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platform_system_vold/VolumeManager.cpp
Momoko Hattori b4e033ed4c vold: Unmount StubVolume disks before unmounting EmulatedVolumes 
The current shutdown / reset logic in VolumeManager unmounts
EmulatedVolume first, and unmounts the other disks.

In ARC (Android on ChromeOS), ChromeOS Downloads directory (exposed from
ChromeOS to Android as a disk having StubVolume) is bind-mounted to
/data/media/0/Download in the ARC-customized version of
StubVolume::doMount() (http://shortn/_lKaAhTLhY3), and the current
unmount order causes EmulatedVolume not to be cleanly unmounted. This
patch hence changes the order of the unmount of volumes to first unmount
StubVolume disks, then unmount the EmulatedVolumes, then unmount the
non-StubVolume disks.

Bug: 304369444
Test: On an Android phone, create a virtual public volume with the
  following commands on adb shell (taken from
  android.scopedstorage.cts.lib.TestUtils.createNewPublicVolume()):
  $ sm set-force-adoptable on
  $ sm set-virtual-disk true
  $ sm list-disks  # <- This returns the virtual disk name
  $ sm partition <virtual disk name> public
  Then, run `vdc volume reset` on lynx adb shell, observe logcat from
  vold and check that no error is observed.
Test: Run `vdc volume reset` on ARC adb shell, and confirm that:
  * Without this patch, the primary emulated volume fails to unmount
    with "Device or resource busy", followed by MyFiles volume unmount.
  * With this patch, MyFiles volume is unmounted before the primary
    emulated volume, and no error is observed.

Change-Id: I54f60e3320574ccf8d3589545ff77967fff14fc7
2024-02-22 18:07:18 +09:00

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/*
* Copyright (C) 2008 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.
*/
#define ATRACE_TAG ATRACE_TAG_PACKAGE_MANAGER
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <array>
#include <linux/kdev_t.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/parseint.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <async_safe/log.h>
#include <cutils/fs.h>
#include <utils/Trace.h>
#include <selinux/android.h>
#include <sysutils/NetlinkEvent.h>
#include <private/android_filesystem_config.h>
#include <fscrypt/fscrypt.h>
#include <libdm/dm.h>
#include "AppFuseUtil.h"
#include "FsCrypt.h"
#include "Loop.h"
#include "NetlinkManager.h"
#include "Process.h"
#include "Utils.h"
#include "VoldNativeService.h"
#include "VoldUtil.h"
#include "VolumeManager.h"
#include "fs/Ext4.h"
#include "fs/Vfat.h"
#include "model/EmulatedVolume.h"
#include "model/ObbVolume.h"
#include "model/PrivateVolume.h"
#include "model/PublicVolume.h"
#include "model/StubVolume.h"
using android::OK;
using android::base::GetBoolProperty;
using android::base::StartsWith;
using android::base::StringAppendF;
using android::base::StringPrintf;
using android::base::unique_fd;
using android::vold::BindMount;
using android::vold::CreateDir;
using android::vold::DeleteDirContents;
using android::vold::DeleteDirContentsAndDir;
using android::vold::EnsureDirExists;
using android::vold::GetFuseMountPathForUser;
using android::vold::IsFilesystemSupported;
using android::vold::IsSdcardfsUsed;
using android::vold::IsVirtioBlkDevice;
using android::vold::PrepareAndroidDirs;
using android::vold::PrepareAppDirFromRoot;
using android::vold::PrivateVolume;
using android::vold::PublicVolume;
using android::vold::Symlink;
using android::vold::Unlink;
using android::vold::UnmountTree;
using android::vold::VoldNativeService;
using android::vold::VolumeBase;
static const char* kPathVirtualDisk = "/data/misc/vold/virtual_disk";
static const char* kPropVirtualDisk = "persist.sys.virtual_disk";
static const std::string kEmptyString("");
/* 512MiB is large enough for testing purposes */
static const unsigned int kSizeVirtualDisk = 536870912;
static const unsigned int kMajorBlockMmc = 179;
using ScanProcCallback = bool(*)(uid_t uid, pid_t pid, int nsFd, const char* name, void* params);
VolumeManager* VolumeManager::sInstance = NULL;
VolumeManager* VolumeManager::Instance() {
if (!sInstance) sInstance = new VolumeManager();
return sInstance;
}
VolumeManager::VolumeManager() {
mDebug = false;
mNextObbId = 0;
mNextStubId = 0;
// For security reasons, assume that a secure keyguard is
// showing until we hear otherwise
mSecureKeyguardShowing = true;
}
VolumeManager::~VolumeManager() {}
int VolumeManager::updateVirtualDisk() {
ATRACE_NAME("VolumeManager::updateVirtualDisk");
if (GetBoolProperty(kPropVirtualDisk, false)) {
if (access(kPathVirtualDisk, F_OK) != 0) {
Loop::createImageFile(kPathVirtualDisk, kSizeVirtualDisk / 512);
}
if (mVirtualDisk == nullptr) {
if (Loop::create(kPathVirtualDisk, mVirtualDiskPath) != 0) {
LOG(ERROR) << "Failed to create virtual disk";
return -1;
}
struct stat buf;
if (stat(mVirtualDiskPath.c_str(), &buf) < 0) {
PLOG(ERROR) << "Failed to stat " << mVirtualDiskPath;
return -1;
}
auto disk = new android::vold::Disk(
"virtual", buf.st_rdev, "virtual",
android::vold::Disk::Flags::kAdoptable | android::vold::Disk::Flags::kSd);
mVirtualDisk = std::shared_ptr<android::vold::Disk>(disk);
handleDiskAdded(mVirtualDisk);
}
} else {
if (mVirtualDisk != nullptr) {
dev_t device = mVirtualDisk->getDevice();
handleDiskRemoved(device);
Loop::destroyByDevice(mVirtualDiskPath.c_str());
mVirtualDisk = nullptr;
}
if (access(kPathVirtualDisk, F_OK) == 0) {
unlink(kPathVirtualDisk);
}
}
return 0;
}
int VolumeManager::setDebug(bool enable) {
mDebug = enable;
return 0;
}
int VolumeManager::start() {
ATRACE_NAME("VolumeManager::start");
// Always start from a clean slate by unmounting everything in
// directories that we own, in case we crashed.
