Keystore 2.0: Implement legacy blob support.
This CL implements on-demand migration of legacy key blobs into
the Keystore 2.0.
This CL has joined authorship by
hasinigt@google.com and jdanis@google.com
Test: keystore2_test
CTS Test.
And manual test with key upgrade app.
Change-Id: I0a1f266c12f06cc2e196692d759dedf48b4d347a
diff --git a/keystore2/src/legacy_migrator.rs b/keystore2/src/legacy_migrator.rs
new file mode 100644
index 0000000..60c6bca
--- /dev/null
+++ b/keystore2/src/legacy_migrator.rs
@@ -0,0 +1,570 @@
+// Copyright 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.
+
+//! This module acts as a bridge between the legacy key database and the keystore2 database.
+
+use crate::database::{
+ BlobMetaData, BlobMetaEntry, CertificateInfo, DateTime, EncryptedBy, KeyMetaData, KeyMetaEntry,
+ KeystoreDB, Uuid, KEYSTORE_UUID,
+};
+use crate::error::Error;
+use crate::legacy_blob::BlobValue;
+use crate::utils::uid_to_android_user;
+use crate::{async_task::AsyncTask, legacy_blob::LegacyBlobLoader};
+use android_hardware_security_keymint::aidl::android::hardware::security::keymint::SecurityLevel::SecurityLevel;
+use android_system_keystore2::aidl::android::system::keystore2::{
+ Domain::Domain, KeyDescriptor::KeyDescriptor, ResponseCode::ResponseCode,
+};
+use anyhow::{Context, Result};
+use core::ops::Deref;
+use keystore2_crypto::ZVec;
+use std::collections::{HashMap, HashSet};
+use std::convert::TryInto;
+use std::sync::atomic::{AtomicU8, Ordering};
+use std::sync::mpsc::channel;
+use std::sync::{Arc, Mutex};
+
+/// Represents LegacyMigrator.
+pub struct LegacyMigrator {
+ async_task: Arc<AsyncTask>,
+ initializer: Mutex<
+ Option<
+ Box<
+ dyn FnOnce() -> (KeystoreDB, HashMap<SecurityLevel, Uuid>, Arc<LegacyBlobLoader>)
+ + Send
+ + 'static,
+ >,
+ >,
+ >,
+ /// This atomic is used for cheap interior mutability. It is intended to prevent
+ /// expensive calls into the legacy migrator when the legacy database is empty.
+ /// When transitioning from READY to EMPTY, spurious calls may occur for a brief period
+ /// of time. This is tolerable in favor of the common case.
+ state: AtomicU8,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+struct RecentMigration {
+ uid: u32,
+ alias: String,
+}
+
+impl RecentMigration {
+ fn new(uid: u32, alias: String) -> Self {
+ Self { uid, alias }
+ }
+}
+
+struct LegacyMigratorState {
+ recently_migrated: HashSet<RecentMigration>,
+ recently_migrated_super_key: HashSet<u32>,
+ legacy_loader: Arc<LegacyBlobLoader>,
+ sec_level_to_km_uuid: HashMap<SecurityLevel, Uuid>,
+ db: KeystoreDB,
+}
+
+impl LegacyMigrator {
+ const WIFI_NAMESPACE: i64 = 102;
+ const AID_WIFI: u32 = 1010;
+
+ const STATE_UNINITIALIZED: u8 = 0;
+ const STATE_READY: u8 = 1;
+ const STATE_EMPTY: u8 = 2;
+
+ /// Constructs a new LegacyMigrator using the given AsyncTask object as migration
+ /// worker.
+ pub fn new(async_task: Arc<AsyncTask>) -> Self {
+ Self {
+ async_task,
+ initializer: Default::default(),
+ state: AtomicU8::new(Self::STATE_UNINITIALIZED),
+ }
+ }
+
+ /// The legacy migrator must be initialized deferred, because keystore starts very early.
+ /// At this time the data partition may not be mounted. So we cannot open database connections
+ /// until we get actual key load requests. This sets the function that the legacy loader
+ /// uses to connect to the database.
+ pub fn set_init<F>(&self, f_init: F) -> Result<()>
+ where
+ F: FnOnce() -> (KeystoreDB, HashMap<SecurityLevel, Uuid>, Arc<LegacyBlobLoader>)
+ + Send
+ + 'static,
+ {
+ let mut initializer = self.initializer.lock().expect("Failed to lock initializer.");
+
+ // If we are not uninitialized we have no business setting the initializer.
+ if self.state.load(Ordering::Relaxed) != Self::STATE_UNINITIALIZED {
+ return Ok(());
+ }
+
+ // Only set the initializer if it hasn't been set before.
+ if initializer.is_none() {
+ *initializer = Some(Box::new(f_init))
+ }
+
+ Ok(())
+ }
+
+ /// This function is called by the migration requestor to check if it is worth
+ /// making a migration request. It also transitions the state from UNINITIALIZED
+ /// to READY or EMPTY on first use. The deferred initialization is necessary, because
+ /// Keystore 2.0 runs early during boot, where data may not yet be mounted.
+ /// Returns Ok(STATE_READY) if a migration request is worth undertaking and
+ /// Ok(STATE_EMPTY) if the database is empty. An error is returned if the loader
+ /// was not initialized and cannot be initialized.
+ fn check_state(&self) -> Result<u8> {
+ let mut first_try = true;
+ loop {
+ match (self.state.load(Ordering::Relaxed), first_try) {
+ (Self::STATE_EMPTY, _) => {
+ return Ok(Self::STATE_EMPTY);
+ }
+ (Self::STATE_UNINITIALIZED, true) => {
+ // If we find the legacy loader uninitialized, we grab the initializer lock,
+ // check if the legacy database is empty, and if not, schedule an initialization
+ // request. Coming out of the initializer lock, the state is either EMPTY or
+ // READY.
+ let mut initializer = self.initializer.lock().unwrap();
+
+ if let Some(initializer) = initializer.take() {
+ let (db, sec_level_to_km_uuid, legacy_loader) = (initializer)();
+
+ if legacy_loader.is_empty().context(
+ "In check_state: Trying to check if the legacy database is empty.",
+ )? {
+ self.state.store(Self::STATE_EMPTY, Ordering::Relaxed);
+ return Ok(Self::STATE_EMPTY);
+ }
+
+ self.async_task.queue_hi(move |shelf| {
+ shelf.get_or_put_with(|| LegacyMigratorState {
+ recently_migrated: Default::default(),
+ recently_migrated_super_key: Default::default(),
+ legacy_loader,
+ sec_level_to_km_uuid,
+ db,
+ });
+ });
+
+ // It is safe to set this here even though the async task may not yet have
+ // run because any thread observing this will not be able to schedule a
+ // task that can run before the initialization.
+ // Also we can only transition out of this state while having the
+ // initializer lock and having found an initializer.
+ self.state.store(Self::STATE_READY, Ordering::Relaxed);
+ return Ok(Self::STATE_READY);
+ } else {
+ // There is a chance that we just lost the race from state.load() to
+ // grabbing the initializer mutex. If that is the case the state must
+ // be EMPTY or READY after coming out of the lock. So we can give it
+ // one more try.
+ first_try = false;
+ continue;
+ }
+ }
+ (Self::STATE_UNINITIALIZED, false) => {
+ // Okay, tough luck. The legacy loader was really completely uninitialized.
+ return Err(Error::sys()).context(
+ "In check_state: Legacy loader should not be called uninitialized.",
+ );
+ }
+ (Self::STATE_READY, _) => return Ok(Self::STATE_READY),
+ (s, _) => panic!("Unknown legacy migrator state. {} ", s),
+ }
+ }
+ }
+
+ /// List all aliases for uid in the legacy database.
+ pub fn list_uid(&self, domain: Domain, namespace: i64) -> Result<Vec<KeyDescriptor>> {
+ let uid = match (domain, namespace) {
+ (Domain::APP, namespace) => namespace as u32,
+ (Domain::SELINUX, Self::WIFI_NAMESPACE) => Self::AID_WIFI,
+ _ => return Ok(Vec::new()),
+ };
+ self.do_serialized(move |state| state.list_uid(uid)).unwrap_or_else(|| Ok(Vec::new())).map(
+ |v| {
+ v.into_iter()
+ .map(|alias| KeyDescriptor {
+ domain,
+ nspace: namespace,
+ alias: Some(alias),
+ blob: None,
+ })
+ .collect()
+ },
+ )
+ }
+
+ /// Sends the given closure to the migrator thread for execution after calling check_state.
+ /// Returns None if the database was empty and the request was not executed.
+ /// Otherwise returns Some with the result produced by the migration request.
+ /// The loader state may transition to STATE_EMPTY during the execution of this function.
+ fn do_serialized<F, T: Send + 'static>(&self, f: F) -> Option<Result<T>>
+ where
+ F: FnOnce(&mut LegacyMigratorState) -> Result<T> + Send + 'static,
+ {
+ // Short circuit if the database is empty or not initialized (error case).
+ match self.check_state().context("In do_serialized: Checking state.") {
+ Ok(LegacyMigrator::STATE_EMPTY) => return None,
+ Ok(LegacyMigrator::STATE_READY) => {}
+ Err(e) => return Some(Err(e)),
+ Ok(s) => panic!("Unknown legacy migrator state. {} ", s),
+ }
+
+ // We have established that there may be a key in the legacy database.
+ // Now we schedule a migration request.
+ let (sender, receiver) = channel();
+ self.async_task.queue_hi(move |shelf| {
+ // Get the migrator state from the shelf.
+ // There may not be a state. This can happen if this migration request was scheduled
+ // before a previous request established that the legacy database was empty
+ // and removed the state from the shelf. Since we know now that the database
+ // is empty, we can return None here.
+ let (new_state, result) = if let Some(legacy_migrator_state) =
+ shelf.get_downcast_mut::<LegacyMigratorState>()
+ {
+ let result = f(legacy_migrator_state);
+ (legacy_migrator_state.check_empty(), Some(result))
+ } else {
+ (Self::STATE_EMPTY, None)
+ };
+
+ // If the migration request determined that the database is now empty, we discard
+ // the state from the shelf to free up the resources we won't need any longer.
+ if result.is_some() && new_state == Self::STATE_EMPTY {
+ shelf.remove_downcast_ref::<LegacyMigratorState>();
+ }
+
+ // Send the result to the requester.
+ if let Err(e) = sender.send((new_state, result)) {
+ log::error!("In do_serialized. Error in sending the result. {:?}", e);
+ }
+ });
+
+ let (new_state, result) = match receiver.recv() {
+ Err(e) => {
+ return Some(Err(e).context("In do_serialized. Failed to receive from the sender."))
+ }
+ Ok(r) => r,
+ };
+
+ // We can only transition to EMPTY but never back.
+ // The migrator never creates any legacy blobs.
+ if new_state == Self::STATE_EMPTY {
+ self.state.store(Self::STATE_EMPTY, Ordering::Relaxed)
+ }
+
+ result
+ }
+
+ /// Runs the key_accessor function and returns its result. If it returns an error and the
+ /// root cause was KEY_NOT_FOUND, tries to migrate a key with the given parameters from
+ /// the legacy database to the new database and runs the key_accessor function again if
+ /// the migration request was successful.
+ pub fn with_try_migrate<F, T>(
+ &self,
+ key: &KeyDescriptor,
+ caller_uid: u32,
+ key_accessor: F,
+ ) -> Result<T>
+ where
+ F: Fn() -> Result<T>,
+ {
+ // Access the key and return on success.
+ match key_accessor() {
+ Ok(result) => return Ok(result),
+ Err(e) => match e.root_cause().downcast_ref::<Error>() {
+ Some(&Error::Rc(ResponseCode::KEY_NOT_FOUND)) => {}
+ _ => return Err(e),
+ },
+ }
+
+ // Filter inputs. We can only load legacy app domain keys and some special rules due
+ // to which we migrate keys transparently to an SELINUX domain.
+ let uid = match key {
+ KeyDescriptor { domain: Domain::APP, alias: Some(_), .. } => caller_uid,
+ KeyDescriptor { domain: Domain::SELINUX, nspace, alias: Some(_), .. } => {
+ match *nspace {
+ Self::WIFI_NAMESPACE => Self::AID_WIFI,
+ _ => {
+ return Err(Error::Rc(ResponseCode::KEY_NOT_FOUND))
+ .context(format!("No legacy keys for namespace {}", nspace))
+ }
+ }
+ }
+ _ => {
+ return Err(Error::Rc(ResponseCode::KEY_NOT_FOUND))
+ .context("No legacy keys for key descriptor.")
+ }
+ };
+
+ let key_clone = key.clone();
+ let result = self
+ .do_serialized(move |migrator_state| migrator_state.check_and_migrate(uid, key_clone));
+
+ if let Some(result) = result {
+ result?;
+ // After successful migration try again.
+ key_accessor()
+ } else {
+ Err(Error::Rc(ResponseCode::KEY_NOT_FOUND)).context("Legacy database is empty.")
+ }
+ }
+
+ /// Calls key_accessor and returns the result on success. In the case of a KEY_NOT_FOUND error
+ /// this function makes a migration request and on success retries the key_accessor.
+ pub fn with_try_migrate_super_key<F, T>(
+ &self,
+ user_id: u32,
+ pw: &[u8],
+ mut key_accessor: F,
+ ) -> Result<Option<T>>
+ where
+ F: FnMut() -> Result<Option<T>>,
+ {
+ match key_accessor() {
+ Ok(Some(result)) => return Ok(Some(result)),
+ Ok(None) => {}
+ Err(e) => return Err(e),
+ }
+
+ let pw: ZVec = pw
+ .try_into()
+ .context("In with_try_migrate_super_key: copying the password into a zvec.")?;
+ let result = self.do_serialized(move |migrator_state| {
+ migrator_state.check_and_migrate_super_key(user_id, pw)
+ });
+
+ if let Some(result) = result {
+ result?;
+ // After successful migration try again.
+ key_accessor()
+ } else {
+ Ok(None)
+ }
+ }
+
+ /// Queries the legacy database for the presence of a super key for the given user.
+ pub fn has_super_key(&self, user_id: u32) -> Result<bool> {
+ let result =
+ self.do_serialized(move |migrator_state| migrator_state.has_super_key(user_id));
+ result.unwrap_or(Ok(false))
+ }
+}
+
+impl LegacyMigratorState {
+ fn get_km_uuid(&self, is_strongbox: bool) -> Result<Uuid> {
+ let sec_level = if is_strongbox {
+ SecurityLevel::STRONGBOX
+ } else {
+ SecurityLevel::TRUSTED_ENVIRONMENT
+ };
+
+ self.sec_level_to_km_uuid.get(&sec_level).copied().ok_or_else(|| {
+ anyhow::anyhow!(Error::sys()).context("In get_km_uuid: No KM instance for blob.")
+ })
+ }
+
+ fn list_uid(&mut self, uid: u32) -> Result<Vec<String>> {
+ self.legacy_loader
+ .list_keystore_entries_for_uid(uid)
+ .context("In list_uid: Trying to list legacy entries.")
+ }
+
+ /// This is a key migration request that can run in the migrator thread. This should
+ /// be passed to do_serialized.
+ fn check_and_migrate(&mut self, uid: u32, mut key: KeyDescriptor) -> Result<()> {
+ let alias = key.alias.clone().ok_or_else(|| {
+ anyhow::anyhow!(Error::sys()).context(concat!(
+ "In check_and_migrate: Must be Some because ",
+ "our caller must not have called us otherwise."
+ ))
+ })?;
+
+ if self.recently_migrated.contains(&RecentMigration::new(uid, alias.clone())) {
+ return Ok(());
+ }
+
+ if key.domain == Domain::APP {
+ key.nspace = uid as i64;
+ }
+
+ // If the key is not found in the cache, try to load from the legacy database.
+ let (km_blob_params, user_cert, ca_cert) = self
+ .legacy_loader
+ .load_by_uid_alias(uid, &alias, None)
+ .context("In check_and_migrate: Trying to load legacy blob.")?;
+ let result = match km_blob_params {
+ Some((km_blob, params)) => {
+ let is_strongbox = km_blob.is_strongbox();
+ let (blob, mut blob_metadata) = match km_blob.take_value() {
+ BlobValue::Encrypted { iv, tag, data } => {
+ // Get super key id for user id.
+ let user_id = uid_to_android_user(uid as u32);
+
+ let super_key_id = match self
+ .db
+ .load_super_key(user_id)
+ .context("In check_and_migrate: Failed to load super key")?
+ {
+ Some((_, entry)) => entry.id(),
+ None => {
+ // This might be the first time we access the super key,
+ // and it may not have been migrated. We cannot import
+ // the legacy super_key key now, because we need to reencrypt
+ // it which we cannot do if we are not unlocked, which we are
+ // not because otherwise the key would have been migrated.
+ // We can check though if the key exists. If it does,
+ // we can return Locked. Otherwise, we can delete the
+ // key and return NotFound, because the key will never
+ // be unlocked again.
+ if self.legacy_loader.has_super_key(user_id) {
+ return Err(Error::Rc(ResponseCode::LOCKED)).context(concat!(
+ "In check_and_migrate: Cannot migrate super key of this ",
+ "key while user is locked."
+ ));
+ } else {
+ self.legacy_loader.remove_keystore_entry(uid, &alias).context(
+ concat!(
+ "In check_and_migrate: ",
+ "Trying to remove obsolete key."
+ ),
+ )?;
+ return Err(Error::Rc(ResponseCode::KEY_NOT_FOUND))
+ .context("In check_and_migrate: Obsolete key.");
+ }
+ }
+ };
+
+ let mut blob_metadata = BlobMetaData::new();
+ blob_metadata.add(BlobMetaEntry::Iv(iv.to_vec()));
+ blob_metadata.add(BlobMetaEntry::AeadTag(tag.to_vec()));
+ blob_metadata
+ .add(BlobMetaEntry::EncryptedBy(EncryptedBy::KeyId(super_key_id)));
+ (LegacyBlob::Vec(data), blob_metadata)
+ }
+ BlobValue::Decrypted(data) => (LegacyBlob::ZVec(data), BlobMetaData::new()),
+ _ => {
+ return Err(Error::Rc(ResponseCode::KEY_NOT_FOUND))
+ .context("In check_and_migrate: Legacy key has unexpected type.")
+ }
+ };
+
+ let km_uuid = self
+ .get_km_uuid(is_strongbox)
+ .context("In check_and_migrate: Trying to get KM UUID")?;
+ blob_metadata.add(BlobMetaEntry::KmUuid(km_uuid));
+
+ let mut metadata = KeyMetaData::new();
+ let creation_date = DateTime::now()
+ .context("In check_and_migrate: Trying to make creation time.")?;
+ metadata.add(KeyMetaEntry::CreationDate(creation_date));
+
+ // Store legacy key in the database.
+ self.db
+ .store_new_key(
+ &key,
+ ¶ms,
+ &(&blob, &blob_metadata),
+ &CertificateInfo::new(user_cert, ca_cert),
+ &metadata,
+ &km_uuid,
+ )
+ .context("In check_and_migrate.")?;
+ Ok(())
+ }
+ None => {
+ if let Some(ca_cert) = ca_cert {
+ self.db
+ .store_new_certificate(&key, &ca_cert, &KEYSTORE_UUID)
+ .context("In check_and_migrate: Failed to insert new certificate.")?;
+ Ok(())
+ } else {
+ Err(Error::Rc(ResponseCode::KEY_NOT_FOUND))
+ .context("In check_and_migrate: Legacy key not found.")
+ }
+ }
+ };
+
+ match result {
+ Ok(()) => {
+ // Add the key to the migrated_keys list.
+ self.recently_migrated.insert(RecentMigration::new(uid, alias.clone()));
+ // Delete legacy key from the file system
+ self.legacy_loader
+ .remove_keystore_entry(uid, &alias)
+ .context("In check_and_migrate: Trying to remove migrated key.")?;
+ Ok(())
+ }
+ Err(e) => Err(e),
+ }
+ }
+
+ fn check_and_migrate_super_key(&mut self, user_id: u32, pw: ZVec) -> Result<()> {
+ if self.recently_migrated_super_key.contains(&user_id) {
+ return Ok(());
+ }
+
+ if let Some(super_key) = self
+ .legacy_loader
+ .load_super_key(user_id, &pw)
+ .context("In check_and_migrate_super_key: Trying to load legacy super key.")?
+ {
+ let (blob, blob_metadata) =
+ crate::super_key::SuperKeyManager::encrypt_with_password(&super_key, &pw)
+ .context("In check_and_migrate_super_key: Trying to encrypt super key.")?;
+
+ self.db.store_super_key(user_id, &(&blob, &blob_metadata)).context(concat!(
+ "In check_and_migrate_super_key: ",
+ "Trying to insert legacy super_key into the database."
+ ))?;
+ self.legacy_loader.remove_super_key(user_id);
+ self.recently_migrated_super_key.insert(user_id);
+ Ok(())
+ } else {
+ Err(Error::Rc(ResponseCode::KEY_NOT_FOUND))
+ .context("In check_and_migrate_super_key: No key found do migrate.")
+ }
+ }
+
+ fn has_super_key(&mut self, user_id: u32) -> Result<bool> {
+ Ok(self.recently_migrated_super_key.contains(&user_id)
+ || self.legacy_loader.has_super_key(user_id))
+ }
+
+ fn check_empty(&self) -> u8 {
+ if self.legacy_loader.is_empty().unwrap_or(false) {
+ LegacyMigrator::STATE_EMPTY
+ } else {
+ LegacyMigrator::STATE_READY
+ }
+ }
+}
+
+enum LegacyBlob {
+ Vec(Vec<u8>),
+ ZVec(ZVec),
+}
+
+impl Deref for LegacyBlob {
+ type Target = [u8];
+
+ fn deref(&self) -> &Self::Target {
+ match self {
+ Self::Vec(v) => &v,
+ Self::ZVec(v) => &v,
+ }
+ }
+}