[PATCH nf-next 3/3] netfilter: nf_tables_offload: undo updates if transaction fails

[Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>]

The nft_flow_rule_offload_commit() might fail after several successful
commands leaving the hardware filtering policy in inconsistent state.
This patch adds nft_flow_rule_offload_abort() which undoes the updates
that have been already processed if one command of this transaction
fails. Hence, the hardware ruleset is left as is it was before the
update.

Thee deletion path needs to create the flow_rule object too, in case
that an existing rule needs to be re-added from the abort path.

Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
 net/netfilter/nf_tables_api.c     | 11 ++++++++
 net/netfilter/nf_tables_offload.c | 54 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 1dcab99cb947..575791a36d59 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -361,6 +361,7 @@ static struct nft_trans *nft_trans_rule_add(struct nft_ctx *ctx, int msg_type,
 
 static int nft_delrule(struct nft_ctx *ctx, struct nft_rule *rule)
 {
+	struct nft_flow_rule *flow;
 	struct nft_trans *trans;
 	int err;
 
@@ -368,6 +369,16 @@ static int nft_delrule(struct nft_ctx *ctx, struct nft_rule *rule)
 	if (trans == NULL)
 		return -ENOMEM;
 
+	if (ctx->chain->flags & NFT_CHAIN_HW_OFFLOAD) {
+		flow = nft_flow_rule_create(ctx->net, rule);
+		if (IS_ERR(flow)) {
+			nft_trans_destroy(trans);
+			return PTR_ERR(flow);
+		}
+
+		nft_trans_flow_rule(trans) = flow;
+	}
+
 	err = nf_tables_delrule_deactivate(ctx, rule);
 	if (err < 0) {
 		nft_trans_destroy(trans);
diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index 6d5f3cd7f1b7..68f17a6921d8 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -389,6 +389,55 @@ static int nft_flow_offload_chain(struct nft_chain *chain, u8 *ppolicy,
 	return nft_flow_block_chain(basechain, NULL, cmd);
 }
 
+static void nft_flow_rule_offload_abort(struct net *net,
+					struct nft_trans *trans)
+{
+	int err = 0;
+
+	list_for_each_entry_continue_reverse(trans, &net->nft.commit_list, list) {
+		if (trans->ctx.family != NFPROTO_NETDEV)
+			continue;
+
+		switch (trans->msg_type) {
+		case NFT_MSG_NEWCHAIN:
+			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD) ||
+			    nft_trans_chain_update(trans))
+				continue;
+
+			err = nft_flow_offload_chain(trans->ctx.chain, NULL,
+						     FLOW_BLOCK_UNBIND);
+			break;
+		case NFT_MSG_DELCHAIN:
+			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
+				continue;
+
+			err = nft_flow_offload_chain(trans->ctx.chain, NULL,
+						     FLOW_BLOCK_BIND);
+			break;
+		case NFT_MSG_NEWRULE:
+			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
+				continue;
+
+			err = nft_flow_offload_rule(trans->ctx.chain,
+						    nft_trans_rule(trans),
+						    NULL, FLOW_CLS_DESTROY);
+			break;
+		case NFT_MSG_DELRULE:
+			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
+				continue;
+
+			err = nft_flow_offload_rule(trans->ctx.chain,
+						    nft_trans_rule(trans),
+						    nft_trans_flow_rule(trans),
+						    FLOW_CLS_REPLACE);
+			break;
+		}
+
+		if (WARN_ON_ONCE(err))
+			break;
+	}
+}
+
 int nft_flow_rule_offload_commit(struct net *net)
 {
 	struct nft_trans *trans;
@@ -441,8 +490,10 @@ int nft_flow_rule_offload_commit(struct net *net)
 			break;
 		}
 
-		if (err)
+		if (err) {
+			nft_flow_rule_offload_abort(net, trans);
 			break;
+		}
 	}
 
 	list_for_each_entry(trans, &net->nft.commit_list, list) {
@@ -451,6 +502,7 @@ int nft_flow_rule_offload_commit(struct net *net)
 
 		switch (trans->msg_type) {
 		case NFT_MSG_NEWRULE:
+		case NFT_MSG_DELRULE:
 			if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
 				continue;
 
-- 
2.11.0