unmountAll();
Loop::destroyAll();
// Assume that we always have an emulated volume on internal
// storage; the framework will decide if it should be mounted.
CHECK(mInternalEmulatedVolumes.empty());
auto vol = std::shared_ptr<android::vold::VolumeBase>(
new android::vold::EmulatedVolume("/data/media", 0));
vol->setMountUserId(0);
vol->create();
mInternalEmulatedVolumes.push_back(vol);
// Consider creating a virtual disk
updateVirtualDisk();
return 0;
}
void VolumeManager::handleBlockEvent(NetlinkEvent* evt) {
std::lock_guard<std::mutex> lock(mLock);
if (mDebug) {
LOG(DEBUG) << "----------------";
LOG(DEBUG) << "handleBlockEvent with action " << (int)evt->getAction();
evt->dump();
}
std::string eventPath(evt->findParam("DEVPATH") ? evt->findParam("DEVPATH") : "");
std::string devType(evt->findParam("DEVTYPE") ? evt->findParam("DEVTYPE") : "");
if (devType != "disk") return;
int major = std::stoi(evt->findParam("MAJOR"));
int minor = std::stoi(evt->findParam("MINOR"));
dev_t device = makedev(major, minor);
switch (evt->getAction()) {
case NetlinkEvent::Action::kAdd: {
for (const auto& source : mDiskSources) {
if (source->matches(eventPath)) {
// For now, assume that MMC and virtio-blk (the latter is
// specific to virtual platforms; see Utils.cpp for details)
// devices are SD, and that everything else is USB
int flags = source->getFlags();
if (major == kMajorBlockMmc || IsVirtioBlkDevice(major)) {
flags |= android::vold::Disk::Flags::kSd;
} else {
flags |= android::vold::Disk::Flags::kUsb;
}
auto disk =
new android::vold::Disk(eventPath, device, source->getNickname(), flags);
handleDiskAdded(std::shared_ptr<android::vold::Disk>(disk));
break;
}
}
break;
}
case NetlinkEvent::Action::kChange: {
LOG(VERBOSE) << "Disk at " << major << ":" << minor << " changed";
handleDiskChanged(device);
break;
}
case NetlinkEvent::Action::kRemove: {
handleDiskRemoved(device);
break;
}
default: {
LOG(WARNING) << "Unexpected block event action " << (int)evt->getAction();
break;
}
}
}
void VolumeManager::handleDiskAdded(const std::shared_ptr<android::vold::Disk>& disk) {
// For security reasons, if secure keyguard is showing, wait
// until the user unlocks the device to actually touch it
// Additionally, wait until user 0 is actually started, since we need
// the user to be up before we can mount a FUSE daemon to handle the disk.
bool userZeroStarted = mStartedUsers.find(0) != mStartedUsers.end();
if (mSecureKeyguardShowing) {
LOG(INFO) << "Found disk at " << disk->getEventPath()
<< " but delaying scan due to secure keyguard";
mPendingDisks.push_back(disk);
} else if (!userZeroStarted) {
LOG(INFO) << "Found disk at " << disk->getEventPath()
<< " but delaying scan due to user zero not having started";
mPendingDisks.push_back(disk);
} else {
disk->create();
mDisks.push_back(disk);
}
}
void VolumeManager::handleDiskChanged(dev_t device) {
for (const auto& disk : mDisks) {
if (disk->getDevice() == device) {
disk->readMetadata();
disk->readPartitions();
}
}
// For security reasons, we ignore all pending disks, since
// we'll scan them once the device is unlocked
}
void VolumeManager::handleDiskRemoved(dev_t device) {
auto i = mDisks.begin();
while (i != mDisks.end()) {
if ((*i)->getDevice() == device) {
(*i)->destroy();
i = mDisks.erase(i);
} else {
++i;
}
}
auto j = mPendingDisks.begin();
while (j != mPendingDisks.end()) {
if ((*j)->getDevice() == device) {
j = mPendingDisks.erase(j);
} else {
++j;
}
}
}
void VolumeManager::addDiskSource(const std::shared_ptr<DiskSource>& diskSource) {
std::lock_guard<std::mutex> lock(mLock);
mDiskSources.push_back(diskSource);
}
std::shared_ptr<android::vold::Disk> VolumeManager::findDisk(const std::string& id) {
for (auto disk : mDisks) {
if (disk->getId() == id) {
return disk;
}
}
return nullptr;
}
std::shared_ptr<android::vold::VolumeBase> VolumeManager::findVolume(const std::string& id) {
for (const auto& vol : mInternalEmulatedVolumes) {
if (vol->getId() == id) {
return vol;
}
}
for (const auto& disk : mDisks) {
auto vol = disk->findVolume(id);
if (vol != nullptr) {
return vol;
}
}
for (const auto& vol : mObbVolumes) {
if (vol->getId() == id) {
return vol;
}
}
return nullptr;
}
void VolumeManager::listVolumes(android::vold::VolumeBase::Type type,
std::list<std::string>& list) const {
list.clear();
for (const auto& disk : mDisks) {
disk->listVolumes(type, list);
}
}
bool VolumeManager::forgetPartition(const std::string& partGuid, const std::string& fsUuid) {
std::string normalizedGuid;
if (android::vold::NormalizeHex(partGuid, normalizedGuid)) {
LOG(WARNING) << "Invalid GUID " << partGuid;
return false;
}
std::string keyPath = android::vold::BuildKeyPath(normalizedGuid);
if (unlink(keyPath.c_str()) != 0) {
LOG(ERROR) << "Failed to unlink " << keyPath;
return false;
}
return true;
}
void VolumeManager::destroyEmulatedVolumesForUser(userid_t userId) {
// Destroy and remove all unstacked EmulatedVolumes for the user
auto i = mInternalEmulatedVolumes.begin();
while (i != mInternalEmulatedVolumes.end()) {
auto vol = *i;
if (vol->getMountUserId() == userId) {
vol->destroy();
i = mInternalEmulatedVolumes.erase(i);
} else {
i++;
}
}
// Destroy and remove all stacked EmulatedVolumes for the user on each mounted private volume
std::list<std::string> private_vols;
listVolumes(VolumeBase::Type::kPrivate, private_vols);
for (const std::string& id : private_vols) {
PrivateVolume* pvol = static_cast<PrivateVolume*>(findVolume(id).get());
std::list<std::shared_ptr<VolumeBase>> vols_to_remove;
if (pvol->getState() == VolumeBase::State::kMounted) {
for (const auto& vol : pvol->getVolumes()) {
if (vol->getMountUserId() == userId) {
vols_to_remove.push_back(vol);
}
}
for (const auto& vol : vols_to_remove) {
vol->destroy();
pvol->removeVolume(vol);
}
} // else EmulatedVolumes will be destroyed on VolumeBase#unmount
}
}
void VolumeManager::createEmulatedVolumesForUser(userid_t userId) {
// Create unstacked EmulatedVolumes for the user
auto vol = std::shared_ptr<android::vold::VolumeBase>(
new android::vold::EmulatedVolume("/data/media", userId));
vol->setMountUserId(userId);
mInternalEmulatedVolumes.push_back(vol);
vol->create();
// Create stacked EmulatedVolumes for the user on each PrivateVolume
std::list<std::string> private_vols;
listVolumes(VolumeBase::Type::kPrivate, private_vols);
for (const std::string& id : private_vols) {
PrivateVolume* pvol = static_cast<PrivateVolume*>(findVolume(id).get());
if (pvol->getState() == VolumeBase::State::kMounted) {
auto evol =
std::shared_ptr<android::vold::VolumeBase>(new android::vold::EmulatedVolume(
pvol->getPath() + "/media", pvol->getRawDevice(), pvol->getFsUuid(),
userId));
evol->setMountUserId(userId);
pvol->addVolume(evol);
evol->create();
} // else EmulatedVolumes will be created per user when on PrivateVolume#doMount
}
}
userid_t VolumeManager::getSharedStorageUser(userid_t userId) {
if (mSharedStorageUser.find(userId) == mSharedStorageUser.end()) {
return USER_UNKNOWN;
}
return mSharedStorageUser.at(userId);
}
int VolumeManager::onUserAdded(userid_t userId, int userSerialNumber,
userid_t sharesStorageWithUserId) {
LOG(INFO) << "onUserAdded: " << userId;
mAddedUsers[userId] = userSerialNumber;
if (sharesStorageWithUserId != USER_UNKNOWN) {
mSharedStorageUser[userId] = sharesStorageWithUserId;
}
return 0;
}
int VolumeManager::onUserRemoved(userid_t userId) {
LOG(INFO) << "onUserRemoved: " << userId;
onUserStopped(userId);
mAddedUsers.erase(userId);
mSharedStorageUser.erase(userId);
return 0;
}
int VolumeManager::onUserStarted(userid_t userId) {
LOG(INFO) << "onUserStarted: " << userId;
if (mStartedUsers.find(userId) == mStartedUsers.end()) {
createEmulatedVolumesForUser(userId);
std::list<std::string> public_vols;
listVolumes(VolumeBase::Type::kPublic, public_vols);
for (const std::string& id : public_vols) {
PublicVolume* pvol = static_cast<PublicVolume*>(findVolume(id).get());
if (pvol->getState() != VolumeBase::State::kMounted) {
continue;
}
if (pvol->isVisible() == 0) {
continue;
}
userid_t mountUserId = pvol->getMountUserId();
if (userId == mountUserId) {
// No need to bind mount for the user that owns the mount
continue;
}
if (mountUserId != VolumeManager::Instance()->getSharedStorageUser(userId)) {
// No need to bind if the user does not share storage with the mount owner
continue;
}
auto bindMountStatus = pvol->bindMountForUser(userId);
if (bindMountStatus != OK) {
LOG(ERROR) << "Bind Mounting Public Volume: " << pvol << " for user: " << userId
<< "Failed. Error: " << bindMountStatus;
}
}
}
mStartedUsers.insert(userId);
createPendingDisksIfNeeded();
return 0;
}
int VolumeManager::onUserStopped(userid_t userId) {
LOG(VERBOSE) << "onUserStopped: " << userId;
if (mStartedUsers.find(userId) != mStartedUsers.end()) {
destroyEmulatedVolumesForUser(userId);
}
mStartedUsers.erase(userId);
return 0;
}
void VolumeManager::createPendingDisksIfNeeded() {
bool userZeroStarted = mStartedUsers.find(0) != mStartedUsers.end();
if (!mSecureKeyguardShowing && userZeroStarted) {
// Now that secure keyguard has been dismissed and user 0 has
// started, process any pending disks
for (const auto& disk : mPendingDisks) {
disk->create();
mDisks.push_back(disk);
}
mPendingDisks.clear();
}
}
int VolumeManager::onSecureKeyguardStateChanged(bool isShowing) {
mSecureKeyguardShowing = isShowing;
createPendingDisksIfNeeded();
return 0;
}
// This code is executed after a fork so it's very important that the set of
// methods we call here is strictly limited.
