shadow/libmisc/valid.c

98 lines
3.3 KiB
C

/*
* Copyright 1989 - 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>
#ident "$Id: valid.c,v 1.6 2005/08/31 17:24:58 kloczek Exp $"
#include <sys/types.h>
#include <stdio.h>
#include "prototypes.h"
#include "defines.h"
#include <pwd.h>
/*
* valid - compare encrypted passwords
*
* Valid() compares the DES encrypted password from the password file
* against the password which the user has entered after it has been
* encrypted using the same salt as the original. Entries which do
* not have a password file entry have a NULL pw_name field and this
* is used to indicate that a dummy salt must be used to encrypt the
* password anyway.
*/
int valid (const char *password, const struct passwd *ent)
{
const char *encrypted;
const char *salt;
/*
* Start with blank or empty password entries. Always encrypt
* a password if no such user exists. Only if the ID exists and
* the password is really empty do you return quickly. This
* routine is meant to waste CPU time.
*/
if (ent->pw_name && !ent->pw_passwd[0]) {
if (!password[0])
return (1); /* user entered nothing */
else
return (0); /* user entered something! */
}
/*
* If there is no entry then we need a salt to use.
*/
if (ent->pw_name == (char *) 0 || ent->pw_passwd[0] == '\0') {
salt = "xx";
} else {
salt = ent->pw_passwd;
}
/*
* Now, perform the encryption using the salt from before on
* the users input. Since we always encrypt the string, it
* should be very difficult to determine if the user exists by
* looking at execution time.
*/
encrypted = pw_encrypt (password, salt);
/*
* One last time we must deal with there being no password file
* entry for the user. We use the pw_name == NULL idiom to
* cause non-existent users to not be validated.
*/
if (ent->pw_name && strcmp (encrypted, ent->pw_passwd) == 0)
return (1);
else
return (0);
}