af_vsock_tap.c

  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);