jenkins-bot has submitted this change and it was merged.
Change subject: displaytitle: reject some CSS if $wgRestrictDisplayTitle set
......................................................................
displaytitle: reject some CSS if $wgRestrictDisplayTitle set
$wgRestrictDisplayTitle is intended to make it possible to simply
copy-and-paste the title text even if it requires some styling like
subscript or superscript. Using a <span style="display: none;" />
broke that expectation, as the text hidden in such way becomes
completely invisible and unselectable. This patch rejects such styles.
Also disallowed 'user-select' and 'visibility', since they both
prevent the user from selecting and/or copying the text as well.
Minor changes in Sanitizer:
* checkCss() was made to pass through values which consist of nothing
but a single comment, to allow this rejection to display some sort
of a notification to the user.
* encodeTagAttributes() was added as a counterpart to
decodeTagAttributes(), pulling some code out of fixTagAttributes().
Bug: 26547
Change-Id: Ie162535b6bcbebce4ee69f6dcc1957ccccc3c672
---
M includes/DefaultSettings.php
M includes/Sanitizer.php
M includes/parser/CoreParserFunctions.php
M tests/parser/parserTests.txt
M tests/phpunit/includes/SanitizerTest.php
5 files changed, 113 insertions(+), 36 deletions(-)
Approvals:
Mattflaschen: Looks good to me, approved
jenkins-bot: Verified
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 9221784..173605c 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -3497,8 +3497,9 @@
$wgAllowDisplayTitle = true;
/**
- * For consistency, restrict DISPLAYTITLE to titles that normalize to the same
- * canonical DB key.
+ * For consistency, restrict DISPLAYTITLE to text that normalizes to the same
+ * canonical DB key. Also disallow some inline CSS rules like display: none;
+ * which can cause the text to be hidden or unselectable.
*/
$wgRestrictDisplayTitle = true;
diff --git a/includes/Sanitizer.php b/includes/Sanitizer.php
index ed01235..b4a1c62 100644
--- a/includes/Sanitizer.php
+++ b/includes/Sanitizer.php
@@ -813,9 +813,10 @@
/**
* Pick apart some CSS and check it for forbidden or unsafe structures.
* Returns a sanitized string. This sanitized string will have
- * character references and escape sequences decoded, and comments
- * stripped. If the input is just too evil, only a comment complaining
- * about evilness will be returned.
+ * character references and escape sequences decoded and comments
+ * stripped (unless it is itself one valid comment, in which case the
value
+ * will be passed through). If the input is just too evil, only a
comment
+ * complaining about evilness will be returned.
*
* Currently URL references, 'expression', 'tps' are forbidden.
*
@@ -856,19 +857,24 @@
$value = preg_replace_callback( $decodeRegex,
array( __CLASS__, 'cssDecodeCallback' ), $value );
- // Remove any comments; IE gets token splitting wrong
- // This must be done AFTER decoding character references and
- // escape sequences, because those steps can introduce comments
- // This step cannot introduce character references or escape
- // sequences, because it replaces comments with spaces rather
- // than removing them completely.
- $value = StringUtils::delimiterReplace( '/*', '*/', ' ', $value
);
+ // Let the value through if it's nothing but a single comment,
to
+ // allow other functions which may reject it to pass some error
+ // message through.
+ if ( !preg_match( '! ^ \s* /\* [^*\\/]* \*/ \s* $ !x', $value )
) {
+ // Remove any comments; IE gets token splitting wrong
+ // This must be done AFTER decoding character
references and
+ // escape sequences, because those steps can introduce
comments
+ // This step cannot introduce character references or
escape
+ // sequences, because it replaces comments with spaces
rather
+ // than removing them completely.
+ $value = StringUtils::delimiterReplace( '/*', '*/', '
', $value );
- // Remove anything after a comment-start token, to guard against
- // incorrect client implementations.
- $commentPos = strpos( $value, '/*' );
- if ( $commentPos !== false ) {
- $value = substr( $value, 0, $commentPos );
+ // Remove anything after a comment-start token, to
guard against
+ // incorrect client implementations.
