125 lines
4.5 KiB
Python
125 lines
4.5 KiB
Python
"""SAML AuthnRequest Processor"""
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from base64 import b64encode
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from typing import Dict
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from urllib.parse import quote_plus
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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 django.http import HttpRequest
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from lxml import etree # nosec
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from lxml.etree import Element # nosec
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from signxml import XMLSigner
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from passbook.providers.saml.utils import get_random_id
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from passbook.providers.saml.utils.encoding import deflate_and_base64_encode
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from passbook.providers.saml.utils.time import get_time_string
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from passbook.sources.saml.models import SAMLSource
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from passbook.sources.saml.processors.constants import (
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NS_MAP,
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NS_SAML_ASSERTION,
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NS_SAML_PROTOCOL,
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)
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SESSION_REQUEST_ID = "passbook_source_saml_request_id"
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class RequestProcessor:
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"""SAML AuthnRequest Processor"""
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source: SAMLSource
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http_request: HttpRequest
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relay_state: str
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request_id: str
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issue_instant: str
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def __init__(self, source: SAMLSource, request: HttpRequest, relay_state: str):
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self.source = source
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self.http_request = request
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self.relay_state = relay_state
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self.request_id = get_random_id()
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self.http_request.session[SESSION_REQUEST_ID] = self.request_id
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self.issue_instant = get_time_string()
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def get_issuer(self) -> Element:
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"""Get Issuer Element"""
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issuer = Element(f"{{{NS_SAML_ASSERTION}}}Issuer")
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issuer.text = self.source.get_issuer(self.http_request)
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return issuer
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def get_name_id_policy(self) -> Element:
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"""Get NameID Policy Element"""
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name_id_policy = Element(f"{{{NS_SAML_PROTOCOL}}}NameIDPolicy")
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name_id_policy.text = self.source.name_id_policy
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return name_id_policy
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def get_auth_n(self) -> Element:
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"""Get full AuthnRequest"""
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auth_n_request = Element(f"{{{NS_SAML_PROTOCOL}}}AuthnRequest", nsmap=NS_MAP)
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auth_n_request.attrib[
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"AssertionConsumerServiceURL"
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] = self.source.build_full_url(self.http_request)
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auth_n_request.attrib["Destination"] = self.source.sso_url
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auth_n_request.attrib["ID"] = self.request_id
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auth_n_request.attrib["IssueInstant"] = self.issue_instant
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auth_n_request.attrib["ProtocolBinding"] = self.source.binding_type
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auth_n_request.attrib["Version"] = "2.0"
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# Create issuer object
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auth_n_request.append(self.get_issuer())
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# Create NameID Policy Object
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auth_n_request.append(self.get_name_id_policy())
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return auth_n_request
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def build_auth_n(self) -> str:
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"""Get Signed string representation of AuthN Request
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(used for POST Bindings)"""
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auth_n_request = self.get_auth_n()
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if self.source.signing_kp:
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signed_request = XMLSigner().sign(
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auth_n_request,
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cert=self.source.signing_kp.certificate_data,
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key=self.source.signing_kp.key_data,
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)
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return etree.tostring(signed_request).decode()
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return etree.tostring(auth_n_request).decode()
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def build_auth_n_detached(self) -> Dict[str, str]:
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"""Get Dict AuthN Request for Redirect bindings, with detached
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Signature. See https://docs.oasis-open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf"""
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auth_n_request = self.get_auth_n()
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saml_request = deflate_and_base64_encode(
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etree.tostring(auth_n_request).decode()
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)
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response_dict = {
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"SAMLRequest": saml_request,
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}
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if self.relay_state != "":
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response_dict["RelayState"] = self.relay_state
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if self.source.signing_kp:
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sig_alg = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
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sig_hash = hashes.SHA1() # nosec
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# Create the full querystring in the correct order to be signed
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querystring = f"SAMLRequest={quote_plus(saml_request)}&"
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if self.relay_state != "":
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querystring += f"RelayState={quote_plus(self.relay_state)}&"
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querystring += f"SigAlg={sig_alg}"
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signature = self.source.signing_kp.private_key.sign(
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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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response_dict["SigAlg"] = sig_alg
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response_dict["Signature"] = b64encode(signature).decode()
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return response_dict
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