3 * $Id: daemon.c,v 1.2 1997/08/04 10:24:21 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 1.2 1997/08/04 10:24:21 mdw
33 * Sources placed under CVS control.
35 * Revision 1.1 1997/07/21 13:47:50 mdw
40 /*----- Header files ------------------------------------------------------*/
42 /* --- ANSI headers --- */
51 /* --- Unix headers --- */
53 #include <sys/types.h>
55 #include <sys/socket.h>
57 #include <netinet/in.h>
59 #include <arpa/inet.h>
65 /* --- Local headers --- */
80 /*----- Arbitrary constants -----------------------------------------------*/
82 #define daemon__awakeEvery (5 * 60) /* Awaken this often to rescan */
84 /*----- Static variables --------------------------------------------------*/
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 */
94 /*----- Main code ---------------------------------------------------------*/
96 /* --- @daemon_usePort@ --- *
98 * Arguments: @int port@ = port to use, please
102 * Use: Instructs the daemon to listen to the given port.
105 void daemon_usePort(int port)
110 /* --- @daemon_readKey@ --- *
112 * Arguments: @const char *kf@ = name of file containing key
116 * Use: Instructs the daemon to read the named key file.
119 void daemon_readKey(const char *kf)
123 if (!daemon__running)
126 if ((fp = fopen(kf, "r")) == 0) {
127 syslog(LOG_WARNING, "couldn't read key file: %e");
130 tx_getBits(daemon__key, 128, fp);
136 /* --- @daemon__readConfig@ --- *
138 * Arguments: @const char *cf@ = pointer to configuration file to use
140 * Returns: Zero if it worked, nonzero if it hurt...
142 * Use: Reads the configuration file, and other things.
145 static int daemon__readConfig(const char *cf)
150 if ((fp = fopen(cf, "r")) == 0)
155 if (!daemon__readKey)
156 daemon_readKey(file_KEY);
158 T( trace(TRACE_DAEMON, "daemon: read config file"); )
162 /* --- @daemon__restart@ --- *
164 * Arguments: @int sig@ = the signal number
168 * Use: Handles signals. Causes the configuration file to be reread.
171 static void daemon__restart(int sig)
174 signal(sig, daemon__restart);
177 /* --- @daemon__die@ --- *
179 * Arguments: @int sig@ = the signal number
181 * Returns: via @longjmp@
183 * Use: Handles other signals. Causes the daemon to die.
186 static void daemon__die(int sig)
188 daemon__signum = sig;
189 longjmp(daemon__dieBuf, 1);
192 /* --- @daemon__read@ --- *
194 * Arguments: @int fd@ = socket handle
198 * Use: Examines a buffer, and returns a response.
201 void daemon__read(int fd)
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 */
210 /* --- Read the message --- */
213 int slen = sizeof(sin);
215 if (recvfrom(fd, (char *)buff, sizeof(buff), 0,
216 (struct sockaddr *)&sin, &slen) < 0) {
217 T( trace(TRACE_DAEMON, "daemon: error reading packet: %s",
219 syslog(LOG_INFO, "duff packet received: %e");
224 /* --- Resolve the host name --- */
227 struct hostent *he = gethostbyaddr((char *)&sin.sin_addr,
228 sizeof(sin.sin_addr),
232 he ? he->h_name : inet_ntoa(sin.sin_addr),
234 syslog(LOG_DEBUG, "packet received from %s", sender);
235 T( trace(TRACE_DAEMON, "daemon: received request from %s", sender); )
238 /* --- Unpack the block --- */
240 if (crypt_unpackRequest(&rq, buff, daemon__key, sk, rpl) == 0) {
242 T( trace(TRACE_DAEMON, "daemon: received corrupt or invalid request"); )
243 syslog(LOG_INFO, "packet from %s rejected", sender);
248 /* --- Fill in the sender's address in the request block --- */
250 rq.host = sin.sin_addr;
252 /* --- Build a reply block --- */
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);
262 /* --- Send the reply off --- */
264 sendto(fd, (char *)rpl, crp_size, 0, (struct sockaddr *)&sin, sizeof(sin));
265 T( trace(TRACE_DAEMON, "daemon: reply sent"); )
269 /* --- @daemon_init@ --- *
271 * Arguments: @const char *cf@ = pointer to name of configuration file
272 * @int port@ = port to listen to, or %$-1$% for default
276 * Use: Starts `become' up in daemon mode.
279 void daemon_init(const char *cf, int port)
283 /* --- Remove my root privileges --- *
285 * Just in case there's anything dodgy in my configuration file, or the
286 * user wants me to start on a funny port.
291 /* --- Initialise bits of the program --- */
300 openlog(quis(), 0, LOG_DAEMON);
301 syslog(LOG_NOTICE, "starting up");
303 if (daemon__readConfig(cf))
304 die("couldn't read configuration file");
306 /* --- Decide on a port to use --- *
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.
312 if (daemon__port <= 0) {
313 struct servent *se = getservbyname(quis(), "udp");
315 die("no idea which port to use");
316 daemon__port = ntohs(se->s_port);
319 /* --- Now set up a socket --- */
322 struct sockaddr_in sin;
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));
333 /* --- Fork off into the sunset --- */
340 /* --- Make a background process --- */
343 die("couldn't fork daemon: %s", strerror(errno));
347 /* --- Disconnect from the terminal --- */
351 /* --- Write my process id to a file --- */
353 if ((fp = fopen(file_PID, "w")) != 0) {
354 fprintf(fp, "%lu\n", (unsigned long)getpid());
357 T( trace(TRACE_DAEMON, "daemon: forked to pid %li", (long)getpid()); )
361 /* --- Program in daemon death mode --- */
363 if (setjmp(daemon__dieBuf)) {
365 if (daemon__signum == SIGQUIT && tracing() & TRACE_RULE) {
367 signal(SIGQUIT, daemon__die);
371 T( trace(TRACE_DAEMON, "daemon: killed by signal %i",
373 syslog(LOG_NOTICE, "killed by signal type %i", daemon__signum);
379 /* --- Set signal handlers --- */
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);
390 /* --- Now wait for something exciting to happen --- *
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
400 /* --- Find when I am, and thus when I need to be awoken again --- */
402 when = time(0) + daemon__awakeEvery;
408 /* --- Set up the file descriptor tables --- */
413 /* --- Now wait for something interesting --- */
415 T( trace(TRACE_DAEMON, "daemon: waiting for requests"); )
416 i = select(FD_SETSIZE, &fds, 0, 0, 0);
418 /* --- Now, see if I need to rescan the config --- */
420 if (daemon__rescan || time(0) - when > 0) {
422 syslog(LOG_INFO, "rescanning configuration file");
428 if (daemon__readConfig(cf))
429 syslog(LOG_ERR, "error reading configuration file");
430 when = time(0) + daemon__awakeEvery;
433 /* --- Read the data from the request --- */
441 /*----- That's all, folks -------------------------------------------------*/