RBAC in Kubernetes
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Questions and Answers

Which of the following flags can be used to enable RBAC in the Kubernetes API server?

  • --authorization-config (correct)
  • --enable-rbac
  • --authorization-mode (correct)
  • --rbac-enabled

    • RBAC allows you to define 'deny' rules for access control.

    False (B)

    What are the four kinds of Kubernetes objects declared by the RBAC API?

    Role, ClusterRole, RoleBinding, ClusterRoleBinding

    A ______ always sets permissions within a particular namespace, while a ______ is a non-namespaced resource.

    <p>Role, ClusterRole</p> Signup and view all the answers

    Match the following RBAC objects with their primary function:

    <p>Role = Defines permissions within a single namespace ClusterRole = Defines permissions across all namespaces RoleBinding = Assigns a Role to a user or group within a namespace ClusterRoleBinding = Assigns a ClusterRole to a user or group across all namespaces</p> Signup and view all the answers

    You can use kubectl to create and manage RBAC objects.

    <p>True (A)</p> Signup and view all the answers

    What is the purpose of a RoleBinding?

    <p>To grant the permissions defined in a Role to a user or group.</p> Signup and view all the answers

    Which of these resources can be read by default in the 'core' API group?

    <p>Pods (B)</p> Signup and view all the answers

    A RoleBinding can bind a role to groups, users, or ServiceAccounts.

    <p>True (A)</p> Signup and view all the answers

    What is the prefix reserved for group names in Kubernetes?

    <p>system:</p> Signup and view all the answers

    The API server automatically updates default ______ and ______ with any missing permissions and subjects.

    Signup and view all the answers

    The command kubectl auth reconcile is used to create and manage role bindings.

    <p>True (A)</p> Signup and view all the answers

    Which of the following commands would grant the permissions in the "view" ClusterRole to a service account named "myapp" in the namespace "acme" across the entire cluster?

    <p>kubectl create rolebinding acme-myapp-view-binding --clusterrole view --serviceaccount acme:myapp (A)</p> Signup and view all the answers

    What is the purpose of bootstrapping initial roles and role bindings?

    <p>To grant permissions to the initial user who doesn't have them yet, allowing them to set up subsequent roles and bindings.</p> Signup and view all the answers

    Default RBAC policies in Kubernetes v1.22 or later grant no permissions to service accounts outside the ______ namespace.

    <p>kube-system</p> Signup and view all the answers

    Which of the following is considered the most secure way to grant permissions to an application in Kubernetes?

    <p>Grant a role to an application-specific service account (C)</p> Signup and view all the answers

    When running Kubernetes with both RBAC and ABAC authorizers, if RBAC denies a request, the ABAC authorizer will then be consulted.

    <p>True (A)</p> Signup and view all the answers

    Which of the following is NOT a common way to grant permissions to ServiceAccounts?

    <p>Grant a role to a specific group of users (A)</p> Signup and view all the answers

    What is the purpose of the command kubectl create rolebinding myappnamespace-myapp-view-binding --clusterrole view --serviceaccount myappnamespace:myapp?

    <p>To grant &quot;view&quot; ClusterRole permissions across the entire cluster to the service account &quot;myapp&quot; in the namespace &quot;myappnamespace&quot;.</p> Signup and view all the answers

    Match the following Kubernetes terms with their definitions:

    <p>Role = Defines a set of permissions that can be granted to users, groups, or service accounts RoleBinding = Associates a Role or ClusterRole with a user, group, or service account ClusterRole = Defines a set of permissions that applies to all namespaces in the cluster ServiceAccount = An account that represents an application within a namespace Subject = The entity that will be granted a role (e.g., user, group, service account)</p> Signup and view all the answers

    In order from most secure to least secure, the approaches to granting permissions to ServiceAccounts are: ______, grant a role to all service accounts in a namespace, grant a cluster-wide role to all service accounts, and grant super-user access to all service accounts.

    <p>Grant a role to an application-specific service account</p> Signup and view all the answers

    Kubernetes clusters created with Kubernetes v1.22 or later include write access to Endpoints in the aggregated "edit" and "admin" roles by default.

    <p>False (B)</p> Signup and view all the answers

    What is the primary benefit of using fine-grained role bindings?

    <p>Enhanced security by limiting unnecessary access to API resources.</p> Signup and view all the answers

    Which of the following is NOT a typical method for managing the transition from permissive ABAC policies to RBAC policies?

    <p>Granting cluster-admin permissions to all service accounts (B)</p> Signup and view all the answers

    The command kubectl create rolebinding myappnamespace-myapp-view-binding --clusterrole view --serviceaccount myappnamespace:______ would grant the "view" ClusterRole permissions across the entire cluster to the service account "myapp" in the namespace "myappnamespace".

    <p>myapp</p> Signup and view all the answers

    Kubernetes clusters created before v1.22 included write access to EndpointSlices in the aggregated "edit" and "admin" roles.

    <p>True (A)</p> Signup and view all the answers

    What is the significance of running the kube-apiserver with a log level of 5 or higher for the RBAC component?

    <p>It enables you to view RBAC denial messages in the server logs, which can be used to determine what roles need to be granted.</p> Signup and view all the answers

    What is the prefix for group names in Kubernetes?

    <p>system: (D)</p> Signup and view all the answers

    ServiceAccounts belong to groups with names prefixed with 'system:serviceaccounts:'.

    <p>True (A)</p> Signup and view all the answers

    What are the two types of RBAC objects that bind a role to subjects?

    <p>RoleBinding and ClusterRoleBinding</p> Signup and view all the answers

    To prevent accidental modifications, the API server automatically updates default ______ and ______ with any missing permissions and subjects.

    <p>ClusterRoles, ClusterRoleBindings</p> Signup and view all the answers

    What flag can be used in the API server configuration to disable anonymous unauthenticated access?

    <p>--anonymous-auth=false (C)</p> Signup and view all the answers

    The 'system:node' role is essential for kubelet API access and should be used in modern Kubernetes deployments.

    <p>False (B)</p> Signup and view all the answers

    Name a system: prefixed ClusterRole that is specifically designed for the Kubernetes controller manager.

    <p>system:controller:manager</p> Signup and view all the answers

    When the kube-controller-manager is started with the flag ______, each controller runs using a separate ServiceAccount.

    <p>--use-service-account-credentials</p> Signup and view all the answers

    Which of the following labels is used to identify a ClusterRole that can be added to the 'admin', 'edit', or 'view' roles?

    <p>kubernetes.io/role-aggregation (C)</p> Signup and view all the answers

    The 'edit' role in Kubernetes allows for read/write access to all resources, including the ability to create Roles and RoleBindings.

    <p>False (B)</p> Signup and view all the answers

    What resource does the 'admin' role NOT grant write access to?

    <p>EndpointSlices (or Endpoints)</p> Signup and view all the answers

    The 'view' role does not allow reading ______ as it enables access to secrets and ServiceAccount credentials.

    <p>Secrets</p> Signup and view all the answers

    Match the following roles with their primary function:

    <p>system:node = Legacy role for kubelet API access system:controller:manager = Core controller manager role admin = Read/write access to most resources in a namespace edit = Enhanced read access to all resources in a namespace view = Limited access to resources, providing read-only permissions</p> Signup and view all the answers

    Which of the following statements regarding RoleBinding and ClusterRoleBinding is true?

    <p>A RoleBinding grants permissions within a specific namespace, while a ClusterRoleBinding grants permissions cluster-wide. (C)</p> Signup and view all the answers

    A RoleBinding can reference a ClusterRole and bind that ClusterRole to the namespace of the RoleBinding.

    <p>True (A)</p> Signup and view all the answers

    What is the purpose of the kubectl auth reconcile command-line utility?

    <p>The <code>kubectl auth reconcile</code> command-line utility is used to create or update a manifest file containing RBAC objects and handles deleting and recreating binding objects if required to change the role they refer to.</p> Signup and view all the answers

    In Kubernetes, most resources are represented and accessed using a ______ representation of their object name.

    <p>string</p> Signup and view all the answers

    Match the following RBAC concepts with their definitions:

    <p>Role = A set of permissions that can be granted to users, groups, or service accounts within a specific namespace. ClusterRole = A set of permissions that can be granted to users, groups, or service accounts across the entire Kubernetes cluster. RoleBinding = A mechanism for binding a Role to a specific user, group, or service account within a namespace. ClusterRoleBinding = A mechanism for binding a ClusterRole to a specific user, group, or service account across the entire Kubernetes cluster.</p> Signup and view all the answers

    Which of the following is NOT a valid way to represent resources in an RBAC role?

    <p>Using a colon to delimit resource and subresource, e.g. <code>pods:log</code> for Pod logs (B)</p> Signup and view all the answers

    The resourceNames list in an RBAC role can be used to restrict access to specific instances of a resource.

    <p>True (A)</p> Signup and view all the answers

    What is the purpose of the wildcard (*) symbol in RBAC roles?

    <p>The wildcard (*) symbol in RBAC roles refers to all resources, apiGroups, and verbs.</p> Signup and view all the answers

    Which of the following statements regarding ClusterRole aggregation is true?

    <p>ClusterRole aggregation combines multiple ClusterRoles into one combined ClusterRole. (C), ClusterRole aggregation can be used to create custom roles for specific resources. (D)</p> Signup and view all the answers

    After creating a binding, its roleRef can be changed to reference a different role.

    <p>False (B)</p> Signup and view all the answers

    The ______ defines a label selector that a controller uses to match other ClusterRole objects that should be combined into the rules field of this one.

    <p>aggregationRule</p> Signup and view all the answers

    What is the principle of least privilege in the context of RBAC?

    <p>The principle of least privilege dictates that users, groups, or service accounts should only have access to the resources and permissions they need to perform their assigned tasks.</p> Signup and view all the answers

    What is the purpose of the rules section in a Role or ClusterRole object?

    <p>To define the resources and verbs that the role grants access to. (B)</p> Signup and view all the answers

    A RoleBinding with a namespace of "development" can grant cluster-wide read access for Secrets.

    <p>False (B)</p> Signup and view all the answers

    A ______ can be used to grant cluster-wide access, while a ______ is used to grant access within a specific namespace.

    Signup and view all the answers

    Which of the following statements accurately describes the difference between a RoleBinding and a ClusterRoleBinding?

    <p>A RoleBinding grants permissions within a specific namespace, while a ClusterRoleBinding grants those permissions cluster-wide. (A)</p> Signup and view all the answers

    A RoleBinding can reference a ClusterRole, and bind that ClusterRole's permissions to the namespace of the RoleBinding.

    <p>True (A)</p> Signup and view all the answers

    The name of a [BLANK] or [BLANK] object must be a valid path segment name.

    <p>RoleBinding, ClusterRoleBinding</p> Signup and view all the answers

    What is the primary purpose of the 'kubectl auth reconcile' command-line utility?

    <p>The 'kubectl auth reconcile' command-line utility is designed to help manage RBAC by creating or updating manifest files containing RBAC objects. It handles deleting and recreating binding objects if required to change the role they refer to. It can be used to align existing roles with any required permissions, making sure the system is secure and has the correct access control.</p> Signup and view all the answers

    Match each Kubernetes resource with its corresponding subresource:

    <p>pods = log services = proxy secrets = status endpoints = subsets configmaps = data</p> Signup and view all the answers

    You can use the wildcard symbol '*' to refer to all current and future resources in a specific API group.

    <p>True (A)</p> Signup and view all the answers

    Which of the following statements BEST describes the principle of least privilege when applied to RBAC?

    <p>Granting users the minimal set of permissions needed to perform their tasks. (D)</p> Signup and view all the answers

    What is the mechanism used to aggregate several ClusterRoles into one combined ClusterRole?

    <p>ClusterRole aggregation utilizes a 'aggregationRule' within a ClusterRole. This rule defines a label selector that a controller uses to locate and combine other ClusterRole objects that match the selector, effectively creating a unified ClusterRole with rules from multiple sources.</p> Signup and view all the answers

    The default user-facing roles in Kubernetes leverage ClusterRole aggregation.

    <p>True (A)</p> Signup and view all the answers

    To allow a subject to read pods and also access the [BLANK] subresource for each of those pods, you write: rules: - apiGroups: [''] - resources: ['pods', 'pods/______'] - verbs: ['get', 'list', 'watch']

    <p>log</p> Signup and view all the answers

    How can you create a new ClusterRole that adds rules to an existing aggregated ClusterRole, like 'monitoring'?

    <p>By creating a new ClusterRole with a label that matches the existing aggregated ClusterRole's aggregation selector, then adding the new rules to the new ClusterRole. (D)</p> Signup and view all the answers

    Explain the purpose of the 'resourceNames' list in an RBAC role.

    <p>The 'resourceNames' list within an RBAC role acts as a way to refine access control by restricting operations to specific instances of a resource. If this list is present, it allows access only to the named resource objects, limiting the overall scope of permissions granted.</p> Signup and view all the answers

    You can use a wildcard (*) symbol to refer to all current and future resources in a specific API group, but this approach can lead to overly permissive access to sensitive resources.

    <p>True (A)</p> Signup and view all the answers

    The [BLANK] principle should be employed while defining RBAC roles, ensuring only the necessary permissions are granted for workloads to function correctly.

    <p>least privilege</p> Signup and view all the answers

    When using RBAC, which approach is generally considered the MOST secure way to grant permissions to an application running in Kubernetes?

    <p>Providing the application's ServiceAccount with a RoleBinding that grants the application only the specific permissions needed to function. (B)</p> Signup and view all the answers

    Describe a situation where ClusterRole aggregation would be useful for managing RBAC in a Kubernetes cluster.

    <p>ClusterRole aggregation proves especially useful when managing different sets of related permissions for different workloads. For example, in a cluster hosting multiple microservices, you might create individual ClusterRoles for each service, granting them the specific permissions needed for their respective tasks. Then, you could combine these ClusterRoles into a larger, more general ClusterRole, perhaps named 'microservices' or 'application-roles', to simplify management and ensure all necessary permissions are accessible without needing to individually manage each ClusterRole during updates or changes.</p> Signup and view all the answers

    Flashcards

    RBAC

    Role-based access control (RBAC) regulates access based on user roles.

    Authorization Config

    Starts the API server with roles and permissions defined in RBAC.

    RBAC Objects

    Includes Role, ClusterRole, RoleBinding, and ClusterRoleBinding in Kubernetes.

    Role vs ClusterRole

    A Role is namespace-specific while a ClusterRole is cluster-wide.

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    RoleBinding

    Grants role permissions to users or groups in a specific namespace.

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    ClusterRoleBinding

    Grants ClusterRole permissions to users or groups across all namespaces.

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    Permission Model

    Permissions in RBAC are additive; there are no deny rules.

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    Role Example

    A Role grants read access to pods in a specific namespace.

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    Deployments in apps API

    Objects with 'deployments' in their URL for management in Kubernetes.

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    Roles in Kubernetes

    Define permissions for users, groups, or ServiceAccounts in the cluster.

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    ServiceAccount

    A special type of user account for processes running in a pod.

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    Default ClusterRoles

    Predefined roles managed by the Kubernetes control plane.

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    Auto-reconciliation

    Updates roles/permissions automatically to repair accidental changes.

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    ClusterRole

    Role that grants permissions across the entire cluster.

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    API Server Configuration

    Defines the behavior of Kubernetes API servers including role permissions.

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    Node authorizer

    Manages API access for kubelets based on scheduled pods.

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    RBAC API

    Provides granular control over user permissions in Kubernetes.

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    Creating roles

    Possible only if you have permissions within the same scope.

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    NodeRestriction admission plugin

    Enhances security by limiting kubelet permissions to pods they're scheduled for.

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    Viewing permissions

    Can be done using kubectl to check roles and bindings.

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    RoleReference

    Links a Role or ClusterRole to a RoleBinding.

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    Namespaces

    Isolated environments to manage resources in Kubernetes.

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    pod-reader Role

    Permits reading pods in a specific namespace.

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    Subject

    Users, groups, or service accounts affected by a RoleBinding.

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    Wildcard (*)

    Represents all objects of a resource type in RBAC.

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    AggregationRule

    Defines how to combine ClusterRoles into one.

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    NonResourceURLs

    Paths not related to Kubernetes resources accessed via RBAC.

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    RoleRef

    Specifies which Role or ClusterRole a RoleBinding uses.

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    ResourceNames

    Restricts access to specific instances of a resource.

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    Least Privilege Principle

    Granting only the essential permissions needed.

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    Subresource

    An additional endpoint for modifying part of a resource.

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    Admin Role

    A role that grants full control over resources in a namespace.

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    View Role

    A role that allows reading of resources in a namespace without making changes.

