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 EC8D1C433FE for ; Wed, 16 Nov 2022 18:08:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233512AbiKPSII (ORCPT ); Wed, 16 Nov 2022 13:08:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbiKPSII (ORCPT ); Wed, 16 Nov 2022 13:08:08 -0500 X-Greylist: delayed 504 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Wed, 16 Nov 2022 10:08:06 PST Received: from gardel.0pointer.net (gardel.0pointer.net [85.214.157.71]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58A2FEE1D; Wed, 16 Nov 2022 10:08:06 -0800 (PST) Received: from gardel-login.0pointer.net (gardel-mail [85.214.157.71]) by gardel.0pointer.net (Postfix) with ESMTP id EFB82E8019B; Wed, 16 Nov 2022 18:59:38 +0100 (CET) Received: by gardel-login.0pointer.net (Postfix, from userid 1000) id 72FBE1600BB; Wed, 16 Nov 2022 18:59:38 +0100 (CET) Date: Wed, 16 Nov 2022 18:59:38 +0100 From: Lennart Poettering To: "Jason A. Donenfeld" Cc: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org, Ard Biesheuvel Subject: Re: [PATCH RFC v1 0/6] Use EFI variables for random seed Message-ID: References: <20221116161642.1670235-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221116161642.1670235-1-Jason@zx2c4.com> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Mi, 16.11.22 17:16, Jason A. Donenfeld (Jason@zx2c4.com) wrote: > Commit messages are rather sparse at the moment. I'll fill those out for > the next non-RFC patchset if this idea isn't immediately demolished. > > The biggest consideration is wear leveling on the EFI variable flash > chips. However, EFI *already* winds up writing to non-volatile memory on > every single boot anyway, so maybe it's not actually a big deal? So as mentioned elsewhere: This might (probably more than) double the wear on the flash chips, since firmware is unlikely to batch these writes with the monotonic counter write. I have no idea how realistic these issues are, there's a lot of handwaving involved, but to sidestep the issue I put sd-boot's seed in a file on disk (which should not have issues that much with wear) instead of efi vars. Lennart