From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Kleikamp Subject: Re: [RFC][PATCH] ensure i_ino uniqueness in filesystems without permanent inode numbers (via pointer conversion) Date: Fri, 17 Nov 2006 09:01:25 -0600 Message-ID: <1163775685.17280.13.camel@kleikamp.austin.ibm.com> References: <1163770980.13410.39.camel@dantu.rdu.redhat.com> <20061117142435.GC18567@parisc-linux.org> <1163774903.13410.68.camel@dantu.rdu.redhat.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Matthew Wilcox , linux-fsdevel@vger.kernel.org Return-path: Received: from e36.co.us.ibm.com ([32.97.110.154]:11923 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S933638AbWKQPBd (ORCPT ); Fri, 17 Nov 2006 10:01:33 -0500 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e36.co.us.ibm.com (8.13.8/8.12.11) with ESMTP id kAHF1RoC004375 for ; Fri, 17 Nov 2006 10:01:27 -0500 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay04.boulder.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id kAHF1QmB274662 for ; Fri, 17 Nov 2006 08:01:27 -0700 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id kAHF1Qc7018025 for ; Fri, 17 Nov 2006 08:01:26 -0700 To: Jeff Layton In-Reply-To: <1163774903.13410.68.camel@dantu.rdu.redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, 2006-11-17 at 09:48 -0500, Jeff Layton wrote: > On Fri, 2006-11-17 at 07:24 -0700, Matthew Wilcox wrote: > > I *think* the xor mask is mere obfuscation. It looks likely that you can > > recover it with a little bit of trial and error. If you can force the > > filesystem to hand you back new inodes quickly such that there is a high > > probability you get consecutive allocations, you'll get a sequence which > > would be spaced 700-odd bytes apart, except that it's been xored. Since > > you know it's incrementing, if you see the sequence decrease, you'll > > know that was a 1 in that bit. > > I think you're right, the addresses would often be sequential, so this > is probably crackable. Wouldn't you only be able to only crack a few of the low-order bits due to a cluster of inodes being sequential? I don't think you'd be able crack enough of it to be useful. You may be able to determine where some inodes are relative to others, but I don't think you'd be able to point the their location in memory. I don't know anything about crypto, so I could be wrong. > I'll look over the md5 routines when I get the > chance, though if someone more cryptographically inclined than I has a > different suggestion, I'd love to hear it. > -- Jeff Shaggy -- David Kleikamp IBM Linux Technology Center