system/core/fs_mgr/include/fs_mgr.h

/*
 * Copyright (C) 2012 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.
 */

#pragma once

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <linux/dm-ioctl.h>

#include <functional>
#include <optional>
#include <string>

#include <fstab/fstab.h>

// Magic number at start of verity metadata
#define VERITY_METADATA_MAGIC_NUMBER 0xb001b001

// Replacement magic number at start of verity metadata to cleanly
// turn verity off in userdebug builds.
#define VERITY_METADATA_MAGIC_DISABLE 0x46464f56 // "VOFF"

// Verity modes
enum verity_mode {
    VERITY_MODE_EIO = 0,
    VERITY_MODE_LOGGING = 1,
    VERITY_MODE_RESTART = 2,
    VERITY_MODE_LAST = VERITY_MODE_RESTART,
    VERITY_MODE_DEFAULT = VERITY_MODE_RESTART
};

// Mount modes
enum mount_mode {
    MOUNT_MODE_DEFAULT = 0,
    MOUNT_MODE_EARLY = 1,
    MOUNT_MODE_LATE = 2,
    // TODO(b/135984674): remove this after refactoring fs_mgr_mount_all.
    MOUNT_MODE_ONLY_USERDATA = 3
};

#define FS_MGR_MNTALL_DEV_IS_METADATA_ENCRYPTED 7
#define FS_MGR_MNTALL_DEV_NEEDS_METADATA_ENCRYPTION 6
#define FS_MGR_MNTALL_DEV_FILE_ENCRYPTED 5
#define FS_MGR_MNTALL_DEV_NEEDS_RECOVERY 4
#define FS_MGR_MNTALL_DEV_NOT_ENCRYPTABLE 0
#define FS_MGR_MNTALL_FAIL (-1)

struct MountAllResult {
    // One of the FS_MGR_MNTALL_* returned code defined above.
    int code;
    // Whether userdata was mounted as a result of |fs_mgr_mount_all| call.
    bool userdata_mounted;
};

struct HashtreeInfo {
    // The hash algorithm used to build the merkle tree.
    std::string algorithm;
    // The root digest of the merkle tree.
    std::string root_digest;
};

// fs_mgr_mount_all() updates fstab entries that reference device-mapper.
// Returns a |MountAllResult|. The first element is one of the FS_MNG_MNTALL_* return codes
// defined above, and the second element tells whether this call to fs_mgr_mount_all was responsible
// for mounting userdata. Later is required for init to correctly enqueue fs-related events as part
// of userdata remount during userspace reboot.
MountAllResult fs_mgr_mount_all(android::fs_mgr::Fstab* fstab, int mount_mode);

#define FS_MGR_DOMNT_FAILED (-1)
#define FS_MGR_DOMNT_BUSY (-2)
#define FS_MGR_DOMNT_SUCCESS 0
int fs_mgr_do_mount(android::fs_mgr::Fstab* fstab, const char* n_name, char* n_blk_device,
                    char* tmp_mount_point);
int fs_mgr_do_mount(android::fs_mgr::Fstab* fstab, const char* n_name, char* n_blk_device,
                    char* tmp_mount_point, bool need_cp, bool metadata_encrypted);
int fs_mgr_do_mount_one(const android::fs_mgr::FstabEntry& entry,
                        const std::string& mount_point = "");
int fs_mgr_do_tmpfs_mount(const char *n_name);
bool fs_mgr_load_verity_state(int* mode);
// Returns true if verity is enabled on this particular FstabEntry.
bool fs_mgr_is_verity_enabled(const android::fs_mgr::FstabEntry& entry);
// Returns the verity hashtree information of this particular FstabEntry. Returns std::nullopt
// if the input isn't a dm-verity entry, or if there is an error.
std::optional<HashtreeInfo> fs_mgr_get_hashtree_info(const android::fs_mgr::FstabEntry& entry);

bool fs_mgr_swapon_all(const android::fs_mgr::Fstab& fstab);
bool fs_mgr_update_logical_partition(android::fs_mgr::FstabEntry* entry);

// Returns true if the given fstab entry has verity enabled, *and* the verity
// device is in "check_at_most_once" mode.
bool fs_mgr_verity_is_check_at_most_once(const android::fs_mgr::FstabEntry& entry);

int fs_mgr_do_format(const android::fs_mgr::FstabEntry& entry);

#define FS_MGR_SETUP_VERITY_SKIPPED  (-3)
#define FS_MGR_SETUP_VERITY_DISABLED (-2)
#define FS_MGR_SETUP_VERITY_FAIL (-1)
#define FS_MGR_SETUP_VERITY_SUCCESS 0
int fs_mgr_setup_verity(android::fs_mgr::FstabEntry* fstab, bool wait_for_verity_dev);

// Return the name of the super partition if it exists. If a slot number is
// specified, the super partition for the corresponding metadata slot will be
// returned. Otherwise, it will use the current slot.
std::string fs_mgr_get_super_partition_name(int slot = -1);

enum FsMgrUmountStatus : int {
    SUCCESS = 0,
    ERROR_UNKNOWN = 1 << 0,
    ERROR_UMOUNT = 1 << 1,
    ERROR_VERITY = 1 << 2,
    ERROR_DEVICE_MAPPER = 1 << 3,
};
// fs_mgr_umount_all() is the reverse of fs_mgr_mount_all. In particular,
// it destroys verity devices from device mapper after the device is unmounted.
int fs_mgr_umount_all(android::fs_mgr::Fstab* fstab);

// Finds a entry in |fstab| that was used to mount a /data on |data_block_device|.
android::fs_mgr::FstabEntry* fs_mgr_get_mounted_entry_for_userdata(
        android::fs_mgr::Fstab* fstab, const std::string& data_block_device);
int fs_mgr_remount_userdata_into_checkpointing(android::fs_mgr::Fstab* fstab);

// Finds the dm_bow device on which this block device is stacked, or returns
// empty string
std::string fs_mgr_find_bow_device(const std::string& block_device);

// Creates mount point if not already existed, and checks that mount point is a
// canonical path that doesn't contain any symbolic link or /../.
bool fs_mgr_create_canonical_mount_point(const std::string& mount_point);

// Like fs_mgr_do_mount_one() but for overlayfs fstab entries.
// Unlike fs_mgr_overlayfs, mount overlayfs without upperdir and workdir, so the
// filesystem cannot be remount read-write.
bool fs_mgr_mount_overlayfs_fstab_entry(const android::fs_mgr::FstabEntry& entry);