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 ED429C46467 for ; Sun, 27 Nov 2022 21:12:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229610AbiK0VMr (ORCPT ); Sun, 27 Nov 2022 16:12:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229600AbiK0VMq (ORCPT ); Sun, 27 Nov 2022 16:12:46 -0500 X-Greylist: delayed 244 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 27 Nov 2022 13:12:45 PST Received: from cavan.codon.org.uk (cavan.codon.org.uk [176.126.240.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DE59BC86; Sun, 27 Nov 2022 13:12:45 -0800 (PST) Received: by cavan.codon.org.uk (Postfix, from userid 1000) id 3317D424A3; Sun, 27 Nov 2022 21:12:44 +0000 (GMT) Date: Sun, 27 Nov 2022 21:12:44 +0000 From: Matthew Garrett To: "Jason A. Donenfeld" Cc: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, ardb@kernel.org Subject: Re: [PATCH v3 2/5] efi: stub: use random seed from EFI variable Message-ID: <20221127211244.GB32253@srcf.ucam.org> References: <20221122020404.3476063-1-Jason@zx2c4.com> <20221122020404.3476063-3-Jason@zx2c4.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221122020404.3476063-3-Jason@zx2c4.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Tue, Nov 22, 2022 at 03:04:01AM +0100, Jason A. Donenfeld wrote: > + * We delete the seed here, and /hope/ that this causes EFI to > + * also zero out its representation on disk. This is somewhat Several implementations I've worked with simply append a deletion marker or append a new variable value until the variable store fills up entirely, at which point a garbage collection event is either run or scheduled for the next reboot. The spec doesn't define how this is handled so unfortunately I don't think there's any way to get a pony here.