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<title>[46894] trunk: Prevent stored XSS through wp_targeted_link_rel().</title>
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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/46894">46894</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/46894","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>whyisjake</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2019-12-12 17:51:35 +0000 (Thu, 12 Dec 2019)</dd>
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<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>Prevent stored XSS through wp_targeted_link_rel().
Props: vortfu, whyisjake, peterwilsoncc, xknown, SergeyBiryukov, flaviozavan.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpincludesformattingphp">trunk/src/wp-includes/formatting.php</a></li>
<li><a href="#trunktestsphpunittestsformattingWPTargetedLinkRelphp">trunk/tests/phpunit/tests/formatting/WPTargetedLinkRel.php</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunksrcwpincludesformattingphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-includes/formatting.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-includes/formatting.php 2019-12-12 17:50:13 UTC (rev 46893)
+++ trunk/src/wp-includes/formatting.php 2019-12-12 17:51:35 UTC (rev 46894)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -3148,9 +3148,25 @@
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> function wp_targeted_link_rel( $text ) {
</span><span class="cx" style="display: block; padding: 0 10px"> // Don't run (more expensive) regex if no links with targets.
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( stripos( $text, 'target' ) !== false && stripos( $text, '<a ' ) !== false ) {
- if ( ! is_serialized( $text ) ) {
- $text = preg_replace_callback( '|<a\s([^>]*target\s*=[^>]*)>|i', 'wp_targeted_link_rel_callback', $text );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( stripos( $text, 'target' ) === false || stripos( $text, '<a ' ) === false || is_serialized( $text ) ) {
+ return $text;
+ }
+
+ $script_and_style_regex = '/<(script|style).*?<\/\\1>/si';
+
+ preg_match_all( $script_and_style_regex, $text, $matches );
+ $extra_parts = $matches[0];
+ $html_parts = preg_split( $script_and_style_regex, $text );
+
+ foreach ( $html_parts as &$part ) {
+ $part = preg_replace_callback( '|<a\s([^>]*target\s*=[^>]*)>|i', 'wp_targeted_link_rel_callback', $part );
+ }
+
+ $text = '';
+ for ( $i = 0; $i < count( $html_parts ); $i++ ) {
+ $text .= $html_parts[ $i ];
+ if ( isset( $extra_parts[ $i ] ) ) {
+ $text .= $extra_parts[ $i ];
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -3169,9 +3185,18 @@
</span><span class="cx" style="display: block; padding: 0 10px"> * @return string HTML A Element with rel noreferrer noopener in addition to any existing values
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> function wp_targeted_link_rel_callback( $matches ) {
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $link_html = $matches[1];
- $rel_match = array();
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $link_html = $matches[1];
+ $original_link_html = $link_html;
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // Consider the html escaped if there are no unescaped quotes
+ $is_escaped = ! preg_match( '/(^|[^\\\\])[\'"]/', $link_html );
+ if ( $is_escaped ) {
+ // Replace only the quotes so that they are parsable by wp_kses_hair, leave the rest as is
+ $link_html = preg_replace( '/\\\\([\'"])/', '$1', $link_html );
+ }
+
+ $atts = wp_kses_hair( $link_html, wp_allowed_protocols() );
+
</ins><span class="cx" style="display: block; padding: 0 10px"> /**
</span><span class="cx" style="display: block; padding: 0 10px"> * Filters the rel values that are added to links with `target` attribute.
</span><span class="cx" style="display: block; padding: 0 10px"> *
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -3182,35 +3207,21 @@
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> $rel = apply_filters( 'wp_targeted_link_rel', 'noopener noreferrer', $link_html );
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- // Avoid additional regex if the filter removes rel values.
- if ( ! $rel ) {
- return "<a $link_html>";
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ // Return early if no rel values to be added or if no actual target attribute
+ if ( ! $rel || ! isset( $atts['target'] ) ) {
+ return "<a $original_link_html>";
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- // Value with delimiters, spaces around are optional.
- $attr_regex = '|rel\s*=\s*?(\\\\{0,1}["\'])(.*?)\\1|i';
- preg_match( $attr_regex, $link_html, $rel_match );
-
- if ( empty( $rel_match[0] ) ) {
- // No delimiters, try with a single value and spaces, because `rel = va"lue` is totally fine...
- $attr_regex = '|rel\s*=(\s*)([^\s]*)|i';
- preg_match( $attr_regex, $link_html, $rel_match );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( isset( $atts['rel'] ) ) {
+ $all_parts = preg_split( '/\s/', "{$atts['rel']['value']} $rel", -1, PREG_SPLIT_NO_EMPTY );
+ $rel = implode( ' ', array_unique( $all_parts ) );
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( ! empty( $rel_match[0] ) ) {
- $parts = preg_split( '|\s+|', strtolower( $rel_match[2] ) );
- $parts = array_map( 'esc_attr', $parts );
- $needed = explode( ' ', $rel );
- $parts = array_unique( array_merge( $parts, $needed ) );
- $delimiter = trim( $rel_match[1] ) ? $rel_match[1] : '"';
- $rel = 'rel=' . $delimiter . trim( implode( ' ', $parts ) ) . $delimiter;
- $link_html = str_replace( $rel_match[0], $rel, $link_html );
- } elseif ( preg_match( '|target\s*=\s*?\\\\"|', $link_html ) ) {
- $link_html .= " rel=\\\"$rel\\\"";
- } elseif ( preg_match( '#(target|href)\s*=\s*?\'#', $link_html ) ) {
- $link_html .= " rel='$rel'";
- } else {
- $link_html .= " rel=\"$rel\"";
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $atts['rel']['whole'] = 'rel="' . esc_attr( $rel ) . '"';
+ $link_html = join( ' ', array_column( $atts, 'whole' ) );
+
+ if ( $is_escaped ) {
+ $link_html = preg_replace( '/[\'"]/', '\\\\$0', $link_html );
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> return "<a $link_html>";
</span></span></pre></div>
<a id="trunktestsphpunittestsformattingWPTargetedLinkRelphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/tests/phpunit/tests/formatting/WPTargetedLinkRel.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/tests/phpunit/tests/formatting/WPTargetedLinkRel.php 2019-12-12 17:50:13 UTC (rev 46893)
+++ trunk/tests/phpunit/tests/formatting/WPTargetedLinkRel.php 2019-12-12 17:51:35 UTC (rev 46894)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -38,7 +38,7 @@
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> public function test_rel_with_single_quote_delimiter() {
</span><span class="cx" style="display: block; padding: 0 10px"> $content = '<p>Links: <a href="/" rel=\'existing values\' target="_blank">Existing rel</a></p>';
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $expected = '<p>Links: <a href="/" rel=\'existing values noopener noreferrer\' target="_blank">Existing rel</a></p>';
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $expected = '<p>Links: <a href="/" rel="existing values noopener noreferrer" target="_blank">Existing rel</a></p>';
</ins><span class="cx" style="display: block; padding: 0 10px"> $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -54,12 +54,6 @@
</span><span class="cx" style="display: block; padding: 0 10px"> $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- public function test_rel_value_spaced_and_no_delimiter_and_values_to_escape() {
- $content = '<p>Links: <a href="/" rel = existing"value target="_blank">Existing rel</a></p>';
- $expected = '<p>Links: <a href="/" rel="existing"value noopener noreferrer" target="_blank">Existing rel</a></p>';
- $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
- }
-
</del><span class="cx" style="display: block; padding: 0 10px"> public function test_escaped_quotes() {
</span><span class="cx" style="display: block; padding: 0 10px"> $content = '<p>Links: <a href=\"/\" rel=\"existing values\" target=\"_blank\">Existing rel</a></p>';
</span><span class="cx" style="display: block; padding: 0 10px"> $expected = '<p>Links: <a href=\"/\" rel=\"existing values noopener noreferrer\" target=\"_blank\">Existing rel</a></p>';
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -114,18 +108,14 @@
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- * Ensure correct quotes are used when relation attribute (rel) is missing.
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ * Ensure the content of style and script tags are not processed
</ins><span class="cx" style="display: block; padding: 0 10px"> *
</span><span class="cx" style="display: block; padding: 0 10px"> * @ticket 47244
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- public function test_wp_targeted_link_rel_should_use_correct_quotes() {
- $content = '<p>Links: <a href=\'\/\' target=\'_blank\'>No rel<\/a><\/p>';
- $expected = '<p>Links: <a href=\'\/\' target=\'_blank\' rel=\'noopener noreferrer\'>No rel<\/a><\/p>';
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ public function test_wp_targeted_link_rel_skips_style_and_scripts() {
+ $content = '<style><a href="/" target=a></style><p>Links: <script>console.log("<a href=\'/\' target=a>hi</a>");</script><script>alert(1);</script>here <a href="/" target=_blank>aq</a></p><script>console.log("<a href=\'last\' target=\'_blank\'")</script>';
+ $expected = '<style><a href="/" target=a></style><p>Links: <script>console.log("<a href=\'/\' target=a>hi</a>");</script><script>alert(1);</script>here <a href="/" target="_blank" rel="noopener noreferrer">aq</a></p><script>console.log("<a href=\'last\' target=\'_blank\'")</script>';
</ins><span class="cx" style="display: block; padding: 0 10px"> $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-
- $content = '<p>Links: <a href=\'\/\' target=_blank>No rel<\/a><\/p>';
- $expected = '<p>Links: <a href=\'\/\' target=_blank rel=\'noopener noreferrer\'>No rel<\/a><\/p>';
- $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
</del><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -139,4 +129,10 @@
</span><span class="cx" style="display: block; padding: 0 10px"> $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ public function test_wp_targeted_link_rel_tab_separated_values_are_split() {
+ $content = "<p>Links: <a href=\"/\" target=\"_blank\" rel=\"ugc\t\tnoopener\t\">No rel</a></p>";
+ $expected = '<p>Links: <a href="/" target="_blank" rel="ugc noopener noreferrer">No rel</a></p>';
+ $this->assertEquals( $expected, wp_targeted_link_rel( $content ) );
+ }
+
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span></span></pre>
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