# Copyright (C) 2012-2022 Germar Reitze, Taylor Raack
#
# This program 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.
#
# This program 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 this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
import os
import subprocess
import string
import random
import tempfile
import socket
import re
import atexit
import signal
from pathlib import Path
from time import sleep
import logger
import tools
import password_ipc
from mount import MountControl
from exceptions import MountException, NoPubKeyLogin, KnownHost
import bcolors
import version
[docs]
class SSH(MountControl):
"""
This is a backend for the mount API :py:class:`mount.MountControl`.
This will mount the remote path with ``sshfs``, prepare the remote path and
check that everything is set up correctly for `Back In Time` to run
snapshots through SSH.
This class will only mount the remote path. The real takeSnapshot process
will use rsync over ssh. Other commands run remote over ssh.
Args:
cfg (config.Config): current config
(handled by inherited
:py:class:`mount.MountControl`)
user (str): User name on remote host
host (str): Name or IP Address of remote host
port (int): Port used by SSHd on remote host
path (str): remote path where snapshots are stored. Can be
either relative from remote users homedir or
an absolute path
cipher (str): Cipher used to encrypt the network transfer
private_key_file (str): Private key which is able to log on with
Public/Private Key-Method on remote host
nice (bool): use ``nice -n 19`` to run commands with
low CPU priority on remote host
ionice (bool): use ``ionice -c2 -n7`` to run commands with
low IO priority on remote host
nocache (bool): use ``nocache`` to deactivate RAM caching of
files on remote host
password (str): password to unlock the private key
profile_id (str): profile ID that should be used
(handled by inherited
:py:class:`mount.MountControl`)
hash_id (str): crc32 hash used to identify
identical mountpoints
(handled by inherited
:py:class:`mount.MountControl`)
tmp_mount (bool): if ``True`` mount to a temporary destination
(handled by inherited
:py:class:`mount.MountControl`)
parent (QWidget): parent widget for QDialogs or ``None`` if there
is no parent (handled by
inherited :py:class:`mount.MountControl`)
symlink (bool): if ``True`` set symlink to mountpoint
(handled by
inherited :py:class:`mount.MountControl`)
mode (str): one of ``local``, ``local_encfs``, ``ssh`` or
``ssh_encfs`` (handled by inherited
:py:class:`mount.MountControl`)
hash_collision (int): global value used to prevent hash collisions
on mountpoints (handled by inherited
:py:class:`mount.MountControl`)
Note:
All Arguments are optional. Default values will be fetched from
:py:class:`config.Config`. But after changing Settings we need to test
the new values **before** storing them into :py:class:`config.Config`.
This is why all values will be added as arguments.
"""
def __init__(self, *args, **kwargs):
# init MountControl
super(SSH, self).__init__(*args, **kwargs)
# Workaround for linters
self.user = None
self.host = None
self.port = None
self.cipher = None
self.proxy_user = None
self.proxy_host = None
self.proxy_port = None
self.nice = None
self.ionice = None
self.nocache = None
self.private_key_file = None
self.password = None
self.setattrKwargs(
'user', self.config.sshUser(self.profile_id), **kwargs)
self.setattrKwargs(
'host', self.config.sshHost(self.profile_id), **kwargs)
self.setattrKwargs(
'port', self.config.sshPort(self.profile_id), **kwargs)
self.setattrKwargs(
'path', self.config.sshSnapshotsPath(self.profile_id), **kwargs)
self.setattrKwargs(
'cipher', self.config.sshCipher(self.profile_id), **kwargs)
self.setattrKwargs(
'private_key_file',
self.config.sshPrivateKeyFile(self.profile_id), **kwargs)
self.setattrKwargs(
'proxy_user', self.config.sshProxyUser(self.profile_id), **kwargs)
self.setattrKwargs(
'proxy_host', self.config.sshProxyHost(self.profile_id), **kwargs)
self.setattrKwargs(
'proxy_port', self.config.sshProxyPort(self.profile_id), **kwargs)
self.setattrKwargs(
'nice',
self.config.niceOnRemote(self.profile_id), store=False, **kwargs)
self.setattrKwargs(
'ionice',
self.config.ioniceOnRemote(self.profile_id), store=False, **kwargs)
self.setattrKwargs(
'nocache',
self.config.nocacheOnRemote(self.profile_id),
store=False,
**kwargs)
self.setattrKwargs('password', None, store=False, **kwargs)
if not self.path:
self.path = './'
self.setDefaultArgs()
# config strings used in ssh-calls
self.user_host_path \
= '%s@%s:%s' % (self.user,
tools.escapeIPv6Address(self.host),
self.path)
self.user_host = '%s@%s' % (self.user, self.host)
self.mountproc = 'sshfs'
self.symlink_subfolder = None
self.log_command = '%s: %s' % (self.mode, self.user_host_path)
self.private_key_fingerprint = sshKeyFingerprint(self.private_key_file)
if not self.private_key_fingerprint:
logger.warning('Couldn\'t get fingerprint for private '
'key %(path)s. '
'Most likely because the public key %(path)s.pub '
'wasn\'t found. Using fallback to private keys '
'path instead. But this can make troubles with '
'passphrase-less keys.'
% {'path': self.private_key_file},
self)
self.private_key_fingerprint = self.private_key_file
self.unlockSshAgent()
[docs]
def _mount(self):
"""
Backend mount method. This will call ``sshfs`` to mount the remote
path.
Raises:
exceptions.MountException: if mount wasn't successful
"""
sshfs = [self.mountproc]
sshfs += self.config.sshDefaultArgs(self.profile_id)
sshfs += ['-p', str(self.port)]
if not self.cipher == 'default':
sshfs.extend(['-o', 'Ciphers=%s' % self.cipher])
sshfs.extend(['-o', 'idmap=user',
'-o', 'cache_dir_timeout=2',
'-o', 'cache_stat_timeout=2'])
sshfs.extend([self.user_host_path, self.currentMountpoint])
# bugfix: sshfs doesn't mount if locale in LC_ALL is not available on
# remote host
# LANG or other environment variable are no problem.
env = os.environ.copy()
if 'LC_ALL' in list(env.keys()):
env['LC_ALL'] = 'C'
logger.debug('Call mount command: %s'
% ' '.join(sshfs),
self)
# SSH Proxy (aka Jump host)
if self.proxy_host:
sshfs.extend([
'-o',
'ssh_command=ssh -J '
f'{self.proxy_user}@{self.proxy_host}:{self.proxy_port}'
])
logger.debug(f'Execute SSHFS command {sshfs}.')
proc = subprocess.Popen(sshfs,
env=env,
stdout=subprocess.DEVNULL,
stderr=subprocess.PIPE,
universal_newlines=True)
err = proc.communicate()[1]
if proc.returncode == 0:
return
raise MountException(
"{}\n\n{}".format(
_("Can't mount {sshfs}").format(sshfs=" ".join(sshfs)),
err
)
)
[docs]
def preMountCheck(self, first_run=False):
"""
Check that everything is prepared and ready for successfully mount the
remote path. Default is to run a light version of checks which will
only make sure the remote host is online, ``sshfs`` is installed and
the remote folder is available.
After changing settings this should be run with ``first_run = True``
to run a full check with all tests.
Args:
first_run (bool): run a full test with all checks
Raises:
exceptions.MountException: if one test failed an we can not mount
the remote path
"""
self.checkPingHost()
self.checkFuse()
if first_run:
self.unlockSshAgent(force=True)
self.checkKnownHosts()
self.checkLogin()
if first_run:
self.checkCipher()
self.checkRemoteFolder()
if first_run:
self.checkRemoteCommands()
return True
[docs]
def startSshAgent(self):
"""
Start a new ``ssh-agent`` if it is not already running.
Raises:
exceptions.MountException: if starting ``ssh-agent`` failed
"""
SOCK = 'SSH_AUTH_SOCK'
PID = 'SSH_AGENT_PID'
if os.getenv(SOCK, '') and os.getenv(PID, ''):
logger.debug(
'ssh-agent already running. Skip starting a new one.', self)
return
sshAgent = tools.which('ssh-agent')
if not sshAgent:
raise MountException(
_('ssh-agent not found. Please make sure it is installed.'))
if isinstance(sshAgent, str):
sshAgent = [sshAgent, ]
sa = subprocess.Popen(sshAgent,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
universal_newlines=True)
out, err = sa.communicate()
if sa.returncode:
raise MountException(
'Failed to start ssh-agent: [{}] {}'
.format(sa.returncode, err))
m = re.match(r'.*{}(?:=|\s)([^;]+);.*{}(?:=|\s)(\d+);'
.format(SOCK, PID),
out,
re.DOTALL | re.MULTILINE)
if m:
logger.debug('ssh-agent started successful: {}={} | {}={}'
.format(SOCK, m.group(1), PID, m.group(2)), self)
os.environ[SOCK] = m.group(1)
os.environ[PID] = m.group(2)
atexit.register(os.kill, int(m.group(2)), signal.SIGKILL)
else:
raise MountException(
'No matching output from ssh-agent: {} | {}'.format(out, err))
[docs]
def unlockSshAgent(self, force=False):
"""
Unlock the private key in ``ssh-agent`` which will provide it for
all other commands. The password to unlock the key will be provided
by ``backintime-askpass``.
Args:
force (bool): force to unlock the key by removing it
first and add it again to make sure,
the given values are correct
Raises:
exceptions.MountException: if unlock failed
"""
self.startSshAgent()
env = os.environ.copy()
env['SSH_ASKPASS'] = 'backintime-askpass'
env['ASKPASS_PROFILE_ID'] = self.profile_id
env['ASKPASS_MODE'] = self.mode
if force:
# remove private key first so we can check if the given
# password is valid
logger.debug(
'Remove private key %s from ssh agent' % self.private_key_file,
self)
proc = subprocess.Popen(['ssh-add', '-d', self.private_key_file],
stdin=subprocess.DEVNULL,
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
universal_newlines=True)
proc.communicate()
proc = subprocess.Popen(['ssh-add', '-l'],
stdout=subprocess.PIPE,
universal_newlines=True)
output = proc.communicate()[0]
if force or not output.find(self.private_key_fingerprint) >= 0:
logger.debug(
'Add private key %s to ssh agent' % self.private_key_file,
self)
password_available = any([
self.config.passwordSave(self.profile_id),
self.config.passwordUseCache(self.profile_id),
not self.password is None
])
logger.debug('Password available: %s' % password_available, self)
if not password_available and not tools.checkXServer():
# we need to unlink stdin from ssh-add in order to make it
# use our own backintime-askpass.
# But because of this we can NOT use getpass inside
# backintime-askpass if password is not saved and there is no
# x-server.
# So, let's just keep ssh-add asking for the password in
# that case.
alarm = tools.Alarm()
alarm.start(10)
try:
proc = subprocess.call(['ssh-add', self.private_key_file])
alarm.stop()
except tools.Timeout:
pass
else:
if self.password:
logger.debug('Provide password through temp FIFO', self)
thread = password_ipc.TempPasswordThread(self.password)
env['ASKPASS_TEMP'] = thread.temp_file
thread.start()
proc = subprocess.Popen(['ssh-add', self.private_key_file],
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
env=env,
preexec_fn=os.setsid,
universal_newlines=True)
output, error = proc.communicate()
if proc.returncode:
logger.error('Failed to unlock SSH private key %s: %s'
% (self.private_key_file, error),
self)
if self.password:
thread.stop()
proc = subprocess.Popen(['ssh-add', '-l'],
stdout=subprocess.PIPE,
universal_newlines=True)
output = proc.communicate()[0]
if not output.find(self.private_key_fingerprint) >= 0:
logger.debug(
'Was not able to unlock private key %s' %
self.private_key_file, self)
raise MountException(
_('Could not unlock ssh private key. Wrong password '
'or password not available for cron.'))
else:
logger.debug('Private key %s is already unlocked in ssh agent'
% self.private_key_file, self)
[docs]
def checkLogin(self):
"""
Try to login to remote host with public/private-key-method
(passwordless).
Raises:
exceptions.NoPubKeyLogin: if login failed
"""
logger.debug('Check login', self)
# Custom SSH arguments
custom_ssh_args = [
'-o',
'PreferredAuthentications=publickey',
'-p', str(self.port),
self.user_host
]
# Create SSH command
ssh = self.config.sshCommand(cmd=['exit'],
custom_args=custom_ssh_args,
port=False,
user_host=False,
nice=False,
ionice=False,
profile_id=self.profile_id)
proc = subprocess.Popen(ssh,
stdout=subprocess.DEVNULL,
stderr=subprocess.PIPE,
universal_newlines=True)
err = proc.communicate()[1]
if proc.returncode:
raise NoPubKeyLogin(
'Password-less authentication for %(user)s@%(host)s '
'failed. Look at \'man backintime\' for further '
'instructions.' % {
'user': self.user,
'host': self.host}
+ '\n\n' + err)
[docs]
def checkCipher(self):
"""
Try to login to remote host with the chosen cipher. This should make
sure both `localhost` and the remote host support the chosen cipher.
