Extract peer certificate if client is verified

Author: madoll

lib/logstash/inputs/tcp.rb

@@ -23,7 +23,7 @@
 # #### Accepting log4j2 logs
 #
 # Log4j2 can send JSON over a socket, and we can use that combined with our tcp
-# input to accept the logs. 
+# input to accept the logs.
 #
 # First, we need to configure your application to send logs in JSON over a
 # socket. The following log4j2.xml accomplishes this task.
@@ -179,13 +179,13 @@ def close
   end
 
   def decode_buffer(client_ip_address, client_address, client_port, codec, proxy_address,
-                    proxy_port, tbuf, socket)
+                    proxy_port, tbuf, socket, cert_subject = "")
     codec.decode(tbuf) do |event|
       if @proxy_protocol
         event.set(PROXY_HOST_FIELD, proxy_address) unless event.get(PROXY_HOST_FIELD)
         event.set(PROXY_PORT_FIELD, proxy_port) unless event.get(PROXY_PORT_FIELD)
       end
-      enqueue_decorated(event, client_ip_address, client_address, client_port, socket)
+      enqueue_decorated(event, client_ip_address, client_address, client_port, socket, cert_subject)
     end
   end
 
@@ -257,15 +257,15 @@ def handle_socket(socket)
     flush_codec(codec, client_ip_address, client_address, client_port, socket)
   end
 
-  def enqueue_decorated(event, client_ip_address, client_address, client_port, socket)
+  def enqueue_decorated(event, client_ip_address, client_address, client_port, socket, cert_subject = "")
     event.set(HOST_FIELD, client_address) unless event.get(HOST_FIELD)
     event.set(HOST_IP_FIELD, client_ip_address) unless event.get(HOST_IP_FIELD)
     event.set(PORT_FIELD, client_port) unless event.get(PORT_FIELD)
-    event.set(SSLSUBJECT_FIELD, socket.peer_cert.subject.to_s) if socket && @ssl_enable && @ssl_verify && event.get(SSLSUBJECT_FIELD).nil?
+    event.set(SSLSUBJECT_FIELD, cert_subject) if !cert_subject.empty? && @ssl_enable && @ssl_verify && event.get(SSLSUBJECT_FIELD).nil?
     decorate(event)
     @output_queue << event
   end
-  
+
   def server?
     @mode == "server"
   end

lib/logstash/inputs/tcp/decoder_impl.rb

@@ -13,7 +13,7 @@ def initialize(codec, tcp)
     @first_read = true
   end
 
-  def decode(channel_addr, data)
+  def decode(channel_addr, data, cert_subject = "")
     bytes = Java::byte[data.readableBytes].new
     data.getBytes(0, bytes)
     data.release
@@ -22,7 +22,7 @@ def decode(channel_addr, data)
       tbuf = init_first_read(channel_addr, tbuf)
     end
     @tcp.decode_buffer(@ip_address, @address, @port, @codec,
-                       @proxy_address, @proxy_port, tbuf, nil)
+                       @proxy_address, @proxy_port, tbuf, nil, cert_subject)
   end
 
   def copy

src/main/java/org/logstash/tcp/Decoder.java

@@ -12,8 +12,9 @@ public interface Decoder {
      * Decode data coming from specific {@link SocketAddress} session.
      * @param key {@link SocketAddress}
      * @param message Data {@link ByteBuf} for this address
+     * @param peerSslCertSubject String The subject of the peer's SSL certificate
      */
-    void decode(SocketAddress key, ByteBuf message);
+    void decode(SocketAddress key, ByteBuf message, String peerSslCertSubject);
 
     /**
      * Creates a copy of this decoder, that has all internal meta data cleared.

src/main/java/org/logstash/tcp/InputLoop.java

@@ -12,6 +12,8 @@
 import io.netty.channel.socket.SocketChannel;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
 import io.netty.handler.ssl.SslContext;
+import io.netty.handler.ssl.SslHandler;
+import javax.net.ssl.SSLPeerUnverifiedException;
 import io.netty.util.concurrent.Future;
 import io.netty.util.concurrent.GenericFutureListener;
 import org.apache.logging.log4j.Logger;
@@ -201,7 +203,17 @@ private static final class DecoderAdapter extends ChannelInboundHandlerAdapter {
 
             @Override
             public void channelRead(final ChannelHandlerContext ctx, final Object msg) {
-                decoder.decode(ctx.channel().remoteAddress(), (ByteBuf) msg);
+                String sslPeerCertSubject = "";
+                SslHandler sslhandler = (SslHandler) ctx.channel().pipeline().get(SslHandler.class);
+                if (sslhandler != null) {
+                    try {
+                        sslPeerCertSubject = sslhandler.engine().getSession().getPeerCertificateChain()[0].getSubjectDN().getName();
+                    } catch(SSLPeerUnverifiedException e) {
+                    } catch(Exception e) {
+                        logger.error("Error when getting peer SSL certificate: " + e);
+                    }
+                }
+                decoder.decode(ctx.channel().remoteAddress(), (ByteBuf) msg, sslPeerCertSubject);
             }
 
             @Override