AMD SEV-SNP#

How to use the AMD SEV-SNP platform#

CCF must run on an AMD CPU which supports SEV-SNP (typically Azure confidential containers).

To use SNP, in the enclave configuration section, the enclave platform should be set to SNP.

Attestation#

SNP attestation provide several fields needed to establish trust. Several deployment scenarios are possible.

Confidential Azure Container Instance (ACI)#

Note

See here for more information on the deployment of confidential containers in Azure.

Azure Confidential ACI provides a security context directory containing the following files. The content of these files are checked against the attestation report on node startup and join, and stored in the ledger for audit and improved serviceability.

  • host-amd-cert-base64: The certificate chain corresponding to the key (VCEK) used to sign the attestation report, up to the well-known AMD root of trust certificate authority (Base64 encoded).

  • security-policy-base64: The security policy [1] describing the state and transitions allowed for the container (Base64 encoded). The SHA256 hash of the decoded value should match the attestation report host_data. This value is stored in the nodes.snp.host_data table.

  • reference-info-base64: The COSE Sign1 document containing the measurement [2] of the utility VM (UVM) used to launch the container (Base64 encoded). The measurement contained in the document payload should match the report measurement. If set, the value is stored in the nodes.snp.uvm_endorsements table and new nodes must present measurement endorsements from the same issuer (did:x509) to be trusted.

The location of the security context directory is passed to the container’s startup command as the UVM_SECURITY_CONTEXT_DIR environment variable. The name of an alternative environment variable may be specified as the value of the --snp-security-context-dir-var CLI argument, if an alternative trust root is needed.

Tip

See samples/config/start_config_aci_sev_snp.json for a sample node configuration for ACI deployments.

Non-ACI Deployment#

For non-ACI deployments, the certificate chain for VCEK will need to be retrieved from an endorsement server, as specified in the snp_endorsements_servers configuration section. For example, for the well-known AMD endorsement server, the value should be set to:

"attestation": {
    "snp_endorsements_servers": [
        {
            "type": "AMD",
            "url": "kdsintf.amd.com"
        }
    ]
}

Tip

See samples/config/start_config_amd_sev_snp.json for a sample node configuration for non-ACI deployments.

Note

The CCF node will fetch the endorsements from the server on startup, which may cause substantial deployment delays (up to tens of seconds) depending on network latency and endpoint throttling.

Governance Proposals#

The following governance proposals can be issued to add/remove these trusted values, e.g. when upgrading the service (see Code Upgrade):

  • add_snp_host_data/remove_snp_host_data: To add/remove a trusted security policy, e.g. when adding a new trusted container image as part of the code upgrade procedure.

  • add_snp_uvm_endorsement/add_snp_uvm_endorsement: To add remove a trusted UVM endorsement (ACI deployment only).

  • add_snp_measurement/remove_snp_measurement: To add/remove a trusted measurement.

Footnotes