/*
* 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 <errno.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <selinux/selinux.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <sys/vfs.h>
#include <unistd.h>
#include <algorithm>
#include <memory>
#include <optional>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/macros.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <ext4_utils/ext4_utils.h>
#include <fs_mgr.h>
#include <fs_mgr/file_wait.h>
#include <fs_mgr_dm_linear.h>
#include <fs_mgr_overlayfs.h>
#include <fstab/fstab.h>
#include <libdm/dm.h>
#include <libfiemap/image_manager.h>
#include <libgsi/libgsi.h>
#include <liblp/builder.h>
#include <liblp/liblp.h>
#include <storage_literals/storage_literals.h>
#include "fs_mgr_priv.h"
#include "fs_mgr_priv_overlayfs.h"
#include "libfiemap/utility.h"
using namespace std::literals;
using namespace android::dm;
using namespace android::fs_mgr;
using namespace android::storage_literals;
using android::fiemap::FilesystemHasReliablePinning;
using android::fiemap::IImageManager;
namespace {
constexpr char kDataScratchSizeMbProp[] = "fs_mgr.overlayfs.data_scratch_size_mb";
constexpr char kPreferCacheBackingStorageProp[] = "fs_mgr.overlayfs.prefer_cache_backing_storage";
bool fs_mgr_access(const std::string& path) {
return access(path.c_str(), F_OK) == 0;
}
const auto kLowerdirOption = "lowerdir="s;
const auto kUpperdirOption = "upperdir="s;
bool fs_mgr_in_recovery() {
// Check the existence of recovery binary instead of using the compile time
// __ANDROID_RECOVERY__ macro.
// If BOARD_USES_RECOVERY_AS_BOOT is true, both normal and recovery boot
// mode would use the same init binary, which would mean during normal boot
// the '/init' binary is actually a symlink pointing to
// init_second_stage.recovery, which would be compiled with
// __ANDROID_RECOVERY__ defined.
return fs_mgr_access("/system/bin/recovery");
}
bool fs_mgr_is_dsu_running() {
// Since android::gsi::CanBootIntoGsi() or android::gsi::MarkSystemAsGsi() is
// never called in recovery, the return value of android::gsi::IsGsiRunning()
// is not well-defined. In this case, just return false as being in recovery
// implies not running a DSU system.
if (fs_mgr_in_recovery()) return false;
return android::gsi::IsGsiRunning();
}
// list of acceptable overlayfs backing storage
const auto kScratchMountPoint = "/mnt/scratch"s;
const auto kCacheMountPoint = "/cache"s;
bool IsABDevice() {
return !android::base::GetProperty("ro.boot.slot_suffix", "").empty();
}
std::vector<const std::string> OverlayMountPoints() {
// Never fallback to legacy cache mount point if within a DSU system,
// because running a DSU system implies the device supports dynamic
// partitions, which means legacy cache mustn't be used.
if (fs_mgr_is_dsu_running()) {
return {kScratchMountPoint};
}
// For non-A/B devices prefer cache backing storage if
// kPreferCacheBackingStorageProp property set.
if (!IsABDevice() && android::base::GetBoolProperty(kPreferCacheBackingStorageProp, false) &&
android::base::GetIntProperty("ro.vendor.api_level", -1) < __ANDROID_API_T__) {
return {kCacheMountPoint, kScratchMountPoint};
}
return {kScratchMountPoint, kCacheMountPoint};
}
// Return true if everything is mounted, but before adb is started. Right
// after 'trigger load_persist_props_action' is done.
bool fs_mgr_boot_completed() {
return android::base::GetBoolProperty("ro.persistent_properties.ready", false);
}
bool fs_mgr_is_dir(const std::string& path) {
struct stat st;
return !stat(path.c_str(), &st) && S_ISDIR(st.st_mode);
}
bool fs_mgr_rw_access(const std::string& path) {
if (path.empty()) return false;
return access(path.c_str(), R_OK | W_OK) == 0;
}
// At less than 1% or 8MB of free space return value of false,
// means we will try to wrap with overlayfs.
bool fs_mgr_filesystem_has_space(const std::string& mount_point) {
// If we have access issues to find out space remaining, return true
// to prevent us trying to override with overlayfs.
struct statvfs vst;
if (statvfs(mount_point.c_str(), &vst)) {
PLOG(ERROR) << "statvfs " << mount_point;
return true;
}
static constexpr int kPercentThreshold = 1; // 1%
static constexpr unsigned long kSizeThreshold = 8 * 1024 * 1024; // 8MB
return (vst.f_bfree >= (vst.f_blocks * kPercentThreshold / 100)) &&
(static_cast<uint64_t>(vst.f_bfree) * vst.f_frsize) >= kSizeThreshold;
}
const auto kPhysicalDevice = "/dev/block/by-name/"s;
constexpr char kScratchImageMetadata[] = "/metadata/gsi/remount/lp_metadata";
// Note: this is meant only for recovery/first-stage init.
bool ScratchIsOnData() {
// The scratch partition of DSU is managed by gsid.
if (fs_mgr_is_dsu_running()) {
return false;
}
return fs_mgr_access(kScratchImageMetadata);
}
bool fs_mgr_update_blk_device(FstabEntry* entry) {
if (entry->fs_mgr_flags.logical) {
fs_mgr_update_logical_partition(entry);
}
if (fs_mgr_access(entry->blk_device)) {
return true;
}
if (entry->blk_device != "/dev/root") {
return false;
}
// special case for system-as-root (taimen and others)
auto blk_device = kPhysicalDevice + "system";
if (!fs_mgr_access(blk_device)) {
blk_device += fs_mgr_get_slot_suffix();
if (!fs_mgr_access(blk_device)) {
return false;
}
}
entry->blk_device = blk_device;
return true;
}
bool fs_mgr_has_shared_blocks(const std::string& mount_point, const std::string& dev) {
struct statfs fs;
if ((statfs((mount_point + "/lost+found").c_str(), &fs) == -1) ||
(fs.f_type != EXT4_SUPER_MAGIC)) {
return false;
}
android::base::unique_fd fd(open(dev.c_str(), O_RDONLY | O_CLOEXEC));
if (fd < 0) return false;
struct ext4_super_block sb;
if ((TEMP_FAILURE_RETRY(lseek64(fd, 1024, SEEK_SET)) < 0) ||
(TEMP_FAILURE_RETRY(read(fd, &sb, sizeof(sb))) < 0)) {
return false;
}
struct fs_info info;
if (ext4_parse_sb(&sb, &info) < 0) return false;
return (info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SHARED_BLOCKS) != 0;
}
#define F2FS_SUPER_OFFSET 1024
#define F2FS_FEATURE_OFFSET 2180
#define F2FS_FEATURE_RO 0x4000
bool fs_mgr_is_read_only_f2fs(const std::string& dev) {
if (!fs_mgr_is_f2fs(dev)) return false;
android::base::unique_fd fd(open(dev.c_str(), O_RDONLY | O_CLOEXEC));
if (fd < 0) return false;
__le32 feat;
if ((TEMP_FAILURE_RETRY(lseek64(fd, F2FS_SUPER_OFFSET + F2FS_FEATURE_OFFSET, SEEK_SET)) < 0) ||
(TEMP_FAILURE_RETRY(read(fd, &feat, sizeof(feat))) < 0)) {
return false;
}
return (feat & cpu_to_le32(F2FS_FEATURE_RO)) != 0;
}
bool fs_mgr_overlayfs_enabled(FstabEntry* entry) {
// readonly filesystem, can not be mount -o remount,rw
// for squashfs, erofs or if free space is (near) zero making such a remount
// virtually useless, or if there are shared blocks that prevent remount,rw
if (!fs_mgr_filesystem_has_space(entry->mount_point)) {
return true;
}
// blk_device needs to be setup so we can check superblock.
