Commit e3b99556 authored by Mark McLoughlin's avatar Mark McLoughlin Committed by David S. Miller
Browse files

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: default avatarMark McLoughlin <markmc@redhat.com>
Acked-by: default avatarMax Krasnyansky <maxk@qualcomm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 04a0551c

drivers/net/tun.c

+39 −0
Original line number Diff line number Diff line
@@ -748,6 +748,36 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) 
	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 @@ static int tun_chr_ioctl(struct inode *inode, struct file *file, 
	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)

include/linux/if_tun.h

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ 
#define TUNGETFEATURES _IOR('T', 207, unsigned int)

#define TUNSETOFFLOAD  _IOW('T', 208, unsigned int)

#define TUNSETTXFILTER _IOW('T', 209, unsigned int)

#define TUNGETIFF      _IOR('T', 210, unsigned int)



/* TUNSETIFF ifr flags */

#define IFF_TUN		0x0001

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