The kdbuswreck

To state this clearly: sd-bus allows overriding of both creds mask. By default though the receiving mask sets uid/pid/selinux label/caps, since that what is necessary for basic authentication. The sending mask allows all bits. If you choose to deviate from this, you can freely set other masks, note though that if you suppress the creds necessary for authorization this has the effect that all services that want to authorize will deny access to you, but I figure that's hardly surprising.