chgpasswd.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* 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 ([e-mail]) and Evan Patterson
 * ([e-mail]) 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 [e-mail]. 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"

extern struct passdb_ops pdb_ops;

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],
				   SAM_ACCOUNT **hnd, char *new_passwd,
				   int new_passwd_size);

#if ALLOW_CHANGE_PASSWORD

static int findpty(char **slave)
{
	int master;
	static fstring line;
	SMB_STRUCT_DIR *dirp;
	const char *dpname;

#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);
		*slave = (char *)ptsname(master);
		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 */

	fstrcpy(line, "/dev/ptyXX");

	dirp = sys_opendir("/dev");
	if (!dirp)
		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);
	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;

	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(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");
	}
#elif defined(TIOCSCTTY)
	if (ioctl(slave, TIOCSCTTY, 0) < 0)
	{
		DEBUG(3, ("Error in ioctl call for slave pty\n"));
		/* return(False); */
	}
#endif

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

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

	if (sys_dup2(slave, STDIN_FILENO) != STDIN_FILENO)
	{
		DEBUG(3, ("Could not re-direct stdin\n"));
		return (False);
	}
	if (sys_dup2(slave, STDOUT_FILENO) != STDOUT_FILENO)
	{
		DEBUG(3, ("Could not re-direct stdout\n"));
		return (False);
	}
	if (sys_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 (execl("/bin/sh", "sh", "-c", passwordprogram, NULL) < 0)
	{
		DEBUG(3, ("Bad status returned from %s\n", passwordprogram));
		return (False);
	}
	return (True);
}

static int expect(int master, char *issue, char *expected)
{
	pstring buffer;
	int attempts, timeout, nread, len;
	BOOL match = False;

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

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

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

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

		while ((len = read_socket_with_timeout(master, buffer + nread, 1,
						       sizeof(buffer) - nread - 1,
						       timeout)) > 0) {
			nread += len;
			buffer[nread] = 0;

			{
				/* Eat leading/trailing whitespace before match. */
				pstring str;
				pstrcpy( str, buffer);
				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;
				}
			}
		}

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

		if (match)
			break;

		if (len < 0) {
			DEBUG(2, ("expect: %s\n", strerror(errno)));
			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)
{
	int count = 0;
	fstring issue, expected;

	fstrcpy(issue, ".");

	while (next_token(&seq, expected, NULL, sizeof(expected)))
	{
		pwd_sub(expected);
		count++;

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

		if (!next_token(&seq, issue, NULL, sizeof(issue)))
			fstrcpy(issue, ".");

		pwd_sub(issue);
	}
	if (!strequal(issue, ".")) {
		/* we have one final issue to send */
		fstrcpy(expected, ".");
		if (!expect(master, issue, expected))
			return False;
	}

	return (count > 0);
}

static BOOL chat_with_program(char *passwordprogram, const struct passwd *pass,
			      char *chatsequence, BOOL as_root)
{
	char *slavedev;
	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));
		close(master);
		CatchChild();
		return (False);
	}

	/* we now have a pty */
	if (pid > 0) {			/* This is the parent process */
		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 oplock capabilities.
		 */
		oplock_set_capability(False, False);

		/* 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)
{
	pstring passwordprogram;
	pstring chatsequence;
	size_t i;
	size_t len;

	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;

		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();

		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;
	}

	pstrcpy(passwordprogram, lp_passwd_program());
	pstrcpy(chatsequence, lp_passwd_chat());

	if (!*chatsequence) {
		DEBUG(2, ("chgpasswd: Null chat sequence - no password changing\n"));
		return (False);
	}

	if (!*passwordprogram) {
		DEBUG(2, ("chgpasswd: Null password program - 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;
		}