aif-ng/aif/disk/luks_fallback.py

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import os
import re
import secrets
import subprocess
import tempfile
import uuid
##
import parse
##
import aif.disk.block_fallback as block
import aif.disk.lvm_fallback as lvm
import aif.disk.mdadm_fallback as mdadm
class LuksSecret(object):
def __init__(self, *args, **kwargs):
self.passphrase = None
self.size = 4096
self.path = None
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.realpath(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')
return()
class LUKS(object):
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def __init__(self, luks_xml, partobj):
self.xml = luks_xml
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)):
raise ValueError(('partobj must be of type '
'aif.disk.block.Disk, '
'aif.disk.block.Partition, '
'aif.disk.lvm.LV, or'
'aif.disk.mdadm.Array'))
self.devpath = '/dev/mapper/{0}'.format(self.name)
self.info = None
def addSecret(self, secretobj):
if not isinstance(secretobj, LuksSecret):
raise ValueError('secretobj must be of type aif.disk.luks.LuksSecret '
'(aif.disk.luks.LuksSecretPassphrase or '
'aif.disk.luks.LuksSecretFile)')
self.secrets.append(secretobj)
return()
def createSecret(self, secrets_xml = None):
if not secrets_xml: # Find all of them from self
for secret in self.xml.findall('secrets'):
secretobj = None
secrettypes = set()
for s in secret.iterchildren():
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.find('keyFile')
secretobj = LuksSecretFile(kf.text, # path
passphrase = secret.find('passphrase').text,
bytesize = kf.attrib.get('size', 4096)) # TECHNICALLY should be a no-op.
elif 'passphrase' in secrettypes:
secretobj = LuksSecretPassphrase(secret.find('passphrase').text)
elif 'keyFile' in secrettypes:
kf = secret.find('keyFile')
secretobj = LuksSecretFile(kf.text,
passphrase = None,
bytesize = kf.attrib.get('size', 4096))
self.secrets.append(secretobj)
else:
secretobj = None
secrettypes = set()
for s in secrets_xml.iterchildren():
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)
return()
def create(self):
if self.created:
return()
if not self.secrets:
raise RuntimeError('Cannot create a LUKS volume with no secrets added')
for idx, secret in enumerate(self.secrets):
if idx == 0:
# TODO: add support for custom parameters for below?
# TODO: logging
cmd = ['cryptsetup',
'--batch-mode',
'luksFormat',
'--type', 'luks2',
'--key-file', '-',
self.source]
subprocess.run(cmd, input = secret.passphrase)
else:
tmpfile = tempfile.mkstemp()
with open(tmpfile[1], 'wb') as fh:
fh.write(secret.passphrase)
cmd = ['cryptsetup',
'--batch-mode',
'luksAdd',
'--type', 'luks2',
'--key-file', '-',
self.source,
tmpfile[1]]
subprocess.run(cmd, input = self.secrets[0].passphrase)
os.remove(tmpfile[1])
self.created = True
return()
def lock(self):
if not self.created:
raise RuntimeError('Cannot lock a LUKS volume before it is created')
if self.locked:
return()
# TODO: logging
cmd = ['cryptsetup',
'--batch-mode',
'luksClose',
self.name]
subprocess.run(cmd)
self.locked = True
return()
def unlock(self, passphrase = None):
if not self.created:
raise RuntimeError('Cannot unlock a LUKS volume before it is created')
if not self.locked:
return()
cmd = ['cryptsetup',
'--batch-mode',
'luksOpen',
'--key-file', '-',
self.source,
self.name]
subprocess.run(cmd, input = self.secrets[0].passphrase)
self.locked = False
return()
def updateInfo(self):
if self.locked:
raise RuntimeError('Must be unlocked to gather info')
info = {}
cmd = ['cryptsetup',
'--batch-mode',
'luksDump',
self.source]
_info = subprocess.run(cmd, stdout = subprocess.PIPE).stdout.decode('utf-8')
k = None
# I wish there was a better way to do this but I sure as heck am not writing a regex to do it.
# https://pypi.org/project/parse/
_tpl = ('LUKS header information\nVersion: {header_ver}\nEpoch: {epoch_ver}\n'
'Metadata area: {metadata_pos} [bytes]\nKeyslots area: {keyslots_pos} [bytes]\n'
'UUID: {uuid}\nLabel: {label}\nSubsystem: {subsystem}\n'
'Flags: {flags}\n\nData segments:\n 0: crypt\n '
'offset: {offset_bytes} [bytes]\n length: {crypt_length}\n '
'cipher: {crypt_cipher}\n sector: {sector_size} [bytes]\n\nKeyslots:\n 0: luks2\n '
'Key: {key_size} bits\n Priority: {priority}\n '
'Cipher: {keyslot_cipher}\n Cipher key: {cipher_key_size} bits\n '
'PBKDF: {pbkdf}\n Time cost: {time_cost}\n Memory: {memory}\n '
'Threads: {threads}\n Salt: {key_salt} \n AF stripes: {af_stripes}\n '
'AF hash: {af_hash}\n Area offset:{keyslot_offset} [bytes]\n '
'Area length:{keyslot_length} [bytes]\n Digest ID: {keyslot_id}\nTokens:\nDigests:\n '
'0: pbkdf2\n Hash: {token_hash}\n Iterations: {token_iterations}\n '
'Salt: {token_salt}\n Digest: {token_digest}\n\n')
info = parse.parse(_tpl, _info).named
for k, v in info.items():
# Technically we can do this in the _tpl string, but it's hard to visually parse.
if k in ('af_stripes', 'cipher_key_size', 'epoch_ver', 'header_ver', 'key_size', 'keyslot_id',
'keyslot_length', 'keyslot_offset', 'keyslots_pos', 'memory', 'metadata_pos', 'offset_bytes',
'sector_size', 'threads', 'time_cost', 'token_iterations'):
v = int(v)
elif k in ('key_salt', 'token_digest', 'token_salt'):
v = bytes.fromhex(re.sub(r'\s+', '', v))
elif k in ('label', 'subsystem'):
if re.search(r'\(no\s+', v.lower()):
v = None
elif k == 'flags':
if v.lower() == '(no flags)':
v = []
else:
# Space-separated or comma-separated? TODO.
v = [i.strip() for i in v.split() if i.strip() != '']
elif k == 'uuid':
v = uuid.UUID(hex = v)
self.info = info
return()
def writeConf(self, conf = '/etc/crypttab'):
if not self.secrets:
raise RuntimeError('secrets must be added before the configuration can be written')
conf = os.path.realpath(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))
return()