Authorization

When interacting with Incus over the Unix socket, members of the incus-admin group will have full access to the Incus API. Those who are only members of the incus group will instead be restricted to a single project tied to their user.

When interacting with Incus over the network (see How to expose Incus to the network for instructions), it is possible to further authenticate and restrict user access. There are three supported authorization methods:

• TLS authorization

• Open Fine-Grained Authorization (OpenFGA)

• Scriptlet authorization

By default, the method used for a request is determined automatically from the client’s authentication protocol. This can be customized so that different kinds of clients are handled by different methods; see Client routing.

TLS authorization

Incus natively supports restricting Trusted TLS clients to one or more projects. When a client certificate is restricted, the client will also be prevented from performing global configuration changes or altering the configuration (limits, restrictions) of the projects it’s allowed access to.

To restrict access, use incus config trust edit <fingerprint>. Set the restricted key to true and specify a list of projects to restrict the client to. If the list of projects is empty, the client will not be allowed access to any of them.

By default, this authorization method is used for clients authenticating with a restricted TLS certificate. Clients using an unrestricted certificate are granted full access instead. Both can be changed, see Client routing.

Open Fine-Grained Authorization (OpenFGA)

Incus supports integrating with OpenFGA. This authorization method is highly granular. For example, it can be used to restrict user access to a single instance.

To use OpenFGA for authorization, you must configure and run an OpenFGA server yourself. Incus will connect to the OpenFGA server, write the OpenFGA model, and query this server for authorization for all subsequent requests.

To enable this authorization method in Incus, set the authorization.openfga.* server configuration options. All options must be set in order to enable OpenFGA. Though, you do not have to create the authorization-model yourself, Incus will generate it including the initial tuple to allow only authenticated users: server:incus#authenticated@user:*.

Warning

Setting the authorization.openfga.* options only makes OpenFGA available. It does not on its own cause any request to be authorized by it.

OpenFGA is only consulted for clients whose class is routed to it with an authorization.client.* option, see Client routing.

OpenFGA model

With OpenFGA, access to a particular API resource is determined by the user’s relationship to it. These relationships are determined by an OpenFGA authorization model. The Incus OpenFGA authorization model describes API resources in terms of their relationship to other resources, and a relationship a user or group might have with that resource.

The full Incus OpenFGA authorization model is defined in internal/server/auth/driver_openfga_model.openfga:

model
  schema 1.1
type user

type group
  relations
    define member: [user]

type certificate
  relations
    define server: [server]
    define can_edit: [user, group#member] or admin from server
    define can_view: viewer from server

type image
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type image_alias
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type instance
  relations
    define project: [project]
    define admin: [user, group#member] or admin from project
    define operator: [user, group#member] or admin or operator from project
    define user: [user, group#member] or operator or user from project
    define viewer: [user, group#member] or user or viewer from project
    define can_access_console: [user, group#member] or user
    define can_access_files: [user, group#member] or user
    define can_connect_nbd: [user, group#member] or user
    define can_connect_sftp: [user, group#member] or user
    define can_connect_tcp: [user, group#member] or user
    define can_edit: operator
    define can_exec: [user, group#member] or user
    define can_manage_backups: [user, group#member] or operator
    define can_manage_snapshots: [user, group#member] or operator
    define can_update_state: [user, group#member] or operator
    define can_view: viewer

type network
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type network_acl
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type network_address_set
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type network_integration
  relations
    define server: [server]
    define can_edit: [user, group#member] or admin from server
    define can_view: viewer from server

type network_zone
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type profile
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type project
  relations
    define server: [server]
    define admin: [user, group#member] or admin from server
    define operator: [user, group#member] or admin or operator from server
    define user: [user, group#member] or operator or user from server
    define viewer: [user, group#member] or user or viewer from server
    define can_create_image_aliases: [user, group#member] or operator
    define can_create_images: [user, group#member] or operator
    define can_create_instances: [user, group#member] or operator
    define can_create_network_acls: [user, group#member] or operator
    define can_create_network_address_sets: [user, group#member] or operator
    define can_create_networks: [user, group#member] or operator
    define can_create_network_zones: [user, group#member] or operator
    define can_create_profiles: [user, group#member] or operator
    define can_create_storage_buckets: [user, group#member] or operator
    define can_create_storage_volumes: [user, group#member] or operator
    define can_edit: admin
    define can_view_events: [user, group#member] or user
    define can_view_operations: [user, group#member] or user
    define can_view: viewer

