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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 44D3BC3A5A1 for ; Wed, 28 Aug 2019 10:16:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23896217F5 for ; Wed, 28 Aug 2019 10:16:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726439AbfH1KQY (ORCPT ); Wed, 28 Aug 2019 06:16:24 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:46343 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726246AbfH1KQX (ORCPT ); Wed, 28 Aug 2019 06:16:23 -0400 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1i2uzz-0000AP-EV; Wed, 28 Aug 2019 12:16:19 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 173901C07D2; Wed, 28 Aug 2019 12:16:19 +0200 (CEST) Date: Wed, 28 Aug 2019 10:16:18 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/core] posix-cpu-timers: Provide task validation functions Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , linux-kernel@vger.kernel.org In-Reply-To: <20190821192919.326097175@linutronix.de> References: <20190821192919.326097175@linutronix.de> MIME-Version: 1.0 Message-ID: <156698737894.5680.10697132030534215507.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the timers/core branch of tip: Commit-ID: 6ae40e3fdcd33a6ff3c490b9302d6a1861093f65 Gitweb: https://git.kernel.org/tip/6ae40e3fdcd33a6ff3c490b9302d6a1861093f65 Author: Thomas Gleixner AuthorDate: Wed, 21 Aug 2019 21:08:48 +02:00 Committer: Thomas Gleixner CommitterDate: Wed, 28 Aug 2019 11:50:24 +02:00 posix-cpu-timers: Provide task validation functions 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 Link: https://lkml.kernel.org/r/20190821192919.326097175@linutronix.de --- kernel/time/posix-cpu-timers.c | 65 ++++++++++++++++++++++----------- 1 file changed, 44 insertions(+), 21 deletions(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 387e0e8..b06ed8b 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -35,27 +35,52 @@ void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) 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; + + 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 (pid == 0) - return 0; + 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_struct *p) 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 which_clock, struct timespec64 *tp) } 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. */