[PATCH net-next 3/3] net: ipgre: add skb drop reasons to gre_rcv()

[menglong8.dong@gmail.com]

From: Menglong Dong <imagedong@tencent.com>

Replace kfree_skb() used in gre_rcv() with kfree_skb_reason(). With
previous patch, we can tell that no tunnel device is found when
PACKET_NEXT is returned by erspan_rcv() or ipgre_rcv().

In this commit, following new drop reasons are added:

SKB_DROP_REASON_GRE_CSUM
SKB_DROP_REASON_GRE_NOTUNNEL

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Biao Jiang <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 include/linux/skbuff.h     |  2 ++
 include/trace/events/skb.h |  2 ++
 net/ipv4/ip_gre.c          | 28 ++++++++++++++++++----------
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 5edb704af5bb..4f5e58e717ee 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -448,6 +448,8 @@ enum skb_drop_reason {
 	SKB_DROP_REASON_GRE_NOHANDLER,	/* no handler found (version not
 					 * supported?)
 					 */
+	SKB_DROP_REASON_GRE_CSUM,	/* GRE csum error */
+	SKB_DROP_REASON_GRE_NOTUNNEL,	/* no tunnel device found */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index f2bcffdc4bae..e8f95c96cf9d 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -63,6 +63,8 @@
 	EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER)		\
 	EM(SKB_DROP_REASON_GRE_VERSION, GRE_VERSION)		\
 	EM(SKB_DROP_REASON_GRE_NOHANDLER, GRE_NOHANDLER)	\
+	EM(SKB_DROP_REASON_GRE_CSUM, GRE_CSUM)			\
+	EM(SKB_DROP_REASON_GRE_NOTUNNEL, GRE_NOTUNNEL)		\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index b1579d8374fd..b989239e4abc 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -421,9 +421,10 @@ static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
 
 static int gre_rcv(struct sk_buff *skb)
 {
+	enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	struct tnl_ptk_info tpi;
 	bool csum_err = false;
-	int hdr_len;
+	int hdr_len, ret;
 
 #ifdef CONFIG_NET_IPGRE_BROADCAST
 	if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
@@ -438,19 +439,26 @@ static int gre_rcv(struct sk_buff *skb)
 		goto drop;
 
 	if (unlikely(tpi.proto == htons(ETH_P_ERSPAN) ||
-		     tpi.proto == htons(ETH_P_ERSPAN2))) {
-		if (erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
-			return 0;
-		goto out;
-	}
+		     tpi.proto == htons(ETH_P_ERSPAN2)))
+		ret = erspan_rcv(skb, &tpi, hdr_len);
+	else
+		ret = ipgre_rcv(skb, &tpi, hdr_len);
 
-	if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
+	switch (ret) {
+	case PACKET_NEXT:
+		reason = SKB_DROP_REASON_GRE_NOTUNNEL;
+		break;
+	case PACKET_RCVD:
 		return 0;
-
-out:
+	case PACKET_REJECT:
+		reason = SKB_DROP_REASON_NOMEM;
+		break;
+	}
 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 drop:
-	kfree_skb(skb);
+	if (csum_err)
+		reason = SKB_DROP_REASON_GRE_CSUM;
+	kfree_skb_reason(skb, reason);
 	return 0;
 }
 
-- 
2.35.1