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
11static struct proto *udpv6_prot_saved __read_mostly;
12
13static int sk_udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
14 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, flags, addr_len);
19#endif
20 return udp_prot.recvmsg(sk, msg, len, flags, addr_len);
21}
22
23static bool udp_sk_has_data(struct sock *sk)
24{
25 return !skb_queue_empty(list: &udp_sk(sk)->reader_queue) ||
26 !skb_queue_empty(list: &sk->sk_receive_queue);
27}
28
29static bool psock_has_data(struct sk_psock *psock)
30{
31 return !skb_queue_empty(list: &psock->ingress_skb) ||
32 !sk_psock_queue_empty(psock);
33}
34
35#define udp_msg_has_data(__sk, __psock) \
36 ({ udp_sk_has_data(__sk) || psock_has_data(__psock); })
37
38static int udp_msg_wait_data(struct sock *sk, struct sk_psock *psock,
39 long timeo)
40{
41 DEFINE_WAIT_FUNC(wait, woken_wake_function);
42 int ret = 0;
43
44 if (sk->sk_shutdown & RCV_SHUTDOWN)
45 return 1;
46
47 if (!timeo)
48 return ret;
49
50 add_wait_queue(wq_head: sk_sleep(sk), wq_entry: &wait);
51 sk_set_bit(nr: SOCKWQ_ASYNC_WAITDATA, sk);
52 ret = udp_msg_has_data(sk, psock);
53 if (!ret) {
54 wait_woken(wq_entry: &wait, TASK_INTERRUPTIBLE, timeout: timeo);
55 ret = udp_msg_has_data(sk, psock);
56 }
57 sk_clear_bit(nr: SOCKWQ_ASYNC_WAITDATA, sk);
58 remove_wait_queue(wq_head: sk_sleep(sk), wq_entry: &wait);
59 return ret;
60}
61
62static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
63 int flags, int *addr_len)
64{
65 struct sk_psock *psock;
66 int copied, ret;
67
68 if (unlikely(flags & MSG_ERRQUEUE))
69 return inet_recv_error(sk, msg, len, addr_len);
70
71 if (!len)
72 return 0;
73
74 psock = sk_psock_get(sk);
75 if (unlikely(!psock))
76 return sk_udp_recvmsg(sk, msg, len, flags, addr_len);
77
78 if (!psock_has_data(psock)) {
79 ret = sk_udp_recvmsg(sk, msg, len, flags, addr_len);
80 goto out;
81 }
82
83msg_bytes_ready:
84 copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
85 if (!copied) {
86 long timeo;
87 int data;
88
89 timeo = sock_rcvtimeo(sk, noblock: flags & MSG_DONTWAIT);
90 data = udp_msg_wait_data(sk, psock, timeo);
91 if (data) {
92 if (psock_has_data(psock))
93 goto msg_bytes_ready;
94 ret = sk_udp_recvmsg(sk, msg, len, flags, addr_len);
95 goto out;
96 }
97 copied = -EAGAIN;
98 }
99 ret = copied;
100out:
101 sk_psock_put(sk, psock);
102 return ret;
103}
104
105enum {
106 UDP_BPF_IPV4,
107 UDP_BPF_IPV6,
108 UDP_BPF_NUM_PROTS,
109};
110
111static DEFINE_SPINLOCK(udpv6_prot_lock);
112static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS];
113
114static void udp_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
115{
116 *prot = *base;
117 prot->close = sock_map_close;
118 prot->recvmsg = udp_bpf_recvmsg;
119 prot->sock_is_readable = sk_msg_is_readable;
120}
121
122static void udp_bpf_check_v6_needs_rebuild(struct proto *ops)
123{
124 if (unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) {
125 spin_lock_bh(lock: &udpv6_prot_lock);
126 if (likely(ops != udpv6_prot_saved)) {
127 udp_bpf_rebuild_protos(prot: &udp_bpf_prots[UDP_BPF_IPV6], base: ops);
128 smp_store_release(&udpv6_prot_saved, ops);
129 }
130 spin_unlock_bh(lock: &udpv6_prot_lock);
131 }
132}
133
134static int __init udp_bpf_v4_build_proto(void)
135{
136 udp_bpf_rebuild_protos(prot: &udp_bpf_prots[UDP_BPF_IPV4], base: &udp_prot);
137 return 0;
138}
139late_initcall(udp_bpf_v4_build_proto);
140
141int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
142{
143 int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
144
145 if (restore) {
146 sk->sk_write_space = psock->saved_write_space;
147 sock_replace_proto(sk, proto: psock->sk_proto);
148 return 0;
149 }
150
151 if (sk->sk_family == AF_INET6)
152 udp_bpf_check_v6_needs_rebuild(ops: psock->sk_proto);
153
154 sock_replace_proto(sk, proto: &udp_bpf_prots[family]);
155 return 0;
156}
157EXPORT_SYMBOL_GPL(udp_bpf_update_proto);
158

source code of linux/net/ipv4/udp_bpf.c