From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gao feng Subject: Re: [PATCH] userns: Allow the unprivileged users to mount mqueue fs Date: Mon, 28 Jan 2013 14:48:15 +0800 Message-ID: <51061F2F.6040104@cn.fujitsu.com> References: <1359342541-383-1-git-send-email-gaofeng@cn.fujitsu.com> <87bocayntu.fsf@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87bocayntu.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 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: "Eric W. Biederman" Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: containers.vger.kernel.org On 2013/01/28 11:43, Eric W. Biederman wrote: > Gao feng writes: > >> This patch allow the unprivileged user to mount mqueuefs in >> user ns. >> >> If two userns share the same ipcns,the files in mqueue fs >> should be seen in both these two userns. >> >> If the userns has its own ipcns,it has its own mqueue fs too. >> ipcns has already done this job well. > > I am a little dense. When does userspace actually mount a mqueuefs? > My impression was that user space never needed to mount and actually > never could mount a mqueuefs. MS_NO_USER isn't set so mounting a > mqueuefs is possible but when does it happen and why? > Actually the files which representative messgae queue in mqueuefs contains some informations,such as QSIZE,NOTIFY,SIGNO,NOTIFY_PID. My workstation is Fedora 17,mqueuefs is mounted on /dev/mqueue by default. So I think at lest this patch is needed by some people. Thanks! Gao > I am trying to think through the logic here and I think this is safe > but since I don't understand why we would mount an mqueue fs I am > having trouble verifying that there are no silly reasons why this might > be a bad idea. > > But from what I can tell so far this seems like a good patch. > > Eric > > >> Signed-off-by: Gao feng >> --- >> ipc/mqueue.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/ipc/mqueue.c b/ipc/mqueue.c >> index 71a3ca1..023c986 100644 >> --- a/ipc/mqueue.c >> +++ b/ipc/mqueue.c >> @@ -1383,6 +1383,7 @@ static struct file_system_type mqueue_fs_type = { >> .name = "mqueue", >> .mount = mqueue_mount, >> .kill_sb = kill_litter_super, >> + .fs_flags = FS_USERNS_MOUNT, >> }; >> >> int mq_init_ns(struct ipc_namespace *ns) > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >