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platform_system_vold/FsCrypt.cpp
Eric Biggers f74373b177 KeyStorage: rework key upgrade handling 
Remove the error-prone 'keepOld' parameter, and instead make begin()
(renamed to BeginKeymasterOp()) do all the key upgrade handling.

Don't handle /data and /metadata differently anymore.  Previously, when
a checkpoint is active, key blob files were replaced on /data
immediately; only the actual Keymaster key deletion was delayed until
checkpoint commit.  But it's easier to just delay the key blob file
replacement too, as we have to implement that for /metadata anyway.

Also be more vigilant about deleting any leftover upgraded keys.

Test: Tested on bramble using an OTA rvc-d1-release => master.  In OTA
      success case, verified via logcat that the keys were upgraded and
      then were committed after the boot succeeded.  In OTA failure
      case, verified that the device still boots -- i.e., the old keys
      weren't lost.  Verified that in either case, no
      keymaster_key_blob_upgraded files were left over.  Finally, also
      tried 'pm create-user' and 'pm remove-user' and verified via
      logcat that the Keymaster keys still get deleted.
Change-Id: Ic9c3e63e0bcae0c608fc79050ca4a1676b3852ee
2020-11-05 19:58:26 -08:00

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/*
* 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 "KeyStorage.h"
#include "KeyUtil.h"
#include "Utils.h"
#include "VoldUtil.h"
#include <algorithm>
#include <map>
#include <optional>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <selinux/android.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <private/android_filesystem_config.h>
#include <private/android_projectid_config.h>
#include "android/os/IVold.h"
#define EMULATED_USES_SELINUX 0
#define MANAGE_MISC_DIRS 0
#include <cutils/fs.h>
#include <cutils/properties.h>
#include <fscrypt/fscrypt.h>
#include <keyutils.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>
using android::base::Basename;
using android::base::Realpath;
using android::base::StartsWith;
using android::base::StringPrintf;
using android::fs_mgr::GetEntryForMountPoint;
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::SetQuotaInherit;
using android::vold::SetQuotaProjectId;
using android::vold::writeStringToFile;
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";
// Some users are ephemeral, don't try to wipe their keys from disk
std::set<userid_t> s_ephemeral_users;
// Map user ids to encryption policies
std::map<userid_t, EncryptionPolicy> s_de_policies;
std::map<userid_t, EncryptionPolicy> s_ce_policies;
} // namespace
// Returns KeyGeneration suitable for key as described in EncryptionOptions
static KeyGeneration makeGen(const EncryptionOptions& options) {
return KeyGeneration{FSCRYPT_MAX_KEY_SIZE, true, options.use_hw_wrapped_key};
}
static bool fscrypt_is_emulated() {
return property_get_bool("persist.sys.emulate_fbe", false);
}
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.
// No point in acting on errors in this; ignore them.
static void fixate_user_ce_key(const std::string& directory_path, const std::string& to_fix,
const std::vector<std::string>& paths) {
for (auto const other_path : paths) {
if (other_path != to_fix) {
android::vold::destroyKey(other_path);
}
}
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 (rename(to_fix.c_str(), current_path.c_str()) != 0) {
PLOG(WARNING) << "Unable to rename " << to_fix << " to " << current_path;
return;
}
}
android::vold::FsyncDirectory(directory_path);
}
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";
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;
}
static bool IsEmmcStorage(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.
LOG(DEBUG) << "IsEmmcStorage(): blk_device = " << blk_device << ", real_path=" << real_path;
return StartsWith(Basename(real_path), "mmcblk");
}
// Retrieve the options to use for encryption policies on the /data filesystem.
