}
/**
- * htmlspecialchars wrapper
+ * Htmlspecialchars wrapper
+ *
+ * @param string $str the string to escape.
+ *
+ * @return string escaped.
*/
function escape($str)
{
return htmlspecialchars($str, ENT_COMPAT, 'UTF-8', false);
}
+/**
+ * Reverse the escape function.
+ *
+ * @param string $str the string to unescape.
+ *
+ * @return string unescaped string.
+ */
+function unescape($str)
+{
+ return htmlspecialchars_decode($str);
+}
+
/**
* Link sanitization before templating
*/
}
/**
- * Remove '>' at start of line auto generated by Shaarli core system
- * to allow markdown blockquotes.
+ * Remove dangerous HTML tags (tags, iframe, etc.).
+ * Doesn't affect <code> content (already escaped by Parsedown).
*
* @param string $description input description text.
*
- * @return string $description without HTML links.
+ * @return string given string escaped.
*/
-function reset_quote_tags($description)
+function sanitize_html($description)
{
- return preg_replace('/^( *)> /m', '$1> ', $description);
+ $escapeTags = array(
+ 'script',
+ 'style',
+ 'link',
+ 'iframe',
+ 'frameset',
+ 'frame',
+ );
+ foreach ($escapeTags as $tag) {
+ $description = preg_replace_callback(
+ '#<\s*'. $tag .'[^>]*>(.*</\s*'. $tag .'[^>]*>)?#is',
+ function ($match) { return escape($match[0]); },
+ $description);
+ }
+ $description = preg_replace(
+ '#(<[^>]+)on[a-z]*="[^"]*"#is',
+ '$1',
+ $description);
+ return $description;
}
/**
* Render shaare contents through Markdown parser.
* 1. Remove HTML generated by Shaarli core.
- * 2. Generate markdown descriptions.
- * 3. Wrap description in 'markdown' CSS class.
+ * 2. Reverse the escape function.
+ * 3. Generate markdown descriptions.
+ * 4. Sanitize sensible HTML tags for security.
+ * 5. Wrap description in 'markdown' CSS class.
*
* @param string $description input description text.
*
$processedDescription = reverse_text2clickable($processedDescription);
$processedDescription = reverse_nl2br($processedDescription);
$processedDescription = reverse_space2nbsp($processedDescription);
- $processedDescription = reset_quote_tags($processedDescription);
+ $processedDescription = unescape($processedDescription);
$processedDescription = $parsedown
->setMarkupEscaped(false)
->setBreaksEnabled(true)
->text($processedDescription);
+ $processedDescription = sanitize_html($processedDescription);
$processedDescription = '<div class="markdown">'. $processedDescription . '</div>';
return $processedDescription;
}
/**
- * Test reset_quote_tags()
+ * Test sanitize_html().
*/
- function testResetQuoteTags()
- {
- $text = '> quote1'. PHP_EOL . ' > quote2 ' . PHP_EOL . 'noquote';
- $processedText = escape($text);
- $reversedText = reset_quote_tags($processedText);
- $this->assertEquals($text, $reversedText);
+ function testSanitizeHtml() {
+ $input = '< script src="js.js"/>';
+ $input .= '< script attr>alert(\'xss\');</script>';
+ $input .= '<style> * { display: none }</style>';
+ $output = escape($input);
+ $input .= '<a href="#" onmouseHover="alert(\'xss\');" attr="tt">link</a>';
+ $output .= '<a href="#" attr="tt">link</a>';
+ $this->assertEquals($output, sanitize_html($input));
+ // Do not touch escaped HTML.
+ $input = escape($input);
+ $this->assertEquals($input, sanitize_html($input));
}
}