We're already using a custom controller to handle direct uploads.
Besides, as mentioned by one of Active Storage co-authors [1], the
Active Storage DirectUploadsController doesn't provide any
authentication or validation at all, meaning anyone could create blobs
in our database by posting to `/rails/active_storage/direct_uploads`.
The response there could be then used to upload any file (again, without
validation) to `/rails/active_storage/disk/`.
For now, we're monkey-patching the controllers in order to send
unauthorized responses, since we aren't using these routes. If we ever
enable direct uploads with Active Storage, we'll have to add some sort
of authentication.
Similar upload solutions like CKEditor don't have this issue since their
controllers inherit from `ApplicationController` (which includes
authorization rules), while Active Storage controllers inherit from
`ActionController::Base`.
[1] https://discuss.rubyonrails.org/t/activestorage-direct-uploads-safe-by-default-how-to-make-it-safe/74863/2
be9c272ce4