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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D0409C3A5A0 for ; Mon, 19 Aug 2019 15:48:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF85A22CE5 for ; Mon, 19 Aug 2019 15:48:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728164AbfHSPsj (ORCPT ); Mon, 19 Aug 2019 11:48:39 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:47577 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727653AbfHSPpl (ORCPT ); Mon, 19 Aug 2019 11:45:41 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hzjqk-0006u6-NW; Mon, 19 Aug 2019 17:45:38 +0200 Message-Id: <20190819143802.144101420@linutronix.de> User-Agent: quilt/0.65 Date: Mon, 19 Aug 2019 16:31:49 +0200 From: Thomas Gleixner To: LKML Cc: Oleg Nesterov , Ingo Molnar , Peter Zijlstra , John Stultz , Frederic Weisbecker , Anna-Maria Behnsen Subject: [patch 08/44] posix-cpu-timers: Provide task validation functions References: <20190819143141.221906747@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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; + if (thread) + return same_thread_group(p, current) ? p : NULL; + if (p == current) + return p; + return has_group_leader_pid(p) ? p : NULL; +} + +static struct task_struct *__get_task_for_clock(const clockid_t clock, + bool getref) +{ + const bool thread = !!CPUCLOCK_PERTHREAD(clock); + const pid_t pid = CPUCLOCK_PID(clock); + struct task_struct *p; + + if (CPUCLOCK_WHICH(clock) >= CPUCLOCK_MAX) + return NULL; rcu_read_lock(); - p = find_task_by_vpid(pid); - if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? - same_thread_group(p, current) : has_group_leader_pid(p))) { - error = -EINVAL; - } + p = lookup_task(pid, thread); + if (p && getref) + get_task_struct(p); rcu_read_unlock(); + return p; +} - return error; +static inline struct task_struct *get_task_for_clock(const clockid_t clock) +{ + return __get_task_for_clock(clock, true); +} + +static inline int validate_clock_permissions(const clockid_t clock) +{ + return __get_task_for_clock(clock, false) ? 0 : -EINVAL; } /* @@ -125,7 +150,8 @@ static inline u64 virt_ticks(struct task static int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp) { - int error = check_clock(which_clock); + int error = validate_clock_permissions(which_clock); + if (!error) { tp->tv_sec = 0; tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ); @@ -142,20 +168,17 @@ posix_cpu_clock_getres(const clockid_t w } static int -posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp) +posix_cpu_clock_set(const clockid_t clock, const struct timespec64 *tp) { + int error = validate_clock_permissions(clock); + /* * You can never reset a CPU clock, but we check for other errors * in the call before failing with EPERM. */ - int error = check_clock(which_clock); - if (error == 0) { - error = -EPERM; - } - return error; + return error ? : -EPERM; } - /* * Sample a per-thread clock for the given task. */