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/*
* Copyright (C) 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 "auth_token_table.h"
#include <assert.h>
#include <time.h>
#include <algorithm>
#include <keymaster/android_keymaster_utils.h>
#include <keymaster/logger.h>
namespace keymaster {
//
// Some trivial template wrappers around std algorithms, so they take containers not ranges.
//
template <typename Container, typename Predicate>
typename Container::iterator find_if(Container& container, Predicate pred) {
return std::find_if(container.begin(), container.end(), pred);
}
template <typename Container, typename Predicate>
typename Container::iterator remove_if(Container& container, Predicate pred) {
return std::remove_if(container.begin(), container.end(), pred);
}
template <typename Container> typename Container::iterator min_element(Container& container) {
return std::min_element(container.begin(), container.end());
}
time_t clock_gettime_raw() {
struct timespec time;
clock_gettime(CLOCK_MONOTONIC_RAW, &time);
return time.tv_sec;
}
void AuthTokenTable::AddAuthenticationToken(const hw_auth_token_t* auth_token) {
Entry new_entry(auth_token, clock_function_());
RemoveEntriesSupersededBy(new_entry);
if (entries_.size() >= max_entries_) {
LOG_W("Auth token table filled up; replacing oldest entry", 0);
*min_element(entries_) = std::move(new_entry);
} else {
entries_.push_back(std::move(new_entry));
}
}
inline bool is_secret_key_operation(keymaster_algorithm_t algorithm, keymaster_purpose_t purpose) {
if ((algorithm != KM_ALGORITHM_RSA || algorithm != KM_ALGORITHM_EC))
return true;
if (purpose == KM_PURPOSE_SIGN || purpose == KM_PURPOSE_DECRYPT)
return true;
return false;
}
inline bool KeyRequiresAuthentication(const AuthorizationSet& key_info,
keymaster_purpose_t purpose) {
keymaster_algorithm_t algorithm = KM_ALGORITHM_AES;
key_info.GetTagValue(TAG_ALGORITHM, &algorithm);
return is_secret_key_operation(algorithm, purpose) && key_info.find(TAG_NO_AUTH_REQUIRED) == -1;
}
inline bool KeyRequiresAuthPerOperation(const AuthorizationSet& key_info,
keymaster_purpose_t purpose) {
keymaster_algorithm_t algorithm = KM_ALGORITHM_AES;
key_info.GetTagValue(TAG_ALGORITHM, &algorithm);
return is_secret_key_operation(algorithm, purpose) && key_info.find(TAG_AUTH_TIMEOUT) == -1;
}
AuthTokenTable::Error AuthTokenTable::FindAuthorization(const AuthorizationSet& key_info,
keymaster_purpose_t purpose,
keymaster_operation_handle_t op_handle,
const hw_auth_token_t** found) {
if (!KeyRequiresAuthentication(key_info, purpose))
return AUTH_NOT_REQUIRED;
hw_authenticator_type_t auth_type = HW_AUTH_NONE;
key_info.GetTagValue(TAG_USER_AUTH_TYPE, &auth_type);
std::vector<uint64_t> key_sids;
ExtractSids(key_info, &key_sids);
if (KeyRequiresAuthPerOperation(key_info, purpose))
return FindAuthPerOpAuthorization(key_sids, auth_type, op_handle, found);
else
return FindTimedAuthorization(key_sids, auth_type, key_info, found);
}
AuthTokenTable::Error AuthTokenTable::FindAuthPerOpAuthorization(
const std::vector<uint64_t>& sids, hw_authenticator_type_t auth_type,
keymaster_operation_handle_t op_handle, const hw_auth_token_t** found) {
if (op_handle == 0)
return OP_HANDLE_REQUIRED;
auto matching_op = find_if(
entries_, [&](Entry& e) { return e.token()->challenge == op_handle && !e.completed(); });
if (matching_op == entries_.end())
return AUTH_TOKEN_NOT_FOUND;
if (!matching_op->SatisfiesAuth(sids, auth_type))
return AUTH_TOKEN_WRONG_SID;
*found = matching_op->token();
return OK;
}
AuthTokenTable::Error AuthTokenTable::FindTimedAuthorization(const std::vector<uint64_t>& sids,
hw_authenticator_type_t auth_type,
const AuthorizationSet& key_info,
const hw_auth_token_t** found) {
Entry* newest_match = NULL;
for (auto& entry : entries_)
if (entry.SatisfiesAuth(sids, auth_type) && entry.is_newer_than(newest_match))
newest_match = &entry;
if (!newest_match)
return AUTH_TOKEN_NOT_FOUND;
uint32_t timeout;
key_info.GetTagValue(TAG_AUTH_TIMEOUT, &timeout);
time_t now = clock_function_();
if (static_cast<int64_t>(newest_match->time_received()) + timeout < static_cast<int64_t>(now))
return AUTH_TOKEN_EXPIRED;
if (key_info.GetTagValue(TAG_ALLOW_WHILE_ON_BODY)) {
if (static_cast<int64_t>(newest_match->time_received()) <
static_cast<int64_t>(last_off_body_)) {
return AUTH_TOKEN_EXPIRED;
}
}
newest_match->UpdateLastUse(now);
*found = newest_match->token();
return OK;
}
void AuthTokenTable::ExtractSids(const AuthorizationSet& key_info, std::vector<uint64_t>* sids) {
assert(sids);
for (auto& param : key_info)
if (param.tag == TAG_USER_SECURE_ID)
sids->push_back(param.long_integer);
}
void AuthTokenTable::RemoveEntriesSupersededBy(const Entry& entry) {
entries_.erase(remove_if(entries_, [&](Entry& e) { return entry.Supersedes(e); }),
entries_.end());
}
void AuthTokenTable::onDeviceOffBody() {
last_off_body_ = clock_function_();
}
void AuthTokenTable::Clear() {
entries_.clear();
}
bool AuthTokenTable::IsSupersededBySomeEntry(const Entry& entry) {
return std::any_of(entries_.begin(), entries_.end(),
[&](Entry& e) { return e.Supersedes(entry); });
}
void AuthTokenTable::MarkCompleted(const keymaster_operation_handle_t op_handle) {
auto found = find_if(entries_, [&](Entry& e) { return e.token()->challenge == op_handle; });
if (found == entries_.end())
return;
assert(!IsSupersededBySomeEntry(*found));
found->mark_completed();
if (IsSupersededBySomeEntry(*found))
entries_.erase(found);
}
AuthTokenTable::Entry::Entry(const hw_auth_token_t* token, time_t current_time)
: token_(token), time_received_(current_time), last_use_(current_time),
operation_completed_(token_->challenge == 0) {
}
uint32_t AuthTokenTable::Entry::timestamp_host_order() const {
return ntoh(token_->timestamp);
}
hw_authenticator_type_t AuthTokenTable::Entry::authenticator_type() const {
hw_authenticator_type_t result = static_cast<hw_authenticator_type_t>(
ntoh(static_cast<uint32_t>(token_->authenticator_type)));
return result;
}
bool AuthTokenTable::Entry::SatisfiesAuth(const std::vector<uint64_t>& sids,
hw_authenticator_type_t auth_type) {
for (auto sid : sids)
if ((sid == token_->authenticator_id) ||
(sid == token_->user_id && (auth_type & authenticator_type()) != 0))
return true;
return false;
}
void AuthTokenTable::Entry::UpdateLastUse(time_t time) {
this->last_use_ = time;
}
bool AuthTokenTable::Entry::Supersedes(const Entry& entry) const {
if (!entry.completed())
return false;
return (token_->user_id == entry.token_->user_id &&
token_->authenticator_type == entry.token_->authenticator_type &&
token_->authenticator_type == entry.token_->authenticator_type &&
timestamp_host_order() > entry.timestamp_host_order());
}
} // namespace keymaster
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