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platform_system_vold/vold_prepare_subdirs.cpp
Tianjie 570f0585b9 Create the checkin subdirectory under misc_ce 
We need some storage on the device to backup the token for checkin
services. So users won't lose the checkin tokens when they clear
the app's storage. If the device accidentally loses the
token without backup, it won't be able to checkin again until
factory reset.

Because we want the token to be user specific, put it under misc_ce
and let vold create the sub-directory.

Bug: 197636740
Test: boot device, check selinux label of the dir
Change-Id: I0e19dcb7f4feb98fd9d1013cfd84b56ff1325373
2021-10-05 22:17:22 -07:00

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/*
* Copyright (C) 2017 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.
*/
/*
* Tool to create a directory with the right SELinux context applied, or
* apply the context if it's absent. Also fixes mode, uid, gid.
*/
#include <iostream>
#include <string>
#include <vector>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <android-base/logging.h>
#include <android-base/scopeguard.h>
#include <cutils/fs.h>
#include <selinux/android.h>
#include "Utils.h"
#include "android/os/IVold.h"
#include <private/android_filesystem_config.h>
static void usage(const char* progname) {
std::cerr << "Usage: " << progname << " [ prepare | destroy ] <volume_uuid> <user_id> <flags>"
<< std::endl;
exit(-1);
}
static bool small_int(const std::string& s) {
return !s.empty() && s.size() < 7 && s.find_first_not_of("0123456789") == std::string::npos;
}
static bool valid_uuid(const std::string& s) {
return s.size() < 40 && s.find_first_not_of("0123456789abcdefABCDEF-_") == std::string::npos;
}
static bool prepare_dir_for_user(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
const std::string& path, uid_t user_id) {
auto clearfscreatecon = android::base::make_scope_guard([] { setfscreatecon(nullptr); });
auto secontext = std::unique_ptr<char, void (*)(char*)>(nullptr, freecon);
if (sehandle) {
char* tmp_secontext;
if (selabel_lookup(sehandle, &tmp_secontext, path.c_str(), S_IFDIR) == 0) {
secontext.reset(tmp_secontext);
if (user_id != (uid_t)-1) {
if (selinux_android_context_with_level(secontext.get(), &tmp_secontext, user_id,
(uid_t)-1) != 0) {
PLOG(ERROR) << "Unable to create context with level for: " << path;
return false;
}
secontext.reset(tmp_secontext); // Free the context
}
}
}
LOG(DEBUG) << "Setting up mode " << std::oct << mode << std::dec << " uid " << uid << " gid "
<< gid << " context " << (secontext ? secontext.get() : "null")
<< " on path: " << path;
if (secontext) {
if (setfscreatecon(secontext.get()) != 0) {
PLOG(ERROR) << "Unable to setfscreatecon for: " << path;
return false;
}
}
if (fs_prepare_dir(path.c_str(), mode, uid, gid) != 0) {
return false;
}
if (secontext) {
char* tmp_oldsecontext = nullptr;
if (lgetfilecon(path.c_str(), &tmp_oldsecontext) < 0) {
PLOG(ERROR) << "Unable to read secontext for: " << path;
return false;
}
auto oldsecontext = std::unique_ptr<char, void (*)(char*)>(tmp_oldsecontext, freecon);
if (strcmp(secontext.get(), oldsecontext.get()) != 0) {
LOG(INFO) << "Relabelling from " << ((char*)oldsecontext.get()) << " to "
<< ((char*)secontext.get()) << ": " << path;
if (lsetfilecon(path.c_str(), secontext.get()) != 0) {
PLOG(ERROR) << "Relabelling failed for: " << path;
return false;
}
}
}
return true;
}
static bool prepare_dir(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
const std::string& path) {
return prepare_dir_for_user(sehandle, mode, uid, gid, path, (uid_t)-1);
}
static bool rmrf_contents(const std::string& path) {
auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(path.c_str()), closedir);
if (!dirp) {
PLOG(ERROR) << "Unable to open directory: " << path;
return false;
}
bool res = true;
for (;;) {
errno = 0;
auto const entry = readdir(dirp.get());
if (!entry) {
if (errno) {
PLOG(ERROR) << "readdir failed on: " << path;
return false;
}
return res;
}
if (entry->d_name[0] == '.') continue;
auto subdir = path + "/" + entry->d_name;
if (0 !=
android::vold::ForkExecvp(std::vector<std::string>{"/system/bin/rm", "-rf", subdir})) {
