Mapping SSO Identities into Anchore

Overview of Mapping External Identities into Anchore

Anchore SSO support provides a way to keep users’ credentials centrally stored in a corporate Identity Provider and outside of the Anchore deployment. Anchore’s SSO approach uses the external identity store to authenticate a user and bootstrap its permissions using Anchore’s RBAC system. For each login, the user’s identity is verified against the external provider but once the identity is initialized inside the Anchore deployment, its access to resources is controlled by the Anchore Enterprise RBAC system. This approach allows Anchore admins to manage user access without having to require administrator access to a corporate or central IT identity system while still being able to leverage that system for defining identity and securing access credentials.

The identity mapping process has two distinct phases:

  1. Initial identity bootstrap - Occurs on the first login of a user to Anchore causing dynamic construction of an Anchore user record.
  2. Identity verification and assertion validation - Validates the administrators requirements against the external identity record on each login.

Defining the Username

By default, with SSO, the SAML Assertion’s “Subject” attribute is used to define the username. Using the subject is the right solution in most situations, but in extreme cases it may be necessary to provide the username in some other form via attributes in the SAML Response. This behavior can be configured by setting: idp_username_attribute in the SAML Configuration within Anchore. This should only be used when the subject either cannot be used due to it being a transient ID as configured by the IDP itself, or you want the username to map to some form other than the IDP’s username, email, or persistent ID.

If the idp_username_attribute is set to an attribute name, and that attribute is not found or has no value in the SAML Response presented during login, then that user login will be rejected by Anchore.

If idp_username_attribute is an empty string or null, then the SAML Response’s subject attribute is used as the username. This is the default behavior.

Defining the Account the User Belongs To

In Anchore, all users belong to an Account. When an SSO user logs into Anchore UI for the first time, the identity is initialized with the username (as defined above), but the account to which the user belongs is configurable via a separate pair of configuration properties in the SAML Configuration within Anchore. These configuration properties are mutually exclusive.

idp_account_attribute - If set in the SAML Configuration, this attribute must be found within the SAML Response during each login for every user. The attribute value received is the ‘account name’. It must also be valid. A valid value must be greater than three characters and must not be a reserved account name such as ‘admin’ or ‘anchore-system’ If the attribute is not found within the SAML Response or the value is not valid, the login is rejected.

default_account - If set in the SAML Configuration, it’s value is the account all users that login from this IDP will be assigned.

  • In both cases, on the initial login by the user, if the account does not already exist within Anchore, an external account with that name is created.

Defining the User’s Initial Roles

In Anchore, all users are allowed to have one or more Roles that describe a set of access permissions.
Roles are assigned to the user via a separate pair of configuration properties in the SAML Configuration within Anchore.
These configuration properties are mutually exclusive.

idp_role_attribute - If set in the SAML Configuration, the attribute must be found within the SAML Response during each login for every user. The attribute value received is one or more ‘role name’. The value must also be valid. If the attribute is not found within the SAML Response or the value is not valid, the login is rejected.

default_role - If set in the SAML Configuration, it’s value will be the single role set for all users that login with this IDP. During a user’s first login, this role will be set on the account during user identity initialization. On subsequent logins for this user, the value will be ignored.

Revoking SSO User Access

  1. Disable the Anchore account. Any user, SSO or otherwise, that is a member of a disabled account cannot log in or perform API operations.
  2. If using idp_account_attribute or idp_role_attribute, simply remove or zero that attribute at the IDP for that user or group. All affected users will no longer be able to log in to Anchore.

Changing the Anchore SAML Configuration

Initialization of identities and roles occurs on the user’s first login. Once initialized, the configuration must match the SAML Response presented during each login for the user to log in.

Thus, changes to the SAML Configuration within Anchore may affect subsequent logins for your users. For instance, if you change the SAML Configuration within Anchore to start using attributes instead of defaults, a user’s SAML Response will need to contain the same attributes. Failure to find the correct attribute(s) with valid values will prevent the user’s login.

Examples

Identity Mapping Example Configurations

Examples of configuration values for a single SAML Configuration within Anchore to achieve different behavior:

  1. All SSO users in one account with the same read-write permissions:

    • default_account = ‘account’
    • default_role = ‘read-write’

  2. SSO users in accounts managed by the IDP property, for example a ‘groups’ property:

    • default_account = null
    • default_role = null
    • idp_account_attribute = "primary_group"
    • idp_role_attribute = "roles"
    • Will initialize the user with the roles specified in the ‘roles’ attribute for the accounts in the ‘primary_group’ attribute.
      • E.g. if ‘primary_group’ = [’testers’], and ‘roles’ = [‘read-only’] for a user, [email protected]
      • [email protected] will be initialized at login as username = [email protected] in account testers with role read-only
      • Because the account is from an attribute, [email protected] might have ‘primary_group’ = [‘security_engineers’] and thus be initialized in a different account in Anchore.
Last modified December 19, 2022