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