netdev - Re: [PATCH net,v3] vrf: Use orig netdev to count Ip6InNoRoutes and a fresh route lookup when sending dest unreach

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Date:   Sat, 27 Apr 2019 11:27:49 -0600
From:   David Ahern <dsahern@...il.com>
To:     Stephen Suryaputra <ssuryaextr@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net,v3] vrf: Use orig netdev to count Ip6InNoRoutes and a
 fresh route lookup when sending dest unreach

On 4/27/19 7:14 AM, Stephen Suryaputra wrote:
> When there is no route to an IPv6 dest addr, skb_dst(skb) points
> to loopback dev in the case of that the IP6CB(skb)->iif is
> enslaved to a vrf. This causes Ip6InNoRoutes to be incremented on the
> loopback dev. This also causes the lookup to fail on icmpv6_send() and
> the dest unreachable to not sent and Ip6OutNoRoutes gets incremented on
> the loopback dev.
> 
> To reproduce:
> * Gateway configuration:
>         ip link add dev vrf_258 type vrf table 258
>         ip link set dev enp0s9 master vrf_258
>         ip addr add 66:1/64 dev enp0s9
>         ip -6 route add unreachable default metric 8192 table 258
>         sysctl -w net.ipv6.conf.all.forwarding=1
>         sysctl -w net.ipv6.conf.enp0s9.forwarding=1
> * Sender configuration:
>         ip addr add 66::2/64 dev enp0s9
>         ip -6 route add default via 66::1
> and ping 67::1 for example from the sender.
> 
> Fix this by counting on the original netdev and reset the skb dst to
> force a fresh lookup.
> 
> v2: Fix typo of destination address in the repro steps.
> v3: Simplify the loopback check (per David Ahern) and use reverse
>     Christmas tree format (per David Miller).
> 
> Signed-off-by: Stephen Suryaputra <ssuryaextr@...il.com>
> Reviewed-by: David Ahern <dsahern@...il.com>
> Tested-by: David Ahern <dsahern@...il.com>
> ---
>  net/ipv6/route.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@...il.com>