Widget: Don't allow un-encrypted to-device traffic if the room is encrypted (parity with rust widget driver)

src/stores/widgets/StopGapWidget.ts

@@ -515,9 +515,33 @@ export class StopGapWidget extends EventEmitter {
     };
 
     private onToDeviceMessage = async (payload: ReceivedToDeviceMessage): Promise<void> => {
+        // Check if the room the widget is in is end-to-end encrypted
+        let acceptEncryptedTrafficOnly: boolean;
+        if (this.roomId && this.client.getCrypto()) {
+            acceptEncryptedTrafficOnly = await this.client.getCrypto()!.isEncryptionEnabledInRoom(this.roomId);
+        } else {
+            // If the widget is not in a room, default to encrypted traffic only
+            acceptEncryptedTrafficOnly = true;
+        }
         const { message, encryptionInfo } = payload;
-        // TODO: Update the widget API to use a proper IToDeviceMessage instead of a IRoomEvent
-        await this.messaging?.feedToDevice(message as IRoomEvent, encryptionInfo != null);
+
+        if (acceptEncryptedTrafficOnly) {
+            // Only pass on to-device messages that are encrypted
+            if (encryptionInfo != null) {
+                // TODO: Update the widget API to use a proper IToDeviceMessage instead of a IRoomEvent
+                await this.messaging?.feedToDevice(message as IRoomEvent, true);
+            } else {
+                logger.warn(
+                    `Received to-device event in clear for a widget in an e2e room (${this.roomId}), dropping.`,
+                );
+            }
+            return;
+        } else {
+            // Forward to the widget.
+            // It is ok to send an encrypted to-device message even if the room is clear.
+            // TODO: Update the widget API to use a proper IToDeviceMessage instead of a IRoomEvent
+            await this.messaging?.feedToDevice(message as IRoomEvent, encryptionInfo != null);
+        }
     };
 
     /**

src/stores/widgets/StopGapWidgetDriver.ts

@@ -424,8 +424,22 @@ export class StopGapWidgetDriver extends WidgetDriver {
     ): Promise<void> {
         const client = MatrixClientPeg.safeGet();
 
-        if (encrypted) {
-            const crypto = client.getCrypto();
+        const crypto = client.getCrypto();
+
+        let forceEncryptedTraffic: boolean;
+        if (crypto) {
+            if (this.inRoomId) {
+                forceEncryptedTraffic = await client.getCrypto()!.isEncryptionEnabledInRoom(this.inRoomId);
+            } else {
+                // If the widget is not in a room, we default to only encrypted traffic
+                forceEncryptedTraffic = true;
+            }
+        } else {
+            // If the client does not have crypto we default to not allowing encrypted traffic?
+            forceEncryptedTraffic = false;
+        }
+
+        if (forceEncryptedTraffic || encrypted) {
             if (!crypto) throw new Error("E2EE not enabled");
 
             // attempt to re-batch these up into a single request

test/test-utils/test-utils.ts

@@ -158,6 +158,7 @@ export function createTestClient(): MatrixClient {
             isSecretStorageReady: jest.fn().mockResolvedValue(false),
             deleteKeyBackupVersion: jest.fn(),
             crossSignDevice: jest.fn(),
+            encryptToDeviceMessages: jest.fn(),
         }),
 
         getPushActionsForEvent: jest.fn(),

test/unit-tests/stores/widgets/StopGapWidget-test.ts

@@ -121,6 +121,81 @@ describe("StopGapWidget", () => {
         expect(messaging.feedToDevice).toHaveBeenCalledWith(receivedToDevice.message, true);
     });
 
+    it("Drop sent in clear to-device messages if room is encrypted.", async () => {
+        jest.spyOn(client.getCrypto()!, "isEncryptionEnabledInRoom").mockResolvedValue(true);
+
+        const clearReceivedToDevice = {
+            message: {
+                type: "org.example.foo",
+                sender: "@alice:example.org",
+                content: {
+                    hello: "spoofed world",
+                },
+            },
+            encryptionInfo: null,
+        };
+
+        client.emit(ClientEvent.ReceivedToDeviceMessage, clearReceivedToDevice);
+        await Promise.resolve(); // flush promises
+        expect(messaging.feedToDevice).not.toHaveBeenCalled();
+
+        const encryptedReceivedToDevice = {
+            message: {
+                type: "org.example.foo",
+                sender: "@alice:example.org",
+                content: {
+                    hello: "Hello world",
+                },
+            },
+            encryptionInfo: {
+                senderVerified: false,
+                sender: "@alice:example.org",
+                senderCurve25519KeyBase64: "",
+                senderDevice: "ABCDEFGHI",
+            },
+        };
+
+        client.emit(ClientEvent.ReceivedToDeviceMessage, encryptedReceivedToDevice);
+        await Promise.resolve(); // flush promises
+        expect(messaging.feedToDevice).toHaveBeenCalledWith(encryptedReceivedToDevice.message, true);
+    });
+
+    it("Default to only encrypted traffic if there is no room.", async () => {
+        // Replace the widget with one that has no room
+        // first stop messaging to clear the previous widget
+        widget.stopMessaging();
+        widget = new StopGapWidget({
+            app: {
+                id: "test",
+                creatorUserId: "@alice:example.org",
+                type: "example",
+                url: "https://example.org?user-id=$matrix_user_id&device-id=$org.matrix.msc3819.matrix_device_id&base-url=$org.matrix.msc4039.matrix_base_url&theme=$org.matrix.msc2873.client_theme",
+            },
+            // no room provided
+            userId: "@alice:example.org",
+            creatorUserId: "@alice:example.org",
+            waitForIframeLoad: true,
+            userWidget: false,
+        });
+        // Start messaging without an iframe, since ClientWidgetApi is mocked
+        widget.startMessaging(null as unknown as HTMLIFrameElement);
+
+        const clearReceivedToDevice = {
+            message: {
+                type: "org.example.foo",
+                sender: "@alice:example.org",
+                content: {
+                    hello: "spoofed world",
+                },
+            },
+            encryptionInfo: null,
+        };
+
+        client.emit(ClientEvent.ReceivedToDeviceMessage, clearReceivedToDevice);
+        await Promise.resolve(); // flush promises
+        expect(messaging.feedToDevice).not.toHaveBeenCalled();
+    });
+
     it("feeds incoming state updates to the widget", () => {
         const event = mkEvent({
             event: true,

test/unit-tests/stores/widgets/StopGapWidgetDriver-test.ts

@@ -190,6 +190,22 @@ describe("StopGapWidgetDriver", () => {
 
         beforeEach(() => {
             driver = mkDefaultDriver();
+
+            mocked(client.getCrypto()!.encryptToDeviceMessages).mockImplementation(
+                async (eventType, devices, payload) => {
+                    return {
+                        eventType: "m.room.encrypted",
+                        batch: devices.map(({ userId, deviceId }) => ({
+                            userId,
+                            deviceId,
+                            payload: {
+                                type: "m.room.encrypted",
+                                content: { ciphertext: "ciphertext" },
+                            },
+                        })),
+                    };
+                },
+            );
         });
 
         it("sends unencrypted messages", async () => {
@@ -203,25 +219,54 @@ describe("StopGapWidgetDriver", () => {
             });
         });
 
-        it("sends encrypted messages", async () => {
-            const encryptToDeviceMessages = jest
-                .fn()
-                .mockImplementation(
-                    (eventType, recipients: { userId: string; deviceId: string }[], content: object) => ({
-                        eventType: "m.room.encrypted",
-                        batch: recipients.map(({ userId, deviceId }) => ({
-                            userId,
-                            deviceId,
-                            payload: {
-                                eventType,
-                                content,
-                            },
-                        })),
-                    }),
-                );
+        it("should force encrypted traffic if room is e2ee", async () => {
+            mocked(client.getCrypto()!.isEncryptionEnabledInRoom).mockResolvedValue(true);
 
