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