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logoutd.c

/*
 * Copyright 1991 - 1993, Julianne Frances Haugh
 * 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. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Julianne F. Haugh nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``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 JULIE HAUGH OR CONTRIBUTORS 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, WHETHER 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.
 */

#include <config.h>

#include "rcsid.h"
RCSID (PKG_VER "$Id: logoutd.c 6 2005-03-20 15:34:28Z bubulle $")
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <signal.h>
#include <utmp.h>
#include <fcntl.h>
#include "prototypes.h"
#include "defines.h"
#ifdef      SVR4
#include <libgen.h>
#endif
#ifdef      SVR4
#define     signal      sigset
#endif
static char *Prog;

#ifndef DEFAULT_HUP_MESG
#define DEFAULT_HUP_MESG "login time exceeded\r\n"
#endif

#ifndef HUP_MESG_FILE
#define HUP_MESG_FILE "/etc/logoutd.mesg"
#endif

/* local function prototypes */
static int check_login (const struct utmp *);


/*
 * check_login - check if user (struct utmp) allowed to stay logged in
 */
static int check_login (const struct utmp *ut)
{
      char user[sizeof (ut->ut_user) + 1];
      time_t now;

      /*
       * ut_user may not have the terminating NUL.
       */
      strncpy (user, ut->ut_user, sizeof (ut->ut_user));
      user[sizeof (ut->ut_user)] = '\0';

      time (&now);

      /*
       * Check if they are allowed to be logged in right now.
       */
      if (!isttytime (user, ut->ut_line, now))
            return 0;
#if 0
      /*
       * Check for how long they are allowed to stay logged in.
       * XXX - not implemented yet. Need to add a new field to
       * /etc/porttime (login time limit in minutes, or no limit,
       * based on username, tty, and time of login).
       */
      if (now - ut->ut_time >
          get_time_limit (user, ut->ut_line, ut->ut_time))
            return 0;
#endif
      return 1;
}


static void send_mesg_to_tty (int tty_fd)
{
      TERMIO oldt, newt;
      FILE *mesg_file, *tty_file;
      int c, is_tty;

      tty_file = fdopen (tty_fd, "w");
      if (!tty_file)
            return;

      is_tty = (GTTY (tty_fd, &oldt) == 0);
      if (is_tty) {
            /* Suggested by Ivan Nejgebauar <ian@unsux.ns.ac.yu>:
               set OPOST before writing the message. */
            newt = oldt;
            newt.c_oflag |= OPOST;
            STTY (tty_fd, &newt);
      }

      mesg_file = fopen (HUP_MESG_FILE, "r");
      if (mesg_file) {
            while ((c = getc (mesg_file)) != EOF) {
                  if (c == '\n')
                        putc ('\r', tty_file);
                  putc (c, tty_file);
            }
            fclose (mesg_file);
      } else {
            fputs (DEFAULT_HUP_MESG, tty_file);
      }
      fflush (tty_file);
      fclose (tty_file);

      if (is_tty) {
            STTY (tty_fd, &oldt);
      }
}


/*
 * logoutd - logout daemon to enforce /etc/porttime file policy
 *
 *    logoutd is started at system boot time and enforces the login
 *    time and port restrictions specified in /etc/porttime. The
 *    utmp file is periodically scanned and offending users are logged
 *    off from the system.
 */

int main (int argc, char **argv)
{
      int i;
      int status;
      pid_t pid;
      struct utmp *ut;
      char user[sizeof (ut->ut_user) + 1];      /* terminating NUL */
      char tty_name[sizeof (ut->ut_line) + 6];  /* /dev/ + NUL */
      int tty_fd;

      setlocale (LC_ALL, "");
      bindtextdomain (PACKAGE, LOCALEDIR);
      textdomain (PACKAGE);

#ifndef DEBUG
      for (i = 0; close (i) == 0; i++);

#ifdef HAVE_SETPGRP
#ifdef SETPGRP_VOID
      setpgrp ();       /* USG */
#else
      setpgrp (getpid (), getpid ());
#endif
#else                   /* !HAVE_SETPGRP */
      setpgid (getpid (), getpid ());     /* BSD || SUN || SUN4 */
#endif                        /* !HAVE_SETPGRP */

      /*
       * Put this process in the background.
       */

      pid = fork ();
      if (pid > 0) {
            /* parent */
            exit (0);
      } else if (pid < 0) {
            /* error */
            perror ("fork");
            exit (1);
      }
#endif                        /* !DEBUG */

      /*
       * Start syslogging everything
       */

      Prog = Basename (argv[0]);

      OPENLOG (Prog);

      /*
       * Scan the UTMP file once per minute looking for users that
       * are not supposed to still be logged in.
       */

      while (1) {

            /* 
             * Attempt to re-open the utmp file. The file is only
             * open while it is being used.
             */

            setutent ();

            /*
             * Read all of the entries in the utmp file. The entries
             * for login sessions will be checked to see if the user
             * is permitted to be signed on at this time.
             */

            while ((ut = getutent ())) {
#ifdef USER_PROCESS
                  if (ut->ut_type != USER_PROCESS)
                        continue;
#endif
                  if (ut->ut_user[0] == '\0')
                        continue;
                  if (check_login (ut))
                        continue;

                  /*
                   * Put the rest of this in a child process. This
                   * keeps the scan from waiting on other ports to die.
                   */

                  pid = fork ();
                  if (pid > 0) {
                        /* parent */
                        continue;
                  } else if (pid < 0) {
                        /* failed - give up until the next scan */
                        break;
                  }
                  /* child */

                  if (strncmp (ut->ut_line, "/dev/", 5) != 0)
                        strcpy (tty_name, "/dev/");
                  else
                        tty_name[0] = '\0';

                  strcat (tty_name, ut->ut_line);
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
                  tty_fd =
                      open (tty_name,
                          O_WRONLY | O_NDELAY | O_NOCTTY);
                  if (tty_fd != -1) {
                        send_mesg_to_tty (tty_fd);
                        close (tty_fd);
                        sleep (10);
                  }
#ifdef USER_PROCESS           /* USG_UTMP */
                  if (ut->ut_pid > 1) {
                        kill (-ut->ut_pid, SIGHUP);
                        sleep (10);
                        kill (-ut->ut_pid, SIGKILL);
                  }
#else                   /* BSD || SUN || SUN4 */
                  /*
                   * vhangup() the line to kill try and kill
                   * whatever is out there using it.
                   */

                  if ((tty_fd =
                       open (tty_name, O_RDONLY | O_NDELAY)) == -1)
                        continue;

                  vhangup (tty_fd);
                  close (tty_fd);
#endif                        /* BSD || SUN || SUN4 */

                  strncpy (user, ut->ut_user, sizeof (user) - 1);
                  user[sizeof (user) - 1] = '\0';

                  SYSLOG ((LOG_NOTICE,
                         "logged off user `%s' on `%s'", user,
                         tty_name));

                  /*
                   * This child has done all it can, drop dead.
                   */

                  exit (0);
            }

            endutent ();

#ifndef DEBUG
            sleep (60);
#endif
            /*
             * Reap any dead babies ...
             */

            while (wait (&status) != -1);
      }
      return 1;         /* not reached */
}

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