xtables: extend matches and targets with .usersize

In matches and targets that define a kernel-only tail to their
xt_match and xt_target data structs, add a field .usersize that
specifies up to where data is to be shared with userspace.

Performed a search for comment "Used internally by the kernel" to find
relevant matches and targets. Manually inspected the structs to derive
a valid offsetof.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/xt_TEE.c b/net/netfilter/xt_TEE.c
index 1c57ace..86b0580 100644
--- a/net/netfilter/xt_TEE.c
+++ b/net/netfilter/xt_TEE.c
@@ -133,6 +133,7 @@ static struct xt_target tee_tg_reg[] __read_mostly = {
 		.family     = NFPROTO_IPV4,
 		.target     = tee_tg4,
 		.targetsize = sizeof(struct xt_tee_tginfo),
+		.usersize   = offsetof(struct xt_tee_tginfo, priv),
 		.checkentry = tee_tg_check,
 		.destroy    = tee_tg_destroy,
 		.me         = THIS_MODULE,
@@ -144,6 +145,7 @@ static struct xt_target tee_tg_reg[] __read_mostly = {
 		.family     = NFPROTO_IPV6,
 		.target     = tee_tg6,
 		.targetsize = sizeof(struct xt_tee_tginfo),
+		.usersize   = offsetof(struct xt_tee_tginfo, priv),
 		.checkentry = tee_tg_check,
 		.destroy    = tee_tg_destroy,
 		.me         = THIS_MODULE,