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Two phases to set the password for disk encryption

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am: a363036b44

* commit 'a363036b44f7f140aa9a943578f56abff5880a60':
  Two phases to set the password for disk encryption

Change-Id: I37368c698abcf4b541f924cb18927f4645edcb3f
This commit is contained in:
Paul Crowley 2016-05-18 22:59:57 +00:00 committed by android-build-merger
commit ad4dcc2ff6
3 changed files with 138 additions and 43 deletions
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13
CryptCommandListener.cpp
View file

@ -385,11 +385,14 @@ int CryptCommandListener::CryptfsCmd::runCommand(SocketClient *cli,
if (!check_argc(cli, subcommand, argc, 3, "<user>")) return 0;
return sendGenericOkFailOnBool(cli, e4crypt_destroy_user_key(atoi(argv[2])));
} else if (subcommand == "change_user_key") {
if (!check_argc(cli, subcommand, argc, 7,
"<user> <serial> <token> <old_secret> <new_secret>")) return 0;
return sendGenericOkFailOnBool(cli, e4crypt_change_user_key(
atoi(argv[2]), atoi(argv[3]), argv[4], argv[5], argv[6]));
} else if (subcommand == "add_user_key_auth") {
if (!check_argc(cli, subcommand, argc, 6, "<user> <serial> <token> <secret>")) return 0;
return sendGenericOkFailOnBool(cli, e4crypt_add_user_key_auth(
atoi(argv[2]), atoi(argv[3]), argv[4], argv[5]));
} else if (subcommand == "fixate_newest_user_key_auth") {
if (!check_argc(cli, subcommand, argc, 3, "<user>")) return 0;
return sendGenericOkFailOnBool(cli, e4crypt_fixate_newest_user_key_auth(atoi(argv[2])));
} else if (subcommand == "unlock_user_key") {
if (!check_argc(cli, subcommand, argc, 6, "<user> <serial> <token> <secret>")) return 0;

163
Ext4Crypt.cpp
View file

@ -19,6 +19,7 @@
#include "KeyStorage.h"
#include "Utils.h"
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
@ -28,6 +29,7 @@
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <openssl/sha.h>
#include <selinux/android.h>
#include <stdio.h>
@ -175,16 +177,100 @@ 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_path(userid_t user_id) {
return StringPrintf("%s/ce/%d/current", 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 (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;
}
}
}
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;
const auto ce_key_path = get_ce_key_path(user_id);
std::string ce_key;
if (!android::vold::retrieveKey(ce_key_path, auth, &ce_key)) return false;
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;
@ -252,12 +338,17 @@ static bool create_and_install_user_keys(userid_t user_id, bool 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 (!store_key(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 (!store_key(get_de_key_path(user_id), user_key_temp,
kEmptyAuthentication, de_key)) return false;
if (!prepare_dir(user_key_dir + "/ce/" + std::to_string(user_id),
0700, AID_ROOT, AID_ROOT)) return false;
if (!store_key(get_ce_key_path(user_id), user_key_temp,
kEmptyAuthentication, ce_key)) return false;
}
std::string de_raw_ref;
if (!install_key(de_key, &de_raw_ref)) return false;
@ -374,15 +465,7 @@ bool e4crypt_init_user0() {
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;
auto de_path = get_de_key_path(0);
auto ce_path = get_ce_key_path(0);
if (!path_exists(de_path) || !path_exists(ce_path)) {
if (path_exists(de_path)) {
android::vold::destroyKey(de_path); // May be partially created so ignore errors
}
if (path_exists(ce_path)) {
android::vold::destroyKey(ce_path); // May be partially created so ignore errors
}
if (!path_exists(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
@ -456,7 +539,9 @@ bool e4crypt_destroy_user_key(userid_t user_id) {
if (it != s_ephemeral_users.end()) {
s_ephemeral_users.erase(it);
} else {
success &= android::vold::destroyKey(get_ce_key_path(user_id));
for (auto const path: get_ce_key_paths(get_ce_key_directory_path(user_id))) {
success &= android::vold::destroyKey(path);
}
success &= android::vold::destroyKey(get_de_key_path(user_id));
}
return success;
@ -504,35 +589,41 @@ static bool parse_hex(const char* hex, std::string* result) {
return true;
}
bool e4crypt_change_user_key(userid_t user_id, int serial, const char* token_hex,
const char* old_secret_hex, const char* new_secret_hex) {
LOG(DEBUG) << "e4crypt_change_user_key " << user_id << " serial=" << serial
bool e4crypt_add_user_key_auth(userid_t user_id, int serial, const char* token_hex,
const char* secret_hex) {
LOG(DEBUG) << "e4crypt_add_user_key_auth " << user_id << " serial=" << serial
<< " token_present=" << (strcmp(token_hex, "!") != 0);
if (!e4crypt_is_native()) return true;
if (s_ephemeral_users.count(user_id) != 0) return true;
std::string token, old_secret, new_secret;
std::string token, secret;
if (!parse_hex(token_hex, &token)) return false;
if (!parse_hex(old_secret_hex, &old_secret)) return false;
if (!parse_hex(new_secret_hex, &new_secret)) return false;
auto old_auth = old_secret.empty() ? kEmptyAuthentication
: android::vold::KeyAuthentication(token, old_secret);
auto new_auth = new_secret.empty() ? kEmptyAuthentication
: android::vold::KeyAuthentication(token, new_secret);
if (!parse_hex(secret_hex, &secret)) return false;
auto auth = secret.empty() ? kEmptyAuthentication
: android::vold::KeyAuthentication(token, secret);
auto it = s_ce_keys.find(user_id);
if (it == s_ce_keys.end()) {
LOG(ERROR) << "Key not loaded into memory, can't change for user " << user_id;
return false;
}
auto ce_key = it->second;
auto ce_key_path = get_ce_key_path(user_id);
std::string trial_key;
if (!android::vold::retrieveKey(ce_key_path, old_auth, &trial_key)) {
LOG(WARNING) << "change_user_key wasn't given enough info to reconstruct the key";
} else if (ce_key != trial_key) {
LOG(WARNING) << "Reconstructed key != stored key";
auto const directory_path = get_ce_key_directory_path(user_id);
auto const paths = get_ce_key_paths(directory_path);
std::string ce_key_path;
if (!get_ce_key_new_path(directory_path, paths, &ce_key_path)) return false;
if (!store_key(ce_key_path, user_key_temp, auth, ce_key)) return false;
return true;
}
bool e4crypt_fixate_newest_user_key_auth(userid_t user_id) {
LOG(DEBUG) << "e4crypt_fixate_newest_user_key_auth " << user_id;
if (!e4crypt_is_native()) 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;
}
android::vold::destroyKey(ce_key_path);
if (!store_key(ce_key_path, user_key_temp, new_auth, ce_key)) return false;
fixate_user_ce_key(directory_path, paths[0], paths);
return true;
}

5
Ext4Crypt.h
View file

@ -28,8 +28,9 @@ bool e4crypt_initialize_global_de();
bool e4crypt_init_user0();
bool e4crypt_vold_create_user_key(userid_t user_id, int serial, bool ephemeral);
bool e4crypt_destroy_user_key(userid_t user_id);
bool e4crypt_change_user_key(userid_t user_id, int serial, const char* token,
const char* old_secret, const char* new_secret);
bool e4crypt_add_user_key_auth(userid_t user_id, int serial, const char* token,
const char* secret);
bool e4crypt_fixate_newest_user_key_auth(userid_t user_id);
bool e4crypt_unlock_user_key(userid_t user_id, int serial, const char* token, const char* secret);
bool e4crypt_lock_user_key(userid_t user_id);