netfilter: nf_tables: add nft_chain_add()

jira VUlN-429
subsystem-sync netfilter:nf_tables 4.18.0-511
commit-author Pablo Neira Ayuso <pablo@netfilter.org>
commit 04b7db4
upstream-diff same as most in this series, patch looks identical but has
offset fuzz.

This patch adds a helper function to add the chain to the hashtable and
the chain list.

	Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit 04b7db4)
	Signed-off-by: Greg Rose <g.v.rose@ciq.com>

Author: gvrose8192

net/netfilter/nf_tables_api.c

@@ -1986,6 +1986,20 @@ static int nft_basechain_init(struct nft_base_chain *basechain, u8 family,
 	return 0;
 }
 
+static int nft_chain_add(struct nft_table *table, struct nft_chain *chain)
+{
+	int err;
+
+	err = rhltable_insert_key(&table->chains_ht, chain->name,
+				  &chain->rhlhead, nft_chain_ht_params);
+	if (err)
+		return err;
+
+	list_add_tail_rcu(&chain->list, &table->chains);
+
+	return 0;
+}
+
 static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 			      u8 policy, u32 flags)
 {
@@ -2065,26 +2079,23 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 	if (err < 0)
 		goto err1;
 
-	err = rhltable_insert_key(&table->chains_ht, chain->name,
-				  &chain->rhlhead, nft_chain_ht_params);
-	if (err)
-		goto err2;
-
 	trans = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN);
 	if (IS_ERR(trans)) {
 		err = PTR_ERR(trans);
-		rhltable_remove(&table->chains_ht, &chain->rhlhead,
-				nft_chain_ht_params);
 		goto err2;
 	}
 
 	nft_trans_chain_policy(trans) = NFT_CHAIN_POLICY_UNSET;
 	if (nft_is_base_chain(chain))
 		nft_trans_chain_policy(trans) = policy;
 
+	err = nft_chain_add(table, chain);
+	if (err < 0) {
+		nft_trans_destroy(trans);
+		goto err2;
+	}
 
 	table->use++;
-	list_add_tail_rcu(&chain->list, &table->chains);
 
 	return 0;
 err2: