Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit de417e73 authored by Kohsuke Yatoh's avatar Kohsuke Yatoh
Browse files

Add crash detection and recovery. 

Bug: 176939176
Test: atest FrameworksServicesTests:FontCrashDetectorTest
Test: atest FrameworksServicesTests:UpdatableFontDirTest
Change-Id: I435898d080fb2ebaf47dd4989a9d8f70d95be52b
parent ad685084

services/core/java/com/android/server/graphics/fonts/FontCrashDetector.java

0 → 100644
+92 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2021 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



package com.android.server.graphics.fonts;



import android.annotation.NonNull;

import android.util.Slog;



import java.io.File;

import java.io.IOException;



/**

 * A class to detect font-related native crash.

 *

 * <p>If a fs-verity protected file is accessed through mmap and corrupted file block is detected,

 * SIGBUG signal is generated and the process will crash. To find corrupted files and remove them,

 * we use a marker file to detect crash.

 * <ol>

 *     <li>Create a marker file before reading fs-verity protected font files.

 *     <li>Delete the marker file after reading font files successfully.

 *     <li>If the marker file is found in the next process startup, it means that the process

 *         crashed before. We will delete font files to prevent crash loop.

 * </ol>

 *

 * <p>Example usage:

 * <pre>

 *     FontCrashDetector detector = new FontCrashDetector(new File("/path/to/marker_file"));

 *     if (detector.hasCrashed()) {

 *         // Do cleanup

 *     }

 *     try (FontCrashDetector.MonitoredBlock b = detector.start()) {

 *         // Read files

 *     }

 * </pre>

 *

 * <p>This class DOES NOT detect Java exceptions. If a Java exception is thrown while monitoring

 * crash, the marker file will be deleted. Creating and deleting marker files are not lightweight.

 * Please use this class sparingly with caution.

 */

/* package */ final class FontCrashDetector {



    private static final String TAG = "FontCrashDetector";



    @NonNull

    private final File mMarkerFile;



    /* package */ FontCrashDetector(@NonNull File markerFile) {

        mMarkerFile = markerFile;

    }



    /* package */ boolean hasCrashed() {

        return mMarkerFile.exists();

    }



    /* package */ void clear() {

        if (!mMarkerFile.delete()) {

            Slog.e(TAG, "Could not delete marker file: " + mMarkerFile);

        }

    }



    /** Starts crash monitoring. */

    /* package */ MonitoredBlock start() {

        try {

            mMarkerFile.createNewFile();

        } catch (IOException e) {

            Slog.e(TAG, "Could not create marker file: " + mMarkerFile, e);

        }

        return new MonitoredBlock();

    }



    /** A helper class to monitor crash with try-with-resources syntax. */

    /* package */ class MonitoredBlock implements AutoCloseable {

        /** Ends crash monitoring. */

        @Override

        public void close() {

            clear();

        }

    }

}

services/core/java/com/android/server/graphics/fonts/FontManagerService.java

+42 −11
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ public final class FontManagerService extends IFontManager.Stub { 
    private static final String TAG = "FontManagerService";



    private static final String FONT_FILES_DIR = "/data/fonts/files";

    private static final String CRASH_MARKER_FILE = "/data/fonts/config/crash.txt";



    @Override

    public FontConfig getFontConfig() throws RemoteException {
@@ -179,6 +180,13 @@ public final class FontManagerService extends IFontManager.Stub { 
        }

    }



    @NonNull

    private final Context mContext;



    @GuardedBy("FontManagerService.this")

    @NonNull

    private final FontCrashDetector mFontCrashDetector;



    @Nullable

    private final UpdatableFontDir mUpdatableFontDir;
@@ -188,7 +196,9 @@ public final class FontManagerService extends IFontManager.Stub { 


    private FontManagerService(Context context) {

        mContext = context;

        mFontCrashDetector = new FontCrashDetector(new File(CRASH_MARKER_FILE));

        mUpdatableFontDir = createUpdatableFontDir();

        initialize();

    }



    @Nullable
@@ -201,20 +211,35 @@ public final class FontManagerService extends IFontManager.Stub { 
                new OtfFontFileParser(), new FsverityUtilImpl());

    }





    @NonNull

    private final Context mContext;

    private void initialize() {

        synchronized (FontManagerService.this) {

            if (mUpdatableFontDir == null) {

                mSerializedFontMap = buildNewSerializedFontMap();

                return;

            }

            if (mFontCrashDetector.hasCrashed()) {

                Slog.i(TAG, "Crash detected. Clearing font updates.");

                try {

                    mUpdatableFontDir.clearUpdates();

                } catch (SystemFontException e) {

                    Slog.e(TAG, "Failed to clear updates.", e);

