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