You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
140 lines
5.3 KiB
140 lines
5.3 KiB
/*
|
|
* 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.
|
|
*/
|
|
|
|
#include <keymaster/key_blob_utils/integrity_assured_key_blob.h>
|
|
|
|
#include <assert.h>
|
|
|
|
#include <openssl/hmac.h>
|
|
#include <openssl/mem.h>
|
|
|
|
#include <keymaster/android_keymaster_utils.h>
|
|
#include <keymaster/authorization_set.h>
|
|
#include <keymaster/km_openssl/openssl_err.h>
|
|
|
|
namespace keymaster {
|
|
|
|
static const uint8_t BLOB_VERSION = 0;
|
|
static const size_t HMAC_SIZE = 8;
|
|
static const char HMAC_KEY[] = "IntegrityAssuredBlob0";
|
|
|
|
inline size_t min(size_t a, size_t b) {
|
|
if (a < b) return a;
|
|
return b;
|
|
}
|
|
|
|
class HmacCleanup {
|
|
public:
|
|
explicit HmacCleanup(HMAC_CTX* ctx) : ctx_(ctx) {}
|
|
~HmacCleanup() { HMAC_CTX_cleanup(ctx_); }
|
|
|
|
private:
|
|
HMAC_CTX* ctx_;
|
|
};
|
|
|
|
static keymaster_error_t ComputeHmac(const uint8_t* serialized_data, size_t serialized_data_size,
|
|
const AuthorizationSet& hidden, uint8_t hmac[HMAC_SIZE]) {
|
|
size_t hidden_bytes_size = hidden.SerializedSize();
|
|
UniquePtr<uint8_t[]> hidden_bytes(new (std::nothrow) uint8_t[hidden_bytes_size]);
|
|
if (!hidden_bytes.get()) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
|
|
hidden.Serialize(hidden_bytes.get(), hidden_bytes.get() + hidden_bytes_size);
|
|
|
|
HMAC_CTX ctx;
|
|
HMAC_CTX_init(&ctx);
|
|
const EVP_MD* md = EVP_sha256();
|
|
if (!HMAC_Init_ex(&ctx, HMAC_KEY, sizeof(HMAC_KEY), md, nullptr /* engine */))
|
|
return TranslateLastOpenSslError();
|
|
HmacCleanup cleanup(&ctx);
|
|
|
|
uint8_t tmp[EVP_MAX_MD_SIZE];
|
|
unsigned tmp_len;
|
|
if (!HMAC_Update(&ctx, serialized_data, serialized_data_size) ||
|
|
!HMAC_Update(&ctx, hidden_bytes.get(), hidden_bytes_size) || //
|
|
!HMAC_Final(&ctx, tmp, &tmp_len))
|
|
return TranslateLastOpenSslError();
|
|
|
|
assert(tmp_len >= HMAC_SIZE);
|
|
memcpy(hmac, tmp, min(HMAC_SIZE, tmp_len));
|
|
|
|
return KM_ERROR_OK;
|
|
}
|
|
|
|
keymaster_error_t SerializeIntegrityAssuredBlob(const KeymasterKeyBlob& key_material,
|
|
const AuthorizationSet& hidden,
|
|
const AuthorizationSet& hw_enforced,
|
|
const AuthorizationSet& sw_enforced,
|
|
KeymasterKeyBlob* key_blob) {
|
|
size_t size = 1 /* version */ + //
|
|
key_material.SerializedSize() + //
|
|
hw_enforced.SerializedSize() + //
|
|
sw_enforced.SerializedSize() + //
|
|
HMAC_SIZE;
|
|
|
|
if (!key_blob->Reset(size)) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
|
|
|
|
uint8_t* p = key_blob->writable_data();
|
|
*p++ = BLOB_VERSION;
|
|
p = key_material.Serialize(p, key_blob->end());
|
|
p = hw_enforced.Serialize(p, key_blob->end());
|
|
p = sw_enforced.Serialize(p, key_blob->end());
|
|
|
|
return ComputeHmac(key_blob->key_material, p - key_blob->key_material, hidden, p);
|
|
}
|
|
|
|
keymaster_error_t DeserializeIntegrityAssuredBlob(const KeymasterKeyBlob& key_blob,
|
|
const AuthorizationSet& hidden,
|
|
KeymasterKeyBlob* key_material,
|
|
AuthorizationSet* hw_enforced,
|
|
AuthorizationSet* sw_enforced) {
|
|
const uint8_t* p = key_blob.begin();
|
|
const uint8_t* end = key_blob.end();
|
|
|
|
if (p > end || p + HMAC_SIZE > end) return KM_ERROR_INVALID_KEY_BLOB;
|
|
|
|
uint8_t computed_hmac[HMAC_SIZE];
|
|
keymaster_error_t error = ComputeHmac(key_blob.begin(), key_blob.key_material_size - HMAC_SIZE,
|
|
hidden, computed_hmac);
|
|
if (error != KM_ERROR_OK) return error;
|
|
|
|
if (CRYPTO_memcmp(key_blob.end() - HMAC_SIZE, computed_hmac, HMAC_SIZE) != 0)
|
|
return KM_ERROR_INVALID_KEY_BLOB;
|
|
|
|
return DeserializeIntegrityAssuredBlob_NoHmacCheck(key_blob, key_material, hw_enforced,
|
|
sw_enforced);
|
|
}
|
|
|
|
keymaster_error_t DeserializeIntegrityAssuredBlob_NoHmacCheck(const KeymasterKeyBlob& key_blob,
|
|
KeymasterKeyBlob* key_material,
|
|
AuthorizationSet* hw_enforced,
|
|
AuthorizationSet* sw_enforced) {
|
|
const uint8_t* p = key_blob.begin();
|
|
const uint8_t* end = key_blob.end() - HMAC_SIZE;
|
|
|
|
if (p > end) return KM_ERROR_INVALID_KEY_BLOB;
|
|
|
|
if (*p != BLOB_VERSION) return KM_ERROR_INVALID_KEY_BLOB;
|
|
++p;
|
|
|
|
if (!key_material->Deserialize(&p, end) || //
|
|
!hw_enforced->Deserialize(&p, end) || //
|
|
!sw_enforced->Deserialize(&p, end))
|
|
return KM_ERROR_INVALID_KEY_BLOB;
|
|
|
|
return KM_ERROR_OK;
|
|
}
|
|
|
|
} // namespace keymaster
|