[PATCH net 02/13] netfilter: nf_tables: validate .maxattr at expression registration

From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org,
	pabeni@redhat.com, edumazet@google.com, fw@strlen.de
Subject: [PATCH net 02/13] netfilter: nf_tables: validate .maxattr at expression registration
Date: Thu, 18 Jan 2024 17:17:15 +0100	[thread overview]
Message-ID: <20240118161726.14838-3-pablo@netfilter.org> (raw)
In-Reply-To: <20240118161726.14838-1-pablo@netfilter.org>

struct nft_expr_info allows to store up to NFT_EXPR_MAXATTR (16)
attributes when parsing netlink attributes.

Rise a warning in case there is ever a nft expression whose .maxattr
goes beyond this number of expressions, in such case, struct nft_expr_info
needs to be updated.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a90a364f5be5..2548d7d56408 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2977,6 +2977,9 @@ static int nf_tables_delchain(struct sk_buff *skb, const struct nfnl_info *info,
  */
 int nft_register_expr(struct nft_expr_type *type)
 {
+	if (WARN_ON_ONCE(type->maxattr > NFT_EXPR_MAXATTR))
+		return -ENOMEM;
+
 	nfnl_lock(NFNL_SUBSYS_NFTABLES);
 	if (type->family == NFPROTO_UNSPEC)
 		list_add_tail_rcu(&type->list, &nf_tables_expressions);
-- 
2.30.2

