[PATCH net-next 2/2] netfilter: nft_payload: packet mangling offload support

[Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>]

This patch allows for mangling packet fields using hardware offload
infrastructure.

Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
 net/netfilter/nft_payload.c | 82 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
index 22a80eb60222..d758c8900835 100644
--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -562,12 +562,94 @@ static int nft_payload_set_dump(struct sk_buff *skb, const struct nft_expr *expr
 	return -1;
 }
 
+static int nft_payload_offload_set_nh(struct nft_offload_ctx *ctx,
+				      struct nft_flow_rule *flow,
+				      const struct nft_payload_set *priv)
+{
+	int type = FLOW_ACT_MANGLE_UNSPEC;
+
+	switch (ctx->dep.l3num) {
+	case htons(ETH_P_IP):
+		type = FLOW_ACT_MANGLE_HDR_TYPE_IP4;
+		break;
+	case htons(ETH_P_IPV6):
+		type = FLOW_ACT_MANGLE_HDR_TYPE_IP6;
+		break;
+	}
+
+	return type;
+}
+
+static int nft_payload_offload_set_th(struct nft_offload_ctx *ctx,
+				      struct nft_flow_rule *flow,
+				      const struct nft_payload_set *priv)
+{
+	int type = FLOW_ACT_MANGLE_UNSPEC;
+
+	switch (ctx->dep.protonum) {
+	case IPPROTO_TCP:
+		type = FLOW_ACT_MANGLE_HDR_TYPE_TCP;
+		break;
+	case IPPROTO_UDP:
+		type = FLOW_ACT_MANGLE_HDR_TYPE_UDP;
+		break;
+	}
+
+	return type;
+}
+
+static inline u32 nft_payload_mask(int len)
+{
+	return (1 << (len * BITS_PER_BYTE)) - 1;
+}
+
+static int nft_payload_set_offload(struct nft_offload_ctx *ctx,
+				   struct nft_flow_rule *flow,
+				   const struct nft_expr *expr)
+{
+	const struct nft_payload_set *priv = nft_expr_priv(expr);
+	struct nft_offload_reg *sreg = &ctx->regs[priv->sreg];
+	int type = FLOW_ACT_MANGLE_UNSPEC;
+	struct flow_action_entry *entry;
+	u32 words;
+	int i;
+
+	switch (priv->base) {
+	case NFT_PAYLOAD_LL_HEADER:
+		type = FLOW_ACT_MANGLE_HDR_TYPE_ETH;
+		break;
+	case NFT_PAYLOAD_NETWORK_HEADER:
+		type = nft_payload_offload_set_nh(ctx, flow, priv);
+		break;
+	case NFT_PAYLOAD_TRANSPORT_HEADER:
+		type = nft_payload_offload_set_th(ctx, flow, priv);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+	words = round_up(priv->len, sizeof(u32)) / sizeof(u32);
+
+	entry = &flow->rule->action.entries[ctx->num_actions++];
+	entry->mangle.htype	= type;
+	entry->mangle.offset	= priv->offset;
+	for (i = 0; i < words; i++) {
+		entry->mangle.data[i].mask =
+			~htonl(nft_payload_mask(priv->len));
+		entry->mangle.data[i].val = sreg->data.data[i];
+	}
+	entry->mangle.words	= words;
+
+	return type != FLOW_ACT_MANGLE_UNSPEC ? 0 : -EOPNOTSUPP;
+}
+
 static const struct nft_expr_ops nft_payload_set_ops = {
 	.type		= &nft_payload_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
 	.eval		= nft_payload_set_eval,
 	.init		= nft_payload_set_init,
 	.dump		= nft_payload_set_dump,
+	.offload	= nft_payload_set_offload,
 };
 
 static const struct nft_expr_ops *
-- 
2.11.0