netdev - Re: [PATCH net-next 1/2] ipv6: do not set routes if disable

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Message-ID: <20180329081929.GA3186@localhost.localdomain>
Date:   Thu, 29 Mar 2018 10:19:30 +0200
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     David Ahern <dsahern@...il.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] ipv6: do not set routes if disable_ipv6 has
 been enabled

> On 3/27/18 11:11 AM, Lorenzo Bianconi wrote:
> > Do not allow to set ipv6 routes from userspace if disable_ipv6 has been
> > enabled. The issue can be triggered using the following reproducer:
> > 
> > - sysctl net.ipv6.conf.all.disable_ipv6=1
> > - ip -6 route add a:b:c:d::/64 dev em1
> > - ip -6 route show
> >   a:b:c:d::/64 dev em1 metric 1024 pref medium
> > 
> > Fix it checking disable_ipv6 value in ip6_route_info_create routine
> > 
> > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
> > ---
> >  net/ipv6/route.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > index 1d0eaa69874d..672fd7fdb037 100644
> > --- a/net/ipv6/route.c
> > +++ b/net/ipv6/route.c
> > @@ -2917,6 +2917,11 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg,
> >  	if (!dev)
> >  		goto out;
> >  
> > +	if (idev->cnf.disable_ipv6) {
> > +		err = -EACCES;
> 
> you need an extack message telling the user that IPv6 is disabled on the
> nexthop device.
> 

Ack, will do in v2.

Regards,
Lorenzo

> > +		goto out;
> > +	}
> > +
> >  	if (!(dev->flags & IFF_UP)) {
> >  		NL_SET_ERR_MSG(extack, "Nexthop device is not up");
> >  		err = -ENETDOWN;
> > 
>