From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-security-module@vger.kernel.org,
tpmdd-devel@lists.sourceforge.net,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager
Date: Tue, 03 Jan 2017 08:36:10 -0800 [thread overview]
Message-ID: <1483461370.2464.19.camel@HansenPartnership.com> (raw)
In-Reply-To: <20170103135121.4kh3jld5gaq3ptj4@intel.com>
On Tue, 2017-01-03 at 15:51 +0200, Jarkko Sakkinen wrote:
> On Mon, Jan 02, 2017 at 01:40:48PM -0800, James Bottomley wrote:
> > On Mon, 2017-01-02 at 21:33 +0200, Jarkko Sakkinen wrote:
> > > On Mon, Jan 02, 2017 at 08:36:20AM -0800, James Bottomley wrote:
> > > > On Mon, 2017-01-02 at 15:22 +0200, Jarkko Sakkinen wrote:
> > > > > This patch set adds support for TPM spaces that provide a
> > > > > context for isolating and swapping transient objects. This
> > > > > patch set does not yet include support for isolating policy
> > > > > and HMAC sessions but it is trivial to add once the basic
> > > > > approach is settled (and that's why I created an RFC patch
> > > > > set).
> > > >
> > > > The approach looks fine to me. The only basic query I have is
> > > > about the default: shouldn't it be with resource manager on
> > > > rather than off? I can't really think of a use case that wants
> > > > the RM off (even if you're running your own, having another
> > > > doesn't hurt anything, and it's still required to share with in
> > > > -kernel uses).
> > >
> > > This is a valid question and here's a longish explanation.
> > >
> > > In TPM2_GetCapability and maybe couple of other commands you can
> > > get handles in the response body. I do not want to have special
> > > cases in the kernel for response bodies because there is no a
> > > generic way to do the substitution. What's worse, new commands in
> > > the standard future revisions could have such commands requiring
> > > special cases. In addition, vendor specific commans could have
> > > handles in the response bodies.
> >
> > OK, in general I buy this ... what you're effectively saying is
> > that we need a non-RM interface for certain management type
> > commands.
>
> Not only that.
>
> Doing virtualization for commands like GetCapability is just a better
> fit for doing in the user space. You could have a thin translation
> layer in your TSS library for example to handle these specific
> messages.
Yes, we could do it that way too. To be honest I can't see much use
for getting the transient handles and all the other handles you'd be
interested in aren't virtualized.
> > However, let me expand a bit on why I'm fretting about the non-RM
> > use case. Right at the moment, we have a single TPM device which
> > you use for access to the kernel TPM. The current tss2 just makes
> > direct use of this, meaning it has to have 0666 permissions. This
> > means that any local user can simply DoS the TPM by running us out
> > of transient resources if they don't activate the RM. If they get
> > a connection always via the RM, this isn't a worry. Perhaps the
> > best way of fixing this is to expose two separate device nodes: one
> > raw to the TPM which we could keep at 0600 and one with an always
> > RM connection which we can set to 0666. That would mean that
> > access to the non-RM connection is either root only or governed by
> > a system set ACL.
>
> I'm not sure about this. Why you couldn't have a very thin daemon
> that prepares the file descriptor and sends it through UDS socket to
> a client.
So I'm a bit soured on daemons from the trousers experience: tcsd
crashed regularly and when it did it took all the TPM connections down
irrecoverably. I'm not saying we can't write a stateless daemon to fix
most of the trousers issues, but I think it's valuable first to ask the
question, "can we manage without a daemon at all?" I actually think
the answer is "yes", so I'm interested in seeing how far that line of
research gets us.
> The non-RFC version will also have whitelisting ioctl for
> further restricting the file descriptor to only specific TPM
> commands.
>
> This is also architecture I preseted in my LSS presentation and I
> think it makes sense especially when I add the whitelisting to the
> pack.
Do you have a link to the presentation? The Plumbers etherpad doesn't
contain it. I've been trying to work out whether a properly set up TPM
actually does need any protections at all. As far as I can tell, once
you've set all the hierarchy authorities and the lockout one, you're
pretty well protected.
> > James
>
> I'm more dilated to keep things way they are now. I'll stick to that
> at least with the first non-RFC version and hopefully get the tpm2
> -space.c part reviewed as I split that stuff to a separate commit.
Sure, we need the patch in an acceptable form first. I'll keep
worrying about the systems implications, but I can layer playing with
those on top of what you do.
