Add CLI argument for SNP context directory (#5686)

.snpcc_canary

@@ -1,4 +1,4 @@
   ___         ___    ___
  (. =)     Y (0 0)  (* *)    Y
-   O     \     .   \- | -/ /
-/-xXx--//-----x=x--/-xXx--/---x---->
+   O     \     .      |    /
+/-xXx--//-----x=x--/-xXx--/---x---->>

CHANGELOG.md

@@ -15,7 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Updated `nghttp2` from `1.51.0` to `1.55.1`.
 - Converted SNP attestation UVM endorsements from integer to arbitrary string.
 - Updated Intel SGX PSW from 2.17 to 2.20 (#5616)
-- Path to the enclave file should now be passed as `--enclave-file` CLI argument to `cchost`, rather than `enclave.file` entry within configuration file. This is to ensure the path to the application file is attested on Confidential Containers/SNP, even if the configuration itself is provided from un-attested storage. The configuration entry is deprecated, and will be removed in a future release.
+- Path to the enclave file should now be passed as `--enclave-file` CLI argument to `cchost`, rather than `enclave.file` entry within configuration file. A potential SNP security context directory environment variable override, where desired, should now be passed as `--snp-security-context-dir-var` CLI argument to `cchost`, rather than `attestation.environment.security_context_directory` entry within configuration file. This is to ensure that these values are attested on Confidential Containers/SNP, even if the configuration itself is provided from un-attested storage, such as an external mount. The configuration entries are deprecated, and will be removed in a future release.
 - Added `ccf.SnpAttestation.verifySnpAttestation()` endpoint for TypeScript apps. (#5653)
 - Secret sharing used for ledger recovery now relies on a much simpler implementation that requires no external dependencies. Note that while the code still accepts shares generated by the old code for now, it only generates shares with the new implementation. As a result, a DR attempt that would downgrade the code to a version that pre-dates this change, after having previously picked it up, would not succeed if a reshare had already taken place (#5655).
 

doc/host_config_schema/cchost_config.json

@@ -9,7 +9,7 @@
       "properties": {
         "file": {
           "type": "string",
-          "description": "Path to enclave application"
+          "description": "DEPRECATED: Replaced by --enclave-file CLI argument. Path to enclave application"
         },
         "platform": {
           "type": "string",
@@ -25,7 +25,7 @@
         }
       },
       "description": "This section includes configuration for the enclave application launched by this node",
-      "required": [],
+      "required": ["platform", "type"],
       "additionalProperties": false
     },
     "network": {
@@ -449,11 +449,11 @@
           "properties": {
             "security_context_directory": {
               "type": ["string", "null"],
-              "description": "Name of environment variable (e.g. ``UVM_SECURITY_CONTEXT_DIR``) specifying the directory containing the security context files (i.e. ``host-amd-cert-base64``, ``security-policy-base64`` and ``reference-info-base64``)."
+              "description": "DEPRECATED: Replaced by --snp-security-context-dir-var CLI argument. Name of environment variable (e.g. ``UVM_SECURITY_CONTEXT_DIR``) specifying the directory containing the security context files (i.e. ``host-amd-cert-base64``, ``security-policy-base64`` and ``reference-info-base64``)."
             }
           },
           "description": "Environment variables required to provide best auditability and serviceability for Azure Container Instance deployments (SEV-SNP only)",
-          "required": ["security_context_directory"],
+          "required": [],
           "additionalProperties": false
         },
         "snp_endorsements_servers": {
@@ -475,7 +475,7 @@
             "required": ["url"],
             "additionalProperties": false
           },
-          "description": "List of servers used to retrieve attestation report endorsement certificates (SEV-SNP only). The first server in the list is always used and other servers are only specified as fallback. If set, endorsements from ``environment.security_context_directory`` are ignored"
+          "description": "List of servers used to retrieve attestation report endorsement certificates (SEV-SNP only). The first server in the list is always used and other servers are only specified as fallback. If set, attestation endorsements from ``--snp-security-context-dir-var`` are ignored, but uvm endorsements from that directory are still used."
         }
       },
       "description": "This section includes configuration for the attestation for AMD SEV-SNP platform (ignored for SGX)",
@@ -680,6 +680,6 @@
       "minimum": 0
     }
   },
-  "required": ["network", "command"],
+  "required": ["enclave", "network", "command"],
   "additionalProperties": false
 }

doc/operations/platforms/snp.rst

@@ -24,7 +24,7 @@ Azure Confidential ACI provides a security context directory containing the foll
 - ``security-policy-base64``: The security policy [#security_policy]_ 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 :ref:`audit/builtin_maps:``nodes.snp.host_data``` table.
 - ``reference-info-base64``: The COSE Sign1 document containing the measurement [#measurement]_ 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 :ref:`audit/builtin_maps:``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 this environment variable should be specified as the value of the ``security_context_directory`` in the :ref:`operations/configuration:``environment``` configuration section.
+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 :ccf_repo:`samples/config/start_config_aci_sev_snp.json` for a sample node configuration for ACI deployments.
 

src/host/configuration.h

@@ -168,8 +168,8 @@ namespace host
   };
 
   DECLARE_JSON_TYPE_WITH_OPTIONAL_FIELDS(CCHostConfig::Enclave);
-  DECLARE_JSON_REQUIRED_FIELDS(CCHostConfig::Enclave);
-  DECLARE_JSON_OPTIONAL_FIELDS(CCHostConfig::Enclave, file, type, platform);
+  DECLARE_JSON_REQUIRED_FIELDS(CCHostConfig::Enclave, type, platform);
+  DECLARE_JSON_OPTIONAL_FIELDS(CCHostConfig::Enclave, file);
 
   DECLARE_JSON_TYPE_WITH_OPTIONAL_FIELDS(CCHostConfig::OutputFiles);
   DECLARE_JSON_REQUIRED_FIELDS(CCHostConfig::OutputFiles);
@@ -225,10 +225,9 @@ namespace host
     CCHostConfig::Command, service_certificate_file, start, join, recover);
 
   DECLARE_JSON_TYPE_WITH_BASE_AND_OPTIONAL_FIELDS(CCHostConfig, CCFConfig);
-  DECLARE_JSON_REQUIRED_FIELDS(CCHostConfig, command);
+  DECLARE_JSON_REQUIRED_FIELDS(CCHostConfig, enclave, command);
   DECLARE_JSON_OPTIONAL_FIELDS(
     CCHostConfig,
-    enclave,
     tick_interval,
     slow_io_logging_threshold,
     node_client_interface,

src/host/main.cpp

@@ -124,6 +124,15 @@ int main(int argc, char** argv)
     enclave_file_path,
     "Path to enclave application (security critical)");
 
+  std::string snp_security_context_dir_var = "UVM_SECURITY_CONTEXT_DIR";
+  app
+    .add_option(
+      "--snp-security-context-dir-var",
+      snp_security_context_dir_var,
+      "Name of environment variable specifying the directory containing the "
+      "SNP UVM security context files (security critical)")
+    ->capture_default_str();
+
   try
   {
     app.parse(argc, argv);
@@ -502,10 +511,20 @@ int main(int argc, char** argv)
     startup_config.snapshot_tx_interval = config.snapshots.tx_count;
 
     if (config.attestation.environment.security_context_directory.has_value())
+    {
+      LOG_FAIL_FMT(
+        "DEPRECATED: security_context_dir was specified in config file! This "
+        "should be removed from the config, and passed directly to the CLI. "
+        "Note that the CLI provides a default value, which may be sufficient");
+
+      snp_security_context_dir_var =
+        config.attestation.environment.security_context_directory.value();
+    }
+
+    if (config.enclave.platform == host::EnclavePlatform::SNP)
     {
       auto dir = read_required_environment_variable(
-        config.attestation.environment.security_context_directory.value(),
-        "security context directory");
+        snp_security_context_dir_var, "security context directory");
 
       constexpr auto security_policy_filename = "security-policy-base64";
       startup_config.attestation.environment.security_policy =

tests/config.jinja

@@ -20,11 +20,7 @@
   "node_data_json_file": {{ node_data_json_file|tojson }},
   "attestation":
   {
-    "snp_endorsements_servers": {{ snp_endorsements_servers|tojson }},
-    "environment":
-    {
-      "security_context_directory": {{ snp_security_context_directory_envvar|tojson }}
-    }
+    "snp_endorsements_servers": {{ snp_endorsements_servers|tojson }}
   },
   "service_data_json_file": {{ service_data_json_file|tojson }},
   "command": {

tests/infra/remote.py

@@ -789,7 +789,7 @@ def __init__(
                 service_cert_file=service_cert_file,
                 snp_endorsements_servers=snp_endorsements_servers_list,
                 node_pid_file=node_pid_file,
-                snp_security_context_directory_envvar=snp_security_context_directory_envvar,
+                snp_security_context_directory_envvar=snp_security_context_directory_envvar,  # Ignored by current jinja, but passed for LTS compat
                 ignore_first_sigterm=ignore_first_sigterm,
                 node_address=remote_class.get_node_address(node_address),
                 follow_redirect=follow_redirect,
@@ -847,6 +847,11 @@ def __init__(
                 "--enclave-file",
                 self.enclave_file,
             ]
+            if snp_security_context_directory_envvar is not None:
+                cmd += [
+                    "--snp-security-context-dir-var",
+                    snp_security_context_directory_envvar,
+                ]
 
         if start_type == StartType.start:
             members_info = kwargs.get("members_info")