240 lines
9.4 KiB
Python
240 lines
9.4 KiB
Python
"""Basic SAML Processor"""
|
|
from typing import TYPE_CHECKING, Dict, List, Union
|
|
|
|
from cryptography.exceptions import InvalidSignature
|
|
from defusedxml import ElementTree
|
|
from django.http import HttpRequest
|
|
from signxml import XMLVerifier
|
|
from structlog import get_logger
|
|
|
|
from passbook.core.exceptions import PropertyMappingExpressionException
|
|
from passbook.providers.saml.exceptions import CannotHandleAssertion
|
|
from passbook.providers.saml.processors.types import SAMLResponseParams
|
|
from passbook.providers.saml.utils import get_random_id
|
|
from passbook.providers.saml.utils.encoding import decode_base64_and_inflate, nice64
|
|
from passbook.providers.saml.utils.time import get_time_string, timedelta_from_string
|
|
from passbook.providers.saml.utils.xml_render import get_assertion_xml, get_response_xml
|
|
|
|
if TYPE_CHECKING:
|
|
from passbook.providers.saml.models import SAMLProvider
|
|
|
|
# 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
|
|
|
|
_remote: "SAMLProvider"
|
|
_http_request: HttpRequest
|
|
|
|
_assertion_xml: str
|
|
_response_xml: str
|
|
_saml_response: str
|
|
|
|
_relay_state: str
|
|
_saml_request: str
|
|
|
|
_assertion_params: Dict[str, Union[str, List[Dict[str, str]]]]
|
|
_request_params: Dict[str, str]
|
|
_response_params: Dict[str, str]
|
|
|
|
@property
|
|
def subject_format(self) -> str:
|
|
"""Get subject Format"""
|
|
return "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress"
|
|
|
|
def __init__(self, remote: "SAMLProvider"):
|
|
self.name = remote.name
|
|
self._remote = remote
|
|
self._logger = get_logger()
|
|
|
|
def _build_assertion(self):
|
|
"""Builds _assertion_params."""
|
|
self._assertion_params = {
|
|
"ASSERTION_ID": get_random_id(),
|
|
"ASSERTION_SIGNATURE": "", # it's unsigned
|
|
"AUDIENCE": self._remote.audience,
|
|
"AUTH_INSTANT": get_time_string(),
|
|
"ISSUE_INSTANT": get_time_string(),
|
|
"NOT_BEFORE": get_time_string(
|
|
timedelta_from_string(self._remote.assertion_valid_not_before)
|
|
),
|
|
"NOT_ON_OR_AFTER": get_time_string(
|
|
timedelta_from_string(self._remote.assertion_valid_not_on_or_after)
|
|
),
|
|
"SESSION_INDEX": self._http_request.session.session_key,
|
|
"SESSION_NOT_ON_OR_AFTER": get_time_string(
|
|
timedelta_from_string(self._remote.session_valid_not_on_or_after)
|
|
),
|
|
"SP_NAME_QUALIFIER": self._remote.audience,
|
|
"SUBJECT": self._http_request.user.email,
|
|
"SUBJECT_FORMAT": self.subject_format,
|
|
"ISSUER": self._remote.issuer,
|
|
}
|
|
self._assertion_params.update(self._request_params)
|
|
|
|
def _build_response(self):
|
|
"""Builds _response_params."""
|
|
self._response_params = {
|
|
"ASSERTION": self._assertion_xml,
|
|
"ISSUE_INSTANT": get_time_string(),
|
|
"RESPONSE_ID": get_random_id(),
|
|
"RESPONSE_SIGNATURE": "", # initially unsigned
|
|
"ISSUER": self._remote.issuer,
|
|
}
|
|
self._response_params.update(self._request_params)
|
|
|
|
def _encode_response(self):
|
|
"""Encodes _response_xml to _encoded_xml."""
|
|
self._saml_response = nice64(str.encode(self._response_xml))
|
|
|
|
def _extract_saml_request(self):
|
|
"""Retrieves the _saml_request AuthnRequest from the _http_request."""
|
|
self._saml_request = self._http_request.session["SAMLRequest"]
|
|
self._relay_state = self._http_request.session["RelayState"]
|
|
|
|
def _format_assertion(self):
|
|
"""Formats _assertion_params as _assertion_xml."""
|
|
# https://commons.lbl.gov/display/IDMgmt/Attribute+Definitions
|
|
attributes = []
|
|
from passbook.providers.saml.models import SAMLPropertyMapping
|
|
|
|
for mapping in self._remote.property_mappings.all().select_subclasses():
|
|
if not isinstance(mapping, SAMLPropertyMapping):
|
|
continue
|
|
try:
|
|
mapping: SAMLPropertyMapping
|
|
value = mapping.evaluate(
|
|
user=self._http_request.user,
|
|
request=self._http_request,
|
|
provider=self._remote,
|
|
)
|
|
mapping_payload = {
|
|
"Name": mapping.saml_name,
|
|
"FriendlyName": mapping.friendly_name,
|
|
}
|
|
# Normal values and arrays need different dict keys as they are handeled
|
|
# differently in the template
|
|
if isinstance(value, list):
|
|
mapping_payload["ValueArray"] = value
|
|
else:
|
|
mapping_payload["Value"] = value
|
|
attributes.append(mapping_payload)
|
|
except PropertyMappingExpressionException as exc:
|
|
self._logger.warning(exc)
|
|
continue
|
|
self._assertion_params["ATTRIBUTES"] = attributes
|
|
self._assertion_xml = 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 = get_response_xml(
|
|
self._response_params, saml_provider=self._remote, assertion_id=assertion_id
|
|
)
|
|
|
|
def _get_saml_response_params(self) -> SAMLResponseParams:
|
|
"""Returns a dictionary of parameters for the response template."""
|
|
return SAMLResponseParams(
|
|
acs_url=self._request_params["ACS_URL"],
|
|
saml_response=self._saml_response,
|
|
relay_state=self._relay_state,
|
|
)
|
|
|
|
def _decode_and_parse_request(self):
|
|
"""Parses various parameters from _request_xml into _request_params."""
|
|
decoded_xml = decode_base64_and_inflate(self._saml_request)
|
|
|
|
if self._remote.require_signing and self._remote.signing_kp:
|
|
self._logger.debug("Verifying Request signature")
|
|
try:
|
|
XMLVerifier().verify(
|
|
decoded_xml, x509_cert=self._remote.signing_kp.certificate_data
|
|
)
|
|
except InvalidSignature as exc:
|
|
raise CannotHandleAssertion("Failed to verify signature") from exc
|
|
|
|
root = ElementTree.fromstring(decoded_xml)
|
|
|
|
params = {}
|
|
params["ACS_URL"] = root.attrib.get(
|
|
"AssertionConsumerServiceURL", self._remote.acs_url
|
|
)
|
|
params["REQUEST_ID"] = root.attrib["ID"]
|
|
params["DESTINATION"] = root.attrib.get("Destination", "")
|
|
params["PROVIDER_NAME"] = root.attrib.get("ProviderName", "")
|
|
self._request_params = params
|
|
|
|
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 = (
|
|
f"ACS URL of {request_acs_url} doesn't match Provider "
|
|
f"ACS URL of {self._remote.acs_url}."
|
|
)
|
|
self._logger.info(msg)
|
|
raise CannotHandleAssertion(msg)
|
|
|
|
def can_handle(self, request: HttpRequest) -> bool:
|
|
"""Returns true if this processor can handle this request."""
|
|
self._http_request = request
|
|
# Read the request.
|
|
try:
|
|
self._extract_saml_request()
|
|
except KeyError:
|
|
raise CannotHandleAssertion(f"Couldn't find SAML request in user session")
|
|
|
|
try:
|
|
self._decode_and_parse_request()
|
|
except Exception as exc:
|
|
raise CannotHandleAssertion(f"Couldn't parse SAML request: {exc}") from exc
|
|
|
|
self._validate_request()
|
|
return True
|
|
|
|
def generate_response(self) -> SAMLResponseParams:
|
|
"""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._http_request)
|
|
|
|
self._build_assertion()
|
|
self._format_assertion()
|
|
self._build_response()
|
|
self._format_response()
|
|
self._encode_response()
|
|
|
|
# Return proper template params.
|
|
return self._get_saml_response_params()
|
|
|
|
def init_deep_link(self, request: HttpRequest):
|
|
"""Initialize this Processor to make an IdP-initiated call to the SP's
|
|
deep-linked URL."""
|
|
self._http_request = 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 = ""
|