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=-5.2 required=3.0 tests=BAYES_00, 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 9900BC43461 for ; Wed, 16 Sep 2020 18:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44D3D20732 for ; Wed, 16 Sep 2020 18:02:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727756AbgIPSCK (ORCPT ); Wed, 16 Sep 2020 14:02:10 -0400 Received: from foss.arm.com ([217.140.110.172]:34856 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727291AbgIPSAk (ORCPT ); Wed, 16 Sep 2020 14:00:40 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E251214BF; Wed, 16 Sep 2020 08:38:15 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 91CA13F718; Wed, 16 Sep 2020 08:38:14 -0700 (PDT) Date: Wed, 16 Sep 2020 16:38:12 +0100 From: Dave Martin To: Boyan Karatotev Cc: Boyan Karatotev , Will Deacon , Catalin Marinas , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, amit.kachhap@arm.com, vincenzo.frascino@arm.com, Shuah Khan , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 3/4] kselftests/arm64: add PAuth test for whether exec() changes keys Message-ID: <20200916153809.GZ6642@arm.com> References: <20200828131606.7946-1-boyan.karatotev@arm.com> <20200828131606.7946-4-boyan.karatotev@arm.com> <20200902170052.GJ6642@arm.com> <70e207ea-f7c2-2c9d-e868-3ba3b6451c6f@arm.com> <20200907102717.GM6642@arm.com> <4f38a974-d5a0-87e6-3db3-647e3cc32c0e@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4f38a974-d5a0-87e6-3db3-647e3cc32c0e@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 15, 2020 at 04:18:28PM +0100, Boyan Karatotev wrote: > On 07/09/2020 11:27 am, Dave Martin wrote: > > On Thu, Sep 03, 2020 at 11:20:25AM +0100, Boyan Karatotev wrote: > >> On 02/09/2020 18:00, Dave Martin wrote: > >>> On Fri, Aug 28, 2020 at 02:16:05PM +0100, Boyan Karatotev wrote: > >>>> +int exec_sign_all(struct signatures *signed_vals, size_t val) > >>>> +{ > >>> > >>> Could popen(3) be used here? > >>> > >>> Fork-and-exec is notoriously fiddly, so it's preferable to use a library > >>> function to do it where applicable.I would love to, but the worker needs a bidirectional channel and popen > >> only gives a unidirectional stream. > > > > Ah, fair point. > > > > Would it help if you created an additional pipe before calling popen()? > > > > May not be worth it, though. For one thing, wiring that extra pipe to > > stdin or stdout in the child process would require some extra work... > Well, I probably could, but I doubt the result would be any better. I > agree that I'm not sure the effort is worth it and would rather keep it > the same. Sure, fair enough. Ideally kselftest would provide some common code for this sort of thing, but I guess that's a separate discussion. Cheers ---Dave