include/uapi/linux/incrementalfs.h

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
* Userspace interface for Incremental FS.
*
* Incremental FS is special-purpose Linux virtual file system that allows
* execution of a program while its binary and resource files are still being
* lazily downloaded over the network, USB etc.
*
* Copyright 2019 Google LLC
*/
#ifndef _UAPI_LINUX_INCREMENTALFS_H
#define _UAPI_LINUX_INCREMENTALFS_H

#include <linux/limits.h>
#include <linux/ioctl.h>
#include <linux/types.h>
#include <linux/xattr.h>

/* ===== constants ===== */
#define INCFS_NAME "incremental-fs"

/*
* Magic number used in file header and in memory superblock
* Note that it is a 5 byte unsigned long. Thus on 32 bit kernels, it is
* truncated to a 4 byte number
*/
#define INCFS_MAGIC_NUMBER (0x5346434e49ul & ULONG_MAX)

#define INCFS_DATA_FILE_BLOCK_SIZE 4096
#define INCFS_HEADER_VER 1

/* TODO: This value is assumed in incfs_copy_signature_info_from_user to be the
* actual signature length. Set back to 64 when fixed.
*/
#define INCFS_MAX_HASH_SIZE 32
#define INCFS_MAX_FILE_ATTR_SIZE 512

#define INCFS_INDEX_NAME ".index"
#define INCFS_INCOMPLETE_NAME ".incomplete"
#define INCFS_PENDING_READS_FILENAME ".pending_reads"
#define INCFS_LOG_FILENAME ".log"
#define INCFS_BLOCKS_WRITTEN_FILENAME ".blocks_written"
#define INCFS_XATTR_ID_NAME (XATTR_USER_PREFIX "incfs.id")
#define INCFS_XATTR_SIZE_NAME (XATTR_USER_PREFIX "incfs.size")
#define INCFS_XATTR_METADATA_NAME (XATTR_USER_PREFIX "incfs.metadata")
#define INCFS_XATTR_VERITY_NAME (XATTR_USER_PREFIX "incfs.verity")

#define INCFS_MAX_SIGNATURE_SIZE 8096
#define INCFS_SIGNATURE_VERSION 2
#define INCFS_SIGNATURE_SECTIONS 2

#define INCFS_IOCTL_BASE_CODE 'g'

/* ===== ioctl requests on the command dir ===== */

/*
* Create a new file
* May only be called on .pending_reads file
*/
#define INCFS_IOC_CREATE_FILE \
_IOWR(INCFS_IOCTL_BASE_CODE, 30, struct incfs_new_file_args)

/* Read file signature */
#define INCFS_IOC_READ_FILE_SIGNATURE \
_IOR(INCFS_IOCTL_BASE_CODE, 31, struct incfs_get_file_sig_args)

/*
* Fill in one or more data block. This may only be called on a handle
* passed as a parameter to INCFS_IOC_PERMIT_FILLING
*
* Returns number of blocks filled in, or error if none were
*/
#define INCFS_IOC_FILL_BLOCKS \
_IOR(INCFS_IOCTL_BASE_CODE, 32, struct incfs_fill_blocks)

/*
* Permit INCFS_IOC_FILL_BLOCKS on the given file descriptor
* May only be called on .pending_reads file
*
* Returns 0 on success or error
*/
#define INCFS_IOC_PERMIT_FILL \
_IOW(INCFS_IOCTL_BASE_CODE, 33, struct incfs_permit_fill)

/*
* Fills buffer with ranges of populated blocks
*
* Returns 0 if all ranges written
* error otherwise
*
* Either way, range_buffer_size_out is set to the number
* of bytes written. Should be set to 0 by caller. The ranges
* filled are valid, but if an error was returned there might
* be more ranges to come.
*
* Ranges are ranges of filled blocks:
*
* 1 2 7 9
*
* means blocks 1, 2, 7, 8, 9 are filled, 0, 3, 4, 5, 6 and 10 on
* are not
*
* If hashing is enabled for the file, the hash blocks are simply
* treated as though they immediately followed the data blocks.
*/
#define INCFS_IOC_GET_FILLED_BLOCKS \
_IOR(INCFS_IOCTL_BASE_CODE, 34, struct incfs_get_filled_blocks_args)

/*
* Creates a new mapped file
* May only be called on .pending_reads file
*/
#define INCFS_IOC_CREATE_MAPPED_FILE \
_IOWR(INCFS_IOCTL_BASE_CODE, 35, struct incfs_create_mapped_file_args)

/*
* Get number of blocks, total and filled
* May only be called on .pending_reads file
*/
#define INCFS_IOC_GET_BLOCK_COUNT \
_IOR(INCFS_IOCTL_BASE_CODE, 36, struct incfs_get_block_count_args)

/*
* Get per UID read timeouts
* May only be called on .pending_reads file
*/
#define INCFS_IOC_GET_READ_TIMEOUTS \
_IOR(INCFS_IOCTL_BASE_CODE, 37, struct incfs_get_read_timeouts_args)

/*
* Set per UID read timeouts
* May only be called on .pending_reads file
*/
#define INCFS_IOC_SET_READ_TIMEOUTS \
_IOW(INCFS_IOCTL_BASE_CODE, 38, struct incfs_set_read_timeouts_args)

/*
* Get last read error
* May only be called on .pending_reads file
*/
#define INCFS_IOC_GET_LAST_READ_ERROR \
_IOW(INCFS_IOCTL_BASE_CODE, 39, struct incfs_get_last_read_error_args)

/* ===== sysfs feature flags ===== */
/*
* Each flag is represented by a file in /sys/fs/incremental-fs/features
* If the file exists the feature is supported
* Also the file contents will be the line "supported"
*/

/*
* Basic flag stating that the core incfs file system is available
*/
#define INCFS_FEATURE_FLAG_COREFS "corefs"

/*
* zstd compression support
*/
#define INCFS_FEATURE_FLAG_ZSTD "zstd"

/*
* v2 feature set support. Covers:
* INCFS_IOC_CREATE_MAPPED_FILE
* INCFS_IOC_GET_BLOCK_COUNT
* INCFS_IOC_GET_READ_TIMEOUTS/INCFS_IOC_SET_READ_TIMEOUTS
* .blocks_written status file
* .incomplete folder
* report_uid mount option
*/
#define INCFS_FEATURE_FLAG_V2 "v2"

enum incfs_compression_alg {
COMPRESSION_NONE = 0,
COMPRESSION_LZ4 = 1,
COMPRESSION_ZSTD = 2,
};

enum incfs_block_flags {
INCFS_BLOCK_FLAGS_NONE = 0,
INCFS_BLOCK_FLAGS_HASH = 1,
};

typedef struct {
__u8 bytes[16];
} incfs_uuid_t __attribute__((aligned (8)));

/*
* Description of a pending read. A pending read - a read call by
* a userspace program for which the filesystem currently doesn't have data.
*
* Reads from .pending_reads and .log return an array of these structure
*/
struct incfs_pending_read_info {
/* Id of a file that is being read from. */
incfs_uuid_t file_id;

/* A number of microseconds since system boot to the read. */
__aligned_u64 timestamp_us;

/* Index of a file block that is being read. */
__u32 block_index;

/* A serial number of this pending read. */
__u32 serial_number;
};

/*
* Description of a pending read. A pending read - a read call by
* a userspace program for which the filesystem currently doesn't have data.
*
* This version of incfs_pending_read_info is used whenever the file system is
* mounted with the report_uid flag
*/
struct incfs_pending_read_info2 {
/* Id of a file that is being read from. */
incfs_uuid_t file_id;

/* A number of microseconds since system boot to the read. */
__aligned_u64 timestamp_us;

/* Index of a file block that is being read. */
__u32 block_index;

/* A serial number of this pending read. */
__u32 serial_number;

/* The UID of the reading process */
__u32 uid;

__u32 reserved;
};

/*
* Description of a data or hash block to add to a data file.
*/
struct incfs_fill_block {
/* Index of a data block. */
__u32 block_index;

/* Length of data */
__u32 data_len;

