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ed45e20164
I originally chose the name "file measurement" to refer to the fs-verity file digest to avoid confusion with traditional full-file digests or with the bare root hash of the Merkle tree. But the name "file measurement" hasn't caught on, and usually people are calling it something else, usually the "file digest". E.g. see "struct fsverity_digest" and "struct fsverity_formatted_digest", the libfsverity_compute_digest() and libfsverity_sign_digest() functions in libfsverity, and the "fsverity digest" command. Having multiple names for the same thing is always confusing. So to hopefully avoid confusion in the future, rename "fs-verity file measurement" to "fs-verity file digest". This leaves FS_IOC_MEASURE_VERITY as the only reference to "measure" in the kernel, which makes some amount of sense since the ioctl is actively "measuring" the file. I'll be renaming this in fsverity-utils too (though similarly the 'fsverity measure' command, which is a wrapper for FS_IOC_MEASURE_VERITY, will stay). Acked-by: Luca Boccassi <luca.boccassi@microsoft.com> Link: https://lore.kernel.org/r/20201113211918.71883-4-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>
60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Ioctl to get a verity file's digest
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*
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* Copyright 2019 Google LLC
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*/
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#include "fsverity_private.h"
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#include <linux/uaccess.h>
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/**
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* fsverity_ioctl_measure() - get a verity file's digest
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* @filp: file to get digest of
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* @_uarg: user pointer to fsverity_digest
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*
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* Retrieve the file digest that the kernel is enforcing for reads from a verity
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* file. See the "FS_IOC_MEASURE_VERITY" section of
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* Documentation/filesystems/fsverity.rst for the documentation.
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*
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* Return: 0 on success, -errno on failure
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*/
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int fsverity_ioctl_measure(struct file *filp, void __user *_uarg)
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{
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const struct inode *inode = file_inode(filp);
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struct fsverity_digest __user *uarg = _uarg;
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const struct fsverity_info *vi;
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const struct fsverity_hash_alg *hash_alg;
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struct fsverity_digest arg;
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vi = fsverity_get_info(inode);
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if (!vi)
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return -ENODATA; /* not a verity file */
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hash_alg = vi->tree_params.hash_alg;
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/*
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* The user specifies the digest_size their buffer has space for; we can
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* return the digest if it fits in the available space. We write back
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* the actual size, which may be shorter than the user-specified size.
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*/
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if (get_user(arg.digest_size, &uarg->digest_size))
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return -EFAULT;
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if (arg.digest_size < hash_alg->digest_size)
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return -EOVERFLOW;
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memset(&arg, 0, sizeof(arg));
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arg.digest_algorithm = hash_alg - fsverity_hash_algs;
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arg.digest_size = hash_alg->digest_size;
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if (copy_to_user(uarg, &arg, sizeof(arg)))
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return -EFAULT;
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if (copy_to_user(uarg->digest, vi->file_digest, hash_alg->digest_size))
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return -EFAULT;
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return 0;
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}
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EXPORT_SYMBOL_GPL(fsverity_ioctl_measure);
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