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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham 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 74F96ECDFB8 for ; Wed, 18 Jul 2018 14:26:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BE8A20854 for ; Wed, 18 Jul 2018 14:26:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=thunk.org header.i=@thunk.org header.b="mOoiE35u" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BE8A20854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mit.edu Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731068AbeGRPEn (ORCPT ); Wed, 18 Jul 2018 11:04:43 -0400 Received: from imap.thunk.org ([74.207.234.97]:57080 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730123AbeGRPEm (ORCPT ); Wed, 18 Jul 2018 11:04:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=thunk.org; s=ef5046eb; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=PCBwdRZ1mcUvHLqdmdrQtlawWulAYCxtHc+C8zCeC9Y=; b=mOoiE35uSNXdjpyLqyDnO6La/6 FeCPYM7PsBEbSRedjRj0WQuiPSc4QOlO3eExK1HIURJ/fbLhWywkCE9aa0Jc3jaTE/uadSzYL3gHx gwmcaPou/RIT0CCFfSdJO+AbgmSd+jo2mslqQTLbcJpNheMUQUAb034Dp/rYKHsEIii8=; Received: from root (helo=callcc.thunk.org) by imap.thunk.org with local-esmtp (Exim 4.89) (envelope-from ) id 1ffnPP-0003Jy-Nh; Wed, 18 Jul 2018 14:26:27 +0000 Received: by callcc.thunk.org (Postfix, from userid 15806) id 52BC77A6404; Wed, 18 Jul 2018 10:26:25 -0400 (EDT) Date: Wed, 18 Jul 2018 10:26:25 -0400 From: "Theodore Y. Ts'o" To: Yann Droneaud Cc: linux-crypto@vger.kernel.org, Linux Kernel Developers List , labbott@redhat.com Subject: Re: [PATCH] random: add a config option to trust the CPU's hwrng Message-ID: <20180718142625.GA5942@thunk.org> Mail-Followup-To: "Theodore Y. Ts'o" , Yann Droneaud , linux-crypto@vger.kernel.org, Linux Kernel Developers List , labbott@redhat.com References: <20180718014344.1309-1-tytso@mit.edu> <37046662f2b38f98854abfa1b5868a27c3fa0888.camel@opteya.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <37046662f2b38f98854abfa1b5868a27c3fa0888.camel@opteya.com> User-Agent: Mutt/1.10.0 (2018-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 18, 2018 at 09:22:13AM +0200, Yann Droneaud wrote: > > The text message should explain this is only relevant during > initialization / early boot. > > The config option name should state this. There are other workarounds for hangs that happen after initialization / early boot, yes. They are of varying levels of quality / safely, but that's neither here nor there. However, enabling config option means that the CRNG will be initialized with potentially information available to the CPU manufacturer and/or Nation States, and this persists *after* initialization / early boot. So to say, "we're perfectly safe after we leave initialization / early boot" is not true. So I'd much rather make it clear that we are trusting the CPU manufacturer far more than just during early boot. Cheers, - Ted