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725 lines
28 KiB
725 lines
28 KiB
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "KeyStorage.h"
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#include "Checkpoint.h"
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#include "Keymaster.h"
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#include "ScryptParameters.h"
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#include "Utils.h"
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#include <algorithm>
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#include <memory>
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#include <mutex>
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#include <thread>
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#include <vector>
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#include <errno.h>
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#include <stdio.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <openssl/err.h>
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#include <openssl/evp.h>
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#include <openssl/sha.h>
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#include <android-base/file.h>
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#include <android-base/logging.h>
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#include <android-base/properties.h>
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#include <android-base/unique_fd.h>
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#include <cutils/properties.h>
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extern "C" {
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#include "crypto_scrypt.h"
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}
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namespace android {
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namespace vold {
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const KeyAuthentication kEmptyAuthentication{""};
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static constexpr size_t AES_KEY_BYTES = 32;
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static constexpr size_t GCM_NONCE_BYTES = 12;
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static constexpr size_t GCM_MAC_BYTES = 16;
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static constexpr size_t SECDISCARDABLE_BYTES = 1 << 14;
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static const char* kCurrentVersion = "1";
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static const char* kRmPath = "/system/bin/rm";
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static const char* kSecdiscardPath = "/system/bin/secdiscard";
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static const char* kStretch_none = "none";
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static const char* kStretch_nopassword = "nopassword";
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static const char* kHashPrefix_secdiscardable = "Android secdiscardable SHA512";
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static const char* kHashPrefix_keygen = "Android key wrapping key generation SHA512";
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static const char* kFn_encrypted_key = "encrypted_key";
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static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
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static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
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static const char* kFn_secdiscardable = "secdiscardable";
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static const char* kFn_stretching = "stretching";
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static const char* kFn_version = "version";
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namespace {
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// Storage binding info for ensuring key encryption keys include a
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// platform-provided seed in their derivation.
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struct StorageBindingInfo {
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enum class State {
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UNINITIALIZED,
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IN_USE, // key storage keys are bound to seed
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NOT_USED, // key storage keys are NOT bound to seed
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};
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// Binding seed mixed into all key storage keys.
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std::vector<uint8_t> seed;
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// State tracker for the key storage key binding.
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State state = State::UNINITIALIZED;
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std::mutex guard;
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};
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// Never freed as the dtor is non-trivial.
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StorageBindingInfo& storage_binding_info = *new StorageBindingInfo;
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} // namespace
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static bool checkSize(const std::string& kind, size_t actual, size_t expected) {
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if (actual != expected) {
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LOG(ERROR) << "Wrong number of bytes in " << kind << ", expected " << expected << " got "
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<< actual;
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return false;
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}
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return true;
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}
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static void hashWithPrefix(char const* prefix, const std::string& tohash, std::string* res) {
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SHA512_CTX c;
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SHA512_Init(&c);
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// Personalise the hashing by introducing a fixed prefix.
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// Hashing applications should use personalization except when there is a
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// specific reason not to; see section 4.11 of https://www.schneier.com/skein1.3.pdf
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std::string hashingPrefix = prefix;
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hashingPrefix.resize(SHA512_CBLOCK);
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SHA512_Update(&c, hashingPrefix.data(), hashingPrefix.size());
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SHA512_Update(&c, tohash.data(), tohash.size());
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res->assign(SHA512_DIGEST_LENGTH, '\0');
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SHA512_Final(reinterpret_cast<uint8_t*>(&(*res)[0]), &c);
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}
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// Generates a keymaster key, using rollback resistance if supported.
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static bool generateKeymasterKey(Keymaster& keymaster,
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const km::AuthorizationSetBuilder& paramBuilder,
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std::string* key) {
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auto paramsWithRollback = paramBuilder;
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paramsWithRollback.Authorization(km::TAG_ROLLBACK_RESISTANCE);
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if (!keymaster.generateKey(paramsWithRollback, key)) {
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LOG(WARNING) << "Failed to generate rollback-resistant key. This is expected if keymaster "
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"doesn't support rollback resistance. Falling back to "
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"non-rollback-resistant key.";
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if (!keymaster.generateKey(paramBuilder, key)) return false;
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}
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return true;
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}
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static bool generateKeyStorageKey(Keymaster& keymaster, const std::string& appId,
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std::string* key) {
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auto paramBuilder = km::AuthorizationSetBuilder()
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.AesEncryptionKey(AES_KEY_BYTES * 8)
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.GcmModeMinMacLen(GCM_MAC_BYTES * 8)
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.Authorization(km::TAG_APPLICATION_ID, appId)
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.Authorization(km::TAG_NO_AUTH_REQUIRED);
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LOG(DEBUG) << "Generating \"key storage\" key";
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return generateKeymasterKey(keymaster, paramBuilder, key);
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}
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bool generateWrappedStorageKey(KeyBuffer* key) {
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Keymaster keymaster;
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if (!keymaster) return false;
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std::string key_temp;
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auto paramBuilder = km::AuthorizationSetBuilder().AesEncryptionKey(AES_KEY_BYTES * 8);
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paramBuilder.Authorization(km::TAG_STORAGE_KEY);
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if (!generateKeymasterKey(keymaster, paramBuilder, &key_temp)) return false;
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*key = KeyBuffer(key_temp.size());
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memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
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return true;
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}
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bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key) {
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Keymaster keymaster;
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if (!keymaster) return false;
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std::string key_temp;
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if (!keymaster.exportKey(kmKey, &key_temp)) return false;
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*key = KeyBuffer(key_temp.size());
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memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
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return true;
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}
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static km::AuthorizationSet beginParams(const std::string& appId) {
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return km::AuthorizationSetBuilder()
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.GcmModeMacLen(GCM_MAC_BYTES * 8)
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.Authorization(km::TAG_APPLICATION_ID, appId);
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}
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static bool readFileToString(const std::string& filename, std::string* result) {
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if (!android::base::ReadFileToString(filename, result)) {
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PLOG(ERROR) << "Failed to read from " << filename;
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return false;
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}
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return true;
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}
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static bool readRandomBytesOrLog(size_t count, std::string* out) {
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auto status = ReadRandomBytes(count, *out);
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if (status != OK) {
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LOG(ERROR) << "Random read failed with status: " << status;
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return false;
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}
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return true;
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}
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bool createSecdiscardable(const std::string& filename, std::string* hash) {
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std::string secdiscardable;
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if (!readRandomBytesOrLog(SECDISCARDABLE_BYTES, &secdiscardable)) return false;
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if (!writeStringToFile(secdiscardable, filename)) return false;
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hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash);
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return true;
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}
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bool readSecdiscardable(const std::string& filename, std::string* hash) {
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std::string secdiscardable;
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if (!readFileToString(filename, &secdiscardable)) return false;
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hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash);
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return true;
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}
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static std::mutex key_upgrade_lock;
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// List of key directories that have had their Keymaster key upgraded during
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// this boot and written to "keymaster_key_blob_upgraded", but replacing the old
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// key was delayed due to an active checkpoint. Protected by key_upgrade_lock.
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static std::vector<std::string> key_dirs_to_commit;
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// Replaces |dir|/keymaster_key_blob with |dir|/keymaster_key_blob_upgraded and
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// deletes the old key from Keymaster.
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static bool CommitUpgradedKey(Keymaster& keymaster, const std::string& dir) {
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auto blob_file = dir + "/" + kFn_keymaster_key_blob;
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auto upgraded_blob_file = dir + "/" + kFn_keymaster_key_blob_upgraded;
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std::string blob;
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if (!readFileToString(blob_file, &blob)) return false;
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if (rename(upgraded_blob_file.c_str(), blob_file.c_str()) != 0) {
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PLOG(ERROR) << "Failed to rename " << upgraded_blob_file << " to " << blob_file;
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return false;
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}
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// Ensure that the rename is persisted before deleting the Keymaster key.
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if (!FsyncDirectory(dir)) return false;
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if (!keymaster || !keymaster.deleteKey(blob)) {
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LOG(WARNING) << "Failed to delete old key " << blob_file
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<< " from Keymaster; continuing anyway";
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// Continue on, but the space in Keymaster used by the old key won't be freed.
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}
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return true;
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}
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static void DeferredCommitKeys() {
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android::base::WaitForProperty("vold.checkpoint_committed", "1");
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LOG(INFO) << "Committing upgraded keys";
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Keymaster keymaster;
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if (!keymaster) {
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LOG(ERROR) << "Failed to open Keymaster; old keys won't be deleted from Keymaster";
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// Continue on, but the space in Keymaster used by the old keys won't be freed.
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}
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std::lock_guard<std::mutex> lock(key_upgrade_lock);
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for (auto& dir : key_dirs_to_commit) {
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LOG(INFO) << "Committing upgraded key " << dir;
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CommitUpgradedKey(keymaster, dir);
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}
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key_dirs_to_commit.clear();
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}
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// Returns true if the Keymaster key in |dir| has already been upgraded and is
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// pending being committed. Assumes that key_upgrade_lock is held.
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static bool IsKeyCommitPending(const std::string& dir) {
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for (const auto& dir_to_commit : key_dirs_to_commit) {
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if (IsSameFile(dir, dir_to_commit)) return true;
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}
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return false;
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}
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// Schedules the upgraded Keymaster key in |dir| to be committed later.
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// Assumes that key_upgrade_lock is held.
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static void ScheduleKeyCommit(const std::string& dir) {
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if (key_dirs_to_commit.empty()) std::thread(DeferredCommitKeys).detach();
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key_dirs_to_commit.push_back(dir);
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}
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static void CancelPendingKeyCommit(const std::string& dir) {
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std::lock_guard<std::mutex> lock(key_upgrade_lock);
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for (auto it = key_dirs_to_commit.begin(); it != key_dirs_to_commit.end(); it++) {
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if (IsSameFile(*it, dir)) {
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LOG(DEBUG) << "Cancelling pending commit of upgraded key " << dir
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<< " because it is being destroyed";
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key_dirs_to_commit.erase(it);
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break;
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}
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}
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}
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// Renames a key directory. Also updates the deferred commit vector
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// (key_dirs_to_commit) appropriately.
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//
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// However, @old_name must be the path to the directory that was used to put that
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// directory into the deferred commit list in the first place (since this function
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// directly compares paths instead of using IsSameFile()).
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static bool RenameKeyDir(const std::string& old_name, const std::string& new_name) {
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std::lock_guard<std::mutex> lock(key_upgrade_lock);
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if (rename(old_name.c_str(), new_name.c_str()) != 0) return false;
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// IsSameFile() doesn't work here since we just renamed @old_name.
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for (auto it = key_dirs_to_commit.begin(); it != key_dirs_to_commit.end(); it++) {
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if (*it == old_name) *it = new_name;
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}
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return true;
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}
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// Deletes a leftover upgraded key, if present. An upgraded key can be left
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// over if an update failed, or if we rebooted before committing the key in a
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// freak accident. Either way, we can re-upgrade the key if we need to.
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static void DeleteUpgradedKey(Keymaster& keymaster, const std::string& path) {
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if (pathExists(path)) {
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LOG(DEBUG) << "Deleting leftover upgraded key " << path;
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std::string blob;
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if (!android::base::ReadFileToString(path, &blob)) {
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LOG(WARNING) << "Failed to read leftover upgraded key " << path
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<< "; continuing anyway";
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} else if (!keymaster.deleteKey(blob)) {
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LOG(WARNING) << "Failed to delete leftover upgraded key " << path
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<< " from Keymaster; continuing anyway";
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}
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if (unlink(path.c_str()) != 0) {
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LOG(WARNING) << "Failed to unlink leftover upgraded key " << path
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<< "; continuing anyway";
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}
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}
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}
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// Begins a Keymaster operation using the key stored in |dir|.
