Source code for duplicity.gpg

# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4; encoding:utf-8 -*-
#
# Copyright 2002 Ben Escoto <ben@emerose.org>
# Copyright 2007 Kenneth Loafman <kenneth@loafman.com>
#
# This file is part of duplicity.
#
# Duplicity is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
# Duplicity is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with duplicity; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

u"""
duplicity's gpg interface, builds upon Frank Tobin's GnuPGInterface
which is now patched with some code for iterative threaded execution
see duplicity's README for details
"""

from builtins import next
from builtins import str
from builtins import object
import os
import sys
import tempfile
import re
import gzip
import locale

from duplicity import config
from duplicity import gpginterface
from duplicity import tempdir
from duplicity import util

try:
    from hashlib import sha1
    from hashlib import md5
except ImportError:
    from sha import new as sha1
    from md5 import new as md5

blocksize = 256 * 1024


[docs]class GPGError(Exception): u""" Indicate some GPG Error """ pass
[docs]class GPGProfile(object): u""" Just hold some GPG settings, avoid passing tons of arguments """
[docs] def __init__(self, passphrase=None, sign_key=None, recipients=None, hidden_recipients=None): u""" Set all data with initializer passphrase is the passphrase. If it is None (not ""), assume it hasn't been set. sign_key can be blank if no signing is indicated, and recipients should be a list of keys. For all keys, the format should be an hex key like 'AA0E73D2'. """ assert passphrase is None or isinstance(passphrase, (str, u"".__class__)) self.passphrase = passphrase self.signing_passphrase = passphrase self.sign_key = sign_key self.encrypt_secring = None if recipients is not None: assert isinstance(recipients, list) # must be list, not tuple self.recipients = recipients else: self.recipients = [] if hidden_recipients is not None: assert isinstance(hidden_recipients, list) # must be list, not tuple self.hidden_recipients = hidden_recipients else: self.hidden_recipients = [] self.gpg_version = self.get_gpg_version(config.gpg_binary)
rc = re.compile _version_re = rc(b'^gpg.*\\(GnuPG(?:/MacGPG2)?\\) (?P<maj>[0-9]+)\\.(?P<min>[0-9]+)\\.(?P<bug>[0-9]+)(-.+)?$')
[docs] def get_gpg_version(self, binary): gnupg = gpginterface.GnuPG() if binary is not None: gnupg.call = binary # user supplied options if config.gpg_options: for opt in config.gpg_options.split(): gnupg.options.extra_args.append(opt) # get gpg version res = gnupg.run([u"--version"], create_fhs=[u"stdout"]) line = res.handles[u"stdout"].readline().rstrip() m = self._version_re.search(line) if m is not None: return int(m.group(u"maj")), int(m.group(u"min")), int(m.group(u"bug")) raise GPGError(u"failed to determine gnupg version of %s from %s" % (binary, line))
[docs]class GPGFile(object): u""" File-like object that encrypts decrypts another file on the fly """
[docs] def __init__(self, encrypt, encrypt_path, profile): u""" GPGFile initializer If recipients is set, use public key encryption and encrypt to the given keys. Otherwise, use symmetric encryption. encrypt_path is the Path of the gpg encrypted file. Right now only symmetric encryption/decryption is supported. If passphrase is false, do not set passphrase - GPG program should prompt for it. """ self.status_fp = None # used to find signature self.closed = None # set to true after file closed self.stderr_fp = tempfile.TemporaryFile(dir=tempdir.default().dir()) self.name = encrypt_path self.byte_count = 0 self.signature = None # Start GPG process - copied from GnuPGInterface docstring. gnupg = gpginterface.GnuPG() # overrides default gpg binary 'gpg' if config.gpg_binary is not None: gnupg.call = config.gpg_binary gnupg.options.meta_interactive = 0 gnupg.options.extra_args.append(u'--no-secmem-warning') gnupg.options.extra_args.append(u'--ignore-mdc-error') # Support three versions of gpg present 1.x, 2.0.x, 2.1.x if profile.gpg_version[:1] == (1,): if config.use_agent: # gpg1 agent use is optional gnupg.options.extra_args.append(u'--use-agent') elif profile.gpg_version[:2] == (2, 0): pass elif profile.gpg_version[:2] >= (2, 1): if not config.use_agent: # This forces gpg2 to ignore the agent. # Necessary to enforce truly non-interactive operation. gnupg.options.extra_args.append(u'--pinentry-mode=loopback') else: raise GPGError(u"Unsupported GNUPG