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/*
* 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 "MetadataCrypt.h"
#include "KeyBuffer.h"
#include <algorithm>
#include <string>
#include <thread>
#include <vector>
#include <fcntl.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/unique_fd.h>
#include <cutils/fs.h>
#include <fs_mgr.h>
#include <libdm/dm.h>
#include "Checkpoint.h"
#include "EncryptInplace.h"
#include "KeyStorage.h"
#include "KeyUtil.h"
#include "Keymaster.h"
#include "Utils.h"
#include "VoldUtil.h"
#define TABLE_LOAD_RETRIES 10
using android::fs_mgr::FstabEntry;
using android::fs_mgr::GetEntryForMountPoint;
using android::vold::KeyBuffer;
using namespace android::dm;
static const std::string kDmNameUserdata = "userdata";
static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
// fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
// partitions in the fsck domain.
if (setexeccon(android::vold::sFsckContext)) {
PLOG(ERROR) << "Failed to setexeccon";
return false;
}
auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
const_cast<char*>(blk_device), nullptr,
android::vold::cp_needsCheckpoint());
if (setexeccon(nullptr)) {
PLOG(ERROR) << "Failed to clear setexeccon";
return false;
}
if (mount_rc != 0) {
LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc;
return false;
}
LOG(DEBUG) << "Mounted " << mount_point;
return true;
}
namespace android {
namespace vold {
// Note: It is possible to orphan a key if it is removed before deleting
// Update this once keymaster APIs change, and we have a proper commit.
static void commit_key(const std::string& dir) {
while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
LOG(ERROR) << "Wait for boot timed out";
}
Keymaster keymaster;
auto keyPath = dir + "/" + kFn_keymaster_key_blob;
auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
std::string key;
if (!android::base::ReadFileToString(keyPath, &key)) {
LOG(ERROR) << "Failed to read old key: " << dir;
return;
}
if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
return;
}
if (!keymaster.deleteKey(key)) {
LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
}
LOG(INFO) << "Old Key deleted: " << dir;
}
static bool read_key(const FstabEntry& data_rec, bool create_if_absent, KeyBuffer* key) {
if (data_rec.key_dir.empty()) {
LOG(ERROR) << "Failed to get key_dir";
return false;
}
std::string key_dir = data_rec.key_dir;
std::string sKey;
auto dir = key_dir + "/key";
LOG(DEBUG) << "key_dir/key: " << dir;
if (fs_mkdirs(dir.c_str(), 0700)) {
PLOG(ERROR) << "Creating directories: " << dir;
return false;
}
auto temp = key_dir + "/tmp";
auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
/* If we have a leftover upgraded key, delete it.
* We either failed an update and must return to the old key,
* or we rebooted before commiting the keys in a freak accident.
* Either way, we can re-upgrade the key if we need to.
*/
Keymaster keymaster;
if (pathExists(newKeyPath)) {
if (!android::base::ReadFileToString(newKeyPath, &sKey))
LOG(ERROR) << "Failed to read old key: " << dir;
else if (!keymaster.deleteKey(sKey))
LOG(ERROR) << "Old key deletion failed, continuing anyway: " << dir;
else
unlink(newKeyPath.c_str());
}
bool needs_cp = cp_needsCheckpoint();
if (!android::vold::retrieveKey(create_if_absent, dir, temp, key, needs_cp)) return false;
if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
return true;
}
} // namespace vold
} // namespace android
static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {
PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
return false;
}
return true;
}
static bool create_crypto_blk_dev(const std::string& dm_name, uint64_t nr_sec,
const std::string& real_blkdev, const KeyBuffer& key,
std::string* crypto_blkdev, bool set_dun) {
auto& dm = DeviceMapper::Instance();
KeyBuffer hex_key_buffer;
if (android::vold::StrToHex(key, hex_key_buffer) != android::OK) {
LOG(ERROR) << "Failed to turn key to hex";
return false;
}
std::string hex_key(hex_key_buffer.data(), hex_key_buffer.size());
DmTable table;
table.Emplace<DmTargetDefaultKey>(0, nr_sec, "AES-256-XTS", hex_key, real_blkdev, 0, set_dun);
for (int i = 0;; i++) {
if (dm.CreateDevice(dm_name, table)) {
break;
}
if (i + 1 >= TABLE_LOAD_RETRIES) {
LOG(ERROR) << "Could not create default-key device " << dm_name;
return false;
}
PLOG(INFO) << "Could not create default-key device, retrying";
usleep(500000);
}
if (!dm.GetDmDevicePathByName(dm_name, crypto_blkdev)) {
LOG(ERROR) << "Cannot retrieve default-key device status " << dm_name;
return false;
}
return true;
}
bool fscrypt_mount_metadata_encrypted(const std::string& blk_device, const std::string& mount_point,
bool needs_encrypt) {
LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
if (encrypted_state != "" && encrypted_state != "encrypted") {
LOG(DEBUG) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
return false;
}
auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
if (!data_rec) {
LOG(ERROR) << "Failed to get data_rec";
return false;
}
KeyBuffer key;
if (!read_key(*data_rec, needs_encrypt, &key)) return false;
uint64_t nr_sec;
if (!get_number_of_sectors(data_rec->blk_device, &nr_sec)) return false;
bool set_dun = android::base::GetBoolProperty("ro.crypto.set_dun", false);
if (!set_dun && data_rec->fs_mgr_flags.checkpoint_blk) {
LOG(ERROR) << "Block checkpoints and metadata encryption require setdun option!";
return false;
}
std::string crypto_blkdev;
if (!create_crypto_blk_dev(kDmNameUserdata, nr_sec, blk_device, key, &crypto_blkdev, set_dun))
return false;
// FIXME handle the corrupt case
if (needs_encrypt) {
LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
off64_t size_already_done = 0;
auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), blk_device.data(), nr_sec,
&size_already_done, nr_sec, 0, false);
if (rc != 0) {
LOG(ERROR) << "Inplace crypto failed with code: " << rc;
return false;
}
if (static_cast<uint64_t>(size_already_done) != nr_sec) {
LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done;
return false;
}
LOG(INFO) << "Inplace encryption complete";
}
LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;
mount_via_fs_mgr(data_rec->mount_point.c_str(), crypto_blkdev.c_str());
return true;
}
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