Kubernetes Pod and Container Security
External
Internal
Overview
TODO: https://opensource.com/business/15/3/docker-security-tuning
Containers instantiated from container images and running in pods in a Kubernetes cluster are executing by default with container image configuration - for example, the user and the group various container processes run under are by default specified with the USER directive in the container image -, in non-privileged mode and using a pre-defined set of kernel capabilities. The pod and container security contexts, described below, are a declarative method to modify all these run-time settings and get the containers to run with a different run-time configuration. As the name implies, all configuration elements controlled by security contexts are security sensitive.
Pod Security Context
Container Security Context
Pod Security Policy
A pod security policy is a cluster-level API resource that specifies required values or limits for security-sensitive aspects for pod and container configurations, as configured by the pod security context and container security context. If those values are not present in the pod configuration, the pod security policy provides default values. For more details on pod security policies, see:
Privileges and Access Control Settings
The following sections document privileges and access control settings that can be set and modified with pod and container security policies and pod seucirty context.
Privileged Mode
Linux (Kernel) Capabilities
Also see:
Organizatorium
A security context defines privileges and access control settings for containers running in a pod. There is a pod-wide security context:
Each container may have its own security context definition:
The pod security context holds pod-level security attributes and common container settings, which apply to all containers in the pod. Some fields are shared with container security contexts. If the same configuration element is set in both the container security context and the pod security context, the value set in the container security context takes precedence.
Elements specific to the pod security context:
- fsGroup: integer, not quoted in the YAML manifest.
- fsGroupChangePolicy https://kubernetes.io/docs/tasks/configure-pod-container/security-context/#configure-volume-permission-and-ownership-change-policy-for-pods
- supplementalGroups
- sysctls
Elements specific to the container security context:
- privileged
- allowPrivilegeEscalation
- readOnlyRootFilesystem
- capabilities
- procMount
- seccompProfile https://kubernetes.io/docs/tasks/configure-pod-container/security-context/#set-the-seccomp-profile-for-a-container
Elements shared between the pod security context and container security context:
- runAsUser: integer, not quoted in the YAML manifest.
- runAsGroup: integer, not quoted in the YAML manifest.
- runAsNonRoot
- seLinuxOptions