diff options
Diffstat (limited to 'service')
5 files changed, 238 insertions, 162 deletions
diff --git a/service/java/com/android/server/wifi/WifiConfigManager.java b/service/java/com/android/server/wifi/WifiConfigManager.java index 8da2d2cb4..b21893404 100644 --- a/service/java/com/android/server/wifi/WifiConfigManager.java +++ b/service/java/com/android/server/wifi/WifiConfigManager.java @@ -3094,7 +3094,7 @@ public class WifiConfigManager { if (mDeferredUserUnlockRead) { Log.i(TAG, "Handling user unlock before loading from store."); List<WifiConfigStore.StoreFile> userStoreFiles = - WifiConfigStore.createUserFiles(mCurrentUserId, UserManager.get(mContext)); + WifiConfigStore.createUserFiles(mCurrentUserId); if (userStoreFiles == null) { Log.wtf(TAG, "Failed to create user store files"); return false; @@ -3104,7 +3104,7 @@ public class WifiConfigManager { } try { mWifiConfigStore.read(); - } catch (IOException e) { + } catch (IOException | IllegalStateException e) { Log.wtf(TAG, "Reading from new store failed. All saved networks are lost!", e); return false; } catch (XmlPullParserException e) { @@ -3133,13 +3133,13 @@ public class WifiConfigManager { private boolean loadFromUserStoreAfterUnlockOrSwitch(int userId) { try { List<WifiConfigStore.StoreFile> userStoreFiles = - WifiConfigStore.createUserFiles(userId, UserManager.get(mContext)); + WifiConfigStore.createUserFiles(userId); if (userStoreFiles == null) { Log.e(TAG, "Failed to create user store files"); return false; } mWifiConfigStore.switchUserStoresAndRead(userStoreFiles); - } catch (IOException e) { + } catch (IOException | IllegalStateException e) { Log.wtf(TAG, "Reading from new store failed. All saved private networks are lost!", e); return false; } catch (XmlPullParserException e) { @@ -3214,7 +3214,7 @@ public class WifiConfigManager { try { mWifiConfigStore.write(forceWrite); - } catch (IOException e) { + } catch (IOException | IllegalStateException e) { Log.wtf(TAG, "Writing to store failed. Saved networks maybe lost!", e); return false; } catch (XmlPullParserException e) { diff --git a/service/java/com/android/server/wifi/WifiConfigStore.java b/service/java/com/android/server/wifi/WifiConfigStore.java index 6989e728f..e189d00e1 100644 --- a/service/java/com/android/server/wifi/WifiConfigStore.java +++ b/service/java/com/android/server/wifi/WifiConfigStore.java @@ -27,7 +27,6 @@ import android.os.Environment; import android.os.FileUtils; import android.os.Handler; import android.os.Looper; -import android.os.UserManager; import android.util.Log; import android.util.SparseArray; import android.util.Xml; @@ -37,6 +36,7 @@ import com.android.internal.os.AtomicFile; import com.android.internal.util.FastXmlSerializer; import com.android.internal.util.Preconditions; import com.android.server.wifi.util.DataIntegrityChecker; +import com.android.server.wifi.util.EncryptedData; import com.android.server.wifi.util.XmlUtil; import org.xmlpull.v1.XmlPullParser; @@ -53,8 +53,8 @@ import java.io.IOException; import java.io.PrintWriter; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; +import java.nio.ByteBuffer; import java.nio.charset.StandardCharsets; -import java.security.DigestException; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; @@ -100,15 +100,23 @@ public class WifiConfigStore { private static final String XML_TAG_DOCUMENT_HEADER = "WifiConfigStoreData"; private static final String XML_TAG_VERSION = "Version"; + private static final String XML_TAG_HEADER_INTEGRITY = "Integrity"; + private static final String XML_TAG_INTEGRITY_ENCRYPTED_DATA = "EncryptedData"; + private static final String XML_TAG_INTEGRITY_IV = "IV"; /** * Current config store data version. This will be incremented for any additions. */ - private static final int CURRENT_CONFIG_STORE_DATA_VERSION = 1; + private static final int CURRENT_CONFIG_STORE_DATA_VERSION = 2; /** This list of older versions will be used to restore data from older config store. */ /** * First version of the config store data format. */ private static final int INITIAL_CONFIG_STORE_DATA_VERSION = 1; + /** + * Second version of the config store data format, introduced: + * - Integrity info. + */ + private static final int INTEGRITY_CONFIG_STORE_DATA_VERSION = 2; /** * Alarm tag to use for starting alarms for buffering file writes. @@ -150,6 +158,11 @@ public class WifiConfigStore { put(STORE_FILE_USER_NETWORK_SUGGESTIONS, STORE_FILE_NAME_USER_NETWORK_SUGGESTIONS); }}; + @VisibleForTesting + public static final EncryptedData ZEROED_ENCRYPTED_DATA = + new EncryptedData( + new byte[EncryptedData.ENCRYPTED_DATA_LENGTH], + new byte[EncryptedData.IV_LENGTH]); /** * Handler instance to post alarm timeouts to */ @@ -209,7 +222,7 @@ public class WifiConfigStore { * @param clock clock instance to retrieve timestamps for alarms. * @param wifiMetrics Metrics instance. * @param sharedStore StoreFile instance pointing to the shared store file. This should - * be retrieved using {@link #createSharedFile(UserManager)} method. + * be retrieved using {@link #createSharedFile()} method. */ public WifiConfigStore(Context context, Looper looper, Clock clock, WifiMetrics wifiMetrics, StoreFile sharedStore) { @@ -230,8 +243,7 @@ public class WifiConfigStore { /** * Set the user store files. * (Useful for mocking in unit tests). - * @param userStores List of {@link StoreFile} created using {@link #createUserFiles(int, - * UserManager)}. + * @param userStores List of {@link StoreFile} created using {@link #createUserFiles(int)}. */ public void setUserStores(@NonNull List<StoreFile> userStores) { Preconditions.checkNotNull(userStores); @@ -268,11 +280,9 @@ public class WifiConfigStore { * @param storeBaseDir Base directory under which the store file is to be stored. The store file * will be at <storeBaseDir>/wifi/WifiConfigStore.xml. * @param fileId Identifier for the file. See {@link StoreFileId}. - * @param userManager Instance of UserManager to check if the device is in single user mode. * @return new instance of the store file or null if the directory cannot be created. */ - private static @Nullable StoreFile createFile(File storeBaseDir, @StoreFileId int fileId, - UserManager userManager) { + private static @Nullable StoreFile createFile(File storeBaseDir, @StoreFileId int fileId) { File storeDir = new File(storeBaseDir, STORE_DIRECTORY_NAME); if (!storeDir.exists()) { if (!storeDir.mkdir()) { @@ -281,23 +291,17 @@ public class WifiConfigStore { } } File file = new File(storeDir, STORE_ID_TO_FILE_NAME.get(fileId)); - DataIntegrityChecker dataIntegrityChecker = null; - // Turn on integrity checking only for single user mode devices. - if (userManager.hasUserRestriction(UserManager.DISALLOW_ADD_USER)) { - dataIntegrityChecker = new DataIntegrityChecker(file.getAbsolutePath()); - } + DataIntegrityChecker dataIntegrityChecker = new DataIntegrityChecker(file.getName()); return new StoreFile(file, fileId, dataIntegrityChecker); } /** * Create a new instance of the shared store file. * - * @param userManager Instance of UserManager to check if the device is in single user mode. * @return new instance of the store file or null if the directory cannot be created. */ - public static @Nullable StoreFile createSharedFile(UserManager userManager) { - return createFile( - Environment.getDataMiscDirectory(), STORE_FILE_SHARED_GENERAL, userManager); + public static @Nullable StoreFile createSharedFile() { + return createFile(Environment.getDataMiscDirectory(), STORE_FILE_SHARED_GENERAL); } /** @@ -305,16 +309,14 @@ public class WifiConfigStore { * The user store file is inside the user's encrypted data directory. * * @param userId userId corresponding to the currently logged-in user. - * @param userManager Instance of UserManager to check if the device is in single user mode. * @return List of new instances of the store files created or null if the directory cannot be * created. */ - public static @Nullable List<StoreFile> createUserFiles(int userId, UserManager userManager) { + public static @Nullable List<StoreFile> createUserFiles(int userId) { List<StoreFile> storeFiles = new ArrayList<>(); for (int fileId : Arrays.asList( STORE_FILE_USER_GENERAL, STORE_FILE_USER_NETWORK_SUGGESTIONS)) { - StoreFile storeFile = - createFile(Environment.getDataMiscCeDirectory(userId), fileId, userManager); + StoreFile storeFile = createFile(Environment.getDataMiscCeDirectory(userId), fileId); if (storeFile == null) { return null; } @@ -409,6 +411,9 @@ public class WifiConfigStore { * Serialize all the data from all the {@link StoreData} clients registered for the provided * {@link StoreFile}. * + * This method also computes the integrity of the data being written and serializes the computed + * {@link EncryptedData} to the output. + * * @param storeFile StoreFile that we want to write to. * @return byte[] of serialized bytes * @throws XmlPullParserException @@ -422,8 +427,9 @@ public class WifiConfigStore { final ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); out.setOutput(outputStream, StandardCharsets.UTF_8.name()); - XmlUtil.writeDocumentStart(out, XML_TAG_DOCUMENT_HEADER); - XmlUtil.writeNextValue(out, XML_TAG_VERSION, CURRENT_CONFIG_STORE_DATA_VERSION); + // To compute integrity, write zeroes in the integrity fields. Once the integrity is + // computed, go back and modfiy the XML fields in place with the computed values. + writeDocumentMetadata(out, ZEROED_ENCRYPTED_DATA); for (StoreData storeData : storeDataList) { String tag = storeData.getName(); XmlUtil.writeNextSectionStart(out, tag); @@ -432,7 +438,77 @@ public class WifiConfigStore { } XmlUtil.writeDocumentEnd(out, XML_TAG_DOCUMENT_HEADER); - return outputStream.toByteArray(); + byte[] outBytes = outputStream.toByteArray(); + EncryptedData encryptedData = storeFile.computeIntegrity(outBytes); + if (encryptedData == null) { + // should never happen, this is a fatal failure. Abort file write. + Log.wtf(TAG, "Failed to compute integrity, failing write"); + return null; + } + return rewriteDocumentMetadataRawBytes(outBytes, encryptedData); + } + + /** + * Helper method to write the metadata at the start of every config store file. + * The metadata consists of: + * a) Version + * b) Integrity data computed on the data contents. + */ + private void writeDocumentMetadata(XmlSerializer out, EncryptedData encryptedData) + throws XmlPullParserException, IOException { + // First XML header. + XmlUtil.writeDocumentStart(out, XML_TAG_DOCUMENT_HEADER); + // Next version. + XmlUtil.writeNextValue(out, XML_TAG_VERSION, CURRENT_CONFIG_STORE_DATA_VERSION); + + // Next integrity data. + XmlUtil.writeNextSectionStart(out, XML_TAG_HEADER_INTEGRITY); + XmlUtil.writeNextValue(out, XML_TAG_INTEGRITY_ENCRYPTED_DATA, + encryptedData.getEncryptedData()); + XmlUtil.writeNextValue(out, XML_TAG_INTEGRITY_IV, encryptedData.getIv()); + XmlUtil.writeNextSectionEnd(out, XML_TAG_HEADER_INTEGRITY); + } + + /** + * Helper method to generate the raw bytes containing the the metadata at the start of every + * config store file. + * + * NOTE: This does not create a fully formed XML document (the start tag is not closed for + * example). This only creates the top portion of the XML which contains the modified + * integrity data & version along with the XML prolog (metadata): + * <?xml version='1.0' encoding='utf-8' standalone='yes' ?> + * <WifiConfigStoreData> + * <int name="Version" value="2" /> + * <Integrity> + * <byte-array name="EncryptedData" num="48">!EncryptedData!</byte-array> + * <byte-array name="IV" num="12">!IV!