Subject: [PATCH v4 net-next 13/13] netfilter: nft_flow_offload: Add bridgeflow to nft_flow_offload_eval()

From: Eric Woudstra <[email-masked]>
Date: Tue, 7 Jan 2025 10:05:30 +0100

Edit nft_flow_offload_eval() to make it possible to handle a flowtable of
the nft bridge family.

Use nft_flow_offload_bridge_init() to fill the flow tuples. It uses
nft_dev_fill_bridge_path() in each direction.

Signed-off-by: Eric Woudstra <[email-masked]>
---
 net/netfilter/nft_flow_offload.c | 144 +++++++++++++++++++++++++++++--
 1 file changed, 139 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index ed0e9b499971..b17a3ef79852 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -196,6 +196,131 @@ static bool nft_flowtable_find_dev(const struct net_device *dev,
 	return found;
 }
 
+static int nft_dev_fill_bridge_path(struct flow_offload *flow,
+				    struct nft_flowtable *ft,
+				    const struct nft_pktinfo *pkt,
+				    enum ip_conntrack_dir dir,
+				    const struct net_device *src_dev,
+				    const struct net_device *dst_dev,
+				    unsigned char *src_ha,
+				    unsigned char *dst_ha)
+{
+	struct flow_offload_tuple_rhash *th = flow->tuplehash;
+	struct net_device_path_stack stack;
+	struct net_device_path_ctx ctx = {};
+	struct nft_forward_info info = {};
+	int i, j = 0;
+
+	for (i = th[dir].tuple.encap_num - 1; i >= 0 ; i--) {
+		if (info.num_encaps >= NF_FLOW_TABLE_ENCAP_MAX)
+			return -1;
+
+		if (th[dir].tuple.in_vlan_ingress & BIT(i))
+			continue;
+
+		info.encap[info.num_encaps].id = th[dir].tuple.encap[i].id;
+		info.encap[info.num_encaps].proto = th[dir].tuple.encap[i].proto;
+		info.num_encaps++;
+
+		if (th[dir].tuple.encap[i].proto == htons(ETH_P_PPP_SES))
+			continue;
+
+		if (ctx.num_vlans >= NET_DEVICE_PATH_VLAN_MAX)
+			return -1;
+		ctx.vlan[ctx.num_vlans].id = th[dir].tuple.encap[i].id;
+		ctx.vlan[ctx.num_vlans].proto = th[dir].tuple.encap[i].proto;
+		ctx.num_vlans++;
+	}
+	ctx.dev = src_dev;
+	ether_addr_copy(ctx.daddr, dst_ha);
+
+	if (dev_fill_bridge_path(&ctx, &stack) < 0)
+		return -1;
+
+	nft_dev_path_info(&stack, &info, dst_ha, &ft->data);
+
+	if (!info.indev || info.indev != dst_dev)
+		return -1;
+
+	th[!dir].tuple.iifidx = info.indev->ifindex;
+	for (i = info.num_encaps - 1; i >= 0; i--) {
+		th[!dir].tuple.encap[j].id = info.encap[i].id;
+		th[!dir].tuple.encap[j].proto = info.encap[i].proto;
+		if (info.ingress_vlans & BIT(i))
+			th[!dir].tuple.in_vlan_ingress |= BIT(j);
+		j++;
+	}
+	th[!dir].tuple.encap_num = info.num_encaps;
+
+	th[dir].tuple.mtu = dst_dev->mtu;
+	ether_addr_copy(th[dir].tuple.out.h_source, src_ha);
+	ether_addr_copy(th[dir].tuple.out.h_dest, dst_ha);
+	th[dir].tuple.out.ifidx = info.outdev->ifindex;
+	th[dir].tuple.out.hw_ifidx = info.hw_outdev->ifindex;
+	th[dir].tuple.xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
+
+	return 0;
+}
+
+static int nft_flow_offload_bridge_init(struct flow_offload *flow,
+					const struct nft_pktinfo *pkt,
+					enum ip_conntrack_dir dir,
