net/vmw_vsock/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
  13 static DEFINE_SPINLOCK(vsock_tap_lock);
  14 static struct list_head vsock_tap_all __read_mostly =
  15                                 LIST_HEAD_INIT(vsock_tap_all);
  16
  17 int 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 }
  30 EXPORT_SYMBOL_GPL(vsock_add_tap);
  31
  32 int 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);
  48 out:
  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 }
  58 EXPORT_SYMBOL_GPL(vsock_remove_tap);
  59
  60 static 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
  80 static 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
  92 void 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
 107 out:
 108         rcu_read_unlock();
 109 }
 110 EXPORT_SYMBOL_GPL(vsock_deliver_tap);