Raises:
exceptions.MountException: if login with the cipher failed
"""
if not self.cipher == 'default':
logger.debug('Check cipher', self)
ssh = self.config.sshCommand(cmd=['exit'],
custom_args=[
'-o',
'Ciphers=%s' % self.cipher,
'-p',
str(self.port),
self.user_host
],
port=False,
cipher=False,
user_host=False,
nice=False,
ionice=False,
profile_id=self.profile_id)
proc = subprocess.Popen(ssh,
stdout=subprocess.DEVNULL,
stderr=subprocess.PIPE,
universal_newlines=True)
err = proc.communicate()[1]
if proc.returncode:
logger.debug(
'Ciper %s is not supported' %
self.config.SSH_CIPHERS[self.cipher], self)
msg = _('Cipher {cipher} failed for {host}.').format(
cipher=self.config.SSH_CIPHERS[self.cipher],
host=self.host)
raise MountException(f'{msg}:\n{err}')
[docs]
def benchmarkCipher(self, size=40):
"""
Rudimental benchmark to compare transfer speed of all available
ciphers.
Args:
size (int): size of the testfile in MiB
"""
temp = tempfile.mkstemp()[1]
print('create random data file')
subprocess.call([
'dd',
'if=/dev/urandom',
'of=%s' % temp,
'bs=1M',
'count=%s' % size
])
keys = list(self.config.SSH_CIPHERS.keys())
keys.sort()
for cipher in keys:
if cipher == 'default':
continue
print('%s%s:%s' % (bcolors.BOLD, cipher, bcolors.ENDC))
for i in range(2):
# scp uses -P instead of -p for port
subprocess.call([
'scp',
'-P',
str(self.port),
'-c',
cipher,
temp,
self.user_host_path
])
ssh = self.config.sshCommand(
cmd=['rm', os.path.join(self.path, os.path.basename(temp))],
custom_args=['-p', str(self.port), self.user_host],
port=False,
cipher=False,
user_host=False,
nice=False,
ionice=False,
profile_id=self.profile_id)
subprocess.call(ssh)
os.remove(temp)
[docs]
def checkKnownHosts(self):
"""
Check if the remote host is in current users ``known_hosts`` file.
Raises:
exceptions.KnownHost: if the remote host wasn't found
in ``known_hosts`` file
"""
logger.debug('Check known hosts file', self)
for host in (self.host, '[%s]:%s' % (self.host, self.port)):
proc = subprocess.Popen(['ssh-keygen', '-F', host],
stdout=subprocess.PIPE,
universal_newlines=True)
# subprocess.check_output doesn't exist
# in Python 2.6 (Debian squeeze default)
output = proc.communicate()[0]
if output.find('Host %s found' % host) >= 0:
logger.debug(
'Host %s was found in known hosts file' % host, self)
return True
logger.debug('Host %s is not in known hosts file' % self.host, self)
raise KnownHost('%s not found in ssh_known_hosts.' % self.host)
[docs]
def checkRemoteFolder(self):
"""
Check the remote path. If the remote path doesn't exist this will
create it. If it already exist this will check, that it is a folder
and has correct permissions.
Raises:
exceptions.MountException: if remote path couldn't be created or
doesn't have correct permissions.
"""
logger.debug('Check remote folder', self)
cmd = 'd=0;'
# path doesn't exist. set d=1 to indicate
cmd += 'test -e "%s" || d=1;' % self.path
# create path, get errorcode from mkdir
cmd += 'test $d -eq 1 && mkdir "%s"; err=$?;' % self.path
# return errorcode from mkdir
cmd += 'test $d -eq 1 && exit $err;'
# path is no directory
cmd += 'test -d "%s" || exit 11;' % self.path
# path is not writable
cmd += 'test -w "%s" || exit 12;' % self.path
# path is not executable
cmd += 'test -x "%s" || exit 13;' % self.path
# everything is fine
cmd += 'exit 20'
ssh = self.config.sshCommand(
cmd=[cmd],
custom_args=['-p', str(self.port), self.user_host],
port=False,
user_host=False,
nice=False,
ionice=False,
profile_id=self.profile_id)
logger.debug('Call command: %s' % ' '.join(ssh), self)
proc = subprocess.Popen(ssh,
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL)
proc.communicate()
if proc.returncode:
logger.debug('Command returncode: %s' % proc.returncode, self)
if proc.returncode == 20:
# clean exit
pass
elif proc.returncode == 11:
raise MountException('{}:\n{}'.format(
_('Remote path exists but is not a directory.'),
self.path))
elif proc.returncode == 12:
raise MountException('{}:\n{}'.format(
_('Remote path is not writable.'),
self.path))
elif proc.returncode == 13:
raise MountException('{}:\n{}'.format(
_('Remote path is not executable.'),
self.path))
else:
raise MountException('{}:\n{}'.format(
_("Couldn't create remote path."),
self.path))
else:
# returncode is 0
logger.info('Create remote folder %s' % self.path, self)
[docs]
def checkPingHost(self):
"""
Check if the remote host is online. Other than methods name may let
suppose
this does not use Ping (``ICMP``) but try to open a connection to
the configured port on the remote host. In this way it will even work
on remote hosts which have ``ICMP`` disabled.
If connection failed it will retry five times before failing.
Raises:
exceptions.MountException: if connection failed most probably
because remote host is offline
"""
if not self.config.sshCheckPingHost(self.profile_id):
return
ping_host = self.proxy_host or self.host
ping_port = self.proxy_port or self.port
logger.debug(f'Check ping host "{ping_host}:{ping_port}"', self)
versionString = 'SSH-2.0-backintime_{}\r\n'.format(
version.__version__).encode()
count = 0
while count < 5:
try:
with socket.create_connection(
(ping_host, ping_port), 2.0) as s:
result = s.connect_ex(s.getpeername())
s.sendall(versionString)
except: # Refactor: too broad exception
result = -1
if result == 0:
logger.debug(
f'Host "{ping_host}:{ping_port}" is available', self)
return
count += 1
sleep(0.2)
if result != 0:
proxy_msg = f' via proxy "{ping_host}:{ping_port}"' \
if self.proxy_host else ''
msg = f'Ping {self.host}{proxy_msg} failed. ' \
'Host is down or wrong address.'
logger.debug(msg, self)
raise MountException(msg)
[docs]
def checkRemoteCommands(self, retry=False):
"""
Try out all relevant commands used by `Back In Time` on the remote
host to make sure snapshots will be successful with the remote host.
This will also check that hard-links are supported on the remote host.
This check can be disabled
with :py:func:`config.Config.sshCheckCommands`
Args:
retry (bool): retry to run the commands if it failed
because the command string was to long
Raises:
exceptions.MountException: if a command is not supported on
remote host or if hard-links are not
supported
"""
if not self.config.sshCheckCommands():
return
logger.debug('Check remote commands', self)
def maxArg():
if retry:
raise MountException(
"Checking commands on remote host didn't return any "
"output. We already checked the maximum argument length "
"but it seems like there is another problem")
logger.warning(
'Looks like the command was to long for remote SSHd. '
'We will test max arg length now and retry.',
self)
import sshMaxArg
max_arg_size = sshMaxArg.probe_max_ssh_command_size(self.config)
sshMaxArg.report_result(self.host, max_arg_size)
self.config.setSshMaxArgLength(max_arg_size, self.profile_id)
return self.checkRemoteCommands(retry=True)
remote_tmp_dir_1 = os.path.join(self.path, 'tmp_%s' % self.randomId())
remote_tmp_dir_2 = os.path.join(self.path, 'tmp_%s' % self.randomId())
with tempfile.TemporaryDirectory() as tmp:
tmp_file = os.path.join(tmp, 'a')
with open(tmp_file, 'wt') as f:
f.write('foo')
# check rsync
rsync1 = tools.rsyncPrefix(
self.config, no_perms=False, progress=False)
rsync1.append(tmp_file)
rsync1.append('%s@%s:%s/' % (
self.user,
tools.escapeIPv6Address(self.host),
remote_tmp_dir_1))
# check remote rsync hard-link support
rsync2 = tools.rsyncPrefix(
self.config, no_perms=False, progress=False)
rsync2.append(
'--link-dest=../%s' % os.path.basename(remote_tmp_dir_1))
rsync2.append(tmp_file)
rsync2.append('%s@%s:%s/' % (
self.user,
tools.escapeIPv6Address(self.host),
remote_tmp_dir_2))
for cmd in (rsync1, rsync2):
logger.debug('Check rsync command: %s' % cmd, self)
proc = subprocess.Popen(cmd,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
universal_newlines=True)
out, err = proc.communicate()
if err or proc.returncode:
logger.debug(f'rsync command returned error: {err}', self)
raise MountException(
"Remote host {host} doesn't support '{command}:\n"
"{err}\n"
"Look at 'man backintime' for further instructions."
.format(
host=self.host,
command=cmd,
err=err)
)
# check cp chmod find and rm
head = 'tmp1="%s"; tmp2="%s"; ' % (remote_tmp_dir_1, remote_tmp_dir_2)
# first define a function to clean up and exit
head += 'cleanup(){ '
head += 'test -e "$tmp1/a" && rm "$tmp1/a" >/dev/null 2>&1; '
head += 'test -e "$tmp2/a" && rm "$tmp2/a" >/dev/null 2>&1; '
head += 'test -e smr.lock && rm smr.lock >/dev/null 2>&1; '
head += 'test -e "$tmp1" && rmdir "$tmp1" >/dev/null 2>&1; '
head += 'test -e "$tmp2" && rmdir "$tmp2" >/dev/null 2>&1; '
head += 'test -n "$tmp3" && test -e "$tmp3" && rmdir "$tmp3" >/dev/null 2>&1; '
head += 'exit $1; }; '
tail = []
# list inodes
cmd = 'ls -i "$tmp1/a"; ls -i "$tmp2/a"; '
tail.append(cmd)
# try nice -n 19
if self.nice:
cmd = 'echo \"nice -n 19\"; nice -n 19 true >/dev/null; err_nice=$?; '
cmd += 'test $err_nice -ne 0 && cleanup $err_nice; '
tail.append(cmd)
# try ionice -c2 -n7
if self.ionice:
cmd = 'echo \"ionice -c2 -n7\"; ionice -c2 -n7 true >/dev/null; err_nice=$?; '
cmd += 'test $err_nice -ne 0 && cleanup $err_nice; '
tail.append(cmd)
# try nocache
if self.nocache:
cmd = 'echo \"nocache\"; nocache true >/dev/null; err_nocache=$?; '
cmd += 'test $err_nocache -ne 0 && cleanup $err_nocache; '
tail.append(cmd)
# try screen, bash and flock used by smart-remove running in background
if self.config.smartRemoveRunRemoteInBackground(self.profile_id):
cmd = 'echo \"screen -d -m bash -c ...\"; screen -d -m bash -c \"true\" >/dev/null; err_screen=$?; '
cmd += 'test $err_screen -ne 0 && cleanup $err_screen; '
tail.append(cmd)
cmd = 'echo \"(flock -x 9) 9>smr.lock\"; bash -c \"(flock -x 9) 9>smr.lock\" >/dev/null; err_flock=$?; '
cmd += 'test $err_flock -ne 0 && cleanup $err_flock; '
tail.append(cmd)
cmd = 'echo \"rmdir \\$(mktemp -d)\"; tmp3=$(mktemp -d); test -z "$tmp3" && cleanup 1; rmdir $tmp3 >/dev/null; err_rmdir=$?; '
cmd += 'test $err_rmdir -ne 0 && cleanup $err_rmdir; '
tail.append(cmd)
# if we end up here, everything should be fine
cmd = 'echo \"done\"; cleanup 0'
tail.append(cmd)
maxLength = self.config.sshMaxArgLength(self.profile_id)
additionalChars = len('echo ""') \
+ len(self.config.sshPrefixCmd(self.profile_id, cmd_type=str))
output = ''
err = ''
returncode = 0
for cmd in tools.splitCommands(tail,
head=head,
maxLength=maxLength-additionalChars):
if cmd.endswith('; '):
cmd += 'echo ""'
c = self.config.sshCommand(
cmd=[cmd],
custom_args=['-p', str(self.port), self.user_host],
port=False,
user_host=False,
nice=False,
ionice=False,
profile_id=self.profile_id)
try:
logger.debug('Call command: %s' % ' '.join(c), self)
proc = subprocess.Popen(c,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
universal_newlines=True)
ret = proc.communicate()
except OSError as e:
# Argument list too long
if e.errno == 7:
logger.debug(
'Argument list too long (Python exception)', self)
return maxArg()
else:
raise
logger.debug('Command stdout: %s' % ret[0], self)
logger.debug('Command stderr: %s' % ret[1], self)
logger.debug('Command returncode: %s' % proc.returncode, self)
