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("$FreeBSD$"); 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 log(LOG_DEBUG, 468 "arpresolve: can't allocate llinfo for %s on %s\n", 469 inet_ntoa(SIN(dst)->sin_addr), if_name(ifp)); 470 m_freem(m); 471 return (EINVAL); 472 } 473 474 IF_AFDATA_WLOCK(ifp); 475 LLE_WLOCK(la); 476 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 477 /* Prefer ANY existing lle over newly-created one */ 478 if (la_tmp == NULL) 479 lltable_link_entry(LLTABLE(ifp), la); 480 IF_AFDATA_WUNLOCK(ifp); 481 if (la_tmp != NULL) { 482 lltable_free_entry(LLTABLE(ifp), la); 483 la = la_tmp; 484 } 485 } 486 if (la == NULL) { 487 m_freem(m); 488 return (EINVAL); 489 } 490 491 if ((la->la_flags & LLE_VALID) && 492 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { 493 if (flags & LLE_ADDRONLY) { 494 lladdr = la->ll_addr; 495 ll_len = ifp->if_addrlen; 496 } else { 497 lladdr = la->r_linkdata; 498 ll_len = la->r_hdrlen; 499 } 500 bcopy(lladdr, desten, ll_len); 501 502 /* Check if we have feedback request from arptimer() */ 503 if (la->r_skip_req != 0) { 504 LLE_REQ_LOCK(la); 505 la->r_skip_req = 0; /* Notify that entry was used */ 506 LLE_REQ_UNLOCK(la); 507 } 508 if (pflags != NULL) 509 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); 510 if (plle) { 511 LLE_ADDREF(la); 512 *plle = la; 513 } 514 LLE_WUNLOCK(la); 515 return (0); 516 } 517 518 renew = (la->la_asked == 0 || la->la_expire != time_uptime); 519 /* 520 * There is an arptab entry, but no ethernet address 521 * response yet. Add the mbuf to the list, dropping 522 * the oldest packet if we have exceeded the system 523 * setting. 524 */ 525 if (m != NULL) { 526 if (la->la_numheld >= V_arp_maxhold) { 527 if (la->la_hold != NULL) { 528 next = la->la_hold->m_nextpkt; 529 m_freem(la->la_hold); 530 la->la_hold = next; 531 la->la_numheld--; 532 ARPSTAT_INC(dropped); 533 } 534 } 535 if (la->la_hold != NULL) { 536 curr = la->la_hold; 537 while (curr->m_nextpkt != NULL) 538 curr = curr->m_nextpkt; 539 curr->m_nextpkt = m; 540 } else 541 la->la_hold = m; 542 la->la_numheld++; 543 } 544 /* 545 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 546 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 547 * if we have already sent arp_maxtries ARP requests. Retransmit the 548 * ARP request, but not faster than one request per second. 549 */ 550 if (la->la_asked < V_arp_maxtries) 551 error = EWOULDBLOCK; /* First request. */ 552 else 553 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; 554 555 if (renew) { 556 int canceled; 557 558 LLE_ADDREF(la); 559 la->la_expire = time_uptime; 560 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, 561 arptimer, la); 562 if (canceled) 563 LLE_REMREF(la); 564 la->la_asked++; 565 LLE_WUNLOCK(la); 566 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); 567 return (error); 568 } 569 570 LLE_WUNLOCK(la); 571 return (error); 572 } 573 574 /* 575 * Resolve an IP address into an ethernet address. 576 */ 577 int 578 arpresolve_addr(struct ifnet *ifp, int flags, const struct sockaddr *dst, 579 char *desten, uint32_t *pflags, struct llentry **plle) 580 { 581 int error; 582 583 flags |= LLE_ADDRONLY; 584 error = arpresolve_full(ifp, 0, flags, NULL, dst, desten, pflags, plle); 585 return (error); 586 } 587 588 589 /* 590 * Lookups link header based on an IP address. 591 * On input: 592 * ifp is the interface we use 593 * is_gw != 0 if @dst represents gateway to some destination 594 * m is the mbuf. May be NULL if we don't have a packet. 595 * dst is the next hop, 596 * desten is the storage to put LL header. 597 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR 598 * 599 * On success, full/partial link header and flags are filled in and 600 * the function returns 0. 601 * If the packet must be held pending resolution, we return EWOULDBLOCK 602 * On other errors, we return the corresponding error code. 603 * Note that m_freem() handles NULL. 604 */ 605 int 606 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, 607 const struct sockaddr *dst, u_char *desten, uint32_t *pflags, 608 struct llentry **plle) 609 { 610 struct llentry *la = NULL; 611 612 if (pflags != NULL) 613 *pflags = 0; 614 if (plle != NULL) 615 *plle = NULL; 616 617 if (m != NULL) { 618 if (m->m_flags & M_BCAST) { 619 /* broadcast */ 620 (void)memcpy(desten, 621 ifp->if_broadcastaddr, ifp->if_addrlen); 622 return (0); 623 } 624 if (m->m_flags & M_MCAST) { 625 /* multicast */ 626 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 627 return (0); 628 } 629 } 630 631 IF_AFDATA_RLOCK(ifp); 632 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); 633 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { 634 /* Entry found, let's copy lle info */ 635 bcopy(la->r_linkdata, desten, la->r_hdrlen); 636 if (pflags != NULL) 637 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); 638 /* Check if we have feedback request from arptimer() */ 639 if (la->r_skip_req != 0) { 640 LLE_REQ_LOCK(la); 641 la->r_skip_req = 0; /* Notify that entry was used */ 642 LLE_REQ_UNLOCK(la); 643 } 644 if (plle) { 645 LLE_ADDREF(la); 646 *plle = la; 647 LLE_WUNLOCK(la); 648 } 649 IF_AFDATA_RUNLOCK(ifp); 650 return (0); 651 } 652 if (plle && la) 653 LLE_WUNLOCK(la); 654 IF_AFDATA_RUNLOCK(ifp); 655 656 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, 657 desten, pflags, plle)); 658 } 659 660 /* 661 * Common length and type checks are done here, 662 * then the protocol-specific routine is called. 663 */ 664 static void 665 arpintr(struct mbuf *m) 666 { 667 struct arphdr *ar; 668 struct ifnet *ifp; 669 char *layer; 670 int hlen; 671 672 ifp = m->m_pkthdr.rcvif; 673 674 if (m->m_len < sizeof(struct arphdr) && 675 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 676 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", 677 if_name(ifp)); 678 return; 679 } 680 ar = mtod(m, struct arphdr *); 681 682 /* Check if length is sufficient */ 683 if (m->m_len < arphdr_len(ar)) { 684 m = m_pullup(m, arphdr_len(ar)); 685 if (m == NULL) { 686 ARP_LOG(LOG_NOTICE, "short packet received on %s\n", 687 if_name(ifp)); 688 return; 689 } 690 ar = mtod(m, struct arphdr *); 691 } 692 693 hlen = 0; 694 layer = ""; 695 switch (ntohs(ar->ar_hrd)) { 696 case ARPHRD_ETHER: 697 hlen = ETHER_ADDR_LEN; /* RFC 826 */ 698 layer = "ethernet"; 699 break; 700 case ARPHRD_IEEE802: 701 hlen = 6; /* RFC 1390, FDDI_ADDR_LEN */ 702 layer = "fddi"; 703 break; 704 case ARPHRD_ARCNET: 705 hlen = 1; /* RFC 1201, ARC_ADDR_LEN */ 706 layer = "arcnet"; 707 break; 708 case ARPHRD_INFINIBAND: 709 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ 710 layer = "infiniband"; 711 break; 712 case ARPHRD_IEEE1394: 713 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ 714 layer = "firewire"; 715 716 /* 717 * Restrict too long hardware addresses. 718 * Currently we are capable of handling 20-byte 719 * addresses ( sizeof(lle->ll_addr) ) 720 */ 721 if (ar->ar_hln >= 20) 722 hlen = 16; 723 break; 724 default: 725 ARP_LOG(LOG_NOTICE, 726 "packet with unknown hardware format 0x%02d received on " 727 "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); 728 m_freem(m); 729 return; 730 } 731 732 if (hlen != 0 && hlen != ar->ar_hln) { 733 ARP_LOG(LOG_NOTICE, 734 "packet with invalid %s address length %d received on %s\n", 735 layer, ar->ar_hln, if_name(ifp)); 736 m_freem(m); 737 return; 738 } 739 740 ARPSTAT_INC(received); 741 switch (ntohs(ar->ar_pro)) { 742 #ifdef INET 743 case ETHERTYPE_IP: 744 in_arpinput(m); 745 return; 746 #endif 747 } 748 m_freem(m); 749 } 750 751 #ifdef INET 752 /* 753 * ARP for Internet protocols on 10 Mb/s Ethernet. 754 * Algorithm is that given in RFC 826. 755 * In addition, a sanity check is performed on the sender 756 * protocol address, to catch impersonators. 757 * We no longer handle negotiations for use of trailer protocol: 758 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 759 * along with IP replies if we wanted trailers sent to us, 760 * and also sent them in response to IP replies. 761 * This allowed either end to announce the desire to receive 762 * trailer packets. 763 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 764 * but formerly didn't normally send requests. 765 */ 766 static int log_arp_wrong_iface = 1; 767 static int log_arp_movements = 1; 768 static int log_arp_permanent_modify = 1; 769 static int allow_multicast = 0; 770 771 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 772 &log_arp_wrong_iface, 0, 773 "log arp packets arriving on the wrong interface"); 774 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 775 &log_arp_movements, 0, 776 "log arp replies from MACs different than the one in the cache"); 777 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 778 &log_arp_permanent_modify, 0, 779 "log arp replies from MACs different than the one in the permanent arp entry"); 780 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, 781 &allow_multicast, 0, "accept multicast addresses"); 782 783 static void 784 in_arpinput(struct mbuf *m) 785 { 786 struct rm_priotracker in_ifa_tracker; 787 struct arphdr *ah; 788 struct ifnet *ifp = m->m_pkthdr.rcvif; 789 struct llentry *la = NULL, *la_tmp; 790 struct ifaddr *ifa; 791 struct in_ifaddr *ia; 792 struct sockaddr sa; 793 struct in_addr isaddr, itaddr, myaddr; 794 u_int8_t *enaddr = NULL; 795 int op; 796 int bridged = 0, is_bridge = 0; 797 int carped; 798 struct sockaddr_in sin; 799 struct sockaddr *dst; 800 struct nhop4_basic nh4; 801 uint8_t linkhdr[LLE_MAX_LINKHDR]; 802 struct route ro; 803 size_t linkhdrsize; 804 int lladdr_off; 805 int error; 806 807 sin.sin_len = sizeof(struct sockaddr_in); 808 sin.sin_family = AF_INET; 809 sin.sin_addr.s_addr = 0; 810 811 if (ifp->if_bridge) 812 bridged = 1; 813 if (ifp->if_type == IFT_BRIDGE) 814 is_bridge = 1; 815 816 /* 817 * We already have checked that mbuf contains enough contiguous data 818 * to hold entire arp message according to the arp header. 819 */ 820 ah = mtod(m, struct arphdr *); 821 822 /* 823 * ARP is only for IPv4 so we can reject packets with 824 * a protocol length not equal to an IPv4 address. 825 */ 826 if (ah->ar_pln != sizeof(struct in_addr)) { 827 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", 828 sizeof(struct in_addr)); 829 goto drop; 830 } 831 832 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { 833 ARP_LOG(LOG_NOTICE, "%*D is multicast\n", 834 ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); 835 goto drop; 836 } 837 838 op = ntohs(ah->ar_op); 839 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 840 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 841 842 if (op == ARPOP_REPLY) 843 ARPSTAT_INC(rxreplies); 844 845 /* 846 * For a bridge, we want to check the address irrespective 847 * of the receive interface. (This will change slightly 848 * when we have clusters of interfaces). 849 */ 850 IN_IFADDR_RLOCK(&in_ifa_tracker); 851 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 852 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 853 ia->ia_ifp == ifp) && 854 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && 855 (ia->ia_ifa.ifa_carp == NULL || 856 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { 857 ifa_ref(&ia->ia_ifa); 858 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 859 goto match; 860 } 861 } 862 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 863 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || 864 ia->ia_ifp == ifp) && 865 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 866 ifa_ref(&ia->ia_ifa); 867 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 868 goto match; 869 } 870 871 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ 872 (ia->ia_ifp->if_bridge == ifp->if_softc && \ 873 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ 874 addr == ia->ia_addr.sin_addr.s_addr) 875 /* 876 * Check the case when bridge shares its MAC address with 877 * some of its children, so packets are claimed by bridge 878 * itself (bridge_input() does it first), but they are really 879 * meant to be destined to the bridge member. 880 */ 881 if (is_bridge) { 882 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 883 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { 884 ifa_ref(&ia->ia_ifa); 885 ifp = ia->ia_ifp; 886 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 887 goto match; 888 } 889 } 890 } 891 #undef BDG_MEMBER_MATCHES_ARP 892 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 893 894 /* 895 * No match, use the first inet address on the receive interface 896 * as a dummy address for the rest of the function. 897 */ 898 IF_ADDR_RLOCK(ifp); 899 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 900 if (ifa->ifa_addr->sa_family == AF_INET && 901 (ifa->ifa_carp == NULL || 902 (*carp_iamatch_p)(ifa, &enaddr))) { 903 ia = ifatoia(ifa); 904 ifa_ref(ifa); 905 IF_ADDR_RUNLOCK(ifp); 906 goto match; 907 } 908 IF_ADDR_RUNLOCK(ifp); 909 910 /* 911 * If bridging, fall back to using any inet address. 912 */ 913 IN_IFADDR_RLOCK(&in_ifa_tracker); 914 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { 915 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 916 goto drop; 917 } 918 ifa_ref(&ia->ia_ifa); 919 IN_IFADDR_RUNLOCK(&in_ifa_tracker); 920 match: 921 if (!enaddr) 922 enaddr = (u_int8_t *)IF_LLADDR(ifp); 923 carped = (ia->ia_ifa.ifa_carp != NULL); 924 myaddr = ia->ia_addr.sin_addr; 925 ifa_free(&ia->ia_ifa); 926 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 927 goto drop; /* it's from me, ignore it. */ 928 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 929 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " 930 "%s!\n", inet_ntoa(isaddr)); 931 goto drop; 932 } 933 934 if (ifp->if_addrlen != ah->ar_hln) { 935 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " 936 "i/f %d (ignored)\n", ifp->if_addrlen, 937 (u_char *) ar_sha(ah), ":", ah->ar_hln, 938 ifp->if_addrlen); 939 goto drop; 940 } 941 942 /* 943 * Warn if another host is using the same IP address, but only if the 944 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 945 * case we suppress the warning to avoid false positive complaints of 946 * potential misconfiguration. 947 */ 948 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && 949 myaddr.s_addr != 0) { 950 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", 951 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 952 inet_ntoa(isaddr), ifp->if_xname); 953 itaddr = myaddr; 954 ARPSTAT_INC(dupips); 955 goto reply; 956 } 957 if (ifp->if_flags & IFF_STATICARP) 958 goto reply; 959 960 bzero(&sin, sizeof(sin)); 961 sin.sin_len = sizeof(struct sockaddr_in); 962 sin.sin_family = AF_INET; 963 sin.sin_addr = isaddr; 964 dst = (struct sockaddr *)&sin; 965 IF_AFDATA_RLOCK(ifp); 966 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 967 IF_AFDATA_RUNLOCK(ifp); 968 if (la != NULL) 969 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 970 else if (itaddr.s_addr == myaddr.s_addr) { 971 /* 972 * Request/reply to our address, but no lle exists yet. 973 * Calculate full link prepend to use in lle. 974 */ 975 linkhdrsize = sizeof(linkhdr); 976 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 977 &linkhdrsize, &lladdr_off) != 0) 978 goto reply; 979 980 /* Allocate new entry */ 981 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); 982 if (la == NULL) { 983 984 /* 985 * lle creation may fail if source address belongs 986 * to non-directly connected subnet. However, we 987 * will try to answer the request instead of dropping 988 * frame. 989 */ 990 goto reply; 991 } 992 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 993 lladdr_off); 994 995 IF_AFDATA_WLOCK(ifp); 996 LLE_WLOCK(la); 997 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 998 999 /* 1000 * Check if lle still does not exists. 1001 * If it does, that means that we either 1002 * 1) have configured it explicitly, via 1003 * 1a) 'arp -s' static entry or 1004 * 1b) interface address static record 1005 * or 1006 * 2) it was the result of sending first packet to-host 1007 * or 1008 * 3) it was another arp reply packet we handled in 1009 * different thread. 1010 * 1011 * In all cases except 3) we definitely need to prefer 1012 * existing lle. For the sake of simplicity, prefer any 1013 * existing lle over newly-create one. 1014 */ 1015 if (la_tmp == NULL) 1016 lltable_link_entry(LLTABLE(ifp), la); 1017 IF_AFDATA_WUNLOCK(ifp); 1018 1019 if (la_tmp == NULL) { 1020 arp_mark_lle_reachable(la); 1021 LLE_WUNLOCK(la); 1022 } else { 1023 /* Free newly-create entry and handle packet */ 1024 lltable_free_entry(LLTABLE(ifp), la); 1025 la = la_tmp; 1026 la_tmp = NULL; 1027 arp_check_update_lle(ah, isaddr, ifp, bridged, la); 1028 /* arp_check_update_lle() returns @la unlocked */ 1029 } 1030 la = NULL; 1031 } 1032 reply: 1033 if (op != ARPOP_REQUEST) 1034 goto drop; 1035 ARPSTAT_INC(rxrequests); 1036 1037 if (itaddr.s_addr == myaddr.s_addr) { 1038 /* Shortcut.. the receiving interface is the target. */ 1039 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1040 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1041 } else { 1042 struct llentry *lle = NULL; 1043 1044 sin.sin_addr = itaddr; 1045 IF_AFDATA_RLOCK(ifp); 1046 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); 1047 IF_AFDATA_RUNLOCK(ifp); 1048 1049 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { 1050 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1051 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); 1052 LLE_RUNLOCK(lle); 1053 } else { 1054 1055 if (lle != NULL) 1056 LLE_RUNLOCK(lle); 1057 1058 if (!V_arp_proxyall) 1059 goto drop; 1060 1061 /* XXX MRT use table 0 for arp reply */ 1062 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) 1063 goto drop; 1064 1065 /* 1066 * Don't send proxies for nodes on the same interface 1067 * as this one came out of, or we'll get into a fight 1068 * over who claims what Ether address. 1069 */ 1070 if (nh4.nh_ifp == ifp) 1071 goto drop; 1072 1073 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 1074 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 1075 1076 /* 1077 * Also check that the node which sent the ARP packet 1078 * is on the interface we expect it to be on. This 1079 * avoids ARP chaos if an interface is connected to the 1080 * wrong network. 1081 */ 1082 1083 /* XXX MRT use table 0 for arp checks */ 1084 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) 1085 goto drop; 1086 if (nh4.nh_ifp != ifp) { 1087 ARP_LOG(LOG_INFO, "proxy: ignoring request" 1088 " from %s via %s\n", 1089 inet_ntoa(isaddr), ifp->if_xname); 1090 goto drop; 1091 } 1092 1093 #ifdef DEBUG_PROXY 1094 printf("arp: proxying for %s\n", inet_ntoa(itaddr)); 1095 #endif 1096 } 1097 } 1098 1099 if (itaddr.s_addr == myaddr.s_addr && 1100 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 1101 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 1102 #ifdef DEBUG_LINKLOCAL 1103 printf("arp: sending reply for link-local addr %s\n", 1104 inet_ntoa(itaddr)); 1105 #endif 1106 m->m_flags |= M_BCAST; 1107 m->m_flags &= ~M_MCAST; 1108 } else { 1109 /* default behaviour; never reply by broadcast. */ 1110 m->m_flags &= ~(M_BCAST|M_MCAST); 1111 } 1112 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 1113 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 1114 ah->ar_op = htons(ARPOP_REPLY); 1115 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 1116 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 1117 m->m_pkthdr.len = m->m_len; 1118 m->m_pkthdr.rcvif = NULL; 1119 sa.sa_family = AF_ARP; 1120 sa.sa_len = 2; 1121 1122 /* Calculate link header for sending frame */ 1123 bzero(&ro, sizeof(ro)); 1124 linkhdrsize = sizeof(linkhdr); 1125 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); 1126 1127 /* 1128 * arp_fillheader() may fail due to lack of support inside encap request 1129 * routing. This is not necessary an error, AF_ARP can/should be handled 1130 * by if_output(). 1131 */ 1132 if (error != 0 && error != EAFNOSUPPORT) { 1133 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", 1134 if_name(ifp), error); 1135 return; 1136 } 1137 1138 ro.ro_prepend = linkhdr; 1139 ro.ro_plen = linkhdrsize; 1140 ro.ro_flags = 0; 1141 1142 m_clrprotoflags(m); /* Avoid confusing lower layers. */ 1143 (*ifp->if_output)(ifp, m, &sa, &ro); 1144 ARPSTAT_INC(txreplies); 1145 return; 1146 1147 drop: 1148 m_freem(m); 1149 } 1150 #endif 1151 1152 /* 1153 * Checks received arp data against existing @la. 1154 * Updates lle state/performs notification if necessary. 1155 */ 1156 static void 1157 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, 1158 int bridged, struct llentry *la) 1159 { 1160 struct sockaddr sa; 1161 struct mbuf *m_hold, *m_hold_next; 1162 uint8_t linkhdr[LLE_MAX_LINKHDR]; 1163 size_t linkhdrsize; 1164 int lladdr_off; 1165 1166 LLE_WLOCK_ASSERT(la); 1167 1168 /* the following is not an error when doing bridging */ 1169 if (!bridged && la->lle_tbl->llt_ifp != ifp) { 1170 if (log_arp_wrong_iface) 1171 ARP_LOG(LOG_WARNING, "%s is on %s " 1172 "but got reply from %*D on %s\n", 1173 inet_ntoa(isaddr), 1174 la->lle_tbl->llt_ifp->if_xname, 1175 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1176 ifp->if_xname); 1177 LLE_WUNLOCK(la); 1178 return; 1179 } 1180 if ((la->la_flags & LLE_VALID) && 1181 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { 1182 if (la->la_flags & LLE_STATIC) { 1183 LLE_WUNLOCK(la); 1184 if (log_arp_permanent_modify) 1185 ARP_LOG(LOG_ERR, 1186 "%*D attempts to modify " 1187 "permanent entry for %s on %s\n", 1188 ifp->if_addrlen, 1189 (u_char *)ar_sha(ah), ":", 1190 inet_ntoa(isaddr), ifp->if_xname); 1191 return; 1192 } 1193 if (log_arp_movements) { 1194 ARP_LOG(LOG_INFO, "%s moved from %*D " 1195 "to %*D on %s\n", 1196 inet_ntoa(isaddr), 1197 ifp->if_addrlen, 1198 (u_char *)&la->ll_addr, ":", 1199 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 1200 ifp->if_xname); 1201 } 1202 } 1203 1204 /* Calculate full link prepend to use in lle */ 1205 linkhdrsize = sizeof(linkhdr); 1206 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, 1207 &linkhdrsize, &lladdr_off) != 0) 1208 return; 1209 1210 /* Check if something has changed */ 1211 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || 1212 (la->la_flags & LLE_VALID) == 0) { 1213 /* Try to perform LLE update */ 1214 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, 1215 lladdr_off) == 0) 1216 return; 1217 1218 /* Clear fast path feedback request if set */ 1219 la->r_skip_req = 0; 1220 } 1221 1222 arp_mark_lle_reachable(la); 1223 1224 /* 1225 * The packets are all freed within the call to the output 1226 * routine. 1227 * 1228 * NB: The lock MUST be released before the call to the 1229 * output routine. 1230 */ 1231 if (la->la_hold != NULL) { 1232 m_hold = la->la_hold; 1233 la->la_hold = NULL; 1234 la->la_numheld = 0; 1235 lltable_fill_sa_entry(la, &sa); 1236 LLE_WUNLOCK(la); 1237 for (; m_hold != NULL; m_hold = m_hold_next) { 1238 m_hold_next = m_hold->m_nextpkt; 1239 m_hold->m_nextpkt = NULL; 1240 /* Avoid confusing lower layers. */ 1241 m_clrprotoflags(m_hold); 1242 (*ifp->if_output)(ifp, m_hold, &sa, NULL); 1243 } 1244 } else 1245 LLE_WUNLOCK(la); 1246 } 1247 1248 static void 1249 arp_mark_lle_reachable(struct llentry *la) 1250 { 1251 int canceled, wtime; 1252 1253 LLE_WLOCK_ASSERT(la); 1254 1255 la->ln_state = ARP_LLINFO_REACHABLE; 1256 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); 1257 1258 if (!(la->la_flags & LLE_STATIC)) { 1259 LLE_ADDREF(la); 1260 la->la_expire = time_uptime + V_arpt_keep; 1261 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; 1262 if (wtime < 0) 1263 wtime = V_arpt_keep; 1264 canceled = callout_reset(&la->lle_timer, 1265 hz * wtime, arptimer, la); 1266 if (canceled) 1267 LLE_REMREF(la); 1268 } 1269 la->la_asked = 0; 1270 la->la_preempt = V_arp_maxtries; 1271 } 1272 1273 /* 1274 * Add pernament link-layer record for given interface address. 1275 */ 1276 static __noinline void 1277 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) 1278 { 1279 struct llentry *lle, *lle_tmp; 1280 1281 /* 1282 * Interface address LLE record is considered static 1283 * because kernel code relies on LLE_STATIC flag to check 1284 * if these entries can be rewriten by arp updates. 1285 */ 1286 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); 1287 if (lle == NULL) { 1288 log(LOG_INFO, "arp_ifinit: cannot create arp " 1289 "entry for interface address\n"); 1290 return; 1291 } 1292 1293 IF_AFDATA_WLOCK(ifp); 1294 LLE_WLOCK(lle); 1295 /* Unlink any entry if exists */ 1296 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); 1297 if (lle_tmp != NULL) 1298 lltable_unlink_entry(LLTABLE(ifp), lle_tmp); 1299 1300 lltable_link_entry(LLTABLE(ifp), lle); 1301 IF_AFDATA_WUNLOCK(ifp); 1302 1303 if (lle_tmp != NULL) 1304 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); 1305 1306 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); 1307 LLE_WUNLOCK(lle); 1308 if (lle_tmp != NULL) 1309 lltable_free_entry(LLTABLE(ifp), lle_tmp); 1310 } 1311 1312 /* 1313 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range 1314 * of valid values. 1315 */ 1316 static int 1317 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) 1318 { 1319 int error; 1320 int rexmit_count = *(int *)arg1; 1321 1322 error = sysctl_handle_int(oidp, &rexmit_count, 0, req); 1323 1324 /* Enforce limits on any new value that may have been set. */ 1325 if (!error && req->newptr) { 1326 /* A new value was set. */ 1327 if (rexmit_count < 0) { 1328 rexmit_count = 0; 1329 } else if (rexmit_count > MAX_GARP_RETRANSMITS) { 1330 rexmit_count = MAX_GARP_RETRANSMITS; 1331 } 1332 *(int *)arg1 = rexmit_count; 1333 } 1334 1335 return (error); 1336 } 1337 1338 /* 1339 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to 1340 * retransmit it again. A pending callout owns a reference to the ifa. 1341 */ 1342 static void 1343 garp_rexmit(void *arg) 1344 { 1345 struct in_ifaddr *ia = arg; 1346 1347 if (callout_pending(&ia->ia_garp_timer) || 1348 !callout_active(&ia->ia_garp_timer)) { 1349 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1350 ifa_free(&ia->ia_ifa); 1351 return; 1352 } 1353 1354 /* 1355 * Drop lock while the ARP request is generated. 1356 */ 1357 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1358 1359 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, 1360 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); 1361 1362 /* 1363 * Increment the count of retransmissions. If the count has reached the 1364 * maximum value, stop sending the GARP packets. Otherwise, schedule 1365 * the callout to retransmit another GARP packet. 