From fa17b17ea74a21a44596f3212466ff3d2d3ede8e Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Sat, 2 Sep 2023 10:37:39 +0200
Subject: [PATCH] evaluate: revisit anonymous set with single element
 optimization

This patch reworks it to perform this optimization from the evaluation
step of the relational expression. Hence, when optimizing for protocol
flags, use OP_EQ instead of OP_IMPLICIT, that is:

	tcp flags { syn }

becomes (to represent an exact match):

	tcp flags == syn

given OP_IMPLICIT and OP_EQ are not equivalent for flags.

01167c393a12 ("evaluate: do not remove anonymous set with protocol flags
and single element") disabled this optimization, which is enabled again
after this patch.

Fixes: 01167c393a12 ("evaluate: do not remove anonymous set with protocol flags and single element")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/evaluate.c | 60 +++++++++++++++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 20 deletions(-)

diff --git a/src/evaluate.c b/src/evaluate.c
index a7725f4e..ab3ec987 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1815,26 +1815,6 @@ static int expr_evaluate_set(struct eval_ctx *ctx, struct expr **expr)
 	if (ctx->set) {
 		if (ctx->set->flags & NFT_SET_CONCAT)
 			set->set_flags |= NFT_SET_CONCAT;
-	} else if (set->size == 1) {
-		i = list_first_entry(&set->expressions, struct expr, list);
-		if (i->etype == EXPR_SET_ELEM &&
-		    (!i->dtype->basetype ||
-		     i->dtype->basetype->type != TYPE_BITMASK ||
-		     i->dtype->type == TYPE_CT_STATE) &&
-		    list_empty(&i->stmt_list)) {
-
-			switch (i->key->etype) {
-			case EXPR_PREFIX:
-			case EXPR_RANGE:
-			case EXPR_VALUE:
-				*expr = i->key;
-				i->key = NULL;
-				expr_free(set);
-				return 0;
-			default:
-				break;
-			}
-		}
 	}
 
 	set->set_flags |= NFT_SET_CONSTANT;
@@ -2355,6 +2335,35 @@ static bool range_needs_swap(const struct expr *range)
 	return mpz_cmp(left->value, right->value) > 0;
 }
 
+static void optimize_singleton_set(struct expr *rel, struct expr **expr)
+{
+	struct expr *set = rel->right, *i;
+
+	i = list_first_entry(&set->expressions, struct expr, list);
+	if (i->etype == EXPR_SET_ELEM &&
+	    list_empty(&i->stmt_list)) {
+
+		switch (i->key->etype) {
+		case EXPR_PREFIX:
+		case EXPR_RANGE:
+		case EXPR_VALUE:
+			rel->right = *expr = i->key;
+			i->key = NULL;
+			expr_free(set);
+			break;
+		default:
+			break;
+		}
+	}
+
+	if (rel->op == OP_IMPLICIT &&
+	    rel->right->dtype->basetype &&
+	    rel->right->dtype->basetype->type == TYPE_BITMASK &&
+	    rel->right->dtype->type != TYPE_CT_STATE) {
+		rel->op = OP_EQ;
+	}
+}
+
 static int expr_evaluate_relational(struct eval_ctx *ctx, struct expr **expr)
 {
 	struct expr *rel = *expr, *left, *right;
@@ -2434,6 +2443,17 @@ static int expr_evaluate_relational(struct eval_ctx *ctx, struct expr **expr)
 		return expr_binary_error(ctx->msgs, right, left,
 					 "Cannot be used with right hand side constant value");
 
+	switch (rel->op) {
+	case OP_EQ:
+	case OP_IMPLICIT:
+	case OP_NEQ:
+		if (right->etype == EXPR_SET && right->size == 1)
+			optimize_singleton_set(rel, &right);
+		break;
+	default:
+		break;
+	}
+
 	switch (rel->op) {
 	case OP_EQ:
 	case OP_IMPLICIT:
-- 
2.33.0