Password Authentication - System.ArgumentException: data

[okarpov]

This is with the latest nuget package

System.ArgumentException: data
at Renci.SshNet.Security.Cryptography.BlockCipher.Encrypt(Byte[] input, Int32 offset, Int32 length)
at Renci.SshNet.Session.SendMessage(Message message)
at Renci.SshNet.PasswordAuthenticationMethod.Authenticate(Session session)
at Renci.SshNet.ClientAuthentication.TryAuthenticate(ISession session, AuthenticationState authenticationState, String[] allowedAuthenticationMethods, SshAuthenticationException& authenticationException)
at Renci.SshNet.ClientAuthentication.Authenticate(IConnectionInfoInternal connectionInfo, ISession session)
at Renci.SshNet.ConnectionInfo.Authenticate(ISession session, IServiceFactory serviceFactory)
at Renci.SshNet.Session.ConnectAsync(CancellationToken cancellationToken)
at Renci.SshNet.BaseClient.CreateAndConnectSessionAsync(CancellationToken cancellationToken)
at Renci.SshNet.BaseClient.ConnectAsync(CancellationToken cancellationToken)

[WojciechNagorski]

@okarpov We need a description of the context of what you want do do.
What version of .NET do you use?
Can you provide the source code or mini repro?

[okarpov]

This is connecting to VPS via SSH using username and password.
Code runs in multi-task scenario under .Net 8.0 + Windows 11

no code to reproduce because of this error is not constant.

[WojciechNagorski]

@okarpov You have to provide more detail or help as to reproduce the problem, if not I going to close this issue.
Can you describe the environment? More information about SSH server, version and what kind of server.

What do you mean by "multi-task", async code or threads. You can prepare a small console application that simulates what you do with this tasks.

[Rob-Hague]

Seemingly related to #805

[WojciechNagorski]

We can merge #818 but this will not fix the problem. This is simply adding a better error message.

[okarpov]

Seemingly related to #805

yes, seems so

so this is simplified version of my code which works with +1000 Sftp and Ssh connections.
It connects to Ubuntu Server VPSs with from 20.04 to 22.04 versions.

runThread = new Thread(async () =>
{
    foreach (var vps in vpss)
    {
        Task ot = Task.Run(async () =>
        {
            Renci.SshNet.ConnectionInfo con = new Renci.SshNet.ConnectionInfo(vps.IP, vps.SSHPort, vps.UserName,
                    new PasswordAuthenticationMethod(vps.UserName, vps.Password),
                        new PrivateKeyAuthenticationMethod("rsa.key"));

                vps.SFTP = new SftpClient(con);
                vps.SFTP.HostKeyReceived += (sender, e) =>
                {
                    e.CanTrust = true;
                };

                var sftptask = vps.SFTP.ConnectAsync(CancellationToken.None);
                    using (FileStream fs = new FileStream(Path.GetFullPath($"{_workspace}\\Data\\{vps.IP}.zip"), FileMode.Open, FileAccess.Read, FileShare.Read))
                    {
                        await sftptask.ConfigureAwait(false);
                        vps.SFTP.UploadFile(fs, $"/home/{Path.GetFileName(fs.Name)}", true,
                        (u) =>
                        {
                            vps.Log = $"Uploading {fs.Name}: " + u + Environment.NewLine;
                        });
                    }

            vps.SSH = new SshClient(con);

            vps.SSH.HostKeyReceived += (sender, e) =>
            {
                e.CanTrust = true;
            };
            var sshc = vps.SSH.ConnectAsync(CancellationToken.None);
            await sshc.ConfigureAwait(false);
            var cmd = vps.SSH.CreateCommand(ssh);

            var ires = cmd.BeginExecute();
            string res = cmd.EndExecute(ires);
        }
    }
});

[Rob-Hague]

Maybe it is a race between

SSH.NET/src/Renci.SshNet/Session.cs

Line 1042 in 8e23633

var paddingMultiplier = _clientCipher is null ? (byte) 8 : Math.Max((byte) 8, _serverCipher.MinimumSize);

and

SSH.NET/src/Renci.SshNet/Session.cs

Line 1436 in 8e23633

_clientCipher = _keyExchange.CreateClientCipher();

[okarpov]

Maybe it is a race between

SSH.NET/src/Renci.SshNet/Session.cs

Line 1042 in 8e23633

var paddingMultiplier = _clientCipher is null ? (byte) 8 : Math.Max((byte) 8, _serverCipher.MinimumSize);

and

SSH.NET/src/Renci.SshNet/Session.cs

Line 1436 in 8e23633

_clientCipher = _keyExchange.CreateClientCipher();

_clientCipher is the instance field so i do not think so.

