diff --git a/include/net/tcp.h b/include/net/tcp.h
index 738b65f..f9abd9b 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -30,6 +30,7 @@
 #include <linux/dmaengine.h>
 #include <linux/crypto.h>
 #include <linux/cryptohash.h>
+#include <linux/kref.h>
 
 #include <net/inet_connection_sock.h>
 #include <net/inet_timewait_sock.h>
@@ -164,6 +165,7 @@
 #define TCPOPT_SACK             5       /* SACK Block */
 #define TCPOPT_TIMESTAMP	8	/* Better RTT estimations/PAWS */
 #define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
+#define TCPOPT_COOKIE		253	/* Cookie extension (experimental) */
 
 /*
  *     TCP option lengths
@@ -174,6 +176,10 @@
 #define TCPOLEN_SACK_PERM      2
 #define TCPOLEN_TIMESTAMP      10
 #define TCPOLEN_MD5SIG         18
+#define TCPOLEN_COOKIE_BASE    2	/* Cookie-less header extension */
+#define TCPOLEN_COOKIE_PAIR    3	/* Cookie pair header extension */
+#define TCPOLEN_COOKIE_MIN     (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
+#define TCPOLEN_COOKIE_MAX     (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
 
 /* But this is what stacks really send out. */
 #define TCPOLEN_TSTAMP_ALIGNED		12
@@ -1482,6 +1488,83 @@
 
 extern int tcp_cookie_generator(u32 *bakery);
 
+/**
+ *	struct tcp_cookie_values - each socket needs extra space for the
+ *	cookies, together with (optional) space for any SYN data.
+ *
+ *	A tcp_sock contains a pointer to the current value, and this is
+ *	cloned to the tcp_timewait_sock.
+ *
+ * @cookie_pair:	variable data from the option exchange.
+ *
+ * @cookie_desired:	user specified tcpct_cookie_desired.  Zero
+ *			indicates default (sysctl_tcp_cookie_size).
+ *			After cookie sent, remembers size of cookie.
+ *			Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
+ *
+ * @s_data_desired:	user specified tcpct_s_data_desired.  When the
+ *			constant payload is specified (@s_data_constant),
+ *			holds its length instead.
+ *			Range 0 to TCP_MSS_DESIRED.
+ *
+ * @s_data_payload:	constant data that is to be included in the
+ *			payload of SYN or SYNACK segments when the
+ *			cookie option is present.
+ */
+struct tcp_cookie_values {
+	struct kref	kref;
+	u8		cookie_pair[TCP_COOKIE_PAIR_SIZE];
+	u8		cookie_pair_size;
+	u8		cookie_desired;
+	u16		s_data_desired:11,
+			s_data_constant:1,
+			s_data_in:1,
+			s_data_out:1,
+			s_data_unused:2;
+	u8		s_data_payload[0];
+};
+
+static inline void tcp_cookie_values_release(struct kref *kref)
+{
+	kfree(container_of(kref, struct tcp_cookie_values, kref));
+}
+
+/* The length of constant payload data.  Note that s_data_desired is
+ * overloaded, depending on s_data_constant: either the length of constant
+ * data (returned here) or the limit on variable data.
+ */
+static inline int tcp_s_data_size(const struct tcp_sock *tp)
+{
+	return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
+		? tp->cookie_values->s_data_desired
+		: 0;
+}
+
+/**
+ *	struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
+ *
+ *	As tcp_request_sock has already been extended in other places, the
+ *	only remaining method is to pass stack values along as function
+ *	parameters.  These parameters are not needed after sending SYNACK.
+ *
+ * @cookie_bakery:	cryptographic secret and message workspace.
+ *
+ * @cookie_plus:	bytes in authenticator/cookie option, copied from
+ *			struct tcp_options_received (above).
+ */
+struct tcp_extend_values {
+	struct request_values		rv;
+	u32				cookie_bakery[COOKIE_WORKSPACE_WORDS];
+	u8				cookie_plus:6,
+					cookie_out_never:1,
+					cookie_in_always:1;
+};
+
+static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
+{
+	return (struct tcp_extend_values *)rvp;
+}
+
 extern void tcp_v4_init(void);
 extern void tcp_init(void);