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pam_smb_passwd.c

/* Unix NT password database implementation, version 0.7.5.
 *
 * 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.
*/

/* indicate the following groups are defined */
#define PAM_SM_PASSWORD

#include "includes.h"

#ifndef LINUX

/* This is only used in the Sun implementation. */
#include <security/pam_appl.h>

#endif  /* LINUX */

#include <security/pam_modules.h>

#include "general.h" 

#include "support.h"

int smb_update_db( pam_handle_t *pamh, int ctrl, char *user,  char *pass_new )
{
 int        retval;
 pstring    err_str;
 pstring    msg_str;

    err_str[0] = '\0';
    msg_str[0] = '\0';

    retval = local_password_change( user, 0, pass_new, err_str, sizeof(err_str),
                              msg_str, sizeof(msg_str) );

    if (!retval) {
        if (*err_str) {
            err_str[PSTRING_LEN-1] = '\0';
            make_remark( pamh, ctrl, PAM_ERROR_MSG, err_str );
        }

        /* FIXME: what value is appropriate here? */
        retval = PAM_AUTHTOK_ERR;
    } else {
        if (*msg_str) {
            msg_str[PSTRING_LEN-1] = '\0';
            make_remark( pamh, ctrl, PAM_TEXT_INFO, msg_str );
        }
        retval = PAM_SUCCESS;
    }

    return retval;      

}


/* data tokens */

#define _SMB_OLD_AUTHTOK  "-SMB-OLD-PASS"
#define _SMB_NEW_AUTHTOK  "-SMB-NEW-PASS"

/*
 * FUNCTION: pam_sm_chauthtok()
 *
 * This function is called twice by the PAM library, once with
 * PAM_PRELIM_CHECK set, and then again with PAM_UPDATE_AUTHTOK set.  With
 * Linux-PAM, these two passes generally involve first checking the old
 * token and then changing the token.  This is what we do here.
 *
 * Having obtained a new password. The function updates the
 * SMB_PASSWD_FILE file (normally, $(LIBDIR)/smbpasswd).
 */

int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
                     int argc, const char **argv)
{
    unsigned int ctrl;
    int retval;

    extern BOOL in_client;

    SAM_ACCOUNT *sampass = NULL;
    char *user;
    char *pass_old, *pass_new;

    /* Samba initialization. */
    setup_logging( "pam_smbpass", False );
    charset_initialise();
    codepage_initialise(lp_client_code_page());
    in_client = True;

    ctrl = set_ctrl(flags, argc, argv);

    /*
     * First get the name of a user.  No need to do anything if we can't
     * determine this.
     */

    retval = pam_get_user( pamh, (const char **)&user, "Username: " );
    if (retval != PAM_SUCCESS) {
        if (on( SMB_DEBUG, ctrl )) {
            _log_err( LOG_DEBUG, "password: could not identify user" );
        }
        return retval;
    }
    if (on( SMB_DEBUG, ctrl )) {
        _log_err( LOG_DEBUG, "username [%s] obtained", user );
    }

    if (!initialize_password_db(True)) {
        _log_err( LOG_ALERT, "Cannot access samba password database" );
        return PAM_AUTHINFO_UNAVAIL;
    }

    /* obtain user record */
    pdb_init_sam(&sampass);
    pdb_getsampwnam(sampass,user);

    if (sampass == NULL) {
        _log_err( LOG_ALERT, "Failed to find entry for user %s.", user );
        return PAM_USER_UNKNOWN;
    }

    if (flags & PAM_PRELIM_CHECK) {
        /*
         * obtain and verify the current password (OLDAUTHTOK) for
         * the user.
         */

        char *Announce;

        if (_smb_blankpasswd( ctrl, sampass )) {

            pdb_free_sam(sampass);
            return PAM_SUCCESS;
        }

      /* Password change by root, or for an expired token, doesn't
           require authentication.  Is this a good choice? */
        if (getuid() != 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {

            /* tell user what is happening */
#define greeting "Changing password for "
            Announce = (char *) malloc(sizeof(greeting)+strlen(user));
            if (Announce == NULL) {
                _log_err(LOG_CRIT, "password: out of memory");
                pdb_free_sam(sampass);
                return PAM_BUF_ERR;
            }
            strncpy( Announce, greeting, sizeof(greeting) );
            strncpy( Announce+sizeof(greeting)-1, user, strlen(user)+1 );
#undef greeting

            set( SMB__OLD_PASSWD, ctrl );
            retval = _smb_read_password( pamh, ctrl, Announce, "Current SMB password: ",
                                         NULL, _SMB_OLD_AUTHTOK, &pass_old );
            SAFE_FREE( Announce );

            if (retval != PAM_SUCCESS) {
                _log_err( LOG_NOTICE
                          , "password - (old) token not obtained" );
                pdb_free_sam(sampass);
                return retval;
            }

