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>