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sys/netinet/if_ether.c
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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: releng/12.0/sys/netinet/if_ether.c 336676 2018-07-24 16:35:52Z andrew $"); 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 than we can't use existing lle without 437 * modification so we have to acquire LLE_EXCLUSIVE lle lock. 438 * 439 * On success, desten and flags 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 * Resolve an IP address into an ethernet address. 577 */ 578 int 579 arpresolve_addr(struct ifnet *ifp, int flags, const struct sockaddr *dst, 580 char *desten, uint32_t *pflags, struct llentry **plle) 581 { 582 int error; 583 584 flags |= LLE_ADDRONLY; 585 error = arpresolve_full(ifp, 0, flags, NULL, dst, desten, pflags, plle); 586 return (error); 587 } 588 589 590 /* 591 * Lookups link header based on an IP address. 592 * On input: 593 * ifp is the interface we use 594 * is_gw != 0 if @dst represents gateway to some destination 595 * m is the mbuf. May be NULL if we don't have a packet. 596 * dst is the next hop, 597 * desten is the storage to put LL header. 598 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 599 * 600 * On success, full/partial link header and flags are filled in and 601 * the function returns 0. 602 * If the packet must be held pending resolution, we return EWOULDBLOCK 603 * On other errors, we return the corresponding error code. 604 * Note that m_freem() handles NULL. 605 */ 606 int 607 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 608 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 609 struct llentry **plle) 610 { 611 struct llentry *la = NULL; 612 613 if (pflags != NULL) 614 *pflags = 0; 615 if (plle != NULL) 616 *plle = NULL; 617 618 if (m != NULL) { 619 if (m->m_flags & M_BCAST) { 620 /* broadcast */ 621 (void)memcpy(desten, 622 ifp->if_broadcastaddr, ifp->if_addrlen); 623 return (0); 624 } 625 if (m->m_flags & M_MCAST) { 626 /* multicast */ 627 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 628 return (0); 629 } 630 } 631 632 IF_AFDATA_RLOCK(ifp); 633 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 634 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 635 /* Entry found, let's copy lle info */ 636 bcopy(la->r_linkdata, desten, la->r_hdrlen); 637 if (pflags != NULL) 638 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 639 /* Notify the LLE handling code that the entry was used. */ 640 llentry_mark_used(la); 641 if (plle) { 642 LLE_ADDREF(la); 643 *plle = la; 644 LLE_WUNLOCK(la); 645 } 646 IF_AFDATA_RUNLOCK(ifp); 647 return (0); 648 } 649 if (plle && la) 650 LLE_WUNLOCK(la); 651 IF_AFDATA_RUNLOCK(ifp); 652 653 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 654 desten, pflags, plle)); 655 } 656 657 /* 658 * Common length and type checks are done here, 659 * then the protocol-specific routine is called. 660 */ 661 static void 662 arpintr(struct mbuf *m) 663 { 664 struct arphdr *ar; 665 struct ifnet *ifp; 666 char *layer; 667 int hlen; 668 669 ifp = m->m_pkthdr.rcvif; 670 671 if (m->m_len < sizeof(struct arphdr) && 672 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 673 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 674 if_name(ifp)); 675 return; 676 } 677 ar = mtod(m, struct arphdr *); 678 679 /* Check if length is sufficient */ 680 if (m->m_len < arphdr_len(ar)) { 681 m = m_pullup(m, arphdr_len(ar)); 682 if (m == NULL) { 683 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 684 if_name(ifp)); 685 return; 686 } 687 ar = mtod(m, struct arphdr *); 688 } 689 690 hlen = 0; 691 layer = ""; 692 switch (ntohs(ar->ar_hrd)) { 693 case ARPHRD_ETHER: 694 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 695 layer = "ethernet"; 696 break; 697 case ARPHRD_INFINIBAND: 698 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 699 layer = "infiniband"; 700 break; 701 case ARPHRD_IEEE1394: 702 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 703 layer = "firewire"; 704 705 /* 706 * Restrict too long hardware addresses. 