+ $commentPos = strpos( $value, '/*' );
+ if ( $commentPos !== false ) {
+ $value = substr( $value, 0, $commentPos );
+ }
}
// Reject problematic keywords and control characters
@@ -932,14 +938,7 @@
$decoded = Sanitizer::decodeTagAttributes( $text );
$stripped = Sanitizer::validateTagAttributes( $decoded,
$element );
- $attribs = array();
- foreach ( $stripped as $attribute => $value ) {
- $encAttribute = htmlspecialchars( $attribute );
- $encValue = Sanitizer::safeEncodeAttribute( $value );
-
- $attribs[] = "$encAttribute=\"$encValue\"";
- }
- return count( $attribs ) ? ' ' . implode( ' ', $attribs ) : '';
+ return Sanitizer::safeEncodeTagAttributes( $stripped );
}
/**
@@ -1140,6 +1139,24 @@
}
/**
+ * Build a partial tag string from an associative array of attribute
+ * names and values as returned by decodeTagAttributes.
+ *
+ * @param $assoc_array Array
+ * @return String
+ */
+ public static function safeEncodeTagAttributes( $assoc_array ) {
+ $attribs = array();
+ foreach ( $assoc_array as $attribute => $value ) {
+ $encAttribute = htmlspecialchars( $attribute );
+ $encValue = Sanitizer::safeEncodeAttribute( $value );
+
+ $attribs[] = "$encAttribute=\"$encValue\"";
+ }
+ return count( $attribs ) ? ' ' . implode( ' ', $attribs ) : '';
+ }
+
+ /**
* Pick the appropriate attribute value from a match set from the
* attribs regex matches.
*
diff --git a/includes/parser/CoreParserFunctions.php
b/includes/parser/CoreParserFunctions.php
index be945f7..375ff2b 100644
--- a/includes/parser/CoreParserFunctions.php
+++ b/includes/parser/CoreParserFunctions.php
@@ -363,22 +363,43 @@
static function displaytitle( $parser, $text = '' ) {
global $wgRestrictDisplayTitle;
- #parse a limited subset of wiki markup (just the single quote
items)
+ // parse a limited subset of wiki markup (just the single quote
items)
$text = $parser->doQuotes( $text );
- #remove stripped text (e.g. the UNIQ-QINU stuff) that was
generated by tag extensions/whatever
+ // remove stripped text (e.g. the UNIQ-QINU stuff) that was
generated by tag extensions/whatever
$text = preg_replace( '/' . preg_quote( $parser->uniqPrefix(),
'/' ) . '.*?'
. preg_quote( Parser::MARKER_SUFFIX, '/' ) . '/', '',
$text );
- #list of disallowed tags for DISPLAYTITLE
- #these will be escaped even though they are allowed in normal
wiki text
+ // list of disallowed tags for DISPLAYTITLE
+ // these will be escaped even though they are allowed in normal
wiki text
$bad = array( 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'div',
'blockquote', 'ol', 'ul', 'li', 'hr',
'table', 'tr', 'th', 'td', 'dl', 'dd', 'caption', 'p',
'ruby', 'rb', 'rt', 'rp', 'br' );
- #only requested titles that normalize to the actual title are
allowed through
- #if $wgRestrictDisplayTitle is true (it is by default)
- #mimic the escaping process that occurs in
OutputPage::setPageTitle
- $text = Sanitizer::normalizeCharReferences(
Sanitizer::removeHTMLtags( $text, null, array(), array(), $bad ) );
+ // disallow some styles that could be used to bypass
$wgRestrictDisplayTitle
+ if ( $wgRestrictDisplayTitle ) {
+ $htmlTagsCallback = function ( $params ) {
+ $decoded = Sanitizer::decodeTagAttributes(
$params );
+
+ if ( isset( $decoded['style'] ) ) {
+ // this is called later anyway, but we
need it right now for the regexes below to be safe
+ // calling it twice doesn't hurt
+ $decoded['style'] =
Sanitizer::checkCss( $decoded['style'] );
+
+ if ( preg_match(
'/(display|user-select|visibility)\s*:/i', $decoded['style'] ) ) {
+ $decoded['style'] = '/* attempt
to bypass $wgRestrictDisplayTitle */';
+ }
+ }
+
+ $params = Sanitizer::safeEncodeTagAttributes(
$decoded );
+ };
+ } else {
+ $htmlTagsCallback = null;
+ }
+
+ // only requested titles that normalize to the actual title are
allowed through
+ // if $wgRestrictDisplayTitle is true (it is by default)
+ // mimic the escaping process that occurs in
OutputPage::setPageTitle
+ $text = Sanitizer::normalizeCharReferences(
Sanitizer::removeHTMLtags( $text, $htmlTagsCallback, array(), array(), $bad ) );
$title = Title::newFromText( Sanitizer::stripAllTags( $text ) );
if ( !$wgRestrictDisplayTitle ) {
diff --git a/tests/parser/parserTests.txt b/tests/parser/parserTests.txt
index d5e221a..8995593 100644
--- a/tests/parser/parserTests.txt
+++ b/tests/parser/parserTests.txt
@@ -13290,6 +13290,40 @@
!! end
!! test
+Verify that displaytitle handles inline CSS styles (bug 26547) - rejected value
+!! options
+showtitle
+title=[[Screen]]
+!! config
+wgAllowDisplayTitle=true
+wgRestrictDisplayTitle=true
+!! input
+this is not the the title
+{{DISPLAYTITLE:<span style="display: none;">s</span>creen}}
+!! result
+<span style="/* attempt to bypass $wgRestrictDisplayTitle */">s</span>creen
+<p>this is not the the title
+</p>
+!! end
+
+!! test
+Verify that displaytitle handles inline CSS styles (bug 26547) - accepted value
+!! options
+showtitle
+title=[[Screen]]
+!! config
+wgAllowDisplayTitle=true
+wgRestrictDisplayTitle=true
+!! input
+this is not the the title
+{{DISPLAYTITLE:<span style="color: red;">s</span>creen}}
+!! result
+<span style="color: red;">s</span>creen
+<p>this is not the the title
+</p>
+!! end
+
+!! test
preload: check <noinclude> and <includeonly>
!! options
preload
diff --git a/tests/phpunit/includes/SanitizerTest.php
b/tests/phpunit/includes/SanitizerTest.php
index b745423..38c15ee 100644
--- a/tests/phpunit/includes/SanitizerTest.php
+++ b/tests/phpunit/includes/SanitizerTest.php
@@ -227,10 +227,14 @@
public static function provideCssCommentsFixtures() {
/** array( <expected>, <css>, [message] ) */
return array(
- array( ' ', '/**/' ),
+ // Valid comments spanning entire input
+ array( '/**/', '/**/' ),
+ array( '/* comment */', '/* comment */' ),
+ // Weird stuff
array( ' ', '/****/' ),
- array( ' ', '/* comment */' ),
- array( ' ', "\\2f\\2a foo \\2a\\2f",
+ array( ' ', '/* /* */' ),
+ array( 'display: block;', "display:/* foo */block;" ),
+ array( 'display: block;', "display:\\2f\\2a foo
\\2a\\2f block;",
'Backslash-escaped comments must be stripped
(bug 28450)' ),
array( '', '/* unfinished comment structure',
'Remove anything after a comment-start token' ),
--
To view, visit https://gerrit.wikimedia.org/r/64911
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: merged
Gerrit-Change-Id: Ie162535b6bcbebce4ee69f6dcc1957ccccc3c672
Gerrit-PatchSet: 9
Gerrit-Project: mediawiki/core
Gerrit-Branch: master
Gerrit-Owner: Matmarex <matma....@gmail.com>
Gerrit-Reviewer: CSteipp <cste...@wikimedia.org>
Gerrit-Reviewer: Daniel Friesen <dan...@nadir-seen-fire.com>
Gerrit-Reviewer: Matmarex <matma....@gmail.com>
Gerrit-Reviewer: Mattflaschen <mflasc...@wikimedia.org>
Gerrit-Reviewer: Umherirrender <umherirrender_de...@web.de>
Gerrit-Reviewer: jenkins-bot
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