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/kernel.h> 47 #include <sys/lock.h> 48 #include <sys/queue.h> 49 #include <sys/sysctl.h> 50 #include <sys/systm.h> 51 #include <sys/mbuf.h> 52 #include <sys/malloc.h> 53 #include <sys/proc.h> 54 #include <sys/rmlock.h> 55 #include <sys/socket.h> 56 #include <sys/syslog.h> 57 58 #include <net/if.h> 59 #include <net/if_var.h> 60 #include <net/if_dl.h> 61 #include <net/if_types.h> 62 #include <net/netisr.h> 63 #include <net/ethernet.h> 64 #include <net/route.h> 65 #include <net/vnet.h> 66 67 #include <netinet/in.h> 68 #include <netinet/in_fib.h> 69 #include <netinet/in_var.h> 70 #include <net/if_llatbl.h> 71 #include <netinet/if_ether.h> 72 #ifdef INET 73 #include <netinet/ip_carp.h> 74 #endif 75 76 #include <security/mac/mac_framework.h> 77 78 #define SIN(s) ((const struct sockaddr_in *)(s)) 79 80 static struct timeval arp_lastlog; 81 static int arp_curpps; 82 static int arp_maxpps = 1; 83 84 /* Simple ARP state machine */ 85 enum arp_llinfo_state { 86 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 87 ARP_LLINFO_REACHABLE, /* LLE is valid */ 88 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 89 ARP_LLINFO_DELETED, /* LLE is deleted */ 90 }; 91 92 SYSCTL_DECL(_net_link_ether); 93 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 94 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 95 96 /* timer values */ 97 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20 98 * minutes */ 99 VNET_DEFINE_STATIC(int, arp_maxtries) = 5; 100 VNET_DEFINE_STATIC(int, arp_proxyall) = 0; 101 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for 102 * 20 seconds */ 103 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 104 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 105 VNET_PCPUSTAT_SYSINIT(arpstat); 106 107 #ifdef VIMAGE 108 VNET_PCPUSTAT_SYSUNINIT(arpstat); 109 #endif /* VIMAGE */ 110 111 VNET_DEFINE_STATIC(int, arp_maxhold) = 1; 112 113 #define V_arpt_keep VNET(arpt_keep) 114 #define V_arpt_down VNET(arpt_down) 115 #define V_arpt_rexmit VNET(arpt_rexmit) 116 #define V_arp_maxtries VNET(arp_maxtries) 117 #define V_arp_proxyall VNET(arp_proxyall) 118 #define V_arp_maxhold VNET(arp_maxhold) 119 120 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 121 &VNET_NAME(arpt_keep), 0, 122 "ARP entry lifetime in seconds"); 123 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 124 &VNET_NAME(arp_maxtries), 0, 125 "ARP resolution attempts before returning error"); 126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 127 &VNET_NAME(arp_proxyall), 0, 128 "Enable proxy ARP for all suitable requests"); 129 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 130 &VNET_NAME(arpt_down), 0, 131 "Incomplete ARP entry lifetime in seconds"); 132 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 133 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 134 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 135 &VNET_NAME(arp_maxhold), 0, 136 "Number of packets to hold per ARP entry"); 137 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 138 CTLFLAG_RW, &arp_maxpps, 0, 139 "Maximum number of remotely triggered ARP messages that can be " 140 "logged per second"); 141 142 /* 143 * Due to the exponential backoff algorithm used for the interval between GARP 144 * retransmissions, the maximum number of retransmissions is limited for 145 * sanity. This limit corresponds to a maximum interval between retransmissions 146 * of 2^16 seconds ~= 18 hours. 147 * 148 * Making this limit more dynamic is more complicated than worthwhile, 149 * especially since sending out GARPs spaced days apart would be of little 150 * use. A maximum dynamic limit would look something like: 151 * 152 * const int max = fls(INT_MAX / hz) - 1; 153 */ 154 #define MAX_GARP_RETRANSMITS 16 155 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 156 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 157 158 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 159 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 160 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 161 "Number of times to retransmit GARP packets;" 162 " 0 to disable, maximum of 16"); 163 164 #define ARP_LOG(pri, ...) do { \ 165 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 166 log((pri), "arp: " __VA_ARGS__); \ 167 } while (0) 168 169 170 static void arpintr(struct mbuf *); 171 static void arptimer(void *); 172 #ifdef INET 173 static void in_arpinput(struct mbuf *); 174 #endif 175 176 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 177 struct ifnet *ifp, int bridged, struct llentry *la); 178 static void arp_mark_lle_reachable(struct llentry *la); 179 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 180 181 static eventhandler_tag iflladdr_tag; 182 183 static const struct netisr_handler arp_nh = { 184 .nh_name = "arp", 185 .nh_handler = arpintr, 186 .nh_proto = NETISR_ARP, 187 .nh_policy = NETISR_POLICY_SOURCE, 188 }; 189 190 /* 191 * Timeout routine. Age arp_tab entries periodically. 192 */ 193 static void 194 arptimer(void *arg) 195 { 196 struct llentry *lle = (struct llentry *)arg; 197 struct ifnet *ifp; 198 int r_skip_req; 199 200 if (lle->la_flags & LLE_STATIC) { 201 return; 202 } 203 LLE_WLOCK(lle); 204 if (callout_pending(&lle->lle_timer)) { 205 /* 206 * Here we are a bit odd here in the treatment of 207 * active/pending. If the pending bit is set, it got 208 * rescheduled before I ran. The active 209 * bit we ignore, since if it was stopped 210 * in ll_tablefree() and was currently running 211 * it would have return 0 so the code would 212 * not have deleted it since the callout could 213 * not be stopped so we want to go through 214 * with the delete here now. If the callout 215 * was restarted, the pending bit will be back on and 216 * we just want to bail since the callout_reset would 217 * return 1 and our reference would have been removed 218 * by arpresolve() below. 219 */ 220 LLE_WUNLOCK(lle); 221 return; 222 } 223 ifp = lle->lle_tbl->llt_ifp; 224 CURVNET_SET(ifp->if_vnet); 225 226 switch (lle->ln_state) { 227 case ARP_LLINFO_REACHABLE: 228 229 /* 230 * Expiration time is approaching. 231 * Let's try to refresh entry if it is still 232 * in use. 233 * 234 * Set r_skip_req to get feedback from 235 * fast path. Change state and re-schedule 236 * ourselves. 237 */ 238 LLE_REQ_LOCK(lle); 239 lle->r_skip_req = 1; 240 LLE_REQ_UNLOCK(lle); 241 lle->ln_state = ARP_LLINFO_VERIFY; 242 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 243 LLE_WUNLOCK(lle); 244 CURVNET_RESTORE(); 245 return; 246 case ARP_LLINFO_VERIFY: 247 LLE_REQ_LOCK(lle); 248 r_skip_req = lle->r_skip_req; 249 LLE_REQ_UNLOCK(lle); 250 251 if (r_skip_req == 0 && lle->la_preempt > 0) { 252 /* Entry was used, issue refresh request */ 253 struct in_addr dst; 254 dst = lle->r_l3addr.addr4; 255 lle->la_preempt--; 256 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 257 LLE_WUNLOCK(lle); 258 arprequest(ifp, NULL, &dst, NULL); 259 CURVNET_RESTORE(); 260 return; 261 } 262 /* Nothing happened. Reschedule if not too late */ 263 if (lle->la_expire > time_uptime) { 264 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 265 LLE_WUNLOCK(lle); 266 CURVNET_RESTORE(); 267 return; 268 } 269 break; 270 case ARP_LLINFO_INCOMPLETE: 271 case ARP_LLINFO_DELETED: 272 break; 273 } 274 275 if ((lle->la_flags & LLE_DELETED) == 0) { 276 int evt; 277 278 if (lle->la_flags & LLE_VALID) 279 evt = LLENTRY_EXPIRED; 280 else 281 evt = LLENTRY_TIMEDOUT; 282 EVENTHANDLER_INVOKE(lle_event, lle, evt); 283 } 284 285 callout_stop(&lle->lle_timer); 286 287 /* XXX: LOR avoidance. We still have ref on lle. */ 288 LLE_WUNLOCK(lle); 289 IF_AFDATA_LOCK(ifp); 290 LLE_WLOCK(lle); 291 292 /* Guard against race with other llentry_free(). */ 293 if (lle->la_flags & LLE_LINKED) { 294 LLE_REMREF(lle); 295 lltable_unlink_entry(lle->lle_tbl, lle); 296 } 297 IF_AFDATA_UNLOCK(ifp); 298 299 size_t pkts_dropped = llentry_free(lle); 300 301 ARPSTAT_ADD(dropped, pkts_dropped); 302 ARPSTAT_INC(timeouts); 303 304 CURVNET_RESTORE(); 305 } 306 307 /* 308 * Stores link-layer header for @ifp in format suitable for if_output() 309 * into buffer @buf. Resulting header length is stored in @bufsize. 310 * 311 * Returns 0 on success. 312 */ 313 static int 314 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 315 size_t *bufsize) 316 { 317 struct if_encap_req ereq; 318 int error; 319 320 bzero(buf, *bufsize); 321 bzero(&ereq, sizeof(ereq)); 322 ereq.buf = buf; 323 ereq.bufsize = *bufsize; 324 ereq.rtype = IFENCAP_LL; 325 ereq.family = AF_ARP; 326 ereq.lladdr = ar_tha(ah); 327 ereq.hdata = (u_char *)ah; 328 if (bcast) 329 ereq.flags = IFENCAP_FLAG_BROADCAST; 330 error = ifp->if_requestencap(ifp, &ereq); 331 if (error == 0) 332 *bufsize = ereq.bufsize; 333 334 return (error); 335 } 336 337 338 /* 339 * Broadcast an ARP request. Caller specifies: 340 * - arp header source ip address 341 * - arp header target ip address 342 * - arp header source ethernet address 343 */ 344 void 345 arprequest(struct ifnet *ifp, const struct in_addr *sip, 346 const struct in_addr *tip, u_char *enaddr) 347 { 348 struct mbuf *m; 349 struct arphdr *ah; 350 struct sockaddr sa; 351 u_char *carpaddr = NULL; 352 uint8_t linkhdr[LLE_MAX_LINKHDR]; 353 size_t linkhdrsize; 354 struct route ro; 355 int error; 356 357 if (sip == NULL) { 358 /* 359 * The caller did not supply a source address, try to find 360 * a compatible one among those assigned to this interface. 361 */ 362 struct epoch_tracker et; 363 struct ifaddr *ifa; 364 365 NET_EPOCH_ENTER(et); 366 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 367 if (ifa->ifa_addr->sa_family != AF_INET) 368 continue; 369 370 if (ifa->ifa_carp) { 371 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 372 continue; 373 sip = &IA_SIN(ifa)->sin_addr; 374 } else { 375 carpaddr = NULL; 376 sip = &IA_SIN(ifa)->sin_addr; 377 } 378 379 if (0 == ((sip->s_addr ^ tip->s_addr) & 380 IA_MASKSIN(ifa)->sin_addr.s_addr)) 381 break; /* found it. */ 382 } 383 NET_EPOCH_EXIT(et); 384 if (sip == NULL) { 385 printf("%s: cannot find matching address\n", __func__); 386 return; 387 } 388 } 389 if (enaddr == NULL) 390 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 391 392 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 393 return; 394 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 395 2 * ifp->if_addrlen; 396 m->m_pkthdr.len = m->m_len; 397 M_ALIGN(m, m->m_len); 398 ah = mtod(m, struct arphdr *); 399 bzero((caddr_t)ah, m->m_len); 400 #ifdef MAC 401 mac_netinet_arp_send(ifp, m); 402 #endif 403 ah->ar_pro = htons(ETHERTYPE_IP); 404 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 405 