[PATCH 5.15 157/279] net: sched: act_mirred: drop dst for the direction from egress to ingress

Greg Kroah-Hartman
2021-11-24T13:57:36Z

From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit f799ada6bf2397c351220088b9b0980125c77280 ]

Without dropping dst, the packets sent from local mirred/redirected
to ingress will may still use the old dst. ip_rcv() will drop it as
the old dst is for output and its .input is dst_discard.

This patch is to fix by also dropping dst for those packets that are
mirred or redirected from egress to ingress in act_mirred.

Note that we don't drop it for the direction change from ingress to
egress, as on which there might be a user case attaching a metadata
dst by act_tunnel_key that would be used later.

Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Cong Wang <cong.wang@bytedance.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/act_mirred.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index d64b0eeccbe4d..efc963ab995a3 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -19,6 +19,7 @@
#include <linux/if_arp.h>
#include <net/net_namespace.h>
#include <net/netlink.h>
+#include <net/dst.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <linux/tc_act/tc_mirred.h>
@@ -228,6 +229,7 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
bool want_ingress;
bool is_redirect;
bool expects_nh;
+ bool at_ingress;
int m_eaction;
int mac_len;
bool at_nh;
@@ -263,7 +265,8 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
* ingress - that covers the TC S/W datapath.
*/
is_redirect = tcf_mirred_is_act_redirect(m_eaction);
- use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
+ at_ingress = skb_at_tc_ingress(skb);
+ use_reinsert = at_ingress && is_redirect &&
tcf_mirred_can_reinsert(retval);
if (!use_reinsert) {
skb2 = skb_clone(skb, GFP_ATOMIC);
@@ -271,10 +274,12 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
goto out;
}

+ want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
+
/* All mirred/redirected skbs should clear previous ct info */
nf_reset_ct(skb2);
-
- want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
+ if (want_ingress && !at_ingress) /* drop dst for egress -> ingress */
+ skb_dst_drop(skb2);

expects_nh = want_ingress || !m_mac_header_xmit;
at_nh = skb->data == skb_network_header(skb);
--
2.33.0