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From:   Mimi Zohar <zohar@linux.ibm.com>
To:     linux-integrity@vger.kernel.org
Cc:     Mimi Zohar <zohar@linux.ibm.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Stefan Berger <stefanb@linux.ibm.com>,
        linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v7 5/5] fsverity: update the documentation
Date:   Fri, 25 Mar 2022 18:38:24 -0400
Message-Id: <20220325223824.310119-6-zohar@linux.ibm.com>
In-Reply-To: <20220325223824.310119-1-zohar@linux.ibm.com>
References: <20220325223824.310119-1-zohar@linux.ibm.com>
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Update the fsverity documentation related to IMA signature support.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
 Documentation/filesystems/fsverity.rst | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
index 1d831e3cbcb3..c1d355f17a54 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`_.
+
+The Integrity Measurement Architecture (IMA) supports including
+fs-verity file digests and signatures in the IMA measurement list
+and verifying fs-verity based file signatures stored as security.ima
+xattrs, based on policy.
 
 User API
 ========
@@ -653,12 +657,12 @@ 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
+    IMA supports the fs-verity hashing mechanism as an alternative
+    to full file hashes, for those who want the performance and
+    security benefits of the Merkle tree based hash.  However, it
+    doesn't make sense to force all uses of fs-verity to be through
+    IMA.  fs-verity already meets many users' needs even as a
+    standalone filesystem feature, and it's testable like other
     filesystem features e.g. with xfstests.
 
 :Q: Isn't fs-verity useless because the attacker can just modify the
-- 
2.27.0