Minimize the admission of privileged containers

Description:

Do not generally permit containers to be run with the 'securityContext.privileged' flag set to 'true'.

Rationale:

Privileged containers have access to all Linux Kernel capabilities and devices. A container running with full privileges can do almost everything that the host can do. This flag exists to allow special use-cases, like manipulating the network stack and accessing devices.

There should be at least one admission control policy defined which does not permit privileged containers.

If you need to run privileged containers, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.

Pods defined with 'spec.containers[].securityContext.privileged: true', 'spec.initContainers[].securityContext.privileged: true' and 'spec.ephemeralContainers[].securityContext.privileged: true' will not be permitted.

Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.

To enable PSA for a namespace in your cluster, set the pod-security.kubernetes.io/enforce label with the policy value you want to enforce.

'kubectl label --overwrite ns NAMESPACE pod-security.kubernetes.io/enforce=restricted'

The above command enforces the restricted policy for the NAMESPACE namespace.

You can also enable Pod Security Admission for all your namespaces. For example:

'kubectl label --overwrite ns --all pod-security.kubernetes.io/warn=baseline'