# Copyright (C) 2006-2010 Robey Pointer <robey@lag.net>
# Copyright (C) 2005, 2006, 2007 Canonical Ltd
#
# 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
"""Foundation SSH support for SFTP and smart server."""
import errno
import getpass
import logging
import os
import socket
import subprocess
import sys
from bzrlib import (
config,
errors,
osutils,
trace,
ui,
)
try:
import paramiko
except ImportError, e:
# If we have an ssh subprocess, we don't strictly need paramiko for all ssh
# access
paramiko = None
else:
from paramiko.sftp_client import SFTPClient
SYSTEM_HOSTKEYS = {}
BZR_HOSTKEYS = {}
_paramiko_version = getattr(paramiko, '__version_info__', (0, 0, 0))
# Paramiko 1.5 tries to open a socket.AF_UNIX in order to connect
# to ssh-agent. That attribute doesn't exist on win32 (it does in cygwin)
# so we get an AttributeError exception. So we will not try to
# connect to an agent if we are on win32 and using Paramiko older than 1.6
_use_ssh_agent = (sys.platform != 'win32' or _paramiko_version >= (1, 6, 0))
class SSHVendorManager(object):
"""Manager for manage SSH vendors."""
# Note, although at first sign the class interface seems similar to
# bzrlib.registry.Registry it is not possible/convenient to directly use
# the Registry because the class just has "get()" interface instead of the
# Registry's "get(key)".
def __init__(self):
self._ssh_vendors = {}
self._cached_ssh_vendor = None
self._default_ssh_vendor = None
def register_default_vendor(self, vendor):
"""Register default SSH vendor."""
self._default_ssh_vendor = vendor
def register_vendor(self, name, vendor):
"""Register new SSH vendor by name."""
self._ssh_vendors[name] = vendor
def clear_cache(self):
"""Clear previously cached lookup result."""
self._cached_ssh_vendor = None
def _get_vendor_by_environment(self, environment=None):
"""Return the vendor or None based on BZR_SSH environment variable.
:raises UnknownSSH: if the BZR_SSH environment variable contains
unknown vendor name
"""
if environment is None:
environment = os.environ
if 'BZR_SSH' in environment:
vendor_name = environment['BZR_SSH']
try:
vendor = self._ssh_vendors[vendor_name]
except KeyError:
vendor = self._get_vendor_from_path(vendor_name)
if vendor is None:
raise errors.UnknownSSH(vendor_name)
vendor.executable_path = vendor_name
return vendor
return None
def _get_ssh_version_string(self, args):
"""Return SSH version string from the subprocess."""
try:
p = subprocess.Popen(args,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
**os_specific_subprocess_params())
stdout, stderr = p.communicate()
except OSError:
stdout = stderr = ''
return stdout + stderr
def _get_vendor_by_version_string(self, version, progname):
"""Return the vendor or None based on output from the subprocess.
:param version: The output of 'ssh -V' like command.
:param args: Command line that was run.
"""
vendor = None
if 'OpenSSH' in version:
trace.mutter('ssh implementation is OpenSSH')
vendor = OpenSSHSubprocessVendor()
elif 'SSH Secure Shell' in version:
trace.mutter('ssh implementation is SSH Corp.')
vendor = SSHCorpSubprocessVendor()
# As plink user prompts are not handled currently, don't auto-detect
# it by inspection below, but keep this vendor detection for if a path
# is given in BZR_SSH. See https://bugs.launchpad.net/bugs/414743
elif 'plink' in version and progname == 'plink':
# Checking if "plink" was the executed argument as Windows
# sometimes reports 'ssh -V' incorrectly with 'plink' in it's
# version. See https://bugs.launchpad.net/bzr/+bug/107155
trace.mutter("ssh implementation is Putty's plink.")
vendor = PLinkSubprocessVendor()
return vendor
def _get_vendor_by_inspection(self):
"""Return the vendor or None by checking for known SSH implementations."""
version = self._get_ssh_version_string(['ssh', '-V'])
return self._get_vendor_by_version_string(version, "ssh")
def _get_vendor_from_path(self, path):
"""Return the vendor or None using the program at the given path"""
version = self._get_ssh_version_string([path, '-V'])
return self._get_vendor_by_version_string(version,
os.path.splitext(os.path.basename(path))[0])
def get_vendor(self, environment=None):
"""Find out what version of SSH is on the system.
:raises SSHVendorNotFound: if no any SSH vendor is found
:raises UnknownSSH: if the BZR_SSH environment variable contains
unknown vendor name
"""
if self._cached_ssh_vendor is None:
vendor = self._get_vendor_by_environment(environment)
if vendor is None:
vendor = self._get_vendor_by_inspection()
if vendor is None:
trace.mutter('falling back to default implementation')
vendor = self._default_ssh_vendor
if vendor is None:
raise errors.SSHVendorNotFound()
self._cached_ssh_vendor = vendor
return self._cached_ssh_vendor
_ssh_vendor_manager = SSHVendorManager()
_get_ssh_vendor = _ssh_vendor_manager.get_vendor
register_default_ssh_vendor = _ssh_vendor_manager.register_default_vendor
register_ssh_vendor = _ssh_vendor_manager.register_vendor
def _ignore_signals():
# TODO: This should possibly ignore SIGHUP as well, but bzr currently
# doesn't handle it itself.
# <https://launchpad.net/products/bzr/+bug/41433/+index>
import signal
signal.signal(signal.SIGINT, signal.SIG_IGN)
# GZ 2010-02-19: Perhaps make this check if breakin is installed instead
if signal.getsignal(signal.SIGQUIT) != signal.SIG_DFL:
signal.signal(signal.SIGQUIT, signal.SIG_IGN)
class SocketAsChannelAdapter(object):
"""Simple wrapper for a socket that pretends to be a paramiko Channel."""
def __init__(self, sock):
self.__socket = sock
def get_name(self):
return "bzr SocketAsChannelAdapter"
def send(self, data):
return self.__socket.send(data)
def recv(self, n):
try:
return self.__socket.recv(n)
except socket.error, e:
if e.args[0] in (errno.EPIPE, errno.ECONNRESET, errno.ECONNABORTED,
errno.EBADF):
# Connection has closed. Paramiko expects an empty string in
# this case, not an exception.
return ''
raise
def recv_ready(self):
# TODO: jam 20051215 this function is necessary to support the
# pipelined() function. In reality, it probably should use
# poll() or select() to actually return if there is data
# available, otherwise we probably don't get any benefit
return True
def close(self):
self.__socket.close()
class SSHVendor(object):
"""Abstract base class for SSH vendor implementations."""
def connect_sftp(self, username, password, host, port):
"""Make an SSH connection, and return an SFTPClient.
:param username: an ascii string
:param password: an ascii string
:param host: a host name as an ascii string
:param port: a port number
:type port: int
:raises: ConnectionError if it cannot connect.
:rtype: paramiko.sftp_client.SFTPClient
"""
raise NotImplementedError(self.connect_sftp)
def connect_ssh(self, username, password, host, port, command):
"""Make an SSH connection.
:returns: something with a `close` method, and a `get_filelike_channels`
method that returns a pair of (read, write) filelike objects.
"""
raise NotImplementedError(self.connect_ssh)
def _raise_connection_error(self, host, port=None, orig_error=None,
msg='Unable to connect to SSH host'):
"""Raise a SocketConnectionError with properly formatted host.
This just unifies all the locations that try to raise ConnectionError,
so that they format things properly.
"""
raise errors.SocketConnectionError(host=host, port=port, msg=msg,
orig_error=orig_error)
class LoopbackVendor(SSHVendor):
"""SSH "vendor" that connects over a plain TCP socket, not SSH."""
def connect_sftp(self, username, password, host, port):
sock = socket.socket()
try:
sock.connect((host, port))
except socket.error, e:
self._raise_connection_error(host, port=port, orig_error=e)
return SFTPClient(SocketAsChannelAdapter(sock))
register_ssh_vendor('loopback', LoopbackVendor())
class _ParamikoSSHConnection(object):
def __init__(self, channel):
self.channel = channel
def get_filelike_channels(self):
return self.channel.makefile('rb'), self.channel.makefile('wb')
def close(self):
return self.channel.close()
class ParamikoVendor(SSHVendor):
"""Vendor that uses paramiko."""
