c4f2d992 |
1 | /* -*-c-*- |
2 | * |
8702965d |
3 | * $Id: daemon.c,v 1.10 1998/04/23 13:23:09 mdw Exp $ |
c4f2d992 |
4 | * |
5 | * Running a `become' daemon |
6 | * |
c758e654 |
7 | * (c) 1998 EBI |
c4f2d992 |
8 | */ |
9 | |
03f996bd |
10 | /*----- Licensing notice --------------------------------------------------* |
c4f2d992 |
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 |
03f996bd |
25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
c4f2d992 |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: daemon.c,v $ |
8702965d |
32 | * Revision 1.10 1998/04/23 13:23:09 mdw |
33 | * Support new interface to configuration file parser. |
34 | * |
c758e654 |
35 | * Revision 1.9 1998/01/12 16:45:59 mdw |
36 | * Fix copyright date. |
37 | * |
9e5602f0 |
38 | * Revision 1.8 1997/09/26 09:14:58 mdw |
39 | * Merged blowfish branch into trunk. |
40 | * |
41 | * Revision 1.7.2.1 1997/09/26 09:08:05 mdw |
42 | * Use the Blowfish encryption algorithm instead of IDEA. This is partly |
43 | * because I prefer Blowfish (without any particularly strong evidence) but |
44 | * mainly because IDEA is patented and Blowfish isn't. |
45 | * |
0c6c5a97 |
46 | * Revision 1.7 1997/09/17 10:23:23 mdw |
47 | * Fix a typo. Port numbers are in network order now, so don't change them. |
48 | * |
f3debbd8 |
49 | * Revision 1.6 1997/09/09 18:17:06 mdw |
50 | * Allow default port to be given as a service name or port number. |
51 | * |
52 | * Revision 1.5 1997/08/20 16:17:10 mdw |
ffdb9474 |
53 | * More sensible restart routine: `_reinit' functions replaced by `_end' and |
54 | * `_init' functions. |
55 | * |
a63eaefc |
56 | * Revision 1.4 1997/08/07 10:00:37 mdw |
57 | * (Log entry for previous version is bogus.) Read netgroups database. |
58 | * Give up privileges permanently on startup. |
607937a4 |
59 | * |
03f996bd |
60 | * Revision 1.2 1997/08/04 10:24:21 mdw |
61 | * Sources placed under CVS control. |
62 | * |
63 | * Revision 1.1 1997/07/21 13:47:50 mdw |
c4f2d992 |
64 | * Initial revision |
65 | * |
66 | */ |
67 | |
68 | /*----- Header files ------------------------------------------------------*/ |
69 | |
70 | /* --- ANSI headers --- */ |
71 | |
72 | #include <errno.h> |
73 | #include <signal.h> |
74 | #include <setjmp.h> |
75 | #include <stdio.h> |
76 | #include <stdlib.h> |
77 | #include <string.h> |
78 | |
79 | /* --- Unix headers --- */ |
80 | |
81 | #include <sys/types.h> |
82 | #include <sys/time.h> |
83 | #include <sys/socket.h> |
84 | |
85 | #include <netinet/in.h> |
86 | |
87 | #include <arpa/inet.h> |
88 | |
89 | #include <netdb.h> |
90 | #include <syslog.h> |
91 | #include <unistd.h> |
92 | |
93 | /* --- Local headers --- */ |
94 | |
95 | #include "become.h" |
9e5602f0 |
96 | #include "blowfish.h" |
c4f2d992 |
97 | #include "config.h" |
98 | #include "crypt.h" |
99 | #include "daemon.h" |
c4f2d992 |
100 | #include "lexer.h" |
101 | #include "name.h" |
607937a4 |
102 | #include "netg.h" |
c4f2d992 |
103 | #include "parser.h" |
104 | #include "rule.h" |
105 | #include "tx.h" |
106 | #include "userdb.h" |
107 | #include "utils.h" |
108 | |
109 | /*----- Arbitrary constants -----------------------------------------------*/ |
110 | |
607937a4 |
111 | #define daemon__awakeEvery (30 * 60) /* Awaken this often to rescan */ |
c4f2d992 |
112 | |
113 | /*----- Static variables --------------------------------------------------*/ |
114 | |
115 | static int daemon__running = 0; /* Am I running as a daemon? */ |
116 | static int daemon__port = -1; /* No particular port yet */ |
117 | static volatile sig_atomic_t daemon__rescan = 0; /* Rescan as soon as poss */ |
118 | #define daemon__signum daemon__rescan /* Alias for readbility */ |
