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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>
This commit is contained in:
Mark McLoughlin 2008-08-15 15:09:56 -07:00 committed by David S. Miller
parent 04a0551c87
commit e3b9955697
2 changed files with 40 additions and 0 deletions
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39
drivers/net/tun.c
View File

@ -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)

1
include/linux/if_tun.h
View File

@ -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