1 /* $NetBSD: input.c,v 1.27 2001/03/10 23:52:45 christos Exp $ */ 2 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgment: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include "defs.h" 37 38 #ifdef __NetBSD__ 39 __RCSID("$NetBSD: input.c,v 1.27 2001/03/10 23:52:45 christos Exp $"); 40 #elif defined(__FreeBSD__) 41 __RCSID("$FreeBSD$"); 42 #else 43 __RCSID("Revision: 2.23 "); 44 #ident "Revision: 2.23 " 45 #endif 46 47 static void input(struct sockaddr_in *, struct interface *, struct interface *, 48 struct rip *, int); 49 static void input_route(naddr, naddr, struct rt_spare *, struct netinfo *); 50 static int ck_passwd(struct interface *, struct rip *, void *, 51 naddr, struct msg_limit *); 52 53 54 /* process RIP input 55 */ 56 void 57 read_rip(int sock, 58 struct interface *sifp) 59 { 60 struct sockaddr_in from; 61 struct interface *aifp; 62 int fromlen, cc; 63 #ifdef USE_PASSIFNAME 64 static struct msg_limit bad_name; 65 struct { 66 char ifname[IFNAMSIZ]; 67 union pkt_buf pbuf; 68 } inbuf; 69 #else 70 struct { 71 union pkt_buf pbuf; 72 } inbuf; 73 #endif 74 75 76 for (;;) { 77 fromlen = sizeof(from); 78 cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0, 79 (struct sockaddr*)&from, &fromlen); 80 if (cc <= 0) { 81 if (cc < 0 && errno != EWOULDBLOCK) 82 LOGERR("recvfrom(rip)"); 83 break; 84 } 85 if (fromlen != sizeof(struct sockaddr_in)) 86 logbad(1,"impossible recvfrom(rip) fromlen=%d", 87 fromlen); 88 89 /* aifp is the "authenticated" interface via which the packet 90 * arrived. In fact, it is only the interface on which 91 * the packet should have arrived based on is source 92 * address. 93 * sifp is interface associated with the socket through which 94 * the packet was received. 95 */ 96 #ifdef USE_PASSIFNAME 97 if ((cc -= sizeof(inbuf.ifname)) < 0) 98 logbad(0,"missing USE_PASSIFNAME; only %d bytes", 99 cc+sizeof(inbuf.ifname)); 100 101 /* check the remote interfaces first */ 102 for (aifp = remote_if; aifp; aifp = aifp->int_rlink) { 103 if (aifp->int_addr == from.sin_addr.s_addr) 104 break; 105 } 106 if (aifp == 0) { 107 aifp = ifwithname(inbuf.ifname, 0); 108 if (aifp == 0) { 109 msglim(&bad_name, from.sin_addr.s_addr, 110 "impossible interface name %.*s", 111 IFNAMSIZ, inbuf.ifname); 112 } else if (((aifp->int_if_flags & IFF_POINTOPOINT) 113 && aifp->int_dstaddr!=from.sin_addr.s_addr) 114 || (!(aifp->int_if_flags & IFF_POINTOPOINT) 115 && !on_net(from.sin_addr.s_addr, 116 aifp->int_net, 117 aifp->int_mask))) { 118 /* If it came via the wrong interface, do not 119 * trust it. 120 */ 121 aifp = 0; 122 } 123 } 124 #else 125 aifp = iflookup(from.sin_addr.s_addr); 126 #endif 127 if (sifp == 0) 128 sifp = aifp; 129 130 input(&from, sifp, aifp, &inbuf.pbuf.rip, cc); 131 } 132 } 133 134 135 /* Process a RIP packet 136 */ 137 static void 138 input(struct sockaddr_in *from, /* received from this IP address */ 139 struct interface *sifp, /* interface of incoming socket */ 140 struct interface *aifp, /* "authenticated" interface */ 141 struct rip *rip, 142 int cc) 143 { 144 # define FROM_NADDR from->sin_addr.s_addr 145 static struct msg_limit use_auth, bad_len, bad_mask; 146 static struct msg_limit unk_router, bad_router, bad_nhop; 147 148 struct rt_entry *rt; 149 struct rt_spare new; 150 struct netinfo *n, *lim; 151 struct interface *ifp1; 152 naddr gate, mask, v1_mask, dst, ddst_h = 0; 153 struct auth *ap; 