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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C3576C43461 for ; Mon, 7 Sep 2020 10:27:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E63921473 for ; Mon, 7 Sep 2020 10:27:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728887AbgIGK1u (ORCPT ); Mon, 7 Sep 2020 06:27:50 -0400 Received: from foss.arm.com ([217.140.110.172]:60084 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728186AbgIGK10 (ORCPT ); Mon, 7 Sep 2020 06:27:26 -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 CFFFF106F; Mon, 7 Sep 2020 03:27:20 -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 7EAE33F66E; Mon, 7 Sep 2020 03:27:19 -0700 (PDT) Date: Mon, 7 Sep 2020 11:27:17 +0100 From: Dave Martin To: Boyan Karatotev Cc: Shuah Khan , boian4o1@gmail.com, Catalin Marinas , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, amit.kachhap@arm.com, vincenzo.frascino@arm.com, Will Deacon , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 3/4] kselftests/arm64: add PAuth test for whether exec() changes keys Message-ID: <20200907102717.GM6642@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <70e207ea-f7c2-2c9d-e868-3ba3b6451c6f@arm.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 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: > >> Kernel documentation states that it will change PAuth keys on exec() calls. > >> > >> Verify that all keys are correctly switched to new ones. > >> > >> Cc: Shuah Khan > >> Cc: Catalin Marinas > >> Cc: Will Deacon > >> Signed-off-by: Boyan Karatotev > >> --- [...] > >> diff --git a/tools/testing/selftests/arm64/pauth/pac.c b/tools/testing/selftests/arm64/pauth/pac.c > >> index cdbffa8bf61e..16dea47b11c7 100644 > >> --- a/tools/testing/selftests/arm64/pauth/pac.c > >> +++ b/tools/testing/selftests/arm64/pauth/pac.c [...] > >> +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... Cheers ---Dave