def _connect(self, username, password, host, port):
global SYSTEM_HOSTKEYS, BZR_HOSTKEYS
load_host_keys()
try:
t = paramiko.Transport((host, port or 22))
t.set_log_channel('bzr.paramiko')
t.start_client()
except (paramiko.SSHException, socket.error), e:
self._raise_connection_error(host, port=port, orig_error=e)
server_key = t.get_remote_server_key()
server_key_hex = paramiko.util.hexify(server_key.get_fingerprint())
keytype = server_key.get_name()
if host in SYSTEM_HOSTKEYS and keytype in SYSTEM_HOSTKEYS[host]:
our_server_key = SYSTEM_HOSTKEYS[host][keytype]
our_server_key_hex = paramiko.util.hexify(
our_server_key.get_fingerprint())
elif host in BZR_HOSTKEYS and keytype in BZR_HOSTKEYS[host]:
our_server_key = BZR_HOSTKEYS[host][keytype]
our_server_key_hex = paramiko.util.hexify(
our_server_key.get_fingerprint())
else:
trace.warning('Adding %s host key for %s: %s'
% (keytype, host, server_key_hex))
add = getattr(BZR_HOSTKEYS, 'add', None)
if add is not None: # paramiko >= 1.X.X
BZR_HOSTKEYS.add(host, keytype, server_key)
else:
BZR_HOSTKEYS.setdefault(host, {})[keytype] = server_key
our_server_key = server_key
our_server_key_hex = paramiko.util.hexify(
our_server_key.get_fingerprint())
save_host_keys()
if server_key != our_server_key:
filename1 = os.path.expanduser('~/.ssh/known_hosts')
filename2 = osutils.pathjoin(config.config_dir(), 'ssh_host_keys')
raise errors.TransportError(
'Host keys for %s do not match! %s != %s' %
(host, our_server_key_hex, server_key_hex),
['Try editing %s or %s' % (filename1, filename2)])
_paramiko_auth(username, password, host, port, t)
return t
def connect_sftp(self, username, password, host, port):
t = self._connect(username, password, host, port)
try:
return t.open_sftp_client()
except paramiko.SSHException, e:
self._raise_connection_error(host, port=port, orig_error=e,
msg='Unable to start sftp client')
def connect_ssh(self, username, password, host, port, command):
t = self._connect(username, password, host, port)
try:
channel = t.open_session()
cmdline = ' '.join(command)
channel.exec_command(cmdline)
return _ParamikoSSHConnection(channel)
except paramiko.SSHException, e:
self._raise_connection_error(host, port=port, orig_error=e,
msg='Unable to invoke remote bzr')
if paramiko is not None:
vendor = ParamikoVendor()
register_ssh_vendor('paramiko', vendor)
register_ssh_vendor('none', vendor)
register_default_ssh_vendor(vendor)
_sftp_connection_errors = (EOFError, paramiko.SSHException)
del vendor
else:
_sftp_connection_errors = (EOFError,)
class SubprocessVendor(SSHVendor):
"""Abstract base class for vendors that use pipes to a subprocess."""
def _connect(self, argv):
proc = subprocess.Popen(argv,
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
**os_specific_subprocess_params())
return SSHSubprocess(proc)
def connect_sftp(self, username, password, host, port):
try:
argv = self._get_vendor_specific_argv(username, host, port,
subsystem='sftp')
sock = self._connect(argv)
return SFTPClient(SocketAsChannelAdapter(sock))
except _sftp_connection_errors, e:
self._raise_connection_error(host, port=port, orig_error=e)
except (OSError, IOError), e:
# If the machine is fast enough, ssh can actually exit
# before we try and send it the sftp request, which
# raises a Broken Pipe
if e.errno not in (errno.EPIPE,):
raise
self._raise_connection_error(host, port=port, orig_error=e)
def connect_ssh(self, username, password, host, port, command):
try:
argv = self._get_vendor_specific_argv(username, host, port,
command=command)
return self._connect(argv)
except (EOFError), e:
self._raise_connection_error(host, port=port, orig_error=e)
except (OSError, IOError), e:
# If the machine is fast enough, ssh can actually exit
# before we try and send it the sftp request, which
# raises a Broken Pipe
if e.errno not in (errno.EPIPE,):
raise
self._raise_connection_error(host, port=port, orig_error=e)
def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
command=None):
"""Returns the argument list to run the subprocess with.
Exactly one of 'subsystem' and 'command' must be specified.
