crypto/ext4crypt/Ext4Crypt.cpp - android_bootable_recovery - Gitiles

 /*
  * 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) {
     LOG(INFO) << "ensure_policy '" << path << "'\n";
     return true;
     return access(path.c_str(), F_OK) == 0; // 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;
 }
	/*
	* 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) {
	LOG(INFO) << "ensure_policy '" << path << "'\n";
	return true;
	return access(path.c_str(), F_OK) == 0; // 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;
	}