From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9189C433FE for ; Mon, 7 Nov 2022 16:23:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232824AbiKGQXp (ORCPT ); Mon, 7 Nov 2022 11:23:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232133AbiKGQXL (ORCPT ); Mon, 7 Nov 2022 11:23:11 -0500 Received: from smtp-1908.mail.infomaniak.ch (smtp-1908.mail.infomaniak.ch [IPv6:2001:1600:4:17::1908]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9DC4240BB for ; Mon, 7 Nov 2022 08:21:00 -0800 (PST) Received: from smtp-2-0000.mail.infomaniak.ch (unknown [10.5.36.107]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4N5c0n3vwFzMq4Rq; Mon, 7 Nov 2022 17:20:57 +0100 (CET) Received: from ns3096276.ip-94-23-54.eu (unknown [23.97.221.149]) by smtp-2-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4N5c0k0hNRzMppDn; Mon, 7 Nov 2022 17:20:54 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=digikod.net; s=20191114; t=1667838057; bh=/Hxzji7LOlrPI3D4EEkzO0ARX8DsTpF3mgj/GUpF6Pk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gFUGW4Fw6Ro4F87y5z93lAFXMNDQZkpgvZFUYBth1xVO6RFSg0Y/jNrArCaLGqe35 TSBOCoY9PGKmpc3SkoK5uTdTeNIgngOdglJXnnNg5tnBX8WbJBdiO5Hlt012/cN+7y 1VhNMm1AnRtPLiI+eoj2usye0DamHZ44AldN0MM8= Message-ID: <8692915f-437c-56fd-8984-d6febf533fa9@digikod.net> Date: Mon, 7 Nov 2022 17:20:53 +0100 MIME-Version: 1.0 User-Agent: Subject: Re: [PATCH] certs: Prevent spurious errors on repeated blacklisting Content-Language: en-US To: =?UTF-8?Q?Thomas_Wei=c3=9fschuh?= Cc: David Howells , David Woodhouse , Jarkko Sakkinen , keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Pearson , Eric Snowberg , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org References: <20221104014704.3469-1-linux@weissschuh.net> <3b997266-067c-975c-911a-da146fe9033a@digikod.net> From: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/11/2022 16:55, Thomas Weißschuh wrote: > On 2022-11-07 14:12+0100, Mickaël Salaün wrote: >> This is a follow-up of >> https://lore.kernel.org/r/c8c65713-5cda-43ad-8018-20f2e32e4432@t-8ch.de >> >> Added Jarkko, Mark Pearson, Eric Snowberg and more ML in Cc. >> >> >> On 04/11/2022 02:47, Thomas Weißschuh wrote: >>> When the blacklist keyring was changed to allow updates from the root >>> user it gained an ->update() function that disallows all updates. >>> When the a hash is blacklisted multiple times from the builtin or >>> firmware-provided blacklist this spams prominent logs during boot: >>> >>> [ 0.890814] blacklist: Problem blacklisting hash (-13) >>> >>> As all these repeated calls to mark_raw_hash_blacklisted() would create >>> the same keyring entry again anyways these errors can be safely ignored. >> >> These errors can indeed be safely ignored, however they highlight issues >> with some firmware vendors not checking nor optimizing their blocked hashes. >> This raises security concerns, and it should be fixed by firmware vendors. > > Thanks, I was not aware that these are worth fixing. > >>> Fixes: 6364d106e041 ("certs: Allow root user to append signed hashes to the blacklist keyring") >>> Signed-off-by: Thomas Weißschuh >>> --- >>> certs/blacklist.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/certs/blacklist.c b/certs/blacklist.c >>> index 41f10601cc72..5f7f2882ced7 100644 >>> --- a/certs/blacklist.c >>> +++ b/certs/blacklist.c >>> @@ -191,7 +191,9 @@ static int mark_raw_hash_blacklisted(const char *hash) >>> BLACKLIST_KEY_PERM, >>> KEY_ALLOC_NOT_IN_QUOTA | >>> KEY_ALLOC_BUILT_IN); >>> - if (IS_ERR(key)) { >>> + >>> + /* Blacklisting the same hash twice fails but would be idempotent */ >>> + if (IS_ERR(key) && PTR_ERR(key) != -EACCES) { >> >> We should not hide EACCES errors. This logs issues, which is correct for >> duplicate hashes, and can help firmware vendors to fix their database. I'd >> really like to see a different log message instead: change the duplicate >> entry error code from EACCES to EEXIST, and call pr_warn for this specific >> case. > > Returning EACCES would require some deeper changes to how the keyring is set up I guess you meant EEXIST? > or even changes to the keyring core itself to introduce a key_create() (without > update) function. > > Is this something you would take a look at, or should I try to do it? > (I have no previous knowledge about the keyring subsystem) Please take a look. I think it should not be too complex. > > In any case it probably would also be good to log the problematic hashes > themselves, so users can properly report the issue to their firmware vendors. Agree > >>> pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key)); >>> return PTR_ERR(key); >>> } >>> >>> base-commit: ee6050c8af96bba2f81e8b0793a1fc2f998fcd20