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obscure.c

/*
 * Copyright 1989 - 1994, 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("$Id: obscure.c 6 2005-03-20 15:34:28Z bubulle $")

/*
 * This version of obscure.c contains modifications to support "cracklib"
 * by Alec Muffet (alec.muffett@uk.sun.com).  You must obtain the Cracklib
 * library source code for this function to operate.
 */

#include <ctype.h>
#include <stdio.h>
#include "prototypes.h"
#include "defines.h"

#include "getdef.h"

/*
 * can't be a palindrome - like `R A D A R' or `M A D A M'
 */

/*ARGSUSED*/
static int
palindrome(const char *old, const char *new)
{
      int   i, j;

      i = strlen (new);

      for (j = 0;j < i;j++)
            if (new[i - j - 1] != new[j])
                  return 0;

      return 1;
}

/*
 * more than half of the characters are different ones.
 */

/*ARGSUSED*/
static int
similar(const char *old, const char *new)
{
      int i, j;

      /*
       * XXX - sometimes this fails when changing from a simple password
       * to a really long one (MD5).  For now, I just return success if
       * the new password is long enough.  Please feel free to suggest
       * something better...  --marekm
       */
      if (strlen(new) >= 8)
            return 0;

      for (i = j = 0; new[i] && old[i]; i++)
            if (strchr(new, old[i]))
                  j++;

      if (i >= j * 2)
            return 0;

      return 1;
}

/*
 * a nice mix of characters.
 */

/*ARGSUSED*/
static int
simple(const char *old, const char *new)
{
      int   digits = 0;
      int   uppers = 0;
      int   lowers = 0;
      int   others = 0;
      int   size;
      int   i;

      for (i = 0;new[i];i++) {
            if (isdigit (new[i]))
                  digits++;
            else if (isupper (new[i]))
                  uppers++;
            else if (islower (new[i]))
                  lowers++;
            else
                  others++;
      }

      /*
       * The scam is this - a password of only one character type
       * must be 8 letters long.  Two types, 7, and so on.
       */

      size = 9;
      if (digits) size--;
      if (uppers) size--;
      if (lowers) size--;
      if (others) size--;

      if (size <= i)
            return 0;

      return 1;
}

static char *
str_lower(char *string)
{
      char *cp;

      for (cp = string; *cp; cp++)
            *cp = tolower(*cp);
      return string;
}

static const char *
password_check(const char *old, const char *new, const struct passwd *pwdp)
{
      const char *msg = NULL;
      char *oldmono, *newmono, *wrapped;
#ifdef HAVE_LIBCRACK
      char *dictpath;
#ifdef HAVE_LIBCRACK_PW
      char *FascistCheckPw();
#else
      char *FascistCheck();
#endif
#endif

      if (strcmp(new, old) == 0)
            return "no change";

      newmono = str_lower(xstrdup(new));
      oldmono = str_lower(xstrdup(old));
      wrapped = xmalloc(strlen(oldmono) * 2 + 1);
      strcpy (wrapped, oldmono);
      strcat (wrapped, oldmono);

      if (palindrome(oldmono, newmono))
            msg = "a palindrome";

      if (!msg && strcmp(oldmono, newmono) == 0)
            msg = "case changes only";

      if (!msg && similar(oldmono, newmono))
            msg = "too similar";

      if (!msg && simple(old, new))
            msg = "too simple";

      if (!msg && strstr(wrapped, newmono))
            msg = "rotated";

#ifdef HAVE_LIBCRACK
      /*
       * Invoke Alec Muffett's cracklib routines.
       */

      if (!msg && (dictpath = getdef_str("CRACKLIB_DICTPATH")))
#ifdef HAVE_LIBCRACK_PW
            msg = FascistCheckPw(new, dictpath, pwdp);
#else
            msg = FascistCheck(new, dictpath);
#endif
#endif
      strzero(newmono);
      strzero(oldmono);
      strzero(wrapped);
      free(newmono);
      free(oldmono);
      free(wrapped);

      return msg;
}

/*ARGSUSED*/
static const char *
obscure_msg(const char *old, const char *new, const struct passwd *pwdp)
{
      int maxlen, oldlen, newlen;
      char *new1, *old1;
      const char *msg;

      oldlen = strlen(old);
      newlen = strlen(new);

#if 0  /* why not check the password when set for the first time?  --marekm */
      if (old[0] == '\0')
            return NULL;
#endif

      if ( newlen < getdef_num("PASS_MIN_LEN", 0) )
            return "too short";

      /*
       * Remaining checks are optional.
       */
      if (!getdef_bool("OBSCURE_CHECKS_ENAB"))
            return NULL;

      msg = password_check(old, new, pwdp);
      if (msg)
            return msg;

      /* The traditional crypt() truncates passwords to 8 chars.  It is
         possible to circumvent the above checks by choosing an easy
         8-char password and adding some random characters to it...
         Example: "password$%^&*123".  So check it again, this time
         truncated to the maximum length.  Idea from npasswd.  --marekm */

      if (getdef_bool("MD5_CRYPT_ENAB"))
            return NULL;  /* unlimited password length */

      maxlen = getdef_num("PASS_MAX_LEN", 8);
      if (oldlen <= maxlen && newlen <= maxlen)
            return NULL;

      new1 = xstrdup(new);
      old1 = xstrdup(old);
      if (newlen > maxlen)
            new1[maxlen] = '\0';
      if (oldlen > maxlen)
            old1[maxlen] = '\0';

      msg = password_check(old1, new1, pwdp);

      memzero(new1, newlen);
      memzero(old1, oldlen);
      free(new1);
      free(old1);

      return msg;
}

/*
 * Obscure - see if password is obscure enough.
 *
 *    The programmer is encouraged to add as much complexity to this
 *    routine as desired.  Included are some of my favorite ways to
 *    check passwords.
 */

int
obscure(const char *old, const char *new, const struct passwd *pwdp)
{
      const char *msg = obscure_msg(old, new, pwdp);
      if (msg) {
            printf(_("Bad password: %s.  "), msg);
            return 0;
      }
      return 1;
}


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