This change makes it possible to identify SKBs that have been redirected
by TC-BPF (cls_act). This is needed for a number of cases.
(1) For collaborating with driver ifb net_devices.
(2) For avoiding starting generic-XDP prog on TC ingress redirect.
It is most important to fix XDP case(2), because this can break userspace
when a driver gets support for native-XDP. Imagine userspace loads XDP
prog on eth0, which fallback to generic-XDP, and it process TC-redirected
packets. When kernel is updated with native-XDP support for eth0, then the
program no-longer see the TC-redirected packets. Therefore it is important
to keep the order intact; that XDP runs before TC-BPF.
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
net/core/dev.c | 2 ++
net/sched/Kconfig | 1 +
2 files changed, 3 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index 6ceb6412ee97..26b40f8005ae 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3872,6 +3872,7 @@ sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
return NULL;
case TC_ACT_REDIRECT:
/* No need to push/pop skb's mac_header here on egress! */
+ skb_set_redirected(skb, false);
skb_do_redirect(skb);
*ret = NET_XMIT_SUCCESS;
return NULL;
@@ -4963,6 +4964,7 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
* redirecting to another netdev
*/
__skb_push(skb, skb->mac_len);
+ skb_set_redirected(skb, true);
if (skb_do_redirect(skb) == -EAGAIN) {
__skb_pull(skb, skb->mac_len);
*another = true;
diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index a3b37d88800e..a1bbaa8fd054 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -384,6 +384,7 @@ config NET_SCH_INGRESS
depends on NET_CLS_ACT
select NET_INGRESS
select NET_EGRESS
+ select NET_REDIRECT
help
Say Y here if you want to use classifiers for incoming and/or outgoing
packets. This qdisc doesn't do anything else besides running classifiers,