707 * Currently we are capable of handling 20-byte 708 * addresses ( sizeof(lle->ll_addr) ) 709 */ 710 if (ar->ar_hln >= 20) 711 hlen = 16; 712 break; 713 default: 714 ARP_LOG(LOG_NOTICE, 715 "packet with unknown hardware format 0x%02d received on " 716 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 717 m_freem(m); 718 return; 719 } 720 721 if (hlen != 0 && hlen != ar->ar_hln) { 722 ARP_LOG(LOG_NOTICE, 723 "packet with invalid %s address length %d received on %s\n", 724 layer, ar->ar_hln, if_name(ifp)); 725 m_freem(m); 726 return; 727 } 728 729 ARPSTAT_INC(received); 730 switch (ntohs(ar->ar_pro)) { 731 #ifdef INET 732 case ETHERTYPE_IP: 733 in_arpinput(m); 734 return; 735 #endif 736 } 737 m_freem(m); 738 } 739 740 #ifdef INET 741 /* 742 * ARP for Internet protocols on 10 Mb/s Ethernet. 743 * Algorithm is that given in RFC 826. 744 * In addition, a sanity check is performed on the sender 745 * protocol address, to catch impersonators. 746 * We no longer handle negotiations for use of trailer protocol: 747 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 748 * along with IP replies if we wanted trailers sent to us, 749 * and also sent them in response to IP replies. 750 * This allowed either end to announce the desire to receive 751 * trailer packets. 752 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 753 * but formerly didn't normally send requests. 754 */ 755 static int log_arp_wrong_iface = 1; 756 static int log_arp_movements = 1; 757 static int log_arp_permanent_modify = 1; 758 static int allow_multicast = 0; 759 760 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 761 &log_arp_wrong_iface, 0, 762 "log arp packets arriving on the wrong interface"); 763 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 764 &log_arp_movements, 0, 765 "log arp replies from MACs different than the one in the cache"); 766 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 767 &log_arp_permanent_modify, 0, 768 "log arp replies from MACs different than the one in the permanent arp entry"); 769 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 770 &allow_multicast, 0, "accept multicast addresses"); 771 772 static void 773 in_arpinput(struct mbuf *m) 774 { 775 struct rm_priotracker in_ifa_tracker; 776 struct arphdr *ah; 777 struct ifnet *ifp = m->m_pkthdr.rcvif; 778 struct llentry *la = NULL, *la_tmp; 779 struct ifaddr *ifa; 780 struct in_ifaddr *ia; 781 struct sockaddr sa; 782 struct in_addr isaddr, itaddr, myaddr; 783 u_int8_t *enaddr = NULL; 784 int op; 785 int bridged = 0, is_bridge = 0; 786 int carped; 787 struct sockaddr_in sin; 788 struct sockaddr *dst; 789 struct nhop4_basic nh4; 790 uint8_t linkhdr[LLE_MAX_LINKHDR]; 791 struct route ro; 792 size_t linkhdrsize; 793 int lladdr_off; 794 int error; 795 char addrbuf[INET_ADDRSTRLEN]; 796 797 sin.sin_len = sizeof(struct sockaddr_in); 798 sin.sin_family = AF_INET; 799 sin.sin_addr.s_addr = 0; 800 801 if (ifp->if_bridge) 802 bridged = 1; 803 if (ifp->if_type == IFT_BRIDGE) 804 is_bridge = 1; 805 806 /* 807 * We already have checked that mbuf contains enough contiguous data 808 * to hold entire arp message according to the arp header. 809 */ 810 ah = mtod(m, struct arphdr *); 811 812 /* 813 * ARP is only for IPv4 so we can reject packets with 814 * a protocol length not equal to an IPv4 address. 815 */ 816 if (ah->ar_pln != sizeof(struct in_addr)) { 817 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 818 sizeof(struct in_addr)); 819 goto drop; 820 } 821 822 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 823 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 824 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 825 goto drop; 826 } 827 828 op = ntohs(ah->ar_op); 829 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 830 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 831 832 if (op == ARPOP_REPLY) 833 ARPSTAT_INC(rxreplies); 834 835 /* 836 * For a bridge, we want to check the address irrespective 837 * of the receive interface. (This will change slightly 838 * when we have clusters of interfaces). 