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tun: Add ioctl() TUNGETDEVNETNS cmd to allow obtaining real net ns of tun device

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In commit f2780d6d74 "tun: Add ioctl() SIOCGSKNS cmd to allow
obtaining net ns of tun device" it was missed that tun may change
its net ns, while net ns of socket remains the same as it was
created initially. SIOCGSKNS returns net ns of socket, so it is
not suitable for obtaining net ns of device.

We may have two tun devices with the same names in two net ns,
and in this case it's not possible to determ, which of them
fd refers to (TUNGETIFF will return the same name).

This patch adds new ioctl() cmd for obtaining net ns of a device.

Reported-by: Harald Albrecht <harald.albrecht@gmx.net>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kirill Tkhai 2019-03-20 12:16:42 +03:00 committed by David S. Miller
parent 28b18b39c5
commit 0c3e0e3bb6
2 changed files with 9 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

8
drivers/net/tun.c
View file

@ -3102,6 +3102,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd); tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd);
net = dev_net(tun->dev);
ret = 0; ret = 0;
switch (cmd) { switch (cmd) {
case TUNGETIFF: case TUNGETIFF:
@ -3327,6 +3328,13 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
ret = tun_net_change_carrier(tun->dev, (bool)carrier); ret = tun_net_change_carrier(tun->dev, (bool)carrier);
break; break;
case TUNGETDEVNETNS:
ret = -EPERM;
if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
goto unlock;
ret = open_related_ns(&net->ns, get_net_ns);
break;
default: default:
ret = -EINVAL; ret = -EINVAL;
break; break;

1
include/uapi/linux/if_tun.h
View file

@ -60,6 +60,7 @@
#define TUNSETSTEERINGEBPF _IOR('T', 224, int) #define TUNSETSTEERINGEBPF _IOR('T', 224, int)
#define TUNSETFILTEREBPF _IOR('T', 225, int) #define TUNSETFILTEREBPF _IOR('T', 225, int)
#define TUNSETCARRIER _IOW('T', 226, int) #define TUNSETCARRIER _IOW('T', 226, int)
#define TUNGETDEVNETNS _IO('T', 227)
/* TUNSETIFF ifr flags */ /* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001 #define IFF_TUN 0x0001