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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: daemon.c,v 1.7.2.1 1997/09/26 09:08:05 mdw Exp $ |
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4 | * |
5 | * Running a `become' daemon |
6 | * |
7 | * (c) 1997 EBI |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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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 |
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25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: daemon.c,v $ |
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32 | * Revision 1.7.2.1 1997/09/26 09:08:05 mdw |
33 | * Use the Blowfish encryption algorithm instead of IDEA. This is partly |
34 | * because I prefer Blowfish (without any particularly strong evidence) but |
35 | * mainly because IDEA is patented and Blowfish isn't. |
36 | * |
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37 | * Revision 1.7 1997/09/17 10:23:23 mdw |
38 | * Fix a typo. Port numbers are in network order now, so don't change them. |
39 | * |
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40 | * Revision 1.6 1997/09/09 18:17:06 mdw |
41 | * Allow default port to be given as a service name or port number. |
42 | * |
43 | * Revision 1.5 1997/08/20 16:17:10 mdw |
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44 | * More sensible restart routine: `_reinit' functions replaced by `_end' and |
45 | * `_init' functions. |
46 | * |
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47 | * Revision 1.4 1997/08/07 10:00:37 mdw |
48 | * (Log entry for previous version is bogus.) Read netgroups database. |
49 | * Give up privileges permanently on startup. |
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50 | * |
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51 | * Revision 1.2 1997/08/04 10:24:21 mdw |
52 | * Sources placed under CVS control. |
53 | * |
54 | * Revision 1.1 1997/07/21 13:47:50 mdw |
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55 | * Initial revision |
56 | * |
57 | */ |
58 | |
59 | /*----- Header files ------------------------------------------------------*/ |
60 | |
61 | /* --- ANSI headers --- */ |
62 | |
63 | #include <errno.h> |
64 | #include <signal.h> |
65 | #include <setjmp.h> |
66 | #include <stdio.h> |
67 | #include <stdlib.h> |
68 | #include <string.h> |
69 | |
70 | /* --- Unix headers --- */ |
71 | |
72 | #include <sys/types.h> |
73 | #include <sys/time.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 <syslog.h> |
82 | #include <unistd.h> |
83 | |
84 | /* --- Local headers --- */ |
85 | |
86 | #include "become.h" |
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87 | #include "blowfish.h" |
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88 | #include "config.h" |
89 | #include "crypt.h" |
90 | #include "daemon.h" |
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91 | #include "lexer.h" |
92 | #include "name.h" |
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93 | #include "netg.h" |
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94 | #include "parser.h" |
95 | #include "rule.h" |
96 | #include "tx.h" |
97 | #include "userdb.h" |
98 | #include "utils.h" |
99 | |
100 | /*----- Arbitrary constants -----------------------------------------------*/ |
101 | |
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102 | #define daemon__awakeEvery (30 * 60) /* Awaken this often to rescan */ |
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103 | |
104 | /*----- Static variables --------------------------------------------------*/ |
105 | |
106 | static int daemon__running = 0; /* Am I running as a daemon? */ |
107 | static int daemon__port = -1; /* No particular port yet */ |
108 | static volatile sig_atomic_t daemon__rescan = 0; /* Rescan as soon as poss */ |
109 | #define daemon__signum daemon__rescan /* Alias for readbility */ |
110 | static int daemon__readKey = 0; /* Have I read a key? */ |
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111 | static unsigned char daemon__key[BLOWFISH_KEYSIZE]; /* Encryption key */ |
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112 | static jmp_buf daemon__dieBuf; /* Jump here to kill the daemon */ |
113 | |
114 | /*----- Main code ---------------------------------------------------------*/ |
115 | |
116 | /* --- @daemon_usePort@ --- * |
117 | * |
118 | * Arguments: @int port@ = port to use, please |
119 | * |
120 | * Returns: --- |
121 | * |
122 | * Use: Instructs the daemon to listen to the given port. |
123 | */ |
124 | |
125 | void daemon_usePort(int port) |
126 | { |
127 | daemon__port = port; |
128 | } |
129 | |
130 | /* --- @daemon_readKey@ --- * |
131 | * |
132 | * Arguments: @const char *kf@ = name of file containing key |
133 | * |
134 | * Returns: --- |
135 | * |
136 | * Use: Instructs the daemon to read the named key file. |
137 | */ |
138 | |
139 | void daemon_readKey(const char *kf) |
140 | { |
141 | FILE *fp; |
142 | |
143 | if (!daemon__running) |
144 | return; |
145 | |
146 | if ((fp = fopen(kf, "r")) == 0) { |
147 | syslog(LOG_WARNING, "couldn't read key file: %e"); |
148 | return; |
149 | } |
150 | tx_getBits(daemon__key, 128, fp); |
151 | fclose(fp); |
152 | daemon__readKey = 1; |
153 | return; |
154 | } |
155 | |
156 | /* --- @daemon__readConfig@ --- * |
157 | * |
158 | * Arguments: @const char *cf@ = pointer to configuration file to use |
159 | * |
160 | * Returns: Zero if it worked, nonzero if it hurt... |
161 | * |
162 | * Use: Reads the configuration file, and other things. |
163 | */ |
164 | |
165 | static int daemon__readConfig(const char *cf) |
166 | { |
167 | FILE *fp; |
168 | |
169 | daemon__readKey = 0; |
170 | if ((fp = fopen(cf, "r")) == 0) |
171 | return (-1); |
172 | lexer_scan(fp); |
173 | yyparse(); |
174 | fclose(fp); |
175 | if (!daemon__readKey) |
176 | daemon_readKey(file_KEY); |
177 | daemon__rescan = 0; |
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178 | T( trace(TRACE_DAEMON, "daemon: read config file"); ) |
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179 | return (0); |
180 | } |
181 | |
182 | /* --- @daemon__restart@ --- * |
183 | * |
184 | * Arguments: @int sig@ = the signal number |
185 | * |
186 | * Returns: --- |
187 | * |
188 | * Use: Handles signals. Causes the configuration file to be reread. |
189 | */ |
190 | |
191 | static void daemon__restart(int sig) |
192 | { |
193 | daemon__rescan = 1; |
194 | signal(sig, daemon__restart); |
195 | } |
196 | |
197 | /* --- @daemon__die@ --- * |
198 | * |
199 | * Arguments: @int sig@ = the signal number |
200 | * |
201 | * Returns: via @longjmp@ |
202 | * |
203 | * Use: Handles other signals. Causes the daemon to die. |
204 | */ |
205 | |
206 | static void daemon__die(int sig) |
207 | { |
208 | daemon__signum = sig; |
209 | longjmp(daemon__dieBuf, 1); |
210 | } |
211 | |
212 | /* --- @daemon__read@ --- * |
213 | * |
214 | * Arguments: @int fd@ = socket handle |
215 | * |
216 | * Returns: --- |
217 | * |
218 | * Use: Examines a buffer, and returns a response. |
219 | */ |
220 | |
221 | void daemon__read(int fd) |
222 | { |
223 | unsigned char buff[65536]; /* Buffer for incoming packets */ |
224 | unsigned char rpl[crp_size]; /* Buffer for outgoing replies */ |
225 | struct sockaddr_in sin; /* Address of packet sender */ |
226 | char sender[64]; /* Sender's hostname (resolved) */ |
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227 | unsigned char sk[BLOWFISH_KEYSIZE]; /* Session key for reply */ |
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228 | request rq; /* Request buffer for verification */ |
229 | |
230 | /* --- Read the message --- */ |
231 | |
232 | { |
233 | int slen = sizeof(sin); |
234 | |
235 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
236 | (struct sockaddr *)&sin, &slen) < 0) { |
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237 | T( trace(TRACE_DAEMON, "daemon: error reading packet: %s", |
238 | strerror(errno)); ) |
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239 | syslog(LOG_INFO, "duff packet received: %e"); |
240 | return; |
241 | } |
242 | } |
243 | |
244 | /* --- Resolve the host name --- */ |
245 | |
246 | { |
247 | struct hostent *he = gethostbyaddr((char *)&sin.sin_addr, |
248 | sizeof(sin.sin_addr), |
249 | AF_INET); |
250 | sender[0] = 0; |
251 | strncat(sender, |
252 | he ? he->h_name : inet_ntoa(sin.sin_addr), |
253 | sizeof(sender)); |
254 | syslog(LOG_DEBUG, "packet received from %s", sender); |
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255 | T( trace(TRACE_DAEMON, "daemon: received request from %s", sender); ) |
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256 | } |
257 | |
258 | /* --- Unpack the block --- */ |
259 | |
260 | if (crypt_unpackRequest(&rq, buff, daemon__key, sk, rpl) == 0) { |
261 | burn(buff); |
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262 | T( trace(TRACE_DAEMON, "daemon: received corrupt or invalid request"); ) |
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263 | syslog(LOG_INFO, "packet from %s rejected", sender); |
264 | return; |
265 | } |
266 | burn(buff); |
267 | |
268 | /* --- Fill in the sender's address in the request block --- */ |
269 | |
270 | rq.host = sin.sin_addr; |
271 | |
272 | /* --- Build a reply block --- */ |
273 | |
274 | { |
275 | int answer = rule_check(&rq); |
276 | syslog(LOG_INFO, "request from %s for %i to become %i to run %s %s", |
277 | sender, rq.from, rq.to, rq.cmd, answer ? "granted" : "denied"); |
278 | crypt_packReply(rpl, sk, answer); |
279 | burn(sk); |
280 | } |
281 | |
282 | /* --- Send the reply off --- */ |
283 | |
284 | sendto(fd, (char *)rpl, crp_size, 0, (struct sockaddr *)&sin, sizeof(sin)); |
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285 | T( trace(TRACE_DAEMON, "daemon: reply sent"); ) |
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286 | burn(rpl); |
287 | } |
288 | |
289 | /* --- @daemon_init@ --- * |
290 | * |
291 | * Arguments: @const char *cf@ = pointer to name of configuration file |
292 | * @int port@ = port to listen to, or %$-1$% for default |
293 | * |
294 | * Returns: Never. |
295 | * |
296 | * Use: Starts `become' up in daemon mode. |
297 | */ |
298 | |
299 | void daemon_init(const char *cf, int port) |
300 | { |
301 | int s; |
302 | |
303 | /* --- Remove my root privileges --- * |
304 | * |
305 | * Just in case there's anything dodgy in my configuration file, or the |
306 | * user wants me to start on a funny port. |
307 | */ |
308 | |
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309 | setuid(getuid()); |
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310 | |
311 | /* --- Initialise bits of the program --- */ |
312 | |
313 | daemon__running = 1; |
314 | daemon__port = port; |
315 | userdb_init(); |
316 | userdb_local(); |
317 | userdb_yp(); |
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318 | netg_init(); |
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319 | name_init(); |
320 | rule_init(); |
321 | openlog(quis(), 0, LOG_DAEMON); |
322 | syslog(LOG_NOTICE, "starting up"); |
323 | |
324 | if (daemon__readConfig(cf)) |
325 | die("couldn't read configuration file"); |
326 | |
327 | /* --- Decide on a port to use --- * |
328 | * |
329 | * If I don't have a port yet (e.g., from the configuration file) then |
330 | * look it up in /etc/services under whatever name I was started as. |
331 | */ |
332 | |
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333 | if (daemon__port == 0) { |
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334 | struct servent *se = getservbyname(quis(), "udp"); |
335 | if (!se) |
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336 | die("no idea which port to listen to"); |
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337 | daemon__port = se->s_port; |
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338 | } |
339 | |
340 | /* --- Now set up a socket --- */ |
341 | |
342 | { |
343 | struct sockaddr_in sin; |
344 | |
345 | if ((s = socket(PF_INET, SOCK_DGRAM, 0)) == -1) |
346 | die("couldn't create socket: %s", strerror(errno)); |
347 | sin.sin_family = AF_INET; |
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348 | sin.sin_port = daemon__port; |
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349 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
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350 | if (bind(s, (struct sockaddr *)&sin, sizeof(sin))) { |
351 | die("couldn't bind socket to port %i: %s", |
352 | ntohs(daemon__port), strerror(errno)); |
353 | } |
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354 | } |
355 | |
356 | /* --- Fork off into the sunset --- */ |
357 | |
358 | #ifdef NDEBUG |
359 | { |
360 | int pid = fork(); |
361 | FILE *fp; |
362 | |
363 | /* --- Make a background process --- */ |
364 | |
365 | if (pid == -1) |
366 | die("couldn't fork daemon: %s", strerror(errno)); |
367 | else if (pid != 0) |
368 | return; |
369 | |
370 | /* --- Disconnect from the terminal --- */ |
371 | |
372 | setsid(); |
373 | |
374 | /* --- Write my process id to a file --- */ |
375 | |
376 | if ((fp = fopen(file_PID, "w")) != 0) { |
377 | fprintf(fp, "%lu\n", (unsigned long)getpid()); |
378 | fclose(fp); |
379 | } |
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380 | T( trace(TRACE_DAEMON, "daemon: forked to pid %li", (long)getpid()); ) |
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381 | } |
382 | #endif |
383 | |
384 | /* --- Program in daemon death mode --- */ |
385 | |
386 | if (setjmp(daemon__dieBuf)) { |
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387 | #ifdef TRACING |
388 | if (daemon__signum == SIGQUIT && tracing() & TRACE_RULE) { |
389 | T( rule_dump(); ) |
390 | signal(SIGQUIT, daemon__die); |
391 | } else |
392 | #endif |
393 | { |
394 | T( trace(TRACE_DAEMON, "daemon: killed by signal %i", |
395 | daemon__signum); ) |
396 | syslog(LOG_NOTICE, "killed by signal type %i", daemon__signum); |
397 | remove(file_PID); |
398 | exit(0); |
399 | } |
400 | } else { |
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401 | |
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402 | /* --- Set signal handlers --- */ |
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403 | |
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404 | signal(SIGHUP, daemon__restart); |
405 | signal(SIGQUIT, daemon__die); |
406 | signal(SIGINT, daemon__die); |
407 | signal(SIGTERM, daemon__die); |
408 | signal(SIGSEGV, daemon__die); |
409 | signal(SIGFPE, daemon__die); |
410 | signal(SIGBUS, daemon__die); |
411 | } |
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412 | |
413 | /* --- Now wait for something exciting to happen --- * |
414 | * |
415 | * Actually, every so often (5 minutes, perhaps) I need to wake up and |
416 | * rescan the users to see whether they've changed. Time to play with |
417 | * @select@. |
418 | */ |
419 | |
420 | { |
421 | time_t when; |
422 | |
423 | /* --- Find when I am, and thus when I need to be awoken again --- */ |
424 | |
425 | when = time(0) + daemon__awakeEvery; |
426 | |
427 | for (;;) { |
428 | fd_set fds; |
429 | int i; |
430 | |
431 | /* --- Set up the file descriptor tables --- */ |
432 | |
433 | FD_ZERO(&fds); |
434 | FD_SET(s, &fds); |
435 | |
436 | /* --- Now wait for something interesting --- */ |
437 | |
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438 | T( trace(TRACE_DAEMON, "daemon: waiting for requests"); ) |
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439 | i = select(FD_SETSIZE, &fds, 0, 0, 0); |
440 | |
441 | /* --- Now, see if I need to rescan the config --- */ |
442 | |
443 | if (daemon__rescan || time(0) - when > 0) { |
444 | daemon__rescan = 0; |
445 | syslog(LOG_INFO, "rescanning configuration file"); |
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446 | name_end(); |
447 | rule_end(); |
448 | netg_end(); |
449 | userdb_end(); |
450 | userdb_init(); |
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451 | userdb_local(); |
452 | userdb_yp(); |
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453 | netg_init(); |
454 | rule_init(); |
455 | name_init(); |
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456 | if (daemon__readConfig(cf)) |
457 | syslog(LOG_ERR, "error reading configuration file"); |
458 | when = time(0) + daemon__awakeEvery; |
459 | } |
460 | |
461 | /* --- Read the data from the request --- */ |
462 | |
463 | if (i > 0) |
464 | daemon__read(s); |
465 | } |
466 | } |
467 | } |
468 | |
469 | /*----- That's all, folks -------------------------------------------------*/ |