From: Peter Gonda <pgonda@google.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-coco@lists.linux.dev,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Erdem Aktas <erdemaktas@google.com>,
peterz@infradead.org, dave.hansen@linux.intel.com, bp@alien8.de
Subject: Re: [PATCH v6 7/7] virt: tdx-guest: Add Quote generation support using TSM_REPORTS
Date: Thu, 19 Oct 2023 12:12:37 -0600 [thread overview]
Message-ID: <CAMkAt6obkMy0yL9B=RO8bYz+bpNsORJNQNbGuwhWBG2L=Y=xDg@mail.gmail.com> (raw)
In-Reply-To: <169716327547.984874.4293302721471522858.stgit@dwillia2-xfh.jf.intel.com>
On Thu, Oct 12, 2023 at 8:14 PM Dan Williams <dan.j.williams@intel.com> wrote:
>
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>
> In TDX guest, the attestation process is used to verify the TDX guest
> trustworthiness to other entities before provisioning secrets to the
> guest. The first step in the attestation process is TDREPORT
> generation, which involves getting the guest measurement data in the
> format of TDREPORT, which is further used to validate the authenticity
> of the TDX guest. TDREPORT by design is integrity-protected and can
> only be verified on the local machine.
>
> To support remote verification of the TDREPORT in a SGX-based
> attestation, the TDREPORT needs to be sent to the SGX Quoting Enclave
> (QE) to convert it to a remotely verifiable Quote. SGX QE by design can
> only run outside of the TDX guest (i.e. in a host process or in a
> normal VM) and guest can use communication channels like vsock or
> TCP/IP to send the TDREPORT to the QE. But for security concerns, the
> TDX guest may not support these communication channels. To handle such
> cases, TDX defines a GetQuote hypercall which can be used by the guest
> to request the host VMM to communicate with the SGX QE. More details
> about GetQuote hypercall can be found in TDX Guest-Host Communication
> Interface (GHCI) for Intel TDX 1.0, section titled
> "TDG.VP.VMCALL<GetQuote>".
>
> Trusted Security Module (TSM) [1] exposes a common ABI for Confidential
> Computing Guest platforms to get the measurement data via ConfigFS.
> Extend the TSM framework and add support to allow an attestation agent
> to get the TDX Quote data (included usage example below).
>
> report=/sys/kernel/config/tsm/report/report0
> mkdir $report
> dd if=/dev/urandom bs=64 count=1 > $report/inblob
> hexdump -C $report/outblob
> rmdir $report
>
> GetQuote TDVMCALL requires TD guest pass a 4K aligned shared buffer
> with TDREPORT data as input, which is further used by the VMM to copy
> the TD Quote result after successful Quote generation. To create the
> shared buffer, allocate a large enough memory and mark it shared using
> set_memory_decrypted() in tdx_guest_init(). This buffer will be re-used
> for GetQuote requests in the TDX TSM handler.
>
> Although this method reserves a fixed chunk of memory for GetQuote
> requests, such one time allocation can help avoid memory fragmentation
> related allocation failures later in the uptime of the guest.
>
> Since the Quote generation process is not time-critical or frequently
> used, the current version uses a polling model for Quote requests and
> it also does not support parallel GetQuote requests.
>
> Link: https://lore.kernel.org/lkml/169342399185.3934343.3035845348326944519.stgit@dwillia2-xfh.jf.intel.com/ [1]
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Reviewed-by: Erdem Aktas <erdemaktas@google.com>
> Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
I was able to test this on an SNP machine with VCEKs provisioned and
handed to KVM.
Tested-by: Peter Gonda <pgonda@google.com>
next prev parent reply other threads:[~2023-10-19 18:12 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-13 2:13 [PATCH v6 0/7] configfs-tsm: Attestation Report ABI Dan Williams
2023-10-13 2:14 ` [PATCH v6 1/7] virt: sevguest: Fix passing a stack buffer as a scatterlist target Dan Williams
2023-10-13 2:14 ` [PATCH v6 2/7] virt: coco: Add a coco/Makefile and coco/Kconfig Dan Williams
2023-10-13 2:14 ` [PATCH v6 3/7] configfs-tsm: Introduce a shared ABI for attestation reports Dan Williams
2023-10-13 4:43 ` Dionna Amalie Glaze
2023-10-13 5:15 ` Dan Williams
2023-10-16 6:36 ` Alexey Kardashevskiy
2023-10-17 2:19 ` Dan Williams
2023-10-17 6:20 ` Alexey Kardashevskiy
2023-10-19 1:29 ` Dan Williams
2023-10-19 20:24 ` Dan Williams
2023-10-13 2:14 ` [PATCH v6 4/7] virt: sevguest: Prep for kernel internal get_ext_report() Dan Williams
2023-10-13 2:14 ` [PATCH v6 5/7] mm/slab: Add __free() support for kvfree Dan Williams
2023-10-13 2:14 ` [PATCH v6 6/7] virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT Dan Williams
2023-10-13 15:38 ` Tom Lendacky
2023-10-14 4:46 ` Dan Williams
2023-10-16 11:36 ` Alexey Kardashevskiy
2023-10-16 15:39 ` Dionna Amalie Glaze
2023-10-16 15:42 ` Peter Gonda
2023-10-17 0:42 ` Alexey Kardashevskiy
2023-10-19 4:30 ` Dan Williams
2023-10-17 4:07 ` Dan Williams
2023-10-17 5:35 ` Alexey Kardashevskiy
2023-10-17 6:28 ` Alexey Kardashevskiy
2023-10-19 4:43 ` Dan Williams
2023-10-19 5:12 ` Alexey Kardashevskiy
2023-10-19 3:34 ` Dan Williams
2023-10-13 2:14 ` [PATCH v6 7/7] virt: tdx-guest: Add Quote generation support using TSM_REPORTS Dan Williams
2023-10-19 18:12 ` Peter Gonda [this message]
2023-10-13 15:39 ` [PATCH v6 0/7] configfs-tsm: Attestation Report ABI Tom Lendacky
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