Improve tls info for openssl with kprobes (#1177)

Instead of going through the socket fd, addresses are obtained in kprobe/tcp_sendmsg on ssl write and kprobe/tcp_recvmsg on ssl read. The tcp kprobes and the openssl uprobes communicate through the id->sslInfo bpf map.

tap/tlstapper/ssllib_hooks.go

@@ -14,6 +14,8 @@ type sslHooks struct {
 	sslWriteExRetProbe link.Link
 	sslReadExProbe     link.Link
 	sslReadExRetProbe  link.Link
+	tcpSendmsg         link.Link
+	tcpRecvmsg         link.Link
 }
 
 func (s *sslHooks) installUprobes(bpfObjects *tlsTapperObjects, sslLibraryPath string) error {
@@ -103,6 +105,16 @@ func (s *sslHooks) installSslHooks(bpfObjects *tlsTapperObjects, sslLibrary *lin
 		}
 	}
 
+	s.tcpSendmsg, err = link.Kprobe("tcp_sendmsg", bpfObjects.TcpSendmsg, nil)
+	if err != nil {
+		return errors.Wrap(err, 0)
+	}
+
+	s.tcpRecvmsg, err = link.Kprobe("tcp_recvmsg", bpfObjects.TcpRecvmsg, nil)
+	if err != nil {
+		return errors.Wrap(err, 0)
+	}
+
 	return nil
 }
 
@@ -149,5 +161,17 @@ func (s *sslHooks) close() []error {
 		}
 	}
 
+	if s.tcpSendmsg != nil {
+		if err := s.tcpSendmsg.Close(); err != nil {
+			returnValue = append(returnValue, err)
+		}
+	}
+
+	if s.tcpRecvmsg != nil {
+		if err := s.tcpRecvmsg.Close(); err != nil {
+			returnValue = append(returnValue, err)
+		}
+	}
+
 	return returnValue
 }