netfilter: nf_tables: avoid usage of embedded nft_ctx

nft_ctx is stored in nft_trans object, but nft_ctx is large
(48 bytes on 64-bit platforms), it should not be embedded in
the transaction structures.

Reduce its usage so we can remove it eventually.

This replaces trans->ctx.chain with the chain pointer
already available in nft_trans_chain structure.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -9682,10 +9682,10 @@ static void nf_tables_commit_chain_prepare_cancel(struct net *net)
 	struct nft_trans *trans, *next;
 
 	list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
-		struct nft_chain *chain = trans->ctx.chain;
-
 		if (trans->msg_type == NFT_MSG_NEWRULE ||
 		    trans->msg_type == NFT_MSG_DELRULE) {
+			struct nft_chain *chain = trans->ctx.chain;
+
 			kvfree(chain->blob_next);
 			chain->blob_next = NULL;
 		}
@@ -10318,7 +10318,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 				/* trans destroyed after rcu grace period */
 			} else {
 				nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
-				nft_clear(net, trans->ctx.chain);
+				nft_clear(net, nft_trans_chain(trans));
 				nf_tables_chain_notify(&trans->ctx, NFT_MSG_NEWCHAIN, NULL);
 				nft_trans_destroy(trans);
 			}
@@ -10334,11 +10334,11 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 								    true);
 				}
 			} else {
-				nft_chain_del(trans->ctx.chain);
+				nft_chain_del(nft_trans_chain(trans));
 				nf_tables_chain_notify(&trans->ctx, NFT_MSG_DELCHAIN,
 						       NULL);
 				nf_tables_unregister_hook(trans->ctx.net, table,
-							  trans->ctx.chain);
+							  nft_trans_chain(trans));
 			}
 			break;
 		case NFT_MSG_NEWRULE:

net/netfilter/nf_tables_offload.c

@@ -518,18 +518,18 @@ static void nft_flow_rule_offload_abort(struct net *net,
 
 		switch (trans->msg_type) {
 		case NFT_MSG_NEWCHAIN:
-			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD) ||
+			if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD) ||
 			    nft_trans_chain_update(trans))
 				continue;
 
-			err = nft_flow_offload_chain(trans->ctx.chain, NULL,
+			err = nft_flow_offload_chain(nft_trans_chain(trans), NULL,
 						     FLOW_BLOCK_UNBIND);
 			break;
 		case NFT_MSG_DELCHAIN:
-			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
+			if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
 				continue;
 
-			err = nft_flow_offload_chain(trans->ctx.chain, NULL,
+			err = nft_flow_offload_chain(nft_trans_chain(trans), NULL,
 						     FLOW_BLOCK_BIND);
 			break;
 		case NFT_MSG_NEWRULE:
@@ -569,20 +569,20 @@ int nft_flow_rule_offload_commit(struct net *net)
 
 		switch (trans->msg_type) {
 		case NFT_MSG_NEWCHAIN:
-			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD) ||
+			if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD) ||
 			    nft_trans_chain_update(trans))
 				continue;
 
 			policy = nft_trans_chain_policy(trans);
-			err = nft_flow_offload_chain(trans->ctx.chain, &policy,
+			err = nft_flow_offload_chain(nft_trans_chain(trans), &policy,
 						     FLOW_BLOCK_BIND);
 			break;
 		case NFT_MSG_DELCHAIN:
-			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
+			if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
 				continue;
 
 			policy = nft_trans_chain_policy(trans);
-			err = nft_flow_offload_chain(trans->ctx.chain, &policy,
+			err = nft_flow_offload_chain(nft_trans_chain(trans), &policy,
 						     FLOW_BLOCK_UNBIND);
 			break;
 		case NFT_MSG_NEWRULE: