Explicitly use IdentityFile option when connecting to specific host

libagent/ssh/__init__.py

@@ -23,9 +23,11 @@ log = logging.getLogger(__name__)
 UNIX_SOCKET_TIMEOUT = 0.1
 
 
-def ssh_args(label):
+def ssh_args(conn):
     """Create SSH command for connecting specified server."""
-    identity = device.interface.string_to_identity(label)
+    I, = conn.identities
+    identity = I.identity_dict
+    pubkey_tempfile, = conn.public_keys_as_files()
 
     args = []
     if 'port' in identity:
@@ -33,12 +35,15 @@ def ssh_args(label):
     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(label):
+def mosh_args(conn):
     """Create SSH command for connecting specified server."""
-    identity = device.interface.string_to_identity(label)
+    I, = conn.identities
+    identity = I.identity_dict
 
     args = []
     if 'port' in identity:
@@ -193,6 +198,7 @@ class JustInTimeConnection(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)."""
@@ -209,6 +215,17 @@ class JustInTimeConnection(object):
             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()
@@ -238,6 +255,7 @@ def main(device_type):
     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')
@@ -252,14 +270,22 @@ def main(device_type):
         identity.identity_dict['proto'] = u'ssh'
         log.info('identity #%d: %s', index, identity.to_string())
 
-    sock_path = _get_sock_path(args)
+    # override default PIN/passphrase entry tools (relevant for TREZOR/Keepkey):
+    device_type.ui = device.ui.UI(device_type=device_type, config=vars(args))
+    device_type.cached_passphrase_ack = util.ExpiringCache(
+        args.cache_expiry_seconds)
 
+    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(args.identity) + args.command
+        command = ['ssh'] + ssh_args(conn) + args.command
     elif args.mosh:
-        command = ['mosh'] + mosh_args(args.identity) + args.command
+        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)
@@ -274,15 +300,6 @@ def main(device_type):
         command = os.environ['SHELL']
         sys.stdin.close()
 
-    # override default PIN/passphrase entry tools (relevant for TREZOR/Keepkey):
-    device_type.ui = device.ui.UI(device_type=device_type, config=vars(args))
-    device_type.cached_passphrase_ack = util.ExpiringCache(
-        args.cache_expiry_seconds)
-
-    conn = JustInTimeConnection(
-        conn_factory=lambda: client.Client(device_type()),
-        identities=identities, public_keys=public_keys)
-
     if command or args.daemonize or args.foreground:
         with context:
             return run_server(conn=conn, command=command, sock_path=sock_path,