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 #include <login_cap.h>
61 #include <security/pam_appl.h>
62 #include <security/openpam.h>
74 #define ATJOB_DIR "/usr/spool/atjobs/"
78 #define ATSPOOL_DIR "/usr/spool/atspool/"
82 #define LOADAVG_MX 1.5
85 /* File scope variables */
87 static const char * const atrun = "atrun"; /* service name for syslog etc. */
90 void perr(const char *fmt, ...);
91 void perrx(const char *fmt, ...);
92 static void usage(void);
96 write_string(int fd, const char* a)
98 return write(fd, a, strlen(a));
109 kill(getpid(),SIGSTOP);
117 run_file(const char *filename, uid_t uid, gid_t gid)
119 /* Run a file by spawning off a process which redirects I/O,
120 * spawns a subshell, then waits for it to complete and sends
126 char mailbuf[MAXLOGNAME], fmt[49];
127 char *mailname = NULL;
130 struct stat buf, lbuf;
132 struct passwd *pentry;
137 pam_handle_t *pamh = NULL;
139 struct pam_conv pamc = {
140 .conv = openpam_nullconv,
147 if (chmod(filename, S_IRUSR) != 0)
149 perr("cannot change file permissions");
161 /* Let's see who we mail to. Hopefully, we can read it from
162 * the command file; if not, send it to the owner, or, failing that,
166 pentry = getpwuid(uid);
168 perrx("Userid %lu not found - aborting job %s",
169 (unsigned long) uid, filename);
174 pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh);
175 if (pam_err != PAM_SUCCESS)
176 perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err));
178 pam_err = pam_acct_mgmt(pamh, PAM_SILENT);
179 /* Expired password shouldn't prevent the job from running. */
180 if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD)
181 perrx("Account %s (userid %lu) unavailable for job %s: %s",
182 pentry->pw_name, (unsigned long)uid,
183 filename, pam_strerror(pamh, pam_err));
185 pam_end(pamh, pam_err);
192 stream=fopen(filename, "r");
197 perr("cannot open input file");
199 if ((fd_in = dup(fileno(stream))) <0)
200 perr("error duplicating input file descriptor");
202 if (fstat(fd_in, &buf) == -1)
203 perr("error in fstat of input file descriptor");
205 if (lstat(filename, &lbuf) == -1)
206 perr("error in fstat of input file");
208 if (S_ISLNK(lbuf.st_mode))
209 perrx("Symbolic link encountered in job %s - aborting", filename);
211 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
212 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
213 (lbuf.st_size!=buf.st_size))
214 perrx("Somebody changed files from under us for job %s - aborting",
217 if (buf.st_nlink > 1)
218 perrx("Somebody is trying to run a linked script for job %s", filename);
220 if ((fflags = fcntl(fd_in, F_GETFD)) <0)
221 perr("error in fcntl");
223 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
225 snprintf(fmt, sizeof(fmt),
226 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
229 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4)
230 perrx("File %s is in wrong format - aborting", filename);
232 if (mailbuf[0] == '-')
233 perrx("Illegal mail name %s in %s", mailbuf, filename);
238 perrx("Job %s - userid %ld does not match file uid %lu",
239 filename, nuid, (unsigned long)uid);
242 perrx("Job %s - groupid %ld does not match file gid %lu",
243 filename, ngid, (unsigned long)gid);
247 if (chdir(ATSPOOL_DIR) < 0)
248 perr("cannot chdir to %s", ATSPOOL_DIR);
250 /* Create a file to hold the output of the job we are about to run.
251 * Write the mail header.
253 if((fd_out=open(filename,
254 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
255 perr("cannot create output file");
257 write_string(fd_out, "Subject: Output from your job ");
258 write_string(fd_out, filename);
259 write_string(fd_out, "\n\n");
264 close(STDOUT_FILENO);
265 close(STDERR_FILENO);
269 perr("error in fork");
276 /* Set up things for the child; we want standard input from the input file,
277 * and standard output and error sent to our output file.
280 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
281 perr("error in lseek");
283 if (dup(fd_in) != STDIN_FILENO)
284 perr("error in I/O redirection");
286 if (dup(fd_out) != STDOUT_FILENO)
287 perr("error in I/O redirection");
289 if (dup(fd_out) != STDERR_FILENO)
290 perr("error in I/O redirection");
294 if (chdir(ATJOB_DIR) < 0)
295 perr("cannot chdir to %s", ATJOB_DIR);
301 nice(tolower(queue) - 'a');
305 * For simplicity and safety, set all aspects of the user context
306 * except for a selected subset: Don't set priority, which was
307 * set based on the queue file name according to the tradition.
308 * Don't bother to set environment, including path vars, either
309 * because it will be discarded anyway. Although the job file
310 * should set umask, preset it here just in case.
