netdev - VRF destination unreachable

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Date:   Fri, 23 Feb 2018 12:49:17 -0500
From:   Stephen Suryaputra <ssuryaextr@...il.com>
To:     netdev@...r.kernel.org
Subject: VRF destination unreachable

Greetings,

We found that ICMP destination unreachable isn't sent if VRF
forwarding isn't configured, i.e.
/proc/sys/net/ipv4/conf/<vrf_net_device>/forwarding isn't set. The
relevant code is:

static int ip_error(struct sk_buff *skb)
{
...
        // in_dev is the vrf net_device
        if (!IN_DEV_FORWARD(in_dev)) {
                switch (rt->dst.error) {
                case EHOSTUNREACH:
                        __IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
                        break;

                case ENETUNREACH:
                        __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
                        break;
                }
                goto out;
        }
...
out:    kfree_skb(skb);
        return 0;
}

The question: is it intended to be set? The basic forwarding seems to
be working without. We do set it on the slave net devices.

Thank you,

Stephen.