/* 
   Unix SMB/CIFS implementation.
   Samba utility functions
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Andrew Bartlett 2001-2004
   
   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/>.
*/

/* These comments regard the code to change the user's unix password: */

/* fork a child process to exec passwd and write to its
 * tty to change a users password. This is running as the
 * user who is attempting to change the password.
 */

/*
 * This code was copied/borrowed and stolen from various sources.
 * The primary source was the poppasswd.c from the authors of POPMail. This software
 * was included as a client to change passwords using the 'passwd' program
 * on the remote machine.
 *
 * This code has been hacked by Bob Nance (nance@niehs.nih.gov) and Evan Patterson
 * (patters2@niehs.nih.gov) at the National Institute of Environmental Health Sciences
 * and rights to modify, distribute or incorporate this change to the CAP suite or
 * using it for any other reason are granted, so long as this disclaimer is left intact.
 */

/*
   This code was hacked considerably for inclusion in Samba, primarily
   by Andrew.Tridgell@anu.edu.au. The biggest change was the addition
   of the "password chat" option, which allows the easy runtime
   specification of the expected sequence of events to change a
   password.
   */

#include "includes.h"
#include "../libcli/auth/libcli_auth.h"

static NTSTATUS check_oem_password(const char *user,
				   uchar password_encrypted_with_lm_hash[516],
				   const uchar old_lm_hash_encrypted[16],
				   uchar password_encrypted_with_nt_hash[516],
				   const uchar old_nt_hash_encrypted[16],
				   struct samu *sampass,
				   char **pp_new_passwd);

#if ALLOW_CHANGE_PASSWORD

static int findpty(char **slave)
{
	int master = -1;
	char *line = NULL;
	SMB_STRUCT_DIR *dirp = NULL;
	const char *dpname;

	*slave = NULL;

#if defined(HAVE_GRANTPT)
	/* Try to open /dev/ptmx. If that fails, fall through to old method. */
	if ((master = sys_open("/dev/ptmx", O_RDWR, 0)) >= 0) {
		grantpt(master);
		unlockpt(master);
		line = (char *)ptsname(master);
		if (line) {
			*slave = SMB_STRDUP(line);
		}

		if (*slave == NULL) {
			DEBUG(0,
			      ("findpty: Unable to create master/slave pty pair.\n"));
			/* Stop fd leak on error. */
			close(master);
			return -1;
		} else {
			DEBUG(10,
			      ("findpty: Allocated slave pty %s\n", *slave));
			return (master);
		}
	}
#endif /* HAVE_GRANTPT */

	line = SMB_STRDUP("/dev/ptyXX");
	if (!line) {
		return (-1);
	}

	dirp = sys_opendir("/dev");
	if (!dirp) {
		SAFE_FREE(line);
		return (-1);
	}

	while ((dpname = readdirname(dirp)) != NULL) {
		if (strncmp(dpname, "pty", 3) == 0 && strlen(dpname) == 5) {
			DEBUG(3,
			      ("pty: try to open %s, line was %s\n", dpname,
			       line));
			line[8] = dpname[3];
			line[9] = dpname[4];
			if ((master = sys_open(line, O_RDWR, 0)) >= 0) {
				DEBUG(3, ("pty: opened %s\n", line));
				line[5] = 't';
				*slave = line;
				sys_closedir(dirp);
				return (master);
			}
		}
	}
	sys_closedir(dirp);
	SAFE_FREE(line);
	return (-1);
}

static int dochild(int master, const char *slavedev, const struct passwd *pass,
		   const char *passwordprogram, bool as_root)
{
	int slave;
	struct termios stermios;
	gid_t gid;
	uid_t uid;
	char * const eptrs[1] = { NULL };

	if (pass == NULL)
	{
		DEBUG(0,
		      ("dochild: user doesn't exist in the UNIX password database.\n"));
		return False;
	}

	gid = pass->pw_gid;
	uid = pass->pw_uid;

	gain_root_privilege();

	/* Start new session - gets rid of controlling terminal. */
	if (setsid() < 0)
	{
		DEBUG(3,
		      ("Weirdness, couldn't let go of controlling terminal\n"));
		return (False);
	}

	/* Open slave pty and acquire as new controlling terminal. */
	if ((slave = sys_open(slavedev, O_RDWR, 0)) < 0)
	{
		DEBUG(3, ("More weirdness, could not open %s\n", slavedev));
		return (False);
	}
#if defined(TIOCSCTTY) && !defined(SUNOS5)
	/*
	 * On patched Solaris 10 TIOCSCTTY is defined but seems not to work,
	 * see the discussion under
	 * https://bugzilla.samba.org/show_bug.cgi?id=5366.
	 */
	if (ioctl(slave, TIOCSCTTY, 0) < 0)
	{
		DEBUG(3, ("Error in ioctl call for slave pty\n"));
		/* return(False); */
	}
#elif defined(I_PUSH) && defined(I_FIND)
	if (ioctl(slave, I_FIND, "ptem") == 0) {
		ioctl(slave, I_PUSH, "ptem");
	}
	if (ioctl(slave, I_FIND, "ldterm") == 0) {
		ioctl(slave, I_PUSH, "ldterm");
	}
#endif

	/* Close master. */
	close(master);

	/* Make slave stdin/out/err of child. */

	if (dup2(slave, STDIN_FILENO) != STDIN_FILENO)
	{
		DEBUG(3, ("Could not re-direct stdin\n"));
		return (False);
	}
	if (dup2(slave, STDOUT_FILENO) != STDOUT_FILENO)
	{
		DEBUG(3, ("Could not re-direct stdout\n"));
		return (False);
	}
	if (dup2(slave, STDERR_FILENO) != STDERR_FILENO)
	{
		DEBUG(3, ("Could not re-direct stderr\n"));
		return (False);
	}
	if (slave > 2)
		close(slave);

	/* Set proper terminal attributes - no echo, canonical input processing,
	   no map NL to CR/NL on output. */

	if (tcgetattr(0, &stermios) < 0)
	{
		DEBUG(3,
		      ("could not read default terminal attributes on pty\n"));
		return (False);
	}
	stermios.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
	stermios.c_lflag |= ICANON;
#ifdef ONLCR
 	stermios.c_oflag &= ~(ONLCR);
#endif
	if (tcsetattr(0, TCSANOW, &stermios) < 0)
	{
		DEBUG(3, ("could not set attributes of pty\n"));
		return (False);
	}

	/* make us completely into the right uid */
	if (!as_root)
	{
		become_user_permanently(uid, gid);
	}

	DEBUG(10,
	      ("Invoking '%s' as password change program.\n",
	       passwordprogram));

	/* execl() password-change application */
	if (execle("/bin/sh", "sh", "-c", passwordprogram, NULL, eptrs) < 0)
	{
		DEBUG(3, ("Bad status returned from %s\n", passwordprogram));
		return (False);
	}
	return (True);
}

static int expect(int master, char *issue, char *expected)
{
	char buffer[1024];
	int attempts, timeout, nread;
	size_t len;
	bool match = False;

	for (attempts = 0; attempts < 2; attempts++) {
		NTSTATUS status;
		if (!strequal(issue, ".")) {
			if (lp_passwd_chat_debug())
				DEBUG(100, ("expect: sending [%s]\n", issue));

			if ((len = sys_write(master, issue, strlen(issue))) != strlen(issue)) {
				DEBUG(2,("expect: (short) write returned %d\n",
					 (int)len ));
				return False;
			}
		}

		if (strequal(expected, "."))
			return True;

		/* Initial timeout. */
		timeout = lp_passwd_chat_timeout() * 1000;
		nread = 0;
		buffer[nread] = 0;

		while (True) {
			status = read_fd_with_timeout(
				master, buffer + nread, 1,
				sizeof(buffer) - nread - 1,
				timeout, &len);

			if (!NT_STATUS_IS_OK(status)) {
				break;
			}
			nread += len;
			buffer[nread] = 0;

			{
				/* Eat leading/trailing whitespace before match. */
				char *str = SMB_STRDUP(buffer);
				if (!str) {
					DEBUG(2,("expect: ENOMEM\n"));
					return False;
				}
				trim_char(str, ' ', ' ');

				if ((match = unix_wild_match(expected, str)) == True) {
					/* Now data has started to return, lower timeout. */
					timeout = lp_passwd_chat_timeout() * 100;
				}
				SAFE_FREE(str);
			}
		}

		if (lp_passwd_chat_debug())
			DEBUG(100, ("expect: expected [%s] received [%s] match %s\n",
				    expected, buffer, match ? "yes" : "no" ));

		if (match)
			break;

		if (!NT_STATUS_IS_OK(status)) {
			DEBUG(2, ("expect: %s\n", nt_errstr(status)));
			return False;
		}
	}

	DEBUG(10,("expect: returning %s\n", match ? "True" : "False" ));
	return match;
}

static void pwd_sub(char *buf)
{
	all_string_sub(buf, "\\n", "\n", 0);
	all_string_sub(buf, "\\r", "\r", 0);
	all_string_sub(buf, "\\s", " ", 0);
	all_string_sub(buf, "\\t", "\t", 0);
}

static int talktochild(int master, const char *seq)
{
	TALLOC_CTX *frame = talloc_stackframe();
	int count = 0;
	char *issue;
	char *expected;

	issue = talloc_strdup(frame, ".");
	if (!issue) {
		TALLOC_FREE(frame);
		return false;
	}

	while (next_token_talloc(frame, &seq, &expected, NULL)) {
		pwd_sub(expected);
		count++;

		if (!expect(master, issue, expected)) {
			DEBUG(3, ("Response %d incorrect\n", count));
			TALLOC_FREE(frame);
			return false;
		}

		if (!next_token_talloc(frame, &seq, &issue, NULL)) {
			issue = talloc_strdup(frame, ".");
			if (!issue) {
				TALLOC_FREE(frame);
				return false;
			}
		}
		pwd_sub(issue);
	}

	if (!strequal(issue, ".")) {
		/* we have one final issue to send */
		expected = talloc_strdup(frame, ".");
		if (!expected) {
			TALLOC_FREE(frame);
			return false;
		}
		if (!expect(master, issue, expected)) {
			TALLOC_FREE(frame);
			return False;
		}
	}
	TALLOC_FREE(frame);
	return (count > 0);
}

static bool chat_with_program(char *passwordprogram, const struct passwd *pass,
			      char *chatsequence, bool as_root)
{
	char *slavedev = NULL;
	int master;
	pid_t pid, wpid;
	int wstat;
	bool chstat = False;

	if (pass == NULL) {
		DEBUG(0, ("chat_with_program: user doesn't exist in the UNIX password database.\n"));
		return False;
	}

	/* allocate a pseudo-terminal device */
	if ((master = findpty(&slavedev)) < 0) {
		DEBUG(3, ("chat_with_program: Cannot Allocate pty for password change: %s\n", pass->pw_name));
		return (False);
	}

	/*
	 * We need to temporarily stop CatchChild from eating
	 * SIGCLD signals as it also eats the exit status code. JRA.
	 */

	CatchChildLeaveStatus();

	if ((pid = sys_fork()) < 0) {
		DEBUG(3, ("chat_with_program: Cannot fork() child for password change: %s\n", pass->pw_name));
		SAFE_FREE(slavedev);
		close(master);
		CatchChild();
		return (False);
	}

	/* we now have a pty */
	if (pid > 0) {			/* This is the parent process */
		/* Don't need this anymore in parent. */
		SAFE_FREE(slavedev);

		if ((chstat = talktochild(master, chatsequence)) == False) {
			DEBUG(3, ("chat_with_program: Child failed to change password: %s\n", pass->pw_name));
			kill(pid, SIGKILL);	/* be sure to end this process */
		}

		while ((wpid = sys_waitpid(pid, &wstat, 0)) < 0) {
			if (errno == EINTR) {
				errno = 0;
				continue;
			}
			break;
		}

		if (wpid < 0) {
			DEBUG(3, ("chat_with_program: The process is no longer waiting!\n\n"));
			close(master);
			CatchChild();
			return (False);
		}

		/*
		 * Go back to ignoring children.
		 */
		CatchChild();

		close(master);

		if (pid != wpid) {
			DEBUG(3, ("chat_with_program: We were waiting for the wrong process ID\n"));
			return (False);
		}
		if (WIFEXITED(wstat) && (WEXITSTATUS(wstat) != 0)) {
			DEBUG(3, ("chat_with_program: The process exited with status %d \
while we were waiting\n", WEXITSTATUS(wstat)));
			return (False);
		}
#if defined(WIFSIGNALLED) && defined(WTERMSIG)
		else if (WIFSIGNALLED(wstat)) {
                        DEBUG(3, ("chat_with_program: The process was killed by signal %d \
while we were waiting\n", WTERMSIG(wstat)));
			return (False);
		}
#endif
	} else {
		/* CHILD */

		/*
		 * Lose any elevated privileges.
		 */
		drop_effective_capability(KERNEL_OPLOCK_CAPABILITY);
		drop_effective_capability(DMAPI_ACCESS_CAPABILITY);

		/* make sure it doesn't freeze */
		alarm(20);

		if (as_root)
			become_root();

		DEBUG(3, ("chat_with_program: Dochild for user %s (uid=%d,gid=%d) (as_root = %s)\n", pass->pw_name,
		       (int)getuid(), (int)getgid(), BOOLSTR(as_root) ));
		chstat = dochild(master, slavedev, pass, passwordprogram, as_root);

		if (as_root)
			unbecome_root();

		/*
		 * The child should never return from dochild() ....
		 */

		DEBUG(0, ("chat_with_program: Error: dochild() returned %d\n", chstat));
		exit(1);
	}

	if (chstat)
		DEBUG(3, ("chat_with_program: Password change %ssuccessful for user %s\n",
		       (chstat ? "" : "un"), pass->pw_name));
	return (chstat);
}

bool chgpasswd(const char *name, const struct passwd *pass,
	       const char *oldpass, const char *newpass, bool as_root)
{
	char *passwordprogram = NULL;
	char *chatsequence = NULL;
	size_t i;
	size_t len;
	TALLOC_CTX *ctx = talloc_tos();

	if (!oldpass) {
		oldpass = "";
	}

	DEBUG(3, ("chgpasswd: Password change (as_root=%s) for user: %s\n", BOOLSTR(as_root), name));

#ifdef DEBUG_PASSWORD
	DEBUG(100, ("chgpasswd: Passwords: old=%s new=%s\n", oldpass, newpass));
#endif

