2010c13c0a
Prior to Ib563b0ea the passphrase used by CryptsetupEncryptor and LuksEncryptor had any leading zeros per hexadecimal digit removed, for example 0x04 or 04 would turn into 0x4 or 4. As a result any volume encrypted prior to the release of Newton used a modified passphrase that was different to that stored by the key manager being used in the environment. To correct this for LuksEncryptor volumes permission denied errors are now caught when attempting to open a volume. A second attempt to open the volume is then made using a mangled passphrase. If successful the correct passphrase is then added to the volume before the mangled passphrase is finally removed. This workaround can be removed in a future release once it is safe to assume that all LuksEncryptor volumes have had any mangled passphrases replaced in this way. This isn't possible for CryptsetupEncryptor volumes as the plain mode used by cryptsetup does not provide a way for adding and removing keys. As such on a permission denied error a second attempt is made to open the volume using a mangled passphrase. Unlike the above workaround this cannot be removed in a future release. Change-Id: I7096463c5eba951dd6322ee6965435e877ca0371 Partial-bug: #1633518
169 lines
7.1 KiB
Python
169 lines
7.1 KiB
Python
# Copyright (c) 2013 The Johns Hopkins University/Applied Physics Laboratory
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from oslo_concurrency import processutils
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from oslo_log import log as logging
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from nova.i18n import _LI
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from nova.i18n import _LW
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from nova import utils
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from nova.volume.encryptors import cryptsetup
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LOG = logging.getLogger(__name__)
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def is_luks(device):
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"""Checks if the specified device uses LUKS for encryption.
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:param device: the device to check
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:returns: true if the specified device uses LUKS; false otherwise
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"""
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try:
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# check to see if the device uses LUKS: exit status is 0
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# if the device is a LUKS partition and non-zero if not
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utils.execute('cryptsetup', 'isLuks', '--verbose', device,
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run_as_root=True, check_exit_code=True)
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return True
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except processutils.ProcessExecutionError as e:
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LOG.warning(_LW("isLuks exited abnormally (status %(exit_code)s): "
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"%(stderr)s"),
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{"exit_code": e.exit_code, "stderr": e.stderr})
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return False
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class LuksEncryptor(cryptsetup.CryptsetupEncryptor):
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"""A VolumeEncryptor based on LUKS.
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This VolumeEncryptor uses dm-crypt to encrypt the specified volume.
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"""
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def _format_volume(self, passphrase, **kwargs):
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"""Creates a LUKS header on the volume.
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:param passphrase: the passphrase used to access the volume
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"""
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LOG.debug("formatting encrypted volume %s", self.dev_path)
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# NOTE(joel-coffman): cryptsetup will strip trailing newlines from
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# input specified on stdin unless --key-file=- is specified.
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cmd = ["cryptsetup", "--batch-mode", "luksFormat", "--key-file=-"]
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cipher = kwargs.get("cipher", None)
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if cipher is not None:
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cmd.extend(["--cipher", cipher])
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key_size = kwargs.get("key_size", None)
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if key_size is not None:
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cmd.extend(["--key-size", key_size])
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cmd.extend([self.dev_path])
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utils.execute(*cmd, process_input=passphrase,
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check_exit_code=True, run_as_root=True, attempts=3)
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def _open_volume(self, passphrase, **kwargs):
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"""Opens the LUKS partition on the volume using the specified
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passphrase.
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:param passphrase: the passphrase used to access the volume
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"""
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LOG.debug("opening encrypted volume %s", self.dev_path)
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utils.execute('cryptsetup', 'luksOpen', '--key-file=-',
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self.dev_path, self.dev_name, process_input=passphrase,
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run_as_root=True, check_exit_code=True)
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def _unmangle_volume(self, key, passphrase, **kwargs):
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"""Workaround bug#1633518 by first identifying if a mangled passphrase
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is used before replacing it with the correct passphrase.
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"""
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mangled_passphrase = self._get_mangled_passphrase(key)
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self._open_volume(mangled_passphrase, **kwargs)
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self._close_volume(**kwargs)
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LOG.debug("%s correctly opened with a mangled passphrase, replacing"
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"this with the original passphrase", self.dev_path)
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# NOTE(lyarwood): Now that we are sure that the mangled passphrase is
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# used attempt to add the correct passphrase before removing the
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# mangled version from the volume.
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# luksAddKey currently prompts for the following input :
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# Enter any existing passphrase:
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# Enter new passphrase for key slot:
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# Verify passphrase:
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utils.execute('cryptsetup', 'luksAddKey', self.dev_path,
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process_input=''.join([mangled_passphrase, '\n',
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passphrase, '\n', passphrase]),
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run_as_root=True, check_exit_code=True)
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# Verify that we can open the volume with the current passphrase
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# before removing the mangled passphrase.
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self._open_volume(passphrase, **kwargs)
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self._close_volume(**kwargs)
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# luksRemoveKey only prompts for the key to remove.
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utils.execute('cryptsetup', 'luksRemoveKey', self.dev_path,
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process_input=mangled_passphrase,
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run_as_root=True, check_exit_code=True)
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LOG.debug("%s mangled passphrase successfully replaced", self.dev_path)
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def attach_volume(self, context, **kwargs):
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"""Shadows the device and passes an unencrypted version to the
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instance.
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Transparent disk encryption is achieved by mounting the volume via
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dm-crypt and passing the resulting device to the instance. The
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instance is unaware of the underlying encryption due to modifying the
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original symbolic link to refer to the device mounted by dm-crypt.
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"""
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key = self._get_key(context).get_encoded()
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passphrase = self._get_passphrase(key)
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try:
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self._open_volume(passphrase, **kwargs)
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except processutils.ProcessExecutionError as e:
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if e.exit_code == 1 and not is_luks(self.dev_path):
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# the device has never been formatted; format it and try again
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LOG.info(_LI("%s is not a valid LUKS device;"
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" formatting device for first use"),
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self.dev_path)
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self._format_volume(passphrase, **kwargs)
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self._open_volume(passphrase, **kwargs)
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elif e.exit_code == 2:
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# NOTE(lyarwood): Workaround bug#1633518 by replacing any
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# mangled passphrases that are found on the volume.
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# TODO(lyarwood): Remove workaround during R.
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LOG.warning(_LW("%s is not usable with the current "
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"passphrase, attempting to use a mangled "
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"passphrase to open the volume."),
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self.dev_path)
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self._unmangle_volume(key, passphrase, **kwargs)
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self._open_volume(passphrase, **kwargs)
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else:
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raise
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# modify the original symbolic link to refer to the decrypted device
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utils.execute('ln', '--symbolic', '--force',
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'/dev/mapper/%s' % self.dev_name, self.symlink_path,
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run_as_root=True, check_exit_code=True)
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def _close_volume(self, **kwargs):
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"""Closes the device (effectively removes the dm-crypt mapping)."""
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LOG.debug("closing encrypted volume %s", self.dev_path)
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utils.execute('cryptsetup', 'luksClose', self.dev_name,
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run_as_root=True, check_exit_code=True,
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attempts=3)
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