From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: James Bottomley <jejb@linux.vnet.ibm.com>,
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: Wed, 4 Jan 2017 15:00:46 +0200 [thread overview]
Message-ID: <20170104130046.u5isqy3z2nptdpgk@intel.com> (raw)
In-Reply-To: <649a9342-f1a5-ca63-90e3-efec1e537908@kernel.org>
On Tue, Jan 03, 2017 at 09:47:21PM -0800, Andy Lutomirski wrote:
> On 01/02/2017 09:26 PM, James Bottomley wrote:
> > On Mon, 2017-01-02 at 13:40 -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.
> > >
> > > 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.
> >
> > OK, so I put a patch together that does this (see below). It all works
> > nicely (with a udev script that sets the resource manager device to
> > 0666):
> >
> > jejb@jarvis:~> ls -l /dev/tpm*
> > crw------- 1 root root 10, 224 Jan 2 20:54 /dev/tpm0
> > crw-rw-rw- 1 root root 246, 65536 Jan 2 20:54 /dev/tpm0rm
> >
> > I've modified the tss to connect to /dev/tpm0rm by default and it all
> > seems to work.
> >
> > The patch applies on top of your tabrm branch, by the way.
>
> Conceptually I like this a *lot* better. I believe that this effectively
> solves my major gripe with the TPM 1.2 ecosystem.
>
> However, can this be taken just a little farther? IMO the tpm0rm (or tpms0
> or whatever) node should also restrict commands that can be sent (perhaps by
> in-kernel whitelist?) to those that shouldn't be restricted to the owner (by
> which I probably mean the Owner, the Platform, etc)? For example, someone
> with tpm0rm open should not be able to change key hierarchy passwords, write
> to NV memory, clear hierarchies, etc.
Yes. This was already discussed in Linux Plumbers. It is trivial to have
that. I just left it out from this RFC patch set to get something not
too complicated out quickly. Whitelist is coming to the non-RFC version.
> Hmm. Maybe there should be a way to allocate NV slots to users.
> /dev/tpm/nv0? I don't really like that idea, though.
/Jarkko
next prev parent reply other threads:[~2017-01-04 13:00 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 [this message]
2017-01-03 13:51 ` Jarkko Sakkinen
2017-01-03 16:36 ` James Bottomley
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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