feat(core): prevent interruption of workflows from other communication interfaces

common/protob/messages-common.proto

@@ -39,6 +39,7 @@ message Failure {
         Failure_PinMismatch = 12;
         Failure_WipeCodeMismatch = 13;
         Failure_InvalidSession = 14;
+        Failure_DeviceIsBusy = 15;
         Failure_FirmwareError = 99;
     }
 }

core/src/all_modules.py

@@ -39,6 +39,8 @@ boot
 import boot
 main
 import main
+mutex
+import mutex
 session
 import session
 typing

core/src/mutex.py

@@ -0,0 +1,23 @@
+class Mutex:
+    def __init__(self):
+        self.ifaces = []
+        self.busy = None
+
+    def add(self, iface_num: int):
+        if iface_num not in self.ifaces:
+            self.ifaces.append(iface_num)
+
+    def set_busy(self, iface_num: int):
+        if iface_num in self.ifaces:
+            self.busy = iface_num
+
+    def get_busy(self, iface_num: int) -> int:
+        return (
+            iface_num in self.ifaces
+            and self.busy is not None
+            and self.busy != iface_num
+        )
+
+    def release(self, iface_num: int):
+        if iface_num == self.busy:
+            self.busy = None

core/src/session.py

@@ -1,3 +1,5 @@
+from mutex import Mutex
+
 from trezor import log, loop, utils, wire, workflow
 
 import apps.base
@@ -20,11 +22,19 @@ if __debug__:
 apps.base.set_homescreen()
 workflow.start_default()
 
+
+mutex = Mutex()
+
+mutex.add(usb.iface_wire.iface_num())
+mutex.add(usb.iface_debug.iface_num())
+mutex.add(bluetooth.iface_ble.iface_num())
+
 # initialize the wire codec
-wire.setup(usb.iface_wire)
+wire.setup(usb.iface_wire, mutex=mutex)
 if __debug__:
-    wire.setup(usb.iface_debug, is_debug_session=True)
+    wire.setup(usb.iface_debug, is_debug_session=True, mutex=mutex)
-wire.setup(bluetooth.iface_ble)
+wire.setup(bluetooth.iface_ble, mutex=mutex)
+
 
 loop.run()
 

core/src/trezor/enums/FailureType.py

@@ -16,4 +16,5 @@ NotInitialized = 11
 PinMismatch = 12
 WipeCodeMismatch = 13
 InvalidSession = 14
+DeviceIsBusy = 15
 FirmwareError = 99

core/src/trezor/enums/__init__.py

@@ -268,6 +268,7 @@ if TYPE_CHECKING:
         PinMismatch = 12
         WipeCodeMismatch = 13
         InvalidSession = 14
+        DeviceIsBusy = 15
         FirmwareError = 99
 
     class ButtonRequestType(IntEnum):

core/src/trezor/wire/__init__.py

@@ -92,9 +92,9 @@ if TYPE_CHECKING:
 experimental_enabled = False
 
 
-def setup(iface: WireInterface, is_debug_session: bool = False) -> None:
+def setup(iface: WireInterface, is_debug_session: bool = False, mutex=None) -> None:
     """Initialize the wire stack on passed USB interface."""
-    loop.schedule(handle_session(iface, codec_v1.SESSION_ID, is_debug_session))
+    loop.schedule(handle_session(iface, codec_v1.SESSION_ID, is_debug_session, mutex))
 
 
 def _wrap_protobuf_load(
@@ -384,7 +384,7 @@ async def _handle_single_message(
 
 
 async def handle_session(
-    iface: WireInterface, session_id: int, is_debug_session: bool = False
+    iface: WireInterface, session_id: int, is_debug_session: bool = False, mutex=None
 ) -> None:
     if __debug__ and is_debug_session:
         ctx_buffer = WIRE_BUFFER_DEBUG
@@ -409,6 +409,18 @@ async def handle_session(
                 # wait for a new one coming from the wire.
                 try:
                     msg = await ctx.read_from_wire()
+                    if mutex is not None:
+                        if mutex.get_busy(iface.iface_num()):
+                            await ctx.write(
+                                Failure(
+                                    code=FailureType.DeviceIsBusy,
+                                    message="Device is busy",
+                                )
+                            )
+                            continue
+                        else:
+                            mutex.set_busy(iface.iface_num())
+
                 except codec_v1.CodecError as exc:
                     if __debug__:
                         log.exception(__name__, exc)

python/src/trezorlib/cli/__init__.py

@@ -26,7 +26,7 @@ import dbus.mainloop.glib
 import dbus.service
 from gi.repository import GLib
 
-from .. import exceptions, transport
+from .. import exceptions, messages, transport
 from ..client import TrezorClient
 from ..ui import ClickUI, ScriptUI
 
@@ -108,6 +108,12 @@ class TrezorConnection:
         except transport.DeviceIsBusy:
             click.echo("Device is in use by another process.")
             sys.exit(1)
+        except exceptions.TrezorFailure as e:
+            if e.code is messages.FailureType.DeviceIsBusy:
+                click.echo(str(e))
+                sys.exit(1)
+            else:
+                raise e
         except Exception:
             click.echo("Failed to find a Trezor device.")
             if self.path is not None:

python/src/trezorlib/messages.py

@@ -277,6 +277,7 @@ class FailureType(IntEnum):
     PinMismatch = 12
     WipeCodeMismatch = 13
     InvalidSession = 14
+    DeviceIsBusy = 15
     FirmwareError = 99