sbin/routed/input.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1983, 1988, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  * $FreeBSD$
  32  */
  33
  34 #include "defs.h"
  35
  36 __RCSID("$FreeBSD$");
  37
  38 static void input(struct sockaddr_in *, struct interface *, struct interface *,
  39                   struct rip *, int);
  40 static void input_route(naddr, naddr, struct rt_spare *, struct netinfo *);
  41 static int ck_passwd(struct interface *, struct rip *, void *,
  42                      naddr, struct msg_limit *);
  43
  44
  45 /* process RIP input
  46  */
  47 void
  48 read_rip(int sock,
  49          struct interface *sifp)
  50 {
  51         struct sockaddr_in from;
  52         struct interface *aifp;
  53         socklen_t fromlen;
  54         int cc;
  55 #ifdef USE_PASSIFNAME
  56         static struct msg_limit  bad_name;
  57         struct {
  58                 char    ifname[IFNAMSIZ];
  59                 union pkt_buf pbuf;
  60         } inbuf;
  61 #else
  62         struct {
  63                 union pkt_buf pbuf;
  64         } inbuf;
  65 #endif
  66
  67
  68         for (;;) {
  69                 fromlen = sizeof(from);
  70                 cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0,
  71                               (struct sockaddr*)&from, &fromlen);
  72                 if (cc <= 0) {
  73                         if (cc < 0 && errno != EWOULDBLOCK)
  74                                 LOGERR("recvfrom(rip)");
  75                         break;
  76                 }
  77                 if (fromlen != sizeof(struct sockaddr_in))
  78                         logbad(1,"impossible recvfrom(rip) fromlen=%d",
  79                                (int)fromlen);
  80
  81                 /* aifp is the "authenticated" interface via which the packet
  82                  *      arrived.  In fact, it is only the interface on which
  83                  *      the packet should have arrived based on is source
  84                  *      address.
  85                  * sifp is interface associated with the socket through which
  86                  *      the packet was received.
  87                  */
  88 #ifdef USE_PASSIFNAME
  89                 if ((cc -= sizeof(inbuf.ifname)) < 0)
  90                         logbad(0,"missing USE_PASSIFNAME; only %d bytes",
  91                                cc+sizeof(inbuf.ifname));
  92
  93                 /* check the remote interfaces first */
  94                 LIST_FOREACH(aifp, &remote_if, remote_list) {
  95                         if (aifp->int_addr == from.sin_addr.s_addr)
  96                                 break;
  97                 }
  98                 if (aifp == NULL) {
  99                         aifp = ifwithname(inbuf.ifname, 0);
 100                         if (aifp == NULL) {
 101                                 msglim(&bad_name, from.sin_addr.s_addr,
 102                                        "impossible interface name %.*s",
 103                                        IFNAMSIZ, inbuf.ifname);
 104                         } else if (((aifp->int_if_flags & IFF_POINTOPOINT)
 105                                     && aifp->int_dstaddr!=from.sin_addr.s_addr)
 106                                    || (!(aifp->int_if_flags & IFF_POINTOPOINT)
 107                                        && !on_net(from.sin_addr.s_addr,
 108                                                   aifp->int_net,
 109                                                   aifp->int_mask))) {
 110                                 /* If it came via the wrong interface, do not
 111                                  * trust it.
 112                                  */
 113                                 aifp = NULL;
 114                         }
 115                 }
 116 #else
 117                 aifp = iflookup(from.sin_addr.s_addr);
 118 #endif
 119                 if (sifp == NULL)
 120                         sifp = aifp;
 121
 122                 input(&from, sifp, aifp, &inbuf.pbuf.rip, cc);
 123         }
 124 }
 125
 126
 127 /* Process a RIP packet
 128  */
 129 static void
 130 input(struct sockaddr_in *from,         /* received from this IP address */
 131       struct interface *sifp,           /* interface of incoming socket */
 132       struct interface *aifp,           /* "authenticated" interface */
 133       struct rip *rip,
 134       int cc)
 135 {
 136 #       define FROM_NADDR from->sin_addr.s_addr
 137         static struct msg_limit use_auth, bad_len, bad_mask;
 138         static struct msg_limit unk_router, bad_router, bad_nhop;
 139
 140         struct rt_entry *rt;
 141         struct rt_spare new;
 142         struct netinfo *n, *lim;
 143         struct interface *ifp1;
 144         naddr gate, mask, v1_mask, dst, ddst_h = 0;
 145         struct auth *ap;
 146         struct tgate *tg = NULL;
 147         struct tgate_net *tn;
 148         int i, j;
 149
 150         /* Notice when we hear from a remote gateway
 151          */
 152         if (aifp != NULL
 153             && (aifp->int_state & IS_REMOTE))
 154                 aifp->int_act_time = now.tv_sec;
 155
 156         trace_rip("Recv", "from", from, sifp, rip, cc);
 157
 158         if (sifp == NULL) {
 159                 trace_pkt("    discard a request from an indirect router"
 160                     " (possibly an attack)");
 161                 return;
 162         }
 163
 164         if (rip->rip_vers == 0) {
 165                 msglim(&bad_router, FROM_NADDR,
 166                        "RIP version 0, cmd %d, packet received from %s",
 167                        rip->rip_cmd, naddr_ntoa(FROM_NADDR));
 168                 return;
 169         } else if (rip->rip_vers > RIPv2) {
 170                 rip->rip_vers = RIPv2;
 171         }
 172         if (cc > (int)OVER_MAXPACKETSIZE) {
 173                 msglim(&bad_router, FROM_NADDR,
 174                        "packet at least %d bytes too long received from %s",
 175                        cc-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR));
 176                 return;
 177         }
 178
 179         n = rip->rip_nets;
 180         lim = (struct netinfo *)((char*)rip + cc);
 181
 182         /* Notice authentication.
