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>

src/security/apparmor/libvirt-qemu

@@ -35,6 +35,8 @@
   @{PROC}/sys/vm/overcommit_memory r,
   # detect hardware capabilities via qemu_getauxval
   owner @{PROC}/*/auxv r,
+  # allow reading libnl's classid file
+  /etc/libnl{,-3}/classid r,
 
   # For hostdev access. The actual devices will be added dynamically
   /sys/bus/usb/devices/ r,

src/security/apparmor/usr.lib.libvirt.virt-aa-helper.in

@@ -19,7 +19,8 @@ profile virt-aa-helper @libexecdir@/virt-aa-helper {
   # Used when internally running another command (namely apparmor_parser)
   @{PROC}/@{pid}/fd/ r,
 
-  @sysconfdir@/libnl-3/classid r,
+  # allow reading libnl's classid file
+  @sysconfdir@/libnl{,-3}/classid r,
 
   # for gl enabled graphics
   /dev/dri/{,*} r,