Changeset 47891

Timestamp:

06/02/2020 11:44:40 PM (5 years ago)

Author:

adamsilverstein

Message:

Formatting: add a new 'safe_style_disallowed_chars' filter.

Enable developers to change the regex used in safecss_filter_attr to limit characters in the parsed CSS.

Props paulschreiber, swissspidy, rmccue, bartekcholewa, miinasikk.
Fixes #37134.

Location:

trunk

Files:

• src/wp-includes/kses.php (modified) (1 diff)
• tests/phpunit/tests/kses.php (modified) (2 diffs)

trunk/src/wp-includes/kses.php

@@ -2302 +2302 @@
         }
 
-        // Remove any CSS containing containing \ ( & } = or comments, except for url() useage checked above.
-        if ( $found && ! preg_match( '%[\\\(&=}]|/\*%', $css_test_string ) ) {
-            if ( '' !== $css ) {
-                $css .= ';';
+        if ( $found ) {
+            /**
+             * Filters the regex limiting the list of characters not allowed in CSS rules.
+             *
+             * Default behaviour is to remove any css containing \ ( & } = or comments, except for url() usage.
+             *
+             * @since 5.5.0
+             *
+             * @param string $regex           Regex pattern of disallowed characters in CSS rules. Default is '%[\\\(&=}]|/\*%'.
+             * @param string $css_test_string CSS value to test.
+             */
+            $disallowed_chars = apply_filters( 'safe_style_disallowed_chars', '%[\\\(&=}]|/\*%', $css_test_string );
+            if ( ! preg_match( $disallowed_chars, $css_test_string ) ) {
+                if ( '' !== $css ) {
+                    $css .= ';';
+                }
+                $css .= $css_item;
             }
-
-            $css .= $css_item;
         }
     }

trunk/tests/phpunit/tests/kses.php

@@ -1003 +1003 @@
                 'expected' => 'background: conic-gradient(at 0% 30%, red 10%, yellow 30%, #1e90ff 50%)',
             ),
-
+            // Expressions are not allowed.
+            array(
+                'css'      => 'height: expression( body.scrollTop + 50 + "px" )',
+                'expected' => '',
+            ),
+            // RGB color values are not allowed.
+            array(
+                'css'      => 'color: rgb( 100, 100, 100 )',
+                'expected' => '',
+            ),
+            // RGBA color values are not allowed.
+            array(
+                'css'      => 'color: rgb( 100, 100, 100, .4 )',
+                'expected' => '',
+            ),
         );
     }
@@ -1248 +1262 @@
         );
     }
+
+    /**
+     * Filter for disallowed characters never matches thus allowing all characters.
+     */
+    function _safe_style_disallowed_chars_filter( $regex ) {
+        return '%a^%'; // Regex with no matches.
+
+    }
+    /**
+     * Testing the safecss_filter_attr() function with the safe_style_disallowed_chars filter.
+     *
+     * @ticket 37134
+     *
+     * @dataProvider data_test_safecss_filter_attr_filtered
+     *
+     * @param string $css      A string of CSS rules.
+     * @param string $expected Expected string of CSS rules.
+     */
+    public function test_safecss_filter_attr_filtered( $css, $expected ) {
+        add_filter( 'safe_style_disallowed_chars', array( $this, '_safe_style_disallowed_chars_filter' ) );
+        $this->assertSame( $expected, safecss_filter_attr( $css ) );
+        remove_filter( 'safe_style_disallowed_chars', array( $this, '_safe_style_disallowed_chars_filter' ) );
+    }
+
+    /**
+     * Data Provider for test_safecss_filter_attr_filtered().
+     *
+     * @return array {
+     *     @type array {
+     *         @string string $css      A string of CSS rules.
+     *         @string string $expected Expected string of CSS rules.
+     *     }
+     * }
+     */
+    public function data_test_safecss_filter_attr_filtered() {
+        return array(
+
+            // A single attribute name, with a single value.
+            array(
+                'css'      => 'margin-top: 2px',
+                'expected' => 'margin-top: 2px',
+            ),
+            // Backslash \ can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'margin-top: \2px',
+                'expected' => 'margin-top: \2px',
+            ),
+            // Curly bracket } can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'margin-bottom: 2px}',
+                'expected' => 'margin-bottom: 2px}',
+            ),
+            // Parenthesis ) can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'margin-bottom: 2px)',
+                'expected' => 'margin-bottom: 2px)',
+            ),
+            // Ampersand & can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'margin-bottom: 2px&',
+                'expected' => 'margin-bottom: 2px&',
+            ),
+            // Expressions can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'height: expression( body.scrollTop + 50 + "px" )',
+                'expected' => 'height: expression( body.scrollTop + 50 + "px" )',
+            ),
+            // RGB color values can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'color: rgb( 100, 100, 100 )',
+                'expected' => 'color: rgb( 100, 100, 100 )',
+            ),
+            // RGBA color values can be allowed with the 'safe_style_disallowed_chars' filter.
+            array(
+                'css'      => 'color: rgb( 100, 100, 100, .4 )',
+                'expected' => 'color: rgb( 100, 100, 100, .4 )',
+            ),
+        );
+    }
 }