SAML

The SAML backend allows users to authenticate with any provider that supports the SAML 2.0 protocol (commonly used for corporate or academic single sign on).

The SAML backend for python-social-auth allows your web app to act as a SAML Service Provider. You can configure one or more SAML Identity Providers that users can use for authentication. For example, if your users are students, you could enable Harvard and MIT as identity providers, so that students of either of those two universities can use their campus login to access your app.

Required Dependency

You must install python-saml 2.2.0 or higher in order to use this backend, if using Python 3, you need to install python3-saml 1.2.1 or higher.

Required Configuration

At a minimum, you must add the following to your project’s settings:

  • SOCIAL_AUTH_SAML_SP_ENTITY_ID: The SAML Entity ID for your app. This should be a URL that includes a domain name you own. It doesn’t matter what the URL points to. Example: http://saml.yoursite.com

  • SOCIAL_AUTH_SAML_SP_PUBLIC_CERT: The X.509 certificate string for the key pair that your app will use. You can generate a new self-signed key pair with:

    openssl req -new -x509 -days 3652 -nodes -out saml.crt -keyout saml.key
    

    The contents of saml.crt should then be used as the value of this setting (you can omit the first and last lines, which aren’t required).

  • SOCIAL_AUTH_SAML_SP_PRIVATE_KEY: The private key to be used by your app. If you used the example openssl command given above, set this to the contents of saml.key (again, you can omit the first and last lines).

  • SOCIAL_AUTH_SAML_ORG_INFO: A dictionary that contains information about your app. You must specify values for English at a minimum. Each language’s entry should specify a name (not shown to the user), a displayname (shown to the user), and a URL. See the following example:

    {
        "en-US": {
            "name": "example",
            "displayname": "Example Inc.",
            "url": "http://example.com",
        }
    }
    
  • SOCIAL_AUTH_SAML_TECHNICAL_CONTACT: A dictionary with two values, givenName and emailAddress, describing the name and email of a technical contact responsible for your app. Example:

    {
        "givenName": "Tech Gal",
        "emailAddress": "technical@example.com"
    }
    
  • SOCIAL_AUTH_SAML_SUPPORT_CONTACT: A dictionary with two values, givenName and emailAddress, describing the name and email of a support contact for your app. Example:

    {
        "givenName": "Support Guy",
        "emailAddress": "support@example.com",
    }
    
  • SOCIAL_AUTH_SAML_ENABLED_IDPS: The most important setting. List the Entity ID, SSO URL, and x.509 public key certificate for each provider that your app wants to support. The SSO URL must support the HTTP-Redirect binding. You can get these values from the provider’s XML metadata. Here’s an example, for TestShib (the values come from TestShib’s metadata):

    {
        "testshib": {
            "entity_id": "https://idp.testshib.org/idp/shibboleth",
            "url": "https://idp.testshib.org/idp/profile/SAML2/Redirect/SSO",
            "x509cert": "MIIEDjCCAvagAwIBAgIBADA ... 8Bbnl+ev0peYzxFyF5sQA==",
        }
    }
    

    Each IDP can define configuration keys to avoid having to use uniform resource name’s (ie: urn:oid:0.9.2342.19200300.100.1.3 for email address) as attributes to map user details required to complete account creation. The values associated with the attr_* keys correspond to the keys specified as attributes in the IDP.

    Extending on the “testshib” example:

    {
        "testshib": {
            "entity_id": "https://idp.testshib.org/idp/shibboleth",
            "url": "https://idp.testshib.org/idp/profile/SAML2/Redirect/SSO",
            "x509cert": "MIIEDjCCAvagAwIBAgIBADA ... 8Bbnl+ev0peYzxFyF5sQA==",
            "attr_user_permanent_id": "email",
            "attr_first_name": "first_name",
            "attr_last_name": "last_name",
            "attr_username": "email",
            "attr_email": "email",
        }
    }
    

    In this example, the attr_user_permanent_id and attr_email are both set to the email address passed back in the attribute key ‘email’.

    Note: testshib does not provide email as an attribute. This was tested using Okta and G Suite (formerly Google Apps for Business).

Basic Usage

  • Set all of the required configuration variables described above.

  • Generate the SAML XML metadata for your app. The best way to do this is to create a new view/page/URL in your app that will call the backend’s generate_metadata_xml() method. Here’s an example of how to do this in Django:

    def saml_metadata_view(request):
        complete_url = reverse('social:complete', args=("saml", ))
        saml_backend = load_backend(
            load_strategy(request),
            "saml",
            redirect_uri=complete_url,
        )
        metadata, errors = saml_backend.generate_metadata_xml()
        if not errors:
            return HttpResponse(content=metadata, content_type='text/xml')
    
  • Download the metadata for your app that was generated by the above method, and send it to each Identity Provider (IdP) that you wish to use. Each IdP must install and configure your metadata on their system before it will work.

  • Now everything is set! To allow users to login with any given IdP, you need to give them a link to the python-social-auth “begin”/”auth” URL and include an idp query parameter that specifies the name of the IdP to use. This is needed since the backend supports multiple IdPs. The names of the IdPs are the keys used in the SOCIAL_AUTH_SAML_ENABLED_IDPS setting.

    Django example:

    # In view:
    context['testshib_url'] = u"{base}?{params}".format(
        base=reverse('social:begin', kwargs={'backend': 'saml'}),
        params=urllib.urlencode({'next': '/home', 'idp': 'testshib'})
    )
    # In template:
    <a href="{{ testshib_url }}">TestShib Login</a>
    # Result:
    <a href="/login/saml/?next=%2Fhome&amp;idp=testshib">TestShib Login</a>
    
  • Testing with the TestShib provider is recommended, as it is known to work well.

Advanced Settings

  • SOCIAL_AUTH_SAML_SP_EXTRA: This can be set to a dict, and any key/value pairs specified here will be passed to the underlying python-saml library configuration’s sp setting. Refer to the python-saml documentation for details.

  • SOCIAL_AUTH_SAML_SECURITY_CONFIG: This can be set to a dict, and any key/value pairs specified here will be passed to the underlying python-saml library configuration’s security setting. Two useful keys that you can set are metadataCacheDuration and metadataValidUntil, which control the expiry time of your XML metadata. By default, a cache duration of 10 days will be used, which means that IdPs are allowed to cache your metadata for up to 10 days, but no longer. metadataCacheDuration must be specified as an ISO 8601 duration string (e.g. P1D for one day).

  • SOCIAL_AUTH_SAML_EXTRA_DATA: This can be set to a list of tuples similar to the OAuth backend setting. It maps IDP attributes to extra_data attributes. Each attribute will be a list of values (even if only 1 value) per how python-saml processes attributes:

    SOCIAL_AUTH_SAML_EXTRA_DATA = [('attribute_name', 'extra_data_name_for_attribute'),
                                 ('department', 'department'),
                                 ('manager_full_name', 'manager_full_name')]
    

Advanced Usage

You can subclass the SAMLAuth backend to provide custom functionality. In particular, there are two methods that are designed for subclasses to override:

  • get_idp(self, idp_name): Given the name of an IdP, return an instance of SAMLIdentityProvider with the details of the IdP. Override this method if you wish to use some other method for configuring the available identity providers, such as fetching them at runtime from another server, or using a list of providers from a Shibboleth federation.
  • _check_entitlements(self, idp, attributes): This method gets called during the login process and is where you can decide to accept or reject a user based on the user’s SAML attributes. For example, you can restrict access to your application to only accept users who belong to a certain department. After inspecting the passed attributes parameter, do nothing to allow the user to login, or raise social_core.exceptions.AuthForbidden to reject the user.