[mirror_ubuntu-jammy-kernel.git] / fs / verity / measure.c

// SPDX-License-Identifier: GPL-2.0
/*
 * fs/verity/measure.c: ioctl to get a verity file's measurement
 *
 * Copyright 2019 Google LLC
 */

#include "fsverity_private.h"

#include <linux/uaccess.h>

/**
 * fsverity_ioctl_measure() - get a verity file's measurement
 *
 * Retrieve the file measurement that the kernel is enforcing for reads from a
 * verity file.  See the "FS_IOC_MEASURE_VERITY" section of
 * Documentation/filesystems/fsverity.rst for the documentation.
 *
 * Return: 0 on success, -errno on failure
 */
int fsverity_ioctl_measure(struct file *filp, void __user *_uarg)
{
	const struct inode *inode = file_inode(filp);
	struct fsverity_digest __user *uarg = _uarg;
	const struct fsverity_info *vi;
	const struct fsverity_hash_alg *hash_alg;
	struct fsverity_digest arg;

	vi = fsverity_get_info(inode);
	if (!vi)
		return -ENODATA; /* not a verity file */
	hash_alg = vi->tree_params.hash_alg;

	/*
	 * The user specifies the digest_size their buffer has space for; we can
	 * return the digest if it fits in the available space.  We write back
	 * the actual size, which may be shorter than the user-specified size.
	 */

	if (get_user(arg.digest_size, &uarg->digest_size))
		return -EFAULT;
	if (arg.digest_size < hash_alg->digest_size)
		return -EOVERFLOW;

	memset(&arg, 0, sizeof(arg));
	arg.digest_algorithm = hash_alg - fsverity_hash_algs;
	arg.digest_size = hash_alg->digest_size;

	if (copy_to_user(uarg, &arg, sizeof(arg)))
		return -EFAULT;

	if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size))
		return -EFAULT;

	return 0;
}
EXPORT_SYMBOL_GPL(fsverity_ioctl_measure);
Commit	Line	Data
4dd893d8 EB	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* fs/verity/measure.c: ioctl to get a verity file's measurement
	4	*
	5	* Copyright 2019 Google LLC
	6	*/
	7
	8	#include "fsverity_private.h"
	9
	10	#include <linux/uaccess.h>
	11
	12	/**
	13	* fsverity_ioctl_measure() - get a verity file's measurement
	14	*
	15	* Retrieve the file measurement that the kernel is enforcing for reads from a
	16	* verity file. See the "FS_IOC_MEASURE_VERITY" section of
	17	* Documentation/filesystems/fsverity.rst for the documentation.
	18	*
	19	* Return: 0 on success, -errno on failure
	20	*/
	21	int fsverity_ioctl_measure(struct file filp, void __user _uarg)
	22	{
	23	const struct inode *inode = file_inode(filp);
	24	struct fsverity_digest __user *uarg = _uarg;
	25	const struct fsverity_info *vi;
	26	const struct fsverity_hash_alg *hash_alg;
	27	struct fsverity_digest arg;
	28
	29	vi = fsverity_get_info(inode);
	30	if (!vi)
	31	return -ENODATA; /* not a verity file */
	32	hash_alg = vi->tree_params.hash_alg;
	33
	34	/*
	35	* The user specifies the digest_size their buffer has space for; we can
	36	* return the digest if it fits in the available space. We write back
	37	* the actual size, which may be shorter than the user-specified size.
	38	*/
	39
	40	if (get_user(arg.digest_size, &uarg->digest_size))
	41	return -EFAULT;
	42	if (arg.digest_size < hash_alg->digest_size)
	43	return -EOVERFLOW;
	44
	45	memset(&arg, 0, sizeof(arg));
	46	arg.digest_algorithm = hash_alg - fsverity_hash_algs;
	47	arg.digest_size = hash_alg->digest_size;
	48
	49	if (copy_to_user(uarg, &arg, sizeof(arg)))
	50	return -EFAULT;
	51
	52	if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size))
	53	return -EFAULT;
	54
	55	return 0;
	56	}
	57	EXPORT_SYMBOL_GPL(fsverity_ioctl_measure);