2 * atrun.c - run jobs queued by at; run with root privileges.
4 * SPDX-License-Identifier: BSD-2-Clause
6 * Copyright (C) 1993, 1994 Thomas Koenig
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. The name of the author(s) may not be used to endorse or promote
14 * products derived from this software without specific prior written
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 static const char rcsid[] =
36 #include <sys/fcntl.h>
38 #include <sys/types.h>
41 #include <sys/sysctl.h>
44 #include <sys/param.h>
65 #include <login_cap.h>
68 #include <security/pam_appl.h>
69 #include <security/openpam.h>
81 #define ATJOB_DIR "/usr/spool/atjobs/"
85 #define ATSPOOL_DIR "/usr/spool/atspool/"
89 #define LOADAVG_MX 1.5
92 /* File scope variables */
94 static const char * const atrun = "atrun"; /* service name for syslog etc. */
97 void perr(const char *fmt, ...);
98 void perrx(const char *fmt, ...);
99 static void usage(void) __dead2;
101 /* Local functions */
103 write_string(int fd, const char* a)
105 return write(fd, a, strlen(a));
116 kill(getpid(),SIGSTOP);
124 run_file(const char *filename, uid_t uid, gid_t gid)
126 /* Run a file by spawning off a process which redirects I/O,
127 * spawns a subshell, then waits for it to complete and sends
133 char mailbuf[MAXLOGNAME], fmt[64];
134 char *mailname = NULL;
137 struct stat buf, lbuf;
139 struct passwd *pentry;
144 pam_handle_t *pamh = NULL;
146 struct pam_conv pamc = {
147 .conv = openpam_nullconv,
154 if (chmod(filename, S_IRUSR) != 0)
156 perr("cannot change file permissions");
168 /* Let's see who we mail to. Hopefully, we can read it from
169 * the command file; if not, send it to the owner, or, failing that,
173 pentry = getpwuid(uid);
175 perrx("Userid %lu not found - aborting job %s",
176 (unsigned long) uid, filename);
181 pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh);
182 if (pam_err != PAM_SUCCESS)
183 perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err));
185 pam_err = pam_acct_mgmt(pamh, PAM_SILENT);
186 /* Expired password shouldn't prevent the job from running. */
187 if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD)
188 perrx("Account %s (userid %lu) unavailable for job %s: %s",
189 pentry->pw_name, (unsigned long)uid,
190 filename, pam_strerror(pamh, pam_err));
192 pam_end(pamh, pam_err);
199 stream=fopen(filename, "r");
204 perr("cannot open input file %s", filename);
206 if ((fd_in = dup(fileno(stream))) <0)
207 perr("error duplicating input file descriptor");
209 if (fstat(fd_in, &buf) == -1)
210 perr("error in fstat of input file descriptor");
212 if (lstat(filename, &lbuf) == -1)
213 perr("error in fstat of input file");
215 if (S_ISLNK(lbuf.st_mode))
216 perrx("Symbolic link encountered in job %s - aborting", filename);
218 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
219 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
220 (lbuf.st_size!=buf.st_size))
221 perrx("Somebody changed files from under us for job %s - aborting",
224 if (buf.st_nlink > 1)
225 perrx("Somebody is trying to run a linked script for job %s", filename);
227 if ((fflags = fcntl(fd_in, F_GETFD)) <0)
228 perr("error in fcntl");
230 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
232 snprintf(fmt, sizeof(fmt),
233 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
236 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4)
237 perrx("File %s is in wrong format - aborting", filename);
239 if (mailbuf[0] == '-')
240 perrx("Illegal mail name %s in %s", mailbuf, filename);
245 perrx("Job %s - userid %ld does not match file uid %lu",
246 filename, nuid, (unsigned long)uid);
249 perrx("Job %s - groupid %ld does not match file gid %lu",
250 filename, ngid, (unsigned long)gid);
254 if (chdir(ATSPOOL_DIR) < 0)
255 perr("cannot chdir to %s", ATSPOOL_DIR);
257 /* Create a file to hold the output of the job we are about to run.
258 * Write the mail header.
260 if((fd_out=open(filename,
261 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
262 perr("cannot create output file");
264 write_string(fd_out, "Subject: Output from your job ");
265 write_string(fd_out, filename);
266 write_string(fd_out, "\n\n");
271 close(STDOUT_FILENO);
272 close(STDERR_FILENO);
276 perr("error in fork");
283 /* Set up things for the child; we want standard input from the input file,
284 * and standard output and error sent to our output file.
287 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
288 perr("error in lseek");
290 if (dup(fd_in) != STDIN_FILENO)
291 perr("error in I/O redirection");
293 if (dup(fd_out) != STDOUT_FILENO)
294 perr("error in I/O redirection");
296 if (dup(fd_out) != STDERR_FILENO)
297 perr("error in I/O redirection");
301 if (chdir(ATJOB_DIR) < 0)
302 perr("cannot chdir to %s", ATJOB_DIR);
308 nice(tolower(queue) - 'a');
312 * For simplicity and safety, set all aspects of the user context
313 * except for a selected subset: Don't set priority, which was
314 * set based on the queue file name according to the tradition.
315 * Don't bother to set environment, including path vars, either
316 * because it will be discarded anyway. Although the job file
317 * should set umask, preset it here just in case.