                }

                mFontCrashDetector.clear();

            }

            try (FontCrashDetector.MonitoredBlock ignored = mFontCrashDetector.start()) {

                mUpdatableFontDir.loadFontFileMap();

                mSerializedFontMap = buildNewSerializedFontMap();

            }

        }

    }



    @NonNull

    public Context getContext() {

        return mContext;

    }



    @NonNull /* package */ SharedMemory getCurrentFontMap() {

    @Nullable /* package */ SharedMemory getCurrentFontMap() {

        synchronized (FontManagerService.this) {

            if (mSerializedFontMap == null) {

                mSerializedFontMap = buildNewSerializedFontMap();

            }

            return mSerializedFontMap;

        }

    }
@@ -234,9 +259,10 @@ public final class FontManagerService extends IFontManager.Stub { 
                        FontManager.RESULT_ERROR_VERSION_MISMATCH,

                        "The base config version is older than current.");

            }

            try (FontCrashDetector.MonitoredBlock ignored = mFontCrashDetector.start()) {

                mUpdatableFontDir.installFontFile(fd, pkcs7Signature);

            // Create updated font map in the next getSerializedSystemFontMap() call.

            mSerializedFontMap = null;

                mSerializedFontMap = buildNewSerializedFontMap();

            }

        }

    }
@@ -246,7 +272,12 @@ public final class FontManagerService extends IFontManager.Stub { 
                    FontManager.RESULT_ERROR_FONT_UPDATER_DISABLED,

                    "The font updater is disabled.");

        }

        synchronized (FontManagerService.this) {

            try (FontCrashDetector.MonitoredBlock ignored = mFontCrashDetector.start()) {

                mUpdatableFontDir.clearUpdates();

                mSerializedFontMap = buildNewSerializedFontMap();

            }

        }

    }



    /* package */ Map<String, File> getFontFileMap() {

services/core/java/com/android/server/graphics/fonts/UpdatableFontDir.java

+1 −3
Original line number Diff line number Diff line
@@ -142,11 +142,9 @@ final class UpdatableFontDir { 
        mFsverityUtil = fsverityUtil;

        mConfigFile = configFile;

        mTmpConfigFile = new File(configFile.getAbsoluteFile() + ".tmp");

        loadFontFileMap();

    }



    private void loadFontFileMap() {

        // TODO: SIGBUS crash protection

    /* package */ void loadFontFileMap() {

        synchronized (UpdatableFontDir.this) {

            boolean success = false;

services/tests/servicestests/src/com/android/server/graphics/fonts/FontCrashDetectorTest.java

0 → 100644
+77 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2021 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



package com.android.server.graphics.fonts;



import static com.google.common.truth.Truth.assertThat;



import android.content.Context;

import android.os.FileUtils;

import android.platform.test.annotations.Presubmit;



import androidx.test.InstrumentationRegistry;

import androidx.test.filters.SmallTest;

import androidx.test.runner.AndroidJUnit4;



import org.junit.Before;

import org.junit.Test;

import org.junit.runner.RunWith;



import java.io.File;



@Presubmit

@SmallTest

@RunWith(AndroidJUnit4.class)

public final class FontCrashDetectorTest {



    private File mCacheDir;



    @SuppressWarnings("ResultOfMethodCallIgnored")

    @Before

    public void setUp() {

        Context context = InstrumentationRegistry.getInstrumentation().getTargetContext();

        mCacheDir = new File(context.getCacheDir(), "UpdatableFontDirTest");

        FileUtils.deleteContentsAndDir(mCacheDir);

        mCacheDir.mkdirs();

    }



    @Test

    public void detectCrash() throws Exception {

        // Prepare a marker file.

        File file = new File(mCacheDir, "detectCrash");

        assertThat(file.createNewFile()).isTrue();



        FontCrashDetector detector = new FontCrashDetector(file);

        assertThat(detector.hasCrashed()).isTrue();



        detector.clear();

        assertThat(detector.hasCrashed()).isFalse();

        assertThat(file.exists()).isFalse();

    }



    @Test

    public void monitorCrash() {

        File file = new File(mCacheDir, "monitorCrash");

        FontCrashDetector detector = new FontCrashDetector(file);

        assertThat(detector.hasCrashed()).isFalse();



        FontCrashDetector.MonitoredBlock block = detector.start();

        assertThat(file.exists()).isTrue();



        block.close();

        assertThat(file.exists()).isFalse();

    }

}

services/tests/servicestests/src/com/android/server/graphics/fonts/UpdatableFontDirTest.java

+20 −0
Original line number Diff line number Diff line
@@ -147,6 +147,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dirForPreparation = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dirForPreparation.loadFontFileMap();

        assertThat(dirForPreparation.getSystemFontConfig().getLastModifiedTimeMillis())

                .isEqualTo(expectedModifiedDate);

        installFontFile(dirForPreparation, "foo,1", GOOD_SIGNATURE);
@@ -162,6 +163,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();

        assertThat(dir.getFontFileMap()).containsKey("foo.ttf");

        assertThat(parser.getRevision(dir.getFontFileMap().get("foo.ttf"))).isEqualTo(3);

        assertThat(dir.getFontFileMap()).containsKey("bar.ttf");
@@ -177,6 +179,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();

        assertThat(dir.getFontFileMap()).isEmpty();

    }
@@ -187,6 +190,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dirForPreparation = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dirForPreparation.loadFontFileMap();

        installFontFile(dirForPreparation, "foo,1", GOOD_SIGNATURE);

        installFontFile(dirForPreparation, "bar,2", GOOD_SIGNATURE);

        installFontFile(dirForPreparation, "foo,3", GOOD_SIGNATURE);
@@ -199,6 +203,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();

        assertThat(dir.getFontFileMap()).isEmpty();

        // All font dirs (including dir for "bar.ttf") should be deleted.

        assertThat(mUpdatableFontFilesDir.list()).hasLength(0);
@@ -211,6 +216,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dirForPreparation = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dirForPreparation.loadFontFileMap();

        installFontFile(dirForPreparation, "foo,1", GOOD_SIGNATURE);

        installFontFile(dirForPreparation, "bar,2", GOOD_SIGNATURE);

        installFontFile(dirForPreparation, "foo,3", GOOD_SIGNATURE);
@@ -224,6 +230,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();

        assertThat(dir.getFontFileMap()).isEmpty();

        // All font dirs (including dir for "bar.ttf") should be deleted.

        assertThat(mUpdatableFontFilesDir.list()).hasLength(0);
@@ -236,6 +243,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dirForPreparation = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dirForPreparation.loadFontFileMap();

        installFontFile(dirForPreparation, "foo,1", GOOD_SIGNATURE);

        installFontFile(dirForPreparation, "bar,2", GOOD_SIGNATURE);

        installFontFile(dirForPreparation, "foo,3", GOOD_SIGNATURE);
@@ -250,6 +258,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();

        // For foo.ttf, preinstalled font (revision 5) should be used.

        assertThat(dir.getFontFileMap()).doesNotContainKey("foo.ttf");

        // For bar.ttf, updated font (revision 4) should be used.
@@ -268,6 +277,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                new File("/dev/null"));

        dir.loadFontFileMap();

        assertThat(dir.getFontFileMap()).isEmpty();

    }
@@ -278,6 +288,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        installFontFile(dir, "test,1", GOOD_SIGNATURE);

        assertThat(dir.getFontFileMap()).containsKey("test.ttf");
@@ -295,6 +306,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        installFontFile(dir, "test,1", GOOD_SIGNATURE);

        Map<String, File> mapBeforeUpgrade = dir.getFontFileMap();
@@ -313,6 +325,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        installFontFile(dir, "test,2", GOOD_SIGNATURE);

        try {
@@ -333,6 +346,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        installFontFile(dir, "foo,1", GOOD_SIGNATURE);

        installFontFile(dir, "bar,2", GOOD_SIGNATURE);
@@ -349,6 +363,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        try {

            installFontFile(dir, "test,1", "Invalid signature");
@@ -368,6 +383,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        try {

            installFontFile(dir, "test,1", GOOD_SIGNATURE);
@@ -398,6 +414,7 @@ public final class UpdatableFontDirTest { 
            UpdatableFontDir dir = new UpdatableFontDir(

                    mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                    readonlyFile);

            dir.loadFontFileMap();



            try {

                installFontFile(dir, "test,2", GOOD_SIGNATURE);
@@ -429,6 +446,7 @@ public final class UpdatableFontDirTest { 
                        return 0;

                    }

                }, fakeFsverityUtil, mConfigFile);

        dir.loadFontFileMap();



        try {

            installFontFile(dir, "foo,1", GOOD_SIGNATURE);
@@ -456,6 +474,7 @@ public final class UpdatableFontDirTest { 
                        return 0;

                    }

                }, fakeFsverityUtil, mConfigFile);

        dir.loadFontFileMap();



        try {

            installFontFile(dir, "foo,1", GOOD_SIGNATURE);
@@ -491,6 +510,7 @@ public final class UpdatableFontDirTest { 
        UpdatableFontDir dir = new UpdatableFontDir(

                mUpdatableFontFilesDir, mPreinstalledFontDirs, parser, fakeFsverityUtil,

                mConfigFile);

        dir.loadFontFileMap();



        try {

            installFontFile(dir, "foo,1", GOOD_SIGNATURE);