netfilter: nf_tables: Fix for deleting base chains with payload

When deleting a base chain, iptables-nft simply submits the whole chain
to the kernel, including the NFTA_CHAIN_HOOK attribute. The new code
added by fixed commit then turned this into a chain update, destroying
the hook but not the chain itself. Detect the situation by checking if
the chain type is either netdev or inet/ingress.

Fixes: 7d937b10 ("netfilter: nf_tables: support for deleting devices in an existing netdev chain")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -2811,21 +2811,18 @@ static int nf_tables_newchain(struct sk_buff *skb, const struct nfnl_info *info,
 	return nf_tables_addchain(&ctx, family, genmask, policy, flags, extack);
 }
 
-static int nft_delchain_hook(struct nft_ctx *ctx, struct nft_chain *chain,
+static int nft_delchain_hook(struct nft_ctx *ctx,
+			     struct nft_base_chain *basechain,
 			     struct netlink_ext_ack *extack)
 {
+	const struct nft_chain *chain = &basechain->chain;
 	const struct nlattr * const *nla = ctx->nla;
 	struct nft_chain_hook chain_hook = {};
-	struct nft_base_chain *basechain;
 	struct nft_hook *this, *hook;
 	LIST_HEAD(chain_del_list);
 	struct nft_trans *trans;
 	int err;
 
-	if (!nft_is_base_chain(chain))
-		return -EOPNOTSUPP;
-
-	basechain = nft_base_chain(chain);
 	err = nft_chain_parse_hook(ctx->net, basechain, nla, &chain_hook,
 				   ctx->family, chain->flags, extack);
 	if (err < 0)
@@ -2910,7 +2907,12 @@ static int nf_tables_delchain(struct sk_buff *skb, const struct nfnl_info *info,
 		if (chain->flags & NFT_CHAIN_HW_OFFLOAD)
 			return -EOPNOTSUPP;
 
-		return nft_delchain_hook(&ctx, chain, extack);
+		if (nft_is_base_chain(chain)) {
+			struct nft_base_chain *basechain = nft_base_chain(chain);
+
+			if (nft_base_chain_netdev(table->family, basechain->ops.hooknum))
+				return nft_delchain_hook(&ctx, basechain, extack);
+		}
 	}
 
 	if (info->nlh->nlmsg_flags & NLM_F_NONREC &&