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, CTLFLAG_RW, 0, ""); 95 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 96 97 /* timer values */ 98 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 99 * minutes */ 100 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 101 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 102 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 103 * 20 seconds */ 104 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 105 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 106 VNET_PCPUSTAT_SYSINIT(arpstat); 107 108 #ifdef VIMAGE 109 VNET_PCPUSTAT_SYSUNINIT(arpstat); 110 #endif /* VIMAGE */ 111 112 VNET_DEFINE_STATIC(int, arp_maxhold) = 1; 113 114 #define V_arpt_keep VNET(arpt_keep) 115 #define V_arpt_down VNET(arpt_down) 116 #define V_arpt_rexmit VNET(arpt_rexmit) 117 #define V_arp_maxtries VNET(arp_maxtries) 118 #define V_arp_proxyall VNET(arp_proxyall) 119 #define V_arp_maxhold VNET(arp_maxhold) 120 121 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 122 &VNET_NAME(arpt_keep), 0, 123 "ARP entry lifetime in seconds"); 124 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 125 &VNET_NAME(arp_maxtries), 0, 126 "ARP resolution attempts before returning error"); 127 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 128 &VNET_NAME(arp_proxyall), 0, 129 "Enable proxy ARP for all suitable requests"); 130 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 131 &VNET_NAME(arpt_down), 0, 132 "Incomplete ARP entry lifetime in seconds"); 133 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 134 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 136 &VNET_NAME(arp_maxhold), 0, 137 "Number of packets to hold per ARP entry"); 138 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 139 CTLFLAG_RW, &arp_maxpps, 0, 140 "Maximum number of remotely triggered ARP messages that can be " 141 "logged per second"); 142 143 /* 144 * Due to the exponential backoff algorithm used for the interval between GARP 145 * retransmissions, the maximum number of retransmissions is limited for 146 * sanity. This limit corresponds to a maximum interval between retransmissions 147 * of 2^16 seconds ~= 18 hours. 148 * 149 * Making this limit more dynamic is more complicated than worthwhile, 150 * especially since sending out GARPs spaced days apart would be of little 151 * use. A maximum dynamic limit would look something like: 152 * 153 * const int max = fls(INT_MAX / hz) - 1; 154 */ 155 #define MAX_GARP_RETRANSMITS 16 156 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 157 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 158 159 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 160 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 161 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 162 "Number of times to retransmit GARP packets;" 163 " 0 to disable, maximum of 16"); 164 165 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */ 166 #define V_arp_log_level VNET(arp_log_level) 167 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW, 168 &VNET_NAME(arp_log_level), 0, 169 "Minimum log(9) level for recording rate limited arp log messages. " 170 "The higher will be log more (emerg=0, info=6 (default), debug=7)."); 171 #define ARP_LOG(pri, ...) do { \ 172 if ((pri) <= V_arp_log_level && \ 173 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 174 log((pri), "arp: " __VA_ARGS__); \ 175 } while (0) 176 177 178 static void arpintr(struct mbuf *); 179 static void arptimer(void *); 180 #ifdef INET 181 static void in_arpinput(struct mbuf *); 182 #endif 183 184 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 185 struct ifnet *ifp, int bridged, struct llentry *la); 186 static void arp_mark_lle_reachable(struct llentry *la); 187 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 188 189 static eventhandler_tag iflladdr_tag; 190 191 static const struct netisr_handler arp_nh = { 192 .nh_name = "arp", 193 .nh_handler = arpintr, 194 .nh_proto = NETISR_ARP, 195 .nh_policy = NETISR_POLICY_SOURCE, 196 }; 197 198 /* 199 * Timeout routine. Age arp_tab entries periodically. 200 */ 201 static void 202 arptimer(void *arg) 203 { 204 struct llentry *lle = (struct llentry *)arg; 205 struct ifnet *ifp; 206 int r_skip_req; 207 208 if (lle->la_flags & LLE_STATIC) { 209 return; 210 } 211 LLE_WLOCK(lle); 212 if (callout_pending(&lle->lle_timer)) { 213 /* 214 * Here we are a bit odd here in the treatment of 215 * active/pending. If the pending bit is set, it got 216 * rescheduled before I ran. The active 217 * bit we ignore, since if it was stopped 218 * in ll_tablefree() and was currently running 219 * it would have return 0 so the code would 220 * not have deleted it since the callout could 221 * not be stopped so we want to go through 222 * with the delete here now. If the callout 223 * was restarted, the pending bit will be back on and 224 * we just want to bail since the callout_reset would 225 * return 1 and our reference would have been removed 226 * by arpresolve() below. 227 */ 228 LLE_WUNLOCK(lle); 229 return; 230 } 231 ifp = lle->lle_tbl->llt_ifp; 232 CURVNET_SET(ifp->if_vnet); 233 234 switch (lle->ln_state) { 235 case ARP_LLINFO_REACHABLE: 236 237 /* 238 * Expiration time is approaching. 239 * Let's try to refresh entry if it is still 240 * in use. 241 * 242 * Set r_skip_req to get feedback from 243 * fast path. Change state and re-schedule 244 * ourselves. 245 */ 246 LLE_REQ_LOCK(lle); 247 lle->r_skip_req = 1; 248 LLE_REQ_UNLOCK(lle); 249 lle->ln_state = ARP_LLINFO_VERIFY; 250 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 251 LLE_WUNLOCK(lle); 252 CURVNET_RESTORE(); 253 return; 254 case ARP_LLINFO_VERIFY: 255 LLE_REQ_LOCK(lle); 256 r_skip_req = lle->r_skip_req; 257 LLE_REQ_UNLOCK(lle); 258 259 if (r_skip_req == 0 && lle->la_preempt > 0) { 260 /* Entry was used, issue refresh request */ 261 struct epoch_tracker et; 262 struct in_addr dst; 263 264 dst = lle->r_l3addr.addr4; 265 lle->la_preempt--; 266 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 267 LLE_WUNLOCK(lle); 268 NET_EPOCH_ENTER(et); 269 arprequest(ifp, NULL, &dst, NULL); 270 NET_EPOCH_EXIT(et); 271 CURVNET_RESTORE(); 272 return; 273 } 274 /* Nothing happened. Reschedule if not too late */ 275 if (lle->la_expire > time_uptime) { 276 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 277 LLE_WUNLOCK(lle); 278 CURVNET_RESTORE(); 279 return; 280 } 281 break; 282 case ARP_LLINFO_INCOMPLETE: 283 case ARP_LLINFO_DELETED: 284 break; 285 } 286 287 if ((lle->la_flags & LLE_DELETED) == 0) { 288 int evt; 289 290 if (lle->la_flags & LLE_VALID) 291 evt = LLENTRY_EXPIRED; 292 else 293 evt = LLENTRY_TIMEDOUT; 294 EVENTHANDLER_INVOKE(lle_event, lle, evt); 295 } 296 297 callout_stop(&lle->lle_timer); 298 299 /* XXX: LOR avoidance. We still have ref on lle. */ 300 LLE_WUNLOCK(lle); 301 IF_AFDATA_LOCK(ifp); 302 LLE_WLOCK(lle); 303 304 /* Guard against race with other llentry_free(). */ 305 if (lle->la_flags & LLE_LINKED) { 306 LLE_REMREF(lle); 307 lltable_unlink_entry(lle->lle_tbl, lle); 308 } 309 IF_AFDATA_UNLOCK(ifp); 310 311 size_t pkts_dropped = llentry_free(lle); 312 313 ARPSTAT_ADD(dropped, pkts_dropped); 314 ARPSTAT_INC(timeouts); 315 316 CURVNET_RESTORE(); 317 } 318 319 /* 320 * Stores link-layer header for @ifp in format suitable for if_output() 321 * into buffer @buf. Resulting header length is stored in @bufsize. 322 * 323 * Returns 0 on success. 324 */ 325 static int 326 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 327 size_t *bufsize) 328 { 329 struct if_encap_req ereq; 330 int error; 331 332 bzero(buf, *bufsize); 333 bzero(&ereq, sizeof(ereq)); 334 ereq.buf = buf; 335 ereq.bufsize = *bufsize; 336 ereq.rtype = IFENCAP_LL; 337 ereq.family = AF_ARP; 338 ereq.lladdr = ar_tha(ah); 339 ereq.hdata = (u_char *)ah; 340 if (bcast) 341 ereq.flags = IFENCAP_FLAG_BROADCAST; 342 error = ifp->if_requestencap(ifp, &ereq); 343 if (error == 0) 344 *bufsize = ereq.bufsize; 345 346 return (error); 347 } 348 349 350 /* 351 * Broadcast an ARP request. Caller specifies: 352 * - arp header source ip address 353 * - arp header target ip address 354 * - arp header source ethernet address 355 */ 356 static int 357 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 358 const struct in_addr *tip, u_char *enaddr) 359 { 360 struct mbuf *m; 361 struct arphdr *ah; 362 struct sockaddr sa; 363 u_char *carpaddr = NULL; 364 uint8_t linkhdr[LLE_MAX_LINKHDR]; 365 size_t linkhdrsize; 366 struct route ro; 367 int error; 368 369 NET_EPOCH_ASSERT(); 370 371 if (sip == NULL) { 372 /* 373 * The caller did not supply a source address, try to find 374 * a compatible one among those assigned to this interface. 375 */ 376 struct ifaddr *ifa; 377 378 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 379 if (ifa->ifa_addr->sa_family != AF_INET) 380 continue; 381 382 if (ifa->ifa_carp) { 383 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 384 continue; 385 sip = &IA_SIN(ifa)->sin_addr; 386 } else { 387 carpaddr = NULL; 388 sip = &IA_SIN(ifa)->sin_addr; 389 } 390 391 if (0 == ((sip->s_addr ^ tip->s_addr) & 392 IA_MASKSIN(ifa)->sin_addr.s_addr)) 393 break; /* found it. */ 394 } 395 if (sip == NULL) { 396 printf("%s: cannot find matching address\n", __func__); 397 return (EADDRNOTAVAIL); 398 } 399 } 400 if (enaddr == NULL) 401 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 402 403 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 404 return (ENOMEM); 405 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 406 2 * ifp->if_addrlen; 407 m->m_pkthdr.len = m->m_len; 408 M_ALIGN(m, m->m_len); 409 ah = mtod(m, struct arphdr *); 410 bzero((caddr_t)ah, m->m_len); 411 #ifdef MAC 412 mac_netinet_arp_send(ifp, m); 413 #endif 414 ah->ar_pro = htons(ETHERTYPE_IP); 415 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 416 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 417 ah->ar_op = htons(ARPOP_REQUEST); 418 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 419 bcopy(sip, ar_spa(ah), ah->ar_pln); 420 bcopy(tip, ar_tpa(ah), ah->ar_pln); 421 sa.sa_family = AF_ARP; 422 sa.sa_len = 2; 423 424 /* Calculate link header for sending frame */ 425 bzero(&ro, sizeof(ro)); 426 linkhdrsize = sizeof(linkhdr); 427 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 428 if (error != 0 && error != EAFNOSUPPORT) { 429 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 430 if_name(ifp), error); 431 return (error); 432 } 433 434 ro.ro_prepend = linkhdr; 435 ro.ro_plen = linkhdrsize; 436 ro.ro_flags = 0; 437 438 m->m_flags |= M_BCAST; 439 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 440 error = (*ifp->if_output)(ifp, m, &sa, &ro); 441 ARPSTAT_INC(txrequests); 442 if (error) { 443 ARPSTAT_INC(txerrors); 444 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 445 if_name(ifp), error); 446 } 447 return (error); 448 } 449 450 void 451 arprequest(struct ifnet *ifp, const struct in_addr *sip, 452 const struct in_addr *tip, u_char *enaddr) 453 { 454 455 (void) arprequest_internal(ifp, sip, tip, enaddr); 456 } 457 458 /* 459 * Resolve an IP address into an ethernet address - heavy version. 