NetworkManager runs as root and has lots of capabilities.
We want to reduce the attach surface by dropping capabilities,
but there is a genuine need to do certain things.
For example, we currently require dac_override capability, to open
the unix socket of ovsdb. Most users wouldn't use OVS, so we should
find a way to not require that dac_override capability. The solution
is to have a separate, D-Bus activate service (nm-sudo), which
has the capability to open and provide the file descriptor.
For authentication, we only rely on D-Bus. We watch the name owner
of NetworkManager, and only accept requests from that service. We trust
D-Bus to get it right a request from that name owner is really coming
from NetworkManager. If we couldn't trust that, how could PolicyKit
or any authentication via D-Bus work? For testing, the user can set
NM_SUDO_NO_AUTH_FOR_TESTING=1.
https://bugzilla.redhat.com/show_bug.cgi?id=1921826
f137b32d31