b615f3beac
On the first boot after an upgrade, ensure that any Keystore key deletions triggered by fscrypt_set_user_key_protection() are deferred until the userdata filesystem checkpoint is committed, so that the system doesn't end up in a bad state if the checkpoint is rolled back. Test: see I77d30f9be57de7b7c4818680732331549ecb73c8 Bug: 232452368 Ignore-AOSP-First: depends on other changes in internal master Change-Id: I59b758bc13b7a2ae270f1a6c409affe2eb61119c
699 lines
27 KiB
C++
699 lines
27 KiB
C++
/*
|
|
* Copyright (C) 2016 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 "KeyStorage.h"
|
|
|
|
#include "Checkpoint.h"
|
|
#include "Keystore.h"
|
|
#include "Utils.h"
|
|
|
|
#include <algorithm>
|
|
#include <memory>
|
|
#include <mutex>
|
|
#include <vector>
|
|
|
|
#include <errno.h>
|
|
#include <stdio.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/types.h>
|
|
#include <sys/wait.h>
|
|
#include <unistd.h>
|
|
|
|
#include <openssl/err.h>
|
|
#include <openssl/evp.h>
|
|
#include <openssl/sha.h>
|
|
|
|
#include <android-base/file.h>
|
|
#include <android-base/logging.h>
|
|
#include <android-base/properties.h>
|
|
#include <android-base/unique_fd.h>
|
|
|
|
#include <cutils/properties.h>
|
|
|
|
namespace android {
|
|
namespace vold {
|
|
|
|
const KeyAuthentication kEmptyAuthentication{""};
|
|
|
|
static constexpr size_t AES_KEY_BYTES = 32;
|
|
static constexpr size_t GCM_NONCE_BYTES = 12;
|
|
static constexpr size_t GCM_MAC_BYTES = 16;
|
|
static constexpr size_t SECDISCARDABLE_BYTES = 1 << 14;
|
|
|
|
static const char* kCurrentVersion = "1";
|
|
static const char* kRmPath = "/system/bin/rm";
|
|
static const char* kSecdiscardPath = "/system/bin/secdiscard";
|
|
static const char* kHashPrefix_secdiscardable = "Android secdiscardable SHA512";
|
|
static const char* kHashPrefix_keygen = "Android key wrapping key generation SHA512";
|
|
static const char* kFn_encrypted_key = "encrypted_key";
|
|
static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
|
|
static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
|
|
static const char* kFn_secdiscardable = "secdiscardable";
|
|
static const char* kFn_version = "version";
|
|
// Note: old key directories may contain a file named "stretching".
|
|
|
|
namespace {
|
|
|
|
// Storage binding info for ensuring key encryption keys include a
|
|
// platform-provided seed in their derivation.
|
|
struct StorageBindingInfo {
|
|
enum class State {
|
|
UNINITIALIZED,
|
|
IN_USE, // key storage keys are bound to seed
|
|
NOT_USED, // key storage keys are NOT bound to seed
|
|
};
|
|
|
|
// Binding seed mixed into all key storage keys.
|
|
std::vector<uint8_t> seed;
|
|
|
|
// State tracker for the key storage key binding.
|
|
State state = State::UNINITIALIZED;
|
|
|
|
std::mutex guard;
|
|
};
|
|
|
|
// Never freed as the dtor is non-trivial.
|
|
StorageBindingInfo& storage_binding_info = *new StorageBindingInfo;
|
|
|
|
} // namespace
|
|
|
|
static bool checkSize(const std::string& kind, size_t actual, size_t expected) {
|
|
if (actual != expected) {
|
|
LOG(ERROR) << "Wrong number of bytes in " << kind << ", expected " << expected << " got "
|
|
<< actual;
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static void hashWithPrefix(char const* prefix, const std::string& tohash, std::string* res) {
|
|
SHA512_CTX c;
|
|
|
|
SHA512_Init(&c);
|
|
// Personalise the hashing by introducing a fixed prefix.
|
|
// Hashing applications should use personalization except when there is a
|
|
// specific reason not to; see section 4.11 of https://www.schneier.com/skein1.3.pdf
|
|
std::string hashingPrefix = prefix;
|
|
hashingPrefix.resize(SHA512_CBLOCK);
|
|
SHA512_Update(&c, hashingPrefix.data(), hashingPrefix.size());
|
|
SHA512_Update(&c, tohash.data(), tohash.size());
|
|
res->assign(SHA512_DIGEST_LENGTH, '\0');
|
|
SHA512_Final(reinterpret_cast<uint8_t*>(&(*res)[0]), &c);
|
|
}
|
|
|
|
static bool generateKeyStorageKey(Keystore& keystore, const std::string& appId, std::string* key) {
|
|
auto paramBuilder = km::AuthorizationSetBuilder()
|
|
.AesEncryptionKey(AES_KEY_BYTES * 8)
|
|
.GcmModeMinMacLen(GCM_MAC_BYTES * 8)
|
|
.Authorization(km::TAG_APPLICATION_ID, appId)
|
|
.Authorization(km::TAG_NO_AUTH_REQUIRED);
|
|
LOG(DEBUG) << "Generating \"key storage\" key";
|
|
auto paramsWithRollback = paramBuilder;
|
|
paramsWithRollback.Authorization(km::TAG_ROLLBACK_RESISTANCE);
|
|
|
|
if (!keystore.generateKey(paramsWithRollback, key)) {
|
|
LOG(WARNING) << "Failed to generate rollback-resistant key. This is expected if keystore "
|
|
"doesn't support rollback resistance. Falling back to "
|
|
"non-rollback-resistant key.";
|
|
if (!keystore.generateKey(paramBuilder, key)) return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool generateWrappedStorageKey(KeyBuffer* key) {
|
|
Keystore keystore;
|
|
if (!keystore) return false;
|
|
std::string key_temp;
|
|
auto paramBuilder = km::AuthorizationSetBuilder().AesEncryptionKey(AES_KEY_BYTES * 8);
|
|
paramBuilder.Authorization(km::TAG_STORAGE_KEY);
|
|
if (!keystore.generateKey(paramBuilder, &key_temp)) return false;
|
|
*key = KeyBuffer(key_temp.size());
|
|
memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
|
|
return true;
|
|
}
|
|
|
|
bool exportWrappedStorageKey(const KeyBuffer& ksKey, KeyBuffer* key) {
|
|
Keystore keystore;
|
|
if (!keystore) return false;
|
|
std::string key_temp;
|
|
|
|
if (!keystore.exportKey(ksKey, &key_temp)) return false;
|
|
*key = KeyBuffer(key_temp.size());
|
|
memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
|
|
return true;
|
|
}
|
|
|
|
static km::AuthorizationSet beginParams(const std::string& appId) {
|
|
return km::AuthorizationSetBuilder()
|
|
.GcmModeMacLen(GCM_MAC_BYTES * 8)
|
|
.Authorization(km::TAG_APPLICATION_ID, appId);
|
|
}
|
|
|
|
static bool readFileToString(const std::string& filename, std::string* result) {
|
|
if (!android::base::ReadFileToString(filename, result)) {
|
|
PLOG(ERROR) << "Failed to read from " << filename;
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static bool readRandomBytesOrLog(size_t count, std::string* out) {
|
|
auto status = ReadRandomBytes(count, *out);
|
|
if (status != OK) {
|
|
LOG(ERROR) << "Random read failed with status: " << status;
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool createSecdiscardable(const std::string& filename, std::string* hash) {
|
|
std::string secdiscardable;
|
|
if (!readRandomBytesOrLog(SECDISCARDABLE_BYTES, &secdiscardable)) return false;
|
|
if (!writeStringToFile(secdiscardable, filename)) return false;
|
|
hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash);
|
|
return true;
|
|
}
|
|
|
|
bool readSecdiscardable(const std::string& filename, std::string* hash) {
|
|
if (pathExists(filename)) {
|
|
std::string secdiscardable;
|
|
if (!readFileToString(filename, &secdiscardable)) return false;
|
|
hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash);
|
|
} else {
|
|
*hash = "";
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static std::mutex key_upgrade_lock;
|
|
|
|
// List of key directories that have had their Keystore key upgraded during
|
|
// this boot and written to "keymaster_key_blob_upgraded", but replacing the old
|
|
// key was delayed due to an active checkpoint. Protected by key_upgrade_lock.
|
|
// A directory can be in this list at most once.
|
|
static std::vector<std::string> key_dirs_to_commit;
|
|
|
|
// Replaces |dir|/keymaster_key_blob with |dir|/keymaster_key_blob_upgraded and
|
|
// deletes the old key from Keystore.
|
|
static bool CommitUpgradedKey(Keystore& keystore, const std::string& dir) {
|
|
auto blob_file = dir + "/" + kFn_keymaster_key_blob;
|
|
auto upgraded_blob_file = dir + "/" + kFn_keymaster_key_blob_upgraded;
|
|
|
|
std::string blob;
|
|
if (!readFileToString(blob_file, &blob)) return false;
|
|
|
|
if (rename(upgraded_blob_file.c_str(), blob_file.c_str()) != 0) {
|
|
PLOG(ERROR) << "Failed to rename " << upgraded_blob_file << " to " << blob_file;
|
|
return false;
|
|
}
|
|
// Ensure that the rename is persisted before deleting the Keystore key.
|
|
if (!FsyncDirectory(dir)) return false;
|
|
|
|
if (!keystore || !keystore.deleteKey(blob)) {
|
|
LOG(WARNING) << "Failed to delete old key " << blob_file
|
|
<< " from Keystore; continuing anyway";
|
|
// Continue on, but the space in Keystore used by the old key won't be freed.
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void DeferredCommitKeystoreKeys() {
|
|
LOG(INFO) << "Committing upgraded Keystore keys";
|
|
Keystore keystore;
|
|
if (!keystore) {
|
|
LOG(ERROR) << "Failed to open Keystore; old keys won't be deleted from Keystore";
|
|
// Continue on, but the space in Keystore used by the old keys won't be freed.
|
|
}
|
|
std::lock_guard<std::mutex> lock(key_upgrade_lock);
|
|
for (auto& dir : key_dirs_to_commit) {
|
|
LOG(INFO) << "Committing upgraded Keystore key for " << dir;
|
|
CommitUpgradedKey(keystore, dir);
|
|
}
|
|
key_dirs_to_commit.clear();
|
|
LOG(INFO) << "Done committing upgraded Keystore keys";
|
|
}
|
|
|
|
// Returns true if the Keystore key in |dir| has already been upgraded and is
|
|
// pending being committed. Assumes that key_upgrade_lock is held.
|
|
static bool IsKeyCommitPending(const std::string& dir) {
|
|
for (const auto& dir_to_commit : key_dirs_to_commit) {
|
|
if (IsSameFile(dir, dir_to_commit)) return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Schedules the upgraded Keystore key in |dir| to be committed later. Assumes
|
|
// that key_upgrade_lock is held and that a commit isn't already pending for the
|
|
// directory.
|
|
static void ScheduleKeyCommit(const std::string& dir) {
|
|
key_dirs_to_commit.push_back(dir);
|
|
}
|
|
|
|
static void CancelPendingKeyCommit(const std::string& dir) {
|
|
std::lock_guard<std::mutex> lock(key_upgrade_lock);
|
|
for (auto it = key_dirs_to_commit.begin(); it != key_dirs_to_commit.end(); it++) {
|
|
if (IsSameFile(*it, dir)) {
|
|
LOG(DEBUG) << "Cancelling pending commit of upgraded key " << dir
|
|
<< " because it is being destroyed";
|
|
key_dirs_to_commit.erase(it);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
bool RenameKeyDir(const std::string& old_name, const std::string& new_name) {
|
|
std::lock_guard<std::mutex> lock(key_upgrade_lock);
|
|
|
|
// Find the entry in key_dirs_to_commit (if any) for this directory so that
|
|
// we can update it if the rename succeeds. We don't allow duplicates in
|
|
// this list, so there can be at most one such entry.
|
|
auto it = key_dirs_to_commit.begin();
|
|
for (; it != key_dirs_to_commit.end(); it++) {
|
|
if (IsSameFile(old_name, *it)) break;
|
|
}
|
|
|
|
if (rename(old_name.c_str(), new_name.c_str()) != 0) {
|
|
PLOG(ERROR) << "Failed to rename key directory \"" << old_name << "\" to \"" << new_name
|
|
<< "\"";
|
|
return false;
|
|
}
|
|
|
|
if (it != key_dirs_to_commit.end()) *it = new_name;
|
|
|
|
return true;
|
|
}
|
|
|
|
// Deletes a leftover upgraded key, if present. An upgraded key can be left
|
|
// over if an update failed, or if we rebooted before committing the key in a
|
|
// freak accident. Either way, we can re-upgrade the key if we need to.
|
|
static void DeleteUpgradedKey(Keystore& keystore, const std::string& path) {
|
|
if (pathExists(path)) {
|
|
LOG(DEBUG) << "Deleting leftover upgraded key " << path;
|
|
std::string blob;
|
|
if (!android::base::ReadFileToString(path, &blob)) {
|
|
LOG(WARNING) << "Failed to read leftover upgraded key " << path
|
|
<< "; continuing anyway";
|
|
} else if (!keystore.deleteKey(blob)) {
|
|
LOG(WARNING) << "Failed to delete leftover upgraded key " << path
|
|
<< " from Keystore; continuing anyway";
|
|
}
|
|
if (unlink(path.c_str()) != 0) {
|
|
LOG(WARNING) << "Failed to unlink leftover upgraded key " << path
|
|
<< "; continuing anyway";
|
|
}
|
|
}
|
|
}
|
|
|
|
// Begins a Keystore operation using the key stored in |dir|.
