Do not clone additional info into each ServerHandshaker.

This is important, as with unary request the runtime will keep a cache of ServerHandshaker instances

Author: Juliette Pretot

grpc_attestation/src/server.rs

@@ -151,8 +151,7 @@ where
                     .map_err(|error| {
                         error_logger.log_error(&format!("Couldn't create self attestation behavior: {:?}", error));
                         Status::internal("")
-                    })?,
-                    additional_info,
+                    })?
             );
             while !handshaker.is_completed() {
                 let incoming_message = request_stream.next()
@@ -167,7 +166,7 @@ where
                     })?;
 
                 let outgoing_message = handshaker
-                    .next_step(&incoming_message.body)
+                    .next_step(&incoming_message.body, additional_info.clone())
                     .map_err(|error| {
                         error_logger.log_error(&format!("Couldn't process handshake message: {:?}", error));
                         Status::aborted("")

remote_attestation/rust/src/handshaker.rs

@@ -329,40 +329,45 @@ pub struct ServerHandshaker {
     /// Collection of previously sent and received messages.
     /// Signed transcript is sent in messages to prevent replay attacks.
     transcript: Transcript,
-    /// Additional info about the server, including configuration information and proof of
-    /// inclusion in a verifiable log.
-    additional_info: Vec<u8>,
 }
 
 impl ServerHandshaker {
     /// Creates [`ServerHandshaker`] with `ServerHandshakerState::ExpectingClientIdentity`
     /// state.
-    pub fn new(behavior: AttestationBehavior, additional_info: Vec<u8>) -> Self {
+    pub fn new(behavior: AttestationBehavior) -> Self {
         Self {
             behavior,
             state: ServerHandshakerState::ExpectingClientHello,
             transcript: Transcript::new(),
-            additional_info,
         }
     }
 
     /// Processes incoming `message` and returns a serialized remote attestation message.
     /// If [`None`] is returned, then no messages should be sent out to the client.
-    pub fn next_step(&mut self, message: &[u8]) -> anyhow::Result<Option<Vec<u8>>> {
-        self.next_step_util(message).map_err(|error| {
-            self.state = ServerHandshakerState::Aborted;
-            error
-        })
+    pub fn next_step(
+        &mut self,
+        message: &[u8],
+        additional_info: Vec<u8>,
+    ) -> anyhow::Result<Option<Vec<u8>>> {
+        self.next_step_util(message, additional_info)
+            .map_err(|error| {
+                self.state = ServerHandshakerState::Aborted;
+                error
+            })
     }
 
-    fn next_step_util(&mut self, message: &[u8]) -> anyhow::Result<Option<Vec<u8>>> {
+    fn next_step_util(
+        &mut self,
+        message: &[u8],
+        additional_info: Vec<u8>,
+    ) -> anyhow::Result<Option<Vec<u8>>> {
         let deserialized_message =
             deserialize_message(message).context("Couldn't deserialize message")?;
         match deserialized_message {
             MessageWrapper::ClientHello(client_hello) => match &self.state {
                 ServerHandshakerState::ExpectingClientHello => {
                     let server_identity = self
-                        .process_client_hello(client_hello)
+                        .process_client_hello(client_hello, additional_info)
                         .context("Couldn't process client hello message")?;
                     let serialized_server_identity = server_identity
                         .serialize()
@@ -429,6 +434,7 @@ impl ServerHandshaker {
     fn process_client_hello(
         &mut self,
         client_hello: ClientHello,
+        additional_info: Vec<u8>,
     ) -> anyhow::Result<ServerIdentity> {
         // Create server identity message.
         let key_negotiator = KeyNegotiator::create(KeyNegotiatorType::Server)
@@ -448,7 +454,6 @@ impl ServerHandshaker {
                 .as_ref()
                 .context("Couldn't get TEE certificate")?;
 
-            let additional_info = self.additional_info.clone();
             let attestation_info =
                 create_attestation_info(signer, additional_info.as_ref(), tee_certificate)
                     .context("Couldn't get attestation info")?;

remote_attestation/rust/src/tests/handshaker.rs

@@ -27,6 +27,7 @@ use assert_matches::assert_matches;
 
 const TEE_MEASUREMENT: &str = "Test TEE measurement";
 const DATA: [u8; 10] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+const ADDITIONAL_INFO: [u8; 15] = *br"Additional Info";
 
 fn create_handshakers() -> (ClientHandshaker, ServerHandshaker) {
     let bidirectional_attestation =
@@ -47,8 +48,7 @@ fn create_handshakers() -> (ClientHandshaker, ServerHandshaker) {
         AttestationBehavior::create_bidirectional_attestation(&[], TEE_MEASUREMENT.as_bytes())
             .unwrap();
 
