The module generates RBAC for users and implements the basic multi-tenancy mode with namespace-based access.

Also, it implements the role-based subsystem for end-to-end authorization, thereby extending the functionality of the standard RBAC mechanism.

All the configuration of access rights is performed using Custom Resources.

Module features

  • Manages user and group access control using Kubernetes RBAC;
  • Manages access to scaling tools (the allowScale parameter of the ClusterAuthorizationRule Custom Resource);
  • Manages access to port forwarding (the portForwarding parameter of the ClusterAuthorizationRule Custom Resource);
  • Manages the list of allowed namespaces with a labelSelector (the namespaceSelector parameter of the ClusterAuthorizationRule Custom Resource);
  • Manages the list of allowed namespaces as regular expressions (the limitNamespaces deprecated parameter of the ClusterAuthorizationRule Custom Resource);
  • Manages access to system namespaces such as kube-system, etc., (the allowAccessToSystemNamespaces parameter of the ClusterAuthorizationRule Custom Resource);

Role model

In addition to the RBAC, you can use a set of high-level roles in the module:

  • User — has access to information about all objects (including viewing pod logs) but cannot exec into containers, read secrets, and perform port-forwarding;
  • PrivilegedUser — the same as User + can exec into containers, read secrets, and delete pods (and thus, restart them);
  • Editor — is the same as PrivilegedUser + can create and edit all objects that are usually required for application tasks.
  • Admin — the same as Editor + can delete service objects (auxiliary resources such as ReplicaSet, certmanager.k8s.io/challenges and certmanager.k8s.io/orders);
  • ClusterEditor — the same as Editor + can manage a limited set of cluster-wide objects that can be used in application tasks (ClusterXXXMetric, KeepalivedInstance, DaemonSet, etc.). This role is best suited for cluster operators.
  • ClusterAdmin — the same as both ClusterEditor and Admin + can manage cluster-wide service objects (e.g., MachineSets, Machines, OpenstackInstanceClasses…, as well as ClusterAuthorizationRule, ClusterRoleBindings and ClusterRole). This role is best suited for cluster administrators. Note that since ClusterAdmin can edit ClusterRoleBindings, he can broaden his privileges within the cluster;
  • SuperAdmin — can perform any actions with any objects (note that namespaceSelector and limitNamespaces restrictions remain valid).

Implementation nuances

Caution! Currently, the multi-tenancy mode (namespace-based authorization) is implemented according to a temporary scheme and isn’t guaranteed to be entirely safe and secure!

If a ClusterAuthorizationRule Custom Resource contains the namespaceSelector field, neither limitNamespaces nor allowAccessToSystemNamespacesare taken into consideration.

The allowAccessToSystemNamespaces, namespaceSelector and limitNamespaces options in the CR will no longer be applied if the authorization system’s webhook is unavailable for some reason. As a result, users will have access to all namespaces. After the webhook availability is restored, the options will become relevant again.

Default access list for each role

verbs aliases:

  • read - get, list, watch
  • read-write - get, list, watch, create, delete, deletecollection, patch, update
  • write - create, delete, deletecollection, patch, update

Role User:

read:
    - apiextensions.k8s.io/customresourcedefinitions
    - apps/daemonsets
    - apps/deployments
    - apps/replicasets
    - apps/statefulsets
    - autoscaling.k8s.io/verticalpodautoscalers
    - autoscaling/horizontalpodautoscalers
    - batch/cronjobs
    - batch/jobs
    - configmaps
    - discovery.k8s.io/endpointslices
    - endpoints
    - events
    - events.k8s.io/events
    - extensions/daemonsets
    - extensions/deployments
    - extensions/ingresses
    - extensions/replicasets
    - extensions/replicationcontrollers
    - limitranges
    - metrics.k8s.io/nodes
    - metrics.k8s.io/pods
    - namespaces
    - networking.k8s.io/ingresses
    - networking.k8s.io/networkpolicies
    - nodes
    - persistentvolumeclaims
    - persistentvolumes
    - pods
    - pods/log
    - policy/poddisruptionbudgets
    - rbac.authorization.k8s.io/rolebindings
    - rbac.authorization.k8s.io/roles
    - replicationcontrollers
    - resourcequotas
    - serviceaccounts
    - services
    - storage.k8s.io/storageclasses

Role PrivilegedUser (includes all rules from the role User):

create:
    - pods/eviction
create,get:
    - pods/attach
    - pods/exec
delete,deletecollection:
    - pods
read:
    - secrets

Role Editor (includes all rules from the role User, PrivilegedUser):

read-write:
    - apps/deployments
    - apps/statefulsets
    - autoscaling.k8s.io/verticalpodautoscalers
    - autoscaling/horizontalpodautoscalers
    - batch/cronjobs
    - batch/jobs
    - configmaps
    - discovery.k8s.io/endpointslices
    - endpoints
    - extensions/deployments
    - extensions/ingresses
    - networking.k8s.io/ingresses
    - persistentvolumeclaims
    - policy/poddisruptionbudgets
    - serviceaccounts
    - services
write:
    - secrets

Role Admin (includes all rules from the role User, PrivilegedUser, Editor):

create,patch,update:
    - pods
delete,deletecollection:
    - apps/replicasets
    - extensions/replicasets

Role ClusterEditor (includes all rules from the role User, PrivilegedUser, Editor):

read:
    - rbac.authorization.k8s.io/clusterrolebindings
    - rbac.authorization.k8s.io/clusterroles
write:
    - apiextensions.k8s.io/customresourcedefinitions
    - apps/daemonsets
    - extensions/daemonsets
    - storage.k8s.io/storageclasses

Role ClusterAdmin (includes all rules from the role User, PrivilegedUser, Editor, Admin, ClusterEditor):

read-write:
    - deckhouse.io/clusterauthorizationrules
write:
    - limitranges
    - namespaces
    - networking.k8s.io/networkpolicies
    - rbac.authorization.k8s.io/clusterrolebindings
    - rbac.authorization.k8s.io/clusterroles
    - rbac.authorization.k8s.io/rolebindings
    - rbac.authorization.k8s.io/roles
    - resourcequotas

You can get additional list of access rules for module role from cluster (existing user defined rules and non-default rules from other deckhouse modules):

D8_ROLE_NAME=Editor
kubectl get clusterrole -A -o jsonpath="{range .items[?(@.metadata.annotations.user-authz\.deckhouse\.io/access-level=='$D8_ROLE_NAME')]}{.rules}{'\n'}{end}" | jq -s add