Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/if_ether.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 30 */ 31 32 /* 33 * Ethernet address resolution protocol. 34 * TODO: 35 * add "inuse/lock" bit (or ref. count) along with valid bit 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD: releng/11.1/sys/netinet/if_ether.c 315479 2017-03-18 10:48:37Z ae $"); 40 41 #include "opt_inet.h" 42 43 #include <sys/param.h> 44 #include <sys/kernel.h> 45 #include <sys/lock.h> 46 #include <sys/queue.h> 47 #include <sys/sysctl.h> 48 #include <sys/systm.h> 49 #include <sys/mbuf.h> 50 #include <sys/malloc.h> 51 #include <sys/proc.h> 52 #include <sys/rmlock.h> 53 #include <sys/socket.h> 54 #include <sys/syslog.h> 55 56 #include <net/if.h> 57 #include <net/if_var.h> 58 #include <net/if_dl.h> 59 #include <net/if_types.h> 60 #include <net/netisr.h> 61 #include <net/ethernet.h> 62 #include <net/route.h> 63 #include <net/vnet.h> 64 65 #include <netinet/in.h> 66 #include <netinet/in_fib.h> 67 #include <netinet/in_var.h> 68 #include <net/if_llatbl.h> 69 #include <netinet/if_ether.h> 70 #ifdef INET 71 #include <netinet/ip_carp.h> 72 #endif 73 74 #include <security/mac/mac_framework.h> 75 76 #define SIN(s) ((const struct sockaddr_in *)(s)) 77 78 static struct timeval arp_lastlog; 79 static int arp_curpps; 80 static int arp_maxpps = 1; 81 82 /* Simple ARP state machine */ 83 enum arp_llinfo_state { 84 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ 85 ARP_LLINFO_REACHABLE, /* LLE is valid */ 86 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ 87 ARP_LLINFO_DELETED, /* LLE is deleted */ 88 }; 89 90 SYSCTL_DECL(_net_link_ether); 91 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 92 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); 93 94 /* timer values */ 95 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 96 * minutes */ 97 static VNET_DEFINE(int, arp_maxtries) = 5; 98 static VNET_DEFINE(int, arp_proxyall) = 0; 99 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for 100 * 20 seconds */ 101 static VNET_DEFINE(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ 102 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ 103 VNET_PCPUSTAT_SYSINIT(arpstat); 104 105 #ifdef VIMAGE 106 VNET_PCPUSTAT_SYSUNINIT(arpstat); 107 #endif /* VIMAGE */ 108 109 static VNET_DEFINE(int, arp_maxhold) = 1; 110 111 #define V_arpt_keep VNET(arpt_keep) 112 #define V_arpt_down VNET(arpt_down) 113 #define V_arpt_rexmit VNET(arpt_rexmit) 114 #define V_arp_maxtries VNET(arp_maxtries) 115 #define V_arp_proxyall VNET(arp_proxyall) 116 #define V_arp_maxhold VNET(arp_maxhold) 117 118 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, 119 &VNET_NAME(arpt_keep), 0, 120 "ARP entry lifetime in seconds"); 121 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, 122 &VNET_NAME(arp_maxtries), 0, 123 "ARP resolution attempts before returning error"); 124 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, 125 &VNET_NAME(arp_proxyall), 0, 126 "Enable proxy ARP for all suitable requests"); 127 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, 128 &VNET_NAME(arpt_down), 0, 129 "Incomplete ARP entry lifetime in seconds"); 130 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, 131 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); 132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, 133 &VNET_NAME(arp_maxhold), 0, 134 "Number of packets to hold per ARP entry"); 135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, 136 CTLFLAG_RW, &arp_maxpps, 0, 137 "Maximum number of remotely triggered ARP messages that can be " 138 "logged per second"); 139 140 /* 141 * Due to the exponential backoff algorithm used for the interval between GARP 142 * retransmissions, the maximum number of retransmissions is limited for 143 * sanity. This limit corresponds to a maximum interval between retransmissions 144 * of 2^16 seconds ~= 18 hours. 145 * 146 * Making this limit more dynamic is more complicated than worthwhile, 147 * especially since sending out GARPs spaced days apart would be of little 148 * use. A maximum dynamic limit would look something like: 149 * 150 * const int max = fls(INT_MAX / hz) - 1; 151 */ 152 #define MAX_GARP_RETRANSMITS 16 153 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); 154 static int garp_rexmit_count = 0; /* GARP retransmission setting. */ 155 156 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, 157 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, 158 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", 159 "Number of times to retransmit GARP packets;" 160 " 0 to disable, maximum of 16"); 161 162 #define ARP_LOG(pri, ...) do { \ 163 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ 164 log((pri), "arp: " __VA_ARGS__); \ 165 } while (0) 166 167 168 static void arpintr(struct mbuf *); 169 static void arptimer(void *); 170 #ifdef INET 171 static void in_arpinput(struct mbuf *); 172 #endif 173 174 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, 175 struct ifnet *ifp, int bridged, struct llentry *la); 176 static void arp_mark_lle_reachable(struct llentry *la); 177 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); 178 179 static eventhandler_tag iflladdr_tag; 180 181 static const struct netisr_handler arp_nh = { 182 .nh_name = "arp", 183 .nh_handler = arpintr, 184 .nh_proto = NETISR_ARP, 185 .nh_policy = NETISR_POLICY_SOURCE, 186 }; 187 188 /* 189 * Timeout routine. Age arp_tab entries periodically. 190 */ 191 static void 192 arptimer(void *arg) 193 { 194 struct llentry *lle = (struct llentry *)arg; 195 struct ifnet *ifp; 196 int r_skip_req; 197 198 if (lle->la_flags & LLE_STATIC) { 199 return; 200 } 201 LLE_WLOCK(lle); 202 if (callout_pending(&lle->lle_timer)) { 203 /* 204 * Here we are a bit odd here in the treatment of 205 * active/pending. If the pending bit is set, it got 206 * rescheduled before I ran. The active 207 * bit we ignore, since if it was stopped 208 * in ll_tablefree() and was currently running 209 * it would have return 0 so the code would 210 * not have deleted it since the callout could 211 * not be stopped so we want to go through 212 * with the delete here now. If the callout 213 * was restarted, the pending bit will be back on and 214 * we just want to bail since the callout_reset would 215 * return 1 and our reference would have been removed 216 * by arpresolve() below. 217 */ 218 LLE_WUNLOCK(lle); 219 return; 220 } 221 ifp = lle->lle_tbl->llt_ifp; 222 CURVNET_SET(ifp->if_vnet); 223 224 switch (lle->ln_state) { 225 case ARP_LLINFO_REACHABLE: 226 227 /* 228 * Expiration time is approaching. 229 * Let's try to refresh entry if it is still 230 * in use. 231 * 232 * Set r_skip_req to get feedback from 233 * fast path. Change state and re-schedule 234 * ourselves. 235 */ 236 LLE_REQ_LOCK(lle); 237 lle->r_skip_req = 1; 238 LLE_REQ_UNLOCK(lle); 239 lle->ln_state = ARP_LLINFO_VERIFY; 240 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 241 LLE_WUNLOCK(lle); 242 CURVNET_RESTORE(); 243 return; 244 case ARP_LLINFO_VERIFY: 245 LLE_REQ_LOCK(lle); 246 r_skip_req = lle->r_skip_req; 247 LLE_REQ_UNLOCK(lle); 248 249 if (r_skip_req == 0 && lle->la_preempt > 0) { 250 /* Entry was used, issue refresh request */ 251 struct in_addr dst; 252 dst = lle->r_l3addr.addr4; 253 lle->la_preempt--; 254 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 255 LLE_WUNLOCK(lle); 256 arprequest(ifp, NULL, &dst, NULL); 257 CURVNET_RESTORE(); 258 return; 259 } 260 /* Nothing happened. Reschedule if not too late */ 261 if (lle->la_expire > time_uptime) { 262 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); 263 LLE_WUNLOCK(lle); 264 CURVNET_RESTORE(); 265 return; 266 } 267 break; 268 case ARP_LLINFO_INCOMPLETE: 269 case ARP_LLINFO_DELETED: 270 break; 271 } 272 273 if ((lle->la_flags & LLE_DELETED) == 0) { 274 int evt; 275 276 if (lle->la_flags & LLE_VALID) 277 evt = LLENTRY_EXPIRED; 278 else 279 evt = LLENTRY_TIMEDOUT; 280 EVENTHANDLER_INVOKE(lle_event, lle, evt); 281 } 282 283 callout_stop(&lle->lle_timer); 284 285 /* XXX: LOR avoidance. We still have ref on lle. */ 286 LLE_WUNLOCK(lle); 287 IF_AFDATA_LOCK(ifp); 288 LLE_WLOCK(lle); 289 290 /* Guard against race with other llentry_free(). */ 291 if (lle->la_flags & LLE_LINKED) { 292 LLE_REMREF(lle); 293 lltable_unlink_entry(lle->lle_tbl, lle); 294 } 295 IF_AFDATA_UNLOCK(ifp); 296 297 size_t pkts_dropped = llentry_free(lle); 298 299 ARPSTAT_ADD(dropped, pkts_dropped); 300 ARPSTAT_INC(timeouts); 301 302 CURVNET_RESTORE(); 303 } 304 305 /* 306 * Stores link-layer header for @ifp in format suitable for if_output() 307 * into buffer @buf. Resulting header length is stored in @bufsize. 308 * 309 * Returns 0 on success. 310 */ 311 static int 312 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, 313 size_t *bufsize) 314 { 315 struct if_encap_req ereq; 316 int error; 317 318 bzero(buf, *bufsize); 319 bzero(&ereq, sizeof(ereq)); 320 ereq.buf = buf; 321 ereq.bufsize = *bufsize; 322 ereq.rtype = IFENCAP_LL; 323 ereq.family = AF_ARP; 324 ereq.lladdr = ar_tha(ah); 325 ereq.hdata = (u_char *)ah; 326 if (bcast) 327 ereq.flags = IFENCAP_FLAG_BROADCAST; 328 error = ifp->if_requestencap(ifp, &ereq); 329 if (error == 0) 330 *bufsize = ereq.bufsize; 331 332 return (error); 333 } 334 335 336 /* 337 * Broadcast an ARP request. Caller specifies: 338 * - arp header source ip address 339 * - arp header target ip address 340 * - arp header source ethernet address 341 */ 342 void 343 arprequest(struct ifnet *ifp, const struct in_addr *sip, 344 const struct in_addr *tip, u_char *enaddr) 345 { 346 struct mbuf *m; 347 struct arphdr *ah; 348 struct sockaddr sa; 349 u_char *carpaddr = NULL; 350 uint8_t linkhdr[LLE_MAX_LINKHDR]; 351 size_t linkhdrsize; 352 struct route ro; 353 int error; 354 355 if (sip == NULL) { 356 /* 357 * The caller did not supply a source address, try to find 358 * a compatible one among those assigned to this interface. 359 */ 360 struct ifaddr *ifa; 361 362 IF_ADDR_RLOCK(ifp); 363 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 364 if (ifa->ifa_addr->sa_family != AF_INET) 365 continue; 366 367 if (ifa->ifa_carp) { 368 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) 369 continue; 370 sip = &IA_SIN(ifa)->sin_addr; 371 } else { 372 carpaddr = NULL; 373 sip = &IA_SIN(ifa)->sin_addr; 374 } 375 376 if (0 == ((sip->s_addr ^ tip->s_addr) & 377 IA_MASKSIN(ifa)->sin_addr.s_addr)) 378 break; /* found it. */ 379 } 380 IF_ADDR_RUNLOCK(ifp); 381 if (sip == NULL) { 382 printf("%s: cannot find matching address\n", __func__); 383 return; 384 } 385 } 386 if (enaddr == NULL) 387 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); 388 389 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) 390 return; 391 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 392 2 * ifp->if_addrlen; 393 m->m_pkthdr.len = m->m_len; 394 M_ALIGN(m, m->m_len); 395 ah = mtod(m, struct arphdr *); 396 bzero((caddr_t)ah, m->m_len); 397 #ifdef MAC 398 mac_netinet_arp_send(ifp, m); 399 #endif 400 ah->ar_pro = htons(ETHERTYPE_IP); 401 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 402 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 403 ah->ar_op = htons(ARPOP_REQUEST); 404 bcopy(enaddr, ar_sha(ah), ah->ar_hln); 405 bcopy(sip, ar_spa(ah), ah->ar_pln); 406 bcopy(tip, ar_tpa(ah), ah->ar_pln); 407 sa.sa_family = AF_ARP; 408 sa.sa_len = 2; 409 410 /* Calculate link header for sending frame */ 411 bzero(&ro, sizeof(ro)); 412 linkhdrsize = sizeof(linkhdr); 413 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); 414 if (error != 0 && error != EAFNOSUPPORT) { 415 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 416 if_name(ifp), error); 417 return; 418 } 419 420 ro.ro_prepend = linkhdr; 421 ro.ro_plen = linkhdrsize; 422 ro.ro_flags = 0; 423 424 m->m_flags |= M_BCAST; 425 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 426 (*ifp->if_output)(ifp, m, &sa, &ro); 427 ARPSTAT_INC(txrequests); 428 } 429 430 431 /* 432 * Resolve an IP address into an ethernet address - heavy version. 433 * Used internally by arpresolve(). 434 * We have already checked than we can't use existing lle without 435 * modification so we have to acquire LLE_EXCLUSIVE lle lock. 436 * 437 * On success, desten and flags are filled in and the function returns 0; 438 * If the packet must be held pending resolution, we return EWOULDBLOCK 439 * On other errors, we return the corresponding error code. 440 * Note that m_freem() handles NULL. 441 */ 442 static int 443 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, 444 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 445 struct llentry **plle) 446 { 447 struct llentry *la = NULL, *la_tmp; 448 struct mbuf *curr = NULL; 449 struct mbuf *next = NULL; 450 int error, renew; 451 char *lladdr; 452 int ll_len; 453 454 if (pflags != NULL) 455 *pflags = 0; 456 if (plle != NULL) 457 *plle = NULL; 458 459 if ((flags & LLE_CREATE) == 0) { 460 IF_AFDATA_RLOCK(ifp); 461 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 462 IF_AFDATA_RUNLOCK(ifp); 463 } 464 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { 465 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 466 if (la == NULL) { 467 char addrbuf[INET_ADDRSTRLEN]; 468 469 log(LOG_DEBUG, 470 "arpresolve: can't allocate llinfo for %s on %s\n", 471 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), 472 if_name(ifp)); 473 m_freem(m); 474 return (EINVAL); 475 } 476 477 IF_AFDATA_WLOCK(ifp); 478 LLE_WLOCK(la); 479 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 480 /* Prefer ANY existing lle over newly-created one */ 481 if (la_tmp == NULL) 482 lltable_link_entry(LLTABLE(ifp), la); 483 IF_AFDATA_WUNLOCK(ifp); 484 if (la_tmp != NULL) { 485 lltable_free_entry(LLTABLE(ifp), la); 486 la = la_tmp; 487 } 488 } 489 if (la == NULL) { 490 m_freem(m); 491 return (EINVAL); 492 } 493 494 if ((la->la_flags & LLE_VALID) && 495 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 496 if (flags & LLE_ADDRONLY) { 497 lladdr = la->ll_addr; 498 ll_len = ifp->if_addrlen; 499 } else { 500 lladdr = la->r_linkdata; 501 ll_len = la->r_hdrlen; 502 } 503 bcopy(lladdr, desten, ll_len); 504 505 /* Check if we have feedback request from arptimer() */ 506 if (la->r_skip_req != 0) { 507 LLE_REQ_LOCK(la); 508 la->r_skip_req = 0; /* Notify that entry was used */ 509 LLE_REQ_UNLOCK(la); 510 } 511 if (pflags != NULL) 512 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 513 if (plle) { 514 LLE_ADDREF(la); 515 *plle = la; 516 } 517 LLE_WUNLOCK(la); 518 return (0); 519 } 520 521 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 522 /* 523 * There is an arptab entry, but no ethernet address 524 * response yet. Add the mbuf to the list, dropping 525 * the oldest packet if we have exceeded the system 526 * setting. 527 */ 528 if (m != NULL) { 529 if (la->la_numheld >= V_arp_maxhold) { 530 if (la->la_hold != NULL) { 531 next = la->la_hold->m_nextpkt; 532 m_freem(la->la_hold); 533 la->la_hold = next; 534 la->la_numheld--; 535 ARPSTAT_INC(dropped); 536 } 537 } 538 if (la->la_hold != NULL) { 539 curr = la->la_hold; 540 while (curr->m_nextpkt != NULL) 541 curr = curr->m_nextpkt; 542 curr->m_nextpkt = m; 543 } else 544 la->la_hold = m; 545 la->la_numheld++; 546 } 547 /* 548 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 549 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 550 * if we have already sent arp_maxtries ARP requests. Retransmit the 551 * ARP request, but not faster than one request per second. 552 */ 553 if (la->la_asked < V_arp_maxtries) 554 error = EWOULDBLOCK; /* First request. */ 555 else 556 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 557 558 if (renew) { 559 int canceled; 560 561 LLE_ADDREF(la); 562 la->la_expire = time_uptime; 563 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 564 arptimer, la); 565 if (canceled) 566 LLE_REMREF(la); 567 la->la_asked++; 568 LLE_WUNLOCK(la); 569 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 570 return (error); 571 } 572 573 LLE_WUNLOCK(la); 574 return (error); 575 } 576 577 /* 578 * Resolve an IP address into an ethernet address. 579 */ 580 int 581 arpresolve_addr(struct ifnet *ifp, int flags, const struct sockaddr *dst, 582 char *desten, uint32_t *pflags, struct llentry **plle) 583 { 584 int error; 585 586 flags |= LLE_ADDRONLY; 587 error = arpresolve_full(ifp, 0, flags, NULL, dst, desten, pflags, plle); 588 return (error); 589 } 590 591 592 /* 593 * Lookups link header based on an IP address. 