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_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 35C92CA9EC3 for ; Tue, 29 Oct 2019 14:58:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C8442087E for ; Tue, 29 Oct 2019 14:58:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="T7NX3+73"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="T7NX3+73" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389794AbfJ2O6S (ORCPT ); Tue, 29 Oct 2019 10:58:18 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:38210 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389245AbfJ2O6S (ORCPT ); Tue, 29 Oct 2019 10:58:18 -0400 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id A5CCE8EE180; Tue, 29 Oct 2019 07:58:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1572361097; bh=Km7xzhqJCON168lObmDAWI1ZFbTna56Ifa4zThcvXmI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=T7NX3+73FsAuWkqUitVx2dlusGJI7PHBMrkLdJhs5zUKhsqIYRZxc/145jTq9hAq8 NIavX8VqU11G6odn3IbVJ563OSbkYJ6oDDeE4xjwau2ZlQzfgKwYTUEAPO7mY5YIy9 Ts4PAGWefolf/XFoWCxWmlkQGZONV8Z4eNIxQjuQ= Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id b3FM-ft7E3RJ; Tue, 29 Oct 2019 07:58:17 -0700 (PDT) Received: from jarvis.lan (unknown [50.35.76.230]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 173048EE15F; Tue, 29 Oct 2019 07:58:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1572361097; bh=Km7xzhqJCON168lObmDAWI1ZFbTna56Ifa4zThcvXmI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=T7NX3+73FsAuWkqUitVx2dlusGJI7PHBMrkLdJhs5zUKhsqIYRZxc/145jTq9hAq8 NIavX8VqU11G6odn3IbVJ563OSbkYJ6oDDeE4xjwau2ZlQzfgKwYTUEAPO7mY5YIy9 Ts4PAGWefolf/XFoWCxWmlkQGZONV8Z4eNIxQjuQ= Message-ID: <1572361096.4812.3.camel@HansenPartnership.com> Subject: Re: [PATCH] KEYS: asym_tpm: Switch to get_random_bytes() From: James Bottomley To: Jarkko Sakkinen Cc: "Safford, David (GE Global Research, US)" , Ken Goldman , Mimi Zohar , "linux-integrity@vger.kernel.org" , "stable@vger.kernel.org" , "open list:ASYMMETRIC KEYS" , "open list:CRYPTO API" , open list Date: Tue, 29 Oct 2019 07:58:16 -0700 In-Reply-To: <20191029084258.GA5649@linux.intel.com> References: <20191008235339.GB13926@linux.intel.com> <20191014190033.GA15552@linux.intel.com> <1571081397.3728.9.camel@HansenPartnership.com> <20191016110031.GE10184@linux.intel.com> <1571229252.3477.7.camel@HansenPartnership.com> <20191016162543.GB6279@linux.intel.com> <1571253029.17520.5.camel@HansenPartnership.com> <20191017180440.GG6667@linux.intel.com> <20191021113939.GA11649@linux.intel.com> <20191029084258.GA5649@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2019-10-29 at 10:42 +0200, Jarkko Sakkinen wrote: > On Mon, Oct 21, 2019 at 02:39:39PM +0300, Jarkko Sakkinen wrote: > > On Thu, Oct 17, 2019 at 09:04:40PM +0300, Jarkko Sakkinen wrote: > > > On Wed, Oct 16, 2019 at 03:10:29PM -0400, James Bottomley wrote: > > > > On Wed, 2019-10-16 at 19:25 +0300, Jarkko Sakkinen wrote: > > > > > On Wed, Oct 16, 2019 at 08:34:12AM -0400, James Bottomley > > > > > wrote: > > > > > > reversible ciphers are generally frowned upon in random > > > > > > number > > > > > > generation, that's why the krng uses chacha20. In general > > > > > > I think > > > > > > we shouldn't try to code our own mixing and instead should > > > > > > get the > > > > > > krng to do it for us using whatever the algorithm du jour > > > > > > that the > > > > > > crypto guys have blessed is. That's why I proposed adding > > > > > > the TPM > > > > > > output to the krng as entropy input and then taking the > > > > > > output of > > > > > > the krng. > > > > > > > > > > It is already registered as hwrng. What else? > > > > > > > > It only contributes entropy once at start of OS. > > > > > > Ok. > > > > > > > > Was the issue that it is only used as seed when the rng is > > > > > init'd > > > > > first? I haven't at this point gone to the internals of krng. > > > > > > > > Basically it was similar to your xor patch except I got the > > > > kernel rng > > > > to do the mixing, so it would use the chacha20 cipher at the > > > > moment > > > > until they decide that's unsafe and change it to something > > > > else: > > > > > > > > https://lore.kernel.org/linux-crypto/1570227068.17537.4.camel@H > > > > ansenPartnership.com/ > > > > > > > > It uses add_hwgenerator_randomness() to do the mixing. It also > > > > has an > > > > unmixed source so that read of the TPM hwrng device works as > > > > expected. > > > > > > Thinking that could this potentially racy? I.e. between the calls > > > something else could eat the entropy added? > > > > Also, what is wrong just taking one value from krng and mixing > > it with a value from TPM RNG where needed? That would be non-racy > > too. > > I guess we can move forward with this? Sure I suppose; can we can figure out how to get the mixing function du jour exposed? James