type server
  relations
    define admin: [user, group#member]
    define operator: [user, group#member] or admin
    define user: [user, group#member] or operator
    define viewer: [user, group#member] or user
    define authenticated: [user:*]
    define can_create_certificates: [user, group#member] or admin
    define can_create_network_integrations: [user, group#member] or admin
    define can_create_projects: [user, group#member] or admin
    define can_create_storage_pools: [user, group#member] or admin
    define can_edit: admin
    define can_override_cluster_target_restriction: [user, group#member] or admin
    define can_view_privileged_events: [user, group#member] or admin
    define can_view_metrics: authenticated
    define can_view_resources: authenticated
    define can_view_sensitive: [user, group#member] or viewer
    define can_view: authenticated

type storage_bucket
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_view: [user, group#member] or can_edit or viewer from project

type storage_pool
  relations
    define server: [server]
    define can_edit: [user, group#member] or admin from server
    define can_view: authenticated from server

type storage_volume
  relations
    define project: [project]
    define can_edit: [user, group#member] or operator from project
    define can_manage_backups: [user, group#member] or can_edit
    define can_manage_snapshots: [user, group#member] or can_edit
    define can_view: [user, group#member] or can_edit or viewer from project
    define can_access_files: [user, group#member] or can_edit
    define can_connect_nbd: [user, group#member] or can_edit
    define can_connect_sftp: [user, group#member] or can_edit

Important

Users that you do not trust with root access to the host should not be granted the following relations:

• server -> admin

• server -> operator

• server -> can_edit

• server -> can_create_storage_pools

• server -> can_create_projects

• server -> can_create_certificates

• certificate -> can_edit

• storage_pool -> can_edit

• project -> admin

The remaining relations may be granted. However, you must apply appropriate Project restrictions.

Scriptlet authorization

Incus supports defining a scriptlet to manage fine-grained authorization, allowing to write precise authorization rules with no dependency on external tools.

Warning

Setting authorization.scriptlet only makes the scriptlet available. It does not on its own cause any request to be authorized by it.

The scriptlet is only run for clients whose class is routed to it with an authorization.client.* option, see Client routing.

To use scriptlet authorization, you can write a scriptlet in the authorization.scriptlet server configuration option implementing a function authorize, which takes three arguments:

• details, an object with the following attributes:

  • Username: the user name or certificate fingerprint

  • Protocol: the authentication protocol

  • IsAllProjectsRequest: whether the request is made on all projects

  • ProjectName: the project name

  • Chain: the certificate chain as a list of dissected x509 certificates

  • Certificate: the certificate data stored in the database

• object, the object on which the user requests authorization

• entitlement, the authorization level asked by the user

This function must return a Boolean indicating whether the user has access or not to the given object with the given entitlement.

Additionally, two optional functions can be defined so that users can be listed through the access API:

• get_instance_access, with two arguments (project_name and instance_name), returning a list of users able to access a given instance

• get_project_access, with one argument (project_name), returning a list of users able to access a given project

Client routing

More than one authorization method can be loaded at the same time, with each request routed to exactly one of them based on the authentication class of the client. This is controlled through the authorization.client.* server configuration options, one per client class:

• authorization.client.unix: local clients connecting over the Unix socket

• authorization.client.tls: clients using an unrestricted client certificate

• authorization.client.tls-restricted: clients using a restricted (project-scoped) client certificate

• authorization.client.oidc: OIDC-authenticated clients

• authorization.client.default: any client class not set above

Each option accepts one of the following values:

• allow: unconditionally grant access

• deny: unconditionally refuse access

• tls: use TLS authorization, only valid for authorization.client.tls-restricted

• openfga: use Open Fine-Grained Authorization (OpenFGA)

• scriptlet: use Scriptlet authorization

A per-class option falls back to authorization.client.default when unset. When that is unset too, the following built-in routing applies:

Client class	Built-in route
unix	allow
tls	allow
tls-restricted	tls
oidc	allow
default	deny

This routing is fixed.

Warning

The per-certificate project restrictions described in TLS authorization are enforced by the TLS authorization method only.

If authorization.client.tls-restricted is set to any value other than tls, the project list of the client certificate are no longer consulted, and a restricted certificate may gain access well beyond the projects it is limited to. Only set this option to something other than tls if the method you route to reproduces the restrictions you rely on.

Warning

Always set authorization.client.default last, once you have confirmed that every explicitly configured client class behaves as expected.

The default applies to every class that is not set explicitly, so a single mistake affects all of them at once. If it is set to openfga or scriptlet while that method is misconfigured or unreachable, or to deny, every remote client is refused.

The root user is always allowed to interact with the API over the Unix socket, regardless of the configured authorization method. This is what allows a server locked out by a bad routing configuration to be recovered.

For example, to have OpenFGA authorize OIDC clients while restricted TLS clients keep using TLS authorization:

incus config set authorization.client.oidc=openfga
incus config set authorization.client.tls-restricted=scriptlet