[20/21] netfilter: nft_dynset: dynamic stateful expression instantiation

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 4894238..5fa1cd0 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -567,6 +567,7 @@  enum nft_dynset_ops {
  * @NFTA_DYNSET_SREG_KEY: source register of the key (NLA_U32)
  * @NFTA_DYNSET_SREG_DATA: source register of the data (NLA_U32)
  * @NFTA_DYNSET_TIMEOUT: timeout value for the new element (NLA_U64)
+ * @NFTA_DYNSET_EXPR: expression (NLA_NESTED: nft_expr_attributes)
  */
 enum nft_dynset_attributes {
 	NFTA_DYNSET_UNSPEC,
@@ -576,6 +577,7 @@  enum nft_dynset_attributes {
 	NFTA_DYNSET_SREG_KEY,
 	NFTA_DYNSET_SREG_DATA,
 	NFTA_DYNSET_TIMEOUT,
+	NFTA_DYNSET_EXPR,
 	__NFTA_DYNSET_MAX,
 };
 #define NFTA_DYNSET_MAX		(__NFTA_DYNSET_MAX - 1)
diff --git a/net/netfilter/nft_dynset.c b/net/netfilter/nft_dynset.c
index 03699d5..513a8ef 100644
--- a/net/netfilter/nft_dynset.c
+++ b/net/netfilter/nft_dynset.c
@@ -23,6 +23,7 @@  struct nft_dynset {
 	enum nft_registers		sreg_key:8;
 	enum nft_registers		sreg_data:8;
 	u64				timeout;
+	struct nft_expr			*expr;
 	struct nft_set_binding		binding;
 };
 
@@ -30,6 +31,7 @@  static void *nft_dynset_new(struct nft_set *set, const struct nft_expr *expr,
 			    struct nft_regs *regs)
 {
 	const struct nft_dynset *priv = nft_expr_priv(expr);
+	struct nft_set_ext *ext;
 	u64 timeout;
 	void *elem;
 
@@ -44,7 +46,13 @@  static void *nft_dynset_new(struct nft_set *set, const struct nft_expr *expr,
 	if (elem == NULL) {
 		if (set->size)
 			atomic_dec(&set->nelems);
+		return NULL;
 	}
+
+	ext = nft_set_elem_ext(set, elem);
+	if (priv->expr != NULL)
+		nft_expr_clone(nft_set_ext_expr(ext), priv->expr);
+
 	return elem;
 }
 
@@ -55,18 +63,27 @@  static void nft_dynset_eval(const struct nft_expr *expr,
 	const struct nft_dynset *priv = nft_expr_priv(expr);
 	struct nft_set *set = priv->set;
 	const struct nft_set_ext *ext;
+	const struct nft_expr *sexpr;
 	u64 timeout;
 
 	if (set->ops->update(set, &regs->data[priv->sreg_key], nft_dynset_new,
 			     expr, regs, &ext)) {
+		sexpr = NULL;
+		if (nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
+			sexpr = nft_set_ext_expr(ext);
+
 		if (priv->op == NFT_DYNSET_OP_UPDATE &&
 		    nft_set_ext_exists(ext, NFT_SET_EXT_EXPIRATION)) {
 			timeout = priv->timeout ? : set->timeout;
 			*nft_set_ext_expiration(ext) = jiffies + timeout;
-			return;
-		}
-	}
+		} else if (sexpr == NULL)
+			goto out;
 
+		if (sexpr != NULL)
+			sexpr->ops->eval(sexpr, regs, pkt);
+		return;
+	}
+out:
 	regs->verdict.code = NFT_BREAK;
 }
 
@@ -77,6 +94,7 @@  static const struct nla_policy nft_dynset_policy[NFTA_DYNSET_MAX + 1] = {
 	[NFTA_DYNSET_SREG_KEY]	= { .type = NLA_U32 },
 	[NFTA_DYNSET_SREG_DATA]	= { .type = NLA_U32 },
 	[NFTA_DYNSET_TIMEOUT]	= { .type = NLA_U64 },
+	[NFTA_DYNSET_EXPR]	= { .type = NLA_NESTED },
 };
 
 static int nft_dynset_init(const struct nft_ctx *ctx,
@@ -142,10 +160,29 @@  static int nft_dynset_init(const struct nft_ctx *ctx,
 	} else if (set->flags & NFT_SET_MAP)
 		return -EINVAL;
 
+	if (tb[NFTA_DYNSET_EXPR] != NULL) {
+		if (!(set->flags & NFT_SET_EVAL))
+			return -EINVAL;
+		if (!(set->flags & NFT_SET_ANONYMOUS))
+			return -EOPNOTSUPP;
+
+		priv->expr = nft_expr_init(ctx, tb[NFTA_DYNSET_EXPR]);
+		if (IS_ERR(priv->expr))
+			return PTR_ERR(priv->expr);
+
+		err = -EOPNOTSUPP;
+		if (!(priv->expr->ops->type->flags & NFT_EXPR_STATEFUL))
+			goto err1;
+	} else if (set->flags & NFT_SET_EVAL)
+		return -EINVAL;
+
 	nft_set_ext_prepare(&priv->tmpl);
 	nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_KEY, set->klen);
 	if (set->flags & NFT_SET_MAP)
 		nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_DATA, set->dlen);
+	if (priv->expr != NULL)
+		nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_EXPR,
+				       priv->expr->ops->size);
 	if (set->flags & NFT_SET_TIMEOUT) {
 		if (timeout || set->timeout)
 			nft_set_ext_add(&priv->tmpl, NFT_SET_EXT_EXPIRATION);
@@ -155,10 +192,15 @@  static int nft_dynset_init(const struct nft_ctx *ctx,
 
 	err = nf_tables_bind_set(ctx, set, &priv->binding);
 	if (err < 0)
-		return err;
+		goto err1;
 
 	priv->set = set;
 	return 0;
+
+err1:
+	if (priv->expr != NULL)
+		nft_expr_destroy(ctx, priv->expr);
+	return err;
 }
 
 static void nft_dynset_destroy(const struct nft_ctx *ctx,
@@ -167,6 +209,8 @@  static void nft_dynset_destroy(const struct nft_ctx *ctx,
 	struct nft_dynset *priv = nft_expr_priv(expr);
 
 	nf_tables_unbind_set(ctx, priv->set, &priv->binding);
+	if (priv->expr != NULL)
+		nft_expr_destroy(ctx, priv->expr);
 }
 
 static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
@@ -184,6 +228,8 @@  static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
 		goto nla_put_failure;
 	if (nla_put_be64(skb, NFTA_DYNSET_TIMEOUT, cpu_to_be64(priv->timeout)))
 		goto nla_put_failure;
+	if (priv->expr && nft_expr_dump(skb, NFTA_DYNSET_EXPR, priv->expr))
+		goto nla_put_failure;
 	return 0;
 
 nla_put_failure: