RBAC not working as expected when trying to lock namespace - kubernetes

Question

I'm trying to lock down a namespace in kubernetes using RBAC so I followed this tutorial.
I'm working on a baremetal cluster (no minikube, no cloud provider) and installed kubernetes using Ansible.
I created the folowing namespace :
apiVersion: v1
kind: Namespace
metadata:
name: lockdown
Service account :
apiVersion: v1
kind: ServiceAccount
metadata:
name: sa-lockdown
namespace: lockdown
Role :
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: lockdown
rules:
- apiGroups: [""] # "" indicates the core API group
resources: [""]
verbs: [""]
RoleBinding :
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: rb-lockdown
subjects:
- kind: ServiceAccount
name: sa-lockdown
roleRef:
kind: Role
name: lockdown
apiGroup: rbac.authorization.k8s.io
And finally I tested the authorization using the next command
kubectl auth can-i get pods --namespace lockdown --as system:serviceaccount:lockdown:sa-lockdown
This SHOULD be returning "No" but I got "Yes" :-(
What am I doing wrong ?
Thx

Answer 1

A couple possibilities:
are you running the "can-i" check against the secured port or unsecured port (add --v=6 to see). Requests made against the unsecured (non-https) port are always authorized.
RBAC is additive, so if there is an existing clusterrolebinding or rolebinding granting "get pods" permissions to that service account (or one of the groups system:serviceaccounts:lockdown, system:serviceaccounts, or system:authenticated), then that service account will have that permission. You cannot "ungrant" permissions by binding more restrictive roles

Answer 2

I finally found what was the problem.
The role and rolebinding must be created inside the targeted namespace.
I changed the following role and rolebinding types by specifying the namespace inside the yaml directly.
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: lockdown
namespace: lockdown
rules:
- apiGroups:
- ""
resources:
- pods
verbs:
- get
- watch
- list
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: rb-lockdown
namespace: lockdown
subjects:
- kind: ServiceAccount
name: sa-lockdown
roleRef:
kind: Role
name: lockdown
apiGroup: rbac.authorization.k8s.io
In this example I gave permission to the user sa-lockdown to get, watch and list the pods in the namespace lockdown.
Now if I ask to get the pods : kubectl auth can-i get pods --namespace lockdown --as system:serviceaccount:lockdown:sa-lockdown it will return yes.
On the contrary if ask to get the deployments : kubectl auth can-i get deployments --namespace lockdown --as system:serviceaccount:lockdown:sa-lockdown it will return no.
You can also leave the files like they were in the question and simply create them using kubectl create -f <file> -n lockdown.