[lxc-users] Is an unprivileged LXC where the host user itself is mapped to 0 less secure of one where one of its subids is mapped to 0, and why?

[Serge Hallyn]

Quoting Fabio Tudone (fabio at paralleluniverse.co) (fabio at paralleluniverse.co):
> Hi,
> 
> instead of creating "regular" LXC unprivileged containers where all
> the users are mapped to (unprivileged) subuid/gid of my host user,
> I'm considering a mapping where my host user itself will be mapped
> to user 0 (root). They'd be very slim single-app containers.
> 
> The reason is that in this way I don't need the rootfs directory
> subtree, which resides in my user's home, to be namespace-|chmod|to
> a different user and I can delete it with a plain|rm|instead of a
> namespace one.
> 
> Is this kind of LXC less secure than the "regular" one, and why is
> it? What could happen in the worst case?

Don't know what you mean by the regular lxc.  Root in your container
will have full rights to your user-owned files on the host, but that's
it.  That is no different than if you map your host uid into the
container to any other id (since root in the container will have privilege
over your host-uid-owned files in that case).

So in general I recommend against mapping your host user into the container,
but it has its uses (and i do it in one container).