netdev - Re: VRF leaking doesn't work

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Message-ID: <CADbyt6542624xAVzWXM6KEfk=zAOmB_SHbN=nzC_oib_+eXB1Q@mail.gmail.com>
Date:   Mon, 15 Mar 2021 18:10:34 +0100
From:   Greesha Mikhalkin <grigoriymikhalkin@...il.com>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: VRF leaking doesn't work

> That's the way the source address selection works -- it takes the fib
> lookup result and finds the best source address match for it.
>
> Try adding 'src a.b.c.d' to the leaked route. e.g.,
>     ip ro add 172.16.1.0/24 dev red vrf blue src 172.16.2.1
>
> where red and blue are VRFs, 172.16.2.1 is a valid source address in VRF
> blue and VRF red has the reverse route installed.

Tried to do that. Added reverse route to vrf red like that:
    ip ro add vrf red 172.16.2.1/32 dev blue

172.16.2.1 is selected as source address when i ping. But now, when i
look at `tcpdump icmp` i only see requests:
    172.16.2.1 > 172.16.1.3: ICMP echo request, id 9, seq 10, length 64

And no replies and anything else. If i look into tcpdump on machine
that's pinged -- it doesn't receive anything.

So it looks like it's not using nexthops from vrf red in that case.
Maybe it has something to do with how address is setup. In routing
table it looks like:
    local 172.16.2.1 dev vlanblue proto kernel scope host src 172.16.2.1