commit ca1e0064d9dcb824e6c8eda8472e4623cea4c3db
author Austin Borger <borgera@google.com> Wed Jun 28 11:32:55 2023 -0700
committer Austin Borger <borgera@google.com> Wed Feb 14 17:48:22 2024 -0800
tree 8f2cf587db4733b96d15aae1a4d08b7c90c3a308
parent ffff5ff5d67aeed595016c9007173012b2f803e3

CameraService: Watch for foreground changes from AppOps

AppOps now sends notifications when an app loses its camera capability.
We should watch for these notifications and block clients when they
happen, assuming they're untrusted. Otherwise, an app that should not
have camera access outside of the foreground may retain it.

Bug: 290086710
Test: Ran on physical device, tested Zoom + GCA
Change-Id: Ie69f96d91ec3898114a2c106afe3d42143cd8d33

services/camera/libcameraservice/CameraService.cpp

diff --git a/services/camera/libcameraservice/CameraService.cpp b/services/camera/libcameraservice/CameraService.cpp
index 7202532..2d55f39 100644
--- a/services/camera/libcameraservice/CameraService.cpp
+++ b/services/camera/libcameraservice/CameraService.cpp
@@ -4288,8 +4288,15 @@
     if (mAppOpsManager != nullptr) {
         // Notify app ops that the camera is not available
         mOpsCallback = new OpsCallback(this);
-        mAppOpsManager->startWatchingMode(AppOpsManager::OP_CAMERA,
+
+        if (flags::watch_foreground_changes()) {
+            mAppOpsManager->startWatchingMode(AppOpsManager::OP_CAMERA,
+                toString16(mClientPackageName),
+                AppOpsManager::WATCH_FOREGROUND_CHANGES, mOpsCallback);
+        } else {
+            mAppOpsManager->startWatchingMode(AppOpsManager::OP_CAMERA,
                 toString16(mClientPackageName), mOpsCallback);
+        }
 
         // Just check for camera acccess here on open - delay startOp until
         // camera frames start streaming in startCameraStreamingOps
@@ -4450,6 +4457,11 @@
     } else if (res == AppOpsManager::MODE_IGNORED) {
         bool isUidActive = sCameraService->mUidPolicy->isUidActive(mClientUid, mClientPackageName);
 
+        // Uid may be active, but not visible to the user (e.g. PROCESS_STATE_FOREGROUND_SERVICE).
+        // If not visible, but still active, then we want to block instead of muting the camera.
+        int32_t procState = sCameraService->mUidPolicy->getProcState(mClientUid);
+        bool isUidVisible = (procState <= ActivityManager::PROCESS_STATE_BOUND_TOP);
+
         bool isCameraPrivacyEnabled;
         if (flags::camera_privacy_allowlist()) {
             isCameraPrivacyEnabled = sCameraService->isCameraPrivacyEnabled(
@@ -4460,17 +4472,26 @@
         }
 
         ALOGI("Camera %s: Access for \"%s\" has been restricted, isUidTrusted %d, isUidActive %d"
-                " isCameraPrivacyEnabled %d", mCameraIdStr.c_str(), mClientPackageName.c_str(),
-                mUidIsTrusted, isUidActive, isCameraPrivacyEnabled);
-        // If the calling Uid is trusted (a native service), or the client Uid is active (WAR for
-        // b/175320666), the AppOpsManager could return MODE_IGNORED. Do not treat such cases as
-        // error.
+                " isUidVisible %d, isCameraPrivacyEnabled %d", mCameraIdStr.c_str(),
+                mClientPackageName.c_str(), mUidIsTrusted, isUidActive, isUidVisible,
+                isCameraPrivacyEnabled);
+        // If the calling Uid is trusted (a native service), or the client Uid is active / visible
+        // (WAR for b/175320666)the AppOpsManager could return MODE_IGNORED. Do not treat such
+        // cases as error.
         if (!mUidIsTrusted) {
-            if (isUidActive && isCameraPrivacyEnabled && supportsCameraMute()) {
-                setCameraMute(true);
-            } else if (!isUidActive
-                || (isCameraPrivacyEnabled && !supportsCameraMute())) {
-                block();
+            if (flags::watch_foreground_changes()) {
+                if (isUidVisible && isCameraPrivacyEnabled && supportsCameraMute()) {
+                    setCameraMute(true);
+                } else {
+                    block();
+                }
+            } else {
+                if (isUidActive && isCameraPrivacyEnabled && supportsCameraMute()) {
+                    setCameraMute(true);
+                } else if (!isUidActive
+                    || (isCameraPrivacyEnabled && !supportsCameraMute())) {
+                    block();
+                }
             }
         }
     } else if (res == AppOpsManager::MODE_ALLOWED) {