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Date:   Thu, 5 Oct 2023 15:09:17 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Lukas Wunner <lukas@wunner.de>
Cc:     Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        David Howells <dhowells@redhat.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Alex Williamson <alex.williamson@redhat.com>,
        linux-pci@vger.kernel.org, linux-cxl@vger.kernel.org,
        linux-coco@lists.linux.dev, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, kvm@vger.kernel.org,
        linuxarm@huawei.com, David Box <david.e.box@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        "Li, Ming" <ming4.li@intel.com>, Zhi Wang <zhi.a.wang@intel.com>,
        Alistair Francis <alistair.francis@wdc.com>,
        Wilfred Mallawa <wilfred.mallawa@wdc.com>,
        Alexey Kardashevskiy <aik@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Alexander Graf <graf@amazon.com>
Subject: Re: [PATCH 09/12] PCI/CMA: Validate Subject Alternative Name in
 certificates
Message-ID: <20231005200917.GA789502@bhelgaas>
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On Thu, Oct 05, 2023 at 04:04:47PM +0200, Lukas Wunner wrote:
> On Tue, Oct 03, 2023 at 04:04:55PM +0100, Jonathan Cameron wrote:
> > On Thu, 28 Sep 2023 19:32:39 +0200 Lukas Wunner <lukas@wunner.de> wrote:
> > > PCIe r6.1 sec 6.31.3 stipulates requirements for X.509 Leaf Certificates

The PCIe spec does not contain "X.509", so I assume this is sort of a
transitive requirement from SPDM.

> > > presented by devices, in particular the presence of a Subject Alternative
> > > Name extension with a name that encodes the Vendor ID, Device ID, Device
> > > Serial Number, etc.
> > 
> > Lets you do any of
> > * What you have here
> > * Reference Integrity Manifest, e.g. see Trusted Computing Group
> > * A pointer to a location where such a Reference Integrity Manifest can be
> >   obtained.
> > 
> > So this text feels a little strong though I'm fine with only support the
> > Subject Alternative Name bit for now. Whoever has one of the other options
> > can add that support :)
> 
> I intend to amend the commit message as follows.  If anyone believes
> this is inaccurate, please let me know:
> 
>     Side note:  Instead of a Subject Alternative Name, Leaf Certificates may
>     include "a Reference Integrity Manifest, e.g., see Trusted Computing
>     Group" or "a pointer to a location where such a Reference Integrity
>     Manifest can be obtained" (PCIe r6.1 sec 6.31.3).
> 
>     A Reference Integrity Manifest contains "golden" measurements which can
>     be compared to actual measurements retrieved from a device.  It serves a
>     different purpose than the Subject Alternative Name, hence it is unclear
>     why the spec says only either of them is necessary.  It is also unclear
>     how a Reference Integrity Manifest shall be encoded into a certificate.
> 
>     Ignore the Reference Integrity Manifest requirement until this confusion
>     is resolved by a spec update.

Thanks for this; I was about to comment the same.

Bjorn