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 X-Spam-Level: X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74FFFC433DB for ; Thu, 21 Jan 2021 06:39:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DD142342C for ; Thu, 21 Jan 2021 06:39:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725984AbhAUGis (ORCPT ); Thu, 21 Jan 2021 01:38:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:49450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387519AbhATXpp (ORCPT ); Wed, 20 Jan 2021 18:45:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3FF75221FE; Wed, 20 Jan 2021 23:44:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611186302; bh=DtYGGvkksfs7vXommXeJwl91lOsFd1rEuyBTgJv2+l0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=E70AnGgrCqxaoh1vWdlhGmZ2hd7h/FB84wv2240pZVLQUYmrHgMKATyaqSOkK85F/ efCn9nc8j0I9yyif6cEaIBQ+Y8LWSf+T/dqeBGKToiPaLLnNeBV1+7hwW5AxIM/qIi msPEsJTYyd/Wx5bu8Da6KODI7Zbxlq/djYsCS3CT/WKtcjJxGMw81TsvZN0B0zv+fH yq1FOKDdleusG2CT5IJQua2USHSh1tGzSkT6kTlaaNQQJ6+uyly9wZta2XxuOIhExl bu2B36wdUYjoVyWPzvMvz8AUR+XPQHfHGGqkXP6OrYIbAY4z8Hgjlm7KTVPVLiVjYh Vr6VDSf5UWiWw== Date: Thu, 21 Jan 2021 01:44:56 +0200 From: Jarkko Sakkinen To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: David Howells , David Woodhouse , "David S . Miller" , Herbert Xu , James Morris , =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= , Mimi Zohar , "Serge E . Hallyn" , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Ben Boeckel Subject: Re: [PATCH v3 02/10] certs: Fix blacklisted hexadecimal hash string check Message-ID: References: <20210114151909.2344974-1-mic@digikod.net> <20210114151909.2344974-3-mic@digikod.net> <05e3ce56-c27c-877d-8ebe-d088ba95f248@digikod.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <05e3ce56-c27c-877d-8ebe-d088ba95f248@digikod.net> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Wed, Jan 20, 2021 at 12:12:50PM +0100, Mickaël Salaün wrote: > > On 20/01/2021 04:43, Jarkko Sakkinen wrote: > > On Thu, Jan 14, 2021 at 04:19:01PM +0100, Mickaël Salaün wrote: > >> From: Mickaël Salaün > >> > >> When looking for a blacklisted hash, bin2hex() is used to transform a > >> binary hash to an ascii (lowercase) hexadecimal string. This string is > >> then search for in the description of the keys from the blacklist > >> keyring. When adding a key to the blacklist keyring, > >> blacklist_vet_description() checks the hash prefix and the hexadecimal > >> string, but not that this string is lowercase. It is then valid to set > >> hashes with uppercase hexadecimal, which will be silently ignored by the > >> kernel. > >> > >> Add an additional check to blacklist_vet_description() to check that > >> hexadecimal strings are in lowercase. > >> > >> Cc: David Woodhouse > >> Signed-off-by: Mickaël Salaün > >> Signed-off-by: David Howells > >> Reviewed-by: Ben Boeckel > >> --- > >> > >> Changes since v2: > >> * Cherry-pick v1 patch from > >> https://lore.kernel.org/lkml/2659836.1607940186@warthog.procyon.org.uk/ > >> to rebase on v5.11-rc3. > >> * Rearrange Cc order. > >> --- > >> certs/blacklist.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/certs/blacklist.c b/certs/blacklist.c > >> index 2719fb2fbc1c..a888b934a1cd 100644 > >> --- a/certs/blacklist.c > >> +++ b/certs/blacklist.c > >> @@ -37,7 +37,7 @@ static int blacklist_vet_description(const char *desc) > >> found_colon: > >> desc++; > >> for (; *desc; desc++) { > >> - if (!isxdigit(*desc)) > >> + if (!isxdigit(*desc) || isupper(*desc)) > >> return -EINVAL; > >> n++; > >> } > >> -- > >> 2.30.0 > >> > > > > Shouldn't this rather convert the upper case to lower case? I don't like > > the ABI break that this causes. > > It doesn't break the ABI because keys loaded in the blacklist keyring > can only happen with builtin hashes. Moreover these builtin hashes will > be checked by patch 10/10 at build time. Right the patches are just out of order then. /Jarkko > > This patch is also important to remove a false sense of security and > warns about mis-blacklisted certificates or binaries: > https://lore.kernel.org/lkml/c9664a67-61b7-6b4a-86d7-5aca9ff06fa5@digikod.net/ > > Hot-patching keys doesn't seem a good idea, especially when these keys > are signed. Moreover, it would bring additional complexity and will > require to change the core of the key management. > > > > > /Jarkko > > >