            /* verify that this is the password for this user */

            retval = _smb_verify_password( pamh, sampass, pass_old, ctrl );

        } else {
          pass_old = NULL;
            retval = PAM_SUCCESS;           /* root doesn't have to */
        }

        pass_old = NULL;
        pdb_free_sam(sampass);
        return retval;

    } else if (flags & PAM_UPDATE_AUTHTOK) {

#if 0
        /* We used to return when this flag was set, but that breaks
           password synchronization when /other/ tokens are expired.  For
           now, we change the password whenever we're asked. SRL */
        if (flags & PAM_CHANGE_EXPIRED_AUTHTOK) {
            pdb_free_sam(sampass);
            return PAM_SUCCESS;
        }
#endif
        /*
         * obtain the proposed password
         */

        /*
         * get the old token back. NULL was ok only if root [at this
         * point we assume that this has already been enforced on a
         * previous call to this function].
         */

        if (off( SMB_NOT_SET_PASS, ctrl )) {
            retval = pam_get_item( pamh, PAM_OLDAUTHTOK,
                                   (const void **)&pass_old );
        } else {
            retval = pam_get_data( pamh, _SMB_OLD_AUTHTOK,
                                   (const void **)&pass_old );
            if (retval == PAM_NO_MODULE_DATA) {
            pass_old = NULL;
                retval = PAM_SUCCESS;
            }
        }

        if (retval != PAM_SUCCESS) {
            _log_err( LOG_NOTICE, "password: user not authenticated" );
            pdb_free_sam(sampass);
            return retval;
        }

        /*
         * use_authtok is to force the use of a previously entered
         * password -- needed for pluggable password strength checking
       * or other module stacking
         */

        if (on( SMB_USE_AUTHTOK, ctrl )) {
            set( SMB_USE_FIRST_PASS, ctrl );
        }

        retval = _smb_read_password( pamh, ctrl
                                      , NULL
                                      , "Enter new SMB password: "
                                      , "Retype new SMB password: "
                                      , _SMB_NEW_AUTHTOK
                                      , &pass_new );

        if (retval != PAM_SUCCESS) {
            if (on( SMB_DEBUG, ctrl )) {
                _log_err( LOG_ALERT
                          , "password: new password not obtained" );
            }
            pass_old = NULL;                               /* tidy up */
            pdb_free_sam(sampass);
            return retval;
        }

        /*
         * At this point we know who the user is and what they
         * propose as their new password. Verify that the new
         * password is acceptable.
         */ 

        if (pass_new[0] == '\0') {     /* "\0" password = NULL */
            pass_new = NULL;
        }

        retval = _pam_smb_approve_pass(pamh, ctrl, pass_old, pass_new);

        if (retval != PAM_SUCCESS) {
            _log_err(LOG_NOTICE, "new password not acceptable");
            pass_new = pass_old = NULL;               /* tidy up */
            pdb_free_sam(sampass);
            return retval;
        }

        /*
         * By reaching here we have approved the passwords and must now
         * rebuild the smb password file.
         */

        /* update the password database */

        retval = smb_update_db(pamh, ctrl, user, pass_new);
        if (retval == PAM_SUCCESS) {
            /* password updated */
            _log_err( LOG_NOTICE, "password for (%s/%d) changed by (%s/%d)"
                      , user, pdb_get_uid(sampass), uidtoname( getuid() )
                      , getuid() );
        } else {
            _log_err( LOG_ERR, "password change failed for user %s"
                      , user );
        }

        pass_old = pass_new = NULL;
      if (sampass) {
            pdb_free_sam(sampass);
            sampass = NULL;
      }

    } else {            /* something has broken with the library */

        _log_err( LOG_ALERT, "password received unknown request" );
        retval = PAM_ABORT;

    }
    
    if (sampass) {
      pdb_free_sam(sampass);
      sampass = NULL;
    }

    pdb_free_sam(sampass);
    return retval;
}

/* static module data */
#ifdef PAM_STATIC
struct pam_module _pam_smbpass_passwd_modstruct = {
     "pam_smbpass",
     NULL,
     NULL,
     NULL,
     NULL,
     NULL,
     pam_sm_chauthtok
};
#endif


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