| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: check.c,v 1.7 1998/04/23 13:22:08 mdw Exp $ |
| 4 | * |
| 5 | * Check validity of requests |
| 6 | * |
| 7 | * (c) 1998 EBI |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of `become' |
| 13 | * |
| 14 | * `Become' is free software; you can redistribute it and/or modify |
| 15 | * it under the terms of the GNU General Public License as published by |
| 16 | * the Free Software Foundation; either version 2 of the License, or |
| 17 | * (at your option) any later version. |
| 18 | * |
| 19 | * `Become' is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | * GNU General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU General Public License |
| 25 | * along with `become'; if not, write to the Free Software Foundation, |
| 26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 27 | */ |
| 28 | |
| 29 | /*----- Revision history --------------------------------------------------* |
| 30 | * |
| 31 | * $Log: check.c,v $ |
| 32 | * Revision 1.7 1998/04/23 13:22:08 mdw |
| 33 | * Support no-network configuration option, and new interface to |
| 34 | * configuration file parser. |
| 35 | * |
| 36 | * Revision 1.6 1998/01/12 16:45:47 mdw |
| 37 | * Fix copyright date. |
| 38 | * |
| 39 | * Revision 1.5 1997/09/26 09:14:58 mdw |
| 40 | * Merged blowfish branch into trunk. |
| 41 | * |
| 42 | * Revision 1.4.2.1 1997/09/26 09:08:01 mdw |
| 43 | * Use the Blowfish encryption algorithm instead of IDEA. This is partly |
| 44 | * because I prefer Blowfish (without any particularly strong evidence) but |
| 45 | * mainly because IDEA is patented and Blowfish isn't. |
| 46 | * |
| 47 | * Revision 1.4 1997/08/07 09:52:05 mdw |
| 48 | * (Log entry for previous version is bogus.) Added support for multiple |
| 49 | * servers. |
| 50 | * |
| 51 | * Revision 1.2 1997/08/04 10:24:20 mdw |
| 52 | * Sources placed under CVS control. |
| 53 | * |
| 54 | * Revision 1.1 1997/07/21 13:47:53 mdw |
| 55 | * Initial revision |
| 56 | * |
| 57 | */ |
| 58 | |
| 59 | /*----- Header files ------------------------------------------------------*/ |
| 60 | |
| 61 | /* --- ANSI headers --- */ |
| 62 | |
| 63 | #include <ctype.h> |
| 64 | #include <errno.h> |
| 65 | #include <stdio.h> |
| 66 | #include <stdlib.h> |
| 67 | #include <string.h> |
| 68 | #include <time.h> |
| 69 | |
| 70 | /* --- Unix headers --- */ |
| 71 | |
| 72 | #include <sys/time.h> |
| 73 | #include <sys/types.h> |
| 74 | #include <sys/socket.h> |
| 75 | |
| 76 | #include <netinet/in.h> |
| 77 | |
| 78 | #include <arpa/inet.h> |
| 79 | |
| 80 | #include <netdb.h> |
| 81 | #include <unistd.h> |
| 82 | |
| 83 | /* --- Local headers --- */ |
| 84 | |
| 85 | #include "become.h" |
| 86 | #include "blowfish.h" |
| 87 | #include "config.h" |
| 88 | #include "crypt.h" |
| 89 | #include "lexer.h" |
| 90 | #include "name.h" |
| 91 | #include "netg.h" |
| 92 | #include "rule.h" |
| 93 | #include "parser.h" |
| 94 | #include "tx.h" |
| 95 | #include "userdb.h" |
| 96 | #include "utils.h" |
| 97 | |
| 98 | /*----- Client-end network support ----------------------------------------*/ |
| 99 | |
| 100 | #ifndef NONETWORK |
| 101 | |
| 102 | /* --- @check__send@ --- * |
| 103 | * |
| 104 | * Arguments: @unsigned char *crq@ = pointer to encrypted request |
| 105 | * @int fd@ = socket to send from |
| 106 | * @struct sockaddr_in *serv@ = pointer to table of servers |
| 107 | * @size_t n_serv@ = number of servers |
| 108 | * |
| 109 | * Returns: --- |
| 110 | * |
