Merge "Add crash detection and recovery." into sc-dev

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

@@ -0,0 +1,92 @@
+/*
+ * 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

@@ -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());
     }
 
-
+    private void initialize() {
-    @NonNull
+        synchronized (FontManagerService.this) {
-    private final Context mContext;
+            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.");
             }
-            mUpdatableFontDir.installFontFile(fd, pkcs7Signature);
+            try (FontCrashDetector.MonitoredBlock ignored = mFontCrashDetector.start()) {
-            // Create updated font map in the next getSerializedSystemFontMap() call.
+                mUpdatableFontDir.installFontFile(fd, pkcs7Signature);
-            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.");
         }
-        mUpdatableFontDir.clearUpdates();
+        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

@@ -142,11 +142,9 @@ final class UpdatableFontDir {
         mFsverityUtil = fsverityUtil;
         mConfigFile = configFile;
         mTmpConfigFile = new File(configFile.getAbsoluteFile() + ".tmp");
-        loadFontFileMap();
     }
 
-    private void loadFontFileMap() {
+    /* package */ void loadFontFileMap() {
-        // TODO: SIGBUS crash protection
         synchronized (UpdatableFontDir.this) {
             boolean success = false;
 

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

@@ -0,0 +1,77 @@
+/*
+ * 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

@@ -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);