feat(rendezvous-server): verify the device certificate chain

use trusted CAs specified by the optional `trusted_device_keys_path`
configuration variable to verify the device certificate chain.

if the configuration variable is not specified we still validate
that the chain is correct but all the certificates will be trusted.

Signed-off-by: Miguel Martín <[email protected]>

HOWTO.md

@@ -532,6 +532,7 @@ session_store_driver:
   Directory:
     path: /path/to/stores/rendezvous_sessions
 trusted_manufacturer_keys_path: /path/to/keys/manufacturer_cert.pem
+trusted_device_keys_path: /path/to/keys/device_ca_cert.pem
 max_wait_seconds: ~
 bind: "0.0.0.0:8082"
 ```
@@ -568,7 +569,9 @@ Where:
       Please refer to the [Database management section](#database-management) on how to initialize databases.
 - `session_store_driver`: path to a directory that will hold session
   information.
-- `trusted_manufacturer_keys_path`: path to the Manufacturer Certificate.
+- `trusted_manufacturer_keys_path` [OPTIONAL]: path to the Manufacturer Certificate.
+- `trusted_device_keys_path` [OPTIONAL]: path to the CA certificates used for
+device certificate chain verification.
 - `max_wait_seconds`: [OPTIONAL] maximum wait time in seconds for the TO0 and
   TO1 protocols (default 2592000).
 - `bind`: IP address and port that the Rendezvous Server will take.

admin-tool/src/aio/configure.rs

@@ -219,6 +219,11 @@ fn generate_configs(aio_dir: &Path, config_args: &Configuration) -> Result<(), E
                     .expect("Failed to build absolute path"),
             ),
 
+            trusted_device_keys_path: Some(
+                AbsolutePathBuf::new(aio_dir.join("keys").join("device_ca_cert.pem"))
+                    .expect("Failed to build absolute path"),
+            ),
+
             max_wait_seconds: None,
 
             bind: get_bind(config_args.listen_port_rendezvous_server)?,

examples/config/rendezvous-server.yml

@@ -6,5 +6,6 @@ session_store_driver:
   Directory:
     path: /path/to/stores/rendezvous_sessions
 trusted_manufacturer_keys_path: /path/to/keys/manufacturer_cert.pem
+trusted_device_keys_path: /path/to/keys/device_ca_cert.pem
 max_wait_seconds: ~
 bind: "0.0.0.0:8082"

rendezvous-server/src/handlers_to0.rs

@@ -157,8 +157,14 @@ pub(super) async fn ownersign(
         }
         Some(v) => v,
     };
-    //let device_pubkey = match device_cert_chain.verify_from_x5bag(&user_data.trusted_device_keys) {
-    let device_pubkey = match device_cert_chain.insecure_verify_without_root_verification() {
+
+    let verify_device_pubkey = if let Some(trusted_device_keys) = &user_data.trusted_device_keys {
+        device_cert_chain.verify_from_x5bag(trusted_device_keys)
+    } else {
+        device_cert_chain.insecure_verify_without_root_verification()
+    };
+
+    let device_pubkey = match verify_device_pubkey {
         Err(cert_chain_err) => {
             log::debug!("Error verifying device certificate: {:?}", cert_chain_err);
             return Err(Error::new(

rendezvous-server/src/main.rs

@@ -25,6 +25,8 @@ impl fdo_store::MetadataLocalKey for RendezvousStoreMetadataKey {
 struct RendezvousUD {
     max_wait_seconds: u32,
     trusted_manufacturer_keys: Option<X5Bag>,
+    trusted_device_keys: Option<X5Bag>,
+
     store: Box<dyn Store<fdo_store::ReadWriteOpen, Guid, StoredItem, RendezvousStoreMetadataKey>>,
 
     session_store: Arc<fdo_http_wrapper::server::SessionStore>,
@@ -102,11 +104,28 @@ async fn main() -> Result<()> {
         .transpose()
         .context("Error loading trusted manufacturer keys")?;
 
+    // Load trusted CA certs for device certificate chain verification
+    let trusted_device_keys = settings
+        .trusted_device_keys_path
+        .as_ref()
+        .map(|path| -> Result<X5Bag, anyhow::Error> {
+            let trusted_device_keys = {
+                let contents = std::fs::read(path)
+                    .with_context(|| format!("Error reading trusted device keys at {}", &path))?;
+                X509::stack_from_pem(&contents).context("Error parsing trusted device keys")?
+            };
+            X5Bag::with_certs(trusted_device_keys)
+                .context("Error building trusted device keys X5Bag")
+        })
+        .transpose()
+        .context("Error loading trusted device keys")?;
+
     // Initialize handler stores
     let user_data = Arc::new(RendezvousUD {
         max_wait_seconds,
         store,
         trusted_manufacturer_keys,
+        trusted_device_keys,
 
         session_store: session_store.clone(),
     });

test/fdo/rendezvous-server.yml

@@ -6,5 +6,6 @@ session_store_driver:
   Directory:
     path: /etc/fdo/stores/rendezvous_sessions
 trusted_manufacturer_keys_path: /etc/fdo/keys/manufacturer_cert.pem
+trusted_device_keys_path: /etc/fdo/keys/device_ca_cert.pem
 max_wait_seconds: ~
 bind: "0.0.0.0:8082"

test/fmf/tests/onboarding/run-onboarding.sh

@@ -158,6 +158,7 @@ session_store_driver:
   Directory:
     path: ${STORES_DIR}/rendezvous_sessions
 trusted_manufacturer_keys_path: ${KEYS_DIR}/manufacturer_cert.pem
+trusted_device_keys_path: ${KEYS_DIR}/device_ca_cert.pem
 max_wait_seconds: ~
 bind: "0.0.0.0:8082"
 EOF

util/src/servers/configuration/rendezvous_server.rs

@@ -13,9 +13,12 @@ pub struct RendezvousServerSettings {
     #[serde(with = "serde_yaml::with::singleton_map")]
     pub session_store_driver: StoreConfig,
 
-    // Trusted keys
+    // Trusted manufacturer public keys
     pub trusted_manufacturer_keys_path: Option<AbsolutePathBuf>,
 
+    // Trusted CA certs for device cert chain verification
+    pub trusted_device_keys_path: Option<AbsolutePathBuf>,
+
     // Other info
     pub max_wait_seconds: Option<u32>,