/*

* 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 "FsCrypt.h"

#include "Checkpoint.h"

#include "KeyStorage.h"

#include "KeyUtil.h"

#include "Utils.h"

#include "VoldUtil.h"

#include <algorithm>

#include <filesystem>

#include <map>

#include <string>

#include <dirent.h>

#include <errno.h>

#include <fcntl.h>

#include <limits.h>

#include <sys/mount.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/utsname.h>

#include <unistd.h>

#include <private/android_filesystem_config.h>

#include <private/android_projectid_config.h>

#include "android/os/IVold.h"

#include <cutils/fs.h>

#include <cutils/properties.h>

#include <fscrypt/fscrypt.h>

#include <libdm/dm.h>

#include <android-base/file.h>

#include <android-base/logging.h>

#include <android-base/properties.h>

#include <android-base/stringprintf.h>

#include <android-base/strings.h>

#include <android-base/unique_fd.h>

#include <android/os/casefoldingremover/ICasefoldingRemover.h>

#include <binder/IServiceManager.h>

using android::defaultServiceManager;

using android::interface_cast;

using android::String16;

using android::base::Basename;

using android::base::Realpath;

using android::base::StartsWith;

using android::base::StringPrintf;

using android::fs_mgr::GetEntryForMountPoint;

using android::os::casefoldingremover::ICasefoldingRemover;

using android::vold::BuildDataPath;

using android::vold::IsDotOrDotDot;

using android::vold::IsFilesystemSupported;

using android::vold::kEmptyAuthentication;

using android::vold::KeyBuffer;

using android::vold::KeyGeneration;

using android::vold::retrieveKey;

using android::vold::retrieveOrGenerateKey;

using android::vold::SetDefaultAcl;

using android::vold::SetQuotaInherit;

using android::vold::SetQuotaProjectId;

using namespace android::fscrypt;

using namespace android::dm;

namespace {

const std::string device_key_dir = std::string() + DATA_MNT_POINT + fscrypt_unencrypted_folder;

const std::string device_key_path = device_key_dir + "/key";

const std::string device_key_temp = device_key_dir + "/temp";

const std::string user_key_dir = std::string() + DATA_MNT_POINT + "/misc/vold/user_keys";

const std::string user_key_temp = user_key_dir + "/temp";

const std::string prepare_subdirs_path = "/system/bin/vold_prepare_subdirs";

const std::string systemwide_volume_key_dir =

std::string() + DATA_MNT_POINT + "/misc/vold/volume_keys";

const std::string data_data_dir = std::string() + DATA_MNT_POINT + "/data";

const std::string data_user_0_dir = std::string() + DATA_MNT_POINT + "/user/0";

const std::string media_obb_dir = std::string() + DATA_MNT_POINT + "/media/obb";

// The file encryption options to use on the /data filesystem

EncryptionOptions s_data_options;

// Some users are ephemeral; don't try to store or wipe their keys on disk.

std::set<userid_t> s_ephemeral_users;

// New CE keys that haven't been committed to disk yet

std::map<userid_t, KeyBuffer> s_new_ce_keys;

// CE key fixation operations that have been deferred to checkpoint commit

std::map<std::string, std::string> s_deferred_fixations;

// The system DE encryption policy

EncryptionPolicy s_device_policy;

// Struct that holds the EncryptionPolicy for each CE or DE key that is currently installed

// (added to the kernel) for a particular user

struct UserPolicies {

// Internal storage policy. Exists whenever a user's UserPolicies exists at all, and used

// instead of a map entry keyed by an empty UUID to make this invariant explicit.

EncryptionPolicy internal;

// Adoptable storage policies, indexed by (nonempty) volume UUID

std::map<std::string, EncryptionPolicy> adoptable;

};

// The currently installed CE and DE keys for each user. Protected by VolumeManager::mCryptLock.

std::map<userid_t, UserPolicies> s_ce_policies;

std::map<userid_t, UserPolicies> s_de_policies;

} // namespace

// Returns KeyGeneration suitable for key as described in EncryptionOptions

static KeyGeneration makeGen(const EncryptionOptions& options) {

if (options.version == 0) {

LOG(ERROR) << "EncryptionOptions not initialized";

return android::vold::neverGen();

}

return KeyGeneration{FSCRYPT_MAX_KEY_SIZE, true, options.key_type};

}

static KeyGeneration userdataKeyGen() {

return makeGen(s_data_options);

}

static const char* escape_empty(const std::string& value) {

return value.empty() ? "null" : value.c_str();

}

static std::string get_de_key_path(userid_t user_id) {

return StringPrintf("%s/de/%d", user_key_dir.c_str(), user_id);

}

static std::string get_ce_key_directory_path(userid_t user_id) {

return StringPrintf("%s/ce/%d", user_key_dir.c_str(), user_id);

}

// Returns the keys newest first

static std::vector<std::string> get_ce_key_paths(const std::string& directory_path) {

auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(directory_path.c_str()), closedir);

if (!dirp) {

PLOG(ERROR) << "Unable to open ce key directory: " + directory_path;

return std::vector<std::string>();

}

std::vector<std::string> result;

for (;;) {

errno = 0;

auto const entry = readdir(dirp.get());

if (!entry) {

if (errno) {

PLOG(ERROR) << "Unable to read ce key directory: " + directory_path;

return std::vector<std::string>();

}

break;

}

if (IsDotOrDotDot(*entry)) continue;

if (entry->d_type != DT_DIR || entry->d_name[0] != 'c') {

LOG(DEBUG) << "Skipping non-key " << entry->d_name;

continue;

}

result.emplace_back(directory_path + "/" + entry->d_name);

}

std::sort(result.begin(), result.end());

std::reverse(result.begin(), result.end());

return result;

}

static std::string get_ce_key_current_path(const std::string& directory_path) {

return directory_path + "/current";

}

static bool get_ce_key_new_path(const std::string& directory_path,

const std::vector<std::string>& paths, std::string* ce_key_path) {

if (paths.empty()) {

*ce_key_path = get_ce_key_current_path(directory_path);

return true;

}

for (unsigned int i = 0; i < UINT_MAX; i++) {

auto const candidate = StringPrintf("%s/cx%010u", directory_path.c_str(), i);

if (paths[0] < candidate) {

*ce_key_path = candidate;

return true;

}

}

return false;

}

// Discard all keys but the named one; rename it to canonical name.

static bool fixate_user_ce_key(const std::string& directory_path, const std::string& to_fix,

const std::vector<std::string>& paths) {

bool need_sync = false;

for (auto const& other_path : paths) {

if (other_path != to_fix) {

android::vold::destroyKey(other_path);

need_sync = true;

}

}

auto const current_path = get_ce_key_current_path(directory_path);

if (to_fix != current_path) {

LOG(DEBUG) << "Renaming " << to_fix << " to " << current_path;

if (!android::vold::RenameKeyDir(to_fix, current_path)) return false;

need_sync = true;

}

if (need_sync && !android::vold::FsyncDirectory(directory_path)) return false;

return true;

}

static bool read_and_fixate_user_ce_key(userid_t user_id,

const android::vold::KeyAuthentication& auth,

KeyBuffer* ce_key) {

auto const directory_path = get_ce_key_directory_path(user_id);

auto const paths = get_ce_key_paths(directory_path);

for (auto const& ce_key_path : paths) {

LOG(DEBUG) << "Trying user CE key " << ce_key_path;

if (retrieveKey(ce_key_path, auth, ce_key)) {

LOG(DEBUG) << "Successfully retrieved key";

s_deferred_fixations.erase(directory_path);

fixate_user_ce_key(directory_path, ce_key_path, paths);

return true;

}

}

LOG(ERROR) << "Failed to find working ce key for user " << user_id;

return false;

}

// Checks whether the kernel definitely supports the sysfs files that describe the storage

// hardware's inline encryption capabilities. They are supported in upstream 5.18 and later, and in

// android14-5.15 and later (but not android13-5.15). For simplicity we just check for 5.18.

static bool DoesKernelSupportBlkCryptoSysfsFiles() {

struct utsname uts;

unsigned int major = 0, minor = 0;

if (uname(&uts) != 0 || sscanf(uts.release, "%u.%u", &major, &minor) != 2) {

return true; // This should never happen; assume new rather than old.

}

return major > 5 || (major == 5 && minor >= 18);

}

// Checks whether the storage hardware might support only 32-bit data unit numbers.

static bool DoesHardwareSupportOnly32DunBits(const std::string& blk_device) {

// Handle symlinks.

std::string real_path;

if (!Realpath(blk_device, &real_path)) {

real_path = blk_device;

}

// Handle logical volumes.

auto& dm = DeviceMapper::Instance();

for (;;) {

auto parent = dm.GetParentBlockDeviceByPath(real_path);

if (!parent.has_value()) break;

real_path = *parent;

}

// Now we should have the "real" block device.

std::string name = Basename(real_path);

// If possible, do the check precisely via sysfs.

// Exclude older devices, just in case they are broken by doing the check correctly...

if (GetFirstApiLevel() >= __ANDROID_API_V__) {

std::string sysfs_path = "/sys/class/block/" + name + "/queue/crypto/max_dun_bits";

if (!android::vold::pathExists(sysfs_path)) {

// For a partition, "queue" is in the parent directory which represents the disk.

sysfs_path = "/sys/class/block/" + name + "/../queue/crypto/max_dun_bits";

}

if (android::vold::pathExists(sysfs_path)) {

std::string max_dun_bits;

if (!android::base::ReadFileToString(sysfs_path, &max_dun_bits)) {

PLOG(ERROR) << "Error reading " << sysfs_path;

return false;

}

max_dun_bits = android::base::Trim(max_dun_bits);

if (max_dun_bits != "32") {

LOG(ERROR) << sysfs_path << " = " << max_dun_bits;

// In this case, using emmc_optimized is not appropriate because the hardware

// supports inline encryption but does not have the 32-bit DUN limit.

return false;

}

LOG(DEBUG) << sysfs_path << " = " << max_dun_bits;

return true;

}

if (DoesKernelSupportBlkCryptoSysfsFiles()) {

// In this case, using emmc_optimized is not appropriate because the hardware does not

// support inline encryption.

