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

Daniel Borkmann
2024-06-28T21:51:34Z

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!