From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: [CFT][PATCH 03/10] vfs: Ignore unlocked mounts in fs_fully_visible Date: Thu, 14 May 2015 12:32:37 -0500 Message-ID: <878ucrjc96.fsf@x220.int.ebiederm.org> References: <87pp63jcca.fsf@x220.int.ebiederm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87pp63jcca.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org> (Eric W. Biederman's message of "Thu, 14 May 2015 12:30:45 -0500") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Linux Containers Cc: Linux API , Greg Kroah-Hartman , Andy Lutomirski , Kenton Varda , Michael Kerrisk-manpages , Richard Weinberger , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tejun Heo List-Id: containers.vger.kernel.org Limit the mounts fs_fully_visible considers to locked mounts. Unlocked can always be unmounted so considering them adds hassle but no security benefit. Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Signed-off-by: "Eric W. Biederman" --- fs/namespace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index fccee9924e8c..3ede0669b8d2 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3211,11 +3211,15 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) 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) -- 2.2.1