Re: One question about trusted key of keyring in Linux kernel.

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: James Bottomley <jejb@linux.ibm.com>
Cc: "Zhao, Shirley" <shirley.zhao@intel.com>,
	Mimi Zohar <zohar@linux.ibm.com>,
	Jonathan Corbet <corbet@lwn.net>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	'Mauro Carvalho Chehab' <mchehab+samsung@kernel.org>,
	"Zhu, Bing" <bing.zhu@intel.com>,
	"Chen, Luhai" <luhai.chen@intel.com>
Subject: Re: One question about trusted key of keyring in Linux kernel.
Date: Wed, 11 Dec 2019 19:53:51 +0200	[thread overview]
Message-ID: <20191211175351.GJ4516@linux.intel.com> (raw)
In-Reply-To: <20191211173322.GD4516@linux.intel.com>

On Wed, Dec 11, 2019 at 07:33:22PM +0200, Jarkko Sakkinen wrote:
> On Wed, Dec 11, 2019 at 07:23:59PM +0200, Jarkko Sakkinen wrote:
> > On Mon, Dec 09, 2019 at 12:31:53PM -0800, James Bottomley wrote:
> > > On Mon, 2019-12-09 at 21:47 +0200, Jarkko Sakkinen wrote:
> > > > On Mon, Dec 02, 2019 at 10:55:32AM -0800, James Bottomley wrote:
> > > > > blob but it looks like we need to fix the API.  I suppose the good
> > > > > news is given this failure that we have the opportunity to rewrite
> > > > > the API since no-one else can have used it for anything because of
> > > > > this.  The
> > > > 
> > > > I did successfully run this test when I wrote it 5 years ago:
> > > > 
> > > > https://github.com/jsakkine-intel/tpm2-scripts/blob/master/keyctl-smo
> > > > ke.sh
> > > > 
> > > > Given that there is API a way must be found that backwards
> > > > compatibility
> > > > is not broken. New format is fine but it must co-exist.
> > > 
> > > The old API is unsupportable in the combination of policy + auth as I
> > > already explained.  The kernel doesn't have access to the nonces to
> > > generate the HMAC because the session was created by the user and the
> > > API has no way to pass them in (plus passing them in would be a huge
> > > security failure if we tried).  Given that Shirley appears to be the
> > > first person ever to try this, I don't think the old API has grown any
> > > policy users so its safe to remove it.  If we get a complaint, we can
> > > discuss adding it back.
> > 
> > It works within limits so it can be definitely be maintained for
> > backwards compatibility.
> > 
> > Also, you are making a claim of the users that we cannot verify.
> > 
> > Finally, the new feature neither handles sessions. You claim that
> > it could be added later. I have to deny that because until session
> > handling is there we have no ways to be sure about that.
> > 
> > I see your point but this needs more consideration. It does not
> > make sense to rush.
> 
> Also can test the current patch set as soon as I've done with
> release critical tpm_tis bug even if I don't agree on every
> point.

E.g. I cannot do any good judgement on the options before I get
the feel to the code so please hold for a while until I get to
the point that I can run it.

/Jarkko