Support installation of the new app source certificate

The new certificate can be installed from Settings ("Install a
certificate > App Source certificate").  The installation flow includes
a warning with user authorization to proceed, then a prompt for reboot
(now or later).

Installed certificate can be managed in "User credentials".  The name is
currently a hash of hex numbers.

Upon deletion, there will also be a promot for reboot (now or later).

Test: Only see the new setting entry if feature is enabled
Test: Install from Settings, see the expected file name in
      /data/misc/keysetore/user_0.  Reboot also works.
Test: Able to see the certificate in Settings after installed
Test: Able to delete the certificate, which triggers confirmation dialog
      to reboot.  Reboot works.
Test: add certificate, see dialog, "not now" / tapping elsewhere does
      nothing
Test: atest RestrictedEncryptionPreferenceControllerTest
Bug: 112038744

Change-Id: I7a4494ea0f243730df2212076588074d8774ae23

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

@@ -44,6 +44,7 @@ import androidx.fragment.app.FragmentActivity;
 
 import com.android.internal.widget.LockPatternUtils;
 import com.android.settings.R;
+import com.android.settings.RebootDialog;
 import com.android.settings.password.ChooseLockSettingsHelper;
 import com.android.settings.vpn2.VpnUtils;
 
@@ -130,10 +131,10 @@ public final class CredentialStorage extends FragmentActivity {
         if (uid != KeyStore.UID_SELF && !UserHandle.isSameUser(uid, Process.myUid())) {
             final int dstUserId = UserHandle.getUserId(uid);
 
-            // Restrict install target to the wifi uid.
-            if (uid != Process.WIFI_UID) {
+            // Restrict install target to the known uid.
+            if (uid != Process.WIFI_UID && uid != Process.FSVERITY_CERT_UID) {
                 Log.e(TAG, "Failed to install credentials as uid " + uid + ": cross-user installs"
-                        + " may only target wifi uids");
+                        + " may only target known uids");
                 return true;
             }
 
@@ -309,6 +310,16 @@ public final class CredentialStorage extends FragmentActivity {
         Log.i(TAG, String.format("Successfully installed alias %s to uid %d.",
                 alias, uid));
 
+        if (uid == Process.FSVERITY_CERT_UID) {
+            new RebootDialog(
+                    this,
+                    R.string.app_src_cert_reboot_dialog_install_title,
+                    R.string.app_src_cert_reboot_dialog_install_message,
+                    "Reboot to make new fsverity cert effective").show();
+            setResult(RESULT_OK);
+            return;
+        }
+
         // Send the broadcast.
         final Intent broadcast = new Intent(KeyChain.ACTION_KEYCHAIN_CHANGED);
         sendBroadcast(broadcast);

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

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2019 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.os.SystemProperties;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.settings.core.BasePreferenceController;
+
+class InstallAppSourceCertificatePreferenceController extends
+        BasePreferenceController {
+
+    private static final String APK_VERITY_PROPERTY = "ro.apk_verity.mode";
+    private static final int APK_VERITY_MODE_ENABLED = 2;
+
+    InstallAppSourceCertificatePreferenceController(Context context, String key) {
+        super(context, key);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return isApkVerityEnabled() ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+    }
+
+    @VisibleForTesting
+    static boolean isApkVerityEnabled() {
+        // TODO(victorhsieh): replace this with a new API in PackageManager once it is landed.
+        return SystemProperties.getInt(APK_VERITY_PROPERTY, 0) == APK_VERITY_MODE_ENABLED;
+    }
+}

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

@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2019 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.annotation.Nullable;
+import android.app.Activity;
+import android.content.Intent;
+import android.os.Bundle;
+import android.security.Credentials;
+import android.view.View;
+import android.widget.Toast;
+
+import com.android.settings.R;
+
+import com.google.android.setupcompat.template.FooterBarMixin;
+import com.google.android.setupcompat.template.FooterButton;
+import com.google.android.setupdesign.GlifLayout;
+
+/**
+ * Creates a warning dialog explaining the consequences of installing a certificate
+ * This is displayed before an app source certificate can be installed from Settings.
+ */
+public class InstallAppSourceCertificateWarning extends Activity {
+    @Override
+    public void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        setContentView(R.layout.app_source_certificate_warning_dialog);
+        final GlifLayout layout = findViewById(R.id.setup_wizard_layout);
+
+        final FooterBarMixin mixin = layout.getMixin(FooterBarMixin.class);
+        mixin.setSecondaryButton(
+                new FooterButton.Builder(this)
+                        .setText(R.string.certificate_warning_install_anyway)
+                        .setListener(installCertificate())
+                        .setButtonType(FooterButton.ButtonType.OTHER)
+                        .setTheme(R.style.SudGlifButton_Secondary)
+                        .build()
+        );
+
+        mixin.setPrimaryButton(
+                new FooterButton.Builder(this)
+                        .setText(R.string.certificate_warning_dont_install)
+                        .setListener(returnToInstallCertificateFromStorage())
+                        .setButtonType(FooterButton.ButtonType.NEXT)
+                        .setTheme(R.style.SudGlifButton_Primary)
+                        .build()
+        );
+    }
+
+    private View.OnClickListener installCertificate() {
+        return v -> {
+            final Intent intent = new Intent();
+            intent.setAction(Credentials.INSTALL_ACTION);
+            intent.putExtra(Credentials.EXTRA_CERTIFICATE_USAGE,
+                    Credentials.CERTIFICATE_USAGE_APP_SOURCE);
+            startActivity(intent);
+            finish();
+        };
+    }
+
+    private View.OnClickListener returnToInstallCertificateFromStorage() {
+        return v -> {
+            Toast.makeText(this, R.string.cert_not_installed, Toast.LENGTH_SHORT).show();
+            finish();
+        };
+    }
+
+}

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

@@ -46,7 +46,7 @@ public class InstallCaCertificateWarning extends Activity {
         final FooterBarMixin mixin = layout.getMixin(FooterBarMixin.class);
         mixin.setSecondaryButton(
                 new FooterButton.Builder(this)
-                        .setText(R.string.ca_certificate_warning_install_anyway)
+                        .setText(R.string.certificate_warning_install_anyway)
                         .setListener(installCaCertificate())
                         .setButtonType(FooterButton.ButtonType.OTHER)
                         .setTheme(R.style.SudGlifButton_Secondary)
@@ -55,7 +55,7 @@ public class InstallCaCertificateWarning extends Activity {
 
         mixin.setPrimaryButton(
                 new FooterButton.Builder(this)
-                        .setText(R.string.ca_certificate_warning_dont_install)
+                        .setText(R.string.certificate_warning_dont_install)
                         .setListener(returnToInstallCertificateFromStorage())
                         .setButtonType(FooterButton.ButtonType.NEXT)
                         .setTheme(R.style.SudGlifButton_Primary)

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

@@ -60,6 +60,7 @@ public class InstallCertificateFromStorage extends DashboardFragment {
 
     private static List<AbstractPreferenceController> buildPreferenceControllers(Context context,
             Lifecycle lifecycle) {
+        // TODO(eranm,victorhsieh): use "settings:controller" in xml and remove the following.
         final List<AbstractPreferenceController> controllers = new ArrayList<>();
         controllers.add(new InstallCaCertificatePreferenceController(context));
         controllers.add(new InstallUserCertificatePreferenceController(context));