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/sysctl.h>
40 #include <sys/param.h>
62 #include <login_cap.h>
65 #include <security/pam_appl.h>
66 #include <security/openpam.h>
69 #if (MAXLOGNAME-1) > UT_NAMESIZE
70 #define LOGNAMESIZE UT_NAMESIZE
72 #define LOGNAMESIZE (MAXLOGNAME-1)
84 #define ATJOB_DIR "/usr/spool/atjobs/"
88 #define ATSPOOL_DIR "/usr/spool/atspool/"
92 #define LOADAVG_MX 1.5
95 /* File scope variables */
97 static const char * const atrun = "atrun"; /* service name for syslog etc. */
100 void perr(const char *fmt, ...);
101 void perrx(const char *fmt, ...);
102 static void usage(void);
104 /* Local functions */
106 write_string(int fd, const char* a)
108 return write(fd, a, strlen(a));
119 kill(getpid(),SIGSTOP);
127 run_file(const char *filename, uid_t uid, gid_t gid)
129 /* Run a file by spawning off a process which redirects I/O,
130 * spawns a subshell, then waits for it to complete and sends
136 char mailbuf[LOGNAMESIZE + 1], fmt[64];
137 char *mailname = NULL;
140 struct stat buf, lbuf;
142 struct passwd *pentry;
147 pam_handle_t *pamh = NULL;
149 struct pam_conv pamc = {
150 .conv = openpam_nullconv,
157 if (chmod(filename, S_IRUSR) != 0)
159 perr("cannot change file permissions");
171 /* Let's see who we mail to. Hopefully, we can read it from
172 * the command file; if not, send it to the owner, or, failing that,
176 pentry = getpwuid(uid);
178 perrx("Userid %lu not found - aborting job %s",
179 (unsigned long) uid, filename);
184 pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh);
185 if (pam_err != PAM_SUCCESS)
186 perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err));
188 pam_err = pam_acct_mgmt(pamh, PAM_SILENT);
189 /* Expired password shouldn't prevent the job from running. */
190 if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD)
191 perrx("Account %s (userid %lu) unavailable for job %s: %s",
192 pentry->pw_name, (unsigned long)uid,
193 filename, pam_strerror(pamh, pam_err));
195 pam_end(pamh, pam_err);
202 stream=fopen(filename, "r");
207 perr("cannot open input file");
209 if ((fd_in = dup(fileno(stream))) <0)
210 perr("error duplicating input file descriptor");
212 if (fstat(fd_in, &buf) == -1)
213 perr("error in fstat of input file descriptor");
215 if (lstat(filename, &lbuf) == -1)
216 perr("error in fstat of input file");
218 if (S_ISLNK(lbuf.st_mode))
219 perrx("Symbolic link encountered in job %s - aborting", filename);
221 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
222 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
223 (lbuf.st_size!=buf.st_size))
224 perrx("Somebody changed files from under us for job %s - aborting",
227 if (buf.st_nlink > 1)
228 perrx("Somebody is trying to run a linked script for job %s", filename);
230 if ((fflags = fcntl(fd_in, F_GETFD)) <0)
231 perr("error in fcntl");
233 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
235 snprintf(fmt, sizeof(fmt),
236 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
239 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4)
240 perrx("File %s is in wrong format - aborting", filename);
242 if (mailbuf[0] == '-')
243 perrx("Illegal mail name %s in %s", mailbuf, filename);
248 perrx("Job %s - userid %ld does not match file uid %lu",
249 filename, nuid, (unsigned long)uid);
252 perrx("Job %s - groupid %ld does not match file gid %lu",
253 filename, ngid, (unsigned long)gid);
257 if (chdir(ATSPOOL_DIR) < 0)
258 perr("cannot chdir to %s", ATSPOOL_DIR);
260 /* Create a file to hold the output of the job we are about to run.
261 * Write the mail header.
263 if((fd_out=open(filename,
264 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
265 perr("cannot create output file");
267 write_string(fd_out, "Subject: Output from your job ");
268 write_string(fd_out, filename);
269 write_string(fd_out, "\n\n");
274 close(STDOUT_FILENO);
275 close(STDERR_FILENO);
279 perr("error in fork");
286 /* Set up things for the child; we want standard input from the input file,
287 * and standard output and error sent to our output file.
290 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
291 perr("error in lseek");
293 if (dup(fd_in) != STDIN_FILENO)
294 perr("error in I/O redirection");
296 if (dup(fd_out) != STDOUT_FILENO)
297 perr("error in I/O redirection");
299 if (dup(fd_out) != STDERR_FILENO)
300 perr("error in I/O redirection");
304 if (chdir(ATJOB_DIR) < 0)
305 perr("cannot chdir to %s", ATJOB_DIR);
311 nice(tolower(queue) - 'a');
315 * For simplicity and safety, set all aspects of the user context
316 * except for a selected subset: Don't set priority, which was
317 * set based on the queue file name according to the tradition.
318 * Don't bother to set environment, including path vars, either
319 * because it will be discarded anyway. Although the job file
320 * should set umask, preset it here just in case.
