net/ipv4/udp_bpf.c

   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
   8 enum {
   9         UDP_BPF_IPV4,
  10         UDP_BPF_IPV6,
  11         UDP_BPF_NUM_PROTS,
  12 };
  13
  14 static struct proto *udpv6_prot_saved __read_mostly;
  15 static DEFINE_SPINLOCK(udpv6_prot_lock);
  16 static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS];
  17
  18 static 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
  25 static void udp_bpf_check_v6_needs_rebuild(struct proto *ops)
  26 {
  27         if (unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) {
  28                 spin_lock_bh(&udpv6_prot_lock);
  29                 if (likely(ops != udpv6_prot_saved)) {
  30                         udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV6], ops);
  31                         smp_store_release(&udpv6_prot_saved, ops);
  32                 }
  33                 spin_unlock_bh(&udpv6_prot_lock);
  34         }
  35 }
  36
  37 static int __init udp_bpf_v4_build_proto(void)
  38 {
  39         udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot);
  40         return 0;
  41 }
  42 core_initcall(udp_bpf_v4_build_proto);
  43
  44 struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
  45 {
  46         int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
  47
  48         if (sk->sk_family == AF_INET6)
  49                 udp_bpf_check_v6_needs_rebuild(psock->sk_proto);
  50
  51         return &udp_bpf_prots[family];
  52 }