154 struct tgate *tg = 0; 155 struct tgate_net *tn; 156 int i, j; 157 158 /* Notice when we hear from a remote gateway 159 */ 160 if (aifp != 0 161 && (aifp->int_state & IS_REMOTE)) 162 aifp->int_act_time = now.tv_sec; 163 164 trace_rip("Recv", "from", from, sifp, rip, cc); 165 166 if (rip->rip_vers == 0) { 167 msglim(&bad_router, FROM_NADDR, 168 "RIP version 0, cmd %d, packet received from %s", 169 rip->rip_cmd, naddr_ntoa(FROM_NADDR)); 170 return; 171 } else if (rip->rip_vers > RIPv2) { 172 rip->rip_vers = RIPv2; 173 } 174 if (cc > (int)OVER_MAXPACKETSIZE) { 175 msglim(&bad_router, FROM_NADDR, 176 "packet at least %d bytes too long received from %s", 177 cc-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR)); 178 return; 179 } 180 181 n = rip->rip_nets; 182 lim = (struct netinfo *)((char*)rip + cc); 183 184 /* Notice authentication. 185 * As required by section 4.2 in RFC 1723, discard authenticated 186 * RIPv2 messages, but only if configured for that silliness. 187 * 188 * RIPv2 authentication is lame. Why authenticate queries? 189 * Why should a RIPv2 implementation with authentication disabled 190 * not be able to listen to RIPv2 packets with authentication, while 191 * RIPv1 systems will listen? Crazy! 192 */ 193 if (!auth_ok 194 && rip->rip_vers == RIPv2 195 && n < lim && n->n_family == RIP_AF_AUTH) { 196 msglim(&use_auth, FROM_NADDR, 197 "RIPv2 message with authentication from %s discarded", 198 naddr_ntoa(FROM_NADDR)); 199 return; 200 } 201 202 switch (rip->rip_cmd) { 203 case RIPCMD_REQUEST: 204 /* For mere requests, be a little sloppy about the source 205 */ 206 if (aifp == 0) 207 aifp = sifp; 208 209 /* Are we talking to ourself or a remote gateway? 210 */ 211 ifp1 = ifwithaddr(FROM_NADDR, 0, 1); 212 if (ifp1) { 213 if (ifp1->int_state & IS_REMOTE) { 214 /* remote gateway */ 215 aifp = ifp1; 216 if (check_remote(aifp)) { 217 aifp->int_act_time = now.tv_sec; 218 (void)if_ok(aifp, "remote "); 219 } 220 } else if (from->sin_port == htons(RIP_PORT)) { 221 trace_pkt(" discard our own RIP request"); 222 return; 223 } 224 } 225 226 /* did the request come from a router? 227 */ 228 if (from->sin_port == htons(RIP_PORT)) { 229 /* yes, ignore the request if RIP is off so that 230 * the router does not depend on us. 231 */ 232 if (rip_sock < 0 233 || (aifp != 0 234 && IS_RIP_OUT_OFF(aifp->int_state))) { 235 trace_pkt(" discard request while RIP off"); 236 return; 237 } 238 } 239 240 /* According to RFC 1723, we should ignore unauthenticated 241 * queries. That is too silly to bother with. Sheesh! 242 * Are forwarding tables supposed to be secret, when 243 * a bad guy can infer them with test traffic? When RIP 244 * is still the most common router-discovery protocol 245 * and so hosts need to send queries that will be answered? 246 * What about `rtquery`? 247 * Maybe on firewalls you'd care, but not enough to 248 * give up the diagnostic facilities of remote probing. 