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storage/file: major FilePool/FileVolume cleanup and documentation

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This driver isn't used in default Qubes 4.0 installation, but if we do
have it, let it follow defined API and its own documentation. And also
explicitly reject not supported operations:
 - support only revisions_to_keep<=1, but do not support revert() anyway
 (implemented version were wrong on so many levels...)
 - use 'save_on_stop'/'snap_on_start' properties directly instead of
 obsolete volume types
 - don't call sudo - qubesd is running as root
 - consistently use path, path_cow, path_source, path_source_cow

Also, add tests for BlockDevice instance returned by
FileVolume.block_device().

QubesOS/qubes-issues#2256
This commit is contained in:
Marek Marczykowski-Górecki 2017-07-01 22:45:22 +02:00
parent 1a1dd3dba2
commit 317d140f46
No known key found for this signature in database
GPG Key ID: 063938BA42CFA724
3 changed files with 114 additions and 125 deletions
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9
qubes/storage/__init__.py
View File

@ -111,6 +111,15 @@ class Volume(object):
assert source is None or (isinstance(source, Volume)
and source.pool == pool)
if snap_on_start and source is None:
msg = "snap_on_start specified on {!r} but no volume source set"
msg = msg.format(name)
raise StoragePoolException(msg)
elif not snap_on_start and source is not None:
msg = "source specified on {!r} but no snap_on_start set"
msg = msg.format(name)
raise StoragePoolException(msg)
#: Name of the volume in a domain it's attached to (like `root` or
#: `private`).
self.name = str(name)

179
qubes/storage/file.py
View File

@ -37,6 +37,20 @@ BLKSIZE = 512
class FilePool(qubes.storage.Pool):
''' File based 'original' disk implementation
Volumes are stored in sparse files. Additionally device-mapper is used for
applying copy-on-write layer.
Quick reference on device-mapper layers:
snap_on_start save_on_stop layout
yes yes not supported
no yes snapshot-origin(volume.img, volume-cow.img)
yes no snapshot(
snapshot(source.img, source-cow.img),
volume-cow.img)
no no volume.img directly
''' # pylint: disable=protected-access
driver = 'file'
@ -57,16 +71,18 @@ class FilePool(qubes.storage.Pool):
}
def init_volume(self, vm, volume_config):
if volume_config.get('snap_on_start', False) and \
volume_config.get('save_on_stop', False):
raise NotImplementedError(
'snap_on_start + save_on_stop not supported by file driver')
volume_config['dir_path'] = self.dir_path
if os.path.join(self.dir_path, self._vid_prefix(vm)) == vm.dir_path:
volume_config['backward_comp'] = True
if 'vid' not in volume_config:
volume_config['vid'] = os.path.join(
self._vid_prefix(vm), volume_config['name'])
try:
if volume_config['reset_on_start']:
if not volume_config.get('save_on_stop', False):
volume_config['revisions_to_keep'] = 0
except KeyError:
pass
@ -74,6 +90,10 @@ class FilePool(qubes.storage.Pool):
if 'revisions_to_keep' not in volume_config:
volume_config['revisions_to_keep'] = self.revisions_to_keep
if int(volume_config['revisions_to_keep']) > 1:
raise NotImplementedError(
'FilePool supports maximum 1 volume revision to keep')
volume_config['pool'] = self
volume = FileVolume(**volume_config)
self._volumes += [volume]
@ -130,59 +150,37 @@ class FileVolume(qubes.storage.Volume):
''' Parent class for the xen volumes implementation which expects a
`target_dir` param on initialization. '''
def __init__(self, dir_path, backward_comp=False, **kwargs):
def __init__(self, dir_path, **kwargs):
self.dir_path = dir_path
self.backward_comp = backward_comp
assert self.dir_path, "dir_path not specified"
super(FileVolume, self).__init__(**kwargs)
if self.snap_on_start and self.source is None:
msg = "snap_on_start specified on {!r} but no volume source set"
msg = msg.format(self.name)
raise qubes.storage.StoragePoolException(msg)
elif not self.snap_on_start and self.source is not None:
msg = "source specified on {!r} but no snap_on_start set"
msg = msg.format(self.name)
raise qubes.storage.StoragePoolException(msg)
if self._is_snapshot:
if self.snap_on_start:
img_name = self.source.vid + '-cow.img'
self.path_source_cow = os.path.join(self.dir_path, img_name)
elif self._is_volume or self._is_volatile:
pass
elif self._is_origin:
pass
else:
assert False, 'This should not happen'
def create(self):
assert isinstance(self.size, int) and self.size > 0, \
'Volatile volume size must be > 0'
if self._is_origin:
'Volume size must be > 0'
if not self.snap_on_start:
create_sparse_file(self.path, self.size)
# path_cow not needed only in volatile volume
if self.save_on_stop or self.snap_on_start:
create_sparse_file(self.path_cow, self.size)
elif not self._is_snapshot:
if self.source is not None:
source_path = os.path.join(self.dir_path,
self.source.vid + '.img')
copy_file(source_path, self.path)
elif self._is_volatile:
pass
else:
create_sparse_file(self.path, self.size)
def remove(self):
if not self.internal:
return # do not remove random attached file volumes
elif self._is_snapshot:
return # no need to remove, because it's just a snapshot
else:
if not self.snap_on_start:
_remove_if_exists(self.path)
if self._is_origin:
if self.snap_on_start or self.save_on_stop:
_remove_if_exists(self.path_cow)
def is_dirty(self):
return False # TODO: How to implement this?
if not self.save_on_stop:
return False
if os.path.exists(self.path_cow):
stat = os.stat(self.path_cow)
return stat.st_blocks > 0
return False
def resize(self, size):
''' Expands volume, throws
@ -203,7 +201,7 @@ class FileVolume(qubes.storage.Volume):
with open(self.path, 'a+b') as fd:
fd.truncate(size)
p = subprocess.Popen(['sudo', 'losetup', '--associated', self.path],
p = subprocess.Popen(['losetup', '--associated', self.path],
stdout=subprocess.PIPE)
result = p.communicate()
@ -212,28 +210,27 @@ class FileVolume(qubes.storage.Volume):
loop_dev = m.group(1)
# resize loop device
subprocess.check_call(['sudo', 'losetup', '--set-capacity',
subprocess.check_call(['losetup', '--set-capacity',
loop_dev])
self.size = size
def commit(self):
msg = 'Tried to commit a non commitable volume {!r}'.format(self)
assert (self._is_origin or self._is_volume) and self.rw, msg
if self._is_volume:
return self
assert self.save_on_stop and self.rw, msg
if os.path.exists(self.path_cow):
if self.revisions_to_keep:
old_path = self.path_cow + '.old'
os.rename(self.path_cow, old_path)
else:
os.unlink(self.path_cow)
old_umask = os.umask(0o002)
with open(self.path_cow, 'w') as f_cow:
f_cow.truncate(self.size)
os.umask(old_umask)
create_sparse_file(self.path_cow, self.size)
return self
def export(self):
# FIXME: this should rather return snapshot(self.path, self.path_cow)
# if domain is running
return self.path
def import_volume(self, src_volume):
@ -251,53 +248,30 @@ class FileVolume(qubes.storage.Volume):
def reset(self):
''' Remove and recreate a volatile volume '''
assert self._is_volatile, "Not a volatile volume"
assert not self.snap_on_start and not self.save_on_stop, \
"Not a volatile volume"
assert isinstance(self.size, int) and self.size > 0, \
'Volatile volume size must be > 0'
_remove_if_exists(self.path)
with open(self.path, "w") as f_volatile:
f_volatile.truncate(self.size)
create_sparse_file(self.path, self.size)
return self
def revert(self, revision=None):
if revision is not None:
try:
return self.revisions[revision]
except KeyError:
msg = "Volume {!r} does not have revision {!s}"
msg = msg.format(self, revision)
raise qubes.storage.StoragePoolException(msg)
else:
try:
old_path = self.revisions.values().pop()
os.rename(old_path, self.path_cow)
except IndexError:
msg = "Volume {!r} does not have old revisions".format(self)
raise qubes.storage.StoragePoolException(msg)
def start(self):
if self._is_volatile:
if not self.save_on_stop and not self.snap_on_start:
self.reset()
else:
_check_path(self.path)
if self.snap_on_start:
if not self.save_on_stop:
# make sure previous snapshot is removed - even if VM
# shutdown routing wasn't called (power interrupt or so)
# shutdown routine wasn't called (power interrupt or so)
_remove_if_exists(self.path_cow)
try:
_check_path(self.path_cow)
except qubes.storage.StoragePoolException:
if not os.path.exists(self.path_cow):
create_sparse_file(self.path_cow, self.size)
_check_path(self.path_cow)
if not self.snap_on_start:
_check_path(self.path)
if hasattr(self, 'path_source_cow'):
try:
_check_path(self.path_source_cow)
except qubes.storage.StoragePoolException:
if not os.path.exists(self.path_source_cow):
create_sparse_file(self.path_source_cow, self.size)
_check_path(self.path_source_cow)
return self
def stop(self):
@ -311,7 +285,7 @@ class FileVolume(qubes.storage.Volume):
@property
def path(self):
if self._is_snapshot:
if self.snap_on_start:
return os.path.join(self.dir_path, self.source.vid + '.img')
return os.path.join(self.dir_path, self.vid + '.img')
@ -322,18 +296,19 @@ class FileVolume(qubes.storage.Volume):
def verify(self):
''' Verifies the volume. '''
if not os.path.exists(self.path) and not self._is_volatile:
if not os.path.exists(self.path) and \
(self.snap_on_start or self.save_on_stop):
msg = 'Missing image file: {!s}.'.format(self.path)
raise qubes.storage.StoragePoolException(msg)
return True
@property
def script(self):
if self._is_volume or self._is_volatile:
if not self.snap_on_start and not self.save_on_stop:
return None
elif self._is_origin:
elif not self.snap_on_start and self.save_on_stop:
return 'block-origin'
elif self._is_origin_snapshot or self._is_snapshot:
elif self.snap_on_start:
return 'block-snapshot'
def block_device(self):
@ -341,9 +316,9 @@ class FileVolume(qubes.storage.Volume):
the libvirt XML template as <disk>.
'''
path = self.path
if self._is_snapshot:
if self.snap_on_start:
path += ":" + self.path_source_cow
if self._is_origin or self._is_snapshot:
if self.snap_on_start or self.save_on_stop:
path += ":" + self.path_cow
return qubes.storage.BlockDevice(path, self.name, self.script, self.rw,
self.domain, self.devtype)
@ -360,39 +335,13 @@ class FileVolume(qubes.storage.Volume):
seconds = os.path.getctime(old_revision)
iso_date = qubes.storage.isodate(seconds).split('.', 1)[0]
return {iso_date: old_revision}
return {'old': iso_date}
@property
def usage(self):
''' Returns the actualy used space '''
return get_disk_usage(self.vid)
@property
def _is_volatile(self):
''' Internal helper. Useful for differentiating volume handling '''
return not self.snap_on_start and not self.save_on_stop
@property
def _is_origin(self):
''' Internal helper. Useful for differentiating volume handling '''
# pylint: disable=line-too-long
return self.save_on_stop and self.revisions_to_keep > 0 # NOQA
@property
def _is_snapshot(self):
''' Internal helper. Useful for differentiating volume handling '''
return self.snap_on_start and not self.save_on_stop
@property
def _is_origin_snapshot(self):
''' Internal helper. Useful for differentiating volume handling '''
return self.snap_on_start and self.save_on_stop
@property
def _is_volume(self):
''' Internal helper. Usefull for differentiating volume handling '''
# pylint: disable=line-too-long
return not self.snap_on_start and self.save_on_stop and self.revisions_to_keep == 0 # NOQA
def create_sparse_file(path, size):
''' Create an empty sparse file '''

33
qubes/tests/storage_file.py
View File

@ -136,6 +136,15 @@ class TC_01_FileVolumes(qubes.tests.QubesTestCase):
self.assertFalse(volume.snap_on_start)
self.assertTrue(volume.save_on_stop)
self.assertTrue(volume.rw)
block = volume.block_device()
self.assertEqual(block.path,
'{base}.img:{base}-cow.img'.format(
base=self.POOL_DIR + '/appvms/' + vm.name + '/root'))
self.assertEqual(block.script, 'block-origin')
self.assertEqual(block.rw, True)
self.assertEqual(block.name, 'root')
self.assertEqual(block.devtype, 'disk')
self.assertIsNone(block.domain)
def test_001_snapshot_volume(self):
template_vm = self.app.default_template
@ -169,6 +178,19 @@ class TC_01_FileVolumes(qubes.tests.QubesTestCase):
self.assertFalse(volume.save_on_stop)
self.assertFalse(volume.rw)
self.assertEqual(volume.usage, 0)
block = volume.block_device()
assert isinstance(block, qubes.storage.BlockDevice)
self.assertEqual(block.path,
'{base}/{src}.img:{base}/{src}-cow.img:'
'{base}/{dst}-cow.img'.format(
base=self.POOL_DIR,
src='vm-templates/' + template_vm.name + '/root',
dst='appvms/' + vm.name + '/root',
))
self.assertEqual(block.name, 'root')
self.assertEqual(block.script, 'block-snapshot')
self.assertEqual(block.rw, False)
self.assertEqual(block.devtype, 'disk')
def test_002_read_write_volume(self):
config = {
@ -186,6 +208,12 @@ class TC_01_FileVolumes(qubes.tests.QubesTestCase):
self.assertFalse(volume.snap_on_start)
self.assertTrue(volume.save_on_stop)
self.assertTrue(volume.rw)
block = volume.block_device()
self.assertEqual(block.name, 'root')
self.assertEqual(block.path, '{base}.img:{base}-cow.img'.format(
base=self.POOL_DIR + '/appvms/' + vm.name + '/root'))
self.assertEqual(block.rw, True)
self.assertEqual(block.script, 'block-origin')
def test_003_read_only_volume(self):
template = self.app.default_template
@ -207,6 +235,8 @@ class TC_01_FileVolumes(qubes.tests.QubesTestCase):
self.assertFalse(volume.snap_on_start)
self.assertFalse(volume.save_on_stop)
self.assertFalse(volume.rw)
block = volume.block_device()
self.assertEqual(block.rw, False)
def test_004_volatile_volume(self):
config = {
@ -248,7 +278,8 @@ class TC_01_FileVolumes(qubes.tests.QubesTestCase):
expected = vm.dir_path + '/root.img:' + vm.dir_path + '/root-cow.img'
self.assertVolumePath(vm, 'root', expected, rw=True)
expected = vm.dir_path + '/private.img'
expected = vm.dir_path + '/private.img:' + \
vm.dir_path + '/private-cow.img'
self.assertVolumePath(vm, 'private', expected, rw=True)
expected = vm.dir_path + '/volatile.img'
self.assertVolumePath(vm, 'volatile', expected, rw=True)