revisit squash (secure mode) permissions

[mitchdraft]

can privileged status be removed? Does squash still need the ability to create serviceaccounts, clusterroles and clusterrolebindings?

[mitchdraft]

Also restrict squash to creating debugger pods in the squash-debugger namespace only.

[orlando-jamie]

I had some success deploying squash with the following. Also removes the ability to create service accounts, cluster roles, and cluster role bindings.

The next big question, I would ask, is does plank really need to be able to use all verbs over customresourcedefinitions? Is allowing plank to manage the debugattachments really not enough?

---
# Namespace - squash-debugger
apiVersion: v1
kind: Namespace
metadata:
  name: squash-debugger

---
# Deployment - Squash
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
  labels:
    app: squash
  name: squash
  namespace: squash-debugger
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: squash
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: squash
    spec:
      containers:
      - env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.namespace
        - name: HOST_ADDR
          value: $(POD_NAME).$(POD_NAMESPACE)
        - name: NODE_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        image: soloio/squash:dev
        imagePullPolicy: IfNotPresent
        name: squash
        ports:
        - containerPort: 1234
          name: http
          protocol: TCP
        resources: {}
        securityContext:
          privileged: true
          procMount: Default
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /var/run/cri.sock
          name: crisock
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      serviceAccount: squash
      serviceAccountName: squash
      terminationGracePeriodSeconds: 30
      volumes:
      - hostPath:
          path: /var/run/dockershim.sock
          type: ""
        name: crisock

---
# Service Account - Squash
apiVersion: v1
kind: ServiceAccount
metadata:
  name: squash
  namespace: squash-debugger

---
# Role Binding - Squash
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: squash-rb-pods
  namespace: squash-debugger
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: squash-r-pods
subjects:
- kind: ServiceAccount
  name: squash
  namespace: squash-debugger

---
# Role - Squash
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: squash-debugger
  name: squash-r-pods
rules:
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
  - list
  - watch
  - create
  - delete

---
# Cluster Role Binding - Squash
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: squash-crb-pods
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: squash-cr-pods
subjects:
- kind: ServiceAccount
  name: squash
  namespace: squash-debugger

---
# Cluster Role - Squash
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: squash-cr-pods
rules:
- apiGroups:
  - ""
  resources:
  - namespaces
  verbs:
  - list
- apiGroups:
  - squash.solo.io
  resources:
  - debugattachments
  verbs:
  - get
  - list
  - watch
  - create
  - update
  - delete
- apiGroups:
  - apiextensions.k8s.io
  resources:
  - customresourcedefinitions
  verbs:
  - get
  - list
  - watch
  - create
  - update
  - delete
  - register

---
# Service Account - Plank
apiVersion: v1
kind: ServiceAccount
metadata:
  name: squash-plank
  namespace: squash-debugger

---
# Role Binding - Plank
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: squash-plank-rb
  namespace: squash-debugger
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: squash-plank-r
subjects:
- kind: ServiceAccount
  name: squash-plank
  namespace: squash-debugger

---
# Role - Plank
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: squash-plank-r
  namespace: squash-debugger
rules:
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
  - list
  - watch
  - create
  - delete

---
# Cluster Role Binding - Plank
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: squash-plank-crb
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: squash-plank-cr
subjects:
- kind: ServiceAccount
  name: squash-plank
  namespace: squash-debugger

---
# Cluster Role - Plank
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: squash-plank-cr
rules:
- apiGroups:
  - ""
  resources:
  - namespaces
  verbs:
  - list
- apiGroups:
  - squash.solo.io
  resources:
  - debugattachments
  verbs:
  - get
  - list
  - watch
  - create
  - update
  - delete
- apiGroups:
  - apiextensions.k8s.io
  resources:
  - customresourcedefinitions
  verbs:
  - get
  - list
  - watch
  - create
  - update
  - delete

[mitchdraft]

I think you can remove the crd permissions on plank if you are in secure mode. This should be enough when using secure-mode:

# Cluster Role - Plank
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: squash-plank-cr
rules:
- apiGroups:
  - ""
  resources:
  - namespaces
  verbs:
  - list
- apiGroups:
  - squash.solo.io
  resources:
  - debugattachments
  verbs:
  - get
  - list
  - watch
  - update
  - delete

[orlando-jamie]

Thank you very much again for your help @mitchdraft. Sorry to be a bother again, but I missed this one before. Could the squash cluster role also possibly drop permissions for clusterwide CRDs in secure mode as well?

# Cluster Role - Squash
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: squash-cr-pods
rules:
- apiGroups:
  - apiextensions.k8s.io
  resources:
  - customresourcedefinitions
  verbs:
  - get
  - list
  - watch
  - create
  - update
  - delete
  - register

[mitchdraft]

Yes, good observation, all of those crd permissions can be dropped. I think the docs need to be updated since a recent change. Now secure mode requires you to register the DebugAttachment crd yourself, which you can do with: squashctl utils register-resource

[orlando-jamie]

@mitchdraft Thanks again for the help!