Re: [PATCH v5 bpf-next 2/3] netfilter: add bpf_xdp_flow_lookup kfunc

On 6/14/24 5:40 PM, Lorenzo Bianconi wrote:
[...]

+enum {
+	NF_BPF_FLOWTABLE_OPTS_SZ = 4,
+};
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		  "Global functions as their definitions will be in nf_flow_table BTF");

nit: __bpf_kfunc_start_defs();

+static struct flow_offload_tuple_rhash *
+bpf_xdp_flow_tuple_lookup(struct net_device *dev,
+			  struct flow_offload_tuple *tuple, __be16 proto)
+{
+	struct flow_offload_tuple_rhash *tuplehash;
+	struct nf_flowtable *nf_flow_table;
+	struct flow_offload *nf_flow;
+
+	nf_flow_table = nf_flowtable_by_dev(dev);
+	if (!nf_flow_table)
+		return ERR_PTR(-ENOENT);
+
+	tuplehash = flow_offload_lookup(nf_flow_table, tuple);
+	if (!tuplehash)
+		return ERR_PTR(-ENOENT);
+
+	nf_flow = container_of(tuplehash, struct flow_offload,
+			       tuplehash[tuplehash->tuple.dir]);
+	flow_offload_refresh(nf_flow_table, nf_flow, false);
+
+	return tuplehash;
+}
+
+__bpf_kfunc struct flow_offload_tuple_rhash *
+bpf_xdp_flow_lookup(struct xdp_md *ctx, struct bpf_fib_lookup *fib_tuple,
+		    struct bpf_flowtable_opts *opts, u32 opts_len)
+{
+	struct xdp_buff *xdp = (struct xdp_buff *)ctx;
+	struct flow_offload_tuple tuple = {
+		.iifidx = fib_tuple->ifindex,
+		.l3proto = fib_tuple->family,
+		.l4proto = fib_tuple->l4_protocol,
+		.src_port = fib_tuple->sport,
+		.dst_port = fib_tuple->dport,
+	};
+	struct flow_offload_tuple_rhash *tuplehash;
+	__be16 proto;
+
+	if (opts_len != NF_BPF_FLOWTABLE_OPTS_SZ) {
+		opts->error = -EINVAL;
+		return NULL;
+	}
+
+	switch (fib_tuple->family) {
+	case AF_INET:
+		tuple.src_v4.s_addr = fib_tuple->ipv4_src;
+		tuple.dst_v4.s_addr = fib_tuple->ipv4_dst;
+		proto = htons(ETH_P_IP);
+		break;
+	case AF_INET6:
+		tuple.src_v6 = *(struct in6_addr *)&fib_tuple->ipv6_src;
+		tuple.dst_v6 = *(struct in6_addr *)&fib_tuple->ipv6_dst;
+		proto = htons(ETH_P_IPV6);
+		break;
+	default:
+		opts->error = -EAFNOSUPPORT;
+		return NULL;
+	}
+
+	tuplehash = bpf_xdp_flow_tuple_lookup(xdp->rxq->dev, &tuple, proto);
+	if (IS_ERR(tuplehash)) {
+		opts->error = PTR_ERR(tuplehash);
+		return NULL;
+	}
+
+	return tuplehash;
+}
+
+__diag_pop()

__bpf_kfunc_end_defs();

Otherwise LGTM!