1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (c) 2022 Bobby Eshleman <bobby.eshleman@bytedance.com> |
3 | * |
4 | * Based off of net/unix/unix_bpf.c |
5 | */ |
6 | |
7 | #include <linux/bpf.h> |
8 | #include <linux/module.h> |
9 | #include <linux/skmsg.h> |
10 | #include <linux/socket.h> |
11 | #include <linux/wait.h> |
12 | #include <net/af_vsock.h> |
13 | #include <net/sock.h> |
14 | |
15 | #define vsock_sk_has_data(__sk, __psock) \ |
16 | ({ !skb_queue_empty(&(__sk)->sk_receive_queue) || \ |
17 | !skb_queue_empty(&(__psock)->ingress_skb) || \ |
18 | !list_empty(&(__psock)->ingress_msg); \ |
19 | }) |
20 | |
21 | static struct proto *vsock_prot_saved __read_mostly; |
22 | static DEFINE_SPINLOCK(vsock_prot_lock); |
23 | static struct proto vsock_bpf_prot; |
24 | |
25 | static bool vsock_has_data(struct sock *sk, struct sk_psock *psock) |
26 | { |
27 | struct vsock_sock *vsk = vsock_sk(sk); |
28 | s64 ret; |
29 | |
30 | ret = vsock_connectible_has_data(vsk); |
31 | if (ret > 0) |
32 | return true; |
33 | |
34 | return vsock_sk_has_data(sk, psock); |
35 | } |
36 | |
37 | static bool vsock_msg_wait_data(struct sock *sk, struct sk_psock *psock, long timeo) |
38 | { |
39 | bool ret; |
40 | |
41 | DEFINE_WAIT_FUNC(wait, woken_wake_function); |
42 | |
43 | if (sk->sk_shutdown & RCV_SHUTDOWN) |
44 | return true; |
45 | |
46 | if (!timeo) |
47 | return false; |
48 | |
49 | add_wait_queue(wq_head: sk_sleep(sk), wq_entry: &wait); |
50 | sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); |
51 | ret = vsock_has_data(sk, psock); |
52 | if (!ret) { |
53 | wait_woken(wq_entry: &wait, TASK_INTERRUPTIBLE, timeout: timeo); |
54 | ret = vsock_has_data(sk, psock); |
55 | } |
56 | sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); |
57 | remove_wait_queue(wq_head: sk_sleep(sk), wq_entry: &wait); |
58 | return ret; |
59 | } |
60 | |
61 | static int __vsock_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags) |
62 | { |
63 | struct socket *sock = sk->sk_socket; |
64 | int err; |
65 | |
66 | if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) |
67 | err = vsock_connectible_recvmsg(sock, msg, len, flags); |
68 | else if (sk->sk_type == SOCK_DGRAM) |
69 | err = vsock_dgram_recvmsg(sock, msg, len, flags); |
70 | else |
71 | err = -EPROTOTYPE; |
72 | |
73 | return err; |
74 | } |
75 | |
76 | static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, |
77 | size_t len, int flags, int *addr_len) |
78 | { |
79 | struct sk_psock *psock; |
80 | int copied; |
81 | |
82 | psock = sk_psock_get(sk); |
83 | if (unlikely(!psock)) |
84 | return __vsock_recvmsg(sk, msg, len, flags); |
85 | |
86 | lock_sock(sk); |
87 | if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) { |
88 | release_sock(sk); |
89 | sk_psock_put(sk, psock); |
90 | return __vsock_recvmsg(sk, msg, len, flags); |
91 | } |
92 | |
93 | copied = sk_msg_recvmsg(sk, psock, msg, len, flags); |
94 | while (copied == 0) { |
95 | long timeo = sock_rcvtimeo(sk, noblock: flags & MSG_DONTWAIT); |
96 | |
97 | if (!vsock_msg_wait_data(sk, psock, timeo)) { |
98 | copied = -EAGAIN; |
99 | break; |
100 | } |
101 | |
102 | if (sk_psock_queue_empty(psock)) { |
103 | release_sock(sk); |
104 | sk_psock_put(sk, psock); |
105 | return __vsock_recvmsg(sk, msg, len, flags); |
106 | } |
107 | |
108 | copied = sk_msg_recvmsg(sk, psock, msg, len, flags); |
109 | } |
110 | |
111 | release_sock(sk); |
112 | sk_psock_put(sk, psock); |
113 | |
114 | return copied; |
115 | } |
116 | |
117 | /* Copy of original proto with updated sock_map methods */ |
118 | static struct proto vsock_bpf_prot = { |
119 | .close = sock_map_close, |
120 | .recvmsg = vsock_bpf_recvmsg, |
121 | .sock_is_readable = sk_msg_is_readable, |
122 | .unhash = sock_map_unhash, |
123 | }; |
124 | |
125 | static void vsock_bpf_rebuild_protos(struct proto *prot, const struct proto *base) |
126 | { |
127 | *prot = *base; |
128 | prot->close = sock_map_close; |
129 | prot->recvmsg = vsock_bpf_recvmsg; |
130 | prot->sock_is_readable = sk_msg_is_readable; |
131 | } |
132 | |
133 | static void vsock_bpf_check_needs_rebuild(struct proto *ops) |
134 | { |
135 | /* Paired with the smp_store_release() below. */ |
136 | if (unlikely(ops != smp_load_acquire(&vsock_prot_saved))) { |
137 | spin_lock_bh(lock: &vsock_prot_lock); |
138 | if (likely(ops != vsock_prot_saved)) { |
139 | vsock_bpf_rebuild_protos(prot: &vsock_bpf_prot, base: ops); |
140 | /* Make sure proto function pointers are updated before publishing the |
141 | * pointer to the struct. |
142 | */ |
143 | smp_store_release(&vsock_prot_saved, ops); |
144 | } |
145 | spin_unlock_bh(lock: &vsock_prot_lock); |
146 | } |
147 | } |
148 | |
149 | int vsock_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) |
150 | { |
151 | struct vsock_sock *vsk; |
152 | |
153 | if (restore) { |
154 | sk->sk_write_space = psock->saved_write_space; |
155 | sock_replace_proto(sk, proto: psock->sk_proto); |
156 | return 0; |
157 | } |
158 | |
159 | vsk = vsock_sk(sk); |
160 | if (!vsk->transport) |
161 | return -ENODEV; |
162 | |
163 | if (!vsk->transport->read_skb) |
164 | return -EOPNOTSUPP; |
165 | |
166 | vsock_bpf_check_needs_rebuild(ops: psock->sk_proto); |
167 | sock_replace_proto(sk, proto: &vsock_bpf_prot); |
168 | return 0; |
169 | } |
170 | |
171 | void __init vsock_bpf_build_proto(void) |
172 | { |
173 | vsock_bpf_rebuild_protos(prot: &vsock_bpf_prot, base: &vsock_proto); |
174 | } |
175 | |