linux-kernel - Re: [PATCH v4] net: netfilter: Fix rpfilter dropping vrf packets by mistake

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Date:   Sat, 29 Jun 2019 02:13:06 +0000
From:   linmiaohe <linmiaohe@...wei.com>
To:     David Ahern <dsahern@...il.com>
CC:     "pablo@...filter.org" <pablo@...filter.org>,
        "kadlec@...ckhole.kfki.hu" <kadlec@...ckhole.kfki.hu>,
        "fw@...len.de" <fw@...len.de>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuznet@....inr.ac.ru" <kuznet@....inr.ac.ru>,
        "yoshfuji@...ux-ipv6.org" <yoshfuji@...ux-ipv6.org>,
        "netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
        "coreteam@...filter.org" <coreteam@...filter.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mingfangsen <mingfangsen@...wei.com>
Subject: Re: [PATCH v4] net: netfilter: Fix rpfilter dropping vrf packets by
 mistake

On 6/29/19 1:05 AM, David Ahern wrote:
> On 6/28/19 3:06 AM, Miaohe Lin wrote:
> > diff --git a/net/ipv6/netfilter/ip6t_rpfilter.c 
> > b/net/ipv6/netfilter/ip6t_rpfilter.c
> > index 6bcaf7357183..3c4a1772c15f 100644
> > --- a/net/ipv6/netfilter/ip6t_rpfilter.c
> > +++ b/net/ipv6/netfilter/ip6t_rpfilter.c
> > @@ -55,6 +55,10 @@ static bool rpfilter_lookup_reverse6(struct net *net, const struct sk_buff *skb,
> >  	if (rpfilter_addr_linklocal(&iph->saddr)) {
> >  		lookup_flags |= RT6_LOOKUP_F_IFACE;
> >  		fl6.flowi6_oif = dev->ifindex;
> > +	/* Set flowi6_oif for vrf devices to lookup route in l3mdev domain. */
> > +	} else if (netif_is_l3_master(dev) || netif_is_l3_slave(dev)) {
> > +		lookup_flags |= FLOWI_FLAG_SKIP_NH_OIF;
>
> you don't need to set that flag here. It is done by the fib_rules code as needed.
>
You're right. Fib rules code would set FLOWI_FLAG_SKIP_NH_OIF flag.  But I set
it here for distinguish with the flags & XT_RPFILTER_LOOSE branch. Without
this, they do the same work and maybe should be  combined. I don't want to
do that as that makes code confusing.
Is this code snipet below ok ? If so, I would delete this flag setting.
 
       } else if (netif_is_l3_master(dev) || netif_is_l3_slave(dev)) {
               fl6.flowi6_oif = dev->ifindex;
        } else if ((flags & XT_RPFILTER_LOOSE) == 0)
                fl6.flowi6_oif = dev->ifindex;