Gitiles
Code Review Sign In
review.shift-gmbh.com / SHIFTPHONES / android_packages_providers_MediaProvider / refs/heads/sos-5.x / . / jni / FuseDaemon.cpp
blob: b2b8ab32cd1a3eb5adc43625160feb7dc7f91b96 [file] [log] [blame] [edit]
// Copyright (C) 2019 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_APP
#define LOG_TAG "FuseDaemon"
#define LIBFUSE_LOG_TAG "libfuse"
#include "FuseDaemon.h"
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <android/log.h>
#include <android/trace.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <fuse_i.h>
#include <fuse_kernel.h>
#include <fuse_log.h>
#include <fuse_lowlevel.h>
#include <inttypes.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/statvfs.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include <iostream>
#include <map>
#include <mutex>
#include <queue>
#include <regex>
#include <thread>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#define BPF_FD_JUST_USE_INT
#include "BpfSyscallWrappers.h"
#include "MediaProviderWrapper.h"
#include "libfuse_jni/FuseUtils.h"
#include "libfuse_jni/ReaddirHelper.h"
#include "libfuse_jni/RedactionInfo.h"
using mediaprovider::fuse::DirectoryEntry;
using mediaprovider::fuse::dirhandle;
using mediaprovider::fuse::handle;
using mediaprovider::fuse::node;
using mediaprovider::fuse::RedactionInfo;
using std::string;
using std::vector;
// logging macros to avoid duplication.
#define TRACE_NODE(__node, __req) \
LOG(VERBOSE) << __FUNCTION__ << " : " << #__node << " = [" << get_name(__node) \
<< "] (uid=" << (__req)->ctx.uid << ") "
#define ATRACE_NAME(name) ScopedTrace ___tracer(name)
#define ATRACE_CALL() ATRACE_NAME(__FUNCTION__)
class ScopedTrace {
public:
explicit inline ScopedTrace(const char *name) {
ATrace_beginSection(name);
}
inline ~ScopedTrace() {
ATrace_endSection();
}
};
const bool IS_OS_DEBUGABLE = android::base::GetIntProperty("ro.debuggable", 0);
#define FUSE_UNKNOWN_INO 0xffffffff
// Stolen from: android_filesystem_config.h
#define AID_APP_START 10000
constexpr size_t MAX_READ_SIZE = 128 * 1024;
// Stolen from: UserHandle#getUserId
constexpr int PER_USER_RANGE = 100000;
// Stolen from: UserManagerService
constexpr int MAX_USER_ID = UINT32_MAX / PER_USER_RANGE;
const int MY_UID = getuid();
const int MY_USER_ID = MY_UID / PER_USER_RANGE;
const std::string MY_USER_ID_STRING(std::to_string(MY_UID / PER_USER_RANGE));
// Regex copied from FileUtils.java in MediaProvider, but without media directory.
const std::regex PATTERN_OWNED_PATH(
"^/storage/[^/]+/(?:[0-9]+/)?Android/(?:data|obb)/([^/]+)(/?.*)?",
std::regex_constants::icase);
const std::regex PATTERN_BPF_BACKING_PATH("^/storage/[^/]+/[0-9]+/Android/(data|obb)$",
std::regex_constants::icase);
static constexpr char TRANSFORM_SYNTHETIC_DIR[] = "synthetic";
static constexpr char TRANSFORM_TRANSCODE_DIR[] = "transcode";
static constexpr char PRIMARY_VOLUME_PREFIX[] = "/storage/emulated";
static constexpr char FUSE_BPF_PROG_PATH[] = "/sys/fs/bpf/prog_fuse_media_fuse_media";
enum class BpfFd { REMOVE = -1 };
/*
* In order to avoid double caching with fuse, call fadvise on the file handles
* in the underlying file system. However, if this is done on every read/write,
* the fadvises cause a very significant slowdown in tests (specifically fio
* seq_write). So call fadvise on the file handles with the most reads/writes
* only after a threshold is passed.
*/
class FAdviser {
public:
FAdviser() : thread_(MessageLoop, this), total_size_(0) {}
~FAdviser() {
SendMessage(Message::quit);
thread_.join();
}
void Record(int fd, size_t size) { SendMessage(Message::record, fd, size); }
void Close(int fd) { SendMessage(Message::close, fd); }
private:
struct Message {
enum Type { record, close, quit };
Type type;
int fd;
size_t size;
};
void RecordImpl(int fd, size_t size) {
total_size_ += size;
// Find or create record in files_
// Remove record from sizes_ if it exists, adjusting size appropriately
auto file = files_.find(fd);
if (file != files_.end()) {
auto old_size = file->second;
size += old_size->first;
sizes_.erase(old_size);
} else {
file = files_.insert(Files::value_type(fd, sizes_.end())).first;
}
// Now (re) insert record in sizes_
auto new_size = sizes_.insert(Sizes::value_type(size, fd));
file->second = new_size;
if (total_size_ < threshold_) return;
LOG(INFO) << "Threshold exceeded - fadvising " << total_size_;
while (!sizes_.empty() && total_size_ > target_) {
auto size = --sizes_.end();
total_size_ -= size->first;
posix_fadvise(size->second, 0, 0, POSIX_FADV_DONTNEED);
files_.erase(size->second);
sizes_.erase(size);
}
LOG(INFO) << "Threshold now " << total_size_;
}
void CloseImpl(int fd) {
auto file = files_.find(fd);
if (file == files_.end()) return;
total_size_ -= file->second->first;
sizes_.erase(file->second);
files_.erase(file);
}
void MessageLoopImpl() {
while (1) {
Message message;
{
std::unique_lock<std::mutex> lock(mutex_);
cv_.wait(lock, [this] { return !queue_.empty(); });
message = queue_.front();
queue_.pop();
}
switch (message.type) {
case Message::record:
RecordImpl(message.fd, message.size);
break;
case Message::close:
CloseImpl(message.fd);
break;
case Message::quit:
return;
}
}
}
static int MessageLoop(FAdviser* ptr) {
ptr->MessageLoopImpl();
return 0;
}
void SendMessage(Message::Type type, int fd = -1, size_t size = 0) {
{
std::unique_lock<std::mutex> lock(mutex_);
Message message = {type, fd, size};
queue_.push(message);
}
cv_.notify_one();
}
std::mutex mutex_;
std::condition_variable cv_;
std::queue<Message> queue_;
std::thread thread_;
typedef std::multimap<size_t, int> Sizes;
typedef std::map<int, Sizes::iterator> Files;
Files files_;
Sizes sizes_;
size_t total_size_;
const size_t threshold_ = 64 * 1024 * 1024;
const size_t target_ = 32 * 1024 * 1024;
};
/* Single FUSE mount */
struct fuse {
explicit fuse(const std::string& _path, const ino_t _ino, const bool _uncached_mode,
const bool _bpf, const int _bpf_fd,
const std::vector<string>& _supported_transcoding_relative_paths,
const std::vector<string>& _supported_uncached_relative_paths)
: path(_path),
tracker(mediaprovider::fuse::NodeTracker(&lock)),
root(node::CreateRoot(_path, &lock, _ino, &tracker)),
uncached_mode(_uncached_mode),
mp(0),
zero_addr(0),
disable_dentry_cache(false),
passthrough(false),
bpf(_bpf),
bpf_fd(_bpf_fd),
supported_transcoding_relative_paths(_supported_transcoding_relative_paths),
supported_uncached_relative_paths(_supported_uncached_relative_paths) {}
inline bool IsRoot(const node* node) const { return node == root; }
inline string GetEffectiveRootPath() {
if (android::base::StartsWith(path, PRIMARY_VOLUME_PREFIX)) {
return path + "/" + MY_USER_ID_STRING;
}
return path;
}
inline string GetTransformsDir() { return GetEffectiveRootPath() + "/.transforms"; }
// Note that these two (FromInode / ToInode) conversion wrappers are required
// because fuse_lowlevel_ops documents that the root inode is always one
// (see FUSE_ROOT_ID in fuse_lowlevel.h). There are no particular requirements
// on any of the other inodes in the FS.
inline node* FromInode(__u64 inode) {
if (inode == FUSE_ROOT_ID) {
return root;
}
return node::FromInode(inode, &tracker);
}
inline node* FromInodeNoThrow(__u64 inode) {
if (inode == FUSE_ROOT_ID) {
return root;
}
return node::FromInodeNoThrow(inode, &tracker);
}
inline __u64 ToInode(node* node) const {
if (IsRoot(node)) {
return FUSE_ROOT_ID;
}
return node::ToInode(node);
}
inline bool IsTranscodeSupportedPath(const string& path) {
// Keep in sync with MediaProvider#supportsTranscode
if (!android::base::EndsWithIgnoreCase(path, ".mp4")) {
return false;
}
const std::string& base_path = GetEffectiveRootPath() + "/";
for (const std::string& relative_path : supported_transcoding_relative_paths) {
if (android::base::StartsWithIgnoreCase(path, base_path + relative_path)) {
return true;
}
}
return false;
}
inline bool IsUncachedPath(const std::string& path) {
const std::string base_path = GetEffectiveRootPath() + "/";
for (const std::string& relative_path : supported_uncached_relative_paths) {
if (android::base::StartsWithIgnoreCase(path, base_path + relative_path)) {
return true;
}
}
return false;
}
inline bool ShouldNotCache(const std::string& path) {
if (uncached_mode) {
// Cache is disabled for the entire volume.
return true;
}
if (supported_uncached_relative_paths.empty()) {
// By default there is no supported uncached path. Just return early in this case.
return false;
}
if (!android::base::StartsWithIgnoreCase(path, PRIMARY_VOLUME_PREFIX)) {
// Uncached path config applies only to primary volumes.
return false;
}
if (android::base::EndsWith(path, "/")) {
return IsUncachedPath(path);
} else {
// Append a slash at the end to make sure that the exact match is picked up.
return IsUncachedPath(path + "/");
}
}
std::recursive_mutex lock;
const string path;
// The Inode tracker associated with this FUSE instance.
mediaprovider::fuse::NodeTracker tracker;
node* const root;
struct fuse_session* se;
const bool uncached_mode;
/*
* Used to make JNI calls to MediaProvider.
* Responsibility of freeing this object falls on corresponding
* FuseDaemon object.
*/
mediaprovider::fuse::MediaProviderWrapper* mp;
/*
* Points to a range of zeroized bytes, used by pf_read to represent redacted ranges.
* The memory is read only and should never be modified.
*/
/* const */ char* zero_addr;
FAdviser fadviser;
std::atomic_bool* active;
std::atomic_bool disable_dentry_cache;
std::atomic_bool passthrough;
std::atomic_bool bpf;
const int bpf_fd;
// FUSE device id.
std::atomic_uint dev;
const std::vector<string> supported_transcoding_relative_paths;
const std::vector<string> supported_uncached_relative_paths;
};
struct OpenInfo {
int flags;
bool for_write;
bool direct_io;
};
enum class FuseOp { lookup, readdir, mknod, mkdir, create };
static inline string get_name(node* n) {
if (n) {
std::string name = IS_OS_DEBUGABLE ? "real_path: " + n->BuildPath() + " " : "";
name += "node_path: " + n->BuildSafePath();
return name;
}
return "?";
}
static inline __u64 ptr_to_id(const void* ptr) {
return (__u64)(uintptr_t) ptr;
}
/*
* Set an F_RDLCK or F_WRLCKK on fd with fcntl(2).
*
* This is called before the MediaProvider returns fd from the lower file
* system to an app over the ContentResolver interface. This allows us
* check with is_file_locked if any reference to that fd is still open.
*/
static int set_file_lock(int fd, bool for_read, const std::string& path) {
std::string lock_str = (for_read ? "read" : "write");
struct flock fl{};
fl.l_type = for_read ? F_RDLCK : F_WRLCK;
fl.l_whence = SEEK_SET;
int res = fcntl(fd, F_OFD_SETLK, &fl);
if (res) {
PLOG(WARNING) << "Failed to set lock: " << lock_str;
return res;
}
return res;
}
/*
* Check if an F_RDLCK or F_WRLCK is set on fd with fcntl(2).
*
* This is used to determine if the MediaProvider has given an fd to the lower fs to an app over
* the ContentResolver interface. Before that happens, we always call set_file_lock on the file
* allowing us to know if any reference to that fd is still open here.
*
* Returns true if fd may have a lock, false otherwise
*/
static bool is_file_locked(int fd, const std::string& path) {
struct flock fl{};
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
int res = fcntl(fd, F_OFD_GETLK, &fl);
if (res) {
PLOG(WARNING) << "Failed to check lock";
// Assume worst
return true;
}
bool locked = fl.l_type != F_UNLCK;
return locked;
}
static struct fuse* get_fuse(fuse_req_t req) {
return reinterpret_cast<struct fuse*>(fuse_req_userdata(req));
}
static bool is_package_owned_path(const string& path, const string& fuse_path) {
if (path.rfind(fuse_path, 0) != 0) {
return false;
}
return std::regex_match(path, PATTERN_OWNED_PATH);
}
static bool is_bpf_backing_path(const string& path) {
return std::regex_match(path, PATTERN_BPF_BACKING_PATH);
}
// See fuse_lowlevel.h fuse_lowlevel_notify_inval_entry for how to call this safetly without
// deadlocking the kernel
static void fuse_inval(fuse_session* se, fuse_ino_t parent_ino, fuse_ino_t child_ino,
const string& child_name, const string& path) {
if (mediaprovider::fuse::containsMount(path)) {
LOG(WARNING) << "Ignoring attempt to invalidate dentry for FUSE mounts";
return;
}
if (fuse_lowlevel_notify_inval_entry(se, parent_ino, child_name.c_str(), child_name.size())) {
// Invalidating the dentry can fail if there's no dcache entry, however, there may still
// be cached attributes, so attempt to invalidate those by invalidating the inode
fuse_lowlevel_notify_inval_inode(se, child_ino, 0, 0);
}
}
static double get_entry_timeout(const string& path, bool should_inval, struct fuse* fuse) {
string media_path = fuse->GetEffectiveRootPath() + "/Android/media";
if (fuse->disable_dentry_cache || should_inval || is_package_owned_path(path, fuse->path) ||
android::base::StartsWithIgnoreCase(path, media_path) || fuse->ShouldNotCache(path)) {
// We set dentry timeout to 0 for the following reasons:
// 1. The dentry cache was completely disabled for the entire volume.
// 2.1 Case-insensitive lookups need to invalidate other case-insensitive dentry matches
// 2.2 Nodes supporting transforms need to be invalidated, so that subsequent lookups by a
// uid requiring a transform is guaranteed to come to the FUSE daemon.
// 3. With app data isolation enabled, app A should not guess existence of app B from the
// Android/{data,obb}/<package> paths, hence we prevent the kernel from caching that
// information.
// 4. Installd might delete Android/media/<package> dirs when app data is cleared.
// This can leave a stale entry in the kernel dcache, and break subsequent creation of the
// dir via FUSE.
// 5. The dentry cache was completely disabled for the given path.
return 0;
}
return std::numeric_limits<double>::max();
}
static std::string get_path(node* node) {
const string& io_path = node->GetIoPath();
return io_path.empty() ? node->BuildPath() : io_path;
}
// Returns true if the path resides under .transforms/synthetic.
// NOTE: currently only file paths corresponding to redacted URIs reside under this folder. The path
// itself never exists and just a link for transformation.
static inline bool is_synthetic_path(const string& path, struct fuse* fuse) {
return android::base::StartsWithIgnoreCase(
path, fuse->GetTransformsDir() + "/" + TRANSFORM_SYNTHETIC_DIR);
}
static inline bool is_transforms_dir_path(const string& path, struct fuse* fuse) {
return android::base::StartsWithIgnoreCase(path, fuse->GetTransformsDir());
}
static std::unique_ptr<mediaprovider::fuse::FileLookupResult> validate_node_path(
const std::string& path, const std::string& name, fuse_req_t req, int* error_code,
struct fuse_entry_param* e, const FuseOp op) {
struct fuse* fuse = get_fuse(req);
const struct fuse_ctx* ctx = fuse_req_ctx(req);
memset(e, 0, sizeof(*e));
const bool synthetic_path = is_synthetic_path(path, fuse);
if (lstat(path.c_str(), &e->attr) < 0 && !(op == FuseOp::lookup && synthetic_path)) {
*error_code = errno;
return nullptr;
}
if (is_transforms_dir_path(path, fuse)) {
if (op == FuseOp::lookup) {
// Lookups are only allowed under .transforms/synthetic dir
if (!(android::base::EqualsIgnoreCase(path, fuse->GetTransformsDir()) ||
android::base::StartsWithIgnoreCase(
path, fuse->GetTransformsDir() + "/" + TRANSFORM_SYNTHETIC_DIR))) {
*error_code = ENONET;
return nullptr;
}
} else {
// user-code is only allowed to make lookups under .transforms dir, and that too only
// under .transforms/synthetic dir
*error_code = ENOENT;
return nullptr;
}
}
if (S_ISDIR(e->attr.st_mode)) {
// now that we have reached this point, ops on directories are safe and require no
// transformation.
return std::make_unique<mediaprovider::fuse::FileLookupResult>(0, 0, 0, true, false, "");
}
if (!synthetic_path && !fuse->IsTranscodeSupportedPath(path)) {
// Transforms are only supported for synthetic or transcode-supported paths
return std::make_unique<mediaprovider::fuse::FileLookupResult>(0, 0, 0, true, false, "");
}
// Handle potential file transforms
std::unique_ptr<mediaprovider::fuse::FileLookupResult> file_lookup_result =
fuse->mp->FileLookup(path, req->ctx.uid, req->ctx.pid);
if (!file_lookup_result) {
// Fail lookup if we can't fetch FileLookupResult for path
LOG(WARNING) << "Failed to fetch FileLookupResult for " << path;
*error_code = EFAULT;
return nullptr;
}
const string& io_path = file_lookup_result->io_path;
// Update size with io_path iff there's an io_path
if (!io_path.empty() && (lstat(io_path.c_str(), &e->attr) < 0)) {
*error_code = errno;
return nullptr;
}
return file_lookup_result;
}
static node* make_node_entry(fuse_req_t req, node* parent, const string& name, const string& path,
struct fuse_entry_param* e, int* error_code, const FuseOp op) {
struct fuse* fuse = get_fuse(req);
const struct fuse_ctx* ctx = fuse_req_ctx(req);
node* node;
memset(e, 0, sizeof(*e));
std::unique_ptr<mediaprovider::fuse::FileLookupResult> file_lookup_result =
validate_node_path(path, name, req, error_code, e, op);
if (!file_lookup_result) {
// Fail lookup if we can't validate |path, |errno| would have already been set
return nullptr;
}
bool should_invalidate = file_lookup_result->transforms_supported;
const bool transforms_complete = file_lookup_result->transforms_complete;
const int transforms = file_lookup_result->transforms;
const int transforms_reason = file_lookup_result->transforms_reason;
const string& io_path = file_lookup_result->io_path;
if (transforms) {
// If the node requires transforms, we MUST never cache it in the VFS
CHECK(should_invalidate);
}
node = parent->LookupChildByName(name, true /* acquire */, transforms);
if (!node) {
ino_t ino = e->attr.st_ino;
node = ::node::Create(parent, name, io_path, transforms_complete, transforms,
transforms_reason, &fuse->lock, ino, &fuse->tracker);
} else if (!mediaprovider::fuse::containsMount(path)) {
// Only invalidate a path if it does not contain mount and |name| != node->GetName.
// Invalidate both names to ensure there's no dentry left in the kernel after the following
// operations:
// 1) touch foo, touch FOO, unlink *foo*
// 2) touch foo, touch FOO, unlink *FOO*
// Invalidating lookup_name fixes (1) and invalidating node_name fixes (2)
// -Set |should_invalidate| to true to invalidate lookup_name by using 0 timeout below
// -Explicitly invalidate node_name. Note that we invalidate async otherwise we will
// deadlock the kernel
if (name != node->GetName()) {
// Force node invalidation to fix the kernel dentry cache for case (1) above
should_invalidate = true;
// Make copies of the node name and path so we're not attempting to acquire
// any node locks from the invalidation thread. Depending on timing, we may end
// up invalidating the wrong inode but that shouldn't result in correctness issues.
const fuse_ino_t parent_ino = fuse->ToInode(parent);
const fuse_ino_t child_ino = fuse->ToInode(node);
const std::string& node_name = node->GetName();
std::thread t([=]() { fuse_inval(fuse->se, parent_ino, child_ino, node_name, path); });
t.detach();
// Update the name after |node_name| reference above has been captured in lambda
// This avoids invalidating the node again on subsequent accesses with |name|
node->SetName(name);
}
// This updated value allows us correctly decide if to keep_cache and use direct_io during
// FUSE_OPEN. Between the last lookup and this lookup, we might have deleted a cached
// transcoded file on the lower fs. A subsequent transcode at FUSE_READ should ensure we
// don't reuse any stale transcode page cache content.
node->SetTransformsComplete(transforms_complete);
}
TRACE_NODE(node, req);
if (should_invalidate && fuse->IsTranscodeSupportedPath(path)) {
// Some components like the MTP stack need an efficient mechanism to determine if a file
// supports transcoding. This allows them workaround an issue with MTP clients on windows
// where those clients incorrectly use the original file size instead of the transcoded file
// size to copy files from the device. This size misuse causes transcoded files to be
// truncated to the original file size, hence corrupting the transcoded file.
//
// We expose the transcode bit via the st_nlink stat field. This should be safe because the
// field is not supported on FAT filesystems which FUSE is emulating.
// WARNING: Apps should never rely on this behavior as it is NOT supported API and will be
// removed in a future release when the MTP stack has better support for transcoded files on
// Windows OS.
e->attr.st_nlink = 2;
}
// This FS is not being exported via NFS so just a fixed generation number
// for now. If we do need this, we need to increment the generation ID each
// time the fuse daemon restarts because that's what it takes for us to
// reuse inode numbers.
e->generation = 0;
e->ino = fuse->ToInode(node);
// When FUSE BPF is used, the caching of node attributes and lookups is
// disabled to avoid possible inconsistencies between the FUSE cache and
// the lower file system state.
// With FUSE BPF the file system requests are forwarded to the lower file
// system bypassing the FUSE daemon, so dropping the caching does not
// introduce a performance regression.
// Currently FUSE BPF is limited to the Android/data and Android/obb
// directories.
if (!fuse->bpf || !is_bpf_backing_path(path)) {
e->entry_timeout = get_entry_timeout(path, should_invalidate, fuse);
e->attr_timeout = std::numeric_limits<double>::max();
}
return node;
}
namespace mediaprovider {
namespace fuse {
/**
* Function implementations
*
* These implement the various functions in fuse_lowlevel_ops
*
*/
static void pf_init(void* userdata, struct fuse_conn_info* conn) {
struct fuse* fuse = reinterpret_cast<struct fuse*>(userdata);
// We don't want a getattr request with every read request
conn->want &= ~FUSE_CAP_AUTO_INVAL_DATA & ~FUSE_CAP_READDIRPLUS_AUTO;
unsigned mask = (FUSE_CAP_SPLICE_WRITE | FUSE_CAP_SPLICE_MOVE | FUSE_CAP_SPLICE_READ |
FUSE_CAP_ASYNC_READ | FUSE_CAP_ATOMIC_O_TRUNC | FUSE_CAP_WRITEBACK_CACHE |
FUSE_CAP_EXPORT_SUPPORT | FUSE_CAP_FLOCK_LOCKS);
bool disable_splice_write = false;
if (fuse->passthrough) {
if (conn->capable & FUSE_CAP_PASSTHROUGH) {
mask |= FUSE_CAP_PASSTHROUGH;
// SPLICE_WRITE seems to cause linux kernel cache corruption with passthrough enabled.
// It is still under investigation but while running
// ScopedStorageDeviceTest#testAccessMediaLocationInvalidation, we notice test flakes
// of about 1/20 for the following reason:
// 1. App without ACCESS_MEDIA_LOCATION permission reads redacted bytes via FUSE cache
// 2. App with ACCESS_MEDIA_LOCATION permission reads non-redacted bytes via passthrough
// cache
// (2) fails because bytes from (1) sneak into the passthrough cache??
// To workaround, we disable splice for write when passthrough is enabled.
// This shouldn't have any performance regression if comparing passthrough devices to
// no-passthrough devices for the following reasons:
// 1. No-op for no-passthrough devices
// 2. Passthrough devices
// a. Files not requiring redaction use passthrough which bypasses FUSE_READ entirely
// b. Files requiring redaction are still faster than no-passthrough devices that use
// direct_io
disable_splice_write = true;
} else {
LOG(WARNING) << "Passthrough feature not supported by the kernel";
fuse->passthrough = false;
}
}
conn->want |= conn->capable & mask;
if (disable_splice_write) {
conn->want &= ~FUSE_CAP_SPLICE_WRITE;
}
conn->max_read = MAX_READ_SIZE;
fuse->active->store(true, std::memory_order_release);
}
static void pf_destroy(void* userdata) {
struct fuse* fuse = reinterpret_cast<struct fuse*>(userdata);
LOG(INFO) << "DESTROY " << fuse->path;
node::DeleteTree(fuse->root);
}
// Return true if the path is accessible for that uid.
static bool is_app_accessible_path(struct fuse* fuse, const string& path, uid_t uid) {
MediaProviderWrapper* mp = fuse->mp;
if (uid < AID_APP_START || uid == MY_UID) {
return true;
}
if (path == PRIMARY_VOLUME_PREFIX) {
// Apps should never refer to /storage/emulated - they should be using the user-spcific
// subdirs, eg /storage/emulated/0
return false;
}
std::smatch match;
if (std::regex_match(path, match, PATTERN_OWNED_PATH)) {
const std::string& pkg = match[1];
// .nomedia is not a valid package. .nomedia always exists in /Android/data directory,
// and it's not an external file/directory of any package
if (pkg == ".nomedia") {
return true;
}
if (!fuse->bpf && android::base::StartsWith(path, PRIMARY_VOLUME_PREFIX)) {
// Emulated storage bind-mounts app-private data directories, and so these
// should not be accessible through FUSE anyway.
LOG(WARNING) << "Rejected access to app-private dir on FUSE: " << path
<< " from uid: " << uid;
return false;
}
if (!mp->isUidAllowedAccessToDataOrObbPath(uid, path)) {
PLOG(WARNING) << "Invalid other package file access from " << uid << "(: " << path;
return false;
}
}
return true;
}
void fuse_bpf_fill_entries(const string& path, const int bpf_fd, struct fuse_entry_param* e,
int& backing_fd) {
/*
* The file descriptor `fd` must not be closed as it is closed
* automatically by the kernel as soon as it consumes the FUSE reply. This
* mechanism is necessary because userspace doesn't know when the kernel
* will consume the FUSE response containing `fd`, thus it may close the
* `fd` too soon, with the risk of assigning a backing file which is either
* invalid or corresponds to the wrong file in the lower file system.
*/
backing_fd = open(path.c_str(), O_CLOEXEC | O_DIRECTORY | O_RDONLY);
if (backing_fd < 0) {
PLOG(ERROR) << "Failed to open: " << path;
return;
}
e->backing_action = FUSE_ACTION_REPLACE;
e->backing_fd = backing_fd;
if (bpf_fd >= 0) {
e->bpf_action = FUSE_ACTION_REPLACE;
e->bpf_fd = bpf_fd;
} else if (bpf_fd == static_cast<int>(BpfFd::REMOVE)) {
e->bpf_action = FUSE_ACTION_REMOVE;
} else {
e->bpf_action = FUSE_ACTION_KEEP;
}
}
void fuse_bpf_install(struct fuse* fuse, struct fuse_entry_param* e, const string& child_path,
int& backing_fd) {
// TODO(b/211873756) Enable only for the primary volume. Must be
// extended for other media devices.
if (android::base::StartsWith(child_path, PRIMARY_VOLUME_PREFIX)) {
if (is_bpf_backing_path(child_path)) {
fuse_bpf_fill_entries(child_path, fuse->bpf_fd, e, backing_fd);
} else if (is_package_owned_path(child_path, fuse->path)) {
fuse_bpf_fill_entries(child_path, static_cast<int>(BpfFd::REMOVE), e, backing_fd);
}
}
}
static std::regex storage_emulated_regex("^\\/storage\\/emulated\\/([0-9]+)");
static node* do_lookup(fuse_req_t req, fuse_ino_t parent, const char* name,
struct fuse_entry_param* e, int* error_code, const FuseOp op,
int* backing_fd = NULL) {
struct fuse* fuse = get_fuse(req);
node* parent_node = fuse->FromInode(parent);
if (!parent_node) {
*error_code = ENOENT;
return nullptr;
}
string parent_path = parent_node->BuildPath();
// We should always allow lookups on the root, because failing them could cause
// bind mounts to be invalidated.
if (!fuse->IsRoot(parent_node) && !is_app_accessible_path(fuse, parent_path, req->ctx.uid)) {
*error_code = ENOENT;
return nullptr;
}
TRACE_NODE(parent_node, req);
const string child_path = parent_path + "/" + name;
std::smatch match;
std::regex_search(child_path, match, storage_emulated_regex);
// Ensure the FuseDaemon user id matches the user id or cross-user lookups are allowed in
// requested path
if (match.size() == 2 && MY_USER_ID_STRING != match[1].str()) {
// If user id mismatch, check cross-user lookups
long userId = strtol(match[1].str().c_str(), nullptr, 10);
if (userId < 0 || userId > MAX_USER_ID ||
!fuse->mp->ShouldAllowLookup(req->ctx.uid, userId)) {
*error_code = EACCES;
return nullptr;
}
}
auto node = make_node_entry(req, parent_node, name, child_path, e, error_code, op);
if (fuse->bpf && op == FuseOp::lookup) fuse_bpf_install(fuse, e, child_path, *backing_fd);
return node;
}
static void pf_lookup(fuse_req_t req, fuse_ino_t parent, const char* name) {
ATRACE_CALL();
struct fuse_entry_param e;
int backing_fd = -1;
int error_code = 0;
if (do_lookup(req, parent, name, &e, &error_code, FuseOp::lookup, &backing_fd)) {
fuse_reply_entry(req, &e);
} else {
CHECK(error_code != 0);
fuse_reply_err(req, error_code);
}
if (backing_fd != -1) close(backing_fd);
}
static void do_forget(fuse_req_t req, struct fuse* fuse, fuse_ino_t ino, uint64_t nlookup) {
node* node = fuse->FromInode(ino);
TRACE_NODE(node, req);
if (node) {
// This is a narrowing conversion from an unsigned 64bit to a 32bit value. For
// some reason we only keep 32 bit refcounts but the kernel issues
// forget requests with a 64 bit counter.
node->Release(static_cast<uint32_t>(nlookup));
}
}
static void pf_forget(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup) {
// Always allow to forget so no need to check is_app_accessible_path()
ATRACE_CALL();
node* node;
struct fuse* fuse = get_fuse(req);
do_forget(req, fuse, ino, nlookup);
fuse_reply_none(req);
}
static void pf_forget_multi(fuse_req_t req,
size_t count,
struct fuse_forget_data* forgets) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
for (int i = 0; i < count; i++) {
do_forget(req, fuse, forgets[i].ino, forgets[i].nlookup);
}
fuse_reply_none(req);
}
static void pf_fallocate(fuse_req_t req, fuse_ino_t ino, int mode, off_t offset, off_t length,
fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
handle* h = reinterpret_cast<handle*>(fi->fh);
auto err = fallocate(h->fd, mode, offset, length);
fuse_reply_err(req, err ? errno : 0);
}
static void pf_getattr(fuse_req_t req,
fuse_ino_t ino,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
if (!node) {
fuse_reply_err(req, ENOENT);
return;
}
const string& path = get_path(node);
if (!is_app_accessible_path(fuse, path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(node, req);
struct stat s;
memset(&s, 0, sizeof(s));
if (lstat(path.c_str(), &s) < 0) {
fuse_reply_err(req, errno);
} else {
fuse_reply_attr(req, &s, std::numeric_limits<double>::max());
}
}
static void pf_setattr(fuse_req_t req,
fuse_ino_t ino,
struct stat* attr,
int to_set,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
if (!node) {
fuse_reply_err(req, ENOENT);
return;
}
const string& path = get_path(node);
if (!is_app_accessible_path(fuse, path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
int fd = -1;
if (fi) {
// If we have a file_info, setattr was called with an fd so use the fd instead of path
handle* h = reinterpret_cast<handle*>(fi->fh);
fd = h->fd;
} else {
const struct fuse_ctx* ctx = fuse_req_ctx(req);
std::unique_ptr<FileOpenResult> result = fuse->mp->OnFileOpen(
path, path, ctx->uid, ctx->pid, node->GetTransformsReason(), true /* for_write */,
false /* redact */, false /* log_transforms_metrics */);
if (!result) {
fuse_reply_err(req, EFAULT);
return;
}
if (result->status) {
fuse_reply_err(req, EACCES);
return;
}
}
struct timespec times[2];
TRACE_NODE(node, req);
/* XXX: incomplete implementation on purpose.
* chmod/chown should NEVER be implemented.*/
if ((to_set & FUSE_SET_ATTR_SIZE)) {
int res = 0;
if (fd == -1) {
res = truncate64(path.c_str(), attr->st_size);
} else {
res = ftruncate64(fd, attr->st_size);
}
if (res < 0) {
fuse_reply_err(req, errno);
return;
}
}
/* Handle changing atime and mtime. If FATTR_ATIME_and FATTR_ATIME_NOW
* are both set, then set it to the current time. Else, set it to the
* time specified in the request. Same goes for mtime. Use utimensat(2)
* as it allows ATIME and MTIME to be changed independently, and has
* nanosecond resolution which fuse also has.
*/
if (to_set & (FATTR_ATIME | FATTR_MTIME)) {
times[0].tv_nsec = UTIME_OMIT;
times[1].tv_nsec = UTIME_OMIT;
if (to_set & FATTR_ATIME) {
if (to_set & FATTR_ATIME_NOW) {
times[0].tv_nsec = UTIME_NOW;
} else {
times[0] = attr->st_atim;
}
}
if (to_set & FATTR_MTIME) {
if (to_set & FATTR_MTIME_NOW) {
times[1].tv_nsec = UTIME_NOW;
} else {
times[1] = attr->st_mtim;
}
}
TRACE_NODE(node, req);
int res = 0;
if (fd == -1) {
res = utimensat(-1, path.c_str(), times, 0);
} else {
res = futimens(fd, times);
}
if (res < 0) {
fuse_reply_err(req, errno);
return;
}
}
lstat(path.c_str(), attr);
fuse_reply_attr(req, attr, std::numeric_limits<double>::max());
}
static void pf_canonical_path(fuse_req_t req, fuse_ino_t ino)
{
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
const string& path = node ? get_path(node) : "";
if (node && is_app_accessible_path(fuse, path, req->ctx.uid)) {
// TODO(b/147482155): Check that uid has access to |path| and its contents
fuse_reply_canonical_path(req, path.c_str());
return;
}
fuse_reply_err(req, ENOENT);
}
static void pf_mknod(fuse_req_t req,
fuse_ino_t parent,
const char* name,
mode_t mode,
dev_t rdev) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* parent_node = fuse->FromInode(parent);
if (!parent_node) {
fuse_reply_err(req, ENOENT);
return;
}
string parent_path = parent_node->BuildPath();
if (!is_app_accessible_path(fuse, parent_path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(parent_node, req);
const string child_path = parent_path + "/" + name;
mode = (mode & (~0777)) | 0664;
if (mknod(child_path.c_str(), mode, rdev) < 0) {
fuse_reply_err(req, errno);
return;
}
int error_code = 0;
struct fuse_entry_param e;
if (make_node_entry(req, parent_node, name, child_path, &e, &error_code, FuseOp::mknod)) {
fuse_reply_entry(req, &e);
} else {
CHECK(error_code != 0);
fuse_reply_err(req, error_code);
}
}
static void pf_mkdir(fuse_req_t req,
fuse_ino_t parent,
const char* name,
mode_t mode) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* parent_node = fuse->FromInode(parent);
if (!parent_node) {
fuse_reply_err(req, ENOENT);
return;
}
const struct fuse_ctx* ctx = fuse_req_ctx(req);
const string parent_path = parent_node->BuildPath();
if (!is_app_accessible_path(fuse, parent_path, ctx->uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(parent_node, req);
const string child_path = parent_path + "/" + name;
int status = fuse->mp->IsCreatingDirAllowed(child_path, ctx->uid);
if (status) {
fuse_reply_err(req, status);
return;
}
mode = (mode & (~0777)) | 0775;
if (mkdir(child_path.c_str(), mode) < 0) {
fuse_reply_err(req, errno);
return;
}
int error_code = 0;
struct fuse_entry_param e;
if (make_node_entry(req, parent_node, name, child_path, &e, &error_code, FuseOp::mkdir)) {
fuse_reply_entry(req, &e);
} else {
CHECK(error_code != 0);
fuse_reply_err(req, error_code);
}
}
static void pf_unlink(fuse_req_t req, fuse_ino_t parent, const char* name) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* parent_node = fuse->FromInode(parent);
if (!parent_node) {
fuse_reply_err(req, ENOENT);
return;
}
const struct fuse_ctx* ctx = fuse_req_ctx(req);
const string parent_path = parent_node->BuildPath();
if (!is_app_accessible_path(fuse, parent_path, ctx->uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(parent_node, req);
const string child_path = parent_path + "/" + name;
int status = fuse->mp->DeleteFile(child_path, ctx->uid);
if (status) {
fuse_reply_err(req, status);
return;
}
// TODO(b/169306422): Log each deleted node
parent_node->SetDeletedForChild(name);
fuse_reply_err(req, 0);
}
static void pf_rmdir(fuse_req_t req, fuse_ino_t parent, const char* name) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* parent_node = fuse->FromInode(parent);
if (!parent_node) {
fuse_reply_err(req, ENOENT);
return;
}
const string parent_path = parent_node->BuildPath();
if (!is_app_accessible_path(fuse, parent_path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
if (is_transforms_dir_path(parent_path, fuse)) {
// .transforms is a special daemon controlled dir so apps shouldn't be able to see it via
// readdir, and any dir operations attempted on it should fail
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(parent_node, req);
const string child_path = parent_path + "/" + name;
int status = fuse->mp->IsDeletingDirAllowed(child_path, req->ctx.uid);
if (status) {
fuse_reply_err(req, status);
return;
}
if (rmdir(child_path.c_str()) < 0) {
fuse_reply_err(req, errno);
return;
}
node* child_node = parent_node->LookupChildByName(name, false /* acquire */);
TRACE_NODE(child_node, req);
if (child_node) {
child_node->SetDeleted();
}
fuse_reply_err(req, 0);
}
/*
static void pf_symlink(fuse_req_t req, const char* link, fuse_ino_t parent,
const char* name)
{
cout << "TODO:" << __func__;
}
*/
static int do_rename(fuse_req_t req, fuse_ino_t parent, const char* name, fuse_ino_t new_parent,
const char* new_name, unsigned int flags) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
if (flags != 0) {
return EINVAL;
}
node* old_parent_node = fuse->FromInode(parent);
if (!old_parent_node) return ENOENT;
const struct fuse_ctx* ctx = fuse_req_ctx(req);
const string old_parent_path = old_parent_node->BuildPath();
if (!is_app_accessible_path(fuse, old_parent_path, ctx->uid)) {
return ENOENT;
}
if (is_transforms_dir_path(old_parent_path, fuse)) {
// .transforms is a special daemon controlled dir so apps shouldn't be able to see it via
// readdir, and any dir operations attempted on it should fail
return ENOENT;
}
node* new_parent_node;
if (fuse->bpf) {
new_parent_node = fuse->FromInodeNoThrow(new_parent);
if (!new_parent_node) return EXDEV;
} else {
new_parent_node = fuse->FromInode(new_parent);
if (!new_parent_node) return ENOENT;
}
const string new_parent_path = new_parent_node->BuildPath();
if (!is_app_accessible_path(fuse, new_parent_path, ctx->uid)) {
return ENOENT;
}
if (!old_parent_node || !new_parent_node) {
return ENOENT;
} else if (parent == new_parent && name == new_name) {
// No rename required.
return 0;
}
TRACE_NODE(old_parent_node, req);
TRACE_NODE(new_parent_node, req);
const string old_child_path = old_parent_path + "/" + name;
const string new_child_path = new_parent_path + "/" + new_name;
if (android::base::EqualsIgnoreCase(fuse->GetEffectiveRootPath() + "/android", old_child_path)) {
// Prevent renaming Android/ dir since it contains bind-mounts on the primary volume
return EACCES;
}
// TODO(b/147408834): Check ENOTEMPTY & EEXIST error conditions before JNI call.
const int res = fuse->mp->Rename(old_child_path, new_child_path, req->ctx.uid);
// TODO(b/145663158): Lookups can go out of sync if file/directory is actually moved but
// EFAULT/EIO is reported due to JNI exception.
if (res == 0) {
// Mark any existing destination nodes as deleted. This fixes the following edge case:
// 1. New destination node is forgotten
// 2. Old destination node is not forgotten because there's still an open fd ref to it
// 3. Lookup for |new_name| returns old destination node with stale metadata
new_parent_node->SetDeletedForChild(new_name);
// TODO(b/169306422): Log each renamed node
old_parent_node->RenameChild(name, new_name, new_parent_node);
}
return res;
}
static void pf_rename(fuse_req_t req, fuse_ino_t parent, const char* name, fuse_ino_t new_parent,
const char* new_name, unsigned int flags) {
int res = do_rename(req, parent, name, new_parent, new_name, flags);
fuse_reply_err(req, res);
}
/*
static void pf_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t new_parent,
const char* new_name)
{
cout << "TODO:" << __func__;
}
*/
static handle* create_handle_for_node(struct fuse* fuse, const string& path, int fd, uid_t uid,
uid_t transforms_uid, node* node, const RedactionInfo* ri,
const bool allow_passthrough, const bool open_info_direct_io,
int* keep_cache) {
std::lock_guard<std::recursive_mutex> guard(fuse->lock);
bool redaction_needed = ri->isRedactionNeeded();
handle* handle = nullptr;
int transforms = node->GetTransforms();
bool transforms_complete = node->IsTransformsComplete();
if (transforms_uid > 0) {
CHECK(transforms);
}
if (fuse->passthrough && allow_passthrough) {
*keep_cache = transforms_complete;
// We only enabled passthrough iff these 2 conditions hold
// 1. Redaction is not needed
// 2. Node transforms are completed, e.g transcoding.
// (2) is important because we transcode lazily (on the first read) and with passthrough,
// we will never get a read into the FUSE daemon, so passthrough would have returned
// arbitrary bytes the first time around. However, if we ensure that transforms are
// completed, then it's safe to use passthrough. Additionally, transcoded nodes never
// require redaction so (2) implies (1)
handle = new struct handle(fd, ri, !open_info_direct_io /* cached */,
!redaction_needed && transforms_complete /* passthrough */, uid,
transforms_uid);
} else {
// Without fuse->passthrough, we don't want to use the FUSE VFS cache in two cases:
// 1. When redaction is needed because app A with EXIF access might access
// a region that should have been redacted for app B without EXIF access, but app B on
// a subsequent read, will be able to see the EXIF data because the read request for
// that region will be served from cache and not get to the FUSE daemon
// 2. When the file has a read or write lock on it. This means that the MediaProvider
// has given an fd to the lower file system to an app. There are two cases where using
// the cache in this case can be a problem:
// a. Writing to a FUSE fd with caching enabled will use the write-back cache and a
// subsequent read from the lower fs fd will not see the write.
// b. Reading from a FUSE fd with caching enabled may not see the latest writes using
// the lower fs fd because those writes did not go through the FUSE layer and reads from
// FUSE after that write may be served from cache
bool has_redacted = node->HasRedactedCache();
bool is_redaction_change =
(redaction_needed && !has_redacted) || (!redaction_needed && has_redacted);
bool is_cached_file_open = node->HasCachedHandle();
bool direct_io = open_info_direct_io || (is_cached_file_open && is_redaction_change) ||
is_file_locked(fd, path) || fuse->ShouldNotCache(path);
if (!is_cached_file_open && is_redaction_change) {
node->SetRedactedCache(redaction_needed);
// Purges stale page cache before open
*keep_cache = 0;
} else {
*keep_cache = transforms_complete;
}
handle = new struct handle(fd, ri, !direct_io /* cached */, false /* passthrough */, uid,
transforms_uid);
}
node->AddHandle(handle);
return handle;
}
static bool do_passthrough_enable(fuse_req_t req, struct fuse_file_info* fi, unsigned int fd) {
int passthrough_fh = fuse_passthrough_enable(req, fd);
if (passthrough_fh <= 0) {
return false;
}
fi->passthrough_fh = passthrough_fh;
return true;
}
static OpenInfo parse_open_flags(const string& path, const int in_flags) {
const bool for_write = in_flags & (O_WRONLY | O_RDWR);
int out_flags = in_flags;
bool direct_io = false;
if (in_flags & O_DIRECT) {
// Set direct IO on the FUSE fs file
direct_io = true;
if (android::base::StartsWith(path, PRIMARY_VOLUME_PREFIX)) {
// Remove O_DIRECT because there are strict alignment requirements for direct IO and
// there were some historical bugs affecting encrypted block devices.
// Hence, this is only supported on public volumes.
out_flags &= ~O_DIRECT;
}
}
if (in_flags & O_WRONLY) {
// Replace O_WRONLY with O_RDWR because even if the FUSE fd is opened write-only, the FUSE
// driver might issue reads on the lower fs ith the writeback cache enabled
out_flags &= ~O_WRONLY;
out_flags |= O_RDWR;
}
if (in_flags & O_APPEND) {
// Remove O_APPEND because passing it to the lower fs can lead to file corruption when
// multiple FUSE threads race themselves reading. With writeback cache enabled, the FUSE
// driver already handles the O_APPEND
out_flags &= ~O_APPEND;
}
return {.flags = out_flags, .for_write = for_write, .direct_io = direct_io};
}
static void fill_fuse_file_info(const handle* handle, const OpenInfo* open_info,
const int keep_cache, struct fuse_file_info* fi) {
fi->fh = ptr_to_id(handle);
fi->keep_cache = keep_cache;
fi->direct_io = !handle->cached;
}
static void pf_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
if (!node) {
fuse_reply_err(req, ENOENT);
return;
}
const struct fuse_ctx* ctx = fuse_req_ctx(req);
const string& io_path = get_path(node);
const string& build_path = node->BuildPath();
if (!is_app_accessible_path(fuse, io_path, ctx->uid)) {
fuse_reply_err(req, ENOENT);
return;
}
const OpenInfo open_info = parse_open_flags(io_path, fi->flags);
if (open_info.for_write && node->GetTransforms()) {
TRACE_NODE(node, req) << "write with transforms";
} else {
TRACE_NODE(node, req) << (open_info.for_write ? "write" : "read");
}
// Force permission check with the build path because the MediaProvider database might not be
// aware of the io_path
// We don't redact if the caller was granted write permission for this file
std::unique_ptr<FileOpenResult> result = fuse->mp->OnFileOpen(
build_path, io_path, ctx->uid, ctx->pid, node->GetTransformsReason(),
open_info.for_write, !open_info.for_write /* redact */,
true /* log_transforms_metrics */);
if (!result) {
fuse_reply_err(req, EFAULT);
return;
}
if (result->status) {
fuse_reply_err(req, result->status);
return;
}
int fd = -1;
const bool is_fd_from_java = result->fd >= 0;
if (is_fd_from_java) {
fd = result->fd;
TRACE_NODE(node, req) << "opened in Java";
} else {
fd = open(io_path.c_str(), open_info.flags);
if (fd < 0) {
fuse_reply_err(req, errno);
return;
}
}
int keep_cache = 1;
// If is_fd_from_java==true, we disallow passthrough because the fd can be pointing to the
// FUSE fs if gotten from another process
const handle* h = create_handle_for_node(fuse, io_path, fd, result->uid, result->transforms_uid,
node, result->redaction_info.release(),
/* allow_passthrough */ !is_fd_from_java,
open_info.direct_io, &keep_cache);
fill_fuse_file_info(h, &open_info, keep_cache, fi);
// TODO(b/173190192) ensuring that h->cached must be enabled in order to
// user FUSE passthrough is a conservative rule and might be dropped as
// soon as demonstrated its correctness.
if (h->passthrough && !do_passthrough_enable(req, fi, fd)) {
// TODO: Should we crash here so we can find errors easily?
