[libvirt] LXC: capset fails with userns

Daniel P. Berrange berrange at redhat.com
Wed Feb 26 15:19:49 UTC 2014


On Wed, Feb 26, 2014 at 08:54:02AM -0600, Serge Hallyn wrote:
> Quoting Stephan Sachse (ste.sachse at gmail.com):
> > for me there is no valid reason why a container is not allowed to set
> > file capabilities.
> 
> (For the sake of the libvir-list, I replied to this on the lxc-devel@
> list with a proposal that should work;  but this particular patch is
> not safe, as nothing would stop an unprivileged user from mapping 0
> to his uid in a new namespace, adding CAP_SYS_ADMIN, getting back to
> the init namespace, and running it with privilege.  Adding a new
> capability format which adds the kuid_t of the user_ns root would
> solve this.  Thanks Stephan for pushing on this.)

Thanks, I thought there would be some good reason for this restriction.

Regards,
Daniel
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