| 111 | * Use: Sends the request packet to the list of servers. If the |
| 112 | * message couldn't be sent to any of them, an error is |
| 113 | * reported. |
| 114 | */ |
| 115 | |
| 116 | static void check__send(unsigned char *crq, int fd, |
| 117 | struct sockaddr_in *serv, size_t n_serv) |
| 118 | { |
| 119 | size_t i; |
| 120 | int ok = 0; |
| 121 | int err = 0; |
| 122 | |
| 123 | for (i = 0; i < n_serv; i++) { |
| 124 | if (sendto(fd, (char *)crq, crq_size, 0, |
| 125 | (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) { |
| 126 | T( trace(TRACE_CLIENT, "client: send to %s failed: %s", |
| 127 | inet_ntoa(serv[i].sin_addr), strerror(errno)); ) |
| 128 | err = errno; |
| 129 | } else |
| 130 | ok = 1; |
| 131 | } |
| 132 | |
| 133 | if (!ok) |
| 134 | die("couldn't send request to server: %s", strerror(err)); |
| 135 | } |
| 136 | |
| 137 | /* --- @check__ask@ --- * |
| 138 | * |
| 139 | * Arguments: @request *rq@ = pointer to request buffer |
| 140 | * @struct sockaddr_in *serv@ = pointer to table of servers |
| 141 | * @size_t n_serv@ = number of servers |
| 142 | * |
| 143 | * Returns: Nonzero if OK, zero if forbidden |
| 144 | * |
| 145 | * Use: Contacts a number of servers to decide whether the request |
| 146 | * is OK. |
| 147 | */ |
| 148 | |
| 149 | static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv) |
| 150 | { |
| 151 | int fd; |
| 152 | unsigned char crq[crq_size]; |
| 153 | unsigned char sk[BLOWFISH_KEYSIZE]; |
| 154 | time_t t; |
| 155 | pid_t pid; |
| 156 | |
| 157 | /* --- First, build the encrypted request packet --- */ |
| 158 | |
| 159 | { |
| 160 | unsigned char k[BLOWFISH_KEYSIZE]; |
| 161 | FILE *fp; |
| 162 | |
| 163 | /* --- Read in the encryption key --- */ |
| 164 | |
| 165 | if ((fp = fopen(file_KEY, "r")) == 0) { |
| 166 | die("couldn't open key file `%s': %s", file_KEY, |
| 167 | strerror(errno)); |
| 168 | } |
| 169 | tx_getBits(k, 128, fp); |
| 170 | |
| 171 | /* --- Now build a request packet --- */ |
| 172 | |
| 173 | t = time(0); |
| 174 | pid = getpid(); |
| 175 | crypt_packRequest(rq, crq, t, pid, k, sk); |
| 176 | burn(k); |
| 177 | T( trace(TRACE_CLIENT, "client: encrypted request packet"); ) |
| 178 | } |
| 179 | |
| 180 | /* --- Create my socket --- */ |
| 181 | |
| 182 | { |
| 183 | struct sockaddr_in sin; |
| 184 | |
| 185 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
| 186 | die("couldn't create socket: %s", strerror(errno)); |
| 187 | |
| 188 | /* --- Bind myself to some address --- */ |
| 189 | |
| 190 | sin.sin_family = AF_INET; |
| 191 | sin.sin_port = 0; |
| 192 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
| 193 | |
| 194 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
| 195 | die("couldn't bind socket to address: %s", strerror(errno)); |
| 196 | } |
| 197 | |
| 198 | /* --- Now wait for a reply --- */ |
| 199 | |
| 200 | { |
| 201 | fd_set fds; |
| 202 | struct timeval start, now, tv; |
| 203 | int ind; |
| 204 | size_t i; |
| 205 | |
| 206 | /* --- State table for waiting for replies --- * |
| 207 | * |
| 208 | * For each number, send off the request to our servers, and wait for |
| 209 | * that many seconds to have elapsed since we started. If the number is |
| 210 | * %$-1$% then it's time to give up. |
| 211 | */ |
| 212 | |
| 213 | static int tbl[] = { 0, 5, 10, 20, -1 }; |
| 214 | |
| 215 | /* --- Find out when we are --- */ |
| 216 | |
| 217 | gettimeofday(&start, 0); |
| 218 | ind = 0; |
| 219 | |
| 220 | /* --- Now loop until everything's done --- */ |
| 221 | |
