VMM/password: Added function extract_scheme().
# -*- coding: UTF-8 -*-
# Copyright (c) 2010 - 2014, Pascal Volk
# See COPYING for distribution information.
"""
VirtualMailManager.password
~~~~~~~~~~~~~~~~~~~~~~~~~~~
VirtualMailManager's password module to generate password hashes from
passwords or random passwords. This module provides following
functions:
hashed_password = pwhash(password[, scheme][, user])
random_password = randompw()
scheme, encoding = verify_scheme(scheme)
schemes, encodings = list_schemes()
scheme = extract_scheme(hashed_password)
"""
import hashlib
import re
from base64 import b64encode
from binascii import b2a_hex
from crypt import crypt
from random import SystemRandom
from subprocess import Popen, PIPE
from VirtualMailManager import ENCODING
from VirtualMailManager.emailaddress import EmailAddress
from VirtualMailManager.common import get_unicode, version_str
from VirtualMailManager.constants import VMM_ERROR
from VirtualMailManager.errors import VMMError
SALTCHARS = './0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
PASSWDCHARS = '._-+#*23456789abcdefghikmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ'
DEFAULT_B64 = (None, 'B64', 'BASE64')
DEFAULT_HEX = (None, 'HEX')
CRYPT_ID_MD5 = 1
CRYPT_ID_BLF = '2a'
CRYPT_ID_SHA256 = 5
CRYPT_ID_SHA512 = 6
CRYPT_SALT_LEN = 2
CRYPT_BLF_ROUNDS_MIN = 4
CRYPT_BLF_ROUNDS_MAX = 31
CRYPT_BLF_SALT_LEN = 22
CRYPT_MD5_SALT_LEN = 8
CRYPT_SHA2_ROUNDS_DEFAULT = 5000
CRYPT_SHA2_ROUNDS_MIN = 1000
CRYPT_SHA2_ROUNDS_MAX = 999999999
CRYPT_SHA2_SALT_LEN = 16
SALTED_ALGO_SALT_LEN = 4
_ = lambda msg: msg
cfg_dget = lambda option: None
_sys_rand = SystemRandom()
_choice = _sys_rand.choice
_get_salt = lambda s_len: ''.join(_choice(SALTCHARS) for x in range(s_len))
def _doveadmpw(password, scheme, encoding):
"""Communicates with Dovecot's doveadm and returns
the hashed password: {scheme[.encoding]}hash
"""
if encoding:
scheme = '.'.join((scheme, encoding))
cmd_args = [cfg_dget('bin.doveadm'), 'pw', '-s', scheme, '-p',
get_unicode(password)]
process = Popen(cmd_args, stdout=PIPE, stderr=PIPE)
stdout, stderr = process.communicate()
if process.returncode:
raise VMMError(stderr.strip().decode(ENCODING), VMM_ERROR)
hashed = stdout.strip().decode(ENCODING)
if not hashed.startswith('{%s}' % scheme):
raise VMMError('Unexpected result from %s: %s' %
(cfg_dget('bin.doveadm'), hashed), VMM_ERROR)
return hashed
def _md4_new():
"""Returns an new MD4-hash object if supported by the hashlib -
otherwise `None`.
"""
try:
return hashlib.new('md4')
except ValueError as err:
if err.args[0].startswith('unsupported hash type'):
return None
else:
raise
def _format_digest(digest, scheme, encoding):
"""Formats the arguments to a string: {scheme[.encoding]}digest."""
if not encoding:
return '{%s}%s' % (scheme, digest)
return '{%s.%s}%s' % (scheme, encoding, digest)
def _clear_hash(password, scheme, encoding):
"""Generates a (encoded) CLEARTEXT/PLAIN 'hash'."""
password = password.decode(ENCODING)
if encoding:
if encoding == 'HEX':
password = b2a_hex(password.encode()).decode()
else:
password = b64encode(password.encode()).decode()
return _format_digest(password, scheme, encoding)
return '{%s}%s' % (scheme, password)
def _get_crypt_blowfish_salt():
"""Generates a salt for Blowfish crypt."""
rounds = cfg_dget('misc.crypt_blowfish_rounds')
if rounds < CRYPT_BLF_ROUNDS_MIN:
rounds = CRYPT_BLF_ROUNDS_MIN
elif rounds > CRYPT_BLF_ROUNDS_MAX:
rounds = CRYPT_BLF_ROUNDS_MAX
return '$%s$%02d$%s' % (CRYPT_ID_BLF, rounds,
_get_salt(CRYPT_BLF_SALT_LEN))
def _get_crypt_sha2_salt(crypt_id):
"""Generates a salt for crypt using the SHA-256 or SHA-512 encryption
method.
*crypt_id* must be either `5` (SHA-256) or `6` (SHA-512).
"""
assert crypt_id in (CRYPT_ID_SHA256, CRYPT_ID_SHA512), 'invalid crypt ' \
'id: %r' % crypt_id
if crypt_id is CRYPT_ID_SHA512:
rounds = cfg_dget('misc.crypt_sha512_rounds')
else:
rounds = cfg_dget('misc.crypt_sha256_rounds')
if rounds < CRYPT_SHA2_ROUNDS_MIN:
rounds = CRYPT_SHA2_ROUNDS_MIN
elif rounds > CRYPT_SHA2_ROUNDS_MAX:
rounds = CRYPT_SHA2_ROUNDS_MAX
if rounds == CRYPT_SHA2_ROUNDS_DEFAULT:
return '$%d$%s' % (crypt_id, _get_salt(CRYPT_SHA2_SALT_LEN))
return '$%d$rounds=%d$%s' % (crypt_id, rounds,
_get_salt(CRYPT_SHA2_SALT_LEN))
def _crypt_hash(password, scheme, encoding):
"""Generates (encoded) CRYPT/MD5/{BLF,MD5,SHA{256,512}}-CRYPT hashes."""
if scheme == 'CRYPT':
salt = _get_salt(CRYPT_SALT_LEN)
elif scheme == 'BLF-CRYPT':
salt = _get_crypt_blowfish_salt()
elif scheme in ('MD5-CRYPT', 'MD5'):
salt = '$%d$%s' % (CRYPT_ID_MD5, _get_salt(CRYPT_MD5_SALT_LEN))
elif scheme == 'SHA256-CRYPT':
salt = _get_crypt_sha2_salt(CRYPT_ID_SHA256)
else:
salt = _get_crypt_sha2_salt(CRYPT_ID_SHA512)
encrypted = crypt(password.decode(ENCODING), salt)
if encoding:
if encoding == 'HEX':
encrypted = b2a_hex(encrypted.encode()).decode()
else:
encrypted = b64encode(encrypted.encode()).decode()
return _format_digest(encrypted, scheme, encoding)
def _md4_hash(password, scheme, encoding):
"""Generates encoded PLAIN-MD4 hashes."""
md4 = _md4_new()
if md4:
md4.update(password)
if encoding in DEFAULT_HEX:
digest = md4.hexdigest()
else:
digest = b64encode(md4.digest()).decode()
return _format_digest(digest, scheme, encoding)
return _doveadmpw(password, scheme, encoding)
def _md5_hash(password, scheme, encoding, user=None):
"""Generates DIGEST-MD5 aka PLAIN-MD5 and LDAP-MD5 hashes."""
md5 = hashlib.md5()
if scheme == 'DIGEST-MD5':
md5.update(user.localpart.encode() + b':' +
user.domainname.encode() + b':')
md5.update(password)
if (scheme in ('PLAIN-MD5', 'DIGEST-MD5') and encoding in DEFAULT_HEX) or \
(scheme == 'LDAP-MD5' and encoding == 'HEX'):
digest = md5.hexdigest()
else:
digest = b64encode(md5.digest()).decode()
return _format_digest(digest, scheme, encoding)
def _ntlm_hash(password, scheme, encoding):
"""Generates NTLM hashes."""
md4 = _md4_new()
if md4:
password = b''.join(bytes(x)
for x in zip(password, bytes(len(password))))
md4.update(password)
if encoding in DEFAULT_HEX:
digest = md4.hexdigest()
else:
digest = b64encode(md4.digest()).decode()
return _format_digest(digest, scheme, encoding)
return _doveadmpw(password, scheme, encoding)
def _sha1_hash(password, scheme, encoding):
"""Generates SHA1 aka SHA hashes."""
sha1 = hashlib.sha1(password)
if encoding in DEFAULT_B64:
digest = b64encode(sha1.digest()).decode()
else:
digest = sha1.hexdigest()
return _format_digest(digest, scheme, encoding)
def _sha256_hash(password, scheme, encoding):
"""Generates SHA256 hashes."""
sha256 = hashlib.sha256(password)
if encoding in DEFAULT_B64:
digest = b64encode(sha256.digest()).decode()
else:
digest = sha256.hexdigest()
return _format_digest(digest, scheme, encoding)
def _sha512_hash(password, scheme, encoding):
"""Generates SHA512 hashes."""
sha512 = hashlib.sha512(password)
if encoding in DEFAULT_B64:
digest = b64encode(sha512.digest()).decode()
else:
digest = sha512.hexdigest()
return _format_digest(digest, scheme, encoding)
def _smd5_hash(password, scheme, encoding):
"""Generates SMD5 (salted PLAIN-MD5) hashes."""
md5 = hashlib.md5(password)
salt = _get_salt(SALTED_ALGO_SALT_LEN).encode()
md5.update(salt)
if encoding in DEFAULT_B64:
digest = b64encode(md5.digest() + salt).decode()
else:
digest = md5.hexdigest() + b2a_hex(salt).decode()
return _format_digest(digest, scheme, encoding)
def _ssha1_hash(password, scheme, encoding):
"""Generates SSHA (salted SHA/SHA1) hashes."""
sha1 = hashlib.sha1(password)
salt = _get_salt(SALTED_ALGO_SALT_LEN).encode()
sha1.update(salt)
if encoding in DEFAULT_B64:
digest = b64encode(sha1.digest() + salt).decode()
else:
digest = sha1.hexdigest() + b2a_hex(salt).decode()
return _format_digest(digest, scheme, encoding)
def _ssha256_hash(password, scheme, encoding):
"""Generates SSHA256 (salted SHA256) hashes."""
sha256 = hashlib.sha256(password)
salt = _get_salt(SALTED_ALGO_SALT_LEN).encode()
sha256.update(salt)
if encoding in DEFAULT_B64:
digest = b64encode(sha256.digest() + salt).decode()
else:
digest = sha256.hexdigest() + b2a_hex(salt).decode()
return _format_digest(digest, scheme, encoding)
def _ssha512_hash(password, scheme, encoding):
"""Generates SSHA512 (salted SHA512) hashes."""
salt = _get_salt(SALTED_ALGO_SALT_LEN).encode()
sha512 = hashlib.sha512(password + salt)
if encoding in DEFAULT_B64:
digest = b64encode(sha512.digest() + salt).decode()
else:
digest = sha512.hexdigest() + b2a_hex(salt).decode()
return _format_digest(digest, scheme, encoding)
_scheme_info = {
'CLEAR': (_clear_hash, 0x2010df00),
'CLEARTEXT': (_clear_hash, 0x10000f00),
'CRAM-MD5': (_doveadmpw, 0x10000f00),
'CRYPT': (_crypt_hash, 0x10000f00),
'DIGEST-MD5': (_md5_hash, 0x10000f00),
'HMAC-MD5': (_doveadmpw, 0x10000f00),
'LANMAN': (_doveadmpw, 0x10000f00),
'LDAP-MD5': (_md5_hash, 0x10000f00),
'MD5': (_crypt_hash, 0x10000f00),
'MD5-CRYPT': (_crypt_hash, 0x10000f00),
'NTLM': (_ntlm_hash, 0x10000f00),
'OTP': (_doveadmpw, 0x10100a01),
'PLAIN': (_clear_hash, 0x10000f00),
'PLAIN-MD4': (_md4_hash, 0x10000f00),
'PLAIN-MD5': (_md5_hash, 0x10000f00),
'RPA': (_doveadmpw, 0x10000f00),
'SCRAM-SHA-1': (_doveadmpw, 0x20200a01),
'SHA': (_sha1_hash, 0x10000f00),
'SHA1': (_sha1_hash, 0x10000f00),
'SHA256': (_sha256_hash, 0x10100a01),
'SHA512': (_sha512_hash, 0x20000b03),
'SKEY': (_doveadmpw, 0x10100a01),
'SMD5': (_smd5_hash, 0x10000f00),
'SSHA': (_ssha1_hash, 0x10000f00),
'SSHA256': (_ssha256_hash, 0x10200a04),
'SSHA512': (_ssha512_hash, 0x20000b03),
}
def extract_scheme(password_hash):
"""Returns the extracted password scheme from *password_hash*.
If the scheme couldn't be extracted, **None** will be returned.
"""
scheme = re.match(r'^\{([^\}]{3,37})\}', password_hash)
if scheme:
return scheme.groups()[0]
return scheme
def list_schemes():
"""Returns the tuple (schemes, encodings).
`schemes` is an iterator for all supported password schemes (depends on
the used Dovecot version and features of the libc).
`encodings` is a tuple with all usable encoding suffixes.
"""
dcv = cfg_dget('misc.dovecot_version')
schemes = (k for (k, v) in _scheme_info.items() if v[1] <= dcv)
encodings = ('.B64', '.BASE64', '.HEX')
return schemes, encodings
def verify_scheme(scheme):
"""Checks if the password scheme *scheme* is known and supported by the
configured `misc.dovecot_version`.
The *scheme* maybe a password scheme's name (e.g.: 'PLAIN') or a scheme
name with a encoding suffix (e.g. 'PLAIN.BASE64'). If the scheme is
known and supported by the used Dovecot version,
a tuple ``(scheme, encoding)`` will be returned.
The `encoding` in the tuple may be `None`.
Raises a `VMMError` if the password scheme:
* is unknown
* depends on a newer Dovecot version
* has a unknown encoding suffix
"""
assert isinstance(scheme, str), 'Not a str: {!r}'.format(scheme)
scheme_encoding = scheme.upper().split('.')
scheme = scheme_encoding[0]
if scheme not in _scheme_info:
raise VMMError(_("Unsupported password scheme: '%s'") % scheme,
VMM_ERROR)
if cfg_dget('misc.dovecot_version') < _scheme_info[scheme][1]:
raise VMMError(_("The password scheme '%(scheme)s' requires Dovecot "
">= v%(version)s.") % {'scheme': scheme,
'version': version_str(_scheme_info[scheme][1])},
VMM_ERROR)
if len(scheme_encoding) > 1:
if scheme_encoding[1] not in ('B64', 'BASE64', 'HEX'):
raise VMMError(_("Unsupported password encoding: '%s'") %
scheme_encoding[1], VMM_ERROR)
encoding = scheme_encoding[1]
else:
encoding = None
return scheme, encoding
def pwhash(password, scheme=None, user=None):
"""Generates a password hash from the plain text *password* string.
If no *scheme* is given the password scheme from the configuration will
be used for the hash generation. When 'DIGEST-MD5' is used as scheme,
also an EmailAddress instance must be given as *user* argument.
"""
if not isinstance(password, str):
raise TypeError('Password is not a string: %r' % password)
password = password.encode(ENCODING).strip()
if not password:
raise ValueError("Could not accept empty password.")
if scheme is None:
scheme = cfg_dget('misc.password_scheme')
scheme, encoding = verify_scheme(scheme)
if scheme == 'DIGEST-MD5':
assert isinstance(user, EmailAddress)
return _md5_hash(password, scheme, encoding, user)
return _scheme_info[scheme][0](password, scheme, encoding)
def randompw():
"""Generates a plain text random password.
The length of the password can be configured in the ``vmm.cfg``
(account.password_length).
"""
pw_len = cfg_dget('account.password_length')
if pw_len < 8:
pw_len = 8
return ''.join(_sys_rand.sample(PASSWDCHARS, pw_len))
def _test_crypt_algorithms():
"""Check for Blowfish/SHA-256/SHA-512 support in crypt.crypt()."""
_blowfish = '$2a$04$0123456789abcdefABCDE.N.drYX5yIAL1LkTaaZotW3yI0hQhZru'
_sha256 = '$5$rounds=1000$0123456789abcdef$K/DksR0DT01hGc8g/kt9McEgrbFMKi\
9qrb1jehe7hn4'
_sha512 = '$6$rounds=1000$0123456789abcdef$ZIAd5WqfyLkpvsVCVUU1GrvqaZTqvh\
JoouxdSqJO71l9Ld3tVrfOatEjarhghvEYADkq//LpDnTeO90tcbtHR1'
if crypt('08/15!test~4711', '$2a$04$0123456789abcdefABCDEF$') == _blowfish:
_scheme_info['BLF-CRYPT'] = (_crypt_hash, 0x20000b06)
if crypt('08/15!test~4711', '$5$rounds=1000$0123456789abcdef$') == _sha256:
_scheme_info['SHA256-CRYPT'] = (_crypt_hash, 0x20000b06)
if crypt('08/15!test~4711', '$6$rounds=1000$0123456789abcdef$') == _sha512:
_scheme_info['SHA512-CRYPT'] = (_crypt_hash, 0x20000b06)
_test_crypt_algorithms()
del _, cfg_dget, _test_crypt_algorithms