[libvirt] [PATCH 0/5] Fix starting of VMs with backing chains containing unknown backing file specification

[Richard W.M. Jones]

On Tue, Sep 09, 2014 at 10:45:43AM +0200, Peter Krempa wrote:
> When a backing chain element specifies a parent in a format not known to libvirt
> we'd fail to start the VM as the chain would appear broken.
> 
> To prevent this happening introduce a new disk type to collect
> unknow format specs and avoid startup failures with such disk type.

I tested the patch series as described here:

  https://bugzilla.redhat.com/show_bug.cgi?id=1134878#c2

and it sort of works.  Instead of the original error, I now get
an SELinux / labelling error:

  process exited while connecting to monitor: 2014-09-09T11:31:12.591266Z qemu-system-x86_64: -drive file=/tmp/test2.img,if=none,id=drive-scsi0-0-0-0,format=qcow2,cache=writeback: could not open disk image /tmp/test2.img: Could not open backing file: Could not open '/tmp/test1.img': Permission denied
 [code=1 domain=10]

because of course the backing file is ignored rather than being
labelled:

  $ ll -Z /tmp/test[12].img
  -rw-rw-r--. rjones rjones unconfined_u:object_r:user_tmp_t:s0 /tmp/test1.img
  -rw-r--r--. rjones rjones unconfined_u:object_r:svirt_image_t:s0:c117,c209 /tmp/test2.img

Now for the case that *I* care about, which is ssh and https backing
files, this doesn't matter because those are not labelled.

Unfortunately this reveals another bug, which is that the SSH_*
variables that are required by the ssh driver are not passed through
to libvirtd.  Ho hum.

Anyway you can add:

  Tested-by: Richard W.M. Jones <rjones at redhat.com>

Rich.

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