selftests: forwarding: mirror_gre_nh: Unset rp_filter on host VRF

The mirrored packets arrive at $h3 encapsulated in GRE/IPv4, with IP
address from 192.0.2.128/28 network. However the interface is configured
as a member of 192.0.2.160/28 and there's no route directing traffic
from the former network through that interface. Correspondingly, the RP
filter on the VRF rejects it.

Therefore turn off the VRF's RP filter.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/mirror_gre_nh.sh

@@ -35,6 +35,8 @@ setup_prepare()
 	vrf_prepare
 	mirror_gre_topo_create
 
+	sysctl_set net.ipv4.conf.v$h3.rp_filter 0
+
 	ip address add dev $swp3 192.0.2.161/28
 	ip address add dev $h3 192.0.2.162/28
 	ip address add dev gt4 192.0.2.129/32
@@ -61,6 +63,8 @@ cleanup()
 	ip address del dev $h3 192.0.2.162/28
 	ip address del dev $swp3 192.0.2.161/28
 
+	sysctl_restore net.ipv4.conf.v$h3.rp_filter 0
+
 	mirror_gre_topo_destroy
 	vrf_cleanup