[SECMARK]: Add secmark support to core networking.

Add a secmark field to the skbuff structure, to allow security subsystems to
place security markings on network packets.  This is similar to the nfmark
field, except is intended for implementing security policy, rather than than
networking policy.

This patch was already acked in principle by Dave Miller.

Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/Kconfig b/net/Kconfig
index ccadc8e..c6cec5a 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -66,6 +66,13 @@
 
 endif # if INET
 
+config NETWORK_SECMARK
+	bool "Security Marking"
+	help
+	  This enables security marking of network packets, similar
+	  to nfmark, but designated for security purposes.
+	  If you are unsure how to answer this question, answer N.
+
 menuconfig NETFILTER
 	bool "Network packet filtering (replaces ipchains)"
 	---help---