Make it possible to use mod-auth-mellon for logins

doc/howto/index.rst

@@ -15,6 +15,7 @@ Howtos
    email
    migrate-data
    mod_auth_openidc_feide
+   mod_auth_mellon_feide
    setting-up-logging
    using_the_api
    api_parameters

doc/howto/mod_auth_mellon_feide.rst

@@ -0,0 +1,175 @@
+================================================================================================================
+Authenticating with the apache plugin `mod_auth_mellon <https://github.com/latchset/mod_auth_mellon>`_ and Feide
+================================================================================================================
+
+Enabling the plugin on Debian
+=============================
+
+First check if the plugin is already installed and enabled::
+
+    $ sudo apache2ctl -M | grep mellon
+      auth_mellon_module (shared)
+
+If it is, go straight to `Configuration`_.
+
+If not:
+
+Install the plugin::
+
+            $ sudo apt install libapache2-mod-auth-mellon
+
+This should create the following files::
+
+    /etc/apache2/mods-available/auth_mellon.conf
+    /etc/apache2/mods-available/auth_mellon.load
+    /etc/apache2/mods-enabled/auth_mellon.conf
+    /etc/apache2/mods-enabled/auth_mellon.load
+
+Enable with::
+
+    $ sudo a2enmod auth_mellon
+
+Disable with::
+
+    $ sudo a2dismod auth_mellon
+
+Files needed
+============
+
+Make a directory ``/etc/apache2/mellon`` on the NAV host. This will contain the
+keys, certificates and metadata.
+
+You need to download the idp metadata.
+
+* `Test metadata <https://idp-test.feide.no/simplesaml/saml2/idp/metadata.php>`_
+* `Production metadata <https://idp.feide.no/simplesaml/saml2/idp/metadata.php>`_
+
+Save the file as ``/etc/apache2/mellon/idp-metadata.xml``.
+
+The easiest way to create the sp metadata is with the command
+``mellon_create_metadata``. Stand in ``/etc/apache2/mellon`` and run::
+
+    mellon_create_metadata https://DOMAINNAME https://DOMAINNAME/mellon
+
+This will output a summary and create three files: ``https_DOMAINNAME.cert``,
+``https_DOMAINNAME.key`` and ``https_DOMAINNAME.xml``. You can edit the
+xml-file if needed.
+
+Feide Kundeportal configuration
+===============================
+
+You will need to ask somebody with the correct access-rights at `Feide
+kundeportal <https://kunde.feide.no>`_ for your organization to create
+a service and a SAML 2.0 configuration for that service. Configurations are
+locked to a specific NAV domain name and user group and cannot be shared. If
+the domainname is updated the Feide and Apache2-configurations will need to be
+updated as well.
+
+The Feide admin will need:
+
+* A name for the service, we recommend: "NAV: domainname" or "NAV: your organization".
+* An url to redirect to after login, this is the domainname followed by
+  a relative url that is *not served by NAV*. We use ``/mellon`` in this howto.
+* A copy of ``https_DOMAINNAME.xml``, to use in the SP metadata field.
+
+Also, the ``userid-feide`` scope needs to be turned on at
+*User information > Personal information*.
+
+Apache2 Configuration
+=====================
+
+Apache virtual host configuration::
+
+    <Location />
+        .
+        .
+
+        AuthType mellon
+        Require valid-user
+
+        MellonEnable "auth"
+        MellonSecureCookie On
+        MellonUser "eduPersonPrincipalName"
+        #MellonSessionIdleTimeout 28800  # auto logout after 8 hours
+        MellonSPMetadataFile /etc/apache2/mellon/https_DOMAINNAME.xml
+        MellonSPPrivateKeyFile /etc/apache2/mellon/https_DOMAINNAME.key
+        MellonSPCertFile /etc/apache2/mellon/https_DOMAINNAME.cert
+        MellonIdPMetadataFile /etc/apache2/mellon/idp-metadata.xml
+    </Location>
+
+    <Location /mellon>
+        SetHandler none
+        AuthType mellon
+        Require valid-user
+
+    </Location>
+
+    <Location /index/logout>
+        AuthType None
+        Require all granted
+    </Location>
+
+    <Location /about>
+        AuthType None
+        Require all granted
+    </Location>
+
+    <Location /refresh_session>
+        AuthType None
+        Require all granted
+    </Location>
+
+    <Location /api>
+        AuthType None
+        Require all granted
+    </Location>
+
+    <Location /doc>
+        AuthType None
+        Require all granted
+    </Location>
+
+Note the location block ``<Location />``. The "Require"-line replaces any other
+"requires" already there. This locks down the entire site. We haven't found
+a way with this plugin to do it any other way.
+
+The second location block (``<Location /mellon>``) just needs to be a relative
+url that is not in use by anything else, this is used by the plugin as its
+endpoint.
+
+The third location block (``<Location /index/logout>``) is the url that must be
+visited before the plugin redirects to the IDP for logout.
+
+The remaining location blocks are either public urls (``/doc``, ``/about``),
+parts of NAV that has its own authentication system (``/api``), or must not be
+under the control of the plugin for the web frontend to correctly function
+(``/refresh_session``). If you have added extra pages or apps to the nav-server
+that will not use the NAV auth system you need to mark their urls similarly.
+
+Note that ``MellonSessionIdleTimeout`` has been commented out. Not all versions
+of mod-auth-mellon support this configuration flag.
+
+NAV configuration
+=================
+
+``webfront.conf``::
+
+    [remote-user]
+    enabled = yes
+    varname = REMOTE_USER
+    post-logout-redirect-url = /mellon/logout?returnTo=/
+
+"mellon" in the ``post-logout-redirect-url`` points to the same place as the
+``<Location /mellon>``-block in the apache configuration. This is hardcoded in
+the SP metadata as well.
+
+Gotchas
+=======
+
+When this is in use, local users like "admin" will no longer be available.
+Therefore, either:
+
+* *before* enabling the plugin create a user that will use OIDC to login then
+  set that user as admin
+* *after* enabling the plugin set a user as admin via the CLI user script,
+  ``navuser``

doc/reference/web_authentication.rst

@@ -50,9 +50,15 @@ originating site upon login/logout completion, the originating NAV URL can be
 inserted using the placeholder string ``{}``.  Example::
 
     [remote-user]
-    enabled=yes
-    login-url: https://sso.example.org/login?nexthop={}
-    logout-url: https://sso.example.org/logout?nexthop={}
+    enabled = yes
+    login-url = https://sso.example.org/login?nexthop={}
+    logout-url = https://sso.example.org/logout?nexthop={}
+
+``logout-url`` will set the link that the logout-button points to, the default
+is "/index/logout".
+
+Some remote user systems need to be visited *after* NAV has logged out the
+user locally. The flag for that is ``post-logout-redirect-url``.
 
 
 Relevant How Tos:

python/nav/etc/webfront/webfront.conf

@@ -122,6 +122,11 @@ enabled = no
 # These variables can be used to control which URLs NAV will redirect the user
 # to when login or logout is requested. The string `{}` acts as a placeholder,
 # where NAV will insert the URL the external idP should return the client to
-# when login/logout is done.
+# when login/logout is done. Changing *logout-url* changes what the
+# Logout-button in the webpage header points to.
 #login-url=https://sso.example.org/login/?nexthop={}
 #logout-url=https://sso.example.org/logout/?nexthop={}
+
+# Some remote user systems need to be visited *after* NAV has logged the user
+# out. The default/unset value is "/"
+#post-logout-redirect-url=/magic/logout?nexthop=/

python/nav/web/auth/__init__.py

@@ -124,6 +124,12 @@ def get_login_url(request):
     return remote_loginurl if remote_loginurl else default_new_url
 
 
+def get_post_logout_redirect_url(request):
+    default = "/"
+    redirect_url = remote_user.get_post_logout_redirect_url(request)
+    return redirect_url if redirect_url else default
+
+
 def get_logout_url(request):
     """Calculate which logout_url to use"""
     remote_logouturl = remote_user.get_logouturl(request)
@@ -152,4 +158,4 @@ def logout(request, sudo=False):
         _logger.debug('logout: logout %s', account.login)
         LogEntry.add_log_entry(account, 'log-out', '{actor} logged out', before=account)
     _logger.debug('logout: redirect to "/" after logout')
-    return u'/'
+    return get_post_logout_redirect_url(request)

python/nav/web/auth/remote_user.py

@@ -53,6 +53,7 @@ class RemoteUserConfigParser(NAVConfigParser):
 varname=REMOTE_USER
 workaround=none
 autocreate=off
+post-logout-redirect-url=/
 """
 
 
@@ -145,6 +146,15 @@ def get_logouturl(request):
     return get_remote_url(request, 'logout-url')
 
 
+def get_post_logout_redirect_url(request):
+    """Return a url (if set) to log out to/via a remote service
+
+    :return: Either a string with an url, or None.
+    :rtype: str, None
+    """
+    return get_remote_url(request, "post-logout-redirect-url")
+
+
 def get_remote_url(request, urltype):
     """Return a url (if set) to a remote service for REMOTE_USER purposes