Rewrite MLS constraints to only constrain open for app_data_file, not read/write.

mls

@@ -60,21 +60,37 @@ mlsconstrain unix_stream_socket { connectto }
 mlsconstrain dir_file_class_set { create relabelfrom relabelto }
 	     (l2 eq h2 and (l1 eq l2 or t1 == mlstrustedsubject));
 
+#
+# Constraints for app data files only.
+#
+
+# Only constrain open, not read/write.
+# Also constrain other forms of manipulation, e.g. chmod/chown, unlink, rename, etc.
+# Subject must be equivalent to object unless the subject is trusted.
+mlsconstrain dir { open search setattr rename add_name remove_name reparent rmdir }
+	     (t2 != app_data_file or l1 eq l2 or t1 == mlstrustedsubject);
+mlsconstrain { file lnk_file sock_file } { open setattr unlink link rename }
+	     (t2 != app_data_file or l1 eq l2 or t1 == mlstrustedsubject);
+
+#
+# Constraints for file types other than app data files.
+#
+
 # Read operations: Subject must dominate object unless the subject
 # or the object is trusted.
 mlsconstrain dir { read getattr search }
-	     (l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
+	     (t2 == app_data_file or l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 mlsconstrain { file lnk_file sock_file chr_file blk_file } { read getattr execute }
-	     (l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
+	     (t2 == app_data_file or l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 # Write operations: Subject must be dominated by the object unless the
 # subject or the object is trusted.
 mlsconstrain dir { write setattr rename add_name remove_name reparent rmdir }
-	     (l1 domby l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
+	     (t2 == app_data_file or l1 domby l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 mlsconstrain { file lnk_file sock_file chr_file blk_file } { write setattr append unlink link rename }
-	     (l1 domby l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
+	     (t2 == app_data_file or l1 domby l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 # Special case for FIFOs.
 # These can be unnamed pipes, in which case they will be labeled with the