837 lines
29 KiB
Python
837 lines
29 KiB
Python
# (c) 2014, James Tanner <tanner.jc@gmail.com>
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# (c) 2016, Adrian Likins <alikins@redhat.com>
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# (c) 2016, Toshio Kuratomi <tkuratomi@ansible.com>
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#
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# Ansible is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Ansible is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
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# Make coding more python3-ish
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from __future__ import (absolute_import, division, print_function)
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__metaclass__ = type
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import os
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import shlex
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import shutil
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import sys
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import tempfile
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import random
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from io import BytesIO
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from subprocess import call
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from hashlib import sha256
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from binascii import hexlify
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from binascii import unhexlify
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from hashlib import md5
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# Note: Only used for loading obsolete VaultAES files. All files are written
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# using the newer VaultAES256 which does not require md5
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try:
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from Crypto.Hash import SHA256, HMAC
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HAS_HASH = True
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except ImportError:
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HAS_HASH = False
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# Counter import fails for 2.0.1, requires >= 2.6.1 from pip
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try:
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from Crypto.Util import Counter
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HAS_COUNTER = True
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except ImportError:
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HAS_COUNTER = False
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# KDF import fails for 2.0.1, requires >= 2.6.1 from pip
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try:
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from Crypto.Protocol.KDF import PBKDF2
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HAS_PBKDF2 = True
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except ImportError:
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HAS_PBKDF2 = False
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# AES IMPORTS
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try:
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from Crypto.Cipher import AES as AES
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HAS_AES = True
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except ImportError:
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HAS_AES = False
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from ansible.errors import AnsibleError
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from ansible.module_utils.six import PY3, binary_type
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from ansible.module_utils.six.moves import zip
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from ansible.module_utils._text import to_bytes, to_text
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try:
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from __main__ import display
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except ImportError:
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from ansible.utils.display import Display
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display = Display()
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# OpenSSL pbkdf2_hmac
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HAS_PBKDF2HMAC = False
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try:
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from cryptography.hazmat.primitives.hashes import SHA256 as c_SHA256
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from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
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from cryptography.hazmat.backends import default_backend
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HAS_PBKDF2HMAC = True
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except ImportError:
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pass
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except Exception as e:
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display.vvvv("Optional dependency 'cryptography' raised an exception, falling back to 'Crypto'.")
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import traceback
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display.vvvv("Traceback from import of cryptography was {0}".format(traceback.format_exc()))
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HAS_ANY_PBKDF2HMAC = HAS_PBKDF2 or HAS_PBKDF2HMAC
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CRYPTO_UPGRADE = "ansible-vault requires a newer version of pycrypto than the one installed on your platform." \
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" You may fix this with OS-specific commands such as: yum install python-devel; rpm -e --nodeps python-crypto; pip install pycrypto"
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b_HEADER = b'$ANSIBLE_VAULT'
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CIPHER_WHITELIST = frozenset((u'AES', u'AES256'))
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CIPHER_WRITE_WHITELIST = frozenset((u'AES256',))
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# See also CIPHER_MAPPING at the bottom of the file which maps cipher strings
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# (used in VaultFile header) to a cipher class
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def check_prereqs():
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if not HAS_AES or not HAS_COUNTER or not HAS_ANY_PBKDF2HMAC or not HAS_HASH:
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raise AnsibleError(CRYPTO_UPGRADE)
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class AnsibleVaultError(AnsibleError):
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pass
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def is_encrypted(data):
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""" Test if this is vault encrypted data blob
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:arg data: a byte or text string to test whether it is recognized as vault
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encrypted data
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:returns: True if it is recognized. Otherwise, False.
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"""
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try:
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# Make sure we have a byte string and that it only contains ascii
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# bytes.
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b_data = to_bytes(to_text(data, encoding='ascii', errors='strict', nonstring='strict'), encoding='ascii', errors='strict')
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except (UnicodeError, TypeError):
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# The vault format is pure ascii so if we failed to encode to bytes
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# via ascii we know that this is not vault data.
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# Similarly, if it's not a string, it's not vault data
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return False
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if b_data.startswith(b_HEADER):
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return True
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return False
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def is_encrypted_file(file_obj, start_pos=0, count=-1):
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"""Test if the contents of a file obj are a vault encrypted data blob.
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:arg file_obj: A file object that will be read from.
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:kwarg start_pos: A byte offset in the file to start reading the header
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from. Defaults to 0, the beginning of the file.
