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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 90F60C2D0DB for ; Tue, 21 Jan 2020 15:50:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CF0D207E0 for ; Tue, 21 Jan 2020 15:50:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729410AbgAUPuk (ORCPT ); Tue, 21 Jan 2020 10:50:40 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:39912 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729345AbgAUPuj (ORCPT ); Tue, 21 Jan 2020 10:50:39 -0500 Received: from [154.119.55.246] (helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1itvnY-0004D0-LU; Tue, 21 Jan 2020 15:50:37 +0000 From: Christian Brauner To: linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Cc: Oleg Nesterov , Christian Brauner , Johannes Weiner , Li Zefan , cgroups@vger.kernel.org Subject: [PATCH v5 4/6] cgroup: add cgroup_may_write() helper Date: Tue, 21 Jan 2020 16:48:42 +0100 Message-Id: <20200121154844.411-5-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200121154844.411-1-christian.brauner@ubuntu.com> References: <20200121154844.411-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a cgroup_may_write() helper which we can use in the CLONE_INTO_CGROUP patch series to verify that we can write to the destination cgroup. Cc: Tejun Heo Cc: Johannes Weiner Cc: Li Zefan Cc: cgroups@vger.kernel.org Signed-off-by: Christian Brauner --- /* v1 */ patch not present /* v2 */ patch not present /* v3 */ patch not present /* v4 */ Link: https://lore.kernel.org/r/20200117181219.14542-5-christian.brauner@ubuntu.com patch introduced /* v5 */ unchanged --- kernel/cgroup/cgroup.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index ce2d5b8aa19f..636fe3d46d2d 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4649,13 +4649,28 @@ static int cgroup_procs_show(struct seq_file *s, void *v) return 0; } +static int cgroup_may_write(const struct cgroup *cgrp, struct super_block *sb) +{ + int ret; + struct inode *inode; + + lockdep_assert_held(&cgroup_mutex); + + inode = kernfs_get_inode(sb, cgrp->procs_file.kn); + if (!inode) + return -ENOMEM; + + ret = inode_permission(inode, MAY_WRITE); + iput(inode); + return ret; +} + static int cgroup_procs_write_permission(struct cgroup *src_cgrp, struct cgroup *dst_cgrp, struct super_block *sb) { struct cgroup_namespace *ns = current->nsproxy->cgroup_ns; struct cgroup *com_cgrp = src_cgrp; - struct inode *inode; int ret; lockdep_assert_held(&cgroup_mutex); @@ -4665,12 +4680,7 @@ static int cgroup_procs_write_permission(struct cgroup *src_cgrp, com_cgrp = cgroup_parent(com_cgrp); /* %current should be authorized to migrate to the common ancestor */ - inode = kernfs_get_inode(sb, com_cgrp->procs_file.kn); - if (!inode) - return -ENOMEM; - - ret = inode_permission(inode, MAY_WRITE); - iput(inode); + ret = cgroup_may_write(com_cgrp, sb); if (ret) return ret; -- 2.25.0