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/vnet.h> 67 68 #include <netinet/in.h> 69 #include <netinet/in_fib.h> 70 #include <netinet/in_var.h> 71 #include <net/if_llatbl.h> 72 #include <netinet/if_ether.h> 73 #ifdef INET 74 #include <netinet/ip_carp.h> 75 #endif 76 77 #include <security/mac/mac_framework.h> 78 79 #define SIN(s) ((const struct sockaddr_in *)(s)) 80 81 static struct timeval arp_lastlog; 82 static int arp_curpps; 83 static int arp_maxpps = 1; 84 85 /* Simple ARP state machine */ 86 enum arp_llinfo_state { 87 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 88 ARP_LLINFO_REACHABLE, /* LLE is valid */ 89 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 90 ARP_LLINFO_DELETED, /* LLE is deleted */ 91 }; 92 93 SYSCTL_DECL(_net_link_ether); 94 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, 95 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 96 ""); 97 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, 98 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 99 ""); 100 101 /* timer values */ 102 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 103 * minutes */ 104 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 105 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 106 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 107 * 20 seconds */ 108 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 109 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 110 VNET_PCPUSTAT_SYSINIT(arpstat); 111 112 #ifdef VIMAGE 113 VNET_PCPUSTAT_SYSUNINIT(arpstat); 114 #endif /* VIMAGE */ 115 116 VNET_DEFINE_STATIC(int, arp_maxhold) = 1; 117 118 #define V_arpt_keep VNET(arpt_keep) 119 #define V_arpt_down VNET(arpt_down) 120 #define V_arpt_rexmit VNET(arpt_rexmit) 121 #define V_arp_maxtries VNET(arp_maxtries) 122 #define V_arp_proxyall VNET(arp_proxyall) 123 #define V_arp_maxhold VNET(arp_maxhold) 124 125 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 126 &VNET_NAME(arpt_keep), 0, 127 "ARP entry lifetime in seconds"); 128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 129 &VNET_NAME(arp_maxtries), 0, 130 "ARP resolution attempts before returning error"); 131 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 132 &VNET_NAME(arp_proxyall), 0, 133 "Enable proxy ARP for all suitable requests"); 134 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 135 &VNET_NAME(arpt_down), 0, 136 "Incomplete ARP entry lifetime in seconds"); 137 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 138 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 139 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 140 &VNET_NAME(arp_maxhold), 0, 141 "Number of packets to hold per ARP entry"); 142 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 143 CTLFLAG_RW, &arp_maxpps, 0, 144 "Maximum number of remotely triggered ARP messages that can be " 145 "logged per second"); 146 147 /* 148 * Due to the exponential backoff algorithm used for the interval between GARP 149 * retransmissions, the maximum number of retransmissions is limited for 150 * sanity. This limit corresponds to a maximum interval between retransmissions 151 * of 2^16 seconds ~= 18 hours. 152 * 153 * Making this limit more dynamic is more complicated than worthwhile, 154 * especially since sending out GARPs spaced days apart would be of little 155 * use. A maximum dynamic limit would look something like: 156 * 157 * const int max = fls(INT_MAX / hz) - 1; 158 */ 159 #define MAX_GARP_RETRANSMITS 16 160 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 161 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 162 163 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 164 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 165 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 166 "Number of times to retransmit GARP packets;" 167 " 0 to disable, maximum of 16"); 168 169 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 170 #define V_arp_log_level VNET(arp_log_level) 171 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 172 &VNET_NAME(arp_log_level), 0, 173 "Minimum log(9) level for recording rate limited arp log messages. " 174 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 175 #define ARP_LOG(pri, ...) do { \ 176 if ((pri) <= V_arp_log_level && \ 177 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 178 log((pri), "arp: " __VA_ARGS__); \ 179 } while (0) 180 181 182 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 /* 355 * Broadcast an ARP request. Caller specifies: 356 * - arp header source ip address 357 * - arp header target ip address 358 * - arp header source ethernet address 359 */ 360 static int 361 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 362 const struct in_addr *tip, u_char *enaddr) 363 { 364 struct mbuf *m; 365 struct arphdr *ah; 366 struct sockaddr sa; 367 u_char *carpaddr = NULL; 368 uint8_t linkhdr[LLE_MAX_LINKHDR]; 369 size_t linkhdrsize; 370 struct route ro; 371 int error; 372 373 NET_EPOCH_ASSERT(); 374 375 if (sip == NULL) { 376 /* 377 * The caller did not supply a source address, try to find 378 * a compatible one among those assigned to this interface. 379 */ 380 struct ifaddr *ifa; 381 382 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 383 if (ifa->ifa_addr->sa_family != AF_INET) 384 continue; 385 386 if (ifa->ifa_carp) { 387 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 388 continue; 389 sip = &IA_SIN(ifa)->sin_addr; 390 } else { 391 carpaddr = NULL; 392 sip = &IA_SIN(ifa)->sin_addr; 393 } 394 395 if (0 == ((sip->s_addr ^ tip->s_addr) & 396 IA_MASKSIN(ifa)->sin_addr.s_addr)) 397 break; /* found it. */ 398 } 399 if (sip == NULL) { 400 printf("%s: cannot find matching address\n", __func__); 401 return (EADDRNOTAVAIL); 402 } 403 } 404 if (enaddr == NULL) 405 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 406 407 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 408 return (ENOMEM); 409 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 410 2 * ifp->if_addrlen; 411 m->m_pkthdr.len = m->m_len; 412 M_ALIGN(m, m->m_len); 413 ah = mtod(m, struct arphdr *); 414 bzero((caddr_t)ah, m->m_len); 415 #ifdef MAC 416 mac_netinet_arp_send(ifp, m); 417 #endif 418 ah->ar_pro = htons(ETHERTYPE_IP); 419 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 420 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 421 ah->ar_op = htons(ARPOP_REQUEST); 422 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 423 bcopy(sip, ar_spa(ah), ah->ar_pln); 424 bcopy(tip, ar_tpa(ah), ah->ar_pln); 425 sa.sa_family = AF_ARP; 426 sa.sa_len = 2; 427 428 /* Calculate link header for sending frame */ 429 bzero(&ro, sizeof(ro)); 430 linkhdrsize = sizeof(linkhdr); 431 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 432 if (error != 0 && error != EAFNOSUPPORT) { 433 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 434 if_name(ifp), error); 435 return (error); 436 } 437 438 ro.ro_prepend = linkhdr; 439 ro.ro_plen = linkhdrsize; 440 ro.ro_flags = 0; 441 442 m->m_flags |= M_BCAST; 443 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 444 error = (*ifp->if_output)(ifp, m, &sa, &ro); 445 ARPSTAT_INC(txrequests); 446 if (error) { 447 ARPSTAT_INC(txerrors); 448 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 449 if_name(ifp), error); 450 } 451 return (error); 452 } 453 454 void 455 arprequest(struct ifnet *ifp, const struct in_addr *sip, 456 const struct in_addr *tip, u_char *enaddr) 457 { 458 459 (void) arprequest_internal(ifp, sip, tip, enaddr); 460 } 461 462 /* 463 * Resolve an IP address into an ethernet address - heavy version. 464 * Used internally by arpresolve(). 465 * We have already checked that we can't use an existing lle without 466 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 467 * 468 * On success, desten and pflags are filled in and the function returns 0; 469 * If the packet must be held pending resolution, we return EWOULDBLOCK 470 * On other errors, we return the corresponding error code. 471 * Note that m_freem() handles NULL. 472 */ 473 static int 474 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 475 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 476 struct llentry **plle) 477 { 478 struct llentry *la = NULL, *la_tmp; 479 struct mbuf *curr = NULL; 480 struct mbuf *next = NULL; 481 int error, renew; 482 char *lladdr; 483 int ll_len; 484 485 NET_EPOCH_ASSERT(); 486 487 if (pflags != NULL) 488 *pflags = 0; 489 if (plle != NULL) 490 *plle = NULL; 491 492 if ((flags & LLE_CREATE) == 0) 493 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 494 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 495 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 496 if (la == NULL) { 497 char addrbuf[INET_ADDRSTRLEN]; 498 499 log(LOG_DEBUG, 500 "arpresolve: can't allocate llinfo for %s on %s\n", 501 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 502 if_name(ifp)); 503 m_freem(m); 504 return (EINVAL); 505 } 506 507 IF_AFDATA_WLOCK(ifp); 508 LLE_WLOCK(la); 509 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 510 /* Prefer ANY existing lle over newly-created one */ 511 if (la_tmp == NULL) 512 lltable_link_entry(LLTABLE(ifp), la); 513 IF_AFDATA_WUNLOCK(ifp); 514 if (la_tmp != NULL) { 515 lltable_free_entry(LLTABLE(ifp), la); 516 la = la_tmp; 517 } 518 } 519 if (la == NULL) { 520 m_freem(m); 521 return (EINVAL); 522 } 523 524 if ((la->la_flags & LLE_VALID) && 525 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 526 if (flags & LLE_ADDRONLY) { 527 lladdr = la->ll_addr; 528 ll_len = ifp->if_addrlen; 529 } else { 530 lladdr = la->r_linkdata; 531 ll_len = la->r_hdrlen; 532 } 533 bcopy(lladdr, desten, ll_len); 534 535 /* Notify LLE code that the entry was used by datapath */ 536 llentry_mark_used(la); 537 if (pflags != NULL) 538 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 539 if (plle) { 540 LLE_ADDREF(la); 541 *plle = la; 542 } 543 LLE_WUNLOCK(la); 544 return (0); 545 } 546 547 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 548 /* 549 * There is an arptab entry, but no ethernet address 550 * response yet. Add the mbuf to the list, dropping 551 * the oldest packet if we have exceeded the system 552 * setting. 553 */ 554 if (m != NULL) { 555 if (la->la_numheld >= V_arp_maxhold) { 556 if (la->la_hold != NULL) { 557 next = la->la_hold->m_nextpkt; 558 m_freem(la->la_hold); 559 la->la_hold = next; 560 la->la_numheld--; 561 ARPSTAT_INC(dropped); 562 } 563 } 564 if (la->la_hold != NULL) { 565 curr = la->la_hold; 566 while (curr->m_nextpkt != NULL) 567 curr = curr->m_nextpkt; 568 curr->m_nextpkt = m; 569 } else 570 la->la_hold = m; 571 la->la_numheld++; 572 } 573 /* 574 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 575 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 576 * if we have already sent arp_maxtries ARP requests. Retransmit the 577 * ARP request, but not faster than one request per second. 578 */ 579 if (la->la_asked < V_arp_maxtries) 580 error = EWOULDBLOCK; /* First request. */ 581 else 582 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 583 584 if (renew) { 585 int canceled, e; 586 587 LLE_ADDREF(la); 588 la->la_expire = time_uptime; 589 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 590 arptimer, la); 591 if (canceled) 592 LLE_REMREF(la); 593 la->la_asked++; 594 LLE_WUNLOCK(la); 595 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL); 596 /* 597 * Only overwrite 'error' in case of error; in case of success 598 * the proper return value was already set above. 599 */ 600 if (e != 0) 601 return (e); 602 return (error); 603 } 604 605 LLE_WUNLOCK(la); 606 return (error); 607 } 608 609 /* 610 * Lookups link header based on an IP address. 611 * On input: 612 * ifp is the interface we use 613 * is_gw != 0 if @dst represents gateway to some destination 614 * m is the mbuf. May be NULL if we don't have a packet. 615 * dst is the next hop, 616 * desten is the storage to put LL header. 617 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 618 * 619 * On success, full/partial link header and flags are filled in and 620 * the function returns 0. 621 * If the packet must be held pending resolution, we return EWOULDBLOCK 622 * On other errors, we return the corresponding error code. 623 * Note that m_freem() handles NULL. 624 */ 625 int 626 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 627 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 628 struct llentry **plle) 629 { 630 struct llentry *la = NULL; 631 632 NET_EPOCH_ASSERT(); 633 634 if (pflags != NULL) 635 *pflags = 0; 636 if (plle != NULL) 637 *plle = NULL; 638 639 if (m != NULL) { 640 if (m->m_flags & M_BCAST) { 641 /* broadcast */ 642 (void)memcpy(desten, 643 ifp->if_broadcastaddr, ifp->if_addrlen); 644 return (0); 645 } 646 if (m->m_flags & M_MCAST) { 647 /* multicast */ 648 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 649 return (0); 650 } 651 } 652 653 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 654 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 655 /* Entry found, let's copy lle info */ 656 bcopy(la->r_linkdata, desten, la->r_hdrlen); 657 if (pflags != NULL) 658 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 659 /* Notify the LLE handling code that the entry was used. */ 660 llentry_mark_used(la); 661 if (plle) { 662 LLE_ADDREF(la); 663 *plle = la; 664 LLE_WUNLOCK(la); 665 } 666 return (0); 667 } 668 if (plle && la) 669 LLE_WUNLOCK(la); 670 671 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 672 desten, pflags, plle)); 673 } 674 675 /* 676 * Common length and type checks are done here, 677 * then the protocol-specific routine is called. 678 */ 679 static void 680 arpintr(struct mbuf *m) 681 { 682 struct arphdr *ar; 683 struct ifnet *ifp; 684 char *layer; 685 int hlen; 686 687 ifp = m->m_pkthdr.rcvif; 688 689 if (m->m_len < sizeof(struct arphdr) && 690 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 691 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 692 if_name(ifp)); 693 return; 694 } 695 ar = mtod(m, struct arphdr *); 696 697 /* Check if length is sufficient */ 698 if (m->m_len < arphdr_len(ar)) { 699 m = m_pullup(m, arphdr_len(ar)); 700 if (m == NULL) { 701 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 702 if_name(ifp)); 703 return; 704 } 705 ar = mtod(m, struct arphdr *); 706 } 707 708 hlen = 0; 709 layer = ""; 710 switch (ntohs(ar->ar_hrd)) { 711 case ARPHRD_ETHER: 712 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 713 layer = "ethernet"; 714 break; 715 case ARPHRD_INFINIBAND: 716 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 717 layer = "infiniband"; 718 break; 719 case ARPHRD_IEEE1394: 720 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 721 layer = "firewire"; 722 723 /* 724 * Restrict too long hardware addresses. 