/* ====================================================================
 * Copyright (c) 1995-1999 The Apache Group.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the Apache Group
 *    for use in the Apache HTTP server project (http://www.apache.org/)."
 *
 * 4. The names "Apache Server" and "Apache Group" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
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 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the Apache Group
 *    for use in the Apache HTTP server project (http://www.apache.org/)."
 *
 * THIS SOFTWARE IS PROVIDED BY THE APACHE GROUP ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Group and was originally based
 * on public domain software written at the National Center for
 * Supercomputing Applications, University of Illinois, Urbana-Champaign.
 * For more information on the Apache Group and the Apache HTTP server
 * project, please see <http://www.apache.org/>.
 *
 */

/*
 * http_auth: authentication
 * 
 * Rob McCool
 * 
 * Adapted to Apache by rst.
 *
 * dirkx - Added Authoritative control to allow passing on to lower
 *         modules if and only if the user-id is not known to this
 *         module. A known user with a faulty or absent password still
 *         causes an AuthRequired. The default is 'Authoritative', i.e.
 *         no control is passed along.
 */

/* 
 * mod_auth_ntsec.c - Apache module for Cygwin 1.x ntsec based authentication
 *
 * $Id: mod_auth_ntsec.c,v 1.4 2001/12/02 17:24:30 tolj Exp tolj $
 *
 * Based upon mod_auth_nt.c by Kamalendu Biswas <kbiswas@hotmail.com>.
 * Stipe Tolj <tolj@wapme-systems.de>
 *
 * Usage: 
 * Include this module if you want to check userid and password
 * credentials against your local NT accounts. 
 *
 * Install:
 * To compile the module using the apxs tool please use the following
 * command within your shell
 *
 *   $ /usr/local/apache/bin/apxs -DCYGWIN_W32API \
 *      -c mod_auth_ntsec.c -o mod_auth_ntsec.dll
 *
 * Defining CYGWIN_W32API is needed due to the fact that we need to exclude
 * W32API declarations in os/cygwin/os.h if we use them inside this module.
 *
 * Configuration Directives:
 *
 *   Auth_ntsec [On|Off] - enable or disable ntsec based authentication
 *   Auth_ntsec_Authorative [Yes|No] - allow access control to be passed
 *                                     to lower authentication modules
 *
 * Supported require arguments:
 * 
 *   require user <user1> <user2> ... <userN>
 *   require valid-user
 *   require file-owner
 *  
 */

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
 
/*
 * Cygwin needs some additional headers 
 */
#ifndef __CYGWIN__
#error "mod_auth_ntsec: this module is specific to the Cygwin 1.x platform"
#else
#include <unistd.h>
#include <sys/param.h>
#include <windows.h>
#include <sys/cygwin.h>
#include <process.h>
#include <pwd.h>

#define cygwin_is_winnt (GetVersion() < 0x80000000)

static struct passwd *pw;
BOOL authenticate_ntsec(request_rec *r, char* user, char* passwd);
#endif

typedef struct auth_config_struct {
	unsigned char enable_ntsec_auth;
    int auth_authoritative;
} ntsec_auth_config_rec;

static void *create_auth_dir_config(pool *p, char *d)
{
    ntsec_auth_config_rec *sec =
    (ntsec_auth_config_rec *) ap_pcalloc(p, sizeof(ntsec_auth_config_rec));
   	sec->enable_ntsec_auth = 1;
    sec->auth_authoritative = 1;	/* keep the fortress secure by default */
    return sec;
}

static const char *set_ntsec_auth_flag(cmd_parms *cmd, ntsec_auth_config_rec *sec, int arg)
{
	sec->enable_ntsec_auth = (unsigned char) arg;
	return NULL;
}

static const command_rec auth_cmds[] =
{
	{"Auth_ntsec", set_ntsec_auth_flag, 
        NULL, OR_AUTHCFG, FLAG, 
        "Enable (on) or disable (off) Cygwin's ntsec based authentication." },
    {"Auth_ntsec_Authoritative", ap_set_flag_slot, 
        (void *) XtOffsetOf(ntsec_auth_config_rec, auth_authoritative),
        OR_AUTHCFG, FLAG,
        "Set to 'no' to allow access control to be passed along to lower modules if the UserID is not known to this module"},
    {NULL}
};

module MODULE_VAR_EXPORT ntsec_auth_module;

