118 lines
4.0 KiB
Python
118 lines
4.0 KiB
Python
"""SAML AuthNRequest Parser and dataclass"""
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from base64 import b64decode
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from dataclasses import dataclass
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from typing import Optional
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from urllib.parse import quote_plus
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from cryptography.exceptions import InvalidSignature
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives.asymmetric import padding
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from defusedxml import ElementTree
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from signxml import XMLVerifier
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from structlog import get_logger
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from passbook.providers.saml.exceptions import CannotHandleAssertion
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from passbook.providers.saml.models import SAMLProvider
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from passbook.providers.saml.utils.encoding import decode_base64_and_inflate
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from passbook.sources.saml.processors.constants import (
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NS_SAML_PROTOCOL,
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SAML_NAME_ID_FORMAT_EMAIL,
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)
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LOGGER = get_logger()
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@dataclass
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class AuthNRequest:
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"""AuthNRequest Dataclass"""
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# pylint: disable=invalid-name
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id: Optional[str] = None
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relay_state: Optional[str] = None
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name_id_policy: str = SAML_NAME_ID_FORMAT_EMAIL
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class AuthNRequestParser:
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"""AuthNRequest Parser"""
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provider: SAMLProvider
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def __init__(self, provider: SAMLProvider):
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self.provider = provider
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def _parse_xml(self, decoded_xml: str, relay_state: Optional[str]) -> AuthNRequest:
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root = ElementTree.fromstring(decoded_xml)
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request_acs_url = root.attrib["AssertionConsumerServiceURL"]
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if self.provider.acs_url != request_acs_url:
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msg = (
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f"ACS URL of {request_acs_url} doesn't match Provider "
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f"ACS URL of {self.provider.acs_url}."
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)
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LOGGER.info(msg)
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raise CannotHandleAssertion(msg)
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auth_n_request = AuthNRequest(id=root.attrib["ID"], relay_state=relay_state)
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# Check if AuthnRequest has a NameID Policy object
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name_id_policies = root.findall(f"{{{NS_SAML_PROTOCOL}}}:NameIDPolicy")
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if len(name_id_policies) > 0:
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name_id_policy = name_id_policies[0]
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auth_n_request.name_id_policy = name_id_policy.attrib["Format"]
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return auth_n_request
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def parse(self, saml_request: str, relay_state: Optional[str]) -> AuthNRequest:
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"""Validate and parse raw request with enveloped signautre."""
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decoded_xml = decode_base64_and_inflate(saml_request)
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if self.provider.signing_kp:
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try:
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XMLVerifier().verify(
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decoded_xml, x509_cert=self.provider.signing_kp.certificate_data
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)
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except InvalidSignature as exc:
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raise CannotHandleAssertion("Failed to verify signature") from exc
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return self._parse_xml(decoded_xml, relay_state)
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def parse_detached(
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self,
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saml_request: str,
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relay_state: Optional[str],
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signature: Optional[str] = None,
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sig_alg: Optional[str] = None,
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) -> AuthNRequest:
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"""Validate and parse raw request with detached signature"""
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decoded_xml = decode_base64_and_inflate(saml_request)
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if signature and sig_alg:
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# if sig_alg == "http://www.w3.org/2000/09/xmldsig#rsa-sha1":
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sig_hash = hashes.SHA1() # nosec
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querystring = f"SAMLRequest={quote_plus(saml_request)}&"
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if relay_state is not None:
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querystring += f"RelayState={quote_plus(relay_state)}&"
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querystring += f"SigAlg={sig_alg}"
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public_key = self.provider.signing_kp.private_key.public_key()
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try:
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public_key.verify(
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b64decode(signature),
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querystring.encode(),
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padding.PSS(
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mgf=padding.MGF1(sig_hash), salt_length=padding.PSS.MAX_LENGTH
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),
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sig_hash,
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)
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except InvalidSignature as exc:
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raise CannotHandleAssertion("Failed to verify signature") from exc
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return self._parse_xml(decoded_xml, relay_state)
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def idp_initiated(self) -> AuthNRequest:
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"""Create IdP Initiated AuthNRequest"""
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return AuthNRequest()
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