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:kwarg count: Read up to this number of bytes from the file to determine
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if it looks like encrypted vault data. The default is -1, read to the
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end of file.
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:returns: True if the file looks like a vault file. Otherwise, False.
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"""
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# read the header and reset the file stream to where it started
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current_position = file_obj.tell()
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try:
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file_obj.seek(start_pos)
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return is_encrypted(file_obj.read(count))
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finally:
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file_obj.seek(current_position)
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class VaultLib:
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def __init__(self, b_password):
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self.b_password = to_bytes(b_password, errors='strict', encoding='utf-8')
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self.cipher_name = None
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self.b_version = b'1.1'
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@staticmethod
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def is_encrypted(data):
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""" Test if this is vault encrypted data
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:arg data: a byte or text string or a python3 to test for whether it is
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recognized as vault encrypted data
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:returns: True if it is recognized. Otherwise, False.
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"""
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# This could in the future, check to see if the data is a vault blob and
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# is encrypted with a key associated with this vault
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# instead of just checking the format.
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display.deprecated(u'vault.VaultLib.is_encrypted is deprecated. Use vault.is_encrypted instead', version='2.4')
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return is_encrypted(data)
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@staticmethod
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def is_encrypted_file(file_obj):
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display.deprecated(u'vault.VaultLib.is_encrypted_file is deprecated. Use vault.is_encrypted_file instead', version='2.4')
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return is_encrypted_file(file_obj)
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def encrypt(self, plaintext):
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"""Vault encrypt a piece of data.
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:arg plaintext: a text or byte string to encrypt.
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:returns: a utf-8 encoded byte str of encrypted data. The string
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contains a header identifying this as vault encrypted data and
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formatted to newline terminated lines of 80 characters. This is
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suitable for dumping as is to a vault file.
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If the string passed in is a text string, it will be encoded to UTF-8
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before encryption.
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"""
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b_plaintext = to_bytes(plaintext, errors='surrogate_or_strict')
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if is_encrypted(b_plaintext):
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raise AnsibleError("input is already encrypted")
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if not self.cipher_name or self.cipher_name not in CIPHER_WRITE_WHITELIST:
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self.cipher_name = u"AES256"
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try:
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this_cipher = CIPHER_MAPPING[self.cipher_name]()
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except KeyError:
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raise AnsibleError(u"{0} cipher could not be found".format(self.cipher_name))
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# encrypt data
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b_ciphertext = this_cipher.encrypt(b_plaintext, self.b_password)
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# format the data for output to the file
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b_vaulttext = self._format_output(b_ciphertext)
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return b_vaulttext
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def decrypt(self, vaulttext, filename=None):
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"""Decrypt a piece of vault encrypted data.
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:arg vaulttext: a string to decrypt. Since vault encrypted data is an
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ascii text format this can be either a byte str or unicode string.
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:kwarg filename: a filename that the data came from. This is only
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used to make better error messages in case the data cannot be
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decrypted.
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:returns: a byte string containing the decrypted data
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"""
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b_vaulttext = to_bytes(vaulttext, errors='strict', encoding='utf-8')
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if self.b_password is None:
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raise AnsibleError("A vault password must be specified to decrypt data")
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if not is_encrypted(b_vaulttext):
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msg = "input is not vault encrypted data"
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if filename:
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msg += "%s is not a vault encrypted file" % filename
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raise AnsibleError(msg)
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# clean out header
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b_vaulttext = self._split_header(b_vaulttext)
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# create the cipher object
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if self.cipher_name in CIPHER_WHITELIST:
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this_cipher = CIPHER_MAPPING[self.cipher_name]()
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else:
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raise AnsibleError("{0} cipher could not be found".format(self.cipher_name))
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# try to unencrypt vaulttext
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b_plaintext = this_cipher.decrypt(b_vaulttext, self.b_password)
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if b_plaintext is None:
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msg = "Decryption failed"
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if filename:
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msg += " on %s" % filename
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raise AnsibleError(msg)
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return b_plaintext
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def _format_output(self, b_ciphertext):
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""" Add header and format to 80 columns
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:arg b_vaulttext: the encrypted and hexlified data as a byte string
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:returns: a byte str that should be dumped into a file. It's
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formatted to 80 char columns and has the header prepended
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"""
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if not self.cipher_name:
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raise AnsibleError("the cipher must be set before adding a header")
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header = b';'.join([b_HEADER, self.b_version,
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to_bytes(self.cipher_name,'utf-8', errors='strict')])
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b_vaulttext = [header]
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b_vaulttext += [b_ciphertext[i:i + 80] for i in range(0, len(b_ciphertext), 80)]
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b_vaulttext += [b'']
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b_vaulttext = b'\n'.join(b_vaulttext)
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return b_vaulttext
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def _split_header(self, b_vaulttext):
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"""Retrieve information about the Vault and clean the data
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When data is saved, it has a header prepended and is formatted into 80
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character lines. This method extracts the information from the header
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and then removes the header and the inserted newlines. The string returned
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is suitable for processing by the Cipher classes.
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:arg b_vaulttext: byte str containing the data from a save file
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:returns: a byte str suitable for passing to a Cipher class's
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decrypt() function.
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"""
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# used by decrypt
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b_tmpdata = b_vaulttext.split(b'\n')
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b_tmpheader = b_tmpdata[0].strip().split(b';')
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self.b_version = b_tmpheader[1].strip()
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self.cipher_name = to_text(b_tmpheader[2].strip())
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b_ciphertext = b''.join(b_tmpdata[1:])
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return b_ciphertext
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class VaultEditor:
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def __init__(self, b_password):
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self.vault = VaultLib(b_password)
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# TODO: mv shred file stuff to it's own class
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def _shred_file_custom(self, tmp_path):
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""""Destroy a file, when shred (core-utils) is not available
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Unix `shred' destroys files "so that they can be recovered only with great difficulty with
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specialised hardware, if at all". It is based on the method from the paper
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"Secure Deletion of Data from Magnetic and Solid-State Memory",
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Proceedings of the Sixth USENIX Security Symposium (San Jose, California, July 22-25, 1996).
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We do not go to that length to re-implement shred in Python; instead, overwriting with a block
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of random data should suffice.
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See https://github.com/ansible/ansible/pull/13700 .
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"""
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file_len = os.path.getsize(tmp_path)
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if file_len > 0: # avoid work when file was empty
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max_chunk_len = min(1024*1024*2, file_len)
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passes = 3
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with open(tmp_path, "wb") as fh:
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for _ in range(passes):
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fh.seek(0, 0)
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# get a random chunk of data, each pass with other length
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chunk_len = random.randint(max_chunk_len//2, max_chunk_len)
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data = os.urandom(chunk_len)
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for _ in range(0, file_len // chunk_len):
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fh.write(data)
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fh.write(data[:file_len % chunk_len])
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assert(fh.tell() == file_len) # FIXME remove this assert once we have unittests to check its accuracy
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os.fsync(fh)
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def _shred_file(self, tmp_path):
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"""Securely destroy a decrypted file
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Note standard limitations of GNU shred apply (For flash, overwriting would have no effect
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due to wear leveling; for other storage systems, the async kernel->filesystem->disk calls never
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guarantee data hits the disk; etc). Furthermore, if your tmp dirs is on tmpfs (ramdisks),
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it is a non-issue.
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Nevertheless, some form of overwriting the data (instead of just removing the fs index entry) is
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a good idea. If shred is not available (e.g. on windows, or no core-utils installed), fall back on
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a custom shredding method.
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"""
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if not os.path.isfile(tmp_path):
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# file is already gone
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return
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try:
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r = call(['shred', tmp_path])
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except (OSError, ValueError):
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# shred is not available on this system, or some other error occurred.
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# ValueError caught because OS X El Capitan is raising an
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# exception big enough to hit a limit in python2-2.7.11 and below.
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# Symptom is ValueError: insecure pickle when shred is not
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# installed there.
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r = 1
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if r != 0:
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# we could not successfully execute unix shred; therefore, do custom shred.
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self._shred_file_custom(tmp_path)
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os.remove(tmp_path)
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def _edit_file_helper(self, filename, existing_data=None, force_save=False):
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# Create a tempfile
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fd, tmp_path = tempfile.mkstemp()
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os.close(fd)
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try:
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if existing_data:
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self.write_data(existing_data, tmp_path, shred=False)
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# drop the user into an editor on the tmp file
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call(self._editor_shell_command(tmp_path))
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except:
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# whatever happens, destroy the decrypted file
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self._shred_file(tmp_path)
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raise
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b_tmpdata = self.read_data(tmp_path)
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# Do nothing if the content has not changed
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if existing_data == b_tmpdata and not force_save:
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self._shred_file(tmp_path)
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return
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# encrypt new data and write out to tmp
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# An existing vaultfile will always be UTF-8,
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# so decode to unicode here
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b_ciphertext = self.vault.encrypt(b_tmpdata)
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self.write_data(b_ciphertext, tmp_path)
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# shuffle tmp file into place
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self.shuffle_files(tmp_path, filename)
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def _real_path(self, filename):
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# '-' is special to VaultEditor, dont expand it.
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if filename == '-':
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return filename
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real_path = os.path.realpath(filename)
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return real_path
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def encrypt_bytes(self, b_plaintext):
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check_prereqs()
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b_ciphertext = self.vault.encrypt(b_plaintext)
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return b_ciphertext
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def encrypt_file(self, filename, output_file=None):
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check_prereqs()
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# A file to be encrypted into a vaultfile could be any encoding
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# so treat the contents as a byte string.
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# follow the symlink
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filename = self._real_path(filename)
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b_plaintext = self.read_data(filename)
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b_ciphertext = self.vault.encrypt(b_plaintext)
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self.write_data(b_ciphertext, output_file or filename)
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def decrypt_file(self, filename, output_file=None):
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check_prereqs()
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# follow the symlink
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filename = self._real_path(filename)
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ciphertext = self.read_data(filename)
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try:
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plaintext = self.vault.decrypt(ciphertext)
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except AnsibleError as e:
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raise AnsibleError("%s for %s" % (to_bytes(e),to_bytes(filename)))
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self.write_data(plaintext, output_file or filename, shred=False)
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def create_file(self, filename):
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""" create a new encrypted file """
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check_prereqs()
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# FIXME: If we can raise an error here, we can probably just make it
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# behave like edit instead.
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if os.path.isfile(filename):
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raise AnsibleError("%s exists, please use 'edit' instead" % filename)
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self._edit_file_helper(filename)
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def edit_file(self, filename):
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check_prereqs()
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# follow the symlink
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filename = self._real_path(filename)
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ciphertext = self.read_data(filename)
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try:
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plaintext = self.vault.decrypt(ciphertext)
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except AnsibleError as e:
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raise AnsibleError("%s for %s" % (to_bytes(e),to_bytes(filename)))
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if self.vault.cipher_name not in CIPHER_WRITE_WHITELIST:
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# we want to get rid of files encrypted with the AES cipher
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self._edit_file_helper(filename, existing_data=plaintext, force_save=True)
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else:
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self._edit_file_helper(filename, existing_data=plaintext, force_save=False)
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def plaintext(self, filename):
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check_prereqs()
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ciphertext = self.read_data(filename)
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try:
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plaintext = self.vault.decrypt(ciphertext)
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except AnsibleError as e:
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raise AnsibleError("%s for %s" % (to_bytes(e),to_bytes(filename)))
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return plaintext
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|
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def rekey_file(self, filename, b_new_password):
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check_prereqs()
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# follow the symlink
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filename = self._real_path(filename)
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prev = os.stat(filename)
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ciphertext = self.read_data(filename)
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try:
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plaintext = self.vault.decrypt(ciphertext)
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except AnsibleError as e:
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raise AnsibleError("%s for %s" % (to_bytes(e),to_bytes(filename)))
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|
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# This is more or less an assert, see #18247
|
|
if b_new_password is None:
|
|
raise AnsibleError('The value for the new_password to rekey %s with is not valid' % filename)
|
|
|
|
new_vault = VaultLib(b_new_password)
|
|
new_ciphertext = new_vault.encrypt(plaintext)
|
|
|
|
self.write_data(new_ciphertext, filename)
|
|
|
|
# preserve permissions
|
|
os.chmod(filename, prev.st_mode)
|
|
os.chown(filename, prev.st_uid, prev.st_gid)
|
|
|
|
def read_data(self, filename):
|
|
|
|
try:
|
|
if filename == '-':
|
|
data = sys.stdin.read()
|
|
else:
|
|
with open(filename, "rb") as fh:
|
|
data = fh.read()
|
|
except Exception as e:
|
|
raise AnsibleError(str(e))
|
|
|
|
return data
|
|
|
|
# TODO: add docstrings for arg types since this code is picky about that
|
|
def write_data(self, data, filename, shred=True):
|
|
"""Write the data bytes to given path
|
|
|
|
This is used to write a byte string to a file or stdout. It is used for
|
|
writing the results of vault encryption or decryption. It is used for
|
|
saving the ciphertext after encryption and it is also used for saving the
|
|
plaintext after decrypting a vault. The type of the 'data' arg should be bytes,
|
|
since in the plaintext case, the original contents can be of any text encoding
|
|
or arbitrary binary data.
