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 in_addr dst; 262 dst = lle->r_l3addr.addr4; 263 lle->la_preempt--; 264 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 265 LLE_WUNLOCK(lle); 266 arprequest(ifp, NULL, &dst, NULL); 267 CURVNET_RESTORE(); 268 return; 269 } 270 /* Nothing happened. Reschedule if not too late */ 271 if (lle->la_expire > time_uptime) { 272 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 273 LLE_WUNLOCK(lle); 274 CURVNET_RESTORE(); 275 return; 276 } 277 break; 278 case ARP_LLINFO_INCOMPLETE: 279 case ARP_LLINFO_DELETED: 280 break; 281 } 282 283 if ((lle->la_flags & LLE_DELETED) == 0) { 284 int evt; 285 286 if (lle->la_flags & LLE_VALID) 287 evt = LLENTRY_EXPIRED; 288 else 289 evt = LLENTRY_TIMEDOUT; 290 EVENTHANDLER_INVOKE(lle_event, lle, evt); 291 } 292 293 callout_stop(&lle->lle_timer); 294 295 /* XXX: LOR avoidance. We still have ref on lle. */ 296 LLE_WUNLOCK(lle); 297 IF_AFDATA_LOCK(ifp); 298 LLE_WLOCK(lle); 299 300 /* Guard against race with other llentry_free(). */ 301 if (lle->la_flags & LLE_LINKED) { 302 LLE_REMREF(lle); 303 lltable_unlink_entry(lle->lle_tbl, lle); 304 } 305 IF_AFDATA_UNLOCK(ifp); 306 307 size_t pkts_dropped = llentry_free(lle); 308 309 ARPSTAT_ADD(dropped, pkts_dropped); 310 ARPSTAT_INC(timeouts); 311 312 CURVNET_RESTORE(); 313 } 314 315 /* 316 * Stores link-layer header for @ifp in format suitable for if_output() 317 * into buffer @buf. Resulting header length is stored in @bufsize. 318 * 319 * Returns 0 on success. 320 */ 321 static int 322 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 323 size_t *bufsize) 324 { 325 struct if_encap_req ereq; 326 int error; 327 328 bzero(buf, *bufsize); 329 bzero(&ereq, sizeof(ereq)); 330 ereq.buf = buf; 331 ereq.bufsize = *bufsize; 332 ereq.rtype = IFENCAP_LL; 333 ereq.family = AF_ARP; 334 ereq.lladdr = ar_tha(ah); 335 ereq.hdata = (u_char *)ah; 336 if (bcast) 337 ereq.flags = IFENCAP_FLAG_BROADCAST; 338 error = ifp->if_requestencap(ifp, &ereq); 339 if (error == 0) 340 *bufsize = ereq.bufsize; 341 342 return (error); 343 } 344 345 346 /* 347 * Broadcast an ARP request. Caller specifies: 348 * - arp header source ip address 349 * - arp header target ip address 350 * - arp header source ethernet address 351 */ 352 static int 353 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip, 354 const struct in_addr *tip, u_char *enaddr) 355 { 356 struct mbuf *m; 357 struct arphdr *ah; 358 struct sockaddr sa; 359 u_char *carpaddr = NULL; 360 uint8_t linkhdr[LLE_MAX_LINKHDR]; 361 size_t linkhdrsize; 362 struct route ro; 363 int error; 364 365 if (sip == NULL) { 366 /* 367 * The caller did not supply a source address, try to find 368 * a compatible one among those assigned to this interface. 369 */ 370 struct epoch_tracker et; 371 struct ifaddr *ifa; 372 373 NET_EPOCH_ENTER(et); 374 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 375 if (ifa->ifa_addr->sa_family != AF_INET) 376 continue; 377 378 if (ifa->ifa_carp) { 379 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 380 continue; 381 sip = &IA_SIN(ifa)->sin_addr; 382 } else { 383 carpaddr = NULL; 384 sip = &IA_SIN(ifa)->sin_addr; 385 } 386 387 if (0 == ((sip->s_addr ^ tip->s_addr) & 388 IA_MASKSIN(ifa)->sin_addr.s_addr)) 389 break; /* found it. */ 390 } 391 NET_EPOCH_EXIT(et); 392 if (sip == NULL) { 393 printf("%s: cannot find matching address\n", __func__); 394 return (EADDRNOTAVAIL); 395 } 396 } 397 if (enaddr == NULL) 398 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 399 400 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 401 return (ENOMEM); 402 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 403 2 * ifp->if_addrlen; 404 m->m_pkthdr.len = m->m_len; 405 M_ALIGN(m, m->m_len); 406 ah = mtod(m, struct arphdr *); 407 bzero((caddr_t)ah, m->m_len); 408 #ifdef MAC 409 mac_netinet_arp_send(ifp, m); 410 #endif 411 ah->ar_pro = htons(ETHERTYPE_IP); 412 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 413 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 414 ah->ar_op = htons(ARPOP_REQUEST); 415 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 416 bcopy(sip, ar_spa(ah), ah->ar_pln); 417 bcopy(tip, ar_tpa(ah), ah->ar_pln); 418 sa.sa_family = AF_ARP; 419 sa.sa_len = 2; 420 421 /* Calculate link header for sending frame */ 422 bzero(&ro, sizeof(ro)); 423 linkhdrsize = sizeof(linkhdr); 424 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 425 if (error != 0 && error != EAFNOSUPPORT) { 426 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 427 if_name(ifp), error); 428 return (error); 429 } 430 431 ro.ro_prepend = linkhdr; 432 ro.ro_plen = linkhdrsize; 433 ro.ro_flags = 0; 434 435 m->m_flags |= M_BCAST; 436 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 437 error = (*ifp->if_output)(ifp, m, &sa, &ro); 438 ARPSTAT_INC(txrequests); 439 if (error) { 440 ARPSTAT_INC(txerrors); 441 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n", 442 if_name(ifp), error); 443 } 444 return (error); 445 } 446 447 void 448 arprequest(struct ifnet *ifp, const struct in_addr *sip, 449 const struct in_addr *tip, u_char *enaddr) 450 { 451 452 (void) arprequest_internal(ifp, sip, tip, enaddr); 453 } 454 455 /* 456 * Resolve an IP address into an ethernet address - heavy version. 457 * Used internally by arpresolve(). 458 * We have already checked that we can't use an existing lle without 459 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 460 * 461 * On success, desten and pflags are filled in and the function returns 0; 462 * If the packet must be held pending resolution, we return EWOULDBLOCK 463 * On other errors, we return the corresponding error code. 464 * Note that m_freem() handles NULL. 465 */ 466 static int 467 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 468 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 469 struct llentry **plle) 470 { 471 struct llentry *la = NULL, *la_tmp; 472 struct mbuf *curr = NULL; 473 struct mbuf *next = NULL; 474 int error, renew; 475 char *lladdr; 476 int ll_len; 477 478 if (pflags != NULL) 479 *pflags = 0; 480 if (plle != NULL) 481 *plle = NULL; 482 483 if ((flags & LLE_CREATE) == 0) { 484 struct epoch_tracker et; 485 486 NET_EPOCH_ENTER(et); 487 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 488 NET_EPOCH_EXIT(et); 489 } 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 epoch_tracker et; 627 struct llentry *la = NULL; 628 629 if (pflags != NULL) 630 *pflags = 0; 631 if (plle != NULL) 632 *plle = NULL; 633 634 if (m != NULL) { 635 if (m->m_flags & M_BCAST) { 636 /* broadcast */ 637 (void)memcpy(desten, 638 ifp->if_broadcastaddr, ifp->if_addrlen); 639 return (0); 640 } 641 if (m->m_flags & M_MCAST) { 642 /* multicast */ 643 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 644 return (0); 645 } 646 } 647 648 NET_EPOCH_ENTER(et); 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 NET_EPOCH_EXIT(et); 663 return (0); 664 } 665 if (plle && la) 666 LLE_WUNLOCK(la); 667 NET_EPOCH_EXIT(et); 668 669 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 670 desten, pflags, plle)); 671 } 672 673 /* 674 * Common length and type checks are done here, 675 * then the protocol-specific routine is called. 676 */ 677 static void 678 arpintr(struct mbuf *m) 679 { 680 struct arphdr *ar; 681 struct ifnet *ifp; 682 char *layer; 683 int hlen; 684 685 ifp = m->m_pkthdr.rcvif; 686 687 if (m->m_len < sizeof(struct arphdr) && 688 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 689 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 690 if_name(ifp)); 691 return; 692 } 693 ar = mtod(m, struct arphdr *); 694 695 /* Check if length is sufficient */ 696 if (m->m_len < arphdr_len(ar)) { 697 m = m_pullup(m, arphdr_len(ar)); 698 if (m == NULL) { 699 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 700 if_name(ifp)); 701 return; 702 } 703 ar = mtod(m, struct arphdr *); 704 } 705 706 hlen = 0; 707 layer = ""; 708 switch (ntohs(ar->ar_hrd)) { 709 case ARPHRD_ETHER: 710 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 711 layer = "ethernet"; 712 break; 713 case ARPHRD_INFINIBAND: 714 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 715 layer = "infiniband"; 716 break; 717 case ARPHRD_IEEE1394: 718 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 719 layer = "firewire"; 720 721 /* 722 * Restrict too long hardware addresses. 723 * Currently we are capable of handling 20-byte 724 * addresses ( sizeof(lle->ll_addr) ) 725 */ 726 if (ar->ar_hln >= 20) 727 hlen = 16; 728 break; 729 default: 730 ARP_LOG(LOG_NOTICE, 731 "packet with unknown hardware format 0x%02d received on " 732 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 733 m_freem(m); 734 return; 735 } 736 737 if (hlen != 0 && hlen != ar->ar_hln) { 738 ARP_LOG(LOG_NOTICE, 739 "packet with invalid %s address length %d received on %s\n", 740 layer, ar->ar_hln, if_name(ifp)); 741 m_freem(m); 742 return; 743 } 744 745 ARPSTAT_INC(received); 746 switch (ntohs(ar->ar_pro)) { 747 #ifdef INET 748 case ETHERTYPE_IP: 749 in_arpinput(m); 750 return; 751 #endif 752 } 753 m_freem(m); 754 } 755 756 #ifdef INET 757 /* 758 * ARP for Internet protocols on 10 Mb/s Ethernet. 759 * Algorithm is that given in RFC 826. 760 * In addition, a sanity check is performed on the sender 761 * protocol address, to catch impersonators. 762 * We no longer handle negotiations for use of trailer protocol: 763 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 764 * along with IP replies if we wanted trailers sent to us, 765 * and also sent them in response to IP replies. 766 * This allowed either end to announce the desire to receive 767 * trailer packets. 768 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 769 * but formerly didn't normally send requests. 770 */ 771 static int log_arp_wrong_iface = 1; 772 static int log_arp_movements = 1; 773 static int log_arp_permanent_modify = 1; 774 static int allow_multicast = 0; 775 776 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 777 &log_arp_wrong_iface, 0, 778 "log arp packets arriving on the wrong interface"); 779 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 780 &log_arp_movements, 0, 781 "log arp replies from MACs different than the one in the cache"); 782 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 783 &log_arp_permanent_modify, 0, 784 "log arp replies from MACs different than the one in the permanent arp entry"); 785 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 786 &allow_multicast, 0, "accept multicast addresses"); 787 788 static void 789 in_arpinput(struct mbuf *m) 790 { 791 struct rm_priotracker in_ifa_tracker; 792 struct arphdr *ah; 793 struct ifnet *ifp = m->m_pkthdr.rcvif; 794 struct llentry *la = NULL, *la_tmp; 795 struct ifaddr *ifa; 796 struct in_ifaddr *ia; 797 struct sockaddr sa; 798 struct in_addr isaddr, itaddr, myaddr; 799 u_int8_t *enaddr = NULL; 800 int op; 801 int bridged = 0, is_bridge = 0; 802 int carped; 803 struct sockaddr_in sin; 804 struct sockaddr *dst; 805 struct nhop4_basic nh4; 806 uint8_t linkhdr[LLE_MAX_LINKHDR]; 807 struct route ro; 808 size_t linkhdrsize; 809 int lladdr_off; 810 int error; 811 char addrbuf[INET_ADDRSTRLEN]; 812 struct epoch_tracker et; 813 814 sin.sin_len = sizeof(struct sockaddr_in); 815 sin.sin_family = AF_INET; 816 sin.sin_addr.s_addr = 0; 817 818 if (ifp->if_bridge) 819 bridged = 1; 820 if (ifp->if_type == IFT_BRIDGE) 821 is_bridge = 1; 822 823 /* 824 * We already have checked that mbuf contains enough contiguous data 825 * to hold entire arp message according to the arp header. 826 */ 827 ah = mtod(m, struct arphdr *); 828 829 /* 830 * ARP is only for IPv4 so we can reject packets with 831 * a protocol length not equal to an IPv4 address. 832 */ 833 if (ah->ar_pln != sizeof(struct in_addr)) { 834 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 835 sizeof(struct in_addr)); 836 goto drop; 837 } 838 839 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 840 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 841 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 842 goto drop; 843 } 844 845 op = ntohs(ah->ar_op); 846 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 847 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 848 849 if (op == ARPOP_REPLY) 850 ARPSTAT_INC(rxreplies); 851 852 /* 853 * For a bridge, we want to check the address irrespective 854 * of the receive interface. (This will change slightly 855 * when we have clusters of interfaces). 856 */ 857 IN_IFADDR_RLOCK(&in_ifa_tracker); 858 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 859 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 860 ia->ia_ifp == ifp) && 861 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 862 (ia->ia_ifa.ifa_carp == NULL || 863 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 864 ifa_ref(&ia->ia_ifa); 865 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 866 goto match; 867 } 868 } 869 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 870 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 871 ia->ia_ifp == ifp) && 872 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 873 ifa_ref(&ia->ia_ifa); 874 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 875 goto match; 876 } 877 878 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 879 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 880 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 881 addr == ia->ia_addr.sin_addr.s_addr) 882 /* 883 * Check the case when bridge shares its MAC address with 884 * some of its children, so packets are claimed by bridge 885 * itself (bridge_input() does it first), but they are really 886 * meant to be destined to the bridge member. 887 */ 888 if (is_bridge) { 889 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 890 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 891 ifa_ref(&ia->ia_ifa); 892 ifp = ia->ia_ifp; 893 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 894 goto match; 895 } 896 } 897 } 898 #undef BDG_MEMBER_MATCHES_ARP 899 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 900 901 /* 902 * No match, use the first inet address on the receive interface 903 * as a dummy address for the rest of the function. 904 */ 905 NET_EPOCH_ENTER(et); 906 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 907 if (ifa->ifa_addr->sa_family == AF_INET && 908 (ifa->ifa_carp == NULL || 909 (*carp_iamatch_p)(ifa, &enaddr))) { 910 ia = ifatoia(ifa); 911 ifa_ref(ifa); 912 NET_EPOCH_EXIT(et); 913 goto match; 914 } 915 NET_EPOCH_EXIT(et); 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 NET_EPOCH_ENTER(et); 973 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 974 NET_EPOCH_EXIT(et); 975 if (la != NULL) 976 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 977 else if (itaddr.s_addr == myaddr.s_addr) { 978 /* 979 * Request/reply to our address, but no lle exists yet. 980 * Calculate full link prepend to use in lle. 981 */ 982 linkhdrsize = sizeof(linkhdr); 983 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 984 &linkhdrsize, &lladdr_off) != 0) 985 goto reply; 986 987 /* Allocate new entry */ 988 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 989 if (la == NULL) { 990 991 /* 992 * lle creation may fail if source address belongs 993 * to non-directly connected subnet. However, we 994 * will try to answer the request instead of dropping 995 * frame. 