c4f2d992 |
1 | /* -*-c-*- |
2 | * |
c758e654 |
3 | * $Id: check.c,v 1.6 1998/01/12 16:45:47 mdw Exp $ |
c4f2d992 |
4 | * |
5 | * Check validity of requests |
6 | * |
c758e654 |
7 | * (c) 1998 EBI |
c4f2d992 |
8 | */ |
9 | |
03f996bd |
10 | /*----- Licensing notice --------------------------------------------------* |
c4f2d992 |
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 |
03f996bd |
25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
c4f2d992 |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: check.c,v $ |
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32 | * Revision 1.6 1998/01/12 16:45:47 mdw |
33 | * Fix copyright date. |
34 | * |
9e5602f0 |
35 | * Revision 1.5 1997/09/26 09:14:58 mdw |
36 | * Merged blowfish branch into trunk. |
37 | * |
38 | * Revision 1.4.2.1 1997/09/26 09:08:01 mdw |
39 | * Use the Blowfish encryption algorithm instead of IDEA. This is partly |
40 | * because I prefer Blowfish (without any particularly strong evidence) but |
41 | * mainly because IDEA is patented and Blowfish isn't. |
42 | * |
27d7bfc2 |
43 | * Revision 1.4 1997/08/07 09:52:05 mdw |
44 | * (Log entry for previous version is bogus.) Added support for multiple |
45 | * servers. |
607937a4 |
46 | * |
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47 | * Revision 1.2 1997/08/04 10:24:20 mdw |
48 | * Sources placed under CVS control. |
49 | * |
50 | * Revision 1.1 1997/07/21 13:47:53 mdw |
c4f2d992 |
51 | * Initial revision |
52 | * |
53 | */ |
54 | |
55 | /*----- Header files ------------------------------------------------------*/ |
56 | |
57 | /* --- ANSI headers --- */ |
58 | |
59 | #include <ctype.h> |
60 | #include <errno.h> |
61 | #include <stdio.h> |
62 | #include <stdlib.h> |
63 | #include <string.h> |
64 | #include <time.h> |
65 | |
66 | /* --- Unix headers --- */ |
67 | |
68 | #include <sys/time.h> |
69 | #include <sys/types.h> |
70 | #include <sys/socket.h> |
71 | |
72 | #include <netinet/in.h> |
73 | |
74 | #include <arpa/inet.h> |
75 | |
76 | #include <netdb.h> |
77 | #include <unistd.h> |
78 | |
79 | /* --- Local headers --- */ |
80 | |
81 | #include "become.h" |
9e5602f0 |
82 | #include "blowfish.h" |
c4f2d992 |
83 | #include "config.h" |
84 | #include "crypt.h" |
c4f2d992 |
85 | #include "lexer.h" |
86 | #include "name.h" |
607937a4 |
87 | #include "netg.h" |
c4f2d992 |
88 | #include "rule.h" |
89 | #include "parser.h" |
90 | #include "tx.h" |
03f996bd |
91 | #include "userdb.h" |
c4f2d992 |
92 | #include "utils.h" |
93 | |
94 | /*----- Main code ---------------------------------------------------------*/ |
95 | |
03f996bd |
96 | /* --- @check__send@ --- * |
97 | * |
98 | * Arguments: @unsigned char *crq@ = pointer to encrypted request |
99 | * @int fd@ = socket to send from |
100 | * @struct sockaddr_in *serv@ = pointer to table of servers |
101 | * @size_t n_serv@ = number of servers |
102 | * |
103 | * Returns: --- |
104 | * |
105 | * Use: Sends the request packet to the list of servers. If the |
106 | * message couldn't be sent to any of them, an error is |
107 | * reported. |
108 | */ |
109 | |
110 | static void check__send(unsigned char *crq, int fd, |
111 | struct sockaddr_in *serv, size_t n_serv) |
112 | { |
113 | size_t i; |
114 | int ok = 0; |
115 | int err = 0; |
116 | |
117 | for (i = 0; i < n_serv; i++) { |
118 | if (sendto(fd, (char *)crq, crq_size, 0, |
119 | (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) { |
120 | T( trace(TRACE_CLIENT, "client: send to %s failed: %s", |
121 | inet_ntoa(serv[i].sin_addr), strerror(errno)); ) |
122 | err = errno; |
123 | } else |
124 | ok = 1; |
125 | } |
126 | |
