netdev - [PATCH net-next 2/6] net: ipv4: use kfree_skb_reason() in ip_rcv

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Date:   Mon, 24 Jan 2022 21:15:34 +0800
From:   menglong8.dong@...il.com
To:     kuba@...nel.org
Cc:     rostedt@...dmis.org, mingo@...hat.com, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org, pablo@...filter.org,
        kadlec@...filter.org, fw@...len.de, imagedong@...cent.com,
        edumazet@...gle.com, alobakin@...me, paulb@...dia.com,
        pabeni@...hat.com, talalahmad@...gle.com, haokexin@...il.com,
        keescook@...omium.org, memxor@...il.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        cong.wang@...edance.com
Subject: [PATCH net-next 2/6] net: ipv4: use kfree_skb_reason() in ip_rcv_core()

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

Replace kfree_skb() with kfree_skb_reason() in ip_rcv_core(). Three new
drop reasons are introduced:

SKB_DROP_REASON_OTHERHOST
SKB_DROP_REASON_IP_CSUM
SKB_DROP_REASON_IP_INHDR

Signed-off-by: Menglong Dong <imagedong@...cent.com>
---
 include/linux/skbuff.h     |  3 +++
 include/trace/events/skb.h |  3 +++
 net/ipv4/ip_input.c        | 15 +++++++++++----
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 1bcd690b8ae1..f3028028b83e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -321,6 +321,9 @@ enum skb_drop_reason {
 	SKB_DROP_REASON_TCP_FILTER,
 	SKB_DROP_REASON_UDP_CSUM,
 	SKB_DROP_REASON_NETFILTER_DROP,
+	SKB_DROP_REASON_OTHERHOST,
+	SKB_DROP_REASON_IP_CSUM,
+	SKB_DROP_REASON_IP_INHDR,
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index beed7bb2bc0e..d1b0d9690e62 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -17,6 +17,9 @@
 	EM(SKB_DROP_REASON_TCP_FILTER, TCP_FILTER)		\
 	EM(SKB_DROP_REASON_UDP_CSUM, UDP_CSUM)			\
 	EM(SKB_DROP_REASON_NETFILTER_DROP, NETFILTER_DROP)	\
+	EM(SKB_DROP_REASON_OTHERHOST, OTHERHOST)		\
+	EM(SKB_DROP_REASON_IP_CSUM, IP_CSUM)			\
+	EM(SKB_DROP_REASON_IP_INHDR, IP_INHDR)			\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 3a025c011971..ab9bee4bbf0a 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -436,13 +436,18 @@ static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 {
 	const struct iphdr *iph;
+	int drop_reason;
 	u32 len;
 
+	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
+
 	/* When the interface is in promisc. mode, drop all the crap
 	 * that it receives, do not try to analyse it.
 	 */
-	if (skb->pkt_type == PACKET_OTHERHOST)
+	if (skb->pkt_type == PACKET_OTHERHOST) {
+		drop_reason = SKB_DROP_REASON_OTHERHOST;
 		goto drop;
+	}
 
 	__IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len);
 
@@ -478,7 +483,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 		       IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
 		       max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
 
-	if (!pskb_may_pull(skb, iph->ihl*4))
+	if (!pskb_may_pull(skb, iph->ihl * 4))
 		goto inhdr_error;
 
 	iph = ip_hdr(skb);
@@ -490,7 +495,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 	if (skb->len < len) {
 		__IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
 		goto drop;
-	} else if (len < (iph->ihl*4))
+	} else if (len < (iph->ihl * 4))
 		goto inhdr_error;
 
 	/* Our transport medium may have padded the buffer out. Now we know it
@@ -516,11 +521,13 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 	return skb;
 
 csum_error:
+	drop_reason = SKB_DROP_REASON_IP_CSUM;
 	__IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
 inhdr_error:
+	drop_reason = drop_reason ?: SKB_DROP_REASON_IP_INHDR;
 	__IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
 drop:
-	kfree_skb(skb);
+	kfree_skb_reason(skb, drop_reason);
 out:
 	return NULL;
 }
-- 
2.34.1