// If we fail here, because during init first stage and have doubts.
if (!fs_mgr_update_blk_device(entry)) {
return true;
}
// f2fs read-only mode doesn't support remount,rw
if (fs_mgr_is_read_only_f2fs(entry->blk_device)) {
return true;
}
// check if ext4 de-dupe
auto has_shared_blocks = fs_mgr_has_shared_blocks(entry->mount_point, entry->blk_device);
if (!has_shared_blocks && (entry->mount_point == "/system")) {
has_shared_blocks = fs_mgr_has_shared_blocks("/", entry->blk_device);
}
return has_shared_blocks;
}
bool fs_mgr_rm_all(const std::string& path, bool* change = nullptr, int level = 0) {
std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(path.c_str()), closedir);
if (!dir) {
if (errno == ENOENT) {
return true;
}
PERROR << "opendir " << path << " depth=" << level;
if ((errno == EPERM) && (level != 0)) {
return true;
}
return false;
}
dirent* entry;
auto ret = true;
while ((entry = readdir(dir.get()))) {
if (("."s == entry->d_name) || (".."s == entry->d_name)) continue;
auto file = path + "/" + entry->d_name;
if (entry->d_type == DT_UNKNOWN) {
struct stat st;
if (!lstat(file.c_str(), &st) && (st.st_mode & S_IFDIR)) entry->d_type = DT_DIR;
}
if (entry->d_type == DT_DIR) {
ret &= fs_mgr_rm_all(file, change, level + 1);
if (!rmdir(file.c_str())) {
if (change) *change = true;
} else {
if (errno != ENOENT) ret = false;
PERROR << "rmdir " << file << " depth=" << level;
}
continue;
}
if (!unlink(file.c_str())) {
if (change) *change = true;
} else {
if (errno != ENOENT) ret = false;
PERROR << "rm " << file << " depth=" << level;
}
}
return ret;
}
const auto kUpperName = "upper"s;
const auto kWorkName = "work"s;
const auto kOverlayTopDir = "/overlay"s;
std::string fs_mgr_get_overlayfs_candidate(const std::string& mount_point) {
if (!fs_mgr_is_dir(mount_point)) return "";
const auto base = android::base::Basename(mount_point) + "/";
for (const auto& overlay_mount_point : OverlayMountPoints()) {
auto dir = overlay_mount_point + kOverlayTopDir + "/" + base;
auto upper = dir + kUpperName;
if (!fs_mgr_is_dir(upper)) continue;
auto work = dir + kWorkName;
if (!fs_mgr_is_dir(work)) continue;
if (!fs_mgr_rw_access(work)) continue;
return dir;
}
return "";
}
static inline bool KernelSupportsUserXattrs() {
struct utsname uts;
uname(&uts);
int major, minor;
if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) {
return false;
}
return major > 5 || (major == 5 && minor >= 15);
}
const std::string fs_mgr_mount_point(const std::string& mount_point) {
if ("/"s != mount_point) return mount_point;
return "/system";
}
// default options for mount_point, returns empty string for none available.
std::string fs_mgr_get_overlayfs_options(const FstabEntry& entry) {
const auto mount_point = fs_mgr_mount_point(entry.mount_point);
auto candidate = fs_mgr_get_overlayfs_candidate(mount_point);
if (candidate.empty()) return "";
auto ret = kLowerdirOption + mount_point + "," + kUpperdirOption + candidate + kUpperName +
",workdir=" + candidate + kWorkName;
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kOverrideCredsRequired) {
ret += ",override_creds=off";
}
if (KernelSupportsUserXattrs()) {
ret += ",userxattr";
}
for (const auto& flag : android::base::Split(entry.fs_options, ",")) {
if (android::base::StartsWith(flag, "context=")) {
ret += "," + flag;
}
}
return ret;
}
constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";
class AutoSetFsCreateCon final {
public:
AutoSetFsCreateCon() {}
AutoSetFsCreateCon(const std::string& context) { Set(context); }
~AutoSetFsCreateCon() { Restore(); }
bool Ok() const { return ok_; }
bool Set(const std::string& context) {
if (setfscreatecon(context.c_str())) {
PLOG(ERROR) << "setfscreatecon " << context;
return false;
}
ok_ = true;
return true;
}
bool Restore() {
if (restored_ || !ok_) {
return true;
}
if (setfscreatecon(nullptr)) {
PLOG(ERROR) << "setfscreatecon null";
return false;
}
restored_ = true;
return true;
}
private:
bool ok_ = false;
bool restored_ = false;
};
std::string fs_mgr_overlayfs_setup_dir(const std::string& dir) {
auto top = dir + kOverlayTopDir;
AutoSetFsCreateCon createcon(kOverlayfsFileContext);
if (!createcon.Ok()) {
return {};
}
if (mkdir(top.c_str(), 0755) != 0 && errno != EEXIST) {
PERROR << "mkdir " << top;
return {};
}
if (!createcon.Restore()) {
return {};
}
return top;
}
bool fs_mgr_overlayfs_setup_one(const std::string& overlay, const std::string& mount_point,
bool* want_reboot) {
if (fs_mgr_overlayfs_already_mounted(mount_point)) {
return true;
}
auto fsrec_mount_point = overlay + "/" + android::base::Basename(mount_point) + "/";
AutoSetFsCreateCon createcon(kOverlayfsFileContext);
if (!createcon.Ok()) {
return false;
}
if (mkdir(fsrec_mount_point.c_str(), 0755) != 0 && errno != EEXIST) {
PERROR << "mkdir " << fsrec_mount_point;
return false;
}
if (mkdir((fsrec_mount_point + kWorkName).c_str(), 0755) != 0 && errno != EEXIST) {
PERROR << "mkdir " << fsrec_mount_point << kWorkName;
return false;
}
if (!createcon.Restore()) {
return false;
}
createcon = {};
auto new_context = fs_mgr_get_context(mount_point);
if (new_context.empty() || !createcon.Set(new_context)) {
return false;
}
auto upper = fsrec_mount_point + kUpperName;
if (mkdir(upper.c_str(), 0755) != 0 && errno != EEXIST) {
PERROR << "mkdir " << upper;
return false;
}
if (!createcon.Restore()) {
return false;
}
if (want_reboot) *want_reboot = true;
return true;
}
uint32_t fs_mgr_overlayfs_slot_number() {
return SlotNumberForSlotSuffix(fs_mgr_get_slot_suffix());
}
std::string fs_mgr_overlayfs_super_device(uint32_t slot_number) {
return kPhysicalDevice + fs_mgr_get_super_partition_name(slot_number);
}
bool fs_mgr_overlayfs_has_logical(const Fstab& fstab) {
for (const auto& entry : fstab) {
if (entry.fs_mgr_flags.logical) {
return true;
}
}
return false;
}
// Returns true if immediate unmount succeeded and the scratch mount point was
// removed.
