vlock.c

   1 /* vlock.c -- main routine for vlock, the VT locking program for linux
   2  *
   3  * This program is copyright (C) 1994 Michael K. Johnson, and is free
   4  * software which is freely distributable under the terms of the
   5  * GNU public license, included as the file COPYING in this
   6  * distribution.  It is NOT public domain software, and any
   7  * redistribution not permitted by the GNU Public License is
   8  * expressly forbidden without prior written permission from
   9  * the author.
  10  *
  11  */
  12
  13 /* RCS log:
  14  * $Log: vlock.c,v $
  15  * Revision 1.11  1994/07/03 12:41:43  johnsonm
  16  * Removed emacs variables.
  17  *
  18  * Revision 1.10  1994/07/03  12:15:22  johnsonm
  19  * *** empty log message ***
  20  *
  21  * Revision 1.9  1994/03/23  17:00:47  johnsonm
  22  * Removed appendages for patterns.
  23  * Added support for non-VT ttys.
  24  *
  25  * Revision 1.8  1994/03/20  11:21:20  johnsonm
  26  * Now check /dev/console after opening it to make sure the call succeeded
  27  *
  28  * Revision 1.7  1994/03/19  17:54:42  johnsonm
  29  * Moved printing the lock message to get_password.  Added a return
  30  * code again.
  31  *
  32  * Revision 1.6  1994/03/19  14:36:08  johnsonm
  33  * Made a better explanation for when the --all or -a flag is chosen.
  34  *
  35  * Revision 1.5  1994/03/19  14:25:16  johnsonm
  36  * Removed silly two-process model.  Must have been half asleep when
  37  * I came up with that idea.  vlock works now.
  38  *
  39  * Revision 1.4  1994/03/16  20:14:06  johnsonm
  40  * Cleaned up, putting most real work into child functions, which
  41  * cleaned up the interface.  The whole program is almost all
  42  * working now.
  43  *
  44  * Revision 1.3  1994/03/15  18:27:33  johnsonm
  45  * Moved terminal handling stuff into terminal.c, and changed the
  46  * end to support a two-process model for async I/O.
  47  *
  48  * Revision 1.2  1994/03/13  17:28:56  johnsonm
  49  * Now using SIGUSR{1,2} correctly to announce VC switches.  Fixed a few
  50  * other minor bugs.
  51  *
  52  * Revision 1.1  1994/03/13  16:28:16  johnsonm
  53  * Initial revision
  54  *
  55  */
  56
  57
  58 #include <stdio.h>
  59 #include <unistd.h>
  60 #include <fcntl.h>
  61 #include <getopt.h>
  62 #include <termios.h>
  63 #include <signal.h>
  64 #include <sys/vt.h>
  65 #include <sys/kd.h>
  66 #include <sys/ioctl.h>
  67 #include "vlock.h"
  68 #include "version.h"
  69
  70
  71 static char rcsid[] = "$Id: vlock.c,v 1.12 1996/05/17 02:52:03 johnsonm Exp $";
  72
  73 /* Option globals */
  74   /* This determines whether the default behavior is to lock only the */
  75   /* current VT or all of them.  0 means current, 1 means all. */
  76   int o_lock_all = 0;
  77
  78 /* Other globals */
  79   struct vt_mode ovtm;
  80   struct termios oterm;
  81   int vfd;
  82   int is_vt;
  83
  84 int main(int argc, char **argv) {
  85
  86   static struct option long_options[] = { /* For parsing long arguments */
  87     {"current", 0, &o_lock_all, 0},
  88     {"all", 0, &o_lock_all, 1},
  89     {"version", no_argument, 0, O_VERSION},
  90     {"help", no_argument, 0, O_HELP},
  91     {0, 0, 0, 0},
  92   };
  93   int option_index; /* Unused */
  94   int c;
  95   struct vt_mode vtm;
  96
  97   /* First we parse all the command line arguments */
  98   while ((c = getopt_long(argc, argv, "acvh",
  99                           long_options, &option_index)) != -1) {
 100     switch(c) {
 101     case 'c':
 102       o_lock_all = 0;
 103       break;
 104     case 'a':
 105       o_lock_all = 1;
 106       break;
 107     case 'v':
 108     case O_VERSION:
 109       fprintf(stderr, VERSION);
 110       exit(0);
 111       break;
 112     case 'h':
 113     case O_HELP:
 114       print_help(0);
 115       break;
 116     case '?':
 117       print_help(1);
 118       break;
 119     }
 120   }
 121
 122   /* Now we have parsed the options, and can get on with life */
 123
 124   /* Get the user's and root's encrypted passwords.  This needs
 125      to run as root when using shadow passwords, but will drop
 126      root privileges as soon as they are no longer needed.  */
 127   init_passwords();
 128
 129   if ((vfd = open("/dev/tty", O_RDWR)) < 0) {
 130     perror("vlock: could not open /dev/tty");
 131     exit (1);
 132   }
 133
 134   /* First we will set process control of VC switching; if this fails, */
 135   /* then we know that we aren't on a VC, and will print a warning message */
 136   /* If it doesn't fail, it gets the current VT status... */
 137   c = ioctl(vfd, VT_GETMODE, &vtm);
 138   if (c < 0) {
 139     fprintf(stderr, " *** This tty is not a VC (virtual console). ***\n"
 140             " *** It may not be securely locked. ***\n\n");
 141     is_vt = 0;
 142     o_lock_all = 0;
 143   } else {
 144     is_vt = 1;
 145   }
 146
 147   /* Now set the signals so we can't be summarily executed or stopped, */
 148   /* and handle SIGUSR{1,2} and SIGCHLD */
 149   mask_signals();
 150
 151   if (is_vt) {
 152     ovtm = vtm; /* Keep a copy around to restore at appropriate times */
 153     vtm.mode = VT_PROCESS;
 154     vtm.relsig = SIGUSR1; /* handled by release_vt() */
 155     vtm.acqsig = SIGUSR2; /* handled by acquire_vt() */
 156     ioctl(vfd, VT_SETMODE, &vtm);
 157   }
 158
 159   /* get_password() sets the terminal characteristics and does not */
 160   /* return until the correct password has been read.              */
 161   get_password();
 162
 163   /* vt status was restored in restore_terminal() already... */
 164
 165   /* we should really return something... */
 166   return (0);
 167
 168 }
 169