839 */ 840 IN_IFADDR_RLOCK(&in_ifa_tracker); 841 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 842 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 843 ia->ia_ifp == ifp) && 844 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 845 (ia->ia_ifa.ifa_carp == NULL || 846 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 847 ifa_ref(&ia->ia_ifa); 848 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 849 goto match; 850 } 851 } 852 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 853 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 854 ia->ia_ifp == ifp) && 855 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 856 ifa_ref(&ia->ia_ifa); 857 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 858 goto match; 859 } 860 861 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 862 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 863 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 864 addr == ia->ia_addr.sin_addr.s_addr) 865 /* 866 * Check the case when bridge shares its MAC address with 867 * some of its children, so packets are claimed by bridge 868 * itself (bridge_input() does it first), but they are really 869 * meant to be destined to the bridge member. 870 */ 871 if (is_bridge) { 872 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 873 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 874 ifa_ref(&ia->ia_ifa); 875 ifp = ia->ia_ifp; 876 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 877 goto match; 878 } 879 } 880 } 881 #undef BDG_MEMBER_MATCHES_ARP 882 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 883 884 /* 885 * No match, use the first inet address on the receive interface 886 * as a dummy address for the rest of the function. 887 */ 888 IF_ADDR_RLOCK(ifp); 889 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 890 if (ifa->ifa_addr->sa_family == AF_INET && 891 (ifa->ifa_carp == NULL || 892 (*carp_iamatch_p)(ifa, &enaddr))) { 893 ia = ifatoia(ifa); 894 ifa_ref(ifa); 895 IF_ADDR_RUNLOCK(ifp); 896 goto match; 897 } 898 IF_ADDR_RUNLOCK(ifp); 899 900 /* 901 * If bridging, fall back to using any inet address. 902 */ 903 IN_IFADDR_RLOCK(&in_ifa_tracker); 904 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 905 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 906 goto drop; 907 } 908 ifa_ref(&ia->ia_ifa); 909 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 910 match: 911 if (!enaddr) 912 enaddr = (u_int8_t *)IF_LLADDR(ifp); 913 carped = (ia->ia_ifa.ifa_carp != NULL); 914 myaddr = ia->ia_addr.sin_addr; 915 ifa_free(&ia->ia_ifa); 916 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 917 goto drop; /* it's from me, ignore it. */ 918 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 919 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 920 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 921 goto drop; 922 } 923 924 if (ifp->if_addrlen != ah->ar_hln) { 925 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 926 "i/f %d (ignored)\n", ifp->if_addrlen, 927 (u_char *) ar_sha(ah), ":", ah->ar_hln, 928 ifp->if_addrlen); 929 goto drop; 930 } 931 932 /* 933 * Warn if another host is using the same IP address, but only if the 934 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 935 * case we suppress the warning to avoid false positive complaints of 936 * potential misconfiguration. 937 */ 938 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 939 myaddr.s_addr != 0) { 940 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 941 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 942 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 943 itaddr = myaddr; 944 ARPSTAT_INC(dupips); 945 goto reply; 946 } 947 if (ifp->if_flags & IFF_STATICARP) 948 goto reply; 949 950 bzero(&sin, sizeof(sin)); 951 sin.sin_len = sizeof(struct sockaddr_in); 952 sin.sin_family = AF_INET; 953 sin.sin_addr = isaddr; 954 dst = (struct sockaddr *)&sin; 955 IF_AFDATA_RLOCK(ifp); 956 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 957 IF_AFDATA_RUNLOCK(ifp); 958 if (la != NULL) 959 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 960 else if (itaddr.s_addr == myaddr.s_addr) { 961 /* 962 * Request/reply to our address, but no lle exists yet. 963 * Calculate full link prepend to use in lle. 964 */ 965 linkhdrsize = sizeof(linkhdr); 966 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 967 &linkhdrsize, &lladdr_off) != 0) 968 goto reply; 969 970 /* Allocate new entry */ 971 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 972 if (la == NULL) { 973 974 /* 975 * lle creation may fail if source address belongs 976 * to non-directly connected subnet. However, we 977 * will try to answer the request instead of dropping 978 * frame. 979 */ 980 goto reply; 981 } 982 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 983 lladdr_off); 984 985 IF_AFDATA_WLOCK(ifp); 986 LLE_WLOCK(la); 987 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 988 989 /* 990 * Check if lle still does not exists. 991 * If it does, that means that we either 992 * 1) have configured it explicitly, via 993 * 1a) 'arp -s' static entry or 994 * 1b) interface address static record 995 * or 996 * 2) it was the result of sending first packet to-host 997 * or 998 * 3) it was another arp reply packet we handled in 999 * different thread. 1000 * 1001 * In all cases except 3) we definitely need to prefer 1002 * existing lle. For the sake of simplicity, prefer any 1003 * existing lle over newly-create one. 1004 */ 1005 if (la_tmp == NULL) 1006 lltable_link_entry(LLTABLE(ifp), la); 1007 IF_AFDATA_WUNLOCK(ifp); 1008 1009 if (la_tmp == NULL) { 1010 arp_mark_lle_reachable(la); 1011 LLE_WUNLOCK(la); 1012 } else { 1013 /* Free newly-create entry and handle packet */ 1014 lltable_free_entry(LLTABLE(ifp), la); 1015 la = la_tmp; 1016 la_tmp = NULL; 1017 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1018 /* arp_check_update_lle() returns @la unlocked */ 1019 } 1020 la = NULL; 1021 } 1022 reply: 1023 if (op != ARPOP_REQUEST) 1024 goto drop; 1025 ARPSTAT_INC(rxrequests); 1026 1027 if (itaddr.s_addr == myaddr.s_addr) { 1028 /* Shortcut.. the receiving interface is the target. */ 1029 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1030 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1031 } else { 1032 struct llentry *lle = NULL; 1033 1034 sin.sin_addr = itaddr; 1035 IF_AFDATA_RLOCK(ifp); 1036 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1037 IF_AFDATA_RUNLOCK(ifp); 1038 1039 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1040 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1041 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1042 LLE_RUNLOCK(lle); 1043 } else { 1044 1045 if (lle != NULL) 1046 LLE_RUNLOCK(lle); 1047 1048 if (!V_arp_proxyall) 1049 goto drop; 1050 1051 /* XXX MRT use table 0 for arp reply */ 1052 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1053 goto drop; 1054 1055 /* 1056 * Don't send proxies for nodes on the same interface 1057 * as this one came out of, or we'll get into a fight 1058 * over who claims what Ether address. 1059 */ 1060 if (nh4.nh_ifp == ifp) 1061 goto drop; 1062 1063 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1064 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1065 1066 /* 1067 * Also check that the node which sent the ARP packet 1068 * is on the interface we expect it to be on. This 1069 * avoids ARP chaos if an interface is connected to the 1070 * wrong network. 