119 | static int daemon__readKey = 0; /* Have I read a key? */ |
9e5602f0 |
120 | static unsigned char daemon__key[BLOWFISH_KEYSIZE]; /* Encryption key */ |
c4f2d992 |
121 | static jmp_buf daemon__dieBuf; /* Jump here to kill the daemon */ |
122 | |
123 | /*----- Main code ---------------------------------------------------------*/ |
124 | |
125 | /* --- @daemon_usePort@ --- * |
126 | * |
127 | * Arguments: @int port@ = port to use, please |
128 | * |
129 | * Returns: --- |
130 | * |
131 | * Use: Instructs the daemon to listen to the given port. |
132 | */ |
133 | |
134 | void daemon_usePort(int port) |
135 | { |
136 | daemon__port = port; |
137 | } |
138 | |
139 | /* --- @daemon_readKey@ --- * |
140 | * |
141 | * Arguments: @const char *kf@ = name of file containing key |
142 | * |
143 | * Returns: --- |
144 | * |
145 | * Use: Instructs the daemon to read the named key file. |
146 | */ |
147 | |
148 | void daemon_readKey(const char *kf) |
149 | { |
150 | FILE *fp; |
151 | |
152 | if (!daemon__running) |
153 | return; |
154 | |
155 | if ((fp = fopen(kf, "r")) == 0) { |
156 | syslog(LOG_WARNING, "couldn't read key file: %e"); |
157 | return; |
158 | } |
159 | tx_getBits(daemon__key, 128, fp); |
160 | fclose(fp); |
161 | daemon__readKey = 1; |
162 | return; |
163 | } |
164 | |
165 | /* --- @daemon__readConfig@ --- * |
166 | * |
167 | * Arguments: @const char *cf@ = pointer to configuration file to use |
168 | * |
169 | * Returns: Zero if it worked, nonzero if it hurt... |
170 | * |
171 | * Use: Reads the configuration file, and other things. |
172 | */ |
173 | |
174 | static int daemon__readConfig(const char *cf) |
175 | { |
176 | FILE *fp; |
177 | |
178 | daemon__readKey = 0; |
179 | if ((fp = fopen(cf, "r")) == 0) |
180 | return (-1); |
181 | lexer_scan(fp); |
8702965d |
182 | parse(); |
c4f2d992 |
183 | fclose(fp); |
184 | if (!daemon__readKey) |
185 | daemon_readKey(file_KEY); |
186 | daemon__rescan = 0; |
03f996bd |
187 | T( trace(TRACE_DAEMON, "daemon: read config file"); ) |
c4f2d992 |
188 | return (0); |
189 | } |
190 | |
191 | /* --- @daemon__restart@ --- * |
192 | * |
193 | * Arguments: @int sig@ = the signal number |
194 | * |
195 | * Returns: --- |
196 | * |
197 | * Use: Handles signals. Causes the configuration file to be reread. |
198 | */ |
199 | |
200 | static void daemon__restart(int sig) |
201 | { |
202 | daemon__rescan = 1; |
203 | signal(sig, daemon__restart); |
204 | } |
205 | |
206 | /* --- @daemon__die@ --- * |
207 | * |
208 | * Arguments: @int sig@ = the signal number |
209 | * |
210 | * Returns: via @longjmp@ |
211 | * |
212 | * Use: Handles other signals. Causes the daemon to die. |
213 | */ |
214 | |
215 | static void daemon__die(int sig) |
216 | { |
217 | daemon__signum = sig; |
218 | longjmp(daemon__dieBuf, 1); |
219 | } |
220 | |
221 | /* --- @daemon__read@ --- * |
222 | * |
223 | * Arguments: @int fd@ = socket handle |
224 | * |
225 | * Returns: --- |
226 | * |
227 | * Use: Examines a buffer, and returns a response. |
228 | */ |
229 | |
230 | void daemon__read(int fd) |
231 | { |
232 | unsigned char buff[65536]; /* Buffer for incoming packets */ |
233 | unsigned char rpl[crp_size]; /* Buffer for outgoing replies */ |
234 | struct sockaddr_in sin; /* Address of packet sender */ |
235 | char sender[64]; /* Sender's hostname (resolved) */ |
9e5602f0 |
236 | unsigned char sk[BLOWFISH_KEYSIZE]; /* Session key for reply */ |
c4f2d992 |
237 | request rq; /* Request buffer for verification */ |
238 | |
239 | /* --- Read the message --- */ |
240 | |
241 | { |
242 | int slen = sizeof(sin); |
243 | |
244 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