James
next prev parent reply other threads:[~2017-01-03 16:37 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-02 13:22 [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen
2017-01-02 13:22 ` [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Jarkko Sakkinen
2017-01-02 21:01 ` Jason Gunthorpe
2017-01-03 0:57 ` Jarkko Sakkinen
2017-01-03 19:13 ` Jason Gunthorpe
2017-01-04 12:29 ` Jarkko Sakkinen
2017-01-02 13:22 ` [PATCH RFC 2/4] tpm: validate TPM 2.0 commands Jarkko Sakkinen
[not found] ` <OF8D508BD2.EAB22BFD-ON0025809E.0062B40C-8525809E.006356C3@notes.na.collabserv.com>
2017-01-04 18:19 ` [tpmdd-devel] " James Bottomley
2017-01-04 18:44 ` Jason Gunthorpe
2017-01-02 13:22 ` [PATCH RFC 3/4] tpm: export tpm2_flush_context_cmd Jarkko Sakkinen
2017-01-02 13:22 ` [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for TPM 2.0 Jarkko Sakkinen
2017-01-02 21:09 ` Jason Gunthorpe
2017-01-03 0:37 ` Jarkko Sakkinen
2017-01-03 18:46 ` Jason Gunthorpe
2017-01-04 12:43 ` Jarkko Sakkinen
2017-01-03 19:16 ` Jason Gunthorpe
2017-01-04 12:45 ` Jarkko Sakkinen
[not found] ` <OF9C3EE9AE.65978870-ON0025809E.0061E7AF-8525809E.0061FFDA@notes.na.collabserv.com>
2017-01-09 22:11 ` [tpmdd-devel] " Jarkko Sakkinen
2017-01-02 16:36 ` [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley
2017-01-02 19:33 ` Jarkko Sakkinen
2017-01-02 21:40 ` James Bottomley
2017-01-03 5:26 ` James Bottomley
2017-01-03 13:41 ` Jarkko Sakkinen
2017-01-03 16:14 ` James Bottomley
2017-01-03 18:36 ` Jarkko Sakkinen
2017-01-03 19:14 ` Jarkko Sakkinen
2017-01-03 19:34 ` James Bottomley
2017-01-03 21:54 ` Jason Gunthorpe
2017-01-04 12:58 ` Jarkko Sakkinen
2017-01-04 16:55 ` Jason Gunthorpe
2017-01-04 5:47 ` Andy Lutomirski
2017-01-04 13:00 ` Jarkko Sakkinen
2017-01-03 13:51 ` Jarkko Sakkinen
2017-01-03 16:36 ` James Bottomley [this message]
2017-01-03 18:40 ` Jarkko Sakkinen
2017-01-03 21:47 ` Jason Gunthorpe
2017-01-03 22:21 ` Ken Goldman
2017-01-03 23:20 ` Jason Gunthorpe
2017-01-03 22:39 ` James Bottomley
2017-01-04 0:17 ` Jason Gunthorpe
2017-01-04 0:29 ` James Bottomley
2017-01-04 0:56 ` Jason Gunthorpe
2017-01-04 12:50 ` Jarkko Sakkinen
2017-01-04 14:53 ` James Bottomley
2017-01-04 18:31 ` Jason Gunthorpe
2017-01-04 18:57 ` James Bottomley
2017-01-04 19:24 ` Jason Gunthorpe
2017-01-04 12:48 ` Jarkko Sakkinen
2017-01-03 21:32 ` Jason Gunthorpe
2017-01-03 22:03 ` James Bottomley
2017-01-05 15:52 ` Fuchs, Andreas
2017-01-05 17:27 ` Jason Gunthorpe
2017-01-05 18:06 ` James Bottomley
2017-01-06 8:43 ` Andreas Fuchs
2017-01-05 18:33 ` James Bottomley
2017-01-05 19:20 ` Jason Gunthorpe
2017-01-05 19:55 ` James Bottomley
2017-01-05 22:21 ` Jason Gunthorpe
2017-01-05 22:58 ` James Bottomley
2017-01-05 23:50 ` Jason Gunthorpe
2017-01-06 0:36 ` James Bottomley
2017-01-06 8:59 ` Andreas Fuchs
2017-01-06 19:10 ` Jason Gunthorpe
2017-01-06 19:02 ` Jason Gunthorpe
2017-01-10 19:03 ` Ken Goldman
2017-01-09 22:39 ` [tpmdd-devel] " Jarkko Sakkinen
2017-01-11 10:03 ` Andreas Fuchs
2017-01-04 16:12 Dr. Greg Wettstein
2017-01-09 23:16 ` Jarkko Sakkinen
2017-01-10 19:29 ` Ken Goldman
2017-01-11 11:36 ` Jarkko Sakkinen
2017-01-10 20:05 ` Jason Gunthorpe
2017-01-11 10:00 ` Andreas Fuchs
2017-01-11 18:03 ` Jason Gunthorpe
2017-01-11 18:27 ` Stefan Berger
2017-01-11 19:18 ` Jason Gunthorpe
2017-01-11 11:34 ` Jarkko Sakkinen
2017-01-11 15:39 ` James Bottomley
2017-01-11 17:56 ` Jason Gunthorpe
2017-01-11 18:25 ` James Bottomley
2017-01-11 19:04 ` Jason Gunthorpe
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