node labeling restriction docs (#10944)

content/en/docs/concepts/architecture/nodes.md

@@ -226,11 +226,12 @@ For self-registration, the kubelet is started with the following options:
   - `--register-node` - Automatically register with the API server.
   - `--register-with-taints` - Register the node with the given list of taints (comma separated `<key>=<value>:<effect>`). No-op if `register-node` is false.
   - `--node-ip` - IP address of the node.
-  - `--node-labels` - Labels to add when registering the node in the cluster.
+  - `--node-labels` - Labels to add when registering the node in the cluster (see label restrictions enforced by the [NodeRestriction admission plugin](/docs/reference/access-authn-authz/admission-controllers/#noderestriction) in 1.13+).
   - `--node-status-update-frequency` - Specifies how often kubelet posts node status to master.
 
-Currently, any kubelet is authorized to create/modify any node resource, but in practice it only creates/modifies
-its own. (In the future, we plan to only allow a kubelet to modify its own node resource.)
+When the [Node authorization mode](/docs/reference/access-authn-authz/node/) and 
+[NodeRestriction admission plugin](/docs/reference/access-authn-authz/admission-controllers/#noderestriction) are enabled,
+kubelets are only authorized to create/modify their own Node resource.
 
 #### Manual Node Administration
 

content/en/docs/concepts/configuration/assign-pod-node.md

@@ -92,6 +92,21 @@ For example, the value of `kubernetes.io/hostname` may be the same as the Node n
 and a different value in other environments.
 {{< /note >}}
 
+## Node isolation/restriction
+
+Adding labels to Node objects allows targeting pods to specific nodes or groups of nodes.
+This can be used to ensure specific pods only run on nodes with certain isolation, security, or regulatory properties.
+When using labels for this purpose, choosing label keys that cannot be modified by the kubelet process on the node is strongly recommended.
+This prevents a compromised node from using its kubelet credential to set those labels on its own Node object,
+and influencing the scheduler to schedule workloads to the compromised node.
+
+The `NodeRestriction` admission plugin prevents kubelets from setting or modifying labels with a `node-restriction.kubernetes.io/` prefix.
+To make use of that label prefix for node isolation:
+
+1. Ensure you are using the [Node authorizer](/docs/reference/access-authn-authz/node/) and have enabled the [NodeRestriction admission plugin](/docs/reference/access-authn-authz/admission-controllers/#noderestriction).
+2. Add labels under the `node-restriction.kubernetes.io/` prefix to your Node objects, and use those labels in your node selectors.
+For example, `example.com.node-restriction.kubernetes.io/fips=true` or `example.com.node-restriction.kubernetes.io/pci-dss=true`.
+
 ## Affinity and anti-affinity
 
 `nodeSelector` provides a very simple way to constrain pods to nodes with particular labels. The affinity/anti-affinity

content/en/docs/reference/access-authn-authz/admission-controllers.md

@@ -415,6 +415,25 @@ This admission controller limits the `Node` and `Pod` objects a kubelet can modi
 kubelets must use credentials in the `system:nodes` group, with a username in the form `system:node:<nodeName>`.
 Such kubelets will only be allowed to modify their own `Node` API object, and only modify `Pod` API objects that are bound to their node.
 In Kubernetes 1.11+, kubelets are not allowed to update or remove taints from their `Node` API object.
+
+In Kubernetes 1.13+, the `NodeRestriction` admission plugin prevents kubelets from deleting their `Node` API object,
+and enforces kubelet modification of labels under the `kubernetes.io/` or `k8s.io/` prefixes as follows:
+
+* **Prevents** kubelets from adding/removing/updating labels with a `node-restriction.kubernetes.io/` prefix.
+This label prefix is reserved for administrators to label their `Node` objects for workload isolation purposes,
+and kubelets will not be allowed to modify labels with that prefix.
+* **Allows** kubelets to add/remove/update these labels and label prefixes:
+  * `kubernetes.io/hostname`
+  * `beta.kubernetes.io/arch`
+  * `beta.kubernetes.io/instance-type`
+  * `beta.kubernetes.io/os`
+  * `failure-domain.beta.kubernetes.io/region`
+  * `failure-domain.beta.kubernetes.io/zone`
+  * `kubelet.kubernetes.io/`-prefixed labels
+  * `node.kubernetes.io/`-prefixed labels
+
+Use of any other labels under the `kubernetes.io` or `k8s.io` prefixes by kubelets is reserved, and may be disallowed or allowed by the `NodeRestriction` admission plugin in the future.
+
 Future versions may add additional restrictions to ensure kubelets have the minimal set of permissions required to operate correctly.
 
 ### OwnerReferencesPermissionEnforcement {#ownerreferencespermissionenforcement}