--- a/mercurial/wireprototypes.py	Wed Mar 07 16:02:24 2018 -0800
+++ b/mercurial/wireprototypes.py	Wed Mar 07 16:18:52 2018 -0800
@@ -146,3 +146,12 @@
 
         Returns a list of capabilities. The passed in argument can be returned.
         """
+
+    @abc.abstractmethod
+    def checkperm(self, perm):
+        """Validate that the client has permissions to perform a request.
+
+        The argument is the permission required to proceed. If the client
+        doesn't have that permission, the exception should raise or abort
+        in a protocol specific manner.
+        """