summaryrefslogtreecommitdiffstats
path: root/net/unix/unix_bpf.c
blob: 7cf14c6b172549a09f23e5eb41c145d0fb0cb931 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */

#include <linux/skmsg.h>
#include <linux/bpf.h>
#include <net/sock.h>
#include <net/af_unix.h>

#define unix_sk_has_data(__sk, __psock)					\
		({	!skb_queue_empty(&__sk->sk_receive_queue) ||	\
			!skb_queue_empty(&__psock->ingress_skb) ||	\
			!list_empty(&__psock->ingress_msg);		\
		})

static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
			      long timeo)
{
	DEFINE_WAIT_FUNC(wait, woken_wake_function);
	struct unix_sock *u = unix_sk(sk);
	int ret = 0;

	if (sk->sk_shutdown & RCV_SHUTDOWN)
		return 1;

	if (!timeo)
		return ret;

	add_wait_queue(sk_sleep(sk), &wait);
	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
	if (!unix_sk_has_data(sk, psock)) {
		mutex_unlock(&u->iolock);
		wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
		mutex_lock(&u->iolock);
		ret = unix_sk_has_data(sk, psock);
	}
	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
	remove_wait_queue(sk_sleep(sk), &wait);
	return ret;
}

static int __unix_recvmsg(struct sock *sk, struct msghdr *msg,
			  size_t len, int flags)
{
	if (sk->sk_type == SOCK_DGRAM)
		return __unix_dgram_recvmsg(sk, msg, len, flags);
	else
		return __unix_stream_recvmsg(sk, msg, len, flags);
}

static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
			    size_t len, int flags, int *addr_len)
{
	struct unix_sock *u = unix_sk(sk);
	struct sk_psock *psock;
	int copied;

	psock = sk_psock_get(sk);
	if (unlikely(!psock))
		return __unix_recvmsg(sk, msg, len, flags);

	mutex_lock(&u->iolock);
	if (!skb_queue_empty(&sk->sk_receive_queue) &&
	    sk_psock_queue_empty(psock)) {
		mutex_unlock(&u->iolock);
		sk_psock_put(sk, psock);
		return __unix_recvmsg(sk, msg, len, flags);
	}

msg_bytes_ready:
	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
	if (!copied) {
		long timeo;
		int data;

		timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
		data = unix_msg_wait_data(sk, psock, timeo);
		if (data) {
			if (!sk_psock_queue_empty(psock))
				goto msg_bytes_ready;
			mutex_unlock(&u->iolock);
			sk_psock_put(sk, psock);
			return __unix_recvmsg(sk, msg, len, flags);
		}
		copied = -EAGAIN;
	}
	mutex_unlock(&u->iolock);
	sk_psock_put(sk, psock);
	return copied;
}

static struct proto *unix_dgram_prot_saved __read_mostly;
static DEFINE_SPINLOCK(unix_dgram_prot_lock);
static struct proto unix_dgram_bpf_prot;

static struct proto *unix_stream_prot_saved __read_mostly;
static DEFINE_SPINLOCK(unix_stream_prot_lock);
static struct proto unix_stream_bpf_prot;

static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
{
	*prot        = *base;
	prot->close  = sock_map_close;
	prot->recvmsg = unix_bpf_recvmsg;
	prot->sock_is_readable = sk_msg_is_readable;
}

static void unix_stream_bpf_rebuild_protos(struct proto *prot,
					   const struct proto *base)
{
	*prot        = *base;
	prot->close  = sock_map_close;
	prot->recvmsg = unix_bpf_recvmsg;
	prot->sock_is_readable = sk_msg_is_readable;
	prot->unhash  = sock_map_unhash;
}

static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops)
{
	if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) {
		spin_lock_bh(&unix_dgram_prot_lock);
		if (likely(ops != unix_dgram_prot_saved)) {
			unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops);
			smp_store_release(&unix_dgram_prot_saved, ops);
		}
		spin_unlock_bh(&unix_dgram_prot_lock);
	}
}

static void unix_stream_bpf_check_needs_rebuild(struct proto *ops)
{
	if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) {
		spin_lock_bh(&unix_stream_prot_lock);
		if (likely(ops != unix_stream_prot_saved)) {
			unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops);
			smp_store_release(&unix_stream_prot_saved, ops);
		}
		spin_unlock_bh(&unix_stream_prot_lock);
	}
}

int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
{
	if (sk->sk_type != SOCK_DGRAM)
		return -EOPNOTSUPP;

	if (restore) {
		sk->sk_write_space = psock->saved_write_space;
		WRITE_ONCE(sk->sk_prot, psock->sk_proto);
		return 0;
	}

	unix_dgram_bpf_check_needs_rebuild(psock->sk_proto);
	WRITE_ONCE(sk->sk_prot, &unix_dgram_bpf_prot);
	return 0;
}

int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
{
	if (restore) {
		sk->sk_write_space = psock->saved_write_space;
		WRITE_ONCE(sk->sk_prot, psock->sk_proto);
		return 0;
	}

	unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
	WRITE_ONCE(sk->sk_prot, &unix_stream_bpf_prot);
	return 0;
}

void __init unix_bpf_build_proto(void)
{
	unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
	unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);

}