[ACM] Fix the resource representations in the resource_label

file. Without this patch, multiple representations of the same
resource can co-exist in the resource label file and lead to errors
during operation.

Ensures that all resource file names are stored with absolute
path name and are unique. Setting labels of phy-resources, relative
paths will automatically be pre-pended with '/dev/'; labeling
file-resources with relative paths will raise an error.

Signed-off by: Reiner Sailer <sailer@us.ibm.com>

tools/python/xen/util/security.py

@@ -596,12 +596,34 @@ def get_res_security_details(resource):
     return (label, ssidref, policy)
 
 
+def unify_resname(resource):
+    """Makes all resource locations absolute. In case of physical
+    resources, '/dev/' is added to local file names"""
+
+    # sanity check on resource name
+    (type, resfile) = resource.split(":")
+    if type == "phy":
+        if not resfile.startswith("/"):
+            resfile = "/dev/" + resfile
+
+    #file: resources must specified with absolute path
+    if (not resfile.startswith("/")) or (not os.path.exists(resfile)):
+        err("Invalid resource.")
+
+    # from here on absolute file names with resources
+    resource = type + ":" + resfile
+    return resource
+
+
 def res_security_check(resource, domain_label):
     """Checks if the given resource can be used by the given domain
        label.  Returns 1 if the resource can be used, otherwise 0.
     """
     rtnval = 1
 
+    #build canonical resource name
+    resource = unify_resname(resource)
+
     # if security is on, ask the hypervisor for a decision
     if on():
         (label, ssidref, policy) = get_res_security_details(resource)

tools/python/xen/xm/addlabel.py

@@ -72,13 +72,8 @@ def add_resource_label(label, resource, policyref):
     # sanity check: make sure this label can be instantiated later on
     ssidref = security.label2ssidref(label, policyref, 'res')
 
-    # sanity check on resource name
-    (type, file) = resource.split(":")
-    if type == "phy":
-        file = "/dev/" + file
-    if not os.path.exists(file):
-        print "Invalid resource '"+resource+"'"
-        return
+    #build canonical resource name
+    resource = security.unify_resname(resource)
 
     # see if this resource is already in the file
     access_control = {}

tools/python/xen/xm/getlabel.py

@@ -33,6 +33,9 @@ def help():
 def get_resource_label(resource):
     """Gets the resource label
     """
+    #build canonical resource name
+    resource = security.unify_resname(resource)
+
     # read in the resource file
     file = security.res_label_filename
     try:

tools/python/xen/xm/rmlabel.py

@@ -37,6 +37,9 @@ def help():
 def rm_resource_label(resource):
     """Removes a resource label from the global resource label file.
     """
+    #build canonical resource name
+    resource = security.unify_resname(resource)
+
     # read in the resource file
     file = security.res_label_filename
     try: