Utils.h - platform/system/vold - Git at Google

 /*
  * Copyright (C) 2015 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.
  */

 #ifndef ANDROID_VOLD_UTILS_H
 #define ANDROID_VOLD_UTILS_H

 #include "KeyBuffer.h"

 #include <android-base/macros.h>
 #include <android-base/unique_fd.h>
 #include <cutils/multiuser.h>
 #include <selinux/selinux.h>
 #include <utils/Errors.h>

 #include <chrono>
 #include <string>
 #include <string_view>
 #include <vector>

 struct DIR;

 namespace android {
 namespace vold {

 static const char* kVoldAppDataIsolationEnabled = "persist.sys.vold_app_data_isolation_enabled";
 static const char* kExternalStorageSdcardfs = "external_storage.sdcardfs.enabled";

 static constexpr std::chrono::seconds kUntrustedFsckSleepTime(45);

 /* SELinux contexts used depending on the block device type */
 extern char* sBlkidContext;
 extern char* sBlkidUntrustedContext;
 extern char* sFsckContext;
 extern char* sFsckUntrustedContext;

 // TODO remove this with better solution, b/64143519
 extern bool sSleepOnUnmount;

 std::string GetFuseMountPathForUser(userid_t user_id, const std::string& relative_upper_path);

 status_t CreateDeviceNode(const std::string& path, dev_t dev);
 status_t DestroyDeviceNode(const std::string& path);

 status_t SetDefaultAcl(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
                        std::vector<gid_t> additionalGids);

 status_t AbortFuseConnections();

 int SetQuotaInherit(const std::string& path);
 int SetQuotaProjectId(const std::string& path, long projectId);
 /*
  * Creates and sets up an application-specific path on external
  * storage with the correct ACL and project ID (if needed).
  *
  * ONLY for use with app-specific data directories on external storage!
  * (eg, /Android/data/com.foo, /Android/obb/com.foo, etc.)
  */
 int PrepareAppDirFromRoot(const std::string& path, const std::string& root, int appUid,
                           bool fixupExisting);

 /* fs_prepare_dir wrapper that creates with SELinux context */
 status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
                     unsigned int attrs = 0);

 /* Really unmounts the path, killing active processes along the way */
 status_t ForceUnmount(const std::string& path);

 /* Kills any processes using given path */
 status_t KillProcessesUsingPath(const std::string& path);

 /* Kills any processes using given tmpfs mount prifix */
 status_t KillProcessesWithTmpfsMountPrefix(const std::string& path);

 /* Creates bind mount from source to target */
 status_t BindMount(const std::string& source, const std::string& target);

 /** Creates a symbolic link to target */
 status_t Symlink(const std::string& target, const std::string& linkpath);

 /** Calls unlink(2) at linkpath */
 status_t Unlink(const std::string& linkpath);

 /** Creates the given directory if it is not already available */
 status_t CreateDir(const std::string& dir, mode_t mode);

 bool FindValue(const std::string& raw, const std::string& key, std::string* value);

 /* Reads filesystem metadata from device at path */
 status_t ReadMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
                       std::string* fsLabel);

 /* Reads filesystem metadata from untrusted device at path */
 status_t ReadMetadataUntrusted(const std::string& path, std::string* fsType, std::string* fsUuid,
                                std::string* fsLabel);

 /* Returns either WEXITSTATUS() status, or a negative errno */
 status_t ForkExecvp(const std::vector<std::string>& args,
                     std::vector<std::string>* output = nullptr, char* context = nullptr);
 status_t ForkExecvpTimeout(const std::vector<std::string>& args, std::chrono::seconds timeout,
                            char* context = nullptr);

 pid_t ForkExecvpAsync(const std::vector<std::string>& args, char* context = nullptr);

 /* Gets block device size in bytes */
 status_t GetBlockDevSize(int fd, uint64_t* size);
 status_t GetBlockDevSize(const std::string& path, uint64_t* size);
 /* Gets block device size in 512 byte sectors */
 status_t GetBlockDev512Sectors(const std::string& path, uint64_t* nr_sec);

 status_t ReadRandomBytes(size_t bytes, std::string& out);
 status_t ReadRandomBytes(size_t bytes, char* buffer);
 status_t GenerateRandomUuid(std::string& out);

 /* Converts hex string to raw bytes, ignoring [ :-] */
 status_t HexToStr(const std::string& hex, std::string& str);
 /* Converts raw bytes to hex string */
 status_t StrToHex(const std::string& str, std::string& hex);
 /* Converts raw key bytes to hex string */
 status_t StrToHex(const KeyBuffer& str, KeyBuffer& hex);
 /* Normalize given hex string into consistent format */
 status_t NormalizeHex(const std::string& in, std::string& out);

 uint64_t GetFreeBytes(const std::string& path);
 uint64_t GetTreeBytes(const std::string& path);

 bool IsFilesystemSupported(const std::string& fsType);
 bool IsSdcardfsUsed();
 bool IsFuseDaemon(const pid_t pid);

 /* Wipes contents of block device at given path */
 status_t WipeBlockDevice(const std::string& path);

 std::string BuildKeyPath(const std::string& partGuid);

 std::string BuildDataSystemLegacyPath(userid_t userid);
 std::string BuildDataSystemCePath(userid_t userid);
 std::string BuildDataSystemDePath(userid_t userid);
 std::string BuildDataProfilesDePath(userid_t userid);
 std::string BuildDataVendorCePath(userid_t userid);
 std::string BuildDataVendorDePath(userid_t userid);

 std::string BuildDataPath(const std::string& volumeUuid);
 std::string BuildDataMediaCePath(const std::string& volumeUuid, userid_t userid);
 std::string BuildDataMiscCePath(const std::string& volumeUuid, userid_t userid);
 std::string BuildDataMiscDePath(const std::string& volumeUuid, userid_t userid);
 std::string BuildDataUserCePath(const std::string& volumeUuid, userid_t userid);
 std::string BuildDataUserDePath(const std::string& volumeUuid, userid_t userid);

 dev_t GetDevice(const std::string& path);

 bool IsSymlink(const std::string& path);

 bool IsSameFile(const std::string& path1, const std::string& path2);

 status_t EnsureDirExists(const std::string& path, mode_t mode, uid_t uid, gid_t gid);

 status_t RestoreconRecursive(const std::string& path);

 // TODO: promote to android::base
 bool Readlinkat(int dirfd, const std::string& path, std::string* result);

 // Handles dynamic major assignment for virtio-block
 bool IsVirtioBlkDevice(unsigned int major);

 status_t UnmountTree(const std::string& mountPoint);

 bool IsDotOrDotDot(const struct dirent& ent);

 status_t DeleteDirContentsAndDir(const std::string& pathname);
 status_t DeleteDirContents(const std::string& pathname);

 status_t WaitForFile(const char* filename, std::chrono::nanoseconds timeout);

 bool pathExists(const std::string& path);

 bool FsyncDirectory(const std::string& dirname);

 bool FsyncParentDirectory(const std::string& path);

 bool MkdirsSync(const std::string& path, mode_t mode);

 bool writeStringToFile(const std::string& payload, const std::string& filename);

 void ConfigureMaxDirtyRatioForFuse(const std::string& fuse_mount, unsigned int max_ratio);

 void ConfigureReadAheadForFuse(const std::string& fuse_mount, size_t read_ahead_kb);

 status_t MountUserFuse(userid_t user_id, const std::string& absolute_lower_path,
                        const std::string& relative_upper_path, android::base::unique_fd* fuse_fd);

 status_t UnmountUserFuse(userid_t userId, const std::string& absolute_lower_path,
                          const std::string& relative_upper_path);

 status_t PrepareAndroidDirs(const std::string& volumeRoot);

 bool IsFuseBpfEnabled();

 // Open a given directory as an FD, and return that and the corresponding procfs virtual
 // symlink path that can be used in any API that accepts a path string. Path stays valid until
 // the directory FD is closed.
 //
 // This may be useful when an API wants to restrict a path passed from an untrusted process,
 // and do it without any TOCTOU attacks possible (e.g. where an attacker replaces one of
 // the components with a symlink after the check passed). In that case opening a path through
 // this function guarantees that the target directory stays the same, and that it can be
 // referenced inside the current process via the virtual procfs symlink returned here.
 std::pair<android::base::unique_fd, std::string> OpenDirInProcfs(std::string_view path);

 }  // namespace vold
 }  // namespace android

 #endif
	/*
	* Copyright (C) 2015 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.
	*/

	#ifndef ANDROID_VOLD_UTILS_H
	#define ANDROID_VOLD_UTILS_H

	#include "KeyBuffer.h"

	#include <android-base/macros.h>
	#include <android-base/unique_fd.h>
	#include <cutils/multiuser.h>
	#include <selinux/selinux.h>
	#include <utils/Errors.h>

	#include <chrono>
	#include <string>
	#include <string_view>
	#include <vector>

	struct DIR;

	namespace android {
	namespace vold {

	static const char* kVoldAppDataIsolationEnabled = "persist.sys.vold_app_data_isolation_enabled";
	static const char* kExternalStorageSdcardfs = "external_storage.sdcardfs.enabled";

	static constexpr std::chrono::seconds kUntrustedFsckSleepTime(45);

	/* SELinux contexts used depending on the block device type */
	extern char* sBlkidContext;
	extern char* sBlkidUntrustedContext;
	extern char* sFsckContext;
	extern char* sFsckUntrustedContext;

	// TODO remove this with better solution, b/64143519
	extern bool sSleepOnUnmount;

	std::string GetFuseMountPathForUser(userid_t user_id, const std::string& relative_upper_path);

	status_t CreateDeviceNode(const std::string& path, dev_t dev);
	status_t DestroyDeviceNode(const std::string& path);

	status_t SetDefaultAcl(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
	std::vector<gid_t> additionalGids);

	status_t AbortFuseConnections();

	int SetQuotaInherit(const std::string& path);
	int SetQuotaProjectId(const std::string& path, long projectId);
	/*
	* Creates and sets up an application-specific path on external
	* storage with the correct ACL and project ID (if needed).
	*
	* ONLY for use with app-specific data directories on external storage!
	* (eg, /Android/data/com.foo, /Android/obb/com.foo, etc.)
	*/
	int PrepareAppDirFromRoot(const std::string& path, const std::string& root, int appUid,
	bool fixupExisting);

	/* fs_prepare_dir wrapper that creates with SELinux context */
	status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
	unsigned int attrs = 0);

	/* Really unmounts the path, killing active processes along the way */
	status_t ForceUnmount(const std::string& path);

	/* Kills any processes using given path */
	status_t KillProcessesUsingPath(const std::string& path);

	/* Kills any processes using given tmpfs mount prifix */
	status_t KillProcessesWithTmpfsMountPrefix(const std::string& path);

	/* Creates bind mount from source to target */
	status_t BindMount(const std::string& source, const std::string& target);

	/** Creates a symbolic link to target */
	status_t Symlink(const std::string& target, const std::string& linkpath);

	/** Calls unlink(2) at linkpath */
	status_t Unlink(const std::string& linkpath);

	/** Creates the given directory if it is not already available */
	status_t CreateDir(const std::string& dir, mode_t mode);

	bool FindValue(const std::string& raw, const std::string& key, std::string* value);

	/* Reads filesystem metadata from device at path */
	status_t ReadMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
	std::string* fsLabel);

	/* Reads filesystem metadata from untrusted device at path */
	status_t ReadMetadataUntrusted(const std::string& path, std::string* fsType, std::string* fsUuid,
	std::string* fsLabel);

	/* Returns either WEXITSTATUS() status, or a negative errno */
	status_t ForkExecvp(const std::vector<std::string>& args,
	std::vector<std::string>* output = nullptr, char* context = nullptr);
	status_t ForkExecvpTimeout(const std::vector<std::string>& args, std::chrono::seconds timeout,
	char* context = nullptr);

	pid_t ForkExecvpAsync(const std::vector<std::string>& args, char* context = nullptr);

	/* Gets block device size in bytes */
	status_t GetBlockDevSize(int fd, uint64_t* size);
	status_t GetBlockDevSize(const std::string& path, uint64_t* size);
	/* Gets block device size in 512 byte sectors */
	status_t GetBlockDev512Sectors(const std::string& path, uint64_t* nr_sec);

	status_t ReadRandomBytes(size_t bytes, std::string& out);
	status_t ReadRandomBytes(size_t bytes, char* buffer);
	status_t GenerateRandomUuid(std::string& out);

