/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <dirent.h>
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#include <selinux/selinux.h>
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#include <sys/mount.h>
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#include <unistd.h>
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#include <memory>
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#include <string>
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#include <vector>
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#include <android-base/logging.h>
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#include <android-base/properties.h>
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#include <fs_mgr_overlayfs.h>
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#include <fs_mgr_vendor_overlay.h>
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#include <fstab/fstab.h>
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#include "fs_mgr_priv.h"
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using namespace std::literals;
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namespace {
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// The order of the list means the priority to show the files in the directory.
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// The last one has the highest priority.
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const std::vector<const std::string> kVendorOverlaySourceDirs = {
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"/system/vendor_overlay/",
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"/product/vendor_overlay/",
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};
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const auto kVndkVersionPropertyName = "ro.vndk.version"s;
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const auto kVendorTopDir = "/vendor/"s;
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const auto kLowerdirOption = "lowerdir="s;
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std::vector<std::pair<std::string, std::string>> fs_mgr_get_vendor_overlay_dirs(
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const std::string& vndk_version) {
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std::vector<std::pair<std::string, std::string>> vendor_overlay_dirs;
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for (const auto& vendor_overlay_source : kVendorOverlaySourceDirs) {
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const auto overlay_top = vendor_overlay_source + vndk_version;
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std::unique_ptr<DIR, decltype(&closedir)> vendor_overlay_top(opendir(overlay_top.c_str()),
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closedir);
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if (!vendor_overlay_top) continue;
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// Vendor overlay root for current vendor version found!
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LINFO << "vendor overlay root: " << overlay_top;
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struct dirent* dp;
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while ((dp = readdir(vendor_overlay_top.get())) != nullptr) {
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if (dp->d_type != DT_DIR || dp->d_name[0] == '.') {
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continue;
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}
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vendor_overlay_dirs.emplace_back(overlay_top, dp->d_name);
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}
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}
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return vendor_overlay_dirs;
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}
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bool fs_mgr_vendor_overlay_mount(const std::pair<std::string, std::string>& mount_point) {
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const auto [overlay_top, mount_dir] = mount_point;
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const auto vendor_mount_point = kVendorTopDir + mount_dir;
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LINFO << "vendor overlay mount on " << vendor_mount_point;
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const auto target_context = fs_mgr_get_context(vendor_mount_point);
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if (target_context.empty()) {
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PERROR << " failed: cannot find the target vendor mount point";
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return false;
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}
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const auto source_directory = overlay_top + "/" + mount_dir;
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const auto source_context = fs_mgr_get_context(source_directory);
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if (target_context != source_context) {
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LERROR << " failed: source and target contexts do not match (source:" << source_context
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<< ", target:" << target_context << ")";
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return false;
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}
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auto options = kLowerdirOption + source_directory + ":" + vendor_mount_point;
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if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kOverrideCredsRequired) {
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options += ",override_creds=off";
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}
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auto report = "__mount(source=overlay,target="s + vendor_mount_point + ",type=overlay," +
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options + ")=";
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auto ret = mount("overlay", vendor_mount_point.c_str(), "overlay", MS_RDONLY | MS_RELATIME,
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options.c_str());
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if (ret) {
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PERROR << report << ret;
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return false;
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} else {
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LINFO << report << ret;
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return true;
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}
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}
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} // namespace
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// Since the vendor overlay requires to know the version of the vendor partition,
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// it is not possible to mount vendor overlay at the first stage that cannot
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// initialize properties.
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// To read the properties, vendor overlay must be mounted at the second stage, right
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// after "property_load_boot_defaults()" is called.
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bool fs_mgr_vendor_overlay_mount_all() {
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// To read the property, it must be called at the second init stage after the default
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// properties are loaded.
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static const auto vndk_version = android::base::GetProperty(kVndkVersionPropertyName, "");
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if (vndk_version.empty()) {
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LINFO << "vendor overlay: vndk version not defined";
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return false;
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}
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const auto vendor_overlay_dirs = fs_mgr_get_vendor_overlay_dirs(vndk_version);
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if (vendor_overlay_dirs.empty()) return true;
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if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
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LINFO << "vendor overlay: kernel does not support overlayfs";
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return false;
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}
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// Mount each directory in /(system|product)/vendor_overlay/<ver> on /vendor
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auto ret = true;
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for (const auto& vendor_overlay_dir : vendor_overlay_dirs) {
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if (!fs_mgr_vendor_overlay_mount(vendor_overlay_dir)) {
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ret = false;
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}
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}
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return ret;
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}
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