|
|
static KeystoreOperation BeginKeystoreOp(Keystore& keystore, const std::string& dir,
|
|
const km::AuthorizationSet& keyParams,
|
|
const km::AuthorizationSet& opParams,
|
|
km::AuthorizationSet* outParams) {
|
|
km::AuthorizationSet inParams(keyParams);
|
|
inParams.append(opParams.begin(), opParams.end());
|
|
|
|
auto blob_file = dir + "/" + kFn_keymaster_key_blob;
|
|
auto upgraded_blob_file = dir + "/" + kFn_keymaster_key_blob_upgraded;
|
|
|
|
std::lock_guard<std::mutex> lock(key_upgrade_lock);
|
|
|
|
std::string blob;
|
|
bool already_upgraded = IsKeyCommitPending(dir);
|
|
if (already_upgraded) {
|
|
LOG(DEBUG)
|
|
<< blob_file
|
|
<< " was already upgraded and is waiting to be committed; using the upgraded blob";
|
|
if (!readFileToString(upgraded_blob_file, &blob)) return KeystoreOperation();
|
|
} else {
|
|
DeleteUpgradedKey(keystore, upgraded_blob_file);
|
|
if (!readFileToString(blob_file, &blob)) return KeystoreOperation();
|
|
}
|
|
|
|
auto opHandle = keystore.begin(blob, inParams, outParams);
|
|
if (!opHandle) return opHandle;
|
|
|
|
// If key blob wasn't upgraded, nothing left to do.
|
|
if (!opHandle.getUpgradedBlob()) return opHandle;
|
|
|
|
if (already_upgraded) {
|
|
LOG(ERROR) << "Unexpected case; already-upgraded key " << upgraded_blob_file
|
|
<< " still requires upgrade";
|
|
return KeystoreOperation();
|
|
}
|
|
LOG(INFO) << "Upgrading key: " << blob_file;
|
|
if (!writeStringToFile(*opHandle.getUpgradedBlob(), upgraded_blob_file))
|
|
return KeystoreOperation();
|
|
if (cp_needsCheckpoint()) {
|
|
LOG(INFO) << "Wrote upgraded key to " << upgraded_blob_file
|
|
<< "; delaying commit due to checkpoint";
|
|
ScheduleKeyCommit(dir);
|
|
} else {
|
|
if (!CommitUpgradedKey(keystore, dir)) return KeystoreOperation();
|
|
LOG(INFO) << "Key upgraded: " << blob_file;
|
|
}
|
|
return opHandle;
|
|
}
|
|
|
|
static bool encryptWithKeystoreKey(Keystore& keystore, const std::string& dir,
|
|
const km::AuthorizationSet& keyParams, const KeyBuffer& message,
|
|
std::string* ciphertext) {
|
|
km::AuthorizationSet opParams =
|
|
km::AuthorizationSetBuilder().Authorization(km::TAG_PURPOSE, km::KeyPurpose::ENCRYPT);
|
|
km::AuthorizationSet outParams;
|
|
auto opHandle = BeginKeystoreOp(keystore, dir, keyParams, opParams, &outParams);
|
|
if (!opHandle) return false;
|
|
auto nonceBlob = outParams.GetTagValue(km::TAG_NONCE);
|
|
if (!nonceBlob) {
|
|
LOG(ERROR) << "GCM encryption but no nonce generated";
|
|
return false;
|
|
}
|
|
// nonceBlob here is just a pointer into existing data, must not be freed
|
|
std::string nonce(nonceBlob.value().get().begin(), nonceBlob.value().get().end());
|
|
if (!checkSize("nonce", nonce.size(), GCM_NONCE_BYTES)) return false;
|
|
std::string body;
|
|
if (!opHandle.updateCompletely(message, &body)) return false;
|
|
|
|
std::string mac;
|
|
if (!opHandle.finish(&mac)) return false;
|
|
if (!checkSize("mac", mac.size(), GCM_MAC_BYTES)) return false;
|
|
*ciphertext = nonce + body + mac;
|
|
return true;
|
|
}
|
|
|
|
static bool decryptWithKeystoreKey(Keystore& keystore, const std::string& dir,
|
|
const km::AuthorizationSet& keyParams,
|
|
const std::string& ciphertext, KeyBuffer* message) {
|
|
const std::string nonce = ciphertext.substr(0, GCM_NONCE_BYTES);
|
|
auto bodyAndMac = ciphertext.substr(GCM_NONCE_BYTES);
|
|
auto opParams = km::AuthorizationSetBuilder()
|
|
.Authorization(km::TAG_NONCE, nonce)
|
|
.Authorization(km::TAG_PURPOSE, km::KeyPurpose::DECRYPT);
|
|
auto opHandle = BeginKeystoreOp(keystore, dir, keyParams, opParams, nullptr);
|
|
if (!opHandle) return false;
