gpgfs/gpgfs.py

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2014-04-27 22:43:14 +02:00
#!/usr/bin/env python
import fuse # fusepy
import gnupg # python-gnupg
import zlib
from errno import ENOENT, EACCES, ENOSYS, ENODATA
import stat
from binascii import hexlify
import os
import sys
import logging
import struct
import time
from cStringIO import StringIO
magic = 'GPGFS1\n'
def decrypt(gpg, path):
data = file(path).read()
if not data:
return data
res = gpg.decrypt(data)
if not res.ok:
raise IOError, "decryption failed, %s" % path
data = zlib.decompress(res.data)
return data
def encrypt(gpg, keyid, path, data):
data = zlib.compress(data, 1)
res = gpg.encrypt(data, keyid, armor=False)
if not res.ok:
raise IOError, "encryption failed, keyid %s, path %s" % (keyid, path)
with file(path, 'w') as fd:
fd.write(res.data)
class Entry:
'''
Filesystem object, either file or directory.
'''
def __init__(self, **kwargs):
for k,v in kwargs.iteritems():
setattr(self, k, v)
# entry types:
ENT_FILE = 0
ENT_DIR = 1
def read_index(gpg, path):
data = decrypt(gpg, path)
buf = StringIO(data)
if buf.read(len(magic)) != magic:
raise IOError, 'index parse error: %s' % path
read_atom(buf)
root = Entry(**read_dict(buf))
return root
def write_index(gpg, keyid, path, root):
buf = StringIO()
buf.write(magic)
header = ''
write_atom(buf, header)
write_dict(buf, root)
encrypt(gpg, keyid, path, buf.getvalue())
def write_dict(fd, dct):
# breadth-first
children = []
buf = StringIO()
if not isinstance(dct, dict):
dct = dct.__dict__
for key in dct:
write_atom(buf, key.encode('utf8'))
val = dct[key]
if isinstance(val, dict):
buf.write('D')
children.append(val)
elif isinstance(val, Entry):
buf.write('E')
children.append(val)
elif isinstance(val, int):
buf.write('I')
buf.write(struct.pack('<I', val))
elif isinstance(val, str):
buf.write('S')
write_atom(buf, val)
elif isinstance(val, unicode):
buf.write('U')
write_atom(buf, val.encode('utf8'))
else:
raise TypeError, val
write_atom(fd, buf.getvalue())
for c in children:
write_dict(fd, c)
def read_dict(fd):
dct = {}
buf = read_atom(fd)
buflen = len(buf)
buf = StringIO(buf)
while buf.tell() < buflen:
key = read_atom(buf).decode('utf8')
tag = buf.read(1)
if tag == 'D': val = read_dict(fd)
elif tag == 'E': val = Entry(**read_dict(fd))
elif tag == 'I': val = struct.unpack('<I', buf.read(4))[0]
elif tag == 'S': val = read_atom(buf)
elif tag == 'U': val = read_atom(buf).decode('utf8')
else: raise TypeError, tag
dct[key] = val
return dct
def write_atom(fd, atom):
assert isinstance(atom, str)
fd.write(struct.pack('<I', len(atom)))
fd.write(atom)
def read_atom(fd):
return fd.read(struct.unpack('<I', fd.read(4))[0])
class LoggingMixIn:
log = logging.getLogger('gpgfs')
def __call__(self, op, path, *args):
if op=='write':
atxt = ' '.join([repr(args[0])[:10], repr(args[1]), repr(args[2])])
else:
atxt = ' '.join(map(repr, args))
self.log.debug('-> %s %s %s', op, path, atxt)
ret = '[Unhandled Exception]'
try:
ret = getattr(self, op)(path, *args)
return ret
except OSError, e:
ret = str(e)
raise
finally:
rtxt = repr(ret)
if op=='read':
rtxt = rtxt[:10]
self.log.debug('<- %s %s', op, rtxt)
#class GpgFs(LoggingMixIn, fuse.Operations):
class GpgFs(fuse.Operations):
def __init__(self, encroot, keyid):
'''
:param encroot: Encrypted root directory
'''
self.encroot = encroot
self.keyid = keyid
#self.cache = cache
self.gpg = gnupg.GPG()
self.index_path = encroot + '/index'
if os.path.exists(self.index_path):
self.root = read_index(self.gpg, self.index_path)
else:
self.root = Entry(type=ENT_DIR, children={},
st_mtime=int(time.time()),
st_ctime=int(time.time()))
self._write_index()
logging.info('created %s', self.index_path)
self.fd = 0
self.write_path = None
self.write_buf = []
self.write_pos = 0
self.write_dirty = False
def _write_index(self):
write_index(self.gpg, self.keyid, self.index_path, self.root)
def _find(self, path, parent=False):
