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 * 3. 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 } 1036