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Intel platforms are transitioning from traditional SGX-based attestation toward DICE-based attestation as part of a broader move toward open and standardized attestation models. DICE enables layered and extensible attestation, where evidence is accumulated across multiple boot stages. With SGX-based attestation, Quote sizes are typically under 8KB, as the payload consists primarily of Quote data and a small certificate bundle. Existing TDX guest code sizes the Quote buffer accordingly. DICE-based attestation produces significantly larger Quotes due to the inclusion of evidence (certificate chains) from multiple boot layers. The cumulative Quote size can reach approximately 100KB. Increase GET_QUOTE_BUF_SIZE to 128KB to ensure sufficient buffer capacity for DICE-based Quote payloads. Reviewed-by: Fang Peter <peter.fang@intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Link: https://patch.msgid.link/20260211001712.1531955-4-sathyanarayanan.kuppuswamy@linux.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
162 lines
6.2 KiB
Plaintext
162 lines
6.2 KiB
Plaintext
What: /sys/kernel/config/tsm/report/$name/inblob
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Date: September, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(WO) Up to 64 bytes of user specified binary data. For replay
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protection this should include a nonce, but the kernel does not
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place any restrictions on the content.
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What: /sys/kernel/config/tsm/report/$name/outblob
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Date: September, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(RO) Binary attestation report generated from @inblob and other
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options The format of the report is implementation specific
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where the implementation is conveyed via the @provider
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attribute.
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This interface fails reads and sets errno to EFBIG when the
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report generated by @provider exceeds the configfs-tsm-report
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internal maximums. Contact the platform provider for the
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compatible security module, driver, and attestation library
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combination.
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What: /sys/kernel/config/tsm/report/$name/auxblob
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Date: October, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(RO) Optional supplemental data that a TSM may emit, visibility
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of this attribute depends on TSM, and may be empty if no
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auxiliary data is available.
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When @provider is "sev_guest" this file contains the
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"cert_table" from SEV-ES Guest-Hypervisor Communication Block
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Standardization v2.03 Section 4.1.8.1 MSG_REPORT_REQ.
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https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/56421.pdf
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See "EFBIG" comment in the @outblob description for potential
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error conditions.
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What: /sys/kernel/config/tsm/report/$name/manifestblob
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Date: January, 2024
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KernelVersion: v6.10
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Contact: linux-coco@lists.linux.dev
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Description:
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(RO) Optional supplemental data that a TSM may emit, visibility
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of this attribute depends on TSM, and may be empty if no
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manifest data is available.
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See 'service_provider' for information on the format of the
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manifest blob.
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See "EFBIG" comment in the @outblob description for potential
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error conditions.
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What: /sys/kernel/config/tsm/report/$name/provider
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Date: September, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(RO) A name for the format-specification of @outblob like
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"sev_guest" [1] or "tdx_guest" [2] in the near term, or a
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common standard format in the future.
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[1]: SEV Secure Nested Paging Firmware ABI Specification
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Revision 1.55 Table 22
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https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/56860.pdf
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[2]: Intel® Trust Domain Extensions Data Center Attestation
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Primitives : Quote Generation Library and Quote Verification
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Library Revision 0.8 Appendix 4,5
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https://download.01.org/intel-sgx/latest/dcap-latest/linux/docs/Intel_TDX_DCAP_Quoting_Library_API.pdf
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Intel TDX platforms with DICE-based attestation use CBOR Web Token
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(CWT) format for the Quote payload. This is indicated by the Quote
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size exceeding 8KB.
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What: /sys/kernel/config/tsm/report/$name/generation
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Date: September, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(RO) The value in this attribute increments each time @inblob or
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any option is written. Userspace can detect conflicts by
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checking generation before writing to any attribute and making
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sure the number of writes matches expectations after reading
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@outblob, or it can prevent conflicts by creating a report
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instance per requesting context.
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What: /sys/kernel/config/tsm/report/$name/privlevel
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Date: September, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(WO) Attribute is visible if a TSM implementation provider
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supports the concept of attestation reports for TVMs running at
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different privilege levels, like SEV-SNP "VMPL", specify the
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privilege level via this attribute. The minimum acceptable
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value is conveyed via @privlevel_floor and the maximum
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acceptable value is TSM_PRIVLEVEL_MAX (3).
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What: /sys/kernel/config/tsm/report/$name/privlevel_floor
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Date: September, 2023
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KernelVersion: v6.7
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Contact: linux-coco@lists.linux.dev
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Description:
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(RO) Indicates the minimum permissible value that can be written
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to @privlevel.
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What: /sys/kernel/config/tsm/report/$name/service_provider
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Date: January, 2024
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KernelVersion: v6.10
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Contact: linux-coco@lists.linux.dev
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Description:
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(WO) Attribute is visible if a TSM implementation provider
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supports the concept of attestation reports from a service
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provider for TVMs, like SEV-SNP running under an SVSM.
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Specifying the service provider via this attribute will create
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an attestation report as specified by the service provider.
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The only currently supported service provider is "svsm".
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For the "svsm" service provider, see the Secure VM Service Module
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for SEV-SNP Guests v1.00 Section 7. For the doc, search for
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"site:amd.com "Secure VM Service Module for SEV-SNP
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Guests", docID: 58019"
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What: /sys/kernel/config/tsm/report/$name/service_guid
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Date: January, 2024
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KernelVersion: v6.10
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Contact: linux-coco@lists.linux.dev
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Description:
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(WO) Attribute is visible if a TSM implementation provider
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supports the concept of attestation reports from a service
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provider for TVMs, like SEV-SNP running under an SVSM.
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Specifying an empty/null GUID (00000000-0000-0000-0000-000000)
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requests all active services within the service provider be
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part of the attestation report. Specifying a GUID request
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an attestation report of just the specified service using the
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manifest form specified by the service_manifest_version
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attribute.
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See 'service_provider' for information on the format of the
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service guid.
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What: /sys/kernel/config/tsm/report/$name/service_manifest_version
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Date: January, 2024
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KernelVersion: v6.10
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Contact: linux-coco@lists.linux.dev
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Description:
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(WO) Attribute is visible if a TSM implementation provider
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supports the concept of attestation reports from a service
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provider for TVMs, like SEV-SNP running under an SVSM.
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Indicates the service manifest version requested for the
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attestation report (default 0). If this field is not set by
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the user, the default manifest version of the service (the
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service's initial/first manifest version) is returned.
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See 'service_provider' for information on the format of the
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service manifest version.
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