On 6/23/23 9:05 PM, Dan Williams wrote: > Kuppuswamy Sathyanarayanan wrote: >> Hi All, >> >> In TDX guest, the attestation process is used to verify the TDX guest >> trustworthiness to other entities before provisioning secrets to the >> guest. >> >> The TDX guest attestation process consists of two steps: >> >> 1. TDREPORT generation >> 2. Quote generation. >> >> The First step (TDREPORT generation) involves getting the TDX guest >> measurement data in the format of TDREPORT which is further used to >> validate the authenticity of the TDX guest. The second step involves >> sending the TDREPORT to a Quoting Enclave (QE) server to generate a >> remotely verifiable Quote. TDREPORT by design can only be verified on >> the local platform. To support remote verification of the TDREPORT, >> TDX leverages Intel SGX Quoting Enclave to verify the TDREPORT >> locally and convert it to a remotely verifiable Quote. Although >> attestation software can use communication methods like TCP/IP or >> vsock to send the TDREPORT to QE, not all platforms support these >> communication models. So TDX GHCI specification [1] defines a method >> for Quote generation via hypercalls. Please check the discussion from >> Google [2] and Alibaba [3] which clarifies the need for hypercall based >> Quote generation support. This patch set adds this support. >> >> Support for TDREPORT generation already exists in the TDX guest driver. >> This patchset extends the same driver to add the Quote generation >> support. > > I missed that the TDREPORT ioctl() and this character device are already > upstream. The TDREPORT ioctl() if it is only needed for quote generation > seems a waste because it just retrieves a blob that needs to be turned > around and injected back into the kernel to generate a quote. Although the end goal is to generate the quote, the method the user chooses to achieve it may differ for a variety of reasons. In this case, we're trying to support the use case where the user will use methods like TCP/IP or vsock to generate the Quote. They can use the GET_REPORT IOCTL to get the TDREPORT and send it to the quoting enclave via the above-mentioned methods. TDVMCALL-based quote generation is intended for users who, for a variety of security reasons, do not wish to use the methods described above. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer
