CVE-2022-31124: Improved error handling to prevent unhandled exceptions in calling code. · scottcwang/openssh_key_parser@d5b53b4

@@ -221,118 +221,127 @@ def from_bytes( Raises: ValueError: The provided byte string is not an ``openssh-key-v1`` key list or the declared key count is negative. key list, when the declared key count is negative, or when an EOF is found while parsing the key. UserWarning: The check numbers in the decrypted private byte string do not match (likely due to an incorrect passphrase), the key type or parameter values of a private key do not match that of the corresponding public key in the list, or the padding bytes at the end of the decrypted private byte string are not as expected. “"” byte_stream = PascalStyleByteStream(byte_string) try: byte_stream = PascalStyleByteStream(byte_string)
header = byte_stream.read_from_format_instructions_dict( cls.HEADER_FORMAT_INSTRUCTIONS_DICT ) header = byte_stream.read_from_format_instructions_dict( cls.HEADER_FORMAT_INSTRUCTIONS_DICT )
if header[‘auth_magic’] != b’openssh-key-v1\x00’: raise ValueError(‘Not an openssh-key-v1 key’)
if header[‘auth_magic’] != b’openssh-key-v1\x00’: raise ValueError(‘Not an openssh-key-v1 key’) num_keys = header[‘num_keys’]
num_keys = header[‘num_keys’] if num_keys < 0: raise ValueError(‘Cannot parse negative number of keys’)
if num_keys < 0: raise ValueError(‘Cannot parse negative number of keys’) public_key_list = [] for i in range(num_keys): public_key_bytes = byte_stream.read_from_format_instruction( PascalStyleFormatInstruction.BYTES ) public_key_list.append( PublicKey.from_bytes(public_key_bytes) )
public_key_list = [] for i in range(num_keys): public_key_bytes = byte_stream.read_from_format_instruction( cipher_bytes = byte_stream.read_from_format_instruction( PascalStyleFormatInstruction.BYTES ) public_key_list.append( PublicKey.from_bytes(public_key_bytes) )
cipher_bytes = byte_stream.read_from_format_instruction( PascalStyleFormatInstruction.BYTES )
kdf_class = get_kdf_options_class(header[‘kdf’]) kdf_options = kdf_class( PascalStyleByteStream( header[‘kdf_options’] ).read_from_format_instructions_dict( kdf_class.FORMAT_INSTRUCTIONS_DICT kdf_class = get_kdf_options_class(header[‘kdf’]) kdf_options = kdf_class( PascalStyleByteStream( header[‘kdf_options’] ).read_from_format_instructions_dict( kdf_class.FORMAT_INSTRUCTIONS_DICT ) ) )
cipher_class = get_cipher_class(header[‘cipher’]) cipher_class = get_cipher_class(header[‘cipher’])
if kdf_class == NoneKDFOptions: passphrase = ‘’ elif passphrase is None: passphrase = getpass.getpass(‘Key passphrase: ') if kdf_class == NoneKDFOptions: passphrase = ‘’ elif passphrase is None: passphrase = getpass.getpass(‘Key passphrase: ')
if issubclass(cipher_class, ConfidentialityIntegrityCipher): cipher_bytes += byte_stream.read_fixed_bytes( cipher_class.TAG_LENGTH )
decipher_bytes = cipher_class.decrypt( kdf_class(kdf_options), passphrase, cipher_bytes )
decipher_byte_stream = PascalStyleByteStream(decipher_bytes) if issubclass(cipher_class, ConfidentialityIntegrityCipher): cipher_bytes += byte_stream.read_fixed_bytes( cipher_class.TAG_LENGTH )
decipher_bytes_header = \ decipher_byte_stream.read_from_format_instructions_dict( cls.DECIPHER_BYTES_HEADER_FORMAT_INSTRUCTIONS_DICT decipher_bytes = cipher_class.decrypt( kdf_class(kdf_options), passphrase, cipher_bytes )
if decipher_bytes_header[‘check_int_1’] \ != decipher_bytes_header[‘check_int_2’]: warnings.warn(‘Cipher header check numbers do not match’) decipher_byte_stream = PascalStyleByteStream(decipher_bytes)
initlist = [] for i in range(num_keys): initlist.append( PublicPrivateKeyPair( public_key_list[i], PrivateKey.from_byte_stream(decipher_byte_stream) ) ) if initlist[i].public.header[‘key_type’] \ != initlist[i].private.header[‘key_type’]: warnings.warn( f’Inconsistency between private and public ' f’key types for key {i}’ decipher_bytes_header = \ decipher_byte_stream.read_from_format_instructions_dict( cls.DECIPHER_BYTES_HEADER_FORMAT_INSTRUCTIONS_DICT ) if not all( ( initlist[i].public.params[k] == initlist[i].private.params[k] ) for k in ( initlist[i].public.params.keys() & initlist[i].private.params.keys()
if decipher_bytes_header[‘check_int_1’] \ != decipher_bytes_header[‘check_int_2’]: warnings.warn(‘Cipher header check numbers do not match’)
initlist = [] for i in range(num_keys): initlist.append( PublicPrivateKeyPair( public_key_list[i], PrivateKey.from_byte_stream(decipher_byte_stream) ) ) if initlist[i].public.header[‘key_type’] \ != initlist[i].private.header[‘key_type’]: warnings.warn( f’Inconsistency between private and public ' f’key types for key {i}’ ) if not all( ( initlist[i].public.params[k] == initlist[i].private.params[k] ) for k in ( initlist[i].public.params.keys() & initlist[i].private.params.keys() ) ): warnings.warn( f’Inconsistency between private and public ' f’values for key {i}’ )
decipher_padding = decipher_byte_stream.read()
if ( len(decipher_byte_stream.getvalue()) % cipher_class.BLOCK_SIZE != 0 ) or not ( bytes( range(1, 1 + cipher_class.BLOCK_SIZE) ).startswith(decipher_padding) ): warnings.warn( f’Inconsistency between private and public ' f’values for key {i}’ )
decipher_padding = decipher_byte_stream.read()
if ( len(decipher_byte_stream.getvalue()) % cipher_class.BLOCK_SIZE != 0 ) or not ( bytes( range(1, 1 + cipher_class.BLOCK_SIZE) ).startswith(decipher_padding) ): warnings.warn(‘Incorrect padding at end of ciphertext’) warnings.warn(‘Incorrect padding at end of ciphertext’) except ValueError as e: raise e except EOFError as e: raise ValueError(‘Premature EOF detected while parsing key.’) except e: raise ValueError(‘Unexpected error condition reached.’)
return cls( initlist,