NetBSD/libexec/atrun/atrun.c

332 lines
8.0 KiB
C

/* $NetBSD: atrun.c,v 1.3 1996/08/30 20:24:51 thorpej Exp $ */
/*
* atrun.c - run jobs queued by at; run with root privileges.
* Copyright (c) 1993 by Thomas Koenig
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. The name of the author(s) may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* System Headers */
#include <sys/fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <dirent.h>
#include <errno.h>
#include <pwd.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <syslog.h>
#include <paths.h>
/* Local headers */
#define MAIN
#include "privs.h"
#include "pathnames.h"
#include "atrun.h"
/* File scope variables */
static char *namep;
static char rcsid[] = "$NetBSD: atrun.c,v 1.3 1996/08/30 20:24:51 thorpej Exp $";
/* Local functions */
static void
perr(a)
const char *a;
{
syslog(LOG_ERR, "%s: %m", a);
exit(EXIT_FAILURE);
}
static int
write_string(fd, a)
int fd;
const char *a;
{
return write(fd, a, strlen(a));
}
static void
run_file(filename, uid)
const char *filename;
uid_t uid;
{
/*
* Run a file by by spawning off a process which redirects I/O,
* spawns a subshell, then waits for it to complete and spawns another
* process to send mail to the user.
*/
pid_t pid;
int fd_out, fd_in;
int queue;
char mailbuf[9];
char *mailname = NULL;
FILE *stream;
int send_mail = 0;
struct stat buf;
off_t size;
struct passwd *pentry;
int fflags;
pid = fork();
if (pid == -1)
perr("Cannot fork");
else if (pid > 0)
return;
/*
* Let's see who we mail to. Hopefully, we can read it from the
* command file; if not, send it to the owner, or, failing that, to
* root.
*/
PRIV_START
stream = fopen(filename, "r");
PRIV_END
pentry = getpwuid(uid);
if (pentry == NULL)
perr("UID not in password file!");
if (stream == NULL)
perr("Cannot open input file");
if ((fd_in = dup(fileno(stream))) < 0)
perr("Error duplicating input file descriptor");
if ((fflags = fcntl(fd_in, F_GETFD)) < 0)
perr("Error in fcntl");
fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
if (fscanf(stream, "#! /bin/sh\n# mail %8s %d", mailbuf, &send_mail) == 2) {
mailname = mailbuf;
} else {
mailname = pentry->pw_name;
}
fclose(stream);
if (chdir(_PATH_ATSPOOL) < 0)
perr("Cannot chdir to " _PATH_ATSPOOL);
/*
* Create a file to hold the output of the job we are about to
* run. Write the mail header.
*/
if ((fd_out = open(filename,
O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
perr("Cannot create output file");
write_string(fd_out, "Subject: Output from your job ");
write_string(fd_out, filename);
write_string(fd_out, "\n\n");
fstat(fd_out, &buf);
size = buf.st_size;
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
pid = fork();
if (pid < 0)
perr("Error in fork");
else if (pid == 0) {
char *nul = NULL;
char **nenvp = &nul;
/*
* Set up things for the child; we want standard input from
* the input file, and standard output and error sent to
* our output file.
*/
if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
perr("Error in lseek");
if (dup(fd_in) != STDIN_FILENO)
perr("Error in I/O redirection");
if (dup(fd_out) != STDOUT_FILENO)
perr("Error in I/O redirection");
if (dup(fd_out) != STDERR_FILENO)
perr("Error in I/O redirection");
close(fd_in);
close(fd_out);
if (chdir(_PATH_ATJOBS) < 0)
perr("Cannot chdir to " _PATH_ATJOBS);
queue = *filename;
PRIV_START
if (queue > 'b')
nice(queue - 'b');
if (initgroups(pentry->pw_name, pentry->pw_gid) < 0)
perr("Cannot init group list");
if (setgid(pentry->pw_gid) < 0)
perr("Cannot change primary group");
if (setuid(uid) < 0)
perr("Cannot set user id");
chdir("/");
if (execle("/bin/sh", "sh", (char *) NULL, nenvp) != 0)
perr("Exec failed");
PRIV_END
}
/* We're the parent. Let's wait. */
close(fd_in);
close(fd_out);
waitpid(pid, (int *) NULL, 0);
stat(filename, &buf);
if ((buf.st_size != size) || send_mail) {
/* Fork off a child for sending mail */
pid = fork();
if (pid < 0)
perr("Fork failed");
else if (pid == 0) {
if (open(filename, O_RDONLY) != STDIN_FILENO)
perr("Cannot reopen output file");
execl(_PATH_SENDMAIL, _PATH_SENDMAIL, mailname,
(char *) NULL);
perr("Exec failed");
}
waitpid(pid, (int *) NULL, 0);
}
unlink(filename);
exit(EXIT_SUCCESS);
}
/* Global functions */
int
main(argc, argv)
int argc;
char *argv[];
{
/*
* Browse through _PATH_ATJOBS, checking all the jobfiles wether
* they should be executed and or deleted. The queue is coded into
* the first byte of the job filename, the date (in minutes since
* Eon) as a hex number in the following eight bytes, followed by
* a dot and a serial number. A file which has not been executed
* yet is denoted by its execute - bit set. For those files which
* are to be executed, run_file() is called, which forks off a
* child which takes care of I/O redirection, forks off another
* child for execution and yet another one, optionally, for sending
* mail. Files which already have run are removed during the
* next invocation.
*/
DIR *spool;
struct dirent *dirent;
struct stat buf;
int older;
unsigned long ctm;
char queue;
/*
* We don't need root privileges all the time; running under uid
* and gid daemon is fine.
*/
RELINQUISH_PRIVS_ROOT(0) /* it's setuid root */
openlog("atrun", LOG_PID, LOG_CRON);
namep = argv[0];
if (chdir(_PATH_ATJOBS) != 0)
perr("Cannot change to " _PATH_ATJOBS);
/*
* Main loop. Open spool directory for reading and look over all
* the files in there. If the filename indicates that the job
* should be run and the x bit is set, fork off a child which sets
* its user and group id to that of the files and exec a /bin/sh
* which executes the shell script. Unlink older files if they
* should no longer be run. For deletion, their r bit has to be
* turned on.
*/
if ((spool = opendir(".")) == NULL)
perr("Cannot read " _PATH_ATJOBS);
while ((dirent = readdir(spool)) != NULL) {
double la;
if (stat(dirent->d_name, &buf) != 0)
perr("Cannot stat in " _PATH_ATJOBS);
/* We don't want directories */
if (!S_ISREG(buf.st_mode))
continue;
if (sscanf(dirent->d_name, "%c%8lx", &queue, &ctm) != 2)
continue;
if ((queue == 'b') && ((getloadavg(&la, 1) != 1) ||
(la > ATRUN_MAXLOAD)))
continue;
older = (time_t) ctm *60 <= time(NULL);
/* The file is executable and old enough */
if (older && (S_IXUSR & buf.st_mode)) {
/*
* Now we know we want to run the file, we can turn
* off the execute bit
*/
PRIV_START
if (chmod(dirent->d_name, S_IRUSR) != 0)
perr("Cannot change file permissions");
PRIV_END
run_file(dirent->d_name, buf.st_uid);
}
/* Delete older files */
if (older && !(S_IXUSR & buf.st_mode) &&
(S_IRUSR & buf.st_mode))
unlink(dirent->d_name);
}
closelog();
exit(EXIT_SUCCESS);
}