996 */ 997 goto reply; 998 } 999 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1000 lladdr_off); 1001 1002 IF_AFDATA_WLOCK(ifp); 1003 LLE_WLOCK(la); 1004 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1005 1006 /* 1007 * Check if lle still does not exists. 1008 * If it does, that means that we either 1009 * 1) have configured it explicitly, via 1010 * 1a) 'arp -s' static entry or 1011 * 1b) interface address static record 1012 * or 1013 * 2) it was the result of sending first packet to-host 1014 * or 1015 * 3) it was another arp reply packet we handled in 1016 * different thread. 1017 * 1018 * In all cases except 3) we definitely need to prefer 1019 * existing lle. For the sake of simplicity, prefer any 1020 * existing lle over newly-create one. 1021 */ 1022 if (la_tmp == NULL) 1023 lltable_link_entry(LLTABLE(ifp), la); 1024 IF_AFDATA_WUNLOCK(ifp); 1025 1026 if (la_tmp == NULL) { 1027 arp_mark_lle_reachable(la); 1028 LLE_WUNLOCK(la); 1029 } else { 1030 /* Free newly-create entry and handle packet */ 1031 lltable_free_entry(LLTABLE(ifp), la); 1032 la = la_tmp; 1033 la_tmp = NULL; 1034 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1035 /* arp_check_update_lle() returns @la unlocked */ 1036 } 1037 la = NULL; 1038 } 1039 reply: 1040 if (op != ARPOP_REQUEST) 1041 goto drop; 1042 ARPSTAT_INC(rxrequests); 1043 1044 if (itaddr.s_addr == myaddr.s_addr) { 1045 /* Shortcut.. the receiving interface is the target. */ 1046 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1047 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1048 } else { 1049 struct llentry *lle = NULL; 1050 1051 sin.sin_addr = itaddr; 1052 NET_EPOCH_ENTER(et); 1053 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1054 NET_EPOCH_EXIT(et); 1055 1056 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1057 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1058 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1059 LLE_RUNLOCK(lle); 1060 } else { 1061 1062 if (lle != NULL) 1063 LLE_RUNLOCK(lle); 1064 1065 if (!V_arp_proxyall) 1066 goto drop; 1067 1068 /* XXX MRT use table 0 for arp reply */ 1069 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1070 goto drop; 1071 1072 /* 1073 * Don't send proxies for nodes on the same interface 1074 * as this one came out of, or we'll get into a fight 1075 * over who claims what Ether address. 1076 */ 1077 if (nh4.nh_ifp == ifp) 1078 goto drop; 1079 1080 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1081 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1082 1083 /* 1084 * Also check that the node which sent the ARP packet 1085 * is on the interface we expect it to be on. This 1086 * avoids ARP chaos if an interface is connected to the 1087 * wrong network. 1088 */ 1089 1090 /* XXX MRT use table 0 for arp checks */ 1091 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1092 goto drop; 1093 if (nh4.nh_ifp != ifp) { 1094 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1095 " from %s via %s\n", 1096 inet_ntoa_r(isaddr, addrbuf), 1097 ifp->if_xname); 1098 goto drop; 1099 } 1100 1101 #ifdef DEBUG_PROXY 1102 printf("arp: proxying for %s\n", 1103 inet_ntoa_r(itaddr, addrbuf)); 1104 #endif 1105 } 1106 } 1107 1108 if (itaddr.s_addr == myaddr.s_addr && 1109 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1110 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1111 #ifdef DEBUG_LINKLOCAL 1112 printf("arp: sending reply for link-local addr %s\n", 1113 inet_ntoa_r(itaddr, addrbuf)); 1114 #endif 1115 m->m_flags |= M_BCAST; 1116 m->m_flags &= ~M_MCAST; 1117 } else { 1118 /* default behaviour; never reply by broadcast. */ 1119 m->m_flags &= ~(M_BCAST|M_MCAST); 1120 } 1121 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1122 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1123 