319 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL &
320 ~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0)
321 exit(EXIT_FAILURE); /* setusercontext() logged the error */
322 #else /* LOGIN_CAP */
323 if (initgroups(pentry->pw_name,pentry->pw_gid))
324 perr("cannot init group access list");
326 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
327 perr("cannot change group");
329 if (setlogin(pentry->pw_name))
330 perr("cannot set login name");
332 if (setuid(uid) < 0 || seteuid(uid) < 0)
333 perr("cannot set user id");
334 #endif /* LOGIN_CAP */
336 if (chdir(pentry->pw_dir))
339 if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
340 perr("exec failed for /bin/sh");
344 /* We're the parent. Let's wait.
348 waitpid(pid, (int *) NULL, 0);
350 /* Send mail. Unlink the output file first, so it is deleted after
353 stat(filename, &buf);
354 if (open(filename, O_RDONLY) != STDIN_FILENO)
355 perr("open of jobfile failed");
358 if ((buf.st_size != size) || send_mail)
364 * This time set full context to run the mailer.
366 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0)
367 exit(EXIT_FAILURE); /* setusercontext() logged the error */
368 #else /* LOGIN_CAP */
369 if (initgroups(pentry->pw_name,pentry->pw_gid))
370 perr("cannot init group access list");
372 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
373 perr("cannot change group");
375 if (setlogin(pentry->pw_name))
376 perr("cannot set login name");
378 if (setuid(uid) < 0 || seteuid(uid) < 0)
379 perr("cannot set user id");
380 #endif /* LOGIN_CAP */
382 if (chdir(pentry->pw_dir))
386 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
388 mailname, (char *) NULL);
390 execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
392 perr("exec failed for mail command");
399 /* Global functions */
401 /* Needed in gloadavg.c */
403 perr(const char *fmt, ...)
405 const char * const fmtadd = ": %m";
406 char nfmt[strlen(fmt) + strlen(fmtadd) + 1];
416 snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd);
417 vsyslog(LOG_ERR, nfmt, ap);
425 perrx(const char *fmt, ...)
433 vsyslog(LOG_ERR, fmt, ap);
440 main(int argc, char *argv[])
442 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should
443 * be executed and or deleted. The queue is coded into the first byte of
444 * the job filename, the date (in minutes since Eon) as a hex number in the
445 * following eight bytes, followed by a dot and a serial number. A file
446 * which has not been executed yet is denoted by its execute - bit set.
447 * For those files which are to be executed, run_file() is called, which forks
448 * off a child which takes care of I/O redirection, forks off another child
449 * for execution and yet another one, optionally, for sending mail.
450 * Files which already have run are removed during the next invocation.
453 struct dirent *dirent;
458 time_t now, run_time;
459 char batch_name[] = "Z2345678901234";
466 double load_avg = -1;
469 double load_avg = LOADAVG_MX;
472 /* We don't need root privileges all the time; running under uid and gid daemon
476 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
478 openlog(atrun, LOG_PID, LOG_CRON);
481 while((c=getopt(argc, argv, "dl:"))!= -1)
486 if (sscanf(optarg, "%lf", &load_avg) != 1)
487 perr("garbled option -l");
490 load_avg = LOADAVG_MX;
504 if (chdir(ATJOB_DIR) != 0)
505 perr("cannot change to %s", ATJOB_DIR);
508 if (load_avg <= 0.) {
509 ncpusz = sizeof(size_t);
510 if (sysctlbyname("hw.ncpu", &ncpu, &ncpusz, NULL, 0) < 0)
512 load_avg = LOADAVG_MX * ncpu;
516 /* Main loop. Open spool directory for reading and look over all the
517 * files in there. If the filename indicates that the job should be run
518 * and the x bit is set, fork off a child which sets its user and group
519 * id to that of the files and exec a /bin/sh which executes the shell
520 * script. Unlink older files if they should no longer be run. For
521 * deletion, their r bit has to be turned on.
523 * Also, pick the oldest batch job to run, at most one per invocation of
526 if ((spool = opendir(".")) == NULL)
527 perr("cannot read %s", ATJOB_DIR);
529 if (flock(dirfd(spool), LOCK_EX) == -1)
530 perr("cannot lock %s", ATJOB_DIR);
534 batch_uid = (uid_t) -1;
535 batch_gid = (gid_t) -1;
537 while ((dirent = readdir(spool)) != NULL) {
538 if (stat(dirent->d_name,&buf) != 0)
539 perr("cannot stat in %s", ATJOB_DIR);
541 /* We don't want directories
543 if (!S_ISREG(buf.st_mode))
546 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
549 run_time = (time_t) ctm*60;
551 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
552 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
554 strlcpy(batch_name, dirent->d_name, sizeof(batch_name));
555 batch_uid = buf.st_uid;
556 batch_gid = buf.st_gid;
559 /* The file is executable and old enough
562 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
564 /* Delete older files
566 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
567 unlink(dirent->d_name);
569 /* run the single batch file, if any
571 if (run_batch && (gloadavg() < load_avg))
572 run_file(batch_name, batch_uid, batch_gid);
574 if (flock(dirfd(spool), LOCK_UN) == -1)
575 perr("cannot unlock %s", ATJOB_DIR);
577 if (closedir(spool) == -1)
578 perr("cannot closedir %s", ATJOB_DIR);
588 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
590 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");