# Copyright (c) 2022, Oracle and/or its affiliates. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License, version 2.0, as # published by the Free Software Foundation. # # This program is also distributed with certain software (including # but not limited to OpenSSL) that is licensed under separate terms, # as designated in a particular file or component or in included license # documentation. The authors of MySQL hereby grant you an # additional permission to link the program and your derivative works # with the separately licensed software that they have included with # MySQL. # # Without limiting anything contained in the foregoing, this file, # which is part of MySQL Connector/Python, is also subject to the # Universal FOSS Exception, version 1.0, a copy of which can be found at # http://oss.oracle.com/licenses/universal-foss-exception. # # 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, version 2.0, for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software Foundation, Inc., # 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA # mypy: disable-error-code="str-bytes-safe,misc" """Kerberos Authentication Plugin.""" import getpass import os import struct from pathlib import Path from typing import Any, Optional, Tuple from ..errors import InterfaceError, ProgrammingError from ..logger import logger try: import gssapi except ImportError: gssapi = None if os.name != "nt": raise ProgrammingError( "Module gssapi is required for GSSAPI authentication " "mechanism but was not found. Unable to authenticate " "with the server" ) from None try: import sspi import sspicon except ImportError: sspi = None sspicon = None from . import BaseAuthPlugin AUTHENTICATION_PLUGIN_CLASS = ( "MySQLSSPIKerberosAuthPlugin" if os.name == "nt" else "MySQLKerberosAuthPlugin" ) # pylint: disable=c-extension-no-member,no-member class MySQLKerberosAuthPlugin(BaseAuthPlugin): """Implement the MySQL Kerberos authentication plugin.""" plugin_name: str = "authentication_kerberos_client" requires_ssl: bool = False context: Optional[gssapi.SecurityContext] = None @staticmethod def get_user_from_credentials() -> str: """Get user from credentials without realm.""" try: creds = gssapi.Credentials(usage="initiate") user = str(creds.name) if user.find("@") != -1: user, _ = user.split("@", 1) return user except gssapi.raw.misc.GSSError: return getpass.getuser() @staticmethod def get_store() -> dict: """Get a credentials store dictionary. Returns: dict: Credentials store dictionary with the krb5 ccache name. Raises: InterfaceError: If 'KRB5CCNAME' environment variable is empty. """ krb5ccname = os.environ.get( "KRB5CCNAME", f"/tmp/krb5cc_{os.getuid()}" if os.name == "posix" else Path("%TEMP%").joinpath("krb5cc"), ) if not krb5ccname: raise InterfaceError( "The 'KRB5CCNAME' environment variable is set to empty" ) logger.debug("Using krb5 ccache name: FILE:%s", krb5ccname) store = {b"ccache": f"FILE:{krb5ccname}".encode("utf-8")} return store def _acquire_cred_with_password(self, upn: str) -> gssapi.raw.creds.Creds: """Acquire and store credentials through provided password. Args: upn (str): User Principal Name. Returns: gssapi.raw.creds.Creds: GSSAPI credentials. """ logger.debug("Attempt to acquire credentials through provided password") user = gssapi.Name(upn, gssapi.NameType.user) password = self._password.encode("utf-8") try: acquire_cred_result = gssapi.raw.acquire_cred_with_password( user, password, usage="initiate" ) creds = acquire_cred_result.creds gssapi.raw.store_cred_into( self.get_store(), creds=creds, mech=gssapi.MechType.kerberos, overwrite=True, set_default=True, ) except gssapi.raw.misc.GSSError as err: raise ProgrammingError( f"Unable to acquire credentials with the given password: {err}" ) from err return creds @staticmethod def _parse_auth_data(packet: bytes) -> Tuple[str, str]: """Parse authentication data. Get the SPN and REALM from the authentication data packet. Format: SPN string length two bytes + SPN string + UPN realm string length two bytes + UPN realm string Returns: tuple: With 'spn' and 'realm'. """ spn_len = struct.unpack(" Optional[bytes]: """Prepare the first message to the server.""" spn = None realm = None if auth_data: try: spn, realm = self._parse_auth_data(auth_data) except struct.error as err: raise InterruptedError(f"Invalid authentication data: {err}") from err if spn is None: return self.prepare_password() upn = f"{self._username}@{realm}" if self._username else None logger.debug("Service Principal: %s", spn) logger.debug("Realm: %s", realm) try: # Attempt to retrieve credentials from cache file creds: Any = gssapi.Credentials(usage="initiate") creds_upn = str(creds.name) logger.debug("Cached credentials found") logger.debug("Cached credentials UPN: %s", creds_upn) # Remove the realm from user if creds_upn.find("@") != -1: creds_user, creds_realm = creds_upn.split("@", 1) else: creds_user = creds_upn creds_realm = None upn = f"{self._username}@{realm}" if self._username else creds_upn # The user from cached credentials matches with the given user? if self._username and self._username != creds_user: logger.debug( "The user from cached credentials doesn't match with the " "given user" ) if self._password is not None: creds = self._acquire_cred_with_password(upn) if creds_realm and creds_realm != realm and self._password is not None: creds = self._acquire_cred_with_password(upn) except gssapi.raw.exceptions.ExpiredCredentialsError as err: if upn and self._password is not None: creds = self._acquire_cred_with_password(upn) else: raise InterfaceError(f"Credentials has expired: {err}") from err except gssapi.raw.misc.GSSError as err: if upn and self._password is not None: creds = self._acquire_cred_with_password(upn) else: raise InterfaceError( f"Unable to retrieve cached credentials error: {err}" ) from err flags = ( gssapi.RequirementFlag.mutual_authentication, gssapi.RequirementFlag.extended_error, gssapi.RequirementFlag.delegate_to_peer, ) name = gssapi.Name(spn, name_type=gssapi.NameType.kerberos_principal) cname = name.canonicalize(gssapi.MechType.kerberos) self.context = gssapi.SecurityContext( name=cname, creds=creds, flags=sum(flags), usage="initiate" ) try: initial_client_token: Optional[bytes] = self.context.step() except gssapi.raw.misc.GSSError as err: raise InterfaceError(f"Unable to initiate security context: {err}") from err logger.debug("Initial client token: %s", initial_client_token) return initial_client_token def auth_continue( self, tgt_auth_challenge: Optional[bytes] ) -> Tuple[Optional[bytes], bool]: """Continue with the Kerberos TGT service request. With the TGT authentication service given response generate a TGT service request. This method must be invoked sequentially (in a loop) until the security context is completed and an empty response needs to be send to acknowledge the server. Args: tgt_auth_challenge: the challenge for the negotiation. Returns: tuple (bytearray TGS service request, bool True if context is completed otherwise False). """ logger.debug("tgt_auth challenge: %s", tgt_auth_challenge) resp: Optional[bytes] = self.context.step(tgt_auth_challenge) logger.debug("Context step response: %s", resp) logger.debug("Context completed?: %s", self.context.complete) return resp, self.context.complete def auth_accept_close_handshake(self, message: bytes) -> bytes: """Accept handshake and generate closing handshake message for server. This method verifies the server authenticity from the given message and included signature and generates the closing handshake for the server. When this method is invoked the security context is already established and the client and server can send GSSAPI formated secure messages. To finish the authentication handshake the server sends a message with the security layer availability and the maximum buffer size. Since the connector only uses the GSSAPI authentication mechanism to authenticate the user with the server, the server will verify clients message signature and terminate the GSSAPI authentication and send two messages; an authentication acceptance b'\x01\x00\x00\x08\x01' and a OK packet (that must be received after sent the returned message from this method). Args: message: a wrapped gssapi message from the server. Returns: bytearray (closing handshake message to be send to the server). """ if not self.context.complete: raise ProgrammingError("Security context is not completed") logger.debug("Server message: %s", message) logger.debug("GSSAPI flags in use: %s", self.context.actual_flags) try: unwraped = self.context.unwrap(message) logger.debug("Unwraped: %s", unwraped) except gssapi.raw.exceptions.BadMICError as err: logger.debug("Unable to unwrap server message: %s", err) raise InterfaceError(f"Unable to unwrap server message: {err}") from err logger.debug("Unwrapped server message: %s", unwraped) # The message contents for the clients closing message: # - security level 1 byte, must be always 1. # - conciliated buffer size 3 bytes, without importance as no # further GSSAPI messages will be sends. response = bytearray(b"\x01\x00\x00\00") # Closing handshake must not be encrypted. logger.debug("Message response: %s", response) wraped = self.context.wrap(response, encrypt=False) logger.debug( "Wrapped message response: %s, length: %d", wraped[0], len(wraped[0]), ) return wraped.message class MySQLSSPIKerberosAuthPlugin(BaseAuthPlugin): """Implement the MySQL Kerberos authentication plugin with Windows SSPI""" plugin_name: str = "authentication_kerberos_client" requires_ssl: bool = False context: Any = None clientauth: Any = None @staticmethod def _parse_auth_data(packet: bytes) -> Tuple[str, str]: """Parse authentication data. Get the SPN and REALM from the authentication data packet. Format: SPN string length two bytes + SPN string + UPN realm string length two bytes + UPN realm string Returns: tuple: With 'spn' and 'realm'. """ spn_len = struct.unpack(" Optional[bytes]: """Prepare the first message to the server.""" logger.debug("auth_response for sspi") spn = None realm = None if auth_data: try: spn, realm = self._parse_auth_data(auth_data) except struct.error as err: raise InterruptedError(f"Invalid authentication data: {err}") from err logger.debug("Service Principal: %s", spn) logger.debug("Realm: %s", realm) if sspicon is None or sspi is None: raise ProgrammingError( 'Package "pywin32" (Python for Win32 (pywin32) extensions)' " is not installed." ) flags = (sspicon.ISC_REQ_MUTUAL_AUTH, sspicon.ISC_REQ_DELEGATE) if self._username and self._password: _auth_info = (self._username, realm, self._password) else: _auth_info = None targetspn = spn logger.debug("targetspn: %s", targetspn) logger.debug("_auth_info is None: %s", _auth_info is None) # The Security Support Provider Interface (SSPI) is an interface # that allows us to choose from a set of SSPs available in the # system; the idea of SSPI is to keep interface consistent no # matter what back end (a.k.a., SSP) we choose. # When using SSPI we should not use Kerberos directly as SSP, # as remarked in [2], but we can use it indirectly via another # SSP named Negotiate that acts as an application layer between # SSPI and the other SSPs [1]. # Negotiate can select between Kerberos and NTLM on the fly; # it chooses Kerberos unless it cannot be used by one of the # systems involved in the authentication or the calling # application did not provide sufficient information to use # Kerberos. # prefix: https://docs.microsoft.com/en-us/windows/win32/secauthn # [1] prefix/microsoft-negotiate?source=recommendations # [2] prefix/microsoft-kerberos?source=recommendations self.clientauth = sspi.ClientAuth( "Negotiate", targetspn=targetspn, auth_info=_auth_info, scflags=sum(flags), datarep=sspicon.SECURITY_NETWORK_DREP, ) try: data = None err, out_buf = self.clientauth.authorize(data) logger.debug("Context step err: %s", err) logger.debug("Context step out_buf: %s", out_buf) logger.debug("Context completed?: %s", self.clientauth.authenticated) initial_client_token = out_buf[0].Buffer logger.debug("pkg_info: %s", self.clientauth.pkg_info) except Exception as err: raise InterfaceError(f"Unable to initiate security context: {err}") from err logger.debug("Initial client token: %s", initial_client_token) return initial_client_token def auth_continue( self, tgt_auth_challenge: Optional[bytes] ) -> Tuple[Optional[bytes], bool]: """Continue with the Kerberos TGT service request. With the TGT authentication service given response generate a TGT service request. This method must be invoked sequentially (in a loop) until the security context is completed and an empty response needs to be send to acknowledge the server. Args: tgt_auth_challenge: the challenge for the negotiation. Returns: tuple (bytearray TGS service request, bool True if context is completed otherwise False). """ logger.debug("tgt_auth challenge: %s", tgt_auth_challenge) err, out_buf = self.clientauth.authorize(tgt_auth_challenge) logger.debug("Context step err: %s", err) logger.debug("Context step out_buf: %s", out_buf) resp = out_buf[0].Buffer logger.debug("Context step resp: %s", resp) logger.debug("Context completed?: %s", self.clientauth.authenticated) return resp, self.clientauth.authenticated