249 */ 250 251 if (n >= lim) { 252 msglim(&bad_len, FROM_NADDR, "empty request from %s", 253 naddr_ntoa(FROM_NADDR)); 254 return; 255 } 256 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) { 257 msglim(&bad_len, FROM_NADDR, 258 "request of bad length (%d) from %s", 259 cc, naddr_ntoa(FROM_NADDR)); 260 } 261 262 if (rip->rip_vers == RIPv2 263 && (aifp == 0 || (aifp->int_state & IS_NO_RIPV1_OUT))) { 264 v12buf.buf->rip_vers = RIPv2; 265 /* If we have a secret but it is a cleartext secret, 266 * do not disclose our secret unless the other guy 267 * already knows it. 268 */ 269 ap = find_auth(aifp); 270 if (ap != 0 && ap->type == RIP_AUTH_PW 271 && n->n_family == RIP_AF_AUTH 272 && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth)) 273 ap = 0; 274 } else { 275 v12buf.buf->rip_vers = RIPv1; 276 ap = 0; 277 } 278 clr_ws_buf(&v12buf, ap); 279 280 do { 281 NTOHL(n->n_metric); 282 283 /* A single entry with family RIP_AF_UNSPEC and 284 * metric HOPCNT_INFINITY means "all routes". 285 * We respond to routers only if we are acting 286 * as a supplier, or to anyone other than a router 287 * (i.e. a query). 288 */ 289 if (n->n_family == RIP_AF_UNSPEC 290 && n->n_metric == HOPCNT_INFINITY) { 291 /* Answer a query from a utility program 292 * with all we know. 293 */ 294 if (from->sin_port != htons(RIP_PORT)) { 295 supply(from, aifp, OUT_QUERY, 0, 296 rip->rip_vers, ap != 0); 297 return; 298 } 299 300 /* A router trying to prime its tables. 301 * Filter the answer in the about same way 302 * broadcasts are filtered. 303 * 304 * Only answer a router if we are a supplier 305 * to keep an unwary host that is just starting 306 * from picking us as a router. 307 */ 308 if (aifp == 0) { 309 trace_pkt("ignore distant router"); 310 return; 311 } 312 if (!supplier 313 || IS_RIP_OFF(aifp->int_state)) { 314 trace_pkt("ignore; not supplying"); 315 return; 316 } 317 318 /* Do not answer a RIPv1 router if 319 * we are sending RIPv2. But do offer 320 * poor man's router discovery. 321 */ 322 if ((aifp->int_state & IS_NO_RIPV1_OUT) 323 && rip->rip_vers == RIPv1) { 324 if (!(aifp->int_state & IS_PM_RDISC)) { 325 trace_pkt("ignore; sending RIPv2"); 326 return; 327 } 328 329 v12buf.n->n_family = RIP_AF_INET; 330 v12buf.n->n_dst = RIP_DEFAULT; 331 i = aifp->int_d_metric; 332 if (0 != (rt = rtget(RIP_DEFAULT, 0))) 333 i = MIN(i, (rt->rt_metric 334 +aifp->int_metric+1)); 335 v12buf.n->n_metric = htonl(i); 336 v12buf.n++; 337 break; 338 } 339 340 /* Respond with RIPv1 instead of RIPv2 if 341 * that is what we are broadcasting on the 342 * interface to keep the remote router from 343 * getting the wrong initial idea of the 344 * routes we send. 345 */ 346 supply(from, aifp, OUT_UNICAST, 0, 347 (aifp->int_state & IS_NO_RIPV1_OUT) 348 ? RIPv2 : RIPv1, 349 ap != 0); 350 return; 351 } 352 353 /* Ignore authentication */ 354 if (n->n_family == RIP_AF_AUTH) 355 continue; 356 357 if (n->n_family != RIP_AF_INET) { 358 msglim(&bad_router, FROM_NADDR, 359 "request from %s for unsupported" 360 " (af %d) %s", 361 naddr_ntoa(FROM_NADDR), 362 ntohs(n->n_family), 363 naddr_ntoa(n->n_dst)); 364 return; 365 } 366 367 /* We are being asked about a specific destination. 368 */ 369 dst = n->n_dst; 370 if (!check_dst(dst)) { 371 msglim(&bad_router, FROM_NADDR, 372 "bad queried destination %s from %s", 373 naddr_ntoa(dst), 374 naddr_ntoa(FROM_NADDR)); 375 return; 376 } 377 378 /* decide what mask was intended */ 379 if (rip->rip_vers == RIPv1 380 || 0 == (mask = ntohl(n->n_mask)) 381 || 0 != (ntohl(dst) & ~mask)) 382 mask = ripv1_mask_host(dst, aifp); 383 384 /* try to find the answer */ 385 rt = rtget(dst, mask); 386 if (!rt && dst != RIP_DEFAULT) 387 rt = rtfind(n->n_dst); 388 389 if (v12buf.buf->rip_vers != RIPv1) 390 v12buf.n->n_mask = mask; 391 if (rt == 0) { 392 /* we do not have the answer */ 393 v12buf.n->n_metric = HOPCNT_INFINITY; 394 } else { 395 /* we have the answer, so compute the 396 * right metric and next hop. 397 */ 398 v12buf.n->n_family = RIP_AF_INET; 399 v12buf.n->n_dst = dst; 400 v12buf.n->n_metric = (rt->rt_metric+1 401 + ((aifp!=0) 402 ? aifp->int_metric 403 : 1)); 404 if (v12buf.n->n_metric > HOPCNT_INFINITY) 405 v12buf.n->n_metric = HOPCNT_INFINITY; 406 if (v12buf.buf->rip_vers != RIPv1) { 407 v12buf.n->n_tag = rt->rt_tag; 408 v12buf.n->n_mask = mask; 409 if (aifp != 0 410 && on_net(rt->rt_gate, 411 aifp->int_net, 412 aifp->int_mask) 413 && rt->rt_gate != aifp->int_addr) 414 v12buf.n->n_nhop = rt->rt_gate; 415 } 416 } 417 HTONL(v12buf.n->n_metric); 418 419 /* Stop paying attention if we fill the output buffer. 420 */ 421 if (++v12buf.n >= v12buf.lim) 422 break; 423 } while (++n < lim); 424 425 /* Send the answer about specific routes. 426 */ 427 if (ap != 0 && ap->type == RIP_AUTH_MD5) 428 end_md5_auth(&v12buf, ap); 429 430 if (from->sin_port != htons(RIP_PORT)) { 431 /* query */ 432 (void)output(OUT_QUERY, from, aifp, 433 v12buf.buf, 434 ((char *)v12buf.n - (char*)v12buf.buf)); 435 } else if (supplier) { 436 (void)output(OUT_UNICAST, from, aifp, 437 v12buf.buf, 438 ((char *)v12buf.n - (char*)v12buf.buf)); 439 } else { 440 /* Only answer a router if we are a supplier 441 * to keep an unwary host that is just starting 442 * from picking us an a router. 443 */ 444 ; 445 } 446 return; 447 448 case RIPCMD_TRACEON: 449 case RIPCMD_TRACEOFF: 450 /* Notice that trace messages are turned off for all possible 451 * abuse if _PATH_TRACE is undefined in pathnames.h. 452 * Notice also that because of the way the trace file is 453 * handled in trace.c, no abuse is plausible even if 454 * _PATH_TRACE_ is defined. 455 * 456 * First verify message came from a privileged port. */ 457 if (ntohs(from->sin_port) > IPPORT_RESERVED) { 458 msglog("trace command from untrusted port on %s", 459 naddr_ntoa(FROM_NADDR)); 460 return; 461 } 462 if (aifp == 0) { 463 msglog("trace command from unknown router %s", 464 naddr_ntoa(FROM_NADDR)); 465 return; 466 } 467 if (rip->rip_cmd == RIPCMD_TRACEON) { 468 rip->rip_tracefile[cc-4] = '\0'; 469 #ifndef __NetBSD__ 470 set_tracefile((char*)rip->rip_tracefile, 471 "trace command: %s\n", 0); 472 #else 473 msglog("RIP_TRACEON for `%s' from %s ignored", 474 (char *) rip->rip_tracefile, 475 naddr_ntoa(FROM_NADDR)); 476 #endif 477 } else { 478 #ifndef __NetBSD__ 479 trace_off("tracing turned off by %s", 480 naddr_ntoa(FROM_NADDR)); 481 #else 482 msglog("RIP_TRACEOFF from %s ignored", 483 naddr_ntoa(FROM_NADDR)); 484 #endif 485 } 486 return; 487 488 case RIPCMD_RESPONSE: 489 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) { 490 msglim(&bad_len, FROM_NADDR, 491 "response of bad length (%d) from %s", 492 cc, naddr_ntoa(FROM_NADDR)); 493 } 494 495 /* verify message came from a router */ 496 if (from->sin_port != ntohs(RIP_PORT)) { 497 msglim(&bad_router, FROM_NADDR, 498 " discard RIP response from unknown port" 499 " %d on %s", 500 ntohs(from->sin_port), naddr_ntoa(FROM_NADDR)); 501 return; 502 } 503 504 if (rip_sock < 0) { 505 trace_pkt(" discard response while RIP off"); 506 return; 507 } 508 509 /* Are we talking to ourself or a remote gateway? 