How would I go about preventing users (non Admins/Mods) from uploading their own profile covers?

[Laz]

As the title says, I'm trying to make it so only admins/mods can upload or adjust the cover images for people's profiles. I've looked around the various hooks and what not, but I'm at a loss of how to achieve this.

I was originally thinking I could edit the function of the upload/edit buttons and check if the person has the required permissions; but I cannot seem to find where their functionality is actually defined.