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Date: Fri, 27 Jan 2017 08:45:05 +0200
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: James Bottomley <James.Bottomley@...senPartnership.com>
Cc: linux-security-module@...r.kernel.org,
tpmdd-devel@...ts.sourceforge.net,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [tpmdd-devel] [PATCH RFC v3 5/5] tpm2: expose resource manager
via a device link /dev/tpms<n>
On Thu, Jan 26, 2017 at 04:29:02PM -0800, James Bottomley wrote:
> On Wed, 2017-01-25 at 15:40 +0200, Jarkko Sakkinen wrote:
> > On Mon, Jan 23, 2017 at 02:16:37PM -0800, James Bottomley wrote:
> > > On Mon, 2017-01-23 at 23:42 +0200, Jarkko Sakkinen wrote:
> > > > On Mon, Jan 23, 2017 at 06:58:23PM +0200, Jarkko Sakkinen wrote:
> > > > > On Mon, Jan 23, 2017 at 04:09:42PM +0200, Jarkko Sakkinen
> > > > > wrote:
> > > > > > On Sun, Jan 22, 2017 at 01:36:28PM -0800, James Bottomley
> > > > > > wrote:
> > > > > > > On Sun, 2017-01-22 at 23:04 +0200, Jarkko Sakkinen wrote:
> > > > > > > > On Sun, Jan 22, 2017 at 11:01:07PM +0200, Jarkko Sakkinen
> > > > > > > > wrote:
> > > > > > > > > On Sun, Jan 22, 2017 at 10:30:55PM +0200, Jarkko
> > > > > > > > > Sakkinen
> > > > > > > > > wrote:
> > > > > > > > > > On Sun, Jan 22, 2017 at 10:48:12AM -0800, James
> > > > > > > > > > Bottomley
> > > > > > > > > > wrote:
> > > > > > > > > > > On Sun, 2017-01-22 at 09:49 -0800, James Bottomley
> > > > > > > > > > > wrote:
> > > > > > > > > > > > On Fri, 2017-01-20 at 23:05 +0200, Jarkko
> > > > > > > > > > > > Sakkinen
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > 'tabrm4' branch has been now rebased. It's now
> > > > > > > > > > > > > on
> > > > > > > > > > > > > top of
> > > > > > > > > > > > > master
> > > > > > > > > > > > > branch that contains Stefan's latest patch (min
> > > > > > > > > > > > > body length
> > > > > > > > > > > > > check)
> > > > > > > > > > > > > that I've reviewed and tested. It also contains
> > > > > > > > > > > > > your
> > > > > > > > > > > > > updated
> > > > > > > > > > > > > /dev/tpms patch.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I guess the 5 commits that are there now are
> > > > > > > > > > > > > such
> > > > > > > > > > > > > that we
> > > > > > > > > > > > > have
> > > > > > > > > > > > > fairly good consensus, don't we? If so, can I
> > > > > > > > > > > > > add
> > > > > > > > > > > > > your
> > > > > > > > > > > > > reviewed-by
> > > > > > > > > > > > > and tested-by to my commits and vice versa?
> > > > > > > > > > > >
> > > > > > > > > > > > We're still failing my test_transients. This is
> > > > > > > > > > > > the
> > > > > > > > > > > > full
> > > > > > > > > > > > python of
> > > > > > > > > > > > the test case:
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > def test_transients(self):
> > > > > > > > > > > > k = self.open_transients()
> > > > > > > > > > > > self.c.flush_context(k[0])
> > > > > > > > > > > > self.c.change_auth(self.c.SRK, k[1],
> > > > > > > > > > > > None,
> > > > > > > > > > > > pwd1)
> > > > > > > > > > > > ...
> > > > > > > > > > > >
> > > > > > > > > > > > It's failing at self.c.flush_context(k[0]) with
> > > > > > > > > > > > TPM_RC_VALUE.
> > > > > > > > > > > > It's
> > > > > > > > > > > > the same problem Ken complained about:
> > > > > > > > > > > > TPM2_FlushContext
> > > > > > > > > > > > doesn't have
> > > > > > > > > > > > a declared handle area so we don't translate the
> > > > > > > > > > > > handle being
> > > > > > > > > > > > sent
> > > > > > > > > > > > down. We have to fix this either by intercepting
> > > > > > > > > > > > the
> > > > > > > > > > > > flush
> > > > > > > > > > > > and
> > > > > > > > > > > > manually translating the context, or by being
> > > > > > > > > > > > dangerously
> > > > > > > > > > > > clever and
> > > > > > > > > > > > marking flush as a command which takes one
> > > > > > > > > > > > handle.
> > > > > > > > > > >
> > > > > > > > > > > This is what the dangerously clever fix looks like.
> > > > > > > > > > > With this
> > > > > > > > > > > and a
> > > > > > > > > > > few other changes, my smoke tests now pass.
> > > > > > > > > > >
> > > > > > > > > > > James
> > > > > > > > > >
> > > > > > > > > > I don't want to be clever here. I will rather
> > > > > > > > > > intercept
> > > > > > > > > > the body
> > > > > > > > > > and
> > > > > > > > > > try to keep the core code simple and easy to
> > > > > > > > > > understand.
> > > > > > > > >
> > > > > > > > > It came out quite clean actually.
> > > > > > > > >
> > > > > > > > > I just encapsulated handle mapping and have this in the
> > > > > > > > > beginning
> > > > > > > > > of
> > > > > > > > > tpm2_map_command:
> > > > > > > > >
> > > > > > > > > if (cc == TPM2_CC_FLUSH_CONTEXT)
> > > > > > > > > return tpm2_map_to_phandle(space,
> > > > > > > > > &cmd[TPM_HEADER_SIZE]);
> > > > > > > > >
> > > > > > > > > I think this documents better what is actually going on
> > > > > > > > > than
> > > > > > > > > tinkering
> > > > > > > > > cc_attr_tbl.
> > > > > > > > >
> > > > > > > > > /Jarkko
> > > > > > > >
> > > > > > > > Actually what you suggested is much better idea because
> > > > > > > > it
> > > > > > > > will also
> > > > > > > > take care of validation.
> > > > > > >
> > > > > > > Yes, that's why it's clever ... I'm just always wary of
> > > > > > > clever
> > > > > > > code
> > > > > > > because of the Kernighan principle.
> > > > > > >
> > > > > > > > I'm still going to keep tpm2_map_to_phandle because it
> > > > > > > > makes
> > > > > > > > the
> > > > > > > > code flow a lot cleaner and probably sessions have to
> > > > > > > > anyway
> > > > > > > > make it
> > > > > > > > even more complicated.
> > > > > > >
> > > > > > > OK, there's one more thing that seems to be causing
> > > > > > > problems:
> > > > > > > when
> > > > > > > tpm2_save_context fails because the handle no longer exists
> > > > > > > (like it's
> > > > > > > been flushed) it returns TPM_RC_REFERENCE_H0 not
> > > > > > > TPM_RC_HANDLE
> > > > > > > (the
> > > > > > > session code does seem to return TPM_RC_HANDLE under some
> > > > > > > circumstances).
> > > > > > >
> > > > > > > James
> > > > > >
> > > > > > What is your way for reproducing this issue? Just want to add
> > > > > > a test case for my smoke test suite so that I can verify that
> > > > > > the issue is fixed once I've fixed it.
> > > > >
> > > > > Right. Too easy. Sorry about this. I'll push a fix for this to
> > > > > tabrm4 branch.
> > > >
> > > > 1. I pushed a fix to the repository.
> > >
> > > I don't think the fix is right; this is what you now have
> > >
> > > } else if ((rc & TPM2_RC_REFERENCE_H0) == TPM2_RC_REFERENCE_H0)
> > > {
> > >
> > > That should be
> > >
> > > } else if (rc == TPM2_RC_REFERENCE_H0)
> >
> > Right I see your point.
> >
> > And yes, also for RC_HANDLE the error handling was done incorrectly.
> > It should be masked like you said with 0xff to catch error number
> > and the F flag (bit 7).
> >
> > As it is format zero error code it should be fine to check without
> > any mask.
> >
> > Thanks for noting this. It is easy to shoot yourself into foot when
> > there's lot of stuff packed :-)
>
> OK, I've rebased and retested to tabrm5. Apart from the obvious
> introduced bug into the last patch (fix below if you need it)
> everything works, so you can add my tested and reviewed bys.
>
> James
>
> ---
>
> commit b63aa4b3a5dce31cbc874fa32bd7252b62f55813
> Author: James Bottomley <James.Bottomley@...senPartnership.com>
> Date: Thu Jan 26 08:43:55 2017 -0800
>
> fix compile failure
>
> diff --git a/drivers/char/tpm/tpms-dev.c b/drivers/char/tpm/tpms-dev.c
> index 5030f8c..5720885 100644
> --- a/drivers/char/tpm/tpms-dev.c
> +++ b/drivers/char/tpm/tpms-dev.c
> @@ -39,7 +39,7 @@ static int tpms_release(struct inode *inode, struct file *file)
> struct tpms_priv *priv = container_of(fpriv, struct tpms_priv, priv);
>
> tpm_common_release(file, fpriv);
> - tpm2_del_space(&priv->space):
> + tpm2_del_space(&priv->space);
> kfree(priv);
>
> return 0;
>
Thanks. It should be now OK.
/Jarkko
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