net/tc: introduce TC_ACT_REINSERT.

This is similar TC_ACT_REDIRECT, but with a slightly different
semantic:
- on ingress the mirred skbs are passed to the target device
network stack without any additional check not scrubbing.
- the rcu-protected stats provided via the tcf_result struct
  are updated on error conditions.

This new tcfa_action value is not exposed to the user-space
and can be used only internally by clsact.

v1 -> v2: do not touch TC_ACT_REDIRECT code path, introduce
 a new action type instead
v2 -> v3:
 - rename the new action value TC_ACT_REINJECT, update the
   helper accordingly
 - take care of uncloned reinjected packets in XDP generic
   hook
v3 -> v4:
 - renamed again the new action value (JiriP)
v4 -> v5:
 - fix build error with !NET_CLS_ACT (kbuild bot)

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index 6d02f31abba8..22bfc3a13c25 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -7,6 +7,9 @@
 #include <net/sch_generic.h>
 #include <net/act_api.h>
 
+/* TC action not accessible from user space */
+#define TC_ACT_REINSERT		(TC_ACT_VALUE_MAX + 1)
+
 /* Basic packet classifier frontend definitions. */
 
 struct tcf_walker {