Disallow CASE and PASE establishment attempts over existing secure se…

…ssions.

Per spec, CASE and PASE establishment needs to happen via unauthenticated
messages.  We should ignore Sigma1 or PBKDFParamsRequest received over a CASE or
PASE (or group) session.

src/protocols/secure_channel/CASEServer.cpp

@@ -73,7 +73,14 @@ CHIP_ERROR CASEServer::OnUnsolicitedMessageReceived(const PayloadHeader & payloa
 CHIP_ERROR CASEServer::OnMessageReceived(Messaging::ExchangeContext * ec, const PayloadHeader & payloadHeader,
                                          System::PacketBufferHandle && payload)
 {
-    ChipLogProgress(Inet, "CASE Server received Sigma1 message. Starting handshake. EC %p", ec);
+    if (!ec->GetSessionHandle()->IsUnauthenticatedSession())
+    {
+        ChipLogError(Inet, "CASE Server received Sigma1 message %s EC %p", "over encrypted session. Ignoring.", ec);
+        return CHIP_ERROR_INCORRECT_STATE;
+    }
+
+    ChipLogProgress(Inet, "CASE Server received Sigma1 message %s EC %p", ". Starting handshake.", ec);
+
     CHIP_ERROR err = InitCASEHandshake(ec);
     SuccessOrExit(err);
 

src/protocols/secure_channel/PASESession.cpp

@@ -794,6 +794,13 @@ CHIP_ERROR PASESession::ValidateReceivedMessage(ExchangeContext * exchange, cons
     {
         mExchangeCtxt = exchange;
     }
+
+    if (!mExchangeCtxt->GetSessionHandle()->IsUnauthenticatedSession())
+    {
+        ChipLogError(SecureChannel, "PASESession received PBKDFParamRequest over encrypted session.  Ignoring.");
+        return CHIP_ERROR_INCORRECT_STATE;
+    }
+
     mExchangeCtxt->UseSuggestedResponseTimeout(kExpectedHighProcessingTime);
 
     VerifyOrReturnError(!msg.IsNull(), CHIP_ERROR_INVALID_ARGUMENT);

src/transport/Session.h

@@ -222,6 +222,8 @@ class Session
 
     bool IsSecureSession() const { return GetSessionType() == SessionType::kSecure; }
 
+    bool IsUnauthenticatedSession() const { return GetSessionType() == SessionType::kUnauthenticated; }
+
     void DispatchSessionEvent(SessionDelegate::Event event)
     {
         // Holders might remove themselves when notified.