Shibboleth Integration

Introduction

The Myota Vault Shibboleth user backend application integrates Myota Vault with a Shibboleth Service Provider (SP) and allows operations in federated and single-sign-on (SSO) infrastructures.

The Docker image does not provide the necessary modules for the embedded Apache web server. A customised image must be built for Shibboleth authentication.

Setting up Shibboleth has two big steps:

  1. Enable and configure the Apache Shibboleth module.

  2. Enable and configure the Myota Vault Shibboleth app.

The Apache Shibboleth Module

Currently supported installations are based on the native Apache integration. The individual configuration of the service provider is dependent on the operating system used for the image (Ubuntu), as well as on the integration with the Identity Providers (IdP), and require case-by-case analysis and installation.

A good starting point for the service provider installation can be found in the official Shibboleth Wiki.

A successful installation and configuration will populate Apache environment variables with at least a unique user id which is then used by the Myota Vault Shibboleth app to login a user.

Apache Configuration

This is an example configuration as installed and operated on a Linux server running the Apache 2.4 Web server. These configurations are highly operating system specific and require a high degree of customization.

The Myota Vault instance itself is installed in /var/www/myota/. Further Shibboleth specific configuration as defined in /etc/apache2/conf.d/shib.conf.

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To allow users to login via the IdP, add a login alternative with the login.alternatives option in config/config.php. Depending on the Myota Vault Shibboleth app mode, you may need to revisit this configuration.

The Myota Vault Shibboleth App

After enabling the Shibboleth app on your Apps page, you need to choose the app mode and map the necessary Shibboleth environment variables to Myota Vault user attributes on your Admin page.

figure 1: Enabling Shibboleth on the Myota Vault Admin page

Choosing the App Mode

After enabling the app it will be in Not active mode, which ignores a Shibboleth session and allows you to login as an administrator and inspect the currently available Apache environment variables. Use this mode to set up the environment mapping for the other modes, and in case you locked yourself out of the system. You can also change the app mode and environment mappings by using the admin console setting, like this example on Ubuntu Linux:

In *Single sign-on only* mode the app checks if the environment variable for the Shibboleth session, by default *Shib-Session-Id*, is set. If that is the case it will take the value of the environment variable as the `uid`, by default `eppn`, and check if a user is known by that `uid`. In effect, this allows another user backend, e.g., the LDAP app, to provide the `displayname`, `email` and `avatar`.

As an example the IdP can send the userPrincipalName which the Apache Shibboleth module writes to a custom Apache environment variable called login. The Myota Vault Shibboleth app reads that login environment variable and tries to find an LDAP user with that username. For this to work userPrincipalName needs to be added to the Additional Search Attributes in the LDAP directory settings on the advanced tab. We recommend using a scoped login attribute like userPrincipalName or mail because otherwise the search might find multiple users and prevent login.

In many scenarios Shibboleth is not intended to hide the user’s password from the service provider, but only to implement SSO. If that is the case it is sufficient to protect the Myota Vault base URL with Shibboleth. This will send Web users to the IdP but allow desktop and mobile clients to continue using username and password, preventing popups due to an expired Shibboleth session lifetime.

In Autoprovision Users mode the app will not ask another user backend, but instead provision users on the fly by reading the two additional environment variables for display name and email address.

Figure 2: Mapping Shibboleth environment configuration variables to Myota Vault user attributes

Mapping Myota Vault User IDs

You can specify a mapper that is used on inbound Myota Vault user IDs, to adjust them before usage in Myota Vault. You can set the mapper using the admin console:

You may view the currently configured mapper using:
The following mappers are provided with the app:
Class Description

OCA\User_Shibboleth\Mapper\NoOpMapper

The default, does not alter the UID

OCA\User_Shibboleth\Mapper\ADFSMapper

Splits the UID around a ; character and takes the first piece

OCA\User_Shibboleth\Mapper\GUIDInMemoryMapper

Maps in binary GUIDs to strings

Shibboleth with Desktop and Mobile Clients

The Myota Vault Desktop Client can interact with an Myota Vault instance running inside a Shibboleth Service Provider by using OAuth2 tokens to authenticate. The Myota Vault Android and iOS mobile apps also work with OAuth2 tokens.

WebDAV Support

Users of standard WebDAV clients can generate an App Password on the Personal settings page. Use of App Passwords may be enforced with the MYOTA_TOKEN_AUTH_ENFORCED environment variable.

Known Limitations

Encryption

File encryption can only be used together with Shibboleth when master key-based encryption is used because the per-user encryption requires the user’s password to unlock the private encryption key. Due to the nature of Shibboleth the user’s password is not known to the service provider.

Other Login Mechanisms

You can allow other login mechanisms (e.g., LDAP or Myota Vault native) by creating a second Apache virtual host configuration; such as in the below example.

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  • The second location in the above configuration is not protected by Shibboleth, and you can use your other Myota Vault login mechanisms.

  • The above configuration can be used with multi-factor authentication as well.

If you use the above configuration, after it’s enabled, configure the alternative logins option with a button to point to /login-shib. This will trigger the Shibboleth session and redirect the user back to /login. At this point, the existing session will be picked up, continuing with the authentication process.

Session Timeout

Session timeout on Shibboleth is controlled by the IdP. It is not possible to have a session length longer than the length controlled by the IdP. In extreme cases this could result in re-login on mobile clients and desktop clients every hour.

UID Considerations and Windows Network Drive Compatibility

To log in LDAP users via SAML for Single Sign On the user in LDAP must be uniquely resolvable by searching for the username that was sent in the SAML token. For this to work the LDAP attribute containing the username needs to be added to the Additional Search Attributes in the LDAP directory settings on the advanced settings tab. We recommend using a scoped login attribute like userPrincipalName or mail because otherwise the search might find multiple users and prevent login.

user_shibboleth will do the authentication, and user_ldap will provide user details such as email and displayname.