Module: RubySMB::Server::ServerClient::Negotiation

Included in:
RubySMB::Server::ServerClient
Defined in:
lib/ruby_smb/server/server_client/negotiation.rb

Instance Method Summary collapse

Instance Method Details

#do_negotiate_smb1(request) ⇒ Object 



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# File 'lib/ruby_smb/server/server_client/negotiation.rb', line 32

def do_negotiate_smb1(request)
  client_dialects = request.dialects.map(&:dialect_string).map(&:value)

  if client_dialects.include?(Client::SMB1_DIALECT_SMB2_WILDCARD) && \
      @server.dialects.any? { |dialect| Dialect[dialect].order == Dialect::ORDER_SMB2 }
    response = SMB2::Packet::NegotiateResponse.new
    response.smb2_header.credits = 1
    response.security_mode.signing_enabled = 1
    response.dialect_revision = SMB2::SMB2_WILDCARD_REVISION
    response.server_guid = @server.guid

    response.max_transact_size = 0x800000
    response.max_read_size = 0x800000
    response.max_write_size = 0x800000
    response.system_time.set(Time.now)
    response.security_buffer_offset = response.security_buffer.abs_offset
    response.security_buffer = process_gss.buffer
    return response
  end

  server_dialects = @server.dialects.select { |dialect| Dialect[dialect].order == Dialect::ORDER_SMB1 }
  dialect = (server_dialects & client_dialects).first
  if dialect.nil?
    # 'NT LM 0.12' is currently the only supported dialect
    # see: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-cifs/80850595-e301-4464-9745-58e4945eb99b
    response = SMB1::Packet::NegotiateResponse.new
    response.parameter_block.word_count = 1
    response.parameter_block.dialect_index = 0xffff
    response.data_block.byte_count = 0
    return response
  end

  response = SMB1::Packet::NegotiateResponseExtended.new
  response.parameter_block.dialect_index = client_dialects.index(dialect)
  response.parameter_block.max_mpx_count = 50
  response.parameter_block.max_number_vcs = 1
  response.parameter_block.max_buffer_size = 16644
  response.parameter_block.max_raw_size = 65536
  server_time = Time.now
  response.parameter_block.system_time.set(server_time)
  response.parameter_block.server_time_zone = server_time.utc_offset
  response.data_block.server_guid = @server.guid
  response.data_block.security_blob = process_gss.buffer

  @dialect = dialect
  response
end

#do_negotiate_smb2(request) ⇒ Object 



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# File 'lib/ruby_smb/server/server_client/negotiation.rb', line 80

def do_negotiate_smb2(request)
  client_dialects = request.dialects.map { |d| "0x%04x" % d }
  server_dialects = @server.dialects.select { |dialect| Dialect[dialect].order == Dialect::ORDER_SMB2 }
  dialect = (server_dialects & client_dialects).first

  response = SMB2::Packet::NegotiateResponse.new
  response.smb2_header.credits = 1
  response.smb2_header.message_id = request.smb2_header.message_id
  response.security_mode.signing_enabled = 1
  response.server_guid = @server.guid
  response.max_transact_size = 0x800000
  response.max_read_size = 0x800000
  response.max_write_size = 0x800000
  response.system_time.set(Time.now)
  if dialect.nil?
    # see: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/b39f253e-4963-40df-8dff-2f9040ebbeb1
    # > If a common dialect is not found, the server MUST fail the request with STATUS_NOT_SUPPORTED.
    response.smb2_header.nt_status = WindowsError::NTStatus::STATUS_NOT_SUPPORTED.value
    return response
  end

  contexts = []
  hash_algorithm = hash_value = nil
  if dialect == '0x0311'
    # see: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/b39f253e-4963-40df-8dff-2f9040ebbeb1
    nc = request.find_negotiate_context(SMB2::NegotiateContext::SMB2_PREAUTH_INTEGRITY_CAPABILITIES)
    hash_algorithm = SMB2::PreauthIntegrityCapabilities::HASH_ALGORITM_MAP[nc&.data&.hash_algorithms&.first]
    hash_value = "\x00" * 64
    unless hash_algorithm
      response.smb2_header.nt_status = WindowsError::NTStatus::STATUS_INVALID_PARAMETER.value
      return response
    end

    contexts << SMB2::NegotiateContext.new(
      context_type: SMB2::NegotiateContext::SMB2_PREAUTH_INTEGRITY_CAPABILITIES,
      data: {
        hash_algorithms: [ SMB2::PreauthIntegrityCapabilities::SHA_512 ],
        salt: SecureRandom.random_bytes(32)
      }
    )

    nc = request.find_negotiate_context(SMB2::NegotiateContext::SMB2_ENCRYPTION_CAPABILITIES)
    ciphers = nc&.data&.ciphers
    if ciphers
      cipher = ciphers.find { |cipher| SMB2::EncryptionCapabilities::ENCRYPTION_ALGORITHM_MAP.include?(cipher) }
      @cipher_id = cipher unless cipher.nil?
    end

    contexts << SMB2::NegotiateContext.new(
      context_type: SMB2::NegotiateContext::SMB2_ENCRYPTION_CAPABILITIES,
      data: {
        ciphers: [ @cipher_id ]
      }
    )
  elsif dialect == '0x0300' || dialect == '0x0302'
    if request.capabilities.encryption == 1
      response.capabilities.encryption = 1
      @cipher_id = SMB2::EncryptionCapabilities::AES_128_CCM
    else
      response.capabilities = 0
    end
  end

  # the order in which the response is built is important to ensure it is valid
  response.dialect_revision = dialect.to_i(16)
  response.security_buffer_offset = response.security_buffer.abs_offset
  response.security_buffer = process_gss.buffer
  if dialect == '0x0311'
    response.negotiate_context_offset = response.negotiate_context_list.abs_offset
    contexts.each { |nc| response.add_negotiate_context(nc) }
  end
  @preauth_integrity_hash_algorithm = hash_algorithm
  @preauth_integrity_hash_value = hash_value

  if dialect == '0x0311'
    update_preauth_hash(request)
    update_preauth_hash(response)
  end

  @dialect = dialect
  response
end

#handle_negotiate(raw_request) ⇒ Object

Handle an SMB negotiation request. Once negotiation is complete, the state will be updated to :session_setup. At this point the @dialect will have been set along with other dialect-specific values.

Parameters:

  • raw_request (String) —

    the negotiation request to process



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# File 'lib/ruby_smb/server/server_client/negotiation.rb', line 12

def handle_negotiate(raw_request)
  response = nil
  case raw_request[0...4].unpack1('L>')
  when RubySMB::SMB1::SMB_PROTOCOL_ID
    request = SMB1::Packet::NegotiateRequest.read(raw_request)
    response = do_negotiate_smb1(request) if request.is_a?(SMB1::Packet::NegotiateRequest)
  when RubySMB::SMB2::SMB2_PROTOCOL_ID
    request = SMB2::Packet::NegotiateRequest.read(raw_request)
    response = do_negotiate_smb2(request) if request.is_a?(SMB2::Packet::NegotiateRequest)
  end

  if response.nil?
    disconnect!
  else
    send_packet(response)
  end

  nil
end