-    let additional_info = br"Additional Info".to_vec();
-    let server_handshaker = ServerHandshaker::new(bidirectional_attestation, additional_info);
+    let server_handshaker = ServerHandshaker::new(bidirectional_attestation);
 
     (client_handshaker, server_handshaker)
 }
@@ -71,7 +71,7 @@ fn test_handshake() {
         .expect("Couldn't create client hello message");
 
     let server_identity = server_handshaker
-        .next_step(&client_hello)
+        .next_step(&client_hello, ADDITIONAL_INFO.into())
         .expect("Couldn't process client hello message")
         .expect("Empty server identity message");
 
@@ -82,7 +82,7 @@ fn test_handshake() {
     assert!(client_handshaker.is_completed());
 
     let result = server_handshaker
-        .next_step(&client_identity)
+        .next_step(&client_identity, ADDITIONAL_INFO.into())
         .expect("Couldn't process client identity message");
     assert_matches!(result, None);
     assert!(server_handshaker.is_completed());
@@ -122,7 +122,7 @@ fn test_invalid_message_after_initialization() {
     let result = client_handshaker.create_client_hello();
     assert_matches!(result, Err(_));
 
-    let result = server_handshaker.next_step(&invalid_message);
+    let result = server_handshaker.next_step(&invalid_message, ADDITIONAL_INFO.into());
     assert_matches!(result, Err(_));
     assert!(server_handshaker.is_aborted());
 }
@@ -137,8 +137,11 @@ fn test_invalid_message_after_hello() {
     assert_matches!(result, Err(_));
     assert!(client_handshaker.is_aborted());
 
-    let server_identity = server_handshaker.next_step(&client_hello).unwrap().unwrap();
-    let result = server_handshaker.next_step(&invalid_message);
+    let server_identity = server_handshaker
+        .next_step(&client_hello, ADDITIONAL_INFO.into())
+        .unwrap()
+        .unwrap();
+    let result = server_handshaker.next_step(&invalid_message, ADDITIONAL_INFO.into());
     assert_matches!(result, Err(_));
     assert!(server_handshaker.is_aborted());
 
@@ -152,7 +155,10 @@ fn test_invalid_message_after_identities() {
     let invalid_message = vec![INVALID_MESSAGE_HEADER];
 
     let client_hello = client_handshaker.create_client_hello().unwrap();
-    let server_identity = server_handshaker.next_step(&client_hello).unwrap().unwrap();
+    let server_identity = server_handshaker
+        .next_step(&client_hello, ADDITIONAL_INFO.into())
+        .unwrap()
+        .unwrap();
     let client_identity = client_handshaker
         .next_step(&server_identity)
         .unwrap()
@@ -162,11 +168,11 @@ fn test_invalid_message_after_identities() {
     assert_matches!(result, Err(_));
     assert!(client_handshaker.is_aborted());
 
-    let result = server_handshaker.next_step(&invalid_message);
+    let result = server_handshaker.next_step(&invalid_message, ADDITIONAL_INFO.into());
     assert_matches!(result, Err(_));
     assert!(server_handshaker.is_aborted());
 
-    let result = server_handshaker.next_step(&client_identity);
+    let result = server_handshaker.next_step(&client_identity, ADDITIONAL_INFO.into());
     assert_matches!(result, Err(_));
 }
 
@@ -177,7 +183,7 @@ fn test_replay_server_identity() {
 
     let first_client_hello = first_client_handshaker.create_client_hello().unwrap();
     let first_server_identity = first_server_handshaker
-        .next_step(&first_client_hello)
+        .next_step(&first_client_hello, ADDITIONAL_INFO.into())
         .unwrap()
         .unwrap();
 
@@ -194,7 +200,7 @@ fn test_replay_client_identity() {
 
     let first_client_hello = first_client_handshaker.create_client_hello().unwrap();
     let first_server_identity = first_server_handshaker
-        .next_step(&first_client_hello)
+        .next_step(&first_client_hello, ADDITIONAL_INFO.into())
         .unwrap()
         .unwrap();
     let first_client_identity = first_client_handshaker
@@ -204,10 +210,10 @@ fn test_replay_client_identity() {
 
     let second_client_hello = second_client_handshaker.create_client_hello().unwrap();
     let _ = second_server_handshaker
-        .next_step(&second_client_hello)
+        .next_step(&second_client_hello, ADDITIONAL_INFO.into())
         .unwrap()
         .unwrap();
-    let result = second_server_handshaker.next_step(&first_client_identity);
+    let result = second_server_handshaker.next_step(&first_client_identity, ADDITIONAL_INFO.into());
     assert_matches!(result, Err(_));
 }