ah->ar_op = htons(ARPOP_REPLY); 1124 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1125 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1126 m->m_pkthdr.len = m->m_len; 1127 m->m_pkthdr.rcvif = NULL; 1128 sa.sa_family = AF_ARP; 1129 sa.sa_len = 2; 1130 1131 /* Calculate link header for sending frame */ 1132 bzero(&ro, sizeof(ro)); 1133 linkhdrsize = sizeof(linkhdr); 1134 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1135 1136 /* 1137 * arp_fillheader() may fail due to lack of support inside encap request 1138 * routing. This is not necessary an error, AF_ARP can/should be handled 1139 * by if_output(). 1140 */ 1141 if (error != 0 && error != EAFNOSUPPORT) { 1142 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1143 if_name(ifp), error); 1144 return; 1145 } 1146 1147 ro.ro_prepend = linkhdr; 1148 ro.ro_plen = linkhdrsize; 1149 ro.ro_flags = 0; 1150 1151 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1152 (*ifp->if_output)(ifp, m, &sa, &ro); 1153 ARPSTAT_INC(txreplies); 1154 return; 1155 1156 drop: 1157 m_freem(m); 1158 } 1159 #endif 1160 1161 /* 1162 * Checks received arp data against existing @la. 1163 * Updates lle state/performs notification if necessary. 1164 */ 1165 static void 1166 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1167 int bridged, struct llentry *la) 1168 { 1169 struct sockaddr sa; 1170 struct mbuf *m_hold, *m_hold_next; 1171 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1172 size_t linkhdrsize; 1173 int lladdr_off; 1174 char addrbuf[INET_ADDRSTRLEN]; 1175 1176 LLE_WLOCK_ASSERT(la); 1177 1178 /* the following is not an error when doing bridging */ 1179 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1180 if (log_arp_wrong_iface) 1181 ARP_LOG(LOG_WARNING, "%s is on %s " 1182 "but got reply from %*D on %s\n", 1183 inet_ntoa_r(isaddr, addrbuf), 1184 la->lle_tbl->llt_ifp->if_xname, 1185 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1186 ifp->if_xname); 1187 LLE_WUNLOCK(la); 1188 return; 1189 } 1190 if ((la->la_flags & LLE_VALID) && 1191 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1192 if (la->la_flags & LLE_STATIC) { 1193 LLE_WUNLOCK(la); 1194 if (log_arp_permanent_modify) 1195 ARP_LOG(LOG_ERR, 1196 "%*D attempts to modify " 1197 "permanent entry for %s on %s\n", 1198 ifp->if_addrlen, 1199 (u_char *)ar_sha(ah), ":", 1200 inet_ntoa_r(isaddr, addrbuf), 1201 ifp->if_xname); 1202 return; 1203 } 1204 if (log_arp_movements) { 1205 ARP_LOG(LOG_INFO, "%s moved from %*D " 1206 "to %*D on %s\n", 1207 inet_ntoa_r(isaddr, addrbuf), 1208 ifp->if_addrlen, 1209 (u_char *)la->ll_addr, ":", 1210 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1211 ifp->if_xname); 1212 } 1213 } 1214 1215 /* Calculate full link prepend to use in lle */ 1216 linkhdrsize = sizeof(linkhdr); 1217 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1218 &linkhdrsize, &lladdr_off) != 0) 1219 return; 1220 1221 /* Check if something has changed */ 1222 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1223 (la->la_flags & LLE_VALID) == 0) { 1224 /* Try to perform LLE update */ 1225 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1226 lladdr_off) == 0) 1227 return; 1228 1229 /* Clear fast path feedback request if set */ 1230 la->r_skip_req = 0; 1231 } 1232 1233 arp_mark_lle_reachable(la); 1234 1235 /* 1236 * The packets are all freed within the call to the output 1237 * routine. 1238 * 1239 * NB: The lock MUST be released before the call to the 1240 * output routine. 1241 */ 1242 if (la->la_hold != NULL) { 1243 m_hold = la->la_hold; 1244 la->la_hold = NULL; 1245 la->la_numheld = 0; 1246 lltable_fill_sa_entry(la, &sa); 1247 LLE_WUNLOCK(la); 1248 for (; m_hold != NULL; m_hold = m_hold_next) { 1249 m_hold_next = m_hold->m_nextpkt; 1250 m_hold->m_nextpkt = NULL; 1251 /* Avoid confusing lower layers. */ 1252 m_clrprotoflags(m_hold); 1253 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1254 } 1255 } else 1256 LLE_WUNLOCK(la); 1257 } 1258 1259 static void 1260 arp_mark_lle_reachable(struct llentry *la) 1261 { 1262 int canceled, wtime; 1263 1264 LLE_WLOCK_ASSERT(la); 1265 1266 la->ln_state = ARP_LLINFO_REACHABLE; 1267 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1268 1269 if (!(la->la_flags & LLE_STATIC)) { 1270 LLE_ADDREF(la); 1271 la->la_expire = time_uptime + V_arpt_keep; 1272 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1273 if (wtime < 0) 1274 wtime = V_arpt_keep; 1275 canceled = callout_reset(&la->lle_timer, 1276 hz * wtime, arptimer, la); 1277 if (canceled) 1278 LLE_REMREF(la); 1279 } 1280 la->la_asked = 0; 1281 la->la_preempt = V_arp_maxtries; 1282 } 1283 1284 /* 1285 * Add permanent link-layer record for given interface address. 1286 */ 1287 static __noinline void 1288 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1289 { 1290 struct llentry *lle, *lle_tmp; 1291 1292 /* 1293 * Interface address LLE record is considered static 1294 * because kernel code relies on LLE_STATIC flag to check 1295 * if these entries can be rewriten by arp updates. 1296 */ 1297 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1298 if (lle == NULL) { 1299 log(LOG_INFO, "arp_ifinit: cannot create arp " 1300 "entry for interface address\n"); 1301 return; 1302 } 1303 1304 IF_AFDATA_WLOCK(ifp); 1305 LLE_WLOCK(lle); 1306 /* Unlink any entry if exists */ 1307 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1308 if (lle_tmp != NULL) 1309 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1310 1311 lltable_link_entry(LLTABLE(ifp), lle); 1312 IF_AFDATA_WUNLOCK(ifp); 1313 1314 if (lle_tmp != NULL) 1315 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1316 1317 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1318 LLE_WUNLOCK(lle); 1319 if (lle_tmp != NULL) 1320 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1321 } 1322 1323 /* 1324 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1325 * of valid values. 1326 */ 1327 static int 1328 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1329 { 1330 int error; 1331 int rexmit_count = *(int *)arg1; 1332 1333 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1334 1335 /* Enforce limits on any new value that may have been set. */ 1336 if (!error && req->newptr) { 1337 /* A new value was set. */ 1338 if (rexmit_count < 0) { 1339 rexmit_count = 0; 1340 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1341 rexmit_count = MAX_GARP_RETRANSMITS; 1342 } 1343 *(int *)arg1 = rexmit_count; 1344 } 1345 1346 return (error); 1347 } 1348 1349 /* 1350 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1351 * retransmit it again. A pending callout owns a reference to the ifa. 1352 */ 1353 static void 1354 garp_rexmit(void *arg) 1355 { 1356 struct in_ifaddr *ia = arg; 1357 1358 if (callout_pending(&ia->ia_garp_timer) || 1359 !callout_active(&ia->ia_garp_timer)) { 1360 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1361 ifa_free(&ia->ia_ifa); 1362 return; 1363 } 1364 1365 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet); 1366 1367 /* 1368 * Drop lock while the ARP request is generated. 1369 */ 1370 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1371 1372 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1373 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1374 1375 /* 1376 * Increment the count of retransmissions. If the count has reached the 1377 * maximum value, stop sending the GARP packets. Otherwise, schedule 1378 * the callout to retransmit another GARP packet. 