Implement validation for duplicate nonces (#893)

* - Add Server nonce validation for duplicate nonces. - Add configuration flag to bypass validation exceptions * Add ITransportChannel.CurrentToken interface for nonce validation.
OPCFoundation · Jan 30, 2020 · 636f5c0 · 636f5c0
1 parent a1faa0f
commit 636f5c0
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Showing 8 changed files with 68 additions and 5 deletions.
diff --git a/SampleApplications/SDK/Opc.Ua.Client/Session.cs b/SampleApplications/SDK/Opc.Ua.Client/Session.cs
@@ -40,6 +40,7 @@
 using System.Xml;
 using System.Threading.Tasks;
 using System.Reflection;
+using Opc.Ua.Bindings;
 
 namespace Opc.Ua.Client
 {
@@ -311,7 +312,7 @@ private void ValidateClientConfiguration(ApplicationConfiguration configuration)
         /// <summary>
         /// Validates the server nonce and security parameters of user identity.
         /// </summary>
-        private void ValidateServerNonce(IUserIdentity identity, byte[] serverNonce, string securityPolicyUri)
+        private void ValidateServerNonce(IUserIdentity identity, byte[] serverNonce, string securityPolicyUri, byte[] previousServerNonce)
         {
             // skip validation if server nonce is not used for encryption.
             if (String.IsNullOrEmpty(securityPolicyUri) || securityPolicyUri == SecurityPolicies.None)
@@ -326,6 +327,15 @@ private void ValidateServerNonce(IUserIdentity identity, byte[] serverNonce, str
                 {
                     throw ServiceResultException.Create(StatusCodes.BadNonceInvalid, "Server nonce is not the correct length or not random enough.");
                 }
+
+                // check that new nonce is different from the previously returned server nonce.
+                if (previousServerNonce!= null && Utils.CompareNonce(serverNonce, previousServerNonce))
+                {
+                    if (!m_configuration.SecurityConfiguration.SuppressNonceValidationErrors)
+                    {
+                        throw ServiceResultException.Create(StatusCodes.BadNonceInvalid, "Server nonce is equal with previously returned nonce.");
+                    }
+                }
             }
         }
 
@@ -1082,7 +1092,7 @@ public void Reconnect()
                 }
 
                 // validate server nonce and security parameters for user identity.
-                ValidateServerNonce(m_identity, m_serverNonce, securityPolicyUri);
+                ValidateServerNonce(m_identity, m_serverNonce, securityPolicyUri, m_previousServerNonce);
 
                 // sign data with user token.
                 UserIdentityToken identityToken = m_identity.GetIdentityToken();
@@ -1150,6 +1160,7 @@ public void Reconnect()
                 lock (SyncRoot)
                 {
                     Utils.Trace("Session RECONNECT completed successfully.");
+                    m_previousServerNonce = m_serverNonce;
                     m_serverNonce = serverNonce;
                     m_reconnecting = false;
                     publishCount = m_subscriptions.Count;
@@ -2571,8 +2582,15 @@ public ReferenceDescriptionCollection FetchReferences(NodeId nodeId)
                     securityPolicyUri = m_endpoint.Description.SecurityPolicyUri;
                 }
 
+                byte[] previousServerNonce = null;
+
+                if (TransportChannel.CurrentToken!= null)
+                {
+                    previousServerNonce = TransportChannel.CurrentToken.ServerNonce;
+                }
+
                 // validate server nonce and security parameters for user identity.
-                ValidateServerNonce(identity, serverNonce, securityPolicyUri);
+                ValidateServerNonce(identity, serverNonce, securityPolicyUri, previousServerNonce);
 
                 // sign data with user token.
                 SignatureData userTokenSignature = identityToken.Sign(dataToSign, securityPolicyUri);
@@ -2625,6 +2643,7 @@ public ReferenceDescriptionCollection FetchReferences(NodeId nodeId)
                     // save nonces.
                     m_sessionName = sessionName;
                     m_identity = identity;
+                    m_previousServerNonce = previousServerNonce;
                     m_serverNonce = serverNonce;
                     m_serverCertificate = serverCertificate;
 
@@ -2735,7 +2754,7 @@ public void UpdateSession(IUserIdentity identity, StringCollection preferredLoca
             }
 
             // validate server nonce and security parameters for user identity.
-            ValidateServerNonce(identity, serverNonce, securityPolicyUri);
+            ValidateServerNonce(identity, serverNonce, securityPolicyUri, m_previousServerNonce);
 
             // sign data with user token.
             identityToken = identity.GetIdentityToken();
@@ -2771,6 +2790,7 @@ public void UpdateSession(IUserIdentity identity, StringCollection preferredLoca
                     m_identity = identity;
                 }
 
+                m_previousServerNonce = m_serverNonce;
                 m_serverNonce = serverNonce;
                 m_preferredLocales = preferredLocales;
 
@@ -4390,6 +4410,7 @@ private void OnRaisePublishNotification(object state)
         private object m_handle;
         private IUserIdentity m_identity;
         private byte[] m_serverNonce;
+        private byte[] m_previousServerNonce;
         private X509Certificate2 m_serverCertificate;
         private long m_publishCounter;
         private DateTime m_lastKeepAliveTime;

diff --git a/Stack/Opc.Ua.Core/Schema/ApplicationConfiguration.cs b/Stack/Opc.Ua.Core/Schema/ApplicationConfiguration.cs
@@ -1037,6 +1037,19 @@ public CertificateTrustList TrustedHttpsCertificates
                 }
             }
         }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the server nonce validation errors should be suppressed.
+        /// </summary>
+        /// <remarks>
+        /// If set to true the server nonce validation errors are suppressed.
+        /// </remarks>
+        [DataMember(IsRequired = false, EmitDefaultValue = false, Order = 19)]
+        public bool SuppressNonceValidationErrors
+        {
+            get { return m_suppressNonceValidationErrors; }
+            set { m_suppressNonceValidationErrors = value; }
+        }
         #endregion
 
         #region Private Fields
@@ -1056,6 +1069,7 @@ public CertificateTrustList TrustedHttpsCertificates
         private ushort m_minCertificateKeySize;
         private bool m_addAppCertToTrustedStore;
         private bool m_sendCertificateChain;
+        private bool m_suppressNonceValidationErrors;
         #endregion
     }
     #endregion

diff --git a/Stack/Opc.Ua.Core/Schema/ApplicationConfiguration.xsd b/Stack/Opc.Ua.Core/Schema/ApplicationConfiguration.xsd
@@ -57,6 +57,7 @@
       <xs:element name="TrustedUserCertificates" type="CertificateTrustList" minOccurs="0" />
       <xs:element name="HttpsIssuerCertificates" type="CertificateTrustList" minOccurs="0" />
       <xs:element name="TrustedHttpsCertificates" type="CertificateTrustList" minOccurs="0" />
+      <xs:element name="SuppressNonceValidationErrors" type="xs:boolean" minOccurs="0" />
     </xs:sequence>
   </xs:complexType>
 

diff --git a/Stack/Opc.Ua.Core/Stack/Client/WcfChannelBase.cs b/Stack/Opc.Ua.Core/Stack/Client/WcfChannelBase.cs
@@ -208,6 +208,14 @@ public ServiceMessageContext MessageContext
             }
         }
 
+        /// <summary>
+        ///  Gets the the channel's current security token.
+        /// </summary>
+        public ChannelToken CurrentToken
+        {
+            get { return null; }
+        }
+
         /// <summary>
         /// Gets or sets the default timeout for requests send via the channel.
         /// </summary>

diff --git a/Stack/Opc.Ua.Core/Stack/Https/HttpsTransportChannel.cs b/Stack/Opc.Ua.Core/Stack/Https/HttpsTransportChannel.cs
@@ -52,6 +52,11 @@ public ServiceMessageContext MessageContext
             get { return m_quotas.MessageContext; }
         }
 
+        public ChannelToken CurrentToken
+        {
+            get { return null; }
+        }
+
         public int OperationTimeout
         {
             get { return m_operationTimeout; }

diff --git a/Stack/Opc.Ua.Core/Stack/Tcp/UaSCBinaryChannel.Symmetric.cs b/Stack/Opc.Ua.Core/Stack/Tcp/UaSCBinaryChannel.Symmetric.cs
@@ -23,7 +23,7 @@ public partial class UaSCUaBinaryChannel
         /// <summary>
         /// Returns the current security token.
         /// </summary>
-        protected ChannelToken CurrentToken => m_currentToken;
+        protected internal ChannelToken CurrentToken => m_currentToken;
 
         /// <summary>
         /// Returns the current security token.

diff --git a/Stack/Opc.Ua.Core/Stack/Tcp/UaSCBinaryTransportChannel.cs b/Stack/Opc.Ua.Core/Stack/Tcp/UaSCBinaryTransportChannel.cs
@@ -81,6 +81,14 @@ public IMessageSocket Socket
         /// </summary>
         public ServiceMessageContext MessageContext => m_quotas.MessageContext;
 
+        /// <summary>
+        ///  Gets the the channel's current security token.
+        /// </summary>
+        public ChannelToken CurrentToken
+        {
+            get { lock (m_lock) { return m_channel?.CurrentToken; } }
+        }
+
         /// <summary>
         /// Gets or sets the default timeout for requests send via the channel.
         /// </summary>

diff --git a/Stack/Opc.Ua.Core/Stack/Transport/ITransportChannel.cs b/Stack/Opc.Ua.Core/Stack/Transport/ITransportChannel.cs
@@ -13,6 +13,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Opc.Ua.Bindings;
 
 namespace Opc.Ua
 {
@@ -54,6 +55,11 @@ public interface ITransportChannel : IDisposable
         /// </summary>
         ServiceMessageContext MessageContext { get; }
 
+        /// <summary>
+        /// Gets the the channel's current security token.
+        /// </summary>
+        ChannelToken CurrentToken { get; }
+
         /// <summary>
         /// Gets or sets the default timeout for requests send via the channel.
         /// </summary>