 183          * As required by section 4.2 in RFC 1723, discard authenticated
 184          * RIPv2 messages, but only if configured for that silliness.
 185          *
 186          * RIPv2 authentication is lame.  Why authenticate queries?
 187          * Why should a RIPv2 implementation with authentication disabled
 188          * not be able to listen to RIPv2 packets with authentication, while
 189          * RIPv1 systems will listen?  Crazy!
 190          */
 191         if (!auth_ok
 192             && rip->rip_vers == RIPv2
 193             && n < lim && n->n_family == RIP_AF_AUTH) {
 194                 msglim(&use_auth, FROM_NADDR,
 195                        "RIPv2 message with authentication from %s discarded",
 196                        naddr_ntoa(FROM_NADDR));
 197                 return;
 198         }
 199
 200         switch (rip->rip_cmd) {
 201         case RIPCMD_REQUEST:
 202                 /* For mere requests, be a little sloppy about the source
 203                  */
 204                 if (aifp == NULL)
 205                         aifp = sifp;
 206
 207                 /* Are we talking to ourself or a remote gateway?
 208                  */
 209                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 210                 if (ifp1) {
 211                         if (ifp1->int_state & IS_REMOTE) {
 212                                 /* remote gateway */
 213                                 aifp = ifp1;
 214                                 if (check_remote(aifp)) {
 215                                         aifp->int_act_time = now.tv_sec;
 216                                         (void)if_ok(aifp, "remote ");
 217                                 }
 218                         } else if (from->sin_port == htons(RIP_PORT)) {
 219                                 trace_pkt("    discard our own RIP request");
 220                                 return;
 221                         }
 222                 }
 223
 224                 /* did the request come from a router?
 225                  */
 226                 if (from->sin_port == htons(RIP_PORT)) {
 227                         /* yes, ignore the request if RIP is off so that
 228                          * the router does not depend on us.
 229                          */
 230                         if (rip_sock < 0
 231                             || (aifp != NULL
 232                                 && IS_RIP_OUT_OFF(aifp->int_state))) {
 233                                 trace_pkt("    discard request while RIP off");
 234                                 return;
 235                         }
 236                 }
 237
 238                 /* According to RFC 1723, we should ignore unauthenticated
 239                  * queries.  That is too silly to bother with.  Sheesh!
 240                  * Are forwarding tables supposed to be secret, when
 241                  * a bad guy can infer them with test traffic?  When RIP
 242                  * is still the most common router-discovery protocol
 243                  * and so hosts need to send queries that will be answered?
 244                  * What about `rtquery`?
 245                  * Maybe on firewalls you'd care, but not enough to
 246                  * give up the diagnostic facilities of remote probing.
 247                  */
 248
 249                 if (n >= lim) {
 250                         msglim(&bad_len, FROM_NADDR, "empty request from %s",
 251                                naddr_ntoa(FROM_NADDR));
 252                         return;
 253                 }
 254                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 255                         msglim(&bad_len, FROM_NADDR,
 256                                "request of bad length (%d) from %s",
 257                                cc, naddr_ntoa(FROM_NADDR));
 258                 }
 259
 260                 if (rip->rip_vers == RIPv2
 261                     && (aifp == NULL || (aifp->int_state & IS_NO_RIPV1_OUT))) {
 262                         v12buf.buf->rip_vers = RIPv2;
 263                         /* If we have a secret but it is a cleartext secret,
 264                          * do not disclose our secret unless the other guy
 265                          * already knows it.
 266                          */
 267                         ap = find_auth(aifp);
 268                         if (ap != NULL && ap->type == RIP_AUTH_PW
 269                             && n->n_family == RIP_AF_AUTH
 270                             && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 271                                 ap = NULL;
 272                 } else {
 273                         v12buf.buf->rip_vers = RIPv1;
 274                         ap = NULL;
 275                 }
 276                 clr_ws_buf(&v12buf, ap);
 277
 278                 do {
 279                         n->n_metric = ntohl(n->n_metric);
 280
 281                         /* A single entry with family RIP_AF_UNSPEC and
 282                          * metric HOPCNT_INFINITY means "all routes".
