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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 7F97DC677FC for ; Thu, 11 Oct 2018 20:17:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40C1B213A2 for ; Thu, 11 Oct 2018 20:17:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 40C1B213A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726647AbeJLDqs convert rfc822-to-8bit (ORCPT ); Thu, 11 Oct 2018 23:46:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42098 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726040AbeJLDqs (ORCPT ); Thu, 11 Oct 2018 23:46:48 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5964A1152B; Thu, 11 Oct 2018 20:17:57 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-149.rdu2.redhat.com [10.10.120.149]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8133787379; Thu, 11 Oct 2018 20:17:55 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <87sh1cqqfs.fsf@xmission.com> References: <87sh1cqqfs.fsf@xmission.com> <5c6f3d62-4cec-2aea-4693-62928611c526@gmail.com> <153754740781.17872.7869536526927736855.stgit@warthog.procyon.org.uk> <153754743491.17872.12115848333103740766.stgit@warthog.procyon.org.uk> <862e36a2-2a6f-4e26-3228-8cab4b4cf230@gmail.com> <17405.1539272035@warthog.procyon.org.uk> To: ebiederm@xmission.com (Eric W. Biederman) Cc: dhowells@redhat.com, Alan Jenkins , viro@zeniv.linux.org.uk, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mszeredi@redhat.com Subject: Re: [PATCH 03/34] teach move_mount(2) to work with OPEN_TREE_CLONE [ver #12] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <15323.1539289074.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Thu, 11 Oct 2018 21:17:54 +0100 Message-ID: <15324.1539289074@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 11 Oct 2018 20:17:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Eric W. Biederman wrote: > It should just be a matter of replacing the test > "if (p->mnt.mnt_sb->s_type == &nsfs)" with "if mnt_ns_loop(p->mnt.mnt_root)" Okay, the attached seems to work. Thanks, David --- diff --git a/fs/namespace.c b/fs/namespace.c index e969ded7d54b..5548fb9b7de2 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2388,6 +2388,27 @@ static inline int tree_contains_unbindable(struct mount *mnt) return 0; } +/* + * Object if there are any nsfs mounts in the specified subtree. These can act + * as pins for mount namespaces that aren't checked by the mount-cycle checking + * code, thereby allowing cycles to be made. + */ +static bool check_for_nsfs_mounts(struct mount *subtree) +{ + struct mount *p; + bool ret = false; + + lock_mount_hash(); + for (p = subtree; p; p = next_mnt(p, subtree)) + if (mnt_ns_loop(p->mnt.mnt_root)) + goto out; + + ret = true; +out: + unlock_mount_hash(); + return ret; +} + static int do_move_mount(struct path *old_path, struct path *new_path) { struct path parent_path = {.mnt = NULL, .dentry = NULL}; @@ -2442,6 +2463,8 @@ static int do_move_mount(struct path *old_path, struct path *new_path) if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) goto out1; err = -ELOOP; + if (!check_for_nsfs_mounts(old)) + goto out1; for (; mnt_has_parent(p); p = p->mnt_parent) if (p == old) goto out1;