725 * Currently we are capable of handling 20-byte 726 * addresses ( sizeof(lle->ll_addr) ) 727 */ 728 if (ar->ar_hln >= 20) 729 hlen = 16; 730 break; 731 default: 732 ARP_LOG(LOG_NOTICE, 733 "packet with unknown hardware format 0x%02d received on " 734 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 735 m_freem(m); 736 return; 737 } 738 739 if (hlen != 0 && hlen != ar->ar_hln) { 740 ARP_LOG(LOG_NOTICE, 741 "packet with invalid %s address length %d received on %s\n", 742 layer, ar->ar_hln, if_name(ifp)); 743 m_freem(m); 744 return; 745 } 746 747 ARPSTAT_INC(received); 748 switch (ntohs(ar->ar_pro)) { 749 #ifdef INET 750 case ETHERTYPE_IP: 751 in_arpinput(m); 752 return; 753 #endif 754 } 755 m_freem(m); 756 } 757 758 #ifdef INET 759 /* 760 * ARP for Internet protocols on 10 Mb/s Ethernet. 761 * Algorithm is that given in RFC 826. 762 * In addition, a sanity check is performed on the sender 763 * protocol address, to catch impersonators. 764 * We no longer handle negotiations for use of trailer protocol: 765 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 766 * along with IP replies if we wanted trailers sent to us, 767 * and also sent them in response to IP replies. 768 * This allowed either end to announce the desire to receive 769 * trailer packets. 770 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 771 * but formerly didn't normally send requests. 772 */ 773 static int log_arp_wrong_iface = 1; 774 static int log_arp_movements = 1; 775 static int log_arp_permanent_modify = 1; 776 static int allow_multicast = 0; 777 778 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 779 &log_arp_wrong_iface, 0, 780 "log arp packets arriving on the wrong interface"); 781 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 782 &log_arp_movements, 0, 783 "log arp replies from MACs different than the one in the cache"); 784 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 785 &log_arp_permanent_modify, 0, 786 "log arp replies from MACs different than the one in the permanent arp entry"); 787 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 788 &allow_multicast, 0, "accept multicast addresses"); 789 790 static void 791 in_arpinput(struct mbuf *m) 792 { 793 struct rm_priotracker in_ifa_tracker; 794 struct arphdr *ah; 795 struct ifnet *ifp = m->m_pkthdr.rcvif; 796 struct llentry *la = NULL, *la_tmp; 797 struct ifaddr *ifa; 798 struct in_ifaddr *ia; 799 struct sockaddr sa; 800 struct in_addr isaddr, itaddr, myaddr; 801 u_int8_t *enaddr = NULL; 802 int op; 803 int bridged = 0, is_bridge = 0; 804 int carped; 805 struct sockaddr_in sin; 806 struct sockaddr *dst; 807 struct nhop4_basic nh4; 808 uint8_t linkhdr[LLE_MAX_LINKHDR]; 809 struct route ro; 810 size_t linkhdrsize; 811 int lladdr_off; 812 int error; 813 char addrbuf[INET_ADDRSTRLEN]; 814 815 NET_EPOCH_ASSERT(); 816 817 sin.sin_len = sizeof(struct sockaddr_in); 818 sin.sin_family = AF_INET; 819 sin.sin_addr.s_addr = 0; 820 821 if (ifp->if_bridge) 822 bridged = 1; 823 if (ifp->if_type == IFT_BRIDGE) 824 is_bridge = 1; 825 826 /* 827 * We already have checked that mbuf contains enough contiguous data 828 * to hold entire arp message according to the arp header. 829 */ 830 ah = mtod(m, struct arphdr *); 831 832 /* 833 * ARP is only for IPv4 so we can reject packets with 834 * a protocol length not equal to an IPv4 address. 835 */ 836 if (ah->ar_pln != sizeof(struct in_addr)) { 837 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 838 sizeof(struct in_addr)); 839 goto drop; 840 } 841 842 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 843 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 844 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 845 goto drop; 846 } 847 848 op = ntohs(ah->ar_op); 849 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 850 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 851 852 if (op == ARPOP_REPLY) 853 ARPSTAT_INC(rxreplies); 854 855 /* 856 * For a bridge, we want to check the address irrespective 857 * of the receive interface. (This will change slightly 858 * when we have clusters of interfaces). 859 */ 860 IN_IFADDR_RLOCK(&in_ifa_tracker); 861 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 862 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 863 ia->ia_ifp == ifp) && 864 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 865 (ia->ia_ifa.ifa_carp == NULL || 866 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 867 ifa_ref(&ia->ia_ifa); 868 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 869 goto match; 870 } 871 } 872 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 873 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 874 ia->ia_ifp == ifp) && 875 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 876 ifa_ref(&ia->ia_ifa); 877 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 878 goto match; 879 } 880 881 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 882 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 883 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 884 addr == ia->ia_addr.sin_addr.s_addr) 885 /* 886 * Check the case when bridge shares its MAC address with 887 * some of its children, so packets are claimed by bridge 888 * itself (bridge_input() does it first), but they are really 889 * meant to be destined to the bridge member. 890 */ 891 if (is_bridge) { 892 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 893 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 894 ifa_ref(&ia->ia_ifa); 895 ifp = ia->ia_ifp; 896 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 897 goto match; 898 } 899 } 900 } 901 #undef BDG_MEMBER_MATCHES_ARP 902 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 903 904 /* 905 * No match, use the first inet address on the receive interface 906 * as a dummy address for the rest of the function. 907 */ 908 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 909 if (ifa->ifa_addr->sa_family == AF_INET && 910 (ifa->ifa_carp == NULL || 911 (*carp_iamatch_p)(ifa, &enaddr))) { 912 ia = ifatoia(ifa); 913 ifa_ref(ifa); 914 goto match; 915 } 916 917 /* 918 * If bridging, fall back to using any inet address. 919 */ 920 IN_IFADDR_RLOCK(&in_ifa_tracker); 921 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 922 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 923 goto drop; 924 } 925 ifa_ref(&ia->ia_ifa); 926 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 927 match: 928 if (!enaddr) 929 enaddr = (u_int8_t *)IF_LLADDR(ifp); 930 carped = (ia->ia_ifa.ifa_carp != NULL); 931 myaddr = ia->ia_addr.sin_addr; 932 ifa_free(&ia->ia_ifa); 933 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 934 goto drop; /* it's from me, ignore it. */ 935 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 936 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 937 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 938 goto drop; 939 } 940 941 if (ifp->if_addrlen != ah->ar_hln) { 942 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 943 "i/f %d (ignored)\n", ifp->if_addrlen, 944 (u_char *) ar_sha(ah), ":", ah->ar_hln, 945 ifp->if_addrlen); 946 goto drop; 947 } 948 949 /* 950 * Warn if another host is using the same IP address, but only if the 951 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 952 * case we suppress the warning to avoid false positive complaints of 953 * potential misconfiguration. 954 */ 955 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 956 myaddr.s_addr != 0) { 957 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 958 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 959 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 960 itaddr = myaddr; 961 ARPSTAT_INC(dupips); 962 goto reply; 963 } 964 if (ifp->if_flags & IFF_STATICARP) 965 goto reply; 966 967 bzero(&sin, sizeof(sin)); 968 sin.sin_len = sizeof(struct sockaddr_in); 969 sin.sin_family = AF_INET; 970 sin.sin_addr = isaddr; 971 dst = (struct sockaddr *)&sin; 972 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 973 if (la != NULL) 974 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 975 else if (itaddr.s_addr == myaddr.s_addr) { 976 /* 977 * Request/reply to our address, but no lle exists yet. 978 * Calculate full link prepend to use in lle. 979 */ 980 linkhdrsize = sizeof(linkhdr); 981 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 982 &linkhdrsize, &lladdr_off) != 0) 983 goto reply; 984 985 /* Allocate new entry */ 986 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 987 if (la == NULL) { 988 989 /* 990 * lle creation may fail if source address belongs 991 * to non-directly connected subnet. However, we 992 * will try to answer the request instead of dropping 993 * frame. 994 */ 995 goto reply; 996 } 997 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 998 lladdr_off); 999 1000 IF_AFDATA_WLOCK(ifp); 1001 LLE_WLOCK(la); 1002 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1003 1004 /* 1005 * Check if lle still does not exists. 1006 * If it does, that means that we either 1007 * 1) have configured it explicitly, via 1008 * 1a) 'arp -s' static entry or 1009 * 1b) interface address static record 1010 * or 1011 * 2) it was the result of sending first packet to-host 1012 * or 1013 * 3) it was another arp reply packet we handled in 1014 * different thread. 1015 * 1016 * In all cases except 3) we definitely need to prefer 1017 * existing lle. For the sake of simplicity, prefer any 1018 * existing lle over newly-create one. 1019 */ 1020 if (la_tmp == NULL) 1021 lltable_link_entry(LLTABLE(ifp), la); 1022 IF_AFDATA_WUNLOCK(ifp); 1023 1024 if (la_tmp == NULL) { 1025 arp_mark_lle_reachable(la); 1026 LLE_WUNLOCK(la); 1027 } else { 1028 /* Free newly-create entry and handle packet */ 1029 lltable_free_entry(LLTABLE(ifp), la); 1030 la = la_tmp; 1031 la_tmp = NULL; 1032 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1033 /* arp_check_update_lle() returns @la unlocked */ 1034 } 1035 la = NULL; 1036 } 1037 reply: 1038 if (op != ARPOP_REQUEST) 1039 goto drop; 1040 ARPSTAT_INC(rxrequests); 1041 1042 if (itaddr.s_addr == myaddr.s_addr) { 1043 /* Shortcut.. the receiving interface is the target. */ 1044 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1045 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1046 } else { 1047 struct llentry *lle = NULL; 1048 1049 sin.sin_addr = itaddr; 1050 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1051 1052 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1053 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1054 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1055 LLE_RUNLOCK(lle); 1056 } else { 1057 1058 if (lle != NULL) 1059 LLE_RUNLOCK(lle); 1060 1061 if (!V_arp_proxyall) 1062 goto drop; 1063 1064 /* XXX MRT use table 0 for arp reply */ 1065 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1066 goto drop; 1067 1068 /* 1069 * Don't send proxies for nodes on the same interface 1070 * as this one came out of, or we'll get into a fight 1071 * over who claims what Ether address. 1072 */ 1073 if (nh4.nh_ifp == ifp) 1074 goto drop; 1075 1076 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1077 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1078 1079 /* 1080 * Also check that the node which sent the ARP packet 1081 * is on the interface we expect it to be on. This 1082 * avoids ARP chaos if an interface is connected to the 1083 * wrong network. 1084 */ 1085 1086 /* XXX MRT use table 0 for arp checks */ 1087 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1088 goto drop; 1089 if (nh4.nh_ifp != ifp) { 1090 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1091 " from %s via %s\n", 1092 inet_ntoa_r(isaddr, addrbuf), 1093 ifp->if_xname); 1094 goto drop; 1095 } 1096 1097 #ifdef DEBUG_PROXY 1098 printf("arp: proxying for %s\n", 1099 inet_ntoa_r(itaddr, addrbuf)); 1100 #endif 1101 } 1102 } 1103 1104 if (itaddr.s_addr == myaddr.s_addr && 1105 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1106 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1107 #ifdef DEBUG_LINKLOCAL 1108 printf("arp: sending reply for link-local addr %s\n", 1109 inet_ntoa_r(itaddr, addrbuf)); 1110 #endif 1111 m->m_flags |= M_BCAST; 1112 m->m_flags &= ~M_MCAST; 1113 } else { 1114 /* default behaviour; never reply by broadcast. */ 1115 m->m_flags &= ~(M_BCAST|M_MCAST); 1116 } 1117 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1118 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1119 ah->ar_op = htons(ARPOP_REPLY); 1120 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1121 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1122 m->m_pkthdr.len = m->m_len; 1123 m->m_pkthdr.rcvif = NULL; 1124 sa.sa_family = AF_ARP; 1125 sa.sa_len = 2; 1126 1127 /* Calculate link header for sending frame */ 1128 bzero(&ro, sizeof(ro)); 1129 linkhdrsize = sizeof(linkhdr); 1130 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1131 1132 /* 1133 * arp_fillheader() may fail due to lack of support inside encap request 1134 * routing. This is not necessary an error, AF_ARP can/should be handled 1135 * by if_output(). 1136 */ 1137 if (error != 0 && error != EAFNOSUPPORT) { 1138 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1139 if_name(ifp), error); 1140 return; 1141 } 1142 1143 ro.ro_prepend = linkhdr; 1144 ro.ro_plen = linkhdrsize; 1145 ro.ro_flags = 0; 1146 1147 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1148 (*ifp->if_output)(ifp, m, &sa, &ro); 1149 ARPSTAT_INC(txreplies); 1150 return; 1151 1152 drop: 1153 m_freem(m); 1154 } 1155 #endif 1156 1157 /* 1158 * Checks received arp data against existing @la. 1159 * Updates lle state/performs notification if necessary. 