linux-kernel - [PATCH net-next 1/3] net: gre_demux: add skb drop reasons to gre

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Date:   Mon, 14 Mar 2022 21:33:10 +0800
From:   menglong8.dong@...il.com
To:     dsahern@...nel.org, kuba@...nel.org
Cc:     rostedt@...dmis.org, mingo@...hat.com, xeb@...l.ru,
        davem@...emloft.net, yoshfuji@...ux-ipv6.org,
        imagedong@...cent.com, edumazet@...gle.com, kafai@...com,
        talalahmad@...gle.com, keescook@...omium.org, alobakin@...me,
        flyingpeng@...cent.com, mengensun@...cent.com,
        dongli.zhang@...cle.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Biao Jiang <benbjiang@...cent.com>
Subject: [PATCH net-next 1/3] net: gre_demux: add skb drop reasons to gre_rcv()

From: Menglong Dong <imagedong@...cent.com>

Replace kfree_skb() used in gre_rcv() with kfree_skb_reason(). Following
new drop reasons are added:

SKB_DROP_REASON_GRE_VERSION
SKB_DROP_REASON_GRE_NOHANDLER

Reviewed-by: Hao Peng <flyingpeng@...cent.com>
Reviewed-by: Biao Jiang <benbjiang@...cent.com>
Signed-off-by: Menglong Dong <imagedong@...cent.com>
---
 include/linux/skbuff.h     |  4 ++++
 include/trace/events/skb.h |  2 ++
 net/ipv4/gre_demux.c       | 12 +++++++++---
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 26538ceb4b01..5edb704af5bb 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -444,6 +444,10 @@ enum skb_drop_reason {
 	SKB_DROP_REASON_TAP_TXFILTER,	/* dropped by tx filter implemented
 					 * at tun/tap, e.g., check_filter()
 					 */
+	SKB_DROP_REASON_GRE_VERSION,	/* GRE version not supported */
+	SKB_DROP_REASON_GRE_NOHANDLER,	/* no handler found (version not
+					 * supported?)
+					 */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index e1670e1e4934..f2bcffdc4bae 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -61,6 +61,8 @@
 	EM(SKB_DROP_REASON_HDR_TRUNC, HDR_TRUNC)		\
 	EM(SKB_DROP_REASON_TAP_FILTER, TAP_FILTER)		\
 	EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER)		\
+	EM(SKB_DROP_REASON_GRE_VERSION, GRE_VERSION)		\
+	EM(SKB_DROP_REASON_GRE_NOHANDLER, GRE_NOHANDLER)	\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index cbb2b4bb0dfa..066cbaadc52a 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -146,20 +146,26 @@ EXPORT_SYMBOL(gre_parse_header);
 static int gre_rcv(struct sk_buff *skb)
 {
 	const struct gre_protocol *proto;
+	enum skb_drop_reason reason;
 	u8 ver;
 	int ret;
 
+	reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	if (!pskb_may_pull(skb, 12))
 		goto drop;
 
 	ver = skb->data[1]&0x7f;
-	if (ver >= GREPROTO_MAX)
+	if (ver >= GREPROTO_MAX) {
+		reason = SKB_DROP_REASON_GRE_VERSION;
 		goto drop;
+	}
 
 	rcu_read_lock();
 	proto = rcu_dereference(gre_proto[ver]);
-	if (!proto || !proto->handler)
+	if (!proto || !proto->handler) {
+		reason = SKB_DROP_REASON_GRE_NOHANDLER;
 		goto drop_unlock;
+	}
 	ret = proto->handler(skb);
 	rcu_read_unlock();
 	return ret;
@@ -167,7 +173,7 @@ static int gre_rcv(struct sk_buff *skb)
 drop_unlock:
 	rcu_read_unlock();
 drop:
-	kfree_skb(skb);
+	kfree_skb_reason(skb, reason);
 	return NET_RX_DROP;
 }
 
-- 
2.35.1