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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 C0CFFC43381 for ; Mon, 25 Feb 2019 22:51:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85A8A21841 for ; Mon, 25 Feb 2019 22:51:50 +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="cws0wPrF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728787AbfBYWvt (ORCPT ); Mon, 25 Feb 2019 17:51:49 -0500 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:57526 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728708AbfBYWvt (ORCPT ); Mon, 25 Feb 2019 17:51:49 -0500 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 0F4978EE1A0; Mon, 25 Feb 2019 14:51:49 -0800 (PST) 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 Ghq_VUdu-Qch; Mon, 25 Feb 2019 14:51:48 -0800 (PST) Received: from [153.66.254.194] (unknown [50.35.68.20]) (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 1112E8EE101; Mon, 25 Feb 2019 14:51:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1551135108; bh=WSdvB4lMWzZfO50Ccyn/jvKRnIPp8dWVS6rbA+pYxVQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=cws0wPrF10v/F+cfJ+J3zM5cofwSiCUw5sxtacm6TCj+0QynpkCuOwN9IPk3A7Zgh r2ANkM9t5wFQ85lZAipJZbgCI7P3IZ4phEIXbf0gaQ6EaYEwfwsP3HMSq+jWwGKxpz yaxLtLxWF50JCPbAboobNa1W491j0VyCNyrAyr78= Message-ID: <1551135106.3226.91.camel@HansenPartnership.com> Subject: Re: [PATCH] tpm: Add driver for TPM over virtio From: James Bottomley To: Matthew Garrett Cc: David Tolnay , Peter Huewe , Jarkko Sakkinen , Jason Gunthorpe , linux-integrity , "Michael S. Tsirkin" , Jason Wang , virtualization@lists.linux-foundation.org, dgreid@chromium.org, apronin@chromium.org Date: Mon, 25 Feb 2019 14:51:46 -0800 In-Reply-To: References: <388c5b80-21a7-1e91-a11f-3a1c1432368b@gmail.com> <1550849416.2787.5.camel@HansenPartnership.com> <1550873900.2787.25.camel@HansenPartnership.com> <1550885645.3577.31.camel@HansenPartnership.com> <1551025819.3106.25.camel@HansenPartnership.com> <1551108969.3226.26.camel@HansenPartnership.com> <1551126043.3226.45.camel@HansenPartnership.com> <1551132882.3226.67.camel@HansenPartnership.com> <1551133927.3226.81.camel@HansenPartnership.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, 2019-02-25 at 14:43 -0800, Matthew Garrett wrote: > On Mon, Feb 25, 2019 at 2:32 PM James Bottomley > wrote: > > On Mon, 2019-02-25 at 14:24 -0800, Matthew Garrett wrote: > > > My understanding is that the crosvm USB code is intended to allow > > > arbitrary USB hardware to be passed through to the guest - doing > > > this > > > via virtio sounds complicated (you'd need a virtio driver that > > > covered every USB class, and how would you manage that for > > > devices > > > that are handled in userland at the moment), > > > > I think you'd need a virtio equivalent of the host driver, say > > xhci_virtio ... you could still use the in-kernel USB class drivers > > Mm. I honestly don't know enough about the desired use case for USB > to be able to provide meaningful input here. > > > > > Effectively it bypasses the hypervisor altogether and simply > > > > makes a direct connection to the host devices. The TPM could > > > > actually work in exactly the same way, except you'd have to use > > > > the socsim IP connection (which all TSSs support) rather than a > > > > file descriptor. > > > > > > I don't really follow - how would in-kernel TPM features work > > > then? > > > > If you do it at the TSS layer, then, of course, the kernel wouldn't > > participate. If you used the proposed in-kernel socsim driver, I > > suppose it could ... not that I'm advocating this, I'm saying if > > you want to minimise hypervisor code for attack surface reduction, > > this would be the way to do it because this solution requires no > > in-hypervisor code at all. > > You still need a transport mechanism through the hypervisor to > communicate with the host - what would you be using in that case > instead of virtio? Socsim is net transported; it's sort of the TPM equivalent of NFS or iSCSI storage for guests. James