1160 */ 1161 static void 1162 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1163 int bridged, struct llentry *la) 1164 { 1165 struct sockaddr sa; 1166 struct mbuf *m_hold, *m_hold_next; 1167 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1168 size_t linkhdrsize; 1169 int lladdr_off; 1170 char addrbuf[INET_ADDRSTRLEN]; 1171 1172 LLE_WLOCK_ASSERT(la); 1173 1174 /* the following is not an error when doing bridging */ 1175 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1176 if (log_arp_wrong_iface) 1177 ARP_LOG(LOG_WARNING, "%s is on %s " 1178 "but got reply from %*D on %s\n", 1179 inet_ntoa_r(isaddr, addrbuf), 1180 la->lle_tbl->llt_ifp->if_xname, 1181 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1182 ifp->if_xname); 1183 LLE_WUNLOCK(la); 1184 return; 1185 } 1186 if ((la->la_flags & LLE_VALID) && 1187 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1188 if (la->la_flags & LLE_STATIC) { 1189 LLE_WUNLOCK(la); 1190 if (log_arp_permanent_modify) 1191 ARP_LOG(LOG_ERR, 1192 "%*D attempts to modify " 1193 "permanent entry for %s on %s\n", 1194 ifp->if_addrlen, 1195 (u_char *)ar_sha(ah), ":", 1196 inet_ntoa_r(isaddr, addrbuf), 1197 ifp->if_xname); 1198 return; 1199 } 1200 if (log_arp_movements) { 1201 ARP_LOG(LOG_INFO, "%s moved from %*D " 1202 "to %*D on %s\n", 1203 inet_ntoa_r(isaddr, addrbuf), 1204 ifp->if_addrlen, 1205 (u_char *)la->ll_addr, ":", 1206 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1207 ifp->if_xname); 1208 } 1209 } 1210 1211 /* Calculate full link prepend to use in lle */ 1212 linkhdrsize = sizeof(linkhdr); 1213 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1214 &linkhdrsize, &lladdr_off) != 0) 1215 return; 1216 1217 /* Check if something has changed */ 1218 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1219 (la->la_flags & LLE_VALID) == 0) { 1220 /* Try to perform LLE update */ 1221 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1222 lladdr_off) == 0) 1223 return; 1224 1225 /* Clear fast path feedback request if set */ 1226 la->r_skip_req = 0; 1227 } 1228 1229 arp_mark_lle_reachable(la); 1230 1231 /* 1232 * The packets are all freed within the call to the output 1233 * routine. 1234 * 1235 * NB: The lock MUST be released before the call to the 1236 * output routine. 1237 */ 1238 if (la->la_hold != NULL) { 1239 m_hold = la->la_hold; 1240 la->la_hold = NULL; 1241 la->la_numheld = 0; 1242 lltable_fill_sa_entry(la, &sa); 1243 LLE_WUNLOCK(la); 1244 for (; m_hold != NULL; m_hold = m_hold_next) { 1245 m_hold_next = m_hold->m_nextpkt; 1246 m_hold->m_nextpkt = NULL; 1247 /* Avoid confusing lower layers. */ 1248 m_clrprotoflags(m_hold); 1249 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1250 } 1251 } else 1252 LLE_WUNLOCK(la); 1253 } 1254 1255 static void 1256 arp_mark_lle_reachable(struct llentry *la) 1257 { 1258 int canceled, wtime; 1259 1260 LLE_WLOCK_ASSERT(la); 1261 1262 la->ln_state = ARP_LLINFO_REACHABLE; 1263 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1264 1265 if (!(la->la_flags & LLE_STATIC)) { 1266 LLE_ADDREF(la); 1267 la->la_expire = time_uptime + V_arpt_keep; 1268 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1269 if (wtime < 0) 1270 wtime = V_arpt_keep; 1271 canceled = callout_reset(&la->lle_timer, 1272 hz * wtime, arptimer, la); 1273 if (canceled) 1274 LLE_REMREF(la); 1275 } 1276 la->la_asked = 0; 1277 la->la_preempt = V_arp_maxtries; 1278 } 1279 1280 /* 1281 * Add permanent link-layer record for given interface address. 1282 */ 1283 static __noinline void 1284 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1285 { 1286 struct llentry *lle, *lle_tmp; 1287 1288 /* 1289 * Interface address LLE record is considered static 1290 * because kernel code relies on LLE_STATIC flag to check 1291 * if these entries can be rewriten by arp updates. 1292 */ 1293 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1294 if (lle == NULL) { 1295 log(LOG_INFO, "arp_ifinit: cannot create arp " 1296 "entry for interface address\n"); 1297 return; 1298 } 1299 1300 IF_AFDATA_WLOCK(ifp); 1301 LLE_WLOCK(lle); 1302 /* Unlink any entry if exists */ 1303 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1304 if (lle_tmp != NULL) 1305 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1306 1307 lltable_link_entry(LLTABLE(ifp), lle); 1308 IF_AFDATA_WUNLOCK(ifp); 1309 1310 if (lle_tmp != NULL) 1311 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1312 1313 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1314 LLE_WUNLOCK(lle); 1315 if (lle_tmp != NULL) 1316 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1317 } 1318 1319 /* 1320 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1321 * of valid values. 1322 */ 1323 static int 1324 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1325 { 1326 int error; 1327 int rexmit_count = *(int *)arg1; 1328 1329 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1330 1331 /* Enforce limits on any new value that may have been set. */ 1332 if (!error && req->newptr) { 1333 /* A new value was set. */ 1334 if (rexmit_count < 0) { 1335 rexmit_count = 0; 1336 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1337 rexmit_count = MAX_GARP_RETRANSMITS; 1338 } 1339 *(int *)arg1 = rexmit_count; 1340 } 1341 1342 return (error); 1343 } 1344 1345 /* 1346 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1347 * retransmit it again. A pending callout owns a reference to the ifa. 1348 */ 1349 static void 1350 garp_rexmit(void *arg) 1351 { 1352 struct in_ifaddr *ia = arg; 1353 1354 if (callout_pending(&ia->ia_garp_timer) || 1355 !callout_active(&ia->ia_garp_timer)) { 1356 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1357 ifa_free(&ia->ia_ifa); 1358 return; 1359 } 1360 1361 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1362 1363 /* 1364 * Drop lock while the ARP request is generated. 