version, %s" % profile.gpg_version) # user supplied options if config.gpg_options: for opt in config.gpg_options.split(): gnupg.options.extra_args.append(opt) cmdlist = [] if profile.sign_key: gnupg.options.default_key = profile.sign_key cmdlist.append(u"--sign") # encrypt: sign key needs passphrase # decrypt: encrypt key needs passphrase # special case: allow different symmetric pass with empty sign pass if encrypt and profile.sign_key and profile.signing_passphrase: passphrase = profile.signing_passphrase else: passphrase = profile.passphrase # in case the passphrase is not set, pass an empty one to prevent # TypeError: expected a character buffer object on .write() if passphrase is None: passphrase = u"" if encrypt: if profile.recipients: gnupg.options.recipients = profile.recipients if profile.hidden_recipients: gnupg.options.hidden_recipients = profile.hidden_recipients if profile.recipients or profile.hidden_recipients: cmdlist.append(u'--encrypt') else: cmdlist.append(u'--symmetric') # use integrity protection gnupg.options.extra_args.append(u'--force-mdc') # Skip the passphrase if using the agent if config.use_agent: gnupg_fhs = [u'stdin', ] else: gnupg_fhs = [u'stdin', u'passphrase'] p1 = gnupg.run(cmdlist, create_fhs=gnupg_fhs, attach_fhs={u'stdout': encrypt_path.open(u"wb"), u'stderr': self.stderr_fp}) if not config.use_agent: p1.handles[u'passphrase'].write(passphrase) p1.handles[u'passphrase'].close() self.gpg_input = p1.handles[u'stdin'] else: if (profile.recipients or profile.hidden_recipients) and profile.encrypt_secring: cmdlist.append(u'--secret-keyring') cmdlist.append(profile.encrypt_secring) gpg_attach = {u'stdin': encrypt_path.open(u"rb"), u'stderr': self.stderr_fp} if profile.sign_key: self.status_fp = tempfile.TemporaryFile(dir=tempdir.default().dir()) gpg_attach[u'status'] = self.status_fp # Skip the passphrase if using the agent if config.use_agent: gnupg_fhs = [u'stdout', ] else: gnupg_fhs = [u'stdout', u'passphrase'] p1 = gnupg.run([u'--decrypt'], create_fhs=gnupg_fhs, attach_fhs=gpg_attach) if not config.use_agent: p1.handles[u'passphrase'].write(passphrase) p1.handles[u'passphrase'].close() self.gpg_output = p1.handles[u'stdout'] self.gpg_process = p1 self.encrypt = encrypt
[docs] def read(self, length=-1): try: res = self.gpg_output.read(length) if res is not None: self.byte_count += len(res) except Exception: self.gpg_failed() return res
[docs] def write(self, buf): try: res = self.gpg_input.write(buf) if res is not None: if sys.version_info.major >= 3: self.byte_count += res else: self.byte_count += len(res) except Exception: self.gpg_failed() return res
[docs] def tell(self): return self.byte_count
[docs] def seek(self, offset): assert not self.encrypt assert offset >= self.byte_count, u"%d < %d" % (offset, self.byte_count) if offset > self.byte_count: self.read(offset - self.byte_count)
[docs] def gpg_failed(self): msg = u"GPG Failed, see log below:\n" msg += u"===== Begin GnuPG log =====\n" self.stderr_fp.seek(0) for line in self.stderr_fp: try: msg += str(line.strip(), locale.getpreferredencoding(), u'replace') + u"\n" except Exception as e: msg += line.strip() + u"\n" msg += u"===== End GnuPG log =====\n" if not (msg.find(u"invalid packet (ctb=14)") > -1): raise GPGError(msg) else: return u""
[docs] def close(self): if self.encrypt: try: self.gpg_input.close() except Exception: self.gpg_failed() if self.status_fp: self.set_signature() try: self.gpg_process.wait() except Exception: self.gpg_failed() else: res = 1 while res: # discard remaining output to avoid GPG error try: res = self.gpg_output.read(blocksize) except Exception: self.gpg_failed() try: self.gpg_output.close() except Exception: self.gpg_failed() if self.status_fp: self.set_signature() try: self.gpg_process.wait() except Exception: self.gpg_failed() self.stderr_fp.close() self.closed = 1
[docs] def set_signature(self): u""" Set self.signature to signature keyID This only applies to decrypted files. If the file was not signed, set self.signature to None. """ self.status_fp.seek(0) status_buf = self.status_fp.read() match = re.search(b"^\\[GNUPG:\\] GOODSIG ([0-9A-F]*)", status_buf, re.M) if not match: self.signature = None else: assert len(match.group(1)) >= 8 self.signature = match.group(1).decode()
[docs] def get_signature(self): u""" Return keyID of signature, or None if none """ assert self.closed return self.signature
