311 lines
11 KiB
Python
311 lines
11 KiB
Python
"""SSH-agent implementation using hardware authentication devices."""
|
|
import contextlib
|
|
import functools
|
|
import io
|
|
import logging
|
|
import os
|
|
import re
|
|
import signal
|
|
import subprocess
|
|
import sys
|
|
import tempfile
|
|
import threading
|
|
|
|
import configargparse
|
|
import daemon
|
|
import pkg_resources
|
|
|
|
from .. import device, formats, server, util
|
|
from . import client, protocol
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
UNIX_SOCKET_TIMEOUT = 0.1
|
|
|
|
|
|
def ssh_args(conn):
|
|
"""Create SSH command for connecting specified server."""
|
|
I, = conn.identities
|
|
identity = I.identity_dict
|
|
pubkey_tempfile, = conn.public_keys_as_files()
|
|
|
|
args = []
|
|
if 'port' in identity:
|
|
args += ['-p', identity['port']]
|
|
if 'user' in identity:
|
|
args += ['-l', identity['user']]
|
|
|
|
args += ['-o', 'IdentityFile={}'.format(pubkey_tempfile.name)]
|
|
args += ['-o', 'IdentitiesOnly=true']
|
|
return args + [identity['host']]
|
|
|
|
|
|
def mosh_args(conn):
|
|
"""Create SSH command for connecting specified server."""
|
|
I, = conn.identities
|
|
identity = I.identity_dict
|
|
|
|
args = []
|
|
if 'port' in identity:
|
|
args += ['-p', identity['port']]
|
|
if 'user' in identity:
|
|
args += [identity['user']+'@'+identity['host']]
|
|
else:
|
|
args += [identity['host']]
|
|
|
|
return args
|
|
|
|
|
|
def _to_unicode(s):
|
|
try:
|
|
return unicode(s, 'utf-8')
|
|
except NameError:
|
|
return s
|
|
|
|
|
|
def create_agent_parser(device_type):
|
|
"""Create an ArgumentParser for this tool."""
|
|
epilog = ('See https://github.com/romanz/trezor-agent/blob/master/'
|
|
'doc/README-SSH.md for usage examples.')
|
|
p = configargparse.ArgParser(default_config_files=['~/.ssh/agent.config'],
|
|
epilog=epilog)
|
|
p.add_argument('-v', '--verbose', default=0, action='count')
|
|
|
|
agent_package = device_type.package_name()
|
|
resources_map = {r.key: r for r in pkg_resources.require(agent_package)}
|
|
resources = [resources_map[agent_package], resources_map['libagent']]
|
|
versions = '\n'.join('{}={}'.format(r.key, r.version) for r in resources)
|
|
p.add_argument('--version', help='print the version info',
|
|
action='version', version=versions)
|
|
|
|
curve_names = ', '.join(sorted(formats.SUPPORTED_CURVES))
|
|
p.add_argument('-e', '--ecdsa-curve-name', metavar='CURVE',
|
|
default=formats.CURVE_NIST256,
|
|
help='specify ECDSA curve name: ' + curve_names)
|
|
p.add_argument('--timeout',
|
|
default=UNIX_SOCKET_TIMEOUT, type=float,
|
|
help='timeout for accepting SSH client connections')
|
|
p.add_argument('--debug', default=False, action='store_true',
|
|
help='log SSH protocol messages for debugging.')
|
|
p.add_argument('--log-file', type=str,
|
|
help='Path to the log file (to be written by the agent).')
|
|
p.add_argument('--sock-path', type=str,
|
|
help='Path to the UNIX domain socket of the agent.')
|
|
|
|
p.add_argument('--pin-entry-binary', type=str, default='pinentry',
|
|
help='Path to PIN entry UI helper.')
|
|
p.add_argument('--passphrase-entry-binary', type=str, default='pinentry',
|
|
help='Path to passphrase entry UI helper.')
|
|
p.add_argument('--cache-expiry-seconds', type=float, default=float('inf'),
|
|
help='Expire passphrase from cache after this duration.')
|
|
|
|
g = p.add_mutually_exclusive_group()
|
|
g.add_argument('-d', '--daemonize', default=False, action='store_true',
|
|
help='Daemonize the agent and print its UNIX socket path')
|
|
g.add_argument('-f', '--foreground', default=False, action='store_true',
|
|
help='Run agent in foreground with specified UNIX socket path')
|
|
g.add_argument('-s', '--shell', default=False, action='store_true',
|
|
help=('run ${SHELL} as subprocess under SSH agent, allowing '
|
|
'regular SSH-based tools to be used in the shell'))
|
|
g.add_argument('-c', '--connect', default=False, action='store_true',
|
|
help='connect to specified host via SSH')
|
|
g.add_argument('--mosh', default=False, action='store_true',
|
|
help='connect to specified host via using Mosh')
|
|
|
|
p.add_argument('identity', type=_to_unicode, default=None,
|
|
help='proto://[user@]host[:port][/path]')
|
|
p.add_argument('command', type=str, nargs='*', metavar='ARGUMENT',
|
|
help='command to run under the SSH agent')
|
|
return p
|
|
|
|
|
|
@contextlib.contextmanager
|
|
def serve(handler, sock_path, timeout=UNIX_SOCKET_TIMEOUT):
|
|
"""
|
|
Start the ssh-agent server on a UNIX-domain socket.
|
|
|
|
If no connection is made during the specified timeout,
|
|
retry until the context is over.
|
|
"""
|
|
ssh_version = subprocess.check_output(['ssh', '-V'],
|
|
stderr=subprocess.STDOUT)
|
|
log.debug('local SSH version: %r', ssh_version)
|
|
environ = {'SSH_AUTH_SOCK': sock_path, 'SSH_AGENT_PID': str(os.getpid())}
|
|
device_mutex = threading.Lock()
|
|
with server.unix_domain_socket_server(sock_path) as sock:
|
|
sock.settimeout(timeout)
|
|
quit_event = threading.Event()
|
|
handle_conn = functools.partial(server.handle_connection,
|
|
handler=handler,
|
|
mutex=device_mutex)
|
|
kwargs = {'sock': sock,
|
|
'handle_conn': handle_conn,
|
|
'quit_event': quit_event}
|
|
with server.spawn(server.server_thread, kwargs):
|
|
try:
|
|
yield environ
|
|
finally:
|
|
log.debug('closing server')
|
|
quit_event.set()
|
|
|
|
|
|
def run_server(conn, command, sock_path, debug, timeout):
|
|
"""Common code for run_agent and run_git below."""
|
|
ret = 0
|
|
try:
|
|
handler = protocol.Handler(conn=conn, debug=debug)
|
|
with serve(handler=handler, sock_path=sock_path,
|
|
timeout=timeout) as env:
|
|
if command:
|
|
ret = server.run_process(command=command, environ=env)
|
|
else:
|
|
signal.pause() # wait for signal (e.g. SIGINT)
|
|
except KeyboardInterrupt:
|
|
log.info('server stopped')
|
|
return ret
|
|
|
|
|
|
def handle_connection_error(func):
|
|
"""Fail with non-zero exit code."""
|
|
@functools.wraps(func)
|
|
def wrapper(*args, **kwargs):
|
|
try:
|
|
return func(*args, **kwargs)
|
|
except device.interface.NotFoundError as e:
|
|
log.error('Connection error (try unplugging and replugging your device): %s', e)
|
|
return 1
|
|
return wrapper
|
|
|
|
|
|
def parse_config(contents):
|
|
"""Parse config file into a list of Identity objects."""
|
|
for identity_str, curve_name in re.findall(r'\<(.*?)\|(.*?)\>', contents):
|
|
yield device.interface.Identity(identity_str=identity_str,
|
|
curve_name=curve_name)
|
|
|
|
|
|
def import_public_keys(contents):
|
|
"""Load (previously exported) SSH public keys from a file's contents."""
|
|
for line in io.StringIO(contents):
|
|
# Verify this line represents valid SSH public key
|
|
formats.import_public_key(line)
|
|
yield line
|
|
|
|
|
|
class JustInTimeConnection:
|
|
"""Connect to the device just before the needed operation."""
|
|
|
|
def __init__(self, conn_factory, identities, public_keys=None):
|
|
"""Create a JIT connection object."""
|
|
self.conn_factory = conn_factory
|
|
self.identities = identities
|
|
self.public_keys_cache = public_keys
|
|
self.public_keys_tempfiles = []
|
|
|
|
def public_keys(self):
|
|
"""Return a list of SSH public keys (in textual format)."""
|
|
if not self.public_keys_cache:
|
|
conn = self.conn_factory()
|
|
self.public_keys_cache = conn.export_public_keys(self.identities)
|
|
return self.public_keys_cache
|
|
|
|
def parse_public_keys(self):
|
|
"""Parse SSH public keys into dictionaries."""
|
|
public_keys = [formats.import_public_key(pk)
|
|
for pk in self.public_keys()]
|
|
for pk, identity in zip(public_keys, self.identities):
|
|
pk['identity'] = identity
|
|
return public_keys
|
|
|
|
def public_keys_as_files(self):
|
|
"""Store public keys as temporary SSH identity files."""
|
|
if not self.public_keys_tempfiles:
|
|
for pk in self.public_keys():
|
|
f = tempfile.NamedTemporaryFile(prefix='trezor-ssh-pubkey-', mode='w')
|
|
f.write(pk)
|
|
f.flush()
|
|
self.public_keys_tempfiles.append(f)
|
|
|
|
return self.public_keys_tempfiles
|
|
|
|
def sign(self, blob, identity):
|
|
"""Sign a given blob using the specified identity on the device."""
|
|
conn = self.conn_factory()
|
|
return conn.sign_ssh_challenge(blob=blob, identity=identity)
|
|
|
|
|
|
@contextlib.contextmanager
|
|
def _dummy_context():
|
|
yield
|
|
|
|
|
|
def _get_sock_path(args):
|
|
sock_path = args.sock_path
|
|
if not sock_path:
|
|
if args.foreground:
|
|
log.error('running in foreground mode requires specifying UNIX socket path')
|
|
sys.exit(1)
|
|
else:
|
|
sock_path = tempfile.mktemp(prefix='trezor-ssh-agent-')
|
|
return sock_path
|
|
|
|
|
|
@handle_connection_error
|
|
def main(device_type):
|
|
"""Run ssh-agent using given hardware client factory."""
|
|
args = create_agent_parser(device_type=device_type).parse_args()
|
|
util.setup_logging(verbosity=args.verbose, filename=args.log_file)
|
|
|
|
public_keys = None
|
|
filename = None
|
|
if args.identity.startswith('/'):
|
|
filename = args.identity
|
|
contents = open(filename, 'rb').read().decode('utf-8')
|
|
# Allow loading previously exported SSH public keys
|
|
if filename.endswith('.pub'):
|
|
public_keys = list(import_public_keys(contents))
|
|
identities = list(parse_config(contents))
|
|
else:
|
|
identities = [device.interface.Identity(
|
|
identity_str=args.identity, curve_name=args.ecdsa_curve_name)]
|
|
for index, identity in enumerate(identities):
|
|
identity.identity_dict['proto'] = 'ssh'
|
|
log.info('identity #%d: %s', index, identity.to_string())
|
|
|
|
# override default PIN/passphrase entry tools (relevant for TREZOR/Keepkey):
|
|
device_type.ui = device.ui.UI(device_type=device_type, config=vars(args))
|
|
|
|
conn = JustInTimeConnection(
|
|
conn_factory=lambda: client.Client(device_type()),
|
|
identities=identities, public_keys=public_keys)
|
|
|
|
sock_path = _get_sock_path(args)
|
|
command = args.command
|
|
context = _dummy_context()
|
|
if args.connect:
|
|
command = ['ssh'] + ssh_args(conn) + args.command
|
|
elif args.mosh:
|
|
command = ['mosh'] + mosh_args(conn) + args.command
|
|
elif args.daemonize:
|
|
out = 'SSH_AUTH_SOCK={0}; export SSH_AUTH_SOCK;\n'.format(sock_path)
|
|
sys.stdout.write(out)
|
|
sys.stdout.flush()
|
|
context = daemon.DaemonContext()
|
|
log.info('running the agent as a daemon on %s', sock_path)
|
|
elif args.foreground:
|
|
log.info('running the agent on %s', sock_path)
|
|
|
|
use_shell = bool(args.shell)
|
|
if use_shell:
|
|
command = os.environ['SHELL']
|
|
sys.stdin.close()
|
|
|
|
if command or args.daemonize or args.foreground:
|
|
with context:
|
|
return run_server(conn=conn, command=command, sock_path=sock_path,
|
|
debug=args.debug, timeout=args.timeout)
|
|
else:
|
|
for pk in conn.public_keys():
|
|
sys.stdout.write(pk)
|
|
return 0 # success exit code
|