From patchwork Fri Aug 13 15:07:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 497435 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 D3988C4320A for ; Fri, 13 Aug 2021 15:14:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE94161131 for ; Fri, 13 Aug 2021 15:14:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241872AbhHMPOt (ORCPT ); Fri, 13 Aug 2021 11:14:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:53104 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242286AbhHMPNt (ORCPT ); Fri, 13 Aug 2021 11:13:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A2F2B6112F; Fri, 13 Aug 2021 15:13:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1628867594; bh=l3FbYfO0WriBgfC4cxzcPJhwLD20Rl43IQrV7LR5xqc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h9MaSLGK4DdOt6STe6Bcil4hAsld971C6sq/6hOXpEi71+28P7/0ujnNSkdemVqrX TycrA9yVEAHXs40lZMZtpaLHh7QjlPL/Mucaampsc3At8Utqd8OGLeKn8ep7+APsDz f5XQlo5ywDV6r9ArCVq/SYhrt2AWGKRK7zer5nZs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alois Wohlschlager , Miklos Szeredi Subject: [PATCH 5.4 16/27] ovl: prevent private clone if bind mount is not allowed Date: Fri, 13 Aug 2021 17:07:14 +0200 Message-Id: <20210813150523.896203260@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210813150523.364549385@linuxfoundation.org> References: <20210813150523.364549385@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Miklos Szeredi commit 427215d85e8d1476da1a86b8d67aceb485eb3631 upstream. Add the following checks from __do_loopback() to clone_private_mount() as well: - verify that the mount is in the current namespace - verify that there are no locked children Reported-by: Alois Wohlschlager Fixes: c771d683a62e ("vfs: introduce clone_private_mount()") Cc: # v3.18 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/namespace.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1861,6 +1861,20 @@ void drop_collected_mounts(struct vfsmou namespace_unlock(); } +static bool has_locked_children(struct mount *mnt, struct dentry *dentry) +{ + struct mount *child; + + list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { + if (!is_subdir(child->mnt_mountpoint, dentry)) + continue; + + if (child->mnt.mnt_flags & MNT_LOCKED) + return true; + } + return false; +} + /** * clone_private_mount - create a private clone of a path * @@ -1875,14 +1889,27 @@ struct vfsmount *clone_private_mount(con struct mount *old_mnt = real_mount(path->mnt); struct mount *new_mnt; + down_read(&namespace_sem); if (IS_MNT_UNBINDABLE(old_mnt)) - return ERR_PTR(-EINVAL); + goto invalid; + + if (!check_mnt(old_mnt)) + goto invalid; + + if (has_locked_children(old_mnt, path->dentry)) + goto invalid; new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); + up_read(&namespace_sem); + if (IS_ERR(new_mnt)) return ERR_CAST(new_mnt); return &new_mnt->mnt; + +invalid: + up_read(&namespace_sem); + return ERR_PTR(-EINVAL); } EXPORT_SYMBOL_GPL(clone_private_mount); @@ -2234,19 +2261,6 @@ static int do_change_type(struct path *p return err; } -static bool has_locked_children(struct mount *mnt, struct dentry *dentry) -{ - struct mount *child; - list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { - if (!is_subdir(child->mnt_mountpoint, dentry)) - continue; - - if (child->mnt.mnt_flags & MNT_LOCKED) - return true; - } - return false; -} - static struct mount *__do_loopback(struct path *old_path, int recurse) { struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt);