[PATCH 5.9 004/757] ipv4: Restore flowi4_oif update before call to xfrm_lookup_route

Greg Kroah-Hartman
2020-10-27T15:58:51Z

From: David Ahern <dsahern@kernel.org>

[ Upstream commit 874fb9e2ca949b443cc419a4f2227cafd4381d39 ]

Tobias reported regressions in IPsec tests following the patch
referenced by the Fixes tag below. The root cause is dropping the
reset of the flowi4_oif after the fib_lookup. Apparently it is
needed for xfrm cases, so restore the oif update to ip_route_output_flow
right before the call to xfrm_lookup_route.

Fixes: 2fbc6e89b2f1 ("ipv4: Update exception handling for multipath routes via same device")
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/route.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2769,10 +2769,12 @@ struct rtable *ip_route_output_flow(stru
if (IS_ERR(rt))
return rt;

- if (flp4->flowi4_proto)
+ if (flp4->flowi4_proto) {
+ flp4->flowi4_oif = rt->dst.dev->ifindex;
rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
flowi4_to_flowi(flp4),
sk, 0);
+ }

return rt;
}