tun: TUNGETIFF interface to query name and flags
Add a TUNGETIFF interface so that userspace can query a
tun/tap descriptor for its name and flags.
This is needed because it is common for one app to create
a tap interface, exec another app and pass it the file
descriptor for the interface. Without TUNGETIFF the spawned
app has no way of detecting wheter the interface has e.g.
IFF_VNET_HDR set.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Acked-by: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e6bbc63..95931a5 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -748,6 +748,36 @@
return err;
}
+static int tun_get_iff(struct net *net, struct file *file, struct ifreq *ifr)
+{
+ struct tun_struct *tun = file->private_data;
+
+ if (!tun)
+ return -EBADFD;
+
+ DBG(KERN_INFO "%s: tun_get_iff\n", tun->dev->name);
+
+ strcpy(ifr->ifr_name, tun->dev->name);
+
+ ifr->ifr_flags = 0;
+
+ if (ifr->ifr_flags & TUN_TUN_DEV)
+ ifr->ifr_flags |= IFF_TUN;
+ else
+ ifr->ifr_flags |= IFF_TAP;
+
+ if (tun->flags & TUN_NO_PI)
+ ifr->ifr_flags |= IFF_NO_PI;
+
+ if (tun->flags & TUN_ONE_QUEUE)
+ ifr->ifr_flags |= IFF_ONE_QUEUE;
+
+ if (tun->flags & TUN_VNET_HDR)
+ ifr->ifr_flags |= IFF_VNET_HDR;
+
+ return 0;
+}
+
/* This is like a cut-down ethtool ops, except done via tun fd so no
* privs required. */
static int set_offload(struct net_device *dev, unsigned long arg)
@@ -833,6 +863,15 @@
DBG(KERN_INFO "%s: tun_chr_ioctl cmd %d\n", tun->dev->name, cmd);
switch (cmd) {
+ case TUNGETIFF:
+ ret = tun_get_iff(current->nsproxy->net_ns, file, &ifr);
+ if (ret)
+ return ret;
+
+ if (copy_to_user(argp, &ifr, sizeof(ifr)))
+ return -EFAULT;
+ break;
+
case TUNSETNOCSUM:
/* Disable/Enable checksum */
if (arg)