/*
   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"
#include "../lib/crypto/arcfour.h"
#include "rpc_server/samr/srv_samr_util.h"

#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)) {
				DEBUG(2, ("expect: read error %s\n",
					  nt_errstr(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 char *rhost, 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, rhost,
						 oldpass, newpass);
		} else {
			ret = smb_pam_passchange(name, rhost, 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 */

/***********************************************************
 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 nt "
					  "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;
}

static 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;
}

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

NTSTATUS check_password_complexity(const char *username,
				   const char *password,
				   enum samPwdChangeReason *samr_reject_reason)
{
	TALLOC_CTX *tosctx = talloc_tos();
	int check_ret;
	char *cmd;

	/* Use external script to check password complexity */
	if ((lp_check_password_script() == NULL)
	    || (*(lp_check_password_script()) == '\0')) {
		return NT_STATUS_OK;
	}

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

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

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

	return NT_STATUS_OK;
}

/***********************************************************
 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.
************************************************************/

static NTSTATUS change_oem_password(struct samu *hnd, const char *rhost,
				    char *old_passwd, char *new_passwd,
				    bool as_root,
				    enum samPwdChangeReason *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);
	NTSTATUS status;

	if (samr_reject_reason) {
		*samr_reject_reason = SAM_PWD_CHANGE_NO_ERROR;
	}

	/* 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 = SAM_PWD_CHANGE_NO_ERROR;
		}
		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 = SAM_PWD_CHANGE_NO_ERROR;
			}
			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 = SAM_PWD_CHANGE_NO_ERROR;
		}
		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 = SAM_PWD_CHANGE_PASSWORD_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 = SAM_PWD_CHANGE_PWD_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;
	}

	status = check_password_complexity(username, new_passwd, samr_reject_reason);
	if (!NT_STATUS_IS_OK(status)) {
		TALLOC_FREE(pass);
		return status;
	}

	/*
	 * 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, rhost, 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);
}

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

NTSTATUS pass_oem_change(char *user, const char *rhost,
			 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],
			 enum samPwdChangeReason *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, rhost, NULL, new_passwd,
					True, reject_reason);
	unbecome_root();

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

	TALLOC_FREE(sampass);

	return nt_status;
}