510 */ 511 ifp1 = ifwithaddr(FROM_NADDR, 0, 1); 512 if (ifp1) { 513 if (ifp1->int_state & IS_REMOTE) { 514 /* remote gateway */ 515 aifp = ifp1; 516 if (check_remote(aifp)) { 517 aifp->int_act_time = now.tv_sec; 518 (void)if_ok(aifp, "remote "); 519 } 520 } else { 521 trace_pkt(" discard our own RIP response"); 522 return; 523 } 524 } 525 526 /* Accept routing packets from routers directly connected 527 * via broadcast or point-to-point networks, and from 528 * those listed in /etc/gateways. 529 */ 530 if (aifp == 0) { 531 msglim(&unk_router, FROM_NADDR, 532 " discard response from %s" 533 " via unexpected interface", 534 naddr_ntoa(FROM_NADDR)); 535 return; 536 } 537 if (IS_RIP_IN_OFF(aifp->int_state)) { 538 trace_pkt(" discard RIPv%d response" 539 " via disabled interface %s", 540 rip->rip_vers, aifp->int_name); 541 return; 542 } 543 544 if (n >= lim) { 545 msglim(&bad_len, FROM_NADDR, "empty response from %s", 546 naddr_ntoa(FROM_NADDR)); 547 return; 548 } 549 550 if (((aifp->int_state & IS_NO_RIPV1_IN) 551 && rip->rip_vers == RIPv1) 552 || ((aifp->int_state & IS_NO_RIPV2_IN) 553 && rip->rip_vers != RIPv1)) { 554 trace_pkt(" discard RIPv%d response", 555 rip->rip_vers); 556 return; 557 } 558 559 /* Ignore routes via dead interface. 560 */ 561 if (aifp->int_state & IS_BROKE) { 562 trace_pkt("discard response via broken interface %s", 563 aifp->int_name); 564 return; 565 } 566 567 /* If the interface cares, ignore bad routers. 568 * Trace but do not log this problem, because where it 569 * happens, it happens frequently. 570 */ 571 if (aifp->int_state & IS_DISTRUST) { 572 tg = tgates; 573 while (tg->tgate_addr != FROM_NADDR) { 574 tg = tg->tgate_next; 575 if (tg == 0) { 576 trace_pkt(" discard RIP response" 577 " from untrusted router %s", 578 naddr_ntoa(FROM_NADDR)); 579 return; 580 } 581 } 582 } 583 584 /* Authenticate the packet if we have a secret. 585 * If we do not have any secrets, ignore the error in 586 * RFC 1723 and accept it regardless. 587 */ 588 if (aifp->int_auth[0].type != RIP_AUTH_NONE 589 && rip->rip_vers != RIPv1 590 && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth)) 591 return; 592 593 do { 594 if (n->n_family == RIP_AF_AUTH) 595 continue; 596 597 NTOHL(n->n_metric); 598 dst = n->n_dst; 599 if (n->n_family != RIP_AF_INET 600 && (n->n_family != RIP_AF_UNSPEC 601 || dst != RIP_DEFAULT)) { 602 msglim(&bad_router, FROM_NADDR, 603 "route from %s to unsupported" 604 " address family=%d destination=%s", 605 naddr_ntoa(FROM_NADDR), 606 n->n_family, 607 naddr_ntoa(dst)); 608 continue; 609 } 610 if (!check_dst(dst)) { 611 msglim(&bad_router, FROM_NADDR, 612 "bad destination %s from %s", 613 naddr_ntoa(dst), 614 naddr_ntoa(FROM_NADDR)); 615 return; 616 } 617 if (n->n_metric == 0 618 || n->n_metric > HOPCNT_INFINITY) { 619 msglim(&bad_router, FROM_NADDR, 620 "bad metric %d from %s" 621 " for destination %s", 622 n->n_metric, 623 naddr_ntoa(FROM_NADDR), 624 naddr_ntoa(dst)); 625 return; 626 } 627 628 /* Notice the next-hop. 629 */ 630 gate = FROM_NADDR; 631 if (n->n_nhop != 0) { 632 if (rip->rip_vers == RIPv1) { 633 n->n_nhop = 0; 634 } else { 635 /* Use it only if it is valid. */ 636 if (on_net(n->n_nhop, 637 aifp->int_net, aifp->int_mask) 638 && check_dst(n->n_nhop)) { 639 gate = n->n_nhop; 640 } else { 641 msglim(&bad_nhop, FROM_NADDR, 642 "router %s to %s" 643 " has bad next hop %s", 644 naddr_ntoa(FROM_NADDR), 645 naddr_ntoa(dst), 646 naddr_ntoa(n->n_nhop)); 647 n->n_nhop = 0; 648 } 649 } 650 } 651 652 if (rip->rip_vers == RIPv1 653 || 0 == (mask = ntohl(n->n_mask))) { 654 mask = ripv1_mask_host(dst,aifp); 655 } else if ((ntohl(dst) & ~mask) != 0) { 656 msglim(&bad_mask, FROM_NADDR, 657 "router %s sent bad netmask" 658 " %#lx with %s", 659 naddr_ntoa(FROM_NADDR), 660 (u_long)mask, 661 naddr_ntoa(dst)); 662 continue; 663 } 664 if (rip->rip_vers == RIPv1) 665 n->n_tag = 0; 666 667 /* Adjust metric according to incoming interface.. 