From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Date: Thu, 29 Nov 2018 13:45:39 +0000 (+0100)
Subject: tun: forbid iface creation with rtnl ops
X-Git-Tag: v3.18.130~34
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=eb75b9b7ec77ed5d11316ef99ee905a16b432430;p=profile%2Fwearable%2Fplatform%2Fkernel%2Flinux-3.18-exynos7270.git

tun: forbid iface creation with rtnl ops

[ Upstream commit 35b827b6d06199841a83839e8bb69c0cd13a28be ]

It's not supported right now (the goal of the initial patch was to support
'ip link del' only).

Before the patch:
$ ip link add foo type tun
[  239.632660] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[snip]
[  239.636410] RIP: 0010:register_netdevice+0x8e/0x3a0

This panic occurs because dev->netdev_ops is not set by tun_setup(). But to
have something usable, it will require more than just setting
netdev_ops.

Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX")
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7448ebe..6338be5 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1423,9 +1423,9 @@ static void tun_setup(struct net_device *dev)
  */
 static int tun_validate(struct nlattr *tb[], struct nlattr *data[])
 {
-	if (!data)
-		return 0;
-	return -EINVAL;
+	/* NL_SET_ERR_MSG(extack,
+		       "tun/tap creation via rtnetlink is not supported."); */
+	return -EOPNOTSUPP;
 }
 
 static struct rtnl_link_ops tun_link_ops __read_mostly = {