245 | (struct sockaddr *)&sin, &slen) < 0) { |
03f996bd |
246 | T( trace(TRACE_DAEMON, "daemon: error reading packet: %s", |
247 | strerror(errno)); ) |
c4f2d992 |
248 | syslog(LOG_INFO, "duff packet received: %e"); |
249 | return; |
250 | } |
251 | } |
252 | |
253 | /* --- Resolve the host name --- */ |
254 | |
255 | { |
256 | struct hostent *he = gethostbyaddr((char *)&sin.sin_addr, |
257 | sizeof(sin.sin_addr), |
258 | AF_INET); |
259 | sender[0] = 0; |
260 | strncat(sender, |
261 | he ? he->h_name : inet_ntoa(sin.sin_addr), |
262 | sizeof(sender)); |
263 | syslog(LOG_DEBUG, "packet received from %s", sender); |
03f996bd |
264 | T( trace(TRACE_DAEMON, "daemon: received request from %s", sender); ) |
c4f2d992 |
265 | } |
266 | |
267 | /* --- Unpack the block --- */ |
268 | |
269 | if (crypt_unpackRequest(&rq, buff, daemon__key, sk, rpl) == 0) { |
270 | burn(buff); |
03f996bd |
271 | T( trace(TRACE_DAEMON, "daemon: received corrupt or invalid request"); ) |
c4f2d992 |
272 | syslog(LOG_INFO, "packet from %s rejected", sender); |
273 | return; |
274 | } |
275 | burn(buff); |
276 | |
277 | /* --- Fill in the sender's address in the request block --- */ |
278 | |
279 | rq.host = sin.sin_addr; |
280 | |
281 | /* --- Build a reply block --- */ |
282 | |
283 | { |
284 | int answer = rule_check(&rq); |
285 | syslog(LOG_INFO, "request from %s for %i to become %i to run %s %s", |
286 | sender, rq.from, rq.to, rq.cmd, answer ? "granted" : "denied"); |
287 | crypt_packReply(rpl, sk, answer); |
288 | burn(sk); |
289 | } |
290 | |
291 | /* --- Send the reply off --- */ |
292 | |
293 | sendto(fd, (char *)rpl, crp_size, 0, (struct sockaddr *)&sin, sizeof(sin)); |
03f996bd |
294 | T( trace(TRACE_DAEMON, "daemon: reply sent"); ) |
c4f2d992 |
295 | burn(rpl); |
296 | } |
297 | |
298 | /* --- @daemon_init@ --- * |
299 | * |
300 | * Arguments: @const char *cf@ = pointer to name of configuration file |
301 | * @int port@ = port to listen to, or %$-1$% for default |
302 | * |
303 | * Returns: Never. |
304 | * |
305 | * Use: Starts `become' up in daemon mode. |
306 | */ |
307 | |
308 | void daemon_init(const char *cf, int port) |
309 | { |
310 | int s; |
311 | |
312 | /* --- Remove my root privileges --- * |
313 | * |
314 | * Just in case there's anything dodgy in my configuration file, or the |
315 | * user wants me to start on a funny port. |
316 | */ |
317 | |
607937a4 |
318 | setuid(getuid()); |
c4f2d992 |
319 | |
320 | /* --- Initialise bits of the program --- */ |
321 | |
322 | daemon__running = 1; |
323 | daemon__port = port; |
324 | userdb_init(); |
325 | userdb_local(); |
326 | userdb_yp(); |
607937a4 |
327 | netg_init(); |
c4f2d992 |
328 | name_init(); |
329 | rule_init(); |
330 | openlog(quis(), 0, LOG_DAEMON); |
331 | syslog(LOG_NOTICE, "starting up"); |
332 | |
333 | if (daemon__readConfig(cf)) |
334 | die("couldn't read configuration file"); |
335 | |
336 | /* --- Decide on a port to use --- * |
337 | * |
338 | * If I don't have a port yet (e.g., from the configuration file) then |
339 | * look it up in /etc/services under whatever name I was started as. |
340 | */ |
341 | |
0c6c5a97 |
342 | if (daemon__port == 0) { |
c4f2d992 |
343 | struct servent *se = getservbyname(quis(), "udp"); |
344 | if (!se) |
9e5602f0 |
345 | die("no idea which port to listen to"); |
f3debbd8 |
346 | daemon__port = se->s_port; |
c4f2d992 |
347 | } |
348 | |
349 | /* --- Now set up a socket --- */ |
350 | |
351 | { |
352 | struct sockaddr_in sin; |
353 | |
354 | if ((s = socket(PF_INET, SOCK_DGRAM, 0)) == -1) |
355 | die("couldn't create socket: %s", strerror(errno)); |
356 | sin.sin_family = AF_INET; |
0c6c5a97 |