|
|
if (!opHandle.updateCompletely(bodyAndMac, message)) return false;
|
|
if (!opHandle.finish(nullptr)) return false;
|
|
return true;
|
|
}
|
|
|
|
static std::string generateAppId(const KeyAuthentication& auth,
|
|
const std::string& secdiscardable_hash) {
|
|
std::string appId = secdiscardable_hash + auth.secret;
|
|
|
|
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::NOT_USED;
|
|
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 appId;
|
|
}
|
|
|
|
static void logOpensslError() {
|
|
LOG(ERROR) << "Openssl error: " << ERR_get_error();
|
|
}
|
|
|
|
static bool encryptWithoutKeystore(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 decryptWithoutKeystore(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;
|
|
}
|
|
|
|
// Creates a directory at the given path |dir| and stores |key| in it, in such a
|
|
// way that it can only be retrieved via Keystore (if no secret is given in
|
|
// |auth|) or with the given secret (if a secret is given in |auth|). In the
|
|
// former case, an attempt is made to make the key securely deletable. In the
|
|
// latter case, secure deletion is expected to be handled at a higher level.
|
|
//
|
|
// If a storage binding seed has been set, then the storage binding seed will be
|
|
// required to retrieve the key as well.
|
|
static 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 (auth.usesKeystore() &&
|
|
!createSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash))
|
|
return false;
|
|
std::string appId = generateAppId(auth, secdiscardable_hash);
|
|
std::string encryptedKey;
|
|
if (auth.usesKeystore()) {
|
|
Keystore keystore;
|
|
if (!keystore) return false;
|
|
std::string ksKey;
|
|
if (!generateKeyStorageKey(keystore, appId, &ksKey)) return false;
|
|
if (!writeStringToFile(ksKey, dir + "/" + kFn_keymaster_key_blob)) return false;
|
|
km::AuthorizationSet keyParams = beginParams(appId);
|
|
if (!encryptWithKeystoreKey(keystore, dir, keyParams, key, &encryptedKey)) {
|
|
LOG(ERROR) << "encryptWithKeystoreKey failed";
|
|
return false;
|
|
}
|
|
} else {
|
|
if (!encryptWithoutKeystore(appId, key, &encryptedKey)) {
|
|
LOG(ERROR) << "encryptWithoutKeystore failed";
|
|
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)) return false;
|
|
|
|
if (!FsyncParentDirectory(key_path)) return false;
|
|
LOG(DEBUG) << "Stored 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 appId = generateAppId(auth, secdiscardable_hash);
|
|
std::string encryptedMessage;
|
|
if (!readFileToString(dir + "/" + kFn_encrypted_key, &encryptedMessage)) return false;
|
|
if (auth.usesKeystore()) {
|
|
Keystore keystore;
|
|
if (!keystore) return false;
|
|
km::AuthorizationSet keyParams = beginParams(appId);
|
|
if (!decryptWithKeystoreKey(keystore, dir, keyParams, encryptedMessage, key)) {
|
|
LOG(ERROR) << "decryptWithKeystoreKey failed";
|
|
return false;
|
|
}
|
|
} else {
|
|
if (!decryptWithoutKeystore(appId, encryptedMessage, key)) {
|
|
LOG(ERROR) << "decryptWithoutKeystore failed";
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static bool DeleteKeystoreKey(const std::string& blob_file) {
|
|
std::string blob;
|
|
if (!readFileToString(blob_file, &blob)) return false;
|
|
Keystore keystore;
|
|
if (!keystore) return false;
|
|
LOG(DEBUG) << "Deleting key " << blob_file << " from Keystore";
|
|
if (!keystore.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 &= DeleteKeystoreKey(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;
|
|
android::base::SetProperty("vold.storage_seed_bound", "1");
|
|
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
|