-            MatrixClientPeg.safeGet().getCrypto()!.encryptToDeviceMessages = encryptToDeviceMessages;
+            // Try to send with `encrypted: false`, but it should be forced to true
+            await driver.sendToDevice("org.example.foo", false, contentMap);
+            expect(client.getCrypto()!.encryptToDeviceMessages).toHaveBeenCalled();
+            expect(client.queueToDevice).toHaveBeenCalledWith(
+                expect.objectContaining({
+                    eventType: "m.room.encrypted",
+                }),
+            );
+        });
+
+        it("Allow to send encrypted in clear room", async () => {
+            mocked(client.getCrypto()!.isEncryptionEnabledInRoom).mockResolvedValue(false);
 
+            await driver.sendToDevice("org.example.foo", true, contentMap);
+            expect(client.getCrypto()!.encryptToDeviceMessages).toHaveBeenCalled();
+            expect(client.queueToDevice).toHaveBeenCalledWith(
+                expect.objectContaining({
+                    eventType: "m.room.encrypted",
+                }),
+            );
+        });
+
+        it("Should default to encrypted traffic for non-room widgets", async () => {
+            const driver = new StopGapWidgetDriver(
+                [],
+                new Widget({
+                    id: "an_id",
+                    creatorUserId: "@alice:example.org",
+                    type: WidgetType.CUSTOM.preferred,
+                    url: "https://call.element.io",
+                }),
+                WidgetKind.Account,
+                true,
+            );
+
+            await driver.sendToDevice("org.example.foo", false, contentMap);
+            expect(client.getCrypto()!.encryptToDeviceMessages).toHaveBeenCalled();
+            expect(client.queueToDevice).toHaveBeenCalledWith(
+                expect.objectContaining({
+                    eventType: "m.room.encrypted",
+                }),
+            );
+        });
+
+        it("sends encrypted messages", async () => {
             await driver.sendToDevice("org.example.foo", true, {
                 "@alice:example.org": {
                     aliceMobile: {
@@ -235,14 +280,14 @@ describe("StopGapWidgetDriver", () => {
                 },
             });
 
-            expect(encryptToDeviceMessages).toHaveBeenCalledWith(
+            expect(client.getCrypto()!.encryptToDeviceMessages).toHaveBeenCalledWith(
                 "org.example.foo",
                 [{ deviceId: "aliceMobile", userId: "@alice:example.org" }],
                 {
                     hello: "alice",
                 },
             );
-            expect(encryptToDeviceMessages).toHaveBeenCalledWith(
+            expect(client.getCrypto()!.encryptToDeviceMessages).toHaveBeenCalledWith(
                 "org.example.foo",
                 [{ deviceId: "bobDesktop", userId: "@bob:example.org" }],
                 {
@@ -252,21 +297,19 @@ describe("StopGapWidgetDriver", () => {
             expect(client.queueToDevice).toHaveBeenCalledWith({
                 eventType: "m.room.encrypted",
                 batch: expect.arrayContaining([
-                    {
+                    expect.objectContaining({
                         deviceId: "aliceMobile",
-                        payload: { content: { hello: "alice" }, eventType: "org.example.foo" },
                         userId: "@alice:example.org",
-                    },
+                    }),
                 ]),
             });
             expect(client.queueToDevice).toHaveBeenCalledWith({
                 eventType: "m.room.encrypted",
                 batch: expect.arrayContaining([
-                    {
+                    expect.objectContaining({
                         deviceId: "bobDesktop",
-                        payload: { content: { hello: "bob" }, eventType: "org.example.foo" },
                         userId: "@bob:example.org",
-                    },
+                    }),
                 ]),
             });
         });