netdev - Re: VRF destination unreachable

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Date:   Tue, 27 Feb 2018 10:09:18 -0700
From:   David Ahern <dsahern@...il.com>
To:     Stephen Suryaputra <ssuryaextr@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: VRF destination unreachable

On 2/27/18 9:09 AM, Stephen Suryaputra wrote:
> Thanks David for confirming that this is unintended.
> 
> Given that, I think the fix isn't complete because when forwarding
> isn't enabled on the original incoming netdev, the ICMP shouldn't be
> generated. This diff fixes that case:
> 
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index a4f44d8..dc40a94 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -937,13 +937,20 @@ static int ip_error(struct sk_buff *skb)
>         struct net *net;
>         bool send;
>         int code;
> +       int in_dev_forward;

declarations are in reverse xmas tree order. ie., put this new one after
peer.


> 
>         /* IP on this device is disabled. */
>         if (!in_dev)
>                 goto out;
> 
>         net = dev_net(rt->dst.dev);
> -       if (!IN_DEV_FORWARD(in_dev)) {
> +       if (netif_is_l3_master(skb->dev)) {
> +               in_dev_forward = IN_DEV_FORWARD(
> +                       __in_dev_get_rcu(__dev_get_by_index(net,
> IPCB(skb)->iif)));
> +       } else {
> +               in_dev_forward = IN_DEV_FORWARD(in_dev);
> +       }

That looks correct.

> +       if (!in_dev_forward) {
>                 switch (rt->dst.error) {
>                 case EHOSTUNREACH:
>                         __IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
> 
> I can put a formal patch if you like.
> 

please do.