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// This code is derived from jcifs smb client library <jcifs at samba dot org>
// Ported by J. Arturo <webmaster at komodosoft dot net>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using SharpCifs.Util;
using SharpCifs.Util.Sharpen;
namespace SharpCifs.Smb
{
/// <summary>To filter 0 len updates and for debugging</summary>
public class SigningDigest
{
internal static LogStream Log = LogStream.GetInstance();
private MessageDigest _digest;
private byte[] _macSigningKey;
private bool _bypass;
private int _updates;
private int _signSequence;
/// <exception cref="SharpCifs.Smb.SmbException"></exception>
public SigningDigest(byte[] macSigningKey, bool bypass)
{
try
{
_digest = MessageDigest.GetInstance("MD5");
}
catch (NoSuchAlgorithmException ex)
{
if (Log.Level > 0)
{
Runtime.PrintStackTrace(ex, Log);
}
throw new SmbException("MD5", ex);
}
this._macSigningKey = macSigningKey;
this._bypass = bypass;
_updates = 0;
_signSequence = 0;
if (Log.Level >= 5)
{
Log.WriteLine("macSigningKey:");
Hexdump.ToHexdump(Log, macSigningKey, 0, macSigningKey.Length);
}
}
/// <exception cref="SharpCifs.Smb.SmbException"></exception>
public SigningDigest(SmbTransport transport, NtlmPasswordAuthentication auth)
{
try
{
_digest = MessageDigest.GetInstance("MD5");
}
catch (NoSuchAlgorithmException ex)
{
if (Log.Level > 0)
{
Runtime.PrintStackTrace(ex, Log);
}
throw new SmbException("MD5", ex);
}
try
{
switch (SmbConstants.LmCompatibility)
{
case 0:
case 1:
case 2:
{
_macSigningKey = new byte[40];
auth.GetUserSessionKey(transport.Server.EncryptionKey, _macSigningKey, 0);
Array.Copy(auth.GetUnicodeHash(transport.Server.EncryptionKey), 0, _macSigningKey
, 16, 24);
break;
}
case 3:
case 4:
case 5:
{
_macSigningKey = new byte[16];
auth.GetUserSessionKey(transport.Server.EncryptionKey, _macSigningKey, 0);
break;
}
default:
{
_macSigningKey = new byte[40];
auth.GetUserSessionKey(transport.Server.EncryptionKey, _macSigningKey, 0);
Array.Copy(auth.GetUnicodeHash(transport.Server.EncryptionKey), 0, _macSigningKey
, 16, 24);
break;
}
}
}
catch (Exception ex)
{
throw new SmbException(string.Empty, ex);
}
if (Log.Level >= 5)
{
Log.WriteLine("LM_COMPATIBILITY=" + SmbConstants.LmCompatibility);
Hexdump.ToHexdump(Log, _macSigningKey, 0, _macSigningKey.Length);
}
}
public virtual void Update(byte[] input, int offset, int len)
{
if (Log.Level >= 5)
{
Log.WriteLine("update: " + _updates + " " + offset + ":" + len);
Hexdump.ToHexdump(Log, input, offset, Math.Min(len, 256));
Log.Flush();
}
if (len == 0)
{
return;
}
_digest.Update(input, offset, len);
_updates++;
}
public virtual byte[] Digest()
{
byte[] b;
b = _digest.Digest();
if (Log.Level >= 5)
{
Log.WriteLine("digest: ");
Hexdump.ToHexdump(Log, b, 0, b.Length);
Log.Flush();
}
_updates = 0;
return b;
}
/// <summary>Performs MAC signing of the SMB.</summary>
/// <remarks>
/// Performs MAC signing of the SMB. This is done as follows.
/// The signature field of the SMB is overwritted with the sequence number;
/// The MD5 digest of the MAC signing key + the entire SMB is taken;
/// The first 8 bytes of this are placed in the signature field.
/// </remarks>
/// <param name="data">The data.</param>
/// <param name="offset">The starting offset at which the SMB header begins.</param>
/// <param name="length">The length of the SMB data starting at offset.</param>
internal virtual void Sign(byte[] data, int offset, int length, ServerMessageBlock
request, ServerMessageBlock response)
{
request.SignSeq = _signSequence;
if (response != null)
{
response.SignSeq = _signSequence + 1;
response.VerifyFailed = false;
}
try
{
Update(_macSigningKey, 0, _macSigningKey.Length);
int index = offset + SmbConstants.SignatureOffset;
for (int i = 0; i < 8; i++)
{
data[index + i] = 0;
}
ServerMessageBlock.WriteInt4(_signSequence, data, index);
Update(data, offset, length);
Array.Copy(Digest(), 0, data, index, 8);
if (_bypass)
{
_bypass = false;
Array.Copy(Runtime.GetBytesForString("BSRSPYL "), 0, data, index,
8);
}
}
catch (Exception ex)
{
if (Log.Level > 0)
{
Runtime.PrintStackTrace(ex, Log);
}
}
finally
{
_signSequence += 2;
}
}
/// <summary>Performs MAC signature verification.</summary>
/// <remarks>
/// Performs MAC signature verification. This calculates the signature
/// of the SMB and compares it to the signature field on the SMB itself.
/// </remarks>
/// <param name="data">The data.</param>
/// <param name="offset">The starting offset at which the SMB header begins.</param>
/// <param name="length">The length of the SMB data starting at offset.</param>
internal virtual bool Verify(byte[] data, int offset, ServerMessageBlock response
)
{
Update(_macSigningKey, 0, _macSigningKey.Length);
int index = offset;
Update(data, index, SmbConstants.SignatureOffset);
index += SmbConstants.SignatureOffset;
byte[] sequence = new byte[8];
ServerMessageBlock.WriteInt4(response.SignSeq, sequence, 0);
Update(sequence, 0, sequence.Length);
index += 8;
if (response.Command == ServerMessageBlock.SmbComReadAndx)
{
SmbComReadAndXResponse raxr = (SmbComReadAndXResponse)response;
int length = response.Length - raxr.DataLength;
Update(data, index, length - SmbConstants.SignatureOffset - 8);
Update(raxr.B, raxr.Off, raxr.DataLength);
}
else
{
Update(data, index, response.Length - SmbConstants.SignatureOffset - 8);
}
byte[] signature = Digest();
for (int i = 0; i < 8; i++)
{
if (signature[i] != data[offset + SmbConstants.SignatureOffset + i])
{
if (Log.Level >= 2)
{
Log.WriteLine("signature verification failure");
Hexdump.ToHexdump(Log, signature, 0, 8);
Hexdump.ToHexdump(Log, data, offset + SmbConstants.SignatureOffset, 8);
}
return response.VerifyFailed = true;
}
}
return response.VerifyFailed = false;
}
public override string ToString()
{
return "LM_COMPATIBILITY=" + SmbConstants.LmCompatibility + " MacSigningKey=" + Hexdump.ToHexString
(_macSigningKey, 0, _macSigningKey.Length);
}
}
}
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