sbin/routed/input.c

   1 /*
   2  * Copyright (c) 1983, 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  * $FreeBSD$
  30  */
  31
  32 #include "defs.h"
  33
  34 #ifdef __NetBSD__
  35 __RCSID("$NetBSD$");
  36 #elif defined(__FreeBSD__)
  37 __RCSID("$FreeBSD$");
  38 #else
  39 __RCSID("$Revision: 2.26 $");
  40 #ident "$Revision: 2.26 $"
  41 #endif
  42
  43 static void input(struct sockaddr_in *, struct interface *, struct interface *,
  44                   struct rip *, int);
  45 static void input_route(naddr, naddr, struct rt_spare *, struct netinfo *);
  46 static int ck_passwd(struct interface *, struct rip *, void *,
  47                      naddr, struct msg_limit *);
  48
  49
  50 /* process RIP input
  51  */
  52 void
  53 read_rip(int sock,
  54          struct interface *sifp)
  55 {
  56         struct sockaddr_in from;
  57         struct interface *aifp;
  58         socklen_t fromlen;
  59         int cc;
  60 #ifdef USE_PASSIFNAME
  61         static struct msg_limit  bad_name;
  62         struct {
  63                 char    ifname[IFNAMSIZ];
  64                 union pkt_buf pbuf;
  65         } inbuf;
  66 #else
  67         struct {
  68                 union pkt_buf pbuf;
  69         } inbuf;
  70 #endif
  71
  72
  73         for (;;) {
  74                 fromlen = sizeof(from);
  75                 cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0,
  76                               (struct sockaddr*)&from, &fromlen);
  77                 if (cc <= 0) {
  78                         if (cc < 0 && errno != EWOULDBLOCK)
  79                                 LOGERR("recvfrom(rip)");
  80                         break;
  81                 }
  82                 if (fromlen != sizeof(struct sockaddr_in))
  83                         logbad(1,"impossible recvfrom(rip) fromlen=%d",
  84                                (int)fromlen);
  85
  86                 /* aifp is the "authenticated" interface via which the packet
  87                  *      arrived.  In fact, it is only the interface on which
  88                  *      the packet should have arrived based on is source
  89                  *      address.
  90                  * sifp is interface associated with the socket through which
  91                  *      the packet was received.
  92                  */
  93 #ifdef USE_PASSIFNAME
  94                 if ((cc -= sizeof(inbuf.ifname)) < 0)
  95                         logbad(0,"missing USE_PASSIFNAME; only %d bytes",
  96                                cc+sizeof(inbuf.ifname));
  97
  98                 /* check the remote interfaces first */
  99                 LIST_FOREACH(aifp, &remote_if, remote_list) {
 100                         if (aifp->int_addr == from.sin_addr.s_addr)
 101                                 break;
 102                 }
 103                 if (aifp == NULL) {
 104                         aifp = ifwithname(inbuf.ifname, 0);
 105                         if (aifp == NULL) {
 106                                 msglim(&bad_name, from.sin_addr.s_addr,
 107                                        "impossible interface name %.*s",
 108                                        IFNAMSIZ, inbuf.ifname);
 109                         } else if (((aifp->int_if_flags & IFF_POINTOPOINT)
 110                                     && aifp->int_dstaddr!=from.sin_addr.s_addr)
 111                                    || (!(aifp->int_if_flags & IFF_POINTOPOINT)
 112                                        && !on_net(from.sin_addr.s_addr,
 113                                                   aifp->int_net,
 114                                                   aifp->int_mask))) {
 115                                 /* If it came via the wrong interface, do not
 116                                  * trust it.
 117                                  */
 118                                 aifp = NULL;
 119                         }
 120                 }
 121 #else
 122                 aifp = iflookup(from.sin_addr.s_addr);
 123 #endif
 124                 if (sifp == NULL)
 125                         sifp = aifp;
 126
 127                 input(&from, sifp, aifp, &inbuf.pbuf.rip, cc);
 128         }
 129 }
 130
 131
 132 /* Process a RIP packet
 133  */
 134 static void
 135 input(struct sockaddr_in *from,         /* received from this IP address */
 136       struct interface *sifp,           /* interface of incoming socket */
 137       struct interface *aifp,           /* "authenticated" interface */
 138       struct rip *rip,
 139       int cc)
 140 {
 141 #       define FROM_NADDR from->sin_addr.s_addr
 142         static struct msg_limit use_auth, bad_len, bad_mask;
 143         static struct msg_limit unk_router, bad_router, bad_nhop;
 144
 145         struct rt_entry *rt;
 146         struct rt_spare new;
 147         struct netinfo *n, *lim;
 148         struct interface *ifp1;
 149         naddr gate, mask, v1_mask, dst, ddst_h = 0;
 150         struct auth *ap;
 151         struct tgate *tg = NULL;
 152         struct tgate_net *tn;
 153         int i, j;
 154
 155         /* Notice when we hear from a remote gateway
 156          */
 157         if (aifp != NULL
 158             && (aifp->int_state & IS_REMOTE))
 159                 aifp->int_act_time = now.tv_sec;
 160
 161         trace_rip("Recv", "from", from, sifp, rip, cc);
 162
 163         if (sifp == NULL) {
 164                 trace_pkt("    discard a request from an indirect router"
 165                     " (possibly an attack)");
 166                 return;
 167         }
 168
 169         if (rip->rip_vers == 0) {
 170                 msglim(&bad_router, FROM_NADDR,
 171                        "RIP version 0, cmd %d, packet received from %s",
 172                        rip->rip_cmd, naddr_ntoa(FROM_NADDR));
 173                 return;
 174         } else if (rip->rip_vers > RIPv2) {
 175                 rip->rip_vers = RIPv2;
 176         }
 177         if (cc > (int)OVER_MAXPACKETSIZE) {
 178                 msglim(&bad_router, FROM_NADDR,
 179                        "packet at least %d bytes too long received from %s",
 180                        cc-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR));
 181                 return;
 182         }
 183
 184         n = rip->rip_nets;
 185         lim = (struct netinfo *)((char*)rip + cc);
 186
 187         /* Notice authentication.
 188          * As required by section 4.2 in RFC 1723, discard authenticated
 189          * RIPv2 messages, but only if configured for that silliness.
 190          *
 191          * RIPv2 authentication is lame.  Why authenticate queries?
 192          * Why should a RIPv2 implementation with authentication disabled
 193          * not be able to listen to RIPv2 packets with authentication, while
 194          * RIPv1 systems will listen?  Crazy!
 195          */
 196         if (!auth_ok
 197             && rip->rip_vers == RIPv2
 198             && n < lim && n->n_family == RIP_AF_AUTH) {
 199                 msglim(&use_auth, FROM_NADDR,
 200                        "RIPv2 message with authentication from %s discarded",
 201                        naddr_ntoa(FROM_NADDR));
 202                 return;
 203         }
 204
 205         switch (rip->rip_cmd) {
 206         case RIPCMD_REQUEST:
 207                 /* For mere requests, be a little sloppy about the source
 208                  */
 209                 if (aifp == NULL)
 210                         aifp = sifp;
 211
 212                 /* Are we talking to ourself or a remote gateway?
 213                  */
 214                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 215                 if (ifp1) {
 216                         if (ifp1->int_state & IS_REMOTE) {
 217                                 /* remote gateway */
 218                                 aifp = ifp1;
 219                                 if (check_remote(aifp)) {
 220                                         aifp->int_act_time = now.tv_sec;
 221                                         (void)if_ok(aifp, "remote ");
 222                                 }
 223                         } else if (from->sin_port == htons(RIP_PORT)) {
 224                                 trace_pkt("    discard our own RIP request");
 225                                 return;
 226                         }
 227                 }
 228
 229                 /* did the request come from a router?
 230                  */
 231                 if (from->sin_port == htons(RIP_PORT)) {
 232                         /* yes, ignore the request if RIP is off so that
 233                          * the router does not depend on us.
 234                          */
 235                         if (rip_sock < 0
 236                             || (aifp != NULL
 237                                 && IS_RIP_OUT_OFF(aifp->int_state))) {
 238                                 trace_pkt("    discard request while RIP off");
 239                                 return;
 240                         }
 241                 }
 242
 243                 /* According to RFC 1723, we should ignore unauthenticated
 244                  * queries.  That is too silly to bother with.  Sheesh!
 245                  * Are forwarding tables supposed to be secret, when
 246                  * a bad guy can infer them with test traffic?  When RIP
 247                  * is still the most common router-discovery protocol
 248                  * and so hosts need to send queries that will be answered?
 249                  * What about `rtquery`?
 250                  * Maybe on firewalls you'd care, but not enough to
 251                  * give up the diagnostic facilities of remote probing.
 252                  */
 253
 254                 if (n >= lim) {
 255                         msglim(&bad_len, FROM_NADDR, "empty request from %s",
 256                                naddr_ntoa(FROM_NADDR));
 257                         return;
 258                 }
 259                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 260                         msglim(&bad_len, FROM_NADDR,
 261                                "request of bad length (%d) from %s",
 262                                cc, naddr_ntoa(FROM_NADDR));
 263                 }
 264
 265                 if (rip->rip_vers == RIPv2
 266                     && (aifp == NULL || (aifp->int_state & IS_NO_RIPV1_OUT))) {
 267                         v12buf.buf->rip_vers = RIPv2;
 268                         /* If we have a secret but it is a cleartext secret,
 269                          * do not disclose our secret unless the other guy
 270                          * already knows it.