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 406 ah->ar_op = htons(ARPOP_REQUEST); 407 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 408 bcopy(sip, ar_spa(ah), ah->ar_pln); 409 bcopy(tip, ar_tpa(ah), ah->ar_pln); 410 sa.sa_family = AF_ARP; 411 sa.sa_len = 2; 412 413 /* Calculate link header for sending frame */ 414 bzero(&ro, sizeof(ro)); 415 linkhdrsize = sizeof(linkhdr); 416 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 417 if (error != 0 && error != EAFNOSUPPORT) { 418 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 419 if_name(ifp), error); 420 return; 421 } 422 423 ro.ro_prepend = linkhdr; 424 ro.ro_plen = linkhdrsize; 425 ro.ro_flags = 0; 426 427 m->m_flags |= M_BCAST; 428 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 429 (*ifp->if_output)(ifp, m, &sa, &ro); 430 ARPSTAT_INC(txrequests); 431 } 432 433 434 /* 435 * Resolve an IP address into an ethernet address - heavy version. 436 * Used internally by arpresolve(). 437 * We have already checked that we can't use an existing lle without 438 * modification so we have to acquire an LLE_EXCLUSIVE lle lock. 439 * 440 * On success, desten and pflags are filled in and the function returns 0; 441 * If the packet must be held pending resolution, we return EWOULDBLOCK 442 * On other errors, we return the corresponding error code. 443 * Note that m_freem() handles NULL. 444 */ 445 static int 446 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 447 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 448 struct llentry **plle) 449 { 450 struct llentry *la = NULL, *la_tmp; 451 struct mbuf *curr = NULL; 452 struct mbuf *next = NULL; 453 int error, renew; 454 char *lladdr; 455 int ll_len; 456 457 if (pflags != NULL) 458 *pflags = 0; 459 if (plle != NULL) 460 *plle = NULL; 461 462 if ((flags & LLE_CREATE) == 0) { 463 struct epoch_tracker et; 464 465 NET_EPOCH_ENTER(et); 466 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 467 NET_EPOCH_EXIT(et); 468 } 469 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 470 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 471 if (la == NULL) { 472 char addrbuf[INET_ADDRSTRLEN]; 473 474 log(LOG_DEBUG, 475 "arpresolve: can't allocate llinfo for %s on %s\n", 476 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 477 if_name(ifp)); 478 m_freem(m); 479 return (EINVAL); 480 } 481 482 IF_AFDATA_WLOCK(ifp); 483 LLE_WLOCK(la); 484 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 485 /* Prefer ANY existing lle over newly-created one */ 486 if (la_tmp == NULL) 487 lltable_link_entry(LLTABLE(ifp), la); 488 IF_AFDATA_WUNLOCK(ifp); 489 if (la_tmp != NULL) { 490 lltable_free_entry(LLTABLE(ifp), la); 491 la = la_tmp; 492 } 493 } 494 if (la == NULL) { 495 m_freem(m); 496 return (EINVAL); 497 } 498 499 if ((la->la_flags & LLE_VALID) && 500 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 501 if (flags & LLE_ADDRONLY) { 502 lladdr = la->ll_addr; 503 ll_len = ifp->if_addrlen; 504 } else { 505 lladdr = la->r_linkdata; 506 ll_len = la->r_hdrlen; 507 } 508 bcopy(lladdr, desten, ll_len); 509 510 /* Notify LLE code that the entry was used by datapath */ 511 llentry_mark_used(la); 512 if (pflags != NULL) 513 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 514 if (plle) { 515 LLE_ADDREF(la); 516 *plle = la; 517 } 518 LLE_WUNLOCK(la); 519 return (0); 520 } 521 522 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 523 /* 524 * There is an arptab entry, but no ethernet address 525 * response yet. Add the mbuf to the list, dropping 526 * the oldest packet if we have exceeded the system 527 * setting. 528 */ 529 if (m != NULL) { 530 if (la->la_numheld >= V_arp_maxhold) { 531 if (la->la_hold != NULL) { 532 next = la->la_hold->m_nextpkt; 533 m_freem(la->la_hold); 534 la->la_hold = next; 535 la->la_numheld--; 536 ARPSTAT_INC(dropped); 537 } 538 } 539 if (la->la_hold != NULL) { 540 curr = la->la_hold; 541 while (curr->m_nextpkt != NULL) 542 curr = curr->m_nextpkt; 543 curr->m_nextpkt = m; 544 } else 545 la->la_hold = m; 546 la->la_numheld++; 547 } 548 /* 549 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 550 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 551 * if we have already sent arp_maxtries ARP requests. Retransmit the 552 * ARP request, but not faster than one request per second. 553 */ 554 if (la->la_asked < V_arp_maxtries) 555 error = EWOULDBLOCK; /* First request. */ 556 else 557 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 558 559 if (renew) { 560 int canceled; 561 562 LLE_ADDREF(la); 563 la->la_expire = time_uptime; 564 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 565 arptimer, la); 566 if (canceled) 567 LLE_REMREF(la); 568 la->la_asked++; 569 LLE_WUNLOCK(la); 570 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 571 return (error); 572 } 573 574 LLE_WUNLOCK(la); 575 return (error); 576 } 577 578 /* 579 * Lookups link header based on an IP address. 580 * On input: 581 * ifp is the interface we use 582 * is_gw != 0 if @dst represents gateway to some destination 583 * m is the mbuf. May be NULL if we don't have a packet. 584 * dst is the next hop, 585 * desten is the storage to put LL header. 586 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 587 * 588 * On success, full/partial link header and flags are filled in and 589 * the function returns 0. 590 * If the packet must be held pending resolution, we return EWOULDBLOCK 591 * On other errors, we return the corresponding error code. 592 * Note that m_freem() handles NULL. 593 */ 594 int 595 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 596 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 597 struct llentry **plle) 598 { 599 struct epoch_tracker et; 600 struct llentry *la = NULL; 601 602 if (pflags != NULL) 603 *pflags = 0; 604 if (plle != NULL) 605 *plle = NULL; 606 607 if (m != NULL) { 608 if (m->m_flags & M_BCAST) { 609 /* broadcast */ 610 (void)memcpy(desten, 611 ifp->if_broadcastaddr, ifp->if_addrlen); 612 return (0); 613 } 614 if (m->m_flags & M_MCAST) { 615 /* multicast */ 616 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 617 return (0); 618 } 619 } 620 621 NET_EPOCH_ENTER(et); 622 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 623 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 624 /* Entry found, let's copy lle info */ 625 bcopy(la->r_linkdata, desten, la->r_hdrlen); 626 if (pflags != NULL) 627 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 628 /* Notify the LLE handling code that the entry was used. */ 629 llentry_mark_used(la); 630 if (plle) { 631 LLE_ADDREF(la); 632 *plle = la; 633 LLE_WUNLOCK(la); 634 } 635 NET_EPOCH_EXIT(et); 636 return (0); 637 } 638 if (plle && la) 639 LLE_WUNLOCK(la); 640 NET_EPOCH_EXIT(et); 641 642 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 643 desten, pflags, plle)); 644 } 645 646 /* 647 * Common length and type checks are done here, 648 * then the protocol-specific routine is called. 649 */ 650 static void 651 arpintr(struct mbuf *m) 652 { 653 struct arphdr *ar; 654 struct ifnet *ifp; 655 char *layer; 656 int hlen; 657 658 ifp = m->m_pkthdr.rcvif; 659 660 if (m->m_len < sizeof(struct arphdr) && 661 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 662 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 663 if_name(ifp)); 664 return; 665 } 666 ar = mtod(m, struct arphdr *); 667 668 /* Check if length is sufficient */ 669 if (m->m_len < arphdr_len(ar)) { 670 m = m_pullup(m, arphdr_len(ar)); 671 if (m == NULL) { 672 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 673 if_name(ifp)); 674 return; 675 } 676 ar = mtod(m, struct arphdr *); 677 } 678 679 hlen = 0; 680 layer = ""; 681 switch (ntohs(ar->ar_hrd)) { 682 case ARPHRD_ETHER: 683 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 684 layer = "ethernet"; 685 break; 686 case ARPHRD_INFINIBAND: 687 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 688 layer = "infiniband"; 689 break; 690 case ARPHRD_IEEE1394: 691 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 692 layer = "firewire"; 693 694 /* 695 * Restrict too long hardware addresses. 696 * Currently we are capable of handling 20-byte 697 * addresses ( sizeof(lle->ll_addr) ) 698 */ 699 if (ar->ar_hln >= 20) 700 hlen = 16; 701 break; 702 default: 703 ARP_LOG(LOG_NOTICE, 704 "packet with unknown hardware format 0x%02d received on " 705 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 706 m_freem(m); 707 return; 708 } 709 710 if (hlen != 0 && hlen != ar->ar_hln) { 711 ARP_LOG(LOG_NOTICE, 712 "packet with invalid %s address length %d received on %s\n", 713 layer, ar->ar_hln, if_name(ifp)); 714 m_freem(m); 715 return; 716 } 717 718 ARPSTAT_INC(received); 719 switch (ntohs(ar->ar_pro)) { 720 #ifdef INET 721 case ETHERTYPE_IP: 722 in_arpinput(m); 723 return; 724 #endif 725 } 726 m_freem(m); 727 } 728 729 #ifdef INET 730 /* 731 * ARP for Internet protocols on 10 Mb/s Ethernet. 732 * Algorithm is that given in RFC 826. 733 * In addition, a sanity check is performed on the sender 734 * protocol address, to catch impersonators. 735 * We no longer handle negotiations for use of trailer protocol: 736 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 737 * along with IP replies if we wanted trailers sent to us, 738 * and also sent them in response to IP replies. 739 * This allowed either end to announce the desire to receive 740 * trailer packets. 741 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 742 * but formerly didn't normally send requests. 743 */ 744 static int log_arp_wrong_iface = 1; 745 static int log_arp_movements = 1; 746 static int log_arp_permanent_modify = 1; 747 static int allow_multicast = 0; 748 749 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 750 &log_arp_wrong_iface, 0, 751 "log arp packets arriving on the wrong interface"); 752 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 753 &log_arp_movements, 0, 754 "log arp replies from MACs different than the one in the cache"); 755 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 756 &log_arp_permanent_modify, 0, 757 "log arp replies from MACs different than the one in the permanent arp entry"); 758 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 759 &allow_multicast, 0, "accept multicast addresses"); 760 761 static void 762 in_arpinput(struct mbuf *m) 763 { 764 struct rm_priotracker in_ifa_tracker; 765 struct arphdr *ah; 766 struct ifnet *ifp = m->m_pkthdr.rcvif; 767 struct llentry *la = NULL, *la_tmp; 768 struct ifaddr *ifa; 769 struct in_ifaddr *ia; 770 struct sockaddr sa; 771 struct in_addr isaddr, itaddr, myaddr; 772 u_int8_t *enaddr = NULL; 773 int op; 774 int bridged = 0, is_bridge = 0; 775 int carped; 776 struct sockaddr_in sin; 777 struct sockaddr *dst; 778 struct nhop4_basic nh4; 779 uint8_t linkhdr[LLE_MAX_LINKHDR]; 780 struct route ro; 781 size_t linkhdrsize; 782 int lladdr_off; 783 int error; 784 char addrbuf[INET_ADDRSTRLEN]; 785 struct epoch_tracker et; 786 787 sin.sin_len = sizeof(struct sockaddr_in); 788 sin.sin_family = AF_INET; 789 sin.sin_addr.s_addr = 0; 790 791 if (ifp->if_bridge) 792 bridged = 1; 793 if (ifp->if_type == IFT_BRIDGE) 794 is_bridge = 1; 795 796 /* 797 * We already have checked that mbuf contains enough contiguous data 798 * to hold entire arp message according to the arp header. 