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Unix SMB/CIFS implementation.
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Use PAM to update user passwords in the local SAM
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Copyright (C) Steve Langasek 1998-2003
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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/* indicate the following groups are defined */
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#define PAM_SM_PASSWORD
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/* This is only used in the Sun implementation. FIXME: we really
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want a define here that distinguishes between the Solaris PAM
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and others (including FreeBSD). */
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#include <security/pam_appl.h>
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#include <security/pam_modules.h>
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int smb_update_db( pam_handle_t *pamh, int ctrl, const char *user, const char *pass_new )
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retval = NT_STATUS_IS_OK(local_password_change( user, LOCAL_SET_PASSWORD, pass_new,
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err_str, sizeof(err_str),
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msg_str, sizeof(msg_str) ));
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err_str[PSTRING_LEN-1] = '\0';
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make_remark( pamh, ctrl, PAM_ERROR_MSG, err_str );
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/* FIXME: what value is appropriate here? */
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retval = PAM_AUTHTOK_ERR;
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msg_str[PSTRING_LEN-1] = '\0';
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make_remark( pamh, ctrl, PAM_TEXT_INFO, msg_str );
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#define _SMB_OLD_AUTHTOK "-SMB-OLD-PASS"
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#define _SMB_NEW_AUTHTOK "-SMB-NEW-PASS"
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* FUNCTION: pam_sm_chauthtok()
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* This function is called twice by the PAM library, once with
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* PAM_PRELIM_CHECK set, and then again with PAM_UPDATE_AUTHTOK set. With
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* Linux-PAM, these two passes generally involve first checking the old
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* token and then changing the token. This is what we do here.
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* Having obtained a new password. The function updates the
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* SMB_PASSWD_FILE file (normally, $(LIBDIR)/smbpasswd).
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int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
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int argc, const char **argv)
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extern BOOL in_client;
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struct samu *sampass = NULL;
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void (*oldsig_handler)(int);
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/* Samba initialization. */
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setup_logging( "pam_smbpass", False );
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ctrl = set_ctrl(flags, argc, argv);
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* First get the name of a user. No need to do anything if we can't
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retval = pam_get_user( pamh, &user, "Username: " );
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if (retval != PAM_SUCCESS) {
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if (on( SMB_DEBUG, ctrl )) {
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_log_err( LOG_DEBUG, "password: could not identify user" );
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if (on( SMB_DEBUG, ctrl )) {
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_log_err( LOG_DEBUG, "username [%s] obtained", user );
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/* Getting into places that might use LDAP -- protect the app
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from a SIGPIPE it's not expecting */
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oldsig_handler = CatchSignal(SIGPIPE, SIGNAL_CAST SIG_IGN);
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if (!initialize_password_db(False)) {
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_log_err( LOG_ALERT, "Cannot access samba password database" );
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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return PAM_AUTHINFO_UNAVAIL;
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/* obtain user record */
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if ( !(sampass = samu_new( NULL )) ) {
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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return nt_status_to_pam(NT_STATUS_NO_MEMORY);
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if (!pdb_getsampwnam(sampass,user)) {
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_log_err( LOG_ALERT, "Failed to find entry for user %s.", user );
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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return PAM_USER_UNKNOWN;
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if (on( SMB_DEBUG, ctrl )) {
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_log_err( LOG_DEBUG, "Located account for %s", user );
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if (flags & PAM_PRELIM_CHECK) {
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* obtain and verify the current password (OLDAUTHTOK) for
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if (_smb_blankpasswd( ctrl, sampass )) {
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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/* Password change by root, or for an expired token, doesn't
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require authentication. Is this a good choice? */
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if (getuid() != 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {
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/* tell user what is happening */
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#define greeting "Changing password for "
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Announce = SMB_MALLOC_ARRAY(char, sizeof(greeting)+strlen(user));
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if (Announce == NULL) {
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_log_err(LOG_CRIT, "password: out of memory");
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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strncpy( Announce, greeting, sizeof(greeting) );
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strncpy( Announce+sizeof(greeting)-1, user, strlen(user)+1 );
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set( SMB__OLD_PASSWD, ctrl );
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retval = _smb_read_password( pamh, ctrl, Announce, "Current SMB password: ",
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NULL, _SMB_OLD_AUTHTOK, &pass_old );
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SAFE_FREE( Announce );
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if (retval != PAM_SUCCESS) {
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, "password - (old) token not obtained" );
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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/* verify that this is the password for this user */
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retval = _smb_verify_password( pamh, sampass, pass_old, ctrl );
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retval = PAM_SUCCESS; /* root doesn't have to */
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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} else if (flags & PAM_UPDATE_AUTHTOK) {
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* obtain the proposed password
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* get the old token back. NULL was ok only if root [at this
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* point we assume that this has already been enforced on a
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* previous call to this function].
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if (off( SMB_NOT_SET_PASS, ctrl )) {
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retval = pam_get_item( pamh, PAM_OLDAUTHTOK,
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(const void **)&pass_old );
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retval = pam_get_data( pamh, _SMB_OLD_AUTHTOK,
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(const void **)&pass_old );
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if (retval == PAM_NO_MODULE_DATA) {
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retval = PAM_SUCCESS;
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if (retval != PAM_SUCCESS) {
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_log_err( LOG_NOTICE, "password: user not authenticated" );
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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* use_authtok is to force the use of a previously entered
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* password -- needed for pluggable password strength checking
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* or other module stacking
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if (on( SMB_USE_AUTHTOK, ctrl )) {
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set( SMB_USE_FIRST_PASS, ctrl );
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retval = _smb_read_password( pamh, ctrl
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, "Enter new SMB password: "
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, "Retype new SMB password: "
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if (retval != PAM_SUCCESS) {
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if (on( SMB_DEBUG, ctrl )) {
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, "password: new password not obtained" );
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pass_old = NULL; /* tidy up */
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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* At this point we know who the user is and what they
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* propose as their new password. Verify that the new
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* password is acceptable.
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if (pass_new[0] == '\0') { /* "\0" password = NULL */
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retval = _pam_smb_approve_pass(pamh, ctrl, pass_old, pass_new);
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if (retval != PAM_SUCCESS) {
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_log_err(LOG_NOTICE, "new password not acceptable");
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pass_new = pass_old = NULL; /* tidy up */
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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* By reaching here we have approved the passwords and must now
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* rebuild the smb password file.
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/* update the password database */
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retval = smb_update_db(pamh, ctrl, user, pass_new);
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if (retval == PAM_SUCCESS) {
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/* password updated */
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if (!sid_to_uid(pdb_get_user_sid(sampass), &uid)) {
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_log_err( LOG_NOTICE, "Unable to get uid for user %s",
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pdb_get_username(sampass));
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_log_err( LOG_NOTICE, "password for (%s) changed by (%s/%d)",
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user, uidtoname(getuid()), getuid());
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_log_err( LOG_NOTICE, "password for (%s/%d) changed by (%s/%d)",
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user, uid, uidtoname(getuid()), getuid());
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_log_err( LOG_ERR, "password change failed for user %s", user);
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pass_old = pass_new = NULL;
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TALLOC_FREE(sampass);
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} else { /* something has broken with the library */
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_log_err( LOG_ALERT, "password received unknown request" );
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TALLOC_FREE(sampass);
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TALLOC_FREE(sampass);
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CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
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/* static module data */
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struct pam_module _pam_smbpass_passwd_modstruct = {