/*
* A pointer to an actual data for the block.
*
* Equivalent to: __u8 *data;
*/
__aligned_u64 data;

/*
* Compression algorithm used to compress the data block.
* Values from enum incfs_compression_alg.
*/
__u8 compression;

/* Values from enum incfs_block_flags */
__u8 flags;

__u16 reserved1;

__u32 reserved2;

__aligned_u64 reserved3;
};

/*
* Description of a number of blocks to add to a data file
*
* Argument for INCFS_IOC_FILL_BLOCKS
*/
struct incfs_fill_blocks {
/* Number of blocks */
__u64 count;

/* A pointer to an array of incfs_fill_block structs */
__aligned_u64 fill_blocks;
};

/*
* Permit INCFS_IOC_FILL_BLOCKS on the given file descriptor
* May only be called on .pending_reads file
*
* Argument for INCFS_IOC_PERMIT_FILL
*/
struct incfs_permit_fill {
/* File to permit fills on */
__u32 file_descriptor;
};

enum incfs_hash_tree_algorithm {
INCFS_HASH_TREE_NONE = 0,
INCFS_HASH_TREE_SHA256 = 1
};

/*
* Create a new file or directory.
*/
struct incfs_new_file_args {
/* Id of a file to create. */
incfs_uuid_t file_id;

/*
* Total size of the new file. Ignored if S_ISDIR(mode).
*/
__aligned_u64 size;

/*
* File mode. Permissions and dir flag.
*/
__u16 mode;

__u16 reserved1;

__u32 reserved2;

/*
* A pointer to a null-terminated relative path to the file's parent
* dir.
* Max length: PATH_MAX
*
* Equivalent to: char *directory_path;
*/
__aligned_u64 directory_path;

/*
* A pointer to a null-terminated file's name.
* Max length: PATH_MAX
*
* Equivalent to: char *file_name;
*/
__aligned_u64 file_name;

/*
* A pointer to a file attribute to be set on creation.
*
* Equivalent to: u8 *file_attr;
*/
__aligned_u64 file_attr;

/*
* Length of the data buffer specfied by file_attr.
* Max value: INCFS_MAX_FILE_ATTR_SIZE
*/
__u32 file_attr_len;

__u32 reserved4;

/*
* Points to an APK V4 Signature data blob
* Signature must have two sections
* Format is:
*	u32 version
*	u32 size_of_hash_info_section
*	u8 hash_info_section[]
*	u32 size_of_signing_info_section
*	u8 signing_info_section[]
*
* Note that incfs does not care about what is in signing_info_section
*
* hash_info_section has following format:
*	u32 hash_algorithm; // Must be SHA256 == 1
*	u8 log2_blocksize; // Must be 12 for 4096 byte blocks
*	u32 salt_size;
*	u8 salt[];
*	u32 hash_size;
*	u8 root_hash[];
*/
__aligned_u64 signature_info;

/* Size of signature_info */
__aligned_u64 signature_size;

__aligned_u64 reserved6;
};

/*
* Request a digital signature blob for a given file.
* Argument for INCFS_IOC_READ_FILE_SIGNATURE ioctl
*/
struct incfs_get_file_sig_args {
/*
* A pointer to the data buffer to save an signature blob to.
*
* Equivalent to: u8 *file_signature;
*/
__aligned_u64 file_signature;

/* Size of the buffer at file_signature. */
__u32 file_signature_buf_size;

/*
* Number of bytes save file_signature buffer.
* It is set after ioctl done.
*/
__u32 file_signature_len_out;
};

struct incfs_filled_range {
__u32 begin;
__u32 end;
};

/*
* Request ranges of filled blocks
* Argument for INCFS_IOC_GET_FILLED_BLOCKS
*/
struct incfs_get_filled_blocks_args {
/*
* A buffer to populate with ranges of filled blocks
*
* Equivalent to struct incfs_filled_ranges *range_buffer
*/
__aligned_u64 range_buffer;

/* Size of range_buffer */
__u32 range_buffer_size;

/* Start index to read from */
__u32 start_index;

/*
* End index to read to. 0 means read to end. This is a range,
* so incfs will read from start_index to end_index - 1
*/
__u32 end_index;

/* Actual number of blocks in file */
__u32 total_blocks_out;

/* The number of data blocks in file */
__u32 data_blocks_out;

/* Number of bytes written to range buffer */
__u32 range_buffer_size_out;

/* Sector scanned up to, if the call was interrupted */
__u32 index_out;
};

/*
* Create a new mapped file
* Argument for INCFS_IOC_CREATE_MAPPED_FILE
*/
struct incfs_create_mapped_file_args {
/*
* Total size of the new file.
*/
__aligned_u64 size;

/*
* File mode. Permissions and dir flag.
*/
__u16 mode;

__u16 reserved1;

__u32 reserved2;

/*
* A pointer to a null-terminated relative path to the incfs mount
* point
* Max length: PATH_MAX
*
* Equivalent to: char *directory_path;
*/
__aligned_u64 directory_path;

/*
* A pointer to a null-terminated file name.
* Max length: PATH_MAX
*
* Equivalent to: char *file_name;
*/
__aligned_u64 file_name;

/* Id of source file to map. */
incfs_uuid_t source_file_id;

/*
* Offset in source file to start mapping. Must be a multiple of
* INCFS_DATA_FILE_BLOCK_SIZE
*/
__aligned_u64 source_offset;
};

/*
* Get information about the blocks in this file
* Argument for INCFS_IOC_GET_BLOCK_COUNT
*/
struct incfs_get_block_count_args {
/* Total number of data blocks in the file */
__u32 total_data_blocks_out;

/* Number of filled data blocks in the file */
__u32 filled_data_blocks_out;

/* Total number of hash blocks in the file */
__u32 total_hash_blocks_out;

/* Number of filled hash blocks in the file */
__u32 filled_hash_blocks_out;
};

/* Description of timeouts for one UID */
struct incfs_per_uid_read_timeouts {
/* UID to apply these timeouts to */
__u32 uid;

/*
* Min time in microseconds to read any block. Note that this doesn't
* apply to reads which are satisfied from the page cache.
*/
__u32 min_time_us;

/*
* Min time in microseconds to satisfy a pending read. Any pending read
* which is filled before this time will be delayed so that the total
* read time >= this value.
*/
__u32 min_pending_time_us;

/*
* Max time in microseconds to satisfy a pending read before the read
* times out. If set to U32_MAX, defaults to mount options
* read_timeout_ms * 1000. Must be >= min_pending_time_us
*/
__u32 max_pending_time_us;
};

/*
* Get the read timeouts array
* Argument for INCFS_IOC_GET_READ_TIMEOUTS
*/
struct incfs_get_read_timeouts_args {
/*
* A pointer to a buffer to fill with the current timeouts
*
* Equivalent to struct incfs_per_uid_read_timeouts *
*/
__aligned_u64 timeouts_array;

/* Size of above buffer in bytes */
__u32 timeouts_array_size;

/* Size used in bytes, or size needed if -ENOMEM returned */
__u32 timeouts_array_size_out;
};

/*
* Set the read timeouts array
* Arguments for INCFS_IOC_SET_READ_TIMEOUTS
*/
struct incfs_set_read_timeouts_args {
/*
* A pointer to an array containing the new timeouts
* This will replace any existing timeouts
*
* Equivalent to struct incfs_per_uid_read_timeouts *
*/
__aligned_u64 timeouts_array;

/* Size of above array in bytes. Must be < 256 */
__u32 timeouts_array_size;
};

/*
* Get last read error struct
* Arguments for INCFS_IOC_GET_LAST_READ_ERROR
*/
struct incfs_get_last_read_error_args {
/* File id of last file that had a read error */
incfs_uuid_t	file_id_out;

/* Time of last read error, in us, from CLOCK_MONOTONIC */
__u64	time_us_out;

/* Index of page that was being read at last read error */
__u32	page_out;

/* errno of last read error */
__u32	errno_out;

/* uid of last read error */
__u32	uid_out;

__u32	reserved1;
__u64	reserved2;
};

#endif /* _UAPI_LINUX_INCREMENTALFS_H */