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
sk_udp_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int noblock,int flags,int * addr_len)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
udp_bpf_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int nonblock,int flags,int * addr_len)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
udp_bpf_rebuild_protos(struct proto * prot,const struct proto * base)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
udp_bpf_check_v6_needs_rebuild(struct proto * ops)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
udp_bpf_v4_build_proto(void)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
udp_bpf_update_proto(struct sock * sk,struct sk_psock * psock,bool restore)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