From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: jgg@ziepe.ca, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] tpm: add support for partial reads
Date: Mon, 5 Nov 2018 15:39:47 +0200 [thread overview]
Message-ID: <20181105133947.GA21757@linux.intel.com> (raw)
In-Reply-To: <154084273717.29396.1021945733871865594.stgit@tstruk-mobl1.jf.intel.com>
On Mon, Oct 29, 2018 at 12:52:17PM -0700, 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.
>
> The usecase is implemented in this TSS commit:
> https://github.com/tpm2-software/tpm2-tss/commit/ce982f67a67dc08e24683d30b05800648d8a264c
>
> Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
> ---
> Changes in v2:
> - Allow writes after only partial response is consumed to maintain
> backwords compatibility.
I do not understand what this bullet means. Do you deny writes somehow?
/Jarkko
next prev parent reply other threads:[~2018-11-05 13:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-29 19:52 [PATCH v2] tpm: add support for partial reads Tadeusz Struk
2018-11-05 13:39 ` Jarkko Sakkinen [this message]
2018-11-15 18:49 ` Tadeusz Struk
2018-11-05 13:44 ` Jarkko Sakkinen
2018-11-15 18:50 ` Tadeusz Struk
2018-11-15 20:40 ` Jarkko Sakkinen
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