594 * On input: 595 * ifp is the interface we use 596 * is_gw != 0 if @dst represents gateway to some destination 597 * m is the mbuf. May be NULL if we don't have a packet. 598 * dst is the next hop, 599 * desten is the storage to put LL header. 600 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 601 * 602 * On success, full/partial link header and flags are filled in and 603 * the function returns 0. 604 * If the packet must be held pending resolution, we return EWOULDBLOCK 605 * On other errors, we return the corresponding error code. 606 * Note that m_freem() handles NULL. 607 */ 608 int 609 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 610 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 611 struct llentry **plle) 612 { 613 struct llentry *la = NULL; 614 615 if (pflags != NULL) 616 *pflags = 0; 617 if (plle != NULL) 618 *plle = NULL; 619 620 if (m != NULL) { 621 if (m->m_flags & M_BCAST) { 622 /* broadcast */ 623 (void)memcpy(desten, 624 ifp->if_broadcastaddr, ifp->if_addrlen); 625 return (0); 626 } 627 if (m->m_flags & M_MCAST) { 628 /* multicast */ 629 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 630 return (0); 631 } 632 } 633 634 IF_AFDATA_RLOCK(ifp); 635 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 636 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 637 /* Entry found, let's copy lle info */ 638 bcopy(la->r_linkdata, desten, la->r_hdrlen); 639 if (pflags != NULL) 640 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 641 /* Check if we have feedback request from arptimer() */ 642 if (la->r_skip_req != 0) { 643 LLE_REQ_LOCK(la); 644 la->r_skip_req = 0; /* Notify that entry was used */ 645 LLE_REQ_UNLOCK(la); 646 } 647 if (plle) { 648 LLE_ADDREF(la); 649 *plle = la; 650 LLE_WUNLOCK(la); 651 } 652 IF_AFDATA_RUNLOCK(ifp); 653 return (0); 654 } 655 if (plle && la) 656 LLE_WUNLOCK(la); 657 IF_AFDATA_RUNLOCK(ifp); 658 659 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 660 desten, pflags, plle)); 661 } 662 663 /* 664 * Common length and type checks are done here, 665 * then the protocol-specific routine is called. 666 */ 667 static void 668 arpintr(struct mbuf *m) 669 { 670 struct arphdr *ar; 671 struct ifnet *ifp; 672 char *layer; 673 int hlen; 674 675 ifp = m->m_pkthdr.rcvif; 676 677 if (m->m_len < sizeof(struct arphdr) && 678 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 679 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 680 if_name(ifp)); 681 return; 682 } 683 ar = mtod(m, struct arphdr *); 684 685 /* Check if length is sufficient */ 686 if (m->m_len < arphdr_len(ar)) { 687 m = m_pullup(m, arphdr_len(ar)); 688 if (m == NULL) { 689 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 690 if_name(ifp)); 691 return; 692 } 693 ar = mtod(m, struct arphdr *); 694 } 695 696 hlen = 0; 697 layer = ""; 698 switch (ntohs(ar->ar_hrd)) { 699 case ARPHRD_ETHER: 700 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 701 layer = "ethernet"; 702 break; 703 case ARPHRD_IEEE802: 704 hlen = 6; /* RFC 1390, FDDI_ADDR_LEN */ 705 layer = "fddi"; 706 break; 707 case ARPHRD_ARCNET: 708 hlen = 1; /* RFC 1201, ARC_ADDR_LEN */ 709 layer = "arcnet"; 710 break; 711 case ARPHRD_INFINIBAND: 712 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 713 layer = "infiniband"; 714 break; 715 case ARPHRD_IEEE1394: 716 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 717 layer = "firewire"; 718 719 /* 720 * Restrict too long hardware addresses. 721 * Currently we are capable of handling 20-byte 722 * addresses ( sizeof(lle->ll_addr) ) 723 */ 724 if (ar->ar_hln >= 20) 725 hlen = 16; 726 break; 727 default: 728 ARP_LOG(LOG_NOTICE, 729 "packet with unknown hardware format 0x%02d received on " 730 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 731 m_freem(m); 732 return; 733 } 734 735 if (hlen != 0 && hlen != ar->ar_hln) { 736 ARP_LOG(LOG_NOTICE, 737 "packet with invalid %s address length %d received on %s\n", 738 layer, ar->ar_hln, if_name(ifp)); 739 m_freem(m); 740 return; 741 } 742 743 ARPSTAT_INC(received); 744 switch (ntohs(ar->ar_pro)) { 745 #ifdef INET 746 case ETHERTYPE_IP: 747 in_arpinput(m); 748 return; 749 #endif 750 } 751 m_freem(m); 752 } 753 754 #ifdef INET 755 /* 756 * ARP for Internet protocols on 10 Mb/s Ethernet. 757 * Algorithm is that given in RFC 826. 758 * In addition, a sanity check is performed on the sender 759 * protocol address, to catch impersonators. 760 * We no longer handle negotiations for use of trailer protocol: 761 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 762 * along with IP replies if we wanted trailers sent to us, 763 * and also sent them in response to IP replies. 764 * This allowed either end to announce the desire to receive 765 * trailer packets. 766 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 767 * but formerly didn't normally send requests. 