output += ret[0].strip('\n') + '\n'
err += ret[1].strip('\n') + '\n'
returncode += proc.returncode
if proc.returncode:
break
output_split = output.strip('\n').split('\n')
while True:
if output_split and not output_split[-1]:
output_split = output_split[:-1]
else:
break
if not output_split:
return maxArg()
if returncode or not output_split[-1].startswith('done'):
for command in ('rm', 'nice', 'ionice',
'nocache', 'screen', '(flock'):
if output_split[-1].startswith(command):
command = f"'{output_split[-1]}':\n{err}"
msg = _("Remote host {host} doesn't support {command}") \
.format(host=self.host, command=command)
raise MountException('{}\n{}'.format(
msg,
_("Look at 'man backintime' for further instructions")
)
)
msg = _('Check commands on host {host} returned unknown error') \
.format(host=self.host)
raise MountException('{}:\n{}n{}'.format(
msg,
err,
_("Look at 'man backintime' for further instructions")))
inodes = []
for tmp in (remote_tmp_dir_1, remote_tmp_dir_2):
for line in output_split:
m = re.match(r'^(\d+).*?%s' % tmp, line)
if m:
inodes.append(m.group(1))
logger.debug('remote inodes: ' + ' | '.join(inodes), self)
if len(inodes) == 2 and inodes[0] != inodes[1]:
raise MountException(
_("Remote host {host} doesn't support hardlinks")
.format(host=self.host))
[docs]
def randomId(self, size=6, chars=string.ascii_uppercase + string.digits):
"""
Create a random string.
Args:
size (int): length of the string
chars (str): characters used as basis for the random string
Returns:
str: random string with length ``size``
"""
return ''.join(random.choice(chars) for x in range(size))
[docs]
def sshKeyGen(keyfile):
"""
Generate a new ssh-key pair (private and public key) in ``keyfile`` and
``keyfile``.pub
Args:
keyfile (str): path for private key file
Returns:
bool: True if successful; False if ``keyfile`` already exist
or if there was an error
"""
if os.path.exists(keyfile):
logger.warning(
'SSH keyfile "{}" already exist. Skip creating a new one'
.format(keyfile))
return False
cmd = ['ssh-keygen', '-t', 'rsa', '-N', '', '-f', keyfile]
proc = subprocess.Popen(cmd,
stdout=subprocess.DEVNULL,
stderr=subprocess.PIPE,
universal_newlines=True)
out, err = proc.communicate()
if proc.returncode:
logger.error('Failed to create a new ssh-key: {}'.format(err))
else:
logger.info('Successfully created new ssh-key "{}"'.format(keyfile))
return not proc.returncode
[docs]
def sshCopyIdCommand(
pubkey,
user,
host,
port='22',
proxy_user=None,
proxy_host=None,
proxy_port='22',
cipher=None
):
"""
Generate a ssh-copy-id command to copy the given public ssh-key to a
remote host.
Args:
pubkey (str): path to the public key file
user (str): remote user
host (str): remote host
port (str): ssh port on remote host
proxy_user (str): proxy host user
proxy_host (str): proxy host
proxy_port (str): proxy host port
cipher (str): cipher used for ssh
Returns:
list: The ssh-copy-id command as a list.
Raises:
FileNotFoundError: If public key file not exist.
