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 | |
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 | #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 | */ |
79 | struct 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 | |
90 | struct 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 | |