//
// TODO: Get rid of this guesswork altogether and instead exec a process
// immediately after fork to do our bindding for us.
static bool childProcess(const char* storageSource, const char* userSource, int nsFd,
const char* name) {
if (setns(nsFd, CLONE_NEWNS) != 0) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to setns for %s :%s", name,
strerror(errno));
return false;
}
// NOTE: Inlined from vold::UnmountTree here to avoid using PLOG methods and
// to also protect against future changes that may cause issues across a
// fork.
if (TEMP_FAILURE_RETRY(umount2("/storage/", MNT_DETACH)) < 0 && errno != EINVAL &&
errno != ENOENT) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to unmount /storage/ :%s",
strerror(errno));
return false;
}
if (TEMP_FAILURE_RETRY(mount(storageSource, "/storage", NULL, MS_BIND | MS_REC, NULL)) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to mount %s for %s :%s",
storageSource, name, strerror(errno));
return false;
}
if (TEMP_FAILURE_RETRY(mount(NULL, "/storage", NULL, MS_REC | MS_SLAVE, NULL)) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold",
"Failed to set MS_SLAVE to /storage for %s :%s", name,
strerror(errno));
return false;
}
if (TEMP_FAILURE_RETRY(mount(userSource, "/storage/self", NULL, MS_BIND, NULL)) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to mount %s for %s :%s",
userSource, name, strerror(errno));
return false;
}
return true;
}
// Fork the process and remount storage
bool forkAndRemountChild(uid_t uid, pid_t pid, int nsFd, const char* name, void* params) {
int32_t mountMode = *static_cast<int32_t*>(params);
std::string userSource;
std::string storageSource;
pid_t child;
// Need to fix these paths to account for when sdcardfs is gone
switch (mountMode) {
case VoldNativeService::REMOUNT_MODE_NONE:
return true;
case VoldNativeService::REMOUNT_MODE_DEFAULT:
storageSource = "/mnt/runtime/default";
break;
case VoldNativeService::REMOUNT_MODE_ANDROID_WRITABLE:
case VoldNativeService::REMOUNT_MODE_INSTALLER:
storageSource = "/mnt/runtime/write";
break;
case VoldNativeService::REMOUNT_MODE_PASS_THROUGH:
return true;
default:
PLOG(ERROR) << "Unknown mode " << std::to_string(mountMode);
return false;
}
LOG(DEBUG) << "Remounting " << uid << " as " << storageSource;
// Fork a child to mount user-specific symlink helper into place
userSource = StringPrintf("/mnt/user/%d", multiuser_get_user_id(uid));
if (!(child = fork())) {
if (childProcess(storageSource.c_str(), userSource.c_str(), nsFd, name)) {
_exit(0);
} else {
_exit(1);
}
}
if (child == -1) {
PLOG(ERROR) << "Failed to fork";
return false;
} else {
TEMP_FAILURE_RETRY(waitpid(child, nullptr, 0));
}
return true;
}
// Helper function to scan all processes in /proc and call the callback if:
// 1). pid belongs to an app process
// 2). If input uid is 0 or it matches the process uid
// 3). If userId is not -1 or userId matches the process userId
bool scanProcProcesses(uid_t uid, userid_t userId, ScanProcCallback callback, void* params) {
DIR* dir;
struct dirent* de;
std::string rootName;
std::string pidName;
std::string exeName;
int pidFd;
int nsFd;
struct stat sb;
if (!(dir = opendir("/proc"))) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to opendir");
return false;
}
// Figure out root namespace to compare against below
if (!android::vold::Readlinkat(dirfd(dir), "1/ns/mnt", &rootName)) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to read root namespace");
closedir(dir);
return false;
}
async_safe_format_log(ANDROID_LOG_INFO, "vold", "Start scanning all processes");
// Poke through all running PIDs look for apps running as UID
while ((de = readdir(dir))) {
pid_t pid;
if (de->d_type != DT_DIR) continue;
if (!android::base::ParseInt(de->d_name, &pid)) continue;
pidFd = -1;
nsFd = -1;
pidFd = openat(dirfd(dir), de->d_name, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
if (pidFd < 0) {
goto next;
}
if (fstat(pidFd, &sb) != 0) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to stat %s", de->d_name);
goto next;
}
if (uid != 0 && sb.st_uid != uid) {
goto next;
}
if (userId != static_cast<userid_t>(-1) && multiuser_get_user_id(sb.st_uid) != userId) {
goto next;
}
// Matches so far, but refuse to touch if in root namespace
if (!android::vold::Readlinkat(pidFd, "ns/mnt", &pidName)) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold",
"Failed to read namespacefor %s", de->d_name);
goto next;
}
if (rootName == pidName) {
goto next;
}
// Some early native processes have mount namespaces that are different
// from that of the init. Therefore, above check can't filter them out.
