This repository has been archived on 2024-05-31. You can view files and clone it, but cannot push or open issues or pull requests.
authentik/passbook/saml_idp/base.py

325 lines
12 KiB
Python

"""Basic SAML Processor"""
import time
import uuid
from defusedxml import ElementTree
from structlog import get_logger
from passbook.saml_idp import exceptions, utils, xml_render
MINUTES = 60
HOURS = 60 * MINUTES
def get_random_id():
"""Random hex id"""
# It is very important that these random IDs NOT start with a number.
random_id = '_' + uuid.uuid4().hex
return random_id
def get_time_string(delta=0):
"""Get Data formatted in SAML format"""
return time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime(time.time() + delta))
# Design note: I've tried to make this easy to sub-class and override
# just the bits you need to override. I've made use of object properties,
# so that your sub-classes have access to all information: use wisely.
# Formatting note: These methods are alphabetized.
# pylint: disable=too-many-instance-attributes
class Processor:
"""Base SAML 2.0 AuthnRequest to Response Processor.
Sub-classes should provide Service Provider-specific functionality."""
is_idp_initiated = False
_audience = ''
_assertion_params = None
_assertion_xml = None
_assertion_id = None
_django_request = None
_relay_state = None
_request = None
_request_id = None
_request_xml = None
_request_params = None
_response_id = None
_response_xml = None
_response_params = None
_saml_request = None
_saml_response = None
_session_index = None
_subject = None
_subject_format = 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
_system_params = {}
@property
def dotted_path(self):
"""Return a dotted path to this class"""
return '{module}.{class_name}'.format(
module=self.__module__,
class_name=self.__class__.__name__)
def __init__(self, remote):
self.name = remote.name
self._remote = remote
self._logger = get_logger(__name__)
self._system_params['ISSUER'] = self._remote.issuer
self._logger.debug('processor configured')
def _build_assertion(self):
"""Builds _assertion_params."""
self._determine_assertion_id()
self._determine_audience()
self._determine_subject()
self._determine_session_index()
self._assertion_params = {
'ASSERTION_ID': self._assertion_id,
'ASSERTION_SIGNATURE': '', # it's unsigned
'AUDIENCE': self._audience,
'AUTH_INSTANT': get_time_string(),
'ISSUE_INSTANT': get_time_string(),
'NOT_BEFORE': get_time_string(-1 * HOURS), # TODO: Make these settings.
'NOT_ON_OR_AFTER': get_time_string(86400 * MINUTES),
'SESSION_INDEX': self._session_index,
'SESSION_NOT_ON_OR_AFTER': get_time_string(8 * HOURS),
'SP_NAME_QUALIFIER': self._audience,
'SUBJECT': self._subject,
'SUBJECT_FORMAT': self._subject_format,
}
self._assertion_params.update(self._system_params)
self._assertion_params.update(self._request_params)
def _build_response(self):
"""Builds _response_params."""
self._determine_response_id()
self._response_params = {
'ASSERTION': self._assertion_xml,
'ISSUE_INSTANT': get_time_string(),
'RESPONSE_ID': self._response_id,
'RESPONSE_SIGNATURE': '', # initially unsigned
}
self._response_params.update(self._system_params)
self._response_params.update(self._request_params)
def _decode_request(self):
"""Decodes _request_xml from _saml_request."""
self._request_xml = utils.decode_base64_and_inflate(self._saml_request).decode('utf-8')
self._logger.debug('SAML request decoded')
def _determine_assertion_id(self):
"""Determines the _assertion_id."""
self._assertion_id = get_random_id()
def _determine_audience(self):
"""Determines the _audience."""
self._audience = self._remote.audience
self._logger.info('determined audience')
def _determine_response_id(self):
"""Determines _response_id."""
self._response_id = get_random_id()
def _determine_session_index(self):
self._session_index = self._django_request.session.session_key
def _determine_subject(self):
"""Determines _subject and _subject_type for Assertion Subject."""
self._subject = self._django_request.user.email
def _encode_response(self):
"""Encodes _response_xml to _encoded_xml."""
self._saml_response = utils.nice64(str.encode(self._response_xml))
def _extract_saml_request(self):
"""Retrieves the _saml_request AuthnRequest from the _django_request."""
self._saml_request = self._django_request.session['SAMLRequest']
self._relay_state = self._django_request.session['RelayState']
def _format_assertion(self):
"""Formats _assertion_params as _assertion_xml."""
