[PATCH v4] net: netfilter: Fix rpfilter dropping vrf packets by mistake

[PATCH v4] net: netfilter: Fix rpfilter dropping vrf packets by mistake

[Miaohe Lin]

When firewalld is enabled with ipv4/ipv6 rpfilter, vrf
ipv4/ipv6 packets will be dropped. Vrf device will pass
through netfilter hook twice. One with enslaved device
and another one with l3 master device. So in device may
dismatch witch out device because out device is always
enslaved device.So failed with the check of the rpfilter
and drop the packets by mistake.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 net/ipv4/netfilter/ipt_rpfilter.c  | 1 +
 net/ipv6/netfilter/ip6t_rpfilter.c | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/netfilter/ipt_rpfilter.c b/net/ipv4/netfilter/ipt_rpfilter.c
index 59031670b16a..cc23f1ce239c 100644
--- a/net/ipv4/netfilter/ipt_rpfilter.c
+++ b/net/ipv4/netfilter/ipt_rpfilter.c
@@ -78,6 +78,7 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
 	flow.flowi4_mark = info->flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
 	flow.flowi4_tos = RT_TOS(iph->tos);
 	flow.flowi4_scope = RT_SCOPE_UNIVERSE;
+	flow.flowi4_oif = l3mdev_master_ifindex_rcu(xt_in(par));
 
 	return rpfilter_lookup_reverse(xt_net(par), &flow, xt_in(par), info->flags) ^ invert;
 }
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;
+		fl6.flowi6_oif = dev->ifindex;
 	} else if ((flags & XT_RPFILTER_LOOSE) == 0)
 		fl6.flowi6_oif = dev->ifindex;
 
@@ -70,7 +74,9 @@ static bool rpfilter_lookup_reverse6(struct net *net, const struct sk_buff *skb,
 		goto out;
 	}
 
-	if (rt->rt6i_idev->dev == dev || (flags & XT_RPFILTER_LOOSE))
+	if (rt->rt6i_idev->dev == dev ||
+	    l3mdev_master_ifindex_rcu(rt->rt6i_idev->dev) == dev->ifindex ||
+	    (flags & XT_RPFILTER_LOOSE))
 		ret = true;
  out:
 	ip6_rt_put(rt);
-- 
2.21.GIT

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

[David Ahern]

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.

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

[David Ahern]

On 6/28/19 8:13 PM, linmiaohe wrote:
> 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;

that looks fine to me, but it is up to Pablo.

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

[linmiaohe]

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;