[PATCH net] net: vrf: Set L3MDEV OIF flag for outbound lookups

[PATCH net] net: vrf: Set L3MDEV OIF flag for outbound lookups

[Haon KIM]

The IPv4 and IPv6 outbound processing paths in the VRF driver
set the L3 master device index in the flow structure before
performing route lookups, but do not set
FLOWI_FLAG_L3MDEV_OIF.

Both the IPv4 and IPv6 outbound processing paths contain
the comment "needed to match OIF rule", indicating that
the L3 master device index is needed to match OIF rules.
However, FIB rule matching requires both
FLOWI_FLAG_L3MDEV_OIF and a matching flowi_l3mdev index
to match a rule specifying the VRF master as the output
interface.

The matching logic introduced by commit 2d300ce0b783
("net: fib_rules: Fix iif / oif matching on L3 master device")
requires FLOWI_FLAG_L3MDEV_OIF to be set for OIF rules to
match the VRF master. The existing outbound processing paths
set the L3 master device index directly, so
l3mdev_update_flow() does not set this flag.

Consequently, OIF rules specifying the VRF master may fail
to match these flows.

Set FLOWI_FLAG_L3MDEV_OIF in both outbound processing paths
so that FIB rules can correctly match the VRF master as the
output interface.

The issue was identified by code inspection. Runtime testing
has not been performed.

Fixes: 2d300ce0b783 ("net: fib_rules: Fix iif / oif matching on L3 master device")
Signed-off-by: Haon KIM <akrn112@naver.com>
---
 drivers/net/vrf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 79d433f49f80..f22ac91fefd4 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -432,6 +432,7 @@ static netdev_tx_t vrf_process_v6_outbound(struct sk_buff *skb,
 	fl6.flowlabel = ip6_flowinfo(iph);
 	fl6.flowi6_mark = skb->mark;
 	fl6.flowi6_proto = iph->nexthdr;
+	fl6.flowi6_flags = FLOWI_FLAG_L3MDEV_OIF;
 
 	dst = ip6_dst_lookup_flow(net, NULL, &fl6, NULL);
 	if (IS_ERR(dst) || dst == dst_null)
@@ -506,7 +507,7 @@ static netdev_tx_t vrf_process_v4_outbound(struct sk_buff *skb,
 	fl4.flowi4_l3mdev = vrf_dev->ifindex;
 	fl4.flowi4_iif = LOOPBACK_IFINDEX;
 	fl4.flowi4_dscp = ip4h_dscp(ip4h);
-	fl4.flowi4_flags = FLOWI_FLAG_ANYSRC;
+	fl4.flowi4_flags = FLOWI_FLAG_ANYSRC | FLOWI_FLAG_L3MDEV_OIF;
 	fl4.flowi4_proto = ip4h->protocol;
 	fl4.daddr = ip4h->daddr;
 	fl4.saddr = ip4h->saddr;
-- 
2.37.0