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 #include "opt_mac.h" 43 #include "opt_carp.h" 44 45 #include <sys/param.h> 46 #include <sys/kernel.h> 47 #include <sys/queue.h> 48 #include <sys/sysctl.h> 49 #include <sys/systm.h> 50 #include <sys/mbuf.h> 51 #include <sys/malloc.h> 52 #include <sys/socket.h> 53 #include <sys/syslog.h> 54 55 #include <net/if.h> 56 #include <net/if_dl.h> 57 #include <net/if_types.h> 58 #include <net/route.h> 59 #include <net/netisr.h> 60 #include <net/if_llc.h> 61 #include <net/ethernet.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 #ifdef DEV_CARP 71 #include <netinet/ip_carp.h> 72 #endif 73 74 #include <security/mac/mac_framework.h> 75 76 #define SIN(s) ((struct sockaddr_in *)s) 77 #define SDL(s) ((struct sockaddr_dl *)s) 78 79 SYSCTL_DECL(_net_link_ether); 80 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); 81 82 /* timer values */ 83 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 84 85 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 86 &arpt_keep, 0, "ARP entry lifetime in seconds"); 87 88 #define rt_expire rt_rmx.rmx_expire 89 90 struct llinfo_arp { 91 struct callout la_timer; 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; /* # requests sent */ 96 }; 97 98 static struct ifqueue arpintrq; 99 static int arp_allocated; 100 101 static int arp_maxtries = 5; 102 static int useloopback = 1; /* use loopback interface for local traffic */ 103 static int arp_proxyall = 0; 104 105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW, 106 &arp_maxtries, 0, "ARP resolution attempts before returning error"); 107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, 108 &useloopback, 0, "Use the loopback interface for local traffic"); 109 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, 110 &arp_proxyall, 0, "Enable proxy ARP for all suitable requests"); 111 112 static void arp_init(void); 113 static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *); 114 static void arprequest(struct ifnet *, 115 struct in_addr *, struct in_addr *, u_char *); 116 static void arpintr(struct mbuf *); 117 static void arptimer(void *); 118 static struct rtentry 119 *arplookup(u_long, int, int); 120 #ifdef INET 121 static void in_arpinput(struct mbuf *); 122 #endif 123 124 /* 125 * Timeout routine. 126 */ 127 static void 128 arptimer(void *arg) 129 { 130 struct rtentry *rt = (struct rtentry *)arg; 131 132 RT_LOCK_ASSERT(rt); 133 /* 134 * The lock is needed to close a theoretical race 135 * between spontaneous expiry and intentional removal. 136 * We still got an extra reference on rtentry, so can 137 * safely pass pointers to its contents. 138 */ 139 RT_UNLOCK(rt); 140 141 rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL); 142 } 143 144 /* 145 * Parallel to llc_rtrequest. 146 */ 147 static void 148 arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info) 149 { 150 struct sockaddr *gate; 151 struct llinfo_arp *la; 152 static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK}; 153 struct in_ifaddr *ia; 154 struct ifaddr *ifa; 155 156 RT_LOCK_ASSERT(rt); 157 158 if (rt->rt_flags & RTF_GATEWAY) 159 return; 160 gate = rt->rt_gateway; 161 la = (struct llinfo_arp *)rt->rt_llinfo; 162 switch (req) { 163 164 case RTM_ADD: 165 /* 166 * XXX: If this is a manually added route to interface 167 * such as older version of routed or gated might provide, 168 * restore cloning bit. 169 */ 170 if ((rt->rt_flags & RTF_HOST) == 0 && 171 rt_mask(rt) != NULL && 172 SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff) 173 rt->rt_flags |= RTF_CLONING; 174 if (rt->rt_flags & RTF_CLONING) { 175 /* 176 * Case 1: This route should come from a route to iface. 