[PATCH 5.13 071/151] net: sched: act_mirred: Reset ct info when mirror/redirect skb

Greg Kroah-Hartman
2021-08-16T13:25:15Z

From: Hangbin Liu <liuhangbin@gmail.com>

[ Upstream commit d09c548dbf3b31cb07bba562e0f452edfa01efe3 ]

When mirror/redirect a skb to a different port, the ct info should be reset
for reclassification. Or the pkts will match unexpected rules. For example,
with following topology and commands:

-----------
|
veth0 -+-------
|
veth1 -+-------
|
------------

tc qdisc add dev veth0 clsact
# The same with "action mirred egress mirror dev veth1" or "action mirred ingress redirect dev veth1"
tc filter add dev veth0 egress chain 1 protocol ip flower ct_state +trk action mirred ingress mirror dev veth1
tc filter add dev veth0 egress chain 0 protocol ip flower ct_state -inv action ct commit action goto chain 1
tc qdisc add dev veth1 clsact
tc filter add dev veth1 ingress chain 0 protocol ip flower ct_state +trk action drop

ping <remove ip via veth0> &
tc -s filter show dev veth1 ingress

With command 'tc -s filter show', we can find the pkts were dropped on
veth1.

Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/act_mirred.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 7153c67f641e..2ef4cd2c848b 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -273,6 +273,9 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
goto out;
}

+ /* All mirred/redirected skbs should clear previous ct info */
+ nf_reset_ct(skb2);
+
want_ingress = tcf_mirred_act_wants_ingress(m_eaction);

expects_nh = want_ingress || !m_mac_header_xmit;
--
2.30.2