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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 4859FECE588 for ; Tue, 15 Oct 2019 17:04:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21BE42084B for ; Tue, 15 Oct 2019 17:04:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="D4ShOz3T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727132AbfJOREx (ORCPT ); Tue, 15 Oct 2019 13:04:53 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:46263 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726558AbfJOREx (ORCPT ); Tue, 15 Oct 2019 13:04:53 -0400 Received: by mail-pf1-f196.google.com with SMTP id q5so12846942pfg.13 for ; Tue, 15 Oct 2019 10:04:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=mqEuhvlTqp14S8mH0iL/2lPaSLcfm7VaqiIgGEqKWMk=; b=D4ShOz3TQih7NmaeEtKqlb0TSvP7KSMCGM5nw1Meu4R/O3TiGC5gvdoT71EV93zC00 o3P+2MuiEwb0x991JYgWp8RdsnPrBq2eyzFNkZDCqtcKJGPHCCnvf1W4QrN3VlTGqVij zRnQqqWnEEhxFpafxdGrn/uS+QEnde8vqvC29bWx5046vcTH9kQMcaZetBfWiLZkgUN8 hjnNumZcvEZx1UUhlUQZRyKKjXyIKIV7KPwAirH1UN6EHwD6GCbdBelziTqbqa4CSk17 wk9w51KIJ5QnnvrCOdhBE3ZGCWGrQSqbFk5WguDuNE5KJN3rwt7Xu/CYbFfh28G9P7bq JqYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=mqEuhvlTqp14S8mH0iL/2lPaSLcfm7VaqiIgGEqKWMk=; b=OwU7uQkbifpfY7Hx+/fEoLnV23rqOnfVqXYWVjWoPjMQzBgJWF97J6hvIc38SLtFjH dXJIKVFSt27lAj21sHkhlMvsw8kPslW3i7N0Mbx/yphfI8GdTXMCgJG+fWbmfve7hrOO jGrZYbtWlqe07CuxqaJJT9blLFttPMZy6dfdNlnLdgmFiyjcn8CPwfqQQe1RttfrBH5D ofH2VDYQuEymiaCgR/6+5Plz29nbugtjArkzJ2vljhVcRD4SC84EdGZRelWm5FrkOg70 xkbkxtF80s8uYZ8EtZYg0wmYLTQhfAktHnLyjZIqvTTecJgqdJ0eP3MN9vMy6TwD392V +BUA== X-Gm-Message-State: APjAAAU0dUWg5rFu+cc770guWRqE4cTCLm65jSbgg5EUYiyquVeGZ0oX 5FX7CnEEP7+PlYqGv+TBFZ2n1g== X-Google-Smtp-Source: APXvYqyhmYECdW43MhFhTN7//aeS41RHJ10Z2yDljk0yyhfJjbjM1mu84/PDw5uP6av+TuznHBaj2A== X-Received: by 2002:a63:6949:: with SMTP id e70mr39295261pgc.226.1571159092733; Tue, 15 Oct 2019 10:04:52 -0700 (PDT) Received: from ziepe.ca ([72.143.229.181]) by smtp.gmail.com with ESMTPSA id t125sm26439052pfc.80.2019.10.15.10.04.51 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 15 Oct 2019 10:04:51 -0700 (PDT) Received: from jgg by jggl.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iKQFe-0001TU-HP; Tue, 15 Oct 2019 14:04:50 -0300 Date: Tue, 15 Oct 2019 14:04:50 -0300 From: Jason Gunthorpe To: Jarkko Sakkinen Cc: linux-integrity@vger.kernel.org, David Safford , Pascal Van Leeuwen , James Bottomley , Peter Huewe , Arnd Bergmann , Greg Kroah-Hartman , open list Subject: Re: [PATCH] tpm: Salt tpm_get_random() result with get_random_bytes() Message-ID: <20191015170450.GB5444@ziepe.ca> References: <20191015124702.633-1-jarkko.sakkinen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191015124702.633-1-jarkko.sakkinen@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Tue, Oct 15, 2019 at 03:47:02PM +0300, Jarkko Sakkinen wrote: > Salt the result that comes from the TPM RNG with random bytes from the > kernel RNG. This will allow to use tpm_get_random() as a substitute for > get_random_bytes(). TPM could have a bug (making results predicatable), > backdoor or even an inteposer in the bus. Salting gives protections > against these concerns. Seems like a dangerous use case, why would any kernel user that cared about quality of randomness ever call a tpm_* API to get quality random data? Jason