"failed to open stream: Permission denied" after 777 my entire app

I'm growing several grey hairs trying to work this one out.

All of a sudden in my Laravel project, I can't upload any files to my symlinked public/storage directly as it's complaining about permissions.

I then 777'ed every single file in the app (I know, I know), and it's still complaining about permissions. I've also run composer dump-autoload, which never seems to do anything but I thought I'd give it a go anyway.

Does anyone know what else I can try? I can verify everything is 777, so I can't see why any permissions would fail...

via Chebli Mohamed