357 | sin.sin_port = daemon__port; |
c4f2d992 |
358 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
0c6c5a97 |
359 | if (bind(s, (struct sockaddr *)&sin, sizeof(sin))) { |
360 | die("couldn't bind socket to port %i: %s", |
361 | ntohs(daemon__port), strerror(errno)); |
362 | } |
c4f2d992 |
363 | } |
364 | |
365 | /* --- Fork off into the sunset --- */ |
366 | |
367 | #ifdef NDEBUG |
368 | { |
369 | int pid = fork(); |
370 | FILE *fp; |
371 | |
372 | /* --- Make a background process --- */ |
373 | |
374 | if (pid == -1) |
375 | die("couldn't fork daemon: %s", strerror(errno)); |
376 | else if (pid != 0) |
377 | return; |
378 | |
379 | /* --- Disconnect from the terminal --- */ |
380 | |
381 | setsid(); |
382 | |
383 | /* --- Write my process id to a file --- */ |
384 | |
385 | if ((fp = fopen(file_PID, "w")) != 0) { |
386 | fprintf(fp, "%lu\n", (unsigned long)getpid()); |
387 | fclose(fp); |
388 | } |
03f996bd |
389 | T( trace(TRACE_DAEMON, "daemon: forked to pid %li", (long)getpid()); ) |
c4f2d992 |
390 | } |
391 | #endif |
392 | |
393 | /* --- Program in daemon death mode --- */ |
394 | |
395 | if (setjmp(daemon__dieBuf)) { |
03f996bd |
396 | #ifdef TRACING |
397 | if (daemon__signum == SIGQUIT && tracing() & TRACE_RULE) { |
398 | T( rule_dump(); ) |
399 | signal(SIGQUIT, daemon__die); |
400 | } else |
401 | #endif |
402 | { |
403 | T( trace(TRACE_DAEMON, "daemon: killed by signal %i", |
404 | daemon__signum); ) |
405 | syslog(LOG_NOTICE, "killed by signal type %i", daemon__signum); |
406 | remove(file_PID); |
407 | exit(0); |
408 | } |
409 | } else { |
c4f2d992 |
410 | |
03f996bd |
411 | /* --- Set signal handlers --- */ |
c4f2d992 |
412 | |
03f996bd |
413 | signal(SIGHUP, daemon__restart); |
414 | signal(SIGQUIT, daemon__die); |
415 | signal(SIGINT, daemon__die); |
416 | signal(SIGTERM, daemon__die); |
417 | signal(SIGSEGV, daemon__die); |
418 | signal(SIGFPE, daemon__die); |
419 | signal(SIGBUS, daemon__die); |
420 | } |
c4f2d992 |
421 | |
422 | /* --- Now wait for something exciting to happen --- * |
423 | * |
424 | * Actually, every so often (5 minutes, perhaps) I need to wake up and |
425 | * rescan the users to see whether they've changed. Time to play with |
426 | * @select@. |
427 | */ |
428 | |
429 | { |
430 | time_t when; |
431 | |
432 | /* --- Find when I am, and thus when I need to be awoken again --- */ |
433 | |
434 | when = time(0) + daemon__awakeEvery; |
435 | |
436 | for (;;) { |
437 | fd_set fds; |
438 | int i; |
439 | |
440 | /* --- Set up the file descriptor tables --- */ |
441 | |
442 | FD_ZERO(&fds); |
443 | FD_SET(s, &fds); |
444 | |
445 | /* --- Now wait for something interesting --- */ |
446 | |
03f996bd |
447 | T( trace(TRACE_DAEMON, "daemon: waiting for requests"); ) |
c4f2d992 |
448 | i = select(FD_SETSIZE, &fds, 0, 0, 0); |
449 | |
450 | /* --- Now, see if I need to rescan the config --- */ |
451 | |
452 | if (daemon__rescan || time(0) - when > 0) { |
453 | daemon__rescan = 0; |
454 | syslog(LOG_INFO, "rescanning configuration file"); |
ffdb9474 |
455 | name_end(); |
456 | rule_end(); |
457 | netg_end(); |
458 | userdb_end(); |
459 | userdb_init(); |
c4f2d992 |
460 | userdb_local(); |
461 | userdb_yp(); |
ffdb9474 |
462 | netg_init(); |
463 | rule_init(); |
464 | name_init(); |
c4f2d992 |
465 | if (daemon__readConfig(cf)) |
466 | syslog(LOG_ERR, "error reading configuration file"); |
467 | when = time(0) + daemon__awakeEvery; |
468 | } |
469 | |
470 | /* --- Read the data from the request --- */ |
471 | |
472 | if (i > 0) |
473 | daemon__read(s); |
474 | } |
475 | } |
476 | } |
477 | |
478 | /*----- That's all, folks -------------------------------------------------*/ |