127 | if (!ok) |
128 | die("couldn't send request to server: %s", strerror(err)); |
129 | } |
130 | |
131 | /* --- @check__ask@ --- * |
c4f2d992 |
132 | * |
133 | * Arguments: @request *rq@ = pointer to request buffer |
03f996bd |
134 | * @struct sockaddr_in *serv@ = pointer to table of servers |
135 | * @size_t n_serv@ = number of servers |
c4f2d992 |
136 | * |
137 | * Returns: Nonzero if OK, zero if forbidden |
138 | * |
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139 | * Use: Contacts a number of servers to decide whether the request |
140 | * is OK. |
c4f2d992 |
141 | */ |
142 | |
03f996bd |
143 | static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv) |
c4f2d992 |
144 | { |
145 | int fd; |
c4f2d992 |
146 | unsigned char crq[crq_size]; |
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147 | unsigned char sk[BLOWFISH_KEYSIZE]; |
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148 | time_t t; |
149 | pid_t pid; |
150 | |
03f996bd |
151 | /* --- First, build the encrypted request packet --- */ |
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152 | |
03f996bd |
153 | { |
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154 | unsigned char k[BLOWFISH_KEYSIZE]; |
03f996bd |
155 | FILE *fp; |
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156 | |
03f996bd |
157 | /* --- Read in the encryption key --- */ |
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158 | |
03f996bd |
159 | if ((fp = fopen(file_KEY, "r")) == 0) { |
160 | die("couldn't open key file `%s': %s", file_KEY, |
161 | strerror(errno)); |
162 | } |
163 | tx_getBits(k, 128, fp); |
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164 | |
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165 | /* --- Now build a request packet --- */ |
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166 | |
03f996bd |
167 | t = time(0); |
168 | pid = getpid(); |
169 | crypt_packRequest(rq, crq, t, pid, k, sk); |
170 | burn(k); |
171 | T( trace(TRACE_CLIENT, "client: encrypted request packet"); ) |
c4f2d992 |
172 | } |
173 | |
03f996bd |
174 | /* --- Create my socket --- */ |
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175 | |
176 | { |
03f996bd |
177 | struct sockaddr_in sin; |
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178 | |
03f996bd |
179 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
180 | die("couldn't create socket: %s", strerror(errno)); |
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181 | |
03f996bd |
182 | /* --- Bind myself to some address --- */ |
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183 | |
03f996bd |
184 | sin.sin_family = AF_INET; |
185 | sin.sin_port = 0; |
186 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
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187 | |
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188 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
189 | die("couldn't bind socket to address: %s", strerror(errno)); |
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190 | } |
191 | |
03f996bd |
192 | /* --- Now wait for a reply --- */ |
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193 | |
194 | { |
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195 | fd_set fds; |
196 | struct timeval start, now, tv; |
197 | int ind; |
198 | size_t i; |
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199 | |
03f996bd |
200 | /* --- State table for waiting for replies --- * |
201 | * |
202 | * For each number, send off the request to our servers, and wait for |
203 | * that many seconds to have elapsed since we started. If the number is |
204 | * %$-1$% then it's time to give up. |