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static KeymasterOperation BeginKeymasterOp(Keymaster& keymaster, const std::string& dir,
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const km::AuthorizationSet& keyParams,
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const km::AuthorizationSet& opParams,
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km::AuthorizationSet* outParams) {
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km::AuthorizationSet inParams(keyParams);
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inParams.append(opParams.begin(), opParams.end());
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auto blob_file = dir + "/" + kFn_keymaster_key_blob;
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auto upgraded_blob_file = dir + "/" + kFn_keymaster_key_blob_upgraded;
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std::lock_guard<std::mutex> lock(key_upgrade_lock);
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std::string blob;
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bool already_upgraded = IsKeyCommitPending(dir);
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if (already_upgraded) {
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LOG(DEBUG)
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<< blob_file
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<< " was already upgraded and is waiting to be committed; using the upgraded blob";
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if (!readFileToString(upgraded_blob_file, &blob)) return KeymasterOperation();
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} else {
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DeleteUpgradedKey(keymaster, upgraded_blob_file);
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if (!readFileToString(blob_file, &blob)) return KeymasterOperation();
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}
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auto opHandle = keymaster.begin(blob, inParams, outParams);
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if (!opHandle) return opHandle;
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// If key blob wasn't upgraded, nothing left to do.
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if (!opHandle.getUpgradedBlob()) return opHandle;
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if (already_upgraded) {
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LOG(ERROR) << "Unexpected case; already-upgraded key " << upgraded_blob_file
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<< " still requires upgrade";
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return KeymasterOperation();
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}
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LOG(INFO) << "Upgrading key: " << blob_file;
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if (!writeStringToFile(*opHandle.getUpgradedBlob(), upgraded_blob_file))
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return KeymasterOperation();
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if (cp_needsCheckpoint()) {
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LOG(INFO) << "Wrote upgraded key to " << upgraded_blob_file
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<< "; delaying commit due to checkpoint";
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ScheduleKeyCommit(dir);
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} else {
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if (!CommitUpgradedKey(keymaster, dir)) return KeymasterOperation();
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LOG(INFO) << "Key upgraded: " << blob_file;
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}
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return opHandle;
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}
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static bool encryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir,
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const km::AuthorizationSet& keyParams,
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const KeyBuffer& message, std::string* ciphertext) {
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km::AuthorizationSet opParams =
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km::AuthorizationSetBuilder()
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.Authorization(km::TAG_ROLLBACK_RESISTANCE)
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.Authorization(km::TAG_PURPOSE, km::KeyPurpose::ENCRYPT);
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km::AuthorizationSet outParams;
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auto opHandle = BeginKeymasterOp(keymaster, dir, keyParams, opParams, &outParams);
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if (!opHandle) return false;
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auto nonceBlob = outParams.GetTagValue(km::TAG_NONCE);
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if (!nonceBlob) {
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LOG(ERROR) << "GCM encryption but no nonce generated";
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return false;
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}
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// nonceBlob here is just a pointer into existing data, must not be freed
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std::string nonce(nonceBlob.value().get().begin(), nonceBlob.value().get().end());
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if (!checkSize("nonce", nonce.size(), GCM_NONCE_BYTES)) return false;
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std::string body;
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if (!opHandle.updateCompletely(message, &body)) return false;
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std::string mac;
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if (!opHandle.finish(&mac)) return false;
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if (!checkSize("mac", mac.size(), GCM_MAC_BYTES)) return false;
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*ciphertext = nonce + body + mac;
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return true;
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}
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static bool decryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir,
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const km::AuthorizationSet& keyParams,
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const std::string& ciphertext, KeyBuffer* message) {
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const std::string nonce = ciphertext.substr(0, GCM_NONCE_BYTES);
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auto bodyAndMac = ciphertext.substr(GCM_NONCE_BYTES);
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auto opParams = km::AuthorizationSetBuilder()
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.Authorization(km::TAG_NONCE, nonce)
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.Authorization(km::TAG_ROLLBACK_RESISTANCE)
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.Authorization(km::TAG_PURPOSE, km::KeyPurpose::DECRYPT);
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auto opHandle = BeginKeymasterOp(keymaster, dir, keyParams, opParams, nullptr);
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if (!opHandle) return false;
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if (!opHandle.updateCompletely(bodyAndMac, message)) return false;
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if (!opHandle.finish(nullptr)) return false;
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return true;
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}
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static std::string getStretching(const KeyAuthentication& auth) {
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if (auth.usesKeymaster()) {
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return kStretch_nopassword;
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} else {
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return kStretch_none;
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}
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}
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static bool stretchSecret(const std::string& stretching, const std::string& secret,
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std::string* stretched) {
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if (stretching == kStretch_nopassword) {
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if (!secret.empty()) {
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LOG(WARNING) << "Password present but stretching is nopassword";
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// Continue anyway
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}
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stretched->clear();
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} else if (stretching == kStretch_none) {
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*stretched = secret;
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} else {
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LOG(ERROR) << "Unknown stretching type: " << stretching;
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return false;
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}
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return true;
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}
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static bool generateAppId(const KeyAuthentication& auth, const std::string& stretching,
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const std::string& secdiscardable_hash, std::string* appId) {
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std::string stretched;
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if (!stretchSecret(stretching, auth.secret, &stretched)) return false;
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*appId = secdiscardable_hash + stretched;
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const std::lock_guard<std::mutex> scope_lock(storage_binding_info.guard);
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switch (storage_binding_info.state) {
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case StorageBindingInfo::State::UNINITIALIZED:
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storage_binding_info.state = StorageBindingInfo::State::NOT_USED;
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|
break;
|
|
case StorageBindingInfo::State::IN_USE:
|
|
appId->append(storage_binding_info.seed.begin(), storage_binding_info.seed.end());
|
|
break;
|
|
case StorageBindingInfo::State::NOT_USED:
|
|
// noop
|
|
break;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static void logOpensslError() {
|
|
LOG(ERROR) << "Openssl error: " << ERR_get_error();
|
|
}
|
|
|
|
static bool encryptWithoutKeymaster(const std::string& preKey, const KeyBuffer& plaintext,
|
|
std::string* ciphertext) {
|
|
std::string key;
|
|
hashWithPrefix(kHashPrefix_keygen, preKey, &key);
|
|
key.resize(AES_KEY_BYTES);
|
|
if (!readRandomBytesOrLog(GCM_NONCE_BYTES, ciphertext)) return false;
|
|
auto ctx = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>(
|
|
EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free);
|
|
if (!ctx) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (1 != EVP_EncryptInit_ex(ctx.get(), EVP_aes_256_gcm(), NULL,
|
|
reinterpret_cast<const uint8_t*>(key.data()),
|
|
reinterpret_cast<const uint8_t*>(ciphertext->data()))) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
ciphertext->resize(GCM_NONCE_BYTES + plaintext.size() + GCM_MAC_BYTES);
|
|
int outlen;
|
|
if (1 != EVP_EncryptUpdate(
|
|
ctx.get(), reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES),
|
|
&outlen, reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext.size())) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (outlen != static_cast<int>(plaintext.size())) {
|
|
LOG(ERROR) << "GCM ciphertext length should be " << plaintext.size() << " was " << outlen;
|
|
return false;
|
|
}
|
|
if (1 != EVP_EncryptFinal_ex(
|
|
ctx.get(),
|
|
reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES + plaintext.size()),
|
|
&outlen)) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (outlen != 0) {
|
|
LOG(ERROR) << "GCM EncryptFinal should be 0, was " << outlen;
|
|
return false;
|
|
}
|
|
if (1 != EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_GET_TAG, GCM_MAC_BYTES,
|
|
reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES +
|
|
plaintext.size()))) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static bool decryptWithoutKeymaster(const std::string& preKey, const std::string& ciphertext,
|
|
KeyBuffer* plaintext) {
|
|
if (ciphertext.size() < GCM_NONCE_BYTES + GCM_MAC_BYTES) {
|
|
LOG(ERROR) << "GCM ciphertext too small: " << ciphertext.size();
|
|
return false;
|
|
}
|
|
std::string key;
|
|
hashWithPrefix(kHashPrefix_keygen, preKey, &key);
|
|
key.resize(AES_KEY_BYTES);
|
|
auto ctx = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>(
|
|
EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free);
|
|
if (!ctx) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (1 != EVP_DecryptInit_ex(ctx.get(), EVP_aes_256_gcm(), NULL,
|
|
reinterpret_cast<const uint8_t*>(key.data()),
|
|
reinterpret_cast<const uint8_t*>(ciphertext.data()))) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
*plaintext = KeyBuffer(ciphertext.size() - GCM_NONCE_BYTES - GCM_MAC_BYTES);
|
|
int outlen;
|
|
if (1 != EVP_DecryptUpdate(ctx.get(), reinterpret_cast<uint8_t*>(&(*plaintext)[0]), &outlen,
|
|
reinterpret_cast<const uint8_t*>(ciphertext.data() + GCM_NONCE_BYTES),
|
|
plaintext->size())) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (outlen != static_cast<int>(plaintext->size())) {
|
|
LOG(ERROR) << "GCM plaintext length should be " << plaintext->size() << " was " << outlen;
|
|
return false;
|
|
}
|
|
if (1 != EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_TAG, GCM_MAC_BYTES,
|
|
const_cast<void*>(reinterpret_cast<const void*>(
|
|
ciphertext.data() + GCM_NONCE_BYTES + plaintext->size())))) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (1 != EVP_DecryptFinal_ex(ctx.get(),
|
|
reinterpret_cast<uint8_t*>(&(*plaintext)[0] + plaintext->size()),
|
|
&outlen)) {
|
|
logOpensslError();
|
|
return false;
|
|
}
|
|
if (outlen != 0) {
|
|
LOG(ERROR) << "GCM EncryptFinal should be 0, was " << outlen;
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool storeKey(const std::string& dir, const KeyAuthentication& auth, const KeyBuffer& key) {
|
|
if (TEMP_FAILURE_RETRY(mkdir(dir.c_str(), 0700)) == -1) {
|
|
PLOG(ERROR) << "key mkdir " << dir;
|
|
return false;
|
|
}
|
|
if (!writeStringToFile(kCurrentVersion, dir + "/" + kFn_version)) return false;
|
|
std::string secdiscardable_hash;
|
|
if (!createSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false;
|
|
std::string stretching = getStretching(auth);
|
|
if (!writeStringToFile(stretching, dir + "/" + kFn_stretching)) return false;
|
|
std::string appId;
|
|
if (!generateAppId(auth, stretching, secdiscardable_hash, &appId)) return false;
|
|
std::string encryptedKey;
|
|
if (auth.usesKeymaster()) {
|
|
Keymaster keymaster;
|
|
if (!keymaster) return false;
|
|
std::string kmKey;
|
|
if (!generateKeyStorageKey(keymaster, appId, &kmKey)) return false;
|
|
if (!writeStringToFile(kmKey, dir + "/" + kFn_keymaster_key_blob)) return false;
|
|
km::AuthorizationSet keyParams = beginParams(appId);
|
|
if (!encryptWithKeymasterKey(keymaster, dir, keyParams, key, &encryptedKey)) return false;
|
|
} else {
|
|
if (!encryptWithoutKeymaster(appId, key, &encryptedKey)) return false;
|
|
}
|
|
if (!writeStringToFile(encryptedKey, dir + "/" + kFn_encrypted_key)) return false;
|
|
if (!FsyncDirectory(dir)) return false;
|
|
return true;
|
|
}
|
|
|
|
bool storeKeyAtomically(const std::string& key_path, const std::string& tmp_path,
|
|
const KeyAuthentication& auth, const KeyBuffer& key) {
|
|
if (pathExists(key_path)) {
|
|
LOG(ERROR) << "Already exists, cannot create key at: " << key_path;
|
|
return false;
|
|
}
|
|
if (pathExists(tmp_path)) {
|
|
LOG(DEBUG) << "Already exists, destroying: " << tmp_path;
|
|
destroyKey(tmp_path); // May be partially created so ignore errors
|
|
}
|
|
if (!storeKey(tmp_path, auth, key)) return false;
|
|
|
|
if (!RenameKeyDir(tmp_path, key_path)) {
|
|
PLOG(ERROR) << "Unable to move new key to location: " << key_path;
|
|
return false;
|
|
}
|
|
if (!FsyncParentDirectory(key_path)) return false;
|
|
LOG(DEBUG) << "Created key: " << key_path;
|
|
return true;
|
|
}
|
|
|
|
bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffer* key) {
|
|
std::string version;
|
|
if (!readFileToString(dir + "/" + kFn_version, &version)) return false;
|
|
if (version != kCurrentVersion) {
|
|
LOG(ERROR) << "Version mismatch, expected " << kCurrentVersion << " got " << version;
|
|
return false;
|
|
}
|
|
std::string secdiscardable_hash;
|
|
if (!readSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false;
|
|
std::string stretching;
|
|
if (!readFileToString(dir + "/" + kFn_stretching, &stretching)) return false;
|
|
std::string appId;
|
|
if (!generateAppId(auth, stretching, secdiscardable_hash, &appId)) return false;
|
|
std::string encryptedMessage;
|
|
if (!readFileToString(dir + "/" + kFn_encrypted_key, &encryptedMessage)) return false;
|
|
if (auth.usesKeymaster()) {
|
|
Keymaster keymaster;
|
|
if (!keymaster) return false;
|
|
km::AuthorizationSet keyParams = beginParams(appId);
|
|
if (!decryptWithKeymasterKey(keymaster, dir, keyParams, encryptedMessage, key))
|
|
return false;
|
|
} else {
|
|
if (!decryptWithoutKeymaster(appId, encryptedMessage, key)) return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static bool DeleteKeymasterKey(const std::string& blob_file) {
|
|
std::string blob;
|
|
if (!readFileToString(blob_file, &blob)) return false;
|
|
Keymaster keymaster;
|
|
if (!keymaster) return false;
|
|
LOG(DEBUG) << "Deleting key " << blob_file << " from Keymaster";
|
|
if (!keymaster.deleteKey(blob)) return false;
|
|
return true;
|
|
}
|
|
|
|
bool runSecdiscardSingle(const std::string& file) {
|
|
if (ForkExecvp(std::vector<std::string>{kSecdiscardPath, "--", file}) != 0) {
|
|
LOG(ERROR) << "secdiscard failed";
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static bool recursiveDeleteKey(const std::string& dir) {
|
|
if (ForkExecvp(std::vector<std::string>{kRmPath, "-rf", dir}) != 0) {
|
|
LOG(ERROR) << "recursive delete failed";
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool destroyKey(const std::string& dir) {
|
|
bool success = true;
|
|
|
|
CancelPendingKeyCommit(dir);
|
|
|
|
auto secdiscard_cmd = std::vector<std::string>{
|
|
kSecdiscardPath,
|
|
"--",
|
|
dir + "/" + kFn_encrypted_key,
|
|
dir + "/" + kFn_secdiscardable,
|
|
};
|
|
// Try each thing, even if previous things failed.
|
|
|
|
for (auto& fn : {kFn_keymaster_key_blob, kFn_keymaster_key_blob_upgraded}) {
|
|
auto blob_file = dir + "/" + fn;
|
|
if (pathExists(blob_file)) {
|
|
success &= DeleteKeymasterKey(blob_file);
|
|
secdiscard_cmd.push_back(blob_file);
|
|
}
|
|
}
|
|
if (ForkExecvp(secdiscard_cmd) != 0) {
|
|
LOG(ERROR) << "secdiscard failed";
|
|
success = false;
|
|
}
|
|
success &= recursiveDeleteKey(dir);
|
|
return success;
|
|
}
|
|
|
|
bool setKeyStorageBindingSeed(const std::vector<uint8_t>& seed) {
|
|
const std::lock_guard<std::mutex> scope_lock(storage_binding_info.guard);
|
|
switch (storage_binding_info.state) {
|
|
case StorageBindingInfo::State::UNINITIALIZED:
|
|
storage_binding_info.state = StorageBindingInfo::State::IN_USE;
|
|
storage_binding_info.seed = seed;
|
|
return true;
|
|
case StorageBindingInfo::State::IN_USE:
|
|
LOG(ERROR) << "key storage binding seed already set";
|
|
return false;
|
|
case StorageBindingInfo::State::NOT_USED:
|
|
LOG(ERROR) << "key storage already in use without binding";
|
|
return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
} // namespace vold
|
|
} // namespace android
|