src/auth-shadow.c

   1 /* auth-shadow.c -- shadow authentification routine for vlock,
   2  *                  the VT locking program for linux
   3  *
   4  * This program is copyright (C) 2007 Frank Benkstein, and is free
   5  * software which is freely distributable under the terms of the
   6  * GNU General Public License version 2, included as the file COPYING in this
   7  * distribution.  It is NOT public domain software, and any
   8  * redistribution not permitted by the GNU General Public License is
   9  * expressly forbidden without prior written permission from
  10  * the author.
  11  *
  12  */
  13
  14 /* for crypt() */
  15 #define _XOPEN_SOURCE
  16
  17 #ifndef __FreeBSD__
  18 /* for asprintf() */
  19 #define _GNU_SOURCE
  20 #endif
  21
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <termios.h>
  28
  29 #include <sys/mman.h>
  30
  31 #include <shadow.h>
  32
  33 #include "vlock.h"
  34
  35 int auth(const char *user, const struct timespec *timeout) {
  36   char *pwd;
  37   char *cryptpw;
  38   char *msg = NULL;
  39   struct spwd *spw;
  40   int result = 0;
  41
  42   /* format the prompt */
  43   (void) asprintf(&msg, "%s's Password: ", user);
  44
  45   if ((pwd = prompt_echo_off(msg, timeout)) == NULL)
  46     goto out;
  47
  48   /* get the shadow password */
  49   if ((spw = getspnam(user)) == NULL)
  50     goto out_shadow;
  51
  52   /* hash the password */
  53   if ((cryptpw = crypt(pwd, spw->sp_pwdp)) == NULL) {
  54     perror("vlock-auth: crypt()");
  55     goto out_shadow;
  56   }
  57
  58   result = (strcmp(cryptpw, spw->sp_pwdp) == 0);
  59
  60   if (!result) {
  61     sleep(1);
  62     fprintf(stderr, "vlock-auth: Authentication error\n");
  63   }
  64
  65 out_shadow:
  66   /* deallocate shadow resources */
  67   endspent();
  68
  69 out:
  70   /* free the prompt */
  71   free(msg);
  72
  73   /* free the password */
  74   free(pwd);
  75
  76   return result;
  77 }