platform_system_security/keystore/auth_token_table.cpp
David Zeuthen ab3e565511 Add credstore system daemon.
The credstore system daemon is sitting below the Identity Credential
Framework APIs and on top of the Identity Credential HALs. Its main
job is to store credential data and provide a way for applications to
communicate with the secure hardware abstracted by the HAL.

This daemon runs as an unprivileged user, credstore.

The auth-tokens needed by credstore are supplied by keystore and this
CL includes the requisite changes to keystore for this to work.

Bug: 111446262
Test: CTS tests for Framework APIs
Change-Id: Ieb4d59852a143482436a1c418c25ed96e25c0047
2020-01-16 13:05:48 -05:00

298 lines
10 KiB
C++

/*
* 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.
*/
#define LOG_TAG "keystore"
#include "auth_token_table.h"
#include <assert.h>
#include <time.h>
#include <algorithm>
#include <log/log.h>
namespace keystore {
template <typename IntType, uint32_t byteOrder> struct choose_hton;
template <typename IntType> struct choose_hton<IntType, __ORDER_LITTLE_ENDIAN__> {
inline static IntType hton(const IntType& value) {
IntType result = 0;
const unsigned char* inbytes = reinterpret_cast<const unsigned char*>(&value);
unsigned char* outbytes = reinterpret_cast<unsigned char*>(&result);
for (int i = sizeof(IntType) - 1; i >= 0; --i) {
*(outbytes++) = inbytes[i];
}
return result;
}
};
template <typename IntType> struct choose_hton<IntType, __ORDER_BIG_ENDIAN__> {
inline static IntType hton(const IntType& value) { return value; }
};
template <typename IntType> inline IntType hton(const IntType& value) {
return choose_hton<IntType, __BYTE_ORDER__>::hton(value);
}
template <typename IntType> inline IntType ntoh(const IntType& value) {
// same operation and hton
return choose_hton<IntType, __BYTE_ORDER__>::hton(value);
}
//
// 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(HardwareAuthToken&& auth_token) {
Entry new_entry(std::move(auth_token), clock_function_());
// STOPSHIP: debug only, to be removed
ALOGD("AddAuthenticationToken: timestamp = %llu, time_received = %lld",
static_cast<unsigned long long>(new_entry.token().timestamp),
static_cast<long long>(new_entry.time_received()));
std::lock_guard<std::mutex> lock(entries_mutex_);
RemoveEntriesSupersededBy(new_entry);
if (entries_.size() >= max_entries_) {
ALOGW("Auth token table filled up; replacing oldest entry");
*min_element(entries_) = std::move(new_entry);
} else {
entries_.push_back(std::move(new_entry));
}
}
inline bool is_secret_key_operation(Algorithm algorithm, KeyPurpose purpose) {
if ((algorithm != Algorithm::RSA && algorithm != Algorithm::EC)) return true;
if (purpose == KeyPurpose::SIGN || purpose == KeyPurpose::DECRYPT) return true;
return false;
}
inline bool KeyRequiresAuthentication(const AuthorizationSet& key_info, KeyPurpose purpose) {
auto algorithm = defaultOr(key_info.GetTagValue(TAG_ALGORITHM), Algorithm::AES);
return is_secret_key_operation(algorithm, purpose) &&
key_info.find(Tag::NO_AUTH_REQUIRED) == -1;
}
inline bool KeyRequiresAuthPerOperation(const AuthorizationSet& key_info, KeyPurpose purpose) {
auto algorithm = defaultOr(key_info.GetTagValue(TAG_ALGORITHM), Algorithm::AES);
return is_secret_key_operation(algorithm, purpose) && key_info.find(Tag::AUTH_TIMEOUT) == -1;
}
std::tuple<AuthTokenTable::Error, HardwareAuthToken>
AuthTokenTable::FindAuthorization(const AuthorizationSet& key_info, KeyPurpose purpose,
uint64_t op_handle) {
std::lock_guard<std::mutex> lock(entries_mutex_);
if (!KeyRequiresAuthentication(key_info, purpose)) return {AUTH_NOT_REQUIRED, {}};
auto auth_type =
defaultOr(key_info.GetTagValue(TAG_USER_AUTH_TYPE), HardwareAuthenticatorType::NONE);
std::vector<uint64_t> key_sids;
ExtractSids(key_info, &key_sids);
if (KeyRequiresAuthPerOperation(key_info, purpose))
return FindAuthPerOpAuthorization(key_sids, auth_type, op_handle);
else
return FindTimedAuthorization(key_sids, auth_type, key_info);
}
std::tuple<AuthTokenTable::Error, HardwareAuthToken> AuthTokenTable::FindAuthPerOpAuthorization(
const std::vector<uint64_t>& sids, HardwareAuthenticatorType auth_type, uint64_t op_handle) {
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, {}};
return {OK, matching_op->token()};
}
std::tuple<AuthTokenTable::Error, HardwareAuthToken>
AuthTokenTable::FindTimedAuthorization(const std::vector<uint64_t>& sids,
HardwareAuthenticatorType auth_type,
const AuthorizationSet& key_info) {
Entry* newest_match = nullptr;
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, {}};
auto timeout = defaultOr(key_info.GetTagValue(TAG_AUTH_TIMEOUT), 0);
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).isOk()) {
if (static_cast<int64_t>(newest_match->time_received()) <
static_cast<int64_t>(last_off_body_)) {
return {AUTH_TOKEN_EXPIRED, {}};
}
}
newest_match->UpdateLastUse(now);
return {OK, newest_match->token()};
}
std::tuple<AuthTokenTable::Error, HardwareAuthToken>
AuthTokenTable::FindAuthorizationForCredstore(uint64_t challenge, uint64_t secureUserId,
int64_t authTokenMaxAgeMillis) {
std::vector<uint64_t> sids = {secureUserId};
HardwareAuthenticatorType auth_type = HardwareAuthenticatorType::ANY;
time_t now = clock_function_();
// challenge-based - the authToken has to contain the given challenge.
if (challenge != 0) {
auto matching_op = find_if(
entries_, [&](Entry& e) { return e.token().challenge == challenge && !e.completed(); });
if (matching_op == entries_.end()) {
return {AUTH_TOKEN_NOT_FOUND, {}};
}
if (!matching_op->SatisfiesAuth(sids, auth_type)) {
return {AUTH_TOKEN_WRONG_SID, {}};
}
if (authTokenMaxAgeMillis > 0) {
if (static_cast<int64_t>(matching_op->time_received()) + authTokenMaxAgeMillis <
static_cast<int64_t>(now)) {
return {AUTH_TOKEN_EXPIRED, {}};
}
}
return {OK, matching_op->token()};
}
// Otherwise, no challenge - any authToken younger than the specified maximum
// age will do.
Entry* newest_match = nullptr;
for (auto& entry : entries_) {
if (entry.SatisfiesAuth(sids, auth_type) && entry.is_newer_than(newest_match)) {
newest_match = &entry;
}
}
if (newest_match == nullptr) {
return {AUTH_TOKEN_NOT_FOUND, {}};
}
if (authTokenMaxAgeMillis > 0) {
if (static_cast<int64_t>(newest_match->time_received()) + authTokenMaxAgeMillis <
static_cast<int64_t>(now)) {
return {AUTH_TOKEN_EXPIRED, {}};
}
}
newest_match->UpdateLastUse(now);
return {OK, newest_match->token()};
}
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(authorizationValue(TAG_USER_SECURE_ID, param).value());
}
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() {
std::lock_guard<std::mutex> lock(entries_mutex_);
entries_.clear();
}
size_t AuthTokenTable::size() const {
std::lock_guard<std::mutex> lock(entries_mutex_);
return entries_.size();
}
bool AuthTokenTable::IsSupersededBySomeEntry(const Entry& entry) {
return std::any_of(entries_.begin(), entries_.end(),
[&](Entry& e) { return e.Supersedes(entry); });
}
void AuthTokenTable::MarkCompleted(const uint64_t op_handle) {
std::lock_guard<std::mutex> lock(entries_mutex_);
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(HardwareAuthToken&& token, time_t current_time)
: token_(std::move(token)), time_received_(current_time), last_use_(current_time),
operation_completed_(token_.challenge == 0) {}
bool AuthTokenTable::Entry::SatisfiesAuth(const std::vector<uint64_t>& sids,
HardwareAuthenticatorType auth_type) {
for (auto sid : sids) {
if (SatisfiesAuth(sid, auth_type)) 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_.userId == entry.token_.userId &&
token_.authenticatorType == entry.token_.authenticatorType &&
token_.authenticatorId == entry.token_.authenticatorId && is_newer_than(&entry));
}
} // namespace keystore