netfilter: synproxy: add common uapi for SYNPROXY infrastructure

This new UAPI file is going to be used by the xt and nft common SYNPROXY
infrastructure. It is needed to avoid duplicated code.
Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_SYNPROXY.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NF_SYNPROXY_H
+#define _NF_SYNPROXY_H
+
+#include <linux/types.h>
+
+#define NF_SYNPROXY_OPT_MSS		0x01
+#define NF_SYNPROXY_OPT_WSCALE		0x02
+#define NF_SYNPROXY_OPT_SACK_PERM	0x04
+#define NF_SYNPROXY_OPT_TIMESTAMP	0x08
+#define NF_SYNPROXY_OPT_ECN		0x10
+
+struct nf_synproxy_info {
+	__u8	options;
+	__u8	wscale;
+	__u16	mss;
+};
+
+#endif /* _NF_SYNPROXY_H */

include/uapi/linux/netfilter/xt_SYNPROXY.h

@@ -2,18 +2,14 @@
 #ifndef _XT_SYNPROXY_H
 #define _XT_SYNPROXY_H
 
-#include <linux/types.h>
+#include <linux/netfilter/nf_SYNPROXY.h>
 
-#define XT_SYNPROXY_OPT_MSS		0x01
-#define XT_SYNPROXY_OPT_WSCALE		0x02
-#define XT_SYNPROXY_OPT_SACK_PERM	0x04
-#define XT_SYNPROXY_OPT_TIMESTAMP	0x08
-#define XT_SYNPROXY_OPT_ECN		0x10
+#define XT_SYNPROXY_OPT_MSS		NF_SYNPROXY_OPT_MSS
+#define XT_SYNPROXY_OPT_WSCALE		NF_SYNPROXY_OPT_WSCALE
+#define XT_SYNPROXY_OPT_SACK_PERM	NF_SYNPROXY_OPT_SACK_PERM
+#define XT_SYNPROXY_OPT_TIMESTAMP	NF_SYNPROXY_OPT_TIMESTAMP
+#define XT_SYNPROXY_OPT_ECN		NF_SYNPROXY_OPT_ECN
 
-struct xt_synproxy_info {
-	__u8	options;
-	__u8	wscale;
-	__u16	mss;
-};
+#define xt_synproxy_info		nf_synproxy_info
 
 #endif /* _XT_SYNPROXY_H */