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platform_system_vold/vold_prepare_subdirs.cpp
Oli Lan 9cfc404c2d Change ownership of apex data directories to root. 
The apex data directories must be accessed by apexd in order for it to
perform snapshot and restore as part of the rollback process. As apexd
runs as root, this CL changes the apex data directories under misc_[ce|de]
to be owned by root.

Bug: 141148175
Test: Build and flash; check permissions are set correctly.
Change-Id: Icf2059cc9448364f834eef7892914a99883746a1
2020-01-17 11:11:06 +00:00

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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(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
const std::string& path) {
auto clearfscreatecon = android::base::make_scope_guard([] { setfscreatecon(nullptr); });
auto secontext = std::unique_ptr<char, void (*)(char*)>(nullptr, freecon);
char* tmp_secontext;
if (sehandle && selabel_lookup(sehandle, &tmp_secontext, path.c_str(), S_IFDIR) == 0) {
secontext.reset(tmp_secontext);
}
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 read 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 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, 0700, 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, 0770, 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 (volume_uuid.empty()) {
if (flags & android::os::IVold::STORAGE_FLAG_DE) {
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 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 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;
// 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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