From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752824Ab2HKGYH (ORCPT ); Sat, 11 Aug 2012 02:24:07 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:11229 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751754Ab2HKGYD (ORCPT ); Sat, 11 Aug 2012 02:24:03 -0400 Message-ID: <5025FA5A.4090403@parallels.com> Date: Sat, 11 Aug 2012 10:23:22 +0400 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 MIME-Version: 1.0 To: "H. Peter Anvin" , Alan Cox , Stanislav Kinsbursky CC: "J. Bruce Fields" , "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> In-Reply-To: <50259494.8060304@zytor.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > -hpa Thanks, Pavel