Re: [PATCH v1 5/5] fsverity: update the documentation

[Eric Biggers <ebiggers@kernel.org>]

On Thu, Dec 02, 2021 at 04:55:07PM -0500, Mimi Zohar wrote:
> Update the fsverity documentation related to IMA signature support.
> 
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
>  Documentation/filesystems/fsverity.rst | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
> index 1d831e3cbcb3..c71f6e365df5 100644
> --- a/Documentation/filesystems/fsverity.rst
> +++ b/Documentation/filesystems/fsverity.rst
> @@ -74,8 +74,12 @@ authenticating the files is up to userspace.  However, to meet some
>  users' needs, fs-verity optionally supports a simple signature
>  verification mechanism where users can configure the kernel to require
>  that all fs-verity files be signed by a key loaded into a keyring; see
> -`Built-in signature verification`_.  Support for fs-verity file hashes
> -in IMA (Integrity Measurement Architecture) policies is also planned.
> +`Built-in signature verification`_.
> +
> +IMA (Integrity Measurement Architecture) supports fs-verity file
> +digests based signatures stored as security.ima xattrs, which are
> +identified by the signature type IMA_VERITY_DIGSIG.
> +
>  
>  User API
>  ========
> @@ -653,13 +657,13 @@ weren't already directly answered in other parts of this document.
>      hashed and what to do with those hashes, such as log them,
>      authenticate them, or add them to a measurement list.
>  
> -    IMA is planned to support the fs-verity hashing mechanism as an
> -    alternative to doing full file hashes, for people who want the
> -    performance and security benefits of the Merkle tree based hash.
> -    But it doesn't make sense to force all uses of fs-verity to be
> -    through IMA.  As a standalone filesystem feature, fs-verity
> -    already meets many users' needs, and it's testable like other
> -    filesystem features e.g. with xfstests.
> +    IMA supports the fs-verity hashing mechanism as an alternative
> +    to doing full file hashes, for people who want the performance
> +    and security benefits of the Merkle tree based hash.  But it
> +    doesn't make sense to force all uses of fs-verity to be through
> +    IMA.  As a standalone filesystem feature, fs-verity already meets
> +    many users' needs, and it's testable like other filesystem
> +    features e.g. with xfstests.
>  

Isn't there IMA documentation that can be linked to?

- Eric