LOG(ERROR) << sysfs_path << " does not exist";

return false;

}

// In this case, the kernel might be too old to support the sysfs files.

}

// Fallback method for older kernels that don't have the crypto capabilities in sysfs. The

// 32-bit DUN limit is only known to exist on eMMC storage, and also on virtio storage that

// inherits the limit from eMMC on the host. So allow either of those storage types. Note that

// this can be overly lenient compared to actually checking max_dun_bits.

if (StartsWith(name, "mmcblk") || StartsWith(name, "vd")) {

LOG(DEBUG) << __func__ << "(): << blk_device = " << blk_device

<< ", real_path = " << real_path;

return true;

}

// Log at ERROR level here so that it shows up in the kernel log.

LOG(ERROR) << __func__ << "(): << blk_device = " << blk_device << ", real_path = " << real_path;

return false;

}

// Sets s_data_options to the file encryption options for the /data filesystem.

static bool init_data_file_encryption_options() {

auto entry = GetEntryForMountPoint(&fstab_default, DATA_MNT_POINT);

if (entry == nullptr) {

LOG(ERROR) << "No mount point entry for " << DATA_MNT_POINT;

return false;

}

if (!ParseOptions(entry->encryption_options, &s_data_options)) {

LOG(ERROR) << "Unable to parse encryption options for " << DATA_MNT_POINT ": "

<< entry->encryption_options;

return false;

}

if ((s_data_options.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&

!DoesHardwareSupportOnly32DunBits(entry->blk_device)) {

// This would unnecessarily reduce security and not be compliant with the CDD.

LOG(ERROR) << "The emmc_optimized encryption flag is only allowed on hardware limited to "

"32-bit DUNs. Remove this flag from the device's fstab";

return false;

}

if (s_data_options.version == 1) {

if (is_metadata_wrapped_key_supported()) s_data_options.key_type = KeyType::kHwWrappedV0;

}

return true;

}

static bool install_storage_key(const std::string& mountpoint, const EncryptionOptions& options,

const KeyBuffer& key, EncryptionPolicy* policy) {

if (options.version == 0) {

LOG(ERROR) << "EncryptionOptions not initialized";

return false;

}

KeyBuffer kernel_key;

if (!prepareKeyForUse(key, options.key_type, &kernel_key)) return false;

return installKey(mountpoint, options, kernel_key, policy);

}

static bool install_userdata_key(const KeyBuffer& key, EncryptionPolicy* policy) {

return install_storage_key(DATA_MNT_POINT, s_data_options, key, policy);

}

// Retrieve the options to use for encryption policies on adoptable storage.

static bool get_volume_file_encryption_options(EncryptionOptions* options) {

// If we give the empty string, libfscrypt will use the default (currently XTS)

auto contents_mode = android::base::GetProperty("ro.crypto.volume.contents_mode", "");

// HEH as default was always a mistake. Use the libfscrypt default (CTS)

// for devices launching on versions above Android 10.

auto first_api_level = GetFirstApiLevel();

auto filenames_mode =

android::base::GetProperty("ro.crypto.volume.filenames_mode",

first_api_level > __ANDROID_API_Q__ ? "" : "aes-256-heh");

auto options_string = android::base::GetProperty("ro.crypto.volume.options",

contents_mode + ":" + filenames_mode);

if (!ParseOptionsForApiLevel(first_api_level, options_string, options)) {

LOG(ERROR) << "Unable to parse volume encryption options: " << options_string;

return false;

}

if (options->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) {

LOG(ERROR) << "The emmc_optimized encryption flag is only allowed on eMMC storage. Remove "

"this flag from ro.crypto.volume.options";

return false;

}

return true;

}

bool is_metadata_wrapped_key_supported() {

return GetEntryForMountPoint(&fstab_default, METADATA_MNT_POINT)->fs_mgr_flags.wrapped_key;

}

// Prepare a directory without assigning it an encryption policy. The directory

// will inherit the encryption policy of its parent directory, or will be

// unencrypted if the parent directory is unencrypted.

static bool prepare_dir(const std::string& dir, mode_t mode, uid_t uid, gid_t gid) {

LOG(DEBUG) << "Preparing: " << dir;

if (android::vold::PrepareDir(dir, mode, uid, gid, 0) != 0) {

PLOG(ERROR) << "Failed to prepare " << dir;

return false;

}

return true;

}

// Prepare a directory and assign it the given encryption policy.

static bool prepare_dir_with_policy(const std::string& dir, mode_t mode, uid_t uid, gid_t gid,

const EncryptionPolicy& policy) {

if (android::vold::pathExists(dir)) {

if (!prepare_dir(dir, mode, uid, gid)) return false;

if (IsFbeEnabled() && !EnsurePolicy(policy, dir)) return false;

} else {

// If the directory does not yet exist, then create it under a temporary name, and only move

// it to the final name after it is fully prepared with an encryption policy and the desired

// file permissions. This prevents the directory from being accessed before it is ready.

//

// Note: this relies on the SELinux file_contexts assigning the same type to the file path

// with the ".new" suffix as to the file path without the ".new" suffix.

const std::string tmp_dir = dir + ".new";

if (android::vold::pathExists(tmp_dir)) {

android::vold::DeleteDirContentsAndDir(tmp_dir);

}

if (!prepare_dir(tmp_dir, mode, uid, gid)) return false;

if (IsFbeEnabled() && !EnsurePolicy(policy, tmp_dir)) return false;

// On some buggy kernels, renaming a directory that is both encrypted and case-insensitive

// fails in some specific circumstances. Unfortunately, these circumstances happen here

// when processing the "media" directory. This was already fixed by kernel commit

// https://git.kernel.org/linus/b5639bb4313b9d45 ('f2fs: don't use casefolded comparison for

// "." and ".."'). But to support kernels that lack that fix, we use the below workaround.

// It bypasses the bug by making the encryption key of tmp_dir be loaded before the rename.

android::vold::pathExists(tmp_dir + "/subdir");

if (rename(tmp_dir.c_str(), dir.c_str()) != 0) {

PLOG(ERROR) << "Failed to rename " << tmp_dir << " to " << dir;

return false;

}

}

return true;

}

static bool destroy_dir(const std::string& dir) {

LOG(DEBUG) << "Destroying: " << dir;

if (rmdir(dir.c_str()) != 0 && errno != ENOENT) {

PLOG(ERROR) << "Failed to destroy " << dir;

return false;

}

return true;

}

// Checks whether the DE key directory exists for the given user.

static bool de_key_exists(userid_t user_id) {

return android::vold::pathExists(get_de_key_path(user_id));

}

// Checks whether at least one CE key subdirectory exists for the given user.

static bool ce_key_exists(userid_t user_id) {

auto directory_path = get_ce_key_directory_path(user_id);

// The common case is that "$dir/current" exists, so check for that first.

if (android::vold::pathExists(get_ce_key_current_path(directory_path))) return true;

// Else, there could still be another subdirectory of $dir (if a crash

// occurred during fixate_user_ce_key()), so check for one.

return android::vold::pathExists(directory_path) && !get_ce_key_paths(directory_path).empty();

}

static bool create_de_key(userid_t user_id, bool ephemeral) {

KeyBuffer de_key;

if (!generateStorageKey(userdataKeyGen(), &de_key)) return false;

if (!ephemeral && !android::vold::storeKeyAtomically(get_de_key_path(user_id), user_key_temp,

kEmptyAuthentication, de_key))

return false;

EncryptionPolicy de_policy;

if (!install_userdata_key(de_key, &de_policy)) return false;

s_de_policies[user_id].internal = de_policy;

LOG(INFO) << "Created DE key for user " << user_id;

return true;

}

static bool create_ce_key(userid_t user_id, bool ephemeral) {

KeyBuffer ce_key;

if (!generateStorageKey(userdataKeyGen(), &ce_key)) return false;

if (!ephemeral) {

if (!prepare_dir(get_ce_key_directory_path(user_id), 0700, AID_ROOT, AID_ROOT))

return false;

// We don't store the CE key on disk here, since here we don't have the

// secret needed to do so securely. Instead, we cache it in memory for

// now, and we store it later in fscrypt_set_ce_key_protection().

s_new_ce_keys.insert({user_id, ce_key});

}

EncryptionPolicy ce_policy;

if (!install_userdata_key(ce_key, &ce_policy)) return false;

s_ce_policies[user_id].internal = ce_policy;

LOG(INFO) << "Created CE key for user " << user_id;

return true;

}

static bool is_numeric(const char* name) {

for (const char* p = name; *p != '\0'; p++) {

if (!isdigit(*p)) return false;

}

return true;

}

static bool load_all_de_keys() {

auto de_dir = user_key_dir + "/de";

auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(de_dir.c_str()), closedir);

if (!dirp) {

PLOG(ERROR) << "Unable to read de key directory";

return false;

}

for (;;) {

errno = 0;

auto entry = readdir(dirp.get());

if (!entry) {

if (errno) {

PLOG(ERROR) << "Unable to read de key directory";

return false;

}

break;

}

if (IsDotOrDotDot(*entry)) continue;

if (entry->d_type != DT_DIR || !is_numeric(entry->d_name)) {

LOG(DEBUG) << "Skipping non-de-key " << entry->d_name;

continue;

}

userid_t user_id = std::stoi(entry->d_name);

auto key_path = de_dir + "/" + entry->d_name;

KeyBuffer de_key;

if (!retrieveKey(key_path, kEmptyAuthentication, &de_key)) {

// This is probably a partially removed user, so ignore

if (user_id != 0) continue;

return false;

}

EncryptionPolicy de_policy;

if (!install_userdata_key(de_key, &de_policy)) return false;

const auto& [existing, is_new] = s_de_policies.insert({user_id, {de_policy, {}}});

if (!is_new && existing->second.internal != de_policy) {

LOG(ERROR) << "DE policy for user" << user_id << " changed";

return false;

