Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752809AbaJMADh (ORCPT ); Sun, 12 Oct 2014 20:03:37 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:58764 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751681AbaJMADc (ORCPT ); Sun, 12 Oct 2014 20:03:32 -0400 Message-ID: <1413158605.14699.46.camel@dhcp-9-2-203-236.watson.ibm.com> Subject: Re: [tpmdd-devel] [TrouSerS-tech] [Ksummit-discuss] TPM MiniSummit @ LinuxCon Europe From: Mimi Zohar To: Andy Lutomirski Cc: Stefan Berger , keyrings@linux-nfs.org, jarkko.sakkinnen@linux.intel.com, "ksummit-discuss@lists.linuxfoundation.org" , "linux-kernel@vger.kernel.org" , LSM List , tpmdd-devel@lists.sourceforge.net, James Morris , linux-ima-devel@lists.sourceforge.net, trousers-tech@lists.sourceforge.net, Peter Huewe Date: Sun, 12 Oct 2014 20:03:25 -0400 In-Reply-To: References: <543428E1.7050702@linux.vnet.ibm.com> <20141007180209.GD10432@obsidianresearch.com> <5434352A.6080403@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4 (3.6.4-3.fc18) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14101300-0009-0000-0000-0000058D18DC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-10-07 at 11:59 -0700, Andy Lutomirski wrote: > On Tue, Oct 7, 2014 at 11:47 AM, Stefan Berger > wrote: > > On 10/07/2014 02:02 PM, Jason Gunthorpe wrote: > >> > >> On Tue, Oct 07, 2014 at 01:54:41PM -0400, Stefan Berger wrote: > >> > >>> Why add the complexity of swapping of authenticated sessions and keys > >>> into the kernel if you can handle this in userspace? You need a library > >>> that is aware of the number of key slots and slots for sessions in the > >>> TPM and swaps them in at out when applications need them. Trousers is > >>> such a library that was designed to cope with the limitations of the > >>> device and make its functionality available to all applications that > >>> want to access it. > >> > >> How does trousers work with the kernel when the kernel is also using > >> TPM key slots for IMA/keyring/whatever? > > > > > > IIRC it only uses a single key slot and swaps all keys in and out of that > > one. If the kernel was to fill up all key (and sessions) slots, TSS would > > probably not work anymore. > > > > Another argument for the TSS is that you also wouldn't want applications to > > swap out each others keys and sessions and leave them out or assume that > > they would always cleanup if they do not currently need them. > > That argument seems backwards. If you're worried about applications > (or trousers itself!) failing to clean up, then shouldn't the kernel > driver clean up orphaned key slots itself? As I understand it, this isn't an issue of "cleaning up", but of mediating the limited resources, by "swapping" keys in and out as needed. Mimi > Also, what protects the kernel from having slot 0 get stomped on or, > worse, inappropriately used by a misbehaving or malicious user > program? Is the authorization session mechanism really secure against > intentional abuse by users of the same machine? > > --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/