[PATCHv2 net] ipvlan: fix bound dev checking for IPv6 l3s mode

[Hangbin Liu <liuhangbin@gmail.com>]

The commit 59a0b022aa24 ("ipvlan: Make skb->skb_iif track skb->dev for l3s
mode") fixed ipvlan bonded dev checking by updating skb skb_iif. This fix
works for IPv4, as in raw_v4_input() the dif is from inet_iif(skb), which
is skb->skb_iif when there is no route.

But for IPv6, the fix is not enough, because in ipv6_raw_deliver() ->
raw_v6_match(), the dif is inet6_iif(skb), which is returns IP6CB(skb)->iif
instead of skb->skb_iif if it's not a l3_slave. To fix the IPv6 part
issue. Let's set IP6CB(skb)->iif to correct ifindex.

BTW, ipvlan handles NS/NA specifically. Since it works fine, I will not
reset IP6CB(skb)->iif when addr->atype is IPVL_ICMPV6.

Fixes: c675e06a98a4 ("ipvlan: decouple l3s mode dependencies from other modes")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2196710
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
v2: set IP6CB(skb)->iif instead of setting IP6SKB_L3SLAVE flag
---
 drivers/net/ipvlan/ipvlan_l3s.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ipvlan/ipvlan_l3s.c b/drivers/net/ipvlan/ipvlan_l3s.c
index 71712ea25403..d5b05e803219 100644
--- a/drivers/net/ipvlan/ipvlan_l3s.c
+++ b/drivers/net/ipvlan/ipvlan_l3s.c
@@ -102,6 +102,10 @@ static unsigned int ipvlan_nf_input(void *priv, struct sk_buff *skb,
 
 	skb->dev = addr->master->dev;
 	skb->skb_iif = skb->dev->ifindex;
+#if IS_ENABLED(CONFIG_IPV6)
+	if (addr->atype == IPVL_IPV6)
+		IP6CB(skb)->iif = skb->dev->ifindex;
+#endif
 	len = skb->len + ETH_HLEN;
 	ipvlan_count_rx(addr->master, len, true, false);
 out:
-- 
2.38.1