VisionFive2 Linux kernel

4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  1) // SPDX-License-Identifier: GPL-2.0
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  2) /*
ed45e20164934 (Eric Biggers 2020-11-13 13:19:17 -0800  3)  * Ioctl to get a verity file's digest
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  4)  *
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  5)  * Copyright 2019 Google LLC
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  6)  */
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  7) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  8) #include "fsverity_private.h"
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700  9) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 10) #include <linux/uaccess.h>
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 11) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 12) /**
ed45e20164934 (Eric Biggers 2020-11-13 13:19:17 -0800 13)  * fsverity_ioctl_measure() - get a verity file's digest
ed45e20164934 (Eric Biggers 2020-11-13 13:19:17 -0800 14)  * @filp: file to get digest of
6377a38bd345b (Eric Biggers 2020-05-11 12:21:17 -0700 15)  * @_uarg: user pointer to fsverity_digest
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 16)  *
ed45e20164934 (Eric Biggers 2020-11-13 13:19:17 -0800 17)  * Retrieve the file digest that the kernel is enforcing for reads from a verity
ed45e20164934 (Eric Biggers 2020-11-13 13:19:17 -0800 18)  * file.  See the "FS_IOC_MEASURE_VERITY" section of
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 19)  * Documentation/filesystems/fsverity.rst for the documentation.
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 20)  *
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 21)  * Return: 0 on success, -errno on failure
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 22)  */
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 23) int fsverity_ioctl_measure(struct file *filp, void __user *_uarg)
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 24) {
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 25) 	const struct inode *inode = file_inode(filp);
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 26) 	struct fsverity_digest __user *uarg = _uarg;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 27) 	const struct fsverity_info *vi;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 28) 	const struct fsverity_hash_alg *hash_alg;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 29) 	struct fsverity_digest arg;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 30) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 31) 	vi = fsverity_get_info(inode);
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 32) 	if (!vi)
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 33) 		return -ENODATA; /* not a verity file */
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 34) 	hash_alg = vi->tree_params.hash_alg;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 35) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 36) 	/*
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 37) 	 * The user specifies the digest_size their buffer has space for; we can
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 38) 	 * return the digest if it fits in the available space.  We write back
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 39) 	 * the actual size, which may be shorter than the user-specified size.
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 40) 	 */
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 41) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 42) 	if (get_user(arg.digest_size, &uarg->digest_size))
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 43) 		return -EFAULT;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 44) 	if (arg.digest_size < hash_alg->digest_size)
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 45) 		return -EOVERFLOW;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 46) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 47) 	memset(&arg, 0, sizeof(arg));
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 48) 	arg.digest_algorithm = hash_alg - fsverity_hash_algs;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 49) 	arg.digest_size = hash_alg->digest_size;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 50) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 51) 	if (copy_to_user(uarg, &arg, sizeof(arg)))
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 52) 		return -EFAULT;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 53) 
ed45e20164934 (Eric Biggers 2020-11-13 13:19:17 -0800 54) 	if (copy_to_user(uarg->digest, vi->file_digest, hash_alg->digest_size))
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 55) 		return -EFAULT;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 56) 
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 57) 	return 0;
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 58) }
4dd893d832cf4 (Eric Biggers 2019-07-22 09:26:23 -0700 59) EXPORT_SYMBOL_GPL(fsverity_ioctl_measure);