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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
// SPDX-License-Identifier: GPL-2.0
/* OpenVPN data channel offload
*
* Copyright (C) 2020-2025 OpenVPN, Inc.
*
* Author: James Yonan <james@openvpn.net>
* Antonio Quartulli <antonio@openvpn.net>
*/
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/udp.h>
#include "ovpnpriv.h"
#include "main.h"
#include "io.h"
#include "peer.h"
#include "socket.h"
#include "udp.h"
static void ovpn_socket_release_kref(struct kref *kref)
{
struct ovpn_socket *sock = container_of(kref, struct ovpn_socket,
refcount);
if (sock->sock->sk->sk_protocol == IPPROTO_UDP)
ovpn_udp_socket_detach(sock);
kfree_rcu(sock, rcu);
}
/**
* ovpn_socket_put - decrease reference counter
* @peer: peer whose socket reference counter should be decreased
* @sock: the RCU protected peer socket
*
* This function is only used internally. Users willing to release
* references to the ovpn_socket should use ovpn_socket_release()
*/
static void ovpn_socket_put(struct ovpn_peer *peer, struct ovpn_socket *sock)
{
kref_put(&sock->refcount, ovpn_socket_release_kref);
}
/**
* ovpn_socket_release - release resources owned by socket user
* @peer: peer whose socket should be released
*
* This function should be invoked when the user is shutting
* down and wants to drop its link to the socket.
*
* In case of UDP, the detach routine will drop a reference to the
* ovpn netdev, pointed by the ovpn_socket.
*
* In case of TCP, releasing the socket will cause dropping
* the refcounter for the peer it is linked to, thus allowing the peer
* disappear as well.
*
* This function is expected to be invoked exactly once per peer
*
* NOTE: this function may sleep
*/
void ovpn_socket_release(struct ovpn_peer *peer)
{
struct ovpn_socket *sock;
might_sleep();
sock = rcu_replace_pointer(peer->sock, NULL, true);
/* release may be invoked after socket was detached */
if (!sock)
return;
/* sanity check: we should not end up here if the socket
* was already closed
*/
if (!sock->sock->sk) {
DEBUG_NET_WARN_ON_ONCE(1);
return;
}
/* Drop the reference while holding the sock lock to avoid
* concurrent ovpn_socket_new call to mess up with a partially
* detached socket.
*
* Holding the lock ensures that a socket with refcnt 0 is fully
* detached before it can be picked by a concurrent reader.
*/
lock_sock(sock->sock->sk);
ovpn_socket_put(peer, sock);
release_sock(sock->sock->sk);
/* align all readers with sk_user_data being NULL */
synchronize_rcu();
}
static bool ovpn_socket_hold(struct ovpn_socket *sock)
{
return kref_get_unless_zero(&sock->refcount);
}
static int ovpn_socket_attach(struct ovpn_socket *sock, struct ovpn_peer *peer)
{
if (sock->sock->sk->sk_protocol == IPPROTO_UDP)
return ovpn_udp_socket_attach(sock, peer->ovpn);
return -EOPNOTSUPP;
}
/**
* ovpn_socket_new - create a new socket and initialize it
* @sock: the kernel socket to embed
* @peer: the peer reachable via this socket
*
* Return: an openvpn socket on success or a negative error code otherwise
*/
struct ovpn_socket *ovpn_socket_new(struct socket *sock, struct ovpn_peer *peer)
{
struct ovpn_socket *ovpn_sock;
int ret;
lock_sock(sock->sk);
/* a TCP socket can only be owned by a single peer, therefore there
* can't be any other user
*/
if (sock->sk->sk_protocol == IPPROTO_TCP && sock->sk->sk_user_data) {
ovpn_sock = ERR_PTR(-EBUSY);
goto sock_release;
}
/* a UDP socket can be shared across multiple peers, but we must make
* sure it is not owned by something else
*/
if (sock->sk->sk_protocol == IPPROTO_UDP) {
u8 type = READ_ONCE(udp_sk(sock->sk)->encap_type);
/* socket owned by other encapsulation module */
if (type && type != UDP_ENCAP_OVPNINUDP) {
ovpn_sock = ERR_PTR(-EBUSY);
goto sock_release;
}
rcu_read_lock();
ovpn_sock = rcu_dereference_sk_user_data(sock->sk);
if (ovpn_sock) {
/* socket owned by another ovpn instance, we can't use it */
if (ovpn_sock->ovpn != peer->ovpn) {
ovpn_sock = ERR_PTR(-EBUSY);
rcu_read_unlock();
goto sock_release;
}
/* this socket is already owned by this instance,
* therefore we can increase the refcounter and
* use it as expected
*/
if (WARN_ON(!ovpn_socket_hold(ovpn_sock))) {
/* this should never happen because setting
* the refcnt to 0 and detaching the socket
* is expected to be atomic
*/
ovpn_sock = ERR_PTR(-EAGAIN);
rcu_read_unlock();
goto sock_release;
}
rcu_read_unlock();
goto sock_release;
}
rcu_read_unlock();
}
/* socket is not owned: attach to this ovpn instance */
ovpn_sock = kzalloc(sizeof(*ovpn_sock), GFP_KERNEL);
if (!ovpn_sock) {
ovpn_sock = ERR_PTR(-ENOMEM);
goto sock_release;
}
ovpn_sock->ovpn = peer->ovpn;
ovpn_sock->sock = sock;
kref_init(&ovpn_sock->refcount);
ret = ovpn_socket_attach(ovpn_sock, peer);
if (ret < 0) {
kfree(ovpn_sock);
ovpn_sock = ERR_PTR(ret);
goto sock_release;
}
rcu_assign_sk_user_data(sock->sk, ovpn_sock);
sock_release:
release_sock(sock->sk);
return ovpn_sock;
}
|