static bool get_data_file_encryption_options(EncryptionOptions* 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, options)) {
LOG(ERROR) << "Unable to parse encryption options for " << DATA_MNT_POINT ": "
<< entry->encryption_options;
return false;
}
if ((options->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
!IsEmmcStorage(entry->blk_device)) {
LOG(ERROR) << "The emmc_optimized encryption flag is only allowed on eMMC storage. Remove "
"this flag from the device's fstab";
return false;
}
return true;
}
static bool install_storage_key(const std::string& mountpoint, const EncryptionOptions& options,
const KeyBuffer& key, EncryptionPolicy* policy) {
KeyBuffer ephemeral_wrapped_key;
if (options.use_hw_wrapped_key) {
if (!exportWrappedStorageKey(key, &ephemeral_wrapped_key)) {
LOG(ERROR) << "Failed to get ephemeral wrapped key";
return false;
}
}
return installKey(mountpoint, options, options.use_hw_wrapped_key ? ephemeral_wrapped_key : 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;
}
static bool read_and_install_user_ce_key(userid_t user_id,
const android::vold::KeyAuthentication& auth) {
if (s_ce_policies.count(user_id) != 0) return true;
EncryptionOptions options;
if (!get_data_file_encryption_options(&options)) return false;
KeyBuffer ce_key;
if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;
EncryptionPolicy ce_policy;
if (!install_storage_key(DATA_MNT_POINT, options, ce_key, &ce_policy)) return false;
s_ce_policies[user_id] = ce_policy;
LOG(DEBUG) << "Installed ce key for user " << user_id;
return true;
}
static bool prepare_dir(const std::string& dir, mode_t mode, uid_t uid, gid_t gid) {
LOG(DEBUG) << "Preparing: " << dir;
if (fs_prepare_dir(dir.c_str(), mode, uid, gid) != 0) {
PLOG(ERROR) << "Failed to prepare " << 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;
}
// NB this assumes that there is only one thread listening for crypt commands, because
// it creates keys in a fixed location.
static bool create_and_install_user_keys(userid_t user_id, bool create_ephemeral) {
EncryptionOptions options;
if (!get_data_file_encryption_options(&options)) return false;
KeyBuffer de_key, ce_key;
if (!generateStorageKey(makeGen(options), &de_key)) return false;
if (!generateStorageKey(makeGen(options), &ce_key)) return false;
if (create_ephemeral) {
// If the key should be created as ephemeral, don't store it.
s_ephemeral_users.insert(user_id);
} else {
auto const directory_path = get_ce_key_directory_path(user_id);
if (!prepare_dir(directory_path, 0700, AID_ROOT, AID_ROOT)) return false;
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, kEmptyAuthentication,
ce_key))
return false;
fixate_user_ce_key(directory_path, ce_key_path, paths);
// Write DE key second; once this is written, all is good.
if (!android::vold::storeKeyAtomically(get_de_key_path(user_id), user_key_temp,
kEmptyAuthentication, de_key))
return false;
}
EncryptionPolicy de_policy;
if (!install_storage_key(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
s_de_policies[user_id] = de_policy;
EncryptionPolicy ce_policy;
if (!install_storage_key(DATA_MNT_POINT, options, ce_key, &ce_policy)) return false;
s_ce_policies[user_id] = ce_policy;
LOG(DEBUG) << "Created keys for user " << user_id;
return true;
}
static bool lookup_policy(const std::map<userid_t, EncryptionPolicy>& key_map, userid_t user_id,
EncryptionPolicy* policy) {
auto refi = key_map.find(user_id);
if (refi == key_map.end()) {
LOG(DEBUG) << "Cannot find key for " << user_id;
return false;
}
*policy = refi->second;
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() {
EncryptionOptions options;
if (!get_data_file_encryption_options(&options)) return false;
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)) return false;
EncryptionPolicy de_policy;
if (!install_storage_key(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
auto ret = s_de_policies.insert({user_id, de_policy});
if (!ret.second && ret.first->second != 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;
}
// Attempt to reinstall CE keys for users that we think are unlocked.
static bool try_reload_ce_keys() {
for (const auto& it : s_ce_policies) {
if (!android::vold::reloadKeyFromSessionKeyring(DATA_MNT_POINT, it.second)) {
LOG(ERROR) << "Failed to load CE key from session keyring for user " << it.first;
return false;
}
}
return true;
}
bool fscrypt_initialize_systemwide_keys() {
LOG(INFO) << "fscrypt_initialize_systemwide_keys";
EncryptionOptions options;
if (!get_data_file_encryption_options(&options)) return false;
KeyBuffer device_key;
if (!retrieveOrGenerateKey(device_key_path, device_key_temp, kEmptyAuthentication,
makeGen(options), &device_key))
return false;
EncryptionPolicy device_policy;
if (!install_storage_key(DATA_MNT_POINT, options, device_key, &device_policy)) return false;
std::string options_string;
if (!OptionsToString(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(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(makeGen(options), &per_boot_key)) return false;
EncryptionPolicy per_boot_policy;
if (!install_storage_key(DATA_MNT_POINT, options, 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;
if (!android::vold::FsyncDirectory(device_key_dir)) return false;
return true;
}
bool fscrypt_init_user0() {
LOG(DEBUG) << "fscrypt_init_user0";
if (fscrypt_is_native()) {
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;
if (!android::vold::pathExists(get_de_key_path(0))) {
if (!create_and_install_user_keys(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;
}
// We can only safely prepare DE storage here, since CE keys are probably
// entangled with user credentials. The framework will always prepare CE
// storage once CE keys are installed.
