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 #include <net/inet_common.h> 8 9 #include "udp_impl.h" 10 11 static struct proto *udpv6_prot_saved __read_mostly; 12 13 static int sk_udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 14 int noblock, int flags, int *addr_len) 15 { 16 #if IS_ENABLED(CONFIG_IPV6) 17 if (sk->sk_family == AF_INET6) 18 return udpv6_prot_saved->recvmsg(sk, msg, len, noblock, flags, 19 addr_len); 20 #endif 21 return udp_prot.recvmsg(sk, msg, len, noblock, flags, addr_len); 22 } 23 24 static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 25 int nonblock, int flags, int *addr_len) 26 { 27 struct sk_psock *psock; 28 int copied, ret; 29 30 if (unlikely(flags & MSG_ERRQUEUE)) 31 return inet_recv_error(sk, msg, len, addr_len); 32 33 psock = sk_psock_get(sk); 34 if (unlikely(!psock)) 35 return sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len); 36 37 lock_sock(sk); 38 if (sk_psock_queue_empty(psock)) { 39 ret = sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len); 40 goto out; 41 } 42 43 msg_bytes_ready: 44 copied = sk_msg_recvmsg(sk, psock, msg, len, flags); 45 if (!copied) { 46 int data, err = 0; 47 long timeo; 48 49 timeo = sock_rcvtimeo(sk, nonblock); 50 data = sk_msg_wait_data(sk, psock, flags, timeo, &err); 51 if (data) { 52 if (!sk_psock_queue_empty(psock)) 53 goto msg_bytes_ready; 54 ret = sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len); 55 goto out; 56 } 57 if (err) { 58 ret = err; 59 goto out; 60 } 61 copied = -EAGAIN; 62 } 63 ret = copied; 64 out: 65 release_sock(sk); 66 sk_psock_put(sk, psock); 67 return ret; 68 } 69 70 enum { 71 UDP_BPF_IPV4, 72 UDP_BPF_IPV6, 73 UDP_BPF_NUM_PROTS, 74 }; 75 76 static DEFINE_SPINLOCK(udpv6_prot_lock); 77 static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS]; 78 79 static void udp_bpf_rebuild_protos(struct proto *prot, const struct proto *base) 80 { 81 *prot = *base; 82 prot->unhash = sock_map_unhash; 83 prot->close = sock_map_close; 84 prot->recvmsg = udp_bpf_recvmsg; 85 } 86 87 static void udp_bpf_check_v6_needs_rebuild(struct proto *ops) 88 { 89 if (unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) { 90 spin_lock_bh(&udpv6_prot_lock); 91 if (likely(ops != udpv6_prot_saved)) { 92 udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV6], ops); 93 smp_store_release(&udpv6_prot_saved, ops); 94 } 95 spin_unlock_bh(&udpv6_prot_lock); 96 } 97 } 98 99 static int __init udp_bpf_v4_build_proto(void) 100 { 101 udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot); 102 return 0; 103 } 104 core_initcall(udp_bpf_v4_build_proto); 105 106 int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) 107 { 108 int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6; 109 110 if (restore) { 111 sk->sk_write_space = psock->saved_write_space; 112 WRITE_ONCE(sk->sk_prot, psock->sk_proto); 113 return 0; 114 } 115 116 if (sk->sk_family == AF_INET6) 117 udp_bpf_check_v6_needs_rebuild(psock->sk_proto); 118 119 WRITE_ONCE(sk->sk_prot, &udp_bpf_prots[family]); 120 return 0; 121 } 122 EXPORT_SYMBOL_GPL(udp_bpf_update_proto); 123