[PATCH 5.16 100/227] selftests: netfilter: disable rp_filter on router

Greg Kroah-Hartman
2022-02-21T09:58:45Z

From: Hangbin Liu <liuhangbin@gmail.com>

commit bbe4c0896d25009a7c86285d2ab024eed4374eea upstream.

Some distros may enable rp_filter by default. After ns1 change addr to
10.0.2.99 and set default router to 10.0.2.1, while the connected router
address is still 10.0.1.1. The router will not reply the arp request
from ns1. Fix it by setting the router's veth0 rp_filter to 0.

Before the fix:
# ./nft_fib.sh
PASS: fib expression did not cause unwanted packet drops
Netns nsrouter-HQkDORO2 fib counter doesn't match expected packet count of 1 for 1.1.1.1
table inet filter {
chain prerouting {
type filter hook prerouting priority filter; policy accept;
ip daddr 1.1.1.1 fib saddr . iif oif missing counter packets 0 bytes 0 drop
ip6 daddr 1c3::c01d fib saddr . iif oif missing counter packets 0 bytes 0 drop
}
}

After the fix:
# ./nft_fib.sh
PASS: fib expression did not cause unwanted packet drops
PASS: fib expression did drop packets for 1.1.1.1
PASS: fib expression did drop packets for 1c3::c01d

Fixes: 82944421243e ("selftests: netfilter: add fib test case")
Signed-off-by: Yi Chen <yiche@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/netfilter/nft_fib.sh | 1 +
1 file changed, 1 insertion(+)

--- a/tools/testing/selftests/netfilter/nft_fib.sh
+++ b/tools/testing/selftests/netfilter/nft_fib.sh
@@ -174,6 +174,7 @@ test_ping() {
ip netns exec ${nsrouter} sysctl net.ipv6.conf.all.forwarding=1 > /dev/null
ip netns exec ${nsrouter} sysctl net.ipv4.conf.veth0.forwarding=1 > /dev/null
ip netns exec ${nsrouter} sysctl net.ipv4.conf.veth1.forwarding=1 > /dev/null
+ip netns exec ${nsrouter} sysctl net.ipv4.conf.veth0.rp_filter=0 > /dev/null

sleep 3