LOG(ERROR) << "rm -rf failed on " << subdir;
res = false;
}
}
}
static bool prepare_apex_subdirs(struct selabel_handle* sehandle, const std::string& path) {
if (!prepare_dir(sehandle, 0711, 0, 0, path + "/apexdata")) return false;
auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir("/apex"), closedir);
if (!dirp) {
PLOG(ERROR) << "Unable to open apex directory";
return false;
}
struct dirent* entry;
while ((entry = readdir(dirp.get())) != nullptr) {
if (entry->d_type != DT_DIR) continue;
const char* name = entry->d_name;
// skip any starting with "."
if (name[0] == '.') continue;
if (strchr(name, '@') != NULL) continue;
if (!prepare_dir(sehandle, 0771, AID_ROOT, AID_SYSTEM, path + "/apexdata/" + name)) {
return false;
}
}
return true;
}
static bool prepare_subdirs(const std::string& volume_uuid, int user_id, int flags) {
struct selabel_handle* sehandle = selinux_android_file_context_handle();
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, user_de_path, user_id)) {
return false;
}
if (volume_uuid.empty()) {
auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/vold")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/storaged")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/rollback")) return false;
// TODO: Return false if this returns false once sure this should succeed.
prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/apexrollback");
prepare_apex_subdirs(sehandle, misc_de_path);
auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, profiles_de_path,
user_id)) {
return false;
}
auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, vendor_de_path + "/fpdata")) {
return false;
}
auto facedata_path = vendor_de_path + "/facedata";
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, facedata_path)) {
return false;
}
}
}
if (flags & android::os::IVold::STORAGE_FLAG_CE) {
auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, user_ce_path, user_id)) {
return false;
}
if (volume_uuid.empty()) {
auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/vold")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/storaged")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/rollback")) return false;
if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/checkin")) return false;
// TODO: Return false if this returns false once sure this should succeed.
prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/apexrollback");
prepare_apex_subdirs(sehandle, misc_ce_path);
auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, system_ce_path + "/backup")) {
return false;
}
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM,
system_ce_path + "/backup_stage")) {
return false;
}
auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
auto facedata_path = vendor_ce_path + "/facedata";
if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, facedata_path)) {
return false;
}
}
}
return true;
}
static bool destroy_subdirs(const std::string& volume_uuid, int user_id, int flags) {
bool res = true;
if (volume_uuid.empty()) {
if (flags & android::os::IVold::STORAGE_FLAG_CE) {
auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
res &= rmrf_contents(misc_ce_path);
auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
res &= rmrf_contents(vendor_ce_path);
}
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
res &= rmrf_contents(misc_de_path);
auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
res &= rmrf_contents(vendor_de_path);
}
}
return res;
}
int main(int argc, const char* const argv[]) {
android::base::InitLogging(const_cast<char**>(argv));
std::vector<std::string> args(argv + 1, argv + argc);
if (args.size() != 4 || !valid_uuid(args[1]) || !small_int(args[2]) || !small_int(args[3])) {
usage(argv[0]);
return -1;
}
auto volume_uuid = args[1];
int user_id = stoi(args[2]);
int flags = stoi(args[3]);
if (args[0] == "prepare") {
if (!prepare_subdirs(volume_uuid, user_id, flags)) return -1;
} else if (args[0] == "destroy") {
if (!destroy_subdirs(volume_uuid, user_id, flags)) return -1;
} else {
usage(argv[0]);
return -1;
}
return 0;
}
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