 271                          */
 272                         ap = find_auth(aifp);
 273                         if (ap != NULL && ap->type == RIP_AUTH_PW
 274                             && n->n_family == RIP_AF_AUTH
 275                             && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 276                                 ap = NULL;
 277                 } else {
 278                         v12buf.buf->rip_vers = RIPv1;
 279                         ap = NULL;
 280                 }
 281                 clr_ws_buf(&v12buf, ap);
 282
 283                 do {
 284                         n->n_metric = ntohl(n->n_metric);
 285
 286                         /* A single entry with family RIP_AF_UNSPEC and
 287                          * metric HOPCNT_INFINITY means "all routes".
 288                          * We respond to routers only if we are acting
 289                          * as a supplier, or to anyone other than a router
 290                          * (i.e. a query).
 291                          */
 292                         if (n->n_family == RIP_AF_UNSPEC
 293                             && n->n_metric == HOPCNT_INFINITY) {
 294                                 /* Answer a query from a utility program
 295                                  * with all we know.
 296                                  */
 297                                 if (aifp == NULL) {
 298                                         trace_pkt("ignore remote query");
 299                                         return;
 300                                 }
 301                                 if (from->sin_port != htons(RIP_PORT)) {
 302                                         /*
 303                                          * insecure: query from non-router node
 304                                          *   > 1: allow from distant node
 305                                          *   > 0: allow from neighbor node
 306                                          *  == 0: deny
 307                                          */
 308                                         if ((aifp != NULL && insecure > 0) ||
 309                                             (aifp == NULL && insecure > 1))
 310                                                 supply(from, aifp, OUT_QUERY, 0,
 311                                                        rip->rip_vers,
 312                                                        ap != NULL);
 313                                         else
 314                                                 trace_pkt("Warning: "
 315                                                     "possible attack detected");
 316                                         return;
 317                                 }
 318
 319                                 /* A router trying to prime its tables.
 320                                  * Filter the answer in the about same way
 321                                  * broadcasts are filtered.
 322                                  *
 323                                  * Only answer a router if we are a supplier
 324                                  * to keep an unwary host that is just starting
 325                                  * from picking us as a router.
 326                                  */
 327                                 if (aifp == NULL) {
 328                                         trace_pkt("ignore distant router");
 329                                         return;
 330                                 }
 331                                 if (!supplier
 332                                     || IS_RIP_OFF(aifp->int_state)) {
 333                                         trace_pkt("ignore; not supplying");
 334                                         return;
 335                                 }
 336
 337                                 /* Do not answer a RIPv1 router if
 338                                  * we are sending RIPv2.  But do offer
 339                                  * poor man's router discovery.
 340                                  */
 341                                 if ((aifp->int_state & IS_NO_RIPV1_OUT)
 342                                     && rip->rip_vers == RIPv1) {
 343                                         if (!(aifp->int_state & IS_PM_RDISC)) {
 344                                             trace_pkt("ignore; sending RIPv2");
 345                                             return;
 346                                         }
 347
 348                                         v12buf.n->n_family = RIP_AF_INET;
 349                                         v12buf.n->n_dst = RIP_DEFAULT;
 350                                         i = aifp->int_d_metric;
 351                                         if (NULL != (rt = rtget(RIP_DEFAULT, 0))) {
 352                                             j = (rt->rt_metric
 353                                                  +aifp->int_metric
 354                                                  +aifp->int_adj_outmetric
 355                                                  +1);
 356                                             if (i > j)
 357                                                 i = j;
 358                                         }
 359                                         v12buf.n->n_metric = htonl(i);
 360                                         v12buf.n++;
 361                                         break;
 362                                 }
 363
 364                                 /* Respond with RIPv1 instead of RIPv2 if
 365                                  * that is what we are broadcasting on the
 366                                  * interface to keep the remote router from
 367                                  * getting the wrong initial idea of the
 368                                  * routes we send.
 369                                  */
 370                                 supply(from, aifp, OUT_UNICAST, 0,
 371                                        (aifp->int_state & IS_NO_RIPV1_OUT)
 372                                        ? RIPv2 : RIPv1,
 373                                        ap != NULL);
 374                                 return;
 375                         }
 376
 377                         /* Ignore authentication */
 378                         if (n->n_family == RIP_AF_AUTH)
 379                                 continue;
 380
 381                         if (n->n_family != RIP_AF_INET) {
 382                                 msglim(&bad_router, FROM_NADDR,
 383                                        "request from %s for unsupported"
 384                                        " (af %d) %s",
 385                                        naddr_ntoa(FROM_NADDR),
 386                                        ntohs(n->n_family),
 387                                        naddr_ntoa(n->n_dst));
 388                                 return;
 389                         }
 390
 391                         /* We are being asked about a specific destination.
