Add pre-save content filter to make target=_blank always secure.

Props notnownikki, iseulde, azaozz
Fixes #43187
Built from https://develop.svn.wordpress.org/trunk@42770


git-svn-id: http://core.svn.wordpress.org/trunk@42600 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This commit is contained in:
Andrew Ozz 2018-03-02 14:42:31 +00:00
parent 74cb5936fc
commit de8936588c
3 changed files with 79 additions and 1 deletions

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@ -104,6 +104,21 @@ foreach ( array( 'content_save_pre', 'excerpt_save_pre', 'comment_save_pre', 'pr
add_filter( $filter, 'balanceTags', 50 );
}
// Add proper rel values for links with target.
foreach ( array(
'title_save_pre',
'content_save_pre',
'excerpt_save_pre',
'content_filtered_save_pre',
'pre_comment_content',
'pre_term_description',
'pre_link_description',
'pre_link_notes',
'pre_user_description',
) as $filter ) {
add_filter( $filter, 'wp_targeted_link_rel' );
};
// Format strings for display.
foreach ( array( 'comment_author', 'term_name', 'link_name', 'link_description', 'link_notes', 'bloginfo', 'wp_title', 'widget_title' ) as $filter ) {
add_filter( $filter, 'wptexturize' );

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@ -3023,6 +3023,69 @@ function wp_rel_nofollow_callback( $matches ) {
return "<a $text rel=\"$rel\">";
}
/**
* Adds rel noreferrer and noopener to all HTML A elements that have a target.
*
* @param string $text Content that may contain HTML A elements.
* @return string Converted content.
*/
function wp_targeted_link_rel( $text ) {
// Don't run (more expensive) regex if no links with targets.
if ( stripos( $text, 'target' ) !== false && stripos( $text, '<a ' ) !== false ) {
$text = preg_replace_callback( '|<a\s([^>]*target\s*=[^>]*)>|i', 'wp_targeted_link_rel_callback', $text );
}
return $text;
}
/**
* Callback to add rel="noreferrer noopener" string to HTML A element.
*
* Will not duplicate existing noreferrer and noopener values
* to prevent from invalidating the HTML.
*
* @param array $matches Single Match
* @return string HTML A Element with rel noreferrer noopener in addition to any existing values
*/
function wp_targeted_link_rel_callback( $matches ) {
$link_html = $matches[1];
$rel_match = array();
/**
* Filters the rel values that are added to links with `target` attribute.
*
* @since 5.0.0
*
* @param string The rel values.
* @param string $link_html The matched content of the link tag including all HTML attributes.
*/
$rel = apply_filters( 'wp_targeted_link_rel', 'noopener noreferrer', $link_html );
// 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 );
}
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 );
} else {
$link_html .= " rel=\"$rel\"";
}
return "<a $link_html>";
}
/**
* Convert one smiley code to the icon graphic file equivalent.
*

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@ -4,7 +4,7 @@
*
* @global string $wp_version
*/
$wp_version = '5.0-alpha-42769';
$wp_version = '5.0-alpha-42770';
/**
* Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.