312 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL &
313 ~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0)
314 exit(EXIT_FAILURE); /* setusercontext() logged the error */
315 #else /* LOGIN_CAP */
316 if (initgroups(pentry->pw_name,pentry->pw_gid))
317 perr("cannot init group access list");
319 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
320 perr("cannot change group");
322 if (setlogin(pentry->pw_name))
323 perr("cannot set login name");
325 if (setuid(uid) < 0 || seteuid(uid) < 0)
326 perr("cannot set user id");
327 #endif /* LOGIN_CAP */
329 if (chdir(pentry->pw_dir))
332 if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
333 perr("exec failed for /bin/sh");
337 /* We're the parent. Let's wait.
341 waitpid(pid, (int *) NULL, 0);
343 /* Send mail. Unlink the output file first, so it is deleted after
346 stat(filename, &buf);
347 if (open(filename, O_RDONLY) != STDIN_FILENO)
348 perr("open of jobfile failed");
351 if ((buf.st_size != size) || send_mail)
357 * This time set full context to run the mailer.
359 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0)
360 exit(EXIT_FAILURE); /* setusercontext() logged the error */
361 #else /* LOGIN_CAP */
362 if (initgroups(pentry->pw_name,pentry->pw_gid))
363 perr("cannot init group access list");
365 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
366 perr("cannot change group");
368 if (setlogin(pentry->pw_name))
369 perr("cannot set login name");
371 if (setuid(uid) < 0 || seteuid(uid) < 0)
372 perr("cannot set user id");
373 #endif /* LOGIN_CAP */
375 if (chdir(pentry->pw_dir))
379 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
381 mailname, (char *) NULL);
383 execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
385 perr("exec failed for mail command");
392 /* Global functions */
394 /* Needed in gloadavg.c */
396 perr(const char *fmt, ...)
398 const char * const fmtadd = ": %m";
399 char nfmt[strlen(fmt) + strlen(fmtadd) + 1];
409 snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd);
410 vsyslog(LOG_ERR, nfmt, ap);
418 perrx(const char *fmt, ...)
426 vsyslog(LOG_ERR, fmt, ap);
433 main(int argc, char *argv[])
435 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should
436 * be executed and or deleted. The queue is coded into the first byte of
437 * the job filename, the date (in minutes since Eon) as a hex number in the
438 * following eight bytes, followed by a dot and a serial number. A file
439 * which has not been executed yet is denoted by its execute - bit set.
440 * For those files which are to be executed, run_file() is called, which forks
441 * off a child which takes care of I/O redirection, forks off another child
442 * for execution and yet another one, optionally, for sending mail.
443 * Files which already have run are removed during the next invocation.
446 struct dirent *dirent;
451 time_t now, run_time;
452 char batch_name[] = "Z2345678901234";
457 double load_avg = LOADAVG_MX;
459 /* We don't need root privileges all the time; running under uid and gid daemon
463 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
465 openlog(atrun, LOG_PID, LOG_CRON);
468 while((c=getopt(argc, argv, "dl:"))!= -1)
473 if (sscanf(optarg, "%lf", &load_avg) != 1)
474 perr("garbled option -l");
476 load_avg = LOADAVG_MX;
489 if (chdir(ATJOB_DIR) != 0)
490 perr("cannot change to %s", ATJOB_DIR);
492 /* Main loop. Open spool directory for reading and look over all the
493 * files in there. If the filename indicates that the job should be run
494 * and the x bit is set, fork off a child which sets its user and group
495 * id to that of the files and exec a /bin/sh which executes the shell
496 * script. Unlink older files if they should no longer be run. For
497 * deletion, their r bit has to be turned on.
499 * Also, pick the oldest batch job to run, at most one per invocation of
502 if ((spool = opendir(".")) == NULL)
503 perr("cannot read %s", ATJOB_DIR);
507 batch_uid = (uid_t) -1;
508 batch_gid = (gid_t) -1;
510 while ((dirent = readdir(spool)) != NULL) {
511 if (stat(dirent->d_name,&buf) != 0)
512 perr("cannot stat in %s", ATJOB_DIR);
514 /* We don't want directories
516 if (!S_ISREG(buf.st_mode))
519 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
522 run_time = (time_t) ctm*60;
524 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
525 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
527 strlcpy(batch_name, dirent->d_name, sizeof(batch_name));
528 batch_uid = buf.st_uid;
529 batch_gid = buf.st_gid;
532 /* The file is executable and old enough
535 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
537 /* Delete older files
539 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
540 unlink(dirent->d_name);
542 /* run the single batch file, if any
544 if (run_batch && (gloadavg() < load_avg))
545 run_file(batch_name, batch_uid, batch_gid);
555 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
557 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");