img_auth.php

<?php
/**
 * Image authorisation script
 *
 * To use this, see https://www.mediawiki.org/wiki/Manual:Image_Authorization
 *
 * - Set $wgUploadDirectory to a non-public directory (not web accessible)
 * - Set $wgUploadPath to point to this file
 *
 * Optional Parameters
 *
 * - Set $wgImgAuthDetails = true if you want the reason the access was denied messages to
 *       be displayed instead of just the 403 error (doesn't work on IE anyway),
 *       otherwise it will only appear in error logs
 * - Set $wgImgAuthPublicTest false if you don't want to just check and see if all are public
 *       must be set to false if using specific restrictions such as LockDown or NSFileRepo
 *
 *  For security reasons, you usually don't want your user to know *why* access was denied,
 *  just that it was. If you want to change this, you can set $wgImgAuthDetails to 'true'
 *  in localsettings.php and it will give the user the reason why access was denied.
 *
 * Your server needs to support PATH_INFO; CGI-based configurations usually don't.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

define( 'MW_NO_OUTPUT_COMPRESSION', 1 );
require __DIR__ . '/includes/WebStart.php';
wfProfileIn( 'img_auth.php' );

# Set action base paths so that WebRequest::getPathInfo()
# recognizes the "X" as the 'title' in ../img_auth.php/X urls.
$wgArticlePath = false; # Don't let a "/*" article path clober our action path
$wgActionPaths = array( "$wgUploadPath/" );

wfImageAuthMain();
wfLogProfilingData();

function wfImageAuthMain() {
	global $wgImgAuthPublicTest, $wgImgAuthUrlPathMap, $wgRequest;

	// See if this is a public Wiki (no protections).
	if ( $wgImgAuthPublicTest
		&& in_array( 'read', User::getGroupPermissions( array( '*' ) ), true )
	) {
		// This is a public wiki, so disable this script (for private wikis only)
		wfForbidden( 'img-auth-accessdenied', 'img-auth-public' );
		return;
	}

	// Get the requested file path (source file or thumbnail)
	$matches = WebRequest::getPathInfo();
	if ( !isset( $matches['title'] ) ) {
		wfForbidden( 'img-auth-accessdenied', 'img-auth-nopathinfo' );
		return;
	}
	$path = $matches['title'];
	if ( $path && $path[0] !== '/' ) {
		// Make sure $path has a leading /
		$path = "/" . $path;
	}

	// Check for bug 28235: QUERY_STRING overriding the correct extension
	$whitelist = array();
	$extension = FileBackend::extensionFromPath( $path );
	if ( $extension != '' ) {
		$whitelist[] = $extension;
	}
	if ( !$wgRequest->checkUrlExtension( $whitelist ) ) {
		return;
	}

	// Various extensions may have their own backends that need access.
	// Check if there is a special backend and storage base path for this file.
	foreach ( $wgImgAuthUrlPathMap as $prefix => $storageDir ) {
		$prefix = rtrim( $prefix, '/' ) . '/'; // implicit trailing slash
		if ( strpos( $path, $prefix ) === 0 ) {
			$be = FileBackendGroup::singleton()->backendFromPath( $storageDir );
			$filename = $storageDir . substr( $path, strlen( $prefix ) ); // strip prefix
			// Check basic user authorization
			if ( !RequestContext::getMain()->getUser()->isAllowed( 'read' ) ) {
				wfForbidden( 'img-auth-accessdenied', 'img-auth-noread', $path );
				return;
			}
			if ( $be->fileExists( array( 'src' => $filename ) ) ) {
				wfDebugLog( 'img_auth', "Streaming `" . $filename . "`." );
				$be->streamFile( array( 'src' => $filename ),
					array( 'Cache-Control: private', 'Vary: Cookie' ) );
			} else {
				wfForbidden( 'img-auth-accessdenied', 'img-auth-nofile', $path );
			}
			return;
		}
	}

	// Get the local file repository
	$repo = RepoGroup::singleton()->getRepo( 'local' );

	// Get the full file storage path and extract the source file name.
	// (e.g. 120px-Foo.png => Foo.png or page2-120px-Foo.png => Foo.png).
	// This only applies to thumbnails, and all thumbnails should
	// be under a folder that has the source file name.
	if ( strpos( $path, '/thumb/' ) === 0 ) {
		$name = wfBaseName( dirname( $path ) ); // file is a thumbnail
		$filename = $repo->getZonePath( 'thumb' ) . substr( $path, 6 ); // strip "/thumb"
	} else {
		$name = wfBaseName( $path ); // file is a source file
		$filename = $repo->getZonePath( 'public' ) . $path;
	}

	// Check to see if the file exists
	if ( !$repo->fileExists( $filename ) ) {
		wfForbidden( 'img-auth-accessdenied', 'img-auth-nofile', $filename );
		return;
	}

	$title = Title::makeTitleSafe( NS_FILE, $name );
	if ( !$title instanceof Title ) { // files have valid titles
		wfForbidden( 'img-auth-accessdenied', 'img-auth-badtitle', $name );
		return;
	}

	// Run hook for extension authorization plugins
	/** @var $result array */
	$result = null;
	if ( !wfRunHooks( 'ImgAuthBeforeStream', array( &$title, &$path, &$name, &$result ) ) ) {
		wfForbidden( $result[0], $result[1], array_slice( $result, 2 ) );
		return;
	}

	// Check user authorization for this title
	// Checks Whitelist too
	if ( !$title->userCan( 'read' ) ) {
		wfForbidden( 'img-auth-accessdenied', 'img-auth-noread', $name );
		return;
	}

	if ( $wgRequest->getCheck( 'download' ) ) {
		header( 'Content-Disposition: attachment' );
	}

	// Stream the requested file
	wfDebugLog( 'img_auth', "Streaming `" . $filename . "`." );
	$repo->streamFile( $filename, array( 'Cache-Control: private', 'Vary: Cookie' ) );
}

/**
 * Issue a standard HTTP 403 Forbidden header ($msg1-a message index, not a message) and an
 * error message ($msg2, also a message index), (both required) then end the script
 * subsequent arguments to $msg2 will be passed as parameters only for replacing in $msg2
 * @param $msg1
 * @param $msg2
 */
function wfForbidden( $msg1, $msg2 ) {
	global $wgImgAuthDetails;

	$args = func_get_args();
	array_shift( $args );
	array_shift( $args );
	$args = ( isset( $args[0] ) && is_array( $args[0] ) ) ? $args[0] : $args;

	$msgHdr = wfMessage( $msg1 )->escaped();
	$detailMsgKey = $wgImgAuthDetails ? $msg2 : 'badaccess-group0';
	$detailMsg = wfMessage( $detailMsgKey, $args )->escaped();

	wfDebugLog( 'img_auth',
		"wfForbidden Hdr: " . wfMessage( $msg1 )->inLanguage( 'en' )->text() . " Msg: " .
			wfMessage( $msg2, $args )->inLanguage( 'en' )->text()
	);

	header( 'HTTP/1.0 403 Forbidden' );
	header( 'Cache-Control: no-cache' );
	header( 'Content-Type: text/html; charset=utf-8' );
	echo <<<ENDS
<html>
<body>
<h1>$msgHdr</h1>
<p>$detailMsg</p>
</body>
</html>
ENDS;
}