1379 */ 1380 ++ia->ia_garp_count; 1381 if (ia->ia_garp_count >= garp_rexmit_count) { 1382 ifa_free(&ia->ia_ifa); 1383 } else { 1384 int rescheduled; 1385 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1386 rescheduled = callout_reset(&ia->ia_garp_timer, 1387 (1 << ia->ia_garp_count) * hz, 1388 garp_rexmit, ia); 1389 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1390 if (rescheduled) { 1391 ifa_free(&ia->ia_ifa); 1392 } 1393 } 1394 1395 CURVNET_RESTORE(); 1396 } 1397 1398 /* 1399 * Start the GARP retransmit timer. 1400 * 1401 * A single GARP is always transmitted when an IPv4 address is added 1402 * to an interface and that is usually sufficient. However, in some 1403 * circumstances, such as when a shared address is passed between 1404 * cluster nodes, this single GARP may occasionally be dropped or 1405 * lost. This can lead to neighbors on the network link working with a 1406 * stale ARP cache and sending packets destined for that address to 1407 * the node that previously owned the address, which may not respond. 1408 * 1409 * To avoid this situation, GARP retransmits can be enabled by setting 1410 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1411 * than zero. The setting represents the maximum number of 1412 * retransmissions. The interval between retransmissions is calculated 1413 * using an exponential backoff algorithm, doubling each time, so the 1414 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1415 */ 1416 static void 1417 garp_timer_start(struct ifaddr *ifa) 1418 { 1419 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1420 1421 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1422 ia->ia_garp_count = 0; 1423 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1424 garp_rexmit, ia) == 0) { 1425 ifa_ref(ifa); 1426 } 1427 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1428 } 1429 1430 void 1431 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1432 { 1433 const struct sockaddr_in *dst_in; 1434 const struct sockaddr *dst; 1435 1436 if (ifa->ifa_carp != NULL) 1437 return; 1438 1439 dst = ifa->ifa_addr; 1440 dst_in = (const struct sockaddr_in *)dst; 1441 1442 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1443 return; 1444 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1445 if (garp_rexmit_count > 0) { 1446 garp_timer_start(ifa); 1447 } 1448 1449 arp_add_ifa_lle(ifp, dst); 1450 } 1451 1452 void 1453 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1454 { 1455 1456 if (ntohl(addr.s_addr) != INADDR_ANY) 1457 arprequest(ifp, &addr, &addr, enaddr); 1458 } 1459 1460 /* 1461 * Sends gratuitous ARPs for each ifaddr to notify other 1462 * nodes about the address change. 1463 */ 1464 static __noinline void 1465 arp_handle_ifllchange(struct ifnet *ifp) 1466 { 1467 struct ifaddr *ifa; 1468 1469 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1470 if (ifa->ifa_addr->sa_family == AF_INET) 1471 arp_ifinit(ifp, ifa); 1472 } 1473 } 1474 1475 /* 1476 * A handler for interface link layer address change event. 1477 */ 1478 static void 1479 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1480 { 1481 1482 lltable_update_ifaddr(LLTABLE(ifp)); 1483 1484 if ((ifp->if_flags & IFF_UP) != 0) 1485 arp_handle_ifllchange(ifp); 1486 } 1487 1488 static void 1489 vnet_arp_init(void) 1490 { 1491 1492 if (IS_DEFAULT_VNET(curvnet)) { 1493 netisr_register(&arp_nh); 1494 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1495 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1496 } 1497 #ifdef VIMAGE 1498 else 1499 netisr_register_vnet(&arp_nh); 1500 #endif 1501 } 1502 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1503 vnet_arp_init, 0); 1504 1505 #ifdef VIMAGE 1506 /* 1507 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1508 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1509 */ 1510 static void 1511 vnet_arp_destroy(__unused void *arg) 1512 { 1513 1514 netisr_unregister_vnet(&arp_nh); 1515 } 1516 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1517 vnet_arp_destroy, NULL); 1518 #endif 1519