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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 18AADC3A59E for ; Wed, 21 Aug 2019 22:34:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF8322339E for ; Wed, 21 Aug 2019 22:34:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566426843; bh=FhOdoG+uEuNHTTDbXbY6PhmljoTde5UcyxI0dUGbGzQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=rPEikNw8aPXMB1qDfB4qWQT6U3PZ33SndFv90aZihpFIEQ3FMyw4WWoQ+jQHD9Nti qVnxD6HV6QUmwc1GC0D9wEVQtPce0fpyeoFUyQwBWG+ZNc58AMictih5jjSzUm7Y73 LjWrkjzD9mQzORYKOqmoC82NGeOHm/v9gnnnst/8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731084AbfHUWeB (ORCPT ); Wed, 21 Aug 2019 18:34:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:55828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729090AbfHUWeB (ORCPT ); Wed, 21 Aug 2019 18:34:01 -0400 Received: from localhost (lfbn-ncy-1-174-150.w83-194.abo.wanadoo.fr [83.194.254.150]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C223D2332A; Wed, 21 Aug 2019 22:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566426840; bh=FhOdoG+uEuNHTTDbXbY6PhmljoTde5UcyxI0dUGbGzQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tpcOoxbyCTO6OSPIk4s4E2UpgZeFQ8vkv4gGyDGHcZblGTO1LITs2QVeZuWns9jgZ Yi9WeMrSwxLt/fH2vkrmemWxZGdFFInP+wcCL9ef6y2KV+4ZnKhflgzcXWkPV2fP/v CK7FZ3lJ5A6ULzhIRV0uQT/3wC2HrQpblirbrWBM= Date: Thu, 22 Aug 2019 00:33:57 +0200 From: Frederic Weisbecker To: Thomas Gleixner Cc: LKML , Oleg Nesterov , Ingo Molnar , Peter Zijlstra , John Stultz , Anna-Maria Behnsen , Christoph Hellwig Subject: Re: [patch V2 01/38] posix-cpu-timers: Provide task validation functions Message-ID: <20190821223356.GC22020@lenoir> References: <20190821190847.665673890@linutronix.de> <20190821192919.326097175@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190821192919.326097175@linutronix.de> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 21, 2019 at 09:08:48PM +0200, Thomas Gleixner wrote: > The code contains three slightly different copies of validating whether a > given clock resolves to a valid task and whether the current caller has > permissions to access it. > > Create central functions. Replace check_clock() as a first step and rename > it to something sensible. > > Signed-off-by: Thomas Gleixner > --- > kernel/time/posix-cpu-timers.c | 65 +++++++++++++++++++++++++++-------------- > 1 file changed, 44 insertions(+), 21 deletions(-) > > --- a/kernel/time/posix-cpu-timers.c > +++ b/kernel/time/posix-cpu-timers.c > @@ -35,27 +35,52 @@ void update_rlimit_cpu(struct task_struc > spin_unlock_irq(&task->sighand->siglock); > } > > -static int check_clock(const clockid_t which_clock) > +/* > + * Functions for validating access to tasks. > + */ > +static struct task_struct *lookup_task(const pid_t pid, bool thread) > { > - int error = 0; > struct task_struct *p; > - const pid_t pid = CPUCLOCK_PID(which_clock); > > - if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) > - return -EINVAL; > + if (!pid) > + return thread ? current : current->group_leader; > > - if (pid == 0) > - return 0; > + p = find_task_by_vpid(pid); > + if (!p || p == current) > + return p; What if (p == current && !thread && !has_group_leader_pid(p)) ? > + if (thread) > + return same_thread_group(p, current) ? p : NULL; > + if (p == current) > + return p; You already checked that above. > + return has_group_leader_pid(p) ? p : NULL; > +}