Source code for CedarBackup3.extend.encrypt

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# Copyright (c) 2007,2010,2015 Kenneth J. Pronovici.
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# Author   : Kenneth J. Pronovici <pronovic@ieee.org>
# Language : Python 3 (>= 3.4)
# Project  : Official Cedar Backup Extensions
# Purpose  : Provides an extension to encrypt staging directories.
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# Module documentation
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"""
Provides an extension to encrypt staging directories.

When this extension is executed, all backed-up files in the configured Cedar
Backup staging directory will be encrypted using gpg.  Any directory which has
already been encrypted (as indicated by the ``cback.encrypt`` file) will be
ignored.

This extension requires a new configuration section <encrypt> and is intended
to be run immediately after the standard stage action or immediately before the
standard store action.  Aside from its own configuration, it requires the
options and staging configuration sections in the standard Cedar Backup
configuration file.

:author: Kenneth J. Pronovici <pronovic@ieee.org>
"""

########################################################################
# Imported modules
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# System modules
import os
import logging
from functools import total_ordering

# Cedar Backup modules
from CedarBackup3.util import resolveCommand, executeCommand, changeOwnership
from CedarBackup3.xmlutil import createInputDom, addContainerNode, addStringNode
from CedarBackup3.xmlutil import readFirstChild, readString
from CedarBackup3.actions.util import findDailyDirs, writeIndicatorFile, getBackupFiles


########################################################################
# Module-wide constants and variables
########################################################################

logger = logging.getLogger("CedarBackup3.log.extend.encrypt")

GPG_COMMAND = [ "gpg", ]
VALID_ENCRYPT_MODES = [ "gpg", ]
ENCRYPT_INDICATOR = "cback.encrypt"


########################################################################
# EncryptConfig class definition
########################################################################

[docs]@total_ordering class EncryptConfig(object): """ Class representing encrypt configuration. Encrypt configuration is used for encrypting staging directories. The following restrictions exist on data in this class: - The encrypt mode must be one of the values in ``VALID_ENCRYPT_MODES`` - The encrypt target value must be a non-empty string """
[docs] def __init__(self, encryptMode=None, encryptTarget=None): """ Constructor for the ``EncryptConfig`` class. Args: encryptMode: Encryption mode encryptTarget: Encryption target (for instance, GPG recipient) Raises: ValueError: If one of the values is invalid """ self._encryptMode = None self._encryptTarget = None self.encryptMode = encryptMode self.encryptTarget = encryptTarget
def __repr__(self): """ Official string representation for class instance. """ return "EncryptConfig(%s, %s)" % (self.encryptMode, self.encryptTarget) def __str__(self): """ Informal string representation for class instance. """ return self.__repr__() def __eq__(self, other): """Equals operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) == 0 def __lt__(self, other): """Less-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) < 0 def __gt__(self, other): """Greater-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) > 0 def __cmp__(self, other): """ Original Python 2 comparison operator. Lists within this class are "unordered" for equality comparisons. Args: other: Other object to compare to Returns: -1/0/1 depending on whether self is ``<``, ``=`` or ``>`` other """ if other is None: return 1 if self.encryptMode != other.encryptMode: if str(self.encryptMode or "") < str(other.encryptMode or ""): return -1 else: return 1 if self.encryptTarget != other.encryptTarget: if str(self.encryptTarget or "") < str(other.encryptTarget or ""): return -1 else: return 1 return 0 def _setEncryptMode(self, value): """ Property target used to set the encrypt mode. If not ``None``, the mode must be one of the values in ``VALID_ENCRYPT_MODES``. Raises: ValueError: If the value is not valid """ if value is not None: if value not in VALID_ENCRYPT_MODES: raise ValueError("Encrypt mode must be one of %s." % VALID_ENCRYPT_MODES) self._encryptMode = value def _getEncryptMode(self): """ Property target used to get the encrypt mode. """ return self._encryptMode def _setEncryptTarget(self, value): """ Property target used to set the encrypt target. """ if value is not None: if len(value) < 1: raise ValueError("Encrypt target must be non-empty string.") self._encryptTarget = value def _getEncryptTarget(self): """ Property target used to get the encrypt target. """ return self._encryptTarget encryptMode = property(_getEncryptMode, _setEncryptMode, None, doc="Encrypt mode.") encryptTarget = property(_getEncryptTarget, _setEncryptTarget, None, doc="Encrypt target (i.e. GPG recipient).")
######################################################################## # LocalConfig class definition ########################################################################
[docs]@total_ordering class LocalConfig(object): """ Class representing this extension's configuration document. This is not a general-purpose configuration object like the main Cedar Backup configuration object. Instead, it just knows how to parse and emit encrypt-specific configuration values. Third parties who need to read and write configuration related to this extension should access it through the constructor, ``validate`` and ``addConfig`` methods. *Note:* Lists within this class are "unordered" for equality comparisons. """
[docs] def __init__(self, xmlData=None, xmlPath=None, validate=True): """ Initializes a configuration object. If you initialize the object without passing either ``xmlData`` or ``xmlPath`` then configuration will be empty and will be invalid until it is filled in properly. No reference to the original XML data or original path is saved off by this class. Once the data has been parsed (successfully or not) this original information is discarded. Unless the ``validate`` argument is ``False``, the :any:`LocalConfig.validate` method will be called (with its default arguments) against configuration after successfully parsing any passed-in XML. Keep in mind that even if ``validate`` is ``False``, it might not be possible to parse the passed-in XML document if lower-level validations fail. *Note:* It is strongly suggested that the ``validate`` option always be set to ``True`` (the default) unless there is a specific need to read in invalid configuration from disk. Args: xmlData (String data): XML data representing configuration xmlPath (Absolute path to a file on disk): Path to an XML file on disk validate (Boolean true/false): Validate the document after parsing it Raises: ValueError: If both ``xmlData`` and ``xmlPath`` are passed-in ValueError: If the XML data in ``xmlData`` or ``xmlPath`` cannot be parsed ValueError: If the parsed configuration document is not valid """ self._encrypt = None self.encrypt = None if xmlData is not None and xmlPath is not None: raise ValueError("Use either xmlData or xmlPath, but not both.") if xmlData is not None: self._parseXmlData(xmlData) if validate: self.validate() elif xmlPath is not None: with open(xmlPath) as f: xmlData = f.read() self._parseXmlData(xmlData) if validate: self.validate()
def __repr__(self): """ Official string representation for class instance. """ return "LocalConfig(%s)" % (self.encrypt) def __str__(self): """ Informal string representation for class instance. """ return self.__repr__() def __eq__(self, other): """Equals operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) == 0 def __lt__(self, other): """Less-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) < 0 def __gt__(self, other): """Greater-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) > 0 def __cmp__(self, other): """ Original Python 2 comparison operator. Lists within this class are "unordered" for equality comparisons. Args: other: Other object to compare to Returns: -1/0/1 depending on whether self is ``<``, ``=`` or ``>`` other """ if other is None: return 1 if self.encrypt != other.encrypt: if self.encrypt < other.encrypt: return -1 else: return 1 return 0 def _setEncrypt(self, value): """ Property target used to set the encrypt configuration value. If not ``None``, the value must be a ``EncryptConfig`` object. Raises: ValueError: If the value is not a ``EncryptConfig`` """ if value is None: self._encrypt = None else: if not isinstance(value, EncryptConfig): raise ValueError("Value must be a ``EncryptConfig`` object.") self._encrypt = value def _getEncrypt(self): """ Property target used to get the encrypt configuration value. """ return self._encrypt encrypt = property(_getEncrypt, _setEncrypt, None, "Encrypt configuration in terms of a ``EncryptConfig`` object.")
[docs] def validate(self): """ Validates configuration represented by the object. Encrypt configuration must be filled in. Within that, both the encrypt mode and encrypt target must be filled in. Raises: ValueError: If one of the validations fails """ if self.encrypt is None: raise ValueError("Encrypt section is required.") if self.encrypt.encryptMode is None: raise ValueError("Encrypt mode must be set.") if self.encrypt.encryptTarget is None: raise ValueError("Encrypt target must be set.")
[docs] def addConfig(self, xmlDom, parentNode): """ Adds an <encrypt> configuration section as the next child of a parent. Third parties should use this function to write configuration related to this extension. We add the following fields to the document:: encryptMode //cb_config/encrypt/encrypt_mode encryptTarget //cb_config/encrypt/encrypt_target Args: xmlDom: DOM tree as from ``impl.createDocument()`` parentNode: Parent that the section should be appended to """ if self.encrypt is not None: sectionNode = addContainerNode(xmlDom, parentNode, "encrypt") addStringNode(xmlDom, sectionNode, "encrypt_mode", self.encrypt.encryptMode) addStringNode(xmlDom, sectionNode, "encrypt_target", self.encrypt.encryptTarget)
def _parseXmlData(self, xmlData): """ Internal method to parse an XML string into the object. This method parses the XML document into a DOM tree (``xmlDom``) and then calls a static method to parse the encrypt configuration section. Args: xmlData (String data): XML data to be parsed Raises: ValueError: If the XML cannot be successfully parsed """ (xmlDom, parentNode) = createInputDom(xmlData) self._encrypt = LocalConfig._parseEncrypt(parentNode) @staticmethod def _parseEncrypt(parent): """ Parses an encrypt configuration section. We read the following individual fields:: encryptMode //cb_config/encrypt/encrypt_mode encryptTarget //cb_config/encrypt/encrypt_target Args: parent: Parent node to search beneath Returns: ``EncryptConfig`` object or ``None`` if the section does not exist Raises: ValueError: If some filled-in value is invalid """ encrypt = None section = readFirstChild(parent, "encrypt") if section is not None: encrypt = EncryptConfig() encrypt.encryptMode = readString(section, "encrypt_mode") encrypt.encryptTarget = readString(section, "encrypt_target") return encrypt
######################################################################## # Public functions ######################################################################## ########################### # executeAction() function ########################### # pylint: disable=W0613
[docs]def executeAction(configPath, options, config): """ Executes the encrypt backup action. Args: configPath (String representing a path on disk): Path to configuration file on disk options (Options object): Program command-line options config (Config object): Program configuration Raises: ValueError: Under many generic error conditions IOError: If there are I/O problems reading or writing files """ logger.debug("Executing encrypt extended action.") if config.options is None or config.stage is None: raise ValueError("Cedar Backup configuration is not properly filled in.") local = LocalConfig(xmlPath=configPath) if local.encrypt.encryptMode not in ["gpg", ]: raise ValueError("Unknown encrypt mode [%s]" % local.encrypt.encryptMode) if local.encrypt.encryptMode == "gpg": _confirmGpgRecipient(local.encrypt.encryptTarget) dailyDirs = findDailyDirs(config.stage.targetDir, ENCRYPT_INDICATOR) for dailyDir in dailyDirs: _encryptDailyDir(dailyDir, local.encrypt.encryptMode, local.encrypt.encryptTarget, config.options.backupUser, config.options.backupGroup) writeIndicatorFile(dailyDir, ENCRYPT_INDICATOR, config.options.backupUser, config.options.backupGroup) logger.info("Executed the encrypt extended action successfully.")
