1356 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1357 rexmit_count = MAX_GARP_RETRANSMITS; 1358 } 1359 *(int *)arg1 = rexmit_count; 1360 } 1361 1362 return (error); 1363 } 1364 1365 /* 1366 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1367 * retransmit it again. A pending callout owns a reference to the ifa. 1368 */ 1369 static void 1370 garp_rexmit(void *arg) 1371 { 1372 struct in_ifaddr *ia = arg; 1373 1374 if (callout_pending(&ia->ia_garp_timer) || 1375 !callout_active(&ia->ia_garp_timer)) { 1376 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1377 ifa_free(&ia->ia_ifa); 1378 return; 1379 } 1380 1381 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1382 1383 /* 1384 * Drop lock while the ARP request is generated. 1385 */ 1386 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1387 1388 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1389 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1390 1391 /* 1392 * Increment the count of retransmissions. If the count has reached the 1393 * maximum value, stop sending the GARP packets. Otherwise, schedule 1394 * the callout to retransmit another GARP packet. 1395 */ 1396 ++ia->ia_garp_count; 1397 if (ia->ia_garp_count >= garp_rexmit_count) { 1398 ifa_free(&ia->ia_ifa); 1399 } else { 1400 int rescheduled; 1401 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1402 rescheduled = callout_reset(&ia->ia_garp_timer, 1403 (1 << ia->ia_garp_count) * hz, 1404 garp_rexmit, ia); 1405 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1406 if (rescheduled) { 1407 ifa_free(&ia->ia_ifa); 1408 } 1409 } 1410 1411 CURVNET_RESTORE(); 1412 } 1413 1414 /* 1415 * Start the GARP retransmit timer. 1416 * 1417 * A single GARP is always transmitted when an IPv4 address is added 1418 * to an interface and that is usually sufficient. However, in some 1419 * circumstances, such as when a shared address is passed between 1420 * cluster nodes, this single GARP may occasionally be dropped or 1421 * lost. This can lead to neighbors on the network link working with a 1422 * stale ARP cache and sending packets destined for that address to 1423 * the node that previously owned the address, which may not respond. 1424 * 1425 * To avoid this situation, GARP retransmits can be enabled by setting 1426 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1427 * than zero. The setting represents the maximum number of 1428 * retransmissions. The interval between retransmissions is calculated 1429 * using an exponential backoff algorithm, doubling each time, so the 1430 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1431 */ 1432 static void 1433 garp_timer_start(struct ifaddr *ifa) 1434 { 1435 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1436 1437 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1438 ia->ia_garp_count = 0; 1439 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1440 garp_rexmit, ia) == 0) { 1441 ifa_ref(ifa); 1442 } 1443 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1444 } 1445 1446 void 1447 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1448 { 1449 struct epoch_tracker et; 1450 const struct sockaddr_in *dst_in; 1451 const struct sockaddr *dst; 1452 1453 if (ifa->ifa_carp != NULL) 1454 return; 1455 1456 dst = ifa->ifa_addr; 1457 dst_in = (const struct sockaddr_in *)dst; 1458 1459 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1460 return; 1461 NET_EPOCH_ENTER(et); 1462 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1463 NET_EPOCH_EXIT(et); 1464 if (garp_rexmit_count > 0) { 1465 garp_timer_start(ifa); 1466 } 1467 1468 arp_add_ifa_lle(ifp, dst); 1469 } 1470 1471 void 1472 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1473 { 1474 1475 if (ntohl(addr.s_addr) != INADDR_ANY) 1476 arprequest(ifp, &addr, &addr, enaddr); 1477 } 1478 1479 /* 1480 * Sends gratuitous ARPs for each ifaddr to notify other 1481 * nodes about the address change. 1482 */ 1483 static __noinline void 1484 arp_handle_ifllchange(struct ifnet *ifp) 1485 { 1486 struct ifaddr *ifa; 1487 1488 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1489 if (ifa->ifa_addr->sa_family == AF_INET) 1490 arp_ifinit(ifp, ifa); 1491 } 1492 } 1493 1494 /* 1495 * A handler for interface link layer address change event. 1496 */ 1497 static void 1498 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1499 { 1500 /* if_bridge can update its lladdr during if_vmove(), after we've done 1501 * if_detach_internal()/dom_ifdetach(). */ 1502 if (ifp->if_afdata[AF_INET] == NULL) 1503 return; 1504 1505 lltable_update_ifaddr(LLTABLE(ifp)); 1506 1507 if ((ifp->if_flags & IFF_UP) != 0) 1508 arp_handle_ifllchange(ifp); 1509 } 1510 1511 static void 1512 vnet_arp_init(void) 1513 { 1514 1515 if (IS_DEFAULT_VNET(curvnet)) { 1516 netisr_register(&arp_nh); 1517 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1518 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1519 } 1520 #ifdef VIMAGE 1521 else 1522 netisr_register_vnet(&arp_nh); 1523 #endif 1524 } 1525 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1526 vnet_arp_init, 0); 1527 1528 #ifdef VIMAGE 1529 /* 1530 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1531 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1532 */ 1533 static void 1534 vnet_arp_destroy(__unused void *arg) 1535 { 1536 1537 netisr_unregister_vnet(&arp_nh); 1538 } 1539 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1540 vnet_arp_destroy, NULL); 1541 #endif 1542