Like most OpenStack projects, Identity supports the protection of its
APIs by defining policy rules based on an RBAC approach. Identity stores
a reference to a policy JSON file in the main Identity configuration
/etc/keystone/keystone.conf. Typically this file is named
policy.json, and contains the rules for which roles have access to
certain actions in defined services.
Each Identity API v3 call has a line in the policy file that dictates which level of governance of access applies.
API_NAME: RULE_STATEMENT or MATCH_STATEMENT
RULE_STATEMENT can contain
MATCH_STATEMENT is a set of identifiers that must match between the
token provided by the caller of the API and the parameters or target
entities of the API call in question. For example:
"identity:create_user": "role:admin and domain_id:%(user.domain_id)s"
Indicates that to create a user, you must have the admin role in your
domain_id in your token must match the
domain_id in the user object that you are trying
to create, which implies this must be a domain-scoped token.
In other words, you must have the admin role on the domain
in which you are creating the user, and the token that you use
must be scoped to that domain.
Each component of a match statement uses this format:
ATTRIB_FROM_TOKEN:CONSTANT or ATTRIB_RELATED_TO_API_CALL
The Identity service expects these attributes:
Attributes from token:
project_id attribute requirement depends on the scope, and the
list of roles you have within that scope.
Attributes related to API call:
You reference attributes of objects passed with an object.attribute
syntax (such as,
user.domain_id). The target objects of an API are
also available using a target.object.attribute syntax. For instance:
"identity:delete_user": "role:admin and domain_id:%(target.user.domain_id)s"
would ensure that Identity only deletes the user object in the same domain as the provided token.
Every target object has an
id and a
name available as
target.OBJECT.name. Identity retrieves
other attributes from the database, and the attributes vary between
object types. The Identity service filters out some database fields,
such as user passwords.
List of object attributes:
role: target.role.id target.role.name user: target.user.default_project_id target.user.description target.user.domain_id target.user.enabled target.user.id target.user.name group: target.group.description target.group.domain_id target.group.id target.group.name domain: target.domain.enabled target.domain.id target.domain.name project: target.project.description target.project.domain_id target.project.enabled target.project.id target.project.name
policy.json file supplied provides a somewhat
basic example of API protection, and does not assume any particular
use of domains. Refer to
policy.v3cloudsample.json as an
example of multi-domain configuration installations where a cloud
provider wants to delegate administration of the contents of a domain
to a particular
admin domain. This example policy file also
shows the use of an
admin_domain to allow a cloud provider to
enable administrators to have wider access across the APIs.
A clean installation could start with the standard policy file, to
allow creation of the
admin_domain with the first users within
it. You could then obtain the
domain_id of the admin domain,
paste the ID into a modified version of
policy.v3cloudsample.json, and then enable it as the main