Merge pull request #39193 from xilabao/add-rules-failed-message

Automatic merge from submit-queue

add rules not allow message when authorize failed

old result:
```
# ./cluster/kubectl.sh --token=/test get po
Error from server (Forbidden): User "" cannot list pods in the namespace "default".: "<nil>" (get pods)
```
new result:
```
# ./cluster/kubectl.sh --token=/test get po
Error from server (Forbidden): User "" cannot list pods in the namespace "default".: "rules not allow" (get pods)
```

test.yaml
```
kind: Role
apiVersion: rbac.authorization.k8s.io/v1alpha1
metadata:
  name: test
rules:
- apiGroups: ["*"]
  verbs: ["create"]
  resources: ["*"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1alpha1
metadata:
  name: admin-resource-binding
subjects:
  - kind: Group
    name: test
roleRef:
  kind: Role
  name: test
```

pkg/genericapiserver/api/handlers/responsewriters/errors.go

@@ -38,7 +38,12 @@ func Forbidden(attributes authorizer.Attributes, w http.ResponseWriter, req *htt
 	w.Header().Set("Content-Type", "text/plain")
 	w.Header().Set("X-Content-Type-Options", "nosniff")
 	w.WriteHeader(http.StatusForbidden)
-	fmt.Fprintf(w, "%s: %q", msg, reason)
+
+	if len(reason) == 0 {
+		fmt.Fprintf(w, "%s", msg)
+	} else {
+		fmt.Fprintf(w, "%s: %q", msg, reason)
+	}
 }
 
 func forbiddenMessage(attributes authorizer.Attributes) string {

plugin/pkg/auth/authorizer/rbac/rbac.go

@@ -48,7 +48,11 @@ func (r *RBACAuthorizer) Authorize(requestAttributes authorizer.Attributes) (boo
 	glog.V(2).Infof("RBAC DENY: user %q groups %v cannot %q on \"%v.%v/%v\"", requestAttributes.GetUser().GetName(), requestAttributes.GetUser().GetGroups(),
 		requestAttributes.GetVerb(), requestAttributes.GetResource(), requestAttributes.GetAPIGroup(), requestAttributes.GetSubresource())
 
-	return false, fmt.Sprintf("%v", ruleResolutionError), nil
+	reason := ""
+	if ruleResolutionError != nil {
+		reason = fmt.Sprintf("%v", ruleResolutionError)
+	}
+	return false, reason, nil
 }
 
 func New(roles validation.RoleGetter, roleBindings validation.RoleBindingLister, clusterRoles validation.ClusterRoleGetter, clusterRoleBindings validation.ClusterRoleBindingLister) *RBACAuthorizer {