platform_system_security/keystore/user_state.h
Shawn Willden 688d3ab299 Don't clear kesytore after 5 auth failures.
Keystore's security originally derived from encrypting keys with a key
derived from the user's password.  To avoid making keystore into a
password brute force oracle, keystore cleared itself after five
incorrect presentations.  All of this has been superseded by moving
keystore's security into Keymaster, and by moving password security
into Gatekeeper/Weaver, and further by implmenting the synthetic
password model.

This CL removes the now-useless and occasionally-dangerous keystore
self-destruct.

Test: Manual
Change-Id: Id85c1c39769701bbc0dcfcb76511faf9eeb65496
2019-11-13 06:30:13 -07:00

131 lines
3.9 KiB
C++

/*
* Copyright (C) 2016 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.
*/
#ifndef KEYSTORE_USER_STATE_H_
#define KEYSTORE_USER_STATE_H_
#include <sys/types.h>
#include <openssl/aes.h>
#include <utils/String8.h>
#include <keystore/keystore.h>
#include "blob.h"
#include "keystore_utils.h"
#include <android-base/logging.h>
#include <condition_variable>
#include <keystore/keystore_concurrency.h>
#include <mutex>
#include <set>
#include <vector>
namespace keystore {
class UserState;
template <typename UserState> using LockedUserState = ProxyLock<UnlockProxyLockHelper<UserState>>;
class UserState {
public:
explicit UserState(uid_t userId);
bool initialize();
uid_t getUserId() const { return mUserId; }
const std::string& getUserDirName() const { return mMasterKeyEntry.user_dir(); }
std::string getMasterKeyFileName() const { return mMasterKeyEntry.getKeyBlobPath(); }
void setState(State state);
State getState() const { return mState; }
void zeroizeMasterKeysInMemory();
bool deleteMasterKey();
ResponseCode initialize(const android::String8& pw);
ResponseCode copyMasterKey(LockedUserState<UserState>* src);
ResponseCode copyMasterKeyFile(LockedUserState<UserState>* src);
ResponseCode writeMasterKey(const android::String8& pw);
ResponseCode readMasterKey(const android::String8& pw);
const std::vector<uint8_t>& getEncryptionKey() const { return mMasterKey; }
bool reset();
bool operator<(const UserState& rhs) const;
bool operator<(uid_t userId) const;
private:
static constexpr int SHA1_DIGEST_SIZE_BYTES = 16;
static constexpr int SHA256_DIGEST_SIZE_BYTES = 32;
static constexpr int MASTER_KEY_SIZE_BYTES = kAes256KeySizeBytes;
static constexpr int MASTER_KEY_SIZE_BITS = MASTER_KEY_SIZE_BYTES * 8;
static constexpr size_t SALT_SIZE = 16;
void generateKeyFromPassword(std::vector<uint8_t>& key, const android::String8& pw,
uint8_t* salt);
bool generateSalt();
bool generateMasterKey();
void setupMasterKeys();
KeyBlobEntry mMasterKeyEntry;
uid_t mUserId;
State mState;
std::vector<uint8_t> mMasterKey;
uint8_t mSalt[SALT_SIZE];
};
bool operator<(uid_t userId, const UserState& rhs);
class UserStateDB {
public:
LockedUserState<UserState> getUserState(uid_t userId);
LockedUserState<UserState> getUserStateByUid(uid_t uid);
LockedUserState<const UserState> getUserState(uid_t userId) const;
LockedUserState<const UserState> getUserStateByUid(uid_t uid) const;
private:
mutable std::set<const UserState*> locked_state_;
mutable std::mutex locked_state_mutex_;
mutable std::condition_variable locked_state_mutex_cond_var_;
template <typename UserState>
LockedUserState<UserState> get(std::unique_lock<std::mutex> lock, UserState* entry) const {
locked_state_mutex_cond_var_.wait(
lock, [&] { return locked_state_.find(entry) == locked_state_.end(); });
locked_state_.insert(entry);
return {entry, [&](UserState* entry) {
std::unique_lock<std::mutex> lock(locked_state_mutex_);
locked_state_.erase(entry);
lock.unlock();
locked_state_mutex_cond_var_.notify_all();
}};
}
std::map<uid_t, UserState> mMasterKeys;
};
} // namespace keystore
#endif // KEYSTORE_USER_STATE_H_