Unexpected behaviour when uploading same filename in different subsites (same folder)

[baukezwaan]

Files on subsite specific folders will overwrite other files that already exists in the folder, when in use on another subsite.

Steps to reproduce:

• Create two subsites: subsite A and subsite B
• Switch to subsite A
  • In the Assets-section create an Uploads folder for subsite A (select this in Permission-dropdown)
  • Navigate to folder (observe this is ID 1)
  • Upload an image of a cat in the Uploads folder named animal.jpg
  • Publish the image
  • Go to the file system and check the image in public\assets\Uploads (probably a cat)
• Switch to subsite B
  • In the Assets-section create an Uploads folder for subsite B (select this in Permission-dropdown)
  • Navigate to folder (observe this is ID 3 - different then subsite A folder A)
  • Upload an image of a dog in the Uploads folder named animal.jpg
  • Publish the image
  • Go to the file system and check the image in public\assets\Uploads (spoiler: a dog!)
• Switch back to subsite A
  • see the file of the cat cannot be found

So the database and protected assets do not have a problem with images with the same name + folder. But once the are being published, the file is overwitten without warning. And information is being leaked from one subsite to another.

[michalkleiner]

Nice find!

I guess the proper solution here would be a subsites-aware flysystem adapter of sorts, reflecting the subsite in the public file URL, or a handler that would serve the file dynamically by PHP based on the current subsite, without exposing the file directly from the filesystem itself.

[normann]

No matter what, this seems very severe, the bottom line here is the CMS should not allow users to created folders/files with the same file path across different subsites / main site, because in the file system there is only one location for such folders/files to sit on. Could anyone from the core team on this, please?
Some of our clients are currently suffering from this problem.

[micschk]

An alternative solution/fix may be to remove the Subsites extension from File altogether (depending on use-case).

# Remove subsites from File as it tends to be confusing to authors (and may produce filename collisions)
SilverStripe\Assets\File::remove_extension(SilverStripe\Subsites\Extensions\FileSubsites::class);