if (!fscrypt_prepare_user_storage("", 0, 0, android::os::IVold::STORAGE_FLAG_DE)) {
LOG(ERROR) << "Failed to prepare user 0 storage";
return false;
}
// If this is a non-FBE device that recently left an emulated mode,
// restore user data directories to known-good state.
if (!fscrypt_is_native() && !fscrypt_is_emulated()) {
fscrypt_unlock_user_key(0, 0, "!", "!");
}
// In some scenarios (e.g. userspace reboot) we might unmount userdata
// without doing a hard reboot. If CE keys were stored in fs keyring then
// they will be lost after unmount. Attempt to re-install them.
if (fscrypt_is_native() && android::vold::isFsKeyringSupported()) {
if (!try_reload_ce_keys()) return false;
}
return true;
}
bool fscrypt_vold_create_user_key(userid_t user_id, int serial, bool ephemeral) {
LOG(DEBUG) << "fscrypt_vold_create_user_key for " << user_id << " serial " << serial;
if (!fscrypt_is_native()) {
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 fscrypt_vold_create_user_key for " << user_id
<< " serial " << serial;
// FIXME should we fail the command?
return true;
}
if (!create_and_install_user_keys(user_id, ephemeral)) {
return false;
}
return true;
}
// "Lock" all encrypted directories whose key has been removed. This is needed
// in the case where the keys are being put in the session keyring (rather in
// the newer filesystem-level keyrings), because removing a key from the session
// keyring doesn't affect inodes in the kernel's inode cache whose per-file key
// was already set up. So to remove the per-file keys and make the files
// "appear encrypted", these inodes must be evicted.
//
// To do this, sync() to clean all dirty inodes, then drop all reclaimable slab
// objects systemwide. This is overkill, but it's the best available method
// currently. Don't use drop_caches mode "3" because that also evicts pagecache
// for in-use files; all files relevant here are already closed and sync'ed.
static void drop_caches_if_needed() {
if (android::vold::isFsKeyringSupported()) {
return;
}
sync();
if (!writeStringToFile("2", "/proc/sys/vm/drop_caches")) {
PLOG(ERROR) << "Failed to drop caches during key eviction";
}
}
static bool evict_ce_key(userid_t user_id) {
bool success = true;
EncryptionPolicy policy;
// If we haven't loaded the CE key, no need to evict it.
if (lookup_policy(s_ce_policies, user_id, &policy)) {
success &= android::vold::evictKey(DATA_MNT_POINT, policy);
drop_caches_if_needed();
}
s_ce_policies.erase(user_id);
return success;
}
bool fscrypt_destroy_user_key(userid_t user_id) {
LOG(DEBUG) << "fscrypt_destroy_user_key(" << user_id << ")";
if (!fscrypt_is_native()) {
return true;
}
bool success = true;
success &= evict_ce_key(user_id);
EncryptionPolicy de_policy;
success &= lookup_policy(s_de_policies, user_id, &de_policy) &&
android::vold::evictKey(DATA_MNT_POINT, de_policy);
s_de_policies.erase(user_id);
auto it = s_ephemeral_users.find(user_id);
if (it != s_ephemeral_users.end()) {
s_ephemeral_users.erase(it);
} else {
for (auto const path : get_ce_key_paths(get_ce_key_directory_path(user_id))) {
success &= android::vold::destroyKey(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 bool emulated_lock(const std::string& path) {
if (chmod(path.c_str(), 0000) != 0) {
PLOG(ERROR) << "Failed to chmod " << path;
return false;
}
#if EMULATED_USES_SELINUX
if (setfilecon(path.c_str(), "u:object_r:storage_stub_file:s0") != 0) {
PLOG(WARNING) << "Failed to setfilecon " << path;
return false;
}
#endif
return true;
}
static bool emulated_unlock(const std::string& path, mode_t mode) {
if (chmod(path.c_str(), mode) != 0) {
PLOG(ERROR) << "Failed to chmod " << path;
// FIXME temporary workaround for b/26713622
if (fscrypt_is_emulated()) return false;
}
#if EMULATED_USES_SELINUX
if (selinux_android_restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_FORCE) != 0) {
PLOG(WARNING) << "Failed to restorecon " << path;
// FIXME temporary workaround for b/26713622
if (fscrypt_is_emulated()) return false;
}
#endif
return true;
}
static bool parse_hex(const std::string& hex, std::string* result) {
if (hex == "!") {
*result = "";
return true;
}
if (android::vold::HexToStr(hex, *result) != 0) {
LOG(ERROR) << "Invalid FBE hex string"; // Don't log the string for security reasons
return false;
}
return true;
}
static std::optional<android::vold::KeyAuthentication> authentication_from_hex(
