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/*
* Copyright (C) 2018 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 <dirent.h>
#include <selinux/selinux.h>
#include <sys/mount.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <vector>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <fs_mgr_overlayfs.h>
#include <fs_mgr_vendor_overlay.h>
#include <fstab/fstab.h>
#include "fs_mgr_priv.h"
using namespace std::literals;
namespace {
// The order of the list means the priority to show the files in the directory.
// The last one has the highest priority.
const std::vector<const std::string> kVendorOverlaySourceDirs = {
"/system/vendor_overlay/",
"/product/vendor_overlay/",
};
const auto kVndkVersionPropertyName = "ro.vndk.version"s;
const auto kVendorTopDir = "/vendor/"s;
const auto kLowerdirOption = "lowerdir="s;
std::vector<std::pair<std::string, std::string>> fs_mgr_get_vendor_overlay_dirs(
const std::string& vndk_version) {
std::vector<std::pair<std::string, std::string>> vendor_overlay_dirs;
for (const auto& vendor_overlay_source : kVendorOverlaySourceDirs) {
const auto overlay_top = vendor_overlay_source + vndk_version;
std::unique_ptr<DIR, decltype(&closedir)> vendor_overlay_top(opendir(overlay_top.c_str()),
closedir);
if (!vendor_overlay_top) continue;
// Vendor overlay root for current vendor version found!
LINFO << "vendor overlay root: " << overlay_top;
struct dirent* dp;
while ((dp = readdir(vendor_overlay_top.get())) != nullptr) {
if (dp->d_type != DT_DIR || dp->d_name[0] == '.') {
continue;
}
vendor_overlay_dirs.emplace_back(overlay_top, dp->d_name);
}
}
return vendor_overlay_dirs;
}
bool fs_mgr_vendor_overlay_mount(const std::pair<std::string, std::string>& mount_point) {
const auto [overlay_top, mount_dir] = mount_point;
const auto vendor_mount_point = kVendorTopDir + mount_dir;
LINFO << "vendor overlay mount on " << vendor_mount_point;
const auto target_context = fs_mgr_get_context(vendor_mount_point);
if (target_context.empty()) {
PERROR << " failed: cannot find the target vendor mount point";
return false;
}
const auto source_directory = overlay_top + "/" + mount_dir;
const auto source_context = fs_mgr_get_context(source_directory);
if (target_context != source_context) {
LERROR << " failed: source and target contexts do not match (source:" << source_context
<< ", target:" << target_context << ")";
return false;
}
auto options = kLowerdirOption + source_directory + ":" + vendor_mount_point;
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kOverrideCredsRequired) {
options += ",override_creds=off";
}
auto report = "__mount(source=overlay,target="s + vendor_mount_point + ",type=overlay," +
options + ")=";
auto ret = mount("overlay", vendor_mount_point.c_str(), "overlay", MS_RDONLY | MS_RELATIME,
options.c_str());
if (ret) {
PERROR << report << ret;
return false;
} else {
LINFO << report << ret;
return true;
}
}
} // namespace
// Since the vendor overlay requires to know the version of the vendor partition,
// it is not possible to mount vendor overlay at the first stage that cannot
// initialize properties.
// To read the properties, vendor overlay must be mounted at the second stage, right
// after "property_load_boot_defaults()" is called.
bool fs_mgr_vendor_overlay_mount_all() {
// To read the property, it must be called at the second init stage after the default
// properties are loaded.
static const auto vndk_version = android::base::GetProperty(kVndkVersionPropertyName, "");
if (vndk_version.empty()) {
LINFO << "vendor overlay: vndk version not defined";
return false;
}
const auto vendor_overlay_dirs = fs_mgr_get_vendor_overlay_dirs(vndk_version);
if (vendor_overlay_dirs.empty()) return true;
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
LINFO << "vendor overlay: kernel does not support overlayfs";
return false;
}
// Mount each directory in /(system|product)/vendor_overlay/<ver> on /vendor
auto ret = true;
for (const auto& vendor_overlay_dir : vendor_overlay_dirs) {
if (!fs_mgr_vendor_overlay_mount(vendor_overlay_dir)) {
ret = false;
}
}
return ret;
}
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