From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hr2.samba.org ([144.76.82.148]:51728 "EHLO hr2.samba.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726826AbeH0V3F (ORCPT ); Mon, 27 Aug 2018 17:29:05 -0400 Date: Mon, 27 Aug 2018 10:41:21 -0700 From: Jeremy Allison To: Steve French , linux-fsdevel , ebiggers@kernel.org, samba-technical , Al Viro , Matthew Wilcox Subject: Re: Streams support in Linux Message-ID: <20180827174121.GD217636@jra3> Reply-To: Jeremy Allison References: <20180825135107.GA12251@bombadil.infradead.org> <20180825144745.GQ6515@ZenIV.linux.org.uk> <20180825155150.GA3581@bombadil.infradead.org> <20180825180026.GR6515@ZenIV.linux.org.uk> <20180825205716.GA2664@bombadil.infradead.org> <20180825223615.GS6515@ZenIV.linux.org.uk> <20180827170531.GC217636@jra3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180827170531.GC217636@jra3> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Aug 27, 2018 at 10:05:31AM -0700, Jeremy Allison via samba-technical wrote: > On Sat, Aug 25, 2018 at 08:03:03PM -0500, Steve French via samba-technical wrote: > > On Sat, Aug 25, 2018 at 5:37 PM Al Viro via samba-technical > > > > > > Better yet, you need some new objects to represent those things, since > > > you don't want any informative dentries. And not fs-private ones, at > > > that, since those new syscalls of yours would have to operate on them > > > (after all, renaming something opened would probably be expected to > > > have the opened descriptor to keep accessing the same object, wouldn't > > > it?) > > > > These are interesting questions, and there are cases where streams > > have been shown to have value in Windows, and for Apple (in Macs). > > Don't know whether the Solaris equivalent was useful - but presumably > > was. > > Sorry Steve, can't let this pass :-). Please name *one* case > where streams have value in Windows or Mac. And I'm not talking > about the case for EA's, these clearly have value (plus we already > have them :-). > > I'm talking about a case where there is clear value in having > an openable/seekable stream on a file/directory. > > I can't think of a *single* case where a stream adds more > utility than an EA used in the same case. > > I don't want theoretical "well it would be nice if..", > I want clear "we couldn't have done it any other way" > kinds of things. Actually, to answer my own question, I do know of one valid application that uses named streams. The CIA exfiltration tools exposed by WikiLeaks used a named stream on a top-level share directory to hide data being stolen from the target (which is why I guess the CIA doesn't employ NSA-level people, the NSA almost certainly use the hidden data area behind Windows ACL store instead as no known scanning tools look at that :-). So if we really want to enable such things, by all means add named streams to Linux :-) :-).