bsd/netinet/in_arp.c

   1 /*
   2  * Copyright (c) 2004-2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * Copyright (c) 1982, 1989, 1993
  30  *      The Regents of the University of California.  All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  */
  61
  62 #include <kern/debug.h>
  63 #include <netinet/in_arp.h>
  64 #include <sys/types.h>
  65 #include <sys/param.h>
  66 #include <sys/kernel_types.h>
  67 #include <sys/syslog.h>
  68 #include <sys/systm.h>
  69 #include <sys/time.h>
  70 #include <sys/kernel.h>
  71 #include <sys/mbuf.h>
  72 #include <sys/sysctl.h>
  73 #include <string.h>
  74 #include <net/if_arp.h>
  75 #include <net/if_dl.h>
  76 #include <net/dlil.h>
  77 #include <net/route.h>
  78 #include <netinet/if_ether.h>
  79 #include <netinet/in_var.h>
  80
  81 #define SIN(s) ((struct sockaddr_in *)s)
  82 #define CONST_LLADDR(s) ((const u_char*)((s)->sdl_data + (s)->sdl_nlen))
  83 #define rt_expire rt_rmx.rmx_expire
  84
  85 static const size_t MAX_HW_LEN = 10;
  86
  87 SYSCTL_DECL(_net_link_ether);
  88 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW|CTLFLAG_LOCKED, 0, "");
  89
  90 /* timer values */
  91 static int arpt_prune = (5*60*1); /* walk list every 5 minutes */
  92 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
  93 static int arpt_down = 20;      /* once declared down, don't send for 20 sec */
  94
  95 /* Apple Hardware SUM16 checksuming */
  96 int apple_hwcksum_tx = 1;
  97 int apple_hwcksum_rx = 1;
  98
  99 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW,
 100            &arpt_prune, 0, "");
 101 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
 102            &arpt_keep, 0, "");
 103 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, host_down_time, CTLFLAG_RW,
 104            &arpt_down, 0, "");
 105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, apple_hwcksum_tx, CTLFLAG_RW,
 106            &apple_hwcksum_tx, 0, "");
 107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, apple_hwcksum_rx, CTLFLAG_RW,
 108            &apple_hwcksum_rx, 0, "");
 109
 110 struct llinfo_arp {
 111         LIST_ENTRY(llinfo_arp) la_le;
 112         struct  rtentry *la_rt;
 113         struct  mbuf *la_hold;          /* last packet until resolved/timeout */
 114         long    la_asked;               /* last time we QUERIED for this addr */
 115 };
 116
 117 static LIST_HEAD(, llinfo_arp) llinfo_arp;
 118
 119 static int      arp_inuse, arp_allocated;
 120
 121 static int      arp_maxtries = 5;
 122 static int      useloopback = 1; /* use loopback interface for local traffic */
 123 static int      arp_proxyall = 0;
 124 static int      arp_sendllconflict = 0;
 125
 126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
 127            &arp_maxtries, 0, "");
 128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
 129            &useloopback, 0, "");
 130 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
 131            &arp_proxyall, 0, "");
 132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, sendllconflict, CTLFLAG_RW,
 133            &arp_sendllconflict, 0, "");
 134
 135 static int log_arp_warnings = 0;
 136
 137 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_warnings, CTLFLAG_RW,
 138         &log_arp_warnings, 0,
 139         "log arp warning messages");
 140
 141 static int keep_announcements = 1;
 142 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, keep_announcements, CTLFLAG_RW,
 143         &keep_announcements, 0,
 144         "keep arp announcements");
 145
 146 static int send_conflicting_probes = 1;
 147 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, send_conflicting_probes, CTLFLAG_RW,
 148         &send_conflicting_probes, 0,
 149         "send conflicting link-local arp probes");
 150
 151 extern u_int32_t        ipv4_ll_arp_aware;
 152
 153 /*
 154  * Free an arp entry.
 155  */
 156 static void
 157 arptfree(
 158         struct llinfo_arp *la)
 159 {
 160         struct rtentry *rt = la->la_rt;
 161         struct sockaddr_dl *sdl;
 162         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 163         if (rt == 0)
 164                 panic("arptfree");
 165         if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) &&
 166             sdl->sdl_family == AF_LINK) {
 167                 sdl->sdl_alen = 0;
 168                 la->la_asked = 0;
 169                 rt->rt_flags &= ~RTF_REJECT;
 170                 return;
 171         }
 172         rtrequest_locked(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt),
 173                         0, (struct rtentry **)0);
 174 }
 175
 176 /*
 177  * Timeout routine.  Age arp_tab entries periodically.