}

LOG(DEBUG) << "Installed de key for user " << user_id;

}

// fscrypt:TODO: go through all DE directories, ensure that all user dirs have the

// correct policy set on them, and that no rogue ones exist.

return true;

}

bool fscrypt_initialize_systemwide_keys() {

LOG(INFO) << "fscrypt_initialize_systemwide_keys";

if (!init_data_file_encryption_options()) return false;

KeyBuffer device_key;

if (!retrieveOrGenerateKey(device_key_path, device_key_temp, kEmptyAuthentication,

userdataKeyGen(), &device_key))

return false;

// This initializes s_device_policy, which is a global variable so that

// fscrypt_init_user0() can access it later.

if (!install_userdata_key(device_key, &s_device_policy)) return false;

std::string options_string;

if (!OptionsToString(s_device_policy.options, &options_string)) {

LOG(ERROR) << "Unable to serialize options";

return false;

}

std::string options_filename = std::string(DATA_MNT_POINT) + fscrypt_key_mode;

if (!android::vold::writeStringToFile(options_string, options_filename)) return false;

std::string ref_filename = std::string(DATA_MNT_POINT) + fscrypt_key_ref;

if (!android::vold::writeStringToFile(s_device_policy.key_raw_ref, ref_filename)) return false;

LOG(INFO) << "Wrote system DE key reference to:" << ref_filename;

KeyBuffer per_boot_key;

if (!generateStorageKey(userdataKeyGen(), &per_boot_key)) return false;

EncryptionPolicy per_boot_policy;

if (!install_userdata_key(per_boot_key, &per_boot_policy)) return false;

std::string per_boot_ref_filename = std::string("/data") + fscrypt_key_per_boot_ref;

if (!android::vold::writeStringToFile(per_boot_policy.key_raw_ref, per_boot_ref_filename))

return false;

LOG(INFO) << "Wrote per boot key reference to:" << per_boot_ref_filename;

return true;

}

static void remove_casefolding_from_folder(std::string const& folder, std::string const& leaf) {

std::string original_folder = android::base::GetProperty("ro.casefolding.original_folder", "");

if (original_folder.empty()) return;

original_folder = StringPrintf("%s/%s", original_folder.c_str(), leaf.c_str());

interface_cast<ICasefoldingRemover>(

defaultServiceManager()->waitForService(String16("android.os.casefoldingremover")))

->moveFolder(String16(original_folder.c_str()), String16(folder.c_str()));

}

static bool prepare_special_dirs() {

// Ensure that /data/data and its "alias" /data/user/0 exist, and create the

// bind mount of /data/data onto /data/user/0. This *should* happen in

// fscrypt_prepare_user_storage(). However, it actually must be done early,

// before the rest of user 0's CE storage is prepared. This is because

// zygote may need to set up app data isolation before then, which requires

// mounting a tmpfs over /data/data to ensure it remains hidden. This issue

// arises due to /data/data being in the top-level directory.

// /data/user/0 used to be a symlink to /data/data, so we must first delete

// the old symlink if present.

if (android::vold::IsSymlink(data_user_0_dir) && android::vold::Unlink(data_user_0_dir) != 0)

return false;

// On first boot, we'll be creating /data/data for the first time, and user

// 0's CE key will be installed already since it was just created. Take the

// opportunity to also set the encryption policy of /data/data right away.

if (s_ce_policies.count(0) != 0) {

const EncryptionPolicy& ce_policy = s_ce_policies[0].internal;

if (!prepare_dir_with_policy(data_data_dir, 0771, AID_SYSTEM, AID_SYSTEM, ce_policy)) {

// Preparing /data/data failed, yet we had just generated a new CE

// key because one wasn't stored. Before erroring out, try deleting

// the directory and retrying, as it's possible that the directory

// exists with different CE policy from an interrupted first boot.

if (rmdir(data_data_dir.c_str()) != 0) {

PLOG(ERROR) << "rmdir " << data_data_dir << " failed";

}

if (!prepare_dir_with_policy(data_data_dir, 0771, AID_SYSTEM, AID_SYSTEM, ce_policy))

return false;

}

} else {

if (!prepare_dir(data_data_dir, 0771, AID_SYSTEM, AID_SYSTEM)) return false;

// EnsurePolicy() will have to happen later, in fscrypt_prepare_user_storage().

}

if (!prepare_dir(data_user_0_dir, 0700, AID_SYSTEM, AID_SYSTEM)) return false;

if (android::vold::BindMount(data_data_dir, data_user_0_dir) != 0) return false;

// If /data/media/obb doesn't exist, create it and encrypt it with the

// device policy. Normally, device-policy-encrypted directories are created

// and encrypted by init; /data/media/obb is special because it is located

// in /data/media. Since /data/media also contains per-user encrypted

// directories, by design only vold can write to it. As a side effect of

// that, vold must create /data/media/obb.

