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

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Date:   Fri, 21 Oct 2016 13:50:12 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     fgao@...ai8.com, davem@...emloft.net, jasowang@...hat.com,
        edumazet@...gle.com, pabeni@...hat.com, netdev@...r.kernel.org
Cc:     gfree.wind@...il.com
Subject: Re: [PATCH net-next 1/1] driver: tun: Forbid to set IFF_TUN and
 IFF_TAP at the same time

Hello.

On 10/21/2016 9:14 AM, fgao@...ai8.com wrote:

> 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>
> ---
>  drivers/net/tun.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 8093e39..c1f89c1 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1752,6 +1752,10 @@ 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;
> +		}

    {} not needed here.

MBR, Sergei