/*
* 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 <map>
#include <memory>
#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_dm_linear.h>
#include <fs_mgr_overlayfs.h>
#include <fstab/fstab.h>
#include <libdm/dm.h>
#include <libgsi/libgsi.h>
#include <liblp/builder.h>
#include <liblp/liblp.h>
#include "fs_mgr_priv.h"
using namespace std::literals;
using namespace android::dm;
using namespace android::fs_mgr;
namespace {
bool fs_mgr_access(const std::string& path) {
auto save_errno = errno;
auto ret = access(path.c_str(), F_OK) == 0;
errno = save_errno;
return ret;
}
// determine if a filesystem is available
bool fs_mgr_overlayfs_filesystem_available(const std::string& filesystem) {
std::string filesystems;
if (!android::base::ReadFileToString("/proc/filesystems", &filesystems)) return false;
return filesystems.find("\t" + filesystem + "\n") != std::string::npos;
}
} // namespace
#if ALLOW_ADBD_DISABLE_VERITY == 0 // If we are a user build, provide stubs
Fstab fs_mgr_overlayfs_candidate_list(const Fstab&) {
return {};
}
bool fs_mgr_overlayfs_mount_all(Fstab*) {
return false;
}
std::vector<std::string> fs_mgr_overlayfs_required_devices(Fstab*) {
return {};
}
bool fs_mgr_overlayfs_setup(const char*, const char*, bool* change, bool) {
if (change) *change = false;
return false;
}
bool fs_mgr_overlayfs_teardown(const char*, bool* change) {
if (change) *change = false;
return false;
}
bool fs_mgr_overlayfs_is_setup() {
return false;
}
#else // ALLOW_ADBD_DISABLE_VERITY == 0
namespace {
// list of acceptable overlayfs backing storage
const auto kScratchMountPoint = "/mnt/scratch"s;
const auto kCacheMountPoint = "/cache"s;
const std::vector<const std::string> kOverlayMountPoints = {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);
}
// Similar test as overlayfs workdir= validation in the kernel for read-write
// validation, except we use fs_mgr_work. Covers space and storage issues.
bool fs_mgr_dir_is_writable(const std::string& path) {
auto test_directory = path + "/fs_mgr_work";
rmdir(test_directory.c_str());
auto ret = !mkdir(test_directory.c_str(), 0700);
return ret | !rmdir(test_directory.c_str());
}
// At less than 1% 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;
auto save_errno = errno;
if (statvfs(mount_point.c_str(), &vst)) {
errno = save_errno;
return true;
}
static constexpr int kPercentThreshold = 1; // 1%
return (vst.f_bfree >= (vst.f_blocks * kPercentThreshold / 100));
}
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;
}
if (entry->fs_mgr_flags.logical) {
fs_mgr_update_logical_partition(entry);
}
auto save_errno = errno;
errno = 0;
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);
}
// special case for first stage init for system as root (taimen)
if (!has_shared_blocks && (errno == ENOENT) && (entry->blk_device == "/dev/root")) {
has_shared_blocks = true;
}
errno = save_errno;
return has_shared_blocks;
}
bool fs_mgr_rm_all(const std::string& path, bool* change = nullptr, int level = 0) {
auto save_errno = errno;
std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(path.c_str()), closedir);
if (!dir) {
if (errno == ENOENT) {
errno = save_errno;
return true;
}
PERROR << "opendir " << path << " depth=" << level;
if ((errno == EPERM) && (level != 0)) {
errno = save_errno;
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;
save_errno = errno;
if (!lstat(file.c_str(), &st) && (st.st_mode & S_IFDIR)) entry->d_type = DT_DIR;
errno = save_errno;
}
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 : kOverlayMountPoints) {
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_dir_is_writable(work)) continue;
return dir;
}
return "";
}
const auto kLowerdirOption = "lowerdir="s;
const auto kUpperdirOption = "upperdir="s;
// default options for mount_point, returns empty string for none available.