177 */ 178 rt_setgate(rt, rt_key(rt), 179 (struct sockaddr *)&null_sdl); 180 gate = rt->rt_gateway; 181 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 182 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 183 rt->rt_expire = time_uptime; 184 break; 185 } 186 /* Announce a new entry if requested. */ 187 if (rt->rt_flags & RTF_ANNOUNCE) 188 arprequest(rt->rt_ifp, 189 &SIN(rt_key(rt))->sin_addr, 190 &SIN(rt_key(rt))->sin_addr, 191 (u_char *)LLADDR(SDL(gate))); 192 /*FALLTHROUGH*/ 193 case RTM_RESOLVE: 194 if (gate->sa_family != AF_LINK || 195 gate->sa_len < sizeof(null_sdl)) { 196 log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__, 197 inet_ntoa(SIN(rt_key(rt))->sin_addr), 198 (gate->sa_family != AF_LINK) ? 199 " (!AF_LINK)": ""); 200 break; 201 } 202 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 203 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 204 if (la != 0) 205 break; /* This happens on a route change */ 206 /* 207 * Case 2: This route may come from cloning, or a manual route 208 * add with a LL address. 209 */ 210 R_Zalloc(la, struct llinfo_arp *, sizeof(*la)); 211 rt->rt_llinfo = (caddr_t)la; 212 if (la == 0) { 213 log(LOG_DEBUG, "%s: malloc failed\n", __func__); 214 break; 215 } 216 arp_allocated++; 217 /* 218 * We are storing a route entry outside of radix tree. So, 219 * it can be found and accessed by other means than radix 220 * lookup. The routing code assumes that any rtentry detached 221 * from radix can be destroyed safely. To prevent this, we 222 * add an additional reference. 223 */ 224 RT_ADDREF(rt); 225 la->la_rt = rt; 226 rt->rt_flags |= RTF_LLINFO; 227 callout_init_mtx(&la->la_timer, &rt->rt_mtx, 228 CALLOUT_RETURNUNLOCKED); 229 230 #ifdef INET 231 /* 232 * This keeps the multicast addresses from showing up 233 * in `arp -a' listings as unresolved. It's not actually 234 * functional. Then the same for broadcast. 235 */ 236 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) && 237 rt->rt_ifp->if_type != IFT_ARCNET) { 238 ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr, 239 LLADDR(SDL(gate))); 240 SDL(gate)->sdl_alen = 6; 241 rt->rt_expire = 0; 242 } 243 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) { 244 memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr, 245 rt->rt_ifp->if_addrlen); 246 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen; 247 rt->rt_expire = 0; 248 } 249 #endif 250 251 TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) { 252 if (ia->ia_ifp == rt->rt_ifp && 253 SIN(rt_key(rt))->sin_addr.s_addr == 254 (IA_SIN(ia))->sin_addr.s_addr) 255 break; 256 } 257 if (ia) { 258 /* 259 * This test used to be 260 * if (loif.if_flags & IFF_UP) 261 * It allowed local traffic to be forced 262 * through the hardware by configuring the loopback down. 263 * However, it causes problems during network configuration 264 * for boards that can't receive packets they send. 265 * It is now necessary to clear "useloopback" and remove 266 * the route to force traffic out to the hardware. 267 */ 268 rt->rt_expire = 0; 269 bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)), 270 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen); 271 if (useloopback) { 272 rt->rt_ifp = loif; 273 rt->rt_rmx.rmx_mtu = loif->if_mtu; 274 } 275 276 /* 277 * make sure to set rt->rt_ifa to the interface 278 * address we are using, otherwise we will have trouble 279 * with source address selection. 280 */ 281 ifa = &ia->ia_ifa; 282 if (ifa != rt->rt_ifa) { 283 IFAFREE(rt->rt_ifa); 284 IFAREF(ifa); 285 rt->rt_ifa = ifa; 286 } 287 } 288 break; 289 290 case RTM_DELETE: 291 if (la == NULL) /* XXX: at least CARP does this. */ 292 break; 293 callout_stop(&la->la_timer); 294 rt->rt_llinfo = NULL; 295 rt->rt_flags &= ~RTF_LLINFO; 296 RT_REMREF(rt); 297 if (la->la_hold) 298 m_freem(la->la_hold); 299 Free((caddr_t)la); 300 } 301 } 302 303 /* 304 * Broadcast an ARP request. Caller specifies: 305 * - arp header source ip address 306 * - arp header target ip address 307 * - arp header source ethernet address 308 */ 309 static void 310 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip, 311 u_char *enaddr) 312 { 313 struct mbuf *m; 314 struct arphdr *ah; 315 struct sockaddr sa; 316 317 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 318 return; 319 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 320 2*ifp->if_data.ifi_addrlen; 321 m->m_pkthdr.len = m->m_len; 322 MH_ALIGN(m, m->m_len); 323 ah = mtod(m, struct arphdr *); 324 bzero((caddr_t)ah, m->m_len); 325 #ifdef MAC 326 mac_netinet_arp_send(ifp, m); 327 #endif 328 ah->ar_pro = htons(ETHERTYPE_IP); 329 ah->ar_hln = ifp->if_addrlen; /* hardware address length */ 330 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ 331 ah->ar_op = htons(ARPOP_REQUEST); 332 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln); 333 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln); 334 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln); 335 sa.sa_family = AF_ARP; 336 sa.sa_len = 2; 337 m->m_flags |= M_BCAST; 338 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 339 340 return; 341 } 342 343 /* 344 * Resolve an IP address into an ethernet address. 345 * On input: 346 * ifp is the interface we use 347 * dst is the next hop, 348 * rt0 is the route to the final destination (possibly useless) 349 * m is the mbuf 350 * desten is where we want the address. 351 * 352 * On success, desten is filled in and the function returns 0; 353 * If the packet must be held pending resolution, we return EWOULDBLOCK 354 * On other errors, we return the corresponding error code. 355 */ 356 int 357 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, 358 struct sockaddr *dst, u_char *desten) 359 { 360 struct llinfo_arp *la = NULL; 361 struct rtentry *rt = NULL; 362 struct sockaddr_dl *sdl; 363 int error; 364 365 if (m->m_flags & M_BCAST) { /* broadcast */ 366 (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen); 367 return (0); 368 } 369 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */ 370 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 371 return (0); 372 } 373 374 if (rt0 != NULL) { 375 error = rt_check(&rt, &rt0, dst); 376 if (error) { 377 m_freem(m); 378 return error; 379 } 380 la = (struct llinfo_arp *)rt->rt_llinfo; 381 if (la == NULL) 382 RT_UNLOCK(rt); 383 } 384 if (la == NULL) { 385 /* 386 * We enter this block in case if rt0 was NULL, 387 * or if rt found by rt_check() didn't have llinfo. 388 */ 389 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); 390 if (rt == NULL) { 391 log(LOG_DEBUG, 392 "arpresolve: can't allocate route for %s\n", 393 inet_ntoa(SIN(dst)->sin_addr)); 394 m_freem(m); 395 return (EINVAL); /* XXX */ 396 } 397 la = (struct llinfo_arp *)rt->rt_llinfo; 398 if (la == NULL) { 399 RT_UNLOCK(rt); 400 log(LOG_DEBUG, 401 "arpresolve: can't allocate llinfo for %s\n", 402 inet_ntoa(SIN(dst)->sin_addr)); 403 m_freem(m); 404 return (EINVAL); /* XXX */ 405 } 406 } 407 sdl = SDL(rt->rt_gateway); 408 /* 409 * Check the address family and length is valid, the address 410 * is resolved; otherwise, try to resolve. 411 */ 412 if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) && 413 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { 414 415 bcopy(LLADDR(sdl), desten, sdl->sdl_alen); 416 417 /* 418 * If entry has an expiry time and it is approaching, 419 * send an ARP request. 420 */ 421 if ((rt->rt_expire != 0) && 422 (time_uptime + la->la_preempt > rt->rt_expire)) { 423 struct in_addr sin = 424 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 425 426 la->la_preempt--; 427 RT_UNLOCK(rt); 428 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 429 IF_LLADDR(ifp)); 430 return (0); 431 } 432 433 RT_UNLOCK(rt); 434 return (0); 435 } 436 /* 437 * If ARP is disabled or static on this interface, stop. 438 * XXX 439 * Probably should not allocate empty llinfo struct if we are 440 * not going to be sending out an arp request. 