On Tue, Aug 12, 2008 at 09:20:41AM -0400, Daniel J Walsh wrote:
James Morris wrote:
> On Tue, 12 Aug 2008, Daniel P. Berrange wrote:
>
>> Do we instead add the info the udev rules, so when /dev is
>> populated at boot time by udev the device nodes get the desired
>> initial labelling ? Or do we manually chcon() the device
>> at the time we boot the VM ?
>
> Dan Walsh has mentioned wanting to label the device at VM launch so that
> MCS labels can be dynamically assigned. This raises some other possible
> issues such as revoking any existing access (Linux doesn't have general
> revocation) and having the security of the system depend on whatever is
> performing the relabel (although we can enforce relabelfrom/relabelto
> permissions).
>
> I wonder if existing work/concepts related to MLS device allocation would
> be useful here.
>
> See:
>
http://sourceforge.net/projects/devallocator/
>
>
> - James
The experimenting I have done has been around labeling of the virt_image
and the process with mcs labels to prevent one process from touching
another process/image with a different MCS label.
system_u:system_r:qemu_t:s0:c1 can read/write
system_u:system_r:virt_image_t:s0:c1
But can not read/write system_u:system_r:virt_image_t:s0:c2
or communicate with process system_u:system_r:qemu_t:s0:c2
The idea would be to have libvirt look at the labeling of the image file
and lauch the qemu process with the correct type and matching MCS label.
That's not going to fly for VMs without disks in the host - either totally
diskless VMs, or VMs using iSCSI/NFS network blockdevices / root FS.
Daniel
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