2 * atrun.c - run jobs queued by at; run with root privileges.
3 * Copyright (C) 1993, 1994 Thomas Koenig
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. The name of the author(s) may not be used to endorse or promote
11 * products derived from this software without specific prior written
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 static const char rcsid[] =
33 #include <sys/fcntl.h>
34 #include <sys/types.h>
37 #include <sys/param.h>
58 #if (MAXLOGNAME-1) > UT_NAMESIZE
59 #define LOGNAMESIZE UT_NAMESIZE
61 #define LOGNAMESIZE (MAXLOGNAME-1)
73 #define ATJOB_DIR "/usr/spool/atjobs/"
77 #define ATSPOOL_DIR "/usr/spool/atspool/"
81 #define LOADAVG_MX 1.5
84 /* File scope variables */
88 void perr(const char *a);
89 static void usage(void);
93 write_string(int fd, const char* a)
95 return write(fd, a, strlen(a));
106 kill(getpid(),SIGSTOP);
114 run_file(const char *filename, uid_t uid, gid_t gid)
116 /* Run a file by spawning off a process which redirects I/O,
117 * spawns a subshell, then waits for it to complete and sends
123 char mailbuf[LOGNAMESIZE + 1], fmt[49];
124 char *mailname = NULL;
127 struct stat buf, lbuf;
129 struct passwd *pentry;
137 if (chmod(filename, S_IRUSR) != 0)
139 perr("cannot change file permissions");
151 /* Let's see who we mail to. Hopefully, we can read it from
152 * the command file; if not, send it to the owner, or, failing that,
156 pentry = getpwuid(uid);
159 syslog(LOG_ERR,"Userid %lu not found - aborting job %s",
160 (unsigned long) uid, filename);
165 stream=fopen(filename, "r");
170 if (pentry->pw_expire && time(NULL) >= pentry->pw_expire)
172 syslog(LOG_ERR, "Userid %lu is expired - aborting job %s",
173 (unsigned long) uid, filename);
179 perr("cannot open input file");
181 if ((fd_in = dup(fileno(stream))) <0)
182 perr("error duplicating input file descriptor");
184 if (fstat(fd_in, &buf) == -1)
185 perr("error in fstat of input file descriptor");
187 if (lstat(filename, &lbuf) == -1)
188 perr("error in fstat of input file");
190 if (S_ISLNK(lbuf.st_mode)) {
191 syslog(LOG_ERR,"Symbolic link encountered in job %s - aborting",
195 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
196 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
197 (lbuf.st_size!=buf.st_size)) {
198 syslog(LOG_ERR,"Somebody changed files from under us for job %s - "
199 "aborting",filename);
202 if (buf.st_nlink > 1) {
203 syslog(LOG_ERR,"Someboy is trying to run a linked script for job %s",
207 if ((fflags = fcntl(fd_in, F_GETFD)) <0)
208 perr("error in fcntl");
210 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
212 snprintf(fmt, sizeof(fmt),
213 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
215 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) {
216 syslog(LOG_ERR,"File %s is in wrong format - aborting", filename);
219 if (mailbuf[0] == '-') {
220 syslog(LOG_ERR,"illegal mail name %s in %s",mailbuf,filename);
225 syslog(LOG_ERR,"Job %s - userid %ld does not match file uid %lu",
226 filename, nuid, (unsigned long)uid);
230 syslog(LOG_ERR,"Job %s - groupid %ld does not match file gid %lu",
231 filename, ngid, (unsigned long)gid);
235 if (chdir(ATSPOOL_DIR) < 0)
236 perr("cannot chdir to " ATSPOOL_DIR);
238 /* Create a file to hold the output of the job we are about to run.
239 * Write the mail header.
241 if((fd_out=open(filename,
242 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
243 perr("cannot create output file");
245 write_string(fd_out, "Subject: Output from your job ");
246 write_string(fd_out, filename);
247 write_string(fd_out, "\n\n");
252 close(STDOUT_FILENO);
253 close(STDERR_FILENO);
257 perr("error in fork");
264 /* Set up things for the child; we want standard input from the input file,
265 * and standard output and error sent to our output file.
268 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
269 perr("error in lseek");
271 if (dup(fd_in) != STDIN_FILENO)
272 perr("error in I/O redirection");
274 if (dup(fd_out) != STDOUT_FILENO)
275 perr("error in I/O redirection");
277 if (dup(fd_out) != STDERR_FILENO)
278 perr("error in I/O redirection");
282 if (chdir(ATJOB_DIR) < 0)
283 perr("cannot chdir to " ATJOB_DIR);
289 nice(tolower(queue) - 'a');
291 if (initgroups(pentry->pw_name,pentry->pw_gid))
292 perr("cannot delete saved userids");
294 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
295 perr("cannot change group");
297 if (setlogin(pentry->pw_name))
298 perr("cannot set login name");
300 if (setuid(uid) < 0 || seteuid(uid) < 0)
301 perr("cannot set user id");
303 if (chdir(pentry->pw_dir))
306 if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
307 perr("exec failed for /bin/sh");
311 /* We're the parent. Let's wait.
315 waitpid(pid, (int *) NULL, 0);
317 /* Send mail. Unlink the output file first, so it is deleted after
320 stat(filename, &buf);
321 if (open(filename, O_RDONLY) != STDIN_FILENO)
322 perr("open of jobfile failed");
325 if ((buf.st_size != size) || send_mail)
329 if (initgroups(pentry->pw_name,pentry->pw_gid))
330 perr("cannot delete saved userids");
332 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
333 perr("cannot change group");
335 if (setlogin(pentry->pw_name))
336 perr("cannot set login name");
338 if (setuid(uid) < 0 || seteuid(uid) < 0)
339 perr("cannot set user id");
341 if (chdir(pentry->pw_dir))
345 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
347 mailname, (char *) NULL);
349 execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
351 perr("exec failed for mail command");
358 /* Global functions */
360 /* Needed in gloadavg.c */
369 syslog(LOG_ERR, "%s: %m", a);
375 main(int argc, char *argv[])
377 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should
378 * be executed and or deleted. The queue is coded into the first byte of
379 * the job filename, the date (in minutes since Eon) as a hex number in the
380 * following eight bytes, followed by a dot and a serial number. A file
381 * which has not been executed yet is denoted by its execute - bit set.
382 * For those files which are to be executed, run_file() is called, which forks
383 * off a child which takes care of I/O redirection, forks off another child
384 * for execution and yet another one, optionally, for sending mail.
385 * Files which already have run are removed during the next invocation.
388 struct dirent *dirent;
393 time_t now, run_time;
394 char batch_name[] = "Z2345678901234";
399 double load_avg = LOADAVG_MX;
401 /* We don't need root privileges all the time; running under uid and gid daemon
405 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
407 openlog("atrun", LOG_PID, LOG_CRON);
410 while((c=getopt(argc, argv, "dl:"))!= -1)
415 if (sscanf(optarg, "%lf", &load_avg) != 1)
416 perr("garbled option -l");
418 load_avg = LOADAVG_MX;
431 if (chdir(ATJOB_DIR) != 0)
432 perr("cannot change to " ATJOB_DIR);
434 /* Main loop. Open spool directory for reading and look over all the
435 * files in there. If the filename indicates that the job should be run
436 * and the x bit is set, fork off a child which sets its user and group
437 * id to that of the files and exec a /bin/sh which executes the shell
438 * script. Unlink older files if they should no longer be run. For
439 * deletion, their r bit has to be turned on.
441 * Also, pick the oldest batch job to run, at most one per invocation of
444 if ((spool = opendir(".")) == NULL)
445 perr("cannot read " ATJOB_DIR);
449 batch_uid = (uid_t) -1;
450 batch_gid = (gid_t) -1;
452 while ((dirent = readdir(spool)) != NULL) {
453 if (stat(dirent->d_name,&buf) != 0)
454 perr("cannot stat in " ATJOB_DIR);
456 /* We don't want directories
458 if (!S_ISREG(buf.st_mode))
461 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
464 run_time = (time_t) ctm*60;
466 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
467 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
469 strncpy(batch_name, dirent->d_name, sizeof(batch_name));
470 batch_uid = buf.st_uid;
471 batch_gid = buf.st_gid;
474 /* The file is executable and old enough
477 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
479 /* Delete older files
481 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
482 unlink(dirent->d_name);
484 /* run the single batch file, if any
486 if (run_batch && (gloadavg() < load_avg))
487 run_file(batch_name, batch_uid, batch_gid);
497 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
499 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");