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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: daemon.c,v 1.11 1999/05/04 16:17:12 mdw Exp $ |
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4 | * |
5 | * Running a `become' daemon |
6 | * |
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7 | * (c) 1998 EBI |
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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 1.11 1999/05/04 16:17:12 mdw |
33 | * Change to header file name for parser. See log for `parse.h' for |
34 | * details. |
35 | * |
36 | * Revision 1.10 1998/04/23 13:23:09 mdw |
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37 | * Support new interface to configuration file parser. |
38 | * |
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39 | * Revision 1.9 1998/01/12 16:45:59 mdw |
40 | * Fix copyright date. |
41 | * |
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42 | * Revision 1.8 1997/09/26 09:14:58 mdw |
43 | * Merged blowfish branch into trunk. |
44 | * |
45 | * Revision 1.7.2.1 1997/09/26 09:08:05 mdw |
46 | * Use the Blowfish encryption algorithm instead of IDEA. This is partly |
47 | * because I prefer Blowfish (without any particularly strong evidence) but |
48 | * mainly because IDEA is patented and Blowfish isn't. |
49 | * |
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50 | * Revision 1.7 1997/09/17 10:23:23 mdw |
51 | * Fix a typo. Port numbers are in network order now, so don't change them. |
52 | * |
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53 | * Revision 1.6 1997/09/09 18:17:06 mdw |
54 | * Allow default port to be given as a service name or port number. |
55 | * |
56 | * Revision 1.5 1997/08/20 16:17:10 mdw |
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57 | * More sensible restart routine: `_reinit' functions replaced by `_end' and |
58 | * `_init' functions. |
59 | * |
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60 | * Revision 1.4 1997/08/07 10:00:37 mdw |
61 | * (Log entry for previous version is bogus.) Read netgroups database. |
62 | * Give up privileges permanently on startup. |
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63 | * |
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64 | * Revision 1.2 1997/08/04 10:24:21 mdw |
65 | * Sources placed under CVS control. |
66 | * |
67 | * Revision 1.1 1997/07/21 13:47:50 mdw |
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68 | * Initial revision |
69 | * |
70 | */ |
71 | |
72 | /*----- Header files ------------------------------------------------------*/ |
73 | |
74 | /* --- ANSI headers --- */ |
75 | |
76 | #include <errno.h> |
77 | #include <signal.h> |
78 | #include <setjmp.h> |
79 | #include <stdio.h> |
80 | #include <stdlib.h> |
81 | #include <string.h> |
82 | |
83 | /* --- Unix headers --- */ |
84 | |
85 | #include <sys/types.h> |
86 | #include <sys/time.h> |
87 | #include <sys/socket.h> |
88 | |
89 | #include <netinet/in.h> |
90 | |
91 | #include <arpa/inet.h> |
92 | |
93 | #include <netdb.h> |
94 | #include <syslog.h> |
95 | #include <unistd.h> |
96 | |
97 | /* --- Local headers --- */ |
98 | |
99 | #include "become.h" |
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100 | #include "blowfish.h" |
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101 | #include "config.h" |
102 | #include "crypt.h" |
103 | #include "daemon.h" |
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104 | #include "lexer.h" |
105 | #include "name.h" |
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106 | #include "netg.h" |
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107 | #include "parse.h" |
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108 | #include "rule.h" |
109 | #include "tx.h" |
110 | #include "userdb.h" |
111 | #include "utils.h" |
112 | |
113 | /*----- Arbitrary constants -----------------------------------------------*/ |
114 | |
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115 | #define daemon__awakeEvery (30 * 60) /* Awaken this often to rescan */ |
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116 | |
117 | /*----- Static variables --------------------------------------------------*/ |
118 | |
119 | static int daemon__running = 0; /* Am I running as a daemon? */ |
120 | static int daemon__port = -1; /* No particular port yet */ |
