--- /dev/null
+#!/usr/bin/env python3
+# Unix SMB/CIFS implementation.
+#
+# Tests for Key Trust authentication
+#
+# Based on pkinit_tests.py
+#
+# Copyright (C) Gary Lockyer <gary@catalyst.net.nz> 2025
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+import sys
+import os
+
+sys.path.insert(0, "bin/python")
+os.environ["PYTHONUNBUFFERED"] = "1"
+
+from datetime import datetime, timedelta
+
+from cryptography import x509
+from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import hashes, serialization
+from cryptography.hazmat.primitives.asymmetric import rsa, padding
+from cryptography.x509.oid import NameOID
+
+from samba.dcerpc import security
+from samba.domain.models import User
+from samba.key_credential_link import create_key_credential_link
+from samba.tests.krb5 import kcrypto
+from samba.tests.krb5.kdc_base_test import KDCBaseTest
+from samba.tests.krb5.raw_testcase import PkInit, RawKerberosTest
+from samba.tests.krb5.rfc4120_constants import (
+ DES_EDE3_CBC,
+ KDC_ERR_CLIENT_NOT_TRUSTED,
+ NT_PRINCIPAL,
+ PADATA_PK_AS_REQ,
+)
+import samba.tests.krb5.rfc4120_pyasn1 as krb5_asn1
+
+SidType = RawKerberosTest.SidType
+
+global_asn1_print = False
+global_hexdump = False
+
+
+class KeyTrustTests(KDCBaseTest):
+ @classmethod
+ def setUpClass(cls):
+ super().setUpClass()
+
+ def setUp(self):
+ super().setUp()
+ self.do_asn1_print = global_asn1_print
+ self.do_hexdump = global_hexdump
+
+ def test_key_trust_user(self):
+ """
+ Test key trust logon for a normal account
+ """
+ client_creds = self._get_creds()
+ target_creds = self.get_service_creds()
+ certificate = self._create_certificate(client_creds)
+ public_key = certificate.public_bytes(Encoding.DER)
+ self._add_key_cred_link(client_creds, public_key)
+
+ self._pkinit_req(client_creds, target_creds, certificate)
+
+ def test_key_trust_user_mismatched_keys(self):
+ """
+ Test key trust logon for a normal account, where the certificate
+ public key does not match the msDS-KeyCredentialLink value
+ """
+ client_creds = self._get_creds()
+ target_creds = self.get_service_creds()
+ certificate = self._create_certificate(client_creds)
+
+ private_key = rsa.generate_private_key(
+ public_exponent=65537, key_size=2048, backend=default_backend()
+ )
+ public_key = private_key.public_key().public_bytes(
+ encoding=Encoding.DER, format=PublicFormat.SubjectPublicKeyInfo
+ )
+ self._add_key_cred_link(client_creds, public_key)
+
+ self._pkinit_req(
+ client_creds,
+ target_creds,
+ certificate,
+ expect_error=KDC_ERR_CLIENT_NOT_TRUSTED,
+ )
+
+ def test_key_trust_user_no_keys(self):
+ """
+ Test key trust logon for a normal account,
+ with no msDS-KeyCredentialLink
+ """
+ client_creds = self._get_creds()
+ target_creds = self.get_service_creds()
+ certificate = self._create_certificate(client_creds)
+
+ self._pkinit_req(
+ client_creds,
+ target_creds,
+ certificate,
+ expect_error=KDC_ERR_CLIENT_NOT_TRUSTED,
+ )
+
+ def test_key_trust_computer(self):
+ """
+ Test key trust logon with a computer account.
+ """
+ client_creds = self._get_creds(self.AccountType.COMPUTER)
+ target_creds = self.get_service_creds()
+ certificate = self._create_certificate(client_creds)
+ public_key = certificate.public_bytes(Encoding.DER)
+ self._add_key_cred_link(client_creds, public_key)
+
+ self._pkinit_req(client_creds, target_creds, certificate)
+
+ def test_key_trust_computer_mismatched_keys(self):
+ """
+ Test key trust logon for a computer account, where the certificate
+ public key does not match the msDS-KeyCredentialLink value
+ """
+ client_creds = self._get_creds(self.AccountType.COMPUTER)
+ target_creds = self.get_service_creds()
+ certificate = self._create_certificate(client_creds)
+
+ private_key = rsa.generate_private_key(
+ public_exponent=65537, key_size=2048, backend=default_backend()
+ )
+ public_key = private_key.public_key().public_bytes(
+ encoding=Encoding.DER, format=PublicFormat.SubjectPublicKeyInfo
+ )
+ self._add_key_cred_link(client_creds, public_key)
+
+ self._pkinit_req(
+ client_creds,
+ target_creds,
+ certificate,
+ expect_error=KDC_ERR_CLIENT_NOT_TRUSTED,
+ )
+
+ def test_key_trust_computer_no_keys(self):
+ """
+ Test key trust logon with a computer account,
+ with no msDS-KeyCredentialLink
+ """
+ client_creds = self._get_creds(self.AccountType.COMPUTER)
+ target_creds = self.get_service_creds()
+ certificate = self._create_certificate(client_creds)
+
+ self._pkinit_req(
+ client_creds,
+ target_creds,
+ certificate,
+ expect_error=KDC_ERR_CLIENT_NOT_TRUSTED,
+ )
+
+ def _get_creds(self, account_type=KDCBaseTest.AccountType.USER, use_cache=False):
+ """
+ Return credentials with an account having a UPN for performing
+ PK-INIT.
+
+ Modified from the version in python/samba/tests/krb5/pkinit_tests.py
+ """
+ samdb = self.get_samdb()
+ realm = samdb.domain_dns_name().upper()
+
+ opts = {"upn": f"{{account}}.{realm}@{realm}"}
+
+ return self.get_cached_creds(
+ account_type=account_type, opts=opts, use_cache=use_cache
+ )
+
+ def _add_key_cred_link(self, creds, public_key):
+ """
+ Update the msDS-KeyCredentialLink for the user specified in creds with
+ the supplied public key
+ """
+ link = create_key_credential_link(self.get_samdb(), creds.get_dn(), public_key)
+
+ user = User.find(self.get_samdb(), creds.get_username())
+ self.assertIsNotNone(user)
+ if user is not None:
+ user.key_credential_link = link
+ user.save(self.get_samdb())
+
+ def _create_certificate(self, creds):
+ """
+ Create a new self signed certificate
+
+ Modified from the version in python/samba/tests/krb5/pkinit_tests.py
+ """
+
+ certificate_signature = hashes.SHA256
+
+ user_name = creds.get_username()
+
+ builder = x509.CertificateBuilder()
+
+ # Add the subject name.
+ cert_name = f"{user_name}@{creds.get_realm().lower()}"
+ subject_name = x509.Name(
+ [
+ # This name can be anything; it isn’t needed to authorize the
+ # user. The SubjectAlternativeName is used for that instead.
+ x509.NameAttribute(NameOID.COUNTRY_NAME, "US"),
+ x509.NameAttribute(NameOID.STATE_OR_PROVINCE_NAME, "SambaState"),
+ x509.NameAttribute(NameOID.ORGANIZATION_NAME, "SambaSelfTesting"),
+ x509.NameAttribute(NameOID.ORGANIZATIONAL_UNIT_NAME, "Users"),
+ x509.NameAttribute(NameOID.COMMON_NAME, f"{cert_name}"),
+ ]
+ )
+ builder = builder.subject_name(subject_name)
+
+ # The new certificate is self signed
+ builder = builder.issuer_name(subject_name)
+
+ one_day = timedelta(1, 0, 0)
+
+ # Put the certificate start time in the past to avoid issues where the
+ # KDC considers the certificate to be invalid due to clock skew. Note
+ # that if the certificate predates the existence of the account in AD,
+ # Windows will refuse authentication unless a strong mapping is
+ # present (in the certificate, or in AD).
+ # See https://support.microsoft.com/en-us/topic/kb5014754-certificate-based-authentication-changes-on-windows-domain-controllers-ad2c23b0-15d8-4340-a468-4d4f3b188f16#ID0EFR
+ builder = builder.not_valid_before(datetime.today() - one_day)
+ builder = builder.not_valid_after(datetime.today() + (one_day * 30))
+
+ builder = builder.serial_number(x509.random_serial_number())
+
+ public_key = creds.get_public_key()
+ builder = builder.public_key(public_key)
+
+ # Add the SubjectAlternativeName. Windows uses this to map the account
+ # to the certificate.
+ id_pkinit_ms_san = x509.ObjectIdentifier(str(krb5_asn1.id_pkinit_ms_san))
+ encoded_upn = self.der_encode(creds.get_upn(), asn1Spec=krb5_asn1.MS_UPN_SAN())
+ ms_upn_san = x509.OtherName(id_pkinit_ms_san, encoded_upn)
+ builder = builder.add_extension(
+ x509.SubjectAlternativeName([ms_upn_san]),
+ critical=False,
+ )
+
+ # The key identifier is used to identify the certificate.
+ subject_key_id = x509.SubjectKeyIdentifier.from_public_key(public_key)
+ builder = builder.add_extension(
+ subject_key_id,
+ critical=True,
+ )
+
+ # Add the key usages for which this certificate is valid.
+ builder = builder.add_extension(
+ # Heimdal requires that the certificate be valid for digital
+ # signatures.
+ x509.KeyUsage(digital_signature=True,
+ content_commitment=False,
+ key_encipherment=False,
+ data_encipherment=False,
+ key_agreement=False,
+ key_cert_sign=False,
+ crl_sign=False,
+ encipher_only=False,
+ decipher_only=False),
+ critical=True,
+ )
+
+ certificate = builder.sign(
+ private_key=creds.get_private_key(),
+ algorithm=certificate_signature(),
+ backend=default_backend(),
+ )
+
+ return certificate
+
+ def _pkinit_req(
+ self,
+ creds,
+ target_creds,
+ certificate,
+ expect_error=0,
+ ):
+ """
+ Modified from the version in python/samba/tests/krb5/pkinit_tests.py
+ """
+ signature_algorithm = krb5_asn1.sha1WithRSAEncryption
+ signature_algorithm_id = self.AlgorithmIdentifier_create(signature_algorithm)
+
+ private_key = creds.get_private_key()
+
+ preauth_key = private_key
+
+ pk_nonce = self.get_Nonce()
+
+ def generate_pk_padata(_kdc_exchange_dict, _callback_dict, req_body):
+ # Suppress unused parameter warnings
+ _ = (_kdc_exchange_dict, _callback_dict)
+
+ checksum_blob = self.der_encode(req_body, asn1Spec=krb5_asn1.KDC_REQ_BODY())
+
+ # Calculate the SHA1 checksum over the KDC-REQ-BODY. This checksum
+ # is required to be present in the authenticator, and must be SHA1.
+ digest = hashes.Hash(hashes.SHA1(), default_backend())
+ digest.update(checksum_blob)
+ digest = digest.finalize()
+
+ ctime, cusec = self.get_KerberosTimeWithUsec()
+
+ # Create the authenticator, which shows that we had possession of
+ # the private key at some point.
+ authenticator_obj = self.PKAuthenticator_create(
+ cusec, ctime, pk_nonce, pa_checksum=digest
+ )
+
+ client_public_value = None
+
+ # An optional set of algorithms supported by the client in
+ # decreasing order of preference. For whatever reason, if this
+ # field is missing or empty, Windows will respond with a slightly
+ # differently encoded ReplyKeyPack, wrapping it first in a
+ # ContentInfo structure.
+ supported_cms_types = [
+ self.AlgorithmIdentifier_create(
+ krb5_asn1.id_pkcs1_sha256WithRSAEncryption
+ ),
+ ]
+ auth_pack_obj = self.AuthPack_create(
+ authenticator_obj,
+ client_public_value=client_public_value,
+ supported_cms_types=supported_cms_types,
+ )
+
+ asn1_spec = krb5_asn1.AuthPack
+ auth_pack = self.der_encode(auth_pack_obj, asn1Spec=asn1_spec())
+
+ signature_hash = self.hash_from_algorithm(signature_algorithm)
+
+ pad = padding.PKCS1v15()
+ signed = private_key.sign(
+ auth_pack, padding=pad, algorithm=signature_hash()
+ )
+
+ encap_content_info_obj = self.EncapsulatedContentInfo_create(
+ krb5_asn1.id_pkinit_authData, auth_pack
+ )
+
+ subject_key_id = certificate.extensions.get_extension_for_oid(
+ x509.ExtensionOID.SUBJECT_KEY_IDENTIFIER
+ )
+ signer_identifier = self.SignerIdentifier_create(
+ subject_key_id=subject_key_id.value.digest
+ )
+
+ signer_info = self.SignerInfo_create(
+ signer_identifier,
+ signature_algorithm_id,
+ signature_algorithm_id,
+ signed,
+ signed_attrs=[
+ # Note: these attributes are optional.
+ krb5_asn1.id_pkinit_authData,
+ krb5_asn1.id_messageDigest,
+ ],
+ )
+
+ encoded_cert = certificate.public_bytes(serialization.Encoding.DER)
+ decoded_cert = self.der_decode(
+ encoded_cert, asn1Spec=krb5_asn1.CertificateChoices()
+ )
+
+ signed_auth_pack = self.SignedData_create(
+ [signature_algorithm_id],
+ encap_content_info_obj,
+ signer_infos=[signer_info],
+ certificates=[decoded_cert],
+ crls=None,
+ )
+
+ signed_auth_pack = self.der_encode(
+ signed_auth_pack, asn1Spec=krb5_asn1.SignedData()
+ )
+
+ pk_as_req = self.PK_AS_REQ_create(signed_auth_pack)
+
+ pa_type = PADATA_PK_AS_REQ
+ padata = [self.PA_DATA_create(pa_type, pk_as_req)]
+
+ return padata, req_body
+
+ user_name = creds.get_username()
+ cname = self.PrincipalName_create(
+ name_type=NT_PRINCIPAL, names=user_name.split("/")
+ )
+
+ target_name = target_creds.get_username()
+ target_realm = target_creds.get_realm()
+
+ target_sname = self.PrincipalName_create(
+ name_type=NT_PRINCIPAL, names=["host", target_name[:-1]]
+ )
+ expected_sname = self.PrincipalName_create(
+ name_type=NT_PRINCIPAL, names=[target_name]
+ )
+
+ if expect_error:
+ check_error_fn = self.generic_check_kdc_error
+ check_rep_fn = None
+
+ expected_sname = target_sname
+ else:
+ check_error_fn = None
+ check_rep_fn = self.generic_check_kdc_rep
+
+ kdc_options = "forwardable,renewable,canonicalize,renewable-ok"
+ kdc_options = krb5_asn1.KDCOptions(kdc_options)
+
+ ticket_decryption_key = self.TicketDecryptionKey_from_creds(target_creds)
+
+ expected_groups = None
+ unexpected_groups = {
+ (
+ security.SID_FRESH_PUBLIC_KEY_IDENTITY,
+ SidType.EXTRA_SID,
+ security.SE_GROUP_DEFAULT_FLAGS,
+ )
+ }
+
+ kdc_exchange_dict = self.as_exchange_dict(
+ creds=creds,
+ client_cert=certificate,
+ expected_crealm=creds.get_realm(),
+ expected_cname=cname,
+ expected_srealm=target_realm,
+ expected_sname=expected_sname,
+ expected_supported_etypes=target_creds.tgs_supported_enctypes,
+ expected_groups=expected_groups,
+ unexpected_groups=unexpected_groups,
+ ticket_decryption_key=ticket_decryption_key,
+ generate_padata_fn=generate_pk_padata,
+ check_error_fn=check_error_fn,
+ check_rep_fn=check_rep_fn,
+ check_kdc_private_fn=self.generic_check_kdc_private,
+ expected_error_mode=expect_error,
+ expected_salt=creds.get_salt(),
+ preauth_key=preauth_key,
+ kdc_options=str(kdc_options),
+ using_pkinit=PkInit.PUBLIC_KEY,
+ pk_nonce=pk_nonce,
+ expect_edata=False,
+ expect_matching_nt_hash_in_pac=True,
+ )
+
+ till = self.get_KerberosTime(offset=36000)
+
+ etypes = (
+ kcrypto.Enctype.AES256,
+ kcrypto.Enctype.RC4,
+ )
+ # DES-EDE3-CBC is required for public-key PK-INIT to work on Windows.
+ etypes += (DES_EDE3_CBC,)
+
+ rep = self._generic_kdc_exchange(
+ kdc_exchange_dict,
+ cname=cname,
+ realm=target_realm,
+ sname=target_sname,
+ till_time=till,
+ etypes=etypes,
+ )
+ if expect_error:
+ self.check_error_rep(rep, expect_error)
+ return None
+
+ self.check_as_reply(rep)
+ return kdc_exchange_dict
+
+
+if __name__ == "__main__":
+ global_asn1_print = False
+ global_hexdump = False
+ import unittest
+
+ unittest.main()
projects / thirdparty / samba.git / commitdiff
