linux-kernel - Re: [PATCH v6] tpm: add support for partial reads

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Message-ID: <20181127233617.GA1304@linux.intel.com>
Date:   Tue, 27 Nov 2018 15:36:17 -0800
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Tadeusz Struk <tadeusz.struk@...el.com>
Cc:     jgg@...pe.ca, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] tpm: add support for partial reads

On Wed, Nov 21, 2018 at 05:18:38PM +0200, Jarkko Sakkinen wrote:
> On Wed, Nov 21, 2018 at 06:50:37AM -0800, Tadeusz Struk wrote:
> > Currently to read a response from the TPM device an application needs
> > provide big enough buffer for the whole response and read it in one go.
> > The application doesn't know how big the response it beforehand so it
> > always needs to maintain a 4K buffer and read the max (4K).
> > In case if the user of the TSS library doesn't provide big enough
> > buffer the TCTI spec says that the library should set the required
> > size and return TSS2_TCTI_RC_INSUFFICIENT_BUFFER error code so that the
> > application could allocate a bigger buffer and call receive again.
> > To make it possible in the TSS library, this requires being able to do
> > partial reads from the driver.
> > The library would read the 10 bytes header first to get the actual size
> > of the response from the header, and then read the rest of the response.
> > 
> > This patch adds support for partial reads, i.e. the user can read the
> > response in one or multiple reads, until the whole response is consumed.
> > The user can also read only part of the response and ignore
> > the rest by issuing a new write to send a new command.
> > 
> > Signed-off-by: Tadeusz Struk <tadeusz.struk@...el.com>
> 
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

Pushed.

/Jarkko