/*
**
** Copyright 2017, 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/legacy_support/keymaster1_legacy_support.h>
#include <android-base/logging.h>
#include <assert.h>
#include <algorithm>
#include <vector>
namespace keymaster {
template <typename T> std::vector<T> make_vector(const T* array, size_t len) {
return std::vector<T>(array, array + len);
}
// This helper class implements just enough of the C++ standard collection interface to be able to
// accept push_back calls, and it does nothing but count them. It's useful when you want to count
// insertions but not actually store anything. It's used in digest_set_is_full below to count the
// size of a set intersection.
struct PushbackCounter {
struct value_type {
// NOLINTNEXTLINE(google-explicit-constructor)
template <typename T> value_type(const T&) {}
};
void push_back(const value_type&) { ++count; }
size_t count = 0;
};
static std::vector<keymaster_digest_t> full_digest_list = {
KM_DIGEST_MD5, KM_DIGEST_SHA1, KM_DIGEST_SHA_2_224,
KM_DIGEST_SHA_2_256, KM_DIGEST_SHA_2_384, KM_DIGEST_SHA_2_512};
template <typename Iter> static bool digest_set_is_full(Iter begin, Iter end) {
PushbackCounter counter;
std::set_intersection(begin, end, full_digest_list.begin(), full_digest_list.end(),
std::back_inserter(counter));
return counter.count == full_digest_list.size();
}
static keymaster_error_t add_digests(const keymaster1_device_t* dev, keymaster_algorithm_t algorithm,
keymaster_purpose_t purpose,
Keymaster1LegacySupport::DigestMap* map, bool* supports_all) {
auto key = std::make_pair(algorithm, purpose);
keymaster_digest_t* digests;
size_t digests_length;
keymaster_error_t error =
dev->get_supported_digests(dev, algorithm, purpose, &digests, &digests_length);
if (error != KM_ERROR_OK) {
LOG(ERROR) << "Error " << error << " getting supported digests from keymaster1 device";
return error;
}
std::unique_ptr<keymaster_digest_t, Malloc_Delete> digests_deleter(digests);
auto digest_vec = make_vector(digests, digests_length);
*supports_all = digest_set_is_full(digest_vec.begin(), digest_vec.end());
(*map)[key] = std::move(digest_vec);
return error;
}
static keymaster_error_t map_digests(const keymaster1_device_t* dev,
Keymaster1LegacySupport::DigestMap* map,
bool* supports_all) {
map->clear();
*supports_all = true;
keymaster_algorithm_t sig_algorithms[] = {KM_ALGORITHM_RSA, KM_ALGORITHM_EC, KM_ALGORITHM_HMAC};
keymaster_purpose_t sig_purposes[] = {KM_PURPOSE_SIGN, KM_PURPOSE_VERIFY};
for (auto algorithm : sig_algorithms)
for (auto purpose : sig_purposes) {
bool alg_purpose_supports_all;
keymaster_error_t error =
add_digests(dev, algorithm, purpose, map, &alg_purpose_supports_all);
if (error != KM_ERROR_OK)
return error;
*supports_all &= alg_purpose_supports_all;
}
keymaster_algorithm_t crypt_algorithms[] = {KM_ALGORITHM_RSA};
keymaster_purpose_t crypt_purposes[] = {KM_PURPOSE_ENCRYPT, KM_PURPOSE_DECRYPT};
for (auto algorithm : crypt_algorithms)
for (auto purpose : crypt_purposes) {
bool alg_purpose_supports_all;
keymaster_error_t error =
add_digests(dev, algorithm, purpose, map, &alg_purpose_supports_all);
if (error != KM_ERROR_OK)
return error;
*supports_all &= alg_purpose_supports_all;
}
return KM_ERROR_OK;
}
Keymaster1LegacySupport::Keymaster1LegacySupport(const keymaster1_device_t* dev) {
map_digests(dev, &device_digests_, &supports_all_);
}
template <typename Collection, typename Value> bool contains(const Collection& c, const Value& v) {
return std::find(c.begin(), c.end(), v) != c.end();
}
template <typename T>
static bool findUnsupportedDigest(keymaster_algorithm_t algorithm,
keymaster_purpose_t purpose,
keymaster_digest_t digest,
const T& params,
const Keymaster1LegacySupport::DigestMap& digest_map) {
auto supported_digests = digest_map.find(std::make_pair(algorithm, purpose));
if (supported_digests == digest_map.end())
// Invalid algorith/purpose pair (e.g. EC encrypt). Let the error be handled by HW module.
return false;
if (digest != KM_DIGEST_NONE && !contains(supported_digests->second, digest)) {
LOG(WARNING) << "Digest " << digest << " requested but not supported by KM1 hal";
return true;
}
for (auto& entry : params)
if (entry.tag == TAG_DIGEST)
if (!contains(supported_digests->second, entry.enumerated)) {
LOG(WARNING) << "Digest " << entry.enumerated << " requested but not supported by KM1 hal";
return true;
}
return false;
}
template <typename T>
bool requiresSoftwareDigesting(keymaster_algorithm_t algorithm, keymaster_purpose_t purpose,
keymaster_digest_t digest,
const T& params,
const Keymaster1LegacySupport::DigestMap& digest_map) {
switch (algorithm) {
case KM_ALGORITHM_AES:
case KM_ALGORITHM_TRIPLE_DES:
LOG(WARNING) << "Not performing software digesting for symmetric cipher keys";
return false;
case KM_ALGORITHM_HMAC:
case KM_ALGORITHM_RSA:
case KM_ALGORITHM_EC:
break;
}
if (!findUnsupportedDigest(algorithm, purpose, digest, params, digest_map)) {
LOG(DEBUG) << "Requested digest(s) supported for algorithm " << algorithm << " and purpose " << purpose;
return false;
}
return true;
}
bool Keymaster1LegacySupport::RequiresSoftwareDigesting(
const AuthorizationSet& key_description) const {
keymaster_algorithm_t algorithm;
if (!key_description.GetTagValue(TAG_ALGORITHM, &algorithm)) {
// The hardware module will return an error during keygen.
