1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2020 Cloudflare Ltd https://cloudflare.com */
 3
 4#include <linux/skmsg.h>
 5#include <net/sock.h>
 6#include <net/udp.h>
 7
 8enum {
 9	UDP_BPF_IPV4,
10	UDP_BPF_IPV6,
11	UDP_BPF_NUM_PROTS,
12};
13
14static struct proto *udpv6_prot_saved __read_mostly;
15static DEFINE_SPINLOCK(udpv6_prot_lock);
16static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS];
17
18static void udp_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
19{
20	*prot        = *base;
21	prot->unhash = sock_map_unhash;
22	prot->close  = sock_map_close;
23}
24
25static void udp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
26{
27	if (sk->sk_family == AF_INET6 &&
28	    unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) {
29		spin_lock_bh(&udpv6_prot_lock);
30		if (likely(ops != udpv6_prot_saved)) {
31			udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV6], ops);
32			smp_store_release(&udpv6_prot_saved, ops);
33		}
34		spin_unlock_bh(&udpv6_prot_lock);
35	}
36}
37
38static int __init udp_bpf_v4_build_proto(void)
39{
40	udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot);
41	return 0;
42}
43core_initcall(udp_bpf_v4_build_proto);
44
45struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
46{
47	int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
48
49	if (!psock->sk_proto)
50		udp_bpf_check_v6_needs_rebuild(sk, READ_ONCE(sk->sk_prot));
51
52	return &udp_bpf_prots[family];
53}