/*
* 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 "Ext4Crypt.h"
#include "Decrypt.h"
#ifdef USE_KEYSTORAGE_3
#include "KeyStorage3.h"
#else
#include "KeyStorage.h"
#endif
#include "Utils.h"
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <sstream>
#include <string>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <openssl/sha.h>
#include <selinux/android.h>
#include <stdio.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <iostream>
#include <private/android_filesystem_config.h>
#ifdef HAVE_SYNTH_PWD_SUPPORT
#include <ext4_utils/ext4_crypt.h>
#else
#include "ext4_crypt.h"
#endif
#ifndef HAVE_LIBKEYUTILS
#include "key_control.h"
#else
#include <keyutils.h>
#endif
#include <hardware/gatekeeper.h>
#include "HashPassword.h"
#define EMULATED_USES_SELINUX 0
#define MANAGE_MISC_DIRS 0
#include <cutils/fs.h>
#include <android-base/file.h>
//#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#define LOG(x) std::cout
#define PLOG(x) std::cout
#define DATA_MNT_POINT "/data"
using android::base::StringPrintf;
using android::vold::kEmptyAuthentication;
// NOTE: keep in sync with StorageManager
//static constexpr int FLAG_STORAGE_DE = 1 << 0; // moved to Decrypt.h
//static constexpr int FLAG_STORAGE_CE = 1 << 1;
// Store main DE raw ref / policy
std::string de_raw_ref;
// Map user ids to key references
std::map<userid_t, std::string> s_de_key_raw_refs;
std::map<userid_t, std::string> s_ce_key_raw_refs;
namespace {
const std::string device_key_dir = std::string() + DATA_MNT_POINT + e4crypt_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";
bool s_global_de_initialized = false;
// Some users are ephemeral, don't try to wipe their keys from disk
std::set<userid_t> s_ephemeral_users;
// TODO abolish this map. Keys should not be long-lived in user memory, only kernel memory.
// See b/26948053
std::map<userid_t, std::string> s_ce_keys;
// ext4enc:TODO get this const from somewhere good
const int EXT4_KEY_DESCRIPTOR_SIZE = 8;
// ext4enc:TODO Include structure from somewhere sensible
// MUST be in sync with ext4_crypto.c in kernel
constexpr int EXT4_ENCRYPTION_MODE_AES_256_XTS = 1;
constexpr int EXT4_AES_256_XTS_KEY_SIZE = 64;
constexpr int EXT4_MAX_KEY_SIZE = 64;
struct ext4_encryption_key {
uint32_t mode;
char raw[EXT4_MAX_KEY_SIZE];
uint32_t size;
};
}
static bool e4crypt_is_emulated() {
return false; //property_get_bool("persist.sys.emulate_fbe", false);
}
static const char* escape_null(const char* value) {
return (value == nullptr) ? "null" : value;
}
// Get raw keyref - used to make keyname and to pass to ioctl
static std::string generate_key_ref(const char* key, int length) {
SHA512_CTX c;
SHA512_Init(&c);
SHA512_Update(&c, key, length);
unsigned char key_ref1[SHA512_DIGEST_LENGTH];
SHA512_Final(key_ref1, &c);
SHA512_Init(&c);
SHA512_Update(&c, key_ref1, SHA512_DIGEST_LENGTH);
unsigned char key_ref2[SHA512_DIGEST_LENGTH];
SHA512_Final(key_ref2, &c);
static_assert(EXT4_KEY_DESCRIPTOR_SIZE <= SHA512_DIGEST_LENGTH,
"Hash too short for descriptor");
return std::string((char*)key_ref2, EXT4_KEY_DESCRIPTOR_SIZE);
}
static bool fill_key(const std::string& key, ext4_encryption_key* ext4_key) {
if (key.size() != EXT4_AES_256_XTS_KEY_SIZE) {
LOG(ERROR) << "Wrong size key " << key.size();
return false;
}
static_assert(EXT4_AES_256_XTS_KEY_SIZE <= sizeof(ext4_key->raw), "Key too long!");
ext4_key->mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
ext4_key->size = key.size();
memset(ext4_key->raw, 0, sizeof(ext4_key->raw));
memcpy(ext4_key->raw, key.data(), key.size());
return true;
}
static std::string keyname(const std::string& raw_ref) {
std::ostringstream o;
o << "ext4:";
for (auto i : raw_ref) {
o << std::hex << std::setw(2) << std::setfill('0') << (int)i;
}
LOG(INFO) << "keyname is " << o.str() << "\n";
return o.str();
}
// Get the keyring we store all keys in
static bool e4crypt_keyring(key_serial_t* device_keyring) {
*device_keyring = keyctl_search(KEY_SPEC_SESSION_KEYRING, "keyring", "e4crypt", 0);
if (*device_keyring == -1) {
PLOG(ERROR) << "Unable to find device keyring\n";
return false;
}
return true;
}
// Install password into global keyring
// Return raw key reference for use in policy
static bool install_key(const std::string& key, std::string* raw_ref) {
ext4_encryption_key ext4_key;
if (!fill_key(key, &ext4_key)) return false;
*raw_ref = generate_key_ref(ext4_key.raw, ext4_key.size);
auto ref = keyname(*raw_ref);
key_serial_t device_keyring;
if (!e4crypt_keyring(&device_keyring)) return false;
key_serial_t key_id =
add_key("logon", ref.c_str(), (void*)&ext4_key, sizeof(ext4_key), device_keyring);
if (key_id == -1) {
PLOG(ERROR) << "Failed to insert key into keyring " << device_keyring << "\n";
return false;
}
LOG(DEBUG) << "Added key " << key_id << " (" << ref << ") to keyring " << device_keyring
<< " in process " << getpid() << "\n";
return true;
}
static std::string get_de_key_path(userid_t user_id) {
LOG(INFO) << "get_de_key_path " << user_id << " " << StringPrintf("%s/de/%d", user_key_dir.c_str(), user_id) << "\n";
return StringPrintf("%s/de/%d", user_key_dir.c_str(), user_id);
}
static std::string get_ce_key_directory_path(userid_t user_id) {
LOG(INFO) << "get_ce_key_directory_path " << user_id << ": " << StringPrintf("%s/ce/%d", user_key_dir.c_str(), user_id) << "\n";
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 (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);
LOG(INFO) << "get_ce_key_paths adding: " << directory_path + "/" + entry->d_name << "\n";
}
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) {
LOG(INFO) << "get_ce_key_current_path: " << directory_path + "/current\n";
return directory_path + "/current";
}
// 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;
}
}
}
static bool read_and_fixate_user_ce_key(userid_t user_id,
const android::vold::KeyAuthentication& auth,
std::string *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 (android::vold::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 read_and_install_user_ce_key(userid_t user_id,
const android::vold::KeyAuthentication& auth) {
if (s_ce_key_raw_refs.count(user_id) != 0) return true;
std::string ce_key;
if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;
std::string ce_raw_ref;
if (!install_key(ce_key, &ce_raw_ref)) return false;
s_ce_keys[user_id] = ce_key;
s_ce_key_raw_refs[user_id] = ce_raw_ref;
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 << "\n";
return true;
return access(dir.c_str(), F_OK) == 0; // we don't want recovery creating directories or changing permissions at this point, so we will just return true if the path already exists
if (fs_prepare_dir(dir.c_str(), mode, uid, gid) != 0) {
PLOG(ERROR) << "Failed to prepare " << dir;
return false;
}
return true;
}
static bool path_exists(const std::string& path) {
return access(path.c_str(), F_OK) == 0;
}
bool lookup_key_ref(const std::map<userid_t, std::string>& key_map, userid_t user_id,
std::string* raw_ref) {
auto refi = key_map.find(user_id);
if (refi == key_map.end()) {
LOG(ERROR) << "Cannot find key for " << user_id;
return false;
}
*raw_ref = refi->second;
return true;
}
static bool ensure_policy(const std::string& raw_ref __unused, const std::string& path) {
return true;
// ensure policy will set a policy if one is not set on an empty folder - we don't want to do this in recovery
/*if (e4crypt_policy_ensure(path.c_str(), raw_ref.data(), raw_ref.size()) != 0) {
LOG(ERROR) << "Failed to set policy on: " << path << "\n";
return false;
}
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 (entry->d_type != DT_DIR || !is_numeric(entry->d_name)) {
LOG(DEBUG) << "Skipping non-de-key " << entry->d_name;
continue;
}
userid_t user_id = atoi(entry->d_name);
if (s_de_key_raw_refs.count(user_id) == 0) {
auto key_path = de_dir + "/" + entry->d_name;
std::string key;
if (!android::vold::retrieveKey(key_path, kEmptyAuthentication, &key)) return false;
std::string raw_ref;
if (!install_key(key, &raw_ref)) return false;
s_de_key_raw_refs[user_id] = raw_ref;
