Commit 39d08b91 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Jakub Kicinski
Browse files

net, sched: Add tcf_set_drop_reason for {__,}tcf_classify 



Add an initial user for the newly added tcf_set_drop_reason() helper to set the
drop reason for internal errors leading to TC_ACT_SHOT inside {__,}tcf_classify().

Right now this only adds a very basic SKB_DROP_REASON_TC_ERROR as a generic
fallback indicator to mark drop locations. Where needed, such locations can be
converted to more specific codes, for example, when hitting the reclassification
limit, etc.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Victor Nogueira <victor@mojatatu.com>
Link: https://lore.kernel.org/r/20231009092655.22025-2-daniel@iogearbox.net


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 54a59aed

include/net/dropreason-core.h

+3 −0
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ 
	FN(IPV6_NDISC_BAD_OPTIONS)	\

	FN(IPV6_NDISC_NS_OTHERHOST)	\

	FN(QUEUE_PURGE)			\

	FN(TC_ERROR)			\

	FNe(MAX)



/**
@@ -345,6 +346,8 @@ enum skb_drop_reason { 
	SKB_DROP_REASON_IPV6_NDISC_NS_OTHERHOST,

	/** @SKB_DROP_REASON_QUEUE_PURGE: bulk free. */

	SKB_DROP_REASON_QUEUE_PURGE,

	/** @SKB_DROP_REASON_TC_ERROR: generic internal tc error. */

	SKB_DROP_REASON_TC_ERROR,

	/**

	 * @SKB_DROP_REASON_MAX: the maximum of core drop reasons, which

	 * shouldn't be used as a real 'reason' - only for tracing code gen

net/sched/cls_api.c

+20 −6
Original line number Diff line number Diff line
@@ -1681,12 +1681,16 @@ static inline int __tcf_classify(struct sk_buff *skb, 
			 * time we got here with a cookie from hardware.

			 */

			if (unlikely(n->tp != tp || n->tp->chain != n->chain ||

				     !tp->ops->get_exts))

				     !tp->ops->get_exts)) {

				tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

				return TC_ACT_SHOT;

			}



			exts = tp->ops->get_exts(tp, n->handle);

			if (unlikely(!exts || n->exts != exts))

			if (unlikely(!exts || n->exts != exts)) {

				tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

				return TC_ACT_SHOT;

			}



			n = NULL;

			err = tcf_exts_exec_ex(skb, exts, act_index, res);
@@ -1712,8 +1716,10 @@ static inline int __tcf_classify(struct sk_buff *skb, 
			return err;

	}



	if (unlikely(n))

	if (unlikely(n)) {

		tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

		return TC_ACT_SHOT;

	}



	return TC_ACT_UNSPEC; /* signal: continue lookup */

#ifdef CONFIG_NET_CLS_ACT
@@ -1723,6 +1729,7 @@ static inline int __tcf_classify(struct sk_buff *skb, 
				       tp->chain->block->index,

				       tp->prio & 0xffff,

				       ntohs(tp->protocol));

		tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

		return TC_ACT_SHOT;

	}
@@ -1759,8 +1766,10 @@ int tcf_classify(struct sk_buff *skb, 
			if (ext->act_miss) {

				n = tcf_exts_miss_cookie_lookup(ext->act_miss_cookie,

								&act_index);

				if (!n)

				if (!n) {

					tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

					return TC_ACT_SHOT;

				}



				chain = n->chain_index;

			} else {
@@ -1768,8 +1777,10 @@ int tcf_classify(struct sk_buff *skb, 
			}



			fchain = tcf_chain_lookup_rcu(block, chain);

			if (!fchain)

			if (!fchain) {

				tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

				return TC_ACT_SHOT;

			}



			/* Consume, so cloned/redirect skbs won't inherit ext */

			skb_ext_del(skb, TC_SKB_EXT);
@@ -1788,8 +1799,11 @@ int tcf_classify(struct sk_buff *skb, 
			struct tc_skb_cb *cb = tc_skb_cb(skb);



			ext = tc_skb_ext_alloc(skb);

			if (WARN_ON_ONCE(!ext))

			if (WARN_ON_ONCE(!ext)) {

				tcf_set_drop_reason(res, SKB_DROP_REASON_TC_ERROR);

				return TC_ACT_SHOT;

			}



			ext->chain = last_executed_chain;

			ext->mru = cb->mru;

			ext->post_ct = cb->post_ct;