// Since the propagation type of / is 'shared', unmounting /storage
// for the early native processes affects other processes including
// init. Filter out such processes by skipping if a process is a
// non-Java process whose UID is < AID_APP_START. (The UID condition
// is required to not filter out child processes spawned by apps.)
if (!android::vold::Readlinkat(pidFd, "exe", &exeName)) {
goto next;
}
if (!StartsWith(exeName, "/system/bin/app_process") && sb.st_uid < AID_APP_START) {
goto next;
}
// We purposefully leave the namespace open across the fork
// NOLINTNEXTLINE(android-cloexec-open): Deliberately not O_CLOEXEC
nsFd = openat(pidFd, "ns/mnt", O_RDONLY);
if (nsFd < 0) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold",
"Failed to open namespace for %s", de->d_name);
goto next;
}
if (!callback(sb.st_uid, pid, nsFd, de->d_name, params)) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed in callback");
}
next:
close(nsFd);
close(pidFd);
}
closedir(dir);
async_safe_format_log(ANDROID_LOG_INFO, "vold", "Finished scanning all processes");
return true;
}
// In each app's namespace, unmount obb and data dirs
static bool umountStorageDirs(int nsFd, const char* android_data_dir, const char* android_obb_dir,
int uid, const char* targets[], int size) {
// This code is executed after a fork so it's very important that the set of
// methods we call here is strictly limited.
if (setns(nsFd, CLONE_NEWNS) != 0) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to setns %s", strerror(errno));
return false;
}
// Unmount of Android/data/foo needs to be done before Android/data below.
bool result = true;
for (int i = 0; i < size; i++) {
if (TEMP_FAILURE_RETRY(umount2(targets[i], MNT_DETACH)) < 0 && errno != EINVAL &&
errno != ENOENT) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to umount %s: %s",
targets[i], strerror(errno));
result = false;
}
}
// Mount tmpfs on Android/data and Android/obb
if (TEMP_FAILURE_RETRY(umount2(android_data_dir, MNT_DETACH)) < 0 && errno != EINVAL &&
errno != ENOENT) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to umount %s :%s",
android_data_dir, strerror(errno));
result = false;
}
if (TEMP_FAILURE_RETRY(umount2(android_obb_dir, MNT_DETACH)) < 0 && errno != EINVAL &&
errno != ENOENT) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to umount %s :%s",
android_obb_dir, strerror(errno));
result = false;
}
return result;
}
// In each app's namespace, mount tmpfs on obb and data dir, and bind mount obb and data
// package dirs.
static bool remountStorageDirs(int nsFd, const char* android_data_dir, const char* android_obb_dir,
int uid, const char* sources[], const char* targets[], int size) {
// This code is executed after a fork so it's very important that the set of
// methods we call here is strictly limited.
if (setns(nsFd, CLONE_NEWNS) != 0) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to setns %s", strerror(errno));
return false;
}
// Mount tmpfs on Android/data and Android/obb
if (TEMP_FAILURE_RETRY(mount("tmpfs", android_data_dir, "tmpfs",
MS_NOSUID | MS_NODEV | MS_NOEXEC, "uid=0,gid=0,mode=0751")) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to mount tmpfs to %s :%s",
android_data_dir, strerror(errno));
return false;
}
if (TEMP_FAILURE_RETRY(mount("tmpfs", android_obb_dir, "tmpfs",
MS_NOSUID | MS_NODEV | MS_NOEXEC, "uid=0,gid=0,mode=0751")) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to mount tmpfs to %s :%s",
android_obb_dir, strerror(errno));
return false;
}
for (int i = 0; i < size; i++) {
// Create package dir and bind mount it to the actual one.
if (TEMP_FAILURE_RETRY(mkdir(targets[i], 0700)) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to mkdir %s %s",
targets[i], strerror(errno));
return false;
}
if (TEMP_FAILURE_RETRY(mount(sources[i], targets[i], NULL, MS_BIND | MS_REC, NULL)) == -1) {
async_safe_format_log(ANDROID_LOG_ERROR, "vold", "Failed to mount %s to %s :%s",
sources[i], targets[i], strerror(errno));
return false;
}
}
return true;
}
static std::string getStorageDirSrc(userid_t userId, const std::string& dirName,
const std::string& packageName) {
if (IsSdcardfsUsed()) {
return StringPrintf("/mnt/runtime/default/emulated/%d/%s/%s",
userId, dirName.c_str(), packageName.c_str());
} else {
return StringPrintf("/mnt/pass_through/%d/emulated/%d/%s/%s",
userId, userId, dirName.c_str(), packageName.c_str());
}
}
static std::string getStorageDirTarget(userid_t userId, std::string dirName,
std::string packageName) {
return StringPrintf("/storage/emulated/%d/%s/%s",
userId, dirName.c_str(), packageName.c_str());
}
// Fork the process and remount / unmount app data and obb dirs
bool VolumeManager::forkAndRemountStorage(int uid, int pid, bool doUnmount,
const std::vector<std::string>& packageNames) {
userid_t userId = multiuser_get_user_id(uid);
std::string mnt_path = StringPrintf("/proc/%d/ns/mnt", pid);
android::base::unique_fd nsFd(
TEMP_FAILURE_RETRY(open(mnt_path.c_str(), O_RDONLY | O_CLOEXEC)));
if (nsFd == -1) {
PLOG(ERROR) << "Unable to open " << mnt_path.c_str();
return false;
}
// Storing both Android/obb and Android/data paths.
int size = packageNames.size() * 2;
std::unique_ptr<std::string[]> sources(new std::string[size]);
std::unique_ptr<std::string[]> targets(new std::string[size]);
std::unique_ptr<const char*[]> sources_uptr(new const char*[size]);
std::unique_ptr<const char*[]> targets_uptr(new const char*[size]);
const char** sources_cstr = sources_uptr.get();
const char** targets_cstr = targets_uptr.get();
for (int i = 0; i < size; i += 2) {
std::string const& packageName = packageNames[i/2];
sources[i] = getStorageDirSrc(userId, "Android/data", packageName);
targets[i] = getStorageDirTarget(userId, "Android/data", packageName);
sources[i+1] = getStorageDirSrc(userId, "Android/obb", packageName);
targets[i+1] = getStorageDirTarget(userId, "Android/obb", packageName);
sources_cstr[i] = sources[i].c_str();
targets_cstr[i] = targets[i].c_str();
sources_cstr[i+1] = sources[i+1].c_str();
targets_cstr[i+1] = targets[i+1].c_str();
}
for (int i = 0; i < size; i++) {
// Make sure /storage/emulated/... paths are setup correctly
// This needs to be done before EnsureDirExists to ensure Android/ is created.
auto status = setupAppDir(targets_cstr[i], uid, false /* fixupExistingOnly */);
if (status != OK) {
PLOG(ERROR) << "Failed to create dir: " << targets_cstr[i];
return false;
}
status = EnsureDirExists(sources_cstr[i], 0771, AID_MEDIA_RW, AID_MEDIA_RW);
if (status != OK) {
PLOG(ERROR) << "Failed to create dir: " << sources_cstr[i];
return false;
}
}
char android_data_dir[PATH_MAX];
char android_obb_dir[PATH_MAX];
snprintf(android_data_dir, PATH_MAX, "/storage/emulated/%d/Android/data", userId);
snprintf(android_obb_dir, PATH_MAX, "/storage/emulated/%d/Android/obb", userId);
pid_t child;
// Fork a child to mount Android/obb android Android/data dirs, as we don't want it to affect
// original vold process mount namespace.
if (!(child = fork())) {
if (doUnmount) {
if (umountStorageDirs(nsFd, android_data_dir, android_obb_dir, uid,
targets_cstr, size)) {
_exit(0);
} else {
_exit(1);
}
} else {
if (remountStorageDirs(nsFd, android_data_dir, android_obb_dir, uid,
sources_cstr, targets_cstr, size)) {
_exit(0);
} else {
_exit(1);
}
}
}
if (child == -1) {
PLOG(ERROR) << "Failed to fork";
return false;
} else {
int status;
if (TEMP_FAILURE_RETRY(waitpid(child, &status, 0)) == -1) {
PLOG(ERROR) << "Failed to waitpid: " << child;
return false;
}
if (!WIFEXITED(status)) {
PLOG(ERROR) << "Process did not exit normally, status: " << status;
return false;
}
if (WEXITSTATUS(status)) {
PLOG(ERROR) << "Process exited with code: " << WEXITSTATUS(status);
return false;
}
}
return true;
}
int VolumeManager::handleAppStorageDirs(int uid, int pid,
bool doUnmount, const std::vector<std::string>& packageNames) {
// Only run the remount if fuse is mounted for that user.
userid_t userId = multiuser_get_user_id(uid);
bool fuseMounted = false;
for (auto& vol : mInternalEmulatedVolumes) {
if (vol->getMountUserId() == userId && vol->getState() == VolumeBase::State::kMounted) {
auto* emulatedVol = static_cast<android::vold::EmulatedVolume*>(vol.get());
if (emulatedVol) {
fuseMounted = emulatedVol->isFuseMounted();
}
break;
}
}
if (fuseMounted) {
forkAndRemountStorage(uid, pid, doUnmount, packageNames);
}
return 0;
}
int VolumeManager::abortFuse() {
return android::vold::AbortFuseConnections();
}
int VolumeManager::reset() {
// Tear down all existing disks/volumes and start from a blank slate so
// newly connected framework hears all events.
// Destroy StubVolume disks. This needs to be done before destroying
// EmulatedVolumes because in ARC (Android on ChromeOS), ChromeOS Downloads
// directory (which is in a StubVolume) is bind-mounted to
// /data/media/0/Download.
// We do not recreate StubVolumes here because they are managed from outside
// Android (e.g. from ChromeOS) and their disk recreation on reset events
// should be handled from outside by calling createStubVolume() again.
for (const auto& disk : mDisks) {
if (disk->isStub()) {
disk->destroy();
}
}
// Remove StubVolume from both mDisks and mPendingDisks.
const auto isStub = [](const auto& disk) { return disk->isStub(); };
mDisks.remove_if(isStub);
mPendingDisks.remove_if(isStub);
for (const auto& vol : mInternalEmulatedVolumes) {
vol->destroy();
}
mInternalEmulatedVolumes.clear();
// Destroy and recreate non-StubVolume disks.
for (const auto& disk : mDisks) {
disk->destroy();
disk->create();
}
updateVirtualDisk();
mAddedUsers.clear();
mStartedUsers.clear();
mSharedStorageUser.clear();
// Abort all FUSE connections to avoid deadlocks if the FUSE daemon was killed
// with FUSE fds open.
abortFuse();
return 0;
}
// Can be called twice (sequentially) during shutdown. should be safe for that.
int VolumeManager::shutdown() {
if (mInternalEmulatedVolumes.empty()) {
return 0; // already shutdown
}
android::vold::sSleepOnUnmount = false;
// Destroy StubVolume disks before destroying EmulatedVolumes (see the
// comment in VolumeManager::reset()).
