Ask for confirmation before doing a clone by default

kitty/options/definition.py

@@ -2774,6 +2774,15 @@ pager, etc. on supported shells.  Set to ``disabled`` to turn off shell
 integration, completely. See :ref:`shell_integration` for details.
 ''')
 
+opt('allow_cloning', 'ask', choices=('yes', 'no', 'ask'), long_text='''
+Control whether programs running in the terminal can request new
+windows to be created. The canonical example is :code:`clone-in-kitty`.
+By default, kitty will ask for permission for each clone request.
+Allowing cloning unconditionally gives programs running in the terminal
+(including over SSH) permission to execute arbitrary code as the user
+the terminal is running as on the computer the terminal is running on.
+''')
+
 opt('term', 'xterm-kitty',
     long_text='''
 The value of the TERM environment variable to set. Changing this can break many

kitty/options/parse.py

@@ -50,6 +50,14 @@ class Parser:
     def adjust_line_height(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['adjust_line_height'] = adjust_line_height(val)
 
+    def allow_cloning(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
+        val = val.lower()
+        if val not in self.choices_for_allow_cloning:
+            raise ValueError(f"The value {val} is not a valid choice for allow_cloning")
+        ans["allow_cloning"] = val
+
+    choices_for_allow_cloning = frozenset(('yes', 'no', 'ask'))
+
     def allow_hyperlinks(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['allow_hyperlinks'] = allow_hyperlinks(val)
 

kitty/options/types.py

@@ -13,6 +13,7 @@ from kitty.types import FloatEdges, SingleKey
 import kitty.types
 
 if typing.TYPE_CHECKING:
+    choices_for_allow_cloning = typing.Literal['yes', 'no', 'ask']
     choices_for_background_image_layout = typing.Literal['mirror-tiled', 'scaled', 'tiled', 'clamped']
     choices_for_default_pointer_shape = typing.Literal['arrow', 'beam', 'hand']
     choices_for_linux_display_server = typing.Literal['auto', 'wayland', 'x11']
@@ -27,6 +28,7 @@ if typing.TYPE_CHECKING:
     choices_for_tab_switch_strategy = typing.Literal['last', 'left', 'previous', 'right']
     choices_for_window_logo_position = typing.Literal['top-left', 'top', 'top-right', 'left', 'center', 'right', 'bottom-left', 'bottom', 'bottom-right']
 else:
+    choices_for_allow_cloning = str
     choices_for_background_image_layout = str
     choices_for_default_pointer_shape = str
     choices_for_linux_display_server = str
@@ -51,6 +53,7 @@ option_names = (  # {{{
  'adjust_baseline',
  'adjust_column_width',
  'adjust_line_height',
+ 'allow_cloning',
  'allow_hyperlinks',
  'allow_remote_control',
  'background',
@@ -461,6 +464,7 @@ class Options:
     adjust_baseline: typing.Union[int, float] = 0
     adjust_column_width: typing.Union[int, float] = 0
     adjust_line_height: typing.Union[int, float] = 0
+    allow_cloning: choices_for_allow_cloning = 'ask'
     allow_hyperlinks: int = 1
     allow_remote_control: str = 'n'
     background: Color = Color(0, 0, 0)

kitty/window.py

@@ -1015,8 +1015,11 @@ class Window:
         if not msg:
             if self.current_clone_data:
                 cdata, self.current_clone_data = self.current_clone_data, ''
-                from .launch import clone_and_launch
-                clone_and_launch(cdata, self)
+                get_boss().confirm(_(
+                    'A program running in this window wants to clone it into another window.'
+                    ' Allow it do so, once?'),
+                    partial(self.handle_remote_clone_confirmation, cdata), window=self,
+                )
             self.current_clone_data = ''
             return
         num, rest = msg.split(':', 1)
@@ -1024,6 +1027,11 @@ class Window:
             self.current_clone_data = ''
         self.current_clone_data += rest
 
+    def handle_remote_clone_confirmation(self, cdata: str, confirmed: bool) -> None:
+        if confirmed:
+            from .launch import clone_and_launch
+            clone_and_launch(cdata, self)
+
     def handle_remote_askpass(self, msg: str) -> None:
         from .shm import SharedMemory
         with SharedMemory(name=msg, readonly=True) as shm: