netfilter: nf_tables: validate catch-all set elements

jira LE-1907
cve CVE-2023-3390
Rebuild_History Non-Buildable kernel-5.14.0-284.30.1.el9_2
commit-author Pablo Neira Ayuso <[email protected]>
commit d46fc89

catch-all set element might jump/goto to chain that uses expressions
that require validation.

Fixes: aaa3104 ("netfilter: nftables: add catch-all set element support")
	Signed-off-by: Pablo Neira Ayuso <[email protected]>
(cherry picked from commit d46fc89)
	Signed-off-by: Jonathan Maple <[email protected]>

Author: PlaidCat

include/net/netfilter/nf_tables.h

@@ -1029,6 +1029,10 @@ struct nft_chain {
 };
 
 int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain);
+int nft_setelem_validate(const struct nft_ctx *ctx, struct nft_set *set,
+			 const struct nft_set_iter *iter,
+			 struct nft_set_elem *elem);
+int nft_set_catchall_validate(const struct nft_ctx *ctx, struct nft_set *set);
 
 enum nft_chain_types {
 	NFT_CHAIN_T_DEFAULT = 0,

net/netfilter/nf_tables_api.c

@@ -3294,6 +3294,64 @@ static int nft_table_validate(struct net *net, const struct nft_table *table)
 	return 0;
 }
 
+int nft_setelem_validate(const struct nft_ctx *ctx, struct nft_set *set,
+			 const struct nft_set_iter *iter,
+			 struct nft_set_elem *elem)
+{
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
+	struct nft_ctx *pctx = (struct nft_ctx *)ctx;
+	const struct nft_data *data;
+	int err;
+
+	if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
+	    *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
+		return 0;
+
+	data = nft_set_ext_data(ext);
+	switch (data->verdict.code) {
+	case NFT_JUMP:
+	case NFT_GOTO:
+		pctx->level++;
+		err = nft_chain_validate(ctx, data->verdict.chain);
+		if (err < 0)
+			return err;
+		pctx->level--;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+struct nft_set_elem_catchall {
+	struct list_head	list;
+	struct rcu_head		rcu;
+	void			*elem;
+};
+
+int nft_set_catchall_validate(const struct nft_ctx *ctx, struct nft_set *set)
+{
+	u8 genmask = nft_genmask_next(ctx->net);
+	struct nft_set_elem_catchall *catchall;
+	struct nft_set_elem elem;
+	struct nft_set_ext *ext;
+	int ret = 0;
+
+	list_for_each_entry_rcu(catchall, &set->catchall_list, list) {
+		ext = nft_set_elem_ext(set, catchall->elem);
+		if (!nft_set_elem_active(ext, genmask))
+			continue;
+
+		elem.priv = catchall->elem;
+		ret = nft_setelem_validate(ctx, set, NULL, &elem);
+		if (ret < 0)
+			return ret;
+	}
+
+	return ret;
+}
+
 static struct nft_rule *nft_rule_lookup_byid(const struct net *net,
 					     const struct nft_chain *chain,
 					     const struct nlattr *nla);
@@ -4598,12 +4656,6 @@ static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info,
 	return err;
 }
 
-struct nft_set_elem_catchall {
-	struct list_head	list;
-	struct rcu_head		rcu;
-	void			*elem;
-};
-
 static void nft_set_catchall_destroy(const struct nft_ctx *ctx,
 				     struct nft_set *set)
 {

net/netfilter/nft_lookup.c

@@ -198,37 +198,6 @@ static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 	return -1;
 }
 
-static int nft_lookup_validate_setelem(const struct nft_ctx *ctx,
-				       struct nft_set *set,
-				       const struct nft_set_iter *iter,
-				       struct nft_set_elem *elem)
-{
-	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
-	struct nft_ctx *pctx = (struct nft_ctx *)ctx;
-	const struct nft_data *data;
-	int err;
-
-	if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
-	    *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
-		return 0;
-
-	data = nft_set_ext_data(ext);
-	switch (data->verdict.code) {
-	case NFT_JUMP:
-	case NFT_GOTO:
-		pctx->level++;
-		err = nft_chain_validate(ctx, data->verdict.chain);
-		if (err < 0)
-			return err;
-		pctx->level--;
-		break;
-	default:
-		break;
-	}
-
-	return 0;
-}
-
 static int nft_lookup_validate(const struct nft_ctx *ctx,
 			       const struct nft_expr *expr,
 			       const struct nft_data **d)
@@ -244,9 +213,12 @@ static int nft_lookup_validate(const struct nft_ctx *ctx,
 	iter.skip	= 0;
 	iter.count	= 0;
 	iter.err	= 0;
-	iter.fn		= nft_lookup_validate_setelem;
+	iter.fn		= nft_setelem_validate;
 
 	priv->set->ops->walk(ctx, priv->set, &iter);
+	if (!iter.err)
+		iter.err = nft_set_catchall_validate(ctx, priv->set);
+
 	if (iter.err < 0)
 		return iter.err;