############################## # _encryptDailyDir() function ############################## def _encryptDailyDir(dailyDir, encryptMode, encryptTarget, backupUser, backupGroup): """ Encrypts the contents of a daily staging directory. Indicator files are ignored. All other files are encrypted. The only valid encrypt mode is ``"gpg"``. Args: dailyDir: Daily directory to encrypt encryptMode: Encryption mode (only "gpg" is allowed) encryptTarget: Encryption target (GPG recipient for "gpg" mode) backupUser: User that target files should be owned by backupGroup: Group that target files should be owned by Raises: ValueError: If the encrypt mode is not supported ValueError: If the daily staging directory does not exist """ logger.debug("Begin encrypting contents of [%s].", dailyDir) fileList = getBackupFiles(dailyDir) # ignores indicator files for path in fileList: _encryptFile(path, encryptMode, encryptTarget, backupUser, backupGroup, removeSource=True) logger.debug("Completed encrypting contents of [%s].", dailyDir) ########################## # _encryptFile() function ########################## def _encryptFile(sourcePath, encryptMode, encryptTarget, backupUser, backupGroup, removeSource=False): """ Encrypts the source file using the indicated mode. The encrypted file will be owned by the indicated backup user and group. If ``removeSource`` is ``True``, then the source file will be removed after it is successfully encrypted. Currently, only the ``"gpg"`` encrypt mode is supported. Args: sourcePath: Absolute path of the source file to encrypt encryptMode: Encryption mode (only "gpg" is allowed) encryptTarget: Encryption target (GPG recipient) backupUser: User that target files should be owned by backupGroup: Group that target files should be owned by removeSource: Indicates whether to remove the source file Returns: Path to the newly-created encrypted file Raises: ValueError: If an invalid encrypt mode is passed in IOError: If there is a problem accessing, encrypting or removing the source file """ if not os.path.exists(sourcePath): raise ValueError("Source path [%s] does not exist." % sourcePath) if encryptMode == 'gpg': encryptedPath = _encryptFileWithGpg(sourcePath, recipient=encryptTarget) else: raise ValueError("Unknown encrypt mode [%s]" % encryptMode) changeOwnership(encryptedPath, backupUser, backupGroup) if removeSource: if os.path.exists(sourcePath): try: os.remove(sourcePath) logger.debug("Completed removing old file [%s].", sourcePath) except: raise IOError("Failed to remove file [%s] after encrypting it." % (sourcePath)) return encryptedPath ################################# # _encryptFileWithGpg() function ################################# def _encryptFileWithGpg(sourcePath, recipient): """ Encrypts the indicated source file using GPG. The encrypted file will be in GPG's binary output format and will have the same name as the source file plus a ``".gpg"`` extension. The source file will not be modified or removed by this function call. Args: sourcePath: Absolute path of file to be encrypted recipient: Recipient name to be passed to GPG's ``"-r"`` option Returns: Path to the newly-created encrypted file Raises: IOError: If there is a problem encrypting the file """ encryptedPath = "%s.gpg" % sourcePath command = resolveCommand(GPG_COMMAND) args = [ "--batch", "--yes", "-e", "-r", recipient, "-o", encryptedPath, sourcePath, ] result = executeCommand(command, args)[0] if result != 0: raise IOError("Error [%d] calling gpg to encrypt [%s]." % (result, sourcePath)) if not os.path.exists(encryptedPath): raise IOError("After call to [%s], encrypted file [%s] does not exist." % (command, encryptedPath)) logger.debug("Completed encrypting file [%s] to [%s].", sourcePath, encryptedPath) return encryptedPath ################################# # _confirmGpgRecpient() function ################################# def _confirmGpgRecipient(recipient): """ Confirms that a recipient's public key is known to GPG. Throws an exception if there is a problem, or returns normally otherwise. Args: recipient: Recipient name Raises: IOError: If the recipient's public key is not known to GPG """ command = resolveCommand(GPG_COMMAND) args = [ "--batch", "-k", recipient, ] # should use --with-colons if the output will be parsed result = executeCommand(command, args)[0] if result != 0: raise IOError("GPG unable to find public key for [%s]." % recipient)