441 */ 442 if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) { 443 RT_UNLOCK(rt); 444 m_freem(m); 445 return (EINVAL); 446 } 447 /* 448 * There is an arptab entry, but no ethernet address 449 * response yet. Replace the held mbuf with this 450 * latest one. 451 */ 452 if (la->la_hold) 453 m_freem(la->la_hold); 454 la->la_hold = m; 455 KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry")); 456 457 /* 458 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 459 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 460 * if we have already sent arp_maxtries ARP requests. Retransmit the 461 * ARP request, but not faster than one request per second. 462 */ 463 if (la->la_asked < arp_maxtries) 464 error = EWOULDBLOCK; /* First request. */ 465 else 466 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH; 467 468 if (la->la_asked == 0 || rt->rt_expire != time_uptime) { 469 struct in_addr sin = 470 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 471 472 rt->rt_expire = time_uptime; 473 callout_reset(&la->la_timer, hz, arptimer, rt); 474 la->la_asked++; 475 RT_UNLOCK(rt); 476 477 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 478 IF_LLADDR(ifp)); 479 } else 480 RT_UNLOCK(rt); 481 482 return (error); 483 } 484 485 486 int 487 arpresolve2(struct ifnet *ifp, struct rtentry *rt0, struct sockaddr *dst, 488 u_char *desten) 489 { 490 struct llinfo_arp *la = NULL; 491 struct rtentry *rt = NULL; 492 struct sockaddr_dl *sdl; 493 int error; 494 495 if (rt0 != NULL) { 496 error = rt_check(&rt, &rt0, dst); 497 if (error) 498 return (error); 499 500 la = (struct llinfo_arp *)rt->rt_llinfo; 501 if (la == NULL) 502 RT_UNLOCK(rt); 503 } 504 if (la == NULL) { 505 /* 506 * We enter this block in case if rt0 was NULL, 507 * or if rt found by rt_check() didn't have llinfo. 508 */ 509 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); 510 if (rt == NULL) { 511 log(LOG_DEBUG, 512 "arpresolve: can't allocate route for %s\n", 513 inet_ntoa(SIN(dst)->sin_addr)); 514 return (EINVAL); /* XXX */ 515 } 516 la = (struct llinfo_arp *)rt->rt_llinfo; 517 if (la == NULL) { 518 RT_UNLOCK(rt); 519 log(LOG_DEBUG, 520 "arpresolve: can't allocate llinfo for %s\n", 521 inet_ntoa(SIN(dst)->sin_addr)); 522 return (EINVAL); /* XXX */ 523 } 524 } 525 sdl = SDL(rt->rt_gateway); 526 /* 527 * Check the address family and length is valid, the address 528 * is resolved; otherwise, try to resolve. 529 */ 530 if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) && 531 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { 532 533 bcopy(LLADDR(sdl), desten, sdl->sdl_alen); 534 535 /* 536 * If entry has an expiry time and it is approaching, 537 * send an ARP request. 538 */ 539 if ((rt->rt_expire != 0) && 540 (time_uptime + la->la_preempt > rt->rt_expire)) { 541 struct in_addr sin = 542 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 543 544 la->la_preempt--; 545 RT_UNLOCK(rt); 546 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 547 IF_LLADDR(ifp)); 548 return (0); 549 } 550 551 RT_UNLOCK(rt); 552 return (0); 553 } 554 /* 555 * If ARP is disabled or static on this interface, stop. 556 * XXX 557 * Probably should not allocate empty llinfo struct if we are 558 * not going to be sending out an arp request. 559 */ 560 if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) { 561 RT_UNLOCK(rt); 562 return (EINVAL); 563 } 564 KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry")); 565 566 /* 567 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It 568 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH 569 * if we have already sent arp_maxtries ARP requests. Retransmit the 570 * ARP request, but not faster than one request per second. 571 */ 572 if (la->la_asked < arp_maxtries) 573 error = EWOULDBLOCK; /* First request. */ 574 else 575 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH; 576 577 if (la->la_asked == 0 || rt->rt_expire != time_uptime) { 578 struct in_addr sin = 579 SIN(rt->rt_ifa->ifa_addr)->sin_addr; 580 581 rt->rt_expire = time_uptime; 582 callout_reset(&la->la_timer, hz, arptimer, rt); 583 la->la_asked++; 584 RT_UNLOCK(rt); 585 586 arprequest(ifp, &sin, &SIN(dst)->sin_addr, 587 IF_LLADDR(ifp)); 588 } else 589 RT_UNLOCK(rt); 590 591 return (error); 592 } 593 594 /* 595 * Common length and type checks are done here, 596 * then the protocol-specific routine is called. 597 */ 598 static void 599 arpintr(struct mbuf *m) 600 { 601 struct arphdr *ar; 602 603 if (m->m_len < sizeof(struct arphdr) && 604 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { 605 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); 606 return; 607 } 608 ar = mtod(m, struct arphdr *); 609 610 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && 611 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && 612 ntohs(ar->ar_hrd) != ARPHRD_ARCNET && 613 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { 614 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", 615 (unsigned char *)&ar->ar_hrd, ""); 616 m_freem(m); 617 return; 618 } 619 620 if (m->m_len < arphdr_len(ar)) { 621 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { 622 log(LOG_ERR, "arp: runt packet\n"); 623 m_freem(m); 624 return; 625 } 626 ar = mtod(m, struct arphdr *); 627 } 628 629 switch (ntohs(ar->ar_pro)) { 630 #ifdef INET 631 case ETHERTYPE_IP: 632 in_arpinput(m); 633 return; 634 #endif 635 } 636 m_freem(m); 637 } 638 639 #ifdef INET 640 /* 641 * ARP for Internet protocols on 10 Mb/s Ethernet. 642 * Algorithm is that given in RFC 826. 643 * In addition, a sanity check is performed on the sender 644 * protocol address, to catch impersonators. 645 * We no longer handle negotiations for use of trailer protocol: 646 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 647 * along with IP replies if we wanted trailers sent to us, 648 * and also sent them in response to IP replies. 649 * This allowed either end to announce the desire to receive 650 * trailer packets. 651 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 652 * but formerly didn't normally send requests. 653 */ 654 static int log_arp_wrong_iface = 1; 655 static int log_arp_movements = 1; 656 static int log_arp_permanent_modify = 1; 657 658 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, 659 &log_arp_wrong_iface, 0, 660 "log arp packets arriving on the wrong interface"); 661 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, 662 &log_arp_movements, 0, 663 "log arp replies from MACs different than the one in the cache"); 664 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, 665 &log_arp_permanent_modify, 0, 666 "log arp replies from MACs different than the one in the permanent arp entry"); 667 668 669 static void 670 in_arpinput(struct mbuf *m) 671 { 672 struct arphdr *ah; 673 struct ifnet *ifp = m->m_pkthdr.rcvif; 674 struct llinfo_arp *la; 675 struct rtentry *rt; 676 struct ifaddr *ifa; 677 struct in_ifaddr *ia; 678 struct sockaddr_dl *sdl; 679 struct sockaddr sa; 680 struct in_addr isaddr, itaddr, myaddr; 681 struct mbuf *hold; 682 u_int8_t *enaddr = NULL; 683 int op, rif_len; 684 int req_len; 685 int bridged = 0; 686 #ifdef DEV_CARP 687 int carp_match = 0; 688 #endif 689 struct sockaddr_in sin; 690 sin.sin_len = sizeof(struct sockaddr_in); 691 sin.sin_family = AF_INET; 692 sin.sin_addr.s_addr = 0; 693 694 if (ifp->if_bridge) 695 bridged = 1; 696 697 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 698 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { 699 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); 700 return; 701 } 702 703 ah = mtod(m, struct arphdr *); 704 op = ntohs(ah->ar_op); 705 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); 706 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); 707 708 /* 709 * For a bridge, we want to check the address irrespective 710 * of the receive interface. (This will change slightly 711 * when we have clusters of interfaces). 712 * If the interface does not match, but the recieving interface 713 * is part of carp, we call carp_iamatch to see if this is a 714 * request for the virtual host ip. 715 * XXX: This is really ugly! 716 */ 717 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { 718 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 719 (ia->ia_ifp == ifp)) && 720 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 721 goto match; 722 #ifdef DEV_CARP 723 if (ifp->if_carp != NULL && 724 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && 725 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { 726 carp_match = 1; 727 goto match; 728 } 729 #endif 730 } 731 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) 732 if (((bridged && ia->ia_ifp->if_bridge != NULL) || 733 (ia->ia_ifp == ifp)) && 734 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) 735 goto match; 736 /* 737 * No match, use the first inet address on the receive interface 738 * as a dummy address for the rest of the function. 739 */ 740 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) 741 if (ifa->ifa_addr->sa_family == AF_INET) { 742 ia = ifatoia(ifa); 743 goto match; 744 } 745 /* 746 * If bridging, fall back to using any inet address. 747 */ 748 if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL) 749 goto drop; 750 match: 751 if (!enaddr) 752 enaddr = (u_int8_t *)IF_LLADDR(ifp); 753 myaddr = ia->ia_addr.sin_addr; 754 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) 755 goto drop; /* it's from me, ignore it. */ 756 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { 757 log(LOG_ERR, 758 "arp: link address is broadcast for IP address %s!\n", 759 inet_ntoa(isaddr)); 760 goto drop; 761 } 762 /* 763 * Warn if another host is using the same IP address, but only if the 764 * IP address isn't 0.0.0.0, which is used for DHCP only, in which 765 * case we suppress the warning to avoid false positive complaints of 766 * potential misconfiguration. 767 */ 768 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { 769 log(LOG_ERR, 770 "arp: %*D is using my IP address %s on %s!\n", 771 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 772 inet_ntoa(isaddr), ifp->if_xname); 773 itaddr = myaddr; 774 goto reply; 775 } 776 if (ifp->if_flags & IFF_STATICARP) 777 goto reply; 778 rt = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); 779 if (rt != NULL) { 780 sin.sin_addr.s_addr = isaddr.s_addr; 781 EVENTHANDLER_INVOKE(route_arp_update_event, rt, 782 ar_sha(ah), (struct sockaddr *)&sin); 783 784 la = (struct llinfo_arp *)rt->rt_llinfo; 785 if (la == NULL) { 786 RT_UNLOCK(rt); 787 goto reply; 788 } 789 } else 790 goto reply; 791 792 /* The following is not an error when doing bridging. */ 793 if (!bridged && rt->rt_ifp != ifp 794 #ifdef DEV_CARP 795 && (ifp->if_type != IFT_CARP || !carp_match) 796 #endif 797 ) { 798 if (log_arp_wrong_iface) 799 log(LOG_ERR, "arp: %s is on %s but got reply from %*D on %s\n", 800 inet_ntoa(isaddr), 801 rt->rt_ifp->if_xname, 802 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 803 ifp->if_xname); 804 RT_UNLOCK(rt); 805 goto reply; 806 } 807 sdl = SDL(rt->rt_gateway); 808 if (sdl->sdl_alen && 809 bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) { 810 if (rt->rt_expire) { 811 if (log_arp_movements) 812 log(LOG_INFO, "arp: %s moved from %*D to %*D on %s\n", 813 inet_ntoa(isaddr), 814 ifp->if_addrlen, (u_char *)LLADDR(sdl), ":", 815 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 816 ifp->if_xname); 817 } else { 818 RT_UNLOCK(rt); 819 if (log_arp_permanent_modify) 820 log(LOG_ERR, "arp: %*D attempts to modify " 821 "permanent entry for %s on %s\n", 822 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 823 inet_ntoa(isaddr), ifp->if_xname); 824 goto reply; 825 } 826 } 827 /* 828 * sanity check for the address length. 