linux-kernel - Re: [PATCH v2 0/3] evm: disable EVM on overlayfs

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Date: Wed, 20 Dec 2023 09:19:20 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-unionfs@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, Amir Goldstein <amir73il@...il.com>,
        Seth
 Forshee <sforshee@...nel.org>,
        Roberto Sassu <roberto.sassu@...weicloud.com>
Subject: Re: [PATCH v2 0/3] evm: disable EVM on overlayfs

On Wed, 2023-12-20 at 13:35 +0100, Christian Brauner wrote:
> On Tue, Dec 19, 2023 at 12:52:03PM -0500, Mimi Zohar wrote:
> > EVM verifies the existing 'security.evm' value, before allowing it
> > to be updated.  The EVM HMAC and the original file signatures contain
> > filesystem specific metadata (e.g. i_ino, i_generation and s_uuid).
> > 
> > This poses a challenge when transitioning from the lower backing file
> > to the upper backing file.
> > 
> > Until a complete solution is developed, disable EVM on overlayfs.
> > 
> > Changelog v2:
> > Addressed Amir's comments:
> > - Simplified security_inode_copy_up_xattr() return.
> > - Identified filesystems that don't support EVM based on a new SB_I flag.
> 
> We're wasting a flag for a single filesystem but we do have enough of
> them left so I think this is ok,

Thanks, Christian.

> 
> Reviewed-by: Christian Brauner <brauner@...nel.org>