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/**
* cerberus – Minimal login program
*
* Copyright © 2013 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef NO_SHADOW
# ifndef HAVE_SHADOW
# define HAVE_SHADOW
# endif
#endif
#define _XOPEN_SOURCE
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>
#include <string.h>
#include <termios.h>
#ifdef HAVE_SHADOW
#include <shadow.h>
#endif
#include "../config.h"
#include "crypt.h"
#if !defined(__USE_SVID) && !defined(__USE_MISC) && !defined(__USE_XOPEN_EXTENDED)
#define endpwent() /* do nothing */
#endif
/**
* Function that can be used to read a passphrase from the terminal
*/
static char* (*passphrase_reader)(void) = NULL;
/**
* The username of the user to log in to
*/
static char* login_username;
/**
* Initialise crypt authentication module
*
* @param remote The remote computer, {@code NULL} for local login
* @param username The username of the user to log in to
* @param reader Function that can be used to read a passphrase from the terminal
*/
void initialise_crypt(char* remote, char* username, char* (*reader)(void))
{
(void) remote;
login_username = username;
passphrase_reader = reader;
}
/**
* Perform token authentication
*
* @return Whether the user got automatically authenticated
*/
char authenticate_crypt(void)
{
#ifdef HAVE_SHADOW
struct spwd* shadow_entry = NULL;
#endif
struct passwd* passwd_entry = NULL;
char* crypted;
char* entered;
struct termios stty;
#ifdef HAVE_SHADOW
shadow_entry = getspnam(login_username);
endspent();
if (shadow_entry)
crypted = shadow_entry->sp_pwdp;
else
{
#endif
passwd_entry = getpwnam(login_username);
if (passwd_entry)
crypted = passwd_entry->pw_passwd;
else
{
perror("getpwnam");
endpwent();
sleep(ERROR_SLEEP);
_exit(1);
}
endpwent();
#ifdef HAVE_SHADOW
}
#endif
if (!(crypted && *crypted)) /* empty means that no passphrase is required (not even Enter) */
return 1;
entered = crypt(passphrase_reader(), crypted /* salt argument stops parsing when encrypted begins */);
if (entered && !strcmp(entered, crypted))
return 0;
/* Clear ISIG (and everything else) to prevent the user
* from skipping the brute force protection sleep. */
tcgetattr(STDIN_FILENO, &stty);
stty.c_lflag = 0;
tcsetattr(STDIN_FILENO, TCSAFLUSH, &stty);
printf("Incorrect passphrase\n");
sleep(FAILURE_SLEEP);
_exit(1);
}
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