From: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
Currently rp_filter tests in fib_tests.sh:fib_rp_filter_test() are
failing. ping sockets are bound to dummy1 using the "-I" option
(SO_BINDTODEVICE), but socket lookup is failing when receiving ping
replies, since the routing table thinks they belong to dummy0.
For example, suppose ping is using a SOCK_RAW socket for ICMP messages.
When receiving ping replies, in __raw_v4_lookup(), sk->sk_bound_dev_if
is 3 (dummy1), but dif (skb_rtable(skb)->rt_iif) says 2 (dummy0), so the
raw_sk_bound_dev_eq() check fails. Similar things happen in
ping_lookup() for SOCK_DGRAM sockets.
Fix the tests by binding to dummy0 instead. Redirect ping requests to
dummy1 before redirecting them again to lo, so that sk->sk_bound_dev_if
agrees with our routing table.
These tests used to pass due to a bug [1] in iputils, where "ping -I"
actually did not bind ICMP message sockets to device. The bug has been
fixed by iputils commit f455fee41c07 ("ping: also bind the ICMP socket
to the specific device") in 2016, which is why our rp_filter tests
started to fail. See [2] .
Tested with ping from iputils 20210722-41-gf9fb573:
$ ./fib_tests.sh -t rp_filter
IPv4 rp_filter tests
TEST: rp_filter passes local packets [ OK ]
TEST: rp_filter passes loopback packets [ OK ]
[1] https://github.com/iputils/iputils/issues/55
[2] https://github.com/iputils/iputils/commit/f455fee41c077d4b700a473b2f5b3487b8febc1d
Reported-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
Fixes: adb701d6cfa4 ("selftests: add a test case for rp_filter")
Reviewed-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Signed-off-by: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
---
Change in v2:
- s/SOCK_ICMP/SOCK_DGRAM/ in commit message
tools/testing/selftests/net/fib_tests.sh | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
index 5abe92d55b69..b8bceae00f8e 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -453,15 +453,19 @@ fib_rp_filter_test()
$NS_EXEC sysctl -qw net.ipv4.conf.all.accept_local=1
$NS_EXEC sysctl -qw net.ipv4.conf.all.route_localnet=1
+ $NS_EXEC tc qd add dev dummy0 parent root handle 1: fq_codel
+ $NS_EXEC tc filter add dev dummy0 parent 1: protocol arp basic action mirred egress redirect dev dummy1
+ $NS_EXEC tc filter add dev dummy0 parent 1: protocol ip basic action mirred egress redirect dev dummy1
+
$NS_EXEC tc qd add dev dummy1 parent root handle 1: fq_codel
$NS_EXEC tc filter add dev dummy1 parent 1: protocol arp basic action mirred egress redirect dev lo
$NS_EXEC tc filter add dev dummy1 parent 1: protocol ip basic action mirred egress redirect dev lo
set +e
- run_cmd "ip netns exec ns1 ping -I dummy1 -w1 -c1 198.51.100.1"
+ run_cmd "ip netns exec ns1 ping -I dummy0 -w1 -c1 198.51.100.1"
log_test $? 0 "rp_filter passes local packets"
- run_cmd "ip netns exec ns1 ping -I dummy1 -w1 -c1 127.0.0.1"
+ run_cmd "ip netns exec ns1 ping -I dummy0 -w1 -c1 127.0.0.1"
log_test $? 0 "rp_filter passes loopback packets"
cleanup
--
2.20.1
