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59 lines
1.6 KiB
59 lines
1.6 KiB
// 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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