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 3D95EC433F5 for ; Tue, 3 May 2022 12:33:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234547AbiECMhQ (ORCPT ); Tue, 3 May 2022 08:37:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47650 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232602AbiECMhP (ORCPT ); Tue, 3 May 2022 08:37:15 -0400 Received: from gardel.0pointer.net (gardel.0pointer.net [85.214.157.71]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8899F1EAE4; Tue, 3 May 2022 05:33:42 -0700 (PDT) Received: from gardel-login.0pointer.net (gardel-mail [IPv6:2a01:238:43ed:c300:10c3:bcf3:3266:da74]) by gardel.0pointer.net (Postfix) with ESMTP id 5366FE804AA; Tue, 3 May 2022 14:33:40 +0200 (CEST) Received: by gardel-login.0pointer.net (Postfix, from userid 1000) id C5E07160011; Tue, 3 May 2022 14:33:39 +0200 (CEST) Date: Tue, 3 May 2022 14:33:39 +0200 From: Lennart Poettering To: "Jason A. Donenfeld" Cc: Alexander Graf , linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, Dominik Brodowski , Greg Kroah-Hartman , Theodore Ts'o , Colm MacCarthaigh , Torben Hansen , Jann Horn Subject: Re: [PATCH 2/2] random: add fork_event sysctl for polling VM forks Message-ID: References: <20220502140602.130373-1-Jason@zx2c4.com> <20220502140602.130373-2-Jason@zx2c4.com> <7a1cfd1c-9f0e-f134-e544-83ee6d3cd9c9@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Di, 03.05.22 13:55, Jason A. Donenfeld (Jason@zx2c4.com) wrote: > I'm still not convinced there's value in having a counter or a UUID, but > if you had to choose, would you prefer a counter or a UUID? It sounds > like the former, because you see a use for distinguishing between zero > and non-zero? Or did you finally agree with me that vmgenid isn't > granular enough for that? I would prefer a monotonic counter, since it allows answering questions like the following: 1. Did this image get cloned at all? (i.e. counter != 0; usecase as per the MAC address discussion) 2. Did the image get cloned since the last time I looked? (i.e. counter != my_previously_saved_counter; usecase: detect clones in an "offline" fashion, i.e. from a component that doesn't continously run, but only from time to time) 3. How many clones did I miss? (i.e. missed_clones = my_previously_saved_counter - counter; usecase: catch up with generating proxy D-Bus signal messages for clones). There might be more. Using a UUID would not give us #1 or #3. It would deliver #2 however. Lennart -- Lennart Poettering, Berlin