768 */ 769 static int log_arp_wrong_iface = 1; 770 static int log_arp_movements = 1; 771 static int log_arp_permanent_modify = 1; 772 static int allow_multicast = 0; 773 774 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 775 &log_arp_wrong_iface, 0, 776 "log arp packets arriving on the wrong interface"); 777 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 778 &log_arp_movements, 0, 779 "log arp replies from MACs different than the one in the cache"); 780 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 781 &log_arp_permanent_modify, 0, 782 "log arp replies from MACs different than the one in the permanent arp entry"); 783 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 784 &allow_multicast, 0, "accept multicast addresses"); 785 786 static void 787 in_arpinput(struct mbuf *m) 788 { 789 struct rm_priotracker in_ifa_tracker; 790 struct arphdr *ah; 791 struct ifnet *ifp = m->m_pkthdr.rcvif; 792 struct llentry *la = NULL, *la_tmp; 793 struct ifaddr *ifa; 794 struct in_ifaddr *ia; 795 struct sockaddr sa; 796 struct in_addr isaddr, itaddr, myaddr; 797 u_int8_t *enaddr = NULL; 798 int op; 799 int bridged = 0, is_bridge = 0; 800 int carped; 801 struct sockaddr_in sin; 802 struct sockaddr *dst; 803 struct nhop4_basic nh4; 804 uint8_t linkhdr[LLE_MAX_LINKHDR]; 805 struct route ro; 806 size_t linkhdrsize; 807 int lladdr_off; 808 int error; 809 char addrbuf[INET_ADDRSTRLEN]; 810 811 sin.sin_len = sizeof(struct sockaddr_in); 812 sin.sin_family = AF_INET; 813 sin.sin_addr.s_addr = 0; 814 815 if (ifp->if_bridge) 816 bridged = 1; 817 if (ifp->if_type == IFT_BRIDGE) 818 is_bridge = 1; 819 820 /* 821 * We already have checked that mbuf contains enough contiguous data 822 * to hold entire arp message according to the arp header. 823 */ 824 ah = mtod(m, struct arphdr *); 825 826 /* 827 * ARP is only for IPv4 so we can reject packets with 828 * a protocol length not equal to an IPv4 address. 829 */ 830 if (ah->ar_pln != sizeof(struct in_addr)) { 831 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 832 sizeof(struct in_addr)); 833 goto drop; 834 } 835 836 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 837 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 838 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 839 goto drop; 840 } 841 842 op = ntohs(ah->ar_op); 843 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 844 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 845 846 if (op == ARPOP_REPLY) 847 ARPSTAT_INC(rxreplies); 848 849 /* 850 * For a bridge, we want to check the address irrespective 851 * of the receive interface. (This will change slightly 852 * when we have clusters of interfaces). 853 */ 854 IN_IFADDR_RLOCK(&in_ifa_tracker); 855 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 856 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 857 ia->ia_ifp == ifp) && 858 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 859 (ia->ia_ifa.ifa_carp == NULL || 860 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 861 ifa_ref(&ia->ia_ifa); 862 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 863 goto match; 864 } 865 } 866 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 867 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 868 ia->ia_ifp == ifp) && 869 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 870 ifa_ref(&ia->ia_ifa); 871 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 872 goto match; 873 } 874 875 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 876 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 877 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 878 addr == ia->ia_addr.sin_addr.s_addr) 879 /* 880 * Check the case when bridge shares its MAC address with 881 * some of its children, so packets are claimed by bridge 882 * itself (bridge_input() does it first), but they are really 883 * meant to be destined to the bridge member. 884 */ 885 if (is_bridge) { 886 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 887 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 888 ifa_ref(&ia->ia_ifa); 889 ifp = ia->ia_ifp; 890 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 891 goto match; 892 } 893 } 894 } 895 #undef BDG_MEMBER_MATCHES_ARP 896 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 897 898 /* 899 * No match, use the first inet address on the receive interface 900 * as a dummy address for the rest of the function. 901 */ 902 IF_ADDR_RLOCK(ifp); 903 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 904 if (ifa->ifa_addr->sa_family == AF_INET && 905 (ifa->ifa_carp == NULL || 906 (*carp_iamatch_p)(ifa, &enaddr))) { 907 ia = ifatoia(ifa); 908 ifa_ref(ifa); 909 IF_ADDR_RUNLOCK(ifp); 910 goto match; 911 } 912 IF_ADDR_RUNLOCK(ifp); 913 914 /* 915 * If bridging, fall back to using any inet address. 916 */ 917 IN_IFADDR_RLOCK(&in_ifa_tracker); 918 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 919 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 920 goto drop; 921 } 922 ifa_ref(&ia->ia_ifa); 923 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 924 match: 925 if (!enaddr) 926 enaddr = (u_int8_t *)IF_LLADDR(ifp); 927 carped = (ia->ia_ifa.ifa_carp != NULL); 928 myaddr = ia->ia_addr.sin_addr; 929 ifa_free(&ia->ia_ifa); 930 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 931 goto drop; /* it's from me, ignore it. */ 932 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 933 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 934 "%s!\n", inet_ntoa_r(isaddr, addrbuf)); 935 goto drop; 936 } 937 938 if (ifp->if_addrlen != ah->ar_hln) { 939 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 940 "i/f %d (ignored)\n", ifp->if_addrlen, 941 (u_char *) ar_sha(ah), ":", ah->ar_hln, 942 ifp->if_addrlen); 943 goto drop; 944 } 945 946 /* 947 * Warn if another host is using the same IP address, but only if the 948 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 949 * case we suppress the warning to avoid false positive complaints of 950 * potential misconfiguration. 