net/vmw_vsock/af_vsock_tap.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Tap functions for AF_VSOCK sockets.
0004  *
0005  * Code based on net/netlink/af_netlink.c tap functions.
0006  */
0007
0008 #include <linux/module.h>
0009 #include <net/sock.h>
0010 #include <net/af_vsock.h>
0011 #include <linux/if_arp.h>
0012
0013 static DEFINE_SPINLOCK(vsock_tap_lock);
0014 static struct list_head vsock_tap_all __read_mostly =
0015                 LIST_HEAD_INIT(vsock_tap_all);
0016
0017 int vsock_add_tap(struct vsock_tap *vt)
0018 {
0019     if (unlikely(vt->dev->type != ARPHRD_VSOCKMON))
0020         return -EINVAL;
0021
0022     __module_get(vt->module);
0023
0024     spin_lock(&vsock_tap_lock);
0025     list_add_rcu(&vt->list, &vsock_tap_all);
0026     spin_unlock(&vsock_tap_lock);
0027
0028     return 0;
0029 }
0030 EXPORT_SYMBOL_GPL(vsock_add_tap);
0031
0032 int vsock_remove_tap(struct vsock_tap *vt)
0033 {
0034     struct vsock_tap *tmp;
0035     bool found = false;
0036
0037     spin_lock(&vsock_tap_lock);
0038
0039     list_for_each_entry(tmp, &vsock_tap_all, list) {
0040         if (vt == tmp) {
0041             list_del_rcu(&vt->list);
0042             found = true;
0043             goto out;
0044         }
0045     }
0046
0047     pr_warn("vsock_remove_tap: %p not found\n", vt);
0048 out:
0049     spin_unlock(&vsock_tap_lock);
0050
0051     synchronize_net();
0052
0053     if (found)
0054         module_put(vt->module);
0055
0056     return found ? 0 : -ENODEV;
0057 }
0058 EXPORT_SYMBOL_GPL(vsock_remove_tap);
0059
0060 static int __vsock_deliver_tap_skb(struct sk_buff *skb,
0061                    struct net_device *dev)
0062 {
0063     int ret = 0;
0064     struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
0065
0066     if (nskb) {
0067         dev_hold(dev);
0068
0069         nskb->dev = dev;
0070         ret = dev_queue_xmit(nskb);
0071         if (unlikely(ret > 0))
0072             ret = net_xmit_errno(ret);
0073
0074         dev_put(dev);
0075     }
0076
0077     return ret;
0078 }
0079
0080 static void __vsock_deliver_tap(struct sk_buff *skb)
0081 {
0082     int ret;
0083     struct vsock_tap *tmp;
0084
0085     list_for_each_entry_rcu(tmp, &vsock_tap_all, list) {
0086         ret = __vsock_deliver_tap_skb(skb, tmp->dev);
0087         if (unlikely(ret))
0088             break;
0089     }
0090 }
0091
0092 void vsock_deliver_tap(struct sk_buff *build_skb(void *opaque), void *opaque)
0093 {
0094     struct sk_buff *skb;
0095
0096     rcu_read_lock();
0097
0098     if (likely(list_empty(&vsock_tap_all)))
0099         goto out;
0100
0101     skb = build_skb(opaque);
0102     if (skb) {
0103         __vsock_deliver_tap(skb);
0104         consume_skb(skb);
0105     }
0106
0107 out:
0108     rcu_read_unlock();
0109 }
0110 EXPORT_SYMBOL_GPL(vsock_deliver_tap);