[PATCH nf-next] netfilter: nft_ct: track register operations

[Pablo Neira Ayuso <pablo@netfilter.org>]

Check if the destination register already contains the data that this
ct store expression performs. This allows to skip this redundant
operation. If the destination contains a different selector, update
the register tracking information.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_ct.c | 47 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 5adf8bb628a8..66ee49045d8e 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -677,6 +677,32 @@ static int nft_ct_get_dump(struct sk_buff *skb, const struct nft_expr *expr)
 	return -1;
 }
 
+static bool nft_ct_get_reduce(struct nft_regs_track *track,
+			      const struct nft_expr *expr)
+{
+	const struct nft_ct *priv = nft_expr_priv(expr);
+	const struct nft_ct *ct;
+
+	if (!track->regs[priv->dreg].selector ||
+	    track->regs[priv->dreg].selector->ops != expr->ops) {
+		track->regs[priv->dreg].selector = expr;
+		track->regs[priv->dreg].bitwise = NULL;
+		return false;
+	}
+
+	ct = nft_expr_priv(track->regs[priv->dreg].selector);
+	if (priv->key != ct->key) {
+		track->regs[priv->dreg].selector = expr;
+		track->regs[priv->dreg].bitwise = NULL;
+		return false;
+	}
+
+	if (!track->regs[priv->dreg].bitwise)
+		return true;
+
+	return nft_expr_reduce_bitwise(track, expr);
+}
+
 static int nft_ct_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
 {
 	const struct nft_ct *priv = nft_expr_priv(expr);
@@ -710,8 +736,28 @@ static const struct nft_expr_ops nft_ct_get_ops = {
 	.init		= nft_ct_get_init,
 	.destroy	= nft_ct_get_destroy,
 	.dump		= nft_ct_get_dump,
+	.reduce		= nft_ct_get_reduce,
 };
 
+static bool nft_ct_set_reduce(struct nft_regs_track *track,
+			      const struct nft_expr *expr)
+{
+	int i;
+
+	for (i = 0; i < NFT_REG32_NUM; i++) {
+		if (!track->regs[i].selector)
+			continue;
+
+		if (track->regs[i].selector->ops != &nft_ct_get_ops)
+			continue;
+
+		track->regs[i].selector = NULL;
+		track->regs[i].bitwise = NULL;
+	}
+
+	return false;
+}
+
 static const struct nft_expr_ops nft_ct_set_ops = {
 	.type		= &nft_ct_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_ct)),
@@ -719,6 +765,7 @@ static const struct nft_expr_ops nft_ct_set_ops = {
 	.init		= nft_ct_set_init,
 	.destroy	= nft_ct_set_destroy,
 	.dump		= nft_ct_set_dump,
+	.reduce		= nft_ct_set_reduce,
 };
 
 #ifdef CONFIG_NF_CONNTRACK_ZONES
-- 
2.30.2