668 */ 669 n->n_metric += aifp->int_metric; 670 if (n->n_metric > HOPCNT_INFINITY) 671 n->n_metric = HOPCNT_INFINITY; 672 673 /* Should we trust this route from this router? */ 674 if (tg && (tn = tg->tgate_nets)->mask != 0) { 675 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) { 676 if (on_net(dst, tn->net, tn->mask) 677 && tn->mask <= mask) 678 break; 679 } 680 if (i >= MAX_TGATE_NETS || tn->mask == 0) { 681 trace_pkt(" ignored unauthorized %s", 682 addrname(dst,mask,0)); 683 continue; 684 } 685 } 686 687 /* Recognize and ignore a default route we faked 688 * which is being sent back to us by a machine with 689 * broken split-horizon. 690 * Be a little more paranoid than that, and reject 691 * default routes with the same metric we advertised. 692 */ 693 if (aifp->int_d_metric != 0 694 && dst == RIP_DEFAULT 695 && (int)n->n_metric >= aifp->int_d_metric) 696 continue; 697 698 /* We can receive aggregated RIPv2 routes that must 699 * be broken down before they are transmitted by 700 * RIPv1 via an interface on a subnet. 701 * We might also receive the same routes aggregated 702 * via other RIPv2 interfaces. 703 * This could cause duplicate routes to be sent on 704 * the RIPv1 interfaces. "Longest matching variable 705 * length netmasks" lets RIPv2 listeners understand, 706 * but breaking down the aggregated routes for RIPv1 707 * listeners can produce duplicate routes. 708 * 709 * Breaking down aggregated routes here bloats 710 * the daemon table, but does not hurt the kernel 711 * table, since routes are always aggregated for 712 * the kernel. 713 * 714 * Notice that this does not break down network 715 * routes corresponding to subnets. This is part 716 * of the defense against RS_NET_SYN. 717 */ 718 if (have_ripv1_out 719 && (((rt = rtget(dst,mask)) == 0 720 || !(rt->rt_state & RS_NET_SYN))) 721 && (v1_mask = ripv1_mask_net(dst,0)) > mask) { 722 ddst_h = v1_mask & -v1_mask; 723 i = (v1_mask & ~mask)/ddst_h; 724 if (i >= 511) { 725 /* Punt if we would have to generate 726 * an unreasonable number of routes. 727 */ 728 if (TRACECONTENTS) 729 trace_misc("accept %s-->%s as 1" 730 " instead of %d routes", 731 addrname(dst,mask,0), 732 naddr_ntoa(FROM_NADDR), 733 i+1); 734 i = 0; 735 } else { 736 mask = v1_mask; 737 } 738 } else { 739 i = 0; 740 } 741 742 new.rts_gate = gate; 743 new.rts_router = FROM_NADDR; 744 new.rts_metric = n->n_metric; 745 new.rts_tag = n->n_tag; 746 new.rts_time = now.tv_sec; 747 new.rts_ifp = aifp; 748 new.rts_de_ag = i; 749 j = 0; 750 for (;;) { 751 input_route(dst, mask, &new, n); 752 if (++j > i) 753 break; 754 dst = htonl(ntohl(dst) + ddst_h); 755 } 756 } while (++n < lim); 757 break; 758 } 759 #undef FROM_NADDR 760 } 761 762 763 /* Process a single input route. 