aif-ng/aif/disk/luks.py

244 lines
10 KiB
Python

import logging
import os
import secrets
import uuid
##
from lxml import etree
##
from . import _common
import aif.disk.block as block
import aif.disk.lvm as lvm
import aif.disk.mdadm as mdadm
_logger = logging.getLogger(__name__)
_BlockDev = _common.BlockDev
class LuksSecret(object):
def __init__(self, *args, **kwargs):
_common.addBDPlugin('crypto')
self.passphrase = None
self.size = 4096
self.path = None
_logger.info('Instantiated {0}.'.format(type(self).__name__))
class LuksSecretPassphrase(LuksSecret):
def __init__(self, passphrase):
super().__init__()
self.passphrase = passphrase
class LuksSecretFile(LuksSecret):
# TODO: might do a little tweaking in a later release to support *reading from* bytes.
def __init__(self, path, passphrase = None, bytesize = 4096):
super().__init__()
self.path = os.path.abspath(os.path.expanduser(path))
_logger.debug('Path canonized: {0} => {1}'.format(path, self.path))
self.passphrase = passphrase
self.size = bytesize # only used if passphrase == None
self._genSecret()
def _genSecret(self):
if not self.passphrase:
# TODO: is secrets.token_bytes safe for *persistent* random data?
self.passphrase = secrets.token_bytes(self.size)
if not isinstance(self.passphrase, bytes):
self.passphrase = self.passphrase.encode('utf-8')
_logger.debug('Secret generated.')
return(None)
class LUKS(object):
def __init__(self, luks_xml, partobj):
self.xml = luks_xml
_logger.debug('luks_xml: {0}'.format(etree.tostring(self.xml, with_tail = False).decode('utf-8')))
self.id = self.xml.attrib['id']
self.name = self.xml.attrib['name']
self.device = partobj
self.source = self.device.devpath
self.secrets = []
self.created = False
self.locked = True
if not isinstance(self.device, (block.Disk,
block.Partition,
lvm.LV,
mdadm.Array)):
_logger.error(('partobj must be of type '
'aif.disk.block.Disk, '
'aif.disk.block.Partition, '
'aif.disk.lvm.LV, or'
'aif.disk.mdadm.Array.'))
raise ValueError('Invalid partobj type')
_common.addBDPlugin('crypto')
self.devpath = '/dev/mapper/{0}'.format(self.name)
self.info = None
def addSecret(self, secretobj):
if not isinstance(secretobj, LuksSecret):
_logger.error('secretobj must be of type '
'aif.disk.luks.LuksSecret '
'(aif.disk.luks.LuksSecretPassphrase or '
'aif.disk.luks.LuksSecretFile).')
raise ValueError('Invalid secretobj type')
self.secrets.append(secretobj)
return(None)
def createSecret(self, secrets_xml = None):
_logger.info('Compiling secrets.')
if not secrets_xml: # Find all of them from self
_logger.debug('No secrets_xml specified; fetching from configuration block.')
for secret_xml in self.xml.findall('secrets'):
_logger.debug('secret_xml: {0}'.format(etree.tostring(secret_xml, with_tail = False).decode('utf-8')))
secretobj = None
secrettypes = set()
for s in secret_xml.iterchildren():
_logger.debug('secret_xml child: {0}'.format(etree.tostring(s, with_tail = False).decode('utf-8')))
secrettypes.add(s.tag)
if all((('passphrase' in secrettypes),
('keyFile' in secrettypes))):
# This is safe, because a valid config only has at most one of both types.
kf = secret_xml.find('keyFile')
secretobj = LuksSecretFile(kf.text, # path
passphrase = secret_xml.find('passphrase').text,
bytesize = kf.attrib.get('size', 4096)) # TECHNICALLY should be a no-op.
elif 'passphrase' in secrettypes:
secretobj = LuksSecretPassphrase(secret_xml.find('passphrase').text)
elif 'keyFile' in secrettypes:
kf = secret_xml.find('keyFile')
secretobj = LuksSecretFile(kf.text,
passphrase = None,
bytesize = kf.attrib.get('size', 4096))
self.secrets.append(secretobj)
else:
_logger.debug('A secrets_xml was specified.')