951 */ 952 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 953 myaddr.s_addr != 0) { 954 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 955 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 956 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); 957 itaddr = myaddr; 958 ARPSTAT_INC(dupips); 959 goto reply; 960 } 961 if (ifp->if_flags & IFF_STATICARP) 962 goto reply; 963 964 bzero(&sin, sizeof(sin)); 965 sin.sin_len = sizeof(struct sockaddr_in); 966 sin.sin_family = AF_INET; 967 sin.sin_addr = isaddr; 968 dst = (struct sockaddr *)&sin; 969 IF_AFDATA_RLOCK(ifp); 970 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 971 IF_AFDATA_RUNLOCK(ifp); 972 if (la != NULL) 973 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 974 else if (itaddr.s_addr == myaddr.s_addr) { 975 /* 976 * Request/reply to our address, but no lle exists yet. 977 * Calculate full link prepend to use in lle. 978 */ 979 linkhdrsize = sizeof(linkhdr); 980 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 981 &linkhdrsize, &lladdr_off) != 0) 982 goto reply; 983 984 /* Allocate new entry */ 985 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 986 if (la == NULL) { 987 988 /* 989 * lle creation may fail if source address belongs 990 * to non-directly connected subnet. However, we 991 * will try to answer the request instead of dropping 992 * frame. 993 */ 994 goto reply; 995 } 996 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 997 lladdr_off); 998 999 IF_AFDATA_WLOCK(ifp); 1000 LLE_WLOCK(la); 1001 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1002 1003 /* 1004 * Check if lle still does not exists. 1005 * If it does, that means that we either 1006 * 1) have configured it explicitly, via 1007 * 1a) 'arp -s' static entry or 1008 * 1b) interface address static record 1009 * or 1010 * 2) it was the result of sending first packet to-host 1011 * or 1012 * 3) it was another arp reply packet we handled in 1013 * different thread. 1014 * 1015 * In all cases except 3) we definitely need to prefer 1016 * existing lle. For the sake of simplicity, prefer any 1017 * existing lle over newly-create one. 1018 */ 1019 if (la_tmp == NULL) 1020 lltable_link_entry(LLTABLE(ifp), la); 1021 IF_AFDATA_WUNLOCK(ifp); 1022 1023 if (la_tmp == NULL) { 1024 arp_mark_lle_reachable(la); 1025 LLE_WUNLOCK(la); 1026 } else { 1027 /* Free newly-create entry and handle packet */ 1028 lltable_free_entry(LLTABLE(ifp), la); 1029 la = la_tmp; 1030 la_tmp = NULL; 1031 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1032 /* arp_check_update_lle() returns @la unlocked */ 1033 } 1034 la = NULL; 1035 } 1036 reply: 1037 if (op != ARPOP_REQUEST) 1038 goto drop; 1039 ARPSTAT_INC(rxrequests); 1040 1041 if (itaddr.s_addr == myaddr.s_addr) { 1042 /* Shortcut.. the receiving interface is the target. */ 1043 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1044 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1045 } else { 1046 struct llentry *lle = NULL; 1047 1048 sin.sin_addr = itaddr; 1049 IF_AFDATA_RLOCK(ifp); 1050 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1051 IF_AFDATA_RUNLOCK(ifp); 1052 1053 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1054 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1055 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1056 LLE_RUNLOCK(lle); 1057 } else { 1058 1059 if (lle != NULL) 1060 LLE_RUNLOCK(lle); 1061 1062 if (!V_arp_proxyall) 1063 goto drop; 1064 1065 /* XXX MRT use table 0 for arp reply */ 1066 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1067 goto drop; 1068 1069 /* 1070 * Don't send proxies for nodes on the same interface 1071 * as this one came out of, or we'll get into a fight 1072 * over who claims what Ether address. 1073 */ 1074 if (nh4.nh_ifp == ifp) 1075 goto drop; 1076 1077 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1078 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1079 1080 /* 1081 * Also check that the node which sent the ARP packet 1082 * is on the interface we expect it to be on. This 1083 * avoids ARP chaos if an interface is connected to the 1084 * wrong network. 1085 */ 1086 1087 /* XXX MRT use table 0 for arp checks */ 1088 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1089 goto drop; 1090 if (nh4.nh_ifp != ifp) { 1091 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1092 " from %s via %s\n", 1093 inet_ntoa_r(isaddr, addrbuf), 1094 ifp->if_xname); 1095 goto drop; 1096 } 1097 1098 #ifdef DEBUG_PROXY 1099 printf("arp: proxying for %s\n", 1100 inet_ntoa_r(itaddr, addrbuf)); 1101 #endif 1102 } 1103 } 1104 1105 if (itaddr.s_addr == myaddr.s_addr && 1106 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1107 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1108 #ifdef DEBUG_LINKLOCAL 1109 printf("arp: sending reply for link-local addr %s\n", 1110 inet_ntoa_r(itaddr, addrbuf)); 1111 #endif 1112 m->m_flags |= M_BCAST; 1113 m->m_flags &= ~M_MCAST; 1114 } else { 1115 /* default behaviour; never reply by broadcast. */ 1116 m->m_flags &= ~(M_BCAST|M_MCAST); 1117 } 1118 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1119 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1120 ah->ar_op = htons(ARPOP_REPLY); 1121 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1122 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1123 m->m_pkthdr.len = m->m_len; 1124 m->m_pkthdr.rcvif = NULL; 1125 sa.sa_family = AF_ARP; 1126 sa.sa_len = 2; 1127 1128 /* Calculate link header for sending frame */ 1129 bzero(&ro, sizeof(ro)); 1130 linkhdrsize = sizeof(linkhdr); 1131 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1132 1133 /* 1134 * arp_fillheader() may fail due to lack of support inside encap request 1135 * routing. This is not necessary an error, AF_ARP can/should be handled 1136 * by if_output(). 