829 * XXX this does not work for protocols with variable address 830 * length. -is 831 */ 832 if (sdl->sdl_alen && 833 sdl->sdl_alen != ah->ar_hln) { 834 log(LOG_WARNING, 835 "arp from %*D: new addr len %d, was %d", 836 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 837 ah->ar_hln, sdl->sdl_alen); 838 } 839 if (ifp->if_addrlen != ah->ar_hln) { 840 log(LOG_WARNING, 841 "arp from %*D: addr len: new %d, i/f %d (ignored)", 842 ifp->if_addrlen, (u_char *) ar_sha(ah), ":", 843 ah->ar_hln, ifp->if_addrlen); 844 RT_UNLOCK(rt); 845 goto reply; 846 } 847 (void)memcpy(LLADDR(sdl), ar_sha(ah), 848 sdl->sdl_alen = ah->ar_hln); 849 /* 850 * If we receive an arp from a token-ring station over 851 * a token-ring nic then try to save the source 852 * routing info. 853 */ 854 if (ifp->if_type == IFT_ISO88025) { 855 struct iso88025_header *th = NULL; 856 struct iso88025_sockaddr_dl_data *trld; 857 858 th = (struct iso88025_header *)m->m_pkthdr.header; 859 trld = SDL_ISO88025(sdl); 860 rif_len = TR_RCF_RIFLEN(th->rcf); 861 if ((th->iso88025_shost[0] & TR_RII) && 862 (rif_len > 2)) { 863 trld->trld_rcf = th->rcf; 864 trld->trld_rcf ^= htons(TR_RCF_DIR); 865 memcpy(trld->trld_route, th->rd, rif_len - 2); 866 trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK); 867 /* 868 * Set up source routing information for 869 * reply packet (XXX) 870 */ 871 m->m_data -= rif_len; 872 m->m_len += rif_len; 873 m->m_pkthdr.len += rif_len; 874 } else { 875 th->iso88025_shost[0] &= ~TR_RII; 876 trld->trld_rcf = 0; 877 } 878 m->m_data -= 8; 879 m->m_len += 8; 880 m->m_pkthdr.len += 8; 881 th->rcf = trld->trld_rcf; 882 } 883 if (rt->rt_expire) { 884 rt->rt_expire = time_uptime + arpt_keep; 885 callout_reset(&la->la_timer, hz * arpt_keep, arptimer, rt); 886 } 887 la->la_asked = 0; 888 la->la_preempt = arp_maxtries; 889 hold = la->la_hold; 890 la->la_hold = NULL; 891 RT_UNLOCK(rt); 892 if (hold != NULL) 893 (*ifp->if_output)(ifp, hold, rt_key(rt), rt); 894 895 reply: 896 if (op != ARPOP_REQUEST) 897 goto drop; 898 if (itaddr.s_addr == myaddr.s_addr) { 899 /* I am the target */ 900 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 901 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 902 } else { 903 rt = arplookup(itaddr.s_addr, 0, SIN_PROXY); 904 if (rt == NULL) { 905 struct sockaddr_in sin; 906 907 if (!arp_proxyall) 908 goto drop; 909 910 bzero(&sin, sizeof sin); 911 sin.sin_family = AF_INET; 912 sin.sin_len = sizeof sin; 913 sin.sin_addr = itaddr; 914 915 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 916 if (!rt) 917 goto drop; 918 /* 919 * Don't send proxies for nodes on the same interface 920 * as this one came out of, or we'll get into a fight 921 * over who claims what Ether address. 922 */ 923 if (rt->rt_ifp == ifp) { 924 rtfree(rt); 925 goto drop; 926 } 927 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 928 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); 929 rtfree(rt); 930 931 /* 932 * Also check that the node which sent the ARP packet 933 * is on the the interface we expect it to be on. This 934 * avoids ARP chaos if an interface is connected to the 935 * wrong network. 936 */ 937 sin.sin_addr = isaddr; 938 939 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); 940 if (!rt) 941 goto drop; 942 if (rt->rt_ifp != ifp) { 943 log(LOG_INFO, "arp_proxy: ignoring request" 944 " from %s via %s, expecting %s\n", 945 inet_ntoa(isaddr), ifp->if_xname, 946 rt->rt_ifp->if_xname); 947 rtfree(rt); 948 goto drop; 949 } 950 rtfree(rt); 951 952 #ifdef DEBUG_PROXY 953 printf("arp: proxying for %s\n", 954 inet_ntoa(itaddr)); 955 #endif 956 } else { 957 /* 958 * Return proxied ARP replies only on the interface 959 * or bridge cluster where this network resides. 