secretobj = None
secrettypes = set()
for s in secrets_xml.iterchildren():
_logger.debug('secrets_xml child: {0}'.format(etree.tostring(s, with_tail = False).decode('utf-8')))
secrettypes.add(s.tag)
if all((('passphrase' in secrettypes),
('keyFile' in secrettypes))):
# This is safe because a valid config only has at most one of both types.
kf = secrets_xml.find('keyFile')
secretobj = LuksSecretFile(kf.text, # path
passphrase = secrets_xml.find('passphrase').text,
bytesize = kf.attrib.get('size', 4096)) # TECHNICALLY should be a no-op.
elif 'passphrase' in secrettypes:
secretobj = LuksSecretPassphrase(secrets_xml.find('passphrase').text)
elif 'keyFile' in secrettypes:
kf = secrets_xml.find('keyFile')
secretobj = LuksSecretFile(kf.text,
passphrase = None,
bytesize = kf.attrib.get('size', 4096))
self.secrets.append(secretobj)
_logger.debug('Secrets compiled.')
return(None)
def create(self):
if self.created:
return(None)
_logger.info('Creating LUKS volume on {0}'.format(self.source))
if not self.secrets:
_logger.error('Cannot create a LUKS volume with no secrets added.')
raise RuntimeError('Cannot create a LUKS volume with no secrets')
for idx, secret in enumerate(self.secrets):
if idx == 0:
# TODO: add support for custom parameters for below?
_BlockDev.crypto.luks_format_luks2_blob(self.source,
None, # cipher (use default)
0, # keysize (use default)
secret.passphrase, # passphrase
0, # minimum entropy (use default)
_BlockDev.CryptoLUKSVersion.LUKS2, # LUKS version
None) # extra args
else:
_BlockDev.crypto.luks_add_key_blob(self.source,
self.secrets[0].passphrase,
secret.passphrase)
self.created = True
_logger.debug('Created LUKS volume.')
return(None)
def lock(self):
_logger.info('Locking: {0}'.format(self.source))
if not self.created:
_logger.error('Cannot lock a LUKS volume that does not exist yet.')
raise RuntimeError('Cannot lock non-existent volume')
if self.locked:
return(None)
_BlockDev.crypto.luks_close(self.name)
self.locked = True
_logger.debug('Locked.')
return(None)
def unlock(self, passphrase = None):
_logger.info('Unlocking: {0}'.format(self.source))
if not self.created:
_logger.error('Cannot unlock a LUKS volume that does not exist yet.')
raise RuntimeError('Cannot unlock non-existent volume')
if not self.locked:
return(None)
_BlockDev.crypto.luks_open_blob(self.source,
self.name,
self.secrets[0].passphrase,
False) # read-only
self.locked = False
_logger.debug('Unlocked.')
return(None)
def updateInfo(self):
_logger.info('Updating info.')
if self.locked:
_logger.error('Tried to fetch metadata about a locked volume. A volume must be unlocked first.')
raise RuntimeError('Must be unlocked to gather info')
info = {}
_info = _BlockDev.crypto.luks_info(self.devpath)
for k in dir(_info):
if k.startswith('_'):
continue
elif k in ('copy', ):
continue
v = getattr(_info, k)
if k == 'uuid':
v = uuid.UUID(hex = v)
info[k] = v
info['_cipher'] = '{cipher}-{mode}'.format(**info)
self.info = info
_logger.debug('Rendered updated info: {0}'.format(info))
return(None)
def writeConf(self, chroot_base, init_hook = True):
_logger.info('Generating crypttab.')
if not self.secrets:
_logger.error('Secrets must be added before the configuration can be written.')
raise RuntimeError('Missing secrets')
conf = os.path.join(chroot_base, 'etc', 'crypttab')
initconf = '{0}.initramfs'.format(conf)
with open(conf, 'r') as fh:
conflines = fh.read().splitlines()
# Get UUID
disk_uuid = None
uuid_dir = '/dev/disk/by-uuid'
for u in os.listdir(uuid_dir):
d = os.path.join(uuid_dir, u)
if os.path.realpath(d) == self.source:
disk_uuid = u
if disk_uuid:
identifer = 'UUID={0}'.format(disk_uuid)
else:
# This is *not* ideal, but better than nothing.
identifer = self.source
primary_key = self.secrets[0]
luksinfo = '{0}\t{1}\t{2}\tluks'.format(self.name,
identifer,
(primary_key.path if primary_key.path else '-'))
if luksinfo not in conflines:
with open(conf, 'a') as fh:
fh.write('{0}\n'.format(luksinfo))
_logger.debug('Generated crypttab line: {0}'.format(luksinfo))
return(None)