From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 462501C6AD; Thu, 7 Mar 2024 14:31:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709821878; cv=none; b=JLTMofrpG0vu0KdX45+x1wwonHgyZF4IzuzjASSQBXvZRbBVkJH8b6mIjX43wUI8P/TEYgE9WacgZHa7fk/SlnjnIXRzsd322fw8j9QxLnpJJwQVEOeIH91c3KRCRsbrEKbgy9lLTaKLsDxyZ0V//cURJhN2OUsXPMU9tgE8bzw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709821878; c=relaxed/simple; bh=BoCuQpnKvXZmgHfTbdIlDgZOctJUi4njjxRSp+4CH5U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uGqIl3yr7+IWt1DEOeu9qZRzgggzbrGdPVNsXTsyzP5SHoMcUnVkb7aHoGlpksow2r0lUNbwsc6YM6of17o+JmCO7ieavRXPPo5Grx12tZO2IXM37QclyL8QT164n4JPmp68/8zauH5Dxt0Yi82UuFdlm/3n/tsA3KGaryrOp2s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pbC0xNQQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pbC0xNQQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B15B7C433C7; Thu, 7 Mar 2024 14:31:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709821877; bh=BoCuQpnKvXZmgHfTbdIlDgZOctJUi4njjxRSp+4CH5U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pbC0xNQQrGejHQ2bitaJqqjSkMc3ngNCgVrKc4lmct9ZugZ4DVuNDalUqhOcmAfoB 6fb3JKk/IYaOyPrqxkA5sNEZYYIpkwxcT8jt1fbFlcadr4RyVWEI9mz0lih8Fp01Kd uZ6nzAfci7WUsMGdOgDiNZKFx4zD2j3t+FvGKStRleoiz5tPTH83HX5pxO6+P8CTtN 0ujkoGBENcgy6n0Az2w3IC/eH0XBg3+MCgnpnVSsWwHPXBHZ3IAVDv8nm9/bdmBw6C /YawpO4sw+i+UQ8k7YDcO2dOMO4IJ/r10vfitQxgRLLcadLplEQujRsmwV+RBhqLVR oMu7jY1yZUVeA== Date: Thu, 7 Mar 2024 08:31:16 -0600 From: Seth Forshee To: Roberto Sassu Cc: zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Roberto Sassu , stable@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christian Brauner Subject: Re: [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash() Message-ID: References: <20240307122240.3560688-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240307122240.3560688-1-roberto.sassu@huaweicloud.com> On Thu, Mar 07, 2024 at 01:22:39PM +0100, Roberto Sassu wrote: > From: Roberto Sassu > > Use __vfs_getxattr() instead of vfs_getxattr(), in preparation for > deprecating using the vfs_ interfaces for retrieving fscaps. > > __vfs_getxattr() is only used for debugging purposes, to check if kernel > space and user space see the same xattr value. __vfs_getxattr() won't give you the value as seen by userspace though. Userspace goes through vfs_getxattr() -> xattr_getsecurity() -> cap_inode_getsecurity(), which does the conversion to the value userspace sees. __vfs_getxattr() just gives the raw disk data. I'm also currently working on changes to my fscaps series that will make it so that __vfs_getxattr() also cannot be used to read fscaps xattrs. I'll fix this and other code in EVM which will be broken by that change as part of the next version too. > > Cc: stable@vger.kernel.org # 5.14.x > Cc: linux-fsdevel@vger.kernel.org > Cc: Christian Brauner > Cc: Seth Forshee (DigitalOcean) > Fixes: 907a399de7b0 ("evm: Check xattr size discrepancy between kernel and user") > Signed-off-by: Roberto Sassu > --- > security/integrity/evm/evm_crypto.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c > index b1ffd4cc0b44..168d98c63513 100644 > --- a/security/integrity/evm/evm_crypto.c > +++ b/security/integrity/evm/evm_crypto.c > @@ -278,8 +278,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, > if (size < 0) > continue; > > - user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry, > - xattr->name, NULL, 0); > + user_space_size = __vfs_getxattr(dentry, inode, xattr->name, > + NULL, 0); > if (user_space_size != size) > pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n", > dentry->d_name.name, xattr->name, size, > -- > 2.34.1 >