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 #include <asm/ioctls.h>
9
10 #include "udp_impl.h"
11
12 static struct proto *udpv6_prot_saved __read_mostly;
13
sk_udp_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)14 static int sk_udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
15 int flags, int *addr_len)
16 {
17 #if IS_ENABLED(CONFIG_IPV6)
18 if (sk->sk_family == AF_INET6)
19 return udpv6_prot_saved->recvmsg(sk, msg, len, flags, addr_len);
20 #endif
21 return udp_prot.recvmsg(sk, msg, len, flags, addr_len);
22 }
23
udp_sk_has_data(struct sock * sk)24 static bool udp_sk_has_data(struct sock *sk)
25 {
26 return !skb_queue_empty(&udp_sk(sk)->reader_queue) ||
27 !skb_queue_empty(&sk->sk_receive_queue);
28 }
29
psock_has_data(struct sk_psock * psock)30 static bool psock_has_data(struct sk_psock *psock)
31 {
32 return !skb_queue_empty(&psock->ingress_skb) ||
33 !sk_psock_queue_empty(psock);
34 }
35
36 #define udp_msg_has_data(__sk, __psock) \
37 ({ udp_sk_has_data(__sk) || psock_has_data(__psock); })
38
udp_msg_wait_data(struct sock * sk,struct sk_psock * psock,long timeo)39 static int udp_msg_wait_data(struct sock *sk, struct sk_psock *psock,
40 long timeo)
41 {
42 DEFINE_WAIT_FUNC(wait, woken_wake_function);
43 int ret = 0;
44
45 if (sk->sk_shutdown & RCV_SHUTDOWN)
46 return 1;
47
48 if (!timeo)
49 return ret;
50
51 add_wait_queue(sk_sleep(sk), &wait);
52 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
53 ret = udp_msg_has_data(sk, psock);
54 if (!ret) {
55 wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
56 ret = udp_msg_has_data(sk, psock);
57 }
58 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
59 remove_wait_queue(sk_sleep(sk), &wait);
60 return ret;
61 }
62
udp_bpf_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)63 static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
64 int flags, int *addr_len)
65 {
66 struct sk_psock *psock;
67 int copied, ret;
68
69 if (unlikely(flags & MSG_ERRQUEUE))
70 return inet_recv_error(sk, msg, len, addr_len);
71
72 if (!len)
73 return 0;
74
75 psock = sk_psock_get(sk);
76 if (unlikely(!psock))
77 return sk_udp_recvmsg(sk, msg, len, flags, addr_len);
78
79 if (!psock_has_data(psock)) {
80 ret = sk_udp_recvmsg(sk, msg, len, flags, addr_len);
81 goto out;
82 }
83
84 msg_bytes_ready:
85 copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
86 if (!copied) {
87 long timeo;
88 int data;
89
90 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
91 data = udp_msg_wait_data(sk, psock, timeo);
92 if (data) {
93 if (psock_has_data(psock))
94 goto msg_bytes_ready;
95 ret = sk_udp_recvmsg(sk, msg, len, flags, addr_len);
96 goto out;
97 }
98 copied = -EAGAIN;
99 }
100 ret = copied;
101 out:
102 sk_psock_put(sk, psock);
103 return ret;
104 }
105
106 enum {
107 UDP_BPF_IPV4,
108 UDP_BPF_IPV6,
109 UDP_BPF_NUM_PROTS,
110 };
111
112 static DEFINE_SPINLOCK(udpv6_prot_lock);
113 static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS];
114
udp_bpf_ioctl(struct sock * sk,int cmd,int * karg)115 static int udp_bpf_ioctl(struct sock *sk, int cmd, int *karg)
116 {
117 if (cmd != SIOCINQ)
118 return udp_ioctl(sk, cmd, karg);
119
120 /* Since we don't hold a lock, sk_receive_queue may contain data.
121 * BPF might only be processing this data at the moment. We only
122 * care about the data in the ingress_msg here.
123 */
124 *karg = sk_msg_first_len(sk);
125 return 0;
126 }
127
udp_bpf_rebuild_protos(struct proto * prot,const struct proto * base)128 static void udp_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
129 {
130 *prot = *base;
131 prot->close = sock_map_close;
132 prot->recvmsg = udp_bpf_recvmsg;
133 prot->sock_is_readable = sk_msg_is_readable;
134 prot->ioctl = udp_bpf_ioctl;
135 }
136
udp_bpf_check_v6_needs_rebuild(struct proto * ops)137 static void udp_bpf_check_v6_needs_rebuild(struct proto *ops)
138 {
139 if (unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) {
140 spin_lock_bh(&udpv6_prot_lock);
141 if (likely(ops != udpv6_prot_saved)) {
142 udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV6], ops);
143 smp_store_release(&udpv6_prot_saved, ops);
144 }
145 spin_unlock_bh(&udpv6_prot_lock);
146 }
147 }
148
udp_bpf_v4_build_proto(void)149 static int __init udp_bpf_v4_build_proto(void)
150 {
151 udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot);
152 return 0;
153 }
154 late_initcall(udp_bpf_v4_build_proto);
155
udp_bpf_update_proto(struct sock * sk,struct sk_psock * psock,bool restore)156 int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
157 {
158 int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
159
160 if (restore) {
161 WRITE_ONCE(sk->sk_write_space, psock->saved_write_space);
162 sock_replace_proto(sk, psock->sk_proto);
163 return 0;
164 }
165
166 if (sk->sk_family == AF_INET6)
167 udp_bpf_check_v6_needs_rebuild(psock->sk_proto);
168
169 sock_replace_proto(sk, &udp_bpf_prots[family]);
170 return 0;
171 }
172 EXPORT_SYMBOL_GPL(udp_bpf_update_proto);
173