1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux 1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 /* 2 /*
3 * fs-verity user API 3 * fs-verity user API
4 * 4 *
5 * These ioctls can be used on filesystems tha 5 * These ioctls can be used on filesystems that support fs-verity. See the
6 * "User API" section of Documentation/filesys 6 * "User API" section of Documentation/filesystems/fsverity.rst.
7 * 7 *
8 * Copyright 2019 Google LLC 8 * Copyright 2019 Google LLC
9 */ 9 */
10 #ifndef _UAPI_LINUX_FSVERITY_H 10 #ifndef _UAPI_LINUX_FSVERITY_H
11 #define _UAPI_LINUX_FSVERITY_H 11 #define _UAPI_LINUX_FSVERITY_H
12 12
13 #include <linux/ioctl.h> 13 #include <linux/ioctl.h>
14 #include <linux/types.h> 14 #include <linux/types.h>
15 15
16 #define FS_VERITY_HASH_ALG_SHA256 1 16 #define FS_VERITY_HASH_ALG_SHA256 1
17 #define FS_VERITY_HASH_ALG_SHA512 2 17 #define FS_VERITY_HASH_ALG_SHA512 2
18 18
19 struct fsverity_enable_arg { 19 struct fsverity_enable_arg {
20 __u32 version; 20 __u32 version;
21 __u32 hash_algorithm; 21 __u32 hash_algorithm;
22 __u32 block_size; 22 __u32 block_size;
23 __u32 salt_size; 23 __u32 salt_size;
24 __u64 salt_ptr; 24 __u64 salt_ptr;
25 __u32 sig_size; 25 __u32 sig_size;
26 __u32 __reserved1; 26 __u32 __reserved1;
27 __u64 sig_ptr; 27 __u64 sig_ptr;
28 __u64 __reserved2[11]; 28 __u64 __reserved2[11];
29 }; 29 };
30 30
31 struct fsverity_digest { 31 struct fsverity_digest {
32 __u16 digest_algorithm; 32 __u16 digest_algorithm;
33 __u16 digest_size; /* input/output */ 33 __u16 digest_size; /* input/output */
34 __u8 digest[]; 34 __u8 digest[];
35 }; 35 };
36 36
37 /* 37 /*
38 * Struct containing a file's Merkle tree prop 38 * Struct containing a file's Merkle tree properties. The fs-verity file digest
39 * is the hash of this struct. A userspace pr 39 * is the hash of this struct. A userspace program needs this struct only if it
40 * needs to compute fs-verity file digests its 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 41 * It isn't needed just to enable fs-verity on a file.
42 * 42 *
43 * Note: when computing the file digest, 'sig_ 43 * Note: when computing the file digest, 'sig_size' and 'signature' must be left
44 * zero and empty, respectively. These fields 44 * zero and empty, respectively. These fields are present only because some
45 * filesystems reuse this struct as part of th 45 * filesystems reuse this struct as part of their on-disk format.
46 */ 46 */
47 struct fsverity_descriptor { 47 struct fsverity_descriptor {
48 __u8 version; /* must be 1 * 48 __u8 version; /* must be 1 */
49 __u8 hash_algorithm; /* Merkle tree 49 __u8 hash_algorithm; /* Merkle tree hash algorithm */
50 __u8 log_blocksize; /* log2 of siz 50 __u8 log_blocksize; /* log2 of size of data and tree blocks */
51 __u8 salt_size; /* size of sal 51 __u8 salt_size; /* size of salt in bytes; 0 if none */
52 #ifdef __KERNEL__ 52 #ifdef __KERNEL__
53 __le32 sig_size; 53 __le32 sig_size;
54 #else 54 #else
55 __le32 __reserved_0x04; /* must be 0 * 55 __le32 __reserved_0x04; /* must be 0 */
56 #endif 56 #endif
57 __le64 data_size; /* size of fil 57 __le64 data_size; /* size of file the Merkle tree is built over */
58 __u8 root_hash[64]; /* Merkle tree 58 __u8 root_hash[64]; /* Merkle tree root hash */
59 __u8 salt[32]; /* salt prepen 59 __u8 salt[32]; /* salt prepended to each hashed block */
60 __u8 __reserved[144]; /* must be 0's 60 __u8 __reserved[144]; /* must be 0's */
61 #ifdef __KERNEL__ 61 #ifdef __KERNEL__
62 __u8 signature[]; 62 __u8 signature[];
63 #endif 63 #endif
64 }; 64 };
65 65
66 /* 66 /*
67 * Format in which fs-verity file digests are 67 * Format in which fs-verity file digests are signed in built-in signatures.
68 * This is the same as 'struct fsverity_digest 68 * This is the same as 'struct fsverity_digest', except here some magic bytes
69 * are prepended to provide some context about 69 * are prepended to provide some context about what is being signed in case the
70 * same key is used for non-fsverity purposes, 70 * same key is used for non-fsverity purposes, and here the fields have fixed
71 * endianness. 71 * endianness.
72 * 72 *
73 * This struct is specific to the built-in sig 73 * This struct is specific to the built-in signature verification support, which
74 * is optional. fs-verity users may also veri 74 * is optional. fs-verity users may also verify signatures in userspace, in
75 * which case userspace is responsible for dec 75 * which case userspace is responsible for deciding on what bytes are signed.
76 * This struct may still be used, but it doesn 76 * This struct may still be used, but it doesn't have to be. For example,
77 * userspace could instead use a string like " 77 * userspace could instead use a string like "sha256:$digest_as_hex_string".
78 */ 78 */
79 struct fsverity_formatted_digest { 79 struct fsverity_formatted_digest {
80 char magic[8]; /* mus 80 char magic[8]; /* must be "FSVerity" */
81 __le16 digest_algorithm; 81 __le16 digest_algorithm;
82 __le16 digest_size; 82 __le16 digest_size;
83 __u8 digest[]; 83 __u8 digest[];
84 }; 84 };
85 85
86 #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 86 #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1
87 #define FS_VERITY_METADATA_TYPE_DESCRIPTOR 87 #define FS_VERITY_METADATA_TYPE_DESCRIPTOR 2
88 #define FS_VERITY_METADATA_TYPE_SIGNATURE 88 #define FS_VERITY_METADATA_TYPE_SIGNATURE 3
89 89
90 struct fsverity_read_metadata_arg { 90 struct fsverity_read_metadata_arg {
91 __u64 metadata_type; 91 __u64 metadata_type;
92 __u64 offset; 92 __u64 offset;
93 __u64 length; 93 __u64 length;
94 __u64 buf_ptr; 94 __u64 buf_ptr;
95 __u64 __reserved; 95 __u64 __reserved;
96 }; 96 };
97 97
98 #define FS_IOC_ENABLE_VERITY _IOW('f', 133, 98 #define FS_IOC_ENABLE_VERITY _IOW('f', 133, struct fsverity_enable_arg)
99 #define FS_IOC_MEASURE_VERITY _IOWR('f', 134 99 #define FS_IOC_MEASURE_VERITY _IOWR('f', 134, struct fsverity_digest)
100 #define FS_IOC_READ_VERITY_METADATA \ 100 #define FS_IOC_READ_VERITY_METADATA \
101 _IOWR('f', 135, struct fsverity_read_m 101 _IOWR('f', 135, struct fsverity_read_metadata_arg)
102 102
103 #endif /* _UAPI_LINUX_FSVERITY_H */ 103 #endif /* _UAPI_LINUX_FSVERITY_H */
104 104
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