self._assertion_params['ATTRIBUTES'] = [
{
'FriendlyName': 'eduPersonPrincipalName',
'Name': 'urn:oid:1.3.6.1.4.1.5923.1.1.1.6',
'Value': self._django_request.user.email,
},
{
'FriendlyName': 'cn',
'Name': 'urn:oid:2.5.4.3',
'Value': self._django_request.user.name,
},
{
'FriendlyName': 'mail',
'Name': 'urn:oid:0.9.2342.19200300.100.1.3',
'Value': self._django_request.user.email,
},
{
'FriendlyName': 'displayName',
'Name': 'urn:oid:2.16.840.1.113730.3.1.241',
'Value': self._django_request.user.username,
},
]
from passbook.saml_idp.models import SAMLPropertyMapping
for mapping in self._remote.property_mappings.all().select_subclasses():
if isinstance(mapping, SAMLPropertyMapping):
mapping_payload = {
'Name': mapping.saml_name,
'ValueArray': [],
'FriendlyName': mapping.friendly_name
}
for value in mapping.values:
mapping_payload['ValueArray'].append(value.format(
user=self._django_request.user,
request=self._django_request
))
self._assertion_params['ATTRIBUTES'].append(mapping_payload)
self._assertion_xml = xml_render.get_assertion_xml(
'saml/xml/assertions/generic.xml', self._assertion_params, signed=True)
def _format_response(self):
"""Formats _response_params as _response_xml."""
assertion_id = self._assertion_params['ASSERTION_ID']
self._response_xml = xml_render.get_response_xml(self._response_params,
saml_provider=self._remote,
assertion_id=assertion_id)
def _get_django_response_params(self):
"""Returns a dictionary of parameters for the response template."""
return {
'acs_url': self._request_params['ACS_URL'],
'saml_response': self._saml_response,
'relay_state': self._relay_state,
'autosubmit': self._remote.application.skip_authorization,
}
def _parse_request(self):
"""Parses various parameters from _request_xml into _request_params."""
# Minimal test to verify that it's not binarily encoded still:
if not str(self._request_xml.strip()).startswith('<'):
raise Exception('RequestXML is not valid XML; '
'it may need to be decoded or decompressed.')
root = ElementTree.fromstring(self._request_xml)
params = {}
params['ACS_URL'] = root.attrib['AssertionConsumerServiceURL']
params['REQUEST_ID'] = root.attrib['ID']
params['DESTINATION'] = root.attrib.get('Destination', '')
params['PROVIDER_NAME'] = root.attrib.get('ProviderName', '')
self._request_params = params
def _reset(self, django_request, sp_config=None):
"""Initialize (and reset) object properties, so we don't risk carrying
over anything from the last authentication.
If provided, use sp_config throughout; otherwise, it will be set in
_validate_request(). """
self._assertion_params = sp_config
self._assertion_xml = sp_config
self._assertion_id = sp_config
self._django_request = django_request
self._relay_state = sp_config
self._request = sp_config
self._request_id = sp_config
self._request_xml = sp_config
self._request_params = sp_config
self._response_id = sp_config
self._response_xml = sp_config
self._response_params = sp_config
self._saml_request = sp_config
self._saml_response = sp_config
self._session_index = sp_config
self._subject = sp_config
self._subject_format = 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
self._system_params = {
'ISSUER': self._remote.issuer
}
def _validate_request(self):
"""
Validates the SAML request against the SP configuration of this
processor. Sub-classes should override this and raise a
`CannotHandleAssertion` exception if the validation fails.
Raises:
CannotHandleAssertion: if the ACS URL specified in the SAML request
doesn't match the one specified in the processor config.
"""
request_acs_url = self._request_params['ACS_URL']
if self._remote.acs_url != request_acs_url:
msg = ("couldn't find ACS url '{}' in SAML2IDP_REMOTES "
"setting.".format(request_acs_url))
self._logger.info(msg)
raise exceptions.CannotHandleAssertion(msg)
def _validate_user(self):
"""Validates the User. Sub-classes should override this and
throw an CannotHandleAssertion Exception if the validation does not succeed."""
def can_handle(self, request):
"""Returns true if this processor can handle this request."""
self._reset(request)
# Read the request.
try:
self._extract_saml_request()
except Exception as exc:
msg = "can't find SAML request in user session: %s" % exc
self._logger.info(msg)
raise exceptions.CannotHandleAssertion(msg)
try:
self._decode_request()
except Exception as exc:
msg = "can't decode SAML request: %s" % exc
self._logger.info(msg)
raise exceptions.CannotHandleAssertion(msg)
try:
self._parse_request()
except Exception as exc:
msg = "can't parse SAML request: %s" % exc
self._logger.info(msg)
raise exceptions.CannotHandleAssertion(msg)
self._validate_request()
return True
def generate_response(self):
"""Processes request and returns template variables suitable for a response."""
# Build the assertion and response.
# Only call can_handle if SP initiated Request, otherwise we have no Request
if not self.is_idp_initiated:
self.can_handle(self._django_request)
self._validate_user()
self._build_assertion()
self._format_assertion()
self._build_response()
self._format_response()
self._encode_response()
# Return proper template params.
return self._get_django_response_params()
def init_deep_link(self, request, url):
"""Initialize this Processor to make an IdP-initiated call to the SP's
deep-linked URL."""
self._reset(request)
acs_url = self._remote.acs_url
# NOTE: The following request params are made up. Some are blank,
# because they comes over in the AuthnRequest, but we don't have an
# AuthnRequest in this case:
# - Destination: Should be this IdP's SSO endpoint URL. Not used in the response?
# - ProviderName: According to the spec, this is optional.
self._request_params = {
'ACS_URL': acs_url,
'DESTINATION': '',
'PROVIDER_NAME': '',
}
self._relay_state = url