|
|
|
|
When used to write the result of vault encryption, the val of the 'data' arg
|
|
should be a utf-8 encoded byte string and not a text typ and not a text type..
|
|
|
|
When used to write the result of vault decryption, the val of the 'data' arg
|
|
should be a byte string and not a text type.
|
|
|
|
:arg data: the byte string (bytes) data
|
|
:arg filename: filename to save 'data' to.
|
|
:arg shred: if shred==True, make sure that the original data is first shredded so that is cannot be recovered.
|
|
:returns: None
|
|
"""
|
|
# FIXME: do we need this now? data_bytes should always be a utf-8 byte string
|
|
b_file_data = to_bytes(data, errors='strict')
|
|
|
|
# get a ref to either sys.stdout.buffer for py3 or plain old sys.stdout for py2
|
|
# We need sys.stdout.buffer on py3 so we can write bytes to it since the plaintext
|
|
# of the vaulted object could be anything/binary/etc
|
|
output = getattr(sys.stdout, 'buffer', sys.stdout)
|
|
|
|
if filename == '-':
|
|
output.write(b_file_data)
|
|
else:
|
|
if os.path.isfile(filename):
|
|
if shred:
|
|
self._shred_file(filename)
|
|
else:
|
|
os.remove(filename)
|
|
with open(filename, "wb") as fh:
|
|
fh.write(b_file_data)
|
|
|
|
def shuffle_files(self, src, dest):
|
|
prev = None
|
|
# overwrite dest with src
|
|
if os.path.isfile(dest):
|
|
prev = os.stat(dest)
|
|
# old file 'dest' was encrypted, no need to _shred_file
|
|
os.remove(dest)
|
|
shutil.move(src, dest)
|
|
|
|
# reset permissions if needed
|
|
if prev is not None:
|
|
# TODO: selinux, ACLs, xattr?
|
|
os.chmod(dest, prev.st_mode)
|
|
os.chown(dest, prev.st_uid, prev.st_gid)
|
|
|
|
def _editor_shell_command(self, filename):
|
|
EDITOR = os.environ.get('EDITOR','vi')
|
|
editor = shlex.split(EDITOR)
|
|
editor.append(filename)
|
|
|
|
return editor
|
|
|
|
|
|
########################################
|
|
# CIPHERS #
|
|
########################################
|
|
|
|
class VaultAES:
|
|
|
|
# this version has been obsoleted by the VaultAES256 class
|
|
# which uses encrypt-then-mac (fixing order) and also improving the KDF used
|
|
# code remains for upgrade purposes only
|
|
# http://stackoverflow.com/a/16761459
|
|
|
|
# Note: strings in this class should be byte strings by default.
|
|
|
|
def __init__(self):
|
|
if not HAS_AES:
|
|
raise AnsibleError(CRYPTO_UPGRADE)
|
|
|
|
def _aes_derive_key_and_iv(self, b_password, b_salt, key_length, iv_length):
|
|
|
|
""" Create a key and an initialization vector """
|
|
|
|
b_d = b_di = b''
|
|
while len(b_d) < key_length + iv_length:
|
|
b_text = b''.join([b_di, b_password, b_salt])
|
|
b_di = to_bytes(md5(b_text).digest(), errors='strict')
|
|
b_d += b_di
|
|
|
|
b_key = b_d[:key_length]
|
|
b_iv = b_d[key_length:key_length+iv_length]
|
|
|
|
return b_key, b_iv
|
|
|
|
def encrypt(self, b_plaintext, b_password, key_length=32):
|
|
|
|
""" Read plaintext data from in_file and write encrypted to out_file """
|
|
|
|
raise AnsibleError("Encryption disabled for deprecated VaultAES class")
|
|
|
|
def decrypt(self, b_vaulttext, b_password, key_length=32):
|
|
|
|
""" Decrypt the given data and return it
|
|
:arg b_data: A byte string containing the encrypted data
|
|
:arg b_password: A byte string containing the encryption password
|
|
:arg key_length: Length of the key
|
|
:returns: A byte string containing the decrypted data
