1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Tap functions for AF_VSOCK sockets.
4 *
5 * Code based on net/netlink/af_netlink.c tap functions.
6 */
7
8#include <linux/module.h>
9#include <net/sock.h>
10#include <net/af_vsock.h>
11#include <linux/if_arp.h>
12
13static DEFINE_SPINLOCK(vsock_tap_lock);
14static struct list_head vsock_tap_all __read_mostly =
15				LIST_HEAD_INIT(vsock_tap_all);
16
17int vsock_add_tap(struct vsock_tap *vt)
18{
19	if (unlikely(vt->dev->type != ARPHRD_VSOCKMON))
20		return -EINVAL;
21
22	__module_get(vt->module);
23
24	spin_lock(&vsock_tap_lock);
25	list_add_rcu(&vt->list, &vsock_tap_all);
26	spin_unlock(&vsock_tap_lock);
27
28	return 0;
29}
30EXPORT_SYMBOL_GPL(vsock_add_tap);
31
32int vsock_remove_tap(struct vsock_tap *vt)
33{
34	struct vsock_tap *tmp;
35	bool found = false;
36
37	spin_lock(&vsock_tap_lock);
38
39	list_for_each_entry(tmp, &vsock_tap_all, list) {
40		if (vt == tmp) {
41			list_del_rcu(&vt->list);
42			found = true;
43			goto out;
44		}
45	}
46
47	pr_warn("vsock_remove_tap: %p not found\n", vt);
48out:
49	spin_unlock(&vsock_tap_lock);
50
51	synchronize_net();
52
53	if (found)
54		module_put(vt->module);
55
56	return found ? 0 : -ENODEV;
57}
58EXPORT_SYMBOL_GPL(vsock_remove_tap);
59
60static int __vsock_deliver_tap_skb(struct sk_buff *skb,
61				   struct net_device *dev)
62{
63	int ret = 0;
64	struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
65
66	if (nskb) {
67		dev_hold(dev);
68
69		nskb->dev = dev;
70		ret = dev_queue_xmit(nskb);
71		if (unlikely(ret > 0))
72			ret = net_xmit_errno(ret);
73
74		dev_put(dev);
75	}
76
77	return ret;
78}
79
80static void __vsock_deliver_tap(struct sk_buff *skb)
81{
82	int ret;
83	struct vsock_tap *tmp;
84
85	list_for_each_entry_rcu(tmp, &vsock_tap_all, list) {
86		ret = __vsock_deliver_tap_skb(skb, tmp->dev);
87		if (unlikely(ret))
88			break;
89	}
90}
91
92void vsock_deliver_tap(struct sk_buff *build_skb(void *opaque), void *opaque)
93{
94	struct sk_buff *skb;
95
96	rcu_read_lock();
97
98	if (likely(list_empty(&vsock_tap_all)))
99		goto out;
100
101	skb = build_skb(opaque);
102	if (skb) {
103		__vsock_deliver_tap(skb);
104		consume_skb(skb);
105	}
106
107out:
108	rcu_read_unlock();
109}
110EXPORT_SYMBOL_GPL(vsock_deliver_tap);
111