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net/tc: introduce TC_ACT_REINSERT.

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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>
This commit is contained in:
Paolo Abeni 2018-07-30 14:30:44 +02:00 committed by David S. Miller
parent 7fd4b288ea
commit cd11b16407
3 changed files with 36 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
include/net/pkt_cls.h
View file

@ -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 {

28
include/net/sch_generic.h
View file

@ -235,6 +235,12 @@ struct tcf_result {
u32 classid;
};
const struct tcf_proto *goto_tp;
/* used by the TC_ACT_REINSERT action */
struct {
bool ingress;
struct gnet_stats_queue *qstats;
};
};
};
@ -569,6 +575,15 @@ static inline void skb_reset_tc(struct sk_buff *skb)
#endif
}
static inline bool skb_is_tc_redirected(const struct sk_buff *skb)
{
#ifdef CONFIG_NET_CLS_ACT
return skb->tc_redirected;
#else
return false;
#endif
}
static inline bool skb_at_tc_ingress(const struct sk_buff *skb)
{
#ifdef CONFIG_NET_CLS_ACT
@ -1108,4 +1123,17 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
struct mini_Qdisc __rcu **p_miniq);
static inline void skb_tc_reinsert(struct sk_buff *skb, struct tcf_result *res)
{
struct gnet_stats_queue *stats = res->qstats;
int ret;
if (res->ingress)
ret = netif_receive_skb(skb);
else
ret = dev_queue_xmit(skb);
if (ret && stats)
qstats_overlimit_inc(res->qstats);
}
#endif

6
net/core/dev.c
View file

@ -4252,7 +4252,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
/* Reinjected packets coming from act_mirred or similar should
* not get XDP generic processing.
*/
if (skb_cloned(skb))
if (skb_cloned(skb) || skb_is_tc_redirected(skb))
return XDP_PASS;
/* XDP packets must be linear and must have sufficient headroom
@ -4602,6 +4602,10 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
__skb_push(skb, skb->mac_len);
skb_do_redirect(skb);
return NULL;
case TC_ACT_REINSERT:
/* this does not scrub the packet, and updates stats on error */
skb_tc_reinsert(skb, &cl_res);
return NULL;
default:
break;
}