net/ipv6: Fix linklocal to global address with VRF

Example setup:
    host: ip -6 addr add dev eth1 2001:db8:104::4
           where eth1 is enslaved to a VRF

    switch: ip -6 ro add 2001:db8:104::4/128 dev br1
            where br1 only has an LLA

           ping6 2001:db8:104::4
           ssh   2001:db8:104::4

(NOTE: UDP works fine if the PKTINFO has the address set to the global
address and ifindex is set to the index of eth1 with a destination an
LLA).

For ICMP, icmp6_iif needs to be updated to check if skb->dev is an
L3 master. If it is then return the ifindex from rt6i_idev similar
to what is done for loopback.

For TCP, restore the original tcp_v6_iif definition which is needed in
most places and add a new tcp_v6_iif_l3_slave that considers the
l3_slave variability. This latter check is only needed for socket
lookups.

Fixes: 9ff74384600a ("net: vrf: Handle ipv6 multicast and link-local addresses")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 25116ec02087..cd3ecda9386a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -841,6 +841,11 @@ static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
  */
 static inline int tcp_v6_iif(const struct sk_buff *skb)
 {
+	return TCP_SKB_CB(skb)->header.h6.iif;
+}
+
+static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
+{
 	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
 
 	return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;