From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:43180 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933928AbbGHHgb (ORCPT ); Wed, 8 Jul 2015 03:36:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Eric W. Biederman" Subject: [PATCH 4.0 55/55] vfs: Ignore unlocked mounts in fs_fully_visible Date: Wed, 8 Jul 2015 00:35:30 -0700 Message-Id: <20150708073241.889309341@linuxfoundation.org> In-Reply-To: <20150708073238.785749886@linuxfoundation.org> References: <20150708073238.785749886@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: stable-owner@vger.kernel.org List-ID: 4.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" commit ceeb0e5d39fcdf4dca2c997bf225c7fc49200b37 upstream. Limit the mounts fs_fully_visible considers to locked mounts. Unlocked can always be unmounted so considering them adds hassle but no security benefit. Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman --- fs/namespace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3187,11 +3187,15 @@ bool fs_fully_visible(struct file_system if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) continue; - /* This mount is not fully visible if there are any child mounts - * that cover anything except for empty directories. + /* This mount is not fully visible if there are any + * locked child mounts that cover anything except for + * empty directories. */ list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { struct inode *inode = child->mnt_mountpoint->d_inode; + /* Only worry about locked mounts */ + if (!(mnt->mnt.mnt_flags & MNT_LOCKED)) + continue; if (!S_ISDIR(inode->i_mode)) goto next; if (inode->i_nlink > 2)