/*
* Copyright (c) 2008, 2012 Thorsten Kukuk
* Author: Thorsten Kukuk <kukuk@thkukuk.de>
* Copyright (c) 2013 Red Hat, Inc.
*
* 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.
*/
#if defined(HAVE_CONFIG_H)
#include <config.h>
#endif
#define PAM_SM_PASSWORD
#include <pwd.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <signal.h>
#include <fcntl.h>
#include <security/pam_modules.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
#include <security/_pam_macros.h>
#include "opasswd.h"
#define DEFAULT_BUFLEN 2048
#define MAX_FD_NO 20000
struct options_t {
int debug;
int enforce_for_root;
int remember;
int tries;
};
typedef struct options_t options_t;
static void
parse_option (pam_handle_t *pamh, const char *argv, options_t *options)
{
if (strcasecmp (argv, "try_first_pass") == 0)
/* ignore */;
else if (strcasecmp (argv, "use_first_pass") == 0)
/* ignore */;
else if (strcasecmp (argv, "use_authtok") == 0)
/* ignore, handled by pam_get_authtok */;
else if (strcasecmp (argv, "debug") == 0)
options->debug = 1;
else if (strncasecmp (argv, "remember=", 9) == 0)
{
options->remember = strtol(&argv[9], NULL, 10);
if (options->remember < 0)
options->remember = 0;
if (options->remember > 400)
options->remember = 400;
}
else if (strncasecmp (argv, "retry=", 6) == 0)
{
options->tries = strtol(&argv[6], NULL, 10);
if (options->tries < 0)
options->tries = 1;
}
else if (strcasecmp (argv, "enforce_for_root") == 0)
options->enforce_for_root = 1;
else if (strncasecmp (argv, "authtok_type=", 13) == 0)
{ /* ignore, for pam_get_authtok */; }
else
pam_syslog (pamh, LOG_ERR, "pam_pwhistory: unknown option: %s", argv);
}
static int
run_save_helper(pam_handle_t *pamh, const char *user,
int howmany, int debug)
{
int retval, child;
struct sigaction newsa, oldsa;
memset(&newsa, '\0', sizeof(newsa));
newsa.sa_handler = SIG_DFL;
sigaction(SIGCHLD, &newsa, &oldsa);
child = fork();
if (child == 0)
{
int i = 0;
struct rlimit rlim;
int dummyfds[2];
static char *envp[] = { NULL };
char *args[] = { NULL, NULL, NULL, NULL, NULL, NULL };
/* replace std file descriptors with a dummy pipe */
if (pipe2(dummyfds, O_NONBLOCK) == 0)
{
dup2(dummyfds[0], STDIN_FILENO);
dup2(dummyfds[1], STDOUT_FILENO);
dup2(dummyfds[1], STDERR_FILENO);
}
if (getrlimit(RLIMIT_NOFILE,&rlim) == 0)
{
if (rlim.rlim_max >= MAX_FD_NO)
rlim.rlim_max = MAX_FD_NO;
for (i = STDERR_FILENO + 1; i < (int)rlim.rlim_max; i++)
{
if (i != dummyfds[0])
close(i);
}
}
/* exec binary helper */
args[0] = strdup(PWHISTORY_HELPER);
args[1] = strdup("save");
args[2] = x_strdup(user);
asprintf(&args[3], "%d", howmany);
asprintf(&args[4], "%d", debug);
execve(args[0], args, envp);
_exit(PAM_SYSTEM_ERR);
}
else if (child > 0)
{
/* wait for child */
int rc = 0;
rc = waitpid(child, &retval, 0); /* wait for helper to complete */
if (rc < 0)
{
pam_syslog(pamh, LOG_ERR, "pwhistory_helper save waitpid returned %d: %m", rc);
retval = PAM_SYSTEM_ERR;
}
else if (!WIFEXITED(retval))
{
pam_syslog(pamh, LOG_ERR, "pwhistory_helper save abnormal exit: %d", retval);
retval = PAM_SYSTEM_ERR;
}
else
{
retval = WEXITSTATUS(retval);
}
}
else
{
retval = PAM_SYSTEM_ERR;
}
sigaction(SIGCHLD, &oldsa, NULL); /* restore old signal handler */
return retval;
}
static int
run_check_helper(pam_handle_t *pamh, const char *user,
const char *newpass, int debug)
{
int retval, child, fds[2];
struct sigaction newsa, oldsa;
/* create a pipe for the password */
if (pipe(fds) != 0)
return PAM_SYSTEM_ERR;
memset(&newsa, '\0', sizeof(newsa));
newsa.sa_handler = SIG_DFL;
sigaction(SIGCHLD, &newsa, &oldsa);
child = fork();
if (child == 0)
{
int i = 0;
struct rlimit rlim;
int dummyfds[2];
static char *envp[] = { NULL };
char *args[] = { NULL, NULL, NULL, NULL, NULL };
/* reopen stdin as pipe */
dup2(fds[0], STDIN_FILENO);
/* replace std file descriptors with a dummy pipe */
if (pipe2(dummyfds, O_NONBLOCK) == 0)
{
dup2(dummyfds[1], STDOUT_FILENO);
dup2(dummyfds[1], STDERR_FILENO);
}
if (getrlimit(RLIMIT_NOFILE,&rlim) == 0)
{
if (rlim.rlim_max >= MAX_FD_NO)
rlim.rlim_max = MAX_FD_NO;
for (i = STDERR_FILENO + 1; i < (int)rlim.rlim_max; i++)
{
if (i != dummyfds[0])
close(i);
}
}
/* exec binary helper */
args[0] = strdup(PWHISTORY_HELPER);
args[1] = strdup("check");
args[2] = x_strdup(user);
asprintf(&args[3], "%d", debug);
execve(args[0], args, envp);
_exit(PAM_SYSTEM_ERR);
}
else if (child > 0)
{
/* wait for child */
int rc = 0;
if (newpass == NULL)
newpass = "";
/* send the password to the child */
if (write(fds[1], newpass, strlen(newpass)+1) == -1)
{
pam_syslog(pamh, LOG_ERR, "Cannot send password to helper: %m");
retval = PAM_SYSTEM_ERR;
}
newpass = NULL;
close(fds[0]); /* close here to avoid possible SIGPIPE above */
close(fds[1]);
rc = waitpid(child, &retval, 0); /* wait for helper to complete */
if (rc < 0)
{
pam_syslog(pamh, LOG_ERR, "pwhistory_helper check waitpid returned %d: %m", rc);
retval = PAM_SYSTEM_ERR;
}
else if (!WIFEXITED(retval))
{
pam_syslog(pamh, LOG_ERR, "pwhistory_helper check abnormal exit: %d", retval);
retval = PAM_SYSTEM_ERR;
}
else
{
retval = WEXITSTATUS(retval);
}
}
else
{
close(fds[0]);
close(fds[1]);
retval = PAM_SYSTEM_ERR;
}
sigaction(SIGCHLD, &oldsa, NULL); /* restore old signal handler */
return retval;
}
/* This module saves the current crypted password in /etc/security/opasswd
and then compares the new password with all entries in this file. */
int
pam_sm_chauthtok (pam_handle_t *pamh, int flags, int argc, const char **argv)
{
const char *newpass;
const char *user;
int retval, tries;
options_t options;
memset (&options, 0, sizeof (options));
/* Set some default values, which could be overwritten later. */
options.remember = 10;
options.tries = 1;
/* Parse parameters for module */
for ( ; argc-- > 0; argv++)
parse_option (pamh, *argv, &options);
if (options.debug)
pam_syslog (pamh, LOG_DEBUG, "pam_sm_chauthtok entered");
if (options.remember == 0)
return PAM_IGNORE;
retval = pam_get_user (pamh, &user, NULL);
if (retval != PAM_SUCCESS)
return retval;
if (user == NULL || strlen (user) == 0)
{
if (options.debug)
pam_syslog (pamh, LOG_DEBUG,
"User is not known to system");
return PAM_USER_UNKNOWN;
}
if (flags & PAM_PRELIM_CHECK)
{
if (options.debug)
pam_syslog (pamh, LOG_DEBUG,
"pam_sm_chauthtok(PAM_PRELIM_CHECK)");
return PAM_SUCCESS;
}
retval = save_old_pass (pamh, user, options.remember, options.debug);
if (retval == PAM_PWHISTORY_RUN_HELPER)
retval = run_save_helper(pamh, user, options.remember, options.debug);
if (retval != PAM_SUCCESS)
return retval;
newpass = NULL;
tries = 0;
while ((newpass == NULL) && (tries < options.tries))
{
retval = pam_get_authtok (pamh, PAM_AUTHTOK, &newpass, NULL);
if (retval != PAM_SUCCESS && retval != PAM_TRY_AGAIN)
{
if (retval == PAM_CONV_AGAIN)
retval = PAM_INCOMPLETE;
return retval;
}
tries++;
if (options.debug)
{
if (newpass)
pam_syslog (pamh, LOG_DEBUG, "got new auth token");
else
pam_syslog (pamh, LOG_DEBUG, "got no auth token");
}
if (newpass == NULL || retval == PAM_TRY_AGAIN)
continue;
if (options.debug)
pam_syslog (pamh, LOG_DEBUG, "check against old password file");
retval = check_old_pass (pamh, user, newpass, options.debug);
if (retval == PAM_PWHISTORY_RUN_HELPER)
retval = run_check_helper(pamh, user, newpass, options.debug);
if (retval != PAM_SUCCESS)
{
if (getuid() || options.enforce_for_root ||
(flags & PAM_CHANGE_EXPIRED_AUTHTOK))
{
pam_error (pamh,
_("Password has been already used. Choose another."));
newpass = NULL;
/* Remove password item, else following module will use it */
pam_set_item (pamh, PAM_AUTHTOK, (void *) NULL);
}
else
pam_info (pamh,
_("Password has been already used."));
}
}
if (newpass == NULL && tries >= options.tries)
{
if (options.debug)
pam_syslog (pamh, LOG_DEBUG, "Aborted, too many tries");
return PAM_MAXTRIES;
}
return PAM_SUCCESS;
}