# External authorization control

> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/4216) in
> [GitLab Premium](https://about.gitlab.com/pricing) 10.6.
> [Moved](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/27056) to
> [GitLab Core](https://about.gitlab.com/pricing/) in 11.10.

In highly controlled environments, it may be necessary for access policy to be
controlled by an external service that permits access based on project
classification and user access. GitLab provides a way to check project
authorization with your own defined service.

## Overview

Once the external service is configured and enabled, when a project is accessed,
a request is made to the external service with the user information and project
classification label assigned to the project. When the service replies with a
known response, the result is cached for 6 hours.

If the external authorization is enabled, GitLab will further block pages and
functionality that render cross-project data. That includes:

- most pages under Dashboard (Activity, Milestones, Snippets, Assigned merge
  requests, Assigned issues, Todos)
- under a specific group (Activity, Contribution analytics, Issues, Issue boards,
  Labels, Milestones, Merge requests)
- Global and Group search will be disabled

This is to prevent performing to many requests at once to the external
authorization service.

Whenever access is granted or denied this is logged in a logfile called
`external-policy-access-control.log`.
Read more about logs GitLab keeps in the [omnibus documentation][omnibus-log-docs].

## Configuration

The external authorization service can be enabled by an admin on the GitLab's
admin area under the settings page:

![Enable external authorization service](img/external_authorization_service_settings.png)

The available required properties are:

- **Service URL**: The URL to make authorization requests to. When leaving the
  URL blank, cross project features will remain available while still being able
  to specify classification labels for projects.
- **External authorization request timeout**: The timeout after which an
  authorization request is aborted. When a request times out, access is denied
  to the user.
- **Client authentication certificate**: The certificate to use to authenticate
  with the external authorization service.
- **Client authentication key**: Private key for the certificate when
  authentication is required for the external authorization service, this is
  encrypted when stored.
- **Client authentication key password**: Passphrase to use for the private key when authenticating with the external service this is encrypted when stored.
- **Default classification label**: The classification label to use when
  requesting authorization if no specific label is defined on the project

When using TLS Authentication with a self signed certificate, the CA certificate
needs to be trused by the openssl installation. When using GitLab installed using
Omnibus, learn to install a custom CA in the
[omnibus documentation][omnibus-ssl-docs]. Alternatively learn where to install
custom certificates using `openssl version -d`.

## How it works

When GitLab requests access, it will send a JSON POST request to the external
service with this body:

```json
{
  "user_identifier": "jane@acme.org",
  "project_classification_label": "project-label",
  "user_ldap_dn": "CN=Jane Doe,CN=admin,DC=acme"
}
```

The `user_ldap_dn` is optional and is only sent when the user is logged in
through LDAP.

When the external authorization service responds with a status code 200, the
user is granted access. When the external service responds with a status code
401 or 403, the user is denied access. In any case, the request is cached for 6 hours.

When denying access, a `reason` can be optionally specified in the JSON body:

```json
{
  "reason": "You are not allowed access to this project."
}
```

Any other status code than 200, 401 or 403 will also deny access to the user, but the
response will not be cached.

If the service times out (after 500ms), a message "External Policy Server did
not respond" will be displayed.

## Classification labels

You can use your own classification label in the project's
**Settings > General > General project settings** page in the "Classification
label" box. When no classification label is specified on a project, the default
label defined in the [global settings](#configuration) will be used.

The label will be shown on all project pages in the upper right corner.

![classification label on project page](img/classification_label_on_project_page.png)

[omnibus-ssl-docs]: https://docs.gitlab.com/omnibus/settings/ssl.html
[omnibus-log-docs]: https://docs.gitlab.com/omnibus/settings/logs.html