| 222 | for (;;) { |
| 223 | gettimeofday(&now, 0); |
| 224 | |
| 225 | /* --- If the current timer has expired, find one that hasn't --- * |
| 226 | * |
| 227 | * Also resend the request after I've found a timer which is still |
| 228 | * extant. If there aren't any, report an error. |
| 229 | */ |
| 230 | |
| 231 | if (now.tv_sec >= start.tv_sec + tbl[ind] && |
| 232 | now.tv_usec >= start.tv_usec) { |
| 233 | do { |
| 234 | ind++; |
| 235 | if (tbl[ind] < 0) |
| 236 | die("no reply from servers"); |
| 237 | } while (now.tv_sec >= start.tv_sec + tbl[ind] && |
| 238 | now.tv_usec >= start.tv_usec); |
| 239 | check__send(crq, fd, serv, n_serv); |
| 240 | T( trace(TRACE_CLIENT, "client: send request to servers"); ) |
| 241 | } |
| 242 | |
| 243 | /* --- Now wait for a packet to arrive --- */ |
| 244 | |
| 245 | if (now.tv_usec > start.tv_usec) { |
| 246 | now.tv_usec -= 1000000; |
| 247 | now.tv_sec += 1; |
| 248 | } |
| 249 | tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec; |
| 250 | tv.tv_usec = start.tv_usec - now.tv_usec; |
| 251 | |
| 252 | /* --- Sort out file descriptors to watch --- */ |
| 253 | |
| 254 | FD_ZERO(&fds); |
| 255 | FD_SET(fd, &fds); |
| 256 | |
| 257 | /* --- Wait for them --- */ |
| 258 | |
| 259 | i = select(FD_SETSIZE, &fds, 0, 0, &tv); |
| 260 | if (i == 0 || (i < 0 && errno == EINTR)) |
| 261 | continue; |
| 262 | if (i < 0) |
| 263 | die("error waiting for reply: %s", strerror(errno)); |
| 264 | |
| 265 | /* --- A reply should be waiting now --- */ |
| 266 | |
| 267 | { |
| 268 | struct sockaddr_in sin; |
| 269 | int slen = sizeof(sin); |
| 270 | unsigned char buff[256]; |
| 271 | int answer; |
| 272 | |
| 273 | /* --- Read the reply data --- */ |
| 274 | |
| 275 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
| 276 | (struct sockaddr *)&sin, &slen) < 0) |
| 277 | die("error reading server's reply: %s", strerror(errno)); |
| 278 | |
| 279 | IF_TRACING(TRACE_CLIENT, { |
| 280 | struct hostent *h = gethostbyaddr((char *)&sin.sin_addr, |
| 281 | sizeof(sin.sin_addr), AF_INET); |
| 282 | trace(TRACE_CLIENT, "client: reply received from %s port %i", |
| 283 | h ? h->h_name : inet_ntoa(sin.sin_addr), |
| 284 | ntohs(sin.sin_port)); |
| 285 | }) |
| 286 | |
| 287 | /* --- Verify the sender --- * |
| 288 | * |
| 289 | * This is more to avoid confusion than for security: an active |
| 290 | * attacker is quite capable of forging the source address. We rely |
| 291 | * on the checksum in the reply packet for authentication. |
| 292 | */ |
| 293 | |
| 294 | for (i = 0; i < n_serv; i++) { |
| 295 | if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr && |
| 296 | sin.sin_port == serv[i].sin_port) |
| 297 | break; |
| 298 | } |
| 299 | if (i >= n_serv) { |
| 300 | T( trace(TRACE_CLIENT, "client: reply from unknown host"); ) |
| 301 | continue; |
| 302 | } |
| 303 | |
| 304 | /* --- Unpack and verify the response --- */ |
| 305 | |
| 306 | answer = crypt_unpackReply(buff, sk, t, pid); |
| 307 | if (answer < 0) { |
| 308 | T( trace(TRACE_CLIENT, |
| 309 | "client: invalid or corrupt reply packet"); ) |
| 310 | continue; |
| 311 | } |
| 312 | return (answer); |
| 313 | } |
| 314 | } |
| 315 | } |
| 316 | |
| 317 | die("internal error: can't get here in check__ask"); |
| 318 | return (0); |
| 319 | } |
| 320 | |
| 321 | /* --- @check__client@ --- * |
| 322 | * |
| 323 | * Arguments: @request *rq@ = pointer to a request block |
| 324 | * @FILE *fp@ = file containing server configuration |
| 325 | * |
| 326 | * Returns: Nonzero if OK, zero if forbidden |
| 327 | * |
| 328 | * Use: Asks one or several servers whether a request is acceptable. |
| 329 | */ |
| 330 | |
| 331 | int check__client(request *rq, FILE *fp) |
| 332 | { |
| 333 | /* --- Format of the file --- * |
| 334 | * |
| 335 | * The `servers' file contains entries of the form |
| 336 | * |
| 337 | * %%\syntax{<host> [`:' <port>]}%% |
| 338 | * |
| 339 | * separates by whitespace. I build them all into an array of socket |
| 340 | * addresses and pass the whole lot to another function. |
| 341 | */ |
| 342 | |
| 343 | struct sockaddr_in *serv; /* Array of servers */ |
| 344 | size_t n_serv, max_serv; /* Number and maximum number */ |
| 345 | |
| 346 | /* --- Initialise the server array --- */ |
| 347 | |
| 348 | T( trace(TRACE_CLIENT, "client: reading server definitions"); ) |
| 349 | n_serv = 0; max_serv = 4; /* Four seems reasonable */ |
| 350 | serv = xmalloc(sizeof(*serv) * max_serv); |
| 351 | |
| 352 | /* --- Start reading the file --- */ |
| 353 | |
| 354 | { |
| 355 | char buff[256], *p, *l; /* A buffer and pointers for it */ |
| 356 | int port; /* Default port for servers */ |
| 357 | int state; /* Current parser state */ |
| 358 | struct in_addr t_host; /* Temp place for an address*/ |
| 359 | int t_port; /* Temp place for a port */ |
| 360 | int ch; /* The current character */ |
| 361 | |
| 362 | /* --- Parser states --- */ |
| 363 | |
| 364 | enum { |
| 365 | st_start, /* Waiting to begin */ |
| 366 | st_host, /* Reading a new hostname */ |
| 367 | st_colon, /* Expecting a colon, maybe */ |
| 368 | st_preport, /* Waiting before reading port */ |
| 369 | st_port, /* Reading a port number */ |
| 370 | st_commit, /* Commit a newly read server */ |
| 371 | st_done /* Finished reading the file */ |
| 372 | }; |
| 373 | |
| 374 | /* --- Find a default port --- */ |
| 375 | |
| 376 | { |
| 377 | struct servent *s = getservbyname(quis(), "udp"); |
| 378 | port = (s ? s->s_port : -1); |
| 379 | } |
| 380 | |
| 381 | /* --- Initialise for scanning the file --- */ |
| 382 | |
| 383 | state = st_host; |
| 384 | p = buff; |
| 385 | l = buff + sizeof(buff); |
| 386 | t_port = port; |
| 387 | ch = getc(fp); |
| 388 | |
| 389 | /* --- Go for it --- */ |
| 390 | |
| 391 | while (state != st_done) { |
| 392 | switch (state) { |
| 393 | |
| 394 | /* --- Initial whitespace before hostname --- */ |
| 395 | |
| 396 | case st_start: |
| 397 | if (ch == EOF) |
| 398 | state = st_done; |
| 399 | else if (isspace((unsigned char)ch)) |
| 400 | ch = getc(fp); |
| 401 | else |
| 402 | state = st_host; |
| 403 | break; |
| 404 | |
| 405 | /* --- Read a host name --- */ |
| 406 | |
| 407 | case st_host: |
| 408 | if (p == l) |
| 409 | die("string too long in `" file_SERVER "'"); |
| 410 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
| 411 | *p++ = ch; |
| 412 | ch = getc(fp); |
| 413 | } else { |
| 414 | struct hostent *h; |
| 415 | |
| 416 | *p++ = 0; |
| 417 | if ((h = gethostbyname(buff)) == 0) |
| 418 | die("unknown host `%s' in `" file_SERVER "'", buff); |
| 419 | memcpy(&t_host, h->h_addr, sizeof(t_host)); |
| 420 | state = st_colon; |
| 421 | } |
| 422 | break; |
| 423 | |
| 424 | /* --- Waiting for a colon coming up --- */ |
| 425 | |
| 426 | case st_colon: |
| 427 | if (ch == EOF) |
| 428 | state = st_commit; |
| 429 | else if (isspace((unsigned char)ch)) |
| 430 | ch = getc(fp); |
| 431 | else if (ch == ':') { |
| 432 | state = st_preport; |
| 433 | ch = getc(fp); |
| 434 | } |
| 435 | else |
| 436 | state = st_commit; |
| 437 | break; |
| 438 | |
| 439 | /* --- Clearing whitespace before a port number --- */ |
| 440 | |
| 441 | case st_preport: |
| 442 | if (ch == EOF) |
| 443 | state = st_commit; |
| 444 | else if (isspace((unsigned char)ch)) |
| 445 | ch = getc(fp); |
| 446 | else { |
| 447 | state = st_port; |
| 448 | p = buff; |
| 449 | } |
| 450 | break; |
| 451 | |
| 452 | /* --- Read a port number --- */ |
| 453 | |
| 454 | case st_port: |
| 455 | if (p == l) |
| 456 | die("string too long in `" file_SERVER "'"); |
| 457 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
| 458 | *p++ = ch; |
| 459 | ch = getc(fp); |
| 460 | } else { |
| 461 | struct servent *s; |
| 462 | |
| 463 | *p++ = 0; |
| 464 | s = getservbyname(buff, "udp"); |
| 465 | if (!s && isdigit((unsigned char)buff[0])) |
| 466 | t_port = htons(atoi(buff)); |
| 467 | else if (!s) |
| 468 | die("unknown service `%s' in `" file_SERVER "'", buff); |
| 469 | else |
| 470 | t_port = s->s_port; |
| 471 | state = st_commit; |
| 472 | } |
| 473 | break; |
| 474 | |
| 475 | /* --- A server has been read successfully --- */ |
| 476 | |
| 477 | case st_commit: |
| 478 | if (n_serv == max_serv) { |
| 479 | max_serv *= 2; |
| 480 | serv = xrealloc(serv, max_serv * sizeof(*serv)); |
| 481 | } |
| 482 | serv[n_serv].sin_family = AF_INET; |
| 483 | serv[n_serv].sin_addr = t_host; |
| 484 | serv[n_serv].sin_port = t_port; |
| 485 | n_serv++; |
| 486 | state = st_start; |
| 487 | p = buff; |
| 488 | t_port = port; |
| 489 | break; |
| 490 | |
| 491 | /* --- A safety net for a broken parser --- */ |
| 492 | |
| 493 | default: |
| 494 | die("internal error: can't get here in check__client"); |
| 495 | break; |
| 496 | } |
| 497 | } |
| 498 | } |
| 499 | |
| 500 | fclose(fp); |
| 501 | |
| 502 | /* --- Now start sending requests --- */ |
| 503 | |
| 504 | if (!n_serv) |
| 505 | die("no servers specified in `" file_SERVER "'"); |
| 506 | |
| 507 | IF_TRACING(TRACE_CLIENT, { |
| 508 | size_t i; |
| 509 | |
| 510 | for (i = 0; i < n_serv; i++) { |
| 511 | trace(TRACE_CLIENT, "client: server %s port %i", |
| 512 | inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port)); |
| 513 | } |
| 514 | }) |
| 515 | return (check__ask(rq, serv, n_serv)); |
| 516 | } |
| 517 | |
| 518 | #endif |
| 519 | |
| 520 | /*----- Main checking function --------------------------------------------*/ |
| 521 | |
| 522 | /* --- @check@ --- * |
| 523 | * |
| 524 | * Arguments: @request *rq@ = pointer to request buffer |
| 525 | * |
| 526 | * Returns: Nonzero if OK, zero if forbidden |
| 527 | * |
| 528 | * Use: Checks to see if the request is acceptable. |
| 529 | */ |
| 530 | |
| 531 | int check(request *rq) |
| 532 | { |
| 533 | FILE *fp; |
| 534 | |
| 535 | /* --- Check if we need to talk to a server --- */ |
| 536 | |
| 537 | #ifndef NONETWORK |
| 538 | if ((fp = fopen(file_SERVER, "r")) != 0) |
| 539 | return (check__client(rq, fp)); |
| 540 | #endif |
| 541 | |
| 542 | /* --- Otherwise do this all the old-fashioned way --- */ |
| 543 | |
| 544 | if ((fp = fopen(file_RULES, "r")) == 0) { |
| 545 | die("couldn't read configuration file `%s': %s", |
| 546 | file_RULES, strerror(errno)); |
| 547 | } |
| 548 | |
| 549 | userdb_init(); |
| 550 | userdb_local(); |
| 551 | userdb_yp(); |
| 552 | netg_init(); |
| 553 | name_init(); |
| 554 | rule_init(); |
| 555 | lexer_scan(fp); |
| 556 | parse(); |
| 557 | |
| 558 | return (rule_check(rq)); |
| 559 | } |
| 560 | |
| 561 | /*----- That's all, folks -------------------------------------------------*/ |