linux-kernel - Re: [PATCH 1/2 v2] tpm: cmd_ready command can be issued only after granting locality

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Message-ID: <20180208124431.26f43gj66c36gugz@linux.intel.com>
Date:   Thu, 8 Feb 2018 14:44:31 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        "Usyskin, Alexander" <alexander.usyskin@...el.com>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2 v2] tpm: cmd_ready command can be issued only after
 granting locality

On Tue, Feb 06, 2018 at 09:26:15PM +0000, Winkler, Tomas wrote:
> > 
> > On Sun, Jan 28, 2018 at 09:17:53PM +0000, Winkler, Tomas wrote:
> > >
> > > >
> > > > On Sun, Jan 28, 2018 at 09:51:00AM +0200, Tomas Winkler wrote:
> > > >
> > > > > diff --git a/include/linux/tpm.h b/include/linux/tpm.h index
> > > > > bcdd3790e94d..06639fb6ab85 100644
> > > > > +++ b/include/linux/tpm.h
> > > > > @@ -44,7 +44,7 @@ struct tpm_class_ops {
> > > > >  	bool (*update_timeouts)(struct tpm_chip *chip,
> > > > >  				unsigned long *timeout_cap);
> > > > >  	int (*request_locality)(struct tpm_chip *chip, int loc);
> > > > > -	void (*relinquish_locality)(struct tpm_chip *chip, int loc);
> > > > > +	int (*relinquish_locality)(struct tpm_chip *chip, int loc);
> > > >
> > > > This seems wrong.. What is the core code supposed to do if relinquish
> > fails?
> > >
> > > Not much just propage the error to the caller and leave the policy
> > > decision to it.
> > 
> > Your patch set must either cover this or keep it as void.
> 
> 
> How the code is covering other failures in the transmit functions,  
> how is this one different from for example request_locality failure?
> Why we should not propage this error up?
> 
> > 
> > A better idea is to print an error to klog.
> We can do that in addition.

I guess you are right. This can be propagated to the user space so that
it knows that there is problem. To make the root more visible the klog
message would make sense.

/Jarkko