1365 */ 1366 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1367 1368 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1369 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1370 1371 /* 1372 * Increment the count of retransmissions. If the count has reached the 1373 * maximum value, stop sending the GARP packets. Otherwise, schedule 1374 * the callout to retransmit another GARP packet. 1375 */ 1376 ++ia->ia_garp_count; 1377 if (ia->ia_garp_count >= garp_rexmit_count) { 1378 ifa_free(&ia->ia_ifa); 1379 } else { 1380 int rescheduled; 1381 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1382 rescheduled = callout_reset(&ia->ia_garp_timer, 1383 (1 << ia->ia_garp_count) * hz, 1384 garp_rexmit, ia); 1385 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1386 if (rescheduled) { 1387 ifa_free(&ia->ia_ifa); 1388 } 1389 } 1390 1391 CURVNET_RESTORE(); 1392 } 1393 1394 /* 1395 * Start the GARP retransmit timer. 1396 * 1397 * A single GARP is always transmitted when an IPv4 address is added 1398 * to an interface and that is usually sufficient. However, in some 1399 * circumstances, such as when a shared address is passed between 1400 * cluster nodes, this single GARP may occasionally be dropped or 1401 * lost. This can lead to neighbors on the network link working with a 1402 * stale ARP cache and sending packets destined for that address to 1403 * the node that previously owned the address, which may not respond. 1404 * 1405 * To avoid this situation, GARP retransmits can be enabled by setting 1406 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1407 * than zero. The setting represents the maximum number of 1408 * retransmissions. The interval between retransmissions is calculated 1409 * using an exponential backoff algorithm, doubling each time, so the 1410 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1411 */ 1412 static void 1413 garp_timer_start(struct ifaddr *ifa) 1414 { 1415 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1416 1417 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1418 ia->ia_garp_count = 0; 1419 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1420 garp_rexmit, ia) == 0) { 1421 ifa_ref(ifa); 1422 } 1423 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1424 } 1425 1426 void 1427 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1428 { 1429 struct epoch_tracker et; 1430 const struct sockaddr_in *dst_in; 1431 const struct sockaddr *dst; 1432 1433 if (ifa->ifa_carp != NULL) 1434 return; 1435 1436 dst = ifa->ifa_addr; 1437 dst_in = (const struct sockaddr_in *)dst; 1438 1439 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1440 return; 1441 NET_EPOCH_ENTER(et); 1442 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1443 NET_EPOCH_EXIT(et); 1444 if (garp_rexmit_count > 0) { 1445 garp_timer_start(ifa); 1446 } 1447 1448 arp_add_ifa_lle(ifp, dst); 1449 } 1450 1451 void 1452 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1453 { 1454 1455 if (ntohl(addr.s_addr) != INADDR_ANY) 1456 arprequest(ifp, &addr, &addr, enaddr); 1457 } 1458 1459 /* 1460 * Sends gratuitous ARPs for each ifaddr to notify other 1461 * nodes about the address change. 1462 */ 1463 static __noinline void 1464 arp_handle_ifllchange(struct ifnet *ifp) 1465 { 1466 struct ifaddr *ifa; 1467 1468 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1469 if (ifa->ifa_addr->sa_family == AF_INET) 1470 arp_ifinit(ifp, ifa); 1471 } 1472 } 1473 1474 /* 1475 * A handler for interface link layer address change event. 1476 */ 1477 static void 1478 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1479 { 1480 1481 lltable_update_ifaddr(LLTABLE(ifp)); 1482 1483 if ((ifp->if_flags & IFF_UP) != 0) 1484 arp_handle_ifllchange(ifp); 1485 } 1486 1487 static void 1488 vnet_arp_init(void) 1489 { 1490 1491 if (IS_DEFAULT_VNET(curvnet)) { 1492 netisr_register(&arp_nh); 1493 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1494 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1495 } 1496 #ifdef VIMAGE 1497 else 1498 netisr_register_vnet(&arp_nh); 1499 #endif 1500 } 1501 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1502 vnet_arp_init, 0); 1503 1504 #ifdef VIMAGE 1505 /* 1506 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1507 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1508 */ 1509 static void 1510 vnet_arp_destroy(__unused void *arg) 1511 { 1512 1513 netisr_unregister_vnet(&arp_nh); 1514 } 1515 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1516 vnet_arp_destroy, NULL); 1517 #endif 1518