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Formatting: match CSS function names case-insensitively in safecss_fi… #12949

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Formatting: match CSS function names case-insensitively in safecss_fi… #12949

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19 changes: 12 additions & 7 deletions src/wp-includes/kses.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2554,6 +2554,7 @@ function kses_init() {
* @since 6.6.0 Added support for `grid-column`, `grid-row`, and `container-type`.
* @since 6.9.0 Added support for `white-space`.
* @since 7.1.0 Extended gradient support to allow any single-level nested function.
* CSS function names are now matched case-insensitively.
*
* @param string $css A string of CSS rules, decoded from an HTML `style` attribute.
* @param string $deprecated Not used.
Expand Down Expand Up @@ -2869,19 +2870,22 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
}

if ( $is_custom_var ) {
$css_value = trim( $parts[1] );
$url_attr = str_starts_with( $css_value, 'url(' );
$gradient_attr = str_contains( $css_value, '-gradient(' );
$css_value = trim( $parts[1] );

// CSS function names are ASCII case-insensitive.
$lowercase_css_value = strtolower( $css_value );
$url_attr = str_starts_with( $lowercase_css_value, 'url(' );
$gradient_attr = str_contains( $lowercase_css_value, '-gradient(' );
}
}

if ( $found && $url_attr ) {
// Simplified: matches the sequence `url(*)`.
preg_match_all( '/url\([^)]+\)/', $parts[1], $url_matches );
preg_match_all( '/url\([^)]+\)/i', $parts[1], $url_matches );

foreach ( $url_matches[0] as $url_match ) {
// Clean up the URL from each of the matches above.
preg_match( '/^url\(\s*([\'\"]?)(.*)(\g1)\s*\)$/', $url_match, $url_pieces );
preg_match( '/^url\(\s*([\'\"]?)(.*)(\g1)\s*\)$/i', $url_match, $url_pieces );

if ( empty( $url_pieces[2] ) ) {
$found = false;
Expand All @@ -2906,7 +2910,7 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
* (e.g. rgb(), hsl(), var()). Matching each occurrence, rather than requiring the
* whole value to be a single gradient, lets a gradient combine with a url() image.
*/
preg_match_all( '/(?:repeating-)?(?:linear|radial|conic)-gradient\((?:[^()]|\([^()]*\))*\)/', $css_test_string, $gradient_matches );
preg_match_all( '/(?:repeating-)?(?:linear|radial|conic)-gradient\((?:[^()]|\([^()]*\))*\)/i', $css_test_string, $gradient_matches );

foreach ( $gradient_matches[0] as $gradient_match ) {
// Remove each `gradient()` bit that was matched above from the CSS.
Expand All @@ -2918,9 +2922,10 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
/*
* Allow CSS functions like var(), calc(), etc. by removing them from the test string.
* Nested functions and parentheses are also removed, so long as the parentheses are balanced.
* Function names are matched case-insensitively, as they are in CSS.
*/
$css_test_string = preg_replace(
'/\b(?:var|calc|min|max|minmax|clamp|repeat)(\((?:[^()]|(?1))*\))/',
'/\b(?:var|calc|min|max|minmax|clamp|repeat)(\((?:[^()]|(?1))*\))/i',
'',
$css_test_string
);
Expand Down
80 changes: 80 additions & 0 deletions tests/phpunit/tests/kses.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1003,6 +1003,7 @@ public function test_wp_kses_attr_no_attributes_allowed_with_false() {
* @ticket 64414
* @ticket 65457
* @ticket 64974
* @ticket 65838
*
* @dataProvider data_safecss_filter_attr
*
Expand Down Expand Up @@ -1545,6 +1546,85 @@ public function data_safecss_filter_attr() {
'css' => 'text-anchor: middle',
'expected' => 'text-anchor: middle',
),
/*
* CSS function names are ASCII case-insensitive.
*
* Note that property names remain case-sensitive, so only the
* function part of each value is written in mixed case here.
*/
array(
'css' => 'width: CALC(100% - 10px)',
'expected' => 'width: CALC(100% - 10px)',
),
array(
'css' => 'margin-top: Calc(Var(--wp-var1) * 3 + 2em)',
'expected' => 'margin-top: Calc(Var(--wp-var1) * 3 + 2em)',
),
array(
'css' => 'width: CLAMP(MIN(100px, 350px), 50%, MAX(200px, 25%))',
'expected' => 'width: CLAMP(MIN(100px, 350px), 50%, MAX(200px, 25%))',
),
array(
'css' => 'grid-template-columns: REPEAT(4, MINMAX(0, 1fr))',
'expected' => 'grid-template-columns: REPEAT(4, MINMAX(0, 1fr))',
),
array(
'css' => 'background-image: URL("foo.jpg")',
'expected' => 'background-image: URL("foo.jpg")',
),
array(
'css' => 'background: LINEAR-GRADIENT(135deg,RGBA(6,147,227,1) 0%,rgb(155,81,224) 100%)',
'expected' => 'background: LINEAR-GRADIENT(135deg,RGBA(6,147,227,1) 0%,rgb(155,81,224) 100%)',
),
array(
'css' => 'background: Repeating-Radial-Gradient(red, blue)',
'expected' => 'background: Repeating-Radial-Gradient(red, blue)',
),
array(
'css' => '--with-url-value: URL("foo.jpg");--with-gradient: CONIC-GRADIENT(red, blue)',
'expected' => '--with-url-value: URL("foo.jpg");--with-gradient: CONIC-GRADIENT(red, blue)',
),
// Case-insensitive matching must not let unsafe or malformed values through.
array(
'css' => 'background-image: URL("bad://example.com/invalid.gif")',
'expected' => '',
),
array(
'css' => 'background-image: uRl( "JavaScript:alert(1)" )',
'expected' => '',
),
array(
'css' => 'background: LINEAR-GRADIENT(red, URL(javascript:alert(1)))',
'expected' => '',
),
array(
'css' => 'background-image: URL()',
'expected' => '',
),
array(
'css' => 'width: CALC(3em + 10px',
'expected' => '',
),
array(
'css' => 'width: CALC(3em + (10px * 2)',
'expected' => '',
),
array(
'css' => 'width: EXPRESSION(alert(1))',
'expected' => '',
),
array(
'css' => 'aspect-ratio: EXPRESSION( 16 / 9 )',
'expected' => '',
),
array(
'css' => 'background: UNKNOWN-GRADIENT(135deg,rgba(6,147,227,1) 0%)',
'expected' => '',
),
array(
'css' => 'width: CALCMAX(100px + 50%)',
'expected' => '',
),
);
}

Expand Down
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