ac02a4863f
Bug: 110379912 Test: testOpenProxyFileDescriptor Change-Id: I0429a498d7b54682efe9b05815f3470e8745609e
164 lines
4.9 KiB
C++
164 lines
4.9 KiB
C++
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "AppFuseUtil.h"
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#include <sys/mount.h>
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#include <utils/Errors.h>
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include "Utils.h"
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using android::base::StringPrintf;
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namespace android {
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namespace vold {
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namespace {
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static size_t kAppFuseMaxMountPointName = 32;
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static android::status_t GetMountPath(uid_t uid, const std::string& name, std::string* path) {
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if (name.size() > kAppFuseMaxMountPointName) {
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LOG(ERROR) << "AppFuse mount name is too long.";
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return -EINVAL;
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}
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for (size_t i = 0; i < name.size(); i++) {
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if (!isalnum(name[i])) {
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LOG(ERROR) << "AppFuse mount name contains invalid character.";
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return -EINVAL;
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}
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}
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*path = StringPrintf("/mnt/appfuse/%d_%s", uid, name.c_str());
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return android::OK;
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}
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static android::status_t Mount(int device_fd, const std::string& path) {
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// Remove existing mount.
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android::vold::ForceUnmount(path);
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const auto opts = StringPrintf(
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"fd=%i,"
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"rootmode=40000,"
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"default_permissions,"
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"allow_other,"
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"user_id=0,group_id=0,"
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"context=\"u:object_r:app_fuse_file:s0\","
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"fscontext=u:object_r:app_fusefs:s0",
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device_fd);
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const int result =
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TEMP_FAILURE_RETRY(mount("/dev/fuse", path.c_str(), "fuse",
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MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME, opts.c_str()));
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if (result != 0) {
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PLOG(ERROR) << "Failed to mount " << path;
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return -errno;
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}
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return android::OK;
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}
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static android::status_t RunCommand(const std::string& command, uid_t uid, const std::string& path,
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int device_fd) {
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if (DEBUG_APPFUSE) {
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LOG(DEBUG) << "Run app fuse command " << command << " for the path " << path << " and uid "
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<< uid;
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}
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if (command == "mount") {
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return Mount(device_fd, path);
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} else if (command == "unmount") {
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// If it's just after all FD opened on mount point are closed, umount2 can fail with
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// EBUSY. To avoid the case, specify MNT_DETACH.
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if (umount2(path.c_str(), UMOUNT_NOFOLLOW | MNT_DETACH) != 0 && errno != EINVAL &&
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errno != ENOENT) {
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PLOG(ERROR) << "Failed to unmount directory.";
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return -errno;
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}
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if (rmdir(path.c_str()) != 0) {
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PLOG(ERROR) << "Failed to remove the mount directory.";
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return -errno;
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}
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return android::OK;
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} else {
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LOG(ERROR) << "Unknown appfuse command " << command;
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return -EPERM;
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}
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return android::OK;
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}
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} // namespace
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int MountAppFuse(uid_t uid, int mountId, android::base::unique_fd* device_fd) {
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std::string name = std::to_string(mountId);
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// Check mount point name.
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std::string path;
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if (GetMountPath(uid, name, &path) != android::OK) {
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LOG(ERROR) << "Invalid mount point name";
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return -1;
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}
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// Create directories.
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const android::status_t result = android::vold::PrepareDir(path, 0700, 0, 0);
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if (result != android::OK) {
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PLOG(ERROR) << "Failed to prepare directory " << path;
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return -1;
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}
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// Open device FD.
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device_fd->reset(open("/dev/fuse", O_RDWR)); // not O_CLOEXEC
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if (device_fd->get() == -1) {
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PLOG(ERROR) << "Failed to open /dev/fuse";
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return -1;
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}
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// Mount.
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return RunCommand("mount", uid, path, device_fd->get());
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}
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int UnmountAppFuse(uid_t uid, int mountId) {
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std::string name = std::to_string(mountId);
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// Check mount point name.
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std::string path;
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if (GetMountPath(uid, name, &path) != android::OK) {
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LOG(ERROR) << "Invalid mount point name";
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return -1;
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}
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return RunCommand("unmount", uid, path, -1 /* device_fd */);
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}
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int OpenAppFuseFile(uid_t uid, int mountId, int fileId, int flags) {
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std::string name = std::to_string(mountId);
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// Check mount point name.
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std::string mountPoint;
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if (GetMountPath(uid, name, &mountPoint) != android::OK) {
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LOG(ERROR) << "Invalid mount point name";
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return -1;
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}
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std::string path = StringPrintf("%s/%d", mountPoint.c_str(), fileId);
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return TEMP_FAILURE_RETRY(open(path.c_str(), flags));
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}
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} // namespace vold
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} // namespace android
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