121 | static volatile sig_atomic_t daemon__rescan = 0; /* Rescan as soon as poss */ |
122 | #define daemon__signum daemon__rescan /* Alias for readbility */ |
123 | static int daemon__readKey = 0; /* Have I read a key? */ |
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124 | static unsigned char daemon__key[BLOWFISH_KEYSIZE]; /* Encryption key */ |
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125 | static jmp_buf daemon__dieBuf; /* Jump here to kill the daemon */ |
126 | |
127 | /*----- Main code ---------------------------------------------------------*/ |
128 | |
129 | /* --- @daemon_usePort@ --- * |
130 | * |
131 | * Arguments: @int port@ = port to use, please |
132 | * |
133 | * Returns: --- |
134 | * |
135 | * Use: Instructs the daemon to listen to the given port. |
136 | */ |
137 | |
138 | void daemon_usePort(int port) |
139 | { |
140 | daemon__port = port; |
141 | } |
142 | |
143 | /* --- @daemon_readKey@ --- * |
144 | * |
145 | * Arguments: @const char *kf@ = name of file containing key |
146 | * |
147 | * Returns: --- |
148 | * |
149 | * Use: Instructs the daemon to read the named key file. |
150 | */ |
151 | |
152 | void daemon_readKey(const char *kf) |
153 | { |
154 | FILE *fp; |
155 | |
156 | if (!daemon__running) |
157 | return; |
158 | |
159 | if ((fp = fopen(kf, "r")) == 0) { |
160 | syslog(LOG_WARNING, "couldn't read key file: %e"); |
161 | return; |
162 | } |
163 | tx_getBits(daemon__key, 128, fp); |
164 | fclose(fp); |
165 | daemon__readKey = 1; |
166 | return; |
167 | } |
168 | |
169 | /* --- @daemon__readConfig@ --- * |
170 | * |
171 | * Arguments: @const char *cf@ = pointer to configuration file to use |
172 | * |
173 | * Returns: Zero if it worked, nonzero if it hurt... |
174 | * |
175 | * Use: Reads the configuration file, and other things. |
176 | */ |
177 | |
178 | static int daemon__readConfig(const char *cf) |
179 | { |
180 | FILE *fp; |
181 | |
182 | daemon__readKey = 0; |
183 | if ((fp = fopen(cf, "r")) == 0) |
184 | return (-1); |
185 | lexer_scan(fp); |
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186 | parse(); |
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187 | fclose(fp); |
188 | if (!daemon__readKey) |
189 | daemon_readKey(file_KEY); |
190 | daemon__rescan = 0; |
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191 | T( trace(TRACE_DAEMON, "daemon: read config file"); ) |
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192 | return (0); |
193 | } |
194 | |
195 | /* --- @daemon__restart@ --- * |
196 | * |
197 | * Arguments: @int sig@ = the signal number |
198 | * |
199 | * Returns: --- |
200 | * |
201 | * Use: Handles signals. Causes the configuration file to be reread. |
202 | */ |
203 | |
204 | static void daemon__restart(int sig) |
205 | { |
206 | daemon__rescan = 1; |
207 | signal(sig, daemon__restart); |
208 | } |
209 | |
210 | /* --- @daemon__die@ --- * |
211 | * |
212 | * Arguments: @int sig@ = the signal number |
213 | * |
214 | * Returns: via @longjmp@ |
215 | * |
216 | * Use: Handles other signals. Causes the daemon to die. |
217 | */ |
218 | |
219 | static void daemon__die(int sig) |
220 | { |
221 | daemon__signum = sig; |
222 | longjmp(daemon__dieBuf, 1); |
223 | } |
224 | |
225 | /* --- @daemon__read@ --- * |
226 | * |
227 | * Arguments: @int fd@ = socket handle |
228 | * |
229 | * Returns: --- |
230 | * |
231 | * Use: Examines a buffer, and returns a response. |
232 | */ |
233 | |
234 | void daemon__read(int fd) |
235 | { |
236 | unsigned char buff[65536]; /* Buffer for incoming packets */ |
237 | unsigned char rpl[crp_size]; /* Buffer for outgoing replies */ |
238 | struct sockaddr_in sin; /* Address of packet sender */ |
239 | char sender[64]; /* Sender's hostname (resolved) */ |
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240 | unsigned char sk[BLOWFISH_KEYSIZE]; /* Session key for reply */ |
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241 | request rq; /* Request buffer for verification */ |
242 | |
243 | /* --- Read the message --- */ |
244 | |
245 | { |
246 | int slen = sizeof(sin); |
247 | |
248 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
249 | (struct sockaddr *)&sin, &slen) < 0) { |
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250 | T( trace(TRACE_DAEMON, "daemon: error reading packet: %s", |
251 | strerror(errno)); ) |
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252 | syslog(LOG_INFO, "duff packet received: %e"); |
253 | return; |
254 | } |
255 | } |
256 | |
257 | /* --- Resolve the host name --- */ |
258 | |
259 | { |
260 | struct hostent *he = gethostbyaddr((char *)&sin.sin_addr, |
261 | sizeof(sin.sin_addr), |
262 | AF_INET); |
263 | sender[0] = 0; |
264 | strncat(sender, |
265 | he ? he->h_name : inet_ntoa(sin.sin_addr), |
266 | sizeof(sender)); |
267 | syslog(LOG_DEBUG, "packet received from %s", sender); |
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268 | T( trace(TRACE_DAEMON, "daemon: received request from %s", sender); ) |
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269 | } |
270 | |
271 | /* --- Unpack the block --- */ |
272 | |
273 | if (crypt_unpackRequest(&rq, buff, daemon__key, sk, rpl) == 0) { |
274 | burn(buff); |
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275 | T( trace(TRACE_DAEMON, "daemon: received corrupt or invalid request"); ) |
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276 | syslog(LOG_INFO, "packet from %s rejected", sender); |
277 | return; |
278 | } |
279 | burn(buff); |
280 | |
281 | /* --- Fill in the sender's address in the request block --- */ |
282 | |
283 | rq.host = sin.sin_addr; |
284 | |
285 | /* --- Build a reply block --- */ |
286 | |
287 | { |
288 | int answer = rule_check(&rq); |
289 | syslog(LOG_INFO, "request from %s for %i to become %i to run %s %s", |
290 | sender, rq.from, rq.to, rq.cmd, answer ? "granted" : "denied"); |
291 | crypt_packReply(rpl, sk, answer); |
292 | burn(sk); |
293 | } |
294 | |
295 | /* --- Send the reply off --- */ |
296 | |
297 | sendto(fd, (char *)rpl, crp_size, 0, (struct sockaddr *)&sin, sizeof(sin)); |
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298 | T( trace(TRACE_DAEMON, "daemon: reply sent"); ) |
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299 | burn(rpl); |
300 | } |
301 | |
302 | /* --- @daemon_init@ --- * |
303 | * |
304 | * Arguments: @const char *cf@ = pointer to name of configuration file |
305 | * @int port@ = port to listen to, or %$-1$% for default |
306 | * |
307 | * Returns: Never. |
308 | * |
309 | * Use: Starts `become' up in daemon mode. |
310 | */ |
311 | |
312 | void daemon_init(const char *cf, int port) |
313 | { |
314 | int s; |
315 | |
316 | /* --- Remove my root privileges --- * |
317 | * |
318 | * Just in case there's anything dodgy in my configuration file, or the |
319 | * user wants me to start on a funny port. |
320 | */ |
321 | |
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322 | setuid(getuid()); |
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323 | |
324 | /* --- Initialise bits of the program --- */ |
325 | |
326 | daemon__running = 1; |
327 | daemon__port = port; |
328 | userdb_init(); |
329 | userdb_local(); |
330 | userdb_yp(); |
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331 | netg_init(); |
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332 | name_init(); |
333 | rule_init(); |
334 | openlog(quis(), 0, LOG_DAEMON); |
335 | syslog(LOG_NOTICE, "starting up"); |
336 | |
337 | if (daemon__readConfig(cf)) |
338 | die("couldn't read configuration file"); |
339 | |
340 | /* --- Decide on a port to use --- * |
341 | * |
342 | * If I don't have a port yet (e.g., from the configuration file) then |
343 | * look it up in /etc/services under whatever name I was started as. |
344 | */ |
345 | |
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346 | if (daemon__port == 0) { |
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347 | struct servent *se = getservbyname(quis(), "udp"); |
348 | if (!se) |
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349 | die("no idea which port to listen to"); |
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350 | daemon__port = se->s_port; |
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351 | } |
352 | |
353 | /* --- Now set up a socket --- */ |
354 | |
355 | { |
356 | struct sockaddr_in sin; |
357 | |
358 | if ((s = socket(PF_INET, SOCK_DGRAM, 0)) == -1) |
359 | die("couldn't create socket: %s", strerror(errno)); |
360 | sin.sin_family = AF_INET; |
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361 | sin.sin_port = daemon__port; |