1366 */ 1367 ++ia->ia_garp_count; 1368 if (ia->ia_garp_count >= garp_rexmit_count) { 1369 ifa_free(&ia->ia_ifa); 1370 } else { 1371 int rescheduled; 1372 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1373 rescheduled = callout_reset(&ia->ia_garp_timer, 1374 (1 << ia->ia_garp_count) * hz, 1375 garp_rexmit, ia); 1376 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1377 if (rescheduled) { 1378 ifa_free(&ia->ia_ifa); 1379 } 1380 } 1381 } 1382 1383 /* 1384 * Start the GARP retransmit timer. 1385 * 1386 * A single GARP is always transmitted when an IPv4 address is added 1387 * to an interface and that is usually sufficient. However, in some 1388 * circumstances, such as when a shared address is passed between 1389 * cluster nodes, this single GARP may occasionally be dropped or 1390 * lost. This can lead to neighbors on the network link working with a 1391 * stale ARP cache and sending packets destined for that address to 1392 * the node that previously owned the address, which may not respond. 1393 * 1394 * To avoid this situation, GARP retransmits can be enabled by setting 1395 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater 1396 * than zero. The setting represents the maximum number of 1397 * retransmissions. The interval between retransmissions is calculated 1398 * using an exponential backoff algorithm, doubling each time, so the 1399 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). 1400 */ 1401 static void 1402 garp_timer_start(struct ifaddr *ifa) 1403 { 1404 struct in_ifaddr *ia = (struct in_ifaddr *) ifa; 1405 1406 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); 1407 ia->ia_garp_count = 0; 1408 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, 1409 garp_rexmit, ia) == 0) { 1410 ifa_ref(ifa); 1411 } 1412 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); 1413 } 1414 1415 void 1416 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1417 { 1418 const struct sockaddr_in *dst_in; 1419 const struct sockaddr *dst; 1420 1421 if (ifa->ifa_carp != NULL) 1422 return; 1423 1424 dst = ifa->ifa_addr; 1425 dst_in = (const struct sockaddr_in *)dst; 1426 1427 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) 1428 return; 1429 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); 1430 if (garp_rexmit_count > 0) { 1431 garp_timer_start(ifa); 1432 } 1433 1434 arp_add_ifa_lle(ifp, dst); 1435 } 1436 1437 void 1438 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) 1439 { 1440 1441 if (ntohl(addr.s_addr) != INADDR_ANY) 1442 arprequest(ifp, &addr, &addr, enaddr); 1443 } 1444 1445 /* 1446 * Sends gratuitous ARPs for each ifaddr to notify other 1447 * nodes about the address change. 1448 */ 1449 static __noinline void 1450 arp_handle_ifllchange(struct ifnet *ifp) 1451 { 1452 struct ifaddr *ifa; 1453 1454 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { 1455 if (ifa->ifa_addr->sa_family == AF_INET) 1456 arp_ifinit(ifp, ifa); 1457 } 1458 } 1459 1460 /* 1461 * A handler for interface link layer address change event. 1462 */ 1463 static void 1464 arp_iflladdr(void *arg __unused, struct ifnet *ifp) 1465 { 1466 1467 lltable_update_ifaddr(LLTABLE(ifp)); 1468 1469 if ((ifp->if_flags & IFF_UP) != 0) 1470 arp_handle_ifllchange(ifp); 1471 } 1472 1473 static void 1474 vnet_arp_init(void) 1475 { 1476 1477 if (IS_DEFAULT_VNET(curvnet)) { 1478 netisr_register(&arp_nh); 1479 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, 1480 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); 1481 } 1482 #ifdef VIMAGE 1483 else 1484 netisr_register_vnet(&arp_nh); 1485 #endif 1486 } 1487 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, 1488 vnet_arp_init, 0); 1489 1490 #ifdef VIMAGE 1491 /* 1492 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH 1493 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. 1494 */ 1495 static void 1496 vnet_arp_destroy(__unused void *arg) 1497 { 1498 1499 netisr_unregister_vnet(&arp_nh); 1500 } 1501 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, 1502 vnet_arp_destroy, NULL); 1503 #endif 1504