bool fs_mgr_overlayfs_umount_scratch() {
if (umount(kScratchMountPoint.c_str()) != 0) {
return false;
}
if (rmdir(kScratchMountPoint.c_str()) != 0 && errno != ENOENT) {
PLOG(ERROR) << "rmdir " << kScratchMountPoint;
}
return true;
}
OverlayfsTeardownResult TeardownDataScratch(IImageManager* images,
const std::string& partition_name, bool was_mounted) {
if (!images) {
return OverlayfsTeardownResult::Error;
}
if (!images->DisableImage(partition_name)) {
return OverlayfsTeardownResult::Error;
}
if (was_mounted) {
// If overlayfs was mounted, don't bother trying to unmap since
// it'll fail and create error spam.
return OverlayfsTeardownResult::Busy;
}
if (!images->UnmapImageIfExists(partition_name)) {
return OverlayfsTeardownResult::Busy;
}
if (!images->DeleteBackingImage(partition_name)) {
return OverlayfsTeardownResult::Busy;
}
return OverlayfsTeardownResult::Ok;
}
OverlayfsTeardownResult fs_mgr_overlayfs_teardown_scratch(const std::string& overlay,
bool* change) {
// umount and delete kScratchMountPoint storage if we have logical partitions
if (overlay != kScratchMountPoint) {
return OverlayfsTeardownResult::Ok;
}
// Validation check.
if (fs_mgr_is_dsu_running()) {
LERROR << "Destroying DSU scratch is not allowed.";
return OverlayfsTeardownResult::Error;
}
bool was_mounted = fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false);
if (was_mounted) {
fs_mgr_overlayfs_umount_scratch();
}
const auto partition_name = android::base::Basename(kScratchMountPoint);
auto images = IImageManager::Open("remount", 10s);
if (images && images->BackingImageExists(partition_name)) {
// No need to check super partition, if we knew we had a scratch device
// in /data.
return TeardownDataScratch(images.get(), partition_name, was_mounted);
}
auto slot_number = fs_mgr_overlayfs_slot_number();
auto super_device = fs_mgr_overlayfs_super_device(slot_number);
if (!fs_mgr_rw_access(super_device)) {
return OverlayfsTeardownResult::Ok;
}
auto builder = MetadataBuilder::New(super_device, slot_number);
if (!builder) {
return OverlayfsTeardownResult::Ok;
}
if (builder->FindPartition(partition_name) == nullptr) {
return OverlayfsTeardownResult::Ok;
}
builder->RemovePartition(partition_name);
auto metadata = builder->Export();
if (metadata && UpdatePartitionTable(super_device, *metadata.get(), slot_number)) {
if (change) *change = true;
if (!DestroyLogicalPartition(partition_name)) {
return OverlayfsTeardownResult::Error;
}
} else {
LERROR << "delete partition " << overlay;
return OverlayfsTeardownResult::Error;
}
if (was_mounted) {
return OverlayfsTeardownResult::Busy;
}
return OverlayfsTeardownResult::Ok;
}
bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string& mount_point,
bool* change, bool* should_destroy_scratch = nullptr) {
const auto top = overlay + kOverlayTopDir;
if (!fs_mgr_access(top)) {
if (should_destroy_scratch) *should_destroy_scratch = true;
return true;
}
auto cleanup_all = mount_point.empty();
const auto partition_name = android::base::Basename(mount_point);
const auto oldpath = top + (cleanup_all ? "" : ("/" + partition_name));
const auto newpath = cleanup_all ? overlay + "/." + kOverlayTopDir.substr(1) + ".teardown"
: top + "/." + partition_name + ".teardown";
auto ret = fs_mgr_rm_all(newpath);
if (!rename(oldpath.c_str(), newpath.c_str())) {
if (change) *change = true;
} else if (errno != ENOENT) {
ret = false;
PERROR << "mv " << oldpath << " " << newpath;
}
ret &= fs_mgr_rm_all(newpath, change);
if (!rmdir(newpath.c_str())) {
if (change) *change = true;
} else if (errno != ENOENT) {
ret = false;
PERROR << "rmdir " << newpath;
}
if (!cleanup_all) {
if (!rmdir(top.c_str())) {
if (change) *change = true;
cleanup_all = true;
} else if (errno == ENOTEMPTY) {
cleanup_all = true;
// cleanup all if the content is all hidden (leading .)
std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(top.c_str()), closedir);
if (!dir) {
PERROR << "opendir " << top;
} else {
dirent* entry;
while ((entry = readdir(dir.get()))) {
if (entry->d_name[0] != '.') {
cleanup_all = false;
break;
}
}
}
} else if (errno == ENOENT) {
cleanup_all = true;
} else {
ret = false;
PERROR << "rmdir " << top;
}
}
if (should_destroy_scratch) *should_destroy_scratch = cleanup_all;
return ret;
}
bool fs_mgr_overlayfs_set_shared_mount(const std::string& mount_point, bool shared_flag) {
auto ret = mount(nullptr, mount_point.c_str(), nullptr, shared_flag ? MS_SHARED : MS_PRIVATE,
nullptr);
if (ret) {
PERROR << "__mount(target=" << mount_point
<< ",flag=" << (shared_flag ? "MS_SHARED" : "MS_PRIVATE") << ")=" << ret;
// If "/system" doesn't look like a mountpoint, retry with "/".