/* These functions return 0 if client is OK, and proper error status
 * if not... either AUTH_REQUIRED, if we made a check, and it failed, or
 * SERVER_ERROR, if things are so totally confused that we couldn't
 * figure out how to tell if the client is authorized or not.
 *
 * If they return DECLINED, and all other modules also decline, that's
 * treated by the server core as a configuration error, logged and
 * reported as such.
 */

/* Determine user ID, and check if it really is that user, for HTTP
 * basic authentication...
 */

static int ntsec_authenticate_basic_user(request_rec *r)
{
    ntsec_auth_config_rec *sec =
    (ntsec_auth_config_rec *) ap_get_module_config(r->per_dir_config, &ntsec_auth_module);
    conn_rec *c = r->connection;
    const char *sent_pw;
    int res;

    if ((res = ap_get_basic_auth_pw(r, &sent_pw)))
	return res;
    
    if (!sec->enable_ntsec_auth)
	return DECLINED;

    /* check the given password against the ntsec local accounts */
    if (!authenticate_ntsec(r, c->user, (char*)sent_pw)) {
        ap_note_basic_auth_failure(r);
        return AUTH_REQUIRED;
    }
    return OK;
}

/* Checking ID */

static int ntsec_check_auth(request_rec *r)
{
    ntsec_auth_config_rec *sec =
    (ntsec_auth_config_rec *) ap_get_module_config(r->per_dir_config, &ntsec_auth_module);
    char *user = r->connection->user;
    int m = r->method_number;
    int method_restricted = 0;
    register int x;
    const char *t, *w;
    const array_header *reqs_arr = ap_requires(r);
    require_line *reqs;

    /* BUG FIX: tadc, 11-Nov-1995.  If there is no "requires" directive, 
     * then any user will do.
     */
    if (reqs_arr == NULL) {
	return (OK);
    }
    reqs = (require_line *) reqs_arr->elts;

    for (x = 0; x < reqs_arr->nelts; x++) {

	if (!(reqs[x].method_mask & (1 << m)))
	    continue;

	method_restricted = 1;

	t = reqs[x].requirement;
	w = ap_getword_white(r->pool, &t);
	if (!strcmp(w, "valid-user"))
	    return OK;
	if (!strcmp(w, "user")) {
	    while (t[0]) {
		w = ap_getword_conf(r->pool, &t);
		if (!strcmp(user, w))
		    return OK;
	    }
	}
    if (strcmp(w, "file-owner") == 0) {
        struct passwd *pwent;
        ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
            "checking for 'owner' access for file '%s'",
            r->filename);
        if (r->finfo.st_ino == 0) {
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                "no stat info for '%s'", r->filename);
            continue;
        }
        pwent = getpwuid(r->finfo.st_uid);
        if (pwent == NULL) {
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                "no username for UID %d (owner of '%s')",
                r->finfo.st_uid, r->filename);
        } else {
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                "checking authenticated user '%s' "
                "against owner '%s' of '%s'",
                user, pwent->pw_name, r->filename);
             if (strcmp(user, pwent->pw_name) == 0) {
                return OK;
             } else {
                continue;
             }
        }
    /*
    }
 	if (strcmp(w, "file-group") == 0) {
        struct group *grent;
        ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
            "checking for 'group' access for file '%s'",
            r->filename);
        if (r->finfo.st_ino == 0) {
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                "no stat info for '%s'", r->filename);
            continue;
        }
        grent = getgrgid(r->finfo.st_gid);
        if (grent == NULL) {
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                "no group name for GID %d (owner of '%s')",
                r->finfo.st_gid, r->filename);
        } else {
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                "checking groups of authenticated user '%s' "
                "against owner group '%s' of '%s'",
                user, grent->gr_name, r->filename);
            if (ap_table_get(grpstatus, grent->gr_name) != NULL) {
                return OK;
            } else {
                continue;
            }
        }
    }
*/
	} else if (sec->auth_authoritative) {
	    /* if we aren't authoritative, any require directive could be
	     * valid even if we don't grok it.  However, if we are 
	     * authoritative, we can warn the user they did something wrong.
	     * That something could be a missing "AuthAuthoritative off", but
	     * more likely is a typo in the require directive.
	     */
	    ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
		"access to %s failed, reason: unknown require directive:"
		"\"%s\"", r->uri, reqs[x].requirement);
	}
    }

    if (!method_restricted)
	   return OK;

    if (!(sec->auth_authoritative))
	   return DECLINED;

    ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
	   "access to %s failed, reason: user %s not allowed access",
	   r->uri, user);
	
    ap_note_basic_auth_failure(r);
    return AUTH_REQUIRED;
}

#if defined(__CYGWIN__)

/* Enables the necessary NT privileges to query an other user's
 * password from the system in order to compare it against the
 * password the user agent has been delivered. 
 * Returns true if the enabling of the privilige was successfull,
 * false otherwise.
 */

BOOL ntsec_enable_privilege(LPCSTR name, BOOL enable)
{
    HANDLE token;
    TOKEN_PRIVILEGES priv;  
    LUID luid;
    BOOL res = FALSE;

    if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, &token))
        return FALSE;

    if (LookupPrivilegeValue(0, name, &luid)) {
        priv.PrivilegeCount = 1;
        priv.Privileges[0].Luid = luid;
        if (enable)
            priv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
        else
            priv.Privileges[0].Attributes = 0;

        if (AdjustTokenPrivileges(token, FALSE, &priv, 0, 0, 0))
            res = TRUE;
    }

    CloseHandle(token);
    return res;
}

/* Check if the given userid and password match on the local NT
 * system. Returns true if it matches, false otherwise.
 */

BOOL authenticate_ntsec(request_rec *r, char* user, char* passwd)
{
    //BOOL isValidUser = FALSE;
    HANDLE pHandle;

    /* Enable the necessary privilege for the httpd user */
    BOOL prv = ntsec_enable_privilege(SE_TCB_NAME, TRUE);
    if (!prv)
    {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
		    "Could not enable SE_TCB_NAME privilege for httpd user!");
        return FALSE;
    }

    /* We are only having the chance to authenticate if we are 
     * running Cygwin 1.x on a NT based system.
     */
    if (cygwin_is_winnt) {
        pw = getpwnam(user);
        pHandle = cygwin_logon_user(pw, passwd);
        if (pHandle != INVALID_HANDLE_VALUE) {
            cygwin_set_impersonation_token(pHandle);
            CloseHandle(pHandle);
            return TRUE;
        } else {
	        ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
		      "user %s: authentication failure for \"%s\"",
		      user, r->uri);
            return FALSE;
        }
    } else {
	    ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
		    "Can not use ntsec based authentication on Win9x systems!");
        return FALSE;
        
    }

}
#endif /* __CYGWIN__ */

module MODULE_VAR_EXPORT ntsec_auth_module =
{
    STANDARD_MODULE_STUFF,
    NULL,			        /* initializer */
    create_auth_dir_config,	/* dir config creater */
    NULL,			        /* dir merger --- default is to override */
    NULL,			        /* server config */
    NULL,			        /* merge server config */
    auth_cmds,			    /* command table */
    NULL,			        /* handlers */
    NULL,			        /* filename translation */
    ntsec_authenticate_basic_user,/* check_user_id */
    ntsec_check_auth,		/* check auth */
    NULL,			        /* check access */
    NULL,			        /* type_checker */
    NULL,			        /* fixups */
    NULL,			        /* logger */
    NULL,			        /* header parser */
    NULL,			        /* child_init */
    NULL,			        /* child_exit */
    NULL			        /* post read-request */
};