 283                          * We respond to routers only if we are acting
 284                          * as a supplier, or to anyone other than a router
 285                          * (i.e. a query).
 286                          */
 287                         if (n->n_family == RIP_AF_UNSPEC
 288                             && n->n_metric == HOPCNT_INFINITY) {
 289                                 /* Answer a query from a utility program
 290                                  * with all we know.
 291                                  */
 292                                 if (aifp == NULL) {
 293                                         trace_pkt("ignore remote query");
 294                                         return;
 295                                 }
 296                                 if (from->sin_port != htons(RIP_PORT)) {
 297                                         /*
 298                                          * insecure: query from non-router node
 299                                          *   > 1: allow from distant node
 300                                          *   > 0: allow from neighbor node
 301                                          *  == 0: deny
 302                                          */
 303                                         if ((aifp != NULL && insecure > 0) ||
 304                                             (aifp == NULL && insecure > 1))
 305                                                 supply(from, aifp, OUT_QUERY, 0,
 306                                                        rip->rip_vers,
 307                                                        ap != NULL);
 308                                         else
 309                                                 trace_pkt("Warning: "
 310                                                     "possible attack detected");
 311                                         return;
 312                                 }
 313
 314                                 /* A router trying to prime its tables.
 315                                  * Filter the answer in the about same way
 316                                  * broadcasts are filtered.
 317                                  *
 318                                  * Only answer a router if we are a supplier
 319                                  * to keep an unwary host that is just starting
 320                                  * from picking us as a router.
 321                                  */
 322                                 if (aifp == NULL) {
 323                                         trace_pkt("ignore distant router");
 324                                         return;
 325                                 }
 326                                 if (!supplier
 327                                     || IS_RIP_OFF(aifp->int_state)) {
 328                                         trace_pkt("ignore; not supplying");
 329                                         return;
 330                                 }
 331
 332                                 /* Do not answer a RIPv1 router if
 333                                  * we are sending RIPv2.  But do offer
 334                                  * poor man's router discovery.
 335                                  */
 336                                 if ((aifp->int_state & IS_NO_RIPV1_OUT)
 337                                     && rip->rip_vers == RIPv1) {
 338                                         if (!(aifp->int_state & IS_PM_RDISC)) {
 339                                             trace_pkt("ignore; sending RIPv2");
 340                                             return;
 341                                         }
 342
 343                                         v12buf.n->n_family = RIP_AF_INET;
 344                                         v12buf.n->n_dst = RIP_DEFAULT;
 345                                         i = aifp->int_d_metric;
 346                                         if (NULL != (rt = rtget(RIP_DEFAULT, 0))) {
 347                                             j = (rt->rt_metric
 348                                                  +aifp->int_metric
 349                                                  +aifp->int_adj_outmetric
 350                                                  +1);
 351                                             if (i > j)
 352                                                 i = j;
 353                                         }
 354                                         v12buf.n->n_metric = htonl(i);
 355                                         v12buf.n++;
 356                                         break;
 357                                 }
 358
 359                                 /* Respond with RIPv1 instead of RIPv2 if
 360                                  * that is what we are broadcasting on the
 361                                  * interface to keep the remote router from
 362                                  * getting the wrong initial idea of the
 363                                  * routes we send.
 364                                  */
 365                                 supply(from, aifp, OUT_UNICAST, 0,
 366                                        (aifp->int_state & IS_NO_RIPV1_OUT)
 367                                        ? RIPv2 : RIPv1,
 368                                        ap != NULL);
 369                                 return;
 370                         }
 371
 372                         /* Ignore authentication */
 373                         if (n->n_family == RIP_AF_AUTH)
 374                                 continue;
 375
 376                         if (n->n_family != RIP_AF_INET) {
 377                                 msglim(&bad_router, FROM_NADDR,
 378                                        "request from %s for unsupported"
 379                                        " (af %d) %s",
 380                                        naddr_ntoa(FROM_NADDR),
 381                                        ntohs(n->n_family),
 382                                        naddr_ntoa(n->n_dst));
 383                                 return;
 384                         }
 385
 386                         /* We are being asked about a specific destination.
 387                          */
 388                         dst = n->n_dst;
 389                         if (!check_dst(dst)) {
 390                                 msglim(&bad_router, FROM_NADDR,
 391                                        "bad queried destination %s from %s",
 392                                        naddr_ntoa(dst),
 393                                        naddr_ntoa(FROM_NADDR));
 394                                 return;
 395                         }
 396
 397                         /* decide what mask was intended */
 398                         if (rip->rip_vers == RIPv1
 399                             || 0 == (mask = ntohl(n->n_mask))
 400                             || 0 != (ntohl(dst) & ~mask))
 401                                 mask = ripv1_mask_host(dst, aifp);
 402
 403                         /* try to find the answer */
 404                         rt = rtget(dst, mask);
 405                         if (!rt && dst != RIP_DEFAULT)
 406                                 rt = rtfind(n->n_dst);
 407
 408                         if (v12buf.buf->rip_vers != RIPv1)
 409                                 v12buf.n->n_mask = mask;
 410                         if (rt == NULL) {
 411                                 /* we do not have the answer */
 412                                 v12buf.n->n_metric = HOPCNT_INFINITY;
 413                         } else {
 414                                 /* we have the answer, so compute the
 415                                  * right metric and next hop.
