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