return false;
}
if (supports_all_) return false;
bool has_purpose = false;
for (auto& entry : key_description)
if (entry.tag == TAG_PURPOSE) {
has_purpose = true;
keymaster_purpose_t purpose = static_cast<keymaster_purpose_t>(entry.enumerated);
if (requiresSoftwareDigesting(algorithm, purpose, KM_DIGEST_NONE, key_description,
device_digests_))
return true;
}
return !has_purpose;
}
bool Keymaster1LegacySupport::RequiresSoftwareDigesting(const keymaster_digest_t digest,
const AuthProxy& key_description) const {
keymaster_algorithm_t algorithm;
if (!key_description.GetTagValue(TAG_ALGORITHM, &algorithm)) {
// The hardware module will return an error during keygen.
return false;
}
if (supports_all_) return false;
bool has_purpose = false;
for (auto& entry : key_description) {
if (entry.tag == TAG_PURPOSE) {
has_purpose = true;
keymaster_purpose_t purpose = static_cast<keymaster_purpose_t>(entry.enumerated);
if (requiresSoftwareDigesting(algorithm, purpose, digest, key_description,
device_digests_))
return true;
}
}
/*
* If the key does not have a purpose it is unusable, i.e., for private key operations.
* The public key operations which don't need purpose authorization may as well be done
* in software. This also addresses a bug by which begin operation on keys without purpose and
* unauthorized digest which is also not supported by the wrapped KM1 device fail with
* KM_UNSUPPORTED_DIGEST although they should not fail during the begin operation.
* If it has a purpose and we reach this point we did not find unsupported digests, and
* therefore do not required software digesting.
*/
return !has_purpose;
}
template<>
keymaster_error_t
Keymaster1ArbitrationFactory<EcdsaKeymaster1KeyFactory>::GenerateKey(
const AuthorizationSet& key_description,
KeymasterKeyBlob* key_blob, AuthorizationSet* hw_enforced,
AuthorizationSet* sw_enforced) const {
if (legacy_support_.RequiresSoftwareDigesting(key_description)) {
return software_digest_factory_.GenerateKey(key_description, key_blob, hw_enforced,
sw_enforced);
} else {
AuthorizationSet mutable_key_description = key_description;
keymaster_ec_curve_t curve;
if (key_description.GetTagValue(TAG_EC_CURVE, &curve)) {
// Keymaster1 doesn't know about EC curves. We need to translate to key size.
uint32_t key_size_from_curve;
keymaster_error_t error = EcCurveToKeySize(curve, &key_size_from_curve);
if (error != KM_ERROR_OK) {
return error;
}
uint32_t key_size_from_desc;
if (key_description.GetTagValue(TAG_KEY_SIZE, &key_size_from_desc)) {
if (key_size_from_desc != key_size_from_curve) {
return KM_ERROR_INVALID_ARGUMENT;
}
} else {
mutable_key_description.push_back(TAG_KEY_SIZE, key_size_from_curve);
}
}
return passthrough_factory_.GenerateKey(mutable_key_description, key_blob, hw_enforced,
sw_enforced);
}
}
template<>
keymaster_error_t
Keymaster1ArbitrationFactory<EcdsaKeymaster1KeyFactory>::LoadKey(KeymasterKeyBlob&& key_material,
const AuthorizationSet& additional_params,
AuthorizationSet&& hw_enforced,
AuthorizationSet&& sw_enforced,
UniquePtr<Key>* key) const {
keymaster_digest_t digest;
if (!additional_params.GetTagValue(TAG_DIGEST, &digest)) {
digest = KM_DIGEST_NONE;
}
bool requires_software_digesting = legacy_support_.RequiresSoftwareDigesting(digest,
AuthProxy(hw_enforced, sw_enforced));
auto rc = software_digest_factory_.LoadKey(move(key_material), additional_params,
move(hw_enforced), move(sw_enforced), key);
if (rc != KM_ERROR_OK) return rc;
if (!requires_software_digesting) {
(*key)->key_factory() = & passthrough_factory_;
}
return KM_ERROR_OK;
}
template<>
keymaster_error_t
Keymaster1ArbitrationFactory<RsaKeymaster1KeyFactory>::LoadKey(KeymasterKeyBlob&& key_material,
const AuthorizationSet& additional_params,
AuthorizationSet&& hw_enforced,
AuthorizationSet&& sw_enforced,
UniquePtr<Key>* key) const {
keymaster_digest_t digest;
if (!additional_params.GetTagValue(TAG_DIGEST, &digest)) {
digest = KM_DIGEST_NONE;
}
bool requires_software_digesting = legacy_support_.RequiresSoftwareDigesting(digest,
AuthProxy(hw_enforced, sw_enforced));
auto rc = software_digest_factory_.LoadKey(move(key_material), additional_params,
move(hw_enforced), move(sw_enforced), key);
if (rc != KM_ERROR_OK) return rc;
if (!requires_software_digesting) {
(*key)->key_factory() = & passthrough_factory_;
}
return KM_ERROR_OK;
}
} // namespace keymaster