1071 */ 1072 1073 /* XXX MRT use table 0 for arp checks */ 1074 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1075 goto drop; 1076 if (nh4.nh_ifp != ifp) { 1077 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1078 " from %s via %s\n", 1079 inet_ntoa_r(isaddr, addrbuf), 1080 ifp->if_xname); 1081 goto drop; 1082 } 1083 1084 #ifdef DEBUG_PROXY 1085 printf("arp: proxying for %s\n", 1086 inet_ntoa_r(itaddr, addrbuf)); 1087 #endif 1088 } 1089 } 1090 1091 if (itaddr.s_addr == myaddr.s_addr && 1092 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1093 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1094 #ifdef DEBUG_LINKLOCAL 1095 printf("arp: sending reply for link-local addr %s\n", 1096 inet_ntoa_r(itaddr, addrbuf)); 1097 #endif 1098 m->m_flags |= M_BCAST; 1099 m->m_flags &= ~M_MCAST; 1100 } else { 1101 /* default behaviour; never reply by broadcast. */ 1102 m->m_flags &= ~(M_BCAST|M_MCAST); 1103 } 1104 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1105 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1106 ah->ar_op = htons(ARPOP_REPLY); 1107 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1108 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1109 m->m_pkthdr.len = m->m_len; 1110 m->m_pkthdr.rcvif = NULL; 1111 sa.sa_family = AF_ARP; 1112 sa.sa_len = 2; 1113 1114 /* Calculate link header for sending frame */ 1115 bzero(&ro, sizeof(ro)); 1116 linkhdrsize = sizeof(linkhdr); 1117 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1118 1119 /* 1120 * arp_fillheader() may fail due to lack of support inside encap request 1121 * routing. This is not necessary an error, AF_ARP can/should be handled 1122 * by if_output(). 1123 */ 1124 if (error != 0 && error != EAFNOSUPPORT) { 1125 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1126 if_name(ifp), error); 1127 return; 1128 } 1129 1130 ro.ro_prepend = linkhdr; 1131 ro.ro_plen = linkhdrsize; 1132 ro.ro_flags = 0; 1133 1134 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1135 (*ifp->if_output)(ifp, m, &sa, &ro); 1136 ARPSTAT_INC(txreplies); 1137 return; 1138 1139 drop: 1140 m_freem(m); 1141 } 1142 #endif 1143 1144 /* 1145 * Checks received arp data against existing @la. 1146 * Updates lle state/performs notification if necessary. 1147 */ 1148 static void 1149 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1150 int bridged, struct llentry *la) 1151 { 1152 struct sockaddr sa; 1153 struct mbuf *m_hold, *m_hold_next; 1154 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1155 size_t linkhdrsize; 1156 int lladdr_off; 1157 char addrbuf[INET_ADDRSTRLEN]; 1158 1159 LLE_WLOCK_ASSERT(la); 1160 1161 /* the following is not an error when doing bridging */ 1162 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1163 if (log_arp_wrong_iface) 1164 ARP_LOG(LOG_WARNING, "%s is on %s " 1165 "but got reply from %*D on %s\n", 1166 inet_ntoa_r(isaddr, addrbuf), 1167 la->lle_tbl->llt_ifp->if_xname, 1168 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1169 ifp->if_xname); 1170 LLE_WUNLOCK(la); 1171 return; 1172 } 1173 if ((la->la_flags & LLE_VALID) && 1174 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1175 if (la->la_flags & LLE_STATIC) { 1176 LLE_WUNLOCK(la); 1177 if (log_arp_permanent_modify) 1178 ARP_LOG(LOG_ERR, 1179 "%*D attempts to modify " 1180 "permanent entry for %s on %s\n", 1181 ifp->if_addrlen, 1182 (u_char *)ar_sha(ah), ":", 1183 inet_ntoa_r(isaddr, addrbuf), 1184 ifp->if_xname); 1185 return; 1186 } 1187 if (log_arp_movements) { 1188 ARP_LOG(LOG_INFO, "%s moved from %*D " 1189 "to %*D on %s\n", 1190 inet_ntoa_r(isaddr, addrbuf), 1191 ifp->if_addrlen, 1192 (u_char *)la->ll_addr, ":", 1193 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1194 ifp->if_xname); 1195 } 1196 } 1197 1198 /* Calculate full link prepend to use in lle */ 1199 linkhdrsize = sizeof(linkhdr); 1200 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1201 &linkhdrsize, &lladdr_off) != 0) 1202 return; 1203 1204 /* Check if something has changed */ 1205 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1206 (la->la_flags & LLE_VALID) == 0) { 1207 /* Try to perform LLE update */ 1208 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1209 lladdr_off) == 0) 1210 return; 1211 1212 /* Clear fast path feedback request if set */ 1213 la->r_skip_req = 0; 1214 } 1215 1216 arp_mark_lle_reachable(la); 1217 1218 /* 1219 * The packets are all freed within the call to the output 1220 * routine. 1221 * 1222 * NB: The lock MUST be released before the call to the 1223 * output routine. 1224 */ 1225 if (la->la_hold != NULL) { 1226 m_hold = la->la_hold; 1227 la->la_hold = NULL; 1228 la->la_numheld = 0; 1229 lltable_fill_sa_entry(la, &sa); 1230 LLE_WUNLOCK(la); 1231 for (; m_hold != NULL; m_hold = m_hold_next) { 1232 m_hold_next = m_hold->m_nextpkt; 1233 m_hold->m_nextpkt = NULL; 1234 /* Avoid confusing lower layers. */ 1235 m_clrprotoflags(m_hold); 1236 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1237 } 1238 } else 1239 LLE_WUNLOCK(la); 1240 } 1241 1242 static void 1243 arp_mark_lle_reachable(struct llentry *la) 1244 { 1245 int canceled, wtime; 1246 1247 LLE_WLOCK_ASSERT(la); 1248 1249 la->ln_state = ARP_LLINFO_REACHABLE; 1250 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1251 1252 if (!(la->la_flags & LLE_STATIC)) { 1253 LLE_ADDREF(la); 1254 la->la_expire = time_uptime + V_arpt_keep; 1255 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1256 if (wtime < 0) 1257 wtime = V_arpt_keep; 1258 canceled = callout_reset(&la->lle_timer, 1259 hz * wtime, arptimer, la); 1260 if (canceled) 1261 LLE_REMREF(la); 1262 } 1263 la->la_asked = 0; 1264 la->la_preempt = V_arp_maxtries; 1265 } 1266 1267 /* 1268 * Add permanent link-layer record for given interface address. 1269 */ 1270 static __noinline void 1271 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1272 { 1273 struct llentry *lle, *lle_tmp; 1274 1275 /* 1276 * Interface address LLE record is considered static 1277 * because kernel code relies on LLE_STATIC flag to check 1278 * if these entries can be rewriten by arp updates. 1279 */ 1280 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1281 if (lle == NULL) { 1282 log(LOG_INFO, "arp_ifinit: cannot create arp " 1283 "entry for interface address\n"); 1284 return; 1285 } 1286 1287 IF_AFDATA_WLOCK(ifp); 1288 LLE_WLOCK(lle); 1289 /* Unlink any entry if exists */ 1290 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1291 if (lle_tmp != NULL) 1292 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1293 1294 lltable_link_entry(LLTABLE(ifp), lle); 1295 IF_AFDATA_WUNLOCK(ifp); 1296 1297 if (lle_tmp != NULL) 1298 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1299 1300 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1301 LLE_WUNLOCK(lle); 1302 if (lle_tmp != NULL) 1303 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1304 } 1305 1306 /* 1307 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1308 * of valid values. 1309 */ 1310 static int 1311 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1312 { 1313 int error; 1314 int rexmit_count = *(int *)arg1; 1315 1316 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1317 1318 /* Enforce limits on any new value that may have been set. */ 1319 if (!error && req->newptr) { 1320 /* A new value was set. */ 1321 if (rexmit_count < 0) { 1322 rexmit_count = 0; 1323 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1324 rexmit_count = MAX_GARP_RETRANSMITS; 1325 } 1326 *(int *)arg1 = rexmit_count; 1327 } 1328 1329 return (error); 1330 } 1331 1332 /* 1333 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1334 * retransmit it again. A pending callout owns a reference to the ifa. 1335 */ 1336 static void 1337 garp_rexmit(void *arg) 1338 { 1339 struct in_ifaddr *ia = arg; 1340 1341 if (callout_pending(&ia->ia_garp_timer) || 1342 !callout_active(&ia->ia_garp_timer)) { 1343 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1344 ifa_free(&ia->ia_ifa); 1345 return; 1346 } 1347 1348 /* 1349 * Drop lock while the ARP request is generated. 1350 */ 1351 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1352 1353 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1354 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1355 1356 /* 1357 * Increment the count of retransmissions. If the count has reached the 1358 * maximum value, stop sending the GARP packets. Otherwise, schedule 1359 * the callout to retransmit another GARP packet. 1360 */ 1361 ++ia->ia_garp_count; 1362 if (ia->ia_garp_count >= garp_rexmit_count) { 1363 ifa_free(&ia->ia_ifa); 1364 } else { 1365 int rescheduled; 1366 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1367 rescheduled = callout_reset(&ia->ia_garp_timer, 1368 (1 << ia->ia_garp_count) * hz, 1369 garp_rexmit, ia); 1370 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1371 if (rescheduled) { 1372 ifa_free(&ia->ia_ifa); 1373 } 1374 } 1375 } 1376 1377 /* 1378 * Start the GARP retransmit timer. 1379 * 1380 * A single GARP is always transmitted when an IPv4 address is added 1381 * to an interface and that is usually sufficient. However, in some 1382 * circumstances, such as when a shared address is passed between 1383 * cluster nodes, this single GARP may occasionally be dropped or 1384 * lost. This can lead to neighbors on the network link working with a 1385 * stale ARP cache and sending packets destined for that address to 1386 * the node that previously owned the address, which may not respond. 1387 * 1388 * To avoid this situation, GARP retransmits can be enabled by setting 1389 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1390 * than zero. The setting represents the maximum number of 1391 * retransmissions. The interval between retransmissions is calculated 1392 * using an exponential backoff algorithm, doubling each time, so the 1393 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1394 */ 1395 static void 1396 garp_timer_start(struct ifaddr *ifa) 1397 { 1398 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1399 1400 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1401 ia->ia_garp_count = 0; 1402 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1403 garp_rexmit, ia) == 0) { 1404 ifa_ref(ifa); 1405 } 1406 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1407 } 1408 1409 void 1410 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1411 { 1412 const struct sockaddr_in *dst_in; 1413 const struct sockaddr *dst; 1414 1415 if (ifa->ifa_carp != NULL) 1416 return; 1417 1418 dst = ifa->ifa_addr; 1419 dst_in = (const struct sockaddr_in *)dst; 1420 1421 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1422 return; 1423 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1424 if (garp_rexmit_count > 0) { 1425 garp_timer_start(ifa); 1426 } 1427 1428 arp_add_ifa_lle(ifp, dst); 1429 } 1430 1431 void 1432 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1433 { 1434 1435 if (ntohl(addr.s_addr) != INADDR_ANY) 1436 arprequest(ifp, &addr, &addr, enaddr); 1437 } 1438 1439 /* 1440 * Sends gratuitous ARPs for each ifaddr to notify other 1441 * nodes about the address change. 1442 */ 1443 static __noinline void 1444 arp_handle_ifllchange(struct ifnet *ifp) 1445 { 1446 struct ifaddr *ifa; 1447 1448 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1449 if (ifa->ifa_addr->sa_family == AF_INET) 1450 arp_ifinit(ifp, ifa); 1451 } 1452 } 1453 1454 /* 1455 * A handler for interface link layer address change event. 1456 */ 1457 static void 1458 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1459 { 1460 1461 lltable_update_ifaddr(LLTABLE(ifp)); 1462 1463 if ((ifp->if_flags & IFF_UP) != 0) 1464 arp_handle_ifllchange(ifp); 1465 } 1466 1467 static void 1468 vnet_arp_init(void) 1469 { 1470 1471 if (IS_DEFAULT_VNET(curvnet)) { 1472 netisr_register(&arp_nh); 1473 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1474 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1475 } 1476 #ifdef VIMAGE 1477 else 1478 netisr_register_vnet(&arp_nh); 1479 #endif 1480 } 1481 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1482 vnet_arp_init, 0); 1483 1484 #ifdef VIMAGE 1485 /* 1486 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1487 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1488 */ 1489 static void 1490 vnet_arp_destroy(__unused void *arg) 1491 { 1492 1493 netisr_unregister_vnet(&arp_nh); 1494 } 1495 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1496 vnet_arp_destroy, NULL); 1497 #endif
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