Remote schema security. How can I trust the x-hasura-* headers?

[samuela]

I'm working on stitching together a Remote Schema which will require knowing which users auth. The docs note that Hasura will do its own auth and pass along the auth headers (x-hasura-user-id, x-hasura-role, etc) to my RS backend.

But if my RS backend is publicly accessible, how am I supposed to trust those headers? What's the recommended design pattern here?