> -Original Message-
> From: Stephen Hemminger [mailto:step...@networkplumber.org]
> Sent: 2017年9月21日 23:10
> To: Zhang Shengju
> Cc: da...@davemloft.net; will...@google.com; netdev@vger.kernel.org
> Subject: Re: [net-next 2/2] ifb: add device MTU validation check
>
> On Thu, 21 Sep 2017 21:32:02 +0800
> Zhang Shengju wrote:
>
> > Currently, any mtu value can be assigned when adding a new ifb device:
> > [~]# ip link add name ifb2 mtu 10 type ifb [~]# ip link show ifb2
> > 18: ifb2: mtu 10 qdisc noop state DOWN mode
> DEFAULT group default qlen 32
> > link/ether 7a:bf:f4:63:da:d1 brd ff:ff:ff:ff:ff:ff
> >
> > This patch adds device MTU validation check.
> >
> > Signed-off-by: Zhang Shengju
> > ---
> > drivers/net/ifb.c | 8
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c index
> > 8870bd2..ce84ad2 100644
> > --- a/drivers/net/ifb.c
> > +++ b/drivers/net/ifb.c
> > @@ -282,6 +282,14 @@ static int ifb_validate(struct nlattr *tb[], struct
> nlattr *data[],
> > if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
> > return -EADDRNOTAVAIL;
> > }
> > +
> > + if (tb[IFLA_MTU]) {
> > + u32 mtu = nla_get_u32(tb[IFLA_MTU]);
> > +
> > + if (mtu < ETH_MIN_MTU || mtu > ETH_DATA_LEN)
> > + return -EINVAL;
> > + }
> > +
> > return 0;
> > }
> >
>
> What about running ifb with packets coming from devices with jumbo frames?
> Also since ifb is an input only device, MTU doesn't matter.
Actually ifb_setup() function setup ifb valid MTU range: [68, 1500], and
this will be check at dev_set_mtu() function.
You can't setup mtu out of this range after creation, but you can set any
value when adding new ifb device.
This is inconsistent, and I think we should add this check at creation time
BRs,
ZSJ
