Chapter 10. Scoping tokens
10.1. About scoping tokens
You can create scoped tokens to delegate some of your permissions to another user or service account. For example, a project administrator might want to delegate the power to create pods.
A scoped token is a token that identifies as a given user but is limited to certain actions by its scope. Only a user with the dedicated-admin role can create scoped tokens.
Scopes are evaluated by converting the set of scopes for a token into a set of PolicyRules. Then, the request is matched against those rules. The request attributes must match at least one of the scope rules to be passed to the "normal" authorizer for further authorization checks.
10.1.1. User scopes
User scopes are focused on getting information about a given user. They are intent-based, so the rules are automatically created for you:
-
user:full- Allows full read/write access to the API with all of the user’s permissions. -
user:info- Allows read-only access to information about the user, such as name and groups. -
user:check-access- Allows access toself-localsubjectaccessreviewsandself-subjectaccessreviews. These are the variables where you pass an empty user and groups in your request object. -
user:list-projects- Allows read-only access to list the projects the user has access to.
10.1.2. Role scope
The role scope allows you to have the same level of access as a given role filtered by namespace.
role:<cluster-role name>:<namespace or * for all>- Limits the scope to the rules specified by the cluster-role, but only in the specified namespace .NoteCaveat: This prevents escalating access. Even if the role allows access to resources like secrets, rolebindings, and roles, this scope will deny access to those resources. This helps prevent unexpected escalations. Many people do not think of a role like
editas being an escalating role, but with access to a secret it is.-
role:<cluster-role name>:<namespace or * for all>:!- This is similar to the example above, except that including the bang causes this scope to allow escalating access.
10.2. Adding unauthenticated groups to cluster roles
As a cluster administrator, you can add unauthenticated users to the following cluster roles in OpenShift Dedicated by creating a cluster role binding. Unauthenticated users do not have access to non-public cluster roles. This should only be done in specific use cases when necessary.
You can add unauthenticated users to the following cluster roles:
-
system:scope-impersonation -
system:webhook -
system:oauth-token-deleter -
self-access-reviewer
Always verify compliance with your organization’s security standards when modifying unauthenticated access.
Prerequisites
-
You have access to the cluster as a user with the
cluster-adminrole. -
You have installed the OpenShift CLI (
oc).
Procedure
Create a YAML file named
add-<cluster_role>-unauth.yamland add the following content:apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: annotations: rbac.authorization.kubernetes.io/autoupdate: "true" name: <cluster_role>access-unauthenticated roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: <cluster_role> subjects: - apiGroup: rbac.authorization.k8s.io kind: Group name: system:unauthenticated
Apply the configuration by running the following command:
$ oc apply -f add-<cluster_role>.yaml
