[PATCH] fs-verity: rename fsverity_signed_digest to fsverity_formatted_digest

[PATCH] fs-verity: rename fsverity_signed_digest to fsverity_formatted_digest

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

The name "struct fsverity_signed_digest" is causing confusion because it
isn't actually a signed digest, but rather it's the way that the digest
is formatted in order to be signed.  Rename it to
"struct fsverity_formatted_digest" to prevent this confusion.

Also update the struct's comment to clarify that it's specific to the
built-in signature verification support and isn't a requirement for all
fs-verity users.

I'll be renaming this struct in fsverity-utils too.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 Documentation/filesystems/fsverity.rst |  2 +-
 fs/verity/fsverity_private.h           | 17 ++++++++++++-----
 fs/verity/signature.c                  |  2 +-
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
index 895e9711ed88..421b75498d49 100644
--- a/Documentation/filesystems/fsverity.rst
+++ b/Documentation/filesystems/fsverity.rst
@@ -372,7 +372,7 @@ kernel.  Specifically, it adds support for:
 File measurements must be signed in the following format, which is
 similar to the structure used by `FS_IOC_MEASURE_VERITY`_::
 
-    struct fsverity_signed_digest {
+    struct fsverity_formatted_digest {
             char magic[8];                  /* must be "FSVerity" */
             __le16 digest_algorithm;
             __le16 digest_size;
diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h
index e96d99d5145e..75f8e18b44a5 100644
--- a/fs/verity/fsverity_private.h
+++ b/fs/verity/fsverity_private.h
@@ -101,12 +101,19 @@ struct fsverity_descriptor {
 					 sizeof(struct fsverity_descriptor))
 
 /*
- * Format in which verity file measurements are signed.  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 endianness.
+ * Format in which verity file measurements 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
+ * endianness.
+ *
+ * This struct is specific to the built-in signature verification support, which
+ * is optional.  fs-verity users may also verify signatures in userspace, in
+ * which case userspace is responsible for deciding on what bytes are signed.
+ * This struct may still be used, but it doesn't have to be.  For example,
+ * userspace could instead use a string like "sha256:$digest_as_hex_string".
  */
-struct fsverity_signed_digest {
+struct fsverity_formatted_digest {
 	char magic[8];			/* must be "FSVerity" */
 	__le16 digest_algorithm;
 	__le16 digest_size;
diff --git a/fs/verity/signature.c b/fs/verity/signature.c
index b14ed96387ec..26c76fedd78b 100644
--- a/fs/verity/signature.c
+++ b/fs/verity/signature.c
@@ -44,7 +44,7 @@ int fsverity_verify_signature(const struct fsverity_info *vi,
 	const struct inode *inode = vi->inode;
 	const struct fsverity_hash_alg *hash_alg = vi->tree_params.hash_alg;
 	const u32 sig_size = le32_to_cpu(desc->sig_size);
-	struct fsverity_signed_digest *d;
+	struct fsverity_formatted_digest *d;
 	int err;
 
 	if (sig_size == 0) {

base-commit: 4d09c1d952679411da2772f199643e08c46c31cd
-- 
2.29.0.rc2.309.g374f81d7ae-goog

Re: [PATCH] fs-verity: rename fsverity_signed_digest to fsverity_formatted_digest

[Luca Boccassi]

On Tue, 27 Oct 2020 at 19:13, Eric Biggers <ebiggers@kernel.org> wrote:
>
> From: Eric Biggers <ebiggers@google.com>
>
> The name "struct fsverity_signed_digest" is causing confusion because it
> isn't actually a signed digest, but rather it's the way that the digest
> is formatted in order to be signed.  Rename it to
> "struct fsverity_formatted_digest" to prevent this confusion.
>
> Also update the struct's comment to clarify that it's specific to the
> built-in signature verification support and isn't a requirement for all
> fs-verity users.
>
> I'll be renaming this struct in fsverity-utils too.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  Documentation/filesystems/fsverity.rst |  2 +-
>  fs/verity/fsverity_private.h           | 17 ++++++++++++-----
>  fs/verity/signature.c                  |  2 +-
>  3 files changed, 14 insertions(+), 7 deletions(-)

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>

Re: [PATCH] fs-verity: rename fsverity_signed_digest to fsverity_formatted_digest

[Eric Biggers]

On Tue, Oct 27, 2020 at 12:11:06PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> The name "struct fsverity_signed_digest" is causing confusion because it
> isn't actually a signed digest, but rather it's the way that the digest
> is formatted in order to be signed.  Rename it to
> "struct fsverity_formatted_digest" to prevent this confusion.
> 
> Also update the struct's comment to clarify that it's specific to the
> built-in signature verification support and isn't a requirement for all
> fs-verity users.
> 
> I'll be renaming this struct in fsverity-utils too.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Applied to fscrypt.git#fsverity for 5.11.

- Eric

Re: [PATCH] fs-verity: rename fsverity_signed_digest to fsverity_formatted_digest

[Eric Biggers]

On Fri, Nov 13, 2020 at 10:41:13AM -0800, Eric Biggers wrote:
> On Tue, Oct 27, 2020 at 12:11:06PM -0700, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > The name "struct fsverity_signed_digest" is causing confusion because it
> > isn't actually a signed digest, but rather it's the way that the digest
> > is formatted in order to be signed.  Rename it to
> > "struct fsverity_formatted_digest" to prevent this confusion.
> > 
> > Also update the struct's comment to clarify that it's specific to the
> > built-in signature verification support and isn't a requirement for all
> > fs-verity users.
> > 
> > I'll be renaming this struct in fsverity-utils too.
> > 
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> 
> Applied to fscrypt.git#fsverity for 5.11.
> 
> - Eric

Actually, I decided to resend this as part of the series
https://lkml.kernel.org/linux-fscrypt/20201113211918.71883-1-ebiggers@kernel.org.

- Eric