diff --git a/Documentation/networking/secid.txt b/Documentation/networking/secid.txt
new file mode 100644
index 0000000..95ea067
--- /dev/null
+++ b/Documentation/networking/secid.txt
@@ -0,0 +1,14 @@
+flowi structure:
+
+The secid member in the flow structure is used in LSMs (e.g. SELinux) to indicate
+the label of the flow. This label of the flow is currently used in selecting
+matching labeled xfrm(s).
+
+If this is an outbound flow, the label is derived from the socket, if any, or
+the incoming packet this flow is being generated as a response to (e.g. tcp
+resets, timewait ack, etc.). It is also conceivable that the label could be
+derived from other sources such as process context, device, etc., in special
+cases, as may be appropriate.
+
+If this is an inbound flow, the label is derived from the IPSec security
+associations, if any, used by the packet.
diff --git a/include/net/flow.h b/include/net/flow.h
index 04d89f7..1cee5a8 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -78,6 +78,7 @@
 #define fl_icmp_type	uli_u.icmpt.type
 #define fl_icmp_code	uli_u.icmpt.code
 #define fl_ipsec_spi	uli_u.spi
+	__u32           secid;	/* used by xfrm; see secid.txt */
 } __attribute__((__aligned__(BITS_PER_LONG/8)));
 
 #define FLOW_DIR_IN	0