799 */ 800 ah = mtod(m, struct arphdr *); 801 802 /* 803 * ARP is only for IPv4 so we can reject packets with 804 * a protocol length not equal to an IPv4 address. 805 */ 806 if (ah->ar_pln != sizeof(struct in_addr)) { 807 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 808 sizeof(struct in_addr)); 809 goto drop; 810 } 811 812 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 813 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 814 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 815 goto drop; 816 } 817 818 op = ntohs(ah->ar_op); 819 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 820 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 821 822 if (op == ARPOP_REPLY) 823 ARPSTAT_INC(rxreplies); 824 825 /* 826 * For a bridge, we want to check the address irrespective 827 * of the receive interface. (This will change slightly 828 * when we have clusters of interfaces). 829 */ 830 IN_IFADDR_RLOCK(&in_ifa_tracker); 831 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 832 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 833 ia->ia_ifp == ifp) && 834 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 835 (ia->ia_ifa.ifa_carp == NULL || 836 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 837 ifa_ref(&ia->ia_ifa); 838 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 839 goto match; 840 } 841 } 842 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 843 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 844 ia->ia_ifp == ifp) && 845 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 846 ifa_ref(&ia->ia_ifa); 847 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 848 goto match; 849 } 850 851 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 852 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 853 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 854 addr == ia->ia_addr.sin_addr.s_addr) 855 /* 856 * Check the case when bridge shares its MAC address with 857 * some of its children, so packets are claimed by bridge 858 * itself (bridge_input() does it first), but they are really 859 * meant to be destined to the bridge member. 860 */ 861 if (is_bridge) { 862 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 863 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 864 ifa_ref(&ia->ia_ifa); 865 ifp = ia->ia_ifp; 866 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 867 goto match; 868 } 869 } 870 } 871 #undef BDG_MEMBER_MATCHES_ARP 872 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 873 874 /* 875 * No match, use the first inet address on the receive interface 876 * as a dummy address for the rest of the function. 877 */ 878 NET_EPOCH_ENTER(et); 879 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 880 if (ifa->ifa_addr->sa_family == AF_INET && 881 (ifa->ifa_carp == NULL || 882 (*carp_iamatch_p)(ifa, &enaddr))) { 883 ia = ifatoia(ifa); 884 ifa_ref(ifa); 885 NET_EPOCH_EXIT(et); 886 goto match; 887 } 888 NET_EPOCH_EXIT(et); 889 890 /* 891 * If bridging, fall back to using any inet address. 892 */ 893 IN_IFADDR_RLOCK(&in_ifa_tracker); 894 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 895 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 896 goto drop; 897 } 898 ifa_ref(&ia->ia_ifa); 899 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 900 match: 901 if (!enaddr) 902 enaddr = (u_int8_t *)IF_LLADDR(ifp); 903 carped = (ia->ia_ifa.ifa_carp != NULL); 904 myaddr = ia->ia_addr.sin_addr; 905 ifa_free(&ia->ia_ifa); 906 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 907 goto drop; /* it's from me, ignore it. */ 908 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 909 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 910 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 911 goto drop; 912 } 913 914 if (ifp->if_addrlen != ah->ar_hln) { 915 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 916 "i/f %d (ignored)\n", ifp->if_addrlen, 917 (u_char *) ar_sha(ah), ":", ah->ar_hln, 918 ifp->if_addrlen); 919 goto drop; 920 } 921 922 /* 923 * Warn if another host is using the same IP address, but only if the 924 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 925 * case we suppress the warning to avoid false positive complaints of 926 * potential misconfiguration. 