</byte-array> + * </Integrity> + */ + private byte[] generateDocumentMetadataRawBytes(EncryptedData encryptedData) + throws XmlPullParserException, IOException { + final XmlSerializer outXml = new FastXmlSerializer(); + final ByteArrayOutputStream outStream = new ByteArrayOutputStream(); + outXml.setOutput(outStream, StandardCharsets.UTF_8.name()); + writeDocumentMetadata(outXml, encryptedData); + outXml.endDocument(); + return outStream.toByteArray(); + } + + /** + * Helper method to rewrite the existing document metadata in the incoming raw bytes in + * |inBytes| with the new document metadata created with the provided |encryptedData|. + * + * NOTE: This assumes that the metadata in existing XML inside |inBytes| aligns exactly + * with the new metadata created. So, a simple in place rewrite of the first few bytes ( + * corresponding to metadata section of the document) from |inBytes| will preserve the overall + * document structure. + */ + private byte[] rewriteDocumentMetadataRawBytes(byte[] inBytes, EncryptedData encryptedData) + throws XmlPullParserException, IOException { + byte[] replaceMetadataBytes = generateDocumentMetadataRawBytes(encryptedData); + ByteBuffer outByteBuffer = ByteBuffer.wrap(inBytes); + outByteBuffer.put(replaceMetadataBytes); + return outByteBuffer.array(); } /** @@ -516,8 +592,7 @@ public class WifiConfigStore { * Handles a user switch. This method changes the user specific store files and reads from the * new user's store files. * - * @param userStores List of {@link StoreFile} created using {@link #createUserFiles(int, - * UserManager)}. + * @param userStores List of {@link StoreFile} created using {@link #createUserFiles(int)}. */ public void switchUserStoresAndRead(@NonNull List<StoreFile> userStores) throws XmlPullParserException, IOException { @@ -564,6 +639,10 @@ public class WifiConfigStore { /** * Deserialize data from a {@link StoreFile} for all {@link StoreData} instances registered. * + * This method also computes the integrity of the incoming |dataBytes| and compare with + * {@link EncryptedData} parsed from |dataBytes|. If the integrity check fails, the data + * is discarded. + * * @param dataBytes The data to parse * @param storeFile StoreFile that we read from. Will be used to retrieve the list of clients * who have data to deserialize from this file. @@ -584,7 +663,24 @@ public class WifiConfigStore { // Start parsing the XML stream. int rootTagDepth = in.getDepth() + 1; - parseDocumentStartAndVersionFromXml(in); + XmlUtil.gotoDocumentStart(in, XML_TAG_DOCUMENT_HEADER); + + int version = parseVersionFromXml(in); + // Version 2 onwards contains integrity data, so check the integrity of the file. + if (version >= INTEGRITY_CONFIG_STORE_DATA_VERSION) { + EncryptedData integrityData = parseIntegrityDataFromXml(in, rootTagDepth); + // To compute integrity, write zeroes in the integrity fields. + dataBytes = rewriteDocumentMetadataRawBytes(dataBytes, ZEROED_ENCRYPTED_DATA); + if (!storeFile.checkIntegrity(dataBytes, integrityData)) { + Log.wtf(TAG, "Integrity mismatch, discarding data from " + storeFile.mFileName); + return; + } + } else { + // When integrity checking is introduced. The existing data will have no related + // integrity file for validation. Thus, we will assume the existing data is correct. + // Integrity will be computed for the next write. + Log.d(TAG, "No integrity data to check; thus vacously true"); + } String[] headerName = new String[1]; Set<StoreData> storeDatasInvoked = new HashSet<>(); @@ -610,15 +706,14 @@ public class WifiConfigStore { } /** - * Parse the document start and version from the XML stream. + * Parse the version from the XML stream. * This is used for both the shared and user config store data. * * @param in XmlPullParser instance pointing to the XML stream. * @return version number retrieved from the Xml stream. */ - private static int parseDocumentStartAndVersionFromXml(XmlPullParser in) + private static int parseVersionFromXml(XmlPullParser in) throws XmlPullParserException, IOException { - XmlUtil.gotoDocumentStart(in, XML_TAG_DOCUMENT_HEADER); int version = (int) XmlUtil.readNextValueWithName(in, XML_TAG_VERSION); if (version < INITIAL_CONFIG_STORE_DATA_VERSION || version > CURRENT_CONFIG_STORE_DATA_VERSION) { @@ -628,6 +723,25 @@ public class WifiConfigStore { } /** + * Parse the integrity data structure from the XML stream. + * This is used for both the shared and user config store data. + * + * @param in XmlPullParser instance pointing to the XML stream. + * @param outerTagDepth Outer tag depth. + * @return Instance of {@link EncryptedData} retrieved from the Xml stream. + */ + private static @NonNull EncryptedData parseIntegrityDataFromXml( + XmlPullParser in, int outerTagDepth) + throws XmlPullParserException, IOException { + XmlUtil.gotoNextSectionWithName(in, XML_TAG_HEADER_INTEGRITY, outerTagDepth); + byte[] encryptedData = + (byte[]) XmlUtil.readNextValueWithName(in, XML_TAG_INTEGRITY_ENCRYPTED_DATA); + byte[] iv = + (byte[]) XmlUtil.readNextValueWithName(in, XML_TAG_INTEGRITY_IV); + return new EncryptedData(encryptedData, iv); + } + + /** * Dump the local log buffer and other internal state of WifiConfigManager. */ public void dump(FileDescriptor fd, PrintWriter pw, String[] args) { @@ -668,21 +782,20 @@ public class WifiConfigStore { /** * Store the file name for setting the file permissions/logging purposes. */ - private String mFileName; + private final String mFileName; /** * {@link StoreFileId} Type of store file. */ - private @StoreFileId int mFileId; + private final @StoreFileId int mFileId; /** - * The integrity file storing integrity checking data for the store file. - * Note: This is only turned on for single user devices. + * Integrity checking for the store file. */ - private @Nullable DataIntegrityChecker mDataIntegrityChecker; + private final DataIntegrityChecker mDataIntegrityChecker; public StoreFile(File file, @StoreFileId int fileId, - @Nullable DataIntegrityChecker dataIntegrityChecker) { + @NonNull DataIntegrityChecker dataIntegrityChecker) { mAtomicFile = new AtomicFile(file); - mFileName = mAtomicFile.getBaseFile().getAbsolutePath(); + mFileName = file.getAbsolutePath(); mFileId = fileId; mDataIntegrityChecker = dataIntegrityChecker; } @@ -696,7 +809,6 @@ public class WifiConfigStore { return mAtomicFile.exists(); } - /** * Read the entire raw data from the store file and return in a byte array. * @@ -712,22 +824,6 @@ public class WifiConfigStore { } catch (FileNotFoundException e) { return null; } - if (mDataIntegrityChecker != null) { - // Check that the file has not been altered since last writeBufferedRawData() - try { - if (!mDataIntegrityChecker.isOk(bytes)) { - Log.wtf(TAG, "Data integrity problem with file: " + mFileName); - return null; - } - } catch (DigestException e) { - // When integrity checking is introduced. The existing data will have no - // related integrity file for validation. Thus, we will assume the existing - // data is correct and immediately create the integrity file. - Log.i(TAG, "isOK() had no integrity data to check; thus vacuously " - + "true. Running update now."); - mDataIntegrityChecker.update(bytes); - } - } return bytes; } @@ -763,13 +859,36 @@ public class WifiConfigStore { } throw e; } - if (mDataIntegrityChecker != null) { - // There was a legitimate change and update the integrity checker. - mDataIntegrityChecker.update(mWriteData); - } // Reset the pending write data after write. mWriteData = null; } + + /** + * Compute integrity of |dataWithZeroedIntegrityFields| to be written to the file. + * + * @param dataWithZeroedIntegrityFields raw data to be written to the file with the + * integrity fields zeroed out for integrity + * calculation. + * @return Instance of {@link EncryptedData} holding the encrypted integrity data for the + * raw data to be written to the file. + */ + public EncryptedData computeIntegrity(byte[] dataWithZeroedIntegrityFields) { + return mDataIntegrityChecker.compute(dataWithZeroedIntegrityFields); + } + + /** + * Check integrity of |dataWithZeroedIntegrityFields| read from the file with the integrity + * data parsed from the file. + * @param dataWithZeroedIntegrityFields raw data read from the file with the integrity + * fields zeroed out for integrity calculation. + * @param parsedEncryptedData Instance of {@link EncryptedData} parsed from the integrity + * fields in the raw data. + * @return true if the integrity matches, false otherwise. + */ + public boolean checkIntegrity(byte[] dataWithZeroedIntegrityFields, + EncryptedData parsedEncryptedData) { + return mDataIntegrityChecker.isOk(dataWithZeroedIntegrityFields, parsedEncryptedData); + } } /** diff --git a/service/java/com/android/server/wifi/WifiInjector.java b/service/java/com/android/server/wifi/WifiInjector.java index 762b24b0a..8095bfac6 100644 --- a/service/java/com/android/server/wifi/WifiInjector.java +++ b/service/java/com/android/server/wifi/WifiInjector.java @@ -241,7 +241,7 @@ public class WifiInjector { mWifiKeyStore = new WifiKeyStore(mKeyStore); mWifiConfigStore = new WifiConfigStore( mContext, clientModeImplLooper, mClock, mWifiMetrics, - WifiConfigStore.createSharedFile(UserManager.get(mContext))); + WifiConfigStore.createSharedFile()); SubscriptionManager subscriptionManager = mContext.getSystemService(SubscriptionManager.class); // Config Manager diff --git a/service/java/com/android/server/wifi/util/DataIntegrityChecker.java b/service/java/com/android/server/wifi/util/DataIntegrityChecker.java index 1f3c6b3c1..6f03a4861 100644 --- a/service/java/com/android/server/wifi/util/DataIntegrityChecker.java +++ b/service/java/com/android/server/wifi/util/DataIntegrityChecker.java @@ -23,14 +23,7 @@ import android.security.keystore.KeyProperties; import android.text.TextUtils; import android.util.Log; -import java.io.File; -import java.io.FileInputStream; -import java.io.FileNotFoundException; -import java.io.FileOutputStream; import java.io.IOException; -import java.io.ObjectInputStream; -import java.io.ObjectOutputStream; -import java.security.DigestException; import java.security.InvalidAlgorithmParameterException; import java.security.InvalidKeyException; import java.security.KeyStore; @@ -56,7 +49,6 @@ import javax.crypto.spec.GCMParameterSpec; public class DataIntegrityChecker { private static final String TAG = "DataIntegrityChecker"; - private static final String FILE_SUFFIX = ".encrypted-checksum"; private static final String ALIAS_SUFFIX = ".data-integrity-checker-key"; private static final String CIPHER_ALGORITHM = "AES/GCM/NoPadding"; private static final String DIGEST_ALGORITHM = "SHA-256"; @@ -65,28 +57,29 @@ public class DataIntegrityChecker { /** * When KEYSTORE_FAILURE_RETURN_VALUE is true, all cryptographic operation failures will not - * enforce security and {@link #isOk(byte[])} always return true. + * enforce security and {@link #isOk(byte[], EncryptedData)} always return true. */ private static final boolean KEYSTORE_FAILURE_RETURN_VALUE = true; - private final File mIntegrityFile; + private final String mDataFileName; /** * Construct a new integrity checker to update and check if/when a data file was altered * outside expected conditions. * - * @param integrityFilename The {@link File} path prefix for where the integrity data is stored. - * A file will be created in the name of integrityFile with the suffix - * {@link DataIntegrityChecker#FILE_SUFFIX} We recommend using the same - * path as the file for which integrity is performed on. - * @throws NullPointerException When integrity file is null or the empty string. + * @param dataFileName The full path of the data file for which integrity check is performed. + * @throws NullPointerException When data file is empty string. */ - public DataIntegrityChecker(@NonNull String integrityFilename) { - if (TextUtils.isEmpty(integrityFilename)) { - throw new NullPointerException("integrityFilename must not be null or the empty " + public DataIntegrityChecker(@NonNull String dataFileName) { + if (TextUtils.isEmpty(dataFileName)) { + throw new NullPointerException("dataFileName must not be null or the empty " + "string"); } - mIntegrityFile = new File(integrityFilename + FILE_SUFFIX); + mDataFileName = dataFileName; + } + + private String getKeyAlias() { + return mDataFileName + ALIAS_SUFFIX; } /** @@ -95,66 +88,55 @@ public class DataIntegrityChecker { * Call this method immediately before storing the byte array * * @param data The data desired to ensure integrity + * @return Instance of {@link EncryptedData} containing the encrypted integrity data. */ - public void update(byte[] data) { + public EncryptedData compute(byte[] data) { if (data == null || data.length < 1) { - reportException(new Exception("No data to update"), "No data to update."); - return; + reportException(new Exception("No data to compute"), "No data to compute."); + return null; } byte[] digest = getDigest(data); if (digest == null || digest.length < 1) { - return; + reportException(new Exception("digest null in compute"), + "digest null in compute"); + return null; } - String alias = mIntegrityFile.getName() + ALIAS_SUFFIX; - EncryptedData integrityData = encrypt(digest, alias); - if (integrityData != null) { - writeIntegrityData(integrityData, mIntegrityFile); - } else { - reportException(new Exception("integrityData null upon update"), - "integrityData null upon update"); + EncryptedData integrityData = encrypt(digest, getKeyAlias()); + if (integrityData == null) { + reportException(new Exception("integrityData null in compute"), + "integrityData null in compute"); } + return integrityData; } + /** * Check the integrity of a given byte array * * Call this method immediately before trusting the byte array. This method will return false - * when the byte array was altered since the last {@link #update(byte[])} - * call, when {@link #update(byte[])} has never been called, or if there is - * an underlying issue with the cryptographic functions or the key store. + * when the integrity data calculated on the byte array does not match the encrypted integrity + * data provided to compare or if there is an underlying issue with the cryptographic functions + * or the key store. * - * @param data The data to check if its been altered - * @throws DigestException The integrity mIntegrityFile cannot be read. Ensure - * {@link #isOk(byte[])} is called after {@link #update(byte[])}. Otherwise, consider the - * result vacuously true and immediately call {@link #update(byte[])}. - * @return true if the data was not altered since {@link #update(byte[])} was last called + * @param data The data to check if its been altered. + * @param integrityData Encrypted integrity data to be used for comparison. + * @return true if the integrity data computed on |data| matches the provided |integrityData|. */ - public boolean isOk(byte[] data) throws DigestException { + public boolean isOk(@NonNull byte[] data, @NonNull EncryptedData integrityData) { if (data == null || data.length < 1) { return KEYSTORE_FAILURE_RETURN_VALUE; } byte[] currentDigest = getDigest(data); if (currentDigest == null || currentDigest.length < 1) { + reportException(new Exception("current digest null"), "current digest null"); return KEYSTORE_FAILURE_RETURN_VALUE; } - - EncryptedData encryptedData = null; - - try { - encryptedData = readIntegrityData(mIntegrityFile); - } catch (IOException e) { - reportException(e, "readIntegrityData had an IO exception"); - return KEYSTORE_FAILURE_RETURN_VALUE; - } catch (ClassNotFoundException e) { - reportException(e, "readIntegrityData could not find the class EncryptedData"); + if (integrityData == null) { + reportException(new Exception("integrityData null in isOk"), + "integrityData null in isOk"); return KEYSTORE_FAILURE_RETURN_VALUE; } - - if (encryptedData == null) { - // File not found is not considered to be an error. - throw new DigestException("No stored digest is available to compare."); - } - byte[] storedDigest = decrypt(encryptedData); + byte[] storedDigest = decrypt(integrityData, getKeyAlias()); if (storedDigest == null) { return KEYSTORE_FAILURE_RETURN_VALUE; } @@ -177,7 +159,7 @@ public class DataIntegrityChecker { SecretKey secretKeyReference = getOrCreateSecretKey(keyAlias); if (secretKeyReference != null) { cipher.init(Cipher.ENCRYPT_MODE, secretKeyReference); - encryptedData = new EncryptedData(cipher.doFinal(data), cipher.getIV(), keyAlias); + encryptedData = new EncryptedData(cipher.doFinal(data), cipher.getIV()); } else { reportException(new Exception("secretKeyReference is null."), "secretKeyReference is null."); @@ -196,12 +178,12 @@ public class DataIntegrityChecker { return encryptedData; } - private byte[] decrypt(EncryptedData encryptedData) { + private byte[] decrypt(EncryptedData encryptedData, String keyAlias) { byte[] decryptedData = null; try { Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM); GCMParameterSpec spec = new GCMParameterSpec(GCM_TAG_LENGTH, encryptedData.getIv()); - SecretKey secretKeyReference = getOrCreateSecretKey(encryptedData.getKeyAlias()); + SecretKey secretKeyReference = getOrCreateSecretKey(keyAlias); if (secretKeyReference != null) { cipher.init(Cipher.DECRYPT_MODE, secretKeyReference, spec); decryptedData = cipher.doFinal(encryptedData.getEncryptedData()); @@ -268,30 +250,6 @@ public class DataIntegrityChecker { return secretKey; } - private void writeIntegrityData(EncryptedData encryptedData, File file) { - try (FileOutputStream fos = new FileOutputStream(file); - ObjectOutputStream oos = new ObjectOutputStream(fos)) { - oos.writeObject(encryptedData); - } catch (FileNotFoundException e) { - reportException(e, "writeIntegrityData could not find the integrity file"); - } catch (IOException e) { - reportException(e, "writeIntegrityData had an IO exception"); - } - } - - private EncryptedData readIntegrityData(File file) throws IOException, ClassNotFoundException { - try (FileInputStream fis = new FileInputStream(file); - ObjectInputStream ois = new ObjectInputStream(fis)) { - return (EncryptedData) ois.readObject(); - } catch (FileNotFoundException e) { - // File not found, this is not considered to be a real error. The file will be created - // by the system next time the data file is written. Note that it is not possible for - // non system user to delete or modify the file. - Log.w(TAG, "readIntegrityData could not find integrity file"); - } - return null; - } - private boolean constantTimeEquals(byte[] a, byte[] b) { if (a == null && b == null) { return true; @@ -311,7 +269,7 @@ public class DataIntegrityChecker { /* TODO(b/128526030): Remove this error reporting code upon resolving the bug. */ private static final boolean REQUEST_BUG_REPORT = false; private void reportException(Exception exception, String error) { - Log.wtf(TAG, "An irrecoverable key store error was encountered: " + error); + Log.wtf(TAG, "An irrecoverable key store error was encountered: " + error, exception); if (REQUEST_BUG_REPORT) { SystemProperties.set("dumpstate.options", "bugreportwifi"); SystemProperties.set("ctl.start", "bugreport"); diff --git a/service/java/com/android/server/wifi/util/EncryptedData.java b/service/java/com/android/server/wifi/util/EncryptedData.java index 468f28ec0..91342d335 100644 --- a/service/java/com/android/server/wifi/util/EncryptedData.java +++ b/service/java/com/android/server/wifi/util/EncryptedData.java @@ -16,22 +16,25 @@ package com.android.server.wifi.util; -import java.io.Serializable; +import com.android.internal.util.Preconditions; /** * A class to store data created by {@link DataIntegrityChecker}. */ -public class EncryptedData implements Serializable { - private static final long serialVersionUID = 1337L; - - private byte[] mEncryptedData; - private byte[] mIv; - private String mKeyAlias; - - public EncryptedData(byte[] encryptedData, byte[] iv, String keyAlias) { +public class EncryptedData { + public static final int ENCRYPTED_DATA_LENGTH = 48; + public static final int IV_LENGTH = 12; + + private final byte[] mEncryptedData; + private final byte[] mIv; + + public EncryptedData(byte[] encryptedData, byte[] iv) { + Preconditions.checkNotNull(encryptedData, iv); + Preconditions.checkState(encryptedData.length == ENCRYPTED_DATA_LENGTH, + "encryptedData.length=" + encryptedData.length); + Preconditions.checkState(iv.length == IV_LENGTH, "iv.length=" + iv.length); mEncryptedData = encryptedData; mIv = iv; - mKeyAlias = keyAlias; } public byte[] getEncryptedData() { @@ -41,8 +44,4 @@ public class EncryptedData implements Serializable { public byte[] getIv() { return mIv; } - - public String getKeyAlias() { - return mKeyAlias; - } } |