const std::string& token_hex, const std::string& secret_hex) {
std::string token, secret;
if (!parse_hex(token_hex, &token)) return std::optional<android::vold::KeyAuthentication>();
if (!parse_hex(secret_hex, &secret)) return std::optional<android::vold::KeyAuthentication>();
if (secret.empty()) {
return kEmptyAuthentication;
} else {
return android::vold::KeyAuthentication(token, secret);
}
}
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,
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 (fs_mkdirs(secdiscardable_path.c_str(), 0700) != 0) {
PLOG(ERROR) << "Creating directories for: " << secdiscardable_path;
return false;
}
if (!android::vold::createSecdiscardable(secdiscardable_path, &secdiscardable_hash))
return false;
}
auto key_path = volkey_path(misc_path, volume_uuid);
if (fs_mkdirs(key_path.c_str(), 0700) != 0) {
PLOG(ERROR) << "Creating directories for: " << key_path;
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;
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);
}
static bool fscrypt_rewrap_user_key(userid_t user_id, int serial,
const android::vold::KeyAuthentication& retrieve_auth,
const android::vold::KeyAuthentication& store_auth) {
if (s_ephemeral_users.count(user_id) != 0) return true;
auto const directory_path = get_ce_key_directory_path(user_id);
KeyBuffer ce_key;
std::string ce_key_current_path = get_ce_key_current_path(directory_path);
if (retrieveKey(ce_key_current_path, retrieve_auth, &ce_key)) {
LOG(DEBUG) << "Successfully retrieved key";
// TODO(147732812): Remove this once Locksettingservice is fixed.
// Currently it calls fscrypt_clear_user_key_auth with a secret when lockscreen is
// changed from swipe to none or vice-versa
} else if (retrieveKey(ce_key_current_path, kEmptyAuthentication, &ce_key)) {
LOG(DEBUG) << "Successfully retrieved key with empty auth";
} else {
LOG(ERROR) << "Failed to retrieve key for user " << user_id;
return false;
}
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, store_auth, ce_key))
return false;
if (!android::vold::FsyncDirectory(directory_path)) return false;
return true;
}
bool fscrypt_add_user_key_auth(userid_t user_id, int serial, const std::string& token_hex,
const std::string& secret_hex) {
LOG(DEBUG) << "fscrypt_add_user_key_auth " << user_id << " serial=" << serial
<< " token_present=" << (token_hex != "!");
if (!fscrypt_is_native()) return true;
auto auth = authentication_from_hex(token_hex, secret_hex);
if (!auth) return false;
return fscrypt_rewrap_user_key(user_id, serial, kEmptyAuthentication, *auth);
}
bool fscrypt_clear_user_key_auth(userid_t user_id, int serial, const std::string& token_hex,
const std::string& secret_hex) {
LOG(DEBUG) << "fscrypt_clear_user_key_auth " << user_id << " serial=" << serial
<< " token_present=" << (token_hex != "!");
if (!fscrypt_is_native()) return true;
auto auth = authentication_from_hex(token_hex, secret_hex);
if (!auth) return false;
return fscrypt_rewrap_user_key(user_id, serial, *auth, kEmptyAuthentication);
}
bool fscrypt_fixate_newest_user_key_auth(userid_t user_id) {
LOG(DEBUG) << "fscrypt_fixate_newest_user_key_auth " << user_id;
if (!fscrypt_is_native()) return true;
if (s_ephemeral_users.count(user_id) != 0) return true;
auto const directory_path = get_ce_key_directory_path(user_id);
auto const paths = get_ce_key_paths(directory_path);
if (paths.empty()) {
LOG(ERROR) << "No ce keys present, cannot fixate for user " << user_id;
return false;
}
fixate_user_ce_key(directory_path, paths[0], paths);
return true;
}
// TODO: rename to 'install' for consistency, and take flags to know which keys to install
bool fscrypt_unlock_user_key(userid_t user_id, int serial, const std::string& token_hex,
const std::string& secret_hex) {
LOG(DEBUG) << "fscrypt_unlock_user_key " << user_id << " serial=" << serial
<< " token_present=" << (token_hex != "!");
if (fscrypt_is_native()) {
if (s_ce_policies.count(user_id) != 0) {
LOG(WARNING) << "Tried to unlock already-unlocked key for user " << user_id;
return true;
}
auto auth = authentication_from_hex(token_hex, secret_hex);
if (!auth) return false;
if (!read_and_install_user_ce_key(user_id, *auth)) {
LOG(ERROR) << "Couldn't read key for " << user_id;
return false;
}
} else {
// When in emulation mode, we just use chmod. However, we also
// unlock directories when not in emulation mode, to bring devices
// back into a known-good state.
if (!emulated_unlock(android::vold::BuildDataSystemCePath(user_id), 0771) ||
!emulated_unlock(android::vold::BuildDataMiscCePath(user_id), 01771) ||
!emulated_unlock(android::vold::BuildDataMediaCePath("", user_id), 0770) ||
!emulated_unlock(android::vold::BuildDataUserCePath("", user_id), 0771)) {
LOG(ERROR) << "Failed to unlock user " << user_id;
return false;
}
}
return true;
}
// TODO: rename to 'evict' for consistency
bool fscrypt_lock_user_key(userid_t user_id) {
LOG(DEBUG) << "fscrypt_lock_user_key " << user_id;
if (fscrypt_is_native()) {
return evict_ce_key(user_id);
} else if (fscrypt_is_emulated()) {
// When in emulation mode, we just use chmod
if (!emulated_lock(android::vold::BuildDataSystemCePath(user_id)) ||
!emulated_lock(android::vold::BuildDataMiscCePath(user_id)) ||
!emulated_lock(android::vold::BuildDataMediaCePath("", user_id)) ||
!emulated_lock(android::vold::BuildDataUserCePath("", user_id))) {
LOG(ERROR) << "Failed to lock user " << user_id;
return false;
}
}
return true;
}
static bool prepare_subdirs(const std::string& action, const std::string& volume_uuid,
userid_t user_id, int flags) {
// TODO(b/141677108): Remove this & make it the default behavior
if (android::base::GetProperty("ro.vold.level_from_user", "0") == "1") {
flags |= android::os::IVold::STORAGE_FLAG_LEVEL_FROM_USER;
}
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 serial,
int flags) {
LOG(DEBUG) << "fscrypt_prepare_user_storage for volume " << escape_empty(volume_uuid)
<< ", user " << user_id << ", serial " << serial << ", flags " << flags;
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
// DE_sys key
auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
// DE_n key
auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
if (volume_uuid.empty()) {
if (!prepare_dir(system_legacy_path, 0700, AID_SYSTEM, AID_SYSTEM)) return false;
#if MANAGE_MISC_DIRS
if (!prepare_dir(misc_legacy_path, 0750, multiuser_get_uid(user_id, AID_SYSTEM),
multiuser_get_uid(user_id, AID_EVERYBODY)))
return false;
#endif
if (!prepare_dir(profiles_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
if (!prepare_dir(system_de_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
if (!prepare_dir(misc_de_path, 01771, AID_SYSTEM, AID_MISC)) return false;
if (!prepare_dir(vendor_de_path, 0771, AID_ROOT, AID_ROOT)) return false;
}
if (!prepare_dir(user_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
if (fscrypt_is_native()) {
EncryptionPolicy de_policy;
if (volume_uuid.empty()) {
if (!lookup_policy(s_de_policies, user_id, &de_policy)) return false;
if (!EnsurePolicy(de_policy, system_de_path)) return false;
if (!EnsurePolicy(de_policy, misc_de_path)) return false;
if (!EnsurePolicy(de_policy, vendor_de_path)) return false;
} else {
if (!read_or_create_volkey(misc_de_path, volume_uuid, &de_policy)) return false;
}
if (!EnsurePolicy(de_policy, user_de_path)) return false;
}
}
if (flags & android::os::IVold::STORAGE_FLAG_CE) {
// CE_n key
auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
if (volume_uuid.empty()) {
if (!prepare_dir(system_ce_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
if (!prepare_dir(misc_ce_path, 01771, AID_SYSTEM, AID_MISC)) return false;
if (!prepare_dir(vendor_ce_path, 0771, AID_ROOT, AID_ROOT)) return false;
}
if (!prepare_dir(media_ce_path, 0770, AID_MEDIA_RW, AID_MEDIA_RW)) return false;
if (!prepare_dir(user_ce_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
if (fscrypt_is_native()) {
