a0456ce940
Add LDAP based users-groups system This change adds support to integrate an LDAP server for user authentication. This works via a custom STS API for LDAP. Each user accessing the MinIO who can be authenticated via LDAP receives temporary credentials to access the MinIO server. LDAP is enabled only over TLS. User groups are also supported via LDAP. The administrator may configure an LDAP search query to find the group attribute of a user - this may correspond to any attribute in the LDAP tree (that the user has access to view). One or more groups may be returned by such a query. A group is mapped to an IAM policy in the usual way, and the server enforces a policy corresponding to all the groups and the user's own mapped policy. When LDAP is configured, the internal MinIO users system is disabled.
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MinIO LDAP Integration
MinIO provides a custom STS API that allows integration with LDAP based corporate environments. The flow is as follows:
- User provides their LDAP username and password to the STS API.
- MinIO logs-in to the LDAP server as the user - if the login succeeds the user is authenticated.
- MinIO then queries the LDAP server for a list of groups that the
user is a member of.
- This is done via a customizable LDAP search query.
- MinIO then generates temporary credentials for the user storing the list of groups in a cryptographically secure session token. The temporary access key, secret key and session token are returned to the user.
- The user can now use these credentials to make requests to the MinIO server.
The administrator will associate IAM access policies with each group and if required with the user too. The MinIO server then evaluates applicable policies on a user (these are the policies associated with the groups along with the policy on the user if any) to check if the request should be allowed or denied.
Configuring LDAP on MinIO
LDAP configuration is designed to be simple for the MinIO administrator.
The full path of a user DN (Distinguished Name)
(e.g. uid=johnwick,cn=users,cn=accounts,dc=minio,dc=io) is
configured as a format string in the
MINIO_IDENTITY_LDAP_USERNAME_FORMAT environment variable. This
allows an LDAP user to not specify this whole string in the LDAP STS
API. Instead the user only needs to specify the username portion
(i.e. johnwick in this example) that will be substituted into the
format string configured on the server.
MinIO can be configured to find the groups of a user from LDAP by specifying the MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER and MINIO_IDENTITY_LDAP_GROUP_NAME_ATTRIBUTE environment variables. When a user logs in via the STS API, the MinIO server queries the LDAP server with the given search filter and extracts the given attribute from the search results. These values represent the groups that the user is a member of. On each access MinIO applies the IAM policies attached to these groups in MinIO.
LDAP is configured via the following environment variables:
| Variable | Required? | Purpose |
|---|---|---|
| MINIO_IDENTITY_LDAP_SERVER_ADDR | YES | LDAP server address |
| MINIO_IDENTITY_LDAP_USERNAME_FORMAT | YES | Format of full username DN |
| MINIO_IDENTITY_LDAP_GROUP_SEARCH_BASE_DN | NO | Base DN in LDAP hierarchy to use in search requests |
| MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER | NO | Search filter to find groups of a user |
| MINIO_IDENTITY_LDAP_GROUP_NAME_ATTRIBUTE | NO | Attribute of search results to use as group name |
| MINIO_IDENTITY_LDAP_STS_EXPIRY_DURATION | NO (default: "1h") | STS credentials validity duration |
| MINIO_IDENTITY_LDAP_TLS_SKIP_VERIFY | NO (default: "false") | Disable TLS certificate verification |
Please note that MinIO will only access the LDAP server over TLS.
An example setup for development or experimentation:
export MINIO_IDENTITY_LDAP_SERVER_ADDR=myldapserver.com:636
export MINIO_IDENTITY_LDAP_USERNAME_FORMAT="uid=${username},cn=accounts,dc=myldapserver,dc=com"
export MINIO_IDENTITY_LDAP_GROUP_SEARCH_BASE_DN="dc=myldapserver,dc=com"
export MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER="(&(objectclass=groupOfNames)(member=${usernamedn}))"
export MINIO_IDENTITY_LDAP_GROUP_NAME_ATTRIBUTE="cn"
export MINIO_IDENTITY_LDAP_STS_EXPIRY_DURATION=60
export MINIO_IDENTITY_LDAP_TLS_SKIP_VERIFY=true
Variable substitution in LDAP configuration strings
In the configuration values described above, some values support
runtime substitutions. The substitution syntax is simply
${variable} - this substring is replaced with the (string) value of
variable. The following substitutions will be available:
| Variable | Example Runtime Value | Description |
|---|---|---|
| username | "james" | The LDAP username of a user. |
| usernamedn | "uid=james,cn=accounts,dc=myldapserver,dc=com" | The LDAP username DN of a user. This is constructed from the LDAP user DN format string provided to the server and the actual LDAP username. |
The MINIO_IDENTITY_LDAP_USERNAME_FORMAT environment variable supports substitution of the username variable only.
The MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER and MINIO_IDENTITY_LDAP_GROUP_SEARCH_BASE_DN environment variables support substitution of the username and usernamedn variables only.