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 #ifndef _WIN32 14 #include <linux/ioctl.h> 15 #include <linux/types.h> 16 #endif /* !_WIN32 */ 17 18 #define FS_VERITY_HASH_ALG_SHA256 1 19 #define FS_VERITY_HASH_ALG_SHA512 2 20 21 struct fsverity_enable_arg { 22 __u32 version; 23 __u32 hash_algorithm; 24 __u32 block_size; 25 __u32 salt_size; 26 __u64 salt_ptr; 27 __u32 sig_size; 28 __u32 __reserved1; 29 __u64 sig_ptr; 30 __u64 __reserved2[11]; 31 }; 32 33 struct fsverity_digest { 34 __u16 digest_algorithm; 35 __u16 digest_size; /* input/output */ 36 __u8 digest[]; 37 }; 38 39 /* 40 * Struct containing a file's Merkle tree properties. The fs-verity file digest 41 * is the hash of this struct. A userspace program needs this struct only if it 42 * needs to compute fs-verity file digests itself, e.g. in order to sign files. 43 * It isn't needed just to enable fs-verity on a file. 44 * 45 * Note: when computing the file digest, 'sig_size' and 'signature' must be left 46 * zero and empty, respectively. These fields are present only because some 47 * filesystems reuse this struct as part of their on-disk format. 48 */ 49 struct fsverity_descriptor { 50 __u8 version; /* must be 1 */ 51 __u8 hash_algorithm; /* Merkle tree hash algorithm */ 52 __u8 log_blocksize; /* log2 of size of data and tree blocks */ 53 __u8 salt_size; /* size of salt in bytes; 0 if none */ 54 #ifdef __KERNEL__ 55 __le32 sig_size; 56 #else 57 __le32 __reserved_0x04; /* must be 0 */ 58 #endif 59 __le64 data_size; /* size of file the Merkle tree is built over */ 60 __u8 root_hash[64]; /* Merkle tree root hash */ 61 __u8 salt[32]; /* salt prepended to each hashed block */ 62 __u8 __reserved[144]; /* must be 0's */ 63 #ifdef __KERNEL__ 64 __u8 signature[]; 65 #endif 66 }; 67 68 /* 69 * Format in which fs-verity file digests are signed in built-in signatures. 70 * This is the same as 'struct fsverity_digest', except here some magic bytes 71 * are prepended to provide some context about what is being signed in case the 72 * same key is used for non-fsverity purposes, and here the fields have fixed 73 * endianness. 74 * 75 * This struct is specific to the built-in signature verification support, which 76 * is optional. fs-verity users may also verify signatures in userspace, in 77 * which case userspace is responsible for deciding on what bytes are signed. 78 * This struct may still be used, but it doesn't have to be. For example, 79 * userspace could instead use a string like "sha256:$digest_as_hex_string". 80 */ 81 struct fsverity_formatted_digest { 82 char magic[8]; /* must be "FSVerity" */ 83 __le16 digest_algorithm; 84 __le16 digest_size; 85 __u8 digest[]; 86 }; 87 88 #define FS_IOC_ENABLE_VERITY _IOW('f', 133, struct fsverity_enable_arg) 89 #define FS_IOC_MEASURE_VERITY _IOWR('f', 134, struct fsverity_digest) 90 91 #endif /* _UAPI_LINUX_FSVERITY_H */ 92