7

I built a custom post type where we can find a standard textarea/tinymce generated by wp_editor() and I'm facing an issue for the saving part.

If I save the content with the following code :

update_post_meta( $post_id, $prefix.'content', $_POST['content'] );

Everything is working fine but there is no security (sanitization, validation etc...)

If I save the content with the following code :

update_post_meta( $post_id, $prefix.'content', sanitize_text_field($_POST['content']) );

I solve the security issue but I lose all the style, media etc.. in the content.

What could be a good way to save the content with all the style applied, the media inserted but including a sanitization ?

I read a bit about wp_kses() but I don't know how I could apply a good filter. (Allowing common tags, which one should I block ? etc..)

  • in general just randomly applying function with "sanitize" in there name might not sanitize and might not add to security. It is impossible to talk about security without full context, but ib general you should probably use one of the wp_kses family. – Mark Kaplun Apr 7 '17 at 11:17
  • try with wp_slash($value) function before convert value. – ravi patel Mar 6 '18 at 6:51
3

In short: it is in dependence of your context, the data inside your editor.

wp_kses() is really helpful and you can define your custom allowed HTML. Alternative you can use the default functions, like wp_kses_post or wp_kses_data. This functions are helpful in ensuring that HTML received from the user only contains white-listed elements. See https://codex.wordpress.org/Data_Validation#HTML.2FXML_Fragments

WordPress define much more functions to sanitize the input, see https://codex.wordpress.org/Validating_Sanitizing_and_Escaping_User_Data and https://codex.wordpress.org/Data_Validation This pages are really helpful.

However in your context should the wp_kses_post function the right choice.

2

Try

//save this in the database
$content=sanitize_text_field( htmlentities($_POST['content']) );

//to display, use
html_entity_decode($content);
  1. htmlentities() will convert all characters which have HTML character entity equivalents to their equivalents.
  2. sanitize_text_field() will then check for invalid UTF-8 characters and strip them off. This can now be stored in the database.
  3. html_entity_decode() will convert HTML entities to their HTML tag equivalents
  • 2
    Please explain why the original poster should use these functions. – Max Yudin Apr 8 '17 at 10:55
  • If you use wp_editor() and you want to save $_POST['youreditor'] with another bunch of options in your own data structure.. this is the way.. I also added wp_kses_post() – Nissar Dec 1 '18 at 3:36
1

You could do someting like this:

/**
 * Most of the 'post' HTML are excepted accept <textarea> itself.
 * @link https://codex.wordpress.org/Function_Reference/wp_kses_allowed_html
 */
$allowed_html = wp_kses_allowed_html( 'post' );

// Remove '<textarea>' tag
unset ( $allowed_html['textarea'] );

/**
 * wp_kses_allowed_html return the wrong values for wp_kses,
 * need to change "true" -> "array()"
 */
array_walk_recursive(
    $allowed_html,
    function ( &$value ) {
        if ( is_bool( $value ) ) {
            $value = array();
        }
    }
);
// Run sanitization.
$value = wp_kses( $value, $allowed_html );

@fuxia: as OP wrote:
"I read a bit about wp_kses() but I don't know how I could apply a good filter. (Allowing common tags, which one should I block ? etc..)"

wp_kses does the following:
"This function makes sure that only the allowed HTML element names, attribute names and attribute values plus only sane HTML entities will occur in $string. You have to remove any slashes from PHP's magic quotes before you call this function."
https://codex.wordpress.org/Function_Reference/wp_kses

My code uses wp_kses with "Allowing common tags". What are the common tags? The list available to read in the given link. It is a long list, so I did not paste it here.
https://codex.wordpress.org/Function_Reference/wp_kses_allowed_html

I think textarea itself should not be allowed in textarea.

@bueltge
wp_kses_post does the same thing, except allow '<textarea>' tag, which - I think - shouldn't be.
https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/kses.php#L1575

function wp_kses_post( $data ) {
    return wp_kses( $data, 'post' );
}
0

wp_slash More information.

update_post_meta( $post_id, $prefix.'content',wp_slash($_POST['content']) );

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.