ipv6: Set FLOWI_FLAG_KNOWN_NH at flowi6_flags

The neighbor look-up used to depend on the rt6i_gateway (if
there is a gateway) or the rt6i_dst (if it is a RTF_CACHE clone)
as the nexthop address.  Note that rt6i_dst is set to fl6->daddr
for the RTF_CACHE clone where fl6->daddr is the one used to do
the route look-up.

Now, we only create RTF_CACHE clone after encountering exception.
When doing the neighbor look-up with a route that is neither a gateway
nor a RTF_CACHE clone, the daddr in skb will be used as the nexthop.

In some cases, the daddr in skb is not the one used to do
the route look-up.  One example is in ip_vs_dr_xmit_v6() where the
real nexthop server address is different from the one in the skb.

This patch is going to follow the IPv4 approach and ask the
ip6_pol_route() callers to set the FLOWI_FLAG_KNOWN_NH properly.

In the next patch, ip6_pol_route() will honor the FLOWI_FLAG_KNOWN_NH
and create a RTF_CACHE clone.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Tested-by: Julian Anastasov <ja@ssi.bg>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 8072bd4139b7..484a5c144073 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -865,6 +865,9 @@ static int rawv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		fl6.flowi6_oif = np->ucast_oif;
 	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 
+	if (inet->hdrincl)
+		fl6.flowi6_flags |= FLOWI_FLAG_KNOWN_NH;
+
 	dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
 	if (IS_ERR(dst)) {
 		err = PTR_ERR(dst);