1137 */ 1138 if (error != 0 && error != EAFNOSUPPORT) { 1139 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1140 if_name(ifp), error); 1141 return; 1142 } 1143 1144 ro.ro_prepend = linkhdr; 1145 ro.ro_plen = linkhdrsize; 1146 ro.ro_flags = 0; 1147 1148 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1149 (*ifp->if_output)(ifp, m, &sa, &ro); 1150 ARPSTAT_INC(txreplies); 1151 return; 1152 1153 drop: 1154 m_freem(m); 1155 } 1156 #endif 1157 1158 /* 1159 * Checks received arp data against existing @la. 1160 * Updates lle state/performs notification if necessary. 1161 */ 1162 static void 1163 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1164 int bridged, struct llentry *la) 1165 { 1166 struct sockaddr sa; 1167 struct mbuf *m_hold, *m_hold_next; 1168 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1169 size_t linkhdrsize; 1170 int lladdr_off; 1171 char addrbuf[INET_ADDRSTRLEN]; 1172 1173 LLE_WLOCK_ASSERT(la); 1174 1175 /* the following is not an error when doing bridging */ 1176 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1177 if (log_arp_wrong_iface) 1178 ARP_LOG(LOG_WARNING, "%s is on %s " 1179 "but got reply from %*D on %s\n", 1180 inet_ntoa_r(isaddr, addrbuf), 1181 la->lle_tbl->llt_ifp->if_xname, 1182 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1183 ifp->if_xname); 1184 LLE_WUNLOCK(la); 1185 return; 1186 } 1187 if ((la->la_flags & LLE_VALID) && 1188 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1189 if (la->la_flags & LLE_STATIC) { 1190 LLE_WUNLOCK(la); 1191 if (log_arp_permanent_modify) 1192 ARP_LOG(LOG_ERR, 1193 "%*D attempts to modify " 1194 "permanent entry for %s on %s\n", 1195 ifp->if_addrlen, 1196 (u_char *)ar_sha(ah), ":", 1197 inet_ntoa_r(isaddr, addrbuf), 1198 ifp->if_xname); 1199 return; 1200 } 1201 if (log_arp_movements) { 1202 ARP_LOG(LOG_INFO, "%s moved from %*D " 1203 "to %*D on %s\n", 1204 inet_ntoa_r(isaddr, addrbuf), 1205 ifp->if_addrlen, 1206 (u_char *)la->ll_addr, ":", 1207 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1208 ifp->if_xname); 1209 } 1210 } 1211 1212 /* Calculate full link prepend to use in lle */ 1213 linkhdrsize = sizeof(linkhdr); 1214 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1215 &linkhdrsize, &lladdr_off) != 0) 1216 return; 1217 1218 /* Check if something has changed */ 1219 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1220 (la->la_flags & LLE_VALID) == 0) { 1221 /* Try to perform LLE update */ 1222 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1223 lladdr_off) == 0) 1224 return; 1225 1226 /* Clear fast path feedback request if set */ 1227 la->r_skip_req = 0; 1228 } 1229 1230 arp_mark_lle_reachable(la); 1231 1232 /* 1233 * The packets are all freed within the call to the output 1234 * routine. 1235 * 1236 * NB: The lock MUST be released before the call to the 1237 * output routine. 1238 */ 1239 if (la->la_hold != NULL) { 1240 m_hold = la->la_hold; 1241 la->la_hold = NULL; 1242 la->la_numheld = 0; 1243 lltable_fill_sa_entry(la, &sa); 1244 LLE_WUNLOCK(la); 1245 for (; m_hold != NULL; m_hold = m_hold_next) { 1246 m_hold_next = m_hold->m_nextpkt; 1247 m_hold->m_nextpkt = NULL; 1248 /* Avoid confusing lower layers. */ 1249 m_clrprotoflags(m_hold); 1250 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1251 } 1252 } else 1253 LLE_WUNLOCK(la); 1254 } 1255 1256 static void 1257 arp_mark_lle_reachable(struct llentry *la) 1258 { 1259 int canceled, wtime; 1260 1261 LLE_WLOCK_ASSERT(la); 1262 1263 la->ln_state = ARP_LLINFO_REACHABLE; 1264 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1265 1266 if (!(la->la_flags & LLE_STATIC)) { 1267 LLE_ADDREF(la); 1268 la->la_expire = time_uptime + V_arpt_keep; 1269 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1270 if (wtime < 0) 1271 wtime = V_arpt_keep; 1272 canceled = callout_reset(&la->lle_timer, 1273 hz * wtime, arptimer, la); 1274 if (canceled) 1275 LLE_REMREF(la); 1276 } 1277 la->la_asked = 0; 1278 la->la_preempt = V_arp_maxtries; 1279 } 1280 1281 /* 1282 * Add pernament link-layer record for given interface address. 1283 */ 1284 static __noinline void 1285 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1286 { 1287 struct llentry *lle, *lle_tmp; 1288 1289 /* 1290 * Interface address LLE record is considered static 1291 * because kernel code relies on LLE_STATIC flag to check 1292 * if these entries can be rewriten by arp updates. 1293 */ 1294 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1295 if (lle == NULL) { 1296 log(LOG_INFO, "arp_ifinit: cannot create arp " 1297 "entry for interface address\n"); 1298 return; 1299 } 1300 1301 IF_AFDATA_WLOCK(ifp); 1302 LLE_WLOCK(lle); 1303 /* Unlink any entry if exists */ 1304 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1305 if (lle_tmp != NULL) 1306 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1307 1308 lltable_link_entry(LLTABLE(ifp), lle); 1309 IF_AFDATA_WUNLOCK(ifp); 1310 1311 if (lle_tmp != NULL) 1312 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1313 1314 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1315 LLE_WUNLOCK(lle); 1316 if (lle_tmp != NULL) 1317 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1318 } 1319 1320 /* 1321 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1322 * of valid values. 