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/*
* This program is designed to run with sufficient privilege
* to read and write all of the unix password databases.
* Its purpose is to allow updating the databases when
* SELinux confinement of the caller domain prevents them to
* do that themselves.
*
* The password is read from the standard input. The exit status of
* this program indicates whether the password was updated or not.
*
* Copyright information is located at the end of the file.
*
*/
#include "config.h"
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <pwd.h>
#include <shadow.h>
#include <signal.h>
#include <time.h>
#include <sys/time.h>
#include <security/_pam_types.h>
#include <security/_pam_macros.h>
#include "passverify.h"
static int
set_password(const char *forwho, const char *shadow, const char *remember)
{
struct passwd *pwd = NULL;
int retval;
char pass[MAXPASS + 1];
char towhat[MAXPASS + 1];
int npass = 0;
/* we don't care about number format errors because the helper
should be called internally only */
int doshadow = atoi(shadow);
int nremember = atoi(remember);
char *passwords[] = { pass, towhat };
/* read the password from stdin (a pipe from the pam_unix module) */
npass = read_passwords(STDIN_FILENO, 2, passwords);
if (npass != 2) { /* is it a valid password? */
if (npass == 1) {
helper_log_err(LOG_DEBUG, "no new password supplied");
memset(pass, '\0', MAXPASS);
} else {
helper_log_err(LOG_DEBUG, "no valid passwords supplied");
}
return PAM_AUTHTOK_ERR;
}
if (lock_pwdf() != PAM_SUCCESS)
return PAM_AUTHTOK_LOCK_BUSY;
pwd = getpwnam(forwho);
if (pwd == NULL) {
retval = PAM_USER_UNKNOWN;
goto done;
}
/* If real caller uid is not root we must verify that
received old pass agrees with the current one.
We always allow change from null pass. */
if (getuid()) {
retval = helper_verify_password(forwho, pass, 1);
if (retval != PAM_SUCCESS) {
goto done;
}
}
/* first, save old password */
if (save_old_password(forwho, pass, nremember)) {
retval = PAM_AUTHTOK_ERR;
goto done;
}
if (doshadow || is_pwd_shadowed(pwd)) {
retval = unix_update_shadow(forwho, towhat);
if (retval == PAM_SUCCESS)
if (!is_pwd_shadowed(pwd))
retval = unix_update_passwd(forwho, "x");
} else {
retval = unix_update_passwd(forwho, towhat);
}
done:
memset(pass, '\0', MAXPASS);
memset(towhat, '\0', MAXPASS);
unlock_pwdf();
if (retval == PAM_SUCCESS) {
return PAM_SUCCESS;
} else {
return PAM_AUTHTOK_ERR;
}
}
int main(int argc, char *argv[])
{
char *option;
/*
* Catch or ignore as many signal as possible.
*/
setup_signals();
/*
* we establish that this program is running with non-tty stdin.
* this is to discourage casual use. It does *NOT* prevent an
* intruder from repeatadly running this program to determine the
* password of the current user (brute force attack, but one for
* which the attacker must already have gained access to the user's
* account).
*/
if (isatty(STDIN_FILENO) || argc != 5 ) {
helper_log_err(LOG_NOTICE
,"inappropriate use of Unix helper binary [UID=%d]"
,getuid());
fprintf(stderr
,"This binary is not designed for running in this way\n"
"-- the system administrator has been informed\n");
sleep(10); /* this should discourage/annoy the user */
return PAM_SYSTEM_ERR;
}
/* We must be root to read/update shadow.
*/
if (geteuid() != 0) {
return PAM_CRED_INSUFFICIENT;
}
option = argv[2];
if (strcmp(option, "update") == 0) {
/* Attempting to change the password */
return set_password(argv[1], argv[3], argv[4]);
}
return PAM_SYSTEM_ERR;
}
/*
* Copyright (c) Andrew G. Morgan, 1996. All rights reserved
* Copyright (c) Red Hat, Inc., 2007, 2008. 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, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 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 author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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.
*/
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