selftests: netfilter: ipvs.sh: Explicity disable rp_filter on interface tunl0

JIRA: https://issues.redhat.com/browse/RHEL-115594

commit 8b4a1a4
Author: Yi Chen <yiche@redhat.com>
Date:   Thu Jul 24 16:06:53 2025 +0800

    selftests: netfilter: ipvs.sh: Explicity disable rp_filter on interface tunl0

    Although setup_ns() set net.ipv4.conf.default.rp_filter=0,
    loading certain module such as ipip will automatically create a tunl0 interface
    in all netns including new created ones. In the script, this is before than
    default.rp_filter=0 applied, as a result tunl0.rp_filter remains set to 1
    which causes the test report FAIL when ipip module is preloaded.

    Before fix:
    Testing DR mode...
    Testing NAT mode...
    Testing Tunnel mode...
    ipvs.sh: FAIL

    After fix:
    Testing DR mode...
    Testing NAT mode...
    Testing Tunnel mode...
    ipvs.sh: PASS

    Fixes: 7c8b89e ("selftests: netfilter: remove rp_filter configuration")
    Signed-off-by: Yi Chen <yiche@redhat.com>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

tools/testing/selftests/net/netfilter/ipvs.sh

@@ -151,7 +151,7 @@ test_nat() {
 test_tun() {
 	ip netns exec "${ns0}" ip route add "${vip_v4}" via "${gip_v4}" dev br0
 
-	ip netns exec "${ns1}" modprobe -q ipip
+	modprobe -q ipip
 	ip netns exec "${ns1}" ip link set tunl0 up
 	ip netns exec "${ns1}" sysctl -qw net.ipv4.ip_forward=0
 	ip netns exec "${ns1}" sysctl -qw net.ipv4.conf.all.send_redirects=0
@@ -160,10 +160,10 @@ test_tun() {
 	ip netns exec "${ns1}" ipvsadm -a -i -t "${vip_v4}:${port}" -r ${rip_v4}:${port}
 	ip netns exec "${ns1}" ip addr add ${vip_v4}/32 dev lo:1
 
-	ip netns exec "${ns2}" modprobe -q ipip
 	ip netns exec "${ns2}" ip link set tunl0 up
 	ip netns exec "${ns2}" sysctl -qw net.ipv4.conf.all.arp_ignore=1
 	ip netns exec "${ns2}" sysctl -qw net.ipv4.conf.all.arp_announce=2
+	ip netns exec "${ns2}" sysctl -qw net.ipv4.conf.tunl0.rp_filter=0
 	ip netns exec "${ns2}" ip addr add "${vip_v4}/32" dev lo:1
 
 	test_service