From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759797Ab2HJSbs (ORCPT ); Fri, 10 Aug 2012 14:31:48 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52922 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754786Ab2HJSbq (ORCPT ); Fri, 10 Aug 2012 14:31:46 -0400 Message-ID: <5025537D.9060300@zytor.com> Date: Fri, 10 Aug 2012 11:31:25 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Alan Cox CC: Stanislav Kinsbursky , Trond.Myklebust@netapp.com, davem@davemloft.net, linux-nfs@vger.kernel.org, eric.dumazet@gmail.com, xemul@parallels.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bfields@fieldses.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> In-Reply-To: <20120810192628.79a34d28@pyramind.ukuu.org.uk> X-Enigmail-Version: 1.4.3 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 08/10/2012 11:26 AM, Alan Cox wrote: >> On that whole subject... >> >> Do we need a Unix domain socket equivalent to openat()? > > I don't think so. The name is just a file system indexing trick, it's not > really the socket proper. It's little more than "ascii string with > permissions attached" - indeed we also support an abstract name space > which for a lot of uses is actually more convenient. > I don't really understand why Unix domain sockets is different than any other pathname users in this sense. (Actually, I have never understood why open() on a Unix domain socket doesn't give the equivalent of a socket() + connect() -- it would make logical sense and would provide additional functionality). It would be different if the Unix domain sockets simply required an absolute pathname (it is not just about the root, it is also about the cwd, which is where the -at() functions come into play), but that is not the case. The abstract namespace is irrelevant for this, obviously. > AF_UNIX between roots raises some interesting semantic questions when > you begin passing file descriptors down them as well. Why is that? A file descriptor carries all that information with it... -hpa