net: vrf: Flip IPv6 output path from FIB lookup hook to out hook

Flip the IPv6 output path to use the l3mdev tx out hook. The VRF dst
is not returned on the first FIB lookup. Instead, the dst on the
skb is switched at the beginning of the IPv6 output processing to
send the packet to the VRF driver on xmit.

Link scope addresses (linklocal and multicast) need special handling:
specifically the oif the flow struct can not be changed because we
want the lookup tied to the enslaved interface. ie., the source address
and the returned route MUST point to the interface scope passed in.
Convert the existing vrf_get_rt6_dst to handle only link scope addresses.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 2c681113c055..87e0a01ce744 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1188,12 +1188,15 @@ static struct rt6_info *ip6_pol_route_output(struct net *net, struct fib6_table
 struct dst_entry *ip6_route_output_flags(struct net *net, const struct sock *sk,
 					 struct flowi6 *fl6, int flags)
 {
-	struct dst_entry *dst;
 	bool any_src;
 
-	dst = l3mdev_get_rt6_dst(net, fl6);
-	if (dst)
-		return dst;
+	if (rt6_need_strict(&fl6->daddr)) {
+		struct dst_entry *dst;
+
+		dst = l3mdev_link_scope_lookup(net, fl6);
+		if (dst)
+			return dst;
+	}
 
 	fl6->flowi6_iif = LOOPBACK_IFINDEX;