PLOG(ERROR) << "Passthrough OPEN failed for " << io_path;
fuse_reply_err(req, EFAULT);
return;
}
fuse_reply_open(req, fi);
}
static void do_read(fuse_req_t req, size_t size, off_t off, struct fuse_file_info* fi,
bool direct_io) {
handle* h = reinterpret_cast<handle*>(fi->fh);
struct fuse_bufvec buf = FUSE_BUFVEC_INIT(size);
buf.buf[0].fd = h->fd;
buf.buf[0].pos = off;
buf.buf[0].flags =
(enum fuse_buf_flags) (FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK);
if (direct_io) {
// sdcardfs does not register splice_read_file_operations and some requests fail with EFAULT
// Specifically, FUSE splice is only enabled for 8KB+ buffers, hence such reads fail
fuse_reply_data(req, &buf, (enum fuse_buf_copy_flags)FUSE_BUF_NO_SPLICE);
} else {
fuse_reply_data(req, &buf, (enum fuse_buf_copy_flags)0);
}
}
/**
* Sets the parameters for a fuse_buf that reads from memory, including flags.
* Makes buf->mem point to an already mapped region of zeroized memory.
* This memory is read only.
*/
static void create_mem_fuse_buf(size_t size, fuse_buf* buf, struct fuse* fuse) {
buf->size = size;
buf->mem = fuse->zero_addr;
buf->flags = static_cast<fuse_buf_flags>(0 /*read from fuse_buf.mem*/);
buf->pos = -1;
buf->fd = -1;
}
/**
* Sets the parameters for a fuse_buf that reads from file, including flags.
*/
static void create_file_fuse_buf(size_t size, off_t pos, int fd, fuse_buf* buf) {
buf->size = size;
buf->fd = fd;
buf->pos = pos;
buf->flags = static_cast<fuse_buf_flags>(FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK);
buf->mem = nullptr;
}
static void do_read_with_redaction(fuse_req_t req, size_t size, off_t off, fuse_file_info* fi,
bool direct_io) {
handle* h = reinterpret_cast<handle*>(fi->fh);
std::vector<ReadRange> ranges;
h->ri->getReadRanges(off, size, &ranges);
// As an optimization, return early if there are no ranges to redact.
if (ranges.size() == 0) {
do_read(req, size, off, fi, direct_io);
return;
}
const size_t num_bufs = ranges.size();
auto bufvec_ptr = std::unique_ptr<fuse_bufvec, decltype(free)*>{
reinterpret_cast<fuse_bufvec*>(
malloc(sizeof(fuse_bufvec) + (num_bufs - 1) * sizeof(fuse_buf))),
free};
fuse_bufvec& bufvec = *bufvec_ptr;
// initialize bufvec
bufvec.count = num_bufs;
bufvec.idx = 0;
bufvec.off = 0;
for (int i = 0; i < num_bufs; ++i) {
const ReadRange& range = ranges[i];
if (range.is_redaction) {
create_mem_fuse_buf(range.size, &(bufvec.buf[i]), get_fuse(req));
} else {
create_file_fuse_buf(range.size, range.start, h->fd, &(bufvec.buf[i]));
}
}
fuse_reply_data(req, &bufvec, static_cast<fuse_buf_copy_flags>(0));
}
static void pf_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
struct fuse_file_info* fi) {
ATRACE_CALL();
handle* h = reinterpret_cast<handle*>(fi->fh);
const bool direct_io = !h->cached;
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
if (!node->IsTransformsComplete()) {
if (!fuse->mp->Transform(node->BuildPath(), node->GetIoPath(), node->GetTransforms(),
node->GetTransformsReason(), req->ctx.uid, h->uid,
h->transforms_uid)) {
fuse_reply_err(req, EFAULT);
return;
}
node->SetTransformsComplete(true);
}
fuse->fadviser.Record(h->fd, size);
if (h->ri->isRedactionNeeded()) {
do_read_with_redaction(req, size, off, fi, direct_io);
} else {
do_read(req, size, off, fi, direct_io);
}
}
/*
static void pf_write(fuse_req_t req, fuse_ino_t ino, const char* buf,
size_t size, off_t off, struct fuse_file_info* fi)
{
cout << "TODO:" << __func__;
}
*/
static void pf_write_buf(fuse_req_t req,
fuse_ino_t ino,
struct fuse_bufvec* bufv,
off_t off,
struct fuse_file_info* fi) {
ATRACE_CALL();
handle* h = reinterpret_cast<handle*>(fi->fh);
struct fuse_bufvec buf = FUSE_BUFVEC_INIT(fuse_buf_size(bufv));
ssize_t size;
struct fuse* fuse = get_fuse(req);
buf.buf[0].fd = h->fd;
buf.buf[0].pos = off;
buf.buf[0].flags =
(enum fuse_buf_flags) (FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK);
size = fuse_buf_copy(&buf, bufv, (enum fuse_buf_copy_flags) 0);
if (size < 0)
fuse_reply_err(req, -size);
else {
// Execute Record *before* fuse_reply_write to avoid the following ordering:
// fuse_reply_write -> pf_release (destroy handle) -> Record (use handle after free)
fuse->fadviser.Record(h->fd, size);
fuse_reply_write(req, size);
}
}
// Haven't tested this one. Not sure what calls it.
#if 0
static void pf_copy_file_range(fuse_req_t req, fuse_ino_t ino_in,
off_t off_in, struct fuse_file_info* fi_in,
fuse_ino_t ino_out, off_t off_out,
struct fuse_file_info* fi_out, size_t len,
int flags)
{
handle* h_in = reinterpret_cast<handle *>(fi_in->fh);
handle* h_out = reinterpret_cast<handle *>(fi_out->fh);
struct fuse_bufvec buf_in = FUSE_BUFVEC_INIT(len);
struct fuse_bufvec buf_out = FUSE_BUFVEC_INIT(len);
ssize_t size;
buf_in.buf[0].fd = h_in->fd;
buf_in.buf[0].pos = off_in;
buf_in.buf[0].flags = (enum fuse_buf_flags)(FUSE_BUF_IS_FD|FUSE_BUF_FD_SEEK);
buf_out.buf[0].fd = h_out->fd;
buf_out.buf[0].pos = off_out;
buf_out.buf[0].flags = (enum fuse_buf_flags)(FUSE_BUF_IS_FD|FUSE_BUF_FD_SEEK);
size = fuse_buf_copy(&buf_out, &buf_in, (enum fuse_buf_copy_flags) 0);
if (size < 0) {
fuse_reply_err(req, -size);
}
fuse_reply_write(req, size);
}
#endif
/*
* This function does nothing except being a placeholder to keep the FUSE
* driver handling flushes on close(2).
* In fact, kernels prior to 5.8 stop attempting flushing the cache on close(2)
* if the .flush operation is not implemented by the FUSE daemon.
* This has been fixed in the kernel by commit 614c026e8a46 ("fuse: always
* flush dirty data on close(2)"), merged in Linux 5.8, but until then
* userspace must mitigate this behavior by not leaving the .flush function
* pointer empty.
*/
static void pf_flush(fuse_req_t req,
fuse_ino_t ino,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
TRACE_NODE(nullptr, req) << "noop";
fuse_reply_err(req, 0);
}
static void pf_release(fuse_req_t req,
fuse_ino_t ino,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
handle* h = reinterpret_cast<handle*>(fi->fh);
TRACE_NODE(node, req);
fuse->fadviser.Close(h->fd);
if (node) {
node->DestroyHandle(h);
}
fuse_reply_err(req, 0);
}
static int do_sync_common(int fd, bool datasync) {
int res = datasync ? fdatasync(fd) : fsync(fd);
if (res == -1) return errno;
return 0;
}
static void pf_fsync(fuse_req_t req,
fuse_ino_t ino,
int datasync,
struct fuse_file_info* fi) {
ATRACE_CALL();
handle* h = reinterpret_cast<handle*>(fi->fh);
int err = do_sync_common(h->fd, datasync);
fuse_reply_err(req, err);
}
static void pf_fsyncdir(fuse_req_t req,
fuse_ino_t ino,
int datasync,
struct fuse_file_info* fi) {
dirhandle* h = reinterpret_cast<dirhandle*>(fi->fh);
int err = do_sync_common(dirfd(h->d), datasync);
fuse_reply_err(req, err);
}
static void pf_opendir(fuse_req_t req,
fuse_ino_t ino,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
if (!node) {
fuse_reply_err(req, ENOENT);
return;
}
const struct fuse_ctx* ctx = fuse_req_ctx(req);
const string path = node->BuildPath();
if (!is_app_accessible_path(fuse, path, ctx->uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(node, req);
int status = fuse->mp->IsOpendirAllowed(path, ctx->uid, /* forWrite */ false);
if (status) {
fuse_reply_err(req, status);
return;
}
DIR* dir = opendir(path.c_str());
if (!dir) {
fuse_reply_err(req, errno);
return;
}
dirhandle* h = new dirhandle(dir);
node->AddDirHandle(h);
fi->fh = ptr_to_id(h);
fuse_reply_open(req, fi);
}
#define READDIR_BUF 8192LU
static void do_readdir_common(fuse_req_t req,
fuse_ino_t ino,
size_t size,
off_t off,
struct fuse_file_info* fi,
bool plus) {
struct fuse* fuse = get_fuse(req);
dirhandle* h = reinterpret_cast<dirhandle*>(fi->fh);
size_t len = std::min<size_t>(size, READDIR_BUF);
char buf[READDIR_BUF];
size_t used = 0;
std::shared_ptr<DirectoryEntry> de;
struct fuse_entry_param e;
size_t entry_size = 0;
node* node = fuse->FromInode(ino);
if (!node) {
fuse_reply_err(req, ENOENT);
return;
}
const string path = node->BuildPath();
if (!is_app_accessible_path(fuse, path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(node, req);
// Get all directory entries from MediaProvider on first readdir() call of
// directory handle. h->next_off = 0 indicates that current readdir() call
// is first readdir() call for the directory handle, Avoid multiple JNI calls
// for single directory handle.
if (h->next_off == 0) {
h->de = fuse->mp->GetDirectoryEntries(req->ctx.uid, path, h->d);
}
// If the last entry in the previous readdir() call was rejected due to
// buffer capacity constraints, update directory offset to start from
// previously rejected entry. Directory offset can also change if there was
// a seekdir() on the given directory handle.
if (off != h->next_off) {
h->next_off = off;
}
const int num_directory_entries = h->de.size();
// Check for errors. Any error/exception occurred while obtaining directory
// entries will be indicated by marking first directory entry name as empty
// string. In the erroneous case corresponding d_type will hold error number.
if (num_directory_entries && h->de[0]->d_name.empty()) {
fuse_reply_err(req, h->de[0]->d_type);
return;
}
while (h->next_off < num_directory_entries) {
de = h->de[h->next_off];
entry_size = 0;
h->next_off++;
if (plus) {
int error_code = 0;
if (do_lookup(req, ino, de->d_name.c_str(), &e, &error_code, FuseOp::readdir)) {
entry_size = fuse_add_direntry_plus(req, buf + used, len - used, de->d_name.c_str(),
&e, h->next_off);
} else {
// Ignore lookup errors on
// 1. non-existing files returned from MediaProvider database.
// 2. path that doesn't match FuseDaemon UID and calling uid.
if (error_code == ENOENT || error_code == EPERM || error_code == EACCES
|| error_code == EIO) continue;
fuse_reply_err(req, error_code);
return;
}
} else {
// This should never happen because we have readdir_plus enabled without adaptive
// readdir_plus, FUSE_CAP_READDIRPLUS_AUTO
LOG(WARNING) << "Handling plain readdir for " << de->d_name << ". Invalid d_ino";
e.attr.st_ino = FUSE_UNKNOWN_INO;
e.attr.st_mode = de->d_type << 12;
entry_size = fuse_add_direntry(req, buf + used, len - used, de->d_name.c_str(), &e.attr,
h->next_off);
}
// If buffer in fuse_add_direntry[_plus] is not large enough then
// the entry is not added to buffer but the size of the entry is still
// returned. Check available buffer size + returned entry size is less
// than actual buffer size to confirm entry is added to buffer.
if (used + entry_size > len) {
// When an entry is rejected, lookup called by readdir_plus will not be tracked by
// kernel. Call forget on the rejected node to decrement the reference count.
if (plus) {
do_forget(req, fuse, e.ino, 1);
}
break;
}
used += entry_size;
}
fuse_reply_buf(req, buf, used);
}
static void pf_readdir(fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
struct fuse_file_info* fi) {
ATRACE_CALL();
do_readdir_common(req, ino, size, off, fi, false);
}
static void pf_readdirplus(fuse_req_t req,
fuse_ino_t ino,
size_t size,
off_t off,
struct fuse_file_info* fi) {
ATRACE_CALL();
do_readdir_common(req, ino, size, off, fi, true);
}
static void pf_releasedir(fuse_req_t req,
fuse_ino_t ino,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
dirhandle* h = reinterpret_cast<dirhandle*>(fi->fh);
TRACE_NODE(node, req);
if (node) {
node->DestroyDirHandle(h);
}
fuse_reply_err(req, 0);
}
static void pf_statfs(fuse_req_t req, fuse_ino_t ino) {
ATRACE_CALL();
struct statvfs st;
struct fuse* fuse = get_fuse(req);
if (statvfs(fuse->root->GetName().c_str(), &st))
fuse_reply_err(req, errno);
else
fuse_reply_statfs(req, &st);
}
/*
static void pf_setxattr(fuse_req_t req, fuse_ino_t ino, const char* name,
const char* value, size_t size, int flags)
{
cout << "TODO:" << __func__;
}
static void pf_getxattr(fuse_req_t req, fuse_ino_t ino, const char* name,
size_t size)
{
cout << "TODO:" << __func__;
}
static void pf_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
{
cout << "TODO:" << __func__;
}
static void pf_removexattr(fuse_req_t req, fuse_ino_t ino, const char* name)
{
cout << "TODO:" << __func__;
}*/
static void pf_access(fuse_req_t req, fuse_ino_t ino, int mask) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* node = fuse->FromInode(ino);
if (!node) {
fuse_reply_err(req, ENOENT);
return;
}
const string path = node->BuildPath();
if (path != PRIMARY_VOLUME_PREFIX && !is_app_accessible_path(fuse, path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(node, req);
// exists() checks are always allowed.
if (mask == F_OK) {
int res = access(path.c_str(), F_OK);
fuse_reply_err(req, res ? errno : 0);
return;
}
struct stat stat;
if (lstat(path.c_str(), &stat)) {
// File doesn't exist
fuse_reply_err(req, ENOENT);
return;
}
// For read and write permission checks we go to MediaProvider.
int status = 0;
bool for_write = mask & W_OK;
bool is_directory = S_ISDIR(stat.st_mode);
if (is_directory) {
if (path == PRIMARY_VOLUME_PREFIX && mask == X_OK) {
// Special case for this path: apps should be allowed to enter it,
// but not list directory contents (which would be user numbers).
int res = access(path.c_str(), X_OK);
fuse_reply_err(req, res ? errno : 0);
return;
}
status = fuse->mp->IsOpendirAllowed(path, req->ctx.uid, for_write);
} else {
if (mask & X_OK) {
// Fuse is mounted with MS_NOEXEC.
fuse_reply_err(req, EACCES);
return;
}
std::unique_ptr<FileOpenResult> result = fuse->mp->OnFileOpen(
path, path, req->ctx.uid, req->ctx.pid, node->GetTransformsReason(), for_write,
false /* redact */, false /* log_transforms_metrics */);
if (!result) {
status = EFAULT;
} else if (result->status) {
status = EACCES;
}
}
fuse_reply_err(req, status);
}
static void pf_create(fuse_req_t req,
fuse_ino_t parent,
const char* name,
mode_t mode,
struct fuse_file_info* fi) {
ATRACE_CALL();
struct fuse* fuse = get_fuse(req);
node* parent_node = fuse->FromInode(parent);
if (!parent_node) {
fuse_reply_err(req, ENOENT);
return;
}
const string parent_path = parent_node->BuildPath();
if (!is_app_accessible_path(fuse, parent_path, req->ctx.uid)) {
fuse_reply_err(req, ENOENT);
return;
}
TRACE_NODE(parent_node, req);
const string child_path = parent_path + "/" + name;
const OpenInfo open_info = parse_open_flags(child_path, fi->flags);
int mp_return_code = fuse->mp->InsertFile(child_path.c_str(), req->ctx.uid);
if (mp_return_code) {
fuse_reply_err(req, mp_return_code);
return;
}
mode = (mode & (~0777)) | 0664;
int fd = open(child_path.c_str(), open_info.flags, mode);
if (fd < 0) {
int error_code = errno;
// We've already inserted the file into the MP database before the
// failed open(), so that needs to be rolled back here.
fuse->mp->DeleteFile(child_path.c_str(), req->ctx.uid);
fuse_reply_err(req, error_code);
return;
}
int error_code = 0;
struct fuse_entry_param e;
node* node =
make_node_entry(req, parent_node, name, child_path, &e, &error_code, FuseOp::create);
TRACE_NODE(node, req);
if (!node) {
CHECK(error_code != 0);
fuse_reply_err(req, error_code);
return;
}
// Let MediaProvider know we've created a new file
fuse->mp->OnFileCreated(child_path);
// TODO(b/147274248): Assume there will be no EXIF to redact.
// This prevents crashing during reads but can be a security hole if a malicious app opens an fd
// to the file before all the EXIF content is written. We could special case reads before the
// first close after a file has just been created.
int keep_cache = 1;
const handle* h = create_handle_for_node(
fuse, child_path, fd, req->ctx.uid, 0 /* transforms_uid */, node, new RedactionInfo(),
/* allow_passthrough */ true, open_info.direct_io, &keep_cache);
fill_fuse_file_info(h, &open_info, keep_cache, fi);
// TODO(b/173190192) ensuring that h->cached must be enabled in order to
// user FUSE passthrough is a conservative rule and might be dropped as
// soon as demonstrated its correctness.
