/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* fs-verity user API
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*
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* These ioctls can be used on filesystems that support fs-verity. See the
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* "User API" section of Documentation/filesystems/fsverity.rst.
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*
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* Copyright 2019 Google LLC
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*/
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#ifndef _UAPI_LINUX_FSVERITY_H
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#define _UAPI_LINUX_FSVERITY_H
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#include <linux/ioctl.h>
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#include <linux/types.h>
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#define FS_VERITY_HASH_ALG_SHA256 1
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#define FS_VERITY_HASH_ALG_SHA512 2
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struct fsverity_enable_arg {
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__u32 version;
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__u32 hash_algorithm;
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__u32 block_size;
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__u32 salt_size;
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__u64 salt_ptr;
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__u32 sig_size;
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__u32 __reserved1;
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__u64 sig_ptr;
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__u64 __reserved2[11];
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};
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struct fsverity_digest {
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__u16 digest_algorithm;
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__u16 digest_size; /* input/output */
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__u8 digest[];
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};
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/*
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* Struct containing a file's Merkle tree properties. The fs-verity file digest
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* is the hash of this struct. A userspace program needs this struct only if it
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* needs to compute fs-verity file digests itself, e.g. in order to sign files.
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* It isn't needed just to enable fs-verity on a file.
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*
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* Note: when computing the file digest, 'sig_size' and 'signature' must be left
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* zero and empty, respectively. These fields are present only because some
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* filesystems reuse this struct as part of their on-disk format.
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*/
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struct fsverity_descriptor {
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__u8 version; /* must be 1 */
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__u8 hash_algorithm; /* Merkle tree hash algorithm */
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__u8 log_blocksize; /* log2 of size of data and tree blocks */
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__u8 salt_size; /* size of salt in bytes; 0 if none */
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#ifdef __KERNEL__
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__le32 sig_size;
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#else
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__le32 __reserved_0x04; /* must be 0 */
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#endif
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__le64 data_size; /* size of file the Merkle tree is built over */
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__u8 root_hash[64]; /* Merkle tree root hash */
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__u8 salt[32]; /* salt prepended to each hashed block */
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__u8 __reserved[144]; /* must be 0's */
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#ifdef __KERNEL__
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__u8 signature[];
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#endif
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};
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/*
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* Format in which fs-verity file digests are signed in built-in signatures.
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* This is the same as 'struct fsverity_digest', except here some magic bytes
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* are prepended to provide some context about what is being signed in case the
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* same key is used for non-fsverity purposes, and here the fields have fixed
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* endianness.
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*
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* This struct is specific to the built-in signature verification support, which
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* is optional. fs-verity users may also verify signatures in userspace, in
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* which case userspace is responsible for deciding on what bytes are signed.
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* This struct may still be used, but it doesn't have to be. For example,
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* userspace could instead use a string like "sha256:$digest_as_hex_string".
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*/
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struct fsverity_formatted_digest {
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char magic[8]; /* must be "FSVerity" */
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__le16 digest_algorithm;
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__le16 digest_size;
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__u8 digest[];
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};
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#define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1
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#define FS_VERITY_METADATA_TYPE_DESCRIPTOR 2
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#define FS_VERITY_METADATA_TYPE_SIGNATURE 3
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struct fsverity_read_metadata_arg {
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__u64 metadata_type;
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__u64 offset;
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__u64 length;
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__u64 buf_ptr;
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__u64 __reserved;
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};
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#define FS_IOC_ENABLE_VERITY _IOW('f', 133, struct fsverity_enable_arg)
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#define FS_IOC_MEASURE_VERITY _IOWR('f', 134, struct fsverity_digest)
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#define FS_IOC_READ_VERITY_METADATA \
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_IOWR('f', 135, struct fsverity_read_metadata_arg)
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#endif /* _UAPI_LINUX_FSVERITY_H */
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