LXR linux/include/uapi/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 _UAPI_LINUX_FSVERITY_H
  11#define _UAPI_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
  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 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 */
  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#else
  55        __le32 __reserved_0x04; /* must be 0 */
  56#endif
  57        __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#endif
  64};
  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 bytes
  69 * are prepended to provide some context about what is being signed in case the
  70 * same key is used for non-fsverity purposes, and here the fields have fixed
  71 * endianness.
  72 *
  73 * This struct is specific to the built-in signature verification support, which
  74 * is optional.  fs-verity users may also verify signatures in userspace, in
  75 * 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     1
  87#define FS_VERITY_METADATA_TYPE_DESCRIPTOR      2
  88#define FS_VERITY_METADATA_TYPE_SIGNATURE       3
  89
  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