======================
Shibboleth Integration
======================

Introduction
------------

The ownCloud Shibboleth user backend application integrates ownCloud with a
Shibboleth Service Provider (SP) and allows operations in federated and
single-sign-on (SSO) infrastructures. Setting up Shibboleth has two big steps:

1. Enable and configure the Apache Shibboleth module.
2. Enable and configure the ownCloud Shibboleth app.

The Apache Shibboleth module
----------------------------

Currently supported installations are based on the `native Apache integration`_.
The individual configuration of the service provider is highly dependent on
the operating system, 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 ownCloud
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 ownCloud instance itself is installed in ``/var/www/owncloud/``.  The
following aliases are defined in an Apache virtual host directive:

::

Further Shibboleth specific configuration as defined in
``/etc/apache2/conf.d/shib.conf``::

	# Load the Shibboleth module.
	LoadModule mod_shib /usr/lib64/shibboleth/mod_shib_24.so

	# Ensure handler will be accessible
	<Location /Shibboleth.sso>
		AuthType None
		Require all granted
	</Location>

	# always fill env with shib variable for logout url
	<Location />
		AuthType shibboleth
		ShibRequestSetting requireSession false
		Require shibboleth
	</Location>

	# authenticate only on the login page
	<Location ~ "^(/index.php)?/login">
		# force internal users to use the IdP
		<If "-R '192.168.1.0/24'">
			AuthType shibboleth
			ShibRequestSetting requireSession true
			require valid-user
		</If>
		# allow basic auth for eg. guest accounts
		<Else>
			AuthType shibboleth
			ShibRequestSetting requireSession false
			require shibboleth
		</Else>
	</Location>

	# shib session for css, js and woff not needed
	<Location ~ "/.*\.(css|js|woff)">
		AuthType None
		Require all granted
	</Location>


To allow users to login via the IdP, add a login alternative with the ``login.alternatives``
option in config.php.

Depending on the ownCloud Shibboleth app mode, you may need to revisit this
configuration.

The ownCloud 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 ownCloud user
attributes on your Admin page.

.. figure:: ../../images/shib-gui5.png
   :alt: Shibboleth configuration screen.

   *figure 1: Enabling Shibboleth on the ownCloud 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 ``occ`` command, like this example on Ubuntu Linux::

 $ sudo -u www-data php occ shibboleth:mode notactive
 $ sudo -u www-data php occ shibboleth:mapping --uid login

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``.

 .. note:: As an example the IdP can send the **userPrincipalName** which the
    Apache Shibboleth module writes to a custom Apache environment variable
    called ``login``. The ownCloud 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
    :doc:`LDAP directory settings on the advanced tab <../../configuration/user/user_auth_ldap>`.
    We recommend using a scoped login attribute like **userPrincipalName** or
    **mail** because otherwise the search might find multiple users and prevent login.

 .. note:: 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 ownCloud 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:: ../../images/shib-gui6.png
   :alt: Dropdowns for mapping Shibboleth environment configuration variables to ownCloud user attributes.

   *figure 2: Mapping Shibboleth environment configuration variables to ownCloud 
   user attributes*

In ownCloud 8.1 the Shibboleth environment variable mapping was stored in
``apps/user_shibboleth/config.php``. This file was overwritten on upgrades,
preventing a seamless upgrade procedure. In ownCloud 8.2+ the variables are
stored in the ownCloud database, making Shibboleth automatically upgradeable.

Mapping ownCloud User IDs
^^^^^^^^^^^^^^^^^^^^^^^^^

From 3.1.2 you can now specify a mapper that is used on inbound ownCloud user IDs,
to adjust them before usage in ownCloud. You can set the mapper using ``occ``::

 $ sudo -u www-data php occ config:app:set user_shibboleth uid_mapper --value="OCA\User_Shibboleth\Mapper\ADFSMapper"

You may view the currently configured mapper using:

 $ sudo -u www-data php occ shibboleth:mapping

The following mappers are provided with the app:

* 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 ownCloud Desktop Client can interact with an
ownCloud instance running inside a Shibboleth Service Provider by using 
OAuth2 tokens to authenticate.

The ownCloud Android and iOS mobile apps also work with OAuth2 tokens.

WebDAV Support
--------------

Users of standard WebDAV clients can generated an App Password on the
Personal settings page. Use of App Passwords may be enforced with the
``token_auth_enforced``option in config.php


Known Limitations
-----------------

Encryption
^^^^^^^^^^

File encryption can only be used together with Shibboleth when the 
:ref:`master key-based encryption <occ_encryption_label>` 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 ownCloud native) by creating
a second Apache virtual host configuration. This second location is not
protected by Shibboleth, and you can use your other ownCloud login mechanisms.

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 compatability
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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
:doc:`LDAP directory settings on the advanced tab <../../configuration/user/user_auth_ldap>`.
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``.

.. _the official Shibboleth wiki:
    https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPLinuxInstall
.. _native Apache integration:
    https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPApacheConfig
    
.. Github references
.. update shibboleth doc, restructure some sections, add occ commands 
.. https://github.com/owncloud/documentation/pull/2116/
.. Shibboleth configuration in 8.2.1
.. https://github.com/owncloud/enterprise/issues/981
