Where Online Learning is simpler!

The C and C++ Include Header Files

/usr/include/linux/fsverity.h


$ cat -n /usr/include/linux/fsverity.h

     1	/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
     2	/*
     3	 * fs-verity user API
     4	 *
     5	 * These ioctls can be used on filesystems that support fs-verity.  See the
     6	 * "User API" section of Documentation/filesystems/fsverity.rst.
     7	 *
     8	 * Copyright 2019 Google LLC
     9	 */
    10	#ifndef _LINUX_FSVERITY_H
    11	#define _LINUX_FSVERITY_H
    12	
    13	#include <linux/ioctl.h>
    14	#include <linux/types.h>
    15	
    16	#define FS_VERITY_HASH_ALG_SHA256	1
    17	#define FS_VERITY_HASH_ALG_SHA512	2
    18	
    19	struct fsverity_enable_arg {
    20		__u32 version;
    21		__u32 hash_algorithm;
    22		__u32 block_size;
    23		__u32 salt_size;
    24		__u64 salt_ptr;
    25		__u32 sig_size;
    26		__u32 __reserved1;
    27		__u64 sig_ptr;
    28		__u64 __reserved2[11];
    29	};
    30	
    31	struct fsverity_digest {
    32		__u16 digest_algorithm;
    33		__u16 digest_size; /* input/output */
    34		__u8 digest[];
    35	};
    36	
    37	/*
    38	 * Struct containing a file's Merkle tree properties.  The fs-verity file digest
    39	 * is the hash of this struct.  A userspace program needs this struct only if it
    40	 * needs to compute fs-verity file digests itself, e.g. in order to sign files.
    41	 * It isn't needed just to enable fs-verity on a file.
    42	 *
    43	 * Note: when computing the file digest, 'sig_size' and 'signature' must be left
    44	 * zero and empty, respectively.  These fields are present only because some
    45	 * filesystems reuse this struct as part of their on-disk format.
    46	 */
    47	struct fsverity_descriptor {
    48		__u8 version;		/* must be 1 */
    49		__u8 hash_algorithm;	/* Merkle tree hash algorithm */
    50		__u8 log_blocksize;	/* log2 of size of data and tree blocks */
    51		__u8 salt_size;		/* size of salt in bytes; 0 if none */
    52		__le32 __reserved_0x04;	/* must be 0 */
    53		__le64 data_size;	/* size of file the Merkle tree is built over */
    54		__u8 root_hash[64];	/* Merkle tree root hash */
    55		__u8 salt[32];		/* salt prepended to each hashed block */
    56		__u8 __reserved[144];	/* must be 0's */
    57	};
    58	
    59	/*
    60	 * Format in which fs-verity file digests are signed in built-in signatures.
    61	 * This is the same as 'struct fsverity_digest', except here some magic bytes
    62	 * are prepended to provide some context about what is being signed in case the
    63	 * same key is used for non-fsverity purposes, and here the fields have fixed
    64	 * endianness.
    65	 *
    66	 * This struct is specific to the built-in signature verification support, which
    67	 * is optional.  fs-verity users may also verify signatures in userspace, in
    68	 * which case userspace is responsible for deciding on what bytes are signed.
    69	 * This struct may still be used, but it doesn't have to be.  For example,
    70	 * userspace could instead use a string like "sha256:$digest_as_hex_string".
    71	 */
    72	struct fsverity_formatted_digest {
    73		char magic[8];			/* must be "FSVerity" */
    74		__le16 digest_algorithm;
    75		__le16 digest_size;
    76		__u8 digest[];
    77	};
    78	
    79	#define FS_VERITY_METADATA_TYPE_MERKLE_TREE	1
    80	#define FS_VERITY_METADATA_TYPE_DESCRIPTOR	2
    81	#define FS_VERITY_METADATA_TYPE_SIGNATURE	3
    82	
    83	struct fsverity_read_metadata_arg {
    84		__u64 metadata_type;
    85		__u64 offset;
    86		__u64 length;
    87		__u64 buf_ptr;
    88		__u64 __reserved;
    89	};
    90	
    91	#define FS_IOC_ENABLE_VERITY	_IOW('f', 133, struct fsverity_enable_arg)
    92	#define FS_IOC_MEASURE_VERITY	_IOWR('f', 134, struct fsverity_digest)
    93	#define FS_IOC_READ_VERITY_METADATA \
    94		_IOWR('f', 135, struct fsverity_read_metadata_arg)
    95	
    96	#endif /* _LINUX_FSVERITY_H */