assert path.startswith('/')
if path == '/':
return self.root
node = self.root
path = path[1:].split('/')
if parent:
path = path[:-1]
for name in path:
node = node.children[name]
return node
def chmod(self, path, mode):
raise fuse.FuseOSError(ENOSYS)
def chown(self, path, uid, gid):
raise fuse.FuseOSError(ENOSYS)
def create(self, path, mode):
encpath = hexlify(os.urandom(20))
encpath = encpath[:2] + '/' + encpath[2:]
dir = self._find(path, parent=True)
path = path.rsplit('/', 1)[-1]
assert path not in dir.children
dir.children[path] = Entry(type=ENT_FILE, path=encpath, st_size=0)
logging.debug('new path %s => %s', path, encpath)
encdir = self.encroot + '/' + encpath[:2]
if not os.path.exists(encdir):
os.mkdir(encdir, 0755)
with file(self.encroot + '/' + encpath, 'w'):
pass
self._write_index()
self.fd += 1
return self.fd
def flush(self, path, fh):
logging.debug('flush %s', path)
if not (path is not None and
path == self.write_path and self.write_dirty):
return 0
ent = self._find(path)
encpath = self.encroot + '/' + ent.path
buf = ''.join(self.write_buf)
encrypt(self.gpg, self.keyid, encpath, buf)
ent.st_size = len(buf)
self._write_index()
self.write_buf = [buf]
self.write_dirty = False
return 0
def getattr(self, path, fh = None):
try:
ent = self._find(path)
except KeyError:
raise fuse.FuseOSError(ENOENT)
if ent.type == ENT_DIR:
return dict(st_mode = stat.S_IFDIR | 0755, st_size = 0,
st_ctime = ent.st_ctime, st_mtime = ent.st_mtime,
st_atime = 0, st_nlink = 3)
encpath = self.encroot + '/' + ent.path
s = os.stat(encpath)
return dict(st_mode = s.st_mode, st_size = ent.st_size,
st_atime = s.st_atime, st_mtime = s.st_mtime,
st_ctime = s.st_ctime, st_nlink = s.st_nlink)
def getxattr(self, path, name, position = 0):
raise fuse.FuseOSError(ENODATA) # ENOATTR
def listxattr(self, path):
return []
def mkdir(self, path, mode):
dir = self._find(path, parent=True)
path = path.rsplit('/', 1)[-1]
assert path not in dir.children
dir.children[path] = Entry(type=ENT_DIR, children={},
st_mtime=int(time.time()),
st_ctime=int(time.time()))
self._write_index()
def open(self, path, flags):
return 0
def read(self, path, size, offset, fh):
ent = self._find(path)
assert ent.type == ENT_FILE
encpath = self.encroot + '/' + ent.path
data = decrypt(self.gpg, encpath)
return data[offset:offset + size]
def readdir(self, path, fh):
dir = self._find(path)
return ['.', '..'] + list(dir.children)
def readlink(self, path):
raise fuse.FuseOSError(ENOSYS)
def removexattr(self, path, name):
raise fuse.FuseOSError(ENOSYS)
def rename(self, old, new):
raise fuse.FuseOSError(ENOSYS)
def rmdir(self, path):
raise fuse.FuseOSError(ENOSYS)
def setxattr(self, path, name, value, options, position = 0):
raise fuse.FuseOSError(ENOSYS)
def statfs(self, path):
raise fuse.FuseOSError(ENOSYS)
def symlink(self, target, source):
raise fuse.FuseOSError(ENOSYS)
def truncate(self, path, length, fh = None):
raise fuse.FuseOSError(ENOSYS)
def unlink(self, path, times = None):
raise fuse.FuseOSError(ENOSYS)
def utimens(self, path, times = None):
raise fuse.FuseOSError(ENOSYS)
def write(self, path, data, offset, fh):
ent = self._find(path)
encpath = self.encroot + '/' + ent.path
if path != self.write_path:
self.flush(self.write_path, None)
buf = decrypt(self.gpg, encpath)
self.write_buf = [buf]
self.write_pos = len(buf)
self.write_path = path
if offset == self.write_pos:
self.write_buf.append(data)
self.write_pos += len(data)
else:
buf = ''.join(self.write_buf)
buf = buf[:offset] + data + buf[offset + len(data):]
self.write_buf = [buf]
self.write_pos = len(buf)
self.write_dirty = True
return len(data)
if __name__ == '__main__':
if len(sys.argv) != 4:
sys.stderr.write('Usage: gpgfs <gpg_keyid> <encrypted_root> <mountpoint>\n')
sys.exit(1)
logging.basicConfig(level=logging.DEBUG)
logging.getLogger('gnupg').setLevel(logging.INFO)
fs = GpgFs(sys.argv[2], sys.argv[1])
fuse.FUSE(fs, sys.argv[3], foreground=True)