"""
raise NotImplementedError(self._get_vendor_specific_argv)
class OpenSSHSubprocessVendor(SubprocessVendor):
"""SSH vendor that uses the 'ssh' executable from OpenSSH."""
executable_path = 'ssh'
def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
command=None):
args = [self.executable_path,
'-oForwardX11=no', '-oForwardAgent=no',
'-oClearAllForwardings=yes', '-oProtocol=2',
'-oNoHostAuthenticationForLocalhost=yes']
if port is not None:
args.extend(['-p', str(port)])
if username is not None:
args.extend(['-l', username])
if subsystem is not None:
args.extend(['-s', host, subsystem])
else:
args.extend([host] + command)
return args
register_ssh_vendor('openssh', OpenSSHSubprocessVendor())
class SSHCorpSubprocessVendor(SubprocessVendor):
"""SSH vendor that uses the 'ssh' executable from SSH Corporation."""
executable_path = 'ssh'
def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
command=None):
args = [self.executable_path, '-x']
if port is not None:
args.extend(['-p', str(port)])
if username is not None:
args.extend(['-l', username])
if subsystem is not None:
args.extend(['-s', subsystem, host])
else:
args.extend([host] + command)
return args
register_ssh_vendor('sshcorp', SSHCorpSubprocessVendor())
class PLinkSubprocessVendor(SubprocessVendor):
"""SSH vendor that uses the 'plink' executable from Putty."""
executable_path = 'plink'
def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
command=None):
args = [self.executable_path, '-x', '-a', '-ssh', '-2', '-batch']
if port is not None:
args.extend(['-P', str(port)])
if username is not None:
args.extend(['-l', username])
if subsystem is not None:
args.extend(['-s', host, subsystem])
else:
args.extend([host] + command)
return args
register_ssh_vendor('plink', PLinkSubprocessVendor())
def _paramiko_auth(username, password, host, port, paramiko_transport):
auth = config.AuthenticationConfig()
# paramiko requires a username, but it might be none if nothing was
# supplied. If so, use the local username.
if username is None:
username = auth.get_user('ssh', host, port=port,
default=getpass.getuser())
if _use_ssh_agent:
agent = paramiko.Agent()
for key in agent.get_keys():
trace.mutter('Trying SSH agent key %s'
% paramiko.util.hexify(key.get_fingerprint()))
try:
paramiko_transport.auth_publickey(username, key)
return
except paramiko.SSHException, e:
pass
# okay, try finding id_rsa or id_dss? (posix only)
if _try_pkey_auth(paramiko_transport, paramiko.RSAKey, username, 'id_rsa'):
return
if _try_pkey_auth(paramiko_transport, paramiko.DSSKey, username, 'id_dsa'):
return
# If we have gotten this far, we are about to try for passwords, do an
# auth_none check to see if it is even supported.
supported_auth_types = []
try:
# Note that with paramiko <1.7.5 this logs an INFO message:
# Authentication type (none) not permitted.
# So we explicitly disable the logging level for this action
old_level = paramiko_transport.logger.level
paramiko_transport.logger.setLevel(logging.WARNING)
try:
paramiko_transport.auth_none(username)
finally:
paramiko_transport.logger.setLevel(old_level)
except paramiko.BadAuthenticationType, e:
# Supported methods are in the exception
supported_auth_types = e.allowed_types
except paramiko.SSHException, e:
# Don't know what happened, but just ignore it
pass
# We treat 'keyboard-interactive' and 'password' auth methods identically,
# because Paramiko's auth_password method will automatically try
# 'keyboard-interactive' auth (using the password as the response) if
# 'password' auth is not available. Apparently some Debian and Gentoo
# OpenSSH servers require this.
# XXX: It's possible for a server to require keyboard-interactive auth that
# requires something other than a single password, but we currently don't
# support that.
if ('password' not in supported_auth_types and
'keyboard-interactive' not in supported_auth_types):
raise errors.ConnectionError('Unable to authenticate to SSH host as'
'\n %s@%s\nsupported auth types: %s'
% (username, host, supported_auth_types))
if password:
try:
paramiko_transport.auth_password(username, password)
return
except paramiko.SSHException, e:
pass
# give up and ask for a password
password = auth.get_password('ssh', host, username, port=port)
# get_password can still return None, which means we should not prompt
if password is not None:
try:
paramiko_transport.auth_password(username, password)
except paramiko.SSHException, e:
raise errors.ConnectionError(
'Unable to authenticate to SSH host as'
'\n %s@%s\n' % (username, host), e)
else:
raise errors.ConnectionError('Unable to authenticate to SSH host as'
' %s@%s' % (username, host))
def _try_pkey_auth(paramiko_transport, pkey_class, username, filename):
filename = os.path.expanduser('~/.ssh/' + filename)
try:
key = pkey_class.from_private_key_file(filename)
paramiko_transport.auth_publickey(username, key)
return True
except paramiko.PasswordRequiredException:
password = ui.ui_factory.get_password(
prompt='SSH %(filename)s password', filename=filename)
try:
key = pkey_class.from_private_key_file(filename, password)
paramiko_transport.auth_publickey(username, key)
return True
except paramiko.SSHException:
trace.mutter('SSH authentication via %s key failed.'
% (os.path.basename(filename),))
except paramiko.SSHException:
trace.mutter('SSH authentication via %s key failed.'
% (os.path.basename(filename),))
except IOError:
pass
return False
def load_host_keys():
"""
Load system host keys (probably doesn't work on windows) and any
"discovered" keys from previous sessions.
"""
global SYSTEM_HOSTKEYS, BZR_HOSTKEYS
try:
SYSTEM_HOSTKEYS = paramiko.util.load_host_keys(
os.path.expanduser('~/.ssh/known_hosts'))
except IOError, e:
trace.mutter('failed to load system host keys: ' + str(e))
bzr_hostkey_path = osutils.pathjoin(config.config_dir(), 'ssh_host_keys')
try:
BZR_HOSTKEYS = paramiko.util.load_host_keys(bzr_hostkey_path)
except IOError, e:
trace.mutter('failed to load bzr host keys: ' + str(e))
save_host_keys()
def save_host_keys():
"""
Save "discovered" host keys in $(config)/ssh_host_keys/.
"""
global SYSTEM_HOSTKEYS, BZR_HOSTKEYS
bzr_hostkey_path = osutils.pathjoin(config.config_dir(), 'ssh_host_keys')
config.ensure_config_dir_exists()
try:
f = open(bzr_hostkey_path, 'w')
f.write('# SSH host keys collected by bzr\n')
for hostname, keys in BZR_HOSTKEYS.iteritems():
for keytype, key in keys.iteritems():
f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
f.close()
except IOError, e:
trace.mutter('failed to save bzr host keys: ' + str(e))
def os_specific_subprocess_params():
"""Get O/S specific subprocess parameters."""
if sys.platform == 'win32':
# setting the process group and closing fds is not supported on
# win32
return {}
else:
# We close fds other than the pipes as the child process does not need
# them to be open.
#
# We also set the child process to ignore SIGINT. Normally the signal
# would be sent to every process in the foreground process group, but
# this causes it to be seen only by bzr and not by ssh. Python will
# generate a KeyboardInterrupt in bzr, and we will then have a chance
# to release locks or do other cleanup over ssh before the connection
# goes away.
# <https://launchpad.net/products/bzr/+bug/5987>
#
# Running it in a separate process group is not good because then it
# can't get non-echoed input of a password or passphrase.
# <https://launchpad.net/products/bzr/+bug/40508>
return {'preexec_fn': _ignore_signals,
'close_fds': True,
}
import weakref
_subproc_weakrefs = set()
def _close_ssh_proc(proc):
for func in [proc.stdin.close, proc.stdout.close, proc.wait]:
try:
func()
except OSError:
pass
class SSHSubprocess(object):
"""A socket-like object that talks to an ssh subprocess via pipes."""
def __init__(self, proc):
self.proc = proc
# Add a weakref to proc that will attempt to do the same as self.close
# to avoid leaving processes lingering indefinitely.
def terminate(ref):
_subproc_weakrefs.remove(ref)
_close_ssh_proc(proc)
_subproc_weakrefs.add(weakref.ref(self, terminate))
def send(self, data):
return os.write(self.proc.stdin.fileno(), data)
def recv(self, count):
return os.read(self.proc.stdout.fileno(), count)
def close(self):
_close_ssh_proc(self.proc)
def get_filelike_channels(self):
return (self.proc.stdout, self.proc.stdin)
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