linux-kernel - Re: [PATCH] KEYS: trusted: Re-orchestrate tpm2_read

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Message-ID: <aTIXOr3rpI9xufTl@kernel.org>
Date: Fri, 5 Dec 2025 01:20:26 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Mimi Zohar <zohar@...ux.ibm.com>,
	David Howells <dhowells@...hat.com>,
	Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	open list <linux-kernel@...r.kernel.org>,
	"open list:KEYS-TRUSTED" <keyrings@...r.kernel.org>,
	"open list:SECURITY SUBSYSTEM" <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH] KEYS: trusted: Re-orchestrate tpm2_read_public() calls

On Fri, Dec 05, 2025 at 12:31:27AM +0200, Jarkko Sakkinen wrote:
> tpm2_load_cmd() and tpm2_unseal_cmd() use the same parent, and calls to
> tpm_buf_append_name() cause the exact same TPM2_ReadPublic command to be
> sent to the chip, causing unnecessary traffic.
> 
> 1. Export tpm2_read_public in order to make it callable from 'trusted_tpm2'.
> 2. Re-orchestrate tpm2_seal_trusted() and tpm2_unseal_trusted() in order to
>    halve the name resolutions required:
> 2a. Move tpm2_read_public() calls into trusted_tpm2.
> 2b. Pass TPM name to tpm_buf_append_name().
> 2c. Rework tpm_buf_append_name() to use the pre-resolved name.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>

If ASN.1 blob would contain also name of the parent then zero
tpm2_read_public() calls would be required i.e., the main bottleneck
here inherits from the limitations of the file format itself.

BR, Jarkko