[Devel] [PATCH 02/47] net: ipv4: use kfree_skb_reason() in ip_rcv_core()

[Nikolay Borisov]

From: Menglong Dong <imagedong at tencent.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 at tencent.com>
Reviewed-by: David Ahern <dsahern at kernel.org>
Signed-off-by: David S. Miller <davem at davemloft.net>
Acked-by: Nikolay Borisov <nborisov at suse.com>
Signed-off-by: Nikolay Borisov <nikolay.borisov at virtuozzo.com>
---
 include/linux/skbuff.h     | 10 ++++++++++
 include/trace/events/skb.h |  3 +++
 net/ipv4/ip_input.c        | 12 ++++++++++--
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 629296082a9b..3a6bc3932a70 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -319,6 +319,16 @@ enum skb_drop_reason {
 	SKB_DROP_REASON_TCP_FILTER,
 	SKB_DROP_REASON_UDP_CSUM,
 	SKB_DROP_REASON_NETFILTER_DROP, /* dropped by netfilter */
+	SKB_DROP_REASON_OTHERHOST,      /* packet don't belong to current
+					 * host (interface is in promisc
+					 * mode)
+					 */
+	SKB_DROP_REASON_IP_CSUM,        /* IP checksum error */
+	SKB_DROP_REASON_IP_INHDR,       /* there is something wrong with
+					 * IP header (see
+					 * IPSTATS_MIB_INHDRERRORS)
+					 */
+
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index beed7bb2bc0e..c11dfc26bf14 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..7be18de32e16 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -436,13 +436,16 @@ 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;
 
 	/* 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);
 
@@ -452,6 +455,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 		goto out;
 	}
 
+	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 		goto inhdr_error;
 
@@ -488,6 +492,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 
 	len = ntohs(iph->tot_len);
 	if (skb->len < len) {
+		drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
 		__IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
 		goto drop;
 	} else if (len < (iph->ihl*4))
@@ -516,11 +521,14 @@ 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:
+	if (drop_reason == SKB_DROP_REASON_NOT_SPECIFIED)
+		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