Subject: Re: [PATCH net] bareudp: Disallow udp port 0.

From: Martin Varghese <[email-masked]>
Date: Fri, 31 Jul 2020 08:20:34 +0530

On Thu, Jul 30, 2020 at 04:20:30PM -0700, Jakub Kicinski wrote:
> On Thu, 30 Jul 2020 22:33:51 +0530 Martin Varghese wrote:
> > From: Martin Varghese <[email-masked]>
> > 
> > Kernel does not support udp destination port 0 on wire. Hence
> > bareudp device with udp destination port 0 must be disallowed.
> > 
> > Fixes: 571912c69f0e ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
> > Signed-off-by: Martin Varghese <[email-masked]>
> > ---
> >  drivers/net/bareudp.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
> > index 88e7900853db..08b195d32cbe 100644
> > --- a/drivers/net/bareudp.c
> > +++ b/drivers/net/bareudp.c
> > @@ -578,8 +578,13 @@ static int bareudp2info(struct nlattr *data[], struct bareudp_conf *conf,
> >  		return -EINVAL;
> >  	}
> >  
> > -	if (data[IFLA_BAREUDP_PORT])
> > +	if (data[IFLA_BAREUDP_PORT]) {
> >  		conf->port =  nla_get_u16(data[IFLA_BAREUDP_PORT]);
> > +		if (!conf->port) {
> > +			NL_SET_ERR_MSG(extack, "udp port 0 not supported");
> > +			return -EINVAL;
> > +		}
> > +	}
> 
> Please use one of the NLA_POLICY_**-ies, probably NLA_POLICY_MIN() ? 
> That's better for documenting, exporting for user space, and will also
> point the user space to the attribute in exack automatically.

Ok, I will check how to do this way. Thanks for the feedback.

Regards,
Martin