EncryptionPolicy ce_policy;
if (volume_uuid.empty()) {
if (!lookup_policy(s_ce_policies, user_id, &ce_policy)) return false;
if (!EnsurePolicy(ce_policy, system_ce_path)) return false;
if (!EnsurePolicy(ce_policy, misc_ce_path)) return false;
if (!EnsurePolicy(ce_policy, vendor_ce_path)) return false;
} else {
if (!read_or_create_volkey(misc_ce_path, volume_uuid, &ce_policy)) return false;
}
if (!EnsurePolicy(ce_policy, media_ce_path)) return false;
if (!EnsurePolicy(ce_policy, user_ce_path)) return false;
}
if (volume_uuid.empty()) {
// Now that credentials have been installed, we can run restorecon
// over these paths
// NOTE: these paths need to be kept in sync with libselinux
android::vold::RestoreconRecursive(system_ce_path);
android::vold::RestoreconRecursive(vendor_ce_path);
android::vold::RestoreconRecursive(misc_ce_path);
}
}
if (!prepare_subdirs("prepare", volume_uuid, user_id, flags)) return false;
return true;
}
bool fscrypt_destroy_user_storage(const std::string& volume_uuid, userid_t user_id, int flags) {
LOG(DEBUG) << "fscrypt_destroy_user_storage for volume " << escape_empty(volume_uuid)
<< ", user " << user_id << ", flags " << flags;
bool res = true;
res &= prepare_subdirs("destroy", volume_uuid, user_id, flags);
if (flags & android::os::IVold::STORAGE_FLAG_CE) {
// CE_n key
auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
res &= destroy_dir(media_ce_path);
res &= destroy_dir(user_ce_path);
if (volume_uuid.empty()) {
res &= destroy_dir(system_ce_path);
res &= destroy_dir(misc_ce_path);
res &= destroy_dir(vendor_ce_path);
} else {
if (fscrypt_is_native()) {
res &= destroy_volkey(misc_ce_path, volume_uuid);
}
}
}
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
// DE_sys key
auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
// DE_n key
auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
res &= destroy_dir(user_de_path);
if (volume_uuid.empty()) {
res &= destroy_dir(system_legacy_path);
#if MANAGE_MISC_DIRS
res &= destroy_dir(misc_legacy_path);
#endif
res &= destroy_dir(profiles_de_path);
res &= destroy_dir(system_de_path);
res &= destroy_dir(misc_de_path);
res &= destroy_dir(vendor_de_path);
} else {
if (fscrypt_is_native()) {
res &= destroy_volkey(misc_de_path, volume_uuid);
}
}
}
return res;
}
static bool destroy_volume_keys(const std::string& directory_path, const std::string& volume_uuid) {
auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(directory_path.c_str()), closedir);
if (!dirp) {
PLOG(ERROR) << "Unable to open directory: " + directory_path;
return false;
}
bool res = true;
for (;;) {
errno = 0;
auto const entry = readdir(dirp.get());
if (!entry) {
if (errno) {
PLOG(ERROR) << "Unable to read directory: " + directory_path;
return false;
}
break;
}
if (IsDotOrDotDot(*entry)) continue;
if (entry->d_type != DT_DIR || entry->d_name[0] == '.') {
LOG(DEBUG) << "Skipping non-user " << entry->d_name;
continue;
}
res &= destroy_volkey(directory_path + "/" + entry->d_name, volume_uuid);
}
return res;
}
bool fscrypt_destroy_volume_keys(const std::string& volume_uuid) {
bool res = true;
LOG(DEBUG) << "fscrypt_destroy_volume_keys for volume " << escape_empty(volume_uuid);
auto secdiscardable_path = volume_secdiscardable_path(volume_uuid);
res &= android::vold::runSecdiscardSingle(secdiscardable_path);
res &= destroy_volume_keys("/data/misc_ce", volume_uuid);
res &= destroy_volume_keys("/data/misc_de", volume_uuid);
return res;
}
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