Commit 1d3fd8a1 authored Apr 27, 2019 by Stephen Suryaputra Committed by David S. Miller Apr 29, 2019

vrf: Use orig netdev to count Ip6InNoRoutes and a fresh route lookup when sending dest unreach



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@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Tested-by: David Ahern <dsahern@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ca2fe295

net/ipv6/route.c

+17 −6

Original line number	Diff line number	Diff line
		@@ -3668,23 +3668,34 @@ int ipv6_route_ioctl(struct net net, unsigned int cmd, void __user arg)

		static int ip6_pkt_drop(struct sk_buff *skb, u8 code, int ipstats_mib_noroutes)
		{
		int type;
		struct dst_entry *dst = skb_dst(skb);
		struct net *net = dev_net(dst->dev);
		struct inet6_dev *idev;
		int type;

		if (netif_is_l3_master(skb->dev) &&
		dst->dev == net->loopback_dev)
		idev = __in6_dev_get_safely(dev_get_by_index_rcu(net, IP6CB(skb)->iif));
		else
		idev = ip6_dst_idev(dst);

		switch (ipstats_mib_noroutes) {
		case IPSTATS_MIB_INNOROUTES:
		type = ipv6_addr_type(&ipv6_hdr(skb)->daddr);
		if (type == IPV6_ADDR_ANY) {
		IP6_INC_STATS(dev_net(dst->dev),
		__in6_dev_get_safely(skb->dev),
		IPSTATS_MIB_INADDRERRORS);
		IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
		break;
		}
		/* FALLTHROUGH */
		case IPSTATS_MIB_OUTNOROUTES:
		IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst),
		ipstats_mib_noroutes);
		IP6_INC_STATS(net, idev, ipstats_mib_noroutes);
		break;
		}

		/* Start over by dropping the dst for l3mdev case */
		if (netif_is_l3_master(skb->dev))
		skb_dst_drop(skb);

		icmpv6_send(skb, ICMPV6_DEST_UNREACH, code, 0);
		kfree_skb(skb);
		return 0;

Admin message