[docs]def GPGWriteFile(block_iter, filename, profile, size=200 * 1024 * 1024, max_footer_size=16 * 1024): u""" Write GPG compressed file of given size This function writes a gpg compressed file by reading from the input iter and writing to filename. When it has read an amount close to the size limit, it "tops off" the incoming data with incompressible data, to try to hit the limit exactly. block_iter should have methods .next(size), which returns the next block of data, which should be at most size bytes long. Also .get_footer() returns a string to write at the end of the input file. The footer should have max length max_footer_size. Because gpg uses compression, we don't assume that putting bytes_in bytes into gpg will result in bytes_out = bytes_in out. However, do assume that bytes_out <= bytes_in approximately. Returns true if succeeded in writing until end of block_iter. """ # workaround for circular module imports from duplicity import path def top_off(bytelen, file): u""" Add bytelen of incompressible data to to_gpg_fp In this case we take the incompressible data from the beginning of filename (it should contain enough because size >> largest block size). """ incompressible_fp = open(filename, u"rb") assert util.copyfileobj(incompressible_fp, file.gpg_input, bytelen) == bytelen incompressible_fp.close() def get_current_size(): return os.stat(filename).st_size target_size = size - 50 * 1024 # fudge factor, compensate for gpg buffering data_size = target_size - max_footer_size file = GPGFile(True, path.Path(filename), profile) at_end_of_blockiter = 0 try: while True: bytes_to_go = data_size - get_current_size() if bytes_to_go < block_iter.get_read_size(): break try: data = block_iter.__next__().data except StopIteration: at_end_of_blockiter = 1 break file.write(data) file.write(block_iter.get_footer()) if not at_end_of_blockiter: # don't pad last volume cursize = get_current_size() if cursize < target_size: top_off(target_size - cursize, file) file.close() return at_end_of_blockiter except Exception: # ensure that GPG processing terminates file.close() raise
[docs]def GzipWriteFile(block_iter, filename, size=200 * 1024 * 1024, gzipped=True): u""" Write gzipped compressed file of given size This is like the earlier GPGWriteFile except it writes a gzipped file instead of a gpg'd file. This function is somewhat out of place, because it doesn't deal with GPG at all, but it is very similar to GPGWriteFile so they might as well be defined together. The input requirements on block_iter and the output is the same as GPGWriteFile (returns true if wrote until end of block_iter). """ class FileCounted(object): u""" Wrapper around file object that counts number of bytes written """ def __init__(self, fileobj): self.fileobj = fileobj self.byte_count = 0 def write(self, buf): result = self.fileobj.write(buf) self.byte_count += len(buf) return result def close(self): return self.fileobj.close() file_counted = FileCounted(open(filename, u"wb")) # if gzipped wrap with GzipFile else plain file out if gzipped: outfile = gzip.GzipFile(None, u"wb", 6, file_counted) else: outfile = file_counted at_end_of_blockiter = 0 while True: bytes_to_go = size - file_counted.byte_count if bytes_to_go < block_iter.get_read_size(): break try: new_block = next(block_iter) except StopIteration: at_end_of_blockiter = 1 break outfile.write(new_block.data) assert not outfile.close() and not file_counted.close() return at_end_of_blockiter
[docs]def PlainWriteFile(block_iter, filename, size=200 * 1024 * 1024, gzipped=False): u""" Write plain uncompressed file of given size This is like the earlier GPGWriteFile except it writes a gzipped file instead of a gpg'd file. This function is somewhat out of place, because it doesn't deal with GPG at all, but it is very similar to GPGWriteFile so they might as well be defined together. The input requirements on block_iter and the output is the same as GPGWriteFile (returns true if wrote until end of block_iter). """ return GzipWriteFile(block_iter, filename, size, gzipped)
[docs]def get_hash(hash, path, hex=1): # pylint: disable=redefined-builtin u""" Return hash of path hash should be "MD5" or "SHA1". The output will be in hexadecimal form if hex is true, and in text (base64) otherwise. """ # assert path.isreg() fp = path.open(u"rb") if hash == u"SHA1": hash_obj = sha1() elif hash == u"MD5": hash_obj = md5() else: assert 0, u"Unknown hash %s" % (hash,) while 1: buf = fp.read(blocksize) if not buf: break hash_obj.update(buf) assert not fp.close() if hex: return hash_obj.hexdigest() else: return hash_obj.digest()