std::string fs_mgr_get_overlayfs_options(const std::string& 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";
}
return ret;
}
const std::string fs_mgr_mount_point(const std::string& mount_point) {
if ("/"s != mount_point) return mount_point;
return "/system";
}
bool fs_mgr_rw_access(const std::string& path) {
if (path.empty()) return false;
auto save_errno = errno;
auto ret = access(path.c_str(), R_OK | W_OK) == 0;
errno = save_errno;
return ret;
}
bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true) {
Fstab fstab;
auto save_errno = errno;
if (!ReadFstabFromFile("/proc/mounts", &fstab)) {
return false;
}
errno = save_errno;
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;
}
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;
}
constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";
bool fs_mgr_overlayfs_setup_dir(const std::string& dir, std::string* overlay, bool* change) {
auto ret = true;
auto top = dir + kOverlayTopDir;
if (setfscreatecon(kOverlayfsFileContext)) {
ret = false;
PERROR << "setfscreatecon " << kOverlayfsFileContext;
}
auto save_errno = errno;
if (!mkdir(top.c_str(), 0755)) {
if (change) *change = true;
} else if (errno != EEXIST) {
ret = false;
PERROR << "mkdir " << top;
} else {
errno = save_errno;
}
setfscreatecon(nullptr);
if (overlay) *overlay = std::move(top);
return ret;
}
bool fs_mgr_overlayfs_setup_one(const std::string& overlay, const std::string& mount_point,
bool* change) {
auto ret = true;
if (fs_mgr_overlayfs_already_mounted(mount_point)) return ret;
auto fsrec_mount_point = overlay + "/" + android::base::Basename(mount_point) + "/";
if (setfscreatecon(kOverlayfsFileContext)) {
ret = false;
PERROR << "setfscreatecon " << kOverlayfsFileContext;
}
auto save_errno = errno;
if (!mkdir(fsrec_mount_point.c_str(), 0755)) {
if (change) *change = true;
} else if (errno != EEXIST) {
ret = false;
PERROR << "mkdir " << fsrec_mount_point;
} else {
errno = save_errno;
}
save_errno = errno;
if (!mkdir((fsrec_mount_point + kWorkName).c_str(), 0755)) {
if (change) *change = true;
} else if (errno != EEXIST) {
ret = false;
PERROR << "mkdir " << fsrec_mount_point << kWorkName;
} else {
errno = save_errno;
}
setfscreatecon(nullptr);
auto new_context = fs_mgr_get_context(mount_point);
if (!new_context.empty() && setfscreatecon(new_context.c_str())) {
ret = false;
PERROR << "setfscreatecon " << new_context;
}
auto upper = fsrec_mount_point + kUpperName;
save_errno = errno;
if (!mkdir(upper.c_str(), 0755)) {
if (change) *change = true;
} else if (errno != EEXIST) {
ret = false;
PERROR << "mkdir " << upper;
} else {
errno = save_errno;
}
if (!new_context.empty()) setfscreatecon(nullptr);
return ret;
}
uint32_t fs_mgr_overlayfs_slot_number() {
return SlotNumberForSlotSuffix(fs_mgr_get_slot_suffix());
}
const auto kPhysicalDevice = "/dev/block/by-name/"s;
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;
}
void fs_mgr_overlayfs_umount_scratch() {
// Lazy umount will allow us to move on and possibly later
// establish a new fresh mount without requiring a reboot should
// the developer wish to restart. Old references should melt
// away or have no data. Main goal is to shut the door on the
// current overrides with an expectation of a subsequent reboot,
// thus any errors here are ignored.
umount2(kScratchMountPoint.c_str(), MNT_DETACH);
LINFO << "umount(" << kScratchMountPoint << ")";
rmdir(kScratchMountPoint.c_str());
}
// reduce 'DM_DEV_STATUS failed for scratch: No such device or address' noise
std::string scratch_device_cache;
bool 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 true;
scratch_device_cache.erase();
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 true;
auto save_errno = errno;
if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
fs_mgr_overlayfs_umount_scratch();
}
auto builder = MetadataBuilder::New(super_device, slot_number);
if (!builder) {
errno = save_errno;
return true;
}
const auto partition_name = android::base::Basename(kScratchMountPoint);
if (builder->FindPartition(partition_name) == nullptr) {
errno = save_errno;
return true;
}
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, 0s)) return false;
} else {
LERROR << "delete partition " << overlay;
return false;
}
errno = save_errno;
return true;
}
bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string& mount_point,
bool* change) {
const auto top = overlay + kOverlayTopDir;
if (!fs_mgr_access(top)) return fs_mgr_overlayfs_teardown_scratch(overlay, change);
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);
auto save_errno = errno;
if (!rename(oldpath.c_str(), newpath.c_str())) {
if (change) *change = true;
} else if (errno != ENOENT) {
ret = false;
PERROR << "mv " << oldpath << " " << newpath;
} else {
errno = save_errno;
}
ret &= fs_mgr_rm_all(newpath, change);
save_errno = errno;
if (!rmdir(newpath.c_str())) {
if (change) *change = true;
} else if (errno != ENOENT) {
ret = false;
PERROR << "rmdir " << newpath;
} else {
errno = save_errno;
}
if (!cleanup_all) {
save_errno = errno;
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;
}
}
}
errno = save_errno;
} else if (errno == ENOENT) {
cleanup_all = true;
errno = save_errno;
} else {
ret = false;
PERROR << "rmdir " << top;
}
}
if (cleanup_all) ret &= fs_mgr_overlayfs_teardown_scratch(overlay, change);
return ret;
}
bool fs_mgr_overlayfs_mount(const std::string& mount_point) {
auto options = fs_mgr_get_overlayfs_options(mount_point);
if (options.empty()) return false;
// 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_RELATIME,
options.c_str());
if (ret) {
PERROR << report << ret;
return false;
} else {
LINFO << report << ret;
return true;
}
}
// Mount kScratchMountPoint
bool fs_mgr_overlayfs_mount_scratch(const std::string& device_path, const std::string mnt_type,
bool readonly = false) {
if (readonly) {
if (!fs_mgr_access(device_path)) return false;
} else {
if (!fs_mgr_rw_access(device_path)) return false;
}
auto f2fs = fs_mgr_is_f2fs(device_path);
auto ext4 = fs_mgr_is_ext4(device_path);
if (!f2fs && !ext4) return false;
if (setfscreatecon(kOverlayfsFileContext)) {
PERROR << "setfscreatecon " << kOverlayfsFileContext;
}
if (mkdir(kScratchMountPoint.c_str(), 0755) && (errno != EEXIST)) {
PERROR << "create " << kScratchMountPoint;
}
FstabEntry entry;
entry.blk_device = device_path;
entry.mount_point = kScratchMountPoint;
entry.fs_type = mnt_type;
if ((mnt_type == "f2fs") && !f2fs) entry.fs_type = "ext4";
if ((mnt_type == "ext4") && !ext4) entry.fs_type = "f2fs";
entry.flags = MS_RELATIME;
if (readonly) {
entry.flags |= MS_RDONLY;
} else {
fs_mgr_set_blk_ro(device_path, false);
}
auto save_errno = errno;
auto mounted = fs_mgr_do_mount_one(entry) == 0;
if (!mounted) {
if ((entry.fs_type == "f2fs") && ext4) {
entry.fs_type = "ext4";
mounted = fs_mgr_do_mount_one(entry) == 0;
} else if ((entry.fs_type == "ext4") && f2fs) {
entry.fs_type = "f2fs";
mounted = fs_mgr_do_mount_one(entry) == 0;
}
if (!mounted) save_errno = errno;
}
setfscreatecon(nullptr);
if (!mounted) rmdir(kScratchMountPoint.c_str());
errno = save_errno;
return mounted;
}
const std::string kMkF2fs("/system/bin/make_f2fs");
const std::string kMkExt4("/system/bin/mke2fs");
// Only a suggestion for _first_ try during mounting
std::string fs_mgr_overlayfs_scratch_mount_type() {
if (!access(kMkF2fs.c_str(), X_OK) && fs_mgr_overlayfs_filesystem_available("f2fs")) {
return "f2fs";
}
if (!access(kMkExt4.c_str(), X_OK) && fs_mgr_overlayfs_filesystem_available("ext4")) {
return "ext4";
}
return "auto";
}
std::string fs_mgr_overlayfs_scratch_device() {
if (!scratch_device_cache.empty()) return scratch_device_cache;
// Is this a multiple super device (retrofit)?
auto slot_number = fs_mgr_overlayfs_slot_number();
auto super_device = fs_mgr_overlayfs_super_device(slot_number);
auto path = fs_mgr_overlayfs_super_device(slot_number == 0);
if (super_device == path) {
// Create from within single super device;
auto& dm = DeviceMapper::Instance();
const auto partition_name = android::base::Basename(kScratchMountPoint);
if (!dm.GetDmDevicePathByName(partition_name, &path)) {
// non-DAP A/B device?
if (fs_mgr_access(super_device)) return "";
auto other_slot = fs_mgr_get_other_slot_suffix();
if (other_slot.empty()) return "";
path = kPhysicalDevice + "system" + other_slot;
}
}
return scratch_device_cache = path;
}
bool fs_mgr_overlayfs_make_scratch(const std::string& scratch_device, const std::string& mnt_type) {
// 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 command = ""s;
if (mnt_type == "f2fs") {
command = kMkF2fs + " -w 4096 -f -d1 -l" + android::base::Basename(kScratchMountPoint);
} else if (mnt_type == "ext4") {
command = kMkExt4 + " -F -b 4096 -t ext4 -m 0 -O has_journal -M " + kScratchMountPoint;
} else {
errno = ESRCH;
LERROR << mnt_type << " has no mkfs cookbook";
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 " << mnt_type << " filesystem on " << scratch_device << " return=" << ret;
return false;
}
return true;
}
bool fs_mgr_overlayfs_create_scratch(const Fstab& fstab, std::string* scratch_device,
bool* partition_exists, bool* change) {
*scratch_device = fs_mgr_overlayfs_scratch_device();
*partition_exists = fs_mgr_rw_access(*scratch_device);
auto partition_create = !*partition_exists;
// Do we need to create a logical "scratch" partition?
if (!partition_create && android::base::StartsWith(*scratch_device, kPhysicalDevice)) {
return true;
}
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 false;
if (!fs_mgr_overlayfs_has_logical(fstab)) return false;
auto builder = MetadataBuilder::New(super_device, slot_number);
if (!builder) {
LERROR << "open " << super_device << " metadata";
return false;
}
const auto partition_name = android::base::Basename(kScratchMountPoint);
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(partition_name, &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)) {
LERROR << "resize " << partition_name;
return false;
}
if (!partition_create) DestroyLogicalPartition(partition_name, 10s);
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 (change) *change = true;
}
if (changed || partition_create) {
if (!CreateLogicalPartition(super_device, slot_number, partition_name, true, 10s,
scratch_device))
return false;
if (change) *change = true;
}
return true;
}
// Create and mount kScratchMountPoint storage if we have logical partitions
bool fs_mgr_overlayfs_setup_scratch(const Fstab& fstab, bool* change) {
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, change)) {
return false;
}
// If the partition exists, assume first that it can be mounted.
auto mnt_type = fs_mgr_overlayfs_scratch_mount_type();
if (partition_exists) {
if (fs_mgr_overlayfs_mount_scratch(scratch_device, mnt_type)) {
if (!fs_mgr_access(kScratchMountPoint + kOverlayTopDir) &&
!fs_mgr_filesystem_has_space(kScratchMountPoint)) {
// declare it useless, no overrides and no free space
fs_mgr_overlayfs_umount_scratch();
} else {
if (change) *change = true;
return true;
}
}
// partition existed, but was not initialized; fall through to make it.
errno = 0;
}
if (!fs_mgr_overlayfs_make_scratch(scratch_device, mnt_type)) return false;
if (change) *change = true;
return fs_mgr_overlayfs_mount_scratch(scratch_device, mnt_type);
}
bool fs_mgr_overlayfs_scratch_can_be_mounted(const std::string& scratch_device) {
if (scratch_device.empty()) return false;
if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) return false;
if (android::base::StartsWith(scratch_device, kPhysicalDevice)) return true;
if (fs_mgr_rw_access(scratch_device)) return true;
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 false;
auto builder = MetadataBuilder::New(super_device, slot_number);
if (!builder) return false;
return builder->FindPartition(android::base::Basename(kScratchMountPoint)) != nullptr;
}
bool fs_mgr_overlayfs_invalid() {
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) return true;
// in recovery, fastbootd, or gsi mode, not allowed!
if (fs_mgr_access("/system/bin/recovery")) return true;
auto save_errno = errno;
auto ret = android::gsi::IsGsiRunning();
errno = save_errno;
return ret;
}
} // namespace
Fstab fs_mgr_overlayfs_candidate_list(const Fstab& fstab) {
Fstab candidates;
for (const auto& entry : fstab) {
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;
}
bool fs_mgr_overlayfs_mount_all(Fstab* fstab) {
auto ret = false;
if (fs_mgr_overlayfs_invalid()) return ret;
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)) {
ret = true;
continue;
}
if (scratch_can_be_mounted) {
scratch_can_be_mounted = false;
auto scratch_device = fs_mgr_overlayfs_scratch_device();
if (fs_mgr_overlayfs_scratch_can_be_mounted(scratch_device) &&
fs_mgr_wait_for_file(scratch_device, 10s)) {
const auto mount_type = fs_mgr_overlayfs_scratch_mount_type();
if (fs_mgr_overlayfs_mount_scratch(scratch_device, mount_type,
true /* readonly */)) {
auto has_overlayfs_dir = fs_mgr_access(kScratchMountPoint + kOverlayTopDir);
fs_mgr_overlayfs_umount_scratch();
if (has_overlayfs_dir) {
fs_mgr_overlayfs_mount_scratch(scratch_device, mount_type);
}
}
}
}
if (fs_mgr_overlayfs_mount(mount_point)) ret = true;
}
return ret;
}
std::vector<std::string> fs_mgr_overlayfs_required_devices(Fstab* fstab) {
if (fs_mgr_overlayfs_invalid()) return {};
if (GetEntryForMountPoint(fstab, kScratchMountPoint) != nullptr) {
return {};
}
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;
auto device = fs_mgr_overlayfs_scratch_device();
if (!fs_mgr_overlayfs_scratch_can_be_mounted(device)) break;
return {device};
}
return {};
}
// Returns false if setup not permitted, errno set to last error.
// If something is altered, set *change.
