[PATCH 5.8 004/633] ipv4: Restore flowi4_oif update before call to xfrm_lookup_route

[Greg Kroah-Hartman]

From: David Ahern <dsah...@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 <tob...@strongswan.org>
Signed-off-by: David Ahern <dsah...@kernel.org>
Signed-off-by: Jakub Kicinski <k...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/ipv4/route.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2764,10 +2764,12 @@ 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;
 }