Pin UVM roots of trust and add snp_uvm_endorsements_file to configuration (#5867)

.snpcc_canary

@@ -2,4 +2,4 @@
  (. =)     Y (0 0)  (x X)    Y
    O     \     o      |    /
 /-xXx--//-----x=x--/-xXx--/---x---->>>--/
-...
+......

CHANGELOG.md

@@ -10,7 +10,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 [5.0.0-dev10]: https://github.com/microsoft/CCF/releases/tag/ccf-5.0.0-dev10
 
 - The `url` field in `snp_endorsements_servers` can now contain environment variables that will be resolved at startup, such as "$Fabric_NodeIPOrFQDN:2377" (#5862).
-- Add a `new snp_security_policy_file` configuration value under `attestation`, superseding the lookup from `$UVM_SECURITY_CONTEXT_DIR`. The value can contain environment variables, for example: `"snp_security_policy_file": "$UVM_SECURITY_CONTEXT_DIR/security-policy-base64"`.
+- Add a new `snp_security_policy_file` configuration value under `attestation`, superseding the lookup from `$UVM_SECURITY_CONTEXT_DIR`. The value can contain environment variables, for example: `"snp_security_policy_file": "$UVM_SECURITY_CONTEXT_DIR/security-policy-base64"`.
+- Add a new `snp_uvm_endorsements_file` configuration value under `attestation`, superseding the lookup from `$UVM_SECURITY_CONTEXT_DIR`. The value can contain environment variables, for example: `"snp_uvm_endorsements_file": "$UVM_SECURITY_CONTEXT_DIR/reference-info-base64"`. This value can come from an untrusted location, like `snp_security_policy_file` and AMD endorsements (fetched from `snp_endorsements_servers`), because the CCF code contains pre-defined roots of trust.
 
 ## [5.0.0-dev9]
 

doc/host_config_schema/cchost_config.json

@@ -460,6 +460,10 @@
           "type": ["string", "null"],
           "description": "Path to file containing the security policy (SEV-SNP only), can contain environment variables, such as $UVM_SECURITY_CONTEXT_DIR"
         },
+        "snp_uvm_endorsements_file": {
+          "type": ["string", "null"],
+          "description": "Path to file containing UVM endorsements as a base64-encoded COSE Sign1 (SEV-SNP only). Can contain environment variables, such as $UVM_SECURITY_CONTEXT_DIR"
+        },
         "snp_endorsements_servers": {
           "type": "array",
           "items": {

doc/operations/platforms/snp.rst

@@ -61,6 +61,7 @@ For non-Azure deployments, the certificate chain for VCEK will need to be retrie
             }
         ],
         "snp_security_policy_file": "/path/to/security-policy-base64",
+        "snp_uvm_endorsements_file": "/path/to/reference-info-base64"
     }
 
 .. tip:: See :ccf_repo:`samples/config/start_config_amd_sev_snp.json` for a sample node configuration for non-Azure deployments.

include/ccf/node/startup_config.h

@@ -57,6 +57,7 @@ struct CCFConfig
   {
     ccf::pal::snp::EndorsementsServers snp_endorsements_servers = {};
     std::optional<std::string> snp_security_policy_file = std::nullopt;
+    std::optional<std::string> snp_uvm_endorsements_file = std::nullopt;
 
     struct Environment
     {

samples/config/start_config_aci_sev_snp.json

@@ -43,6 +43,7 @@
         "url": "169.254.169.254"
       }
     ],
-    "snp_security_policy_file": "$UVM_SECURITY_CONTEXT_DIR/security-policy-base64"
+    "snp_security_policy_file": "$UVM_SECURITY_CONTEXT_DIR/security-policy-base64",
+    "snp_uvm_endorsements_file": "$UVM_SECURITY_CONTEXT_DIR/reference-info-base64"
   }
 }

samples/config/start_config_aks_sev_snp.json

@@ -34,8 +34,13 @@
     }
   },
   "attestation": {
-    "environment": {
-      "security_context_directory": "UVM_SECURITY_CONTEXT_DIR"
-    }
+    "snp_endorsements_servers": [
+      {
+        "type": "THIM",
+        "url": "169.254.169.254"
+      }
+    ],
+    "snp_security_policy_file": "/path/to/security-policy-base64",
+    "snp_uvm_endorsements_file": "/opt/confidential-containers/share/kata-containers/reference-info-base64"
   }
 }

samples/config/start_config_amd_sev_snp.json

@@ -40,6 +40,7 @@
         "url": "kdsintf.amd.com"
       }
     ],
-    "snp_security_policy_file": "/path/to/security-policy-base64"
+    "snp_security_policy_file": "/path/to/security-policy-base64",
+    "snp_uvm_endorsements_file": "/path/to/reference-info-base64"
   }
 }

src/common/configuration.h

@@ -83,7 +83,8 @@ DECLARE_JSON_OPTIONAL_FIELDS(
   CCFConfig::Attestation,
   snp_endorsements_servers,
   environment,
-  snp_security_policy_file);
+  snp_security_policy_file,
+  snp_uvm_endorsements_file);
 
 DECLARE_JSON_TYPE_WITH_OPTIONAL_FIELDS(CCFConfig);
 DECLARE_JSON_REQUIRED_FIELDS(CCFConfig, network);

src/host/main.cpp

@@ -559,6 +559,21 @@ int main(int argc, char** argv)
         files::try_slurp_string(security_policy_file);
     }
 
+    if (startup_config.attestation.snp_uvm_endorsements_file.has_value())
+    {
+      auto snp_uvm_endorsements_file =
+        startup_config.attestation.snp_uvm_endorsements_file.value();
+      LOG_DEBUG_FMT(
+        "Resolving snp_uvm_endorsements_file: {}", snp_uvm_endorsements_file);
+      snp_uvm_endorsements_file =
+        nonstd::expand_envvars_in_path(snp_uvm_endorsements_file);
+      LOG_DEBUG_FMT(
+        "Resolved snp_uvm_endorsements_file: {}", snp_uvm_endorsements_file);
+
+      startup_config.attestation.environment.uvm_endorsements =
+        files::try_slurp_string(snp_uvm_endorsements_file);
+    }
+
     for (auto endorsement_servers_it =
            startup_config.attestation.snp_endorsements_servers.begin();
          endorsement_servers_it !=

src/node/uvm_endorsements.h

@@ -51,6 +51,34 @@ namespace ccf
     std::string feed;
   };
 
+  // Roots of trust for UVM endorsements/measurement in AMD SEV-SNP attestations
+  static std::vector<UVMEndorsements> uvm_roots_of_trust = {
+    // Confidential Azure Kubertnetes Service (AKS)
+    {"did:x509:0:sha256:I__iuL25oXEVFdTP_aBLx_eT1RPHbCQ_ECBQfYZpt9s::eku:1.3.6."
+     "1.4.1.311.76.59.1.2",
+     "ContainerPlat-AMD-UVM",
+     "0"},
+    // Confidential Azure Container Instances (ACI)
+    {"did:x509:0:sha256:I__iuL25oXEVFdTP_aBLx_eT1RPHbCQ_ECBQfYZpt9s::eku:1.3.6."
+     "1.4.1.311.76.59.1.5",
+     "ConfAKS-AMD-UVM",
+     "0"}};
+
+  bool inline matches_uvm_roots_of_trust(const UVMEndorsements& endorsements)
+  {
+    for (const auto& uvm_root_of_trust : uvm_roots_of_trust)
+    {
+      if (
+        uvm_root_of_trust.did == endorsements.did &&
+        uvm_root_of_trust.feed == endorsements.feed &&
+        uvm_root_of_trust.svn <= endorsements.svn)
+      {
+        return true;
+      }
+    }
+    return false;
+  }
+
   namespace cose
   {
     static constexpr auto HEADER_PARAM_ISSUER = "iss";
@@ -311,6 +339,18 @@ namespace ccf
       phdr.feed,
       payload.sevsnpvm_guest_svn);
 
-    return {did, phdr.feed, payload.sevsnpvm_guest_svn};
+    UVMEndorsements end{did, phdr.feed, payload.sevsnpvm_guest_svn};
+
+    if (!matches_uvm_roots_of_trust(end))
+    {
+      throw std::logic_error(fmt::format(
+        "UVM endorsements did {}, feed {}, svn {} "
+        "do not match any of the known UVM roots of trust",
+        end.did,
+        end.feed,
+        end.svn));
+    }
+
+    return end;
   }
 }

tests/config.jinja

@@ -21,7 +21,8 @@
   "attestation":
   {
     "snp_endorsements_servers": {{ snp_endorsements_servers|tojson }},
-    "snp_security_policy_file": "{{ snp_security_policy_file }}"
+    "snp_security_policy_file": "{{ snp_security_policy_file }}",
+    "snp_uvm_endorsements_file": "{{ snp_uvm_endorsements_file }}"
   },
   "service_data_json_file": {{ service_data_json_file|tojson }},
   "command": {

tests/infra/network.py

@@ -197,6 +197,7 @@ class Network:
         "tick_ms",
         "max_msg_size_bytes",
         "snp_security_policy_file",
+        "snp_uvm_endorsements_file",
     ]
 
     # Maximum delay (seconds) for updates to propagate from the primary to backups

tests/infra/remote.py

@@ -620,6 +620,7 @@ class CCFRemote(object):
         follow_redirect=True,
         max_uncommitted_tx_count=0,
         snp_security_policy_file=None,
+        snp_uvm_endorsements_file=None,
         **kwargs,
     ):
         """
@@ -742,6 +743,12 @@ class CCFRemote(object):
                 "$UVM_SECURITY_CONTEXT_DIR/security-policy-base64"
             )
 
+        # Default snp_uvm_endorsements_file if not set
+        if snp_uvm_endorsements_file is None:
+            snp_uvm_endorsements_file = (
+                "$UVM_SECURITY_CONTEXT_DIR/reference-info-base64"
+            )
+
         # Validate consensus timers
         if (
             election_timeout_ms is not None
@@ -803,6 +810,7 @@ class CCFRemote(object):
                 follow_redirect=follow_redirect,
                 max_uncommitted_tx_count=max_uncommitted_tx_count,
                 snp_security_policy_file=snp_security_policy_file,
+                snp_uvm_endorsements_file=snp_uvm_endorsements_file,
                 **kwargs,
             )