//

// We must tolerate /data/media/obb being unencrypted if it already exists

// on-disk, since it used to be unencrypted (b/64566063).

if (android::vold::pathExists(media_obb_dir)) {

if (!prepare_dir(media_obb_dir, 0770, AID_MEDIA_RW, AID_MEDIA_RW)) return false;

} else {

remove_casefolding_from_folder(media_obb_dir, "obb");

if (!prepare_dir_with_policy(media_obb_dir, 0770, AID_MEDIA_RW, AID_MEDIA_RW,

s_device_policy))

return false;

}

return true;

}

bool fscrypt_init_user0_done;

bool fscrypt_init_user0() {

LOG(DEBUG) << "fscrypt_init_user0";

if (IsFbeEnabled()) {

if (!prepare_dir(user_key_dir, 0700, AID_ROOT, AID_ROOT)) return false;

if (!prepare_dir(user_key_dir + "/ce", 0700, AID_ROOT, AID_ROOT)) return false;

if (!prepare_dir(user_key_dir + "/de", 0700, AID_ROOT, AID_ROOT)) return false;

// Create user 0's DE and CE keys if they don't already exist. Check

// each key independently, since if the first boot was interrupted it is

// possible that the DE key exists but the CE key does not.

if (!de_key_exists(0) && !create_de_key(0, false)) return false;

if (!ce_key_exists(0) && !create_ce_key(0, false)) return false;

// TODO: switch to loading only DE_0 here once framework makes

// explicit calls to install DE keys for secondary users

if (!load_all_de_keys()) return false;

}

// Now that user 0's CE key has been created, we can prepare /data/data.

if (!prepare_special_dirs()) return false;

// With the exception of what is done by prepare_special_dirs() above, we

// only prepare DE storage here, since user 0's CE key won't be installed

// yet unless it was just created. The framework will prepare the user's CE

// storage later, once their CE key is installed.

if (!fscrypt_prepare_user_storage("", 0, android::os::IVold::STORAGE_FLAG_DE)) {

LOG(ERROR) << "Failed to prepare user 0 storage";

return false;

}

fscrypt_init_user0_done = true;

return true;

}

// Creates the CE and DE keys for a new user.

bool fscrypt_create_user_keys(userid_t user_id, bool ephemeral) {

LOG(DEBUG) << "fscrypt_create_user_keys for " << user_id;

if (!IsFbeEnabled()) {

return true;

}

// FIXME test for existence of key that is not loaded yet

if (s_ce_policies.count(user_id) != 0) {

LOG(ERROR) << "Already exists, can't create keys for " << user_id;

// FIXME should we fail the command?

return true;

}

if (!create_de_key(user_id, ephemeral)) return false;

if (!create_ce_key(user_id, ephemeral)) return false;

if (ephemeral) s_ephemeral_users.insert(user_id);

return true;

}

// Evicts all the user's keys of one type from all volumes (internal and adoptable).

// This evicts either CE keys or DE keys, depending on which map is passed.

static bool evict_user_keys(std::map<userid_t, UserPolicies>& policy_map, userid_t user_id) {

bool success = true;

auto it = policy_map.find(user_id);

if (it != policy_map.end()) {

const UserPolicies& policies = it->second;

success &= android::vold::evictKey(BuildDataPath(""), policies.internal);

for (const auto& [volume_uuid, policy] : policies.adoptable) {

success &= android::vold::evictKey(BuildDataPath(volume_uuid), policy);

}

policy_map.erase(it);

}

return success;

}

// Evicts and destroys all CE and DE keys for a user. This is called when the user is removed.

bool fscrypt_destroy_user_keys(userid_t user_id) {

LOG(DEBUG) << "fscrypt_destroy_user_keys(" << user_id << ")";

if (!IsFbeEnabled()) {

return true;

}

bool success = true;

success &= evict_user_keys(s_ce_policies, user_id);

success &= evict_user_keys(s_de_policies, user_id);

if (!s_ephemeral_users.erase(user_id)) {

auto ce_path = get_ce_key_directory_path(user_id);

if (!s_new_ce_keys.erase(user_id)) {

for (auto const& path : get_ce_key_paths(ce_path)) {

success &= android::vold::destroyKey(path);

}

}

s_deferred_fixations.erase(ce_path);

success &= destroy_dir(ce_path);

auto de_key_path = get_de_key_path(user_id);

if (android::vold::pathExists(de_key_path)) {

success &= android::vold::destroyKey(de_key_path);

} else {

LOG(INFO) << "Not present so not erasing: " << de_key_path;

}

}

return success;

}

static android::vold::KeyAuthentication authentication_from_secret(

const std::vector<uint8_t>& secret) {

std::string secret_str(secret.begin(), secret.end());

if (secret_str.empty()) {

return kEmptyAuthentication;

} else {

return android::vold::KeyAuthentication(secret_str);

}

}

static std::string volkey_path(const std::string& misc_path, const std::string& volume_uuid) {

return misc_path + "/vold/volume_keys/" + volume_uuid + "/default";

}

static std::string volume_secdiscardable_path(const std::string& volume_uuid) {

return systemwide_volume_key_dir + "/" + volume_uuid + "/secdiscardable";

}

static bool read_or_create_volkey(const std::string& misc_path, const std::string& volume_uuid,

UserPolicies& user_policies, EncryptionPolicy* policy) {

auto secdiscardable_path = volume_secdiscardable_path(volume_uuid);

std::string secdiscardable_hash;

if (android::vold::pathExists(secdiscardable_path)) {

if (!android::vold::readSecdiscardable(secdiscardable_path, &secdiscardable_hash))

return false;

} else {

if (!android::vold::MkdirsSync(secdiscardable_path, 0700)) return false;

if (!android::vold::createSecdiscardable(secdiscardable_path, &secdiscardable_hash))

return false;

}

auto key_path = volkey_path(misc_path, volume_uuid);

if (!android::vold::MkdirsSync(key_path, 0700)) return false;

android::vold::KeyAuthentication auth(secdiscardable_hash);

EncryptionOptions options;

if (!get_volume_file_encryption_options(&options)) return false;

KeyBuffer key;

if (!retrieveOrGenerateKey(key_path, key_path + "_tmp", auth, makeGen(options), &key))

return false;

if (!install_storage_key(BuildDataPath(volume_uuid), options, key, policy)) return false;

user_policies.adoptable[volume_uuid] = *policy;

return true;

}

static bool destroy_volkey(const std::string& misc_path, const std::string& volume_uuid) {

auto path = volkey_path(misc_path, volume_uuid);

if (!android::vold::pathExists(path)) return true;

return android::vold::destroyKey(path);

}

// (Re-)encrypts the user's CE key with the given secret. This function handles

// storing the CE key for a new user for the first time. It also handles

// re-encrypting the CE key upon upgrade from an Android version where the CE

// key was stored with kEmptyAuthentication when the user didn't have an LSKF.

// See the comments below for the different cases handled.

bool fscrypt_set_ce_key_protection(userid_t user_id, const std::vector<uint8_t>& secret) {

LOG(DEBUG) << "fscrypt_set_ce_key_protection " << user_id;

if (!IsFbeEnabled()) return true;

auto auth = authentication_from_secret(secret);

if (auth.secret.empty()) {

LOG(ERROR) << "fscrypt_set_ce_key_protection: secret must be nonempty";

return false;

}

// We shouldn't store any keys for ephemeral users.

if (s_ephemeral_users.count(user_id) != 0) {

LOG(DEBUG) << "Not storing key because user is ephemeral";

return true;

}

KeyBuffer ce_key;

auto it = s_new_ce_keys.find(user_id);

if (it != s_new_ce_keys.end()) {

// If the key exists in s_new_ce_keys, then the key is a

// not-yet-committed key for a new user, and we are committing it here.

// This happens when the user's synthetic password is created.

ce_key = it->second;

} else if (ce_key_exists(user_id)) {

// If the key doesn't exist in s_new_ce_keys but does exist on-disk,

// then we are setting the protection on an existing key. This happens

// at upgrade time, when CE keys that were previously protected by

// kEmptyAuthentication are encrypted by the user's synthetic password.

LOG(DEBUG) << "CE key already exists on-disk; re-protecting it with the given secret";

if (!read_and_fixate_user_ce_key(user_id, kEmptyAuthentication, &ce_key)) {

// Before failing, also check whether the key is already protected

// with the given secret.

if (read_and_fixate_user_ce_key(user_id, auth, &ce_key)) {

LOG(INFO) << "CE key is already protected by given secret. Nothing to do.";

LOG(INFO) << "Errors above are for the attempt with empty auth and can be ignored.";

return true;

}

LOG(ERROR) << "Failed to retrieve CE key for user " << user_id;

// The key isn't protected by either kEmptyAuthentication or by

// |auth|. This should never happen, and there's nothing we can do

// besides return an error.

return false;

}

} else {

// If the key doesn't exist in memory or on-disk, then we need to

// generate it here, then commit it to disk. This is needed after the

// unusual case where a non-system user was created during early boot,

// and then the device was force-rebooted before the boot completed. In

// that case, the Android user record was committed but the CE key was

// not. So the CE key was lost, and we need to regenerate it. This

// should be fine, since the key should not have been used yet.

LOG(WARNING) << "CE key not found! Regenerating it";

if (!create_ce_key(user_id, false)) return false;

ce_key = s_new_ce_keys.find(user_id)->second;

}

auto const directory_path = get_ce_key_directory_path(user_id);

auto const paths = get_ce_key_paths(directory_path);

std::string ce_key_path;

if (!get_ce_key_new_path(directory_path, paths, &ce_key_path)) return false;

if (!android::vold::storeKeyAtomically(ce_key_path, user_key_temp, auth, ce_key)) return false;

// Fixate the key, i.e. delete all other bindings of it. (In practice this

// just means the kEmptyAuthentication binding, if there is one.) However,

// if a userdata filesystem checkpoint is pending, then we need to delay the

// fixation until the checkpoint has been committed, since deleting keys

// from Keystore cannot be rolled back.

if (android::vold::cp_needsCheckpoint()) {

LOG(INFO) << "Deferring fixation of " << directory_path << " until checkpoint is committed";

s_deferred_fixations[directory_path] = ce_key_path;

} else {

s_deferred_fixations.erase(directory_path);

if (!fixate_user_ce_key(directory_path, ce_key_path, paths)) return false;

}

if (s_new_ce_keys.erase(user_id)) {

LOG(INFO) << "Stored CE key for new user " << user_id;

}

return true;

}

void fscrypt_deferred_fixate_ce_keys() {

for (const auto& it : s_deferred_fixations) {

const auto& directory_path = it.first;

const auto& to_fix = it.second;

LOG(INFO) << "Doing deferred fixation of " << directory_path;

fixate_user_ce_key(directory_path, to_fix, get_ce_key_paths(directory_path));

// Continue on error.

}

s_deferred_fixations.clear();

}

std::vector<int> fscrypt_get_unlocked_users() {

std::vector<int> user_ids;

for (const auto& [user_id, user_policies] : s_ce_policies) {

user_ids.push_back(user_id);

}

return user_ids;

}

// Unlocks internal CE storage for the given user. This only unlocks internal storage, since

// fscrypt_prepare_user_storage() has to be called for each adoptable storage volume anyway (since

// the volume might have been absent when the user was created), and that handles the unlocking.

bool fscrypt_unlock_ce_storage(userid_t user_id, const std::vector<uint8_t>& secret) {

LOG(DEBUG) << "fscrypt_unlock_ce_storage " << user_id;

if (!IsFbeEnabled()) return true;

if (s_ce_policies.count(user_id) != 0) {

LOG(WARNING) << "CE storage for user " << user_id << " is already unlocked";

return true;

}

auto auth = authentication_from_secret(secret);

KeyBuffer ce_key;

if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;

EncryptionPolicy ce_policy;

if (!install_userdata_key(ce_key, &ce_policy)) return false;

s_ce_policies[user_id].internal = ce_policy;

LOG(DEBUG) << "Installed CE key for user " << user_id;

return true;

}

// Locks CE storage for the given user. This locks both internal and adoptable storage.

bool fscrypt_lock_ce_storage(userid_t user_id) {

LOG(DEBUG) << "fscrypt_lock_ce_storage " << user_id;

if (!IsFbeEnabled()) return true;

return evict_user_keys(s_ce_policies, user_id);

}

static bool prepare_subdirs(const std::string& action, const std::string& volume_uuid,

userid_t user_id, int flags) {

if (0 != android::vold::ForkExecvp(

std::vector<std::string>{prepare_subdirs_path, action, volume_uuid,

std::to_string(user_id), std::to_string(flags)})) {

LOG(ERROR) << "vold_prepare_subdirs failed";

return false;

}

return true;

}

bool fscrypt_prepare_user_storage(const std::string& volume_uuid, userid_t user_id, int flags) {

LOG(DEBUG) << "fscrypt_prepare_user_storage for volume " << escape_empty(volume_uuid)

<< ", user " << user_id << ", flags " << flags;

// Internal storage must be prepared before adoptable storage, since the

// user's volume keys are stored in their internal storage.

if (!volume_uuid.empty()) {

if ((flags & android::os::IVold::STORAGE_FLAG_DE) &&

!android::vold::pathExists(android::vold::BuildDataMiscDePath("", user_id))) {

LOG(ERROR) << "Cannot prepare DE storage for user " << user_id << " on volume "

<< volume_uuid << " before internal storage";

return false;

}

if ((flags & android::os::IVold::STORAGE_FLAG_CE) &&

!android::vold::pathExists(android::vold::BuildDataMiscCePath("", user_id))) {

LOG(ERROR) << "Cannot prepare CE storage for user " << user_id << " on volume "

<< volume_uuid << " before internal storage";

return false;

}

}

if (flags & android::os::IVold::STORAGE_FLAG_DE) {

// DE_sys key

auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);

auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);

// DE_n key

EncryptionPolicy de_policy;

auto system_de_path = android::vold::BuildDataSystemDePath(user_id);

auto misc_de_path = android::vold::BuildDataMiscDePath(volume_uuid, user_id);

auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);

auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);

if (IsFbeEnabled()) {

auto it = s_de_policies.find(user_id);

if (it == s_de_policies.end()) {

LOG(ERROR) << "Cannot find DE policy for user " << user_id;

return false;

}

UserPolicies& user_de_policies = it->second;

if (volume_uuid.empty()) {

de_policy = user_de_policies.internal;

} else {

auto misc_de_empty_volume_path = android::vold::BuildDataMiscDePath("", user_id);

if (!read_or_create_volkey(misc_de_empty_volume_path, volume_uuid, user_de_policies,

&de_policy)) {

return false;

}

}

}

if (volume_uuid.empty()) {

if (!prepare_dir(system_legacy_path, 0700, AID_SYSTEM, AID_SYSTEM)) return false;

if (!prepare_dir(profiles_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;

if (!prepare_dir_with_policy(system_de_path, 0770, AID_SYSTEM, AID_SYSTEM, de_policy))

return false;

if (!prepare_dir_with_policy(vendor_de_path, 0771, AID_ROOT, AID_ROOT, de_policy))