927 */ 928 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 929 myaddr.s_addr != 0) { 930 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 931 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 932 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 933 itaddr = myaddr; 934 ARPSTAT_INC(dupips); 935 goto reply; 936 } 937 if (ifp->if_flags & IFF_STATICARP) 938 goto reply; 939 940 bzero(&sin, sizeof(sin)); 941 sin.sin_len = sizeof(struct sockaddr_in); 942 sin.sin_family = AF_INET; 943 sin.sin_addr = isaddr; 944 dst = (struct sockaddr *)&sin; 945 NET_EPOCH_ENTER(et); 946 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 947 NET_EPOCH_EXIT(et); 948 if (la != NULL) 949 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 950 else if (itaddr.s_addr == myaddr.s_addr) { 951 /* 952 * Request/reply to our address, but no lle exists yet. 953 * Calculate full link prepend to use in lle. 954 */ 955 linkhdrsize = sizeof(linkhdr); 956 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 957 &linkhdrsize, &lladdr_off) != 0) 958 goto reply; 959 960 /* Allocate new entry */ 961 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 962 if (la == NULL) { 963 964 /* 965 * lle creation may fail if source address belongs 966 * to non-directly connected subnet. However, we 967 * will try to answer the request instead of dropping 968 * frame. 969 */ 970 goto reply; 971 } 972 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 973 lladdr_off); 974 975 IF_AFDATA_WLOCK(ifp); 976 LLE_WLOCK(la); 977 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 978 979 /* 980 * Check if lle still does not exists. 981 * If it does, that means that we either 982 * 1) have configured it explicitly, via 983 * 1a) 'arp -s' static entry or 984 * 1b) interface address static record 985 * or 986 * 2) it was the result of sending first packet to-host 987 * or 988 * 3) it was another arp reply packet we handled in 989 * different thread. 990 * 991 * In all cases except 3) we definitely need to prefer 992 * existing lle. For the sake of simplicity, prefer any 993 * existing lle over newly-create one. 994 */ 995 if (la_tmp == NULL) 996 lltable_link_entry(LLTABLE(ifp), la); 997 IF_AFDATA_WUNLOCK(ifp); 998 999 if (la_tmp == NULL) { 1000 arp_mark_lle_reachable(la); 1001 LLE_WUNLOCK(la); 1002 } else { 1003 /* Free newly-create entry and handle packet */ 1004 lltable_free_entry(LLTABLE(ifp), la); 1005 la = la_tmp; 1006 la_tmp = NULL; 1007 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1008 /* arp_check_update_lle() returns @la unlocked */ 1009 } 1010 la = NULL; 1011 } 1012 reply: 1013 if (op != ARPOP_REQUEST) 1014 goto drop; 1015 ARPSTAT_INC(rxrequests); 1016 1017 if (itaddr.s_addr == myaddr.s_addr) { 1018 /* Shortcut.. the receiving interface is the target. */ 1019 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1020 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1021 } else { 1022 struct llentry *lle = NULL; 1023 1024 sin.sin_addr = itaddr; 1025 NET_EPOCH_ENTER(et); 1026 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1027 NET_EPOCH_EXIT(et); 1028 1029 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1030 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1031 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1032 LLE_RUNLOCK(lle); 1033 } else { 1034 1035 if (lle != NULL) 1036 LLE_RUNLOCK(lle); 1037 1038 if (!V_arp_proxyall) 1039 goto drop; 1040 1041 /* XXX MRT use table 0 for arp reply */ 1042 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1043 goto drop; 1044 1045 /* 1046 * Don't send proxies for nodes on the same interface 1047 * as this one came out of, or we'll get into a fight 1048 * over who claims what Ether address. 1049 */ 1050 if (nh4.nh_ifp == ifp) 1051 goto drop; 1052 1053 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1054 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1055 1056 /* 1057 * Also check that the node which sent the ARP packet 1058 * is on the interface we expect it to be on. This 1059 * avoids ARP chaos if an interface is connected to the 1060 * wrong network. 1061 */ 1062 1063 /* XXX MRT use table 0 for arp checks */ 1064 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1065 goto drop; 1066 if (nh4.nh_ifp != ifp) { 1067 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1068 " from %s via %s\n", 1069 inet_ntoa_r(isaddr, addrbuf), 1070 ifp->if_xname); 1071 goto drop; 1072 } 1073 1074 #ifdef DEBUG_PROXY 1075 printf("arp: proxying for %s\n", 1076 inet_ntoa_r(itaddr, addrbuf)); 1077 #endif 1078 } 1079 } 1080 1081 if (itaddr.s_addr == myaddr.s_addr && 1082 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1083 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1084 #ifdef DEBUG_LINKLOCAL 1085 printf("arp: sending reply for link-local addr %s\n", 1086 inet_ntoa_r(itaddr, addrbuf)); 1087 #endif 1088 m->m_flags |= M_BCAST; 1089 m->m_flags &= ~M_MCAST; 1090 } else { 1091 /* default behaviour; never reply by broadcast. */ 1092 m->m_flags &= ~(M_BCAST|M_MCAST); 1093 } 1094 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1095 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1096 ah->ar_op = htons(ARPOP_REPLY); 1097 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1098 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1099 m->m_pkthdr.len = m->m_len; 1100 m->m_pkthdr.rcvif = NULL; 1101 sa.sa_family = AF_ARP; 1102 sa.sa_len = 2; 1103 1104 /* Calculate link header for sending frame */ 1105 bzero(&ro, sizeof(ro)); 1106 linkhdrsize = sizeof(linkhdr); 1107 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1108 1109 /* 1110 * arp_fillheader() may fail due to lack of support inside encap request 1111 * routing. This is not necessary an error, AF_ARP can/should be handled 1112 * by if_output(). 1113 */ 1114 if (error != 0 && error != EAFNOSUPPORT) { 1115 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1116 if_name(ifp), error); 1117 return; 1118 } 1119 1120 ro.ro_prepend = linkhdr; 1121 ro.ro_plen = linkhdrsize; 1122 ro.ro_flags = 0; 1123 1124 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1125 (*ifp->if_output)(ifp, m, &sa, &ro); 1126 ARPSTAT_INC(txreplies); 1127 return; 1128 1129 drop: 1130 m_freem(m); 1131 } 1132 #endif 1133 1134 /* 1135 * Checks received arp data against existing @la. 1136 * Updates lle state/performs notification if necessary. 1137 */ 1138 static void 1139 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1140 int bridged, struct llentry *la) 1141 { 1142 struct sockaddr sa; 1143 struct mbuf *m_hold, *m_hold_next; 1144 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1145 size_t linkhdrsize; 1146 int lladdr_off; 1147 char addrbuf[INET_ADDRSTRLEN]; 1148 1149 LLE_WLOCK_ASSERT(la); 1150 1151 /* the following is not an error when doing bridging */ 1152 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1153 if (log_arp_wrong_iface) 1154 ARP_LOG(LOG_WARNING, "%s is on %s " 1155 "but got reply from %*D on %s\n", 1156 inet_ntoa_r(isaddr, addrbuf), 1157 la->lle_tbl->llt_ifp->if_xname, 1158 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1159 ifp->if_xname); 1160 LLE_WUNLOCK(la); 1161 return; 1162 } 1163 if ((la->la_flags & LLE_VALID) && 1164 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1165 if (la->la_flags & LLE_STATIC) { 1166 LLE_WUNLOCK(la); 1167 if (log_arp_permanent_modify) 1168 ARP_LOG(LOG_ERR, 1169 "%*D attempts to modify " 1170 "permanent entry for %s on %s\n", 1171 ifp->if_addrlen, 1172 (u_char *)ar_sha(ah), ":", 1173 inet_ntoa_r(isaddr, addrbuf), 1174 ifp->if_xname); 1175 return; 1176 } 1177 if (log_arp_movements) { 1178 ARP_LOG(LOG_INFO, "%s moved from %*D " 1179 "to %*D on %s\n", 1180 inet_ntoa_r(isaddr, addrbuf), 1181 ifp->if_addrlen, 1182 (u_char *)la->ll_addr, ":", 1183 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1184 ifp->if_xname); 1185 } 1186 } 1187 1188 /* Calculate full link prepend to use in lle */ 1189 linkhdrsize = sizeof(linkhdr); 1190 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1191 &linkhdrsize, &lladdr_off) != 0) 1192 return; 1193 1194 /* Check if something has changed */ 1195 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1196 (la->la_flags & LLE_VALID) == 0) { 1197 /* Try to perform LLE update */ 1198 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1199 lladdr_off) == 0) 1200 return; 1201 1202 /* Clear fast path feedback request if set */ 1203 la->r_skip_req = 0; 1204 } 1205 1206 arp_mark_lle_reachable(la); 1207 1208 /* 1209 * The packets are all freed within the call to the output 1210 * routine. 1211 * 1212 * NB: The lock MUST be released before the call to the 1213 * output routine. 1214 */ 1215 if (la->la_hold != NULL) { 1216 m_hold = la->la_hold; 1217 la->la_hold = NULL; 1218 la->la_numheld = 0; 1219 lltable_fill_sa_entry(la, &sa); 1220 LLE_WUNLOCK(la); 1221 for (; m_hold != NULL; m_hold = m_hold_next) { 1222 m_hold_next = m_hold->m_nextpkt; 1223 m_hold->m_nextpkt = NULL; 1224 /* Avoid confusing lower layers. */ 1225 m_clrprotoflags(m_hold); 1226 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1227 } 1228 } else 1229 LLE_WUNLOCK(la); 1230 } 1231 1232 static void 1233 arp_mark_lle_reachable(struct llentry *la) 1234 { 1235 int canceled, wtime; 1236 1237 LLE_WLOCK_ASSERT(la); 1238 1239 la->ln_state = ARP_LLINFO_REACHABLE; 1240 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1241 1242 if (!(la->la_flags & LLE_STATIC)) { 1243 LLE_ADDREF(la); 1244 la->la_expire = time_uptime + V_arpt_keep; 1245 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1246 if (wtime < 0) 1247 wtime = V_arpt_keep; 1248 canceled = callout_reset(&la->lle_timer, 1249 hz * wtime, arptimer, la); 1250 if (canceled) 1251 LLE_REMREF(la); 1252 } 1253 la->la_asked = 0; 1254 la->la_preempt = V_arp_maxtries; 1255 } 1256 1257 /* 1258 * Add permanent link-layer record for given interface address. 1259 */ 1260 static __noinline void 1261 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1262 { 1263 struct llentry *lle, *lle_tmp; 1264 1265 /* 1266 * Interface address LLE record is considered static 1267 * because kernel code relies on LLE_STATIC flag to check 1268 * if these entries can be rewriten by arp updates. 1269 */ 1270 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1271 if (lle == NULL) { 1272 log(LOG_INFO, "arp_ifinit: cannot create arp " 1273 "entry for interface address\n"); 1274 return; 1275 } 1276 1277 IF_AFDATA_WLOCK(ifp); 1278 LLE_WLOCK(lle); 1279 /* Unlink any entry if exists */ 1280 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1281 if (lle_tmp != NULL) 1282 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1283 1284 lltable_link_entry(LLTABLE(ifp), lle); 1285 IF_AFDATA_WUNLOCK(ifp); 1286 1287 if (lle_tmp != NULL) 1288 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1289 1290 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1291 LLE_WUNLOCK(lle); 1292 if (lle_tmp != NULL) 1293 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1294 } 1295 1296 /* 1297 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1298 * of valid values. 