if (errno == EINVAL && mount_point == "/system") {
return fs_mgr_overlayfs_set_shared_mount("/", shared_flag);
}
return false;
}
return true;
}
bool fs_mgr_overlayfs_move_mount(const std::string& source, const std::string& target) {
auto ret = mount(source.c_str(), target.c_str(), nullptr, MS_MOVE, nullptr);
if (ret) {
PERROR << "__mount(source=" << source << ",target=" << target << ",flag=MS_MOVE)=" << ret;
return false;
}
return true;
}
struct mount_info {
std::string mount_point;
bool shared_flag;
};
std::vector<mount_info> ReadMountinfoFromFile(const std::string& path) {
std::vector<mount_info> info;
auto file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
if (!file) {
PERROR << __FUNCTION__ << "(): cannot open file: '" << path << "'";
return info;
}
ssize_t len;
size_t alloc_len = 0;
char* line = nullptr;
while ((len = getline(&line, &alloc_len, file.get())) != -1) {
/* if the last character is a newline, shorten the string by 1 byte */
if (line[len - 1] == '\n') {
line[len - 1] = '\0';
}
static constexpr char delim[] = " \t";
char* save_ptr;
if (!strtok_r(line, delim, &save_ptr)) {
LERROR << "Error parsing mount ID";
break;
}
if (!strtok_r(nullptr, delim, &save_ptr)) {
LERROR << "Error parsing parent ID";
break;
}
if (!strtok_r(nullptr, delim, &save_ptr)) {
LERROR << "Error parsing mount source";
break;
}
if (!strtok_r(nullptr, delim, &save_ptr)) {
LERROR << "Error parsing root";
break;
}
char* p;
if (!(p = strtok_r(nullptr, delim, &save_ptr))) {
LERROR << "Error parsing mount_point";
break;
}
mount_info entry = {p, false};
if (!strtok_r(nullptr, delim, &save_ptr)) {
LERROR << "Error parsing mount_flags";
break;
}
while ((p = strtok_r(nullptr, delim, &save_ptr))) {
if ((p[0] == '-') && (p[1] == '\0')) break;
if (android::base::StartsWith(p, "shared:")) entry.shared_flag = true;
}
if (!p) {
LERROR << "Error parsing fields";
break;
}
info.emplace_back(std::move(entry));
}
free(line);
if (info.empty()) {
LERROR << __FUNCTION__ << "(): failed to load mountinfo from : '" << path << "'";
}
return info;
}
bool fs_mgr_overlayfs_mount(const FstabEntry& entry) {
const auto mount_point = fs_mgr_mount_point(entry.mount_point);
const auto options = fs_mgr_get_overlayfs_options(entry);
if (options.empty()) return false;
auto retval = true;
struct move_entry {
std::string mount_point;
std::string dir;
bool shared_flag;
};
std::vector<move_entry> move;
auto parent_private = false;
auto parent_made_private = false;
auto dev_private = false;
auto dev_made_private = false;
for (auto& entry : ReadMountinfoFromFile("/proc/self/mountinfo")) {
if ((entry.mount_point == mount_point) && !entry.shared_flag) {
parent_private = true;
}
if ((entry.mount_point == "/dev") && !entry.shared_flag) {
dev_private = true;
}
if (!android::base::StartsWith(entry.mount_point, mount_point + "/")) {
continue;
}
if (std::find_if(move.begin(), move.end(), [&entry](const auto& it) {
return android::base::StartsWith(entry.mount_point, it.mount_point + "/");
}) != move.end()) {
continue;
}
// use as the bound directory in /dev.
AutoSetFsCreateCon createcon;
auto new_context = fs_mgr_get_context(entry.mount_point);
if (new_context.empty() || !createcon.Set(new_context)) {
continue;
}
move_entry new_entry = {std::move(entry.mount_point), "/dev/TemporaryDir-XXXXXX",
entry.shared_flag};
const auto target = mkdtemp(new_entry.dir.data());
if (!createcon.Restore()) {
return false;
}
if (!target) {
retval = false;
PERROR << "temporary directory for MS_BIND";
continue;
}
if (!parent_private && !parent_made_private) {
parent_made_private = fs_mgr_overlayfs_set_shared_mount(mount_point, false);
}
if (new_entry.shared_flag) {
new_entry.shared_flag = fs_mgr_overlayfs_set_shared_mount(new_entry.mount_point, false);
}
if (!fs_mgr_overlayfs_move_mount(new_entry.mount_point, new_entry.dir)) {
retval = false;
if (new_entry.shared_flag) {
fs_mgr_overlayfs_set_shared_mount(new_entry.mount_point, true);
}
continue;
}
move.emplace_back(std::move(new_entry));
}
// hijack __mount() report format to help triage
auto report = "__mount(source=overlay,target="s + mount_point + ",type=overlay";
const auto opt_list = android::base::Split(options, ",");
for (const auto& opt : opt_list) {
if (android::base::StartsWith(opt, kUpperdirOption)) {
report = report + "," + opt;
break;
}
}
report = report + ")=";
auto ret = mount("overlay", mount_point.c_str(), "overlay", MS_RDONLY | MS_NOATIME,
options.c_str());
if (ret) {
retval = false;
PERROR << report << ret;
} else {
LINFO << report << ret;
}
// Move submounts back.
for (const auto& entry : move) {
if (!dev_private && !dev_made_private) {
dev_made_private = fs_mgr_overlayfs_set_shared_mount("/dev", false);
}
if (!fs_mgr_overlayfs_move_mount(entry.dir, entry.mount_point)) {
retval = false;
} else if (entry.shared_flag &&
!fs_mgr_overlayfs_set_shared_mount(entry.mount_point, true)) {
retval = false;
}
rmdir(entry.dir.c_str());
}
if (dev_made_private) {
fs_mgr_overlayfs_set_shared_mount("/dev", true);
}
if (parent_made_private) {
fs_mgr_overlayfs_set_shared_mount(mount_point, true);
}
return retval;
}
// Mount kScratchMountPoint
bool MountScratch(const std::string& device_path, bool readonly = false) {
if (readonly) {
if (!fs_mgr_access(device_path)) {
LOG(ERROR) << "Path does not exist: " << device_path;
return false;
}
} else if (!fs_mgr_rw_access(device_path)) {
LOG(ERROR) << "Path does not exist or is not readwrite: " << device_path;
return false;
}
std::vector<const char*> filesystem_candidates;
if (fs_mgr_is_f2fs(device_path)) {
filesystem_candidates = {"f2fs", "ext4"};
} else if (fs_mgr_is_ext4(device_path)) {
filesystem_candidates = {"ext4", "f2fs"};
} else {
LOG(ERROR) << "Scratch partition is not f2fs or ext4";
return false;
}
AutoSetFsCreateCon createcon(kOverlayfsFileContext);
if (!createcon.Ok()) {
return false;
}
if (mkdir(kScratchMountPoint.c_str(), 0755) && (errno != EEXIST)) {
PERROR << "create " << kScratchMountPoint;
return false;
}
FstabEntry entry;
entry.blk_device = device_path;
entry.mount_point = kScratchMountPoint;
entry.flags = MS_NOATIME | MS_RDONLY;
if (!readonly) {
entry.flags &= ~MS_RDONLY;
entry.flags |= MS_SYNCHRONOUS;
entry.fs_options = "nodiscard";
fs_mgr_set_blk_ro(device_path, false);
}
// check_fs requires apex runtime library
if (fs_mgr_overlayfs_already_mounted("/data", false)) {
entry.fs_mgr_flags.check = true;
}
bool mounted = false;
for (auto fs_type : filesystem_candidates) {
entry.fs_type = fs_type;
if (fs_mgr_do_mount_one(entry) == 0) {
mounted = true;
break;
}
}
if (!createcon.Restore()) {
return false;
}
if (!mounted) {
rmdir(kScratchMountPoint.c_str());
return false;
}
return true;
}
const std::string kMkF2fs("/system/bin/make_f2fs");
const std::string kMkExt4("/system/bin/mke2fs");
// Note: The scratch partition of DSU is managed by gsid, and should be initialized during
// first-stage-mount. Just check if the DM device for DSU scratch partition is created or not.
