Mimi, On Sun, Jan 09, 2022 at 01:55:13PM -0500, Mimi Zohar wrote: > Define a function named fsverity_get_digest() to return the verity file > digest and the associated hash algorithm (enum hash_algo). > > Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx> > --- > fs/verity/Kconfig | 1 + > fs/verity/fsverity_private.h | 7 ------- > fs/verity/measure.c | 40 ++++++++++++++++++++++++++++++++++++ > include/linux/fsverity.h | 18 ++++++++++++++++ > 4 files changed, 59 insertions(+), 7 deletions(-) > > diff --git a/fs/verity/measure.c b/fs/verity/measure.c > index f0d7b30c62db..52906b2e5811 100644 > --- a/fs/verity/measure.c > +++ b/fs/verity/measure.c > @@ -57,3 +57,43 @@ int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) > 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. > + * > + * 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); > + *alg = HASH_ALGO__LAST; Perhaps this line is redundant (*alg is overwritten later) and would needlessly mangle output value in case of -EINVAL while it's being untouched on -ENODATA. Thanks, > + > + /* convert hash algorithm to hash_algo_name */ > + i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name); > + if (i < 0) > + return -EINVAL; > + *alg = i; > + > + 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; > +}
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