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MinIO Identity and Access Management

Overview

MinIO provides an internal Identity and Access Management subsystem that supports the creation of user identities, groups, and policies in support of authentication and authorization of client operations.

Authentication is the process of verifying the identity of a connecting client. MinIO requires clients authenticate using AWS Signature Version 4 protocol with support for the deprecated Signature Version 2 protocol. Specifically, clients must present a valid access key and secret key to access any S3 or MinIO administrative API, such as PUT, GET, and DELETE operations. MinIO provides a built-in IDentity Provider (IDP) for creating and managing user identities in support of client authentication.

Authorization is the process of restricting the actions and resources the authenticated client can perform on the deployment. MinIO uses Policy-Based Access Control (PBAC), where each policy describes one or more rules that outline the permissions of a user or group of users. MinIO supports a subset of actions and conditions when creating policies. By default, MinIO denies access to actions or resources not explicitly referenced in a user’s assigned or inherited policies.

Identity Management

MinIO includes a built-in IDentity Provider (IDP) that provides core identity management functionality. The MinIO IDP supports creating an arbitrary number of long-lived users on the deployment for supporting client authentication.

Each user consists of a unique access key (username) and corresponding secret key (password). Clients must authenticate their identity by specifying both a valid access key (username) and the corresponding secret key (password) of an existing MinIO user.

Administrators use the mc admin user command to create and manage MinIO users. The MinIO Console provides a graphical interface for creating users.

MinIO also supports creating service accounts. Service accounts are child identities of an authenticated parent user and inherit their permissions from the parent.

MinIO by default denies access to all actions or resources not explicitly allowed by a user’s assigned or inherited policies. You must either explicitly assign a policy describing the user’s authorized actions and resources or assign the user to groups which have associated policies. See Access Management for more information.

Access Management

MinIO uses Policy-Based Access Control (PBAC) to define the authorized actions and resources to which an authenticated user has access. Each policy describes one or more actions and conditions that outline the permissions of a user or group of users.

MinIO manages the creation and storage of policies. The process for assigning a policy to a user or group depends on the configured IDentity Provider (IDP).

MinIO deployments using the MinIO Internal IDP require explicitly associating a user to a policy or policies using the mc admin policy set command. A user can also inherit the policies attached to the groups in which they have membership.

By default, MinIO denies access to actions or resources not explicitly allowed by an attached or inherited policy. A user with no explicitly assigned or inherited policies cannot perform any S3 or MinIO administrative API operations.

For MinIO deployments using an External IDP, policy assignment depends on the choice of IDP:

OpenID Connect (OIDC)

MinIO checks for a JSON Web Token (JWT) claim (policy by default) containing the name of the policy or policies to attach to the authenticated user. If the policies do not exist, the user cannot perform any action on the MinIO deployment.

MinIO does not support assigning OIDC user identities to groups. The IDP administrator must instead assign all necessary policies to the user’s policy claim.

See Access Control for Externally Managed Identities for more information.

Active Directory / LDAP (AD/LDAP)

MinIO checks for a policy whose name matches the Distinguished Name (DN) of the authenticated AD/LDAP user.

MinIO also supports querying for the authenticated AD/LDAP user’s group memberships. MinIO assigns any policy whose name matches the DN for each returned group.

If no policies match either the user DN or any of the user’s group DNs, the user cannot perform any action on the MinIO deployment.

See Access Control for Externally Managed Identities for more information.

MinIO PBAC is built for compatibility with AWS IAM policy syntax, structure, and behavior. The MinIO documentation makes a best-effort to cover IAM-specific behavior and functionality. Consider deferring to the IAM documentation for more complete documentation on IAM, IAM policies, or IAM JSON syntax.

Deny overrides Allow

MinIO follows AWS IAM policy evaluation rules where a Deny rule overrides Allow rule on the same action/resource. For example, if a user has an explicitly assigned policy with an Allow rule for an action/resource while one of its groups has an assigned policy with a Deny rule for that action/resource, MinIO would apply only the Deny rule.

For more information on IAM policy evaluation logic, see the IAM documentation on Determining Whether a Request is Allowed or Denied Within an Account.