static std::string GetDsuScratchDevice() {
auto& dm = DeviceMapper::Instance();
std::string device;
if (dm.GetState(android::gsi::kDsuScratch) != DmDeviceState::INVALID &&
dm.GetDmDevicePathByName(android::gsi::kDsuScratch, &device)) {
return device;
}
return "";
}
// This returns the scratch device that was detected during early boot (first-
// stage init). If the device was created later, for example during setup for
// the adb remount command, it can return an empty string since it does not
// query ImageManager. (Note that ImageManager in first-stage init will always
// use device-mapper, since /data is not available to use loop devices.)
static std::string GetBootScratchDevice() {
// Note: fs_mgr_is_dsu_running() always returns false in recovery or fastbootd.
if (fs_mgr_is_dsu_running()) {
return GetDsuScratchDevice();
}
auto& dm = DeviceMapper::Instance();
// If there is a scratch partition allocated in /data or on super, we
// automatically prioritize that over super_other or system_other.
// Some devices, for example, have a write-protected eMMC and the
// super partition cannot be used even if it exists.
std::string device;
auto partition_name = android::base::Basename(kScratchMountPoint);
if (dm.GetState(partition_name) != DmDeviceState::INVALID &&
dm.GetDmDevicePathByName(partition_name, &device)) {
return device;
}
return "";
}
bool MakeScratchFilesystem(const std::string& scratch_device) {
// Force mkfs by design for overlay support of adb remount, simplify and
// thus do not rely on fsck to correct problems that could creep in.
auto fs_type = ""s;
auto command = ""s;
if (!access(kMkF2fs.c_str(), X_OK) && fs_mgr_filesystem_available("f2fs")) {
fs_type = "f2fs";
command = kMkF2fs + " -w 4096 -f -d1 -l" + android::base::Basename(kScratchMountPoint);
} else if (!access(kMkExt4.c_str(), X_OK) && fs_mgr_filesystem_available("ext4")) {
fs_type = "ext4";
command = kMkExt4 + " -F -b 4096 -t ext4 -m 0 -O has_journal -M " + kScratchMountPoint;
} else {
LERROR << "No supported mkfs command or filesystem driver available, supported filesystems "
"are: f2fs, ext4";
return false;
}
command += " " + scratch_device + " >/dev/null 2>/dev/null </dev/null";
fs_mgr_set_blk_ro(scratch_device, false);
auto ret = system(command.c_str());
if (ret) {
LERROR << "make " << fs_type << " filesystem on " << scratch_device << " return=" << ret;
return false;
}
return true;
}
static void TruncatePartitionsWithSuffix(MetadataBuilder* builder, const std::string& suffix) {
auto& dm = DeviceMapper::Instance();
// Remove <other> partitions
for (const auto& group : builder->ListGroups()) {
for (const auto& part : builder->ListPartitionsInGroup(group)) {
const auto& name = part->name();
if (!android::base::EndsWith(name, suffix)) {
continue;
}
if (dm.GetState(name) != DmDeviceState::INVALID && !DestroyLogicalPartition(name)) {
continue;
}
builder->ResizePartition(builder->FindPartition(name), 0);
}
}
}
// Create or update a scratch partition within super.
static bool CreateDynamicScratch(std::string* scratch_device, bool* partition_exists) {
const auto partition_name = android::base::Basename(kScratchMountPoint);
auto& dm = DeviceMapper::Instance();
*partition_exists = dm.GetState(partition_name) != DmDeviceState::INVALID;
auto partition_create = !*partition_exists;
auto slot_number = fs_mgr_overlayfs_slot_number();
auto super_device = fs_mgr_overlayfs_super_device(slot_number);
auto builder = MetadataBuilder::New(super_device, slot_number);
if (!builder) {
LERROR << "open " << super_device << " metadata";
return false;
}
auto partition = builder->FindPartition(partition_name);
*partition_exists = partition != nullptr;
auto changed = false;
if (!*partition_exists) {
partition = builder->AddPartition(partition_name, LP_PARTITION_ATTR_NONE);
if (!partition) {
LERROR << "create " << partition_name;
return false;
}
changed = true;
}
// Take half of free space, minimum 512MB or maximum free - margin.
static constexpr auto kMinimumSize = uint64_t(512 * 1024 * 1024);
if (partition->size() < kMinimumSize) {
auto partition_size =
builder->AllocatableSpace() - builder->UsedSpace() + partition->size();
if ((partition_size > kMinimumSize) || !partition->size()) {
// Leave some space for free space jitter of a few erase
// blocks, in case they are needed for any individual updates
// to any other partition that needs to be flashed while
// overlayfs is in force. Of course if margin_size is not
// enough could normally get a flash failure, so
// ResizePartition() will delete the scratch partition in
// order to fulfill. Deleting scratch will destroy all of
// the adb remount overrides :-( .
auto margin_size = uint64_t(3 * 256 * 1024);
BlockDeviceInfo info;
if (builder->GetBlockDeviceInfo(fs_mgr_get_super_partition_name(slot_number), &info)) {
margin_size = 3 * info.logical_block_size;
}
partition_size = std::max(std::min(kMinimumSize, partition_size - margin_size),
partition_size / 2);
if (partition_size > partition->size()) {
if (!builder->ResizePartition(partition, partition_size)) {
// Try to free up space by deallocating partitions in the other slot.
TruncatePartitionsWithSuffix(builder.get(), fs_mgr_get_other_slot_suffix());
partition_size =
builder->AllocatableSpace() - builder->UsedSpace() + partition->size();
partition_size = std::max(std::min(kMinimumSize, partition_size - margin_size),
partition_size / 2);
if (!builder->ResizePartition(partition, partition_size)) {
LERROR << "resize " << partition_name;
return false;
}
}
if (!partition_create) DestroyLogicalPartition(partition_name);
changed = true;
*partition_exists = false;
}
}
}
// land the update back on to the partition
if (changed) {
auto metadata = builder->Export();
if (!metadata || !UpdatePartitionTable(super_device, *metadata.get(), slot_number)) {
LERROR << "add partition " << partition_name;
return false;
}
}
if (changed || partition_create) {
CreateLogicalPartitionParams params = {
.block_device = super_device,
.metadata_slot = slot_number,
.partition_name = partition_name,
.force_writable = true,
.timeout_ms = 10s,
};
if (!CreateLogicalPartition(params, scratch_device)) {
return false;
}
} else if (scratch_device->empty()) {
*scratch_device = GetBootScratchDevice();
}
return true;
}
static inline uint64_t GetIdealDataScratchSize() {
BlockDeviceInfo super_info;
PartitionOpener opener;
if (!opener.GetInfo(fs_mgr_get_super_partition_name(), &super_info)) {
LERROR << "could not get block device info for super";
return 0;
}
struct statvfs s;
if (statvfs("/data", &s) < 0) {
PERROR << "could not statfs /data";
return 0;
}
auto ideal_size = std::min(super_info.size, (uint64_t(s.f_frsize) * s.f_bfree) / 2);
// Align up to the filesystem block size.
if (auto remainder = ideal_size % s.f_bsize; remainder > 0) {
ideal_size += s.f_bsize - remainder;
}
return ideal_size;
}
static bool CreateScratchOnData(std::string* scratch_device, bool* partition_exists) {
*partition_exists = false;
auto images = IImageManager::Open("remount", 10s);
if (!images) {
return false;
}
auto partition_name = android::base::Basename(kScratchMountPoint);
if (images->GetMappedImageDevice(partition_name, scratch_device)) {
*partition_exists = true;
return true;
}
// Note: calling RemoveDisabledImages here ensures that we do not race with
// clean_scratch_files and accidentally try to map an image that will be
// deleted.
if (!images->RemoveDisabledImages()) {
return false;
}
if (!images->BackingImageExists(partition_name)) {
auto size = android::base::GetUintProperty<uint64_t>(kDataScratchSizeMbProp, 0) * 1_MiB;
if (!size) {
size = GetIdealDataScratchSize();
}
if (!size) {
size = 2_GiB;
}
auto flags = IImageManager::CREATE_IMAGE_DEFAULT;
if (!images->CreateBackingImage(partition_name, size, flags)) {
LERROR << "could not create scratch image of " << size << " bytes";
return false;
}
}
if (!images->MapImageDevice(partition_name, 10s, scratch_device)) {
LERROR << "could not map scratch image";
// If we cannot use this image, then remove it.
TeardownDataScratch(images.get(), partition_name, false /* was_mounted */);
return false;
}
return true;
}
static bool CanUseSuperPartition(const Fstab& fstab) {
auto slot_number = fs_mgr_overlayfs_slot_number();
auto super_device = fs_mgr_overlayfs_super_device(slot_number);
if (!fs_mgr_rw_access(super_device) || !fs_mgr_overlayfs_has_logical(fstab)) {
return false;
}
auto metadata = ReadMetadata(super_device, slot_number);
if (!metadata) {
return false;
}
return true;
}
bool fs_mgr_overlayfs_create_scratch(const Fstab& fstab, std::string* scratch_device,
bool* partition_exists) {
// Use the DSU scratch device managed by gsid if within a DSU system.
if (fs_mgr_is_dsu_running()) {
*scratch_device = GetDsuScratchDevice();
*partition_exists = !scratch_device->empty();
return *partition_exists;
}
// Try ImageManager on /data first.
bool can_use_data = false;
if (FilesystemHasReliablePinning("/data", &can_use_data) && can_use_data) {
if (CreateScratchOnData(scratch_device, partition_exists)) {
return true;
}
LOG(WARNING) << "Failed to allocate scratch on /data, fallback to use free space on super";
}
// If that fails, see if we can land on super.
if (CanUseSuperPartition(fstab)) {
return CreateDynamicScratch(scratch_device, partition_exists);
}
return false;
}
// Create and mount kScratchMountPoint storage if we have logical partitions
bool fs_mgr_overlayfs_setup_scratch(const Fstab& fstab) {
if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
return true;
}
std::string scratch_device;
bool partition_exists;
if (!fs_mgr_overlayfs_create_scratch(fstab, &scratch_device, &partition_exists)) {
LOG(ERROR) << "Failed to create scratch partition";
return false;
}
// If the partition exists, assume first that it can be mounted.
if (partition_exists) {
if (MountScratch(scratch_device)) {
if (fs_mgr_access(kScratchMountPoint + kOverlayTopDir) ||
fs_mgr_filesystem_has_space(kScratchMountPoint)) {
return true;
}
// declare it useless, no overrides and no free space
if (!fs_mgr_overlayfs_umount_scratch()) {
LOG(ERROR) << "Unable to unmount scratch partition";
return false;
}
}
}
if (!MakeScratchFilesystem(scratch_device)) {
LOG(ERROR) << "Failed to format scratch partition";
return false;
}
return MountScratch(scratch_device);
}
#if ALLOW_ADBD_DISABLE_VERITY
constexpr bool kAllowOverlayfs = true;
#else
constexpr bool kAllowOverlayfs = false;
#endif
// NOTE: OverlayfsSetupAllowed() must be "stricter" than OverlayfsTeardownAllowed().
// Setup is allowed only if teardown is also allowed.
bool OverlayfsSetupAllowed(bool verbose = false) {
if (!kAllowOverlayfs) {
if (verbose) {
LOG(ERROR) << "Overlayfs remounts can only be used in debuggable builds";
}
return false;
}
// Check mandatory kernel patches.
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
if (verbose) {
LOG(ERROR) << "Kernel does not support overlayfs";
}
return false;
}
// in recovery or fastbootd, not allowed!
if (fs_mgr_in_recovery()) {
if (verbose) {
LOG(ERROR) << "Unsupported overlayfs setup from recovery";
}
return false;
}
return true;
}
constexpr bool OverlayfsTeardownAllowed() {
// Never allow on non-debuggable build.
return kAllowOverlayfs;
}
} // namespace
bool fs_mgr_wants_overlayfs(FstabEntry* entry) {
// Don't check entries that are managed by vold.
if (entry->fs_mgr_flags.vold_managed || entry->fs_mgr_flags.recovery_only) return false;
// *_other doesn't want overlayfs.
if (entry->fs_mgr_flags.slot_select_other) return false;
// Only concerned with readonly partitions.
if (!(entry->flags & MS_RDONLY)) return false;
// If unbindable, do not allow overlayfs as this could expose us to
// security issues. On Android, this could also be used to turn off
// the ability to overlay an otherwise acceptable filesystem since
// /system and /vendor are never bound(sic) to.
if (entry->flags & MS_UNBINDABLE) return false;
if (!fs_mgr_overlayfs_enabled(entry)) return false;
return true;
}
Fstab fs_mgr_overlayfs_candidate_list(const Fstab& fstab) {
android::fs_mgr::Fstab mounts;
if (!android::fs_mgr::ReadFstabFromFile("/proc/mounts", &mounts)) {
PLOG(ERROR) << "Failed to read /proc/mounts";
return {};
}
Fstab candidates;
for (const auto& entry : fstab) {
// Filter out partitions whose type doesn't match what's mounted.
// This avoids spammy behavior on devices which can mount different
// filesystems for each partition.
auto proc_mount_point = (entry.mount_point == "/system") ? "/" : entry.mount_point;
auto mounted = GetEntryForMountPoint(&mounts, proc_mount_point);
if (!mounted || mounted->fs_type != entry.fs_type) {
continue;
}
FstabEntry new_entry = entry;
if (!fs_mgr_overlayfs_already_mounted(entry.mount_point) &&
!fs_mgr_wants_overlayfs(&new_entry)) {
continue;
}
auto new_mount_point = fs_mgr_mount_point(entry.mount_point);
auto duplicate_or_more_specific = false;
for (auto it = candidates.begin(); it != candidates.end();) {
auto it_mount_point = fs_mgr_mount_point(it->mount_point);
if ((it_mount_point == new_mount_point) ||
(android::base::StartsWith(new_mount_point, it_mount_point + "/"))) {
duplicate_or_more_specific = true;
break;
}
if (android::base::StartsWith(it_mount_point, new_mount_point + "/")) {
it = candidates.erase(it);
} else {
++it;
}
}
if (!duplicate_or_more_specific) candidates.emplace_back(std::move(new_entry));
}
return candidates;
}
static void TryMountScratch() {
// Note we get the boot scratch device here, which means if scratch was
// just created through ImageManager, this could fail. In practice this
// should not happen because "remount" detects this scenario (by checking
// if verity is still disabled, i.e. no reboot occurred), and skips calling
// fs_mgr_overlayfs_mount_all().
auto scratch_device = GetBootScratchDevice();
if (!fs_mgr_rw_access(scratch_device)) {
return;
}
if (!WaitForFile(scratch_device, 10s)) {
return;
}
if (!MountScratch(scratch_device, true /* readonly */)) {
return;
}
auto has_overlayfs_dir = fs_mgr_access(kScratchMountPoint + kOverlayTopDir);
fs_mgr_overlayfs_umount_scratch();
if (has_overlayfs_dir) {
MountScratch(scratch_device);
}
}
bool fs_mgr_overlayfs_mount_all(Fstab* fstab) {
if (!OverlayfsSetupAllowed()) {
return false;
}
auto ret = true;
auto scratch_can_be_mounted = true;
for (const auto& entry : fs_mgr_overlayfs_candidate_list(*fstab)) {
if (fs_mgr_is_verity_enabled(entry)) continue;
auto mount_point = fs_mgr_mount_point(entry.mount_point);
if (fs_mgr_overlayfs_already_mounted(mount_point)) {
continue;
}
if (scratch_can_be_mounted) {
scratch_can_be_mounted = false;
TryMountScratch();
}
ret &= fs_mgr_overlayfs_mount(entry);
}
return ret;
}
bool fs_mgr_overlayfs_setup(const Fstab& fstab, const char* mount_point, bool* want_reboot,
bool just_disabled_verity) {
if (!OverlayfsSetupAllowed(/*verbose=*/true)) {
return false;
}
if (!fs_mgr_boot_completed()) {
LOG(ERROR) << "Cannot setup overlayfs before persistent properties are ready";
return false;
}
auto candidates = fs_mgr_overlayfs_candidate_list(fstab);
for (auto it = candidates.begin(); it != candidates.end();) {
if (mount_point &&
(fs_mgr_mount_point(it->mount_point) != fs_mgr_mount_point(mount_point))) {
it = candidates.erase(it);
continue;
}
auto verity_enabled = !just_disabled_verity && fs_mgr_is_verity_enabled(*it);
if (verity_enabled) {
it = candidates.erase(it);
continue;
}
++it;
}
if (candidates.empty()) {
if (mount_point) {
LOG(ERROR) << "No overlayfs candidate was found for " << mount_point;
return false;
}
return true;
}
std::string dir;
for (const auto& overlay_mount_point : OverlayMountPoints()) {
if (overlay_mount_point == kScratchMountPoint) {
if (!fs_mgr_overlayfs_setup_scratch(fstab)) {
continue;
}
} else {
if (GetEntryForMountPoint(&fstab, overlay_mount_point) == nullptr) {
continue;
}
}
dir = overlay_mount_point;
break;
}
if (dir.empty()) {
LOG(ERROR) << "Could not allocate backing storage for overlays";
return false;
}
const auto overlay = fs_mgr_overlayfs_setup_dir(dir);
if (overlay.empty()) {
return false;
}
bool ok = true;
for (const auto& entry : candidates) {
auto fstab_mount_point = fs_mgr_mount_point(entry.mount_point);
ok &= fs_mgr_overlayfs_setup_one(overlay, fstab_mount_point, want_reboot);
}
return ok;
}
struct MapInfo {
// If set, partition is owned by ImageManager.
std::unique_ptr<IImageManager> images;
// If set, and images is null, this is a DAP partition.
std::string name;
// If set, and images and name are empty, this is a non-dynamic partition.
std::string device;
MapInfo() = default;
MapInfo(MapInfo&&) = default;
~MapInfo() {
if (images) {
images->UnmapImageDevice(name);
} else if (!name.empty()) {
DestroyLogicalPartition(name);
}
}
};
// Note: This function never returns the DSU scratch device in recovery or fastbootd,
// because the DSU scratch is created in the first-stage-mount, which is not run in recovery.
static std::optional<MapInfo> EnsureScratchMapped() {
MapInfo info;
info.device = GetBootScratchDevice();
if (!info.device.empty()) {
return {std::move(info)};
}
if (!fs_mgr_in_recovery()) {
return {};
}
auto partition_name = android::base::Basename(kScratchMountPoint);
// Check for scratch on /data first, before looking for a modified super
// partition. We should only reach this code in recovery, because scratch
// would otherwise always be mapped.
auto images = IImageManager::Open("remount", 10s);
if (images && images->BackingImageExists(partition_name)) {
if (images->IsImageDisabled(partition_name)) {
return {};
}
if (!images->MapImageDevice(partition_name, 10s, &info.device)) {
return {};
}
info.name = partition_name;
info.images = std::move(images);
return {std::move(info)};
}
// Avoid uart spam by first checking for a scratch partition.
auto metadata_slot = fs_mgr_overlayfs_slot_number();
auto super_device = fs_mgr_overlayfs_super_device(metadata_slot);
auto metadata = ReadCurrentMetadata(super_device);
if (!metadata) {
return {};
}
auto partition = FindPartition(*metadata.get(), partition_name);
if (!partition) {
return {};
}
CreateLogicalPartitionParams params = {
.block_device = super_device,
.metadata = metadata.get(),
.partition = partition,
.force_writable = true,
.timeout_ms = 10s,
};
if (!CreateLogicalPartition(params, &info.device)) {
return {};
}
info.name = partition_name;
return {std::move(info)};
}
// This should only be reachable in recovery, where DSU scratch is not
// automatically mapped.
static bool MapDsuScratchDevice(std::string* device) {
std::string dsu_slot;
if (!android::gsi::IsGsiInstalled() || !android::gsi::GetActiveDsu(&dsu_slot) ||
dsu_slot.empty()) {
// Nothing to do if no DSU installation present.
return false;
}
auto images = IImageManager::Open("dsu/" + dsu_slot, 10s);
if (!images || !images->BackingImageExists(android::gsi::kDsuScratch)) {
// Nothing to do if DSU scratch device doesn't exist.
return false;
}
images->UnmapImageDevice(android::gsi::kDsuScratch);
if (!images->MapImageDevice(android::gsi::kDsuScratch, 10s, device)) {
return false;
}
return true;
}
static OverlayfsTeardownResult TeardownMountsAndScratch(const char* mount_point,
bool* want_reboot) {
bool should_destroy_scratch = false;
auto rv = OverlayfsTeardownResult::Ok;
for (const auto& overlay_mount_point : OverlayMountPoints()) {
auto ok = fs_mgr_overlayfs_teardown_one(
overlay_mount_point, mount_point ? fs_mgr_mount_point(mount_point) : "",
want_reboot,
overlay_mount_point == kScratchMountPoint ? &should_destroy_scratch : nullptr);
if (!ok) {
rv = OverlayfsTeardownResult::Error;
}
}
// Do not attempt to destroy DSU scratch if within a DSU system,
// because DSU scratch partition is managed by gsid.
if (should_destroy_scratch && !fs_mgr_is_dsu_running()) {
auto rv = fs_mgr_overlayfs_teardown_scratch(kScratchMountPoint, want_reboot);
if (rv != OverlayfsTeardownResult::Ok) {
return rv;
}
}
// And now that we did what we could, lets inform
// caller that there may still be more to do.
if (!fs_mgr_boot_completed()) {
LOG(ERROR) << "Cannot teardown overlayfs before persistent properties are ready";
return OverlayfsTeardownResult::Error;
}
return rv;
}
// Returns false if teardown not permitted. If something is altered, set *want_reboot.
OverlayfsTeardownResult fs_mgr_overlayfs_teardown(const char* mount_point, bool* want_reboot) {
if (!OverlayfsTeardownAllowed()) {
// Nothing to teardown.
return OverlayfsTeardownResult::Ok;
}
// If scratch exists, but is not mounted, lets gain access to clean
// specific override entries.
auto mount_scratch = false;
if ((mount_point != nullptr) && !fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
std::string scratch_device = GetBootScratchDevice();
if (!scratch_device.empty()) {
mount_scratch = MountScratch(scratch_device);
}
}
auto rv = TeardownMountsAndScratch(mount_point, want_reboot);
if (mount_scratch) {
if (!fs_mgr_overlayfs_umount_scratch()) {
return OverlayfsTeardownResult::Busy;
}
}
return rv;
}
bool fs_mgr_overlayfs_is_setup() {
if (!OverlayfsSetupAllowed()) {
return false;
}
if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) return true;
Fstab fstab;
if (!ReadDefaultFstab(&fstab)) {
return false;
}
for (const auto& entry : fs_mgr_overlayfs_candidate_list(fstab)) {
if (fs_mgr_is_verity_enabled(entry)) continue;
if (fs_mgr_overlayfs_already_mounted(fs_mgr_mount_point(entry.mount_point))) return true;
}
return false;
}
namespace android {
namespace fs_mgr {
void MapScratchPartitionIfNeeded(Fstab* fstab,
const std::function<bool(const std::set<std::string>&)>& init) {
if (!OverlayfsSetupAllowed()) {
return;
}
if (GetEntryForMountPoint(fstab, kScratchMountPoint) != nullptr) {
return;
}
bool want_scratch = false;
for (const auto& entry : fs_mgr_overlayfs_candidate_list(*fstab)) {
if (fs_mgr_is_verity_enabled(entry)) {
continue;
}
if (fs_mgr_overlayfs_already_mounted(fs_mgr_mount_point(entry.mount_point))) {
continue;
}
want_scratch = true;
break;
}
if (!want_scratch) {
return;
}
if (ScratchIsOnData()) {
if (auto images = IImageManager::Open("remount", 0ms)) {
images->MapAllImages(init);
}
}
// Physical or logical partitions will have already been mapped here,
// so just ensure /dev/block symlinks exist.
auto device = GetBootScratchDevice();
if (!device.empty()) {
init({android::base::Basename(device)});
}
}
void CleanupOldScratchFiles() {
if (!OverlayfsTeardownAllowed()) {
return;
}
if (!ScratchIsOnData()) {
return;
}
if (auto images = IImageManager::Open("remount", 0ms)) {
images->RemoveDisabledImages();
}
}
void TeardownAllOverlayForMountPoint(const std::string& mount_point) {
if (!OverlayfsTeardownAllowed()) {
return;
}
if (!fs_mgr_in_recovery()) {
LERROR << __FUNCTION__ << "(): must be called within recovery.";
return;
}
// Empty string means teardown everything.
const std::string teardown_dir = mount_point.empty() ? "" : fs_mgr_mount_point(mount_point);
constexpr bool* ignore_change = nullptr;
// Teardown legacy overlay mount points that's not backed by a scratch device.
for (const auto& overlay_mount_point : OverlayMountPoints()) {
if (overlay_mount_point == kScratchMountPoint) {
continue;
}
fs_mgr_overlayfs_teardown_one(overlay_mount_point, teardown_dir, ignore_change);
}
if (mount_point.empty()) {
// Throw away the entire partition.
auto partition_name = android::base::Basename(kScratchMountPoint);
auto images = IImageManager::Open("remount", 10s);
if (images && images->BackingImageExists(partition_name)) {
if (images->DisableImage(partition_name)) {
LOG(INFO) << "Disabled scratch partition for: " << kScratchMountPoint;
} else {
LOG(ERROR) << "Unable to disable scratch partition for " << kScratchMountPoint;
}
}
}
// Note if we just disabled scratch, this mount will fail.
if (auto info = EnsureScratchMapped(); info.has_value()) {
// Map scratch device, mount kScratchMountPoint and teardown kScratchMountPoint.
fs_mgr_overlayfs_umount_scratch();
if (MountScratch(info->device)) {
bool should_destroy_scratch = false;
fs_mgr_overlayfs_teardown_one(kScratchMountPoint, teardown_dir, ignore_change,
&should_destroy_scratch);
fs_mgr_overlayfs_umount_scratch();
if (should_destroy_scratch) {
fs_mgr_overlayfs_teardown_scratch(kScratchMountPoint, nullptr);
}
}
}
// Teardown DSU overlay if present.
std::string scratch_device;
if (MapDsuScratchDevice(&scratch_device)) {
fs_mgr_overlayfs_umount_scratch();
if (MountScratch(scratch_device)) {
fs_mgr_overlayfs_teardown_one(kScratchMountPoint, teardown_dir, ignore_change);
fs_mgr_overlayfs_umount_scratch();
}
DestroyLogicalPartition(android::gsi::kDsuScratch);
}
}
} // namespace fs_mgr
} // namespace android
bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only) {
Fstab fstab;
if (!ReadFstabFromFile("/proc/mounts", &fstab)) {
return false;
}
const auto lowerdir = kLowerdirOption + mount_point;
for (const auto& entry : fstab) {
if (overlay_only && "overlay" != entry.fs_type && "overlayfs" != entry.fs_type) continue;
if (mount_point != entry.mount_point) continue;
if (!overlay_only) return true;
const auto options = android::base::Split(entry.fs_options, ",");
for (const auto& opt : options) {
if (opt == lowerdir) {
return true;
}
}
}
return false;
}