 416                                  */
 417                                 v12buf.n->n_family = RIP_AF_INET;
 418                                 v12buf.n->n_dst = dst;
 419                                 j = rt->rt_metric+1;
 420                                 if (!aifp)
 421                                         ++j;
 422                                 else
 423                                         j += (aifp->int_metric
 424                                               + aifp->int_adj_outmetric);
 425                                 if (j < HOPCNT_INFINITY)
 426                                         v12buf.n->n_metric = j;
 427                                 else
 428                                         v12buf.n->n_metric = HOPCNT_INFINITY;
 429                                 if (v12buf.buf->rip_vers != RIPv1) {
 430                                         v12buf.n->n_tag = rt->rt_tag;
 431                                         v12buf.n->n_mask = mask;
 432                                         if (aifp != NULL
 433                                             && on_net(rt->rt_gate,
 434                                                       aifp->int_net,
 435                                                       aifp->int_mask)
 436                                             && rt->rt_gate != aifp->int_addr)
 437                                             v12buf.n->n_nhop = rt->rt_gate;
 438                                 }
 439                         }
 440                         v12buf.n->n_metric = htonl(v12buf.n->n_metric);
 441
 442                         /* Stop paying attention if we fill the output buffer.
 443                          */
 444                         if (++v12buf.n >= v12buf.lim)
 445                                 break;
 446                 } while (++n < lim);
 447
 448                 /* Send the answer about specific routes.
 449                  */
 450                 if (ap != NULL && ap->type == RIP_AUTH_MD5)
 451                         end_md5_auth(&v12buf, ap);
 452
 453                 if (from->sin_port != htons(RIP_PORT)) {
 454                         /* query */
 455                         (void)output(OUT_QUERY, from, aifp,
 456                                      v12buf.buf,
 457                                      ((char *)v12buf.n - (char*)v12buf.buf));
 458                 } else if (supplier) {
 459                         (void)output(OUT_UNICAST, from, aifp,
 460                                      v12buf.buf,
 461                                      ((char *)v12buf.n - (char*)v12buf.buf));
 462                 } else {
 463                         /* Only answer a router if we are a supplier
 464                          * to keep an unwary host that is just starting
 465                          * from picking us an a router.
 466                          */
 467                         ;
 468                 }
 469                 return;
 470
 471         case RIPCMD_TRACEON:
 472         case RIPCMD_TRACEOFF:
 473                 /* Notice that trace messages are turned off for all possible
 474                  * abuse if _PATH_TRACE is undefined in pathnames.h.
 475                  * Notice also that because of the way the trace file is
 476                  * handled in trace.c, no abuse is plausible even if
 477                  * _PATH_TRACE_ is defined.
 478                  *
 479                  * First verify message came from a privileged port. */
 480                 if (ntohs(from->sin_port) > IPPORT_RESERVED) {
 481                         msglog("trace command from untrusted port on %s",
 482                                naddr_ntoa(FROM_NADDR));
 483                         return;
 484                 }
 485                 if (aifp == NULL) {
 486                         msglog("trace command from unknown router %s",
 487                                naddr_ntoa(FROM_NADDR));
 488                         return;
 489                 }
 490                 if (rip->rip_cmd == RIPCMD_TRACEON) {
 491                         rip->rip_tracefile[cc-4] = '\0';
 492                         set_tracefile((char*)rip->rip_tracefile,
 493                                       "trace command: %s\n", 0);
 494                 } else {
 495                         trace_off("tracing turned off by %s",
 496                                   naddr_ntoa(FROM_NADDR));
 497                 }
 498                 return;
 499
 500         case RIPCMD_RESPONSE:
 501                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 502                         msglim(&bad_len, FROM_NADDR,
 503                                "response of bad length (%d) from %s",
 504                                cc, naddr_ntoa(FROM_NADDR));
 505                 }
 506
 507                 /* verify message came from a router */
 508                 if (from->sin_port != ntohs(RIP_PORT)) {
 509                         msglim(&bad_router, FROM_NADDR,
 510                                "    discard RIP response from unknown port"
 511                                " %d on %s",
 512                                ntohs(from->sin_port), naddr_ntoa(FROM_NADDR));
 513                         return;
 514                 }
 515
 516                 if (rip_sock < 0) {
 517                         trace_pkt("    discard response while RIP off");
 518                         return;
 519                 }
 520
 521                 /* Are we talking to ourself or a remote gateway?
 522                  */
 523                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 524                 if (ifp1) {
 525                         if (ifp1->int_state & IS_REMOTE) {
 526                                 /* remote gateway */
 527                                 aifp = ifp1;
 528                                 if (check_remote(aifp)) {
 529                                         aifp->int_act_time = now.tv_sec;
 530                                         (void)if_ok(aifp, "remote ");
 531                                 }
 532                         } else {
 533                                 trace_pkt("    discard our own RIP response");
 534                                 return;
 535                         }
 536                 }
 537
 538                 /* Accept routing packets from routers directly connected
 539                  * via broadcast or point-to-point networks, and from
 540                  * those listed in /etc/gateways.
 541                  */
 542                 if (aifp == NULL) {
 543                         msglim(&unk_router, FROM_NADDR,
 544                                "   discard response from %s"
 545                                " via unexpected interface",
 546                                naddr_ntoa(FROM_NADDR));
 547                         return;
 548                 }
 549                 if (IS_RIP_IN_OFF(aifp->int_state)) {
 550                         trace_pkt("    discard RIPv%d response"
 551                                   " via disabled interface %s",
 552                                   rip->rip_vers, aifp->int_name);
 553                         return;
 554                 }
 555
 556                 if (n >= lim) {
 557                         msglim(&bad_len, FROM_NADDR, "empty response from %s",
 558                                naddr_ntoa(FROM_NADDR));
 559                         return;
 560                 }
 561
 562                 if (((aifp->int_state & IS_NO_RIPV1_IN)
 563                      && rip->rip_vers == RIPv1)
 564                     || ((aifp->int_state & IS_NO_RIPV2_IN)
 565                         && rip->rip_vers != RIPv1)) {
 566                         trace_pkt("    discard RIPv%d response",
 567                                   rip->rip_vers);
 568                         return;
 569                 }
 570
 571                 /* Ignore routes via dead interface.
 572                  */
 573                 if (aifp->int_state & IS_BROKE) {
 574                         trace_pkt("discard response via broken interface %s",
 575                                   aifp->int_name);
 576                         return;
 577                 }
 578
 579                 /* If the interface cares, ignore bad routers.
 580                  * Trace but do not log this problem, because where it
 581                  * happens, it happens frequently.
 582                  */
 583                 if (aifp->int_state & IS_DISTRUST) {
 584                         tg = tgates;
 585                         while (tg->tgate_addr != FROM_NADDR) {
 586                                 tg = tg->tgate_next;
 587                                 if (tg == NULL) {
 588                                         trace_pkt("    discard RIP response"
 589                                                   " from untrusted router %s",
 590                                                   naddr_ntoa(FROM_NADDR));
 591                                         return;
 592                                 }
 593                         }
 594                 }
 595
 596                 /* Authenticate the packet if we have a secret.
 597                  * If we do not have any secrets, ignore the error in
 598                  * RFC 1723 and accept it regardless.
 599                  */
 600                 if (aifp->int_auth[0].type != RIP_AUTH_NONE
 601                     && rip->rip_vers != RIPv1
 602                     && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 603                         return;
 604
 605                 do {
 606                         if (n->n_family == RIP_AF_AUTH)
 607                                 continue;
 608
 609                         n->n_metric = ntohl(n->n_metric);
 610                         dst = n->n_dst;
 611                         if (n->n_family != RIP_AF_INET
 612                             && (n->n_family != RIP_AF_UNSPEC
 613                                 || dst != RIP_DEFAULT)) {
 614                                 msglim(&bad_router, FROM_NADDR,
 615                                        "route from %s to unsupported"
 616                                        " address family=%d destination=%s",
 617                                        naddr_ntoa(FROM_NADDR),
 618                                        n->n_family,
 619                                        naddr_ntoa(dst));
 620                                 continue;
 621                         }
 622                         if (!check_dst(dst)) {
 623                                 msglim(&bad_router, FROM_NADDR,
 624                                        "bad destination %s from %s",
 625                                        naddr_ntoa(dst),
 626                                        naddr_ntoa(FROM_NADDR));
 627                                 return;
 628                         }
 629                         if (n->n_metric == 0
 630                             || n->n_metric > HOPCNT_INFINITY) {
 631                                 msglim(&bad_router, FROM_NADDR,
 632                                        "bad metric %d from %s"
 633                                        " for destination %s",
 634                                        n->n_metric,
 635                                        naddr_ntoa(FROM_NADDR),
 636                                        naddr_ntoa(dst));
 637                                 return;
 638                         }
 639
 640                         /* Notice the next-hop.
 641                          */
 642                         gate = FROM_NADDR;
 643                         if (n->n_nhop != 0) {
 644                                 if (rip->rip_vers == RIPv1) {
 645                                         n->n_nhop = 0;
 646                                 } else {
 647                                     /* Use it only if it is valid. */
 648                                     if (on_net(n->n_nhop,
 649                                                aifp->int_net, aifp->int_mask)
 650                                         && check_dst(n->n_nhop)) {
 651                                             gate = n->n_nhop;
 652                                     } else {
 653                                             msglim(&bad_nhop, FROM_NADDR,
 654                                                    "router %s to %s"
 655                                                    " has bad next hop %s",
 656                                                    naddr_ntoa(FROM_NADDR),
 657                                                    naddr_ntoa(dst),
 658                                                    naddr_ntoa(n->n_nhop));
 659                                             n->n_nhop = 0;
 660                                     }
 661                                 }
 662                         }
 663
 664                         if (rip->rip_vers == RIPv1
 665                             || 0 == (mask = ntohl(n->n_mask))) {
 666                                 mask = ripv1_mask_host(dst,aifp);
 667                         } else if ((ntohl(dst) & ~mask) != 0) {
 668                                 msglim(&bad_mask, FROM_NADDR,
 669                                        "router %s sent bad netmask"
 670                                        " %#lx with %s",
 671                                        naddr_ntoa(FROM_NADDR),
 672                                        (u_long)mask,
 673                                        naddr_ntoa(dst));
 674                                 continue;
 675                         }
 676                         if (rip->rip_vers == RIPv1)
 677                                 n->n_tag = 0;
 678
 679                         /* Adjust metric according to incoming interface..
 680                          */
 681                         n->n_metric += (aifp->int_metric
 682                                         + aifp->int_adj_inmetric);
 683                         if (n->n_metric > HOPCNT_INFINITY)
 684                                 n->n_metric = HOPCNT_INFINITY;
 685
 686                         /* Should we trust this route from this router? */
 687                         if (tg && (tn = tg->tgate_nets)->mask != 0) {
 688                                 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) {
 689                                         if (on_net(dst, tn->net, tn->mask)
 690                                             && tn->mask <= mask)
 691                                             break;
 692                                 }
 693                                 if (i >= MAX_TGATE_NETS || tn->mask == 0) {
 694                                         trace_pkt("   ignored unauthorized %s",
 695                                                   addrname(dst,mask,0));
 696                                         continue;
 697                                 }
 698                         }
 699
 700                         /* Recognize and ignore a default route we faked
 701                          * which is being sent back to us by a machine with
 702                          * broken split-horizon.
 703                          * Be a little more paranoid than that, and reject
 704                          * default routes with the same metric we advertised.
 705                          */
 706                         if (aifp->int_d_metric != 0
 707                             && dst == RIP_DEFAULT
 708                             && (int)n->n_metric >= aifp->int_d_metric)
 709                                 continue;
 710
 711                         /* We can receive aggregated RIPv2 routes that must
 712                          * be broken down before they are transmitted by
 713                          * RIPv1 via an interface on a subnet.
 714                          * We might also receive the same routes aggregated
 715                          * via other RIPv2 interfaces.
 716                          * This could cause duplicate routes to be sent on
 717                          * the RIPv1 interfaces.  "Longest matching variable
 718                          * length netmasks" lets RIPv2 listeners understand,
 719                          * but breaking down the aggregated routes for RIPv1
 720                          * listeners can produce duplicate routes.
 721                          *
 722                          * Breaking down aggregated routes here bloats
 723                          * the daemon table, but does not hurt the kernel
 724                          * table, since routes are always aggregated for
 725                          * the kernel.
 726                          *
 727                          * Notice that this does not break down network
 728                          * routes corresponding to subnets.  This is part
 729                          * of the defense against RS_NET_SYN.
 730                          */
 731                         if (have_ripv1_out
 732                             && (((rt = rtget(dst,mask)) == NULL
 733                                  || !(rt->rt_state & RS_NET_SYN)))
 734                             && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 735                                 ddst_h = v1_mask & -v1_mask;
 736                                 i = (v1_mask & ~mask)/ddst_h;
 737                                 if (i >= 511) {
 738                                         /* Punt if we would have to generate
 739                                          * an unreasonable number of routes.
 740                                          */
 741                                         if (TRACECONTENTS)
 742                                             trace_misc("accept %s-->%s as 1"
 743                                                        " instead of %d routes",
 744                                                        addrname(dst,mask,0),
 745                                                        naddr_ntoa(FROM_NADDR),
 746                                                        i+1);
 747                                         i = 0;
 748                                 } else {
 749                                         mask = v1_mask;
 750                                 }
 751                         } else {
 752                                 i = 0;
 753                         }
 754
 755                         new.rts_gate = gate;
 756                         new.rts_router = FROM_NADDR;
 757                         new.rts_metric = n->n_metric;
 758                         new.rts_tag = n->n_tag;
 759                         new.rts_time = now.tv_sec;
 760                         new.rts_ifp = aifp;
 761                         new.rts_de_ag = i;
 762                         j = 0;
 763                         for (;;) {
 764                                 input_route(dst, mask, &new, n);
 765                                 if (++j > i)
 766                                         break;
 767                                 dst = htonl(ntohl(dst) + ddst_h);
 768                         }
 769                 } while (++n < lim);
 770                 break;
 771         }
 772 #undef FROM_NADDR
 773 }
 774
 775
 776 /* Process a single input route.
 777  */
 778 static void
 779 input_route(naddr dst,                  /* network order */
 780             naddr mask,
 781             struct rt_spare *new,
 782             struct netinfo *n)
 783 {
 784         int i;
 785         struct rt_entry *rt;
 786         struct rt_spare *rts, *rts0;
 787         struct interface *ifp1;
 788
 789
 790         /* See if the other guy is telling us to send our packets to him.
 791          * Sometimes network routes arrive over a point-to-point link for
 792          * the network containing the address(es) of the link.
 793          *
 794          * If our interface is broken, switch to using the other guy.
 795          */
 796         ifp1 = ifwithaddr(dst, 1, 1);
 797         if (ifp1 != NULL
 798             && (!(ifp1->int_state & IS_BROKE)
 799                 || (ifp1->int_state & IS_PASSIVE)))
 800                 return;
 801
 802         /* Look for the route in our table.
 803          */
 804         rt = rtget(dst, mask);
 805
 806         /* Consider adding the route if we do not already have it.
 807          */
 808         if (rt == NULL) {
 809                 /* Ignore unknown routes being poisoned.
 810                  */
 811                 if (new->rts_metric == HOPCNT_INFINITY)
 812                         return;
 813
 814                 /* Ignore the route if it points to us */
 815                 if (n->n_nhop != 0
 816                     && ifwithaddr(n->n_nhop, 1, 0) != NULL)
 817                         return;
 818
 819                 /* If something has not gone crazy and tried to fill
 820                  * our memory, accept the new route.
 821                  */
 822                 if (total_routes < MAX_ROUTES)
 823                         rtadd(dst, mask, 0, new);
 824                 return;
 825         }
 826
 827         /* We already know about the route.  Consider this update.
 828          *
 829          * If (rt->rt_state & RS_NET_SYN), then this route
 830          * is the same as a network route we have inferred
 831          * for subnets we know, in order to tell RIPv1 routers
 832          * about the subnets.
 833          *
 834          * It is impossible to tell if the route is coming
 835          * from a distant RIPv2 router with the standard
 836          * netmask because that router knows about the entire
 837          * network, or if it is a round-about echo of a
 838          * synthetic, RIPv1 network route of our own.
 839          * The worst is that both kinds of routes might be
 840          * received, and the bad one might have the smaller
 841          * metric.  Partly solve this problem by never
 842          * aggregating into such a route.  Also keep it
 843          * around as long as the interface exists.
 844          */
 845
 846         rts0 = rt->rt_spares;
 847         for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
 848                 if (rts->rts_router == new->rts_router)
 849                         break;
 850                 /* Note the worst slot to reuse,
 851                  * other than the current slot.
 852                  */
 853                 if (rts0 == rt->rt_spares
 854                     || BETTER_LINK(rt, rts0, rts))
 855                         rts0 = rts;
 856         }
 857         if (i != 0) {
 858                 /* Found a route from the router already in the table.
 859                  */
 860
 861                 /* If the new route is a route broken down from an
 862                  * aggregated route, and if the previous route is either
 863                  * not a broken down route or was broken down from a finer
 864                  * netmask, and if the previous route is current,
 865                  * then forget this one.
 866                  */
 867                 if (new->rts_de_ag > rts->rts_de_ag
 868                     && now_stale <= rts->rts_time)
 869                         return;
 870
 871                 /* Keep poisoned routes around only long enough to pass
 872                  * the poison on.  Use a new timestamp for good routes.
 873                  */
 874                 if (rts->rts_metric == HOPCNT_INFINITY
 875                     && new->rts_metric == HOPCNT_INFINITY)
 876                         new->rts_time = rts->rts_time;
 877
 878                 /* If this is an update for the router we currently prefer,
 879                  * then note it.
 880                  */
 881                 if (i == NUM_SPARES) {
 882                         rtchange(rt, rt->rt_state, new, 0);
 883                         /* If the route got worse, check for something better.
 884                          */
 885                         if (new->rts_metric > rts->rts_metric)
 886                                 rtswitch(rt, 0);
 887                         return;
 888                 }
 889
 890                 /* This is an update for a spare route.
 891                  * Finished if the route is unchanged.
 892                  */
 893                 if (rts->rts_gate == new->rts_gate
 894                     && rts->rts_metric == new->rts_metric
 895                     && rts->rts_tag == new->rts_tag) {
 896                         trace_upslot(rt, rts, new);
 897                         *rts = *new;
 898                         return;
 899                 }
 900                 /* Forget it if it has gone bad.