	/* Converts hex string to raw bytes, ignoring [ :-] */
	status_t HexToStr(const std::string& hex, std::string& str);
	/* Converts raw bytes to hex string */
	status_t StrToHex(const std::string& str, std::string& hex);
	/* Converts raw key bytes to hex string */
	status_t StrToHex(const KeyBuffer& str, KeyBuffer& hex);
	/* Normalize given hex string into consistent format */
	status_t NormalizeHex(const std::string& in, std::string& out);

	uint64_t GetFreeBytes(const std::string& path);
	uint64_t GetTreeBytes(const std::string& path);

	bool IsFilesystemSupported(const std::string& fsType);
	bool IsSdcardfsUsed();
	bool IsFuseDaemon(const pid_t pid);

	/* Wipes contents of block device at given path */
	status_t WipeBlockDevice(const std::string& path);

	std::string BuildKeyPath(const std::string& partGuid);

	std::string BuildDataSystemLegacyPath(userid_t userid);
	std::string BuildDataSystemCePath(userid_t userid);
	std::string BuildDataSystemDePath(userid_t userid);
	std::string BuildDataProfilesDePath(userid_t userid);
	std::string BuildDataVendorCePath(userid_t userid);
	std::string BuildDataVendorDePath(userid_t userid);

	std::string BuildDataPath(const std::string& volumeUuid);
	std::string BuildDataMediaCePath(const std::string& volumeUuid, userid_t userid);
	std::string BuildDataMiscCePath(const std::string& volumeUuid, userid_t userid);
	std::string BuildDataMiscDePath(const std::string& volumeUuid, userid_t userid);
	std::string BuildDataUserCePath(const std::string& volumeUuid, userid_t userid);
	std::string BuildDataUserDePath(const std::string& volumeUuid, userid_t userid);

	dev_t GetDevice(const std::string& path);

	bool IsSymlink(const std::string& path);

	bool IsSameFile(const std::string& path1, const std::string& path2);

	status_t EnsureDirExists(const std::string& path, mode_t mode, uid_t uid, gid_t gid);

	status_t RestoreconRecursive(const std::string& path);

	// TODO: promote to android::base
	bool Readlinkat(int dirfd, const std::string& path, std::string* result);

	// Handles dynamic major assignment for virtio-block
	bool IsVirtioBlkDevice(unsigned int major);

	status_t UnmountTree(const std::string& mountPoint);

	bool IsDotOrDotDot(const struct dirent& ent);

	status_t DeleteDirContentsAndDir(const std::string& pathname);
	status_t DeleteDirContents(const std::string& pathname);

	status_t WaitForFile(const char* filename, std::chrono::nanoseconds timeout);

	bool pathExists(const std::string& path);

	bool FsyncDirectory(const std::string& dirname);

	bool FsyncParentDirectory(const std::string& path);

	bool MkdirsSync(const std::string& path, mode_t mode);

	bool writeStringToFile(const std::string& payload, const std::string& filename);

	void ConfigureMaxDirtyRatioForFuse(const std::string& fuse_mount, unsigned int max_ratio);

	void ConfigureReadAheadForFuse(const std::string& fuse_mount, size_t read_ahead_kb);

	status_t MountUserFuse(userid_t user_id, const std::string& absolute_lower_path,
	const std::string& relative_upper_path, android::base::unique_fd* fuse_fd);

	status_t UnmountUserFuse(userid_t userId, const std::string& absolute_lower_path,
	const std::string& relative_upper_path);

	status_t PrepareAndroidDirs(const std::string& volumeRoot);

	bool IsFuseBpfEnabled();

	// Open a given directory as an FD, and return that and the corresponding procfs virtual
	// symlink path that can be used in any API that accepts a path string. Path stays valid until
	// the directory FD is closed.
	//
	// This may be useful when an API wants to restrict a path passed from an untrusted process,
	// and do it without any TOCTOU attacks possible (e.g. where an attacker replaces one of
	// the components with a symlink after the check passed). In that case opening a path through
	// this function guarantees that the target directory stays the same, and that it can be
	// referenced inside the current process via the virtual procfs symlink returned here.
	std::pair<android::base::unique_fd, std::string> OpenDirInProcfs(std::string_view path);

	} // namespace vold
	} // namespace android

	#endif