 392                          */
 393                         dst = n->n_dst;
 394                         if (!check_dst(dst)) {
 395                                 msglim(&bad_router, FROM_NADDR,
 396                                        "bad queried destination %s from %s",
 397                                        naddr_ntoa(dst),
 398                                        naddr_ntoa(FROM_NADDR));
 399                                 return;
 400                         }
 401
 402                         /* decide what mask was intended */
 403                         if (rip->rip_vers == RIPv1
 404                             || 0 == (mask = ntohl(n->n_mask))
 405                             || 0 != (ntohl(dst) & ~mask))
 406                                 mask = ripv1_mask_host(dst, aifp);
 407
 408                         /* try to find the answer */
 409                         rt = rtget(dst, mask);
 410                         if (!rt && dst != RIP_DEFAULT)
 411                                 rt = rtfind(n->n_dst);
 412
 413                         if (v12buf.buf->rip_vers != RIPv1)
 414                                 v12buf.n->n_mask = mask;
 415                         if (rt == NULL) {
 416                                 /* we do not have the answer */
 417                                 v12buf.n->n_metric = HOPCNT_INFINITY;
 418                         } else {
 419                                 /* we have the answer, so compute the
 420                                  * right metric and next hop.
 421                                  */
 422                                 v12buf.n->n_family = RIP_AF_INET;
 423                                 v12buf.n->n_dst = dst;
 424                                 j = rt->rt_metric+1;
 425                                 if (!aifp)
 426                                         ++j;
 427                                 else
 428                                         j += (aifp->int_metric
 429                                               + aifp->int_adj_outmetric);
 430                                 if (j < HOPCNT_INFINITY)
 431                                         v12buf.n->n_metric = j;
 432                                 else
 433                                         v12buf.n->n_metric = HOPCNT_INFINITY;
 434                                 if (v12buf.buf->rip_vers != RIPv1) {
 435                                         v12buf.n->n_tag = rt->rt_tag;
 436                                         v12buf.n->n_mask = mask;
 437                                         if (aifp != NULL
 438                                             && on_net(rt->rt_gate,
 439                                                       aifp->int_net,
 440                                                       aifp->int_mask)
 441                                             && rt->rt_gate != aifp->int_addr)
 442                                             v12buf.n->n_nhop = rt->rt_gate;
 443                                 }
 444                         }
 445                         v12buf.n->n_metric = htonl(v12buf.n->n_metric);
 446
 447                         /* Stop paying attention if we fill the output buffer.
 448                          */
 449                         if (++v12buf.n >= v12buf.lim)
 450                                 break;
 451                 } while (++n < lim);
 452
 453                 /* Send the answer about specific routes.
 454                  */
 455                 if (ap != NULL && ap->type == RIP_AUTH_MD5)
 456                         end_md5_auth(&v12buf, ap);
 457
 458                 if (from->sin_port != htons(RIP_PORT)) {
 459                         /* query */
 460                         (void)output(OUT_QUERY, from, aifp,
 461                                      v12buf.buf,
 462                                      ((char *)v12buf.n - (char*)v12buf.buf));
 463                 } else if (supplier) {
 464                         (void)output(OUT_UNICAST, from, aifp,
 465                                      v12buf.buf,
 466                                      ((char *)v12buf.n - (char*)v12buf.buf));
 467                 } else {
 468                         /* Only answer a router if we are a supplier
 469                          * to keep an unwary host that is just starting
 470                          * from picking us an a router.
 471                          */
 472                         ;
 473                 }
 474                 return;
 475
 476         case RIPCMD_TRACEON:
 477         case RIPCMD_TRACEOFF:
 478                 /* Notice that trace messages are turned off for all possible
 479                  * abuse if _PATH_TRACE is undefined in pathnames.h.
 480                  * Notice also that because of the way the trace file is
 481                  * handled in trace.c, no abuse is plausible even if
 482                  * _PATH_TRACE_ is defined.
 483                  *
 484                  * First verify message came from a privileged port. */
 485                 if (ntohs(from->sin_port) > IPPORT_RESERVED) {
 486                         msglog("trace command from untrusted port on %s",
 487                                naddr_ntoa(FROM_NADDR));
 488                         return;
 489                 }
 490                 if (aifp == NULL) {
 491                         msglog("trace command from unknown router %s",
 492                                naddr_ntoa(FROM_NADDR));
 493                         return;
 494                 }
 495                 if (rip->rip_cmd == RIPCMD_TRACEON) {
 496                         rip->rip_tracefile[cc-4] = '\0';
 497                         set_tracefile((char*)rip->rip_tracefile,
 498                                       "trace command: %s\n", 0);
 499                 } else {
 500                         trace_off("tracing turned off by %s",
 501                                   naddr_ntoa(FROM_NADDR));
 502                 }
 503                 return;
 504
 505         case RIPCMD_RESPONSE:
 506                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 507                         msglim(&bad_len, FROM_NADDR,
 508                                "response of bad length (%d) from %s",
 509                                cc, naddr_ntoa(FROM_NADDR));
 510                 }
 511
 512                 /* verify message came from a router */
 513                 if (from->sin_port != ntohs(RIP_PORT)) {
 514                         msglim(&bad_router, FROM_NADDR,
 515                                "    discard RIP response from unknown port"
 516                                " %d on %s",
 517                                ntohs(from->sin_port), naddr_ntoa(FROM_NADDR));
 518                         return;
 519                 }
 520
 521                 if (rip_sock < 0) {
 522                         trace_pkt("    discard response while RIP off");
 523                         return;
 524                 }
 525
 526                 /* Are we talking to ourself or a remote gateway?
 527                  */
 528                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 529                 if (ifp1) {
 530                         if (ifp1->int_state & IS_REMOTE) {
 531                                 /* remote gateway */
 532                                 aifp = ifp1;
 533                                 if (check_remote(aifp)) {
 534                                         aifp->int_act_time = now.tv_sec;
 535                                         (void)if_ok(aifp, "remote ");
 536                                 }
 537                         } else {
 538                                 trace_pkt("    discard our own RIP response");
 539                                 return;
 540                         }
 541                 }
 542
 543                 /* Accept routing packets from routers directly connected
 544                  * via broadcast or point-to-point networks, and from
 545                  * those listed in /etc/gateways.
 546                  */
 547                 if (aifp == NULL) {
 548                         msglim(&unk_router, FROM_NADDR,
 549                                "   discard response from %s"
 550                                " via unexpected interface",
 551                                naddr_ntoa(FROM_NADDR));
 552                         return;
 553                 }
 554                 if (IS_RIP_IN_OFF(aifp->int_state)) {
 555                         trace_pkt("    discard RIPv%d response"
 556                                   " via disabled interface %s",
 557                                   rip->rip_vers, aifp->int_name);
 558                         return;
 559                 }
 560
 561                 if (n >= lim) {
 562                         msglim(&bad_len, FROM_NADDR, "empty response from %s",
 563                                naddr_ntoa(FROM_NADDR));
 564                         return;
 565                 }
 566
 567                 if (((aifp->int_state & IS_NO_RIPV1_IN)
 568                      && rip->rip_vers == RIPv1)
 569                     || ((aifp->int_state & IS_NO_RIPV2_IN)
 570                         && rip->rip_vers != RIPv1)) {
 571                         trace_pkt("    discard RIPv%d response",
 572                                   rip->rip_vers);
 573                         return;
 574                 }
 575
 576                 /* Ignore routes via dead interface.
 577                  */
 578                 if (aifp->int_state & IS_BROKE) {
 579                         trace_pkt("discard response via broken interface %s",
 580                                   aifp->int_name);
 581                         return;
 582                 }
 583
 584                 /* If the interface cares, ignore bad routers.
 585                  * Trace but do not log this problem, because where it
 586                  * happens, it happens frequently.
 587                  */
 588                 if (aifp->int_state & IS_DISTRUST) {
 589                         tg = tgates;
 590                         while (tg->tgate_addr != FROM_NADDR) {
 591                                 tg = tg->tgate_next;
 592                                 if (tg == NULL) {
 593                                         trace_pkt("    discard RIP response"
 594                                                   " from untrusted router %s",
 595                                                   naddr_ntoa(FROM_NADDR));
 596                                         return;
 597                                 }
 598                         }
 599                 }
 600
 601                 /* Authenticate the packet if we have a secret.
 602                  * If we do not have any secrets, ignore the error in
 603                  * RFC 1723 and accept it regardless.
 604                  */
 605                 if (aifp->int_auth[0].type != RIP_AUTH_NONE
 606                     && rip->rip_vers != RIPv1
 607                     && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 608                         return;
 609
 610                 do {
 611                         if (n->n_family == RIP_AF_AUTH)
 612                                 continue;
 613
 614                         n->n_metric = ntohl(n->n_metric);
 615                         dst = n->n_dst;
 616                         if (n->n_family != RIP_AF_INET
 617                             && (n->n_family != RIP_AF_UNSPEC
 618                                 || dst != RIP_DEFAULT)) {
 619                                 msglim(&bad_router, FROM_NADDR,
 620                                        "route from %s to unsupported"
 621                                        " address family=%d destination=%s",
 622                                        naddr_ntoa(FROM_NADDR),
 623                                        n->n_family,
 624                                        naddr_ntoa(dst));
 625                                 continue;
 626                         }
 627                         if (!check_dst(dst)) {
 628                                 msglim(&bad_router, FROM_NADDR,
 629                                        "bad destination %s from %s",
 630                                        naddr_ntoa(dst),
 631                                        naddr_ntoa(FROM_NADDR));
 632                                 return;
 633                         }
 634                         if (n->n_metric == 0
 635                             || n->n_metric > HOPCNT_INFINITY) {
 636                                 msglim(&bad_router, FROM_NADDR,
 637                                        "bad metric %d from %s"
 638                                        " for destination %s",
 639                                        n->n_metric,
 640                                        naddr_ntoa(FROM_NADDR),
 641                                        naddr_ntoa(dst));
 642                                 return;
 643                         }
 644
 645                         /* Notice the next-hop.
 646                          */
 647                         gate = FROM_NADDR;
 648                         if (n->n_nhop != 0) {
 649                                 if (rip->rip_vers == RIPv1) {
 650                                         n->n_nhop = 0;
 651                                 } else {
 652                                     /* Use it only if it is valid. */
 653                                     if (on_net(n->n_nhop,
 654                                                aifp->int_net, aifp->int_mask)
 655                                         && check_dst(n->n_nhop)) {
 656                                             gate = n->n_nhop;
 657                                     } else {
 658                                             msglim(&bad_nhop, FROM_NADDR,
 659                                                    "router %s to %s"
 660                                                    " has bad next hop %s",
 661                                                    naddr_ntoa(FROM_NADDR),
 662                                                    naddr_ntoa(dst),
 663                                                    naddr_ntoa(n->n_nhop));
 664                                             n->n_nhop = 0;
 665                                     }
 666                                 }
 667                         }
 668
 669                         if (rip->rip_vers == RIPv1
 670                             || 0 == (mask = ntohl(n->n_mask))) {
 671                                 mask = ripv1_mask_host(dst,aifp);
 672                         } else if ((ntohl(dst) & ~mask) != 0) {
 673                                 msglim(&bad_mask, FROM_NADDR,
 674                                        "router %s sent bad netmask"
 675                                        " %#lx with %s",
 676                                        naddr_ntoa(FROM_NADDR),
 677                                        (u_long)mask,
 678                                        naddr_ntoa(dst));
 679                                 continue;
 680                         }
 681                         if (rip->rip_vers == RIPv1)
 682                                 n->n_tag = 0;
 683
 684                         /* Adjust metric according to incoming interface..
 685                          */
 686                         n->n_metric += (aifp->int_metric
 687                                         + aifp->int_adj_inmetric);
 688                         if (n->n_metric > HOPCNT_INFINITY)
 689                                 n->n_metric = HOPCNT_INFINITY;
 690
 691                         /* Should we trust this route from this router? */
 692                         if (tg && (tn = tg->tgate_nets)->mask != 0) {
 693                                 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) {
 694                                         if (on_net(dst, tn->net, tn->mask)
 695                                             && tn->mask <= mask)
 696                                             break;
 697                                 }
 698                                 if (i >= MAX_TGATE_NETS || tn->mask == 0) {
 699                                         trace_pkt("   ignored unauthorized %s",
 700                                                   addrname(dst,mask,0));
 701                                         continue;
 702                                 }
 703                         }
 704
 705                         /* Recognize and ignore a default route we faked
 706                          * which is being sent back to us by a machine with
 707                          * broken split-horizon.
 708                          * Be a little more paranoid than that, and reject
 709                          * default routes with the same metric we advertised.
 710                          */
 711                         if (aifp->int_d_metric != 0
 712                             && dst == RIP_DEFAULT
 713                             && (int)n->n_metric >= aifp->int_d_metric)
 714                                 continue;
 715
 716                         /* We can receive aggregated RIPv2 routes that must
 717                          * be broken down before they are transmitted by
 718                          * RIPv1 via an interface on a subnet.
 719                          * We might also receive the same routes aggregated
 720                          * via other RIPv2 interfaces.
 721                          * This could cause duplicate routes to be sent on
 722                          * the RIPv1 interfaces.  "Longest matching variable
 723                          * length netmasks" lets RIPv2 listeners understand,
 724                          * but breaking down the aggregated routes for RIPv1
 725                          * listeners can produce duplicate routes.
 726                          *
 727                          * Breaking down aggregated routes here bloats
 728                          * the daemon table, but does not hurt the kernel
 729                          * table, since routes are always aggregated for
 730                          * the kernel.
 731                          *
 732                          * Notice that this does not break down network
 733                          * routes corresponding to subnets.  This is part
 734                          * of the defense against RS_NET_SYN.
 735                          */
 736                         if (have_ripv1_out
 737                             && (((rt = rtget(dst,mask)) == NULL
 738                                  || !(rt->rt_state & RS_NET_SYN)))
 739                             && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 740                                 ddst_h = v1_mask & -v1_mask;
 741                                 i = (v1_mask & ~mask)/ddst_h;
 742                                 if (i >= 511) {
 743                                         /* Punt if we would have to generate
 744                                          * an unreasonable number of routes.
 745                                          */
 746                                         if (TRACECONTENTS)
 747                                             trace_misc("accept %s-->%s as 1"
 748                                                        " instead of %d routes",
 749                                                        addrname(dst,mask,0),
 750                                                        naddr_ntoa(FROM_NADDR),
 751                                                        i+1);
 752                                         i = 0;
 753                                 } else {
 754                                         mask = v1_mask;
 755                                 }
 756                         } else {
 757                                 i = 0;
 758                         }
 759
 760                         new.rts_gate = gate;
 761                         new.rts_router = FROM_NADDR;
 762                         new.rts_metric = n->n_metric;
 763                         new.rts_tag = n->n_tag;
 764                         new.rts_time = now.tv_sec;
 765                         new.rts_ifp = aifp;
 766                         new.rts_de_ag = i;
 767                         j = 0;
 768                         for (;;) {
 769                                 input_route(dst, mask, &new, n);
 770                                 if (++j > i)
 771                                         break;
 772                                 dst = htonl(ntohl(dst) + ddst_h);
 773                         }
 774                 } while (++n < lim);
 775                 break;
 776         }
 777 #undef FROM_NADDR
 778 }
 779
 780
 781 /* Process a single input route.
 782  */
 783 static void
 784 input_route(naddr dst,                  /* network order */
 785             naddr mask,
 786             struct rt_spare *new,
 787             struct netinfo *n)
 788 {
 789         int i;
 790         struct rt_entry *rt;
 791         struct rt_spare *rts, *rts0;
 792         struct interface *ifp1;
 793
 794
 795         /* See if the other guy is telling us to send our packets to him.
 796          * Sometimes network routes arrive over a point-to-point link for
 797          * the network containing the address(es) of the link.
 798          *
 799          * If our interface is broken, switch to using the other guy.
 800          */
 801         ifp1 = ifwithaddr(dst, 1, 1);
 802         if (ifp1 != NULL
 803             && (!(ifp1->int_state & IS_BROKE)
 804                 || (ifp1->int_state & IS_PASSIVE)))
 805                 return;
 806
 807         /* Look for the route in our table.
 808          */
 809         rt = rtget(dst, mask);
 810
 811         /* Consider adding the route if we do not already have it.
 812          */
 813         if (rt == NULL) {
 814                 /* Ignore unknown routes being poisoned.
 815                  */
 816                 if (new->rts_metric == HOPCNT_INFINITY)
 817                         return;
 818
 819                 /* Ignore the route if it points to us */
 820                 if (n->n_nhop != 0
 821                     && ifwithaddr(n->n_nhop, 1, 0) != NULL)
 822                         return;
 823
 824                 /* If something has not gone crazy and tried to fill
 825                  * our memory, accept the new route.
 826                  */
 827                 if (total_routes < MAX_ROUTES)
 828                         rtadd(dst, mask, 0, new);
 829                 return;
 830         }
 831
 832         /* We already know about the route.  Consider this update.
 833          *
 834          * If (rt->rt_state & RS_NET_SYN), then this route
 835          * is the same as a network route we have inferred
 836          * for subnets we know, in order to tell RIPv1 routers
 837          * about the subnets.
 838          *
 839          * It is impossible to tell if the route is coming
 840          * from a distant RIPv2 router with the standard
 841          * netmask because that router knows about the entire
 842          * network, or if it is a round-about echo of a
 843          * synthetic, RIPv1 network route of our own.
 844          * The worst is that both kinds of routes might be
 845          * received, and the bad one might have the smaller
 846          * metric.  Partly solve this problem by never
 847          * aggregating into such a route.  Also keep it
 848          * around as long as the interface exists.
 849          */
 850
 851         rts0 = rt->rt_spares;
 852         for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
 853                 if (rts->rts_router == new->rts_router)
 854                         break;
 855                 /* Note the worst slot to reuse,
 856                  * other than the current slot.
 857                  */
 858                 if (rts0 == rt->rt_spares
 859                     || BETTER_LINK(rt, rts0, rts))
 860                         rts0 = rts;
 861         }
 862         if (i != 0) {
 863                 /* Found a route from the router already in the table.
 864                  */
 865
 866                 /* If the new route is a route broken down from an
 867                  * aggregated route, and if the previous route is either
 868                  * not a broken down route or was broken down from a finer
 869                  * netmask, and if the previous route is current,
 870                  * then forget this one.
 871                  */
 872                 if (new->rts_de_ag > rts->rts_de_ag
 873                     && now_stale <= rts->rts_time)
 874                         return;
 875
 876                 /* Keep poisoned routes around only long enough to pass
 877                  * the poison on.  Use a new timestamp for good routes.
 878                  */
 879                 if (rts->rts_metric == HOPCNT_INFINITY
 880                     && new->rts_metric == HOPCNT_INFINITY)
 881                         new->rts_time = rts->rts_time;
 882
 883                 /* If this is an update for the router we currently prefer,
 884                  * then note it.
 885                  */
 886                 if (i == NUM_SPARES) {
 887                         rtchange(rt, rt->rt_state, new, 0);
 888                         /* If the route got worse, check for something better.
 889                          */
 890                         if (new->rts_metric > rts->rts_metric)
 891                                 rtswitch(rt, 0);
 892                         return;
 893                 }
 894
 895                 /* This is an update for a spare route.
 896                  * Finished if the route is unchanged.
 897                  */
 898                 if (rts->rts_gate == new->rts_gate
 899                     && rts->rts_metric == new->rts_metric
 900                     && rts->rts_tag == new->rts_tag) {
 901                         trace_upslot(rt, rts, new);
 902                         *rts = *new;
 903                         return;
 904                 }
 905                 /* Forget it if it has gone bad.
 906                  */
 907                 if (new->rts_metric == HOPCNT_INFINITY) {
 908                         rts_delete(rt, rts);
 909                         return;
 910                 }
 911
 912         } else {
 913                 /* The update is for a route we know about,
 914                  * but not from a familiar router.
 915                  *
 916                  * Ignore the route if it points to us.
 917                  */
 918                 if (n->n_nhop != 0
 919                     && NULL != ifwithaddr(n->n_nhop, 1, 0))
 920                         return;
 921
 922                 /* the loop above set rts0=worst spare */
 923                 rts = rts0;
 924
 925                 /* Save the route as a spare only if it has
 926                  * a better metric than our worst spare.
 927                  * This also ignores poisoned routes (those
 928                  * received with metric HOPCNT_INFINITY).
 929                  */
 930                 if (new->rts_metric >= rts->rts_metric)
 931                         return;
 932         }
 933
 934         trace_upslot(rt, rts, new);
 935         *rts = *new;
 936
 937         /* try to switch to a better route */
 938         rtswitch(rt, rts);
 939 }
 940
 941
 942 static int                              /* 0 if bad */
 943 ck_passwd(struct interface *aifp,
 944           struct rip *rip,
 945           void *lim,
 946           naddr from,
 947           struct msg_limit *use_authp)
 948 {
 949 #       define NA (rip->rip_auths)
 950         struct netauth *na2;
 951         struct auth *ap;
 952         MD5_CTX md5_ctx;
 953         u_char hash[RIP_AUTH_PW_LEN];
 954         int i, len;
 955
 956         assert(aifp != NULL);
 957         if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) {
 958                 msglim(use_authp, from, "missing password from %s",
 959                        naddr_ntoa(from));
 960                 return 0;
 961         }
 962
 963         /* accept any current (+/- 24 hours) password
 964          */
 965         for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 966                 if (ap->type != NA->a_type
 967                     || (u_long)ap->start > (u_long)clk.tv_sec+DAY
 968                     || (u_long)ap->end+DAY < (u_long)clk.tv_sec)
 969                         continue;
 970
 971                 if (NA->a_type == RIP_AUTH_PW) {
 972                         if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN))
 973                                 return 1;
 974
 975                 } else {
 976                         /* accept MD5 secret with the right key ID
 977                          */
 978                         if (NA->au.a_md5.md5_keyid != ap->keyid)
 979                                 continue;
 980
 981                         len = ntohs(NA->au.a_md5.md5_pkt_len);
 982                         if ((len-sizeof(*rip)) % sizeof(*NA) != 0
 983                             || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) {
 984                                 msglim(use_authp, from,
 985                                        "wrong MD5 RIPv2 packet length of %d"
 986                                        " instead of %d from %s",
 987                                        len, (int)((char *)lim-(char *)rip
 988                                                   -sizeof(*NA)),
 989                                        naddr_ntoa(from));
 990                                 return 0;
 991                         }
 992                         na2 = (struct netauth *)((char *)rip+len);
 993
 994                         /* Given a good hash value, these are not security
 995                          * problems so be generous and accept the routes,
 996                          * after complaining.
 997                          */
 998                         if (TRACEPACKETS) {
 999                                 if (NA->au.a_md5.md5_auth_len
1000                                     != RIP_AUTH_MD5_HASH_LEN)
1001                                         msglim(use_authp, from,
1002                                                "unknown MD5 RIPv2 auth len %#x"
1003                                                " instead of %#x from %s",
1004                                                NA->au.a_md5.md5_auth_len,
1005                                                (unsigned)RIP_AUTH_MD5_HASH_LEN,
1006                                                naddr_ntoa(from));
1007                                 if (na2->a_family != RIP_AF_AUTH)
1008                                         msglim(use_authp, from,
1009                                                "unknown MD5 RIPv2 family %#x"
1010                                                " instead of %#x from %s",
1011                                                na2->a_family, RIP_AF_AUTH,
1012                                                naddr_ntoa(from));
1013                                 if (na2->a_type != ntohs(1))
1014                                         msglim(use_authp, from,
1015                                                "MD5 RIPv2 hash has %#x"
1016                                                " instead of %#x from %s",
1017                                                na2->a_type, ntohs(1),
1018                                                naddr_ntoa(from));
1019                         }
1020
1021                         MD5Init(&md5_ctx);
1022                         MD5Update(&md5_ctx, (u_char *)rip,
1023                                   len + RIP_AUTH_MD5_HASH_XTRA);
1024                         MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_KEY_LEN);
1025                         MD5Final(hash, &md5_ctx);
1026                         if (!memcmp(hash, na2->au.au_pw, sizeof(hash)))
1027                                 return 1;
1028                 }
1029         }
1030
1031         msglim(use_authp, from, "bad password from %s",
1032                naddr_ntoa(from));
1033         return 0;
1034 #undef NA
1035 }