Android 7.1 AppOpsManager默認允許三方應用浮窗權限

平臺

RK3288 + Android 7.1

需求

在高版本的SDK中, 第三方應用申請懸浮窗的權限受到了過一步的限制.
除了要在應用中聲明對權限的申請:

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>

還需要打開設置中的權限:

應用可以通過代碼檢測權限是否已獲取:

            AppOpsManager opsMgr = (AppOpsManager)getSystemService(APP_OPS_SERVICE);
            int res = opsMgr.checkOp(AppOpsManager.OPSTR_SYSTEM_ALERT_WINDOW, Process.myUid(), getPackageName());
            if(res != AppOpsManager.MODE_ALLOWED){
                showToast(AppOpsManager.OPSTR_SYSTEM_ALERT_WINDOW + " not allowed");
            }

有可能會拋出異常:

java.lang.SecurityException: com.android.myapp from uid 10066 not allowed to perform SYSTEM_ALERT_WINDOW

若需要默認打開, 需要修改相關代碼

修改

frameworks/base/services/core/java/com/android/server/AppOpsService.java

    private Ops getOpsRawLocked(int uid, String packageName, boolean edit) {
    	//判斷是否包含在白名單中, 並將其置爲edit 置爲 true.
    	//否則, 默認情況下, 則返回空, 導致在應用或其它服務獲取packageName時, 發現其並未獲取任何操作權限
        edit |= checkIfInWhitelist(packageName);
        UidState uidState = getUidStateLocked(uid, edit);
        if (uidState == null) {
            return null;
        }
        if (uidState.pkgOps == null) {
            if (!edit) {
                return null;
            }
            uidState.pkgOps = new ArrayMap<>();
        }

        Ops ops = uidState.pkgOps.get(packageName);
        if (ops == null) {
            if (!edit) {
                return null;
            }
            boolean isPrivileged = false;
            // This is the first time we have seen this package name under this uid,
            // so let's make sure it is valid.
            if (uid != 0) {
                final long ident = Binder.clearCallingIdentity();
                try {
                    int pkgUid = -1;
                    try {
                        ApplicationInfo appInfo = ActivityThread.getPackageManager()
                                .getApplicationInfo(packageName,
                                        PackageManager.MATCH_DEBUG_TRIAGED_MISSING,
                                        UserHandle.getUserId(uid));
                        if (appInfo != null) {
                            pkgUid = appInfo.uid;
                            isPrivileged = (appInfo.privateFlags
                                    & ApplicationInfo.PRIVATE_FLAG_PRIVILEGED) != 0;
                        } else {
                            if ("media".equals(packageName)) {
                                pkgUid = Process.MEDIA_UID;
                                isPrivileged = false;
                            } else if ("audioserver".equals(packageName)) {
                                pkgUid = Process.AUDIOSERVER_UID;
                                isPrivileged = false;
                            } else if ("cameraserver".equals(packageName)) {
                                pkgUid = Process.CAMERASERVER_UID;
                                isPrivileged = false;
                            }
                        }
                    } catch (RemoteException e) {
                        Slog.w(TAG, "Could not contact PackageManager", e);
                    }
                    if (pkgUid != uid) {
                        // Oops!  The package name is not valid for the uid they are calling
                        // under.  Abort.
                        RuntimeException ex = new RuntimeException("here");
                        ex.fillInStackTrace();
                        Slog.w(TAG, "Bad call: specified package " + packageName
                                + " under uid " + uid + " but it is really " + pkgUid, ex);
                        return null;
                    }
                } finally {
                    Binder.restoreCallingIdentity(ident);
                }
            }
            ops = new Ops(packageName, uidState, isPrivileged);
            if(checkIfInWhitelist(packageName)){
                //添加默認權限並設置爲允許, 這裏只加了SYTEM_ALERT_WINDOW
                Op op = new Op(ops.uidState.uid, ops.packageName, AppOpsManager.OP_SYSTEM_ALERT_WINDOW);
                op.mode = AppOpsManager.MODE_ALLOWED;
                ops.put(op.op, op);
            }
            uidState.pkgOps.put(packageName, ops);
        }
        return ops;
    }

    //allow special package for some permission
    //把需要添加默認權限的應用包名加入到白名單中.
    private boolean checkIfInWhitelist(String pkg){
        if("com.android.testapp".equals(pkg)){
            return true;
        }
        //....更多應用
        return false;
    }

相關代碼

APP安裝後, 權限爲默認值, 即未變更, 默認值:
frameworks/base/core/java/android/app/AppOpsManager.java

    public static final int OP_NONE = -1;
	//..........
    /** @hide */
    public static final int OP_WRITE_SETTINGS = 23;
    /** @hide */
    public static final int OP_SYSTEM_ALERT_WINDOW = 24;

    /**
     * This specifies the default mode for each operation.
     */
    private static int[] sOpDefaultMode = new int[] {
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_IGNORED, // OP_WRITE_SMS
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_DEFAULT, // OP_WRITE_SETTINGS
            AppOpsManager.MODE_DEFAULT, // OP_SYSTEM_ALERT_WINDOW
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_DEFAULT, // OP_GET_USAGE_STATS
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_IGNORED, // OP_PROJECT_MEDIA
            AppOpsManager.MODE_IGNORED, // OP_ACTIVATE_VPN
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ERRORED,  // OP_MOCK_LOCATION
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,  // OP_TURN_ON_SCREEN
            AppOpsManager.MODE_ALLOWED,
            AppOpsManager.MODE_ALLOWED,  // OP_RUN_IN_BACKGROUND
    };

AppOpsManager.MODE_DEFAULT, // OP_SYSTEM_ALERT_WINDOW

• 設置中獲取應用的權限
  packages/apps/Settings/src/com/android/settings/applications/AppStateAppOpsBridge.java

    public PermissionState getPermissionInfo(String pkg, int uid) {
        PermissionState permissionState = new PermissionState(pkg, new UserHandle(UserHandle
                .getUserId(uid)));
        try {
            permissionState.packageInfo = mIPackageManager.getPackageInfo(pkg,
                    PackageManager.GET_PERMISSIONS | PackageManager.MATCH_UNINSTALLED_PACKAGES,
                    permissionState.userHandle.getIdentifier());
            // Check static permission state (whatever that is declared in package manifest)
            String[] requestedPermissions = permissionState.packageInfo.requestedPermissions;
            int[] permissionFlags = permissionState.packageInfo.requestedPermissionsFlags;
            if (requestedPermissions != null) {
                for (int i = 0; i < requestedPermissions.length; i++) {
                    if (doesAnyPermissionMatch(requestedPermissions[i], mPermissions)) {
                        permissionState.permissionDeclared = true;
                        if ((permissionFlags[i] & PackageInfo.REQUESTED_PERMISSION_GRANTED) != 0) {
                            permissionState.staticPermissionGranted = true;
                            break;
                        }
                    }
                }
            }
            // Check app op state.
            List<PackageOps> ops = mAppOpsManager.getOpsForPackage(uid, pkg, mAppOpsOpCodes);
            if (ops != null && ops.size() > 0 && ops.get(0).getOps().size() > 0) {
                permissionState.appOpMode = ops.get(0).getOps().get(0).getMode();
            }
        } catch (RemoteException e) {
            Log.w(TAG, "PackageManager is dead. Can't get package info " + pkg, e);
        }
        return permissionState;
    }

若未變更設置項, mAppOpsManager.getOpsForPackage將返回空
若已變更, 則返回變更後的值

• Android權限管理與AppOpsManager