Migrate CryptoSettings (53b1c12e) · Commits · e / os / android_frameworks_base

packages/BackupEncryption/src/com/android/server/backup/encryption/CryptoSettings.java

0 → 100644

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		/*
		* 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.server.backup.encryption;

		import static com.android.internal.util.Preconditions.checkNotNull;
		import static com.android.internal.util.Preconditions.checkState;

		import android.content.Context;
		import android.content.SharedPreferences;
		import android.content.SharedPreferences.Editor;
		import android.security.keystore.recovery.InternalRecoveryServiceException;
		import android.security.keystore.recovery.RecoveryController;
		import android.util.Slog;

		import com.android.internal.annotations.VisibleForTesting;

		import java.security.KeyStoreException;
		import java.util.Optional;

		/**
		* State about encrypted backups that needs to be remembered.
		*/
		public class CryptoSettings {

		private static final String TAG = "CryptoSettings";

		private static final String SHARED_PREFERENCES_NAME = "crypto_settings";

		private static final String KEY_IS_INITIALIZED = "isInitialized";
		private static final String KEY_ACTIVE_SECONDARY_ALIAS = "activeSecondary";
		private static final String KEY_NEXT_SECONDARY_ALIAS = "nextSecondary";
		private static final String SECONDARY_KEY_LAST_ROTATED_AT = "secondaryKeyLastRotatedAt";
		private static final String[] SETTINGS_FOR_BACKUP = {
		KEY_IS_INITIALIZED,
		KEY_ACTIVE_SECONDARY_ALIAS,
		KEY_NEXT_SECONDARY_ALIAS,
		SECONDARY_KEY_LAST_ROTATED_AT
		};

		private static final String KEY_ANCESTRAL_SECONDARY_KEY_VERSION =
		"ancestral_secondary_key_version";

		private final SharedPreferences mSharedPreferences;
		private final Context mContext;

		/**
		* A new instance.
		*
		* @param context For looking up the {@link SharedPreferences}, for storing state.
		* @return The instance.
		*/
		public static CryptoSettings getInstance(Context context) {
		// We need single process mode because CryptoSettings may be used from several processes
		// simultaneously.
		SharedPreferences sharedPreferences =
		context.getSharedPreferences(SHARED_PREFERENCES_NAME, Context.MODE_PRIVATE);
		return new CryptoSettings(sharedPreferences, context);
		}

		/**
		* A new instance using {@link SharedPreferences} in the default mode.
		*
		* <p>This will not work across multiple processes but will work in tests.
		*/
		@VisibleForTesting
		public static CryptoSettings getInstanceForTesting(Context context) {
		SharedPreferences sharedPreferences =
		context.getSharedPreferences(SHARED_PREFERENCES_NAME, Context.MODE_PRIVATE);
		return new CryptoSettings(sharedPreferences, context);
		}

		private CryptoSettings(SharedPreferences sharedPreferences, Context context) {
		mSharedPreferences = checkNotNull(sharedPreferences);
		mContext = checkNotNull(context);
		}

		/**
		* The alias of the current active secondary key. This should be used to retrieve the key from
		* AndroidKeyStore.
		*/
		public Optional<String> getActiveSecondaryKeyAlias() {
		return getStringInSharedPrefs(KEY_ACTIVE_SECONDARY_ALIAS);
		}

		/**
		* The alias of the secondary key to which the client is rotating. The rotation is not
		* immediate, which is why this setting is needed. Once the next key is created, it can take up
		* to 72 hours potentially (or longer if the user has no network) for the next key to be synced
		* with the keystore. Only after that has happened does the client attempt to re-wrap all
		* tertiary keys and commit the rotation.
		*/
		public Optional<String> getNextSecondaryKeyAlias() {
		return getStringInSharedPrefs(KEY_NEXT_SECONDARY_ALIAS);
		}

		/**
		* If the settings have been initialized.
		*/
		public boolean getIsInitialized() {
		return mSharedPreferences.getBoolean(KEY_IS_INITIALIZED, false);
		}

		/**
		* Sets the alias of the currently active secondary key.
		*
		* @param activeAlias The alias, as in AndroidKeyStore.
		* @throws IllegalArgumentException if the alias is not in the user's keystore.
		*/
		public void setActiveSecondaryKeyAlias(String activeAlias) throws IllegalArgumentException {
		assertIsValidAlias(activeAlias);
		mSharedPreferences.edit().putString(KEY_ACTIVE_SECONDARY_ALIAS, activeAlias).apply();
		}

