Problem

The names of attributes (and hence, the allowed keys for Drupal\Core\Template\Attribute) have a specific constraint outlined by the W3C. Enforce it.

Solution.

The solution relies on the answer to a question - is it the responsibility of Attribute to validate attribute names? Currently the code uses Html::escape on the name attribute, and while this does prevent XSS attacks it also results in invalid attribute names which will cause rendering issues in some browsers and problems for Javascript.

If it is the Attribute class's responsibility to prevent this sort of attack then an outright test is required, with an exception object thrown on failure. If it is not Attribute's responsibility then we should still at least use a runtime assertion to assert() it is true and, further, track down the class in the code that is going to bear this responsibility. This is the sort of validation I'm not sure should be left for the Contrib modules to do, but then again how many of them deal in the creation of new attributes for output?

Disruptive Changes

Regardless of the solution, one test in Drupal\Core\Common\AttributesTest.php breaks because it is testing Html::escaping of attribute names which create escaped output that is an invalid attribute name. This test will need to be amended.

Contrib code should be safe because code creating invalid attributes will not be in a completely functional state anyway.

Comments

Aki Tendo created an issue. See original summary.

joelpittet’s picture

joelpittet
he/him
Primary language English
Location Vancouver
commented

I'd prefer the allow attributes to work with XML and not just be scoped for HTML, we did this in D7 and below with locking down to HTML and and D8 we can now generate much easier content that is not HTML, I'd like to keep this idea in mind.

Aki Tendo’s picture

Aki Tendo commented

The only difference between the two I'm aware of is XML allows a colon in attribute names to namespace them. The regex I planned on using permits this.

And I agree, we need to support XML.

Version: 8.4.x-dev » 8.5.x-dev

Drupal 8.4.0-alpha1 will be released the week of July 31, 2017, which means new developments and disruptive changes should now be targeted against the 8.5.x-dev branch. For more information see the Drupal 8 minor version schedule and the Allowed changes during the Drupal 8 release cycle.

Version: 8.5.x-dev » 8.6.x-dev

Drupal 8.5.0-alpha1 will be released the week of January 17, 2018, which means new developments and disruptive changes should now be targeted against the 8.6.x-dev branch. For more information see the Drupal 8 minor version schedule and the Allowed changes during the Drupal 8 release cycle.

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Drupal 8.7.0-alpha1 will be released the week of March 11, 2019, which means new developments and disruptive changes should now be targeted against the 8.8.x-dev branch. For more information see the Drupal 8 minor version schedule and the Allowed changes during the Drupal 8 release cycle.

Version: 8.8.x-dev » 8.9.x-dev

Drupal 8.8.0-alpha1 will be released the week of October 14th, 2019, which means new developments and disruptive changes should now be targeted against the 8.9.x-dev branch. (Any changes to 8.9.x will also be committed to 9.0.x in preparation for Drupal 9’s release, but some changes like significant feature additions will be deferred to 9.1.x.). For more information see the Drupal 8 and 9 minor version schedule and the Allowed changes during the Drupal 8 and 9 release cycles.

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Drupal 9.2.0-alpha1 will be released the week of May 3, 2021, which means new developments and disruptive changes should now be targeted for the 9.3.x-dev branch. For more information see the Drupal core minor version schedule and the Allowed changes during the Drupal core release cycle.

Version: 9.3.x-dev » 9.4.x-dev

Drupal 9.3.0-rc1 was released on November 26, 2021, which means new developments and disruptive changes should now be targeted for the 9.4.x-dev branch. For more information see the Drupal core minor version schedule and the Allowed changes during the Drupal core release cycle.

Version: 9.4.x-dev » 9.5.x-dev

Drupal 9.4.0-alpha1 was released on May 6, 2022, which means new developments and disruptive changes should now be targeted for the 9.5.x-dev branch. For more information see the Drupal core minor version schedule and the Allowed changes during the Drupal core release cycle.

Version: 9.5.x-dev » 10.1.x-dev

Drupal 9.5.0-beta2 and Drupal 10.0.0-beta2 were released on September 29, 2022, which means new developments and disruptive changes should now be targeted for the 10.1.x-dev branch. For more information see the Drupal core minor version schedule and the Allowed changes during the Drupal core release cycle.

Version: 10.1.x-dev » 11.x-dev

Drupal core is moving towards using a “main” branch. As an interim step, a new 11.x branch has been opened, as Drupal.org infrastructure cannot currently fully support a branch named main. New developments and disruptive changes should now be targeted for the 11.x branch, which currently accepts only minor-version allowed changes. For more information, see the Drupal core minor version schedule and the Allowed changes during the Drupal core release cycle.

smustgrave’s picture

smustgrave commented
Status: Active » Postponed (maintainer needs more info)
Issue tags: +stale-issue-cleanup

Thank you for creating this issue to improve Drupal.

We are working to decide if this task is still relevant to a currently supported version of Drupal. There hasn't been any discussion here for over 8 years which suggests that this has either been implemented or is no longer relevant. Your thoughts on this will allow a decision to be made.

Since we need more information to move forward with this issue, the status is now Postponed (maintainer needs more info). If we don't receive additional information to help with the issue, it may be closed after three months.

Thanks!

Version: 11.x-dev » main

Drupal core is now using the main branch as the primary development branch. New developments and disruptive changes should now be targeted to the main branch.

Read more in the announcement.