"""
if not Path(pubkey).exists():
msg = f'SSH public key "{pubkey}" does not exist.'
logger.error(msg)
raise FileNotFoundError(msg)
cmd = [
'ssh-copy-id',
# key file
'-i', pubkey,
# port
'-p', str(port),
]
# cipher
if cipher and cipher != 'default':
cmd.extend(['-o', 'Ciphers={}'.format(cipher)])
# proxy
if proxy_host:
proxy_jump = f'{proxy_user}@{proxy_host}:{proxy_port}'
cmd.extend(['-o', f'ProxyJump={proxy_jump}'])
cmd.append(f'{user}@{host}')
logger.debug(f'ssh-copy-id command {cmd}')
return cmd
[docs]
def sshCopyId(
pubkey,
user,
host,
port='22',
proxy_user=None,
proxy_host=None,
proxy_port=None,
askPass='backintime-askpass',
cipher=None
):
"""
Copy SSH public key ``pubkey`` to remote ``host``.
Args:
pubkey (str): path to the public key file
user (str): remote user
host (str): remote host
port (str): ssh port on remote host
askPass (str): program used to pipe password into ssh
cipher (str): cipher used for ssh
Returns:
bool: True if successful
"""
cmd = sshCopyIdCommand(
pubkey,
user,
host,
port,
proxy_user,
proxy_host,
proxy_port,
cipher
)
env = os.environ.copy()
env['SSH_ASKPASS'] = askPass
env['ASKPASS_MODE'] = 'USER'
env['ASKPASS_PROMPT'] = '{}\n{}:'.format(
_('Copy public ssh-key "{pubkey}" to remote host "{host}"').format(
pubkey=pubkey, host=host),
_('Please enter password for "{user}"').format(user=user)
)
proc = subprocess.Popen(cmd, env=env,
stdout=subprocess.DEVNULL,
stderr=subprocess.PIPE,
preexec_fn=os.setsid, # cut of ssh from current
# terminal to make it use
# backintime-askpass
universal_newlines=True)
out, err = proc.communicate()
if proc.returncode:
logger.error('Failed to copy ssh-key "{}" to "{}@{}": [{}] {}'
.format(pubkey, user, host, proc.returncode, err))
else:
logger.info('Successfully copied ssh-key "{}" to "{}@{}"'
.format(pubkey, user, host))
return not proc.returncode
[docs]
def sshKeyFingerprint(path):
"""
Get the hex fingerprint from a given ssh key.
Args:
path (str): full path to key file
Returns:
str: hex fingerprint from key
"""
if not os.path.exists(path):
return
cmd = ['ssh-keygen', '-l', '-f', path]
proc = subprocess.Popen(
cmd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
output = proc.communicate()[0]
m = re.match(r'\d+\s+(SHA256:\S+|[a-fA-F0-9:]+)\s.*',
output.decode())
if m:
return m.group(1)
[docs]
def sshHostKey(host, port='22'):
"""
Get the remote host key from ``host``.
Args:
host (str): host name or IP address
port (str): port number of remote ssh-server
Returns:
tuple: three item tuple with (fingerprint, hashed host key,
key type)
"""
for t in ('ecdsa', 'rsa'):
cmd = ['ssh-keyscan', '-t', t, '-p', port, host]
proc = subprocess.Popen(cmd,
stdout=subprocess.PIPE,
stderr=subprocess.DEVNULL)
hostKey = proc.communicate()[0].strip()
if hostKey:
break
if hostKey:
logger.debug('Found {} key for host "{}"'.format(t.upper(), host))
with tempfile.TemporaryDirectory() as tmp:
keyFile = os.path.join(tmp, 'key')
with open(keyFile, 'wb') as f:
f.write(hostKey + b'\n')
hostKeyFingerprint = sshKeyFingerprint(keyFile)
cmd = ['ssh-keygen', '-H', '-f', keyFile]
proc = subprocess.Popen(cmd,
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL)
proc.communicate()
with open(keyFile, 'rt') as f:
hostKeyHash = f.read().strip()
return (hostKeyFingerprint, hostKeyHash, t.upper())
return (None, None, None)
[docs]
def writeKnownHostsFile(key):
"""
Write host key ``key`` into `~/.ssh/known_hosts`.
Args:
key (str): host key
"""
sshDir = os.path.expanduser('~/.ssh')
knownHostFile = os.path.join(sshDir, 'known_hosts')
if not os.path.isdir(sshDir):
tools.mkdir(sshDir, 0o700)
with open(knownHostFile, 'at') as f:
logger.info('Write host key to {}'.format(knownHostFile))
f.write(key + '\n')