bool fs_mgr_overlayfs_setup(const char* backing, const char* mount_point, bool* change,
bool force) {
if (change) *change = false;
auto ret = false;
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) return ret;
if (!fs_mgr_boot_completed()) {
errno = EBUSY;
PERROR << "setup";
return ret;
}
auto save_errno = errno;
Fstab fstab;
if (!ReadDefaultFstab(&fstab)) {
return false;
}
errno = save_errno;
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;
}
save_errno = errno;
auto verity_enabled = !force && fs_mgr_is_verity_enabled(*it);
if (errno == ENOENT || errno == ENXIO) errno = save_errno;
if (verity_enabled) {
it = candidates.erase(it);
continue;
}
++it;
}
if (candidates.empty()) return ret;
std::string dir;
for (const auto& overlay_mount_point : kOverlayMountPoints) {
if (backing && backing[0] && (overlay_mount_point != backing)) continue;
if (overlay_mount_point == kScratchMountPoint) {
if (!fs_mgr_overlayfs_setup_scratch(fstab, change)) continue;
} else {
if (GetEntryForMountPoint(&fstab, overlay_mount_point) == nullptr) {
continue;
}
}
dir = overlay_mount_point;
break;
}
if (dir.empty()) {
if (change && *change) errno = ESRCH;
if (errno == EPERM) errno = save_errno;
return ret;
}
std::string overlay;
ret |= fs_mgr_overlayfs_setup_dir(dir, &overlay, change);
for (const auto& entry : candidates) {
ret |= fs_mgr_overlayfs_setup_one(overlay, fs_mgr_mount_point(entry.mount_point), change);
}
return ret;
}
// Returns false if teardown not permitted, errno set to last error.
// If something is altered, set *change.
bool fs_mgr_overlayfs_teardown(const char* mount_point, bool* change) {
if (change) *change = false;
auto ret = true;
// 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)) {
auto scratch_device = fs_mgr_overlayfs_scratch_device();
if (scratch_device.empty()) {
auto slot_number = fs_mgr_overlayfs_slot_number();
auto super_device = fs_mgr_overlayfs_super_device(slot_number);
const auto partition_name = android::base::Basename(kScratchMountPoint);
CreateLogicalPartition(super_device, slot_number, partition_name, true, 10s,
&scratch_device);
}
mount_scratch = fs_mgr_overlayfs_mount_scratch(scratch_device,
fs_mgr_overlayfs_scratch_mount_type());
}
for (const auto& overlay_mount_point : kOverlayMountPoints) {
ret &= fs_mgr_overlayfs_teardown_one(
overlay_mount_point, mount_point ? fs_mgr_mount_point(mount_point) : "", change);
}
if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
// After obligatory teardown to make sure everything is clean, but if
// we didn't want overlayfs in the the first place, we do not want to
// waste time on a reboot (or reboot request message).
if (change) *change = false;
}
// And now that we did what we could, lets inform
// caller that there may still be more to do.
if (!fs_mgr_boot_completed()) {
errno = EBUSY;
PERROR << "teardown";
ret = false;
}
if (mount_scratch) fs_mgr_overlayfs_umount_scratch();
return ret;
}
bool fs_mgr_overlayfs_is_setup() {
if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) return true;
Fstab fstab;
if (!ReadDefaultFstab(&fstab)) {
return false;
}
if (fs_mgr_overlayfs_invalid()) 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;
}
#endif // ALLOW_ADBD_DISABLE_VERITY != 0
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;
}
std::string fs_mgr_get_context(const std::string& mount_point) {
char* ctx = nullptr;
if (getfilecon(mount_point.c_str(), &ctx) == -1) {
return "";
}
std::string context(ctx);
free(ctx);
return context;
}
OverlayfsValidResult fs_mgr_overlayfs_valid() {
// Overlayfs available in the kernel, and patched for override_creds?
if (fs_mgr_access("/sys/module/overlay/parameters/override_creds")) {
return OverlayfsValidResult::kOverrideCredsRequired;
}
if (!fs_mgr_overlayfs_filesystem_available("overlay")) {
return OverlayfsValidResult::kNotSupported;
}
struct utsname uts;
if (uname(&uts) == -1) {
return OverlayfsValidResult::kNotSupported;
}
int major, minor;
if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) {
return OverlayfsValidResult::kNotSupported;
}
if (major < 4) {
return OverlayfsValidResult::kOk;
}
if (major > 4) {
return OverlayfsValidResult::kNotSupported;
}
if (minor > 3) {
return OverlayfsValidResult::kNotSupported;
}
return OverlayfsValidResult::kOk;
}