 901                  */
 902                 if (new->rts_metric == HOPCNT_INFINITY) {
 903                         rts_delete(rt, rts);
 904                         return;
 905                 }
 906
 907         } else {
 908                 /* The update is for a route we know about,
 909                  * but not from a familiar router.
 910                  *
 911                  * Ignore the route if it points to us.
 912                  */
 913                 if (n->n_nhop != 0
 914                     && NULL != ifwithaddr(n->n_nhop, 1, 0))
 915                         return;
 916
 917                 /* the loop above set rts0=worst spare */
 918                 rts = rts0;
 919
 920                 /* Save the route as a spare only if it has
 921                  * a better metric than our worst spare.
 922                  * This also ignores poisoned routes (those
 923                  * received with metric HOPCNT_INFINITY).
 924                  */
 925                 if (new->rts_metric >= rts->rts_metric)
 926                         return;
 927         }
 928
 929         trace_upslot(rt, rts, new);
 930         *rts = *new;
 931
 932         /* try to switch to a better route */
 933         rtswitch(rt, rts);
 934 }
 935
 936
 937 static int                              /* 0 if bad */
 938 ck_passwd(struct interface *aifp,
 939           struct rip *rip,
 940           void *lim,
 941           naddr from,
 942           struct msg_limit *use_authp)
 943 {
 944 #       define NA (rip->rip_auths)
 945         struct netauth *na2;
 946         struct auth *ap;
 947         MD5_CTX md5_ctx;
 948         u_char hash[RIP_AUTH_PW_LEN];
 949         int i, len;
 950
 951         assert(aifp != NULL);
 952         if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) {
 953                 msglim(use_authp, from, "missing password from %s",
 954                        naddr_ntoa(from));
 955                 return 0;
 956         }
 957
 958         /* accept any current (+/- 24 hours) password
 959          */
 960         for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 961                 if (ap->type != NA->a_type
 962                     || (u_long)ap->start > (u_long)clk.tv_sec+DAY
 963                     || (u_long)ap->end+DAY < (u_long)clk.tv_sec)
 964                         continue;
 965
 966                 if (NA->a_type == RIP_AUTH_PW) {
 967                         if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN))
 968                                 return 1;
 969
 970                 } else {
 971                         /* accept MD5 secret with the right key ID
 972                          */
 973                         if (NA->au.a_md5.md5_keyid != ap->keyid)
 974                                 continue;
 975
 976                         len = ntohs(NA->au.a_md5.md5_pkt_len);
 977                         if ((len-sizeof(*rip)) % sizeof(*NA) != 0
 978                             || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) {
 979                                 msglim(use_authp, from,
 980                                        "wrong MD5 RIPv2 packet length of %d"
 981                                        " instead of %d from %s",
 982                                        len, (int)((char *)lim-(char *)rip
 983                                                   -sizeof(*NA)),
 984                                        naddr_ntoa(from));
 985                                 return 0;
 986                         }
 987                         na2 = (struct netauth *)((char *)rip+len);
 988
 989                         /* Given a good hash value, these are not security
 990                          * problems so be generous and accept the routes,
 991                          * after complaining.
 992                          */
 993                         if (TRACEPACKETS) {
 994                                 if (NA->au.a_md5.md5_auth_len
 995                                     != RIP_AUTH_MD5_HASH_LEN)
 996                                         msglim(use_authp, from,
 997                                                "unknown MD5 RIPv2 auth len %#x"
 998                                                " instead of %#x from %s",
 999                                                NA->au.a_md5.md5_auth_len,
1000                                                (unsigned)RIP_AUTH_MD5_HASH_LEN,
1001                                                naddr_ntoa(from));
1002                                 if (na2->a_family != RIP_AF_AUTH)
1003                                         msglim(use_authp, from,
1004                                                "unknown MD5 RIPv2 family %#x"
1005                                                " instead of %#x from %s",
1006                                                na2->a_family, RIP_AF_AUTH,
1007                                                naddr_ntoa(from));
1008                                 if (na2->a_type != ntohs(1))
1009                                         msglim(use_authp, from,
1010                                                "MD5 RIPv2 hash has %#x"
1011                                                " instead of %#x from %s",
1012                                                na2->a_type, ntohs(1),
1013                                                naddr_ntoa(from));
1014                         }
1015
1016                         MD5Init(&md5_ctx);
1017                         MD5Update(&md5_ctx, (u_char *)rip,
1018                                   len + RIP_AUTH_MD5_HASH_XTRA);
1019                         MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_KEY_LEN);
1020                         MD5Final(hash, &md5_ctx);
1021                         if (!memcmp(hash, na2->au.au_pw, sizeof(hash)))
1022                                 return 1;
1023                 }
1024         }
1025
1026         msglim(use_authp, from, "bad password from %s",
1027                naddr_ntoa(from));
1028         return 0;
1029 #undef NA
1030 }