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1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */2/*3 * fs-verity user API4 *5 * These ioctls can be used on filesystems that support fs-verity. See the6 * "User API" section of Documentation/filesystems/fsverity.rst.7 *8 * Copyright 2019 Google LLC9 */10#ifndef _UAPI_LINUX_FSVERITY_H11#define _UAPI_LINUX_FSVERITY_H12 13#include <linux/ioctl.h>14#include <linux/types.h>15 16#define FS_VERITY_HASH_ALG_SHA256 117#define FS_VERITY_HASH_ALG_SHA512 218 19struct 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 31struct 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 digest39 * is the hash of this struct. A userspace program needs this struct only if it40 * 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 left44 * zero and empty, respectively. These fields are present only because some45 * filesystems reuse this struct as part of their on-disk format.46 */47struct 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#ifdef __KERNEL__53 __le32 sig_size;54#else55 __le32 __reserved_0x04; /* must be 0 */56#endif57 __le64 data_size; /* size of file the Merkle tree is built over */58 __u8 root_hash[64]; /* Merkle tree root hash */59 __u8 salt[32]; /* salt prepended to each hashed block */60 __u8 __reserved[144]; /* must be 0's */61#ifdef __KERNEL__62 __u8 signature[];63#endif64};65 66/*67 * Format in which fs-verity file digests are signed in built-in signatures.68 * This is the same as 'struct fsverity_digest', except here some magic bytes69 * are prepended to provide some context about what is being signed in case the70 * same key is used for non-fsverity purposes, and here the fields have fixed71 * endianness.72 *73 * This struct is specific to the built-in signature verification support, which74 * is optional. fs-verity users may also verify signatures in userspace, in75 * which case userspace is responsible for deciding on what bytes are signed.76 * This struct may still be used, but it doesn't have to be. For example,77 * userspace could instead use a string like "sha256:$digest_as_hex_string".78 */79struct fsverity_formatted_digest {80 char magic[8]; /* must be "FSVerity" */81 __le16 digest_algorithm;82 __le16 digest_size;83 __u8 digest[];84};85 86#define FS_VERITY_METADATA_TYPE_MERKLE_TREE 187#define FS_VERITY_METADATA_TYPE_DESCRIPTOR 288#define FS_VERITY_METADATA_TYPE_SIGNATURE 389 90struct fsverity_read_metadata_arg {91 __u64 metadata_type;92 __u64 offset;93 __u64 length;94 __u64 buf_ptr;95 __u64 __reserved;96};97 98#define FS_IOC_ENABLE_VERITY _IOW('f', 133, struct fsverity_enable_arg)99#define FS_IOC_MEASURE_VERITY _IOWR('f', 134, struct fsverity_digest)100#define FS_IOC_READ_VERITY_METADATA \101 _IOWR('f', 135, struct fsverity_read_metadata_arg)102 103#endif /* _UAPI_LINUX_FSVERITY_H */104