460 * Used internally by arpresolve(). 461 * We have already checked that we can't use an existing lle without 462 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 463 * 464 * On success, desten and pflags are filled in and the function returns 0; 465 * If the packet must be held pending resolution, we return EWOULDBLOCK 466 * On other errors, we return the corresponding error code. 467 * Note that m_freem() handles NULL. 468 */ 469 static int 470 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 471 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 472 struct llentry **plle) 473 { 474 struct llentry *la = NULL, *la_tmp; 475 struct mbuf *curr = NULL; 476 struct mbuf *next = NULL; 477 int error, renew; 478 char *lladdr; 479 int ll_len; 480 481 NET_EPOCH_ASSERT(); 482 483 if (pflags != NULL) 484 *pflags = 0; 485 if (plle != NULL) 486 *plle = NULL; 487 488 if ((flags & LLE_CREATE) == 0) 489 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 490 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 491 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 492 if (la == NULL) { 493 char addrbuf[INET_ADDRSTRLEN]; 494 495 log(LOG_DEBUG, 496 "arpresolve: can't allocate llinfo for %s on %s\n", 497 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 498 if_name(ifp)); 499 m_freem(m); 500 return (EINVAL); 501 } 502 503 IF_AFDATA_WLOCK(ifp); 504 LLE_WLOCK(la); 505 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 506 /* Prefer ANY existing lle over newly-created one */ 507 if (la_tmp == NULL) 508 lltable_link_entry(LLTABLE(ifp), la); 509 IF_AFDATA_WUNLOCK(ifp); 510 if (la_tmp != NULL) { 511 lltable_free_entry(LLTABLE(ifp), la); 512 la = la_tmp; 513 } 514 } 515 if (la == NULL) { 516 m_freem(m); 517 return (EINVAL); 518 } 519 520 if ((la->la_flags & LLE_VALID) && 521 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 522 if (flags & LLE_ADDRONLY) { 523 lladdr = la->ll_addr; 524 ll_len = ifp->if_addrlen; 525 } else { 526 lladdr = la->r_linkdata; 527 ll_len = la->r_hdrlen; 528 } 529 bcopy(lladdr, desten, ll_len); 530 531 /* Notify LLE code that the entry was used by datapath */ 532 llentry_mark_used(la); 533 if (pflags != NULL) 534 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 535 if (plle) { 536 LLE_ADDREF(la); 537 *plle = la; 538 } 539 LLE_WUNLOCK(la); 540 return (0); 541 } 542 543 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 544 /* 545 * There is an arptab entry, but no ethernet address 546 * response yet. Add the mbuf to the list, dropping 547 * the oldest packet if we have exceeded the system 548 * setting. 549 */ 550 if (m != NULL) { 551 if (la->la_numheld >= V_arp_maxhold) { 552 if (la->la_hold != NULL) { 553 next = la->la_hold->m_nextpkt; 554 m_freem(la->la_hold); 555 la->la_hold = next; 556 la->la_numheld--; 557 ARPSTAT_INC(dropped); 558 } 559 } 560 if (la->la_hold != NULL) { 561 curr = la->la_hold; 562 while (curr->m_nextpkt != NULL) 563 curr = curr->m_nextpkt; 564 curr->m_nextpkt = m; 565 } else 566 la->la_hold = m; 567 la->la_numheld++; 568 } 569 /* 570 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 571 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 572 * if we have already sent arp_maxtries ARP requests. Retransmit the 573 * ARP request, but not faster than one request per second. 574 */ 575 if (la->la_asked < V_arp_maxtries) 576 error = EWOULDBLOCK; /* First request. */ 577 else 578 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 579 580 if (renew) { 581 int canceled, e; 582 583 LLE_ADDREF(la); 584 la->la_expire = time_uptime; 585 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 586 arptimer, la); 587 if (canceled) 588 LLE_REMREF(la); 589 la->la_asked++; 590 LLE_WUNLOCK(la); 591 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL); 592 /* 593 * Only overwrite 'error' in case of error; in case of success 594 * the proper return value was already set above. 595 */ 596 if (e != 0) 597 return (e); 598 return (error); 599 } 600 601 LLE_WUNLOCK(la); 602 return (error); 603 } 604 605 /* 606 * Lookups link header based on an IP address. 607 * On input: 608 * ifp is the interface we use 609 * is_gw != 0 if @dst represents gateway to some destination 610 * m is the mbuf. May be NULL if we don't have a packet. 611 * dst is the next hop, 612 * desten is the storage to put LL header. 613 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 614 * 615 * On success, full/partial link header and flags are filled in and 616 * the function returns 0. 