linux-kernel - RE: [tpmdd-devel] [PATCH 4/4] keys, trusted: seal/unseal with TPM 2.0 chips

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Message-ID: <9F48E1A823B03B4790B7E6E69430724D9D7B1E84@EXCH2010A.sit.fraunhofer.de>
Date:	Wed, 7 Oct 2015 10:04:40 +0000
From:	"Fuchs, Andreas" <andreas.fuchs@....fraunhofer.de>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
CC:	"tpmdd-devel@...ts.sourceforge.net" 
	<tpmdd-devel@...ts.sourceforge.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	David Howells <dhowells@...hat.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"open list:KEYS-TRUSTED" <linux-security-module@...r.kernel.org>,
	"open list:KEYS-TRUSTED" <keyrings@...r.kernel.org>,
	James Morris <james.l.morris@...cle.com>,
	"David Safford" <safford@...ibm.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	"josh@...htripplet.org" <josh@...htripplet.org>,
	"richard.l.maliszewski@...el.com" <richard.l.maliszewski@...el.com>,
	"monty.wiseman@...el.com" <monty.wiseman@...el.com>,
	"will.c.arthur@...el.com" <will.c.arthur@...el.com>
Subject: RE: [tpmdd-devel] [PATCH 4/4] keys,	trusted: seal/unseal with TPM
 2.0 chips

> > > > I looked at Patch 3/4 and it seems you default to -EPERM on TPM2_Create()-
> > > > and TPM2_Load()-failures ?
> > > > You might want to test against rc == TPM_RC_OBJECT_MEMORY and return -EBUSY
> > > > in those cases. Would you agree ?
> > > > (P.S. I can cross-post there if that's prefered ?)
> > >
> > > Have to check the return values. I posted this patch set already in
> > > early July. You are the first reviewer in three months for this patch
> > > set.
> > >
> > > I think the reason was that for TPM 1.x returned -EPERM in all error
> > > scenarios and I didn't want to endanger behaviour of command-line tools
> > > such as 'keyctl'. I would keep it that way unless you can guarantee that
> > > command-line tools will continue work correctly if I change it to
> > > -EBUSY.
> > >
> > > Anyway, I will recheck this part of the patch set but likely are not
> > > going to do any changes because I don't want to break the user space.
> > >
> > > I will consider revising the patch set with keyhandle required as an
> > > explicit option.
> >
> > Hmm... Will the old keyctl work without modification with the 2.0 patches
> > anyways ?
> 
> Yes it does and it should. I've been using keyctl utility to test my
> patch set.
> 
> > The different keyHandle values and missing default keyHandle will yield
> > "differences" anyways, I'd say.
> > IMHO, we should get it as correct as possible given that TPM 2.0 is still
> > very young.
> >
> > Is adding "additional" ReturnCodes considered ABI-incompatible breaking
> > anyways ?
> 
> Yes they are if they make the user space utiltiy malfunction.

AFAICT, keyctl just perror()s. Which is what I would have hoped.
So it guess it should work with -EBUSY.
Example-Trace of calls for key_adding:
http://anonscm.debian.org/cgit/collab-maint/keyutils.git/tree/keyutils.c#n43
http://anonscm.debian.org/cgit/collab-maint/keyutils.git/tree/keyctl.c#n379
http://anonscm.debian.org/cgit/collab-maint/keyutils.git/tree/keyctl.c#n131

Wish I could test it myself.
I understand, if you don't want to test my thoughts on this.
I just cannot perform the tests myself right now... :-(

Cheers,
Andreas--
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