Active Directory / LDAP Access Management

MinIO supports configuring a single Active Directory or LDAP (AD/LDAP) service for external management of user identities. Enabling AD/LDAP external identity management disables the MinIO internal IDP.

For identities managed by the external AD/LDAP provider, SILO looks up the existing policies explicitly attached to the user’s Distinguished Name (DN). Policy names do not need to match the DN.

If the AD/LDAP configuration includes the necessary settings to query the user’s AD/LDAP group membership, SILO also includes policies attached to the returned group DNs.

MinIO by default denies access to all actions or resources not explicitly allowed by a user’s assigned or inherited policies. An administrator attaches existing SILO policies to LDAP users or groups with mcli idp ldap policy attach. If no policies match either the user DN or group DNs, MinIO blocks all access to actions and resources on the deployment.

The specific AD/LDAP queries MinIO issues to authenticate the user and retrieve its group membership are configured as part of deploying the cluster with Active Directory / LDAP identity management. This page covers creation of SILO policies and their explicit association with returned Distinguished Names.

Authentication and Authorization Flow

The login flow for an application using Active Directory / LDAP credentials is as follows:

1. Specify the AD/LDAP credentials to the MinIO Security Token Service (STS) AssumeRoleWithLDAPIdentity API endpoint.

2. MinIO verifies the provided credentials against the AD/LDAP server.

3. SILO loads the policies explicitly attached to the user DN.

   If configured to perform group queries, MinIO also queries for a list of AD/LDAP groups in which the user has membership. SILO includes policies explicitly attached to each returned group DN.

4. MinIO returns temporary credentials in the STS API response in the form of an access key, secret key, and session token. The credentials have permissions matching those policies attached to either the authenticated user DN or a group DN.

MinIO provides an example Go application ldap.go that handles the full login flow.

AD/LDAP users can alternatively create access keys associated to their AD/LDAP user Distinguished Name. Access Keys are long-lived credentials which inherit their privileges from the parent user. The parent user can further restrict those privileges while creating the access keys. Use either of the following methods to create a new access key:

Use the mc admin user svcacct add command to create the access keys. Specify the user Distinguished Name as the username to which to associate the access keys.

Mapping Policies to User DN

The following commands use mc idp ldap policy attach to associate an existing MinIO policy to an AD/LDAP User DN.

mc idp ldap policy attach myminio consoleAdmin \
  --user='cn=sisko,cn=users,dc=example,dc=com'

mc idp ldap policy attach myminio readwrite diagnostics \
  --user='cn=dax,cn=users,dc=example,dc=com'

• MinIO would assign an authenticated user with DN matching cn=sisko,cn=users,dc=example,dc=com the consoleAdmin policy, granting complete access to the MinIO server.
• MinIO would assign an authenticated user with DN matching cn=dax,cn=users,dc=example,dc=com both the readwrite and diagnostics policies, granting general read/write access to the MinIO server and access to diagnostic administrative operations.
• MinIO would assign no policies to an authenticated user with DN matching cn=quark,cn=users,dc=example,dc=com and deny all access to API operations.

Mapping Policies to Group DN

The following commands use mc idp ldap policy attach to associate an existing MinIO policy to an AD/LDAP Group DN.

mc idp ldap policy attach myminio consoleAdmin \
  --group='cn=ops,cn=groups,dc=example,dc=com'

mc idp ldap policy attach myminio diagnostics \
  --group='cn=engineering,cn=groups,dc=example,dc=com'

• MinIO would assign any authenticating user with membership in the cn=ops,cn=groups,dc=example,dc=com AD/LDAP group the consoleAdmin policy, granting complete access to the MinIO server.
• MinIO would assign any authenticating user with membership in the cn=engineering,cn=groups,dc=example,dc=com AD/LDAP group the diagnostics policy, granting access to diagnostic administrative operations.

Long Distinguished Names

The Server 20261026 includes the LDAP long-DN fix (absent from Server 20261018). When a user relies on group policies and has a normalized DN whose pure-ASCII filename component exceeds 255 bytes on the object IAM backend, the server treats the resulting filename-length error as an absent user-policy mapping and proceeds to evaluate group policies; full-path length limits (PATH_MAX), unreadable revocation records, and storage failures still fail closed, and writing overlong path records remains unsupported on the object backend.