* @throws MWException On invalid file.
*/
static function Jpeg( $filename ) {
- $showXMP = function_exists( 'xml_parser_create_ns' );
+ $showXMP = XMPReader::isSupported();
$meta = new self();
$seg = JpegMetadataExtractor::segmentSplitter( $filename );
* @return array Array for storage in img_metadata.
*/
public static function PNG( $filename ) {
- $showXMP = function_exists( 'xml_parser_create_ns' );
+ $showXMP = XMPReader::isSupported();
$meta = new self();
$array = PNGMetadataExtractor::getMetadata( $filename );
$meta->addMetadata( array( 'GIFFileComment' => $baseArray['comment'] ), 'native' );
}
- if ( $baseArray['xmp'] !== '' && function_exists( 'xml_parser_create_ns' ) ) {
+ if ( $baseArray['xmp'] !== '' && XMPReader::isSupported() ) {
$xmp = new XMPReader();
$xmp->parse( $baseArray['xmp'] );
$xmpRes = $xmp->getResults();
/** @var int */
private $extendedXMPOffset = 0;
+ /** @var int Flag determining if the XMP is safe to parse **/
+ private $parsable = 0;
+
+ /** @var string Buffer of XML to parse **/
+ private $xmlParsableBuffer = '';
+
/**
* These are various mode constants.
* they are used to figure out what to do
const NS_RDF = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
const NS_XML = 'http://www.w3.org/XML/1998/namespace';
+ // States used while determining if XML is safe to parse
+ const PARSABLE_UNKNOWN = 0;
+ const PARSABLE_OK = 1;
+ const PARSABLE_BUFFERING = 2;
+ const PARSABLE_NO = 3;
+
/**
* Constructor.
*
array( $this, 'endElement' ) );
xml_set_character_data_handler( $this->xmlParser, array( $this, 'char' ) );
+
+ $this->parsable = self::PARSABLE_UNKNOWN;
+ $this->xmlParsableBuffer = '';
}
/** Destroy the xml parser
xml_parser_free( $this->xmlParser );
}
+ /**
+ * Check if this instance supports using this class
+ */
+ public static function isSupported() {
+ return function_exists( 'xml_parser_create_ns' ) && class_exists( 'XMLReader' );
+ }
+
/** Get the result array. Do some post-processing before returning
* the array, and transform any metadata that is special-cased.
*
wfRestoreWarnings();
}
+ // Ensure the XMP block does not have an xml doctype declaration, which
+ // could declare entities unsafe to parse with xml_parse (T85848/T71210).
+ if ( $this->parsable !== self::PARSABLE_OK ) {
+ if ( $this->parsable === self::PARSABLE_NO ) {
+ throw new Exception( 'Unsafe doctype declaration in XML.' );
+ }
+
+ $content = $this->xmlParsableBuffer . $content;
+ if ( !$this->checkParseSafety( $content ) ) {
+ if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
+ // parse wasn't Unsuccessful yet, so return true
+ // in this case.
+ return true;
+ }
+ $msg = ( $this->parsable === self::PARSABLE_NO ) ?
+ 'Unsafe doctype declaration in XML.' :
+ 'No root element found in XML.';
+ throw new Exception( $msg );
+ }
+ }
+
$ok = xml_parse( $this->xmlParser, $content, $allOfIt );
if ( !$ok ) {
$error = xml_error_string( xml_get_error_code( $this->xmlParser ) );
}
}
+ /**
+ * Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
+ * contain a doctype declaration which could contain a dos attack if we
+ * parse it and expand internal entities (T85848).
+ *
+ * @param string $content xml string to check for parse safety
+ * @return bool true if the xml is safe to parse, false otherwise
+ */
+ private function checkParseSafety( $content ) {
+ $reader = new XMLReader();
+ $result = null;
+
+ // For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
+ // instead of using XML().
+ $reader->open(
+ 'data://text/plain,' . urlencode( $content ),
+ null,
+ LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
+ );
+
+ $oldDisable = libxml_disable_entity_loader( true );
+ $reset = new ScopedCallback(
+ 'libxml_disable_entity_loader',
+ array( $oldDisable )
+ );
+ $reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
+
+ // Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
+ // when parsing truncated XML, which causes unit tests to fail.
+ wfSuppressWarnings();
+ while ( $reader->read() ) {
+ if ( $reader->nodeType === XMLReader::ELEMENT ) {
+ // Reached the first element without hitting a doctype declaration
+ $this->parsable = self::PARSABLE_OK;
+ $result = true;
+ break;
+ }
+ if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
+ $this->parsable = self::PARSABLE_NO;
+ $result = false;
+ break;
+ }
+ }
+ wfRestoreWarnings();
+
+ if ( !is_null( $result ) ) {
+ return $result;
+ }
+
+ // Reached the end of the parsable xml without finding an element
+ // or doctype. Buffer and try again.
+ $this->parsable = self::PARSABLE_BUFFERING;
+ $this->xmlParsableBuffer = $content;
+ return false;
+ }
+
/** When we hit a closing element in MODE_IGNORE
* Check to see if this is the element we started to ignore,
* in which case we get out of MODE_IGNORE
array( 'gps', 'Handling of exif GPS parameters in XMP' ),
);
+ $xmpFiles[] = array( 'doctype-included', 'XMP includes doctype' );
+
foreach ( $xmpFiles as $file ) {
$xmp = file_get_contents( $xmpPath . $file[0] . '.xmp' );
// I'm not sure if this is the best way to handle getting the
$this->assertEquals( $expected, $actual );
}
+
+ /**
+ * Test for multi-section, hostile XML
+ * @covers checkParseSafety
+ */
+ public function testCheckParseSafety() {
+
+ // Test for detection
+ $xmpPath = __DIR__ . '/../../data/xmp/';
+ $file = fopen( $xmpPath . 'doctype-included.xmp', 'rb' );
+ $valid = false;
+ $reader = new XMPReader();
+ do {
+ $chunk = fread( $file, 10 );
+ $valid = $reader->parse( $chunk, feof( $file ) );
+ } while ( !feof( $file ) );
+ $this->assertFalse( $valid, 'Check that doctype is detected in fragmented XML' );
+ $this->assertEquals(
+ array(),
+ $reader->getResults(),
+ 'Check that doctype is detected in fragmented XML'
+ );
+ fclose( $file );
+ unset( $reader );
+
+ // Test for false positives
+ $file = fopen( $xmpPath . 'doctype-not-included.xmp', 'rb' );
+ $valid = false;
+ $reader = new XMPReader();
+ do {
+ $chunk = fread( $file, 10 );
+ $valid = $reader->parse( $chunk, feof( $file ) );
+ } while ( !feof( $file ) );
+ $this->assertTrue(
+ $valid,
+ 'Check for false-positive detecting doctype in fragmented XML'
+ );
+ $this->assertEquals(
+ array(
+ 'xmp-exif' => array(
+ 'DigitalZoomRatio' => '0/10',
+ 'Flash' => '9'
+ )
+ ),
+ $reader->getResults(),
+ 'Check that doctype is detected in fragmented XML'
+ );
+ }
}
dépôts / lhc / web / wiklou.git / commitdiff