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Commit 496037de authored by wilsonshih's avatar wilsonshih
Browse files

Create or rename a scramble folder for task snapshots. 

Enhance file security by making the file path unpredictable and
difficult to guess.
Create or rename the scramble folder when first access happen.

Flag: com.android.window.flags.scramble_snapshot_file_name
Bug: 293139053
Test: atest TaskSnapshotCacheTest TaskSnapshotLowResDisabledTest
TaskSnapshotPersisterLoaderTest ActivitySnapshotControllerTests

Change-Id: Ie83e381f3a9fe32bdea6378103fd762251a5faa0
parent 7a3c826d

core/java/android/window/flags/windowing_frontend.aconfig

+11 −0
Original line number Diff line number Diff line
@@ -494,3 +494,14 @@ flag { 
            purpose: PURPOSE_BUGFIX

    }

}



flag {

    name: "scramble_snapshot_file_name"

    namespace: "windowing_frontend"

    description: "Scramble the file name of task snapshot."

    bug: "293139053"

    is_fixed_read_only: true

    metadata {

        purpose: PURPOSE_BUGFIX

    }

}
 
 No newline at end of file

services/core/java/com/android/server/wm/ActivitySnapshotController.java

+6 −2
Original line number Diff line number Diff line
@@ -107,8 +107,7 @@ class ActivitySnapshotController extends AbsAppSnapshotController<ActivityRecord 
                && !ActivityManager.isLowRamDeviceStatic(); // Don't support Android Go

        setSnapshotEnabled(snapshotEnabled);

        mSnapshotPersistQueue = persistQueue;

        mPersistInfoProvider = createPersistInfoProvider(service,

                Environment::getDataSystemCeDirectory);

        mPersistInfoProvider = createPersistInfoProvider(service);

        mPersister = new TaskSnapshotPersister(

                persistQueue,

                mPersistInfoProvider,
@@ -117,6 +116,11 @@ class ActivitySnapshotController extends AbsAppSnapshotController<ActivityRecord 
        initialize(new ActivitySnapshotCache());

    }



    @VisibleForTesting

    PersistInfoProvider createPersistInfoProvider(WindowManagerService service) {

        return createPersistInfoProvider(service, Environment::getDataSystemCeDirectory);

    }



    @Override

    protected float initSnapshotScale() {

        final float config = mService.mContext.getResources().getFloat(

services/core/java/com/android/server/wm/BaseAppSnapshotPersister.java

+84 −0
Original line number Diff line number Diff line
@@ -16,10 +16,20 @@ 


package com.android.server.wm;



import static com.android.server.wm.AbsAppSnapshotController.TAG;



import android.annotation.NonNull;

import android.annotation.Nullable;

import android.util.Slog;

import android.util.SparseArray;

import android.util.SparseBooleanArray;

import android.window.TaskSnapshot;



import com.android.internal.annotations.VisibleForTesting;

import com.android.window.flags.Flags;



import java.io.File;

import java.util.UUID;



class BaseAppSnapshotPersister {

    static final String LOW_RES_FILE_POSTFIX = "_reduced";
@@ -29,6 +39,7 @@ class BaseAppSnapshotPersister { 
    // Shared with SnapshotPersistQueue

    protected final Object mLock;

    protected final SnapshotPersistQueue mSnapshotPersistQueue;

    @VisibleForTesting

    protected final PersistInfoProvider mPersistInfoProvider;



    BaseAppSnapshotPersister(SnapshotPersistQueue persistQueue,
@@ -79,6 +90,8 @@ class BaseAppSnapshotPersister { 
        private final boolean mEnableLowResSnapshots;

        private final float mLowResScaleFactor;

        private final boolean mUse16BitFormat;

        private final SparseBooleanArray mInitializedUsers = new SparseBooleanArray();

        private final SparseArray<File> mScrambleDirectories = new SparseArray<>();



        PersistInfoProvider(DirectoryResolver directoryResolver, String dirName,

                boolean enableLowResSnapshots, float lowResScaleFactor, boolean use16BitFormat) {
@@ -91,9 +104,80 @@ class BaseAppSnapshotPersister { 


        @NonNull

        File getDirectory(int userId) {

            if (Flags.scrambleSnapshotFileName()) {

                final File directory = getOrInitScrambleDirectory(userId);

                if (directory != null) {

                    return directory;

                }

            }

            return getBaseDirectory(userId);

        }



        @NonNull

        private File getBaseDirectory(int userId) {

            return new File(mDirectoryResolver.getSystemDirectoryForUser(userId), mDirName);

        }



        @Nullable

        private File getOrInitScrambleDirectory(int userId) {

            synchronized (mScrambleDirectories) {

                if (mInitializedUsers.get(userId)) {

                    return mScrambleDirectories.get(userId);

                }

                mInitializedUsers.put(userId, true);

                final File scrambledDirectory = getScrambleDirectory(userId);

                final File baseDir = getBaseDirectory(userId);

                String newName = null;

                // If directory exists, rename

                if (scrambledDirectory.exists()) {

                    newName = UUID.randomUUID().toString();

                    final File scrambleTo = new File(baseDir, newName);

                    if (!scrambledDirectory.renameTo(scrambleTo)) {

                        Slog.w(TAG, "SnapshotPersister rename scramble folder fail.");

                        return null;

                    }

                } else {

                    // If directory not exists, mkDir.

                    if (!baseDir.exists() && !baseDir.mkdir()) {

                        Slog.w(TAG, "SnapshotPersister make base folder fail.");

                        return null;

                    }

                    if (!scrambledDirectory.mkdir()) {

                        Slog.e(TAG, "SnapshotPersister make scramble folder fail");

                        return null;

                    }

                    // Move any existing files to this folder.

                    final String[] files = baseDir.list();

                    if (files != null) {

                        for (String file : files) {

                            final File original = new File(baseDir, file);

                            if (original.isDirectory()) {

                                newName = file;

                            } else {

                                File to = new File(scrambledDirectory, file);

                                original.renameTo(to);

                            }

                        }

                    }

                }

                final File newFolder = new File(baseDir, newName);

                mScrambleDirectories.put(userId, newFolder);

                return newFolder;

            }

        }



        @NonNull

        private File getScrambleDirectory(int userId) {

            final File dir = getBaseDirectory(userId);

            final String[] directories = dir.list(

                    (current, name) -> new File(current, name).isDirectory());

            if (directories != null && directories.length > 0) {

                return new File(dir, directories[0]);

            } else {

                return new File(dir, UUID.randomUUID().toString());

            }

        }



        /**

         * Return if task snapshots are stored in 16 bit pixel format.

         *

services/tests/wmtests/src/com/android/server/wm/ActivitySnapshotControllerTests.java

+13 −1
Original line number Diff line number Diff line
@@ -63,11 +63,23 @@ public class ActivitySnapshotControllerTests extends TaskSnapshotPersisterTestBa 
        super(0.8f /* highResScale */, 0.5f /* lowResScale */);

    }



    private class TestActivitySnapshotController extends ActivitySnapshotController {

        TestActivitySnapshotController(WindowManagerService service,

                SnapshotPersistQueue persistQueue) {

            super(service, persistQueue);

        }

        @Override

        BaseAppSnapshotPersister.PersistInfoProvider createPersistInfoProvider(

                WindowManagerService service) {

            return mPersister.mPersistInfoProvider;

        }

    }

    @Override

    @Before

    public void setUp() {

        super.setUp();

        mActivitySnapshotController = new ActivitySnapshotController(mWm, mSnapshotPersistQueue);

        mActivitySnapshotController = new TestActivitySnapshotController(

                mWm, mSnapshotPersistQueue);

        spyOn(mActivitySnapshotController);

        doReturn(false).when(mActivitySnapshotController).shouldDisableSnapshots();

        mActivitySnapshotController.resetTmpFields();

services/tests/wmtests/src/com/android/server/wm/TaskSnapshotLowResDisabledTest.java

+7 −21
Original line number Diff line number Diff line
@@ -68,11 +68,8 @@ public class TaskSnapshotLowResDisabledTest extends TaskSnapshotPersisterTestBas 
    public void testPersistAndLoadSnapshot() {

        mPersister.persistSnapshot(1, mTestUserId, createSnapshot());

        mSnapshotPersistQueue.waitForQueueEmpty();

        final File[] files = new File[]{

                new File(FILES_DIR.getPath() + "/snapshots/1.proto"),

                new File(FILES_DIR.getPath() + "/snapshots/1.jpg")};

        final File[] nonExistsFiles = new File[]{

                new File(FILES_DIR.getPath() + "/snapshots/1_reduced.jpg")};

        final File[] files = convertFilePath("1.proto", "1.jpg");

        final File[] nonExistsFiles = convertFilePath("1_reduced.proto");

        assertTrueForFiles(files, File::exists, " must exist");

        assertTrueForFiles(nonExistsFiles, file -> !file.exists(), " must not exist");

        final TaskSnapshot snapshot = mLoader.loadTask(1, mTestUserId, false /* isLowResolution */);
@@ -92,14 +89,9 @@ public class TaskSnapshotLowResDisabledTest extends TaskSnapshotPersisterTestBas 
        taskIds.add(1);

        mPersister.removeObsoleteFiles(taskIds, new int[]{mTestUserId});

        mSnapshotPersistQueue.waitForQueueEmpty();

        final File[] existsFiles = new File[]{

                new File(FILES_DIR.getPath() + "/snapshots/1.proto"),

                new File(FILES_DIR.getPath() + "/snapshots/1.jpg")};

        final File[] nonExistsFiles = new File[]{

                new File(FILES_DIR.getPath() + "/snapshots/1_reduced.jpg"),

                new File(FILES_DIR.getPath() + "/snapshots/2.proto"),

                new File(FILES_DIR.getPath() + "/snapshots/2.jpg"),

                new File(FILES_DIR.getPath() + "/snapshots/2_reduced.jpg")};

        final File[] existsFiles = convertFilePath("1.proto", "1.jpg");

        final File[] nonExistsFiles = convertFilePath("1_reduced.proto", "2.proto", "2.jpg",

                "2_reduced.jpg");

        assertTrueForFiles(existsFiles, File::exists, " must exist");

        assertTrueForFiles(nonExistsFiles, file -> !file.exists(), " must not exist");

    }
@@ -112,14 +104,8 @@ public class TaskSnapshotLowResDisabledTest extends TaskSnapshotPersisterTestBas 
        mPersister.removeObsoleteFiles(taskIds, new int[]{mTestUserId});

        mPersister.persistSnapshot(2, mTestUserId, createSnapshot());

        mSnapshotPersistQueue.waitForQueueEmpty();

        final File[] existsFiles = new File[]{

                new File(FILES_DIR.getPath() + "/snapshots/1.proto"),

                new File(FILES_DIR.getPath() + "/snapshots/1.jpg"),

                new File(FILES_DIR.getPath() + "/snapshots/2.proto"),

                new File(FILES_DIR.getPath() + "/snapshots/2.jpg")};

        final File[] nonExistsFiles = new File[]{

                new File(FILES_DIR.getPath() + "/snapshots/1_reduced.jpg"),

                new File(FILES_DIR.getPath() + "/snapshots/2_reduced.jpg")};

        final File[] existsFiles = convertFilePath("1.proto", "1.jpg", "2.proto", "2.jpg");

        final File[] nonExistsFiles = convertFilePath("1_reduced.jpg", "2_reduced.jpg");

        assertTrueForFiles(existsFiles, File::exists, " must exist");

        assertTrueForFiles(nonExistsFiles, file -> !file.exists(), " must not exist");

    }