84 lines
2.8 KiB
Python
84 lines
2.8 KiB
Python
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"""SAML Request Parse/builder"""
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from typing import TYPE_CHECKING, Optional
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from defusedxml import ElementTree
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from signxml import XMLVerifier
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from passbook.crypto.models import CertificateKeyPair
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from passbook.providers.samlv2.saml.constants import (
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NS_SAML_ASSERTION,
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NS_SAML_PROTOCOL,
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SAML_ATTRIB_ACS_URL,
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SAML_ATTRIB_DESTINATION,
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SAML_ATTRIB_ID,
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SAML_ATTRIB_ISSUE_INSTANT,
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SAML_ATTRIB_PROTOCOL_BINDING,
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)
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from passbook.providers.samlv2.saml.utils import decode_base64_and_inflate
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if TYPE_CHECKING:
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from xml.etree.ElementTree import Element # nosec
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# pylint: disable=too-many-instance-attributes
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class SAMLRequest:
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"""SAML Request data class, parse raw base64-encoded data, checks signature and more"""
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_root: "Element"
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acs_url: str
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destination: str
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id: str
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issue_instant: str
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protocol_binding: str
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issuer: str
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is_signed: bool
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_detached_signature: str
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def __init__(self):
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self.acs_url = ""
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self.destination = ""
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# pylint: disable=invalid-name
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self.id = ""
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self.issue_instant = ""
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self.protocol_binding = ""
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@staticmethod
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def parse(raw: str, detached_signature: Optional[str] = None) -> "SAMLRequest":
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"""Prase SAML request from raw string, which can be base64 encoded and deflated.
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Optionally accepts a detached_signature, as from a REDIRECT request."""
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decoded_xml = decode_base64_and_inflate(raw)
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root = ElementTree.fromstring(decoded_xml)
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req = SAMLRequest()
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req._root = root # pylint: disable=protected-access
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# Verify the root element's tag
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_expected_tag = f"{{{NS_SAML_PROTOCOL}}}AuthnRequest"
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if root.tag != _expected_tag:
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raise ValueError(
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f"Invalid root tag, got '{root.tag}', expected '{_expected_tag}."
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)
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req.acs_url = root.attrib[SAML_ATTRIB_ACS_URL]
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req.destination = root.attrib[SAML_ATTRIB_DESTINATION]
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req.id = root.attrib[SAML_ATTRIB_ID]
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req.issue_instant = root.attrib[SAML_ATTRIB_ISSUE_INSTANT]
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req.protocol_binding = root.attrib[SAML_ATTRIB_PROTOCOL_BINDING]
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req.issuer = root.find(f"{{{NS_SAML_ASSERTION}}}Issuer").text
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# Check if this Request is signed
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if detached_signature:
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# pylint: disable=protected-access
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req._detached_signature = detached_signature
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return req
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def verify_signature(self, keypair: CertificateKeyPair):
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"""Verify signature of SAML Request.
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Raises `cryptography.exceptions.InvalidSignature` on validaton failure."""
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verifier = XMLVerifier()
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if self._detached_signature:
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verifier.verify(
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self._detached_signature, x509_cert=keypair.certificate_data
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)
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else:
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verifier.verify(self._root, x509_cert=keypair.certificate_data)
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