Return-Path: linux-nfs-owner@vger.kernel.org Received: from relay.parallels.com ([195.214.232.42]:51139 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750861Ab2HMRj7 convert rfc822-to-8bit (ORCPT ); Mon, 13 Aug 2012 13:39:59 -0400 Message-ID: <50293BE9.3010408@parallels.com> Date: Mon, 13 Aug 2012 21:39:53 +0400 From: Stanislav Kinsbursky MIME-Version: 1.0 To: "J. Bruce Fields" CC: Pavel Emelianov , "H. Peter Anvin" , Alan Cox , "Trond.Myklebust@netapp.com" , "davem@davemloft.net" , "linux-nfs@vger.kernel.org" , "eric.dumazet@gmail.com" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "viro@zeniv.linux.org.uk" , "tim.c.chen@linux.intel.com" , "devel@openvz.org" Subject: Re: [RFC PATCH 0/2] net: connect to UNIX sockets from specified root References: <20120810125701.7115.71612.stgit@localhost.localdomain> <50254FA6.3060806@zytor.com> <20120810192628.79a34d28@pyramind.ukuu.org.uk> <20120810191149.GA17985@fieldses.org> <20120810202818.06236f46@pyramind.ukuu.org.uk> <50259494.8060304@zytor.com> <5025FA5A.4090403@parallels.com> <50263ECC.4060501@parallels.com> <20120813164730.GB2497@fieldses.org> In-Reply-To: <20120813164730.GB2497@fieldses.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: 13.08.2012 20:47, J. Bruce Fields пишет: > On Sat, Aug 11, 2012 at 03:15:24PM +0400, Stanislav Kinsbursky wrote: >> 11.08.2012 10:23, Pavel Emelyanov пишет: >>> On 08/11/2012 03:09 AM, H. Peter Anvin wrote: >>>> On 08/10/2012 12:28 PM, Alan Cox wrote: >>>>> Explicitly for Linux yes - this is not generally true of the AF_UNIX >>>>> socket domain and even the permissions aspect isn't guaranteed to be >>>>> supported on some BSD environments ! >>>> Yes, but let's worry about what the Linux behavior should be. >>>> >>>>> The name is however just a proxy for the socket itself. You don't even >>>>> get a device node in the usual sense or the same inode in the file system >>>>> space. >>>> No, but it is looked up the same way any other inode is (the difference >>>> between FIFOs and sockets is that sockets have separate connections, >>>> which is also why open() on sockets would be nice.) >>>> >>>> However, there is a fundamental difference between AF_UNIX sockets and >>>> open(), and that is how the pathname is delivered. It thus would make >>>> more sense to provide the openat()-like information in struct >>>> sockaddr_un, but that may be very hard to do in a sensible way. In that >>>> sense it perhaps would be cleaner to be able to do an open[at]() on the >>>> socket node with O_PATH (perhaps there should be an O_SOCKET option, >>>> even?) and pass the resulting file descriptor to bind() or connect(). >>> I vote for this (openat + O_WHATEVER on a unix socket) as well. It will >>> help us in checkpoint-restore, making handling of overmounted/unlinked >>> sockets much cleaner. >> I have to notice, that it's not enough and doesn't solve the issue. >> There should be some way how to connect/bind already existent unix >> socket (from kernel, at least), because socket can be created in >> user space. >> And this way (sock operation or whatever) have to provide an ability >> to lookup UNIX socket starting from specified root to support >> containers. > I don't understand--the rpcbind sockets are created by the kernel. What > am I missing? Kernel preform connect to rpcbind socket (i.e. user-space binds it), doesn't it? > > --b.