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