fs-verity: rename "file measurement" to "file digest"

I originally chose the name "file measurement" to refer to the fs-verity
file digest to avoid confusion with traditional full-file digests or
with the bare root hash of the Merkle tree.

But the name "file measurement" hasn't caught on, and usually people are
calling it something else, usually the "file digest".  E.g. see
"struct fsverity_digest" and "struct fsverity_formatted_digest", the
libfsverity_compute_digest() and libfsverity_sign_digest() functions in
libfsverity, and the "fsverity digest" command.

Having multiple names for the same thing is always confusing.

So to hopefully avoid confusion in the future, rename
"fs-verity file measurement" to "fs-verity file digest".

This leaves FS_IOC_MEASURE_VERITY as the only reference to "measure" in
the kernel, which makes some amount of sense since the ioctl is actively
"measuring" the file.

I'll be renaming this in fsverity-utils too (though similarly the
'fsverity measure' command, which is a wrapper for
FS_IOC_MEASURE_VERITY, will stay).

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113211918.71883-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/verity/signature.c b/fs/verity/signature.c
index 74ae10f04d21..012468eda2a7 100644
--- a/fs/verity/signature.c
+++ b/fs/verity/signature.c
@@ -32,8 +32,8 @@ static struct key *fsverity_keyring;
  * @desc: the file's fsverity_descriptor
  * @desc_size: size of @desc
  *
- * If the file's fs-verity descriptor includes a signature of the file
- * measurement, verify it against the certificates in the fs-verity keyring.
+ * If the file's fs-verity descriptor includes a signature of the file digest,
+ * verify it against the certificates in the fs-verity keyring.
  *
  * Return: 0 on success (signature valid or not required); -errno on failure
  */
@@ -67,7 +67,7 @@ int fsverity_verify_signature(const struct fsverity_info *vi,
 	memcpy(d->magic, "FSVerity", 8);
 	d->digest_algorithm = cpu_to_le16(hash_alg - fsverity_hash_algs);
 	d->digest_size = cpu_to_le16(hash_alg->digest_size);
-	memcpy(d->digest, vi->measurement, hash_alg->digest_size);
+	memcpy(d->digest, vi->file_digest, hash_alg->digest_size);
 
 	err = verify_pkcs7_signature(d, sizeof(*d) + hash_alg->digest_size,
 				     desc->signature, sig_size,
@@ -90,8 +90,8 @@ int fsverity_verify_signature(const struct fsverity_info *vi,
 		return err;
 	}
 
-	pr_debug("Valid signature for file measurement %s:%*phN\n",
-		 hash_alg->name, hash_alg->digest_size, vi->measurement);
+	pr_debug("Valid signature for file digest %s:%*phN\n",
+		 hash_alg->name, hash_alg->digest_size, vi->file_digest);
 	return 0;
 }