SCTP: Allow ADD_IP to work with AUTH for backward compatibility.

This patch adds a tunable that will allow ADD_IP to work without
AUTH for backward compatibility.  The default value is off since
the default value for ADD_IP is off as well.  People who need
to use ADD-IP with older implementations take risks of connection
hijacking and should consider upgrading or turning this tunable on.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 41f1039..44f2672 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -212,6 +212,7 @@
 	
 	/* Flag to indicate if addip is enabled. */
 	int addip_enable;
+	int addip_noauth_enable;
 
 	/* Flag to indicate if PR-SCTP is enabled. */
 	int prsctp_enable;
@@ -249,6 +250,7 @@
 #define sctp_local_addr_list		(sctp_globals.local_addr_list)
 #define sctp_local_addr_lock		(sctp_globals.addr_list_lock)
 #define sctp_addip_enable		(sctp_globals.addip_enable)
+#define sctp_addip_noauth		(sctp_globals.addip_noauth_enable)
 #define sctp_prsctp_enable		(sctp_globals.prsctp_enable)
 #define sctp_auth_enable		(sctp_globals.auth_enable)