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from abc import ABC, abstractmethod
import re
import subprocess
from .exceptions import RemoteExecException
from . import repository
from . import ssh_remote
from . import _ssh_client
def _parse_name(name):
"""
Parse a backup name into a remote specification.
"""
# split off the username
if not '@' in name:
raise ValueError('Invalid backup name: "%s", must be of format user@host')
username, _, host = name.partition('@')
port = 22 # overridden later if specified in name
colons = host.count(':')
if colons >= 2: # IPv6 literal, possibly with port
m = re.match(r'\[(.+)\](:\d+)?', host, re.ASCII | re.IGNORECASE)
if m is not None: # [literal]:port
host, port = m.groups()
elif colons == 1: # host:port
host, _, port = host.partition(':')
return ssh_remote.SSHRemote(host, port, username)
class Target(ABC):
name = None
dirs = None
excludes = None
def __init__(self, name, dirs, excludes = None):
if excludes is None:
excludes = []
self.name = name
self.dirs = dirs
self.excludes = excludes
@abstractmethod
def save(self, data_dir):
pass
class TargetLocal(Target):
def save(self, data_dir):
cmd = ['bup', 'index', '--update', '--one-file-system']
cmd.extend(['--exclude=%s' % e for e in self.excludes])
cmd.extend(self.dirs)
res_idx = subprocess.run(cmd, capture_output = True)
cmd = ['bup', 'save', '-n', self.name] + self.dirs
res_save = subprocess.run(cmd, capture_output = True)
retcode = 0
output = b''
if res_idx.returncode != 0:
retcode = res_idx.returncode
output += res_idx.stderr + res_idx.stdout
if res_save.returncode != 0:
retcode = res_save.returncode
output += res_save.stderr + res_save.stdout
result = repository.StepResult(retcode, output)
return result
class TargetSSH(Target):
_remote = None
def __init__(self, name, dirs, excludes = None,
remote = None):
super().__init__(name, dirs, excludes)
if remote is None:
remote = _parse_name(name)
if remote.proxy_remote is not None:
raise NotImplementedError('Proxy remote not implemented')
if remote.port != 22:
raise NotImplementedError('Specifying port not implemented')
self._remote = remote
def save(self, data_dir):
cmd = ['bup', 'on', '%s@%s' % (self._remote.username, self._remote.host), 'index', '--update', '--one-file-system']
cmd.extend(['--exclude=%s' % e for e in self.excludes])
cmd.extend(self.dirs)
res_idx = subprocess.run(cmd, capture_output = True)
cmd = ['bup', 'on', '%s@%s' %(self._remote.username, self._remote.host), 'save', '-n', self.name] + self.dirs
res_save = subprocess.run(cmd, capture_output = True)
retcode = 0
output = b''
if res_idx.returncode != 0:
retcode = res_idx.returncode
output += res_idx.stderr + res_idx.stdout
if res_save.returncode != 0:
retcode = res_save.returncode
output += res_save.stderr + res_save.stdout
result = repository.StepResult(retcode, output)
return result
def _paramiko_exec_cmd(client, cmd):
res = client.exec_command(cmd)
chan = res[0].channel
out, err = res[1].read(), res[2].read()
if chan.exit_status != 0:
raise RemoteExecException('Error executing "%s"' % cmd,
chan.exit_status, err + out)
return out.decode('utf-8', errors = 'backslashreplace')
class TargetSSHLXCLVM(TargetSSH):
"""
This target backs up an LXC container that lives on its own LVM logical
volume. Requires root-capable login on the container's host.
:param SSHRemote parent_remote:
"""
_parent_remote = None
_lxc_username = None
_lxc_containername = None
def __init__(self, name, dirs, excludes = None,
target_remote = None, parent_remote = None,
lxc_username = None, lxc_containername = None,
snapshot_size = '20G'):
super().__init__(name, dirs, excludes, target_remote)
if parent_remote is None:
raise ValueError('parent_remote not specified')
if lxc_username is None:
lxc_username = parent_remote.usename
self._parent_remote = parent_remote
self._lxc_username = lxc_username
self._lxc_containername = lxc_containername
self._snapshot_size = snapshot_size
def save(self, data_dir):
with (_ssh_client.SSHConnection(self._parent_remote) as parent,
_ssh_client.SSHConnection(self._remote) as container):
# get the PID of the container's init
cmd_template = 'su -s /bin/sh -c "{command}" %s' % self._lxc_username
container_pid = _paramiko_exec_cmd(parent, cmd_template.format(
command = 'lxc-info -H -p -n %s' % self._lxc_containername)).rstrip('\n')
# get the LV/VG for the container's rootfs
container_rootfs = _paramiko_exec_cmd(parent, cmd_template.format(
command = 'lxc-info -H -c lxc.rootfs -n %s' %
self._lxc_containername))\
.rstrip('\n')\
.translate({ord(' ') : r'\040', ord('\t') : r'\011',
ord('\n') : r'\012', ord('\\') : r'\O134'})
mountline = _paramiko_exec_cmd(parent, 'grep "%s" /proc/mounts' %
container_rootfs).rstrip('\n').split()
if len(mountline) < 2 or mountline[1] != container_rootfs:
raise RemoteExecException('Invalid mount line: %s' % mountline)
lv_path = mountline[0]
lv_name, vg_name = _paramiko_exec_cmd(parent,
'lvdisplay -C --noheadings -o lv_name,vg_name ' + lv_path)\
.strip().split()
# we cannot trust any binaries located inside the container, since a
# compromised container could use them to execute arbitrary code
# with real root privileges, thus nullifying the point of
# unprivileged containers)
# so we now create a temporary
# create a read-only snapshot
snapshot_name = 'bupper_' + lv_name
_paramiko_exec_cmd(parent,
'lvcreate --permission r --snapshot -L {size} -n {name} {origin}'
.format(size = self._snapshot_size, name = snapshot_name,
origin = lv_path))
# execute the backup
try:
print(container_pid, vg_name, lv_path, snapshot_name)
finally:
# delete the snapshot
_paramiko_exec_cmd(parent, 'lvremove -f %s/%s' % (vg_name, snapshot_name))
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