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

From: Lorenzo Bianconi <[email-masked]>
Date: Sat, 29 Jun 2024 21:57:53 +0200

> 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();

ack, I will fix it in v6.

> 
> > +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();

ack, I will fix it in v6.

Regards,
Lorenzo

> Otherwise LGTM!