for (const auto& disk : mDisks) {
if (disk->isStub()) {
disk->destroy();
}
}
for (const auto& vol : mInternalEmulatedVolumes) {
vol->destroy();
}
for (const auto& disk : mDisks) {
if (!disk->isStub()) {
disk->destroy();
}
}
mInternalEmulatedVolumes.clear();
mDisks.clear();
mPendingDisks.clear();
android::vold::sSleepOnUnmount = true;
return 0;
}
int VolumeManager::unmountAll() {
std::lock_guard<std::mutex> lock(mLock);
ATRACE_NAME("VolumeManager::unmountAll()");
// First, try gracefully unmounting all known devices
// Unmount StubVolume disks before unmounting EmulatedVolumes (see the
// comment in VolumeManager::reset()).
for (const auto& disk : mDisks) {
if (disk->isStub()) {
disk->unmountAll();
}
}
for (const auto& vol : mInternalEmulatedVolumes) {
vol->unmount();
}
for (const auto& disk : mDisks) {
if (!disk->isStub()) {
disk->unmountAll();
}
}
// Worst case we might have some stale mounts lurking around, so
// force unmount those just to be safe.
FILE* fp = setmntent("/proc/mounts", "re");
if (fp == NULL) {
PLOG(ERROR) << "Failed to open /proc/mounts";
return -errno;
}
// Some volumes can be stacked on each other, so force unmount in
// reverse order to give us the best chance of success.
std::list<std::string> toUnmount;
mntent* mentry;
while ((mentry = getmntent(fp)) != NULL) {
auto test = std::string(mentry->mnt_dir);
if ((StartsWith(test, "/mnt/") &&
#ifdef __ANDROID_DEBUGGABLE__
!StartsWith(test, "/mnt/scratch") &&
#endif
!StartsWith(test, "/mnt/vendor") && !StartsWith(test, "/mnt/product") &&
!StartsWith(test, "/mnt/installer") && !StartsWith(test, "/mnt/androidwritable")) ||
StartsWith(test, "/storage/")) {
toUnmount.push_front(test);
}
}
endmntent(fp);
for (const auto& path : toUnmount) {
LOG(DEBUG) << "Tearing down stale mount " << path;
android::vold::ForceUnmount(path);
}
return 0;
}
int VolumeManager::ensureAppDirsCreated(const std::vector<std::string>& paths, int32_t appUid) {
int size = paths.size();
for (int i = 0; i < size; i++) {
int result = setupAppDir(paths[i], appUid, false /* fixupExistingOnly */,
true /* skipIfDirExists */);
if (result != OK) {
return result;
}
}
return OK;
}
int VolumeManager::setupAppDir(const std::string& path, int32_t appUid, bool fixupExistingOnly,
bool skipIfDirExists) {
// Only offer to create directories for paths managed by vold
if (!StartsWith(path, "/storage/")) {
LOG(ERROR) << "Failed to find mounted volume for " << path;
return -EINVAL;
}
// Find the volume it belongs to
auto filter_fn = [&](const VolumeBase& vol) {
if (vol.getState() != VolumeBase::State::kMounted) {
// The volume must be mounted
return false;
}
if (!vol.isVisibleForWrite()) {
// App dirs should only be created for writable volumes.
return false;
}
if (vol.getInternalPath().empty()) {
return false;
}
if (vol.getMountUserId() != USER_UNKNOWN &&
vol.getMountUserId() != multiuser_get_user_id(appUid)) {
// The app dir must be created on a volume with the same user-id
return false;
}
if (!path.empty() && StartsWith(path, vol.getPath())) {
return true;
}
return false;
};
auto volume = findVolumeWithFilter(filter_fn);
if (volume == nullptr) {
LOG(ERROR) << "Failed to find mounted volume for " << path;
return -EINVAL;
}
// Convert paths to lower filesystem paths to avoid making FUSE requests for these reasons:
// 1. A FUSE request from vold puts vold at risk of hanging if the FUSE daemon is down
// 2. The FUSE daemon prevents requests on /mnt/user/0/emulated/<userid != 0> and a request
// on /storage/emulated/10 means /mnt/user/0/emulated/10
const std::string lowerPath =
volume->getInternalPath() + path.substr(volume->getPath().length());
const std::string volumeRoot = volume->getRootPath(); // eg /data/media/0
const int access_result = access(lowerPath.c_str(), F_OK);
if (fixupExistingOnly && access_result != 0) {
// Nothing to fixup
return OK;
}
if (skipIfDirExists && access_result == 0) {
// It's safe to assume it's ok as it will be used for zygote to bind mount dir only,
// which the dir doesn't need to have correct permission for now yet.
return OK;
}
if (volume->getType() == VolumeBase::Type::kPublic) {
// On public volumes, we don't need to setup permissions, as everything goes through
// FUSE; just create the dirs and be done with it.
return fs_mkdirs(lowerPath.c_str(), 0700);
}
// Create the app paths we need from the root
return PrepareAppDirFromRoot(lowerPath, volumeRoot, appUid, fixupExistingOnly);
}
int VolumeManager::fixupAppDir(const std::string& path, int32_t appUid) {
if (IsSdcardfsUsed()) {
//sdcardfs magically does this for us
return OK;
}
return setupAppDir(path, appUid, true /* fixupExistingOnly */);
}
int VolumeManager::createObb(const std::string& sourcePath, int32_t ownerGid,
std::string* outVolId) {
int id = mNextObbId++;
std::string lowerSourcePath;
// Convert to lower filesystem path
if (StartsWith(sourcePath, "/storage/")) {
auto filter_fn = [&](const VolumeBase& vol) {
if (vol.getState() != VolumeBase::State::kMounted) {
// The volume must be mounted
return false;
}
if (!vol.isVisibleForWrite()) {
// Obb volume should only be created for writable volumes.
return false;
}
if (vol.getInternalPath().empty()) {
return false;
}
if (!sourcePath.empty() && StartsWith(sourcePath, vol.getPath())) {
return true;
}
return false;
};
auto volume = findVolumeWithFilter(filter_fn);
if (volume == nullptr) {
LOG(ERROR) << "Failed to find mounted volume for " << sourcePath;
return -EINVAL;
} else {
lowerSourcePath =
volume->getInternalPath() + sourcePath.substr(volume->getPath().length());
}
} else {
lowerSourcePath = sourcePath;
}
auto vol = std::shared_ptr<android::vold::VolumeBase>(
new android::vold::ObbVolume(id, lowerSourcePath, ownerGid));
vol->create();
mObbVolumes.push_back(vol);
*outVolId = vol->getId();
return android::OK;
}
int VolumeManager::destroyObb(const std::string& volId) {
auto i = mObbVolumes.begin();
while (i != mObbVolumes.end()) {
if ((*i)->getId() == volId) {
(*i)->destroy();
i = mObbVolumes.erase(i);
} else {
++i;
}
}
return android::OK;
}
int VolumeManager::createStubVolume(const std::string& sourcePath, const std::string& mountPath,
const std::string& fsType, const std::string& fsUuid,
const std::string& fsLabel, int32_t flags,
std::string* outVolId) {
dev_t stubId = --mNextStubId;
auto vol = std::shared_ptr<android::vold::StubVolume>(
new android::vold::StubVolume(stubId, sourcePath, mountPath, fsType, fsUuid, fsLabel));
int32_t passedFlags = 0;
passedFlags |= (flags & android::vold::Disk::Flags::kUsb);
passedFlags |= (flags & android::vold::Disk::Flags::kSd);
if (flags & android::vold::Disk::Flags::kStubVisible) {
passedFlags |= (flags & android::vold::Disk::Flags::kStubVisible);
} else {
passedFlags |= (flags & android::vold::Disk::Flags::kStubInvisible);
}
// StubDisk doesn't have device node corresponds to it. So, a fake device
// number is used.
auto disk = std::shared_ptr<android::vold::Disk>(
new android::vold::Disk("stub", stubId, "stub", passedFlags));
disk->initializePartition(vol);
handleDiskAdded(disk);
*outVolId = vol->getId();
return android::OK;
}
int VolumeManager::destroyStubVolume(const std::string& volId) {
auto tokens = android::base::Split(volId, ":");
CHECK(tokens.size() == 2);
dev_t stubId;
CHECK(android::base::ParseUint(tokens[1], &stubId));
handleDiskRemoved(stubId);
return android::OK;
}
int VolumeManager::mountAppFuse(uid_t uid, int mountId, unique_fd* device_fd) {
return android::vold::MountAppFuse(uid, mountId, device_fd);
}
int VolumeManager::unmountAppFuse(uid_t uid, int mountId) {
return android::vold::UnmountAppFuse(uid, mountId);
}
int VolumeManager::openAppFuseFile(uid_t uid, int mountId, int fileId, int flags) {
return android::vold::OpenAppFuseFile(uid, mountId, fileId, flags);
}
android::status_t android::vold::GetStorageSize(int64_t* storageSize) {
// Start with the /data mount point from fs_mgr
auto entry = android::fs_mgr::GetEntryForMountPoint(&fstab_default, DATA_MNT_POINT);
if (entry == nullptr) {
LOG(ERROR) << "No mount point entry for " << DATA_MNT_POINT;
return EINVAL;
}
// Follow any symbolic links
std::string blkDevice = entry->blk_device;
std::string dataDevice;
if (!android::base::Realpath(blkDevice, &dataDevice)) {
dataDevice = blkDevice;
}
// Handle mapped volumes.
auto& dm = android::dm::DeviceMapper::Instance();
for (;;) {
auto parent = dm.GetParentBlockDeviceByPath(dataDevice);
if (!parent.has_value()) break;
dataDevice = *parent;
}
// Get the potential /sys/block entry
std::size_t leaf = dataDevice.rfind('/');
if (leaf == std::string::npos) {
LOG(ERROR) << "data device " << dataDevice << " is not a path";
return EINVAL;
}
if (dataDevice.substr(0, leaf) != "/dev/block") {
LOG(ERROR) << "data device " << dataDevice << " is not a block device";
return EINVAL;
}
std::string sysfs = std::string() + "/sys/block/" + dataDevice.substr(leaf + 1);
// Look for a directory in /sys/block containing size where the name is a shortened
// version of the name we now have
// Typically we start with something like /sys/block/sda2, and we want /sys/block/sda
// Note that this directory only contains actual disks, not partitions, so this is
// not going to find anything other than the disks
std::string size;
std::string sizeFile;
for (std::string sysfsDir = sysfs;; sysfsDir = sysfsDir.substr(0, sysfsDir.size() - 1)) {
if (sysfsDir.back() == '/') {
LOG(ERROR) << "Could not find valid block device from " << sysfs;
return EINVAL;
}
sizeFile = sysfsDir + "/size";
if (android::base::ReadFileToString(sizeFile, &size, true)) {
break;
}
}
// Read the size file and be done
std::stringstream ssSize(size);
ssSize >> *storageSize;
if (ssSize.fail()) {
LOG(ERROR) << sizeFile << " cannot be read as an integer";
return EINVAL;
}
*storageSize *= 512;
return OK;
}
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