 178  */
 179 /* ARGSUSED */
 180 static void
 181 arptimer(void *ignored_arg)
 182 {
 183 #pragma unused (ignored_arg)
 184         struct llinfo_arp *la, *ola;
 185         struct timeval timenow;
 186
 187         lck_mtx_lock(rt_mtx);
 188         la = llinfo_arp.lh_first;
 189         getmicrotime(&timenow);
 190         while ((ola = la) != 0) {
 191                 struct rtentry *rt = la->la_rt;
 192                 la = la->la_le.le_next;
 193                 if (rt->rt_expire && rt->rt_expire <= timenow.tv_sec)
 194                         arptfree(ola); /* timer has expired, clear */
 195         }
 196         lck_mtx_unlock(rt_mtx);
 197         timeout(arptimer, (caddr_t)0, arpt_prune * hz);
 198 }
 199
 200 /*
 201  * Parallel to llc_rtrequest.
 202  */
 203 static void
 204 arp_rtrequest(
 205         int req,
 206         struct rtentry *rt,
 207         __unused struct sockaddr *sa)
 208 {
 209         struct sockaddr *gate = rt->rt_gateway;
 210         struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
 211         static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK, 0, 0, 0, 0, 0, {0}};
 212         static int arpinit_done;
 213         struct timeval timenow;
 214
 215         if (!arpinit_done) {
 216                 arpinit_done = 1;
 217                 LIST_INIT(&llinfo_arp);
 218                 timeout(arptimer, (caddr_t)0, hz);
 219         }
 220         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 221
 222         if (rt->rt_flags & RTF_GATEWAY)
 223                 return;
 224         getmicrotime(&timenow);
 225         switch (req) {
 226
 227         case RTM_ADD:
 228                 /*
 229                  * XXX: If this is a manually added route to interface
 230                  * such as older version of routed or gated might provide,
 231                  * restore cloning bit.
 232                  */
 233                 if ((rt->rt_flags & RTF_HOST) == 0 &&
 234                     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
 235                         rt->rt_flags |= RTF_CLONING;
 236                 if (rt->rt_flags & RTF_CLONING) {
 237                         /*
 238                          * Case 1: This route should come from a route to iface.
 239                          */
 240                         rt_setgate(rt, rt_key(rt),
 241                                         (struct sockaddr *)&null_sdl);
 242                         gate = rt->rt_gateway;
 243                         SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 244                         SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 245                         rt->rt_expire = timenow.tv_sec;
 246                         break;
 247                 }
 248                 /* Announce a new entry if requested. */
 249                 if (rt->rt_flags & RTF_ANNOUNCE)
 250                         dlil_send_arp(rt->rt_ifp, ARPOP_REQUEST, SDL(gate), rt_key(rt), (struct sockaddr_dl *)rt_key(rt), NULL);
 251                 /*FALLTHROUGH*/
 252         case RTM_RESOLVE:
 253                 if (gate->sa_family != AF_LINK ||
 254                     gate->sa_len < sizeof(null_sdl)) {
 255                         if (log_arp_warnings)
 256                                 log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
 257                         break;
 258                 }
 259                 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 260                 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 261                 if (la != 0)
 262                         break; /* This happens on a route change */
 263                 /*
 264                  * Case 2:  This route may come from cloning, or a manual route
 265                  * add with a LL address.
 266                  */
 267                 R_Malloc(la, struct llinfo_arp *, sizeof(*la));
 268                 rt->rt_llinfo = (caddr_t)la;
 269                 if (la == 0) {
 270                         if ( log_arp_warnings)
 271                                 log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
 272                         break;
 273                 }
 274                 arp_inuse++, arp_allocated++;
 275                 Bzero(la, sizeof(*la));
 276                 la->la_rt = rt;
 277                 rt->rt_flags |= RTF_LLINFO;
 278                 LIST_INSERT_HEAD(&llinfo_arp, la, la_le);
 279
 280 #if INET
 281                 /*
 282                  * This keeps the multicast addresses from showing up
 283                  * in `arp -a' listings as unresolved.  It's not actually
 284                  * functional.  Then the same for broadcast.
 285                  */
 286                 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr))) {
 287                         dlil_resolve_multi(rt->rt_ifp, rt_key(rt), gate, sizeof(struct sockaddr_dl));
 288                         rt->rt_expire = 0;
 289                 }
 290                 else if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
 291                         struct sockaddr_dl      *gate_ll = SDL(gate);
 292                         size_t  broadcast_len;
 293                         ifnet_llbroadcast_copy_bytes(rt->rt_ifp, LLADDR(gate_ll),
 294                                                                                  sizeof(gate_ll->sdl_data),
 295                                                                                  &broadcast_len);
 296                         gate_ll->sdl_alen = broadcast_len;
 297                         gate_ll->sdl_family = AF_LINK;
 298                         gate_ll->sdl_len = sizeof(struct sockaddr_dl);
 299                         rt->rt_expire = timenow.tv_sec;
 300                 }
 301 #endif
 302
 303                 if (SIN(rt_key(rt))->sin_addr.s_addr ==
 304                     (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) {
 305                     /*
 306                      * This test used to be
 307                      *  if (loif.if_flags & IFF_UP)
 308                      * It allowed local traffic to be forced
 309                      * through the hardware by configuring the loopback down.
 310                      * However, it causes problems during network configuration
 311                      * for boards that can't receive packets they send.
 312                      * It is now necessary to clear "useloopback" and remove
 313                      * the route to force traffic out to the hardware.
 314                      */
 315                         rt->rt_expire = 0;
 316                         ifnet_lladdr_copy_bytes(rt->rt_ifp, LLADDR(SDL(gate)), SDL(gate)->sdl_alen = 6);
 317                         if (useloopback)
 318                                 rt->rt_ifp = lo_ifp;
 319
 320                 }
 321                 break;
 322
 323         case RTM_DELETE:
 324                 if (la == 0)
 325                         break;
 326                 arp_inuse--;
 327                 LIST_REMOVE(la, la_le);
 328                 rt->rt_llinfo = NULL;
 329                 rt->rt_flags &= ~RTF_LLINFO;
 330                 if (la->la_hold) {
 331                         m_freem(la->la_hold);
 332                 }
 333                 la->la_hold = NULL;
 334                 R_Free((caddr_t)la);
 335         }
 336 }
 337
 338 /*
 339  * convert hardware address to hex string for logging errors.
 340  */
 341 static const char *
 342 sdl_addr_to_hex(const struct sockaddr_dl *sdl, char * orig_buf, int buflen)
 343 {
 344         char *          buf = orig_buf;
 345         int             i;
 346         const u_char *  lladdr = (u_char *)sdl->sdl_data;
 347         int                     maxbytes = buflen / 3;
 348
 349         if (maxbytes > sdl->sdl_alen) {
 350                 maxbytes = sdl->sdl_alen;
 351         }
 352         *buf = '\0';
 353         for (i = 0; i < maxbytes; i++) {
 354                 snprintf(buf, 3, "%02x", lladdr[i]);
 355                 buf += 2;
 356                 *buf = (i == maxbytes - 1) ? '\0' : ':';
 357                 buf++;
 358         }
 359         return (orig_buf);
 360 }
 361
 362 /*
 363  * arp_lookup_route will lookup the route for a given address.
 364  *
 365  * The routing lock must be held. The address must be for a
 366  * host on a local network on this interface.
 367  */
 368 static errno_t
 369 arp_lookup_route(
 370         const struct in_addr *addr,
 371         int     create,
 372         int proxy,
 373         route_t *route)
 374 {
 375         struct sockaddr_inarp sin = {sizeof(sin), AF_INET, 0, {0}, {0}, 0, 0};
 376         const char *why = NULL;
 377         errno_t error = 0;
 378
 379         // Caller is responsible for taking the routing lock
 380         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 381
 382         sin.sin_addr.s_addr = addr->s_addr;
 383         sin.sin_other = proxy ? SIN_PROXY : 0;
 384
 385         *route = rtalloc1_locked((struct sockaddr*)&sin, create, 0);
 386         if (*route == NULL)
 387                 return ENETUNREACH;
 388
 389         rtunref(*route);
 390
 391         if ((*route)->rt_flags & RTF_GATEWAY) {
 392                 why = "host is not on local network";
 393
 394                 /* If there are no references to this route, purge it */
 395                 if ((*route)->rt_refcnt <= 0 && ((*route)->rt_flags & RTF_WASCLONED) != 0) {
 396                         rtrequest_locked(RTM_DELETE,
 397                                         (struct sockaddr *)rt_key(*route),
 398                                         (*route)->rt_gateway, rt_mask(*route),
 399                                         (*route)->rt_flags, 0);
 400                 }
 401                 *route = NULL;
 402                 error = ENETUNREACH;
 403         }
 404         else if (((*route)->rt_flags & RTF_LLINFO) == 0) {
 405                 why = "could not allocate llinfo";
 406                 *route = NULL;
 407                 error = ENOMEM;
 408         }
 409         else if ((*route)->rt_gateway->sa_family != AF_LINK) {
 410                 why = "gateway route is not ours";
 411                 *route = NULL;
 412                 error = EPROTONOSUPPORT;
 413         }
 414
 415         if (why && create && log_arp_warnings) {
 416                 char    tmp[MAX_IPv4_STR_LEN];
 417                 log(LOG_DEBUG, "arplookup %s failed: %s\n",
 418                         inet_ntop(AF_INET, addr, tmp, sizeof(tmp)), why);
 419         }
 420
 421         return error;
 422 }
 423
 424
 425 __private_extern__ errno_t
 426 arp_route_to_gateway_route(
 427         const struct sockaddr *net_dest,
 428         route_t hint,
 429         route_t *out_route);
 430 /*
 431  * arp_route_to_gateway_route will find the gateway route for a given route.
 432  *
 433  * If the route is down, look the route up again.
 434  * If the route goes through a gateway, get the route to the gateway.
 435  * If the gateway route is down, look it up again.
 436  * If the route is set to reject, verify it hasn't expired.
 437  */
 438 __private_extern__ errno_t
 439 arp_route_to_gateway_route(
 440         const struct sockaddr *net_dest,
 441         route_t hint,
 442         route_t *out_route)
 443 {
 444         struct timeval timenow;
 445         route_t route = hint;
 446         *out_route = NULL;
 447
 448         /* If we got a hint from the higher layers, check it out */
 449         if (route) {
 450                 lck_mtx_lock(rt_mtx);
 451
 452                 if ((route->rt_flags & RTF_UP) == 0) {
 453                         /* route is down, find a new one */
 454                         hint = route = rtalloc1_locked(net_dest, 1, 0);
 455                         if (hint) {
 456                                 rtunref(hint);
 457                         }
 458                         else {
 459                                 /* No route to host */
 460                                 lck_mtx_unlock(rt_mtx);
 461                                 return EHOSTUNREACH;
 462                         }
 463                 }
 464
 465                 if (route->rt_flags & RTF_GATEWAY) {
 466                         /*
 467                          * We need the gateway route. If it is NULL or down,
 468                          * look it up.
 469                          */
 470                         if (route->rt_gwroute == 0 ||
 471                                 (route->rt_gwroute->rt_flags & RTF_UP) == 0) {
 472                                 if (route->rt_gwroute != 0)
 473                                         rtfree_locked(route->rt_gwroute);
 474
 475                                 route->rt_gwroute = rtalloc1_locked(route->rt_gateway, 1, 0);
 476                                 if (route->rt_gwroute == 0) {
 477                                         lck_mtx_unlock(rt_mtx);
 478                                         return EHOSTUNREACH;
 479                                 }
 480                         }
 481
 482                         route = route->rt_gwroute;
 483                 }
 484
 485                 if (route->rt_flags & RTF_REJECT) {
 486                         getmicrotime(&timenow);
 487                         if (route->rt_rmx.rmx_expire == 0 ||
 488                                 timenow.tv_sec < route->rt_rmx.rmx_expire) {
 489                                 lck_mtx_unlock(rt_mtx);
 490                                 return route == hint ? EHOSTDOWN : EHOSTUNREACH;
 491                         }
 492                 }
 493
 494                 lck_mtx_unlock(rt_mtx);
 495         }
 496
 497         *out_route = route;
 498         return 0;
 499 }
 500
 501 errno_t
 502 arp_lookup_ip(
 503         ifnet_t ifp,
 504         const struct sockaddr_in *net_dest,
 505         struct sockaddr_dl *ll_dest,
 506         size_t  ll_dest_len,
 507         route_t hint,
 508         mbuf_t packet)
 509 {
 510         route_t route = NULL;
 511         errno_t result = 0;
 512         struct sockaddr_dl      *gateway;
 513         struct llinfo_arp       *llinfo;
 514         struct timeval timenow;
 515
 516         if (net_dest->sin_family != AF_INET)
 517                 return EAFNOSUPPORT;
 518
 519         if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 520                 return ENETDOWN;
 521
 522         /*
 523          * If we were given a route, verify the route and grab the gateway
 524          */
 525         if (hint) {
 526                 result = arp_route_to_gateway_route((const struct sockaddr*)net_dest,
 527                                                                                         hint, &route);
 528                 if (result != 0)
 529                         return result;
 530         }
 531
 532         if (packet->m_flags & M_BCAST) {
 533                 u_long  broadcast_len;
 534                 bzero(ll_dest, ll_dest_len);
 535                 result = ifnet_llbroadcast_copy_bytes(ifp, LLADDR(ll_dest), ll_dest_len
 536                                                                                           - offsetof(struct sockaddr_dl,
 537                                                                                           sdl_data), &broadcast_len);
 538                 if (result != 0) {
 539                         return result;
 540                 }
 541
 542                 ll_dest->sdl_alen = broadcast_len;
 543                 ll_dest->sdl_family = AF_LINK;
 544                 ll_dest->sdl_len = sizeof(struct sockaddr_dl);
 545
 546                 return 0;
 547         }
 548         if (packet->m_flags & M_MCAST) {
 549                 return dlil_resolve_multi(ifp, (const struct sockaddr*)net_dest,
 550                                                                    (struct sockaddr*)ll_dest, ll_dest_len);
 551         }
 552
 553         lck_mtx_lock(rt_mtx);
 554
 555         /*
 556          * If we didn't find a route, or the route doesn't have
 557          * link layer information, trigger the creation of the
 558          * route and link layer information.
 559          */
 560         if (route == NULL || route->rt_llinfo == NULL)
 561                 result = arp_lookup_route(&net_dest->sin_addr, 1, 0, &route);
 562
 563         if (result || route == NULL || route->rt_llinfo == NULL) {
 564                 char    tmp[MAX_IPv4_STR_LEN];
 565                 lck_mtx_unlock(rt_mtx);
 566                 if (log_arp_warnings)
 567                         log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s\n",
 568                                 inet_ntop(AF_INET, &net_dest->sin_addr, tmp, sizeof(tmp)));
 569                 return result;
 570         }
 571
 572         /*
 573          * Now that we have the right route, is it filled in?
 574          */
 575         gateway = SDL(route->rt_gateway);
 576         getmicrotime(&timenow);
 577         if ((route->rt_rmx.rmx_expire == 0 || route->rt_rmx.rmx_expire > timenow.tv_sec) &&
 578                 gateway != NULL && gateway->sdl_family == AF_LINK && gateway->sdl_alen != 0) {
 579                 bcopy(gateway, ll_dest, MIN(gateway->sdl_len, ll_dest_len));
 580                 lck_mtx_unlock(rt_mtx);
 581                 return 0;
 582         }
 583
 584         /*
 585          * Route wasn't complete/valid. We need to arp.
 586          */
 587         if (ifp->if_flags & IFF_NOARP) {
 588                 lck_mtx_unlock(rt_mtx);
 589                 return ENOTSUP;
 590         }
 591
 592         llinfo = (struct llinfo_arp*)route->rt_llinfo;
 593         if (packet) {
 594                 if (llinfo->la_hold) {
 595                         m_freem(llinfo->la_hold);
 596                 }
 597                 llinfo->la_hold = packet;
 598         }
 599
 600         if (route->rt_rmx.rmx_expire) {
 601                 route->rt_flags &= ~RTF_REJECT;
 602                 if (llinfo->la_asked == 0 || route->rt_rmx.rmx_expire != timenow.tv_sec) {
 603                         route->rt_rmx.rmx_expire = timenow.tv_sec;
 604                         if (llinfo->la_asked++ < arp_maxtries) {
 605                                 lck_mtx_unlock(rt_mtx);
 606                                 dlil_send_arp(ifp, ARPOP_REQUEST, NULL, route->rt_ifa->ifa_addr,
 607                                                           NULL, (const struct sockaddr*)net_dest);
 608                                 return EJUSTRETURN;
 609                         }
 610                         else {
 611                                 route->rt_flags |= RTF_REJECT;
 612                                 route->rt_rmx.rmx_expire += arpt_down;
 613                                 llinfo->la_asked = 0;
 614                                 llinfo->la_hold = NULL;
 615                                 lck_mtx_unlock(rt_mtx);
 616                                 return EHOSTUNREACH;
 617                         }
 618                 }
 619         }
 620         lck_mtx_unlock(rt_mtx);
 621
 622         return EJUSTRETURN;
 623 }
 624
 625 errno_t
 626 arp_ip_handle_input(
 627         ifnet_t         ifp,
 628         u_short         arpop,
 629         const struct sockaddr_dl *sender_hw,
 630         const struct sockaddr_in *sender_ip,
 631         const struct sockaddr_in *target_ip)
 632 {
 633         char    ipv4str[MAX_IPv4_STR_LEN];
 634         struct sockaddr_dl *gateway;
 635         struct in_ifaddr *ia;
 636         struct in_ifaddr *best_ia = NULL;
 637         route_t route = NULL;
 638         char buf[3 * MAX_HW_LEN]; // enough for MAX_HW_LEN byte hw address
 639         struct llinfo_arp *llinfo;
 640         errno_t error;
 641         int created_announcement = 0;
 642
 643         /* Do not respond to requests for 0.0.0.0 */
 644         if (target_ip->sin_addr.s_addr == 0 && arpop == ARPOP_REQUEST) {
 645                 return 0;
 646         }
 647
 648         /*
 649          * Determine if this ARP is for us
 650          */
 651         lck_mtx_lock(rt_mtx);
 652         for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
 653                 /* do_bridge should be tested here for bridging */
 654                 if (ia->ia_ifp == ifp) {
 655                         best_ia = ia;
 656                         if (target_ip->sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr ||
 657                                 sender_ip->sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr) {
 658                                 break;
 659                         }
 660                 }
 661         }
 662
 663         /* If we don't have an IP address on this interface, ignore the packet */
 664         if (best_ia == 0) {
 665                 lck_mtx_unlock(rt_mtx);
 666                 return 0;
 667         }
 668
 669         /* If the packet is from this interface, ignore the packet */
 670         if (!bcmp(CONST_LLADDR(sender_hw), ifnet_lladdr(ifp), sender_hw->sdl_len)) {
 671                 lck_mtx_unlock(rt_mtx);
 672                 return 0;
 673         }
 674
 675         /* Check for a conflict */
 676         if (sender_ip->sin_addr.s_addr == best_ia->ia_addr.sin_addr.s_addr) {
 677                 struct kev_msg        ev_msg;
 678                 struct kev_in_collision *in_collision;
 679                 u_char  storage[sizeof(struct kev_in_collision) + MAX_HW_LEN];
 680                 in_collision = (struct kev_in_collision*)storage;
 681                 log(LOG_ERR, "%s%d duplicate IP address %s sent from address %s\n",
 682                         ifp->if_name, ifp->if_unit,
 683                         inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str, sizeof(ipv4str)),
 684                         sdl_addr_to_hex(sender_hw, buf, sizeof(buf)));
 685
 686                 /* Send a kernel event so anyone can learn of the conflict */
 687                 in_collision->link_data.if_family = ifp->if_family;
 688                 in_collision->link_data.if_unit = ifp->if_unit;
 689                 strncpy(&in_collision->link_data.if_name[0], ifp->if_name, IFNAMSIZ);
 690                 in_collision->ia_ipaddr = sender_ip->sin_addr;
 691                 in_collision->hw_len = sender_hw->sdl_alen < MAX_HW_LEN ? sender_hw->sdl_alen : MAX_HW_LEN;
 692                 bcopy(CONST_LLADDR(sender_hw), (caddr_t)in_collision->hw_addr, in_collision->hw_len);
 693                 ev_msg.vendor_code = KEV_VENDOR_APPLE;
 694                 ev_msg.kev_class = KEV_NETWORK_CLASS;
 695                 ev_msg.kev_subclass = KEV_INET_SUBCLASS;
 696                 ev_msg.event_code = KEV_INET_ARPCOLLISION;
 697                 ev_msg.dv[0].data_ptr = in_collision;
 698                 ev_msg.dv[0].data_length = sizeof(struct kev_in_collision) + in_collision->hw_len;
 699                 ev_msg.dv[1].data_length = 0;
 700                 kev_post_msg(&ev_msg);
 701
 702                 goto respond;
 703         }
 704
 705         /*
 706          * Look up the routing entry. If it doesn't exist and we are the
 707          * target, go ahead and create one.
 708          */
 709         error = arp_lookup_route(&sender_ip->sin_addr, (target_ip->sin_addr.s_addr ==
 710                                 best_ia->ia_addr.sin_addr.s_addr), 0, &route);
 711         if (error || route == 0 || route->rt_gateway == 0) {
 712                 if (arpop != ARPOP_REQUEST) {
 713                         goto respond;
 714                 }
 715                 if (arp_sendllconflict
 716                     && send_conflicting_probes != 0
 717                     && (ifp->if_eflags & IFEF_ARPLL) != 0
 718                     && IN_LINKLOCAL(ntohl(target_ip->sin_addr.s_addr))
 719                     && sender_ip->sin_addr.s_addr == 0) {
 720                         /*
 721                          * Verify this ARP probe doesn't conflict with an IPv4LL we know of
 722                          * on another interface.
 723                          */
 724                         error = arp_lookup_route(&target_ip->sin_addr, 0, 0, &route);
 725                         if (error == 0 && route && route->rt_gateway) {
 726                                 gateway = SDL(route->rt_gateway);
 727                                 if (route->rt_ifp != ifp && gateway->sdl_alen != 0
 728                                     && (gateway->sdl_alen != sender_hw->sdl_alen
 729                                         || bcmp(CONST_LLADDR(gateway), CONST_LLADDR(sender_hw),
 730                                                 gateway->sdl_alen) != 0)) {
 731                                         /*
 732                                          * A node is probing for an IPv4LL we know exists on a
 733                                          * different interface. We respond with a conflicting probe
 734                                          * to force the new device to pick a different IPv4LL
 735                                          * address.
 736                                          */
 737                                         if (log_arp_warnings) {
 738                                             log(LOG_INFO,
 739                                                 "arp: %s on %s%d sent probe for %s, already on %s%d\n",
 740                                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 741                                                 ifp->if_name, ifp->if_unit,
 742                                                 inet_ntop(AF_INET, &target_ip->sin_addr, ipv4str,
 743                                                                   sizeof(ipv4str)),
 744                                                 route->rt_ifp->if_name, route->rt_ifp->if_unit);
 745                                             log(LOG_INFO,
 746                                                 "arp: sending conflicting probe to %s on %s%d\n",
 747                                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 748                                                 ifp->if_name, ifp->if_unit);
 749                                         }
 750                                         /*
 751                                          * Send a conservative unicast "ARP probe".
 752                                          * This should force the other device to pick a new number.
 753                                          * This will not force the device to pick a new number if the device
 754                                          * has already assigned that number.
 755                                          * This will not imply to the device that we own that address.
 756                                          */
 757                                         dlil_send_arp_internal(ifp, ARPOP_REQUEST,
 758                                                 (struct sockaddr_dl*)TAILQ_FIRST(&ifp->if_addrhead)->ifa_addr,
 759                                                 (const struct sockaddr*)sender_ip, sender_hw,
 760                                                 (const struct sockaddr*)target_ip);
 761                                 }
 762                         }
 763                         goto respond;
 764                 } else if (keep_announcements != 0
 765                            && target_ip->sin_addr.s_addr == sender_ip->sin_addr.s_addr) {
 766                         /* don't create entry if link-local address and link-local is disabled */
 767                         if (!IN_LINKLOCAL(ntohl(sender_ip->sin_addr.s_addr))
 768                             || (ifp->if_eflags & IFEF_ARPLL) != 0) {
 769                                 error = arp_lookup_route(&sender_ip->sin_addr, 1, 0, &route);
 770                                 if (error == 0 && route != NULL && route->rt_gateway != NULL) {
 771                                         created_announcement = 1;
 772                                 }
 773                         }
 774                         if (created_announcement == 0) {
 775                                 goto respond;
 776                         }
 777                 } else {
 778                         goto respond;
 779                 }
 780         }
 781
 782         gateway = SDL(route->rt_gateway);
 783         if (route->rt_ifp != ifp) {
 784                 if (!IN_LINKLOCAL(ntohl(sender_ip->sin_addr.s_addr)) || (ifp->if_eflags & IFEF_ARPLL) == 0) {
 785                         if (log_arp_warnings)
 786                                 log(LOG_ERR, "arp: %s is on %s%d but got reply from %s on %s%d\n",
 787                                         inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 788                                                           sizeof(ipv4str)),
 789                                         route->rt_ifp->if_name,
 790                                         route->rt_ifp->if_unit,
 791                                         sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 792                                         ifp->if_name, ifp->if_unit);
 793                         goto respond;
 794                 }
 795                 else {
 796                         /* Don't change a permanent address */
 797                         if (route->rt_rmx.rmx_expire == 0) {
 798                                 goto respond;
 799                         }
 800
 801                         /*
 802                          * Don't change the cloned route away from the parent's interface
 803                          * if the address did resolve.
