This repository has been archived on 2024-05-31.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/providers/saml/processors/base.py
Jens Langhammer e36d7928e4 providers/saml: big cleanup, simplify base processor
add New fields for
 - assertion_valid_not_before
 - assertion_valid_not_on_or_after
 - session_valid_not_on_or_after
allow flexible time durations for these fields
fall back to Provider's ACS if none is specified in AuthNRequest
2020-02-14 15:19:48 +01:00

253 lines
9.7 KiB
Python

"""Basic SAML Processor"""
from typing import TYPE_CHECKING, Dict, List, Union
from defusedxml import ElementTree
from django.http import HttpRequest
from structlog import get_logger
from passbook.providers.saml.exceptions import CannotHandleAssertion
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]
_system_params: Dict[str, str]
_response_params: Dict[str, str]
@property
def subject_format(self) -> str:
"""Get subject Format"""
return "urn:oasis:names:tc:SAML:2.0:nameid-format:persistent"
def __init__(self, remote: "SAMLProvider"):
self.name = remote.name
self._remote = remote
self._logger = get_logger()
self._system_params = {
"ISSUER": self._remote.issuer,
}
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,
}
self._assertion_params.update(self._system_params)
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
}
self._response_params.update(self._system_params)
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
self._assertion_params["ATTRIBUTES"] = [
{
"FriendlyName": "eduPersonPrincipalName",
"Name": "urn:oid:1.3.6.1.4.1.5923.1.1.1.6",
"Value": self._http_request.user.email,
},
{
"FriendlyName": "cn",
"Name": "urn:oid:2.5.4.3",
"Value": self._http_request.user.name,
},
{
"FriendlyName": "mail",
"Name": "urn:oid:0.9.2342.19200300.100.1.3",
"Value": self._http_request.user.email,
},
{
"FriendlyName": "displayName",
"Name": "urn:oid:2.16.840.1.113730.3.1.241",
"Value": self._http_request.user.username,
},
{
"FriendlyName": "uid",
"Name": "urn:oid:0.9.2342.19200300.100.1.1",
"Value": self._http_request.user.pk,
},
]
from passbook.providers.saml.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._http_request.user, request=self._http_request
)
)
self._assertion_params["ATTRIBUTES"].append(mapping_payload)
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_django_response_params(self) -> Dict[str, str]:
"""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 _decode_and_parse_request(self):
"""Parses various parameters from _request_xml into _request_params."""
decoded_xml = decode_base64_and_inflate(self._saml_request).decode("utf-8")
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 = "couldn't find ACS url '{}' in SAML2IDP_REMOTES " "setting.".format(
request_acs_url
)
self._logger.info(msg)
raise 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: HttpRequest) -> bool:
"""Returns true if this processor can handle this request."""
self._http_request = request
# Read the request.
try:
self._extract_saml_request()
except Exception as exc:
raise CannotHandleAssertion(
f"can't find SAML request in user session: {exc}"
) from exc
try:
self._decode_and_parse_request()
except Exception as exc:
raise CannotHandleAssertion(f"can't parse SAML request: {exc}") from exc
self._validate_request()
return True
def generate_response(self) -> Dict[str, str]:
"""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._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: HttpRequest, url: str):
"""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 = url