[PATCH v1 5/5] fsverity: update the documentation
From: Mimi Zohar <zohar@linux.ibm.com>
Date: 2021-12-02 21:55:59
Also in:
linux-fscrypt, lkml
Subsystem:
documentation, fsverity: read-only file-based authenticity protection, the rest · Maintainers:
Jonathan Corbet, Eric Biggers, Theodore Y. Ts'o, Linus Torvalds
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. :Q: Isn't fs-verity useless because the attacker can just modify the hashes in the Merkle tree, which is stored on-disk?
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2.27.0