 804                          */
 805                         if (gateway->sdl_alen != 0 && route->rt_parent &&
 806                                 route->rt_parent->rt_ifp == route->rt_ifp) {
 807                                 goto respond;
 808                         }
 809
 810                         /* Change the interface when the existing route is on */
 811                         route->rt_ifp = ifp;
 812                         rtsetifa(route, &best_ia->ia_ifa);
 813                         gateway->sdl_index = ifp->if_index;
 814                 }
 815         }
 816
 817         if (gateway->sdl_alen && bcmp(LLADDR(gateway), CONST_LLADDR(sender_hw), gateway->sdl_alen)) {
 818                 if (route->rt_rmx.rmx_expire && log_arp_warnings) {
 819                         char buf2[3 * MAX_HW_LEN];
 820                         log(LOG_INFO, "arp: %s moved from %s to %s on %s%d\n",
 821                             inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 822                             sizeof(ipv4str)),
 823                             sdl_addr_to_hex(gateway, buf, sizeof(buf)),
 824                             sdl_addr_to_hex(sender_hw, buf2, sizeof(buf2)),
 825                             ifp->if_name, ifp->if_unit);
 826                 }
 827                 else if (route->rt_rmx.rmx_expire == 0) {
 828                         if (log_arp_warnings) {
 829                                 log(LOG_ERR, "arp: %s attempts to modify "
 830                                     "permanent entry for %s on %s%d\n",
 831                                     sdl_addr_to_hex(sender_hw, buf,
 832                                     sizeof(buf)),
 833                                     inet_ntop(AF_INET, &sender_ip->sin_addr,
 834                                     ipv4str, sizeof(ipv4str)),
 835                                     ifp->if_name, ifp->if_unit);
 836                         }
 837                         goto respond;
 838                 }
 839         }
 840
 841         /* Copy the sender hardware address in to the route's gateway address */
 842         gateway->sdl_alen = sender_hw->sdl_alen;
 843         bcopy(CONST_LLADDR(sender_hw), LLADDR(gateway), gateway->sdl_alen);
 844
 845         /* Update the expire time for the route and clear the reject flag */
 846         if (route->rt_rmx.rmx_expire) {
 847                 struct timeval timenow;
 848
 849                 getmicrotime(&timenow);
 850                 route->rt_rmx.rmx_expire = timenow.tv_sec + arpt_keep;
 851         }
 852         route->rt_flags &= ~RTF_REJECT;
 853
 854         /* update the llinfo, send a queued packet if there is one */
 855         llinfo = (struct llinfo_arp*)route->rt_llinfo;
 856         llinfo->la_asked = 0;
 857         if (llinfo->la_hold) {
 858                 struct mbuf *m0;
 859                 m0 = llinfo->la_hold;
 860                 llinfo->la_hold = 0;
 861
 862                 /* Should we a reference on the route first? */
 863                 lck_mtx_unlock(rt_mtx);
 864                 dlil_output(ifp, PF_INET, m0, (caddr_t)route, rt_key(route), 0);
 865                 lck_mtx_lock(rt_mtx);
 866         }
 867
 868 respond:
 869         if (arpop != ARPOP_REQUEST) {
 870                 lck_mtx_unlock(rt_mtx);
 871                 return 0;
 872         }
 873
 874         /* If we are not the target, check if we should proxy */
 875         if (target_ip->sin_addr.s_addr != best_ia->ia_addr.sin_addr.s_addr) {
 876
 877                 /* Find a proxy route */
 878                 error = arp_lookup_route(&target_ip->sin_addr, 0, SIN_PROXY, &route);
 879                 if (error || route == NULL) {
 880
 881                         /* We don't have a route entry indicating we should use proxy */
 882                         /* If we aren't supposed to proxy all, we are done */
 883                         if (!arp_proxyall) {
 884                                 lck_mtx_unlock(rt_mtx);
 885                                 return 0;
 886                         }
 887
 888                         /* See if we have a route to the target ip before we proxy it */
 889                         route = rtalloc1_locked((const struct sockaddr*)target_ip, 0, 0);
 890                         if (!route) {
 891                                 lck_mtx_unlock(rt_mtx);
 892                                 return 0;
 893                         }
 894
 895                         /*
 896                          * Don't proxy for hosts already on the same interface.
 897                          */
 898                         if (route->rt_ifp == ifp) {
 899                                 rtfree_locked(route);
 900                                 lck_mtx_unlock(rt_mtx);
 901                                 return 0;
 902                         }
 903                 }
 904         }
 905         lck_mtx_unlock(rt_mtx);
 906
 907         dlil_send_arp(ifp, ARPOP_REPLY, NULL, (const struct sockaddr*)target_ip,
 908                 sender_hw, (const struct sockaddr*)sender_ip);
 909
 910         return 0;
 911 }
 912
 913 void
 914 arp_ifinit(
 915         struct ifnet *ifp,
 916         struct ifaddr *ifa)
 917 {
 918         ifa->ifa_rtrequest = arp_rtrequest;
 919         ifa->ifa_flags |= RTF_CLONING;
 920         dlil_send_arp(ifp, ARPOP_REQUEST, NULL, ifa->ifa_addr, NULL, ifa->ifa_addr);
 921 }