322 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL &
323 ~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0)
324 exit(EXIT_FAILURE); /* setusercontext() logged the error */
325 #else /* LOGIN_CAP */
326 if (initgroups(pentry->pw_name,pentry->pw_gid))
327 perr("cannot init group access list");
329 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
330 perr("cannot change group");
332 if (setlogin(pentry->pw_name))
333 perr("cannot set login name");
335 if (setuid(uid) < 0 || seteuid(uid) < 0)
336 perr("cannot set user id");
337 #endif /* LOGIN_CAP */
339 if (chdir(pentry->pw_dir))
342 if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
343 perr("exec failed for /bin/sh");
347 /* We're the parent. Let's wait.
351 waitpid(pid, (int *) NULL, 0);
353 /* Send mail. Unlink the output file first, so it is deleted after
356 stat(filename, &buf);
357 if (open(filename, O_RDONLY) != STDIN_FILENO)
358 perr("open of jobfile failed");
361 if ((buf.st_size != size) || send_mail)
367 * This time set full context to run the mailer.
369 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0)
370 exit(EXIT_FAILURE); /* setusercontext() logged the error */
371 #else /* LOGIN_CAP */
372 if (initgroups(pentry->pw_name,pentry->pw_gid))
373 perr("cannot init group access list");
375 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
376 perr("cannot change group");
378 if (setlogin(pentry->pw_name))
379 perr("cannot set login name");
381 if (setuid(uid) < 0 || seteuid(uid) < 0)
382 perr("cannot set user id");
383 #endif /* LOGIN_CAP */
385 if (chdir(pentry->pw_dir))
389 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
391 mailname, (char *) NULL);
393 execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
395 perr("exec failed for mail command");
402 /* Global functions */
404 /* Needed in gloadavg.c */
406 perr(const char *fmt, ...)
408 const char * const fmtadd = ": %m";
409 char nfmt[strlen(fmt) + strlen(fmtadd) + 1];
419 snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd);
420 vsyslog(LOG_ERR, nfmt, ap);
428 perrx(const char *fmt, ...)
436 vsyslog(LOG_ERR, fmt, ap);
443 main(int argc, char *argv[])
445 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should
446 * be executed and or deleted. The queue is coded into the first byte of
447 * the job filename, the date (in minutes since Eon) as a hex number in the
448 * following eight bytes, followed by a dot and a serial number. A file
449 * which has not been executed yet is denoted by its execute - bit set.
450 * For those files which are to be executed, run_file() is called, which forks
451 * off a child which takes care of I/O redirection, forks off another child
452 * for execution and yet another one, optionally, for sending mail.
453 * Files which already have run are removed during the next invocation.
456 struct dirent *dirent;
461 time_t now, run_time;
462 char batch_name[] = "Z2345678901234";
469 double load_avg = -1;
471 double load_avg = LOADAVG_MX;
474 /* We don't need root privileges all the time; running under uid and gid daemon
478 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
480 openlog(atrun, LOG_PID, LOG_CRON);
483 while((c=getopt(argc, argv, "dl:"))!= -1)
488 if (sscanf(optarg, "%lf", &load_avg) != 1)
489 perr("garbled option -l");
492 load_avg = LOADAVG_MX;
506 if (chdir(ATJOB_DIR) != 0)
507 perr("cannot change to %s", ATJOB_DIR);
510 if (load_avg <= 0.) {
511 ncpusz = sizeof(size_t);
512 if (sysctlbyname("hw.ncpu", &ncpu, &ncpusz, NULL, 0) < 0)
514 load_avg = LOADAVG_MX * ncpu;
518 /* Main loop. Open spool directory for reading and look over all the
519 * files in there. If the filename indicates that the job should be run
520 * and the x bit is set, fork off a child which sets its user and group
521 * id to that of the files and exec a /bin/sh which executes the shell
522 * script. Unlink older files if they should no longer be run. For
523 * deletion, their r bit has to be turned on.
525 * Also, pick the oldest batch job to run, at most one per invocation of
528 if ((spool = opendir(".")) == NULL)
529 perr("cannot read %s", ATJOB_DIR);
533 batch_uid = (uid_t) -1;
534 batch_gid = (gid_t) -1;
536 while ((dirent = readdir(spool)) != NULL) {
537 if (stat(dirent->d_name,&buf) != 0)
538 perr("cannot stat in %s", ATJOB_DIR);
540 /* We don't want directories
542 if (!S_ISREG(buf.st_mode))
545 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
548 run_time = (time_t) ctm*60;
550 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
551 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
553 strlcpy(batch_name, dirent->d_name, sizeof(batch_name));
554 batch_uid = buf.st_uid;
555 batch_gid = buf.st_gid;
558 /* The file is executable and old enough
561 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
563 /* Delete older files
565 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
566 unlink(dirent->d_name);
568 /* run the single batch file, if any
570 if (run_batch && (gloadavg() < load_avg))
571 run_file(batch_name, batch_uid, batch_gid);
581 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
583 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");