linux-kernel - Re: [PATCH v2] tpm: Opt-in in disable PCR integrity protection

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Message-Id: <D5G3K1QSPRNS.153H4EMMWEEBU@kernel.org>
Date: Thu, 07 Nov 2024 18:45:35 +0200
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Mimi Zohar" <zohar@...ux.ibm.com>, <linux-integrity@...r.kernel.org>,
 "Jonathan Corbet" <corbet@....net>, "Peter Huewe" <peterhuewe@....de>,
 "Jason Gunthorpe" <jgg@...pe.ca>, "James Bottomley"
 <James.Bottomley@...senPartnership.com>
Cc: "Roberto Sassu" <roberto.sassu@...wei.com>, <linux-doc@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] tpm: Opt-in in disable PCR integrity protection

On Thu Nov 7, 2024 at 4:00 PM EET, Mimi Zohar wrote:
> On Thu, 2024-11-07 at 15:47 +0200, Jarkko Sakkinen wrote:
> > On Thu Nov 7, 2024 at 3:44 PM EET, Mimi Zohar wrote:
> > > > 
> > > > @@ -232,18 +236,26 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
> > > >  	int rc;
> > > >  	int i;
> > > >  
> > > > -	rc = tpm2_start_auth_session(chip);
> > > > -	if (rc)
> > > > -		return rc;
> > > > +	if (!disable_pcr_integrity_protection) {
> > > > +		rc = tpm2_start_auth_session(chip);
> > > > +		if (rc)
> > > > +			return rc;
> > > > +	}
> > > >  
> > > >  	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
> > > >  	if (rc) {
> > > > -		tpm2_end_auth_session(chip);
> > > > +		if (!disable_pcr_integrity_protection)
> > > > +			tpm2_end_auth_session(chip);
> > > >  		return rc;
> > > >  	}
> > > >  
> > > > -	tpm_buf_append_name(chip, &buf, pcr_idx, NULL);
> > > > -	tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
> > > > +	if (!disable_pcr_integrity_protection) {
> > > > +		tpm_buf_append_name(chip, &buf, pcr_idx);
> > > 
> > > tpm_buf_append_name() parameters didn't change.  Don't remove the 'name' field
> > > here.
> > 
> > Hmm... weird I'll check this. Maybe I had something left to staging...

Yes! This was correct in my clone but not in the patch.

Clearly a sign that I wait until next week before sending a new version
:-)


> > 
> > > 
> > > 
> > > > +		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
> > > > +	} else {
> > > > +		tpm_buf_append_handle(chip, &buf, pcr_idx);
> > > 
> > 
> > > Or here.
> > 
> > Here I think it is appropriate
>
> Agreed

Great

BR, Jarkko