net/vmw_vsock/af_vsock_tap.c

   1 /*
   2  * Tap functions for AF_VSOCK sockets.
   3  *
   4  * Code based on net/netlink/af_netlink.c tap functions.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <net/sock.h>
  14 #include <net/af_vsock.h>
  15 #include <linux/if_arp.h>
  16
  17 static DEFINE_SPINLOCK(vsock_tap_lock);
  18 static struct list_head vsock_tap_all __read_mostly =
  19                                 LIST_HEAD_INIT(vsock_tap_all);
  20
  21 int vsock_add_tap(struct vsock_tap *vt)
  22 {
  23         if (unlikely(vt->dev->type != ARPHRD_VSOCKMON))
  24                 return -EINVAL;
  25
  26         __module_get(vt->module);
  27
  28         spin_lock(&vsock_tap_lock);
  29         list_add_rcu(&vt->list, &vsock_tap_all);
  30         spin_unlock(&vsock_tap_lock);
  31
  32         return 0;
  33 }
  34 EXPORT_SYMBOL_GPL(vsock_add_tap);
  35
  36 int vsock_remove_tap(struct vsock_tap *vt)
  37 {
  38         struct vsock_tap *tmp;
  39         bool found = false;
  40
  41         spin_lock(&vsock_tap_lock);
  42
  43         list_for_each_entry(tmp, &vsock_tap_all, list) {
  44                 if (vt == tmp) {
  45                         list_del_rcu(&vt->list);
  46                         found = true;
  47                         goto out;
  48                 }
  49         }
  50
  51         pr_warn("vsock_remove_tap: %p not found\n", vt);
  52 out:
  53         spin_unlock(&vsock_tap_lock);
  54
  55         synchronize_net();
  56
  57         if (found)
  58                 module_put(vt->module);
  59
  60         return found ? 0 : -ENODEV;
  61 }
  62 EXPORT_SYMBOL_GPL(vsock_remove_tap);
  63
  64 static int __vsock_deliver_tap_skb(struct sk_buff *skb,
  65                                    struct net_device *dev)
  66 {
  67         int ret = 0;
  68         struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
  69
  70         if (nskb) {
  71                 dev_hold(dev);
  72
  73                 nskb->dev = dev;
  74                 ret = dev_queue_xmit(nskb);
  75                 if (unlikely(ret > 0))
  76                         ret = net_xmit_errno(ret);
  77
  78                 dev_put(dev);
  79         }
  80
  81         return ret;
  82 }
  83
  84 static void __vsock_deliver_tap(struct sk_buff *skb)
  85 {
  86         int ret;
  87         struct vsock_tap *tmp;
  88
  89         list_for_each_entry_rcu(tmp, &vsock_tap_all, list) {
  90                 ret = __vsock_deliver_tap_skb(skb, tmp->dev);
  91                 if (unlikely(ret))
  92                         break;
  93         }
  94 }
  95
  96 void vsock_deliver_tap(struct sk_buff *build_skb(void *opaque), void *opaque)
  97 {
  98         struct sk_buff *skb;
  99
 100         rcu_read_lock();
 101
 102         if (likely(list_empty(&vsock_tap_all)))
 103                 goto out;
 104
 105         skb = build_skb(opaque);
 106         if (skb) {
 107                 __vsock_deliver_tap(skb);
 108                 consume_skb(skb);
 109         }
 110
 111 out:
 112         rcu_read_unlock();
 113 }
 114 EXPORT_SYMBOL_GPL(vsock_deliver_tap);