Add MTE Settings.

MTE is a technology to help prevent exploitation of some security bugs.
We want to offer users that want to trade off a slight reduction in
performance for higher security the option to do so from the settings
menu.

Test: make RunSettingsRoboTests
      check UI manually
Bug: 245624194
Change-Id: Ifbb76e124142ae843ce90bd604ae8417d65fcc7b

src/com/android/settings/security/MemtagFooterPreferenceController.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2022 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.settings.security;
+
+import android.content.Context;
+import android.text.TextUtils;
+
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+import com.android.settingslib.HelpUtils;
+import com.android.settingslib.widget.FooterPreference;
+
+/** Footer for face settings showing the help text and help link. */
+public class MemtagFooterPreferenceController extends BasePreferenceController {
+
+    public MemtagFooterPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AVAILABLE_UNSEARCHABLE;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        // Set up learn more link.
+        FooterPreference prefFooter = screen.findPreference(getPreferenceKey());
+        String helpUrl = mContext.getString(R.string.help_url_memtag);
+        if (prefFooter != null && !TextUtils.isEmpty(helpUrl)) {
+            prefFooter.setLearnMoreAction(
+                    v ->
+                            mContext.startActivity(
+                                    HelpUtils.getHelpIntent(
+                                            mContext, helpUrl, /* backupContext= */ "")));
+            prefFooter.setLearnMoreText(mContext.getString(R.string.memtag_learn_more));
+        }
+    }
+}

src/com/android/settings/security/MemtagHelper.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2022 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.settings.security;
+
+import android.os.SystemProperties;
+
+import com.android.internal.os.Zygote;
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+
+import java.util.Arrays;
+
+public class MemtagHelper {
+    private static boolean isForcedOff() {
+        return "force_off"
+                .equals(
+                        SystemProperties.get(
+                                "persist.device_config.memory_safety_native.bootloader_override"));
+    }
+
+    public static boolean isChecked() {
+        String modes[] = SystemProperties.get("arm64.memtag.bootctl", "").split(",");
+        return Arrays.asList(modes).contains("memtag");
+    }
+
+    public static void setChecked(boolean isChecked) {
+        String newString = isChecked ? "memtag" : "none";
+        SystemProperties.set("arm64.memtag.bootctl", newString);
+    }
+
+    public static int getAvailabilityStatus() {
+        if (MemtagHelper.isForcedOff()) {
+            return BasePreferenceController.DISABLED_DEPENDENT_SETTING;
+        }
+        return SystemProperties.getBoolean("ro.arm64.memtag.bootctl_supported", false)
+                ? BasePreferenceController.AVAILABLE
+                : BasePreferenceController.UNSUPPORTED_ON_DEVICE;
+    }
+
+    /**
+     * Returns whether MTE is currently active on this device. We use this to determine whether we
+     * need to reboot the device to apply the user choice.
+     *
+     * @return boolean whether MTE is currently active
+     */
+    public static boolean isOn() {
+        return Zygote.nativeSupportsMemoryTagging();
+    }
+
+    public static int getSummary() {
+        if (isForcedOff()) {
+            return R.string.memtag_force_off;
+        }
+        if (isOn()) {
+            if (isChecked()) {
+                return R.string.memtag_on;
+            }
+            return R.string.memtag_off_pending;
+        }
+        if (isChecked()) {
+            return R.string.memtag_on_pending;
+        }
+        return R.string.memtag_off;
+    }
+}

src/com/android/settings/security/MemtagPage.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2022 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.settings.security;
+
+import android.app.settings.SettingsEnums;
+import android.content.Context;
+
+import com.android.settings.R;
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settings.search.BaseSearchIndexProvider;
+import com.android.settingslib.search.SearchIndexable;
+
+@SearchIndexable
+public class MemtagPage extends DashboardFragment {
+
+    private static final String TAG = "MemtagPage";
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.SETTINGS_MEMTAG_CATEGORY;
+    }
+
+    @Override
+    protected String getLogTag() {
+        return TAG;
+    }
+
+    @Override
+    public void onAttach(Context context) {
+        super.onAttach(context);
+
+        use(MemtagPreferenceController.class).setFragment(this);
+    }
+
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.memtag_page;
+    }
+
+    public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
+            new BaseSearchIndexProvider(R.xml.memtag_page);
+}

src/com/android/settings/security/MemtagPagePreferenceController.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2022 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.settings.security;
+
+import android.content.Context;
+
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.core.BasePreferenceController;
+
+public class MemtagPagePreferenceController extends BasePreferenceController {
+    static final String KEY_MEMTAG = "memtag_page";
+
+    public MemtagPagePreferenceController(Context context, String key) {
+        super(context, key);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return MemtagHelper.getAvailabilityStatus();
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        Preference preference = screen.findPreference(getPreferenceKey());
+        refreshSummary(preference);
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        return mContext.getResources().getString(MemtagHelper.getSummary());
+    }
+}

src/com/android/settings/security/MemtagPreferenceController.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2022 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.settings.security;
+
+import android.content.Context;
+
+import androidx.fragment.app.Fragment;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.R;
+import com.android.settings.core.TogglePreferenceController;
+
+public class MemtagPreferenceController extends TogglePreferenceController {
+    private Preference mPreference;
+    private Fragment mFragment;
+
+    public MemtagPreferenceController(Context context, String key) {
+        super(context, key);
+    }
+
+    public void setFragment(Fragment fragment) {
+        mFragment = fragment;
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return MemtagHelper.getAvailabilityStatus();
+    }
+
+    @Override
+    public boolean isChecked() {
+        return MemtagHelper.isChecked();
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        MemtagHelper.setChecked(isChecked);
+        if (mPreference != null) {
+            refreshSummary(mPreference);
+        }
+        if (isChecked != MemtagHelper.isOn()) {
+            MemtagRebootDialog.show(mContext, mFragment, isChecked);
+        }
+        return true;
+    }
+
+    @Override
+    public int getSliceHighlightMenuRes() {
+        return R.string.menu_key_security;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(getPreferenceKey());
+        refreshSummary(mPreference);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        refreshSummary(preference);
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        return mContext.getResources().getString(MemtagHelper.getSummary());
+    }
+}

src/com/android/settings/security/MemtagRebootDialog.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2022 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.settings.security;
+
+import android.app.Dialog;
+import android.app.settings.SettingsEnums;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.os.Bundle;
+import android.os.PowerManager;
+
+import androidx.appcompat.app.AlertDialog;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+
+import com.android.settings.R;
+import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
+
+public class MemtagRebootDialog extends InstrumentedDialogFragment
+        implements DialogInterface.OnClickListener, DialogInterface.OnDismissListener {
+
+    public static final String TAG = "MemtagRebootDialog";
+    private boolean mIsChecked;
+
+    public MemtagRebootDialog(Context context, boolean isChecked) {
+        mIsChecked = isChecked;
+    }
+
+    public static void show(Context context, Fragment host, boolean isChecked) {
+        final FragmentManager manager = host.getActivity().getSupportFragmentManager();
+        if (manager.findFragmentByTag(TAG) == null) {
+            final MemtagRebootDialog dialog = new MemtagRebootDialog(context, isChecked);
+            dialog.show(manager, TAG);
+        }
+    }
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.REBOOT_WITH_MTE;
+    }
+
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        int msg =
+                mIsChecked ? R.string.memtag_reboot_message_on : R.string.memtag_reboot_message_off;
+        return new AlertDialog.Builder(getActivity())
+                .setTitle(R.string.memtag_reboot_title)
+                .setMessage(msg)
+                .setPositiveButton(R.string.memtag_reboot_yes, this /* onClickListener */)
+                .setNegativeButton(R.string.memtag_reboot_no, null /* onClickListener */)
+                .create();
+    }
+
+    @Override
+    public void onClick(DialogInterface dialog, int which) {
+        PowerManager pm = getContext().getSystemService(PowerManager.class);
+        pm.reboot(/* reason */ null);
+    }
+}