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362 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
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363 | if (bind(s, (struct sockaddr *)&sin, sizeof(sin))) { |
364 | die("couldn't bind socket to port %i: %s", |
365 | ntohs(daemon__port), strerror(errno)); |
366 | } |
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367 | } |
368 | |
369 | /* --- Fork off into the sunset --- */ |
370 | |
371 | #ifdef NDEBUG |
372 | { |
373 | int pid = fork(); |
374 | FILE *fp; |
375 | |
376 | /* --- Make a background process --- */ |
377 | |
378 | if (pid == -1) |
379 | die("couldn't fork daemon: %s", strerror(errno)); |
380 | else if (pid != 0) |
381 | return; |
382 | |
383 | /* --- Disconnect from the terminal --- */ |
384 | |
385 | setsid(); |
386 | |
387 | /* --- Write my process id to a file --- */ |
388 | |
389 | if ((fp = fopen(file_PID, "w")) != 0) { |
390 | fprintf(fp, "%lu\n", (unsigned long)getpid()); |
391 | fclose(fp); |
392 | } |
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393 | T( trace(TRACE_DAEMON, "daemon: forked to pid %li", (long)getpid()); ) |
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394 | } |
395 | #endif |
396 | |
397 | /* --- Program in daemon death mode --- */ |
398 | |
399 | if (setjmp(daemon__dieBuf)) { |
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400 | #ifdef TRACING |
401 | if (daemon__signum == SIGQUIT && tracing() & TRACE_RULE) { |
402 | T( rule_dump(); ) |
403 | signal(SIGQUIT, daemon__die); |
404 | } else |
405 | #endif |
406 | { |
407 | T( trace(TRACE_DAEMON, "daemon: killed by signal %i", |
408 | daemon__signum); ) |
409 | syslog(LOG_NOTICE, "killed by signal type %i", daemon__signum); |
410 | remove(file_PID); |
411 | exit(0); |
412 | } |
413 | } else { |
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414 | |
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415 | /* --- Set signal handlers --- */ |
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416 | |
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417 | signal(SIGHUP, daemon__restart); |
418 | signal(SIGQUIT, daemon__die); |
419 | signal(SIGINT, daemon__die); |
420 | signal(SIGTERM, daemon__die); |
421 | signal(SIGSEGV, daemon__die); |
422 | signal(SIGFPE, daemon__die); |
423 | signal(SIGBUS, daemon__die); |
424 | } |
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425 | |
426 | /* --- Now wait for something exciting to happen --- * |
427 | * |
428 | * Actually, every so often (5 minutes, perhaps) I need to wake up and |
429 | * rescan the users to see whether they've changed. Time to play with |
430 | * @select@. |
431 | */ |
432 | |
433 | { |
434 | time_t when; |
435 | |
436 | /* --- Find when I am, and thus when I need to be awoken again --- */ |
437 | |
438 | when = time(0) + daemon__awakeEvery; |
439 | |
440 | for (;;) { |
441 | fd_set fds; |
442 | int i; |
443 | |
444 | /* --- Set up the file descriptor tables --- */ |
445 | |
446 | FD_ZERO(&fds); |
447 | FD_SET(s, &fds); |
448 | |
449 | /* --- Now wait for something interesting --- */ |
450 | |
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451 | T( trace(TRACE_DAEMON, "daemon: waiting for requests"); ) |
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452 | i = select(FD_SETSIZE, &fds, 0, 0, 0); |
453 | |
454 | /* --- Now, see if I need to rescan the config --- */ |
455 | |
456 | if (daemon__rescan || time(0) - when > 0) { |
457 | daemon__rescan = 0; |
458 | syslog(LOG_INFO, "rescanning configuration file"); |
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459 | name_end(); |
460 | rule_end(); |
461 | netg_end(); |
462 | userdb_end(); |
463 | userdb_init(); |
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464 | userdb_local(); |
465 | userdb_yp(); |
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466 | netg_init(); |
467 | rule_init(); |
468 | name_init(); |
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469 | if (daemon__readConfig(cf)) |
470 | syslog(LOG_ERR, "error reading configuration file"); |
471 | when = time(0) + daemon__awakeEvery; |
472 | } |
473 | |
474 | /* --- Read the data from the request --- */ |
475 | |
476 | if (i > 0) |
477 | daemon__read(s); |
478 | } |
479 | } |
480 | } |
481 | |
482 | /*----- That's all, folks -------------------------------------------------*/ |