From: Jarkko Sakkinen <jarkko@kernel.org>
To: linux-integrity@vger.kernel.org, tpm2@lists.linux.dev
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
Subject: Re: tpm2key.asn1 parent identification
Date: Sun, 14 Sep 2025 19:23:33 +0300 [thread overview]
Message-ID: <aMbsBX2uq6zOixSA@kernel.org> (raw)
In-Reply-To: <aMboFXNNX7WZaOaS@kernel.org>
On Sun, Sep 14, 2025 at 07:08:37PM +0300, Jarkko Sakkinen wrote:
> Hi,
>
> In practice, while implementing tpm2sh and its self-contained TPM emulator
> called "MockTPM", I've noticed that 'tpm2key.asn1.' has a major bottleneck,
> but luckily it is easy to squash.
>
> Parent handle should never be persisted, as it defies the existential
> reason of having a file format in the first place.
>
> To address this issue I just added couple of optional fields to TPMKey:
>
> parentName [6] EXPLICIT OCTET STRING OPTIONAL,
> parentPubkey [7] EXPLICIT OCTET STRING OPTIONAL
>
> By persisting this information TPM2_GetCapability + TPM2_ReadPublic can
> be used to acquire an appropriate handle.
>
> I'd highly recommend to add this quirk to anything that processes this
> ASN.1 format.
Here's a proof of concept:
https://github.com/puavo-org/tpm2sh/commit/18ec3c2169b23523d8866c58fa7b8a89a79bd3d4
BR, Jarkko
next prev parent reply other threads:[~2025-09-14 16:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-14 16:08 tpm2key.asn1 parent identification Jarkko Sakkinen
2025-09-14 16:23 ` Jarkko Sakkinen [this message]
2025-09-22 21:42 ` James Bottomley
2025-09-15 3:24 ` James Bottomley
2025-09-15 14:50 ` Jarkko Sakkinen
2025-09-15 18:08 ` Jarkko Sakkinen
2025-09-16 2:10 ` Jarkko Sakkinen
2025-09-16 2:19 ` Jarkko Sakkinen
2025-09-17 2:33 ` James Bottomley
2025-09-18 15:48 ` Jarkko Sakkinen
2025-09-18 17:35 ` Jarkko Sakkinen
2025-09-22 8:56 ` Jarkko Sakkinen
2025-09-22 21:31 ` James Bottomley
2025-09-23 14:25 ` Jarkko Sakkinen
2025-09-23 14:37 ` James Bottomley
2025-09-23 15:08 ` Jarkko Sakkinen
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