netdev - [PATCH v2 net-next 1/1] driver: tun: Forbid to set IFF_TUN and IFF

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Date:   Fri, 21 Oct 2016 19:02:15 +0800
From:   fgao@...ai8.com
To:     davem@...emloft.net, jasowang@...hat.com, edumazet@...gle.com,
        pabeni@...hat.com, netdev@...r.kernel.org
Cc:     gfree.wind@...il.com, Gao Feng <fgao@...ai8.com>
Subject: [PATCH v2 net-next 1/1] driver: tun: Forbid to set IFF_TUN and IFF_TAP at the same time

From: Gao Feng <fgao@...ai8.com>

Current tun driver permits the ifr_flags is set with IFF_TUN and
IFF_TAP at the same time. But actually there is only IFF_TUN flag
works. And it does not make sense these two flags are set, so add
this check.

Signed-off-by: Gao Feng <fgao@...ai8.com>
---
 v2: Remove useless {}
 v1: Initial patch

 drivers/net/tun.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 8093e39..faaa189 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1752,6 +1752,9 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		if (err < 0)
 			return err;
 
+		if ((ifr->ifr_flags & (IFF_TUN | IFF_TAP)) == (IFF_TUN | IFF_TAP))
+			return -EINVAL;
+
 		/* Set dev type */
 		if (ifr->ifr_flags & IFF_TUN) {
 			/* TUN device */
-- 
1.9.1