if (h->passthrough && !do_passthrough_enable(req, fi, fd)) {
PLOG(ERROR) << "Passthrough CREATE failed for " << child_path;
fuse_reply_err(req, EFAULT);
return;
}
fuse_reply_create(req, &e, fi);
}
/*
static void pf_getlk(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info* fi, struct flock* lock)
{
cout << "TODO:" << __func__;
}
static void pf_setlk(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info* fi,
struct flock* lock, int sleep)
{
cout << "TODO:" << __func__;
}
static void pf_bmap(fuse_req_t req, fuse_ino_t ino, size_t blocksize,
uint64_t idx)
{
cout << "TODO:" << __func__;
}
static void pf_ioctl(fuse_req_t req, fuse_ino_t ino, unsigned int cmd,
void* arg, struct fuse_file_info* fi, unsigned flags,
const void* in_buf, size_t in_bufsz, size_t out_bufsz)
{
cout << "TODO:" << __func__;
}
static void pf_poll(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info* fi,
struct fuse_pollhandle* ph)
{
cout << "TODO:" << __func__;
}
static void pf_retrieve_reply(fuse_req_t req, void* cookie, fuse_ino_t ino,
off_t offset, struct fuse_bufvec* bufv)
{
cout << "TODO:" << __func__;
}
static void pf_flock(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info* fi, int op)
{
cout << "TODO:" << __func__;
}
static void pf_fallocate(fuse_req_t req, fuse_ino_t ino, int mode,
off_t offset, off_t length, struct fuse_file_info* fi)
{
cout << "TODO:" << __func__;
}
*/
static struct fuse_lowlevel_ops ops{
.init = pf_init, .destroy = pf_destroy, .lookup = pf_lookup, .forget = pf_forget,
.getattr = pf_getattr, .setattr = pf_setattr, .canonical_path = pf_canonical_path,
.mknod = pf_mknod, .mkdir = pf_mkdir, .unlink = pf_unlink, .rmdir = pf_rmdir,
/*.symlink = pf_symlink,*/
.rename = pf_rename,
/*.link = pf_link,*/
.open = pf_open, .read = pf_read,
/*.write = pf_write,*/
.flush = pf_flush,
.release = pf_release, .fsync = pf_fsync, .opendir = pf_opendir, .readdir = pf_readdir,
.releasedir = pf_releasedir, .fsyncdir = pf_fsyncdir, .statfs = pf_statfs,
/*.setxattr = pf_setxattr,
.getxattr = pf_getxattr,
.listxattr = pf_listxattr,
.removexattr = pf_removexattr,*/
.access = pf_access, .create = pf_create,
/*.getlk = pf_getlk,
.setlk = pf_setlk,
.bmap = pf_bmap,
.ioctl = pf_ioctl,
.poll = pf_poll,*/
.write_buf = pf_write_buf,
/*.retrieve_reply = pf_retrieve_reply,*/
.forget_multi = pf_forget_multi,
/*.flock = pf_flock,*/
.fallocate = pf_fallocate,
.readdirplus = pf_readdirplus,
/*.copy_file_range = pf_copy_file_range,*/
};
static struct fuse_loop_config config = {
.clone_fd = 1,
.max_idle_threads = 10,
};
static std::unordered_map<enum fuse_log_level, enum android_LogPriority> fuse_to_android_loglevel({
{FUSE_LOG_EMERG, ANDROID_LOG_FATAL},
{FUSE_LOG_ALERT, ANDROID_LOG_ERROR},
{FUSE_LOG_CRIT, ANDROID_LOG_ERROR},
{FUSE_LOG_ERR, ANDROID_LOG_ERROR},
{FUSE_LOG_WARNING, ANDROID_LOG_WARN},
{FUSE_LOG_NOTICE, ANDROID_LOG_INFO},
{FUSE_LOG_INFO, ANDROID_LOG_DEBUG},
{FUSE_LOG_DEBUG, ANDROID_LOG_VERBOSE},
});
static void fuse_logger(enum fuse_log_level level, const char* fmt, va_list ap) {
__android_log_vprint(fuse_to_android_loglevel.at(level), LIBFUSE_LOG_TAG, fmt, ap);
}
bool FuseDaemon::ShouldOpenWithFuse(int fd, bool for_read, const std::string& path) {
if (fuse->passthrough) {
// Always open with FUSE if passthrough is enabled. This avoids the delicate file lock
// acquisition below to ensure VFS cache consistency and doesn't impact filesystem
// performance since read(2)/write(2) happen in the kernel
return true;
}
bool use_fuse = false;
if (active.load(std::memory_order_acquire)) {
std::lock_guard<std::recursive_mutex> guard(fuse->lock);
const node* node = node::LookupAbsolutePath(fuse->root, path);
if (node && node->HasCachedHandle()) {
use_fuse = true;
} else {
// If we are unable to set a lock, we should use fuse since we can't track
// when all fd references (including dups) are closed. This can happen when
// we try to set a write lock twice on the same file
use_fuse = set_file_lock(fd, for_read, path);
}
} else {
LOG(WARNING) << "FUSE daemon is inactive. Cannot open file with FUSE";
}
return use_fuse;
}
bool FuseDaemon::UsesFusePassthrough() const {
return fuse->passthrough;
}
void FuseDaemon::InvalidateFuseDentryCache(const std::string& path) {
LOG(VERBOSE) << "Invalidating FUSE dentry cache";
if (active.load(std::memory_order_acquire)) {
string name;
fuse_ino_t parent;
fuse_ino_t child;
{
std::lock_guard<std::recursive_mutex> guard(fuse->lock);
const node* node = node::LookupAbsolutePath(fuse->root, path);
if (node) {
name = node->GetName();
child = fuse->ToInode(const_cast<class node*>(node));
parent = fuse->ToInode(node->GetParent());
}
}
if (!name.empty()) {
fuse_inval(fuse->se, parent, child, name, path);
}
} else {
LOG(WARNING) << "FUSE daemon is inactive. Cannot invalidate dentry";
}
}
FuseDaemon::FuseDaemon(JNIEnv* env, jobject mediaProvider) : mp(env, mediaProvider),
active(false), fuse(nullptr) {}
bool FuseDaemon::IsStarted() const {
return active.load(std::memory_order_acquire);
}
bool IsFuseBpfEnabled() {
std::string bpf_override = android::base::GetProperty("persist.sys.fuse.bpf.override", "");
if (bpf_override == "true") {
return true;
} else if (bpf_override == "false") {
return false;
}
return android::base::GetBoolProperty("ro.fuse.bpf.enabled", false);
}
void FuseDaemon::Start(android::base::unique_fd fd, const std::string& path,
const bool uncached_mode,
const std::vector<std::string>& supported_transcoding_relative_paths,
const std::vector<std::string>& supported_uncached_relative_paths) {
android::base::SetDefaultTag(LOG_TAG);
struct fuse_args args;
struct fuse_cmdline_opts opts;
struct stat stat;
if (lstat(path.c_str(), &stat)) {
PLOG(ERROR) << "ERROR: failed to stat source " << path;
return;
}
if (!S_ISDIR(stat.st_mode)) {
PLOG(ERROR) << "ERROR: source is not a directory";
return;
}
args = FUSE_ARGS_INIT(0, nullptr);
if (fuse_opt_add_arg(&args, path.c_str()) || fuse_opt_add_arg(&args, "-odebug") ||
fuse_opt_add_arg(&args, ("-omax_read=" + std::to_string(MAX_READ_SIZE)).c_str())) {
LOG(ERROR) << "ERROR: failed to set options";
return;
}
bool bpf_enabled = IsFuseBpfEnabled();
int bpf_fd = -1;
if (bpf_enabled) {
LOG(INFO) << "Using FUSE BPF";
bpf_fd = android::bpf::bpfFdGet(FUSE_BPF_PROG_PATH, BPF_F_RDONLY);
if (bpf_fd < 0) {
PLOG(ERROR) << "Failed to fetch BPF prog fd: " << bpf_fd;
bpf_enabled = false;
} else {
LOG(INFO) << "BPF prog fd fetched";
}
}
struct fuse fuse_default(path, stat.st_ino, uncached_mode, bpf_enabled, bpf_fd,
supported_transcoding_relative_paths,
supported_uncached_relative_paths);
fuse_default.mp = &mp;
// fuse_default is stack allocated, but it's safe to save it as an instance variable because
// this method blocks and FuseDaemon#active tells if we are currently blocking
fuse = &fuse_default;
// Used by pf_read: redacted ranges are represented by zeroized ranges of bytes,
// so we mmap the maximum length of redacted ranges in the beginning and save memory allocations
// on each read.
fuse_default.zero_addr = static_cast<char*>(mmap(
NULL, MAX_READ_SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, /*fd*/ -1, /*off*/ 0));
if (fuse_default.zero_addr == MAP_FAILED) {
LOG(FATAL) << "mmap failed - could not start fuse! errno = " << errno;
}
// Custom logging for libfuse
if (android::base::GetBoolProperty("persist.sys.fuse.log", false)) {
fuse_set_log_func(fuse_logger);
}
if (MY_USER_ID != 0 && mp.IsAppCloneUser(MY_USER_ID)) {
// Disable dentry caching for the app clone user
fuse->disable_dentry_cache = true;
}
fuse->passthrough = android::base::GetBoolProperty("persist.sys.fuse.passthrough.enable", false);
if (fuse->passthrough) {
LOG(INFO) << "Using FUSE passthrough";
}
struct fuse_session
* se = fuse_session_new(&args, &ops, sizeof(ops), &fuse_default);
if (!se) {
PLOG(ERROR) << "Failed to create session ";
return;
}
fuse_default.se = se;
fuse_default.active = &active;
se->fd = fd.release(); // libfuse owns the FD now
se->mountpoint = strdup(path.c_str());
// Single thread. Useful for debugging
// fuse_session_loop(se);
// Multi-threaded
LOG(INFO) << "Starting fuse...";
fuse_session_loop_mt(se, &config);
fuse->active->store(false, std::memory_order_release);
LOG(INFO) << "Ending fuse...";
if (munmap(fuse_default.zero_addr, MAX_READ_SIZE)) {
PLOG(ERROR) << "munmap failed!";
}
fuse_opt_free_args(&args);
fuse_session_destroy(se);
LOG(INFO) << "Ended fuse";
return;
}
std::unique_ptr<FdAccessResult> FuseDaemon::CheckFdAccess(int fd, uid_t uid) const {
struct stat s;
memset(&s, 0, sizeof(s));
if (fstat(fd, &s) < 0) {
PLOG(DEBUG) << "CheckFdAccess fstat failed.";
return std::make_unique<FdAccessResult>(string(), false);
}
ino_t ino = s.st_ino;
dev_t dev = s.st_dev;
dev_t fuse_dev = fuse->dev.load(std::memory_order_acquire);
if (dev != fuse_dev) {
PLOG(DEBUG) << "CheckFdAccess FUSE device id does not match.";
return std::make_unique<FdAccessResult>(string(), false);
}
const node* node = node::LookupInode(fuse->root, ino);
if (!node) {
PLOG(DEBUG) << "CheckFdAccess no node found with given ino";
return std::make_unique<FdAccessResult>(string(), false);
}
return node->CheckHandleForUid(uid);
}
void FuseDaemon::InitializeDeviceId(const std::string& path) {
struct stat stat;
if (lstat(path.c_str(), &stat)) {
PLOG(ERROR) << "InitializeDeviceId failed to stat given path " << path;
return;
}
fuse->dev.store(stat.st_dev, std::memory_order_release);
}
} //namespace fuse
} // namespace mediaprovider