From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/verity/measure.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 fs/verity/measure.c (limited to 'fs/verity/measure.c') diff --git a/fs/verity/measure.c b/fs/verity/measure.c new file mode 100644 index 000000000..e99c00350 --- /dev/null +++ b/fs/verity/measure.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Ioctl to get a verity file's digest + * + * Copyright 2019 Google LLC + */ + +#include "fsverity_private.h" + +#include + +/** + * fsverity_ioctl_measure() - get a verity file's digest + * @filp: file to get digest of + * @_uarg: user pointer to fsverity_digest + * + * Retrieve the file digest 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->file_digest, hash_alg->digest_size)) + return -EFAULT; + + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); + +/** + * fsverity_get_digest() - get a verity file's digest + * @inode: inode to get digest of + * @digest: (out) pointer to the digest + * @alg: (out) pointer to the hash algorithm enumeration + * + * Return the file hash algorithm and digest of an fsverity protected file. + * Assumption: before calling fsverity_get_digest(), the file must have been + * opened. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_get_digest(struct inode *inode, + u8 digest[FS_VERITY_MAX_DIGEST_SIZE], + enum hash_algo *alg) +{ + const struct fsverity_info *vi; + const struct fsverity_hash_alg *hash_alg; + int i; + + vi = fsverity_get_info(inode); + if (!vi) + return -ENODATA; /* not a verity file */ + + hash_alg = vi->tree_params.hash_alg; + memset(digest, 0, FS_VERITY_MAX_DIGEST_SIZE); + + /* convert the verity hash algorithm name to a hash_algo_name enum */ + i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name); + if (i < 0) + return -EINVAL; + *alg = i; + + if (WARN_ON_ONCE(hash_alg->digest_size != hash_digest_size[*alg])) + return -EINVAL; + memcpy(digest, vi->file_digest, hash_alg->digest_size); + + pr_debug("file digest %s:%*phN\n", hash_algo_name[*alg], + hash_digest_size[*alg], digest); + + return 0; +} -- cgit v1.2.3