[ACM/XEND] Fix case where resource label file does not exist.

Fix the case where the resource label file does not exist but its
contents would be needed for access control evaluations.

Signed-off-by: Stefan Berger <stefanb@us.ibm.com>

tools/python/xen/util/security.py

@@ -934,7 +934,8 @@ def resources_compatible_with_vmlabel(xspol, dominfo, vmlabel):
             access_control = dictio.dict_read("resources",
                                               res_label_filename)
         except:
-            return False
+            # No labeled resources -> must be compatible
+            return True
         return __resources_compatible_with_vmlabel(xspol, dominfo, vmlabel,
                                                    access_control)
     finally:
@@ -950,6 +951,7 @@ def __resources_compatible_with_vmlabel(xspol, dominfo, vmlabel,
         given VM label. The access_control parameter provides a
         dictionary of the resource name to resource label mappings
         under which the evaluation should be done.
+        Call this only for a paused or running domain.
     """
     def collect_labels(reslabels, s_label, polname):
         if len(s_label) != 3 or polname != s_label[1]:
@@ -1204,7 +1206,7 @@ def change_acm_policy(bin_pol, del_array, chg_array,
         access_control = {}
         try:
             access_control = dictio.dict_read("resources", res_label_filename)
-        finally:
+        except:
             pass
         for key, labeldata in access_control.items():
             if len(labeldata) == 2: