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/*
* Copyright 2015 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 SOFT_GATEKEEPER_H_
#define SOFT_GATEKEEPER_H_
extern "C" {
#include <openssl/rand.h>
#include <openssl/sha.h>
#include <crypto_scrypt.h>
}
#include <android-base/memory.h>
#include <gatekeeper/gatekeeper.h>
#include <nativehelper/UniquePtr.h>
#include <iostream>
#include <unordered_map>
namespace gatekeeper {
struct fast_hash_t {
uint64_t salt;
uint8_t digest[SHA256_DIGEST_LENGTH];
};
class SoftGateKeeper : public GateKeeper {
public:
static const uint32_t SIGNATURE_LENGTH_BYTES = 32;
// scrypt params
static const uint64_t N = 16384;
static const uint32_t r = 8;
static const uint32_t p = 1;
static const int MAX_UINT_32_CHARS = 11;
SoftGateKeeper() {
key_.reset(new uint8_t[SIGNATURE_LENGTH_BYTES]);
memset(key_.get(), 0, SIGNATURE_LENGTH_BYTES);
}
virtual ~SoftGateKeeper() {
}
virtual bool GetAuthTokenKey(const uint8_t **auth_token_key,
uint32_t *length) const {
if (auth_token_key == NULL || length == NULL) return false;
uint8_t *auth_token_key_copy = new uint8_t[SIGNATURE_LENGTH_BYTES];
memcpy(auth_token_key_copy, key_.get(), SIGNATURE_LENGTH_BYTES);
*auth_token_key = auth_token_key_copy;
*length = SIGNATURE_LENGTH_BYTES;
return true;
}
virtual void GetPasswordKey(const uint8_t **password_key, uint32_t *length) {
if (password_key == NULL || length == NULL) return;
uint8_t *password_key_copy = new uint8_t[SIGNATURE_LENGTH_BYTES];
memcpy(password_key_copy, key_.get(), SIGNATURE_LENGTH_BYTES);
*password_key = password_key_copy;
*length = SIGNATURE_LENGTH_BYTES;
}
virtual void ComputePasswordSignature(uint8_t *signature, uint32_t signature_length,
const uint8_t *, uint32_t, const uint8_t *password,
uint32_t password_length, salt_t salt) const {
if (signature == NULL) return;
crypto_scrypt(password, password_length, reinterpret_cast<uint8_t *>(&salt),
sizeof(salt), N, r, p, signature, signature_length);
}
virtual void GetRandom(void *random, uint32_t requested_length) const {
if (random == NULL) return;
RAND_pseudo_bytes((uint8_t *) random, requested_length);
}
virtual void ComputeSignature(uint8_t *signature, uint32_t signature_length,
const uint8_t *, uint32_t, const uint8_t *, const uint32_t) const {
if (signature == NULL) return;
memset(signature, 0, signature_length);
}
virtual uint64_t GetMillisecondsSinceBoot() const {
struct timespec time;
int res = clock_gettime(CLOCK_BOOTTIME, &time);
if (res < 0) return 0;
return (time.tv_sec * 1000) + (time.tv_nsec / 1000 / 1000);
}
virtual bool IsHardwareBacked() const {
return false;
}
virtual bool GetFailureRecord(uint32_t uid, secure_id_t user_id, failure_record_t *record,
bool /* secure */) {
failure_record_t *stored = &failure_map_[uid];
if (user_id != stored->secure_user_id) {
stored->secure_user_id = user_id;
stored->last_checked_timestamp = 0;
stored->failure_counter = 0;
}
memcpy(record, stored, sizeof(*record));
return true;
}
virtual bool ClearFailureRecord(uint32_t uid, secure_id_t user_id, bool /* secure */) {
failure_record_t *stored = &failure_map_[uid];
stored->secure_user_id = user_id;
stored->last_checked_timestamp = 0;
stored->failure_counter = 0;
return true;
}
virtual bool WriteFailureRecord(uint32_t uid, failure_record_t *record, bool /* secure */) {
failure_map_[uid] = *record;
return true;
}
fast_hash_t ComputeFastHash(const SizedBuffer &password, uint64_t salt) {
fast_hash_t fast_hash;
size_t digest_size = password.length + sizeof(salt);
std::unique_ptr<uint8_t[]> digest(new uint8_t[digest_size]);
memcpy(digest.get(), &salt, sizeof(salt));
memcpy(digest.get() + sizeof(salt), password.buffer.get(), password.length);
SHA256(digest.get(), digest_size, (uint8_t *) &fast_hash.digest);
fast_hash.salt = salt;
return fast_hash;
}
bool VerifyFast(const fast_hash_t &fast_hash, const SizedBuffer &password) {
fast_hash_t computed = ComputeFastHash(password, fast_hash.salt);
return memcmp(computed.digest, fast_hash.digest, SHA256_DIGEST_LENGTH) == 0;
}
bool DoVerify(const password_handle_t *expected_handle, const SizedBuffer &password) {
uint64_t user_id = android::base::get_unaligned<secure_id_t>(&expected_handle->user_id);
FastHashMap::const_iterator it = fast_hash_map_.find(user_id);
if (it != fast_hash_map_.end() && VerifyFast(it->second, password)) {
return true;
} else {
if (GateKeeper::DoVerify(expected_handle, password)) {
uint64_t salt;
GetRandom(&salt, sizeof(salt));
fast_hash_map_[user_id] = ComputeFastHash(password, salt);
return true;
}
}
return false;
}
private:
typedef std::unordered_map<uint32_t, failure_record_t> FailureRecordMap;
typedef std::unordered_map<uint64_t, fast_hash_t> FastHashMap;
UniquePtr<uint8_t[]> key_;
FailureRecordMap failure_map_;
FastHashMap fast_hash_map_;
};
}
#endif // SOFT_GATEKEEPER_H_
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