pam_smbpass/pam_smb_auth.c

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/* 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_AUTH

#include "includes.h"
#include "debug.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"

#define AUTH_RETURN                                             \
do {                                                            \
        /* Restore application signal handler */                \
        CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);       \
        if(ret_data) {                                          \
                *ret_data = retval;                             \
                pam_set_data( pamh, "smb_setcred_return"        \
                              , (void *) ret_data, NULL );      \
        }                                                       \
        return retval;                                          \
} while (0)

static int _smb_add_user(pam_handle_t *pamh, unsigned int ctrl,
                         const char *name, struct samu *sampass, BOOL exist);


/*
 * pam_sm_authenticate() authenticates users against the samba password file.
 *
 *      First, obtain the password from the user. Then use a
 *      routine in 'support.c' to authenticate the user.
 */

#define _SMB_AUTHTOK  "-SMB-PASS"

int pam_sm_authenticate(pam_handle_t *pamh, int flags,
                        int argc, const char **argv)
{
        unsigned int ctrl;
        int retval, *ret_data = NULL;
        struct samu *sampass = NULL;
        extern BOOL in_client;
        const char *name;
        void (*oldsig_handler)(int) = NULL;
        BOOL found;

        /* Points to memory managed by the PAM library. Do not free. */
        char *p = NULL;

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

        ctrl = set_ctrl(flags, argc, argv);

        /* Get a few bytes so we can pass our return value to
                pam_sm_setcred(). */
        ret_data = SMB_MALLOC_P(int);

        /* we need to do this before we call AUTH_RETURN */
        /* Getting into places that might use LDAP -- protect the app
        from a SIGPIPE it's not expecting */
        oldsig_handler = CatchSignal(SIGPIPE, SIGNAL_CAST SIG_IGN);

        /* get the username */
        retval = pam_get_user( pamh, &name, "Username: " );
        if ( retval != PAM_SUCCESS ) {
                if (on( SMB_DEBUG, ctrl )) {
                        _log_err(LOG_DEBUG, "auth: could not identify user");
                }
                AUTH_RETURN;
        }
        if (on( SMB_DEBUG, ctrl )) {
                _log_err( LOG_DEBUG, "username [%s] obtained", name );
        }

        if (geteuid() != 0) {
                _log_err(LOG_DEBUG, "Cannot access samba password database, not running as root.");
                retval = PAM_AUTHINFO_UNAVAIL;
                AUTH_RETURN;
        }

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

        sampass = samu_new( NULL );
        if (!sampass) {
                _log_err( LOG_ALERT, "Cannot talloc a samu struct" );
                retval = nt_status_to_pam(NT_STATUS_NO_MEMORY);
                AUTH_RETURN;
        }

        found = pdb_getsampwnam( sampass, name );

        if (on( SMB_MIGRATE, ctrl )) {
                retval = _smb_add_user(pamh, ctrl, name, sampass, found);
                TALLOC_FREE(sampass);
                AUTH_RETURN;
        }

        if (!found) {
                _log_err(LOG_ALERT, "Failed to find entry for user %s.", name);
                retval = PAM_USER_UNKNOWN;
                TALLOC_FREE(sampass);
                sampass = NULL;
                AUTH_RETURN;
        }
   
        /* if this user does not have a password... */

        if (_smb_blankpasswd( ctrl, sampass )) {
                TALLOC_FREE(sampass);
                retval = PAM_SUCCESS;
                AUTH_RETURN;
        }

        /* get this user's authentication token */

        retval = _smb_read_password(pamh, ctrl, NULL, "Password: ", NULL, _SMB_AUTHTOK, &p);
        if (retval != PAM_SUCCESS ) {
                _log_err(LOG_CRIT, "auth: no password provided for [%s]", name);
                TALLOC_FREE(sampass);
                AUTH_RETURN;
        }

        /* verify the password of this user */

        retval = _smb_verify_password( pamh, sampass, p, ctrl );
        TALLOC_FREE(sampass);
        p = NULL;
        AUTH_RETURN;
}

/*
 * This function is for setting samba credentials.  If anyone comes up
 * with any credentials they think should be set, let me know.
 */

int pam_sm_setcred(pam_handle_t *pamh, int flags,
                   int argc, const char **argv)
{
    int retval, *pretval = NULL;

    retval = PAM_SUCCESS;

    pam_get_data(pamh, "smb_setcred_return", (const void **) &pretval);
    if(pretval) {
        retval = *pretval;
        SAFE_FREE(pretval);
    }
    pam_set_data(pamh, "smb_setcred_return", NULL, NULL);

    return retval;
}


/* Helper function for adding a user to the db. */
static int _smb_add_user(pam_handle_t *pamh, unsigned int ctrl,
                         const char *name, struct samu *sampass, BOOL exist)
{
    pstring err_str;
    pstring msg_str;
    const char *pass = NULL;
    int retval;

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

    /* Get the authtok; if we don't have one, silently fail. */
    retval = pam_get_item( pamh, PAM_AUTHTOK, (const void **) &pass );

    if (retval != PAM_SUCCESS) {
        _log_err( LOG_ALERT
                  , "pam_get_item returned error to pam_sm_authenticate" );
        return PAM_AUTHTOK_RECOVER_ERR;
    } else if (pass == NULL) {
        return PAM_AUTHTOK_RECOVER_ERR;
    }

    /* Add the user to the db if they aren't already there. */
   if (!exist) {
        retval = NT_STATUS_IS_OK(local_password_change( name, LOCAL_ADD_USER|LOCAL_SET_PASSWORD,
                                         pass, err_str,
                                         sizeof(err_str),
                                         msg_str, sizeof(msg_str) ));
        if (!retval && *err_str)
        {
            err_str[PSTRING_LEN-1] = '\0';
            make_remark( pamh, ctrl, PAM_ERROR_MSG, err_str );
        }
        else if (*msg_str)
        {
            msg_str[PSTRING_LEN-1] = '\0';
            make_remark( pamh, ctrl, PAM_TEXT_INFO, msg_str );
        }
        pass = NULL;

        return PAM_IGNORE;
   }
   else {
    /* mimick 'update encrypted' as long as the 'no pw req' flag is not set */
    if ( pdb_get_acct_ctrl(sampass) & ~ACB_PWNOTREQ )
    {
        retval = NT_STATUS_IS_OK(local_password_change( name, LOCAL_SET_PASSWORD, pass, err_str, sizeof(err_str),
                                         msg_str, sizeof(msg_str) ));
        if (!retval && *err_str)
        {
            err_str[PSTRING_LEN-1] = '\0';
            make_remark( pamh, ctrl, PAM_ERROR_MSG, err_str );
        }
        else if (*msg_str)
        {
            msg_str[PSTRING_LEN-1] = '\0';
            make_remark( pamh, ctrl, PAM_TEXT_INFO, msg_str );
        }
    }
   }
    
    pass = NULL;

    return PAM_IGNORE;
}


/* static module data */
#ifdef PAM_STATIC
struct pam_module _pam_smbpass_auth_modstruct = {
     "pam_smbpass",
     pam_sm_authenticate,
     pam_sm_setcred,
     NULL,
     NULL,
     NULL,
     NULL
};
#endif

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