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>

5 files changed, 31 insertions, 31 deletions

diff --git a/fs/verity/enable.c b/fs/verity/enable.c
index 9c5b28c86522..f7e997a01ad0 100644
--- a/fs/verity/enable.c
+++ b/fs/verity/enable.c
@@ -398,9 +398,9 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *uarg)
 	 * Some pages of the file may have been evicted from pagecache after
 	 * being used in the Merkle tree construction, then read into pagecache
 	 * again by another process reading from the file concurrently.  Since
-	 * these pages didn't undergo verification against the file measurement
-	 * which fs-verity now claims to be enforcing, we have to wipe the
-	 * pagecache to ensure that all future reads are verified.
+	 * these pages didn't undergo verification against the file digest which
+	 * fs-verity now claims to be enforcing, we have to wipe the pagecache
+	 * to ensure that all future reads are verified.
 	 */
 	filemap_write_and_wait(inode->i_mapping);
 	invalidate_inode_pages2(inode->i_mapping);
diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h
index 75f8e18b44a5..21e9930d65fb 100644
--- a/fs/verity/fsverity_private.h
+++ b/fs/verity/fsverity_private.h
@@ -67,19 +67,19 @@ struct merkle_tree_params {
  * When a verity file is first opened, an instance of this struct is allocated
  * and stored in ->i_verity_info; it remains until the inode is evicted.  It
  * caches information about the Merkle tree that's needed to efficiently verify
- * data read from the file.  It also caches the file measurement.  The Merkle
- * tree pages themselves are not cached here, but the filesystem may cache them.
+ * data read from the file.  It also caches the file digest.  The Merkle tree
+ * pages themselves are not cached here, but the filesystem may cache them.
  */
 struct fsverity_info {
 	struct merkle_tree_params tree_params;
 	u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE];
-	u8 measurement[FS_VERITY_MAX_DIGEST_SIZE];
+	u8 file_digest[FS_VERITY_MAX_DIGEST_SIZE];
 	const struct inode *inode;
 };
 
 /*
- * Merkle tree properties.  The file measurement is the hash of this structure
- * excluding the signature and with the sig_size field set to 0.
+ * Merkle tree properties.  The fs-verity file digest is the hash of this
+ * structure excluding the signature and with the sig_size field set to 0.
  */
 struct fsverity_descriptor {
 	__u8 version;		/* must be 1 */
@@ -101,7 +101,7 @@ struct fsverity_descriptor {
 					 sizeof(struct fsverity_descriptor))
 
 /*
- * Format in which verity file measurements are signed in built-in signatures.
+ * Format in which fs-verity file digests are signed in built-in signatures.
  * This is the same as 'struct fsverity_digest', except here some magic bytes
  * are prepended to provide some context about what is being signed in case the
  * same key is used for non-fsverity purposes, and here the fields have fixed
diff --git a/fs/verity/measure.c b/fs/verity/measure.c
index 5300b8d38537..f0d7b30c62db 100644
--- a/fs/verity/measure.c
+++ b/fs/verity/measure.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Ioctl to get a verity file's measurement
+ * Ioctl to get a verity file's digest
  *
  * Copyright 2019 Google LLC
  */
@@ -10,12 +10,12 @@
 #include <linux/uaccess.h>
 
 /**
- * fsverity_ioctl_measure() - get a verity file's measurement
- * @filp: file to get measurement of
+ * fsverity_ioctl_measure() - get a verity file's digest
+ * @filp: file to get digest of
  * @_uarg: user pointer to fsverity_digest
  *
- * Retrieve the file measurement that the kernel is enforcing for reads from a
- * verity file.  See the "FS_IOC_MEASURE_VERITY" section of
+ * 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
@@ -51,7 +51,7 @@ int fsverity_ioctl_measure(struct file *filp, void __user *_uarg)
 	if (copy_to_user(uarg, &arg, sizeof(arg)))
 		return -EFAULT;
 
-	if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size))
+	if (copy_to_user(uarg->digest, vi->file_digest, hash_alg->digest_size))
 		return -EFAULT;
 
 	return 0;
diff --git a/fs/verity/open.c b/fs/verity/open.c
index a28d5be78a09..228d0eca3e2e 100644
--- a/fs/verity/open.c
+++ b/fs/verity/open.c
@@ -124,18 +124,18 @@ out_err:
 }
 
 /*
- * Compute the file measurement by hashing the fsverity_descriptor excluding the
+ * Compute the file digest by hashing the fsverity_descriptor excluding the
  * signature and with the sig_size field set to 0.
  */
-static int compute_file_measurement(struct fsverity_hash_alg *hash_alg,
-				    struct fsverity_descriptor *desc,
-				    u8 *measurement)
+static int compute_file_digest(struct fsverity_hash_alg *hash_alg,
+			       struct fsverity_descriptor *desc,
+			       u8 *file_digest)
 {
 	__le32 sig_size = desc->sig_size;
 	int err;
 
 	desc->sig_size = 0;
-	err = fsverity_hash_buffer(hash_alg, desc, sizeof(*desc), measurement);
+	err = fsverity_hash_buffer(hash_alg, desc, sizeof(*desc), file_digest);
 	desc->sig_size = sig_size;
 
 	return err;
@@ -199,15 +199,15 @@ struct fsverity_info *fsverity_create_info(const struct inode *inode,
 
 	memcpy(vi->root_hash, desc->root_hash, vi->tree_params.digest_size);
 
-	err = compute_file_measurement(vi->tree_params.hash_alg, desc,
-				       vi->measurement);
+	err = compute_file_digest(vi->tree_params.hash_alg, desc,
+				  vi->file_digest);
 	if (err) {
-		fsverity_err(inode, "Error %d computing file measurement", err);
+		fsverity_err(inode, "Error %d computing file digest", err);
 		goto out;
 	}
-	pr_debug("Computed file measurement: %s:%*phN\n",
+	pr_debug("Computed file digest: %s:%*phN\n",
 		 vi->tree_params.hash_alg->name,
-		 vi->tree_params.digest_size, vi->measurement);
+		 vi->tree_params.digest_size, vi->file_digest);
 
 	err = fsverity_verify_signature(vi, desc, desc_size);
 out:
@@ -354,7 +354,7 @@ int __init fsverity_init_info_cache(void)
 {
 	fsverity_info_cachep = KMEM_CACHE_USERCOPY(fsverity_info,
 						   SLAB_RECLAIM_ACCOUNT,
-						   measurement);
+						   file_digest);
 	if (!fsverity_info_cachep)
 		return -ENOMEM;
 	return 0;
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;
 }