linux-kernel - Re: [PATCH 00/22] KEYS: Support TPM-wrapped key and crypto ops

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Date:   Fri, 28 Sep 2018 19:20:54 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     David Woodhouse <dwmw2@...radead.org>,
        James Bottemley <James.Bottomley@...senPartnership.com>,
        James Morris <jmorris@...ei.org>
Cc:     David Howells <dhowells@...hat.com>,
        Denis Kenzior <denkenz@...il.com>, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/22] KEYS: Support TPM-wrapped key and crypto ops

Hi David,

>>>>> Yes.  It shouldn't be much code, either.  You still have to check for X.509
>>>>> DER since the kernel currently supports that.
>>>> 
>>>> For reasons of backward compatibility, correct?  The kernel also has
>>>> mscode.asn1 which we would need to support as well.  Since we can't break
>>>> compatibility then perhaps this doesn't buy us a whole lot in the end.
>>> 
>>> Don't worry about mscode - that's not an asymmetric key parser.  That's only
>>> ever used directly from verify_pefile_signature().
>>> 
>>> Currently, we have to retain support for DER-encoded X.509.
>>> 
>>> But there's no reason we can't have a PEM parser that decodes the PEM and
>>> selects X.509, PKCS#8 or TPM based on the ascii header in that.  PKCS#8 and
>>> TPM don't need to take DER directly.
>> 
>> since we have to support DER-encoded anyway, can we get the current
>> patches merged (with fixes to the commit messages for the openssl
>> examples if needed) and then work on PEM support inside the kernel.
>> For me these seems to be two independent features. And in the current
>> form the patches have been tested and used.
>> 
>> Or let me ask this differently, are there any objections to merging
>> these patches with just DER support?
> 
> Let me rephrase that question slightly: Are we happy to have to make
> inferences from the ASN.1 structure, and in particular that a bare
> OCTET-STRING is a TPMv1 blob? I believe James ended up doing something
> somewhat more sensible for the TPMv2 blob so that might end up being
> OK...?

similar to Denis’ comment, I don’t see an issue here with using DER encoding.

James, can you take this series into your -next tree?

Regards

Marcel