960 * Otherwise we may conflict with the host we are 961 * proxying for. 962 */ 963 if (rt->rt_ifp != ifp && 964 (rt->rt_ifp->if_bridge != ifp->if_bridge || 965 ifp->if_bridge == NULL)) { 966 RT_UNLOCK(rt); 967 goto drop; 968 } 969 sdl = SDL(rt->rt_gateway); 970 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 971 (void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln); 972 RT_UNLOCK(rt); 973 } 974 } 975 976 if (itaddr.s_addr == myaddr.s_addr && 977 IN_LINKLOCAL(ntohl(itaddr.s_addr))) { 978 /* RFC 3927 link-local IPv4; always reply by broadcast. */ 979 #ifdef DEBUG_LINKLOCAL 980 printf("arp: sending reply for link-local addr %s\n", 981 inet_ntoa(itaddr)); 982 #endif 983 m->m_flags |= M_BCAST; 984 m->m_flags &= ~M_MCAST; 985 } else { 986 /* default behaviour; never reply by broadcast. */ 987 m->m_flags &= ~(M_BCAST|M_MCAST); 988 } 989 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 990 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 991 ah->ar_op = htons(ARPOP_REPLY); 992 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 993 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); 994 m->m_pkthdr.len = m->m_len; 995 sa.sa_family = AF_ARP; 996 sa.sa_len = 2; 997 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); 998 return; 999 1000 drop: 1001 m_freem(m); 1002 } 1003 #endif 1004 1005 /* 1006 * Lookup or enter a new address in arptab. 1007 */ 1008 static struct rtentry * 1009 arplookup(u_long addr, int create, int proxy) 1010 { 1011 struct rtentry *rt; 1012 struct sockaddr_inarp sin; 1013 const char *why = 0; 1014 1015 bzero(&sin, sizeof(sin)); 1016 sin.sin_len = sizeof(sin); 1017 sin.sin_family = AF_INET; 1018 sin.sin_addr.s_addr = addr; 1019 if (proxy) 1020 sin.sin_other = SIN_PROXY; 1021 rt = rtalloc1((struct sockaddr *)&sin, create, 0UL); 1022 if (rt == 0) 1023 return (0); 1024 1025 if (rt->rt_flags & RTF_GATEWAY) 1026 why = "host is not on local network"; 1027 else if ((rt->rt_flags & RTF_LLINFO) == 0) 1028 why = "could not allocate llinfo"; 1029 else if (rt->rt_gateway->sa_family != AF_LINK) 1030 why = "gateway route is not ours"; 1031 1032 if (why) { 1033 #define ISDYNCLONE(_rt) \ 1034 (((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED) 1035 if (create) 1036 log(LOG_DEBUG, "arplookup %s failed: %s\n", 1037 inet_ntoa(sin.sin_addr), why); 1038 /* 1039 * If there are no references to this Layer 2 route, 1040 * and it is a cloned route, and not static, and 1041 * arplookup() is creating the route, then purge 1042 * it from the routing table as it is probably bogus. 1043 */ 1044 if (rt->rt_refcnt == 1 && ISDYNCLONE(rt)) 1045 rtexpunge(rt); 1046 RTFREE_LOCKED(rt); 1047 return (0); 1048 #undef ISDYNCLONE 1049 } else { 1050 RT_REMREF(rt); 1051 return (rt); 1052 } 1053 } 1054 1055 void 1056 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) 1057 { 1058 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 1059 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 1060 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); 1061 ifa->ifa_rtrequest = arp_rtrequest; 1062 ifa->ifa_flags |= RTF_CLONING; 1063 } 1064 1065 void 1066 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr) 1067 { 1068 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) 1069 arprequest(ifp, &IA_SIN(ifa)->sin_addr, 1070 &IA_SIN(ifa)->sin_addr, enaddr); 1071 ifa->ifa_rtrequest = arp_rtrequest; 1072 ifa->ifa_flags |= RTF_CLONING; 1073 } 1074 1075 static void 1076 arp_init(void) 1077 { 1078 1079 arpintrq.ifq_maxlen = 50; 1080 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); 1081 netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE); 1082 } 1083 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0); 1084