617 * If the packet must be held pending resolution, we return EWOULDBLOCK 618 * On other errors, we return the corresponding error code. 619 * Note that m_freem() handles NULL. 620 */ 621 int 622 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 623 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 624 struct llentry **plle) 625 { 626 struct llentry *la = NULL; 627 628 NET_EPOCH_ASSERT(); 629 630 if (pflags != NULL) 631 *pflags = 0; 632 if (plle != NULL) 633 *plle = NULL; 634 635 if (m != NULL) { 636 if (m->m_flags & M_BCAST) { 637 /* broadcast */ 638 (void)memcpy(desten, 639 ifp->if_broadcastaddr, ifp->if_addrlen); 640 return (0); 641 } 642 if (m->m_flags & M_MCAST) { 643 /* multicast */ 644 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 645 return (0); 646 } 647 } 648 649 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 650 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 651 /* Entry found, let's copy lle info */ 652 bcopy(la->r_linkdata, desten, la->r_hdrlen); 653 if (pflags != NULL) 654 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 655 /* Notify the LLE handling code that the entry was used. */ 656 llentry_mark_used(la); 657 if (plle) { 658 LLE_ADDREF(la); 659 *plle = la; 660 LLE_WUNLOCK(la); 661 } 662 return (0); 663 } 664 if (plle && la) 665 LLE_WUNLOCK(la); 666 667 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 668 desten, pflags, plle)); 669 } 670 671 /* 672 * Common length and type checks are done here, 673 * then the protocol-specific routine is called. 674 */ 675 static void 676 arpintr(struct mbuf *m) 677 { 678 struct arphdr *ar; 679 struct ifnet *ifp; 680 char *layer; 681 int hlen; 682 683 ifp = m->m_pkthdr.rcvif; 684 685 if (m->m_len < sizeof(struct arphdr) && 686 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 687 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 688 if_name(ifp)); 689 return; 690 } 691 ar = mtod(m, struct arphdr *); 692 693 /* Check if length is sufficient */ 694 if (m->m_len < arphdr_len(ar)) { 695 m = m_pullup(m, arphdr_len(ar)); 696 if (m == NULL) { 697 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 698 if_name(ifp)); 699 return; 700 } 701 ar = mtod(m, struct arphdr *); 702 } 703 704 hlen = 0; 705 layer = ""; 706 switch (ntohs(ar->ar_hrd)) { 707 case ARPHRD_ETHER: 708 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 709 layer = "ethernet"; 710 break; 711 case ARPHRD_INFINIBAND: 712 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 713 layer = "infiniband"; 714 break; 715 case ARPHRD_IEEE1394: 716 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 717 layer = "firewire"; 718 719 /* 720 * Restrict too long hardware addresses. 721 * Currently we are capable of handling 20-byte 722 * addresses ( sizeof(lle->ll_addr) ) 723 */ 724 if (ar->ar_hln >= 20) 725 hlen = 16; 726 break; 727 default: 728 ARP_LOG(LOG_NOTICE, 729 "packet with unknown hardware format 0x%02d received on " 730 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 731 m_freem(m); 732 return; 733 } 734 735 if (hlen != 0 && hlen != ar->ar_hln) { 736 ARP_LOG(LOG_NOTICE, 737 "packet with invalid %s address length %d received on %s\n", 738 layer, ar->ar_hln, if_name(ifp)); 739 m_freem(m); 740 return; 741 } 742 743 ARPSTAT_INC(received); 744 switch (ntohs(ar->ar_pro)) { 745 #ifdef INET 746 case ETHERTYPE_IP: 747 in_arpinput(m); 748 return; 749 #endif 750 } 751 m_freem(m); 752 } 753 754 #ifdef INET 755 /* 756 * ARP for Internet protocols on 10 Mb/s Ethernet. 757 * Algorithm is that given in RFC 826. 758 * In addition, a sanity check is performed on the sender 759 * protocol address, to catch impersonators. 760 * We no longer handle negotiations for use of trailer protocol: 761 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 762 * along with IP replies if we wanted trailers sent to us, 763 * and also sent them in response to IP replies. 764 * This allowed either end to announce the desire to receive 765 * trailer packets. 766 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 767 * but formerly didn't normally send requests. 768 */ 769 static int log_arp_wrong_iface = 1; 770 static int log_arp_movements = 1; 771 static int log_arp_permanent_modify = 1; 772 static int allow_multicast = 0; 773 774 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 775 &log_arp_wrong_iface, 0, 776 "log arp packets arriving on the wrong interface"); 777 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 778 &log_arp_movements, 0, 779 "log arp replies from MACs different than the one in the cache"); 780 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 781 &log_arp_permanent_modify, 0, 782 "log arp replies from MACs different than the one in the permanent arp entry"); 783 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 784 &allow_multicast, 0, "accept multicast addresses"); 785 786 static void 787 in_arpinput(struct mbuf *m) 788 { 789 struct rm_priotracker in_ifa_tracker; 790 struct arphdr *ah; 791 struct ifnet *ifp = m->m_pkthdr.rcvif; 792 struct llentry *la = NULL, *la_tmp; 793 struct ifaddr *ifa; 794 struct in_ifaddr *ia; 795 struct sockaddr sa; 796 struct in_addr isaddr, itaddr, myaddr; 797 u_int8_t *enaddr = NULL; 798 int op; 799 int bridged = 0, is_bridge = 0; 800 int carped; 801 struct sockaddr_in sin; 802 struct sockaddr *dst; 803 struct nhop4_basic nh4; 804 uint8_t linkhdr[LLE_MAX_LINKHDR]; 805 struct route ro; 806 size_t linkhdrsize; 807 int lladdr_off; 808 int error; 809 char addrbuf[INET_ADDRSTRLEN]; 810 811 NET_EPOCH_ASSERT(); 812 813 sin.sin_len = sizeof(struct sockaddr_in); 814 sin.sin_family = AF_INET; 815 sin.sin_addr.s_addr = 0; 816 817 if (ifp->if_bridge) 818 bridged = 1; 819 if (ifp->if_type == IFT_BRIDGE) 820 is_bridge = 1; 821 822 /* 823 * We already have checked that mbuf contains enough contiguous data 824 * to hold entire arp message according to the arp header. 825 */ 826 ah = mtod(m, struct arphdr *); 827 828 /* 829 * ARP is only for IPv4 so we can reject packets with 830 * a protocol length not equal to an IPv4 address. 831 */ 832 if (ah->ar_pln != sizeof(struct in_addr)) { 833 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 834 sizeof(struct in_addr)); 835 goto drop; 836 } 837 838 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 839 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 840 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 841 goto drop; 842 } 843 844 op = ntohs(ah->ar_op); 845 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 846 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 847 848 if (op == ARPOP_REPLY) 849 ARPSTAT_INC(rxreplies); 850 851 /* 852 * For a bridge, we want to check the address irrespective 853 * of the receive interface. (This will change slightly 854 * when we have clusters of interfaces). 855 */ 856 IN_IFADDR_RLOCK(&in_ifa_tracker); 857 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 858 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 859 ia->ia_ifp == ifp) && 860 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 861 (ia->ia_ifa.ifa_carp == NULL || 862 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 863 ifa_ref(&ia->ia_ifa); 864 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 865 goto match; 866 } 867 } 868 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 869 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 870 ia->ia_ifp == ifp) && 871 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 872 ifa_ref(&ia->ia_ifa); 873 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 874 goto match; 875 } 876 877 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 878 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 879 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 880 addr == ia->ia_addr.sin_addr.s_addr) 881 /* 882 * Check the case when bridge shares its MAC address with 883 * some of its children, so packets are claimed by bridge 884 * itself (bridge_input() does it first), but they are really 885 * meant to be destined to the bridge member. 886 */ 887 if (is_bridge) { 888 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 889 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 890 ifa_ref(&ia->ia_ifa); 891 ifp = ia->ia_ifp; 892 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 893 goto match; 894 } 895 } 896 } 897 #undef BDG_MEMBER_MATCHES_ARP 898 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 899 900 /* 901 * No match, use the first inet address on the receive interface 902 * as a dummy address for the rest of the function. 903 */ 904 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 905 if (ifa->ifa_addr->sa_family == AF_INET && 906 (ifa->ifa_carp == NULL || 907 (*carp_iamatch_p)(ifa, &enaddr))) { 908 ia = ifatoia(ifa); 909 ifa_ref(ifa); 910 goto match; 911 } 912 913 /* 914 * If bridging, fall back to using any inet address. 915 */ 916 IN_IFADDR_RLOCK(&in_ifa_tracker); 917 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 918 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 919 goto drop; 920 } 921 ifa_ref(&ia->ia_ifa); 922 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 923 match: 924 if (!enaddr) 925 enaddr = (u_int8_t *)IF_LLADDR(ifp); 926 carped = (ia->ia_ifa.ifa_carp != NULL); 927 myaddr = ia->ia_addr.sin_addr; 928 ifa_free(&ia->ia_ifa); 929 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 930 goto drop; /* it's from me, ignore it. */ 931 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 932 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 933 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 934 goto drop; 935 } 936 937 if (ifp->if_addrlen != ah->ar_hln) { 938 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 939 "i/f %d (ignored)\n", ifp->if_addrlen, 940 (u_char *) ar_sha(ah), ":", ah->ar_hln, 941 ifp->if_addrlen); 942 goto drop; 943 } 944 945 /* 946 * Warn if another host is using the same IP address, but only if the 947 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 948 * case we suppress the warning to avoid false positive complaints of 949 * potential misconfiguration. 950 */ 951 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 952 myaddr.s_addr != 0) { 953 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 954 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 955 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 956 itaddr = myaddr; 957 ARPSTAT_INC(dupips); 958 goto reply; 959 } 960 if (ifp->if_flags & IFF_STATICARP) 961 goto reply; 962 963 bzero(&sin, sizeof(sin)); 964 sin.sin_len = sizeof(struct sockaddr_in); 965 sin.sin_family = AF_INET; 966 sin.sin_addr = isaddr; 967 dst = (struct sockaddr *)&sin; 968 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 969 if (la != NULL) 970 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 971 else if (itaddr.s_addr == myaddr.s_addr) { 972 /* 973 * Request/reply to our address, but no lle exists yet. 974 * Calculate full link prepend to use in lle. 975 */ 976 linkhdrsize = sizeof(linkhdr); 977 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 978 &linkhdrsize, &lladdr_off) != 0) 979 goto reply; 980 981 /* Allocate new entry */ 982 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 983 if (la == NULL) { 984 985 /* 986 * lle creation may fail if source address belongs 987 * to non-directly connected subnet. However, we 988 * will try to answer the request instead of dropping 989 * frame. 990 */ 991 goto reply; 992 } 993 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 994 lladdr_off); 995 996 IF_AFDATA_WLOCK(ifp); 997 LLE_WLOCK(la); 998 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 999 1000 /* 1001 * Check if lle still does not exists. 1002 * If it does, that means that we either 1003 * 1) have configured it explicitly, via 1004 * 1a) 'arp -s' static entry or 1005 * 1b) interface address static record 1006 * or 1007 * 2) it was the result of sending first packet to-host 1008 * or 1009 * 3) it was another arp reply packet we handled in 1010 * different thread. 1011 * 1012 * In all cases except 3) we definitely need to prefer 1013 * existing lle. For the sake of simplicity, prefer any 1014 * existing lle over newly-create one. 1015 */ 1016 if (la_tmp == NULL) 1017 lltable_link_entry(LLTABLE(ifp), la); 1018 IF_AFDATA_WUNLOCK(ifp); 1019 1020 if (la_tmp == NULL) { 1021 arp_mark_lle_reachable(la); 1022 LLE_WUNLOCK(la); 1023 } else { 1024 /* Free newly-create entry and handle packet */ 1025 lltable_free_entry(LLTABLE(ifp), la); 1026 la = la_tmp; 1027 la_tmp = NULL; 1028 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1029 /* arp_check_update_lle() returns @la unlocked */ 1030 } 1031 la = NULL; 1032 } 1033 reply: 1034 if (op != ARPOP_REQUEST) 1035 goto drop; 1036 ARPSTAT_INC(rxrequests); 1037 1038 if (itaddr.s_addr == myaddr.s_addr) { 1039 /* Shortcut.. the receiving interface is the target. */ 1040 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1041 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1042 } else { 1043 struct llentry *lle = NULL; 1044 1045 sin.sin_addr = itaddr; 1046 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1047 1048 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1049 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1050 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1051 LLE_RUNLOCK(lle); 1052 } else { 1053 1054 if (lle != NULL) 1055 LLE_RUNLOCK(lle); 1056 1057 if (!V_arp_proxyall) 1058 goto drop; 1059 1060 /* XXX MRT use table 0 for arp reply */ 1061 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1062 goto drop; 1063 1064 /* 1065 * Don't send proxies for nodes on the same interface 1066 * as this one came out of, or we'll get into a fight 1067 * over who claims what Ether address. 1068 */ 1069 if (nh4.nh_ifp == ifp) 1070 goto drop; 1071 1072 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1073 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1074 1075 /* 1076 * Also check that the node which sent the ARP packet 1077 * is on the interface we expect it to be on. This 1078 * avoids ARP chaos if an interface is connected to the 1079 * wrong network. 1080 */ 1081 1082 /* XXX MRT use table 0 for arp checks */ 1083 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1084 goto drop; 1085 if (nh4.nh_ifp != ifp) { 1086 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1087 " from %s via %s\n", 1088 inet_ntoa_r(isaddr, addrbuf), 1089 ifp->if_xname); 1090 goto drop; 1091 } 1092 1093 #ifdef DEBUG_PROXY 1094 printf("arp: proxying for %s\n", 1095 inet_ntoa_r(itaddr, addrbuf)); 1096 #endif 1097 } 1098 } 1099 1100 if (itaddr.s_addr == myaddr.s_addr && 1101 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1102 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1103 #ifdef DEBUG_LINKLOCAL 1104 printf("arp: sending reply for link-local addr %s\n", 1105 inet_ntoa_r(itaddr, addrbuf)); 1106 #endif 1107 m->m_flags |= M_BCAST; 1108 m->m_flags &= ~M_MCAST; 1109 } else { 1110 /* default behaviour; never reply by broadcast. */ 1111 m->m_flags &= ~(M_BCAST|M_MCAST); 1112 } 1113 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1114 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1115 ah->ar_op = htons(ARPOP_REPLY); 1116 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1117 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1118 m->m_pkthdr.len = m->m_len; 1119 m->m_pkthdr.rcvif = NULL; 1120 sa.sa_family = AF_ARP; 1121 sa.sa_len = 2; 1122 1123 /* Calculate link header for sending frame */ 1124 bzero(&ro, sizeof(ro)); 1125 linkhdrsize = sizeof(linkhdr); 1126 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1127 1128 /* 1129 * arp_fillheader() may fail due to lack of support inside encap request 1130 * routing. This is not necessary an error, AF_ARP can/should be handled 1131 * by if_output(). 1132 */ 1133 if (error != 0 && error != EAFNOSUPPORT) { 1134 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1135 if_name(ifp), error); 1136 return; 1137 } 1138 1139 ro.ro_prepend = linkhdr; 1140 ro.ro_plen = linkhdrsize; 1141 ro.ro_flags = 0; 1142 1143 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1144 (*ifp->if_output)(ifp, m, &sa, &ro); 1145 ARPSTAT_INC(txreplies); 1146 return; 1147 1148 drop: 1149 m_freem(m); 1150 } 1151 #endif 1152 1153 /* 1154 * Checks received arp data against existing @la. 1155 * Updates lle state/performs notification if necessary. 1156 */ 1157 static void 1158 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1159 int bridged, struct llentry *la) 1160 { 1161 struct sockaddr sa; 1162 struct mbuf *m_hold, *m_hold_next; 1163 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1164 size_t linkhdrsize; 1165 int lladdr_off; 1166 char addrbuf[INET_ADDRSTRLEN]; 1167 1168 LLE_WLOCK_ASSERT(la); 1169 1170 /* the following is not an error when doing bridging */ 1171 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1172 if (log_arp_wrong_iface) 1173 ARP_LOG(LOG_WARNING, "%s is on %s " 1174 "but got reply from %*D on %s\n", 1175 inet_ntoa_r(isaddr, addrbuf), 1176 la->lle_tbl->llt_ifp->if_xname, 1177 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1178 ifp->if_xname); 1179 LLE_WUNLOCK(la); 1180 return; 1181 } 1182 if ((la->la_flags & LLE_VALID) && 1183 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1184 if (la->la_flags & LLE_STATIC) { 1185 LLE_WUNLOCK(la); 1186 if (log_arp_permanent_modify) 1187 ARP_LOG(LOG_ERR, 1188 "%*D attempts to modify " 1189 "permanent entry for %s on %s\n", 1190 ifp->if_addrlen, 1191 (u_char *)ar_sha(ah), ":", 1192 inet_ntoa_r(isaddr, addrbuf), 1193 ifp->if_xname); 1194 return; 1195 } 1196 if (log_arp_movements) { 1197 ARP_LOG(LOG_INFO, "%s moved from %*D " 1198 "to %*D on %s\n", 1199 inet_ntoa_r(isaddr, addrbuf), 1200 ifp->if_addrlen, 1201 (u_char *)la->ll_addr, ":", 1202 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1203 ifp->if_xname); 1204 } 1205 } 1206 1207 /* Calculate full link prepend to use in lle */ 1208 linkhdrsize = sizeof(linkhdr); 1209 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1210 &linkhdrsize, &lladdr_off) != 0) 1211 return; 1212 1213 /* Check if something has changed */ 1214 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1215 (la->la_flags & LLE_VALID) == 0) { 1216 /* Try to perform LLE update */ 1217 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1218 lladdr_off) == 0) 1219 return; 1220 1221 /* Clear fast path feedback request if set */ 1222 la->r_skip_req = 0; 1223 } 1224 1225 arp_mark_lle_reachable(la); 1226 1227 /* 1228 * The packets are all freed within the call to the output 1229 * routine. 1230 * 1231 * NB: The lock MUST be released before the call to the 1232 * output routine. 1233 */ 1234 if (la->la_hold != NULL) { 1235 m_hold = la->la_hold; 1236 la->la_hold = NULL; 1237 la->la_numheld = 0; 1238 lltable_fill_sa_entry(la, &sa); 1239 LLE_WUNLOCK(la); 1240 for (; m_hold != NULL; m_hold = m_hold_next) { 1241 m_hold_next = m_hold->m_nextpkt; 1242 m_hold->m_nextpkt = NULL; 1243 /* Avoid confusing lower layers. */ 1244 m_clrprotoflags(m_hold); 1245 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1246 } 1247 } else 1248 LLE_WUNLOCK(la); 1249 } 1250 1251 static void 1252 arp_mark_lle_reachable(struct llentry *la) 1253 { 1254 int canceled, wtime; 1255 1256 LLE_WLOCK_ASSERT(la); 1257 1258 la->ln_state = ARP_LLINFO_REACHABLE; 1259 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1260 1261 if (!(la->la_flags & LLE_STATIC)) { 1262 LLE_ADDREF(la); 1263 la->la_expire = time_uptime + V_arpt_keep; 1264 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1265 if (wtime < 0) 1266 wtime = V_arpt_keep; 1267 canceled = callout_reset(&la->lle_timer, 1268 hz * wtime, arptimer, la); 1269 if (canceled) 1270 LLE_REMREF(la); 1271 } 1272 la->la_asked = 0; 1273 la->la_preempt = V_arp_maxtries; 1274 } 1275 1276 /* 1277 * Add permanent link-layer record for given interface address. 1278 */ 1279 static __noinline void 1280 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1281 { 1282 struct llentry *lle, *lle_tmp; 1283 1284 /* 1285 * Interface address LLE record is considered static 1286 * because kernel code relies on LLE_STATIC flag to check 1287 * if these entries can be rewriten by arp updates. 1288 */ 1289 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1290 if (lle == NULL) { 1291 log(LOG_INFO, "arp_ifinit: cannot create arp " 1292 "entry for interface address\n"); 1293 return; 1294 } 1295 1296 IF_AFDATA_WLOCK(ifp); 1297 LLE_WLOCK(lle); 1298 /* Unlink any entry if exists */ 1299 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1300 if (lle_tmp != NULL) 1301 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1302 1303 lltable_link_entry(LLTABLE(ifp), lle); 1304 IF_AFDATA_WUNLOCK(ifp); 1305 1306 if (lle_tmp != NULL) 1307 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1308 1309 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1310 LLE_WUNLOCK(lle); 1311 if (lle_tmp != NULL) 1312 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1313 } 1314 1315 /* 1316 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1317 * of valid values. 1318 */ 1319 static int 1320 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1321 { 1322 int error; 1323 int rexmit_count = *(int *)arg1; 1324 1325 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1326 1327 /* Enforce limits on any new value that may have been set. */ 1328 if (!error && req->newptr) { 1329 /* A new value was set. */ 1330 if (rexmit_count < 0) { 1331 rexmit_count = 0; 1332 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1333 rexmit_count = MAX_GARP_RETRANSMITS; 1334 } 1335 *(int *)arg1 = rexmit_count; 1336 } 1337 1338 return (error); 1339 } 1340 1341 /* 1342 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1343 * retransmit it again. A pending callout owns a reference to the ifa. 1344 */ 1345 static void 1346 garp_rexmit(void *arg) 1347 { 1348 struct in_ifaddr *ia = arg; 1349 1350 if (callout_pending(&ia->ia_garp_timer) || 1351 !callout_active(&ia->ia_garp_timer)) { 1352 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1353 ifa_free(&ia->ia_ifa); 1354 return; 1355 } 1356 1357 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1358 1359 /* 1360 * Drop lock while the ARP request is generated. 1361 */ 1362 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1363 1364 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1365 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1366 1367 /* 1368 * Increment the count of retransmissions. If the count has reached the 1369 * maximum value, stop sending the GARP packets. Otherwise, schedule 1370 * the callout to retransmit another GARP packet. 1371 */ 1372 ++ia->ia_garp_count; 1373 if (ia->ia_garp_count >= garp_rexmit_count) { 1374 ifa_free(&ia->ia_ifa); 1375 } else { 1376 int rescheduled; 1377 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1378 rescheduled = callout_reset(&ia->ia_garp_timer, 1379 (1 << ia->ia_garp_count) * hz, 1380 garp_rexmit, ia); 1381 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1382 if (rescheduled) { 1383 ifa_free(&ia->ia_ifa); 1384 } 1385 } 1386 1387 CURVNET_RESTORE(); 1388 } 1389 1390 /* 1391 * Start the GARP retransmit timer. 1392 * 1393 * A single GARP is always transmitted when an IPv4 address is added 1394 * to an interface and that is usually sufficient. However, in some 1395 * circumstances, such as when a shared address is passed between 1396 * cluster nodes, this single GARP may occasionally be dropped or 1397 * lost. This can lead to neighbors on the network link working with a 1398 * stale ARP cache and sending packets destined for that address to 1399 * the node that previously owned the address, which may not respond. 1400 * 1401 * To avoid this situation, GARP retransmits can be enabled by setting 1402 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1403 * than zero. The setting represents the maximum number of 1404 * retransmissions. The interval between retransmissions is calculated 1405 * using an exponential backoff algorithm, doubling each time, so the 1406 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1407 */ 1408 static void 1409 garp_timer_start(struct ifaddr *ifa) 1410 { 1411 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1412 1413 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1414 ia->ia_garp_count = 0; 1415 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1416 garp_rexmit, ia) == 0) { 1417 ifa_ref(ifa); 1418 } 1419 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1420 } 1421 1422 void 1423 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1424 { 1425 struct epoch_tracker et; 1426 const struct sockaddr_in *dst_in; 1427 const struct sockaddr *dst; 1428 1429 if (ifa->ifa_carp != NULL) 1430 return; 1431 1432 dst = ifa->ifa_addr; 1433 dst_in = (const struct sockaddr_in *)dst; 1434 1435 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1436 return; 1437 NET_EPOCH_ENTER(et); 1438 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1439 NET_EPOCH_EXIT(et); 1440 if (garp_rexmit_count > 0) { 1441 garp_timer_start(ifa); 1442 } 1443 1444 arp_add_ifa_lle(ifp, dst); 1445 } 1446 1447 void 1448 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1449 { 1450 1451 if (ntohl(addr.s_addr) != INADDR_ANY) 1452 arprequest(ifp, &addr, &addr, enaddr); 1453 } 1454 1455 /* 1456 * Sends gratuitous ARPs for each ifaddr to notify other 1457 * nodes about the address change. 1458 */ 1459 static __noinline void 1460 arp_handle_ifllchange(struct ifnet *ifp) 1461 { 1462 struct ifaddr *ifa; 1463 1464 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1465 if (ifa->ifa_addr->sa_family == AF_INET) 1466 arp_ifinit(ifp, ifa); 1467 } 1468 } 1469 1470 /* 1471 * A handler for interface link layer address change event. 1472 */ 1473 static void 1474 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1475 { 1476 1477 lltable_update_ifaddr(LLTABLE(ifp)); 1478 1479 if ((ifp->if_flags & IFF_UP) != 0) 1480 arp_handle_ifllchange(ifp); 1481 } 1482 1483 static void 1484 vnet_arp_init(void) 1485 { 1486 1487 if (IS_DEFAULT_VNET(curvnet)) { 1488 netisr_register(&arp_nh); 1489 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1490 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1491 } 1492 #ifdef VIMAGE 1493 else 1494 netisr_register_vnet(&arp_nh); 1495 #endif 1496 } 1497 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1498 vnet_arp_init, 0); 1499 1500 #ifdef VIMAGE 1501 /* 1502 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1503 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1504 */ 1505 static void 1506 vnet_arp_destroy(__unused void *arg) 1507 { 1508 1509 netisr_unregister_vnet(&arp_nh); 1510 } 1511 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1512 vnet_arp_destroy, NULL); 1513 #endif 1514