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    Bootstrap Permissions

    Granting initial permissions required to set up roles and role bindings.

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    Fine-Grained Role Bindings

    Specific role assignments to ServiceAccounts for enhanced security.

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    Cluster-Wide Role

    A role that provides permissions to all namespaces in the cluster.

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    Super-User Access

    Complete permissions, allowing full control over all resources.

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    Remove Extra Permissions

    A command option to strip unnecessary permissions from roles.

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    Authorization Layers

    Multiple systems that check if a request has permission to access specific resources.

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    ABAC Policies

    Attribute-Based Access Control policies allowing flexible permission granting.

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    Kubernetes v1.22 Change

    Mitigation for CVE-2021-25740; alters role permissions for security.

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    Study Notes

    Role-Based Access Control (RBAC) in Kubernetes

    • RBAC is a method for controlling access to Kubernetes resources based on user roles.
    • Authorization decisions are driven by the rbac.authorization.k8s.io API group.
    • RBAC policies are dynamically configurable via the Kubernetes API.
    • Enabling RBAC involves starting the API server with the --authorization-config or --authorization-mode flags, specifying a RBAC authorizer.

    RBAC Objects

    • RBAC declares four object types:

      • Role: Namespaced permissions
      • ClusterRole: Cluster-wide permissions
      • RoleBinding: Grants a role to a subject within a namespace
      • ClusterRoleBinding: Grants a role to a subject cluster-wide

    • Roles and ClusterRoles contain permissions (additive).

    • Role permissions are namespace-specific, while ClusterRoles are cluster-wide.

    • Object names must be valid path segment names.

    RoleBindings and ClusterRoleBindings

    • RoleBindings grant roles to subjects within a namespace.
    • They can reference Roles or ClusterRoles.
    • RoleBindings specify subjects (users, groups, service accounts).
    • ClusterRoleBindings grant roles to subjects cluster-wide.
    • Cannot change the referenced Role/ClusterRole after creation; removal and recreation required.

    Resource and Subresource References

    • RBAC uses the same resource names as API endpoints.
    • Subresources (e.g., Pod logs) are delimited with a slash.
    • ResourceNames can be used to restrict access to individual resource instances.
    • Wildcards (*) can be used for all resources, verbs, or API groups (use cautiously, least privilege principle).

    ClusterRole Aggregation

    • ClusterRoles can be aggregated to combine multiple ClusterRoles into one.
    • Aggregation is triggered by an aggregationRule that uses a label selector.
    • Aggregated ClusterRoles dynamically incorporate new, matching ClusterRoles.

    Default RBAC Policies

    • Kubernetes includes default ClusterRoles and ClusterRoleBindings for core functionalities.
    • Many are prefixed with system:.
    • These default objects are dynamically updated by the API server to account for missing permissions/subjects and newly released permissions.
    • The update process can be disabled using an annotation.
    • Some roles (e.g., cluster-admin, admin, edit, view) are user-facing.
      • Can be extended via ClusterRole aggregation for custom resource.

    RBAC Principles and Considerations

    • RBAC prevents privilege escalation by controlling role/binding changes.
    • Only create/update roles if permissions are already granted or bind permission is granted.
    • Auto-reconciliation adjusts default roles for API changes.
    • Disabling auto-reconciliation prevents overwriting of manually updated roles.

    Service Accounts and Permissions

    • Service Accounts represent processes and applications.
    • They often inherit from a default service account in the kube-system namespace.
    • Best practice for controlling access to applications/controllers.
    • Fine-grained control is possible, but increased administration is required for multiple service accounts and roles.

    Transitioning to RBAC

    • Clusters using ABAC (Attribute-Based Access Control) can be transitioned.
    • Running both RBAC and ABAC, then removing ABAC when RBAC works correctly is one method.

    Important Notes

    • Permissions are purely additive and there are no deny rules
    • Permissions can be written to the core level in HTTP.
    • Resources, and other components, must reference the exact name that appears on the relevant API endpoint URL.

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    Description

    This quiz covers Role-Based Access Control (RBAC) in Kubernetes, focusing on its components such as Roles, ClusterRoles, RoleBindings, and ClusterRoleBindings. Learn how these elements manage access to resources based on user roles and understand the API configurations necessary for RBAC implementation.

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