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