241 lines
9.8 KiB
Python
241 lines
9.8 KiB
Python
"""SAML Assertion generator"""
|
|
from hashlib import sha256
|
|
from types import GeneratorType
|
|
|
|
from django.http import HttpRequest
|
|
from lxml import etree # nosec
|
|
from lxml.etree import Element, SubElement # nosec
|
|
from signxml import XMLSigner, XMLVerifier
|
|
from structlog import get_logger
|
|
|
|
from passbook.core.exceptions import PropertyMappingExpressionException
|
|
from passbook.providers.saml.models import SAMLPropertyMapping, SAMLProvider
|
|
from passbook.providers.saml.processors.request_parser import AuthNRequest
|
|
from passbook.providers.saml.utils import get_random_id
|
|
from passbook.providers.saml.utils.time import get_time_string, timedelta_from_string
|
|
from passbook.sources.saml.exceptions import UnsupportedNameIDFormat
|
|
from passbook.sources.saml.processors.constants import (
|
|
NS_MAP,
|
|
NS_SAML_ASSERTION,
|
|
NS_SAML_PROTOCOL,
|
|
NS_SIGNATURE,
|
|
SAML_NAME_ID_FORMAT_EMAIL,
|
|
SAML_NAME_ID_FORMAT_PERSISTENT,
|
|
SAML_NAME_ID_FORMAT_TRANSIENT,
|
|
SAML_NAME_ID_FORMAT_X509,
|
|
)
|
|
|
|
LOGGER = get_logger()
|
|
|
|
|
|
class AssertionProcessor:
|
|
"""Generate a SAML Response from an AuthNRequest"""
|
|
|
|
provider: SAMLProvider
|
|
http_request: HttpRequest
|
|
auth_n_request: AuthNRequest
|
|
|
|
_issue_instant: str
|
|
_assertion_id: str
|
|
|
|
_valid_not_before: str
|
|
_valid_not_on_or_after: str
|
|
|
|
def __init__(
|
|
self, provider: SAMLProvider, request: HttpRequest, auth_n_request: AuthNRequest
|
|
):
|
|
self.provider = provider
|
|
self.http_request = request
|
|
self.auth_n_request = auth_n_request
|
|
|
|
self._issue_instant = get_time_string()
|
|
self._assertion_id = get_random_id()
|
|
|
|
self._valid_not_before = get_time_string(
|
|
timedelta_from_string(self.provider.assertion_valid_not_before)
|
|
)
|
|
self._valid_not_on_or_after = get_time_string(
|
|
timedelta_from_string(self.provider.assertion_valid_not_on_or_after)
|
|
)
|
|
|
|
def get_attributes(self) -> Element:
|
|
"""Get AttributeStatement Element with Attributes from Property Mappings."""
|
|
# https://commons.lbl.gov/display/IDMgmt/Attribute+Definitions
|
|
attribute_statement = Element(f"{{{NS_SAML_ASSERTION}}}AttributeStatement")
|
|
for mapping in self.provider.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.provider,
|
|
)
|
|
if value is None:
|
|
continue
|
|
|
|
attribute = Element(f"{{{NS_SAML_ASSERTION}}}Attribute")
|
|
attribute.attrib["FriendlyName"] = mapping.friendly_name
|
|
attribute.attrib["Name"] = mapping.saml_name
|
|
|
|
if not isinstance(value, (list, GeneratorType)):
|
|
value = [value]
|
|
|
|
for value_item in value:
|
|
attribute_value = SubElement(
|
|
attribute, f"{{{NS_SAML_ASSERTION}}}AttributeValue"
|
|
)
|
|
if not isinstance(value_item, str):
|
|
value_item = str(value_item)
|
|
attribute_value.text = value_item
|
|
|
|
attribute_statement.append(attribute)
|
|
|
|
except PropertyMappingExpressionException as exc:
|
|
LOGGER.warning(exc)
|
|
continue
|
|
return attribute_statement
|
|
|
|
def get_issuer(self) -> Element:
|
|
"""Get Issuer Element"""
|
|
issuer = Element(f"{{{NS_SAML_ASSERTION}}}Issuer", nsmap=NS_MAP)
|
|
issuer.text = self.provider.issuer
|
|
return issuer
|
|
|
|
def get_assertion_auth_n_statement(self) -> Element:
|
|
"""Generate AuthnStatement with AuthnContext and ContextClassRef Elements."""
|
|
auth_n_statement = Element(f"{{{NS_SAML_ASSERTION}}}AuthnStatement")
|
|
auth_n_statement.attrib["AuthnInstant"] = self._valid_not_before
|
|
auth_n_statement.attrib["SessionIndex"] = self._assertion_id
|
|
|
|
auth_n_context = SubElement(
|
|
auth_n_statement, f"{{{NS_SAML_ASSERTION}}}AuthnContext"
|
|
)
|
|
auth_n_context_class_ref = SubElement(
|
|
auth_n_context, f"{{{NS_SAML_ASSERTION}}}AuthnContextClassRef"
|
|
)
|
|
auth_n_context_class_ref.text = (
|
|
"urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport"
|
|
)
|
|
return auth_n_statement
|
|
|
|
def get_assertion_conditions(self) -> Element:
|
|
"""Generate Conditions with AudienceRestriction and Audience Elements."""
|
|
conditions = Element(f"{{{NS_SAML_ASSERTION}}}Conditions")
|
|
conditions.attrib["NotBefore"] = self._valid_not_before
|
|
conditions.attrib["NotOnOrAfter"] = self._valid_not_on_or_after
|
|
audience_restriction = SubElement(
|
|
conditions, f"{{{NS_SAML_ASSERTION}}}AudienceRestriction"
|
|
)
|
|
audience = SubElement(audience_restriction, f"{{{NS_SAML_ASSERTION}}}Audience")
|
|
audience.text = self.provider.audience
|
|
return conditions
|
|
|
|
def get_name_id(self) -> Element:
|
|
"""Get NameID Element"""
|
|
name_id = Element(f"{{{NS_SAML_ASSERTION}}}NameID")
|
|
name_id.attrib["Format"] = self.auth_n_request.name_id_policy
|
|
if name_id.attrib["Format"] == SAML_NAME_ID_FORMAT_EMAIL:
|
|
name_id.text = self.http_request.user.email
|
|
return name_id
|
|
if name_id.attrib["Format"] == SAML_NAME_ID_FORMAT_PERSISTENT:
|
|
name_id.text = self.http_request.user.username
|
|
return name_id
|
|
if name_id.attrib["Format"] == SAML_NAME_ID_FORMAT_X509:
|
|
# This attribute is statically set by the LDAP source
|
|
name_id.text = self.http_request.user.attributes.get(
|
|
"distinguishedName", ""
|
|
)
|
|
return name_id
|
|
if name_id.attrib["Format"] == SAML_NAME_ID_FORMAT_TRANSIENT:
|
|
# This attribute is statically set by the LDAP source
|
|
session_key: str = self.http_request.user.session.session_key
|
|
name_id.text = sha256(session_key.encode()).hexdigest()
|
|
return name_id
|
|
raise UnsupportedNameIDFormat(
|
|
f"Assertion contains NameID with unsupported format {name_id.attrib['Format']}."
|
|
)
|
|
|
|
def get_assertion_subject(self) -> Element:
|
|
"""Generate Subject Element with NameID and SubjectConfirmation Objects"""
|
|
subject = Element(f"{{{NS_SAML_ASSERTION}}}Subject")
|
|
subject.append(self.get_name_id())
|
|
|
|
subject_confirmation = SubElement(
|
|
subject, f"{{{NS_SAML_ASSERTION}}}SubjectConfirmation"
|
|
)
|
|
subject_confirmation.attrib["Method"] = "urn:oasis:names:tc:SAML:2.0:cm:bearer"
|
|
|
|
subject_confirmation_data = SubElement(
|
|
subject_confirmation, f"{{{NS_SAML_ASSERTION}}}SubjectConfirmationData"
|
|
)
|
|
if self.auth_n_request.id:
|
|
subject_confirmation_data.attrib["InResponseTo"] = self.auth_n_request.id
|
|
subject_confirmation_data.attrib["NotOnOrAfter"] = self._issue_instant
|
|
subject_confirmation_data.attrib["Recipient"] = self.provider.acs_url
|
|
return subject
|
|
|
|
def get_assertion(self) -> Element:
|
|
"""Generate Main Assertion Element"""
|
|
assertion = Element(f"{{{NS_SAML_ASSERTION}}}Assertion", nsmap=NS_MAP)
|
|
assertion.attrib["Version"] = "2.0"
|
|
assertion.attrib["ID"] = self._assertion_id
|
|
assertion.attrib["IssueInstant"] = self._issue_instant
|
|
assertion.append(self.get_issuer())
|
|
|
|
if self.provider.signing_kp:
|
|
# We need a placeholder signature as SAML requires the signature to be between
|
|
# Issuer and subject
|
|
signature_placeholder = SubElement(
|
|
assertion, f"{{{NS_SIGNATURE}}}Signature", nsmap=NS_MAP
|
|
)
|
|
signature_placeholder.attrib["Id"] = "placeholder"
|
|
|
|
assertion.append(self.get_assertion_subject())
|
|
assertion.append(self.get_assertion_conditions())
|
|
assertion.append(self.get_assertion_auth_n_statement())
|
|
|
|
assertion.append(self.get_attributes())
|
|
return assertion
|
|
|
|
def get_response(self) -> Element:
|
|
"""Generate Root response element"""
|
|
response = Element(f"{{{NS_SAML_PROTOCOL}}}Response", nsmap=NS_MAP)
|
|
response.attrib["Version"] = "2.0"
|
|
response.attrib["IssueInstant"] = self._issue_instant
|
|
response.attrib["Destination"] = self.provider.acs_url
|
|
response.attrib["ID"] = get_random_id()
|
|
if self.auth_n_request.id:
|
|
response.attrib["InResponseTo"] = self.auth_n_request.id
|
|
|
|
response.append(self.get_issuer())
|
|
|
|
status = SubElement(response, f"{{{NS_SAML_PROTOCOL}}}Status")
|
|
status_code = SubElement(status, f"{{{NS_SAML_PROTOCOL}}}StatusCode")
|
|
status_code.attrib["Value"] = "urn:oasis:names:tc:SAML:2.0:status:Success"
|
|
|
|
response.append(self.get_assertion())
|
|
return response
|
|
|
|
def build_response(self) -> str:
|
|
"""Build string XML Response and sign if signing is enabled."""
|
|
root_response = self.get_response()
|
|
if self.provider.signing_kp:
|
|
signer = XMLSigner(
|
|
c14n_algorithm="http://www.w3.org/2001/10/xml-exc-c14n#",
|
|
signature_algorithm=self.provider.signature_algorithm,
|
|
digest_algorithm=self.provider.digest_algorithm,
|
|
)
|
|
signed = signer.sign(
|
|
root_response,
|
|
key=self.provider.signing_kp.private_key,
|
|
cert=[self.provider.signing_kp.certificate_data],
|
|
reference_uri=self._assertion_id,
|
|
)
|
|
XMLVerifier().verify(
|
|
signed, x509_cert=self.provider.signing_kp.certificate_data
|
|
)
|
|
return etree.tostring(signed).decode("utf-8") # nosec
|
|
return etree.tostring(root_response).decode("utf-8") # nosec
|