		/**
		* Sets the alias of the secondary key to which the client is rotating.
		*
		* @param nextAlias The alias, as in AndroidKeyStore.
		* @throws KeyStoreException if unable to check whether alias is valid in the keystore.
		* @throws IllegalArgumentException if the alias is not in the user's keystore.
		*/
		public void setNextSecondaryAlias(String nextAlias) throws IllegalArgumentException {
		assertIsValidAlias(nextAlias);
		mSharedPreferences.edit().putString(KEY_NEXT_SECONDARY_ALIAS, nextAlias).apply();
		}

		/**
		* Unsets the alias of the key to which the client is rotating. This is generally performed once
		* a rotation is complete.
		*/
		public void removeNextSecondaryKeyAlias() {
		mSharedPreferences.edit().remove(KEY_NEXT_SECONDARY_ALIAS).apply();
		}

		/**
		* Sets the timestamp of when the secondary key was last rotated.
		*
		* @param timestamp The timestamp to set.
		*/
		public void setSecondaryLastRotated(long timestamp) {
		mSharedPreferences.edit().putLong(SECONDARY_KEY_LAST_ROTATED_AT, timestamp).apply();
		}

		/**
		* Returns a timestamp of when the secondary key was last rotated.
		*
		* @return The timestamp.
		*/
		public Optional<Long> getSecondaryLastRotated() {
		if (!mSharedPreferences.contains(SECONDARY_KEY_LAST_ROTATED_AT)) {
		return Optional.empty();
		}
		return Optional.of(mSharedPreferences.getLong(SECONDARY_KEY_LAST_ROTATED_AT, -1));
		}

		/**
		* Sets the settings to have been initialized. (Otherwise loading should try to initialize
		* again.)
		*/
		private void setIsInitialized() {
		mSharedPreferences.edit().putBoolean(KEY_IS_INITIALIZED, true).apply();
		}

		/**
		* Initializes with the given key alias.
		*
		* @param alias The secondary key alias to be set as active.
		* @throws IllegalArgumentException if the alias does not reference a valid key.
		* @throws IllegalStateException if attempting to initialize an already initialized settings.
		*/
		public void initializeWithKeyAlias(String alias) throws IllegalArgumentException {
		checkState(
		!getIsInitialized(), "Attempting to initialize an already initialized settings.");
		setActiveSecondaryKeyAlias(alias);
		setIsInitialized();
		}

		/** Returns the secondary key version of the encrypted backup set to restore from (if set). */
		public Optional<String> getAncestralSecondaryKeyVersion() {
		return Optional.ofNullable(
		mSharedPreferences.getString(KEY_ANCESTRAL_SECONDARY_KEY_VERSION, null));
		}

		/** Sets the secondary key version of the encrypted backup set to restore from. */
		public void setAncestralSecondaryKeyVersion(String ancestralSecondaryKeyVersion) {
		mSharedPreferences
		.edit()
		.putString(KEY_ANCESTRAL_SECONDARY_KEY_VERSION, ancestralSecondaryKeyVersion)
		.apply();
		}

		/** Deletes all crypto settings related to backup (as opposed to restore). */
		public void clearAllSettingsForBackup() {
		Editor sharedPrefsEditor = mSharedPreferences.edit();
		for (String backupSettingKey : SETTINGS_FOR_BACKUP) {
		sharedPrefsEditor.remove(backupSettingKey);
		}
		sharedPrefsEditor.apply();

		Slog.d(TAG, "Cleared crypto settings for backup");
		}

		/**
		* Throws {@link IllegalArgumentException} if the alias does not refer to a key that is in
		* the {@link RecoveryController}.
		*/
		private void assertIsValidAlias(String alias) throws IllegalArgumentException {
		try {
		if (!RecoveryController.getInstance(mContext).getAliases().contains(alias)) {
		throw new IllegalArgumentException(alias + " is not in RecoveryController");
		}
		} catch (InternalRecoveryServiceException e) {
		throw new IllegalArgumentException("Problem accessing recovery service", e);
		}
		}

		private Optional<String> getStringInSharedPrefs(String key) {
		return Optional.ofNullable(mSharedPreferences.getString(key, null));
		}
		}

packages/BackupEncryption/test/robolectric/Android.bp

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		@@ -25,6 +25,11 @@ android_robolectric_test {
		"testng",
		"truth-prebuilt",
		],
		static_libs: [
		"androidx.test.core",
		"androidx.test.runner",
		"androidx.test.rules",
		],
		instrumentation_for: "BackupEncryption",
		}

packages/BackupEncryption/test/robolectric/src/com/android/server/backup/encryption/CryptoSettingsTest.java

0 → 100644

+212 −0

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		/*
		* 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.server.backup.encryption;

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

		import static org.testng.Assert.assertThrows;

		import android.app.Application;
		import android.security.keystore.recovery.RecoveryController;

		import androidx.test.core.app.ApplicationProvider;

		import com.android.server.testing.shadows.ShadowRecoveryController;

		import org.junit.Before;
		import org.junit.Test;
		import org.junit.runner.RunWith;
		import org.robolectric.RobolectricTestRunner;
		import org.robolectric.annotation.Config;

		import java.util.Optional;

		@RunWith(RobolectricTestRunner.class)
		@Config(shadows = ShadowRecoveryController.class)
		public class CryptoSettingsTest {

		private static final String TEST_KEY_ALIAS =
		"com.android.server.backup.encryption/keystore/08120c326b928ff34c73b9c58581da63";

		private CryptoSettings mCryptoSettings;
		private Application mApplication;

		@Before
		public void setUp() {
		ShadowRecoveryController.reset();

		mApplication = ApplicationProvider.getApplicationContext();
		mCryptoSettings = CryptoSettings.getInstanceForTesting(mApplication);
		}

		@Test
		public void getActiveSecondaryAlias_isInitiallyAbsent() {
		assertThat(mCryptoSettings.getActiveSecondaryKeyAlias().isPresent()).isFalse();
		}

		@Test
		public void getActiveSecondaryAlias_returnsAliasIfKeyIsInRecoveryController() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);
		mCryptoSettings.setActiveSecondaryKeyAlias(TEST_KEY_ALIAS);
		assertThat(mCryptoSettings.getActiveSecondaryKeyAlias().get()).isEqualTo(TEST_KEY_ALIAS);
		}

		@Test
		public void getNextSecondaryAlias_isInitiallyAbsent() {
		assertThat(mCryptoSettings.getNextSecondaryKeyAlias().isPresent()).isFalse();
		}

		@Test
		public void getNextSecondaryAlias_returnsAliasIfKeyIsInRecoveryController() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);
		mCryptoSettings.setNextSecondaryAlias(TEST_KEY_ALIAS);
		assertThat(mCryptoSettings.getNextSecondaryKeyAlias().get()).isEqualTo(TEST_KEY_ALIAS);
		}

		@Test
		public void isInitialized_isInitiallyFalse() {
		assertThat(mCryptoSettings.getIsInitialized()).isFalse();
		}

		@Test
		public void setActiveSecondaryAlias_throwsIfKeyIsNotInRecoveryController() {
		assertThrows(
		IllegalArgumentException.class,
		() -> mCryptoSettings.setActiveSecondaryKeyAlias(TEST_KEY_ALIAS));
		}

		@Test
		public void setNextSecondaryAlias_inRecoveryController_setsAlias() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);

		mCryptoSettings.setNextSecondaryAlias(TEST_KEY_ALIAS);

		assertThat(mCryptoSettings.getNextSecondaryKeyAlias().get()).isEqualTo(TEST_KEY_ALIAS);
		}

		@Test
		public void setNextSecondaryAlias_throwsIfKeyIsNotInRecoveryController() {
		assertThrows(
		IllegalArgumentException.class,
		() -> mCryptoSettings.setNextSecondaryAlias(TEST_KEY_ALIAS));
		}

		@Test
		public void removeNextSecondaryAlias_removesIt() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);
		mCryptoSettings.setNextSecondaryAlias(TEST_KEY_ALIAS);

		mCryptoSettings.removeNextSecondaryKeyAlias();

		assertThat(mCryptoSettings.getNextSecondaryKeyAlias().isPresent()).isFalse();
		}

		@Test
		public void initializeWithKeyAlias_setsAsInitialized() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);
		mCryptoSettings.initializeWithKeyAlias(TEST_KEY_ALIAS);
		assertThat(mCryptoSettings.getIsInitialized()).isTrue();
		}

		@Test
		public void initializeWithKeyAlias_setsActiveAlias() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);
		mCryptoSettings.initializeWithKeyAlias(TEST_KEY_ALIAS);
		assertThat(mCryptoSettings.getActiveSecondaryKeyAlias().get()).isEqualTo(TEST_KEY_ALIAS);
		}

		@Test
		public void initializeWithKeyAlias_throwsIfKeyIsNotInRecoveryController() {
		assertThrows(
		IllegalArgumentException.class,
		() -> mCryptoSettings.initializeWithKeyAlias(TEST_KEY_ALIAS));
		}

		@Test
		public void initializeWithKeyAlias_throwsIfAlreadyInitialized() throws Exception {
		setAliasIsInRecoveryController(TEST_KEY_ALIAS);
		mCryptoSettings.initializeWithKeyAlias(TEST_KEY_ALIAS);

		assertThrows(
		IllegalStateException.class,
		() -> mCryptoSettings.initializeWithKeyAlias(TEST_KEY_ALIAS));
		}

		@Test
		public void getSecondaryLastRotated_returnsEmptyInitially() {
		assertThat(mCryptoSettings.getSecondaryLastRotated()).isEqualTo(Optional.empty());
		}

		@Test
		public void getSecondaryLastRotated_returnsTimestampAfterItIsSet() {
		long timestamp = 1000001;

		mCryptoSettings.setSecondaryLastRotated(timestamp);

		assertThat(mCryptoSettings.getSecondaryLastRotated().get()).isEqualTo(timestamp);
		}

		@Test
		public void getAncestralSecondaryKeyVersion_notSet_returnsOptionalAbsent() {
		assertThat(mCryptoSettings.getAncestralSecondaryKeyVersion().isPresent()).isFalse();
		}

		@Test
		public void getAncestralSecondaryKeyVersion_isSet_returnsSetValue() {
		String secondaryKeyVersion = "some_secondary_key";
		mCryptoSettings.setAncestralSecondaryKeyVersion(secondaryKeyVersion);

		assertThat(mCryptoSettings.getAncestralSecondaryKeyVersion().get())
		.isEqualTo(secondaryKeyVersion);
		}

		@Test
		public void getAncestralSecondaryKeyVersion_isSetMultipleTimes_returnsLastSetValue() {
		String secondaryKeyVersion1 = "some_secondary_key";
		String secondaryKeyVersion2 = "another_secondary_key";
		mCryptoSettings.setAncestralSecondaryKeyVersion(secondaryKeyVersion1);
		mCryptoSettings.setAncestralSecondaryKeyVersion(secondaryKeyVersion2);

		assertThat(mCryptoSettings.getAncestralSecondaryKeyVersion().get())
		.isEqualTo(secondaryKeyVersion2);
		}

		@Test
		public void clearAllSettingsForBackup_clearsStateForBackup() throws Exception {
		String key1 = "key1";
		String key2 = "key2";
		String ancestralKey = "ancestral_key";
		setAliasIsInRecoveryController(key1);
		setAliasIsInRecoveryController(key2);
		mCryptoSettings.setActiveSecondaryKeyAlias(key1);
		mCryptoSettings.setNextSecondaryAlias(key2);
		mCryptoSettings.setSecondaryLastRotated(100001);
		mCryptoSettings.setAncestralSecondaryKeyVersion(ancestralKey);

		mCryptoSettings.clearAllSettingsForBackup();

		assertThat(mCryptoSettings.getActiveSecondaryKeyAlias().isPresent()).isFalse();
		assertThat(mCryptoSettings.getNextSecondaryKeyAlias().isPresent()).isFalse();
		assertThat(mCryptoSettings.getSecondaryLastRotated().isPresent()).isFalse();
		assertThat(mCryptoSettings.getAncestralSecondaryKeyVersion().get()).isEqualTo(ancestralKey);
		}

		private void setAliasIsInRecoveryController(String alias) throws Exception {
		RecoveryController recoveryController = RecoveryController.getInstance(mApplication);
		recoveryController.generateKey(alias);
		}
		}