net: macsec: Expose MACSEC_SALT_LEN definition to user space

Expose MACSEC_SALT_LEN definition to user space to be
used in various user space applications such as iproute.
Iproute will use this as part of adding macsec extended
packet number support.
Reviewed-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
Link: https://lore.kernel.org/r/20220818153229.4721-1-ehakim@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/macsec.h

@@ -14,7 +14,6 @@
 #define MACSEC_DEFAULT_PN_LEN 4
 #define MACSEC_XPN_PN_LEN 8
 
-#define MACSEC_SALT_LEN 12
 #define MACSEC_NUM_AN 4 /* 2 bits for the association number */
 
 typedef u64 __bitwise sci_t;

include/uapi/linux/if_macsec.h

@@ -22,6 +22,8 @@
 
 #define MACSEC_KEYID_LEN 16
 
+#define MACSEC_SALT_LEN 12
+
 /* cipher IDs as per IEEE802.1AE-2018 (Table 14-1) */
 #define MACSEC_CIPHER_ID_GCM_AES_128 0x0080C20001000001ULL
 #define MACSEC_CIPHER_ID_GCM_AES_256 0x0080C20001000002ULL