LOG(DEBUG) << "Installed de key for user " << user_id;
}
}
// ext4enc: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 e4crypt_initialize_global_de() {
if (s_global_de_initialized) {
LOG(INFO) << "Already initialized\n";
return true;
}
std::string device_key;
if (path_exists(device_key_path)) {
if (!android::vold::retrieveKey(device_key_path,
kEmptyAuthentication, &device_key)) return false;
} else {
LOG(INFO) << "NOT Creating new key\n";
return false;
}
std::string device_key_ref;
if (!install_key(device_key, &device_key_ref)) {
LOG(ERROR) << "Failed to install device key\n";
return false;
}
s_global_de_initialized = true;
de_raw_ref = device_key_ref;
return true;
}
bool e4crypt_init_user0() {
if (e4crypt_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 (!path_exists(get_de_key_path(0))) {
//if (!create_and_install_user_keys(0, false)) return false;
printf("de key path not found\n");
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 (!e4crypt_prepare_user_storage(nullptr, 0, 0, FLAG_STORAGE_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 (!e4crypt_is_native() && !e4crypt_is_emulated()) {
e4crypt_unlock_user_key(0, 0, "!", "!");
}
return true;
}
static bool parse_hex(const char* hex, std::string* result) {
if (strcmp("!", hex) == 0) {
*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;
}
// TODO: rename to 'install' for consistency, and take flags to know which keys to install
bool e4crypt_unlock_user_key(userid_t user_id, int serial __unused, const char* token_hex,
const char* secret_hex) {
if (e4crypt_is_native()) {
if (s_ce_key_raw_refs.count(user_id) != 0) {
LOG(WARNING) << "Tried to unlock already-unlocked key for user " << user_id;
return true;
}
std::string token, secret;
if (!parse_hex(token_hex, &token)) return false;
if (!parse_hex(secret_hex, &secret)) return false;
android::vold::KeyAuthentication auth(token, secret);
if (!read_and_install_user_ce_key(user_id, auth)) {
LOG(ERROR) << "Couldn't read key for " << user_id;
return false;
}
} else {
printf("Emulation mode not supported in TWRP\n");
// 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(nullptr, user_id), 0770) ||
!emulated_unlock(android::vold::BuildDataUserCePath(nullptr, user_id), 0771)) {
LOG(ERROR) << "Failed to unlock user " << user_id;
return false;
}*/
}
return true;
}
bool e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, int serial __unused,
int flags) {
if (flags & FLAG_STORAGE_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);
auto foreign_de_path = android::vold::BuildDataProfilesForeignDexDePath(user_id);
// DE_n key
auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
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(foreign_de_path, 0773, 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(user_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
// For now, FBE is only supported on internal storage
if (e4crypt_is_native() && volume_uuid == nullptr) {
std::string de_raw_ref;
if (!lookup_key_ref(s_de_key_raw_refs, user_id, &de_raw_ref)) return false;
if (!ensure_policy(de_raw_ref, system_de_path)) return false;
if (!ensure_policy(de_raw_ref, misc_de_path)) return false;
if (!ensure_policy(de_raw_ref, user_de_path)) return false;
}
}
if (flags & FLAG_STORAGE_CE) {
// CE_n key
auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
auto misc_ce_path = android::vold::BuildDataMiscCePath(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 (!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(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;
// For now, FBE is only supported on internal storage
if (e4crypt_is_native() && volume_uuid == nullptr) {
std::string ce_raw_ref;
if (!lookup_key_ref(s_ce_key_raw_refs, user_id, &ce_raw_ref)) return false;
if (!ensure_policy(ce_raw_ref, system_ce_path)) return false;
if (!ensure_policy(ce_raw_ref, misc_ce_path)) return false;
if (!ensure_policy(ce_raw_ref, media_ce_path)) return false;
if (!ensure_policy(ce_raw_ref, user_ce_path)) return false;
}
}
return true;
}
