From: David Ahern <dsahern@gmail•com>
To: Stephen Suryaputra <ssuryaextr@gmail•com>
Cc: netdev@vger•kernel.org
Subject: Re: ip rule iif oif and vrf
Date: Thu, 24 Sep 2020 08:41:54 -0600 [thread overview]
Message-ID: <97ce9942-2115-ed3a-75ea-8b58aa799ceb@gmail.com> (raw)
In-Reply-To: <20200924134845.GA3688@ICIPI.localdomain>
On 9/24/20 7:48 AM, Stephen Suryaputra wrote:
> On Wed, Sep 23, 2020 at 07:47:16PM -0600, David Ahern wrote:
>> If I remove the fib rules and add VRF route leaking from core to tenant
>> it works. Why is that not an option? Overlapping tenant addresses?
>
> Exactly.
>
>> One thought to get around it is adding support for a new FIB rule type
>> -- say l3mdev_port. That rule can look at the real ingress device which
>> is saved in the skb->cb as IPCB(skb)->iif.
>
> OK. Just to ensure that the existing ip rule behavior isn't considered a
> bug.
>
> We have multiple options on the table right now. One that can be done
> without writing any code is to use an nft prerouting rule to mark
> the packet with iif equals the tunnel and use ip rule fwmark to lookup
> the right table.
>
> ip netns exec r0 nft add table ip c2t
> ip netns exec r0 nft add chain ip c2t prerouting '{ type filter hook prerouting priority 0; policy accept; }'
> ip netns exec r0 nft rule ip c2t prerouting iif gre01 mark set 101 counter
> ip netns exec r0 ip rule add fwmark 101 table 10 pref 999
>
> ip netns exec r1 nft add table ip c2t
> ip netns exec r1 nft add chain ip c2t prerouting '{ type filter hook prerouting priority 0; policy accept; }'
> ip netns exec r1 nft rule ip c2t prerouting iif gre10 mark set 101 counter
> ip netns exec r1 ip rule add fwmark 101 table 10 pref 999
>
> But this doesn't seem to work on my Ubuntu VM with the namespaces
> script, i.e. pinging from h0 to h1. The packet doesn't egress r1_v11. It
> does work on our target, based on 4.14 kernel.
add debugs to net/core/fib_rules.c, fib_rule_match() to see if
flowi_mark is getting set properly. There could easily be places that
are missed. Or if it works on one setup, but not another compare sysctl
settings for net.core and net.ipv4
>
> We also notice though in on the target platform that the ip rule fwmark
> doesn't seem to change the skb->dev to the vrf of the lookup table.
not following that statement. fwmark should be marking the skb, not
changing the skb->dev.
> E.g., ping from 10.0.0.1 to 11.0.0.1. With net.ipv4.fwmark_reflect set,
> the reply is generated but the originating ping application doesn't get
> the packet. I suspect it is caused by the socket is bound to the tenant
> vrf. I haven't been able to repro this because of the problem with the
> nft approach above.
>
> Thanks,
> Stephen.
>
next prev parent reply other threads:[~2020-09-24 14:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 13:11 ip rule iif oif and vrf Stephen Suryaputra
2020-09-22 15:39 ` David Ahern
2020-09-23 23:50 ` Stephen Suryaputra
2020-09-24 1:47 ` David Ahern
2020-09-24 13:48 ` Stephen Suryaputra
2020-09-24 14:41 ` David Ahern [this message]
2020-10-01 2:23 ` Stephen Suryaputra
2020-10-12 0:06 ` David Ahern
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