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Diffstat (limited to 'libmisc/valid.c')
| -rw-r--r-- | libmisc/valid.c | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/libmisc/valid.c b/libmisc/valid.c new file mode 100644 index 00000000..1cfe2392 --- /dev/null +++ b/libmisc/valid.c @@ -0,0 +1,104 @@ +/* + * Copyright (c) 1989 - 1993, Julianne Frances Haugh + * Copyright (c) 1996 - 1999, Marek Michałkiewicz + * Copyright (c) 2003 - 2005, Tomasz Kłoczko + * Copyright (c) 2007 - 2008, Nicolas François + * 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. The name of the copyright holders or contributors may not be used to + * endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 THE COPYRIGHT + * HOLDERS 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 3232 2010-08-22 19:13:53Z nekral-guest $" + +#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. + */ +bool valid (const char *password, const struct passwd *ent) +{ + const char *encrypted; + /*@observer@*/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 ((NULL != ent->pw_name) && ('\0' == ent->pw_passwd[0])) { + if ('\0' == password[0]) { + return true; /* user entered nothing */ + } else { + return false; /* user entered something! */ + } + } + + /* + * If there is no entry then we need a salt to use. + */ + + if ((NULL == ent->pw_name) || ('\0' == ent->pw_passwd[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 ( (NULL != ent->pw_name) + && (strcmp (encrypted, ent->pw_passwd) == 0)) { + return true; + } else { + return false; + } +} + |