1323 */ 1324 static int 1325 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1326 { 1327 int error; 1328 int rexmit_count = *(int *)arg1; 1329 1330 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1331 1332 /* Enforce limits on any new value that may have been set. */ 1333 if (!error && req->newptr) { 1334 /* A new value was set. */ 1335 if (rexmit_count < 0) { 1336 rexmit_count = 0; 1337 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1338 rexmit_count = MAX_GARP_RETRANSMITS; 1339 } 1340 *(int *)arg1 = rexmit_count; 1341 } 1342 1343 return (error); 1344 } 1345 1346 /* 1347 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1348 * retransmit it again. A pending callout owns a reference to the ifa. 1349 */ 1350 static void 1351 garp_rexmit(void *arg) 1352 { 1353 struct in_ifaddr *ia = arg; 1354 1355 if (callout_pending(&ia->ia_garp_timer) || 1356 !callout_active(&ia->ia_garp_timer)) { 1357 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1358 ifa_free(&ia->ia_ifa); 1359 return; 1360 } 1361 1362 /* 1363 * Drop lock while the ARP request is generated. 1364 */ 1365 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1366 1367 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1368 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1369 1370 /* 1371 * Increment the count of retransmissions. If the count has reached the 1372 * maximum value, stop sending the GARP packets. Otherwise, schedule 1373 * the callout to retransmit another GARP packet. 1374 */ 1375 ++ia->ia_garp_count; 1376 if (ia->ia_garp_count >= garp_rexmit_count) { 1377 ifa_free(&ia->ia_ifa); 1378 } else { 1379 int rescheduled; 1380 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1381 rescheduled = callout_reset(&ia->ia_garp_timer, 1382 (1 << ia->ia_garp_count) * hz, 1383 garp_rexmit, ia); 1384 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1385 if (rescheduled) { 1386 ifa_free(&ia->ia_ifa); 1387 } 1388 } 1389 } 1390 1391 /* 1392 * Start the GARP retransmit timer. 1393 * 1394 * A single GARP is always transmitted when an IPv4 address is added 1395 * to an interface and that is usually sufficient. However, in some 1396 * circumstances, such as when a shared address is passed between 1397 * cluster nodes, this single GARP may occasionally be dropped or 1398 * lost. This can lead to neighbors on the network link working with a 1399 * stale ARP cache and sending packets destined for that address to 1400 * the node that previously owned the address, which may not respond. 1401 * 1402 * To avoid this situation, GARP retransmits can be enabled by setting 1403 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1404 * than zero. The setting represents the maximum number of 1405 * retransmissions. The interval between retransmissions is calculated 1406 * using an exponential backoff algorithm, doubling each time, so the 1407 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1408 */ 1409 static void 1410 garp_timer_start(struct ifaddr *ifa) 1411 { 1412 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1413 1414 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1415 ia->ia_garp_count = 0; 1416 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1417 garp_rexmit, ia) == 0) { 1418 ifa_ref(ifa); 1419 } 1420 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1421 } 1422 1423 void 1424 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1425 { 1426 const struct sockaddr_in *dst_in; 1427 const struct sockaddr *dst; 1428 1429 if (ifa->ifa_carp != NULL) 1430 return; 1431 1432 dst = ifa->ifa_addr; 1433 dst_in = (const struct sockaddr_in *)dst; 1434 1435 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1436 return; 1437 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1438 if (garp_rexmit_count > 0) { 1439 garp_timer_start(ifa); 1440 } 1441 1442 arp_add_ifa_lle(ifp, dst); 1443 } 1444 1445 void 1446 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1447 { 1448 1449 if (ntohl(addr.s_addr) != INADDR_ANY) 1450 arprequest(ifp, &addr, &addr, enaddr); 1451 } 1452 1453 /* 1454 * Sends gratuitous ARPs for each ifaddr to notify other 1455 * nodes about the address change. 1456 */ 1457 static __noinline void 1458 arp_handle_ifllchange(struct ifnet *ifp) 1459 { 1460 struct ifaddr *ifa; 1461 1462 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1463 if (ifa->ifa_addr->sa_family == AF_INET) 1464 arp_ifinit(ifp, ifa); 1465 } 1466 } 1467 1468 /* 1469 * A handler for interface link layer address change event. 1470 */ 1471 static void 1472 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1473 { 1474 1475 lltable_update_ifaddr(LLTABLE(ifp)); 1476 1477 if ((ifp->if_flags & IFF_UP) != 0) 1478 arp_handle_ifllchange(ifp); 1479 } 1480 1481 static void 1482 vnet_arp_init(void) 1483 { 1484 1485 if (IS_DEFAULT_VNET(curvnet)) { 1486 netisr_register(&arp_nh); 1487 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1488 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1489 } 1490 #ifdef VIMAGE 1491 else 1492 netisr_register_vnet(&arp_nh); 1493 #endif 1494 } 1495 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1496 vnet_arp_init, 0); 1497 1498 #ifdef VIMAGE 1499 /* 1500 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1501 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1502 */ 1503 static void 1504 vnet_arp_destroy(__unused void *arg) 1505 { 1506 1507 netisr_unregister_vnet(&arp_nh); 1508 } 1509 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1510 vnet_arp_destroy, NULL); 1511 #endif
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