1299 */ 1300 static int 1301 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1302 { 1303 int error; 1304 int rexmit_count = *(int *)arg1; 1305 1306 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1307 1308 /* Enforce limits on any new value that may have been set. */ 1309 if (!error && req->newptr) { 1310 /* A new value was set. */ 1311 if (rexmit_count < 0) { 1312 rexmit_count = 0; 1313 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1314 rexmit_count = MAX_GARP_RETRANSMITS; 1315 } 1316 *(int *)arg1 = rexmit_count; 1317 } 1318 1319 return (error); 1320 } 1321 1322 /* 1323 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1324 * retransmit it again. A pending callout owns a reference to the ifa. 1325 */ 1326 static void 1327 garp_rexmit(void *arg) 1328 { 1329 struct in_ifaddr *ia = arg; 1330 1331 if (callout_pending(&ia->ia_garp_timer) || 1332 !callout_active(&ia->ia_garp_timer)) { 1333 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1334 ifa_free(&ia->ia_ifa); 1335 return; 1336 } 1337 1338 /* 1339 * Drop lock while the ARP request is generated. 1340 */ 1341 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1342 1343 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1344 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1345 1346 /* 1347 * Increment the count of retransmissions. If the count has reached the 1348 * maximum value, stop sending the GARP packets. Otherwise, schedule 1349 * the callout to retransmit another GARP packet. 1350 */ 1351 ++ia->ia_garp_count; 1352 if (ia->ia_garp_count >= garp_rexmit_count) { 1353 ifa_free(&ia->ia_ifa); 1354 } else { 1355 int rescheduled; 1356 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1357 rescheduled = callout_reset(&ia->ia_garp_timer, 1358 (1 << ia->ia_garp_count) * hz, 1359 garp_rexmit, ia); 1360 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1361 if (rescheduled) { 1362 ifa_free(&ia->ia_ifa); 1363 } 1364 } 1365 } 1366 1367 /* 1368 * Start the GARP retransmit timer. 1369 * 1370 * A single GARP is always transmitted when an IPv4 address is added 1371 * to an interface and that is usually sufficient. However, in some 1372 * circumstances, such as when a shared address is passed between 1373 * cluster nodes, this single GARP may occasionally be dropped or 1374 * lost. This can lead to neighbors on the network link working with a 1375 * stale ARP cache and sending packets destined for that address to 1376 * the node that previously owned the address, which may not respond. 1377 * 1378 * To avoid this situation, GARP retransmits can be enabled by setting 1379 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1380 * than zero. The setting represents the maximum number of 1381 * retransmissions. The interval between retransmissions is calculated 1382 * using an exponential backoff algorithm, doubling each time, so the 1383 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1384 */ 1385 static void 1386 garp_timer_start(struct ifaddr *ifa) 1387 { 1388 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1389 1390 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1391 ia->ia_garp_count = 0; 1392 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1393 garp_rexmit, ia) == 0) { 1394 ifa_ref(ifa); 1395 } 1396 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1397 } 1398 1399 void 1400 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1401 { 1402 const struct sockaddr_in *dst_in; 1403 const struct sockaddr *dst; 1404 1405 if (ifa->ifa_carp != NULL) 1406 return; 1407 1408 dst = ifa->ifa_addr; 1409 dst_in = (const struct sockaddr_in *)dst; 1410 1411 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1412 return; 1413 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1414 if (garp_rexmit_count > 0) { 1415 garp_timer_start(ifa); 1416 } 1417 1418 arp_add_ifa_lle(ifp, dst); 1419 } 1420 1421 void 1422 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1423 { 1424 1425 if (ntohl(addr.s_addr) != INADDR_ANY) 1426 arprequest(ifp, &addr, &addr, enaddr); 1427 } 1428 1429 /* 1430 * Sends gratuitous ARPs for each ifaddr to notify other 1431 * nodes about the address change. 1432 */ 1433 static __noinline void 1434 arp_handle_ifllchange(struct ifnet *ifp) 1435 { 1436 struct ifaddr *ifa; 1437 1438 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1439 if (ifa->ifa_addr->sa_family == AF_INET) 1440 arp_ifinit(ifp, ifa); 1441 } 1442 } 1443 1444 /* 1445 * A handler for interface link layer address change event. 1446 */ 1447 static void 1448 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1449 { 1450 1451 lltable_update_ifaddr(LLTABLE(ifp)); 1452 1453 if ((ifp->if_flags & IFF_UP) != 0) 1454 arp_handle_ifllchange(ifp); 1455 } 1456 1457 static void 1458 vnet_arp_init(void) 1459 { 1460 1461 if (IS_DEFAULT_VNET(curvnet)) { 1462 netisr_register(&arp_nh); 1463 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1464 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1465 } 1466 #ifdef VIMAGE 1467 else 1468 netisr_register_vnet(&arp_nh); 1469 #endif 1470 } 1471 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1472 vnet_arp_init, 0); 1473 1474 #ifdef VIMAGE 1475 /* 1476 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1477 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1478 */ 1479 static void 1480 vnet_arp_destroy(__unused void *arg) 1481 { 1482 1483 netisr_unregister_vnet(&arp_nh); 1484 } 1485 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1486 vnet_arp_destroy, NULL); 1487 #endif 1488