205 | */ |
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206 | |
03f996bd |
207 | static int tbl[] = { 0, 5, 10, 20, -1 }; |
c4f2d992 |
208 | |
03f996bd |
209 | /* --- Find out when we are --- */ |
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210 | |
03f996bd |
211 | gettimeofday(&start, 0); |
212 | ind = 0; |
c4f2d992 |
213 | |
03f996bd |
214 | /* --- Now loop until everything's done --- */ |
c4f2d992 |
215 | |
216 | for (;;) { |
03f996bd |
217 | gettimeofday(&now, 0); |
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218 | |
03f996bd |
219 | /* --- If the current timer has expired, find one that hasn't --- * |
220 | * |
221 | * Also resend the request after I've found a timer which is still |
222 | * extant. If there aren't any, report an error. |
223 | */ |
224 | |
225 | if (now.tv_sec >= start.tv_sec + tbl[ind] && |
226 | now.tv_usec >= start.tv_usec) { |
227 | do { |
228 | ind++; |
229 | if (tbl[ind] < 0) |
230 | die("no reply from servers"); |
231 | } while (now.tv_sec >= start.tv_sec + tbl[ind] && |
232 | now.tv_usec >= start.tv_usec); |
233 | check__send(crq, fd, serv, n_serv); |
234 | T( trace(TRACE_CLIENT, "client: send request to servers"); ) |
235 | } |
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236 | |
03f996bd |
237 | /* --- Now wait for a packet to arrive --- */ |
238 | |
239 | if (now.tv_usec > start.tv_usec) { |
c4f2d992 |
240 | now.tv_usec -= 1000000; |
241 | now.tv_sec += 1; |
242 | } |
03f996bd |
243 | tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec; |
244 | tv.tv_usec = start.tv_usec - now.tv_usec; |
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245 | |
246 | /* --- Sort out file descriptors to watch --- */ |
247 | |
248 | FD_ZERO(&fds); |
249 | FD_SET(fd, &fds); |
250 | |
251 | /* --- Wait for them --- */ |
252 | |
253 | i = select(FD_SETSIZE, &fds, 0, 0, &tv); |
03f996bd |
254 | if (i == 0 || (i < 0 && errno == EINTR)) |
255 | continue; |
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256 | if (i < 0) |
257 | die("error waiting for reply: %s", strerror(errno)); |
258 | |
259 | /* --- A reply should be waiting now --- */ |
260 | |
261 | { |
262 | struct sockaddr_in sin; |
263 | int slen = sizeof(sin); |
264 | unsigned char buff[256]; |
265 | int answer; |
266 | |
267 | /* --- Read the reply data --- */ |
268 | |
269 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
270 | (struct sockaddr *)&sin, &slen) < 0) |
271 | die("error reading server's reply: %s", strerror(errno)); |
272 | |
03f996bd |
273 | IF_TRACING(TRACE_CLIENT, { |
274 | struct hostent *h = gethostbyaddr((char *)&sin.sin_addr, |
275 | sizeof(sin.sin_addr), AF_INET); |
276 | trace(TRACE_CLIENT, "client: reply received from %s port %i", |
277 | h ? h->h_name : inet_ntoa(sin.sin_addr), |
278 | ntohs(sin.sin_port)); |
279 | }) |
280 | |
281 | /* --- Verify the sender --- * |
282 | * |
283 | * This is more to avoid confusion than for security: an active |
284 | * attacker is quite capable of forging the source address. We rely |
285 | * on the checksum in the reply packet for authentication. |
286 | */ |
287 | |
288 | for (i = 0; i < n_serv; i++) { |
289 | if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr && |
290 | sin.sin_port == serv[i].sin_port) |
291 | break; |
292 | } |
293 | if (i >= n_serv) { |
294 | T( trace(TRACE_CLIENT, "client: reply from unknown host"); ) |
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295 | continue; |
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296 | } |
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297 | |
298 | /* --- Unpack and verify the response --- */ |
299 | |
300 | answer = crypt_unpackReply(buff, sk, t, pid); |
03f996bd |
301 | if (answer < 0) { |
302 | T( trace(TRACE_CLIENT, |
303 | "client: invalid or corrupt reply packet"); ) |
c4f2d992 |
304 | continue; |
03f996bd |
305 | } |
c4f2d992 |
306 | return (answer); |
307 | } |
308 | } |
309 | } |
310 | |
03f996bd |
311 | die("internal error: can't get here in check__ask"); |
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312 | return (0); |
313 | } |
314 | |
03f996bd |
315 | /* --- @check__client@ --- * |
316 | * |
317 | * Arguments: @request *rq@ = pointer to a request block |
318 | * @FILE *fp@ = file containing server configuration |
319 | * |
320 | * Returns: Nonzero if OK, zero if forbidden |
321 | * |
322 | * Use: Asks one or several servers whether a request is acceptable. |
323 | */ |
324 | |
325 | int check__client(request *rq, FILE *fp) |
326 | { |
327 | /* --- Format of the file --- * |
328 | * |
329 | * The `servers' file contains entries of the form |
330 | * |
331 | * %%\syntax{<host> [`:' <port>]}%% |
332 | * |
333 | * separates by whitespace. I build them all into an array of socket |
334 | * addresses and pass the whole lot to another function. |
335 | */ |
336 | |
337 | struct sockaddr_in *serv; /* Array of servers */ |
338 | size_t n_serv, max_serv; /* Number and maximum number */ |
339 | |
340 | /* --- Initialise the server array --- */ |
341 | |
342 | T( trace(TRACE_CLIENT, "client: reading server definitions"); ) |
343 | n_serv = 0; max_serv = 4; /* Four seems reasonable */ |
344 | serv = xmalloc(sizeof(*serv) * max_serv); |
345 | |
346 | /* --- Start reading the file --- */ |
347 | |
348 | { |
349 | char buff[256], *p, *l; /* A buffer and pointers for it */ |
350 | int port; /* Default port for servers */ |
351 | int state; /* Current parser state */ |
352 | struct in_addr t_host; /* Temp place for an address*/ |
353 | int t_port; /* Temp place for a port */ |
354 | int ch; /* The current character */ |
355 | |
356 | /* --- Parser states --- */ |
357 | |
358 | enum { |
359 | st_start, /* Waiting to begin */ |
360 | st_host, /* Reading a new hostname */ |
361 | st_colon, /* Expecting a colon, maybe */ |
362 | st_preport, /* Waiting before reading port */ |
363 | st_port, /* Reading a port number */ |
364 | st_commit, /* Commit a newly read server */ |
365 | st_done /* Finished reading the file */ |
366 | }; |
367 | |
368 | /* --- Find a default port --- */ |
369 | |
370 | { |
371 | struct servent *s = getservbyname(quis(), "udp"); |
372 | port = (s ? s->s_port : -1); |
373 | } |
374 | |
375 | /* --- Initialise for scanning the file --- */ |
376 | |
377 | state = st_host; |
378 | p = buff; |
379 | l = buff + sizeof(buff); |
380 | t_port = port; |
381 | ch = getc(fp); |
382 | |
383 | /* --- Go for it --- */ |
384 | |
385 | while (state != st_done) { |
386 | switch (state) { |
387 | |
388 | /* --- Initial whitespace before hostname --- */ |
389 | |
390 | case st_start: |
391 | if (ch == EOF) |
392 | state = st_done; |
393 | else if (isspace((unsigned char)ch)) |
394 | ch = getc(fp); |
395 | else |
396 | state = st_host; |
397 | break; |
398 | |
399 | /* --- Read a host name --- */ |
400 | |
401 | case st_host: |
402 | if (p == l) |
403 | die("string too long in `" file_SERVER "'"); |
404 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
405 | *p++ = ch; |
406 | ch = getc(fp); |
407 | } else { |
408 | struct hostent *h; |
409 | |
410 | *p++ = 0; |
411 | if ((h = gethostbyname(buff)) == 0) |
412 | die("unknown host `%s' in `" file_SERVER "'", buff); |
413 | memcpy(&t_host, h->h_addr, sizeof(t_host)); |
414 | state = st_colon; |
415 | } |
416 | break; |
417 | |
418 | /* --- Waiting for a colon coming up --- */ |
419 | |
420 | case st_colon: |
421 | if (ch == EOF) |
422 | state = st_commit; |
423 | else if (isspace((unsigned char)ch)) |
424 | ch = getc(fp); |
425 | else if (ch == ':') { |
426 | state = st_preport; |
427 | ch = getc(fp); |
428 | } |
429 | else |
430 | state = st_commit; |
431 | break; |
432 | |
433 | /* --- Clearing whitespace before a port number --- */ |
434 | |
435 | case st_preport: |
436 | if (ch == EOF) |
437 | state = st_commit; |
438 | else if (isspace((unsigned char)ch)) |
439 | ch = getc(fp); |
440 | else { |
441 | state = st_port; |
442 | p = buff; |
443 | } |
444 | break; |
445 | |
446 | /* --- Read a port number --- */ |
447 | |
448 | case st_port: |
449 | if (p == l) |
450 | die("string too long in `" file_SERVER "'"); |
451 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
452 | *p++ = ch; |
453 | ch = getc(fp); |
454 | } else { |
455 | struct servent *s; |
456 | |
457 | *p++ = 0; |
458 | s = getservbyname(buff, "udp"); |
459 | if (!s && isdigit((unsigned char)buff[0])) |
460 | t_port = htons(atoi(buff)); |
461 | else if (!s) |
462 | die("unknown service `%s' in `" file_SERVER "'", buff); |
463 | else |
464 | t_port = s->s_port; |
465 | state = st_commit; |
466 | } |
467 | break; |
468 | |
469 | /* --- A server has been read successfully --- */ |
470 | |
471 | case st_commit: |
472 | if (n_serv == max_serv) { |
473 | max_serv *= 2; |
474 | serv = xrealloc(serv, max_serv * sizeof(*serv)); |
475 | } |
476 | serv[n_serv].sin_family = AF_INET; |
477 | serv[n_serv].sin_addr = t_host; |
478 | serv[n_serv].sin_port = t_port; |
479 | n_serv++; |
480 | state = st_start; |
481 | p = buff; |
482 | t_port = port; |
483 | break; |
484 | |
485 | /* --- A safety net for a broken parser --- */ |
486 | |
487 | default: |
488 | die("internal error: can't get here in check__client"); |
489 | break; |
490 | } |
491 | } |
492 | } |
493 | |
494 | fclose(fp); |
495 | |
496 | /* --- Now start sending requests --- */ |
497 | |
498 | if (!n_serv) |
499 | die("no servers specified in `" file_SERVER "'"); |
500 | |
501 | IF_TRACING(TRACE_CLIENT, { |
502 | size_t i; |
503 | |
504 | for (i = 0; i < n_serv; i++) { |
505 | trace(TRACE_CLIENT, "client: server %s port %i", |
506 | inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port)); |
507 | } |
508 | }) |
509 | return (check__ask(rq, serv, n_serv)); |
510 | } |
511 | |
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512 | /* --- @check@ --- * |
513 | * |
514 | * Arguments: @request *rq@ = pointer to request buffer |
515 | * |
516 | * Returns: Nonzero if OK, zero if forbidden |
517 | * |
518 | * Use: Checks to see if the request is acceptable. |
519 | */ |
520 | |
521 | int check(request *rq) |
522 | { |
523 | FILE *fp; |
524 | |
525 | /* --- Check if we need to talk to a server --- */ |
526 | |
03f996bd |
527 | if ((fp = fopen(file_SERVER, "r")) != 0) |
528 | return (check__client(rq, fp)); |
c4f2d992 |
529 | |
03f996bd |
530 | /* --- Otherwise do this all the old-fashioned way --- */ |
c4f2d992 |
531 | |
532 | if ((fp = fopen(file_RULES, "r")) == 0) { |
533 | die("couldn't read configuration file `%s': %s", |
534 | file_RULES, strerror(errno)); |
535 | } |
536 | |
03f996bd |
537 | userdb_init(); |
538 | userdb_local(); |
539 | userdb_yp(); |
607937a4 |
540 | netg_init(); |
c4f2d992 |
541 | name_init(); |
542 | rule_init(); |
543 | lexer_scan(fp); |
544 | yyparse(); |
545 | |
546 | return (rule_check(rq)); |
547 | } |
548 | |
549 | /*----- That's all, folks -------------------------------------------------*/ |