linux-kernel - Re: [tpmdd-devel] [PATCH v2 1/2] tpm2: add session handle context saving and restoring to the space code

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Message-ID: <20170131131517.ewudypkagux2bg6e@intel.com>
Date:   Tue, 31 Jan 2017 15:15:17 +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 v2 1/2] tpm2: add session handle context
 saving and restoring to the space code

On Mon, Jan 30, 2017 at 02:14:37PM -0800, James Bottomley wrote:
> On Mon, 2017-01-30 at 23:45 +0200, Jarkko Sakkinen wrote:
> > On Sun, Jan 29, 2017 at 02:36:58PM -0800, James Bottomley wrote:
> [...]
> > > > 2. Can it really return both TPM_RC_HANDLE and
> > > > TPM_RC_REFERENCE_H0? 
> > > 
> > > Yes, it seems that a session that doesn't exist (because it's been
> > > flushed) then it returns TPM_RC_REFERNCE_H0, but if the context has 
> > > a sequence mismatch (because it's been flushed and reloaded) then 
> > > we get TPM_RC_HANDLE.
> > > 
> > > James
> > 
> > If it is flushed, wouldn't you just get TPM_RC_REFERENCE_H0 when you 
> > try to TPM2_ContextLoad? The "and reloaded" does not make sense to 
> > me. Once a session is flushed it cannot be reloaded.
> > 
> > Maybe you meant to say "beause it's been saved and reloaded"? That 
> > would make more sense and fits better what I see in the Commands 
> > specification.
> 
> I mean if you load a prior context instead of the current one for an
> existing handle, effectively a replay, you get TPM_RC_HANDLE.
> 
> James

Thanks for clarifying this.

/Jarkko