From patchwork Wed Feb 23 13:12:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12756901 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 CD076C433FE for ; Wed, 23 Feb 2022 13:12:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240746AbiBWNNY (ORCPT ); Wed, 23 Feb 2022 08:13:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238766AbiBWNNX (ORCPT ); Wed, 23 Feb 2022 08:13:23 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF8DA5FF17; Wed, 23 Feb 2022 05:12:55 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6478B6117F; Wed, 23 Feb 2022 13:12:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 533DEC340F0; Wed, 23 Feb 2022 13:12:53 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="p2uLwLyr" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1645621971; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=yDH6L5SfKXyei5pTTzcAk9yjz7NgT/Zl7Px1eWnwpqQ=; b=p2uLwLyrNMQ8HTaqGPewS3XX209s7oJqJ9miRcoY1DtAZT8hviF4SxAj5On0Im2pbnBr3p qozPAZOFG4amHtvVOWAclMD5HdWA5Oi9z78mYqPXXrH2JsBBaqdcZS4CZ649Pcqn51y//z udUOOwgOLtSyOIgtQw8+TrDExV8xsig= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 57f5dfd0 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Wed, 23 Feb 2022 13:12:50 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, qemu-devel@nongnu.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, adrian@parity.io Cc: "Jason A. Donenfeld" , dwmw@amazon.co.uk, acatan@amazon.com, graf@amazon.com, colmmacc@amazon.com, sblbir@amazon.com, raduweis@amazon.com, jannh@google.com, gregkh@linuxfoundation.org, tytso@mit.edu Subject: [PATCH RFC v1 0/2] VM fork detection for RNG Date: Wed, 23 Feb 2022 14:12:29 +0100 Message-Id: <20220223131231.403386-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This small series picks up work from Amazon that seems to have stalled out later year around this time: listening for the vmgenid ACPI notification, and using it to "do something." Last year, that something involved a complicated userspace mmap chardev, which seems frought with difficulty. This year, I have something much simpler in mind: simply using those ACPI notifications to tell the RNG to reinitialize safely, so we don't repeat random numbers in cloned, forked, or rolled-back VM instances. This series consists of two patches. The first is a rather straightforward addition to random.c, which I feel fine about. The second patch is the reason this is just an RFC: it's a cleanup of the ACPI driver from last year, and I don't really have much experience writing, testing, debugging, or maintaining these types of drivers. Ideally this thread would yield somebody saying, "I see the intent of this; I'm happy to take over ownership of this part." That way, I can focus on the RNG part, and whoever steps up for the paravirt ACPI part can focus on that. As a final note, this series intentionally does _not_ focus on notification of these events to userspace or to other kernel consumers. Since these VM fork detection events first need to hit the RNG, we can later talk about what sorts of notifications or mmap'd counters the RNG should be making accessible to elsewhere. But that's a different sort of project and ties into a lot of more complicated concerns beyond this more basic patchset. So hopefully we can keep the discussion rather focused here to this ACPI business. Cc: dwmw@amazon.co.uk Cc: acatan@amazon.com Cc: graf@amazon.com Cc: colmmacc@amazon.com Cc: sblbir@amazon.com Cc: raduweis@amazon.com Cc: jannh@google.com Cc: gregkh@linuxfoundation.org Cc: tytso@mit.edu Jason A. Donenfeld (2): random: add mechanism for VM forks to reinitialize crng drivers/virt: add vmgenid driver for reinitializing RNG drivers/char/random.c | 58 ++++++++++++++++++ drivers/virt/Kconfig | 8 +++ drivers/virt/Makefile | 1 + drivers/virt/vmgenid.c | 133 +++++++++++++++++++++++++++++++++++++++++ include/linux/random.h | 1 + 5 files changed, 201 insertions(+) create mode 100644 drivers/virt/vmgenid.c