|
|
"""
|
|
|
|
display.deprecated(u'The VaultAES format is insecure and has been'
|
|
' deprecated since Ansible-1.5. Use vault rekey FILENAME to'
|
|
' switch to the newer VaultAES256 format', version='2.3')
|
|
# http://stackoverflow.com/a/14989032
|
|
|
|
b_ciphertext = unhexlify(b_vaulttext)
|
|
|
|
in_file = BytesIO(b_ciphertext)
|
|
in_file.seek(0)
|
|
out_file = BytesIO()
|
|
|
|
bs = AES.block_size
|
|
b_tmpsalt = in_file.read(bs)
|
|
b_salt = b_tmpsalt[len(b'Salted__'):]
|
|
b_key, b_iv = self._aes_derive_key_and_iv(b_password, b_salt, key_length, bs)
|
|
cipher = AES.new(b_key, AES.MODE_CBC, b_iv)
|
|
b_next_chunk = b''
|
|
finished = False
|
|
|
|
while not finished:
|
|
b_chunk, b_next_chunk = b_next_chunk, cipher.decrypt(in_file.read(1024 * bs))
|
|
if len(b_next_chunk) == 0:
|
|
if PY3:
|
|
padding_length = b_chunk[-1]
|
|
else:
|
|
padding_length = ord(b_chunk[-1])
|
|
|
|
b_chunk = b_chunk[:-padding_length]
|
|
finished = True
|
|
|
|
out_file.write(b_chunk)
|
|
out_file.flush()
|
|
|
|
# reset the stream pointer to the beginning
|
|
out_file.seek(0)
|
|
b_out_data = out_file.read()
|
|
out_file.close()
|
|
|
|
# split out sha and verify decryption
|
|
b_split_data = b_out_data.split(b"\n", 1)
|
|
b_this_sha = b_split_data[0]
|
|
b_plaintext = b_split_data[1]
|
|
b_test_sha = to_bytes(sha256(b_plaintext).hexdigest())
|
|
|
|
if b_this_sha != b_test_sha:
|
|
raise AnsibleError("Decryption failed")
|
|
|
|
return b_plaintext
|
|
|
|
|
|
class VaultAES256:
|
|
|
|
"""
|
|
Vault implementation using AES-CTR with an HMAC-SHA256 authentication code.
|
|
Keys are derived using PBKDF2
|
|
"""
|
|
|
|
# http://www.daemonology.net/blog/2009-06-11-cryptographic-right-answers.html
|
|
|
|
# Note: strings in this class should be byte strings by default.
|
|
|
|
def __init__(self):
|
|
|
|
check_prereqs()
|
|
|
|
@staticmethod
|
|
def _create_key(b_password, b_salt, keylength, ivlength):
|
|
hash_function = SHA256
|
|
|
|
# make two keys and one iv
|
|
pbkdf2_prf = lambda p, s: HMAC.new(p, s, hash_function).digest()
|
|
|
|
b_derivedkey = PBKDF2(b_password, b_salt, dkLen=(2 * keylength) + ivlength,
|
|
count=10000, prf=pbkdf2_prf)
|
|
return b_derivedkey
|
|
|
|
@classmethod
|
|
def _gen_key_initctr(cls, b_password, b_salt):
|
|
# 16 for AES 128, 32 for AES256
|
|
keylength = 32
|
|
|
|
# match the size used for counter.new to avoid extra work
|
|
ivlength = 16
|
|
|
|
if HAS_PBKDF2HMAC:
|
|
backend = default_backend()
|
|
kdf = PBKDF2HMAC(
|
|
algorithm=c_SHA256(),
|
|
length=2 * keylength + ivlength,
|
|
salt=b_salt,
|
|
iterations=10000,
|
|
backend=backend)
|
|
b_derivedkey = kdf.derive(b_password)
|
|
else:
|
|
b_derivedkey = cls._create_key(b_password, b_salt, keylength, ivlength)
|
|
|
|
b_key1 = b_derivedkey[:keylength]
|
|
b_key2 = b_derivedkey[keylength:(keylength * 2)]
|
|
b_iv = b_derivedkey[(keylength * 2):(keylength * 2) + ivlength]
|
|
|
|
return b_key1, b_key2, hexlify(b_iv)
|
|
|
|
def encrypt(self, b_plaintext, b_password):
|
|
b_salt = os.urandom(32)
|
|
b_key1, b_key2, b_iv = self._gen_key_initctr(b_password, b_salt)
|
|
|
|
# PKCS#7 PAD DATA http://tools.ietf.org/html/rfc5652#section-6.3
|
|
bs = AES.block_size
|
|
padding_length = (bs - len(b_plaintext) % bs) or bs
|
|
b_plaintext += to_bytes(padding_length * chr(padding_length), encoding='ascii', errors='strict')
|
|
|
|
# COUNTER.new PARAMETERS
|
|
# 1) nbits (integer) - Length of the counter, in bits.
|
|
# 2) initial_value (integer) - initial value of the counter. "iv" from _gen_key_initctr
|
|
|
|
ctr = Counter.new(128, initial_value=int(b_iv, 16))
|
|
|
|
# AES.new PARAMETERS
|
|
# 1) AES key, must be either 16, 24, or 32 bytes long -- "key" from _gen_key_initctr
|
|
# 2) MODE_CTR, is the recommended mode
|
|
# 3) counter=<CounterObject>
|
|
|
|
cipher = AES.new(b_key1, AES.MODE_CTR, counter=ctr)
|
|
|
|
# ENCRYPT PADDED DATA
|
|
b_ciphertext = cipher.encrypt(b_plaintext)
|
|
|
|
# COMBINE SALT, DIGEST AND DATA
|
|
hmac = HMAC.new(b_key2, b_ciphertext, SHA256)
|
|
b_vaulttext = b'\n'.join([hexlify(b_salt), to_bytes(hmac.hexdigest()), hexlify(b_ciphertext)])
|
|
b_vaulttext = hexlify(b_vaulttext)
|
|
return b_vaulttext
|
|
|
|
def decrypt(self, b_vaulttext, b_password):
|
|
# SPLIT SALT, DIGEST, AND DATA
|
|
b_vaulttext = unhexlify(b_vaulttext)
|
|
b_salt, b_cryptedHmac, b_ciphertext = b_vaulttext.split(b"\n", 2)
|
|
b_salt = unhexlify(b_salt)
|
|
b_ciphertext = unhexlify(b_ciphertext)
|
|
b_key1, b_key2, b_iv = self._gen_key_initctr(b_password, b_salt)
|
|
|
|
# EXIT EARLY IF DIGEST DOESN'T MATCH
|
|
hmacDecrypt = HMAC.new(b_key2, b_ciphertext, SHA256)
|
|
if not self._is_equal(b_cryptedHmac, to_bytes(hmacDecrypt.hexdigest())):
|
|
return None
|
|
# SET THE COUNTER AND THE CIPHER
|
|
ctr = Counter.new(128, initial_value=int(b_iv, 16))
|
|
cipher = AES.new(b_key1, AES.MODE_CTR, counter=ctr)
|
|
|
|
# DECRYPT PADDED DATA
|
|
b_plaintext = cipher.decrypt(b_ciphertext)
|
|
|
|
# UNPAD DATA
|
|
if PY3:
|
|
padding_length = b_plaintext[-1]
|
|
else:
|
|
padding_length = ord(b_plaintext[-1])
|
|
|
|
b_plaintext = b_plaintext[:-padding_length]
|
|
return b_plaintext
|
|
|
|
@staticmethod
|
|
def _is_equal(b_a, b_b):
|
|
"""
|
|
Comparing 2 byte arrrays in constant time
|
|
to avoid timing attacks.
|
|
|
|
It would be nice if there was a library for this but
|
|
hey.
|
|
"""
|
|
if not (isinstance(b_a, binary_type) and isinstance(b_b, binary_type)):
|
|
raise TypeError('_is_equal can only be used to compare two byte strings')
|
|
|
|
# http://codahale.com/a-lesson-in-timing-attacks/
|
|
if len(b_a) != len(b_b):
|
|
return False
|
|
|
|
result = 0
|
|
for b_x, b_y in zip(b_a, b_b):
|
|
if PY3:
|
|
result |= b_x ^ b_y
|
|
else:
|
|
result |= ord(b_x) ^ ord(b_y)
|
|
return result == 0
|
|
|
|
|
|
# Keys could be made bytes later if the code that gets the data is more
|
|
# naturally byte-oriented
|
|
CIPHER_MAPPING = {
|
|
u'AES': VaultAES,
|
|
u'AES256': VaultAES256,
|
|
}
|