From patchwork Wed Jul 6 05:21:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 12907330 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C217EC43334 for ; Wed, 6 Jul 2022 05:23:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231359AbiGFFXi (ORCPT ); Wed, 6 Jul 2022 01:23:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231349AbiGFFX0 (ORCPT ); Wed, 6 Jul 2022 01:23:26 -0400 Received: from smtp-fw-2101.amazon.com (smtp-fw-2101.amazon.com [72.21.196.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4396DE6; Tue, 5 Jul 2022 22:23:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1657085004; x=1688621004; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jh0a+absz9pAb5bIlORUQ/Q1+4cClz2C63wKgA8hG5I=; b=orhJLYQcJiu/kREOpdVNW9a8I2XTwrjwMVg7EZmQu+6wdjdUfAtKcIdF bK12O0bJBf47CLArOqMGig8yFS1mBNeqElC9ryjy7cRd5ta+LaqKiLjrL bPRc4/qvbqjP6H/RN8Z8hQC+EsIz2FI1VPB0Fgs3uq4vcE27KXFMO2fvE Y=; X-IronPort-AV: E=Sophos;i="5.92,248,1650931200"; d="scan'208";a="215167206" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-pdx-2c-90419278.us-west-2.amazon.com) ([10.43.8.2]) by smtp-border-fw-2101.iad2.amazon.com with ESMTP; 06 Jul 2022 05:23:11 +0000 Received: from EX13MTAUWB001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-pdx-2c-90419278.us-west-2.amazon.com (Postfix) with ESMTPS id 4BA3644103; Wed, 6 Jul 2022 05:23:11 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX13MTAUWB001.ant.amazon.com (10.43.161.207) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Wed, 6 Jul 2022 05:23:10 +0000 Received: from 88665a182662.ant.amazon.com (10.43.162.55) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1118.9; Wed, 6 Jul 2022 05:23:08 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Luis Chamberlain , Kees Cook , Iurii Zaikin CC: Kuniyuki Iwashima , Kuniyuki Iwashima , , Subject: [PATCH v1 net 06/16] sysctl: Add proc_douintvec_minmax_lockless(). Date: Tue, 5 Jul 2022 22:21:20 -0700 Message-ID: <20220706052130.16368-7-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220706052130.16368-1-kuniyu@amazon.com> References: <20220706052130.16368-1-kuniyu@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.162.55] X-ClientProxiedBy: EX13D18UWA004.ant.amazon.com (10.43.160.45) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org A sysctl variable is accessed concurrently, and there is always a chance of data-race. So, all readers and writers need some basic protection to avoid load/store-tearing. This patch changes proc_douintvec_minmax() to use READ_ONCE()/WRITE_ONCE() internally to fix a data-race on the sysctl side. For now, proc_douintvec_minmax() itself is tolerant to a data-race, but we still need to add annotations on the other subsystem's side. In case we miss such fixes, this patch converts proc_douintvec_minmax() to a wrapper of proc_douintvec_minmax_lockless(). When we fix a data-race in the other subsystem, we can explicitly set it as a handler. Also, this patch removes proc_douintvec_minmax()'s document and adds proc_douintvec_minmax_lockless()'s one so that no one will use proc_douintvec_minmax() anymore. Fixes: 61d9b56a8920 ("sysctl: add unsigned int range support") Signed-off-by: Kuniyuki Iwashima --- CC: Luis R. Rodriguez --- include/linux/sysctl.h | 1 + kernel/sysctl.c | 17 +++++++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 7f91cc625d56..830d1a8f21d4 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -87,6 +87,7 @@ PROC_HANDLER(proc_dobool_lockless); PROC_HANDLER(proc_dointvec_lockless); PROC_HANDLER(proc_douintvec_lockless); PROC_HANDLER(proc_dointvec_minmax_lockless); +PROC_HANDLER(proc_douintvec_minmax_lockless); /* * Register a set of sysctl names by calling register_sysctl_table diff --git a/kernel/sysctl.c b/kernel/sysctl.c index aead731ae74b..8ff57b8d1212 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -954,14 +954,15 @@ static int do_proc_douintvec_minmax_conv(unsigned long *lvalp, (param->max && *param->max < tmp)) return -ERANGE; - *valp = tmp; + WRITE_ONCE(*valp, tmp); } return 0; } /** - * proc_douintvec_minmax - read a vector of unsigned ints with min/max values + * proc_douintvec_minmax_lockless - read/write a vector of unsigned ints + * with min/max values locklessly * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer @@ -979,8 +980,8 @@ static int do_proc_douintvec_minmax_conv(unsigned long *lvalp, * * Returns 0 on success or -ERANGE on write when the range check fails. */ -int proc_douintvec_minmax(struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos) +int proc_douintvec_minmax_lockless(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) { struct do_proc_douintvec_minmax_conv_param param = { .min = (unsigned int *) table->extra1, @@ -990,6 +991,12 @@ int proc_douintvec_minmax(struct ctl_table *table, int write, do_proc_douintvec_minmax_conv, ¶m); } +int proc_douintvec_minmax(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + return proc_douintvec_minmax_lockless(table, write, buffer, lenp, ppos); +} + /** * proc_dou8vec_minmax - read a vector of unsigned chars with min/max values * @table: the sysctl table @@ -1532,6 +1539,7 @@ PROC_HANDLER_ENOSYS(proc_dobool_lockless); PROC_HANDLER_ENOSYS(proc_dointvec_lockless); PROC_HANDLER_ENOSYS(proc_douintvec_lockless); PROC_HANDLER_ENOSYS(proc_dointvec_minmax_lockless); +PROC_HANDLER_ENOSYS(proc_douintvec_minmax_lockless); #endif /* CONFIG_PROC_SYSCTL */ @@ -2446,3 +2454,4 @@ EXPORT_SYMBOL(proc_dobool_lockless); EXPORT_SYMBOL(proc_dointvec_lockless); EXPORT_SYMBOL(proc_douintvec_lockless); EXPORT_SYMBOL(proc_dointvec_minmax_lockless); +EXPORT_SYMBOL_GPL(proc_douintvec_minmax_lockless);