[okarpov]

also, the stack trace mentiones Renci.SshNet.Security.Cryptography.BlockCipher.Encrypt

[okarpov]

looks like this https://github.com/sshnet/SSH.NET/blob/8e2363360d61e8817da7e0256b9c9cca9984afe7/src/Renci.SshNet/Security/Cryptography/BlockCipher.cs#L79C39-L79C39

[Rob-Hague]

looks like this

Correct, and my thinking is that the length parameter is incorrect because the paddingMultiplier could be a different value depending on whether _clientCipher is null or not:

SSH.NET/src/Renci.SshNet/Session.cs

Line 1042 in 8e23633

var paddingMultiplier = _clientCipher is null ? (byte) 8 : Math.Max((byte) 8, _serverCipher.MinimumSize);

But I have not thought about it too hard.

[Rob-Hague]

@okarpov could you please try with the following patch? (save as diff.patch and run git apply diff.patch)

diff --git a/src/Renci.SshNet/Session.cs b/src/Renci.SshNet/Session.cs
index 257cf8c2..cef26c65 100644
--- a/src/Renci.SshNet/Session.cs
+++ b/src/Renci.SshNet/Session.cs
@@ -1039,7 +1039,11 @@ namespace Renci.SshNet
 
             DiagnosticAbstraction.Log(string.Format("[{0}] Sending message '{1}' to server: '{2}'.", ToHex(SessionId), message.GetType().Name, message));
 
-            var paddingMultiplier = _clientCipher is null ? (byte) 8 : Math.Max((byte) 8, _serverCipher.MinimumSize);
+            // Use locals to avoid races
+            var clientCipher = _clientCipher;
+            var clientMac = _clientMac;
+
+            var paddingMultiplier = clientCipher is null ? (byte) 8 : Math.Max((byte) 8, clientCipher.MinimumSize);
             var packetData = message.GetPacket(paddingMultiplier, _clientCompression);
 
             // take a write lock to ensure the outbound packet sequence number is incremented
@@ -1049,19 +1053,19 @@ namespace Renci.SshNet
                 byte[] hash = null;
                 var packetDataOffset = 4; // first four bytes are reserved for outbound packet sequence
 
-                if (_clientMac != null)
+                if (clientMac != null)
                 {
                     // write outbound packet sequence to start of packet data
                     Pack.UInt32ToBigEndian(_outboundPacketSequence, packetData);
 
                     // calculate packet hash
-                    hash = _clientMac.ComputeHash(packetData);
+                    hash = clientMac.ComputeHash(packetData);
                 }
 
                 // Encrypt packet data
-                if (_clientCipher != null)
+                if (clientCipher != null)
                 {
-                    packetData = _clientCipher.Encrypt(packetData, packetDataOffset, packetData.Length - packetDataOffset);
+                    packetData = clientCipher.Encrypt(packetData, packetDataOffset, packetData.Length - packetDataOffset);
                     packetDataOffset = 0;
                 }
 

[okarpov]

@okarpov could you please try with the following patch? (save as diff.patch and run git apply diff.patch)

diff --git a/src/Renci.SshNet/Session.cs b/src/Renci.SshNet/Session.cs
index 257cf8c2..cef26c65 100644
--- a/src/Renci.SshNet/Session.cs
+++ b/src/Renci.SshNet/Session.cs
@@ -1039,7 +1039,11 @@ namespace Renci.SshNet
 
             DiagnosticAbstraction.Log(string.Format("[{0}] Sending message '{1}' to server: '{2}'.", ToHex(SessionId), message.GetType().Name, message));
 
-            var paddingMultiplier = _clientCipher is null ? (byte) 8 : Math.Max((byte) 8, _serverCipher.MinimumSize);
+            // Use locals to avoid races
+            var clientCipher = _clientCipher;
+            var clientMac = _clientMac;
+
+            var paddingMultiplier = clientCipher is null ? (byte) 8 : Math.Max((byte) 8, clientCipher.MinimumSize);
             var packetData = message.GetPacket(paddingMultiplier, _clientCompression);
 
             // take a write lock to ensure the outbound packet sequence number is incremented
@@ -1049,19 +1053,19 @@ namespace Renci.SshNet
                 byte[] hash = null;
                 var packetDataOffset = 4; // first four bytes are reserved for outbound packet sequence
 
-                if (_clientMac != null)
+                if (clientMac != null)
                 {
                     // write outbound packet sequence to start of packet data
                     Pack.UInt32ToBigEndian(_outboundPacketSequence, packetData);
 
                     // calculate packet hash
-                    hash = _clientMac.ComputeHash(packetData);
+                    hash = clientMac.ComputeHash(packetData);
                 }
 
                 // Encrypt packet data
-                if (_clientCipher != null)
+                if (clientCipher != null)
                 {
-                    packetData = _clientCipher.Encrypt(packetData, packetDataOffset, packetData.Length - packetDataOffset);
+                    packetData = clientCipher.Encrypt(packetData, packetDataOffset, packetData.Length - packetDataOffset);
                     packetDataOffset = 0;
                 }
 

still getting two exceptions

System.ArgumentException: data
   at Renci.SshNet.Security.Cryptography.BlockCipher.Encrypt(Byte[] data, Int32 offset, Int32 length) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Security\Cryptography\BlockCipher.cs:line 105
   at Renci.SshNet.Session.SendMessage(Message message) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Session.cs:line 1070
   at Renci.SshNet.PasswordAuthenticationMethod.Authenticate(Session session) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\PasswordAuthenticationMethod.cs:line 98
   at Renci.SshNet.AuthenticationMethod.Renci.SshNet.IAuthenticationMethod.Authenticate(ISession session) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\AuthenticationMethod.cs:line 60
   at Renci.SshNet.ClientAuthentication.TryAuthenticate(ISession session, AuthenticationState authenticationState, String[] allowedAuthenticationMethods, SshAuthenticationException& authenticationException) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\ClientAuthentication.cs:line 116
   at Renci.SshNet.ClientAuthentication.Authenticate(IConnectionInfoInternal connectionInfo, ISession session) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\ClientAuthentication.cs:line 66
   at Renci.SshNet.ConnectionInfo.Authenticate(ISession session, IServiceFactory serviceFactory) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\ConnectionInfo.cs:line 452
   at Renci.SshNet.Session.ConnectAsync(CancellationToken cancellationToken) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Session.cs:line 763
   at Renci.SshNet.BaseClient.CreateAndConnectSessionAsync(CancellationToken cancellationToken) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\BaseClient.cs:line 545
   at Renci.SshNet.BaseClient.ConnectAsync(CancellationToken cancellationToken) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\BaseClient.cs:line 284





Renci.SshNet.Common.SshException: Message type 52 is not valid in the current context.
   at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle, TimeSpan timeout) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Session.cs:line 989
   at Renci.SshNet.Session.Renci.SshNet.ISession.WaitOnHandle(WaitHandle waitHandle) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Session.cs:line 839
   at Renci.SshNet.Channels.Channel.WaitOnHandle(WaitHandle waitHandle) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Channels\Channel.cs:line 511
   at Renci.SshNet.Channels.ChannelSession.Open() in SSH.NET-rsa-sha2-256\src\Renci.SshNet\Channels\ChannelSession.cs:line 73
   at Renci.SshNet.SshCommand.BeginExecute(AsyncCallback callback, Object state) in SSH.NET-rsa-sha2-256\src\Renci.SshNet\SshCommand.cs:line 256
   at Renci.SshNet.SshCommand.BeginExecute() in SSH.NET-rsa-sha2-256\src\Renci.SshNet\SshCommand.cs:line 171

[okarpov]

with nuget lbrary:

Renci.SshNet.Common.SshException: Message type 52 is not valid in the current context.
   at Renci.SshNet.SshMessageFactory.Create(Byte messageNumber)
   at Renci.SshNet.Session.ReceiveMessage(Socket socket)
   at Renci.SshNet.Session.MessageListener()
--- End of stack trace from previous location ---
   at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle, TimeSpan timeout)
   at Renci.SshNet.Channels.ChannelSession.Open()
   at Renci.SshNet.SshCommand.BeginExecute(AsyncCallback callback, Object state)