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 * $FreeBSD$ 31 */ 32 33 /* 34 * Ethernet address resolution protocol. 35 * TODO: 36 * add "inuse/lock" bit (or ref. count) along with valid bit 37 */ 38 39 #include "opt_inet.h" 40 #include "opt_mac.h" 41 #include "opt_carp.h" 42 43 #include <sys/param.h> 44 #include <sys/kernel.h> 45 #include <sys/queue.h> 46 #include <sys/sysctl.h> 47 #include <sys/systm.h> 48 #include <sys/mbuf.h> 49 #include <sys/malloc.h> 50 #include <sys/socket.h> 51 #include <sys/syslog.h> 52 53 #include <net/if.h> 54 #include <net/if_dl.h> 55 #include <net/if_types.h> 56 #include <net/route.h> 57 #include <net/netisr.h> 58 #include <net/if_llc.h> 59 #include <net/ethernet.h> 60 61 #include <netinet/in.h> 62 #include <netinet/in_var.h> 63 #include <netinet/if_ether.h> 64 65 #include <net/if_arc.h> 66 #include <net/iso88025.h> 67 68 #ifdef DEV_CARP 69 #include <netinet/ip_carp.h> 70 #endif 71 72 #include <security/mac/mac_framework.h> 73 74 #define SIN(s) ((struct sockaddr_in *)s) 75 #define SDL(s) ((struct sockaddr_dl *)s) 76 77 SYSCTL_DECL(_net_link_ether); 78 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 79 80 /* timer values */ 81 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 82 83 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 84 &arpt_keep, 0, "ARP entry lifetime in seconds"); 85 86 #define rt_expire rt_rmx.rmx_expire 87 88 struct llinfo_arp { 89 struct callout la_timer; 90 struct rtentry *la_rt; 91 struct mbuf *la_hold; /* last packet until resolved/timeout */ 92 u_short la_preempt; /* countdown for pre-expiry arps */ 93 u_short la_asked; /* # requests sent */ 94 }; 95 96 static struct ifqueue arpintrq; 97 static int arp_allocated; 98 99 static int arp_maxtries = 5; 100 static int useloopback = 1; /* use loopback interface for local traffic */ 101 static int arp_proxyall = 0; 102 103 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 104 &arp_maxtries, 0, "ARP resolution attempts before returning error"); 105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 106 &useloopback, 0, "Use the loopback interface for local traffic"); 107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 108 &arp_proxyall, 0, "Enable proxy ARP for all suitable requests"); 109 110 static void arp_init(void); 111 static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *); 112 static void arprequest(struct ifnet *, 113 struct in_addr *, struct in_addr *, u_char *); 114 static void arpintr(struct mbuf *); 115 static void arptimer(void *); 116 static struct rtentry 117 *arplookup(u_long, int, int); 118 #ifdef INET 119 static void in_arpinput(struct mbuf *); 120 #endif 121 122 /* 123 * Timeout routine. 124 */ 125 static void 126 arptimer(void *arg) 127 { 128 struct rtentry *rt = (struct rtentry *)arg; 129 130 RT_LOCK_ASSERT(rt); 131 /* 132 * The lock is needed to close a theoretical race 133 * between spontaneous expiry and intentional removal. 134 * We still got an extra reference on rtentry, so can 135 * safely pass pointers to its contents. 136 */ 137 RT_UNLOCK(rt); 138 139 rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL); 140 } 141 142 /* 143 * Parallel to llc_rtrequest. 144 */ 145 static void 146 arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info) 147 { 148 struct sockaddr *gate; 149 struct llinfo_arp *la; 150 static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK}; 151 struct in_ifaddr *ia; 152 struct ifaddr *ifa; 153 154 RT_LOCK_ASSERT(rt); 155 156 if (rt->rt_flags & RTF_GATEWAY) 157 return; 158 gate = rt->rt_gateway; 159 la = (struct llinfo_arp *)rt->rt_llinfo; 160 switch (req) { 161 162 case RTM_ADD: 163 /* 164 * XXX: If this is a manually added route to interface 165 * such as older version of routed or gated might provide, 166 * restore cloning bit. 167 */ 168 if ((rt->rt_flags & RTF_HOST) == 0 && 169 rt_mask(rt) != NULL && 170 SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff) 171 rt->rt_flags |= RTF_CLONING; 172 if (rt->rt_flags & RTF_CLONING) { 173 /* 174 * Case 1: This route should come from a route to iface. 175 */ 176 rt_setgate(rt, rt_key(rt), 177 (struct sockaddr *)&null_sdl); 178 gate = rt->rt_gateway; 179 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 180 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 181 rt->rt_expire = time_uptime; 182 break; 183 } 184 /* Announce a new entry if requested. */ 185 if (rt->rt_flags & RTF_ANNOUNCE) 186 arprequest(rt->rt_ifp, 187 &SIN(rt_key(rt))->sin_addr, 188 &SIN(rt_key(rt))->sin_addr, 189 (u_char *)LLADDR(SDL(gate))); 190 /*FALLTHROUGH*/ 191 case RTM_RESOLVE: 192 if (gate->sa_family != AF_LINK || 193 gate->sa_len < sizeof(null_sdl)) { 194 log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__, 195 inet_ntoa(SIN(rt_key(rt))->sin_addr), 196 (gate->sa_family != AF_LINK) ? 197 " (!AF_LINK)": ""); 198 break; 199 } 200 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 201 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 202 if (la != 0) 203 break; /* This happens on a route change */ 204 /* 205 * Case 2: This route may come from cloning, or a manual route 206 * add with a LL address. 207 */ 208 R_Zalloc(la, struct llinfo_arp *, sizeof(*la)); 209 rt->rt_llinfo = (caddr_t)la; 210 if (la == 0) { 211 log(LOG_DEBUG, "%s: malloc failed\n", __func__); 212 break; 213 } 214 arp_allocated++; 215 /* 216 * We are storing a route entry outside of radix tree. So, 217 * it can be found and accessed by other means than radix 218 * lookup. The routing code assumes that any rtentry detached 219 * from radix can be destroyed safely. To prevent this, we 220 * add an additional reference. 221 */ 222 RT_ADDREF(rt); 223 la->la_rt = rt; 224 rt->rt_flags |= RTF_LLINFO; 225 callout_init_mtx(&la->la_timer, &rt->rt_mtx, 226 CALLOUT_RETURNUNLOCKED); 227 228 #ifdef INET 229 /* 230 * This keeps the multicast addresses from showing up 231 * in `arp -a' listings as unresolved. It's not actually 232 * functional. Then the same for broadcast. 233 */ 234 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) && 235 rt->rt_ifp->if_type != IFT_ARCNET) { 236 ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr, 237 LLADDR(SDL(gate))); 238 SDL(gate)->sdl_alen = 6; 239 rt->rt_expire = 0; 240 } 241 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) { 242 memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr, 243 rt->rt_ifp->if_addrlen); 244 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen; 245 rt->rt_expire = 0; 246 } 247 #endif 248 249 TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) { 250 if (ia->ia_ifp == rt->rt_ifp && 251 SIN(rt_key(rt))->sin_addr.s_addr == 252 (IA_SIN(ia))->sin_addr.s_addr) 253 break; 254 } 255 if (ia) { 256 /* 257 * This test used to be 258 * if (loif.if_flags & IFF_UP) 259 * It allowed local traffic to be forced 260 * through the hardware by configuring the loopback down. 261 * However, it causes problems during network configuration 262 * for boards that can't receive packets they send. 263 * It is now necessary to clear "useloopback" and remove 264 * the route to force traffic out to the hardware. 265 */ 266 rt->rt_expire = 0; 267 bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)), 268 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen); 269 if (useloopback) { 270 rt->rt_ifp = loif; 271 rt->rt_rmx.rmx_mtu = loif->if_mtu; 272 } 273 274 /* 275 * make sure to set rt->rt_ifa to the interface 276 * address we are using, otherwise we will have trouble 277 * with source address selection. 278 */ 279 ifa = &ia->ia_ifa; 280 if (ifa != rt->rt_ifa) { 281 IFAFREE(rt->rt_ifa); 282 IFAREF(ifa); 283 rt->rt_ifa = ifa; 284 } 285 } 286 break; 287 288 case RTM_DELETE: 289 if (la == NULL) /* XXX: at least CARP does this. */ 290 break; 291 callout_stop(&la->la_timer); 292 rt->rt_llinfo = NULL; 293 rt->rt_flags &= ~RTF_LLINFO; 294 RT_REMREF(rt); 295 if (la->la_hold) 296 m_freem(la->la_hold); 297 Free((caddr_t)la); 298 } 299 } 300 301 /* 302 * Broadcast an ARP request. Caller specifies: 303 * - arp header source ip address 304 * - arp header target ip address 305 * - arp header source ethernet address 306 */ 307 static void 308 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 309 u_char *enaddr) 310 { 311 struct mbuf *m; 312 struct arphdr *ah; 313 struct sockaddr sa; 314 315 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 316 return; 317 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 318 2*ifp->if_data.ifi_addrlen; 319 m->m_pkthdr.len = m->m_len; 320 MH_ALIGN(m, m->m_len); 321 ah = mtod(m, struct arphdr *); 322 bzero((caddr_t)ah, m->m_len); 323 #ifdef MAC 324 mac_create_mbuf_linklayer(ifp, m); 325 #endif 326 ah->ar_pro = htons(ETHERTYPE_IP); 327 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 328 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 329 ah->ar_op = htons(ARPOP_REQUEST); 330 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 331 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 332 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 333 sa.sa_family = AF_ARP; 334 sa.sa_len = 2; 335 m->m_flags |= M_BCAST; 336 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 337 338 return; 339 } 340 341 /* 342 * Resolve an IP address into an ethernet address. 343 * On input: 344 * ifp is the interface we use 345 * dst is the next hop, 346 * rt0 is the route to the final destination (possibly useless) 347 * m is the mbuf 348 * desten is where we want the address. 349 * 350 * On success, desten is filled in and the function returns 0; 351 * If the packet must be held pending resolution, we return EWOULDBLOCK 352 * On other errors, we return the corresponding error code. 353 */ 354 int 355 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 356 struct sockaddr *dst, u_char *desten) 357 { 358 struct llinfo_arp *la = NULL; 359 struct rtentry *rt = NULL; 360 struct sockaddr_dl *sdl; 361 int error; 362 363 if (m->m_flags & M_BCAST) { /* broadcast */ 364 (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen); 365 return (0); 366 } 367 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */ 368 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 369 return (0); 370 } 371 372 if (rt0 != NULL) { 373 error = rt_check(&rt, &rt0, dst); 374 if (error) { 375 m_freem(m); 376 return error; 377 } 378 la = (struct llinfo_arp *)rt->rt_llinfo; 379 if (la == NULL) 380 RT_UNLOCK(rt); 381 } 382 if (la == NULL) { 383 /* 384 * We enter this block in case if rt0 was NULL, 385 * or if rt found by rt_check() didn't have llinfo. 386 */ 387 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); 388 if (rt == NULL) { 389 log(LOG_DEBUG, 390 "arpresolve: can't allocate route for %s\n", 391 inet_ntoa(SIN(dst)->sin_addr)); 392 m_freem(m); 393 return (EINVAL); /* XXX */ 394 } 395 la = (struct llinfo_arp *)rt->rt_llinfo; 396 if (la == NULL) { 397 RT_UNLOCK(rt); 398 log(LOG_DEBUG, 399 "arpresolve: can't allocate llinfo for %s\n", 400 inet_ntoa(SIN(dst)->sin_addr)); 401 m_freem(m); 402 return (EINVAL); /* XXX */ 403 } 404 } 405 sdl = SDL(rt->rt_gateway); 406 /* 407 * Check the address family and length is valid, the address 408 * is resolved; otherwise, try to resolve. 409 */ 410 if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) && 411 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { 412 413 bcopy(LLADDR(sdl), desten, sdl->sdl_alen); 414 415 /* 416 * If entry has an expiry time and it is approaching, 417 * send an ARP request. 418 */ 419 if ((rt->rt_expire != 0) && 420 (time_uptime + la->la_preempt > rt->rt_expire)) { 421 struct in_addr sin = 422 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 423 424 la->la_preempt--; 425 RT_UNLOCK(rt); 426 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 427 IF_LLADDR(ifp)); 428 return (0); 429 } 430 431 RT_UNLOCK(rt); 432 return (0); 433 } 434 /* 435 * If ARP is disabled or static on this interface, stop. 436 * XXX 437 * Probably should not allocate empty llinfo struct if we are 438 * not going to be sending out an arp request. 439 */ 440 if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) { 441 RT_UNLOCK(rt); 442 m_freem(m); 443 return (EINVAL); 444 } 445 /* 446 * There is an arptab entry, but no ethernet address 447 * response yet. Replace the held mbuf with this 448 * latest one. 449 */ 450 if (la->la_hold) 451 m_freem(la->la_hold); 452 la->la_hold = m; 453 454 KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry")); 455 456 /* 457 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 458 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 459 * if we have already sent arp_maxtries ARP requests. Retransmit the 460 * ARP request, but not faster than one request per second. 461 */ 462 if (la->la_asked < arp_maxtries) 463 error = EWOULDBLOCK; /* First request. */ 464 else 465 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH; 466 467 if (la->la_asked == 0 || rt->rt_expire != time_uptime) { 468 struct in_addr sin = 469 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 470 471 rt->rt_expire = time_uptime; 472 callout_reset(&la->la_timer, hz, arptimer, rt); 473 la->la_asked++; 474 RT_UNLOCK(rt); 475 476 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 477 IF_LLADDR(ifp)); 478 } else 479 RT_UNLOCK(rt); 480 481 return (error); 482 } 483 484 /* 485 * Common length and type checks are done here, 486 * then the protocol-specific routine is called. 487 */ 488 static void 489 arpintr(struct mbuf *m) 490 { 491 struct arphdr *ar; 492 493 if (m->m_len < sizeof(struct arphdr) && 494 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 495 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 496 return; 497 } 498 ar = mtod(m, struct arphdr *); 499 500 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 501 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 502 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 503 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 504 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 505 (unsigned char *)&ar->ar_hrd, ""); 506 m_freem(m); 507 return; 508 } 509 510 if (m->m_len < arphdr_len(ar)) { 511 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 512 log(LOG_ERR, "arp: runt packet\n"); 513 m_freem(m); 514 return; 515 } 516 ar = mtod(m, struct arphdr *); 517 } 518 519 switch (ntohs(ar->ar_pro)) { 520 #ifdef INET 521 case ETHERTYPE_IP: 522 in_arpinput(m); 523 return; 524 #endif 525 } 526 m_freem(m); 527 } 528 529 #ifdef INET 530 /* 531 * ARP for Internet protocols on 10 Mb/s Ethernet. 532 * Algorithm is that given in RFC 826. 533 * In addition, a sanity check is performed on the sender 534 * protocol address, to catch impersonators. 535 * We no longer handle negotiations for use of trailer protocol: 536 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 537 * along with IP replies if we wanted trailers sent to us, 538 * and also sent them in response to IP replies. 539 * This allowed either end to announce the desire to receive 540 * trailer packets. 541 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 542 * but formerly didn't normally send requests. 543 */ 544 static int log_arp_wrong_iface = 1; 545 static int log_arp_movements = 1; 546 static int log_arp_permanent_modify = 1; 547 548 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 549 &log_arp_wrong_iface, 0, 550 "log arp packets arriving on the wrong interface"); 551 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 552 &log_arp_movements, 0, 553 "log arp replies from MACs different than the one in the cache"); 554 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 555 &log_arp_permanent_modify, 0, 556 "log arp replies from MACs different than the one in the permanent arp entry"); 557 558 559 static void 560 in_arpinput(struct mbuf *m) 561 { 562 struct arphdr *ah; 563 struct ifnet *ifp = m->m_pkthdr.rcvif; 564 struct llinfo_arp *la; 565 struct rtentry *rt; 566 struct ifaddr *ifa; 567 struct in_ifaddr *ia; 568 struct sockaddr_dl *sdl; 569 struct sockaddr sa; 570 struct in_addr isaddr, itaddr, myaddr; 571 struct mbuf *hold; 572 u_int8_t *enaddr = NULL; 573 int op, rif_len; 574 int req_len; 575 int bridged = 0; 576 #ifdef DEV_CARP 577 int carp_match = 0; 578 #endif 579 580 if (ifp->if_bridge) 581 bridged = 1; 582 583 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 584 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 585 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 586 return; 587 } 588 589 ah = mtod(m, struct arphdr *); 590 op = ntohs(ah->ar_op); 591 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 592 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 593 594 /* 595 * For a bridge, we want to check the address irrespective 596 * of the receive interface. (This will change slightly 597 * when we have clusters of interfaces). 598 * If the interface does not match, but the recieving interface 599 * is part of carp, we call carp_iamatch to see if this is a 600 * request for the virtual host ip. 601 * XXX: This is really ugly! 602 */ 603 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 604 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 605 (ia->ia_ifp == ifp)) && 606 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 607 goto match; 608 #ifdef DEV_CARP 609 if (ifp->if_carp != NULL && 610 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 611 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 612 carp_match = 1; 613 goto match; 614 } 615 #endif 616 } 617 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 618 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 619 (ia->ia_ifp == ifp)) && 620 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 621 goto match; 622 /* 623 * No match, use the first inet address on the receive interface 624 * as a dummy address for the rest of the function. 625 */ 626 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 627 if (ifa->ifa_addr->sa_family == AF_INET) { 628 ia = ifatoia(ifa); 629 goto match; 630 } 631 /* 632 * If bridging, fall back to using any inet address. 633 */ 634 if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL) 635 goto drop; 636 match: 637 if (!enaddr) 638 enaddr = (u_int8_t *)IF_LLADDR(ifp); 639 myaddr = ia->ia_addr.sin_addr; 640 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 641 goto drop; /* it's from me, ignore it. */ 642 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 643 log(LOG_ERR, 644 "arp: link address is broadcast for IP address %s!\n", 645 inet_ntoa(isaddr)); 646 goto drop; 647 } 648 /* 649 * Warn if another host is using the same IP address, but only if the 650 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 651 * case we suppress the warning to avoid false positive complaints of 652 * potential misconfiguration. 653 */ 654 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 655 log(LOG_ERR, 656 "arp: %*D is using my IP address %s!\n", 657 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 658 inet_ntoa(isaddr)); 659 itaddr = myaddr; 660 goto reply; 661 } 662 if (ifp->if_flags & IFF_STATICARP) 663 goto reply; 664 rt = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); 665 if (rt != NULL) { 666 la = (struct llinfo_arp *)rt->rt_llinfo; 667 if (la == NULL) { 668 RT_UNLOCK(rt); 669 goto reply; 670 } 671 } else 672 goto reply; 673 674 /* The following is not an error when doing bridging. */ 675 if (!bridged && rt->rt_ifp != ifp 676 #ifdef DEV_CARP 677 && (ifp->if_type != IFT_CARP || !carp_match) 678 #endif 679 ) { 680 if (log_arp_wrong_iface) 681 log(LOG_ERR, "arp: %s is on %s but got reply from %*D on %s\n", 682 inet_ntoa(isaddr), 683 rt->rt_ifp->if_xname, 684 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 685 ifp->if_xname); 686 RT_UNLOCK(rt); 687 goto reply; 688 } 689 sdl = SDL(rt->rt_gateway); 690 if (sdl->sdl_alen && 691 bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) { 692 if (rt->rt_expire) { 693 if (log_arp_movements) 694 log(LOG_INFO, "arp: %s moved from %*D to %*D on %s\n", 695 inet_ntoa(isaddr), 696 ifp->if_addrlen, (u_char *)LLADDR(sdl), ":", 697 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 698 ifp->if_xname); 699 } else { 700 RT_UNLOCK(rt); 701 if (log_arp_permanent_modify) 702 log(LOG_ERR, "arp: %*D attempts to modify " 703 "permanent entry for %s on %s\n", 704 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 705 inet_ntoa(isaddr), ifp->if_xname); 706 goto reply; 707 } 708 } 709 /* 710 * sanity check for the address length. 711 * XXX this does not work for protocols with variable address 712 * length. -is 713 */ 714 if (sdl->sdl_alen && 715 sdl->sdl_alen != ah->ar_hln) { 716 log(LOG_WARNING, 717 "arp from %*D: new addr len %d, was %d", 718 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 719 ah->ar_hln, sdl->sdl_alen); 720 } 721 if (ifp->if_addrlen != ah->ar_hln) { 722 log(LOG_WARNING, 723 "arp from %*D: addr len: new %d, i/f %d (ignored)", 724 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 725 ah->ar_hln, ifp->if_addrlen); 726 RT_UNLOCK(rt); 727 goto reply; 728 } 729 (void)memcpy(LLADDR(sdl), ar_sha(ah), 730 sdl->sdl_alen = ah->ar_hln); 731 /* 732 * If we receive an arp from a token-ring station over 733 * a token-ring nic then try to save the source 734 * routing info. 735 */ 736 if (ifp->if_type == IFT_ISO88025) { 737 struct iso88025_header *th = NULL; 738 struct iso88025_sockaddr_dl_data *trld; 739 740 th = (struct iso88025_header *)m->m_pkthdr.header; 741 trld = SDL_ISO88025(sdl); 742 rif_len = TR_RCF_RIFLEN(th->rcf); 743 if ((th->iso88025_shost[0] & TR_RII) && 744 (rif_len > 2)) { 745 trld->trld_rcf = th->rcf; 746 trld->trld_rcf ^= htons(TR_RCF_DIR); 747 memcpy(trld->trld_route, th->rd, rif_len - 2); 748 trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK); 749 /* 750 * Set up source routing information for 751 * reply packet (XXX) 752 */ 753 m->m_data -= rif_len; 754 m->m_len += rif_len; 755 m->m_pkthdr.len += rif_len; 756 } else { 757 th->iso88025_shost[0] &= ~TR_RII; 758 trld->trld_rcf = 0; 759 } 760 m->m_data -= 8; 761 m->m_len += 8; 762 m->m_pkthdr.len += 8; 763 th->rcf = trld->trld_rcf; 764 } 765 if (rt->rt_expire) { 766 rt->rt_expire = time_uptime + arpt_keep; 767 callout_reset(&la->la_timer, hz * arpt_keep, arptimer, rt); 768 } 769 la->la_asked = 0; 770 la->la_preempt = arp_maxtries; 771 hold = la->la_hold; 772 la->la_hold = NULL; 773 RT_UNLOCK(rt); 774 if (hold != NULL) 775 (*ifp->if_output)(ifp, hold, rt_key(rt), rt); 776 777 reply: 778 if (op != ARPOP_REQUEST) 779 goto drop; 780 if (itaddr.s_addr == myaddr.s_addr) { 781 /* I am the target */ 782 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 783 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 784 } else { 785 rt = arplookup(itaddr.s_addr, 0, SIN_PROXY); 786 if (rt == NULL) { 787 struct sockaddr_in sin; 788 789 if (!arp_proxyall) 790 goto drop; 791 792 bzero(&sin, sizeof sin); 793 sin.sin_family = AF_INET; 794 sin.sin_len = sizeof sin; 795 sin.sin_addr = itaddr; 796 797 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 798 if (!rt) 799 goto drop; 800 /* 801 * Don't send proxies for nodes on the same interface 802 * as this one came out of, or we'll get into a fight 803 * over who claims what Ether address. 804 */ 805 if (rt->rt_ifp == ifp) { 806 rtfree(rt); 807 goto drop; 808 } 809 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 810 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 811 rtfree(rt); 812 813 /* 814 * Also check that the node which sent the ARP packet 815 * is on the the interface we expect it to be on. This 816 * avoids ARP chaos if an interface is connected to the 817 * wrong network. 818 */ 819 sin.sin_addr = isaddr; 820 821 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 822 if (!rt) 823 goto drop; 824 if (rt->rt_ifp != ifp) { 825 log(LOG_INFO, "arp_proxy: ignoring request" 826 " from %s via %s, expecting %s\n", 827 inet_ntoa(isaddr), ifp->if_xname, 828 rt->rt_ifp->if_xname); 829 rtfree(rt); 830 goto drop; 831 } 832 rtfree(rt); 833 834 #ifdef DEBUG_PROXY 835 printf("arp: proxying for %s\n", 836 inet_ntoa(itaddr)); 837 #endif 838 } else { 839 /* 840 * Return proxied ARP replies only on the interface 841 * or bridge cluster where this network resides. 842 * Otherwise we may conflict with the host we are 843 * proxying for. 844 */ 845 if (rt->rt_ifp != ifp && 846 (rt->rt_ifp->if_bridge != ifp->if_bridge || 847 ifp->if_bridge == NULL)) { 848 RT_UNLOCK(rt); 849 goto drop; 850 } 851 sdl = SDL(rt->rt_gateway); 852 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 853 (void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln); 854 RT_UNLOCK(rt); 855 } 856 } 857 858 if (itaddr.s_addr == myaddr.s_addr && 859 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 860 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 861 #ifdef DEBUG_LINKLOCAL 862 printf("arp: sending reply for link-local addr %s\n", 863 inet_ntoa(itaddr)); 864 #endif 865 m->m_flags |= M_BCAST; 866 m->m_flags &= ~M_MCAST; 867 } else { 868 /* default behaviour; never reply by broadcast. */ 869 m->m_flags &= ~(M_BCAST|M_MCAST); 870 } 871 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 872 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 873 ah->ar_op = htons(ARPOP_REPLY); 874 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 875 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 876 m->m_pkthdr.len = m->m_len; 877 sa.sa_family = AF_ARP; 878 sa.sa_len = 2; 879 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 880 return; 881 882 drop: 883 m_freem(m); 884 } 885 #endif 886 887 /* 888 * Lookup or enter a new address in arptab. 889 */ 890 static struct rtentry * 891 arplookup(u_long addr, int create, int proxy) 892 { 893 struct rtentry *rt; 894 struct sockaddr_inarp sin; 895 const char *why = 0; 896 897 bzero(&sin, sizeof(sin)); 898 sin.sin_len = sizeof(sin); 899 sin.sin_family = AF_INET; 900 sin.sin_addr.s_addr = addr; 901 if (proxy) 902 sin.sin_other = SIN_PROXY; 903 rt = rtalloc1((struct sockaddr *)&sin, create, 0UL); 904 if (rt == 0) 905 return (0); 906 907 if (rt->rt_flags & RTF_GATEWAY) 908 why = "host is not on local network"; 909 else if ((rt->rt_flags & RTF_LLINFO) == 0) 910 why = "could not allocate llinfo"; 911 else if (rt->rt_gateway->sa_family != AF_LINK) 912 why = "gateway route is not ours"; 913 914 if (why) { 915 #define ISDYNCLONE(_rt) \ 916 (((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED) 917 if (create) 918 log(LOG_DEBUG, "arplookup %s failed: %s\n", 919 inet_ntoa(sin.sin_addr), why); 920 /* 921 * If there are no references to this Layer 2 route, 922 * and it is a cloned route, and not static, and 923 * arplookup() is creating the route, then purge 924 * it from the routing table as it is probably bogus. 925 */ 926 if (rt->rt_refcnt == 1 && ISDYNCLONE(rt)) 927 rtexpunge(rt); 928 RTFREE_LOCKED(rt); 929 return (0); 930 #undef ISDYNCLONE 931 } else { 932 RT_REMREF(rt); 933 return (rt); 934 } 935 } 936 937 void 938 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 939 { 940 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 941 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 942 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 943 ifa->ifa_rtrequest = arp_rtrequest; 944 ifa->ifa_flags |= RTF_CLONING; 945 } 946 947 void 948 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 949 { 950 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 951 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 952 &IA_SIN(ifa)->sin_addr, enaddr); 953 ifa->ifa_rtrequest = arp_rtrequest; 954 ifa->ifa_flags |= RTF_CLONING; 955 } 956 957 static void 958 arp_init(void) 959 { 960 961 arpintrq.ifq_maxlen = 50; 962 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 963 netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE); 964 } 965 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 966