+					struct nft_flowtable *ft)
+{
+	struct ethhdr *eth = eth_hdr(pkt->skb);
+	struct flow_offload_tuple *tuple;
+	const struct net_device *out_dev;
+	const struct net_device *in_dev;
+	struct pppoe_hdr *phdr;
+	struct vlan_hdr *vhdr;
+	int err, i = 0;
+
+	in_dev = nft_in(pkt);
+	if (!in_dev || !nft_flowtable_find_dev(in_dev, ft))
+		return -1;
+
+	out_dev = nft_out(pkt);
+	if (!out_dev || !nft_flowtable_find_dev(out_dev, ft))
+		return -1;
+
+	tuple =  &flow->tuplehash[!dir].tuple;
+
+	if (skb_vlan_tag_present(pkt->skb)) {
+		tuple->encap[i].id = skb_vlan_tag_get(pkt->skb);
+		tuple->encap[i].proto = pkt->skb->vlan_proto;
+		i++;
+	}
+	switch (pkt->skb->protocol) {
+	case htons(ETH_P_8021Q):
+		vhdr = (struct vlan_hdr *)skb_network_header(pkt->skb);
+		tuple->encap[i].id = ntohs(vhdr->h_vlan_TCI);
+		tuple->encap[i].proto = pkt->skb->protocol;
+		i++;
+		break;
+	case htons(ETH_P_PPP_SES):
+		phdr = (struct pppoe_hdr *)skb_network_header(pkt->skb);
+		tuple->encap[i].id = ntohs(phdr->sid);
+		tuple->encap[i].proto = pkt->skb->protocol;
+		i++;
+		break;
+	}
+	tuple->encap_num = i;
+
+	err = nft_dev_fill_bridge_path(flow, ft, pkt, !dir, out_dev, in_dev,
+				       eth->h_dest, eth->h_source);
+	if (err < 0)
+		return err;
+
+	memset(tuple->encap, 0, sizeof(tuple->encap));
+
+	err = nft_dev_fill_bridge_path(flow, ft, pkt, dir, in_dev, out_dev,
+				       eth->h_source, eth->h_dest);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
 static void nft_dev_forward_path(struct nf_flow_route *route,
 				 const struct nf_conn *ct,
 				 enum ip_conntrack_dir dir,
@@ -306,6 +431,7 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
 {
 	struct nft_flow_offload *priv = nft_expr_priv(expr);
 	struct nf_flowtable *flowtable = &priv->flowtable->data;
+	bool routing = (flowtable->type->family != NFPROTO_BRIDGE);
 	struct tcphdr _tcph, *tcph = NULL;
 	struct nf_flow_route route = {};
 	enum ip_conntrack_info ctinfo;
@@ -359,14 +485,20 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
 		goto out;
 
 	dir = CTINFO2DIR(ctinfo);
-	if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
-		goto err_flow_route;
+	if (routing) {
+		if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
+			goto err_flow_route;
+	}
 
 	flow = flow_offload_alloc(ct);
 	if (!flow)
 		goto err_flow_alloc;
 
-	flow_offload_route_init(flow, &route);
+	if (routing)
+		flow_offload_route_init(flow, &route);
+	else
+		if (nft_flow_offload_bridge_init(flow, pkt, dir, priv->flowtable) < 0)
+			goto err_flow_route;
 
 	if (tcph) {
 		ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
@@ -419,8 +551,10 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
 err_flow_add:
 	flow_offload_free(flow);
 err_flow_alloc:
-	dst_release(route.tuple[dir].dst);
-	dst_release(route.tuple[!dir].dst);
+	if (routing) {
+		dst_release(route.tuple[dir].dst);
+		dst_release(route.tuple[!dir].dst);
+	}
 err_flow_route:
 	clear_bit(IPS_OFFLOAD_BIT, &ct->status);
 out:
-- 
2.47.1