var/opt/nydus/ops/oscrypto/_tls.py000064400000042665147205300440013312 0ustar00# coding: utf-8 from __future__ import unicode_literals, division, absolute_import, print_function import re from datetime import datetime from ._asn1 import Certificate, int_from_bytes, timezone from ._cipher_suites import CIPHER_SUITE_MAP from .errors import TLSVerificationError, TLSDisconnectError, TLSError __all__ = [ 'detect_client_auth_request', 'extract_chain', 'get_dh_params_length', 'parse_alert', 'parse_handshake_messages', 'parse_session_info', 'parse_tls_records', 'raise_client_auth', 'raise_dh_params', 'raise_disconnection', 'raise_expired_not_yet_valid', 'raise_handshake', 'raise_hostname', 'raise_no_issuer', 'raise_protocol_error', 'raise_revoked', 'raise_self_signed', 'raise_verification', 'raise_weak_signature', ] def extract_chain(server_handshake_bytes): """ Extracts the X.509 certificates from the server handshake bytes for use when debugging :param server_handshake_bytes: A byte string of the handshake data received from the server :return: A list of asn1crypto.x509.Certificate objects """ output = [] chain_bytes = None for record_type, _, record_data in parse_tls_records(server_handshake_bytes): if record_type != b'\x16': continue for message_type, message_data in parse_handshake_messages(record_data): if message_type == b'\x0b': chain_bytes = message_data break if chain_bytes: break if chain_bytes: # The first 3 bytes are the cert chain length pointer = 3 while pointer < len(chain_bytes): cert_length = int_from_bytes(chain_bytes[pointer:pointer + 3]) cert_start = pointer + 3 cert_end = cert_start + cert_length pointer = cert_end cert_bytes = chain_bytes[cert_start:cert_end] output.append(Certificate.load(cert_bytes)) return output def detect_client_auth_request(server_handshake_bytes): """ Determines if a CertificateRequest message is sent from the server asking the client for a certificate :param server_handshake_bytes: A byte string of the handshake data received from the server :return: A boolean - if a client certificate request was found """ for record_type, _, record_data in parse_tls_records(server_handshake_bytes): if record_type != b'\x16': continue for message_type, message_data in parse_handshake_messages(record_data): if message_type == b'\x0d': return True return False def get_dh_params_length(server_handshake_bytes): """ Determines the length of the DH params from the ServerKeyExchange :param server_handshake_bytes: A byte string of the handshake data received from the server :return: None or an integer of the bit size of the DH parameters """ output = None dh_params_bytes = None for record_type, _, record_data in parse_tls_records(server_handshake_bytes): if record_type != b'\x16': continue for message_type, message_data in parse_handshake_messages(record_data): if message_type == b'\x0c': dh_params_bytes = message_data break if dh_params_bytes: break if dh_params_bytes: output = int_from_bytes(dh_params_bytes[0:2]) * 8 return output def parse_alert(server_handshake_bytes): """ Parses the handshake for protocol alerts :param server_handshake_bytes: A byte string of the handshake data received from the server :return: None or an 2-element tuple of integers: 0: 1 (warning) or 2 (fatal) 1: The alert description (see https://tools.ietf.org/html/rfc5246#section-7.2) """ for record_type, _, record_data in parse_tls_records(server_handshake_bytes): if record_type != b'\x15': continue if len(record_data) != 2: return None return (int_from_bytes(record_data[0:1]), int_from_bytes(record_data[1:2])) return None def parse_session_info(server_handshake_bytes, client_handshake_bytes): """ Parse the TLS handshake from the client to the server to extract information including the cipher suite selected, if compression is enabled, the session id and if a new or reused session ticket exists. :param server_handshake_bytes: A byte string of the handshake data received from the server :param client_handshake_bytes: A byte string of the handshake data sent to the server :return: A dict with the following keys: - "protocol": unicode string - "cipher_suite": unicode string - "compression": boolean - "session_id": "new", "reused" or None - "session_ticket: "new", "reused" or None """ protocol = None cipher_suite = None compression = False session_id = None session_ticket = None server_session_id = None client_session_id = None for record_type, _, record_data in parse_tls_records(server_handshake_bytes): if record_type != b'\x16': continue for message_type, message_data in parse_handshake_messages(record_data): # Ensure we are working with a ServerHello message if message_type != b'\x02': continue protocol = { b'\x03\x00': "SSLv3", b'\x03\x01': "TLSv1", b'\x03\x02': "TLSv1.1", b'\x03\x03': "TLSv1.2", b'\x03\x04': "TLSv1.3", }[message_data[0:2]] session_id_length = int_from_bytes(message_data[34:35]) if session_id_length > 0: server_session_id = message_data[35:35 + session_id_length] cipher_suite_start = 35 + session_id_length cipher_suite_bytes = message_data[cipher_suite_start:cipher_suite_start + 2] cipher_suite = CIPHER_SUITE_MAP[cipher_suite_bytes] compression_start = cipher_suite_start + 2 compression = message_data[compression_start:compression_start + 1] != b'\x00' extensions_length_start = compression_start + 1 extensions_data = message_data[extensions_length_start:] for extension_type, extension_data in _parse_hello_extensions(extensions_data): if extension_type == 35: session_ticket = "new" break break for record_type, _, record_data in parse_tls_records(client_handshake_bytes): if record_type != b'\x16': continue for message_type, message_data in parse_handshake_messages(record_data): # Ensure we are working with a ClientHello message if message_type != b'\x01': continue session_id_length = int_from_bytes(message_data[34:35]) if session_id_length > 0: client_session_id = message_data[35:35 + session_id_length] cipher_suite_start = 35 + session_id_length cipher_suite_length = int_from_bytes(message_data[cipher_suite_start:cipher_suite_start + 2]) compression_start = cipher_suite_start + 2 + cipher_suite_length compression_length = int_from_bytes(message_data[compression_start:compression_start + 1]) # On subsequent requests, the session ticket will only be seen # in the ClientHello message if server_session_id is None and session_ticket is None: extensions_length_start = compression_start + 1 + compression_length extensions_data = message_data[extensions_length_start:] for extension_type, extension_data in _parse_hello_extensions(extensions_data): if extension_type == 35: session_ticket = "reused" break break if server_session_id is not None: if client_session_id is None: session_id = "new" else: if client_session_id != server_session_id: session_id = "new" else: session_id = "reused" return { "protocol": protocol, "cipher_suite": cipher_suite, "compression": compression, "session_id": session_id, "session_ticket": session_ticket, } def parse_tls_records(data): """ Creates a generator returning tuples of information about each record in a byte string of data from a TLS client or server. Stops as soon as it find a ChangeCipherSpec message since all data from then on is encrypted. :param data: A byte string of TLS records :return: A generator that yields 3-element tuples: [0] Byte string of record type [1] Byte string of protocol version [2] Byte string of record data """ pointer = 0 data_len = len(data) while pointer < data_len: # Don't try to parse any more once the ChangeCipherSpec is found if data[pointer:pointer + 1] == b'\x14': break length = int_from_bytes(data[pointer + 3:pointer + 5]) yield ( data[pointer:pointer + 1], data[pointer + 1:pointer + 3], data[pointer + 5:pointer + 5 + length] ) pointer += 5 + length def parse_handshake_messages(data): """ Creates a generator returning tuples of information about each message in a byte string of data from a TLS handshake record :param data: A byte string of a TLS handshake record data :return: A generator that yields 2-element tuples: [0] Byte string of message type [1] Byte string of message data """ pointer = 0 data_len = len(data) while pointer < data_len: length = int_from_bytes(data[pointer + 1:pointer + 4]) yield ( data[pointer:pointer + 1], data[pointer + 4:pointer + 4 + length] ) pointer += 4 + length def _parse_hello_extensions(data): """ Creates a generator returning tuples of information about each extension from a byte string of extension data contained in a ServerHello ores ClientHello message :param data: A byte string of a extension data from a TLS ServerHello or ClientHello message :return: A generator that yields 2-element tuples: [0] Byte string of extension type [1] Byte string of extension data """ if data == b'': return extentions_length = int_from_bytes(data[0:2]) extensions_start = 2 extensions_end = 2 + extentions_length pointer = extensions_start while pointer < extensions_end: extension_type = int_from_bytes(data[pointer:pointer + 2]) extension_length = int_from_bytes(data[pointer + 2:pointer + 4]) yield ( extension_type, data[pointer + 4:pointer + 4 + extension_length] ) pointer += 4 + extension_length def raise_hostname(certificate, hostname): """ Raises a TLSVerificationError due to a hostname mismatch :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ is_ip = re.match('^\\d+\\.\\d+\\.\\d+\\.\\d+$', hostname) or hostname.find(':') != -1 if is_ip: hostname_type = 'IP address %s' % hostname else: hostname_type = 'domain name %s' % hostname message = 'Server certificate verification failed - %s does not match' % hostname_type valid_ips = ', '.join(certificate.valid_ips) valid_domains = ', '.join(certificate.valid_domains) if valid_domains: message += ' valid domains: %s' % valid_domains if valid_domains and valid_ips: message += ' or' if valid_ips: message += ' valid IP addresses: %s' % valid_ips raise TLSVerificationError(message, certificate) def raise_verification(certificate): """ Raises a generic TLSVerificationError :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ message = 'Server certificate verification failed' raise TLSVerificationError(message, certificate) def raise_weak_signature(certificate): """ Raises a TLSVerificationError when a certificate uses a weak signature algorithm :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ message = 'Server certificate verification failed - weak certificate signature algorithm' raise TLSVerificationError(message, certificate) def raise_client_auth(): """ Raises a TLSError indicating client authentication is required :raises: TLSError """ message = 'TLS handshake failed - client authentication required' raise TLSError(message) def raise_revoked(certificate): """ Raises a TLSVerificationError due to the certificate being revoked :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ message = 'Server certificate verification failed - certificate has been revoked' raise TLSVerificationError(message, certificate) def raise_no_issuer(certificate): """ Raises a TLSVerificationError due to no issuer certificate found in trust roots :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ message = 'Server certificate verification failed - certificate issuer not found in trusted root certificate store' raise TLSVerificationError(message, certificate) def raise_self_signed(certificate): """ Raises a TLSVerificationError due to a self-signed certificate roots :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ message = 'Server certificate verification failed - certificate is self-signed' raise TLSVerificationError(message, certificate) def raise_lifetime_too_long(certificate): """ Raises a TLSVerificationError due to a certificate lifetime exceeding the CAB forum certificate lifetime limit :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ message = 'Server certificate verification failed - certificate lifetime is too long' raise TLSVerificationError(message, certificate) def raise_expired_not_yet_valid(certificate): """ Raises a TLSVerificationError due to certificate being expired, or not yet being valid :param certificate: An asn1crypto.x509.Certificate object :raises: TLSVerificationError """ validity = certificate['tbs_certificate']['validity'] not_after = validity['not_after'].native not_before = validity['not_before'].native now = datetime.now(timezone.utc) if not_before > now: formatted_before = not_before.strftime('%Y-%m-%d %H:%M:%SZ') message = 'Server certificate verification failed - certificate not valid until %s' % formatted_before elif not_after < now: formatted_after = not_after.strftime('%Y-%m-%d %H:%M:%SZ') message = 'Server certificate verification failed - certificate expired %s' % formatted_after raise TLSVerificationError(message, certificate) def raise_disconnection(): """ Raises a TLSDisconnectError due to a disconnection :raises: TLSDisconnectError """ raise TLSDisconnectError('The remote end closed the connection') def raise_protocol_error(server_handshake_bytes): """ Raises a TLSError due to a protocol error :param server_handshake_bytes: A byte string of the handshake data received from the server :raises: TLSError """ other_protocol = detect_other_protocol(server_handshake_bytes) if other_protocol: raise TLSError('TLS protocol error - server responded using %s' % other_protocol) raise TLSError('TLS protocol error - server responded using a different protocol') def raise_handshake(): """ Raises a TLSError due to a handshake error :raises: TLSError """ raise TLSError('TLS handshake failed') def raise_protocol_version(): """ Raises a TLSError due to a TLS version incompatibility :raises: TLSError """ raise TLSError('TLS handshake failed - protocol version error') def raise_dh_params(): """ Raises a TLSError due to weak DH params :raises: TLSError """ raise TLSError('TLS handshake failed - weak DH parameters') def detect_other_protocol(server_handshake_bytes): """ Looks at the server handshake bytes to try and detect a different protocol :param server_handshake_bytes: A byte string of the handshake data received from the server :return: None, or a unicode string of "ftp", "http", "imap", "pop3", "smtp" """ if server_handshake_bytes[0:5] == b'HTTP/': return 'HTTP' if server_handshake_bytes[0:4] == b'220 ': if re.match(b'^[^\r\n]*ftp', server_handshake_bytes, re.I): return 'FTP' else: return 'SMTP' if server_handshake_bytes[0:4] == b'220-': return 'FTP' if server_handshake_bytes[0:4] == b'+OK ': return 'POP3' if server_handshake_bytes[0:4] == b'* OK' or server_handshake_bytes[0:9] == b'* PREAUTH': return 'IMAP' return None