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