Apparmor: Allow reading libnl's classid file

Apparmor: Allow reading libnl's classid file

I noticed the following denial messages from apparmor in audit.log when
starting confined VMs via the QEMU driver

type=AVC msg=audit(1623864006.370:837): apparmor="DENIED" operation="open" \
profile="virt-aa-helper" name="/etc/libnl/classid" pid=11265 \
comm="virt-aa-helper" requested_mask="r" denied_mask="r" fsuid=0 ouid=0

type=AVC msg=audit(1623864006.582:849): apparmor="DENIED" operation="open" \
profile="libvirt-0ca2720d-6cff-48bb-86c2-61ab9a79b6e9" \
name="/etc/libnl/classid" pid=11270 comm="qemu-system-x86" \
requested_mask="r" denied_mask="r" fsuid=107 ouid=0

It is possible for site admins to assign names to classids in this file,
which are then used by all libnl tools, possibly those used by libvirt.
To be on the safe side, allow read access to the file in the virt-aa-helper
profile and the libvirt-qemu abstraction.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>