	/* Take the passed information and test it for minimum criteria */

	/* Password is same as old password */
	if (strcmp(oldpass, newpass) == 0) {
		/* don't allow same password */
		DEBUG(2, ("chgpasswd: Password Change: %s, New password is same as old\n", name));	/* log the attempt */
		return (False);	/* inform the user */
	}

	/*
	 * Check the old and new passwords don't contain any control
	 * characters.
	 */

	len = strlen(oldpass);
	for (i = 0; i < len; i++) {
		if (iscntrl((int)oldpass[i])) {
			DEBUG(0, ("chgpasswd: oldpass contains control characters (disallowed).\n"));
			return False;
		}
	}

	len = strlen(newpass);
	for (i = 0; i < len; i++) {
		if (iscntrl((int)newpass[i])) {
			DEBUG(0, ("chgpasswd: newpass contains control characters (disallowed).\n"));
			return False;
		}
	}

#ifdef WITH_PAM
	if (lp_pam_password_change()) {
		bool ret;
#ifdef HAVE_SETLOCALE
		const char *prevlocale = setlocale(LC_ALL, "C");
#endif

		if (as_root)
			become_root();

		if (pass) {
			ret = smb_pam_passchange(pass->pw_name, oldpass, newpass);
		} else {
			ret = smb_pam_passchange(name, oldpass, newpass);
		}

		if (as_root)
			unbecome_root();

#ifdef HAVE_SETLOCALE
		setlocale(LC_ALL, prevlocale);
#endif

		return ret;
	}
#endif

	/* A non-PAM password change just doen't make sense without a valid local user */

	if (pass == NULL) {
		DEBUG(0, ("chgpasswd: user %s doesn't exist in the UNIX password database.\n", name));
		return false;
	}

	passwordprogram = talloc_strdup(ctx, lp_passwd_program());
	if (!passwordprogram || !*passwordprogram) {
		DEBUG(2, ("chgpasswd: Null password program - no password changing\n"));
		return false;
	}
	chatsequence = talloc_strdup(ctx, lp_passwd_chat());
	if (!chatsequence || !*chatsequence) {
		DEBUG(2, ("chgpasswd: Null chat sequence - no password changing\n"));
		return false;
	}

	if (as_root) {
		/* The password program *must* contain the user name to work. Fail if not. */
		if (strstr_m(passwordprogram, "%u") == NULL) {
			DEBUG(0,("chgpasswd: Running as root the 'passwd program' parameter *MUST* contain \
the string %%u, and the given string %s does not.\n", passwordprogram ));
			return false;
		}
	}

	passwordprogram = talloc_string_sub(ctx, passwordprogram, "%u", name);
	if (!passwordprogram) {
		return false;
	}

	/* note that we do NOT substitute the %o and %n in the password program
	   as this would open up a security hole where the user could use
	   a new password containing shell escape characters */

	chatsequence = talloc_string_sub(ctx, chatsequence, "%u", name);
	if (!chatsequence) {
		return false;
	}
	chatsequence = talloc_all_string_sub(ctx,
					chatsequence,
					"%o",
					oldpass);
	if (!chatsequence) {
		return false;
	}
	chatsequence = talloc_all_string_sub(ctx,
					chatsequence,
					"%n",
					newpass);
	return chat_with_program(passwordprogram,
				pass,
				chatsequence,
				as_root);
}

#else /* ALLOW_CHANGE_PASSWORD */

bool chgpasswd(const char *name, const struct passwd *pass, 
	       const char *oldpass, const char *newpass, bool as_root)
{
	DEBUG(0, ("chgpasswd: Unix Password changing not compiled in (user=%s)\n", name));
	return (False);
}
#endif /* ALLOW_CHANGE_PASSWORD */

/***********************************************************
 Code to check the lanman hashed password.
************************************************************/

bool check_lanman_password(char *user, uchar * pass1,
			   uchar * pass2, struct samu **hnd)
{
	uchar unenc_new_pw[16];
	uchar unenc_old_pw[16];
	struct samu *sampass = NULL;
	uint32 acct_ctrl;
	const uint8 *lanman_pw;
	bool ret;

	if ( !(sampass = samu_new(NULL)) ) {
		DEBUG(0, ("samu_new() failed!\n"));
		return False;
	}
	
	become_root();
	ret = pdb_getsampwnam(sampass, user);
	unbecome_root();

	if (ret == False) {
		DEBUG(0,("check_lanman_password: getsampwnam returned NULL\n"));
		TALLOC_FREE(sampass);
		return False;
	}
	
	acct_ctrl = pdb_get_acct_ctrl     (sampass);
	lanman_pw = pdb_get_lanman_passwd (sampass);

	if (acct_ctrl & ACB_DISABLED) {
		DEBUG(0,("check_lanman_password: account %s disabled.\n", user));
		TALLOC_FREE(sampass);
		return False;
	}

	if (lanman_pw == NULL) {
		if (acct_ctrl & ACB_PWNOTREQ) {
			/* this saves the pointer for the caller */
			*hnd = sampass;
			return True;
		} else {
			DEBUG(0, ("check_lanman_password: no lanman password !\n"));
			TALLOC_FREE(sampass);
			return False;
		}
	}

	/* Get the new lanman hash. */
	D_P16(lanman_pw, pass2, unenc_new_pw);

	/* Use this to get the old lanman hash. */
	D_P16(unenc_new_pw, pass1, unenc_old_pw);

	/* Check that the two old passwords match. */
	if (memcmp(lanman_pw, unenc_old_pw, 16)) {
		DEBUG(0,("check_lanman_password: old password doesn't match.\n"));
		TALLOC_FREE(sampass);
		return False;
	}

	/* this saves the pointer for the caller */
	*hnd = sampass;
	return True;
}

/***********************************************************
 Code to change the lanman hashed password.
 It nulls out the NT hashed password as it will
 no longer be valid.
 NOTE this function is designed to be called as root. Check the old password
 is correct before calling. JRA.
************************************************************/

bool change_lanman_password(struct samu *sampass, uchar *pass2)
{
	uchar null_pw[16];
	uchar unenc_new_pw[16];
	bool ret;
	uint32 acct_ctrl;
	const uint8 *pwd;

	if (sampass == NULL) {
		DEBUG(0,("change_lanman_password: no smb password entry.\n"));
		return False;
	}
	
	acct_ctrl = pdb_get_acct_ctrl(sampass);
	pwd = pdb_get_lanman_passwd(sampass);

	if (acct_ctrl & ACB_DISABLED) {
		DEBUG(0,("change_lanman_password: account %s disabled.\n",
		       pdb_get_username(sampass)));
		return False;
	}

	if (pwd == NULL) { 
		if (acct_ctrl & ACB_PWNOTREQ) {
			uchar no_pw[14];

			ZERO_STRUCT(no_pw);

			E_P16(no_pw, null_pw);

			pwd = null_pw;
		} else {
			DEBUG(0,("change_lanman_password: no lanman password !\n"));
			return False;
		}
	}

	/* Get the new lanman hash. */
	D_P16(pwd, pass2, unenc_new_pw);

	if (!pdb_set_lanman_passwd(sampass, unenc_new_pw, PDB_CHANGED)) {
		return False;
	}

	if (!pdb_set_nt_passwd    (sampass, NULL, PDB_CHANGED)) {
		return False;	/* We lose the NT hash. Sorry. */
	}

	if (!pdb_set_pass_last_set_time  (sampass, time(NULL), PDB_CHANGED)) {
		TALLOC_FREE(sampass);
		/* Not quite sure what this one qualifies as, but this will do */
		return False;
	}

	/* Now flush the sam_passwd struct to persistent storage */
	ret = NT_STATUS_IS_OK(pdb_update_sam_account (sampass));

	return ret;
}

/***********************************************************
 Code to check and change the OEM hashed password.
************************************************************/

NTSTATUS pass_oem_change(char *user,
			 uchar password_encrypted_with_lm_hash[516],
			 const uchar old_lm_hash_encrypted[16],
			 uchar password_encrypted_with_nt_hash[516],
			 const uchar old_nt_hash_encrypted[16],
			 uint32 *reject_reason)
{
	char *new_passwd = NULL;
	struct samu *sampass = NULL;
	NTSTATUS nt_status;
	bool ret = false;

	if (!(sampass = samu_new(NULL))) {
		return NT_STATUS_NO_MEMORY;
	}

	become_root();
	ret = pdb_getsampwnam(sampass, user);
	unbecome_root();

	if (ret == false) {
		DEBUG(0,("pass_oem_change: getsmbpwnam returned NULL\n"));
		TALLOC_FREE(sampass);
		return NT_STATUS_NO_SUCH_USER;
	}

	nt_status = check_oem_password(user,
				       password_encrypted_with_lm_hash,
				       old_lm_hash_encrypted,
				       password_encrypted_with_nt_hash,
				       old_nt_hash_encrypted,
				       sampass,
				       &new_passwd);

	if (!NT_STATUS_IS_OK(nt_status)) {
		TALLOC_FREE(sampass);
		return nt_status;
	}

	/* We've already checked the old password here.... */
	become_root();
	nt_status = change_oem_password(sampass, NULL, new_passwd, True, reject_reason);
	unbecome_root();

	memset(new_passwd, 0, strlen(new_passwd));

	TALLOC_FREE(sampass);

	return nt_status;
}

/***********************************************************
 Decrypt and verify a user password change.

 The 516 byte long buffers are encrypted with the old NT and
 old LM passwords, and if the NT passwords are present, both
 buffers contain a unicode string.

 After decrypting the buffers, check the password is correct by
 matching the old hashed passwords with the passwords in the passdb.

************************************************************/

static NTSTATUS check_oem_password(const char *user,
				   uchar password_encrypted_with_lm_hash[516],
				   const uchar old_lm_hash_encrypted[16],
				   uchar password_encrypted_with_nt_hash[516],
				   const uchar old_nt_hash_encrypted[16],
				   struct samu *sampass,
				   char **pp_new_passwd)
{
	uchar null_pw[16];
	uchar null_ntpw[16];
	uint8 *password_encrypted;
	const uint8 *encryption_key;
	const uint8 *lanman_pw, *nt_pw;
	uint32 acct_ctrl;
	size_t new_pw_len;
	uchar new_nt_hash[16];
	uchar new_lm_hash[16];
	uchar verifier[16];
	char no_pw[2];

	bool nt_pass_set = (password_encrypted_with_nt_hash && old_nt_hash_encrypted);
	bool lm_pass_set = (password_encrypted_with_lm_hash && old_lm_hash_encrypted);

	acct_ctrl = pdb_get_acct_ctrl(sampass);
#if 0
	/* I am convinced this check here is wrong, it is valid to
	 * change a password of a user that has a disabled account - gd */

	if (acct_ctrl & ACB_DISABLED) {
		DEBUG(2,("check_lanman_password: account %s disabled.\n", user));
		return NT_STATUS_ACCOUNT_DISABLED;
	}
#endif
	if ((acct_ctrl & ACB_PWNOTREQ) && lp_null_passwords()) {
		/* construct a null password (in case one is needed */
		no_pw[0] = 0;
		no_pw[1] = 0;
		nt_lm_owf_gen(no_pw, null_ntpw, null_pw);
		lanman_pw = null_pw;
		nt_pw = null_pw;

	} else {
		/* save pointers to passwords so we don't have to keep looking them up */
		if (lp_lanman_auth()) {
			lanman_pw = pdb_get_lanman_passwd(sampass);
		} else {
			lanman_pw = NULL;
		}
		nt_pw = pdb_get_nt_passwd(sampass);
	}

	if (nt_pw && nt_pass_set) {
		/* IDEAL Case: passwords are in unicode, and we can
		 * read use the password encrypted with the NT hash
		 */
		password_encrypted = password_encrypted_with_nt_hash;
		encryption_key = nt_pw;
	} else if (lanman_pw && lm_pass_set) {
		/* password may still be in unicode, but use LM hash version */
		password_encrypted = password_encrypted_with_lm_hash;
		encryption_key = lanman_pw;
	} else if (nt_pass_set) {
		DEBUG(1, ("NT password change supplied for user %s, but we have no NT password to check it with\n", 
			  user));
		return NT_STATUS_WRONG_PASSWORD;
	} else if (lm_pass_set) {
		if (lp_lanman_auth()) {
			DEBUG(1, ("LM password change supplied for user %s, but we have no LanMan password to check it with\n", 
				  user));
		} else {
			DEBUG(1, ("LM password change supplied for user %s, but we have disabled LanMan authentication\n", 
				  user));
		}
		return NT_STATUS_WRONG_PASSWORD;
	} else {
		DEBUG(1, ("password change requested for user %s, but no password supplied!\n", 
			  user));
		return NT_STATUS_WRONG_PASSWORD;
	}

	/*
	 * Decrypt the password with the key
	 */
	arcfour_crypt( password_encrypted, encryption_key, 516);

	if (!decode_pw_buffer(talloc_tos(),
				password_encrypted,
				pp_new_passwd,
				&new_pw_len,
				nt_pass_set ? CH_UTF16 : CH_DOS)) {
		return NT_STATUS_WRONG_PASSWORD;
	}

	/*
	 * To ensure we got the correct new password, hash it and
	 * use it as a key to test the passed old password.
	 */

	if (nt_pass_set) {
		/* NT passwords, verify the NT hash. */

		/* Calculate the MD4 hash (NT compatible) of the password */
		memset(new_nt_hash, '\0', 16);
		E_md4hash(*pp_new_passwd, new_nt_hash);

		if (nt_pw) {
			/*
			 * check the NT verifier
			 */
			E_old_pw_hash(new_nt_hash, nt_pw, verifier);
			if (memcmp(verifier, old_nt_hash_encrypted, 16)) {
				DEBUG(0,("check_oem_password: old lm password doesn't match.\n"));
				return NT_STATUS_WRONG_PASSWORD;
			}

			/* We could check the LM password here, but there is
			 * little point, we already know the password is
			 * correct, and the LM password might not even be
			 * present. */

			/* Further, LM hash generation algorithms
			 * differ with charset, so we could
			 * incorrectly fail a perfectly valid password
			 * change */
#ifdef DEBUG_PASSWORD
			DEBUG(100,
			      ("check_oem_password: password %s ok\n", *pp_new_passwd));
#endif
			return NT_STATUS_OK;
		}

		if (lanman_pw) {
			/*
			 * check the lm verifier
			 */
			E_old_pw_hash(new_nt_hash, lanman_pw, verifier);
			if (memcmp(verifier, old_lm_hash_encrypted, 16)) {
				DEBUG(0,("check_oem_password: old lm password doesn't match.\n"));
				return NT_STATUS_WRONG_PASSWORD;
			}
#ifdef DEBUG_PASSWORD
			DEBUG(100,
			      ("check_oem_password: password %s ok\n", *pp_new_passwd));
#endif
			return NT_STATUS_OK;
		}
	}

	if (lanman_pw && lm_pass_set) {

		E_deshash(*pp_new_passwd, new_lm_hash);

		/*
		 * check the lm verifier
		 */
		E_old_pw_hash(new_lm_hash, lanman_pw, verifier);
		if (memcmp(verifier, old_lm_hash_encrypted, 16)) {
			DEBUG(0,("check_oem_password: old lm password doesn't match.\n"));
			return NT_STATUS_WRONG_PASSWORD;
		}

#ifdef DEBUG_PASSWORD
		DEBUG(100,
		      ("check_oem_password: password %s ok\n", *pp_new_passwd));
#endif
		return NT_STATUS_OK;
	}

	/* should not be reached */
	return NT_STATUS_WRONG_PASSWORD;
}

bool password_in_history(uint8_t nt_pw[NT_HASH_LEN],
			 uint32_t pw_history_len,
			 const uint8_t *pw_history)
{
	static const uint8_t zero_md5_nt_pw[SALTED_MD5_HASH_LEN] = { 0, };
	int i;

	dump_data(100, nt_pw, NT_HASH_LEN);
	dump_data(100, pw_history, PW_HISTORY_ENTRY_LEN * pw_history_len);

	for (i=0; i<pw_history_len; i++) {
		uint8_t new_nt_pw_salted_md5_hash[SALTED_MD5_HASH_LEN];
		const uint8_t *current_salt;
		const uint8_t *old_nt_pw_salted_md5_hash;

		current_salt = &pw_history[i*PW_HISTORY_ENTRY_LEN];
		old_nt_pw_salted_md5_hash = current_salt + PW_HISTORY_SALT_LEN;

		if (memcmp(zero_md5_nt_pw, old_nt_pw_salted_md5_hash,
			   SALTED_MD5_HASH_LEN) == 0) {
			/* Ignore zero valued entries. */
			continue;
		}

		if (memcmp(zero_md5_nt_pw, current_salt,
			   PW_HISTORY_SALT_LEN) == 0)
		{
			/*
			 * New format: zero salt and then plain nt hash.
			 * Directly compare the hashes.
			 */
			if (memcmp(nt_pw, old_nt_pw_salted_md5_hash,
				   SALTED_MD5_HASH_LEN) == 0)
			{
				return true;
			}
		} else {
			/*
			 * Old format: md5sum of salted nt hash.
			 * Create salted version of new pw to compare.
			 */
			E_md5hash(current_salt, nt_pw, new_nt_pw_salted_md5_hash);

			if (memcmp(new_nt_pw_salted_md5_hash,
				   old_nt_pw_salted_md5_hash,
				   SALTED_MD5_HASH_LEN) == 0) {
				return true;
			}
		}
	}
	return false;
}

/***********************************************************
 This routine takes the given password and checks it against
 the password history. Returns True if this password has been
 found in the history list.
************************************************************/

static bool check_passwd_history(struct samu *sampass, const char *plaintext)
{
	uchar new_nt_p16[NT_HASH_LEN];
	const uint8 *nt_pw;
	const uint8 *pwhistory;
	uint32 pwHisLen, curr_pwHisLen;

	pdb_get_account_policy(PDB_POLICY_PASSWORD_HISTORY, &pwHisLen);
	if (pwHisLen == 0) {
		return False;
	}

	pwhistory = pdb_get_pw_history(sampass, &curr_pwHisLen);
	if (!pwhistory || curr_pwHisLen == 0) {
		return False;
	}

	/* Only examine the minimum of the current history len and
	   the stored history len. Avoids race conditions. */
	pwHisLen = MIN(pwHisLen,curr_pwHisLen);

	nt_pw = pdb_get_nt_passwd(sampass);

	E_md4hash(plaintext, new_nt_p16);

	if (!memcmp(nt_pw, new_nt_p16, NT_HASH_LEN)) {
		DEBUG(10,("check_passwd_history: proposed new password for user %s is the same as the current password !\n",
			pdb_get_username(sampass) ));
		return True;
	}

	if (password_in_history(new_nt_p16, pwHisLen, pwhistory)) {
		DEBUG(1,("check_passwd_history: proposed new password for "
			 "user %s found in history list !\n",
			 pdb_get_username(sampass) ));
		return true;
	}
	return false;
}

/***********************************************************
 Code to change the oem password. Changes both the lanman
 and NT hashes.  Old_passwd is almost always NULL.
 NOTE this function is designed to be called as root. Check the old password
 is correct before calling. JRA.
************************************************************/

NTSTATUS change_oem_password(struct samu *hnd, char *old_passwd, char *new_passwd, bool as_root, uint32 *samr_reject_reason)
{
	uint32 min_len;
	uint32 refuse;
	TALLOC_CTX *tosctx = talloc_tos();
	struct passwd *pass = NULL;
	const char *username = pdb_get_username(hnd);
	time_t can_change_time = pdb_get_pass_can_change_time(hnd);

	if (samr_reject_reason) {
		*samr_reject_reason = Undefined;
	}

	/* check to see if the secdesc has previously been set to disallow */
	if (!pdb_get_pass_can_change(hnd)) {
		DEBUG(1, ("user %s does not have permissions to change password\n", username));
		if (samr_reject_reason) {
			*samr_reject_reason = SAMR_REJECT_OTHER;
		}
		return NT_STATUS_ACCOUNT_RESTRICTION;
	}

	/* check to see if it is a Machine account and if the policy
	 * denies machines to change the password. *
	 * Should we deny also SRVTRUST and/or DOMSTRUST ? .SSS. */
	if (pdb_get_acct_ctrl(hnd) & ACB_WSTRUST) {
		if (pdb_get_account_policy(PDB_POLICY_REFUSE_MACHINE_PW_CHANGE, &refuse) && refuse) {
			DEBUG(1, ("Machine %s cannot change password now, "
				  "denied by Refuse Machine Password Change policy\n",
				  username));
			if (samr_reject_reason) {
				*samr_reject_reason = SAMR_REJECT_OTHER;
			}
			return NT_STATUS_ACCOUNT_RESTRICTION;
		}
	}

	/* removed calculation here, because passdb now calculates
	   based on policy.  jmcd */
	if ((can_change_time != 0) && (time(NULL) < can_change_time)) {
		DEBUG(1, ("user %s cannot change password now, must "
			  "wait until %s\n", username,
			  http_timestring(tosctx, can_change_time)));
		if (samr_reject_reason) {
			*samr_reject_reason = SAMR_REJECT_OTHER;
		}
		return NT_STATUS_ACCOUNT_RESTRICTION;
	}

	if (pdb_get_account_policy(PDB_POLICY_MIN_PASSWORD_LEN, &min_len) && (str_charnum(new_passwd) < min_len)) {
		DEBUG(1, ("user %s cannot change password - password too short\n", 
			  username));
		DEBUGADD(1, (" account policy min password len = %d\n", min_len));
		if (samr_reject_reason) {
			*samr_reject_reason = SAMR_REJECT_TOO_SHORT;
		}
		return NT_STATUS_PASSWORD_RESTRICTION;
/* 		return NT_STATUS_PWD_TOO_SHORT; */
	}

	if (check_passwd_history(hnd,new_passwd)) {
		if (samr_reject_reason) {
			*samr_reject_reason = SAMR_REJECT_IN_HISTORY;
		}
		return NT_STATUS_PASSWORD_RESTRICTION;
	}

	pass = Get_Pwnam_alloc(tosctx, username);
	if (!pass) {
		DEBUG(1, ("change_oem_password: Username %s does not exist in system !?!\n", username));
		return NT_STATUS_ACCESS_DENIED;
	}

	/* Use external script to check password complexity */
	if (lp_check_password_script() && *(lp_check_password_script())) {
		int check_ret;
		char *cmd;

		cmd = talloc_string_sub(tosctx, lp_check_password_script(), "%u", username);
        	if (!cmd) {
                	return NT_STATUS_PASSWORD_RESTRICTION;
        	}

		check_ret = smbrunsecret(cmd, new_passwd);
		DEBUG(5, ("change_oem_password: check password script (%s) returned [%d]\n", cmd, check_ret));
		TALLOC_FREE(cmd);

		if (check_ret != 0) {
			DEBUG(1, ("change_oem_password: check password script said new password is not good enough!\n"));
			if (samr_reject_reason) {
				*samr_reject_reason = SAMR_REJECT_COMPLEXITY;
			}
			TALLOC_FREE(pass);
			return NT_STATUS_PASSWORD_RESTRICTION;
		}
	}

	/*
	 * If unix password sync was requested, attempt to change
	 * the /etc/passwd database first. Return failure if this cannot
	 * be done.
	 *
	 * This occurs before the oem change, because we don't want to
	 * update it if chgpasswd failed.
	 *
	 * Conditional on lp_unix_password_sync() because we don't want
	 * to touch the unix db unless we have admin permission.
	 */
	
	if(lp_unix_password_sync() &&
		!chgpasswd(username, pass, old_passwd, new_passwd, as_root)) {
		TALLOC_FREE(pass);
		return NT_STATUS_ACCESS_DENIED;
	}

	TALLOC_FREE(pass);

	if (!pdb_set_plaintext_passwd (hnd, new_passwd)) {
		return NT_STATUS_ACCESS_DENIED;
	}

	/* Now write it into the file. */
	return pdb_update_sam_account (hnd);
}
