3 * $Id: daemon.c,v 1.9 1998/01/12 16:45:59 mdw Exp $
5 * Running a `become' daemon
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of `become'
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.
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.
24 * You should have received a copy of the GNU General Public License
25 * along with `become'; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Revision history --------------------------------------------------*
32 * Revision 1.9 1998/01/12 16:45:59 mdw
35 * Revision 1.8 1997/09/26 09:14:58 mdw
36 * Merged blowfish branch into trunk.
38 * Revision 1.7.2.1 1997/09/26 09:08:05 mdw
39 * Use the Blowfish encryption algorithm instead of IDEA. This is partly
40 * because I prefer Blowfish (without any particularly strong evidence) but
41 * mainly because IDEA is patented and Blowfish isn't.
43 * Revision 1.7 1997/09/17 10:23:23 mdw
44 * Fix a typo. Port numbers are in network order now, so don't change them.
46 * Revision 1.6 1997/09/09 18:17:06 mdw
47 * Allow default port to be given as a service name or port number.
49 * Revision 1.5 1997/08/20 16:17:10 mdw
50 * More sensible restart routine: `_reinit' functions replaced by `_end' and
53 * Revision 1.4 1997/08/07 10:00:37 mdw
54 * (Log entry for previous version is bogus.) Read netgroups database.
55 * Give up privileges permanently on startup.
57 * Revision 1.2 1997/08/04 10:24:21 mdw
58 * Sources placed under CVS control.
60 * Revision 1.1 1997/07/21 13:47:50 mdw
65 /*----- Header files ------------------------------------------------------*/
67 /* --- ANSI headers --- */
76 /* --- Unix headers --- */
78 #include <sys/types.h>
80 #include <sys/socket.h>
82 #include <netinet/in.h>
84 #include <arpa/inet.h>
90 /* --- Local headers --- */
106 /*----- Arbitrary constants -----------------------------------------------*/
108 #define daemon__awakeEvery (30 * 60) /* Awaken this often to rescan */
110 /*----- Static variables --------------------------------------------------*/
112 static int daemon__running
= 0; /* Am I running as a daemon? */
113 static int daemon__port
= -1; /* No particular port yet */
114 static volatile sig_atomic_t daemon__rescan
= 0; /* Rescan as soon as poss */
115 #define daemon__signum daemon__rescan /* Alias for readbility */
116 static int daemon__readKey
= 0; /* Have I read a key? */
117 static unsigned char daemon__key
[BLOWFISH_KEYSIZE
]; /* Encryption key */
118 static jmp_buf daemon__dieBuf
; /* Jump here to kill the daemon */
120 /*----- Main code ---------------------------------------------------------*/
122 /* --- @daemon_usePort@ --- *
124 * Arguments: @int port@ = port to use, please
128 * Use: Instructs the daemon to listen to the given port.
131 void daemon_usePort(int port
)
136 /* --- @daemon_readKey@ --- *
138 * Arguments: @const char *kf@ = name of file containing key
142 * Use: Instructs the daemon to read the named key file.
145 void daemon_readKey(const char *kf
)
149 if (!daemon__running
)
152 if ((fp
= fopen(kf
, "r")) == 0) {
153 syslog(LOG_WARNING
, "couldn't read key file: %e");
156 tx_getBits(daemon__key
, 128, fp
);
162 /* --- @daemon__readConfig@ --- *
164 * Arguments: @const char *cf@ = pointer to configuration file to use
166 * Returns: Zero if it worked, nonzero if it hurt...
168 * Use: Reads the configuration file, and other things.
171 static int daemon__readConfig(const char *cf
)
176 if ((fp
= fopen(cf
, "r")) == 0)
181 if (!daemon__readKey
)
182 daemon_readKey(file_KEY
);
184 T( trace(TRACE_DAEMON
, "daemon: read config file"); )
188 /* --- @daemon__restart@ --- *
190 * Arguments: @int sig@ = the signal number
194 * Use: Handles signals. Causes the configuration file to be reread.
197 static void daemon__restart(int sig
)
200 signal(sig
, daemon__restart
);
203 /* --- @daemon__die@ --- *
205 * Arguments: @int sig@ = the signal number
207 * Returns: via @longjmp@
209 * Use: Handles other signals. Causes the daemon to die.
212 static void daemon__die(int sig
)
214 daemon__signum
= sig
;
215 longjmp(daemon__dieBuf
, 1);
218 /* --- @daemon__read@ --- *
220 * Arguments: @int fd@ = socket handle
224 * Use: Examines a buffer, and returns a response.
227 void daemon__read(int fd
)
229 unsigned char buff
[65536]; /* Buffer for incoming packets */
230 unsigned char rpl
[crp_size
]; /* Buffer for outgoing replies */
231 struct sockaddr_in sin
; /* Address of packet sender */
232 char sender
[64]; /* Sender's hostname (resolved) */
233 unsigned char sk
[BLOWFISH_KEYSIZE
]; /* Session key for reply */
234 request rq
; /* Request buffer for verification */
236 /* --- Read the message --- */
239 int slen
= sizeof(sin
);
241 if (recvfrom(fd
, (char *)buff
, sizeof(buff
), 0,
242 (struct sockaddr
*)&sin
, &slen
) < 0) {
243 T( trace(TRACE_DAEMON
, "daemon: error reading packet: %s",
245 syslog(LOG_INFO
, "duff packet received: %e");
250 /* --- Resolve the host name --- */
253 struct hostent
*he
= gethostbyaddr((char *)&sin
.sin_addr
,
254 sizeof(sin
.sin_addr
),
258 he ? he
->h_name
: inet_ntoa(sin
.sin_addr
),
260 syslog(LOG_DEBUG
, "packet received from %s", sender
);
261 T( trace(TRACE_DAEMON
, "daemon: received request from %s", sender
); )
264 /* --- Unpack the block --- */
266 if (crypt_unpackRequest(&rq
, buff
, daemon__key
, sk
, rpl
) == 0) {
268 T( trace(TRACE_DAEMON
, "daemon: received corrupt or invalid request"); )
269 syslog(LOG_INFO
, "packet from %s rejected", sender
);
274 /* --- Fill in the sender's address in the request block --- */
276 rq
.host
= sin
.sin_addr
;
278 /* --- Build a reply block --- */
281 int answer
= rule_check(&rq
);
282 syslog(LOG_INFO
, "request from %s for %i to become %i to run %s %s",
283 sender
, rq
.from
, rq
.to
, rq
.cmd
, answer ?
"granted" : "denied");
284 crypt_packReply(rpl
, sk
, answer
);
288 /* --- Send the reply off --- */
290 sendto(fd
, (char *)rpl
, crp_size
, 0, (struct sockaddr
*)&sin
, sizeof(sin
));
291 T( trace(TRACE_DAEMON
, "daemon: reply sent"); )
295 /* --- @daemon_init@ --- *
297 * Arguments: @const char *cf@ = pointer to name of configuration file
298 * @int port@ = port to listen to, or %$-1$% for default
302 * Use: Starts `become' up in daemon mode.
305 void daemon_init(const char *cf
, int port
)
309 /* --- Remove my root privileges --- *
311 * Just in case there's anything dodgy in my configuration file, or the
312 * user wants me to start on a funny port.
317 /* --- Initialise bits of the program --- */
327 openlog(quis(), 0, LOG_DAEMON
);
328 syslog(LOG_NOTICE
, "starting up");
330 if (daemon__readConfig(cf
))
331 die("couldn't read configuration file");
333 /* --- Decide on a port to use --- *
335 * If I don't have a port yet (e.g., from the configuration file) then
336 * look it up in /etc/services under whatever name I was started as.
339 if (daemon__port
== 0) {
340 struct servent
*se
= getservbyname(quis(), "udp");
342 die("no idea which port to listen to");
343 daemon__port
= se
->s_port
;
346 /* --- Now set up a socket --- */
349 struct sockaddr_in sin
;
351 if ((s
= socket(PF_INET
, SOCK_DGRAM
, 0)) == -1)
352 die("couldn't create socket: %s", strerror(errno
));
353 sin
.sin_family
= AF_INET
;
354 sin
.sin_port
= daemon__port
;
355 sin
.sin_addr
.s_addr
= htonl(INADDR_ANY
);
356 if (bind(s
, (struct sockaddr
*)&sin
, sizeof(sin
))) {
357 die("couldn't bind socket to port %i: %s",
358 ntohs(daemon__port
), strerror(errno
));
362 /* --- Fork off into the sunset --- */
369 /* --- Make a background process --- */
372 die("couldn't fork daemon: %s", strerror(errno
));
376 /* --- Disconnect from the terminal --- */
380 /* --- Write my process id to a file --- */
382 if ((fp
= fopen(file_PID
, "w")) != 0) {
383 fprintf(fp
, "%lu\n", (unsigned long)getpid());
386 T( trace(TRACE_DAEMON
, "daemon: forked to pid %li", (long)getpid()); )
390 /* --- Program in daemon death mode --- */
392 if (setjmp(daemon__dieBuf
)) {
394 if (daemon__signum
== SIGQUIT
&& tracing() & TRACE_RULE
) {
396 signal(SIGQUIT
, daemon__die
);
400 T( trace(TRACE_DAEMON
, "daemon: killed by signal %i",
402 syslog(LOG_NOTICE
, "killed by signal type %i", daemon__signum
);
408 /* --- Set signal handlers --- */
410 signal(SIGHUP
, daemon__restart
);
411 signal(SIGQUIT
, daemon__die
);
412 signal(SIGINT
, daemon__die
);
413 signal(SIGTERM
, daemon__die
);
414 signal(SIGSEGV
, daemon__die
);
415 signal(SIGFPE
, daemon__die
);
416 signal(SIGBUS
, daemon__die
);
419 /* --- Now wait for something exciting to happen --- *
421 * Actually, every so often (5 minutes, perhaps) I need to wake up and
422 * rescan the users to see whether they've changed. Time to play with
429 /* --- Find when I am, and thus when I need to be awoken again --- */
431 when
= time(0) + daemon__awakeEvery
;
437 /* --- Set up the file descriptor tables --- */
442 /* --- Now wait for something interesting --- */
444 T( trace(TRACE_DAEMON
, "daemon: waiting for requests"); )
445 i
= select(FD_SETSIZE
, &fds
, 0, 0, 0);
447 /* --- Now, see if I need to rescan the config --- */
449 if (daemon__rescan
|| time(0) - when
> 0) {
451 syslog(LOG_INFO
, "rescanning configuration file");
462 if (daemon__readConfig(cf
))
463 syslog(LOG_ERR
, "error reading configuration file");
464 when
= time(0) + daemon__awakeEvery
;
467 /* --- Read the data from the request --- */
475 /*----- That's all, folks -------------------------------------------------*/