764 */ 765 static void 766 input_route(naddr dst, /* network order */ 767 naddr mask, 768 struct rt_spare *new, 769 struct netinfo *n) 770 { 771 int i; 772 struct rt_entry *rt; 773 struct rt_spare *rts, *rts0; 774 struct interface *ifp1; 775 776 777 /* See if the other guy is telling us to send our packets to him. 778 * Sometimes network routes arrive over a point-to-point link for 779 * the network containing the address(es) of the link. 780 * 781 * If our interface is broken, switch to using the other guy. 782 */ 783 ifp1 = ifwithaddr(dst, 1, 1); 784 if (ifp1 != 0 785 && (!(ifp1->int_state & IS_BROKE) 786 || (ifp1->int_state & IS_PASSIVE))) 787 return; 788 789 /* Look for the route in our table. 790 */ 791 rt = rtget(dst, mask); 792 793 /* Consider adding the route if we do not already have it. 794 */ 795 if (rt == 0) { 796 /* Ignore unknown routes being poisoned. 797 */ 798 if (new->rts_metric == HOPCNT_INFINITY) 799 return; 800 801 /* Ignore the route if it points to us */ 802 if (n->n_nhop != 0 803 && 0 != ifwithaddr(n->n_nhop, 1, 0)) 804 return; 805 806 /* If something has not gone crazy and tried to fill 807 * our memory, accept the new route. 808 */ 809 if (total_routes < MAX_ROUTES) 810 rtadd(dst, mask, 0, new); 811 return; 812 } 813 814 /* We already know about the route. Consider this update. 815 * 816 * If (rt->rt_state & RS_NET_SYN), then this route 817 * is the same as a network route we have inferred 818 * for subnets we know, in order to tell RIPv1 routers 819 * about the subnets. 820 * 821 * It is impossible to tell if the route is coming 822 * from a distant RIPv2 router with the standard 823 * netmask because that router knows about the entire 824 * network, or if it is a round-about echo of a 825 * synthetic, RIPv1 network route of our own. 826 * The worst is that both kinds of routes might be 827 * received, and the bad one might have the smaller 828 * metric. Partly solve this problem by never 829 * aggregating into such a route. Also keep it 830 * around as long as the interface exists. 831 */ 832 833 rts0 = rt->rt_spares; 834 for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) { 835 if (rts->rts_router == new->rts_router) 836 break; 837 /* Note the worst slot to reuse, 838 * other than the current slot. 839 */ 840 if (rts0 == rt->rt_spares 841 || BETTER_LINK(rt, rts0, rts)) 842 rts0 = rts; 843 } 844 if (i != 0) { 845 /* Found a route from the router already in the table. 846 */ 847 848 /* If the new route is a route broken down from an 849 * aggregated route, and if the previous route is either 850 * not a broken down route or was broken down from a finer 851 * netmask, and if the previous route is current, 852 * then forget this one. 853 */ 854 if (new->rts_de_ag > rts->rts_de_ag 855 && now_stale <= rts->rts_time) 856 return; 857 858 /* Keep poisoned routes around only long enough to pass 859 * the poison on. Use a new timestamp for good routes. 860 */ 861 if (rts->rts_metric == HOPCNT_INFINITY 862 && new->rts_metric == HOPCNT_INFINITY) 863 new->rts_time = rts->rts_time; 864 865 /* If this is an update for the router we currently prefer, 866 * then note it. 867 */ 868 if (i == NUM_SPARES) { 869 rtchange(rt, rt->rt_state, new, 0); 870 /* If the route got worse, check for something better. 871 */ 872 if (new->rts_metric > rts->rts_metric) 873 rtswitch(rt, 0); 874 return; 875 } 876 877 /* This is an update for a spare route. 878 * Finished if the route is unchanged. 879 */ 880 if (rts->rts_gate == new->rts_gate 881 && rts->rts_metric == new->rts_metric 882 && rts->rts_tag == new->rts_tag) { 883 trace_upslot(rt, rts, new); 884 *rts = *new; 885 return; 886 } 887 /* Forget it if it has gone bad. 888 */ 889 if (new->rts_metric == HOPCNT_INFINITY) { 890 rts_delete(rt, rts); 891 return; 892 } 893 894 } else { 895 /* The update is for a route we know about, 896 * but not from a familiar router. 897 * 898 * Ignore the route if it points to us. 899 */ 900 if (n->n_nhop != 0 901 && 0 != ifwithaddr(n->n_nhop, 1, 0)) 902 return; 903 904 /* the loop above set rts0=worst spare */ 905 rts = rts0; 906 907 /* Save the route as a spare only if it has 908 * a better metric than our worst spare. 909 * This also ignores poisoned routes (those 910 * received with metric HOPCNT_INFINITY). 911 */ 912 if (new->rts_metric >= rts->rts_metric) 913 return; 914 } 915 916 trace_upslot(rt, rts, new); 917 *rts = *new; 918 919 /* try to switch to a better route */ 920 rtswitch(rt, rts); 921 } 922 923 924 static int /* 0 if bad */ 925 ck_passwd(struct interface *aifp, 926 struct rip *rip, 927 void *lim, 928 naddr from, 929 struct msg_limit *use_authp) 930 { 931 # define NA (rip->rip_auths) 932 struct netauth *na2; 933 struct auth *ap; 934 MD5_CTX md5_ctx; 935 u_char hash[RIP_AUTH_PW_LEN]; 936 int i, len; 937 938 939 if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) { 940 msglim(use_authp, from, "missing password from %s", 941 naddr_ntoa(from)); 942 return 0; 943 } 944 945 /* accept any current (+/- 24 hours) password 946 */ 947 for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) { 948 if (ap->type != NA->a_type 949 || (u_long)ap->start > (u_long)clk.tv_sec+DAY 950 || (u_long)ap->end+DAY < (u_long)clk.tv_sec) 951 continue; 952 953 if (NA->a_type == RIP_AUTH_PW) { 954 if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN)) 955 return 1; 956 957 } else { 958 /* accept MD5 secret with the right key ID 959 */ 960 if (NA->au.a_md5.md5_keyid != ap->keyid) 961 continue; 962 963 len = ntohs(NA->au.a_md5.md5_pkt_len); 964 if ((len-sizeof(*rip)) % sizeof(*NA) != 0 965 || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) { 966 msglim(use_authp, from, 967 "wrong MD5 RIPv2 packet length of %d" 968 " instead of %d from %s", 969 len, (int)((char *)lim-(char *)rip 970 -sizeof(*NA)), 971 naddr_ntoa(from)); 972 return 0; 973 } 974 na2 = (struct netauth *)((char *)rip+len); 975 976 /* Given a good hash value, these are not security 977 * problems so be generous and accept the routes, 978 * after complaining. 979 */ 980 if (TRACEPACKETS) { 981 if (NA->au.a_md5.md5_auth_len 982 != RIP_AUTH_MD5_LEN) 983 msglim(use_authp, from, 984 "unknown MD5 RIPv2 auth len %#x" 985 " instead of %#x from %s", 986 NA->au.a_md5.md5_auth_len, 987 RIP_AUTH_MD5_LEN, 988 naddr_ntoa(from)); 989 if (na2->a_family != RIP_AF_AUTH) 990 msglim(use_authp, from, 991 "unknown MD5 RIPv2 family %#x" 992 " instead of %#x from %s", 993 na2->a_family, RIP_AF_AUTH, 994 naddr_ntoa(from)); 995 if (na2->a_type != ntohs(1)) 996 msglim(use_authp, from, 997 "MD5 RIPv2 hash has %#x" 998 " instead of %#x from %s", 999 na2->a_type, ntohs(1), 1000 naddr_ntoa(from)); 1001 } 1002 1003 MD5Init(&md5_ctx); 1004 MD5Update(&md5_ctx, (u_char *)rip, len); 1005 MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_LEN); 1006 MD5Final(hash, &md5_ctx); 1007 if (!memcmp(hash, na2->au.au_pw, sizeof(hash))) 1008 return 1; 1009 } 1010 } 1011 1012 msglim(use_authp, from, "bad password from %s", 1013 naddr_ntoa(from)); 1014 return 0; 1015 #undef NA 1016 } 1017