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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/>.
*/
#include <stdio.h>
#include <unistd.h>
#include <security/pam_appl.h>
#include <security/pam_misc.h>
#include "config.h"
#include "pam.h"
#define __failed(RC) ((RC) != PAM_SUCCESS)
/**
* The PAM handle
*/
static pam_handle_t* handle = NULL;
/**
* The PAM convention
*/
static struct pam_conv conv = { misc_conv, NULL };
/**
* Exit if a PAM instruction failed
*
* @param rc What the PAM instruction return
*/
static void do_pam(int rc)
{
if (__failed(rc))
{
const char* msg = pam_strerror(handle, rc);
if (msg)
fprintf(stderr, "%s\n", msg);
pam_end(handle, rc);
sleep(ERROR_SLEEP);
_exit(1);
}
}
/**
* Initialise PAM
*
* @param remote The remote computer, {@code NULL} for local login
* @param username The username of the user to log in to
*/
void initialise_pam(char* remote, char* username)
{
if (pam_start(remote ? "remote" : "local", username, &conv, &handle) != PAM_SUCCESS)
{
fprintf(stderr, "Cannot initialise PAM\n");
sleep(ERROR_SLEEP);
_exit(1);
}
do_pam(pam_set_item(handle, PAM_RHOST, remote ?: "localhost"));
do_pam(pam_set_item(handle, PAM_TTY, ttyname(STDIN_FILENO) ?: "(none)"));
}
/**
* Verify that the account may be used
*/
void verify_account_pam(void)
{
int rc = pam_acct_mgmt(handle, 0);
if (rc == PAM_NEW_AUTHTOK_REQD)
rc = pam_chauthtok(handle, PAM_CHANGE_EXPIRED_AUTHTOK);
do_pam(rc);
}
/**
* Open PAM session
*/
void open_session_pam(void)
{
int rc;
do_pam(pam_setcred(handle, PAM_ESTABLISH_CRED));
if (__failed(rc = pam_open_session(handle, 0)))
{
pam_setcred(handle, PAM_DELETE_CRED);
do_pam(rc);
}
if (__failed(rc = pam_setcred(handle, PAM_REINITIALIZE_CRED)))
{
pam_close_session(handle, 0);
do_pam(rc);
}
}
/**
* Close PAM session
*/
void close_session_pam(void)
{
pam_setcred(handle, PAM_DELETE_CRED);
pam_end(handle, pam_close_session(handle, 0));
}
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