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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 9DB56C433DB for ; Sun, 17 Jan 2021 14:33:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65B80207FB for ; Sun, 17 Jan 2021 14:33:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728616AbhAQOdG (ORCPT ); Sun, 17 Jan 2021 09:33:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:52108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726209AbhAQOdA (ORCPT ); Sun, 17 Jan 2021 09:33:00 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0114320791; Sun, 17 Jan 2021 14:32:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610893939; bh=fC0xE+/aPbZTMKCRNvqaATbwzFKoHIbiqX9FSPt4u/I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fmuP7loAyQwV1D2OBPwxl3wTMhCZPRoYa/4OYT7GQWfDFkWIZdT2fWzqSFLt/chhS tjc4+LcY8n3iMen51+6MqG0oHNplwibBiLErIkwCu5Ga2U1FroDqPa0JGPPY68Hj1q cw+3v4amhdLZaxDjL6tBXBpqWYTrMlcuz9XfVij4= Date: Sun, 17 Jan 2021 15:32:17 +0100 From: Greg Kroah-Hartman To: Wei Liu Cc: Randy Dunlap , Linux Kernel List , tyhicks@linux.microsoft.com, "Michael S. Tsirkin" , Jason Wang , Thomas Gleixner , Arnd Bergmann , Christian Gromm Subject: Re: [PATCH] fTPM: make sure TEE is initialized before fTPM Message-ID: References: <20210116001301.16861-1-wei.liu@kernel.org> <20210116115529.oq2k2qpgyawngcqn@liuwe-devbox-debian-v2> <20210116121109.xenpxbobni4glecg@liuwe-devbox-debian-v2> <20210117142127.vqgrfzld42sfsylb@liuwe-devbox-debian-v2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210117142127.vqgrfzld42sfsylb@liuwe-devbox-debian-v2> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 17, 2021 at 02:21:27PM +0000, Wei Liu wrote: > On Sun, Jan 17, 2021 at 09:29:42AM +0100, Greg Kroah-Hartman wrote: > > On Sat, Jan 16, 2021 at 12:11:09PM +0000, Wei Liu wrote: > > > On Sat, Jan 16, 2021 at 11:55:29AM +0000, Wei Liu wrote: > > > > On Fri, Jan 15, 2021 at 04:49:57PM -0800, Randy Dunlap wrote: > > > > > Hi, > > > > > > > > > > On 1/15/21 4:12 PM, Wei Liu wrote: > > > > > > For built-in drivers, the order of initialization function invocation is > > > > > > determined by their link order. > > > > > > > > > > > > The original code linked TPM drivers before TEE driver when they were > > > > > > both built in. That caused fTPM's initialization to be deferred to a > > > > > > worker thread instead of running on PID 1. > > > > > > > > > > > > That is problematic because IMA's initialization routine, which runs on > > > > > > PID 1 as a late initcall, needs to have access to the default TPM > > > > > > instance. If fTPM's initialization is deferred, IMA will not be able to > > > > > > get hold of a TPM instance in time. > > > > > > > > > > > > Fix this by modifying Makefile to make sure TEE is initialized before > > > > > > fTPM when they are both built in. > > > > > > > > > > > > Signed-off-by: Wei Liu > > > > > > --- > > > > > > drivers/Makefile | 5 +++++ > > > > > > 1 file changed, 5 insertions(+) > > > > > > > > > > > > diff --git a/drivers/Makefile b/drivers/Makefile > > > > > > index fd11b9ac4cc3..45ea5ec9d0fd 100644 > > > > > > --- a/drivers/Makefile > > > > > > +++ b/drivers/Makefile > > > > > > @@ -180,6 +180,11 @@ obj-$(CONFIG_NVMEM) += nvmem/ > > > > > > obj-$(CONFIG_FPGA) += fpga/ > > > > > > obj-$(CONFIG_FSI) += fsi/ > > > > > > obj-$(CONFIG_TEE) += tee/ > > > > > > + > > > > > > +# TPM drivers must come after TEE, otherwise fTPM initialization will be > > > > > > +# deferred, which causes IMA to not get a TPM device in time > > > > > > +obj-$(CONFIG_TCG_TPM) += char/tpm/ > > > > > > + > > > > > > obj-$(CONFIG_MULTIPLEXER) += mux/ > > > > > > obj-$(CONFIG_UNISYS_VISORBUS) += visorbus/ > > > > > > obj-$(CONFIG_SIOX) += siox/ > > > > > > > > > > > > > > > > As I suspected and then tested, since you did not remove the other build > > > > > of char/tpm/, this ends up with multiple definition linker errors (below). > > > > > > > > Oops, I didn't commit the hunk that removed the line in char/Makefile. > > > > > > > > But I will hold off sending out v2 until the following discussion is > > > > settled. > > > > > > > > > > > > > > I would think that instead of depending on Makefile order you should use different > > > > > initcall levels as needed. Depending on Makefile order is what we did 15 years ago. > > > > > > > > > > > > > No, not really. The same trick was used in 2014 (1bacc894c227). > > > > > > > > Both TEE and TPM are just drivers. I think they belong to the same level > > > > (at the moment device_initcall). Looking at the list of levels, I'm not > > > > sure how I can move TEE to a different level. > > > > > > > > Out of the seven levels, which one would you suggest I use for which > > > > driver? > > > > > > A bit more random thought. > > > > > > Moving one driver to a different level is not the solution either. What > > > if there is a dependency chain in the future in which more than 2 > > > drivers are involved? Do we invent more levels or abuse levels that > > > aren't supposed to be used by device drivers? > > > > > > The proper solution to me is to somehow sort the initcalls with their > > > dependencies in mind. The requires quite a bit of engineering > > > (integrating depmod into kernel build?). Given that there are only a few > > > cases, I don't think effort would be worth it. > > > > Make it an explicit dependancy in the driver, and then things will be > > loaded properly. > > I take it you mean using MODULE_SOFTDEP to do that? That's one way, or just explicitly depend on a symbol in the other module. > > You can always defer your probe if you do not have all > > of the proper resources, which is how these types of things are handled, > > instead of worrying about creating new init levels. > > > fTPM's probe is already deferred in current Linux without this patch. What patch? > It > will eventually show up in Linux but at that point it is too late for > Linux's Integrity Measurement Architecture to use it. How can it be "too late"? > The probe getting deferred is exactly what I tried to avoid here. :-) Then don't start up IMA without it? I really don't know, but this feels like something is broken in your module... thanks, greg k-h