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